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Sex determination is a complicated process involving large-scale modifications in gene expression affecting virtually every tissue in the body. Although the evolutionary origin of sex remains controversial, there is little doubt that it has developed as a process of optimizing metabolic control, as well as developmental and reproductive functions within a given setting of limited resources and environmental pressure. Evidence from various model organisms supports the view that sex determination may occur as a result of direct environmental induction or genetic regulation. The first process has been well documented in reptiles and fish, while the second is the classic case for avian species and mammals. Both of the latter have developed a variety of sex-specific/sex-related genes, which ultimately form a complete chromosome pair (sex chromosomes/gonosomes). Interestingly, combinations of environmental and genetic mechanisms have been described among different classes of animals, thus rendering the possibility of a unidirectional continuous evolutionary process from the one type of mechanism to the other unlikely. On the other hand, common elements appear throughout the animal kingdom, with regard to a) conserved key genes and b) a central role of sex steroid control as a prerequisite for ultimately normal sex differentiation. Studies in invertebrates also indicate a role of epigenetic chromatin modification, particularly with regard to alternative splicing options. This review summarizes current evidence from research in this hot field and signifies the need for further study of both normal hormonal regulators of sexual phenotype and patterns of environmental disruption. © 2012 Angelopoulou et al; licensee BioMed Central Ltd.

Reactive oxygen species (ROS) are active byproducts of aerobic metabolism. Although they are constantly produced during normal cellular activities in the mitochondria, their action is counteracted by inherent antioxidant systems. This equilibrium is distorted in the case of acute or chronic inflammation, which results in increased ROS production and, ultimately, oxidative stress. In sperm, ROS are produced by both spermatozoa and circulating leucocytes and may be part of normal adaptive reactions, such as the capacitation process. However, a number of external toxicants may also contribute to ROS production in the testis and epididymis, leading to a decrease in sperm viability and motility and, therefore, an increased onset of the male factor of infertility. Such pro-oxidative conditions include, among others, exposure to radiation, extreme temperature, certain drugs, toxins, heavy metals, smoking and biological hazards. The current review paper summarizes the available evidence incriminating ROS and oxidative stress as the underlying pathophysiological mechanism leading to the onset of reproductive toxicity in each of these settings. © 2012 Elsevier Inc.

Studies have documented the presence of herpes viruses in semen. The aim of our study was to determine whether they persist in semen samples following two-density gradient centrifugation for IVF purposes. Semen samples were collected from 109 men seeking fertility evaluation, prior to IVF treatment. Routine semen analysis was performed according to WHO guidelines. Each sample was treated in a two-density gradient centrifugation using PureSperm (PS). Both untreated and treated samples were screened for the presence of herpes viruses, using PCR. Kruskal-Wallis, chi-square and binomial statistical tests were used; P≤0.05 was considered statistically significant. No statistically significant associations were observed between semen parameters and viral presence. Viral DNA was detected in 54% of semen samples: HSV1/2 in 32 samples, EBV in 49, CMV in 47, HHV6 in 9, HHV7 in 4 and VZV in none. PS gradient failed to remove CMV in 89.36%, HSV1/2 in 59.38% and EBV in 22.45% of samples, while HHV6 and 7 were completely removed. Especially HSV1/2 and CMV seem to persist even following PS treatment. These observations indicate the possible risk of oocyte becoming infected during insemination, by IVF or intracytoplasmic sperm injection, with unknown sequelae. Further studies are required to determine whether any correlation exists between their presence, implantation rate and the outcome of pregnancy. © 2011 Blackwell Verlag GmbH.

