Zytophotometrische Bestimmung des Histon- und Gesamtproteingehalts von Zellen des lymphatischen Gewebes

Résumé L'étude au microscope électronique a révélé la présence de particules B dans le thymus de la souris NZB, adulte et saine. Les particules se forment dans un type de cellule thymique bien défini, la cellule réticulo-épithéliale à vacuoles et naissent par bourgeonnement des membranes plasmatiques limitant les vacuoles. L'élaboration de particules B dans lethymus d'animaux apparemment sains est un fait nouveau dont la signification n'est pas encore connue.

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Summary An electron microscopical study revealed the presence of virus-like particles in the thymus of adult healthy NZB-mice. The particles are found in the vacuoles of reticuloepithelial cells and are elaborated by a budding process from the membranes surrounding the vacuoles. The formation of B-particles in the thymus of apparently healthy animals is a so far unknown fact the significance of which remains to be determined.

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Avec l'aide du Centre National de la Recherche Scientifique et de l'Institut National de la Santé et de la Recherche Médicale, et la collaboration technique dévouée de M^lle J. Patry et de Mr. B. Fontaine.     

Cost-effectiveness of pharmacotherapy to reduce obesity

Aims

Obesity causes a high disease burden in Australia and across the world. We aimed to analyse the cost-effectiveness of weight reduction with pharmacotherapy in Australia, and to assess its potential to reduce the disease burden due to excess body weight.

Methods

We constructed a multi-state life-table based Markov model in Excel in which body weight influences the incidence of stroke, ischemic heart disease, hypertensive heart disease, diabetes mellitus, osteoarthritis, post-menopausal breast cancer, colon cancer, endometrial cancer and kidney cancer. We use data on effectiveness identified from PubMed searches, on mortality from Australian Bureau of Statistics, on disease costs from the Australian Institute of Health and Welfare, and on drug costs from the Department of Health and Ageing. We evaluate 1-year pharmacological interventions with sibutramine and orlistat targeting obese Australian adults free of obesity-related disease. We use a lifetime horizon for costs and health outcomes and a health sector perspective for costs. Incremental Cost-Effectiveness Ratios (ICERs) below A$50 000 per Disability Adjusted Life Year (DALY) averted are considered good value for money.

Results

The ICERs are A$130 000/DALY (95% uncertainty interval [UI] 93 000–180 000) for sibutramine and A$230 000/DALY (170 000–340 000) for orlistat. The interventions reduce the body weight-related disease burden at the population level by 0.2% and 0.1%, respectively. Modest weight loss during the interventions, rapid post-intervention weight regain and low adherence limit the health benefits.

Conclusions

Treatment with sibutramine or orlistat is not cost-effective from an Australian health sector perspective and has a negligible impact on the total body weight-related disease burden.     

Diverse microbial interactions with the basement membrane barrier

During primary contact with susceptible hosts, microorganisms face an array of barriers that thwart their invasion process. Passage through the basement membrane (BM), a 50-100-nm-thick crucial barrier underlying epithelia and endothelia, is a prerequisite for successful host invasion. Such passage allows pathogens to reach nerve endings or blood vessels in the stroma and to facilitate spread to internal organs. During evolution, several pathogens have developed different mechanisms to cross this dense matrix of sheet-like proteins. To breach the BM, some microorganisms have developed independent mechanisms, others hijack host cells that are able to transverse the BM (e.g. leukocytes and dendritic cells) and oncogenic microorganisms might even trigger metastatic processes in epithelial cells to penetrate the underlying BM.     

Zur Differenzierung der Blutbasophilen und Gewebsmastzellen nach dem Reifegrad ihrer Granula

Zusammenfassung Es wird über eine Modifikation der Toluidinblau-pH-Reihe berichtet. Sie gestattet, in Diagrammen Blutmastzellen (basophile Granulozyten) und Gewebsmastzellen näher zu charakterisieren. Die in tieferen pH-Bereichen färbbaren Mastzellengranula werden als stärker polymerisiert bzw. sulfatiert angesehen. So gelingt es, die Mastzellengranula semiquantitativ nach ihrem pH zu differenzieren und damit ihren Reifegrad zu bestimmen. Eine ausführliche Diskussion beschäftigt sich mit der physikalisch-chemischen Begründung dieser Ansicht.

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Differentiation of blood basophils and tissue mast cells according to the maturity of their granulesA new modification of the toluidinblue-pH-scale

Summary A new modified technique of the Toluidin blue pH-scale is described. Characteristic diagrams show the typical appearance of blood basophils and tissue mast cells. The mast cell granules that appear in the lower part of the pH-scale are regarded as strongly polimerised or sulfated. A far reaching discussion deals with the physicochemical proof of this opinon. The modified Toluidin blue pH-scale allows a semiquantitative differentiation of the mast cell granules according to their acid content. Thus their maturity can be determined.

