茶叶与防癌

饮茶与人类肿瘤发生的关系引起了国内外学者的普遍兴趣，许多学者从肿瘤的起动、促发和增殖阶段对茶叶进行了抗突变性试验研究。结果表明所选用的样品包括绿茶、乌龙茶、红茶、花茶以及所提供的茶叶组分茶多酚，儿茶素等对一些广谱的化学致癌物均有明显的抑制作用，而且对一些未明确的化合物的致突变物也有抑制作用。抗肿瘤作用试验研究表明，茶叶及其组分能抑制多种化学致癌物对实验动物（大鼠、小鼠）的致癌作用，包括食道、胃、肠、肺、肝和皮肤等部位，同时也能抑制小鼠体内移植性肿瘤的生长和恶性肿瘤的转移和浸润。流行病学研究方面，各项癌症发生与饮茶之间相关性的结果并不一致，东西方一些流行病学家持不同看法，其原因主要是由于影响人类癌症发生的因素很多，如果对混合因素控制不当，则很难得出正确的结果。为此需开展一些有严格控制的流行病学的研究（特别是前瞻性研究和人群干预试验）来阐明饮茶究竟对人类癌症有无防治作用。     

Epidemiologic studies of antioxidants and cancer in humans.

To assess whether antioxidants may reduce the risk of cancer, we reviewed the epidemiologic literature from 1985 through 1993. We assessed the separate relationships of three antioxidants (carotenoids, vitamin C, and vitamin E) with six sites of cancer (lung, upper aerodigestive tract, uterine cervix, colon, breast, prostate). This review was limited to dietary intake or serum nutrient studies that met a predefined set of methodologic standards. We judged the evidence in support of causal relationships based upon consistency of results across studies, strength of association, and evidence of a dose-response relationship. The data concerning carotenoids and lung cancer risk were most consistent (protection found in 4 of 8 diet studies and 5 of 6 serum studies), with strong associations that tended to follow a dose-response pattern. For lung cancer, there was weaker evidence of protection from vitamin C (2 of 6 diet studies) and vitamin E (3 of 4 serum studies). For upper aerodigestive tract cancers (oral cavity, pharynx, or larynx), there was evidence of a protective effect of carotenoids (3 of 4 diet studies) and vitamin C (4 of 5 diet studies). For cancer of the uterine cervix, we found suggestive evidence of protection from vitamin C (4 of 5 diet studies) and perhaps carotenoids (2 of 5 diet studies). For cancers of the colon, breast, and prostate, the current data do not support a protective effect of antioxidants. More definite conclusions about the benefits of antioxidants in cancer prevention will be derived from on-going intervention trials.     

Occupational lung cancer. A comparison between humans and experimental animals

Many epidemiological and experimental studies have suggested that the respiratory tract is one of the most sensitive organs to environmental carcinogens. Nevertheless there is little evidence to determine the relationship between a specific environmental carcinogen and a cell type of lung cancer, because the cell types of lung cancer and their relative frequencies are highly complex compared with those of other organs and tissues. In the present paper, occupational lung-cancer characteristics, which are the clearest in the relation between cause and effect in human lung cancers, were reviewed in comparison with the results of animal experiments concerned with occupational lung carcinogens. Through accumulation of histopathological examinations of the lung cancer cases, the following relationships between cause and cell type were conjectured: chromium and squamous cell carcinoma; asbestos and adenocarcinoma; nickel and squamous cell carcinoma; beryllium and small cell carcinoma; bis (chloromethyl) ether and small cell carcinoma; mustard gas and squamous cell or small cell carcinoma; vinyl chloride and large cell or adenocarcinoma; radionuclides and small cell carcinoma. The relation pertaining to arsenic, benzotrichloride and tar could not be conjectured because of insufficient cases and information in the histological diagnosis. On the other hand, the carcinogenicity of these substances in occupational exposure has been confirmed by animal experiments administered intratracheally or by inhalation studies under relatively higher concentration. As a result of recent refinements of inhalation study, all-day and life-span exposure to extremely low concentrations, such as microgram/m3 orders, of certain substances has been possible. The characteristics of lung tumors occurring in these animals are rather different from those of human. For example, in mouse, almost all of the malignant lung tumors developed by carcinogens are adenocarcinomas and it is rare to find the squamous cell carcinoma. Moreover, small cell carcinoma and large cell carcinoma have not known to occur in the lungs of rats and mice. Therefore, future research should focus elucidating the specific relationship between cause and cell type of human lung cancer by means of animal experiments on lung cancer that give attention to the specificities of each experimental animal and the origin of the resultant lung tumor.     

