Culturing and bioassay testing of Daphnia magna using Elendt M4, Elendt M7, and COMBO media.

A performance-based, tiered approach was used to evaluate survival, growth, and reproduction of Daphnia magna in three selected synthetic media: Elendt M4, Elendt M7, and COMBO. Both Elendt M4 and Elendt M7 are high-hardness media currently recommended for Organization for Economic Cooperation and Development (OECD) testing. COMBO is a softer medium similar in total hardness to natural water found in the environment. Tier I consistent of an acclimation phase; Tier II involved a 21-day evaluation of survival, growth, and reproduction; and Tier III used each medium in a 21-day chronic study using a reference toxicant, 3,4-dichloroaniline (3,4-DCA). The evaluation of the performance of each medium was based on acceptance criteria similar to those used by the U.S. Environmental Protection Agency and the European Commission. Tests were run concurrently at three laboratories to assess interlaboratory variability. Daphnids were acclimated to the media for less than 1 month. Daphnid performance in all media exceeded the European Economic Community (EEC) validity criteria; however, reproductive performance and growth were significantly greater in the Elendt media than in COMBO. 3,4-DCA exerted more toxicity to daphnids in COMBO medium [no-observed-effect concentration (NOEC), <3.1microg/liter] compared with those in the Elendt media (NOEC, 相似文献   

Population structure and evolutionary origins of Microsporum canis, M. ferrugineum and M. audouinii.

The recurrent evolutionary emergence of asexual lineages within sexual zoo- and anthropophilic dermatophyte species living in animal-frequented soil is likely to be triggered by changes in ecological niche, i.e., shifts of host animal. Subsequent adaptation to the new host species is noted. Sometimes geographic isolation or intrinsic host factors like human race may also play a role in speciation. In the present study, we elaborate concepts of speciation in dermatophytes using the Microsporum canis complex as an example. The group consists of a cluster of phylogenetically closely related anamorphs: the anthropophilic taxa Microsporum audouinii and M. ferrugineum, and the zoophilic taxon M. canis. The sexually reproducing species underlying this complex is Arthroderma otae. The study is done by an analysis of the population structure of about 200 isolates and using intergenic spacers, non-translated regions of genes as well as hypervariable microsatellite markers that are known to evolve at high mutation rates. The results suggest that sympatric speciation took place already during the period where mating ability was maintained and thus that strictly clonal fungal species emerged in Africa and led to genetically isolated clonal species elsewhere.     

Blood pressure and the T174M and M235T polymorphisms of the angiotensinogen gene.

PURPOSE: The angiotensinogen gene (AGT), which encodes the precursor of the vasoactive hormone angiotensin II, has been reported to be associated with hypertension in Caucasian and Japanese populations. We examined the relationship between two common molecular variants of AGT, T174M and M235T and blood pressure in two cohorts from the Anqing region of China. Cohort I (N = 794) consisted of families ascertained by either hypertensive or hypotensive siblings; and Cohort II (N = 761) represented a collection of randomly selected families. METHODS: Blood pressure was measured according to standard protocols, and information on age, sex, body mass index, alcohol consumption, and cigarette smoking was collected by trained interviewers using standardized questionnaires. The association of AGT genotypes and blood pressure was examined in multivariate linear regression models, with adjustment for potential intrafamilial correlations. The respective T and M allele frequencies for T174M were 0.93 and 0.07, and 0.80 and 0.20 for M235T among the parents for randomly selected families. All the analyses were conducted after exclusion of individuals currently under antihypertensive medication. RESULTS: In the pooled analysis of the two cohorts, neither the T174M nor the M235T polymorphism was significantly associated with variations of blood pressure assuming a recessive (T174M: p = 0.73 and 0.61; M235T: p = 0.99 and 0.24; for SBP and DBP), dominant (T174M: p = 0.54 and 0.72; M235T: p = 0.79 and 0.12; for SBP and DBP), or additive (T174M: p = 0.52 and 0.67, M235T: p = 0.91 and 0.11; for SBP and DBP) model. Likewise, no statistically significant association was detected when the two cohorts were analyzed separately. The logistic regression analysis of hypertension also failed to reveal any association with these markers. CONCLUSIONS: In summary, our analyses suggest that the molecular variants of AGT may not be associated with variations of blood pressure in this rural Chinese population.     

