Relationships between in vivo and in vitro aflatoxin production: reliable prediction of fungal ability to contaminate maize with aflatoxins

Aflatoxins are highly carcinogenic mycotoxins frequently produced by Aspergillus flavus. Contamination of maize with aflatoxins imposes both economic and health burdens in many regions. Identification of the most important etiologic agents of contamination is complicated by mixed infections and varying aflatoxin-producing potential of fungal species and individuals. In order to know the potential importance of an isolate to cause a contamination event, the ability of the isolate to produce aflatoxins on the living host must be determined. Aflatoxin production in vitro (synthetic and natural media) was contrasted with in vivo (viable maize kernels) in order to determine ability of in vitro techniques to predict the relative importance of causal agents to maize contamination events. Several media types and fermentation techniques (aerated, non-aerated, fermentation volume) were compared. There was no correlation between aflatoxin production in viable maize and production in any of the tested liquid fermentation media using any of the fermentation techniques. Isolates that produced aflatoxins on viable maize frequently failed to produce detectable (limit of detection = 1 ppb) aflatoxin concentrations in synthetic media. Aflatoxin production on autoclaved maize kernels was highly correlated with production on viable maize kernels. The results have important implications for researchers seeking to either identify causal agents of contamination events or characterize atoxigenic isolates for biological control.     

武威市2009~2012年流感样病例监测结果分析

目的:分析探讨2009~2012年武威市流行性感冒(简称流感)的流行特征,为流感的防控提供科学依据。方法:收集2009年6月~2012年12月武威市流感样病例及病原学监测资料,分析流感样病例就诊比(ILI%)的变化规律、流感样病例的年龄分布和流感病毒各亚型的变化。结果:2009~2012年,武威市的ILI%分别是1.94%、1.55%、1.12%、1.15%,ILI%高峰分别出现在6月(2009年)、7月(2010年)和10月~次年3月(2011年和2012年)。ILI年龄构成显示病例以15岁以下人群为主。2009~2012年,ILI样本病原学检测阳性率为19.00%;2009年,甲型H1N1为优势毒株,构成比是76.64%,2010年为季节性H3(60.00%)、B型(29.23%)混合流行;2011年主要是甲型H1N1(26.47%)、季节性H3(29.41%)、A未分型(29.41%);2012年为季节性H3(31.78%)、B型(53.49%)混合流行。结论:2009年甲型H1N1流感大流行之后,武威市流感的活动较为平稳,流行优势毒株不断发生变化。     

Childhood leukemia--risk factors and the need for an interdisciplinary research agenda

The International Agency for Research on Cancer (IARC) has classified high as well as low-frequency fields as “possibly carcinogenic to humans” (Group 2B). For high frequency fields the recent assessment is based mainly on weak positive associations described in some epidemiological studies between glioma and acoustic neuroma and the use of mobile and other wireless phones. Also for lowfrequency fields the evidence is based on epidemiological findings revealing a statistic association between childhood leukemia (CL) and low-level magnetic fields. The basic findings are already 10 years old. They have since been supported by further epidemiological studies. However, the knowledge on the main/crucial question of causality has not improved. This fact and in addition the small, but statistically significant increased incidence of CL in the surrounding of German nuclear power plants have motivated the German Office for Radiation Protection (BfS) to work toward a better understanding of the main causes of CL. A long-term strategic research agenda has been developed which builds on an interdisciplinary, international network and aims at clarifying the aetiology of childhood acute lymphoblastic leukemia.     

Compression-induced damage and internal tissue strains are related

Prolonged mechanical loading of soft tissues adjacent to bony prominences can lead to degeneration of muscle tissue, resulting in a condition termed pressure-related deep tissue injury. This type of deep pressure ulcers can develop into a severe wound, associated with problematic healing and a variable prognosis. Limited knowledge of the underlying damage pathways impedes effective preventive strategies and early detection. Traditionally, pressure-induced ischaemia has been thought to be the main aetiological factor for initiating damage. Recent research, however, proposes tissue deformation per se as another candidate for initiating pressure-induced deep tissue injury. In this study, different strain parameters were evaluated on their suitability as a generic predictive indicator for deep tissue injury. With a combined animal-experimental numerical approach, we show that there is a reproducible monotonic increase in damage with increasing maximum shear strain once a strain threshold has been exceeded. This relationship between maximum shear strain and damage seems to reflect an intrinsic muscle property, as it applied across a considerable number of the experiments. This finding confirms that tissue deformation per se is important in the aetiology of deep tissue injury. Using dedicated finite element modeling, a considerable reduction in the inherent biological variation was obtained, leading to the proposal that muscle deformation can prove a generic predictive indicator of damage.     

