Sertoli cell cycle: A re-examination of the structural changes during the cycle of the seminiferous epithelium of the rat

Seminiferous tubules in mammals are composed of cell associations that show a cyclic pattern of renewal and development. The cyclic nature of germ cell development suggests that the cells supporting the spermatogenic process, the Sertoli cells, might also differ structurally during the spermatogenic cycle in terms of the quantity of their constituents. In the present study, cyclic differences in volumes, and surface areas were determined using a sampling technique at the electron microscope level that proportionally samples the Sertoli cell within the seminiferous tubule. Among the many parameters studied, only the surface area of the cell, the volume of lipid, and the volume and surface area of the rough endoplasm reticulum were shown by statistical analysis to vary cyclically. Regarding rough endoplasm reticulum, the volume and surface area of this organelle peaked at mid-cycle and its low was recorded near the end of the cycle, exhibiting an approximate 15-fold difference between extremes. The rough endoplasm reticulum parameters generally correlated with known patterns of protein secretion within the tubule and with the secretion of specific proteins as well as the factors important in controlling protein secretion. Many Sertoli cell structural parameters suggested to be influenced cyclically in the rat in other studies could not be confirmed by the present study. Methodological differences in the present study and past studies are discussed as potential sources of error for these discrepancies. © 1993 Wiley-Liss Inc.     

Method of investigation of deviations from the normal duration of the cardiac cycle

An electronic system for determining the frequency of deviations from the normal duration of the cardiac cycle is described.Department of Physics and Department of Pediatrics, Voroshilovgrad Medical Institute. (Presented by Academician V. N. Chernigovskii.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 78, No. 7, pp. 123–124, July, 1974.     

PDCA循环法在医院药学教学中的应用

目的探讨“计划-执行-检查-处理”循环法(以下简称“PDCA循环法”)在医院药学教学工作中的应用效果。为加强医院药学培训、提升服务水平提供可靠参考。方法以北京朝阳医院2015年9月至2019年9月进行药学教学培训的学员为研究对象,随机抽取接受PDCA循环法药学教学培训模式的学员作为观察组,以接受传统的一般形式教学方法的学员作为对照组,对比两组研究对象在不同教学方法下的考核评分。结果观察组理论知识和操作技能评分均高于对照组(P<0.05)。结论PDCA循环法的系统化教学培训方法有利于改善学员的理论知识掌握度和操作技能,在医院药学教学中值得应用;带教导师在PDCA循环中发挥重要作用,需加强师资和制度建设;教学方法的改进有利于提高学员学习的积极性和自主性。     

Cell cycle dependent phosphatase activity in Bacillus subtilis

In Bacillus subtilis there is evidence that the replication origin of the DNA molecule is attached to the cytoplasmic membrane, and that this attachment is essential for the initiation of replication. We have previously shown that attachment of DNA to the membrane is cyclic and that DNA becomes attached to the cytoplasmic membrane at the beginning of replication and is subsequently released. We have also shown that membrane protein phosphorylation is associated with the initiation of DNA replication in B. subtilis. We now report that cantharidin, an inhibitor of eukaryotic serine/threonine protein phosphatases type 1 and 2A, stimulated membrane binding of DNA and caused premature initiation of DNA replication in B. subtilis cells. The membrane of B. subtilis cells had cell cycle dependent phosphatase activity against a standard substrate in vitro. Cloning of the B. subtilis protein PrpE and production of antibodies allowed us to identify the protein in the cytoplasmic membrane. Its presence was cell cycle dependent, and appeared to contribute to the observed phosphatase activity.     

G2/M cell cycle arrest in the life cycle of viruses

There is increasing evidence that viral infection, expression of viral protein or the presence of viral DNA causes the host cell cycle to arrest during G2/M. The mechanisms used by viruses to cause arrest vary widely; some involve the activation of the cellular pathways that induce arrest in response to DNA damage, while others use completely novel means. The analysis of virus-mediated arrest has not been proven easy, and in most cases the consequences of arrest for the virus life cycle are not well defined. However, a number of effects of arrest are being investigated and it will be interesting to see to what extent perturbation of the G2/M transition is involved in viral infections.     

Investigation of the capillaries of the rat parotid gland during a 3-h secretory cycle

Principles governing changes in diameter of the lumen and area of the endothelium of capillaries in the parotid salivary gland of rats with an experimentally established 3-h secretory cycle, and also during circulatory ischemia of the organ for 5 min, were studied. The diameter of the lumen and area of the endothelium of the capillaries changed very little with the phase of the secretory cycle. Occlusion of the common carotid artery for 5 min likewise did not change the diameter of the lumen or the area of the endothelium of the capillaries. The results suggest that the increase in the transcapillary blood flow during secretion can be explained by the recruiting of more capillaries into the circulation.Laboratory of Electron Microscopy, N. I. Pirogov Second Moscow Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR V. V. Kupriyanov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 80, No. 7, pp. 104–106, July, 1975.     