DNA lesions trigger the DNA damage response (DDR) machinery, which protects genomic integrity and sustains cellular survival. Increasing data underline the significance of the integrity of the DDR pathway in chemotherapy response. According to a recent work, persistent exposure of A549 lung carcinoma cells to doxorubicin induces an initial DDR-dependent checkpoint response, followed by a later DDR-independent, but p27Kip1-dependent one. Prompted by the above report and to better understand the involvement of the DDR signaling after chemotherapeutic stress, we examined the potential role of the canonical DDR pathway in A549 cells treated with doxorubicin. Exposure of A549 cells, prior to doxorubicin treatment, to ATM, ATR and DNA-PKcs inhibitors either alone or in various combinations, revealed that the earlier documented two-step response was DDR-dependent in both steps. Notably, inhibition of both ATM and ATR or selective inhibition of ATM or DNA-PKcs resulted in cell-cycle re-entry despite the increased levels of p27Kip1 at all time points analyzed. We further investigated the regulation of p27Kip1 protein levels in the particular setting. Our results showed that the protein status of p27Kip1 is mainly determined by p38-MAPK, whereas the role of SKP2 is less significant in the doxoroubicin-treated A549 cells. Cumulatively, we provide evidence that the DNA damage signaling is responsible for the prolonged cell cycle arrest observed after persistent chemotherapy-induced genotoxic stress. In conclusion, precise identification of the molecular mechanisms that are activated during the chemotherapeutic cycles could potentially increase the sensitization to the therapy applied. © 2010 The Authors. Journal compilation © 2010 Foundation for Cellular and Molecular Medicine/Blackwell Publishing Ltd.

All of the topics mentioned above were discussed in the recent joint Postgraduate Course of the European Academy of Andrology and the Hellenic Society of Andrology. Although a written report cannot substitute for the living experience of a postgradute course, it may serve as a useful reference and revision tool for future use. © 2009 WPMH GmbH.

Although cellular proliferation is a key component in the progression of atherosclerosis, research so far has been focused primarily on VSMCs. In this study we attempted to evaluate overall proliferation rates in general, as well as foam cells and the endothelial cells lining newly formed plaque microvessels in particular. For this purpose, cellular proliferation was assessed through immunohistochemical staining for PCNA in 10 fresh human carotid artery samples received from patients undergoing carotid endarterectomy. Overall proliferative activity was found significantly higher (P ≤ 0.01) among complicated type VI lesions compared to uncomplicated type V lesions. A similar assessment focused on foam cells alone also revealed a significantly higher (P ≤ 0.05) proliferative index among complicated lesions. On the other hand, the proliferation rate for the endothelial cells lining the interior walls of newly formed microvessels was harder to properly assess, since only two of the uncomplicated lesions bore signs of neovascularization. Still, both of these samples displayed proliferation rates similar to those of the complicated type VI lesions. Thus, it seems that, although total cell population and foam cells are probably affected by the stimulating factors that are expressed during acute events, the same does not apply to the endothelial cells lining plaque vessels. © 2009 Elsevier Ltd. All rights reserved.

Cardiovascular disease incidence rates have long been known to significantly differ between the two sexes. Estrogens alone fail to explain this phenomenon, bringing an increasing amount of attention to the role of androgens. Contrary to what was initially hypothesized, androgens seem to have an overall cardioprotective effect, especially in men. Recent studies and published data continue to support this notion displaying a consistent inverse correlation with atherosclerosis progression and cardiovascular disease both in regressive and prospective study models. Clinical studies have also revealed what seems to be a differential androgenic effect on various cardiovascular risk factors between men and women. Further insight indicates that in order to avoid confusion it may be also preferable to separately examine the effects of endogenous androgen levels from exogenous testosterone administration, as well as discern the differential results of low to normal and supraphysiological administration doses. This review summarizes old and recent data according to the above distinctions, in an attempt to further our understanding of the role of androgens in cardiovascular disease. © 2009 Manolakou et al; licensee BioMed Central Ltd.

Sertoli cell population kinetics, as evidenced by semi-quantitative immunolabeling for proliferating cell nuclear antigen (PCNA) and Ki-67, in developing Wistar rat male gonads of embryos and neonates [14.5 days post conception (dpc) - 7 days post partum (dpp)], was investigated. Throughout the examined period a gradual increase of immunolabeled Sertoli cell number, associated with intense mitotic activity, was observed. PCNA labeling index of Sertoli cells increased from 66.67 (at 14.5 dpc) to 89.74 (at 18.5 dpc) and then dropped to 75.24 (at 20.5 dpc). At birth, the percentage of PCNA immunoreactive Sertoli cells reached 98.70% and remained high thereafter, attaining a peak value of 99.90% at 7 dpp. The percentage of Ki-67 immunoreactive Sertoli cells in the fetal testis increased from E14.5 (43.95%) to E20.5 (77.40%). The proliferation rate did not alter considerably in the neonatal testis until 5 dpp. At this point, a significant increase of the Ki-67 labeling index was observed and a peak value of 95.76% was reached at 7 dpp. The pattern of Sertoli cell proliferation with age and the establishment of the final Sertoli cell number in vivo established in the present study was compared to the results from earlier investigations reported in the literature and the observed fluctuation of dividing cell numbers, associated with immunolabeling results throughout the examined period, complements and extends existing data. An appraisal of the timing of Sertoli cell proliferation in other species, namely mouse and man, is presented. The current investigation may be useful in evaluating the potential influence of factors interfering with normal mitotic activity of Sertoli cells, including cell selection mechanisms, such as apoptosis, senescence, DNA repair and hormonal/paracrine growth modulation. © 2007 Elsevier GmbH. All rights reserved.

