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The Gary Null Show is here to inform you on the best news in health, healing, the environment.   How adding green tea extract to prepared foods may reduce the risk for norovirus In study, edible coating made with tea extract killed the virus and bacteria Ohio State University, July 22, 2020   Infusing prepared foods with an edible coating that contains green tea extract may lower consumers' chances of catching the highly contagious norovirus by eating contaminated food, new research suggests. Norovirus, which causes vomiting and diarrhea, sickens an estimated 48 million people in the United States every year and causes about 3,000 deaths. It's transmitted from person to person and through consumption of contaminated water and food. Lots of things we consume contain what are known in the industry as edible films: They can enhance appearance, like wax that makes apples shiny; hold contents together, like plastic drug capsules; and prevent contents from seeping together by, for example, being placed between a prepared pie crust and the filling. "In many cases, an edible film is in a product, but you are not aware of it," said Melvin Pascall, professor of food science and technology at The Ohio State University and senior study author. "We don't have to put that on the label since the material is edible. That's another way in which we use packaging - and the consumer doesn't have to know." Some edible films are also enriched with antimicrobial agents that can kill or slow the growth of organisms that cause illness, such as E. coli and mold. In this new study led by Pascall, adding green tea extract to a film-forming substance created a safe-to-eat barrier that killed norovirus as well as two types of bacteria. While most antimicrobial packaging advances to date have emphasized fighting bacteria, this finding holds promise for a newer area of research into the concept of using edible film to kill a virus, Pascall said. "Norovirus is a tough virus to work with - it is a non-enveloped virus, which is the type more resistant to sanitizers and antimicrobial agents," he said. "However, because it has public health concerns and has been implicated in a number of foodborne outbreaks, we wanted to look at the effects of green tea extract on norovirus." The study is published in the International Journal of Food Science. Pascall and his team created the films with a base substance called chitosan, a sugar found in the exoskeleton of shellfish. Chitosan is marketed as a weight-loss supplement and used in agricultural and medicinal applications, and has been studied extensively as a safe and readily available compound for edible film development. Previous studies have suggested that chitosan has antimicrobial properties. But norovirus might exceed its bug-fighting abilities: In this study, the researchers found that chitosan by itself did not kill the virus. To test the effects of green tea extract, the researchers dissolved it alone in water and added it to a chitosan-based liquid solution and dried film. Several different concentrations of the extract showed effectiveness against norovirus cells, with the highest level tested in this study killing them all in a day. "We had tested the chitosan by itself and it didn't show much antimicrobial activity against the virus," Pascall said. "But when we added the green tea extract to chitosan, we saw that the film had antiviral properties - so we concluded the antiviral properties were coming from the green tea extract." The scientists introduced at least 1 million virus cells to the solution and dried films. Those containing green tea extract lowered the presence of virus cells within three hours. The films with the highest concentration of green tea extract reduced norovirus to undetectable levels by 24 hours after the exposure. Though norovirus was the focus of this work, the researchers also found that green tea extract lowered E. coli K12 and listeria innocua, surrogates for bacteria that also cause foodborne illness, to undetectable levels within 24 hours. This study didn't identify how the killing happens - typically an antimicrobial agent disables organisms in ways that cause them to die or render them unable to reproduce. The researchers used mouse norovirus cells because human norovirus cells don't grow well in a lab setting. There is still a lot of work to do before green tea extract-infused films are ready to enter the market. A tricky part of adding natural substances to edible packaging is ensuring that enough is used to deliver the microbe-killing effect without changing the taste or smell of the food. "A higher concentration of a natural antimicrobial might cause a large drop in the target organism, but at the same time it defeats the purpose of the food by adding an objectionable taste or odor," Pascall said. "There is also the impact of the natural compound on the material itself - it may cause the film to become too brittle or sticky. These are things food scientists have to consider when using antimicrobial agents, especially those from natural sources." It's also too soon to tell which kinds of food would be the best candidates for antiviral edible films made with green tea extract. It depends on whether the food would be exposed to heat, moisture or acidic conditions, for example. There is also a chance another natural substance could do an even better job - Pascall is conducting similar studies with other extracts.       