Cadmium-induced cancers in animals and in humans

Discovered in the early 1800s, the use of cadmium and various cadmium salts started to become industrially important near the close of the 19th century, rapidly thereafter began to flourish, yet has diminished more recently. Most cadmium used in the United States is a byproduct from the smelting of zinc, lead, or copper ores, and is used to manufacture batteries. Carcinogenic activity of cadmium was discovered first in animals and only subsequently in humans. Cadmium and cadmium compounds have been classified as known human carcinogens by the International Agency for Research on Cancer and the National Toxicology Program based on epidemiologic studies showing a causal association with lung cancer, and possibly prostate cancer, and studies in experimental animals, demonstrating that cadmium causes tumors at multiple tissue sites, by various routes of exposure, and in several species and strains. Epidemiologic studies published since these evaluations suggest that cadmium is also associated with cancers of the breast, kidney, pancreas, and urinary bladder. The basic metal cationic portion of cadmium is responsible for both toxic and carcinogenic activity, and the mechanism of carcinogenicity appears to be multifactorial. Available information about the carcinogenicity of cadmium and cadmium compounds is reviewed, evaluated, and discussed.     

Anthrax in animals and humans in Mongolia

Anthrax is endemic throughout Mongolia, except in the semi-desert and desert areas of the south. The prevalence of anthrax in Mongolia had drastically decreased since the 1950s due to the use of anthrax antiserum and vaccines, but the privatisation of the animal husbandry sector and changes in the structures of the veterinary and medical delivery systems in Mongolia over the last decade have resulted in challenges for disease control. Animal and human anthrax has become an increasing problem since the mid-1990s. Human cutaneous anthrax is common in Mongolia as a result of exposure to infected animals. In this paper, the authors identify potential causes forthe increase of anthrax in Mongolia. The current prevention efforts may not be adequate. Anthrax surveillance and control must be intensified, particularly in areas of high prevalence.     

妊娠期妇女检测弓形虫感染的临床研究

目的了解上海市弓形虫检测方法和试剂盒使用情况,分析孕妇弓形虫感染状况,为本市弓形虫病的监测防治提供依据。方法收集2003—2010年上海市孕妇弓形虫感染筛查的方法和结果资料,分析孕妇弓形虫感染筛查情况。结果2003—2010年全市30家医疗单位开展了孕妇弓形虫感染筛查检测工作,共检测717 391人次,抗体总阳性比例为1.46%,其中IgG和IgM阳性比例分别为2.46%(1.48%~4.96%)和0.83%(0.38%~1.48%)。IgM单项阳性和IgG、IgM双项阳性占41.74%。春、夏季节弓形虫抗体阳性比例高于秋、冬季节;不同性质和等级的医疗单位弓形虫抗体阳性检出比例不等。上海市应用较多的弓形虫抗体检测方法为酶联免疫吸附试验和化学发光法,且对弓形虫IgG和IgM抗体阳性检出比例不同;进口检测试剂盒筛检弓形虫IgM抗体阳性比例较高,而国产检测试剂盒筛检弓形虫IgG抗体阳性比例较高。结论上海市2003—2010年孕妇弓形虫抗体水平与以往调查结果接近,IgM抗体阳性比例较高,应引起重视。各医疗单位要建立相应的质量控制体系,选用质量稳定可靠的检测试剂盒,避免引起漏诊和误诊。     