M4M chat rooms: individual socialization and sexual autonomy

This paper uses data from twenty-one online and in-person qualitative interviews to examine the meaning and use of chat rooms located on men for men (M4M) websites from the perspectives of men seeking men on the Internet. This research is inspired by recent public health and social sciences literature on gay websites and chat rooms. The data indicate that these online sites help expedite learning about sex and sexuality and, for men who are shy or geographically isolated, to interact with metropolitan gay communities. There is, however, a measure of stigma associated with use of these chat rooms, particularly by men who are older or in coupled relationships. Using these data, the paper argues that M4M chat rooms play a vital role in fostering the sexual autonomy of many men who frequent these venues and that sociologists should devote more study to the complexity of online social interaction.     

Improving the evaluation of model fit in confirmatory factor analysis: A commentary on Gundy, C.M., Fayers, P.M., Groenvold, M., Petersen, M. Aa., Scott, N.W., Sprangers, M.A.J., Velikov, G., Aaronson, N.K. (2011). Comparing higher-order models for the EORTC QLQ-C30. Quality of Life Research, doi:10.1007/s11136-011-0082-6

This article is a brief commentary in response to "Gundy, C.M., Fayers, P.M., Groenvold, M., Petersen, M. Aa., Scott, N.W., Sprangers, M.A.J., Velikov, G., Aaronson, N.K. (2011). Comparing higher-order models for the EORTC QLQ-C30. Quality of Life Research, doi: 10.1007/s11136-011-0082-6 ." The commentary argues that approximate goodness-of-fit indexes cannot be used to salvage confirmatory factor models rejected by the Chi-square test of exact fit. Instead, rigorous diagnostic procedures should be used to identify and resolve the particular sources of model misspecification.     

Evaluation of brodifacoum against T. indica, M. hurrianae and R. rattus.

Brodifacoum was evaluated in the laboratory against the two gerbils, Tatera indica and Meriones hurrianae and the house rat, Rattus rattus. The acute oral LD50 for these rodents was found to be 0.10 mg/kg, 0.083 mg/kg and 0.77 mg/kg respectively. Feeding tests with 0.002% and 0.005% brodifacoum produced a 100% mortality after a 3-day feeding period in the gerbils and after a 4-day period in R. rattus. The anticoagulant is toxic at both the concentrations to all three species but is less palatable in comparison to plain baits. Results of this laboratory evaluation indicates that 0.002% brodifacoum-treated bait can be effectively used against T. indica, M. hurrianae and R. rattus.     

QMHC interview: Robert M. Heyssel, M.D.. Interview by Marie E. Sinioris

In 1991, US News and World Report rated The Johns Hopkins Hospital as the best hospital in the country. Its survey of physicians revealed that Hopkins is perceived to be at or near the top in 13 of the 15 specialties studied. For the past three years, The Johns Hopkins Health System has been taking a hard look at the nonclinical aspects of health care delivery. Surveys of patients, physicians, nurses, and employees have revealed a litany of frustrations that can interfere with the delivery of excellent care. To focus on these issues, Hopkins launched a systemwide total quality management (TQM) process in 1989. Dr Robert M. Heyssel and other senior executives provided leadership that has been essential to the initiation and maintenance of the TQM process at The Johns Hopkins Health System. TQM has been associated with impressive results in several areas. In addition, more than 500 people have received intensive training in the use of statistical tools and teamwork. An additional 900 people are scheduled to attend this program in the future.     

Is natural infection with M. tuberculosis protective against cancer?

