The effects of vasectomy on health

The study of possible adverse effects of vasectomy have been mainly focussed on hormonal balance, spermatogenesis, the induction. of auto-immune reactions and cardiovascular changes including the non-fatal myocardial infarction. The review of literature, including our own work on the immunological sequelae of vasectomy, indicates that there is no health hazard following vasectomy. The presence of antibodies to spermatozoa in some individuals, however, may effect future fertility, if reversal is requested.     

The effects of vasectomy on testicular metabolism in the guinea-pig.

The effects of vasectomy on testicular DNA production were studied in guinea-pigs at 2 weeks and 2 and 6 months after surgery. By 6 months, vasectomy had resulted in lower testicular weight and absolute DNA, RNA and protein contents, although RNA and DNA concentrations/protein were unchanged. Incorporation of thymidine into the testis had decreased by 2 weeks after vasectomy, and continued to do so unless the ductal system subsequently ruptured and formed a granuloma when thymidine incorporation returned to normal control levels. It is suggested that in the guinea=pig vasectomy alters spermatogenesis by reducing testicular DNA synthesis.     

A review of the effects of some endocrinological factors on respiratory mechanics

Context: Endocrinological factors have been recently described to affect respiratory mechanics.

Objective: To review recent literature data, most of all obtained by the end-inflation occlusion method, describing the effects of molecules of endocrinological interest such as endothelin, erythropoietin and renin-angiotensin, on respiratory mechanics parameters.

Methods: The papers considered in this review were found by inserting in Pubmed/Medline the following indexing terms: hormones, endothelin, erythropoietin, angiotensin and respiratory mechanics.

Results: It was found that the above cited molecules, beside their well known physiological main effects, exhibit influences on respiratory mechanics, most of all on the airflow resistance, which was described to be increased by endothelin and angiotensin, and decreased by erythropoietin.

Conclusions: A number of molecules of biological interest exhibit unexpected influences on respiratory mechanics. The clinical effects depend on the consequences of modified inspiratory pressure values the respiratory muscles have to perform for a given breathing pattern.     

Current status of the Progymnospermopsida

The three progymnosperm orders, Aneurophytales, Protopityales, and Archaeopteridales, are characterized and analyzed. The possibility that some of the apparent taxonomic diversity of the Aneurophytales and Archaeopteridales might reflect developmental variation is considered as well as the probability that much of it reflects evolutionary change. A detailed discussion of the phylogenetic position of the Progymnospermopsida concludes the paper.     

Current status of the problem of quantitative estimation of cytogenetic effects of low doses of radiation

The results of the author's own experimental studies and the literature on the cytogenetic effects in human lymphocyte culture induced by low-level radiation are presented. The quantitative regularities of the occurrence of structural chromosome damages in the genome of human somatic cells under the effect of low doses differ from those induced by high doses of ionizing radiation. The adequacy of extrapolating the risk of harmful after-effects from high-to low-level radiation is discussed.     

Current status of the ovine genome map

Genome maps in livestock species have been under development for the last decade. While the sheep map is one of the least advanced for livestock, the amount of available information is noteworthy, in light of the paucity of funding and personnel devoted to this project. These limited resources have been strategically aligned to take advantage of information from the human, mouse and bovine mapping and sequencing efforts. The resulting ovine linkage and physical maps have greatly enhanced the search for genes controlling important traits in sheep. In order to improve the efficiency of these investigations, it is imperative that efforts on the sheep comparative map be continued.     

Differing behavioral and endocrinological effects of two female sex pheromones on male goldfish

Ovulatory female goldfish sequentially release at least two sex pheromones: 17 alpha, 20 beta-dihydroxy-4-pregnen-3-one (17,20 beta P) and a mixture of F prostaglandins (PGFs). This study sought to determine whether these pheromones have different endocrinological and behavioral actions and whether the PGF pheromone, which is released by spawning females, is responsible for increasing the gonadotropin (GtH) and milt (sperm and seminal fluid) levels of spawning males. Grouped and isolated males were exposed to combinations of these pheromones, food odor, and spawning and nonspawning females. 17,20 beta P stimulated GtH increases in both grouped and isolated males but had only minor effects on behavior; because its principal function appears to be physiological it may be considered a "primer" pheromone. In contrast, exposue to the PGFs elicited large increases in sexual behavior but increased GtH only when fish were exposed as groups; this pheromone's principal action appears to be behavioral and it should be considered a "releaser" pheromone. Although males had increased GtH and milt levels after 1 hr of spawning, males allowed to interact with nonspawning females also had elevated GtH; thus, behavioral interactions appear capable of elevating GtH in the absence of either pheromone. The existence of an independent behavioral mechanism which stimulates GtH was supported by the fact that males exposed to 17,20 beta P while spawning had GtH levels much greater than males exposed to only one of these stimuli.     

Current status of lupus genetics

Over the past 40 years more than 100 genetic risk factors have been defined in systemic lupus erythematosus through a combination of case studies, linkage analyses of multiplex families, and case-control analyses of single genes. Multiple investigators have examined patient cohorts gathered from around the world, and although we doubt that all of the reported associations will be replicated, we have probably already discovered many of the genes that are important in lupus pathogenesis, including those encoding human leukocyte antigen-DR, Fcγ receptor 3A, protein tyrosine phosphatase nonreceptor 22, cytotoxic T lymphocyte associated antigen 4, and mannose-binding lectin. In this review we will present what is known, what is disputed, and what remains to be discovered in the world of lupus genetics.     