Anthrax--continuous threat to humans and animals

Gram-positive, spore-forming, aerobic bacterium Bacillus anthracis is an etiological agent of anthrax a disease very dangerous to humans and all warm-blooded animals. The spore forms are markedly resistant to unfavourable environmental extremes of heat, cold, desiccation, chemicals, irradiation etc. The vegetative forms characterised virulence factors: the antiphagocytic poly-gamma-D-polipeptide capsule and three proteins, edema factor (EF), lethal factor (LF) and protective antigen (PA). Anthrax is mainly transmitted from animals to man through food of animal origin, animal products and contamination of the environment with B. anthracis and its spores. There are three types of this disease: cutaneous, intestinal and inhalation anthrax. Research on anthrax as a biological weapon began more then 80 years ago. Depending on the target chosen and the scale of the attack the anthrax spores may by used to contaminate of foodstuffs or liquids and water. The aerosolised release of anthrax spore can cause illness with a high fatality rate.     

Tea consumption and epithelial ovarian cancer risk: a systematic review of observational studies

Ovarian cancer is the seventh most common type of cancer in the United States and is often not diagnosed until late stages. Thus, identifying potential risk factors and prevention strategies is particularly important. This systematic review analyzes existing evidence on the association between tea consumption and epithelial ovarian cancer risk in human observational studies. PubMed was searched through September 30, 2010 for eligible articles; 16 articles met the inclusion criteria for this systematic review. Five studies found overall tea intake to be associated with a decreased epithelial ovarian cancer risk, 1 found a borderline decreased risk, 9 found no association, and 1 found a borderline increased risk. Overall, it does not appear that tea consumption increases risk of ovarian cancer, but there is insufficient evidence at this point to conclude that it is protective against ovarian cancer. Many of the studies included in this review had important limitations, especially related to the lack of detailed data collected on tea consumption. Further research is needed and should focus on more detailed assessment of type of tea consumed, frequency, and duration of tea intake. Future studies should also explore potential differences in the association between tea intake and ovarian cancer risk among subpopulations.     

Toxinotype V Clostridium difficile in humans and food animals

Clostridium difficile is a recognized pathogen in neonatal pigs and may contribute to enteritis in calves. Toxinotype V strains have been rare causes of human C. difficile-associated disease (CDAD). We examined toxinotype V in human disease, the genetic relationship of animal and human toxinotype V strains, and in vitro toxin production of these strains. From 2001 through 2006, 8 (1.3%) of 620 patient isolates were identified as toxinotype V; before 2001, 7 (<0.02%) of approximately 6,000 isolates were identified as toxinotype V. Six (46.2%) of 13 case-patients for whom information was available had community-associated CDAD. Molecular characterization showed a high degree of similarity between human and animal toxinotype V isolates; all contained a 39-bp tcdC deletion and most produced binary toxin. Further study is needed to understand the epidemiology of CDAD caused by toxinotype V C. difficile, including the potential of foodborne transmission to humans.     

Borna disease virus infection in animals and humans.

The geographic distribution and host range of Borna disease (BD), a fatal neurologic disease of horses and sheep, are larger than previously thought. The etiologic agent, Borna disease virus (BDV), has been identified as an enveloped nonsegmented negative-strand RNA virus with unique properties of replication. Data indicate a high degree of genetic stability of BDV in its natural host, the horse. Studies in the Lewis rat have shown that BDV replication does not directly influence vital functions; rather, the disease is caused by a virus-induced T-cell mediated immune reaction. Because antibodies reactive with BDV have been found in the sera of patients with neuropsychiatric disorders, this review examines the possible link between BDV and such disorders. Seroepidemiologic and cerebrospinal fluid investigations of psychiatric patients suggest a causal role of BDV infection in human psychiatric disorders. In diagnostically unselected psychiatric patients, the distribution of psychiatric disorders was found to be similar in BDV seropositive and seronegative patients. In addition, BDV-seropositive neurologic patients became ill with lymphocytic meningoencephalitis. In contrast to others, we found no evidence is reported for BDV RNA, BDV antigens, or infectious B DV in peripheral blood cells of psychiatric patients.     