The brain-boosting potential of tart cherry juice University of Delaware, July 21, 2020   A recent study by scientists from the University of Delaware (UD) has found that drinking cherry juice has beneficial effects on memory. Published in the journal Food & Nutrition, it demonstrated that drinking Montmorency tart cherry juice every day for 12 weeks improved cognitive function in adults aged 65 to 80. Tart cherry juice supplementation can improve cognitive performance in older adults Lead author Chai Sheau Ching and colleagues had previously observed the beneficial effects of tart cherry antioxidants, such as melanin, melatonin and anthocyanin, on high blood pressure and cholesterol. In particular, the team found that drinking juice made from Montmorency tart cherries, the most common cherries in the U.S., helped reduce systolic blood pressure, fight inflammation and neutralize the harmful effects of oxidative stress. Based on these earlier findings, the team speculated that the antioxidants in tart cherries could also exert neuroprotective effects on the brain and improve cognitive abilities in older adults. To test their hypothesis, the team asked 37 adults, aged between 65 and 80, to drink either 16 ounces of Montmorency tart cherry juice or a placebo drink of the same amount every day – one in the morning and one in the evening – for 12 weeks. The team also asked the participants to maintain their diet and record their food consumption for the duration of the trial. None of the participants had prior diagnoses of medical conditions like diabetes, heart disease, stroke, cancer and neurological disorders at the time of the trial. Neither were they taking medications that might affect their cognitive abilities. To see whether or not the cherry juice had any effect on the participant's cognitive abilities, the team had each participant answer a series of questionnaires and tests before and after the trial period. At the end of the experiment, the researchers found that the participants in the tart cherry group scored higher in the tests that measured subjective memory, episodic visual memory and spatial memory than the participants in the placebo group. Compared with their pre-trial test results, the tart cherry group also experienced a four percent reduction in their movement time – the time it takes to complete a task – in the post-trial cognitive tests. In addition, the tart cherry group had a 23 percent reduction in errors in episodic visual memory. In both the pre- and post-trial cognitive tests, the participants in the tart cherry group scored significantly higher than those in the placebo group. These findings suggest that the antioxidants in tart cherries are behind the juice's beneficial effects on cognition. Chai hopes that future studies can shed more light on the molecular mechanisms underlying the cognitive-enhancing effects of Montmorency tart cherries. Cognitive health and aging Commenting on their findings, Chai noted that cognitive health plays a key role in determining the quality of life of older adults. According to recent reports by the World Health Organization, about 50 million people around the globe suffer from some form of dementia. And every year, 10 million cases are added to this figure. (Related: Adding more dietary choline can cut back the risk of dementia.) Dementia is a major cause of disability and dependency among older adults. Despite the fact that dementia is not a natural part of aging, its symptoms, including forgetfulness and difficulty communicating, are usually felt later in life. Fortunately, an emerging body of evidence suggests that proper diet and nutrition can reduce the risk of dementia and neurodegenerative diseases in old age. For instance, people can incorporate Montmorency tart cherry juice into a well-balanced diet to enhance their brain performance.     Study suggests benefit for vitamin C in endometriosis Zhejiang University (China), July 20, 2020   According to news reporting originating in Hangzhou, People's Republic of China, research stated, “Endometriosis is a common disease in females that seriously affects quality of life. The principal pathological process of endometriosis is pelvic inflammation, and local and peripheral fibrosis.” The news reporters obtained a quote from the research from Zhejiang University, “Treatment of endometriosis requires both pharmacological and surgical approaches. Vitamin C can scavenge oxygen free radicals and thus accelerate repair of damaged endometrium. This aim of this study was to investigate whether vitamin C can reduce fibrosis in endometriotic lesions. After establishing a rat model of endometriosis, vitamin C solution (vitamin C group) or physiological saline solution (control group) was injected into the abdominal cavity. We compared the indices of fibrotic endometriotic lesions between the two groups. The volume of endometriotic lesions and degree of fibrosis observed in rats within the vitamin C group was significantly reduced compared with those observed in the control group. Immunohistochemistry showed that transforming growth factor-beta 1 (TGF-beta 1), connective tissue growth factor (CTGF), alpha-SMA, and collagen type I staining in lesions of the vitamin C group was significantly less than that observed in lesions from the control group (P < 0.05). Quantitative, real-time PCR (RT-PCR) determined that relative mRNA expression levels of TGF-beta 1, CTGF, alpha-SMA, and collagen type I in lesions obtained from the vitamin C group were significantly lower than levels measured in lesions obtained from animals in the control group. Vitamin C can reduce the volume of endometriotic lesions and inhibit fibrosis of lesions in rats.” According to the news reporters, the research concluded: “This study supports the use of vitamin C in the treatment of endometriosis.”     Cannabis Appears Safe And Effective At Treating Chronic Pain, New Clinical Trial Shows University of California Irvine, July 21, 2020   Cannabis appears to be a safe and potentially effective treatment for the chronic pain that afflicts people with sickle cell disease, according to a new clinical trial co-led by University of California, Irvine researcher Kalpna Gupta and Dr. Donald Abrams of UC San Francisco. The findings appear in JAMA Network Open. “These trial results show that vaporized cannabis appears to be generally safe,” said Gupta, a professor of medicine on the faculty of UCI's Center for the Study of Cannabis. “They also suggest that sickle cell patients may be able to mitigate their pain with cannabis – and that cannabis might help society address the public health crisis related to opioids. Of course, we still need larger studies with more participants to give us a better picture of how cannabis could benefit people with chronic pain.” Opioids are currently the primary treatment for the chronic and acute pain caused by sickle cell disease. But the rise in opioid-associated deaths has prompted physicians to prescribe them less frequently, leaving sickle cell patients with fewer options. The double-blind, placebo-controlled, randomized trial was the first to employ such gold-standard methods to assess cannabis's potential for pain alleviation in people with sickle cell disease. The cannabis used in the trial was obtained from the National Institute on Drug Abuse – part of the National Institutes of Health – and contained equal parts of THC and CBD. “Pain causes many people to turn to cannabis and is, in fact, the top reason that people cite for seeking cannabis from dispensaries,” Gupta said. “We don't know if all forms of cannabis products will have a similar effect on chronic pain. Vaporized cannabis, which we employed, may be safer than other forms because lower amounts reach the body's circulation. This trial opens the door for testing different forms of medical cannabis to treat chronic pain.”   