The aim of the current paper is to evaluate the correlation of germ and follicular cells kinetics during ovarian morphogenesis. Thus, immunohistochemical detection of PCNA and Ki-67 proteins has been examined using PC10 (Dako) and NCL-Ki-67 (Novocastra) antibodies in the developing ovaries of Wistar rat embryos and neonates [14.5, 18.5, 20.5 days post-coitum (dpc), birth (day 0), 1, 3, 5, 7 day post-partum (dpp)]. Estimation of reactive/total cell ratio, per cell type (germ and follicular cells) and visual field was achieved using the Image Pro Plus Software. The statistical interpretation of the results has shown that, before birth, using the PCNA antibody, the percentage of labeled/total germ cells (labeling index, LI) increases from 71.19% at 14.5 dpc to 75.66% at 18.5 dpc. It then decreases to 73.26% at 20.5 dpc. At birth, the labeling index drops significantly (28.57%). Immediately after birth, the percentage of labeled/total germ cells increases, reaching 43.58% at 1 dpp. Subsequently, a further decrease in the percentage of reactive cells is observed resulting to a maximum drop of the LI at 7 dpp (18.41%). Using the Ki-67 antibody, the percentage of labeled/total germ cells is generally lower although the fluctuation is similar with that observed using the first marker of cell proliferation. Using the PCNA antibody, the LI of follicular cells in the developing ovary, increases from 0.70% (at 14.5 dpc) to 28.94% (at 18.5 dpc) and then drops to 18.03% (at 20.5 dpc). At birth, the percentage of reactive follicular cells, reaches 27.66% and remains high thereafter. Similar results are obtained using the Ki-67 antibody. In conclusion, follicular cell reaction ratio, using both antibodies (PCNA and Ki-67), increases continuously throughout the examined period with a maximum value at 7 dpp, suggesting a kinetics profile similar to that observed for Sertoli cells in the testis. In all age groups, PCNA labeling is more intense than Ki-67, a result that may be attributed to selective staining at different periods of the cell cycle. © 2008 Elsevier Ltd. All rights reserved.

Chromosomal sex determination is a widely distributed strategy in nature. In the most classic scenario, one sex is characterized by a homologue pair of sex chromosomes, while the other includes two morphologically and functionally distinct gonosomes. In mammalian diploid cells, the female is characterized by the presence of two identical X chromosomes, while the male features an XY pair, with the Y bearing the major genetic determinant of sex, i.e. the SRY gene. In other species, such as the fruitfly, sex is determined by the ratio of autosomes to X chromosomes. Regardless of the exact mechanism, however, all these animals would exhibit a sex-specific gene expression inequality, due to the different number of X chromosomes, a phenomenon inhibited by a series of genetic and epigenetic regulatory events described as "dosage compensation". Since adequate available data is currently restricted to worms, flies and mammals, while for other groups of animals, such as reptiles, fish and birds it is very limited, it is not yet clear whether this is an evolutionary conserved mechanism. However certain striking similarities have already been observed among evolutionary distant species, such as Drosophila melanogaster and Mus musculus. These mainly refer to a) the need for a counting mechanism, to determine the chromosomal content of the cell, i.e. the ratio of autosomes to gonosomes (a process well understood in flies, but still hypothesized in mammals), b) the implication of non-translated, sex-specific, regulatory RNAs (roX and Xist, respectively) as key elements in this process and the location of similar mediators in the Z chromosome of chicken c) the inclusion of a chromatin modification epigenetic final step, which ensures that gene expression remains stably regulated throughout the affected area of the gonosome. This review summarizes these points and proposes a possible role for comparative genetics, as they seem to constitute proof of maintained cell economy (by using the same basic regulatory elements in various different scenarios) throughout numerous centuries of evolutionary history. © 2008 Angelopoulou et al; licensee BioMed Central Ltd.