Cancer chemoprevention by supplemental carotenoids in animals and humans

Experiments were carried out in mice demonstrating that dietary carotenoids (beta-carotene or canthaxanthin), starting before cancer initiation and continuing throughout the experiment, have a protective effect against indirect skin carcinogenesis induced by benzo[a]pyrene +/- UVA and breast cancer induced by 8-methoxypsoralen + UVA. Experiments in rats demonstrated that carotenoids also prevent the direct gastric carcinogenesis induced by N-methyl-N'-nitro-nitroso-guanidine. Recently, prevention by beta-carotene against colon cancer induced in mice by dimethylhydrazine, another indirect carcinogen, was confirmed by others. The prospects for carotenoid intervention with humans were based on their antitumorigenic effect, which is quite independent of pro-vitamin A activity, their lack of toxicity even after prolonged administration, and their immunostimulating activity. These facts helped to build up a rationale predicting that any epithelial cancer, after radical surgery, can be chemoprevented with supplemental carotenoids. Thus, it is expected that the remaining initiated epithelial tissue will be protected by quenching oxygen radical formation, against the onset of a second primary malignancy. This type of prevention can be envisaged in organs like the lung, urinary bladder, breast, stomach, and colon-rectum. At present, human intervention protocols with a randomized drug/placebo method are underway under the supervision of the Centro Tumori of Pavia to chemoprevent with beta-carotene second primary lung or bladder cancer after radical surgery. Preliminary observations regarding findings in humans without randomization (1980-1988) in Pavia are also reported here. This consisted of chemoprevention with beta-carotene plus canthaxanthin against recurrence of different epithelial malignancies after radical treatment (surgery +/- chemoradiotherapy). None of the 11 cases recruited, on the basis of radical nature of treatment and patient adherence, have shown any recurrence beyond their expected disease-free intervals.     

Blastocystis subtypes detected in humans and animals from Colombia

Blastocystis is a common enteric protist colonizing probably more than 1 billion people along with a large variety of non-human hosts. This protist has been linked to symptoms and diseases such as abdominal pain, constipation, diarrhea, flatulence and irritable bowel syndrome (IBS). Remarkable genetic diversity has been observed, leading to the subdivision of the genus into multiple subtypes (ST), some of which are exclusively found in non-human hosts. The aim of this study was to determine the distribution of Blastocystis STs in different Colombian hosts. We obtained fecal samples positive for Blastocystis by microscopy from 277 humans, 52 birds, and 117 mammals (25 cattle, 40 opossums, 40 dogs, 10 rats and 2 howler monkeys). The samples were submitted to DNA extraction, PCR and sequencing using primers targeting the small subunit rRNA gene, and ST identification was performed according to DNA barcoding. We observed the occurrence of ST1 (34%) and ST2 (23%) and lower proportions of STs 3 (11.4%), 4 (0.8%), 6 (19.8%) and 8 (10.5%). Domesticated mammals shared the same STs as those usually seen in humans (ST1, ST2, ST3), while birds and marsupials had STs, which are usually rare in humans (ST6, ST8). Further studies implementing high-resolution molecular markers are necessary to understand the phylodynamics of Blastocystis transmission and the role of this stramenopile in health and disease in Colombian populations, and to expand on the phylogeographic differences observed so far with a view to exploring and understanding host–parasite co-evolution.     

