Morphometric evidences for regional variation in potential of neural plasticity

The neural plasticity showing the ability of nervous system to change its structure and function is a well-documented fact. However regional variation within a CNS structure to undergo plastic changes has been shown by limited studies. Along medial-lateral sequences of parasagittal sections, the molecular layer thickness of primary fissure borderlands in rat cerebellar left hemisphere was studied to assess the regional difference in plasticibility. Despite the homogeneity of cerebellar histology, this study showed that there is a significant interlobular difference between ML thicknesses of Prf borderlands. In addition, it revealed that the thickness alters in a significant trend within each borderland. The quantitative heterogeneity of cerebellar architecture such as variation of cortical thickness may provide some evidences to show that different regions of a homogenous cortex, even two adjacent borderlands and areas within them, can have different potentials for plasticity. © 2006 Sociedad Chilena de Anatomía

Design and implementation of 30kW 200/900V LCL modular multilevel based DC/DC converter for high power applications

This paper presents the design, development and testing of a 30kW, 200V/900V modular multilevel converter (MMC) based DC/DC converter prototype. An internal LCL circuit is used to provide voltage stepping and fault tolerance property. The converter comprises two five level MMC based on insulated gate bipolar transistors (IGBTs) and metal oxide semiconductor field effect transistor (MOSFET). Due to low number of levels, selective harmonic elimination modulation (SHE) is used, which determines the switching angles in such a way that third harmonic is minimized whereas the fundamental component is a linear function of the modulation index. In addition, instead of using an expensive control board, three commercial control boards are embedded. This is required to implement the sophisticated DC/DC converter control algorithm. Simulation and experimental results are presented to demonstrate the converter performance in step up and down modes

Can formaldehyde exposure induce histopathologic and morphometric changes on rat kidney? [¿la exposición al formaldehído puede inducir cambios histopatológicos y morfométricos sobre el riñón de rata?]

Formaldehyde is used traditionally for fixing the cadaver, and vaporized during dissection and practical studying on cadaver. This study was designed to determine the histopathologic and morphometric changes of rat kidney while all of the experiments were exposed to formaldehyde for 18 weeks. 28 male albino Wistar rats were divided into the following three experimental groups (E1: 2hrs/d, 2d/w; E2: 2hrs/d, 4d/w; E3: 4hrs/d, 4d/w) and one control group (C). when the exposure period was expired the animals were anaesthetized with chloroform. After cervical dislocation, the abdomen was dissected and the kidneys were taken. The kidney specimens were sectioned and stained with Haematoxylin and Eosin technique for histologic and morphometric study. Data were obtained from an Olympus light microscope and the analyzed with spss (version 11.5) and ANOVA test. In all histopathology sections of groups E1, E2 and E3, these similar changes were seen: mild glumerolar congestion, focal congestion, and vacuolar degeneration of tubular cells. There were no evidences of inflammatory cells infiltration or fibrotic changes of interstitial tissue. Only mild, non-specific congestion was seen in cortical vessels. Also there were not any abnormalities in the staining of nucleus and cytoplasm. According to Morphometric study, Mean ±SD of glomerulus's area in control, E1, E2 and E3 group were 10802.66±1038.18, 10759.50±1971.88, 10434.73±1763.76 and 10077.64±2068.78 micrometer, respectively. Mean ±SD inner proximal tubule diameter in control, E1, E2 and E3 group were 16.16±2.49, 16.92±2.90, 16.31±2.79 and15.66±4.11 μm, respectively. Mean ±SD of inner distal tubule diameter in control, E1, E2 and E3 group were 15.96±4.47, 16.20±1.66, 16.96±1.63 and17.45±3.26 μm, respectively. These differences were not significant between cases and control. This study showed that formaldehyde inhalation in 1.5 ppm can not make specific Histopathologic and Morphometric changes in rat kidney

Formaldehyde exposure induces histopathological and morphometric changes in the rat testis

Formaldehyde is a chemical which is traditionally used for fixing cadavers and routine histopathology techniques. It is vaponsed during the dissection and practical study of a cadaver. Previous studies have shown that this vapour may cause clinical symptoms such as throat, eye, skin and nasal irritation. This study was designed to determine the histopathology and morphometrics of the rat testis when all the experimental animals were exposed to formaldehyde for 18 weeks. The study was performed in 2004 on 28 albino Wistar rats of 6-7 postnatal weeks. The rats were divided into three case groups (E1: 4 h/d, 4 d/w; E2: 2 h/d, 4 d/w; E3: 2 h/d, 2 d/w) and one control group. The testes specimens were sectioned at 5 μm and stained with the haematoxylin and eosin staining technique for histological and morphometrical studies. We found a severe decrease in germ cells associated with spermatogenesis arrest in the E1 group. A decrease in germ cells and a thickening of the basal membrane of the seminiferous tubules were seen in E2. Displacement of Sertoli and germinal cells were also found in the E3 group. The mean seminiferous tubular diameter and seminiferous epithelial height in the experimental groups were decreased in comparison with the control group and the differences were statistically significant (p < 0. 05). The findings of this study revealed that chronic formaldehyde exposure can cause histopathological and morphometric changes to the seminiferous epithelium in rats and that these changes depend on the duration of the formaldehyde exposure. Copyright © 2007 Via Medica

