Retinal growth and cell addition during embryogenesis in the teleost, Haplochromis burtoni.

Neurogenesis of the developing embryonic retina is described for the African cichlid fish, Haplochromis burtoni, from 4 days post fertilization until all cell phenotypes are generated (day 7). Cell addition and differentiation both begin at the same absolute location which later becomes the central retina. As observed in most other vertebrates, cones and ganglion cells differentiate first, followed by amacrine and bipolar cells. Rod photoreceptors, which are added late, differentiate last. Changes in retinal thickness, retinal stretching, cell size, and cell density were measured during development. From day 4 through 7, there is an increase in retinal thickness largely due to the expansion of the inner plexiform layer (IPL) and outer nuclear layer (ONL). The inner nuclear layer (INL) decreases in thickness and there is a transient decrease in the density of cells in the scleral portion of the INL. Cells increase in size in the ganglion cell layer (GCL) and the vitread INL, decrease in size in the sclerad INL, and remain the same in the ONL. Changes in the density of the cell layers were observed: the density of ONL cells increased, the density of GCL cells decreased, and INL cells increased then decreased. From day 4 to day 6, eye growth is entirely due to cell addition because no retinal stretching was observed in the ONL or the horizontal layer. During this same developmental period, the pattern and rate of neurogenesis were measured in the differentiated portion of the retina by means of 3H-thymidine labeling. A small number of cell divisions within the differentiated INL precede the onset of cell divisions in the ONL. The number of 3H-thymidine labeled cells within the INL increases at a low rate consistent with an asymmetric pattern of cell division characteristic of stem cells. In contrast, cell divisions in the ONL increase exponentially, consistent with a symmetric pattern of cell division characteristic of progenitor cells. Double-label experiments (3H-thymidine and a rod specific opsin antibody) show that some of the symmetrically dividing cells in the ONL express the rod specific opsin within 2 days, suggesting that these dividing cells are rod progenitors. Although we do not hae conclusive evidence, these developmental processes support the hypothesis that stem cells within the INL could be the source of rod precursors in the embryonic teleost retina.     

血清骨唾液酸蛋白的生物变异性研究

目的　骨唾液酸蛋白（Ｂｏｎｅ ｓｉａｌｏｐｒｏｔｅｉｎ,简称ＢＳＰ）是由成骨细胞分泌的一种非胶原蛋白质,反映骨转换和骨形成的指标。最近研究认为：血清ＢＳＰ浓度可反映破骨细胞活性和骨吸收过程,也可能是一个骨吸收指标。本实验测定了血清ＢＳＰ在人体内的生物变异性。方法　采用ＲＩＡ 法测定了２９０例不同性别和年龄的正常人血清ＢＳＰ的正常值,血清ＢＳＰ的天－天变异性及２４ ｈ 生物周期。　结果　在儿童组血清ＢＳＰ正常水平明显高于成人组,其最高值在新生儿期和青春期。绝经后妇女其血清浓度比绝经前妇女水平明显升高（Ｐ＜ ０．０５）。血清ＢＳＰ在每天同一时间的波动范围在 ７．３％ 至１７．７％ （平均１１．７％ ）。２４ ｈ 内有一个明显的生物周期性变化,表现为峰值在凌晨４～８ 时,然后逐渐下降直到午后１４时为最低。其生物周期的最大波幅为±２０％ ,（平均血浓度为１０．５ ｎｇ／ｍ ｌ）。结论　血清ＢＳＰ反映了骨转换的生理变化与年龄有明显相关性,其血清水平２４ ｈ 内有一个明显的生物周期,而天与天之间变异性较小。     

精液分析现状：对《亚洲男性学杂志》出版的陆金春等所著的“中国118 家实验室精液分析状况的调查”一文的评论

陆金春等[1]所著的"中国118家实验室精液分析状况的调查"一文主要回顾了当前在中国采用的精液分析方法.     

Clinimetric quality of the fire fighting simulation test as part of the Dutch fire fighters Workers' Health Surveillance

Background  

Clinimetric data for the fire fighting simulation test (FFST), a new test proposed for the Workers' Health Surveillance (WHS) of Dutch fire fighters, were evaluated.     

Underutilization of the current clinical capacity to provide buprenorphine treatment for opioid use disorders within the Veterans Health Administration

Background: Opioid use disorder (OUD) is a critical concern among US veterans. The Veterans Health Administration (VHA) recommends buprenorphine as a first-line treatment for OUD; however, only 35% of veterans with an OUD currently receive medication treatment. Practical barriers, including the capacity of providers to prescribe, may affect delivery of buprenorphine. We examined the current state of buprenorphine treatment within the VHA. Methods: National VHA administrative databases were queried to identify all providers credentialed to prescribe buprenorphine as of January 2018. Data were extracted on providers’ prescribing capacity (30, 100, or 275 patients concurrently) and number of patients who received buprenorphine in the prior 180?days. Results: A total of 1458 VHA providers were credentialed to prescribe buprenorphine. Forty-three percent of providers had not prescribed buprenorphine to any VHA patients in the past 180?days. Of those that prescribed to at least 1 patient, providers still prescribed to fewer patients than their capacity, regardless of their patient panel size (30, 100, or 275), prescribing to 18.5 patients on average. Conclusions: VHA providers are prescribing buprenorphine below their capacity. A multipronged approach to increase the number of credentialed providers and address barriers to prescribing is needed to ensure that veterans get effective treatment for OUD.     