Germ cells' proliferation during testicular organogenesis in Wistar rat embryos and neonates [14.5, 18.5, 20.5 days post conception (dpc), birth (day 0), 1, 3, 5, 7 days post partum (dpp)] was evaluated via immunohistochemistry, using the PCNA and Ki-67 nuclear antibodies. Estimation of the reactive/total cell ratio, per visual field [labeIing index (LI)] was achieved using the Image Pro Plus Software. Immunostaining of the fetal testis, with both antibodies, revealed increasing germ cells' numbers between 14.5 dpc and birth. From birth onwards, a sharp decline of germ cells' population was observed in the first 3 days of postnatal life. Then, a transient increase of the LI, between 3 and 5 dpp, was noted. Afterwards, proliferation of germ cells ceased. These results indicate that, during fetal and neonatal life, two peaks of proliferative activity of germ cells are noticed. Following estimation of the LI for both PCNA and Ki-67, a prominent labeling for the first antibody was observed throughout the examined period. Ki-67 staining follows a similar pattern, showing, however, significant fluctuation in the obtained values, in comparison to PCNA. The significant differences observed don't seem to be simply a result of the different half lives of the two markers, but rather a consequence of additional underlying cellular activity associated with PCNA, such as DNA repair. © 2007 Elsevier Ltd. All rights reserved.

The successful treatment of breast cancer is dependent upon a number of complex factors. Her-2/neu gene amplification is known to be one of the most common genetic alterations associated with breast cancer and its accurate determination has become necessary for the selection of patients for trastuzumab therapy. The aim of this study was to prove the consistency of chromogenic in situ hybridisation (CISH) technique after analyzing the overexpression of the Her-2/neu proto-oncogene in 100 invasive breast carcinomas and by comparing CISH results with immunohistochemistry (IHC) and fluorescence in situ hybridisation (FISH). Moreover, it was done to evaluate the possible correlation of estrogen (ERs) and progesterone receptors (PRs), the proliferation marker Ki67 and the tumour suppressor gene p53 with HER-2/neu status of these breast carcinomas. Of the 100 breast carcinomas that were analysed, 22 cases showed HER-2/neu amplification, 66 cases showed no amplification, whereas 12 cases were non-interpretable in both assays (FISH and CISH). Consequently, the overall concordance between FISH and CISH was 100%. Additionally, it was observed that when HER-2/neu gene was overexpressed, there was an association with negative PRs and ERs status, negative p53 protein expression and high Ki67 labelling index. It is concluded that patients with tumours scoring 2+ with the CBE356 antibody (borderline immunohistochemistry-tested cases) would also benefit from CISH as it is shown to be highly accurate, practical and can be easily integrated into routine testing in any histopathology laboratory. Finally, CISH represents an important addition to the HER2 testing algorithm. © 2008 The Japan Society of Histochemistry and Cytochemistry.

Normal (n = 20) and abnormal (n = 21) semen samples were explored for possible relationships between conventional semen parameters, chromatin status, and microdeletions in the Y chromosome. DNA fragmentation was detected by the terminal deoxynucleotidyl trasferase-mediated dUTP-nick end labelling (TUNEL) assay, chromatin condensation, and DNA packaging quality were assessed by chromomycin A3 (CMA3) staining. All men were investigated for Y chromosome microdeletions using polymerase chain reaction (PCR). No deletions were detected in 21 severely oligozoospermic men for the three screened regions (AZFa, AZFb, and AZFc). Men with normal semen parameters showed better chromatin condensation. Spermatozoa with low motility were more likely to contain loosely packaged chromatin. In the abnormal semen group, DNA fragmentation (TUNEL) correlated significantly with sperm motility, concentration, and chromatin packaging assessed by chromomycin A3. However sperm morphology did not correlate significantly with TUNEL and CMA3 staining. Copyright © Informa Healthcare.