Twenty-three patients with sickle cell disease-related pain completed the trial, inhaling vaporized cannabis or a vaporized placebo during two five-day inpatient sessions that were separated by at least 30 days. This allowed them to act as their own control group. Researchers assessed participants' pain levels throughout the treatment period and found that the effectiveness of cannabis appeared to increase over time. As the five-day study period progressed, subjects reported that pain interfered less and less with activities, including walking and sleeping, and there was a statistically significant drop in how much pain affected their mood. Although pain levels were generally lower in patients given cannabis than in those given the placebo, the difference was not statistically significant.     Bad eating habits may cause blindness, warn researchers University of Bristol (UK), July 20, 2020   There's no denying that eating junk food is bad for your health, as it's linked to obesity and an increased risk of various health problems. A report in the Annals of Internal Medicine even found that a diet full of junk food could eventually cause vision loss. Researchers from the University of Bristol in the U.K. looked at a particular case involving a teenager who was a “fussy eater” and didn't eat anything except junk food. Several years of following an unhealthy diet eventually made him lose his eyesight. This unusual and shocking case highlights the dangers of an unhealthy diet. It can cause obesity and increase your risk of developing heart disease and cancer. The report also found that consuming junk food may “permanently damage the nervous system, particularly vision.” The adverse effects of poor eating habits The teen first experienced problems when he was 14, and he consulted a doctor due to symptoms like tiredness. His blood tests then revealed that he had anemia. Since the teenager had B12 deficiency, he was also treated with injections of the vitamin. His physician then told him to improve his eating habits. When the teenager turned 15, he reported more issues like hearing loss and vision problems. His physicians were baffled because the results from an MRI and eye exam were all normal. (Related: Cut the junk: Eating junk food can give you food allergies.) After two years, the teenager's vision worsened. At 17, an eye test revealed that his vision was 20/200 in both eyes: The threshold for being considered “legally blind” in America. Results from other tests revealed that the teenager also suffered damage to his optic nerve, the bundle of nerve fibers that connects the back of the eye to the brain. Despite being told to improve his eating habits when he was 14, the teenager still had a vitamin B12 deficiency. Worse, he also had low levels of copper, selenium and vitamin D. The physicians were alarmed at these deficiencies. After questioning the teenager, they found out that he didn't like eating “certain textures of food.” Since elementary school, the patient followed a limited diet that consisted only of foods such as: Chips Fries Processed ham slices Sausage White bread Once the doctors ruled out other possible causes for his vision loss, the patient was diagnosed with nutritional optic neuropathy or damage to the optic nerve because of nutritional deficiencies. The researchers noted that “[purely] dietary causes are rare in developed countries.” Most of the time, nutritional optic neuropathy is caused by alcohol abuse, drugs, poor diet or the malabsorption of food. Early detection can potentially reverse vision loss due to nutritional optic neuropathy. But unfortunately for the teenager, by the time his condition was diagnosed, his vision loss was permanent. Dr. Denize Atan, a senior lecturer in ophthalmology at Bristol Medical School and a co-author of the study, explained that eyeglasses wouldn't help the patient's vision since any damage to the optic nerve can't be addressed with lenses. To prevent his vision loss from worsening, physicians prescribed the teenager nutritional supplements. Avoidant-restrictive food intake disorder and mental health The doctors involved in the patient's case also referred him to mental health services for an eating disorder because there seemed to be more to his unusual diet. Unlike kids who were simply picky eaters, the teenager's diet “was very restrictive and caused multiple nutritional deficiencies.” They believe that the teenager might have a condition called “avoidant-restrictive food intake disorder” (ARFID). This relatively new diagnosis, previously called “selective eating disorder,” may cause a lack of interest in food or avoidance of foods with certain colors, textures or other factors without links to the patient's body weight or shape. Other symptoms of ARFID include: Abdominal pain, cold intolerance, constipation, lethargy or excess energy Dramatic restriction in amount or types of food eaten Dramatic weight loss Eating only certain textures of food Eating a limited range of preferred foods that becomes narrower over time or picky eating that worsens with time Fears of choking or vomiting Inconsistent and vague gastrointestinal issues, like an upset stomach, around mealtimes with no known cause No body image disturbance or fear of weight gain ARFID often manifests in childhood, and patients tend to have a normal body mass index (BMI) like the teenaged boy, concluded the study authors.   