In order to investigate the effect of natural infection with M. tuberculosis on cancer incidence, a case-control study was undertaken on 108 recently diagnosed cancer cases (all sites) and 317 controls. After removal of cancer cases or controls considered immunoincompetent (25% and 17% respectively), the remaining subjects were tested by intradermal injection of tuberculin (5 I.U.). Results were compared separately for each sex. It was observed that the proportion of tuberculin-negative subjects was higher in cancer patients than in controls within each sex (males 31.3% vs 20.1%, females: 59.2% vs 37.3%) the difference in females being statistically significant ( p < 0.02). Odds ratio for negative tuberculin test was 1.80 and 2.44 for males and females respectively. The results are discussed on the basis of cell-mediated immunity produced by infection with M. tuberculosis and its relations with tumor growth.     

QMHC interview: Alan C. Brewster, M.D.. Interview by Marie E. Sinioris

Information systems for severity-of-illness measurement and case mix adjustment are at the cutting edge of health care quality technology. The rapid rise of these systems in the past decade has paralleled hospital needs for better data on clinical processes and the burgeoning need among health care customers for better data on clinical outcomes and the relative performance of providers. The dual nature of the demand is fueling what promises to be a decade of growth for the developers of severity systems. To get a better handle on the status of these software-based tools, QMHC interviewed Alan C. Brewster, M.D., Vice Chairman and cofounder of MediQual Systems, Inc., and a principal developer of the widely used MedisGroups system.     

Some similarities between the work of M.C. Escher and plastic surgery

At first sight there would appear to be no similarities between the work of the Dutch graphic artist M.C. Escher and plastic surgery. M.C. Escher was a gifted graphic artist who produced a large collection of work. Most of his fame is due to the works that play with symmetry, space and infinity and leave the viewer astounded. However, how Escher came to produce these works is less well known. A theory which he developed himself formed the basis of the regular plane division. It later became apparent that this theory almost completely agreed with the mathematics of plane division. Two movements (isometries) defined in mathematics, translation and rotation, are equivalent to two techniques for transferring local skin in plastic surgery, namely, advancement and transposition. Escher's performance on the plane of a sheet of paper and a plastic surgeon's performance on the plane of the skin, therefore have a similar mathematical background. Escher has visualised these mathematical rules in an unusual and artistic manner, whereas plastic surgeons apply these rules in the grace of an elastic and healing nature.     

M.A. turned M.D. heads HEW's quality bureau.

Helen Smits, M.D., one of the few women to head a federal health bureaucracy, looks for ways to improve the quality, while reducing the cost, of health care.     

结核分枝杆菌Rv3914抗原的克隆表达与纯化

目的构建结核分枝杆菌Rv3914蛋白的重组质粒,并在大肠埃希菌中表达及纯化,为结核病血清学诊断提供候选抗原。方法用PCR方法从结核分枝杆菌H37Rv基因组中扩增Rv3914基因片段,插入到pET-28b(+)载体中,构建pET28b-Rv3914重组质粒,转化大肠埃希菌E.coli BL21plysS(DE3),经IPTG诱导表达后,应用Ni-NTA亲和柱纯化重组蛋白。结果 PCR扩增出Rv3914基因序列,重组质粒经测序并经BLAST分析后发现无点突变。pET28b-Rv3914重组质粒在大肠埃希菌E.coli BL21plysS(DE3)中主要以可溶性形式表达,重组蛋白占细胞蛋白总表达量的30%以上,经Ni-NTA柱纯化后,得到纯度超过90%、相对分子质量约为14.7×103的目的蛋白质。结论高纯度结核分枝杆菌Rv3914重组蛋白的获得为研究结核互补特异性抗原组合在结核病血清诊断中的价值奠定了基础。     

Mycobacterium Species Related to M. leprae and M. lepromatosis from Cows with Bovine Nodular Thelitis

Bovine nodular thelitis is a granulomatous dermatitis associated with infection with acid-fast bacteria. To identify the mycobacterium responsible for this infection, we conducted phylogenetic investigations based on partial sequencing of 6 genes. These bacteria were identified as an undescribed Mycobacterium species that was phylogenetically related to M. leprae and M. lepromatosis.     

Novel Mycobacterium tuberculosis Complex Pathogen, M. mungi

Seven outbreaks involving increasing numbers of banded mongoose troops and high death rates have been documented. We identified a Mycobacterium tuberculosis complex pathogen, M. mungi sp. nov., as the causative agent among banded mongooses that live near humans in Chobe District, Botswana. Host spectrum and transmission dynamics remain unknown.     