Affect and the menstrual cycle.

Evidence from both retrospective and prospective studies suggests that many women do show cyclical changes in affect. Negative changes such as irritability, headache, tension, anxiety, sleep disturbance and depression are more frequent in the premenstrual and menstrual phases. Positive changes, pleasantness, increased vigour and elation are reported more often in the follicular or mid-cycle phases. Various theories have been suggested to explain these changes. These include psychodynamic, sociological and biological explanations. Although there is some evidence to support each theory no definite conclusions can be reached about the aetiological basis of most affective changes. Interpretation of studies attempting to link hormonal and affective fluctuations in limited by the many methodological problems outlined. Only one study appeared able to conclusively demonstrate a hormonal basis for a cyclical symptom. Suggestions are made for further research in this area.     

Cross-sectional multicenter study of patients with urea cycle disorders in the United States

Inherited urea cycle disorders comprise eight disorders (UCD), each caused by a deficiency of one of the proteins that is essential for ureagenesis. We report on a cross-sectional investigation to determine clinical and laboratory characteristics of patients with UCD in the United States. The data used for the analysis was collected at the time of enrollment of individuals with inherited UCD into a longitudinal observation study. The study has been conducted by the Urea Cycle Disorders Consortium within the Rare Diseases Clinical Research Network (RDCRN) funded by the National Institutes of Health. One-hundred eighty-three patients were enrolled into the study. Ornithine transcarbamylase (OTC) deficiency was the most frequent disorder (55%), followed by argininosuccinic aciduria (16%) and citrullinemia (14%). Seventy-nine percent of the participants were white (16% Latinos), and 6% were African American. Intellectual and developmental disabilities were reported in 39% with learning disabilities (35%) and half had abnormal neurological examination. Sixty-three percent were on a protein restricted diet, 37% were on Na-phenylbutyrate and 5% were on Na-benzoate. Forty-five percent of OTC deficient patients were on l-citrulline, while most patients with citrullinemia (58%) and argininosuccinic aciduria (79%) were on l-arginine. Plasma levels of branched-chain amino acids were reduced in patients treated with ammonia scavenger drugs. Plasma glutamine levels were higher in proximal UCD and in neonatal type disease. The RDCRN allows comprehensive analyses of rare inherited UCD, their frequencies and current medical practices.     

Electrographic analysis of the sleep cycle in young depressed patients.

Electrographic (EEG) patterns of nocturnal sleep were investigated in young psychiatric patients during unipolar depressive episodes. EEG-sleep data was recorded in 20 non-psychotic depressed patients all under 26 years old individually matched with a normal control group. All 20 subjects slept in the laboratory for 1-3 consecutive baseline nights from 12-8:00 a.m. During a subsequent extended condition 14 in each group were allowed to sleep ad-lib. Although the mean total time asleep on baseline nights was about the same between groups (greater than 7.1 hr), the depressives had a statistically significant reduction in REM time, increased transitions into stage 1, but most especially averaged: (a) less stage 4; and (b) more stage 1. Compared with the prior eight-hour night 27/28 subjects among both groups exhibited elevated time asleep during the extended condition, but the patients' mean total 10.3 hr sleep was significantly greater by 1.5 hr than the controls (X = 8.8 hr). Sleep exceeding 9 hr on the ad-lib night was a consistent phenomenon which occurred in significantly more (11/14) young depressed patients contrasted to 4/14 control subjects. These findings indicate that young persons with primary affective disorders do not exhibit nocturnal EEG disturbances of comparable severity to most older depressed patients such as reduced time asleep, increased wakefulness or lowered slow-wave (stages 3 and 4) sleep. Although no direct evidence of symptomatic 'hypersomnia' in these patients was provided, the present results demonstrated that some young persons with clinical depression have the capacity to sleep for sustained periods.     