Chronic inflammation alters the evolution of cells in the colon, study finds Researchers have compared diseased colon with healthy tissue to better understand how inflammatory bowel disease (IBD) is linked to an increased risk of colorectal cancers Cambridge University and Wellcome Sanger Institute, July 21, 2020   In a new study, researchers have compared diseased colon with healthy tissue to better understand how inflammatory bowel disease (IBD) is linked to an increased risk of colorectal cancers, at a molecular level. Researchers from the Wellcome Sanger Institute and Cambridge University Hospitals found that the rate of DNA change within colon cells affected by IBD was more than double that in healthy colon, increasing the likelihood of these cells gaining DNA changes that could lead to cancer. The study, published today (21 July) in Cell, also found that chronic inflammation associated with IBD disrupts the tissue structure of the colon, allowing cells to expand over an abnormally wide area. The results provide valuable insights into evolution within the body, and the development of IBD and colorectal cancers. IBD primarily refers to ulcerative colitis and Crohn's disease, chronic illnesses characterised by inflammation of the digestive system that can be highly disruptive to a patient's quality of life. Between 1990 and 2017, the number of IBD cases worldwide rose from 3.7 million to 6.8 million*. The causes of the disease remain unknown, though it is thought that inflammation occurs as a result of an inappropriate immune response to gut microbes. People suffering from IBD are at an increased risk of developing gastrointestinal cancers compared to the general population. Patients will undergo regular surveillance for this and may, in some cases, opt to undergo surgery to remove their entire colon in order to mitigate this risk. In this new study, clinicians at Addenbrooke's Hospital, Cambridge provided colon tissue samples donated by 46 IBD patients, along with anonymised information about their medical history and treatment. Researchers at the Wellcome Sanger Institute then used laser-capture microdissection to cut out 446 individual crypts, the tiny cavities that make up colon tissue, so they could be whole-genome sequenced. These sequences were analysed to discover the mutation rate in the tissue, the genetic relationship between crypts and any genes that were more mutated than normal. They were then compared to sequences from 412 crypts from 41 individuals without IBD, so that the effects of chronic inflammation on the DNA sequence could be observed. The team found that there were more than twice as many DNA changes in the diseased tissue than in normal, and the longer the duration of the disease, the greater this excess. The study also uncovered evidence of an evolutionary process whereby mutations in particular genes are under positive selection. Some of these positively-selected mutations were enriched in genes associated with colorectal cancers, shedding light on the link between IBD and certain cancers. The researchers also detected evidence of positive selection of mutations in genes associated with immune system regulation in the gut and the ability of the cells to fend off the bacteria resident in the colon. Sigurgeir Olafsson, first author of the study from the Wellcome Sanger Institute, said: "How our bodies continue to evolve during our lifetime is a fundamental part of our biology. It has been fascinating to study the effect of a chronic disease on this process and uncover evidence that changes in the genetic sequence of gut cells could have a direct role in the onset of inflammatory bowel disease." Dr Tim Raine, clinical lead for the inflammatory bowel disease (IBD) service at Addenbrooke's Hospital, Cambridge and Honorary Faculty member at the Wellcome Sanger Institute, said: "Colorectal cancer is one of the main clinical concerns when treating patients with IBD. In this study, we found that normal mutational processes that are operative in us all are accelerated in the IBD affected gut, leading to a more than two-fold increase in the rate at which some gut cells acquire mutations, and this underpins the increased cancer risk in IBD." Dr Peter Campbell, an author on the study from the Wellcome Sanger Institute, said: "The role of somatic mutations in cancer susceptibility has long been appreciated. It is exciting to see the methods that we and others have used to understand cancers now being applied to other common diseases. These approaches have given us unique insights into the effects of inflammatory bowel disease on the DNA sequence of the inflamed tissue." A previously unexplained observation in IBD is that repeated flares of inflammation tend to affect the same patch of tissue, suggesting some permanent alterations to the colon. These findings highlight genetic mutations as a possible explanation, with some positively-selected mutations in immune regulation genes occurring in the same regions of the bowel affected by chronic inflammation. Dr Carl Anderson, lead author of the study from the Wellcome Sanger Institute, said: "We know that DNA changes contribute to the development of cancer, but their role in common non-cancerous diseases like inflammatory bowel disease (IBD) has not been extensively studied. Our study revealed that somatic changes in the DNA sequence of the cells that line our gut may contribute to the development of IBD. I strongly believe that studying somatic mutations in all common diseases, not just IBD and cancers, has the potential to provide novel insights into disease biology and highlight potential drug targets."   Studies suggest a fasting diet could boost breast cancer therapy A USC-led team of international scientists found that a one-two punch of a fasting diet with hormone therapy may enhance the effects of breast cancer treatment  University of Southern California, July 22, 2020   A USC-led team of scientists has found that a fasting-mimicking diet combined with hormone therapy has the potential to help treat breast cancer, according to newly published animal studies and small clinical trials in humans. In studies on mice and in two small breast cancer clinical trials, researchers at USC and the IFOM Cancer Institute in Milan -- in collaboration with the University of Genova -- found that the fasting-mimicking diet reduces blood insulin, insulin-like growth factor 1 (IGF1) and leptin. In mice, these effects appear to increase the power of the cancer hormone drugs tamoxifen and fulvestrant and delay any resistance to them. The results from 36 women treated with the hormone therapy and fasting-mimicking diet are promising, but researchers say it is still too early to determine whether the effects will be