M.D. Anderson, Ball cancer centers focus on research, care, prevention

The folks at M.D. Anderson Cancer Center, Houston, win first place in this category with their traditionally excellent report. The Cancer Center at Ball Memorial Hospital, Muncie, Ind., receives the second place award with a report that uses unusual design elements to "shatter the myths" about cancer research.     

Rebecca J. Cook, Bernard M. Dickens, and Mahmoud F. Fathalla, Reproductive Health and Human Rights: Integrating Medicine, Ethics and the Law

Rebecca J. Cook, Bernard M. Dickens, and Mahmoud F. Fathalla, Reproductive Health and Human Rights: Integrating Medicine, Ethics and the Law     

临床/口腔医学博士专业学位研究生科研训练现状分析

通过对北京大学医学部2013年入学的临床/口腔医学博士专业学位研究生进行问卷调查,从对科研训练的认识、用于科研训练的时间、科研训练的类型形式、指导情况以及科研训练的效果和遇到的困难等方面进行分析。建议以临床训练为主的同时注重科研能力训练,针对临床问题选题,强调进行临床科学研究,渗透“转化医学”理念,推广“科研脱产”方式,加强导师指导,确保科研训练的有序进展。     

Differentiation of Mycobacterium chelonei from M. fortuitum by ciprofloxacin susceptibility.

Seventy-five strains of Mycobacterium fortuitum were inhibited by 3.0 mg/l ciprofloxacin but 36 strains of M. chelonei were resistant. The results correlated well with those obtained by the nitratase test. The ciprofloxacin sensitivity test is a useful supplement to the tests used to identify these two species.     

Experimental crosses between Mepraia gajardoi and M. spinolai and hybrid chromosome analyses reveal the occurrence of several isolation mechanisms

Hematophagous insects of the subfamily Triatominae include several species with a large variety of shapes, behavior and distribution. They have great epidemiological importance since most of them transmit the flagellated protozoan Trypanosoma cruzi, the etiologic agent of Chagas disease. In this subfamily several cases of species hybridization have been reported under experimental and natural conditions. Mepraia is a genus of Triatominae endemic in Chile, responsible for transmitting T. cruzi in the sylvatic cycle. This genus includes three species, M. gajardoi, M. spinolai and M. parapatrica; however, the differentiation of M. parapatrica as a separate species remains controversial considering the possible occurrence of introgression/hybridization processes in some populations of this putative species. Mepraia species show conspicuous wing polymorphism, and it has been proposed that the genes related to wings are linked to the Y chromosome, thus wingless males could not engender winged progeny. In order to determine the degree of reproductive isolation and to assess the wing phenotype in the offspring, we performed experimental crosses between the two most divergent Mepraia species (M. gajardoi and M. spinolai) together with chromosome analyses of hybrid progenies. Although fertile F₁ hybrids were obtained in only one direction of crossing, we verified the existence of different isolation mechanisms between parental species, including hybrid breakdown. The occurrence of winged males in the offspring of wingless parental males suggests that the wing character is not linked to the Y chromosome.     

Genetic characterization of the M RNA segment of Crimean Congo hemorrhagic fever virus strains, China.

We report the genetic characterization of the M RNA segment of Crimean Congo hemorrhagic fever virus (CCHFV). Two CCHFV strains isolated in Xinjiang Province, a region endemic for CCHF in northwestern China, were studied. These strains, designated BA66019 and BA8402, were isolated in 1965 and 1984 from a CCHF patient and Hyalomma ticks, respectively. Viral RNA was extracted from suckling mouse brains infected with these two strains, amplified, and sequenced. The full-length M RNA, consisting of 5.3 kb, was determined for both strains. The coding nucleotide sequences of the two strains differed from each other by 17.5% and from the reference CCHFV strain IbAr10200 by a mean of 22%, suggesting that the genus Nairovirus comprises a group of genetically highly diverse strains.