Partitioning of benzene in blood: influence of hemoglobin type in humans and animals

Earlier studies have shown that air/blood partition coefficients (PCs) for many volatile organic chemicals (VOCs) are much higher in rat blood than in human blood. It has been suggested that the discrepancy could be attributed to the fact that hemoglobin (Hb) in rat blood exists in a quasi-crystalline form of hydrophobicity greater than that of normal human Hb (HbA) and thus has a higher carrying capacity for VOCs. In the present study, we used benzene as a prototypic VOC to examine its relative partitioning into human and animal blood. Additionally, we sought to ascertain whether the water-insoluble form of hemoglobin (HbS) found in subjects with homozygous sickle cell (SC) disease has a greater VOC-carrying capacity than does HbA blood. At a low-O(2) tension, HbS switches to water-insoluble polymers, which physically deforms the red blood cells (RBCs) to the sickle shape. We equilibrated HbA, HbS, Hartley guinea pig, CD1 mouse, and rat (F-344, Wistar, and Sprague-Dawley) blood and their respective fractions with benzene vapor (80 or 400 ppm) for 3 hr at 37 degrees C in air-tight vials. We introduced benzene vapor into the vial head space that contained air or respiratory mixtures of venous-type (low-O(2)) or arterial-type (high-O(2)) gases. The blood measurements included the PC, Hb, partial pressures of O(2)(pO(2)) and CO(2)(pCO(2), pH, and percentage of SCs. The benzene concentration had no effect on these parameters, and the high- and low-O(2) gas mixtures produced the expected changes in pO(2), pCO(2), and pH. At equilibrium, the low-O(2) HbS blood had approximately 85% SCs compared with roughly 15% with air or high-O(2) gas. PCs for rat and mouse blood were about 100% higher than those for human and guinea pig blood, but the PC for deoxygenated HbS blood was only slightly higher than that for HbA or oxygenated HbS blood. Benzene showed higher affinities for RBCs in the deoxygenated HbS, rat, and mouse blood and higher affinity for plasma in the guinea pig blood. There was no evidence of disproportionate partitioning of benzene into oxygenated HbS or into HbA blood forms. These data suggest that the water solubility of Hb alone appears to have little effect on the VOC-carrying capacity of blood and that the influence of species is large in comparison. These latter differences in partitioning may depend on the number of hydrophobic sites on the surface of the plasma/heme proteins and thus be unique to the species.     

Drugs and cancer in humans

Some classes of drugs have been shown to be definitely carcinogenic in humans, while others are under suspicion because of experimental evidence of animal carcinogenesis or mutagenesis. Among the drugs discussed are the use of estrogen in menopause, alkylating agents used in cancer therapy, cyclophosphamide, and oral contraceptives. While little definite information has been accumulated to show that certain drugs may be cancer potentiators, this lack of data should not lead to complacency in the further investigation of the interrelation of drugs and cancer in humans.     

汉坦病毒在温州市人与动物间的流行情况

目的通过对肾综合征出血热（HFRS）监测分析,掌握温州市HFRS的流行规律,为制定HFRS防制措施提供依据。方法采用描述流行病学方法对温州市1981-2008年HFRS人间疫情进行分析;用鼠笼捕捉小动物调查宿主动物种群构成,采用间接免疫荧光法检测小动物肺中的汉坦病毒（HV）抗原,用PCR进行基因分型。结果 1981-2008年全市共发病383例,平均发病率为0.20/10万,死亡13例,病死率为3.39%。全市10个县（市、区）均有发病,尤以瑞安市发病最多,占总病例数的53.78%。发病呈明显的季节性,冬季（11月至翌年1月）为流行高峰,占总病例数的41.25%。病例以20～50岁人群为主,占发病总数的74.76%。宿主动物监测发现野外捕获率7.16%,室内捕获率7.88%。野外以北社鼠为优势鼠种,其次为黄毛鼠;室内以褐家鼠为优势鼠种,其次为黄胸鼠。检测422份小动物肺,HV抗原阳性9份,阳性率为2.13%。提取HV抗原阳性鼠肺组织中的病毒RNA,基因分型全部为汉城病毒（SEOV）。结论调查结果提示应采取加强监测、防鼠灭鼠、疫苗接种等综合防控措施,以有效预防HFRS的流行。