confirmed in large-scale clinical trials. The research was published in the journal Nature. "Our new study suggests that a fasting-mimicking diet together with endocrine therapy for breast cancer has the potential to not only shrink tumors but also reverse resistant tumors in mice," said Valter Longo, the study's co-senior author and the director of the Longevity Institute at the USC Leonard Davis School of Gerontology and professor of biological sciences at the USC Dornsife College of Letters, Arts and Sciences. "We have data that for the first time suggests that a fasting-mimicking diet works by changing at least three different factors: IGF1, leptin and insulin." The researchers say the two small clinical trials are feasibility studies that showed promising results, but they are in no way conclusive. They believe the results support further clinical studies of a fasting-mimicking diet used in combination with endocrine therapy in hormone-receptor-positive breast cancer. The scientists also contributed to a recent clinical study of 129 breast cancer patients conducted with the University of Leiden. The results, published last month in Nature Communications, appeared to show increased efficacy of chemotherapy in patients receiving a combination of chemotherapy and a fasting-mimicking diet. In the two new small clinical trials -- one of which was directed by the study co-corresponding author Alessio Nencioni -- patients with hormone-receptor-positive breast cancer receiving estrogen therapy along with cycles of a fasting-mimicking diet seemed to experience metabolic changes similar to those observed in mice. These changes included a reduction in insulin, leptin and IGF1 levels, with the last two remaining low for extended periods. In mice, these long-lasting effects are associated with long-term anti-cancer activity, so further studies in humans is needed. "Some patients followed monthly cycles of the fasting-mimicking diet for almost two years without any problems, suggesting that it is a well-tolerated intervention," Nencioni said. "We hope this means that this nutritional program that mimics fasting could one day represent a weapon to better fight cancer in patients receiving hormone therapy without serious side effects." "The results in mice are very promising. And the early clinical results show potential as well, but now we need to see it work in a 300- to 400-patient trial," Longo explained. The data also suggest that in mice, the fasting-mimicking diet appears to prevent tamoxifen-induced endometrial hyperplasia, a condition in which the endometrium (or the lining of the uterus) becomes abnormally thick. The study authors believe this potential use of the fasting diet should be explored further, given the prevalence of this side effect of tamoxifen and the limited options for preventing it. Approximately 80% of all breast cancers express estrogen and/or progesterone receptors. The most common forms of hormone therapy for these breast cancers work by blocking hormones from attaching to receptors on cancer cells or by decreasing the body's hormone production. Endocrine therapy is frequently effective in these hormone-receptor-positive tumors, but the long-term benefits are often hindered by treatment resistance. Several clinical trials, including one at USC on breast cancer and prostate patients, are now investigating the effects of the fasting-mimicking diets in combination with different cancer-fighting drugs. "I like to call it the nontoxic wildcard for cancer treatment," Longo said. "These clinical studies we have just published -- together with the many animal studies published in the past 12 years -- suggest that cycles of the fasting-mimicking diet has the potential to make standard therapy more effective against different cancers, each time by changing a different factor or nutrient important for cancer cell survival."   Scientists identify 10 risk factors for Alzheimer disease Fudan University (China), July 17, 2020   Alzheimer's disease may be preventable by keeping an eye on key factors including weight gain, blood pressure and avoiding stress, experts say. Researchers said many risk factors are modifiable in the fight to prevent dementia, which affects around 850,000 people in the UK, two-thirds of whom have Alzheimer's. Their review of existing studies found 10 risk factors had strong evidence of a link with Alzheimer's, and people could take action to avoid them. These included ensuring good education in early life, keeping the brain active through activities such as reading, and not being overweight or obese in later life. People should also avoid depression, stress, high blood pressure, head trauma and diabetes to reduce their risk, they said. Other factors had weaker links that could be adjusted, including not being obese in midlife, taking exercise, getting enough sleep, including vitamin C in the diet and not smoking. The study, published in the Journal of Neurology, Neurosurgery & Psychiatry, was led by Professor Jin-Tai Yu at Fudan University in China. The researchers gathered 395 studies and came up with a list of factors that could be used by doctors to try to prevent Alzheimer's disease. They said research into preventing dementia should continue but their report offered “clinicians and stakeholders an evidence-based guideline for Alzheimer's disease prevention”. Fiona Carragher, director of research and influencing at the Alzheimer's Society, said: “In recent years, research has suggested that nearly a third of dementia cases may be preventable and this review builds on this idea, specifically in relation to Alzheimer's disease and how certain risk factors, many of which are associated with cardiovascular health, may be within our control. “We need a deeper dive into each of these risk factors to understand how they work together on an individual level and how best to support people to manage them. “This review demonstrates that, while observational studies are useful to help identify potential risk factors, we need to see many more interventional trials to understand what the best approaches are to preventing Alzheimer's disease developing in the first place. “We don't have all the answers yet, but we do know that small steps to improving your physical and mental health can make a big difference, like walking to your local shop for milk instead of jumping in the car.”