Role of inflammation in gastrointestinal tract in aetiology and pathogenesis of idiopathic parkinsonism

Idiopathic parkinsonism (IP) is a common disorder, conventionally regarded as neurodegenerative. Its cardinal features, poverty and slowness of movement, muscle rigidity, postural abnormality and a characteristic tremor, are associated with loss of dopaminergic neurones in the substantia nigra of the brain. Genetic factors explain only a minority of cases, and a common toxic environmental insult remains elusive. We propose that IP is a systemic disorder resulting from a ubiquitous peripheral infection, and that only the tip of the iceberg comes to diagnosis. There is evidence for inflammatory/immune activation peripherally and in the brain. We have used statistical modelling to explore links with non-specific and specific systemic markers of inflammation/infection in IP probands, and explore whether their partners and siblings have a frank or pre-presentation parkinsonian state. Critical to this approach is continuous objective measures of the facets of IP. Hypotheses on causality and mechanism are based on the statistical models. There is pathological and clinical evidence for direct involvement of the gastrointestinal tract in IP. The candidacy of Helicobacter pylori infection as a trigger event or driving infection is relatively high. We have found that eliminating infection in late parkinsonism with cachexia, a stage usually considered intractable, can result in a U-turn. However, eradication therapy may not provide a complete solution. Persistence of antibody against cytotoxin-associated antigen (CagA), increases the predicted probability of being labelled as having parkinsonism. Evidence for autoimmunity and immunocompromise is used to build schemes for the natural history. We conclude that current classifications of neuropsychiatric disease may not prove the best with respect to defining sub-clinical disease, prophylaxis or halting progression.     

Maxillary sinusitis in Medieval Chichester,England

Maxillary sinusitis is a common medical complaint, affecting more than 30 million people per year in the United States alone. Very little palaeopathological work on this disease has been carried out, probably because of the enclosed nature of the sinuses in intact skulls and the lack of a suitable method for examination. This study tested the hypothesis that maxillary sinusitis was more common in people with leprosy than in people without it in Medieval England. The prevalence of maxillary sinusitis by age and sex was recorded in 133 individuals, some diagnosed as being leprous, derived from a later Medieval (12th to 17th centuries AD) urban hospital population at Chichester, Sussex, England using both macroscopic and endoscopic methods of examination. Of the 133 individuals with one or both sinuses available for examination, 54.9% (73) had evidence of bone change within the sinuses. There was no difference in prevalence between those with leprosy and those without, although clinical studies suggest that over 50% of lepromatous leprous individuals may develop sinusitis. Comparison with another study on Medieval British sites with a 3.6% prevalence (3 of 83) indicates that the prevalence at Chichester is much greater. The problems with diagnosing sinusitis are addressed and reasons behind the high frequency in this study are discussed. Aetiological factors predisposing to maxillary sinusitis are considered with reference to possible environmental conditions prevailing in the later Medieval period in Britain. © 1995 Wiley-Liss, Inc.     

The aetiology and pathogenesis of human breast cancer

Whilst investigators have clearly shown that non-hereditary factors dominate the aetiology of human breast cancer, they have failed to identify quantitatively important causes, and prospects for prevention remain indeed. However, progress in epidemiological and basic research has taken place during the last few years. Current evidence suggests that breast cancer may be affected by the intra-uterine environment, that exposures during adolescence are particularly important, and that pregnancy has a dual effect on breast cancer risk: an early increase followed by long-term protection. Great variation exists in the structural development of the breast ductal system already in the newborn — and by inference in utero — and a pregnancy induces permanent structural changes in the mammary gland. We suggest that these observations fit into an aetiological model with the following key components: (1) breast cancer risk depends on the number of cells at risk, the susceptibility of individual cells to malignant transformation, and on the degree of cellular proliferation, notably cells which can act as founders of breast cancer; (2) the number of target cells is determined by the hormonal environment mainly early in life, perhaps already in utero; (3) in adult life, hormones which are non-genotoxic, increase breast cancer risk by increasing selective cell proliferation and thus number of target cells and the risk of retention of spontaneous somatic mutations; (4) while a pregnancy stimulates the growth of already malignant cells to malignant transformation (and thereby entails a short-term risk increase) the dominating long-term protection occurs due to permanent structural changes, terminal differentiation and perhaps decreased cell proliferation and carcinogen-binding in combination.