Sarcomas are neoplasms of mesenchymal origin, with a predominant cell population mimicking the organization of various soft tissues and/or bones. Previous categorizations also included the possibility of the presence of tissue macrophage-like (histiocytes) neoplasm cells, in a tumour described as malignant fibrous histiocytoma, but this group has been considered as a variety of undifferentiated pleomorphic sarcomas. Although this kind of malignancy is not rare in humans, only few cases have been reported in laboratory animals. We report an unusual single case of spontaneous tumour growth, detected by casual observation, in the left thoracic area of an 18-month-old male laboratory Wistar rat. Both this individual and his ancestors were not exposed to any known carcinogenic substance or radiation, thus suggesting the development of the neoplasm as a spontaneous event. The mass was extracted surgically under general anaesthesia, and slices were examined histologically and immunohistochemically, using photon microscopy. The pathologist reported the presence of a combination of fibroblasts and undifferentiated mesenchymal cells arranged in a storiform pattern. Immunohistochemistry was performed on the tissue using specific antibodies for several proliferation (Ki-67) and differentiation (S-100, CD-34, CD-68, pan-keratin, desmin and smooth muscle actin-SMA) markers. Positive reaction was observed for S-100, Ki-67, CD-68, desmin and SMA (limited) but not for CD-34 or cytokeratin. © 2007 Blackwell Verlag.

Human sperm DNA damage may have adverse effects on reproductive outcome. Infertile men possess substantially more spermatozoa with damaged DNA compared to fertile donors. Although the extent of this abnormality is closely related to sperm function, the underlying etiology of ensuing male infertility is still largely controversial. Both intra-testicular and post-testicular events have been postulated and different mechanisms have been proposed to explain the presence of damaged DNA in human spermatozoa. Three among them, i.e. abnormal chromatin packaging, oxidative stress and apoptosis, are the most studied and discussed in the present review. Furthermore, results from numerous investigations are presented, including our own findings on these pathological conditions, as well as the techniques applied for their evaluation. The crucial points of each methodology on the successful detection of DNA damage and their validity on the appraisal of infertile patients are also discussed. Along with the conventional parameters examined in the standard semen analysis, evaluation of damaged sperm DNA seems to complement the investigation of factors affecting male fertility and may prove an efficient diagnostic tool in the prediction of pregnancy outcome. © 2007 Angelopoulou et al; licensee BioMed Central Ltd.

Purpose: To investigate the effects of male ageing on DNA fragmentation and chromatin packaging in the spermatozoa of oligoasthenoteratozoospermic (OAT) patients. Methods: Sixty-one OAT patients and 49 men with proven fertility (controls) were included in the present study. DNA fragmentation was detected by terminal deoxynucleotidyl transferase-mediated dUTP-nick end labelling (TUNEL) assay, while chromatin packaging was assessed by chromomycin A3 (CMA3) staining. Results: In the patient group, semen volume, percentage of normally shaped spermatozoa and sperm motility decreased significantly (P0.05). Conclusion: Increased age in OAT patients is associated with an increase in sperm concentration, DNA fragmentation and poor chromatin packaging, as well as a decline in semen volume, sperm morphology and motility. © 2007 Springer Science+Business Media, LLC.

Carriers of balanced translocations usually carry alterations in gene sequences, which lead to dysfunction during early and late embryogenesis. Related spatial rearrangement causes either cumulative delay in cell cycles and/or anomalies in transcription and translation. This has also an important impact at the time of genomic activation, the longest cell cycle of preimplantation development. Carrier patients may be affected either with primary infertility or by repeated miscarriages [Hum. Reprod. 12 (1997) 2019.]. Assuming that a fraction of the germ cells is karyotypically normal, these patients would greatly benefit from efficient procedures for generation and use of breakpoint-specific DNA hybridisation probes in preconception and preimplantation genetic diagnosis (PGD) after polar body or blastomere biopsy of the embryos. The objective of this research was to design an approach of patient-specific probes for preimplantation diagnosis of chromosome translocations and which could be used eventually to select chromosomally normal embryos from balanced or unbalanced interphase cells prior to their transfer to the mother's womb. This approach was used for a couple, where the female partner was a carrier of a balanced translocation 46,XX,t(4;12)(p16.1;q24.31). First, BAC/PAC clones were chosen from specific chromosome bands from the genome sequence that hybridise adjacent to the chromosomal breakpoints or span them. Then, the probes and hybridisation conditions were optimised using unrelated normal amniocytes, lymphoblastoid cells and lymphocytes from the carrier to increase hybridisation signal intensity and decrease background. Finally, the probes were tested on target cells before they were used for mimicking preconception or preimplantation genetic diagnosis. Three slides were analysed blindly from a normal karyotype, an unbalanced and a balanced translocation. A total of 78 cells were analysed of which in the slide A 19/22 (86%) were found to be unbalanced, in slide B 25/31 (81%) were normal and in slide C 21/25 (84%) were balanced. Thus, it was demonstrated that cells with known structural abnormalities could be detected, based on hybridisation of breakpoint spanning bacterial artificial chromosome (BAC) DNA probes in interphase cells. © 2005 Elsevier SAS. All rights reserved.