病毒是如何感染细胞进行复制的？窗口期和潜伏期有什么不一样？核酸检测的原理是什么？PCR和RT-PCR有什么区别，RT是什么意思？试剂的灵敏度是什么，怎么判断优劣？简而言之，PCR是检测病毒的一种方式，但只能检测双链的DNA，而不能检测单链的RNA，RT就是把RNA反转录成双链的DNA的过程，RTPCR是新冠病毒的核酸检测方法。在检测过程中，由于一开始病毒含量少，技术无法检测到，这叫做潜伏期。而灵敏度较高的试剂盒，可以在更低病毒浓度下检测出病毒。更多知识内容，可扫描以下二维码观看直播回放~

病毒是如何感染细胞进行复制的？窗口期和潜伏期有什么不一样？核酸检测的原理是什么？PCR和RT-PCR有什么区别，RT是什么意思？试剂的灵敏度是什么，怎么判断优劣？简而言之，PCR是检测病毒的一种方式，但只能检测双链的DNA，而不能检测单链的RNA，RT就是把RNA反转录成双链的DNA的过程，RTPCR是新冠病毒的核酸检测方法。在检测过程中，由于一开始病毒含量少，技术无法检测到，这叫做潜伏期。而灵敏度较高的试剂盒，可以在更低病毒浓度下检测出病毒。更多知识内容，可扫描以下二维码观看直播回放~

Neuroendocrine tumors are a heterogeneous group of malignancies with an increasing prevalence. Since there is not much progress in therapy, model systems are urgently needed. We have a CEA424-SV40 TAg transgenic mouse model which develops spontaneous tumors in the antral region of the stomach. In addition, several cell lines derived from the tumor were established. Gene expression analysis of the tumor tissue as well as cell lines revealed neuroendocrine markers. Therefore we further characterized this model with special emphasis on the cells of origin and used it for testing new targeted treatment protocols. To analyze CEA424-SV40 TAg mouse model in more detail, tumor tissue as well as the cell lines derived from the primary tumor were investigated by immunohistochemistry, immunofluorescence, western blot, and ELISA. Antibodies used were directed at SV40 TAg, Ki-67, chromogranin A, chromogranin B, secretin, H+-K+-ATPase, glucagon, and transcription factors NeuroD1 and Nkx2.2. Plasma hormone levels of serotonin and secretin were measured by ELISA. Immunostainings of SV40 TAg and Ki-67 revealed highly proliferative tumors cells. The tumors stained intensively for the neuroendocrine markers chromogranin A, chromogranin B, secretin and glucagon. The tumor tissue as well as the cell lines expressed transcription factors NeuroD and Nkx2.2, which are involved in the differentiation of the neuroendocrine lineage. Hormone levels of serotonin and secretin in the plasma of the transgenic mice were dramatically elevated when compared with normal littermates, thus supporting the neuroendocrine phenotype. As the neuroendocrine phenotype of CEA424-SV40 TAg transgenic mouse was confirmed, molecularly targeted therapies were tested in this model system both in vitro and in vivo. Cell lines were tested for drug sensitivity with mTOR inhibitors (RAD001, NVP-BEZ235), paclitaxel, E2F inhibitor, HSP90 inhibitor, and p53 stabilizer Nutlin-3a. All the drugs tested in vitro could efficiently inhibit cell proliferation in a dose dependent manner. From these drugs the mTOR inhibitor RAD001 was chosen for the in vivo experiment. Daily feeding of 10 mg/kg RAD001 inhibited the tumor development and prolonged the survival time of the CEA424-SV40 TAg transgenic mice dramatically. The effects of the RAD001 treatment on tumor cells were achieved mainly through inactivating mTOR-p70S6K and mTOR-4EBP1 signaling as proven by western blot and immunohistochemistry. Still, some cells must develop escape mechanisms, since the tumor tend to grow. To gain a better understanding of the T antigen transforming mechanisms as well as the possible escape mechanisms, some efforts were made on the tumor originating cells in the CEA424-SV40 Tag transgenic mouse model. Possible candidates for these tumor originating cells in the stomach are the newly described epithelial as well as mesenchymal stem cells. In a first attempt, the expression feature of epithelial and mesenchymal stem cell markers were analyzed. Established cell lines as well as tumor tissue from the tumor bearing mice were investigated by reverse transcription PCR (RT-PCR), immunohistochemistry, immunofluorescence, western blot, and microarray analysis. From several markers analyzed, the tumor cell lines showed a high expression level of the potential epithelial stem cell marker Bmi1 in RT-PCR and cDNA expression array. This could be further substantiated by western-blotting and immunostaining. Consequently, Bmi1 message could also be found in the growing tumors both in mRNA and protein levels. Experiments using siRNA to knock down the SV40-TAg expression showed that the Bmi1 expression went down in the cell lines thus showing the interrelationship. On the other hand, the mesenchymal stem cell marker Etv1 was also found to be expressed in the tumor tissue and cell lines derived from the tumor. More interestingly, Etv1 expression level was up-regulated over the time course of the tumor development. From these, an Etv1 positive mesenchymal cell could be a possible candidate for transformation. Since the CEA-promoter used for the generation of the T-antigen transgenic animals contains Etv1 binding sites, it is tempting to speculate, that this may drive the transcription of the T antigen. In conclusion, our data provide convincing evidence that CEA424-SV40 TAg mice are a clinically relevant model for neuroendocrine tumor. Testing of molecularly targeted therapies both in vitro and in vivo offered promising candidates for further clinical evaluation. Thus, this new model system could be of great value not only for studies on the mechanisms of how SV40 TAg induces neuroendocrine tumors but also for exploring novel targeted therapy in a preclinical setting.