Morphometric alterations to the rat spleen following formaldehyde exposure

Formaldehyde is commonly used in the production of various industrial and medical products. At room temperature formaldehyde easily evaporates. Exposure to formaldehyde can be hazardous to human health. Studies show that the vapour can be the cause of clinical symptoms such as throat, eye, skin and nasal irritation. It can also decrease the production of IgM in the spleen cells. This study was designed to determine the morphometric changes to the spleen in rats when samples were exposed to formaldehyde for 18 weeks. A total of 28 albino Wistar rats aged 6-7 postnatal weeks were divided into the following three case groups according to their exposure to formaldehyde: E1 (2 h/day, 2 days/week), E2 (2 h/day, 4 days/week), E3 (4 h/day, 4 days/week) and one control group. When the exposure period had expired the animals were anaesthetised with chloroform. After cervical dislocation, the abdomen was dissected and spleen specimens were taken. These were sectioned and stained with the haematoxylin and eosin technique for morphometric study. Data was obtained from an Olympus light microscope and then analysed with SPSS (version 11.5) and one-way ANOVA test. The white pulp area and diameter and the marginal zone diameter were greater in group E3 than those in the other groups. The germinal centre area and diameter and the diameter of the periarterial lymphoid sheaths (PALS) were greater in group E2 than in other groups, although there was no significant difference between groups in the area of white pulp and the PALS diameter (p < 0.05). This study showed that formaldehyde vapour can cause morphometric changes in the white pulp of the spleen in rats. Copyright © 2008 Via Medica

Group a streptococcal serotypes isolated from healthy schoolchildren in iran

Serotypes of group A streptococci are still a major cause of pharyngitis and some post-infectious sequelae such as rheumatic fever. As part of the worldwide effort to clarify the epidemiological pattern of group A streptococci in different countries, the present study was conducted to assess the prevalence of Streptococcus pyogenes serotypes in Iran. A total of 1588 throat swabs were taken from healthy school children in the city of Gorgan during February and March 1999. Of those isolates, 175 resulted positive for group A streptococci. The distribution pattern was similar for girls and boys, with 10.8 and 11.2, respectively. Urban school children showed a higher rate of colonization compared to those in rural areas. Serotyping was performed on 65 of the positive isolates using standard techniques, and only 21 (32) were M-type isolates. Their profiles fell into four types with M1 predominating, which could reflect the presence of rheumatic fever in the region. However, when isolates were challenged for T-antigen types, nearly all were positive (94). The pattern of T types was diverse (18 types), with the most common T types being T1 (26), TB3264 (15), TB\1-19 & B\25\1-19 (9.2) and T2 & 2\28 (7.7). When isolates were tested for opacity factor, only 23 (35) were positive while 34 (52) responded to the serum opacity reaction test. Although the number of isolates in this study was not sufficient to make any epidemiological conclusions, the scarcity of serotyping studies in Iran could render these data useful for future attempts to develop a streptococcal vaccine

Assessing Pb, Ni and Zn accumulation in the tissues of Liza aurata in the south Caspian Sea

The liver, kidney, gill, ovary and muscle tissues of the caught Liza aurata have been sampled in spring 2002 in the southern Caspian Sea to assess their contamination with Pb, Ni and Zn using atomic absorption spectrophotometer method. We found the highest concentration of lead in the liver tissue (17.51 mg/kg), followed by gill (13.95 mg/kg); kidney (5.03 mg/kg) and ovary (4.91 mg/kg). The lowest concentration of lead was seen in muscle tissue (3.01 mg/kg) of Liza aurata. The highest accumulation of Ni and Zn were detected in ovary followed by liver, gill and kidney of the fish with a concentration of 6.23, 6.14, 5.71, and 2.98 mg/kg for Nickel and 647.28, 159.85, 75.71 and 65.42 mg/kg for Zinc. We observed the lowest concentration of Nickel (2.49 mg/kg) and Zinc (20.14 mg/kg) in the muscle tissue and also determined the highest contamination of the fish with these chemicals to be occurring in the southwest followed by south center and southeast Caspian Sea

Paternal effects in a wild‐type zebrafish implicate a role of sperm‐derived small RNAs

While the importance of maternal effects has long been appreciated, a growing body of evidence now points to the paternal environment having an important influence on offspring phenotype. Indeed, research on rodent models suggests that paternal stress leaves an imprint on the behaviour and physiology of offspring via nongenetic information carried in the spermatozoa; however, fish have been understudied with regard to these sperm‐mediated effects. Here, we investigated whether the zebrafish was subjected to heritable influences of paternal stress by exposing males to stressors (conspecific‐derived alarm cue, chasing and bright light) before mating and assessing the behavioural and endocrine responses of their offspring, including their behavioural response to conspecific‐derived alarm cue. We found that after males are exposed to stress, their larval offspring show weakened responses to stressors. Small RNA sequencing subsequently revealed that the levels of several small noncoding RNAs, including microRNAs, PIWI‐interacting RNAs and tRNA‐derived small RNAs, were altered in the spermatozoa of stressed fathers, suggesting that stress‐induced alterations to the spermatozoal RNA landscape may contribute to shaping offspring phenotype. The work demonstrates that paternal stress should not be overlooked as a source of phenotypic variation and that spermatozoal small RNAs may be important intergenerational messengers in fish