Estimated maximum failure rates of cycle monitors using daily conception probabilities in the menstrual cycle

BACKGROUND: A number of menstrual cycle monitors have been developed to detect the fertile window of the menstrual cycle, mainly for contraceptive purposes. Reliable data on most of these systems are still missing but are urgently needed because many women use them and the tested systems differ enormously in price and effectiveness. We suggest a new efficacy estimating method to evaluate cycle monitors prior to full prospective clinical trials. METHODS: Sixty-two women prospectively tested seven cycle monitors and the symptothermal method (STM) of natural family planning (NFP) but not more than two different systems at the same time. The clinical fertile window was determined by detecting the day of ovulation using daily urinary LH measurements and daily ultrasonic folliculometry. This was compared to the fertile phase predicted by the systems. Maximum failure rates were estimated for each cycle monitor and the STM, using the daily conception probability rates taken from the European Fecundability Study. Intercourse was assumed to occur on each of all falsely predicted days of infertility. RESULTS: Sixty-two women with a mean age of 31 years (range: 21-42 years) contributed a total of 122 cycles to this study. Monitors based on the microscopic evaluation of saliva or mucus had many more false infertile days than the other methods based on temperature or hormonal measurements (225 versus 42 days). The maximum unintended pregnancy rates per cycle for temperature computers were estimated to be 0.0134-0.0336, for the hormonal computer 0.1155 and for mini-microscopes 0.2313-0.2369. For the STM of NFP, there were no false infertile days. CONCLUSIONS: The STM of NFP proved to be the most effective contraceptive method to detect the fertile window among all the methods tested. The estimated efficacy of the other cycle monitors range from the temperature computers (upper level) to the hormonal computer (medium level) and the mini-microscopes with very low estimated contraceptive efficacy.     

Action of hydrocortisone on mitotic cycle of pyloric epithelial cells of the mouse stomach

It was shown by the use of thymidine-H³ that the mitotic cycle of mucus-forming cells (superficial epithelial and mucosal cells of the neck) of the pyloric glands of the mouse stomach lasts 13.5 h (G₁+1/2M=7.6h S=5.3 h, G₂+1/2M=0.6 h). After administration of a physiological dose of hydrocortisone (0.1 mg) the duration of the mitotic cycle of these cells increased by 6.7 h (G₁+1/2M=11.6 h, S=7.8 h, G₂+1/2M=0.8 h). A large dose of the hormone (3 mg) had a similar action and increased the duration of the presynthetic period to 12.9 h and of the postsynthetic to 2.3 h.Presented by Academician of the Academy of Medical Sciences of the USSR A. P. Avtsyn.Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 79, No. 6, pp. 92–95, June, 1975.     

Changes in surface area and number of Leydig cells in relation to the 6 stages of the cycle of the human seminiferous epithelium

Summary In order to evaluate the occurrence of a Leydig cell cycle related to the cycle of the seminiferous epithelium in man, the numbers of peritubular Leydig cells and surface area of these cells along 1 mm of tubular basement membrane at each stage of the cycle were calculated on histological sections of young adult testes. The Leydig cells that were located separated from the tubules (perivascular Leydig cells) were also classified according to the stage of the cycle shown by the nearest seminiferous tubule; the surface area and number of these cells were also calculated. The total surface area and numbers of Leydig cells (peritubular plus perivascular) along 1 mm of tubular basement membrane did not change during the cycle of the seminiferous epithelium. Both the surface area and the numbers of peritubular Leydig cells were greater in stages I and II of the cycle, when spermatozoa are released; they decreased in stages III and IV and increased again in stages V and VI, whereas the contrary occurred in perivascular Leydig cells. The average surface area of each Leydig cell type remained constant throughout the stages of the cycle.This work was supported by grants from the Comisión Asesora de Investigación Científica y Técnica and the Fondo de Investigaciones Sanitarias de la Seguridad Social, Madrid, Spain.     

Problems in the management of urea cycle disorders

Several recent reviews describe the management of urea cycle disorders. There is much agreement on diet, alternative pathway therapy, maintenance of arginine and ornithine levels in acute and chronic management, sick-day regimens, and some aspects of monitoring. However, differences remain in several areas, and physicians at most treatment centers have relatively little experience, because these disorders are rare. Early suspicion of the diagnosis of a urea cycle disorder, and prompt referral to a tertiary center is vital. Drug treatment using chronic administration of sodium benzoate has been abandoned by some centers, but the acceptability of phenylbutyrate is an issue for many patients. Using citrulline chronically is not always successful in recommended doses, and may result in an arginine level too low for maximum control. Appetite and nutrition problems are common. One major concern is the early identification and management of chronic catabolism, theoretically easy, but hard in practice. Biochemical measurement problems complicate monitoring, and there are disagreements about the optimum way of identifying OTC carriers. It is not always clear whom to treat. Within a kindred with an early-onset phenotype, an asymptomatic newborn girl may need treatment for some undetermined time, but target values for monitoring are not clear. In late-onset phenotypes, management of asymptomatic males identified by family screening is also difficult. Most centers do not have sufficient cases to solve these conundrums, some of which require further multicenter study. This paper examines the recommendations of a consensus conference on management, outlines some remaining problems, and incorporates in the text the points raised in open discussion during a session of a symposium held in Sydney in 2003 entitled "New Developments in Urea Cycle Disorders."