     

The value of conjunctival biopsy in childhood cystinosis

Cystinosis is frequently presented with cystine storage in the cornea and conjunctiva, and the diagnosis can be established by slit-lamp examination. It can also be confirmed by electron microscopy of a conjunctival biopsy. The present paper reports on a 16-month-old boy with Fanconi's syndrome, in whom the slit-lamp examination did not show crystal deposits of cystine in the conjunctiva. The ultrastructural study of the conjunctival biopsy demonstrated polygonal crystals within double membrane-limited organelles located in fibroblasts. Similar crystals were subsequently found in a kidney biopsy. We therefore think that conjunctival biopsy is a valuable diagnostic tool prior to performing renal biopsy, even in cases with negative findings by ophthalmologic examination.     

In search of relevant predictors for marine species distribution modelling using the MarineSPEED benchmark dataset

Aim

Ideally, datasets for species distribution modelling (SDM) contain evenly sampled records covering the entire distribution of the species, confirmed absences and auxiliary ecophysiological data allowing informed decisions on relevant predictors. Unfortunately, these criteria are rarely met for marine organisms for which distributions are too often only scantly characterized and absences generally not recorded. Here, we investigate predictor relevance as a function of modelling algorithms and settings for a global dataset of marine species.

Location

Global marine.

Methods

We selected well‐studied and identifiable species from all major marine taxonomic groups. Distribution records were compiled from public sources (e.g., OBIS, GBIF, Reef Life Survey) and linked to environmental data from Bio‐ORACLE and MARSPEC. Using this dataset, predictor relevance was analysed under different variations of modelling algorithms, numbers of predictor variables, cross‐validation strategies, sampling bias mitigation methods, evaluation methods and ranking methods. SDMs for all combinations of predictors from eight correlation groups were fitted and ranked, from which the top five predictors were selected as the most relevant.

Results

We collected two million distribution records from 514 species across 18 phyla. Mean sea surface temperature and calcite are, respectively, the most relevant and irrelevant predictors. A less clear pattern was derived from the other predictors. The biggest differences in predictor relevance were induced by varying the number of predictors, the modelling algorithm and the sample selection bias correction. The distribution data and associated environmental data are made available through the R package marinespeed and at http://marinespeed.org .

Main conclusions

While temperature is a relevant predictor of global marine species distributions, considerable variation in predictor relevance is linked to the SDM set‐up. We promote the usage of a standardized benchmark dataset (MarineSPEED) for methodological SDM studies.

     

Macroecology meets macroevolution: evolutionary niche dynamics in the seaweed Halimeda

Aim Because of their broad distribution in geographical and ecological dimensions, seaweeds (marine macroalgae) offer great potential as models for marine biogeographical inquiry and exploration of the interface between macroecology and macroevolution. This study aims to characterize evolutionary niche dynamics in the common green seaweed genus Halimeda, use the observed insights to gain understanding of the biogeographical history of the genus and predict habitats that can be targeted for the discovery of species of special biogeographical interest. Location Tropical and subtropical coastal waters. Methods The evolutionary history of the genus is characterized using molecular phylogenetics and relaxed molecular clock analysis. Niche modelling is carried out with maximum entropy techniques and uses macroecological data derived from global satellite imagery. Evolutionary niche dynamics are inferred through application of ancestral character state estimation. Results A nearly comprehensive molecular phylogeny of the genus was inferred from a six‐locus dataset. Macroecological niche models showed that species distribution ranges are considerably smaller than their potential ranges. We show strong phylogenetic signal in various macroecological niche features. Main conclusions The evolution of Halimeda is characterized by conservatism for tropical, nutrient‐depleted habitats, yet one section of the genus managed to invade colder habitats multiple times independently. Niche models indicate that the restricted geographical ranges of Halimeda species are not due to habitat unsuitability, strengthening the case for dispersal limitation. Niche models identified hotspots of habitat suitability of Caribbean species in the eastern Pacific Ocean. We propose that these hotspots be targeted for discovery of new species separated from their Caribbean siblings since the Pliocene rise of the Central American Isthmus.     

Stemming the obesity epidemic: a tantalizing prospect

Objective: Obesity is a growing problem worldwide, but there are no good methods to assess the future course of the epidemic and the potential influence of interventions. We explore the behavior change needed to stop the obesity epidemic in the U.S. Research Methods and Procedures: We modeled the population distribution of BMI as a log‐normal curve of which the mean shifts upward with time due to a positive population energy balance. Interventions that decrease food intake or increase physical activity result in more favorable trends in BMI. Results: The recently observed trend in average BMI implies that the average U.S. adult over‐consumes by ～10 kcal/d. If this trend continues unaltered, obesity prevalence will exceed 40% for men and 45% for women in 2015. To stop the epidemic, it suffices to decrease caloric consumption by ～10 kcal or walk an extra 2 to 3 minutes per day, on average. Discussion: This leads to a paradox: little behavior change seems sufficient to halt the epidemic, but in practice this proves hard to achieve. The obesogenic environment is the likely culprit. Individuals trying to maintain a healthy weight need to be supported by environments that stimulate physical activity and do not encourage over‐consumption. Research should show what measures are effective.