Comparison of Environmental Tobacco Smoke (ETS) Concentrations Generated by an Electrically Heated Cigarette Smoking System and a Conventional Cigarette

Smoking conventional lit-end cigarettes results in exposure of nonsmokers to potentially harmful cigarette smoke constituents present in environmental tobacco smoke (ETS) generated by sidestream smoke emissions and exhaled mainstream smoke. ETS constituent concentrations generated by a conventional lit-end cigarette and a newly developed electrically heated cigarette smoking system (EHCSS) that produces only mainstream smoke and no sidestream smoke emissions were investigated in simulated “office” and “hospitality” environments with different levels of baseline indoor air quality. Smoking the EHCSS (International Organisation for Standardization yields: 5 mg tar, 0.3 mg nicotine, and 0.6 mg carbon monoxide) in simulated indoor environments resulted in significant reductions in ETS constituent concentrations compared to when smoking a representative lit-end cigarette (Marlboro: 6 mg tar, 0.5 mg nicotine, and 7 mg carbon monoxide). In direct comparisons, 24 of 29 measured smoke constituents (83%) showed mean reductions of greater than 90%, and 5 smoke constituents (17%) showed mean reductions between 80% and 90%. Gas–vapor phase ETS markers (nicotine and 3-ethenylpyridine) were reduced by an average of 97% (range 94–99%). Total respirable suspended particles, determined by online particle measurements and as gravimetric respirable suspended particles, were reduced by 90% (range 82–100%). The mean and standard deviation of the reduction of all constituents was 94?±?4%, indicating that smoking the new EHCSS in simulated “office” and “hospitality” indoor environments resulted in substantial reductions of ETS constituents in indoor air.     

Determination of three carcinogenic aromatic amines in urine of smokers and nonsmokers

Aromatic amines (arylamines) such as o-toluidine, 2-aminonaphthalene, and 4-aminobiphenyl occur in the environment and are constituents of tobacco smoke. Human exposure to these aromatic amines has long been associated with an elevated risk of bladder cancer. A validated, specific, and sensitive method for measuring o-toluidine, 2-aminonaphthalene, and 4-aminobiphenyl in cigarette smokers and nonsmokers was developed. The method uses acid hydrolysis of the arylamine conjugates in urine, extraction with n-hexane, derivatization with pentafluoropropionic anhydride, and subsequent analysis with gas chromatography combined with mass spectrometry using negative ion chemical ionization. The limits of detection were 4 ng/L for o-toluidine and 1 ng/L for 2-aminonaphthalene and 4-aminobiphenyl. Smokers (N = 10) excreted significantly higher amounts of o-toluidine (204 versus 104 ng/24 h), 2-aminonaphthalene (20.8 versus 10.7 ng/24 h), and 4-aminobiphenyl (15.3 versus 9.6 ng/24 h) than nonsmokers (N = 10). Urinary arylamine excretion in smokers was associated with the extent of smoking as assessed by daily cigarette consumption, urinary excretion of nicotine equivalents (nicotine plus its five major metabolites), cotinine in saliva, and carbon monoxide in exhaled breath. All nonsmokers investigated had quantifiable amounts of o-toluidine, 2-aminonaphthalene, and 4-aminobiphenyl in their urine, confirming that other environmental sources of exposure to these compounds also occur. In conclusion, the analytical method is suitable for measuring short-term exposure to arylamines in urine of non-occupationally exposed smokers and nonsmokers.     

Phenotypic library-based microbial source tracking methods: efficacy in the California collaborative study

As part of a larger microbial source tracking (MST) study, several laboratories used library-based, phenotypic subtyping techniques to analyse fecal samples from known sources (human, sewage, cattle, dogs and gulls) and blinded water samples that were contaminated with the fecal sources. The methods used included antibiotic resistance analysis (ARA) of fecal streptococci, enterococci, fecal coliforms and E. coli; multiple antibiotic resistance (MAR) and Kirby-Bauer antibiotic susceptibility testing of E. coli; and carbon source utilization for fecal streptococci and E. coli. Libraries comprising phenotypic patterns of indicator bacteria isolated from known fecal sources were used to predict the sources of isolates from water samples that had been seeded with fecal material from the same sources as those used to create the libraries. The accuracy of fecal source identification in the water samples was assessed both with and without a cut-off termed the minimum detectable percentage (MDP). The libraries (approximately 300 isolates) were not large enough to avoid the artefact of source-independent grouping, but some important conclusions could still be drawn. Use of a MDP decreased the percentage of false-positive source identifications, and had little effect on the high percentage of true-positives in the most accurate libraries. In general, the methods were more prone to false-positive than to false-negative errors. The most accurate method, with a true-positive rate of 100% and a false-positive rate of 39% when analysed with a MDP, was ARA of fecal streptococci. The internal accuracy of the libraries did not correlate with the accuracy of source prediction in water samples, showing that one should not rely solely on parameters such as the average rate of correct classification of a library to indicate its predictive capabilities.     

The development of an intervention programme to reduce whole-body vibration exposure at work induced by a change in behaviour: a study protocol

Background  

Whole body vibration (WBV) exposure at work is common and studies found evidence that this exposure might cause low back pain (LBP). A recent review concluded there is a lack of evidence of effective strategies to reduce WBV exposure. Most research in this field is focussed on the technical implications, although changing behaviour towards WBV exposure might be promising as well. Therefore, we developed an intervention programme to reduce WBV exposure in a population of drivers with the emphasis on a change in behaviour of driver and employer. The hypothesis is that an effective reduction in WBV exposure, in time, will lead to a reduction in LBP as WBV exposure is a proxy for an increased risk of LBP.