Background and aims: Interleukin 26 (IL-26), a novel IL-10-like cytokine without a murine homologue, is expressed in T helper 1 (Th1) and Th17 cells. Currently, its function in human disease is completely unknown. The aim of this study was to analyse its role in intestinal inflammation.Methods: Expression studies were performed by reverse transcription-PCR (RT-PCR), quantitative PCR, western blot and immunohistochemistry. Signal transduction was analysed by western blot experiments and ELISA. Cell proliferation was measured by MTS (3-(4,5-dimethylthiazol-2-yl)-5-(carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) assay. IL-26 serum levels were determined by an immunoluminometric assay (ILMA).Results: All examined intestinal epithelial cell (IEC) lines express both IL-26 receptor subunits IL-20R1 and IL-10R2. IL-26 activates extracellular signal-related kinase (ERK)-1/2 and stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK) mitogen-activated protein (MAP) kinases, Akt and signal transducers and activators of transcription (STAT) 1/3. IL-26 stimulation increases the mRNA expression of proinflammatory cytokines but decreases cell proliferation. In inflamed colonic lesions of patients with Crohn's disease, an elevated IL-26 mRNA expression was found that correlated highly with the IL-8 and IL-22 expression. Immunohistochemical analysis demonstrated IL-26 protein expression in colonic T cells including Th17 cells expressing the orphan nuclear receptor RORtextgreekgt, with an increased number of colonic IL-26-expressing cells in active Crohn's disease.Conclusion: Intestinal cells express the functional IL-26 receptor complex. IL-26 modulates IEC proliferation and proinflammatory gene expression and its expression is upregulated in active Crohn's disease, indicating a role for this cytokine system in the innate host cell response during intestinal inflammation. For the first time, IL-26 expression is demonstrated in colonic RORtextgreekgt-expressing Th17 cells in situ, supporting a role for this cell type in the pathogenesis of Crohn's disease.

Background: Idiopathic pulmonary fibrosis (IPF) is a fatal interstitial lung disease characterised by accumulation of activated (myo)fibroblasts and excessive extracellular matrix deposition. The enhanced accumulation of (myo)fibroblasts may be attributed, in part, to the process of transforming growth factor textgreekb1 (TGFtextgreekb1)-induced epithelial--mesenchymal transition (EMT), the phenotypic switching of epithelial to fibroblast-like cells. Although alveolar epithelial type II (ATII) cells have been shown to undergo EMT, the precise mediators and mechanisms remain to be resolved. The objective of this study is to investigate the role of SNAI transcription factors in the process of EMT and in IPF.Methods: Using quantitative reverse transcription-PCR (RT-PCR), immunofluorescence, immunohistochemistry, western blotting, as well as gain- and loss-of-function studies and functional assays, the role of SNAI1 and SNAI2 in TGFtextgreekb1-induced EMT in ATII cells in vitro was assessed; and the expression of SNAI transcription factors was analysed in experimental and human IPF in vivo.Results: TGFtextgreekb1 treatment increased the expression and nuclear accumulation of SNAI1 and SNAI2, in concert with induction of EMT in ATII cells. SNAI overexpression was sufficient to induce EMT, and small interfering RNA (siRNA)-mediated SNAI depletion attenuated TGFtextgreekb1-induced ATII cell migration and EMT. SNAI expression was elevated in experimental and human IPF and localised to hyperplastic ATII cells in vivo.Conclusions: The results demonstrate that TGFtextgreekb1-induced EMT in ATII cells is essentially controlled by the expression and nuclear translocation of SNAI transcription factors. Increased SNAI1 and SNAI2 expression in experimental and human IPF in vivo suggests that SNAI-mediated EMT may contribute to the fibroblast pool in idiopathic pulmonary fibrosis.