Determining sexual fate is an integral part of reproduction, used as a means to enrich the genome. A variety of such regulatory mechanisms have been described so far and some of the more extensively studied ones are being discussed. For the insect order of Hymenoptera, the choice lies between uniparental haploid males and biparental diploid females, originating from unfertilized and fertilized eggs accordingly. This mechanism is also known as single-locus complementary sex determination (sICSD). On the other hand, for Dipterans and Drosophila melanogaster, sex is determined by the ratio of X chromosomes to autosomes and the sex switching gene, sxl. Another model organism whose sex depends on the X:A ratio, Caenorhabditis elegans, has furthermore to provide for the brief period of spermatogenesis in hermaphrodites (XX) without the benefit of the "male" genes of the sex determination pathway. Many reptiles have no discernible sex determining genes. Their sexual fate is determined by the temperature of the environment during the thermosensitive period (TSP) of incubation, which regulates aromatase activity. Variable patterns of sex determination apply in fish and amphibians. In birds, while sex chromosomes do exist, females are the heterogametic (ZW) and males the homogametic sex (ZZ). However, we have yet to decipher which of the two (Z or W) is responsible for the choice between males and females. In mammals, sex determination is based on the presence of two identical (XX) or distinct (XY) gonosomes. This is believed to be the result of a lengthy evolutionary process, emerging from a common ancestral autosomal pair. Indeed, X and Y present different levels of homology in various mammals, supporting the argument of a gradual structural differentiation starting around the SRY region. The latter initiates a gene cascade that results in the formation of a male. Regulation of sex steroid production is also a major result of these genetic interactions. Similar observations have been described not only in mammals, but also in other vertebrates, emphasizing the need for further study of both normal hormonal regulators of sexual phenotype and patterns of epigenetic/ environmental disruption. © 2006 Manolakou et al; licensee BioMed Central Ltd.

Seventy two rats underwent small bowel resection followed by end-to-end anastomosis. The octreotide group consisted of 36 rats treated with octreotide (subcutaneously, 7 mug/k-/day, in two equal doses), and the control group consisted of 36 rats treated with the same volume saline. Twelve animals from each group were re-explored on the 4th, 8th and l5th postoperative day. Leakages, adhesions, obstructions were the clinical postoperative findings identified and recorded. Anastomotic bursting pressures were measured. Histochemical studies included haematoxylin-eosin and Van Gieson staining techniques and focused on the microscopic characterization of the healing process. Adhesions, leakages and obstructions were not different between octreotide and control groups. Anastomoses of the octreotide group had increased bursting pressures on the 8th and the l5th day (p < .05, p < .05, respectively). Regarding the histogical results, on the 8th day the octreotide group compared to the control group, showed healing in more layers (p < .05), increased bright red collagen fibers and quantity of fibroblasts (p < .05), and on the 15th day, the octreotide group showed fewer gaps (p < .05), increased bright red collagen fibers and quantity of fibroblasts (p < .05). In this experimental model, it appeared that octreotide does not impair heating of small bowel anastomoses, but in contrast, there is some evidence that it enhances healing on the 8th and the 15th postoperative day.