Current status of Kluyveromyces systematics

A brief outline of the current taxonomic status of the genus Kluyveromyces is presented. Noteworthy are the transfer of several former Kluyveromyces species to other genera, the retention of the name Kluyveromyces for K. lactis, K. marxianus, and four related species, and some recent attempts to clarify the variety status of strains assigned to K. lactis.     

Current status of annelid phylogeny

Annelida is an ecologically and morphologically diverse phylum within the Lophotrochozoa whose members occupy a wide range of environments and show diverse life styles. The phylogeny of this group comprising more than 17,000 species remained controversial for a long time. By using next-generation sequencing and phylogenomic analyses of huge data matrices, it was finally possible to reach a well-supported and resolved annelid backbone tree. Most annelid diversity is comprised in two reciprocal monophyletic groups, Sedentaria and Errantia, which are named after the predominant life style of their members. Errantia include Aciculata (Phyllodocida?+?Eunicida) and Protodriliformia, which is a taxon of interstitial polychaetes. Sedentaria comprise most of the polychaete families formerly classified as Canalipalpata or Scolecida, as well as the Clitellata. Six taxa branch as a basal grade outside of this major radiation: Oweniidae, Magelonidae, Chaetopteridae, Sipuncula, Amphinomida, and Lobatocerebrum. Oweniidae and Magelonidae form a monophyletic group which we name Palaeoannelida, which constitutes the sister taxon of the remaining annelids. The early splits of annelid phylogeny date back to the Cambrian. The new annelid phylogeny highlights the variability and lability of annelid body plans, and many instances of simplifications of body plan as adaptations to new life styles can be found. Therefore, annelids will be an appropriate model to understand major transitions in the evolution of Bilateria in general. Evolutionary developmental studies are one way to investigate macroevolutionary transition in annelids. We briefly summarize the state of developmental model organisms in Annelida and also propose new candidates on the background of the phylogeny.     

中国扬子鳄(Alligator sinensis)物种资源现状

1994年8～9月,对安徽扬子鳄国家级自然保护区扬子鳄资源进行了抽样调查,见到有鳄活动痕迹的洞口104个,用光点计数法实见鳄77条,访问法计数为253条,由此分析保护区内有鳄667～740条,其种群年龄锥体为上宽下窄,反映出扬子鳄在野外生存形势严峻。该年,安徽省扬子鳄繁殖研究中心存鳄4376条,其中种鳄248条,孵化幼鳄1542条,其它不等龄鳄2586条,种群年龄锥体为上窄下宽,是一个迅速增长的种群,生存形势良好。     

反义核酸药物的研究现状

反义药物以其合理设计药物的可能性和精确的特异性广泛吸引了人们的注意,但反义药物的研究并非如人们最初预想的那样简单。本文从其特异性,稳定性,透过靶细胞的能力,作用强度,活性判定,给药途径,安全性和毒性,生产成本等诸方面对反义药物的研究现状,现存问题进行了综述。相信伴随这些问题的解决,反义药物很可能成为药典的一部分,给疾病的治疗带来益处。     

缺血预处理的研究现状

目录　　　一、缺血预处理的研究历史二、缺血预处理的实验研究方法　(一)缺血预处理动物模型的复制　(二)其他的预处理方法三、缺血预处理的细胞保护作用　(一)心脏保护作用　(二)心脏以外其他组织器官的保护作用　(三)远隔器官的保护作用四、缺血预处理的细胞保护机制　(一)与缺血预处理有关的内源性触发因子与介质　(二)缺血预处理的细胞信号转导机制　(三)缺血预处理的细胞核反应机制　(四)参与缺血预处理的内源性保护蛋白五、缺血预处理的临床应用现状六、结语　　预先反复短暂缺血可以延缓或减轻组织后续缺血(再灌注)损伤的现象被称为…     

害虫对氟虫腈的抗药性研究进展

氟虫腈是第一个商品化的苯基吡唑类杀虫剂,其作用机理是抑制γ-氨基丁酸(GABA)受体氯离子通道。氟虫腈为防治一些世界性的重大害虫包括对以前使用的杀虫剂具有严重抗性的害虫作出了重要贡献。然而,随着氟虫腈的大量使用,害虫对该药的抗药性问题受到日益关注。至今,重要的农业害虫如小菜蛾,烟粉虱、褐飞虱、白背飞虱,二化螟及斜纹夜蛾等已经对氟虫腈产生抗药性。文章就害虫对氟虫腈的抗药性发生概况、交互抗性及抗药性机理策略进行综述,以期为氟虫腈的合理使用提供理论基础。     

Current status of the rat prolactin releasing factor

The release of prolactin is governed by both inhibiting and releasing factors. Basal plasma concentration of prolactin is controlled mainly through inhibition by a prolactin release-inhibiting factor (PIF), while acute stimulation of prolactin release is believed to be caused by a prolactin-releasing factor (PRF). It is the general consensus that PIF is dopamine. The PRF plays an important role in stimulation of prolactin release, and there are promising putative PRFs.