In situations where well-established approaches such as surgery, radiation therapy and chemotherapy fail to help cancer patients, immunotherapy has the potential to be an effective alternative. Tumour cells can sometimes be distinguished from corresponding normal cells due to their expression of tumour-associated antigens (TAAs), most of which are unaltered self-molecules. These molecules must be presented to the immune system in the context of danger in order to achieve their specific recognition. If dendritic cells (DCs), the most potent professional antigen-presenting cells, are loaded with RNA, they will translate the RNA into protein, process the protein into peptides and present the peptides within MHC molecules (pMHC) on their surface to cytotoxic T-lymphocytes (CTLs) and T-helper cells in a stimulatory manner. These effector cells can, in turn, recognise tumour cells. The goal of these studies was to find optimal conditions for producing a DC-based vaccine for cancer patients using TAAs in the form of RNA. The studies were designed to quantitate RNA transfer into DCs, to determine the intracellular stability of transfected RNA in DCs and to analyse the kinetics of protein expression and the generation of functional pMHC ligands that could activate effector memory CTLs. Simultaneous activation of CTLs with specificities for different antigens minimises the potential for tumour escape through immune selection of tumour variants showing loss of individual antigens. Thus, generation of multiplex pMHC ligands for CTLs may improve clinical efficiency. On the other hand, peptide competition for MHC molecules within the DC may limit pMHC ligand generation. This central immunological question was addressed by comparing DCs loaded with total cellular tumour RNA, amplified total cellular tumour mRNA and pools of defined single-species tumour-antigen cRNAs versus individual single-species tumour-antigen cRNAs for their capacity to display various pMHC ligands and activate CTLs of corresponding specificities. Experiments performed with RNA encoding the enhanced green fluorescence protein (EGFP), a reporter protein, showed that the highest efficiency of RNA transfection into DCs was achieved with electroporation, reaching levels of 90% positive cells. The fact that mature DCs expressed more EGFP than immature DCs suggests that this stage of DC maturation will be optimal for vaccine development. Importantly, electroporation and RNA transfer did not alter the expression of antigen-presenting and co-stimulatory molecules on the surface of DCs. The melanoma model was chosen for extensive analyses because its characterisation at the cellular and molecular levels has made it a very informative model for understanding cancer immunity. In addition to total cellular melanoma RNA, single-species cRNAs were used encoding the melanoma-associated antigens, tyrosinase, Melan-A and CDK4-R24C. Antigen presentation was detected with the help of effector memory CTL clones specific for each of these antigens. The CTL stimulatory capacity of RNA-transfected DCs was higher if they were allowed one day to recuperate from electroporation and to produce pMHC complexes. Tyrosinase cRNA dose-finding showed that more RNA would indeed result in higher stimulatory capacities of transfected DCs. Kinetics of tyrosinase cRNA degradation, similar to kinetics of EGFP cRNA degradation, revealed that the amount of transfected RNA rapidly decreased inside the DCs within 1.5 hr after electroporation. The smallest decrease was observed with the highest amount of RNA applied in electroporation. The kinetics of RNA degradation and protein half-life will be important parameters to consider in defining the right time-frame for T-cell activation by engineered DCs. When reverse transcription PCR (RT-PCR) was performed with total cellular melanoma RNA samples to generate amplified mRNA, the Melan-A, tyrosinase and CDK4/CDK4-R24C message was amplified 62-fold, 24-fold and 2-fold, respectively. These differences likely reflect variations in the expression levels of the corresponding antigen message in melanoma cells from which the RNA was isolated. Approximately 17240-fold more CDK4-R24C message, at least 500-fold more tyrosinase message and at least 480-fold more Melan-A message was found in single-species cRNAs when the same masses of single-species cRNA and amplified melanoma mRNA samples were compared. This explained why electroporation of single-species cRNAs into DCs yielded the highest DC stimulatory capacities. Combinations of tyrosinase, Melan-A and CDK4-R24C cRNAs were studied for their capacity to induce satisfactory levels of T-cell stimulation when presented by DCs. Here it was demonstrated that antigen competition was not a critical factor, since CTL responses to pooled RNAs were not inhibited even though competition for MHC class I molecules may have occurred within the DCs. DCs also developed CTL stimulatory capacities, but at much lower levels, using amplified melanoma mRNA. Two antigen-specific CTL clones displayed higher reactivities upon exposure to pMHC produced naturally by RNA-transfected DCs than to synthetic peptides pulsed onto DCs. In one case, this could be explained by a post-translational modification of the peptide, which normally occurs within cells. Since this particular modification was not represented in the synthetic peptide, which was chosen from the protein sequence, the synthetic peptide was not well recognised. This demonstrated that the use of RNA technology eliminates the need to know the correct sequences of immunogenic peptides. Thereby, DCs are better than scientists at choosing antigens and their epitopes for presentation to T-cells. These data provided a better understanding of antigen presentation by DCs based on the use of RNA, giving insight into antigen competition and paving the way for the use of pooled RNAs of defined species for the development of a multiplex vaccine. They also allowed a precise protocol for efficient T-cell activation to be defined. Further experiments will demonstrate whether quantitative differences detected in antigen presentation between DCs loaded with total cellular tumour RNA and amplified total cellular tumour mRNA versus single-species tumour-antigen cRNAs have an impact on de novo T-cell priming in vitro and in vivo.