Octreotide is a somatostatin analog introduced for clinical use that inhibits the growth of various tumors in rats. This study investigates liver pathology after octreotide treatment following partial (2/3) hepatectomy in rats. Thirty rats, weighing 250-300 g underwent partial hepatectomy and were divided in to two groups. Group A (N = 25) received octreotide subcutaneously [2 mug Sandostatin (Sandoz) in 1 ml normal saline every 12 hr for 15 days]. Group B (N = 5) was injected with 1 ml normal saline subcutaneously every 12 hr for the same time period; animals in this group were used as controls. At the end of the experiment rats were sacrificed and liver tissue was obtained for pathologic examination. Liver sections from group A (octreotide administration) showed extensive cholangiolar and fibrous tissue proliferation in the hepatectomy area, and hypertrophy and swelling of Kupffer cells in the liver parenchyma. Sections from the hepatectomy surface from group B (controls) displayed signs of liver regeneration. Proliferation activity (Ki-67(+) cells) was higher in the cholangiolar epithelium in group A and in hepatocytes in group B. In conclusion, the results of this study show that octreotide inhibits liver regeneration, which occurs after partial hepatectomy in rats and enhances hyperplasia of cholangiolar and fibrous tissue.

Editor—Centromeres are the specialised regions of chromosomes that ensure normal transmission of sister chromatids to each daughter cell after mitosis. Alphoid satellite DNA sequences, consisting of tandemly repeated ≅170 bp units present at all human centromeres, contain the information necessary for centromeric function,1 despite the observation of marker chromosomes lacking detectable alphoid DNA.2-4 Dicentric chromosomes, resulting from some Robertsonian or Y;autosome translocations, represent a valuable tool for studying factors which ensure that only one of the centromeres is mitotically active, thus preventing chromosomal bridges and breakages to occur at anaphase. It has been shown that centromeric inactivation is largely an epigenetic event5 based on the ability of alphoid sequences to bind specific centromeric proteins (CENPs), particularly the CENP-C protein which is necessary for proper kinetochore assembly.6 Here we describe a de novo dicentric Y;13 (q12;p11) translocation chromosome found in a severely oligozoospermic patient and exhibiting a variable pattern of centromeric activity, as defined by the localisation of the primary constriction. This patient was a healthy, 20 year old, West Indian man who referred himself to the laboratory because of ejaculation problems. Sperm analysis showed first an abnormal viscosity of ejaculate which took as long as six hours to liquefy and, second, an extreme oligozoospermia at 0.1 million spermatozoa/ml. Biochemical parameters of the semen were normal. Further sperm counts showed a similar constitution of ejaculate and testicular impairment varying from severe oligozoospermia to azoospermia or cryptozoospermia. Testicular biopsy was not proposed. Karyotyping was performed on blood lymphocytes by conventional cytogenetic methods using R and G banding and BrdU incorporation after cell culture synchronisation. It showed an apparently balanced reciprocal translocation between the distal region of the Y chromosome long arm and the short arm of one chromosome 13. Paternal chromosomes were normal. Curiously, this abnormal …

An expression cassette carrying 426 basepairs of the rat probasin (PB) gene promoter and 28 basepairs of 5’-untranslated region is sufficient to target the expression of the bacterial chloramphenicol acetyltransferase (CAT) gene specifically to the prostate in transgenic mice. The PB-CAT transgene was expressed in three of five (60%) independent lines of mice, and this expression, as reported previously for the endogenous rat gene, was male specific, restricted primarily to the lateral, dorsal, and ventral lobes of the prostate, with only very low levels of CAT activity detected in the anterior prostate and seminal vesicles. The developmental and hormonal regulation of the transgene also paralleled that reported for the rat gene, with a 70-fold increase in CAT activity in the mouse prostate observed between 2-7 weeks of age, a time corresponding to sexual maturation. PB-CAT activity in the prostate declined after castration to 3.5% of the precastration level, and the CAT activity in castrated males approached precastration levels when mice were supplemented with testosterone. Transgene expression in castrated males was not induced by dexamethasone. Coinjection of PB-CAT with a chicken lysozyme gene matrix attachment region resulted in their cointegration and further restricted the pattern of PB-CAT to the dorsolateral prostate, with suppressed expression observed in the ventral prostate. These studies demonstrate that a minimal rat probasin promoter can target heterologous gene expression specifically to the prostate in a developmentally and hormonally regulated fashion.