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At least 235 records · Page 13Linked to original sources
PubMed2001

Molecular approaches to contraceptive development.

The next generation of contraceptives will be based on the identification of novel molecules essential for reproductive processes and will rely on the refinement of older as well as newer technologies. Functional analysis of naturally occurring reproductive genetic disorders and creation of mice null for specific genes would greatly assist in the choice of genetic targets for contraceptive development. Structure-based design of drugs as exemplified by the preparation of an orally active non-peptide gonadotropin releasing hormone (GnRH) would revolutionize drug formulation and delivery for a peptide analogue. This review examines some of the molecular targets that may change contraceptive choices in the future.

Algorithms↗
PubMed2006

Isolation of major histocompatibility complex Class I genes from the tammar wallaby (Macropus eugenii).

The major histocompatibility complex (MHC) plays an essential role in the adaptive immune system of vertebrates through antigen recognition. Although MHC genes are found in all vertebrates, the MHC region is dynamic and has changed throughout vertebrate evolution, making it an important tool for comparative genomics. Marsupials occupy an important position in mammalian phylogeny, yet the MHC of few marsupials has been studied in detail. We report the isolation and analysis of expressed MHC Class I genes from the tammar wallaby, a model marsupial used extensively for the study of mammalian reproduction, genetics, and immunology. We determined that there are at least 11 Class I loci in the tammar genome and isolated six expressed Class I sequences from spleen and testes cDNA libraries, representing at least four loci. Two of the Class I sequences contain substitutions at sites known to be important for antigen binding, perhaps impacting their ability to bind peptides, or the types of peptide to which they bind. Phylogenetic analysis of tammar wallaby Class I sequences and other mammalian Class I sequences suggests that some tammar wallaby and red-necked wallaby loci evolved from common ancestral genes.

Amino Acid Sequence↗
PubMed2004

The effect of climate on the phenology, acorn crop and radial increment of pedunculate oak (Quercus robur) in the middle Volga region, Tatarstan, Russia.

Our data, collected in the extreme east of Europe, show that a significant biological effect of climate change has been experienced even in territories where temperature increase has been the lowest. This study documents the climatic response of pedunculate oak (Quercus robur) growing near its north-eastern limits in Europe. It demonstrates the potential of oak trees in old-growth forest to act as proxy climate indicators. Many factors may influence the temporal stability of the growth-climate, acorn crop-climate and first leafing-climate relationships. Climate data, climatic fluctuations, reproduction, genetics and tree-age may relate to this instability. Our results stress that an increase in climate variability or climatic warming resulting from warmer winters or summers could affect the oak population in eastern Europe in a similar way to that in western Europe. These findings, from remnants of oak forest in the middle Volga region of Russia, allow a further understanding of how species could be affected by future climates.

Acclimatization↗
PubMed1987

Establishment of a collaborative university-commercial maternal serum alpha-fetoprotein screening program: a model for tertiary center outreach.

Expansion of the availability of tertiary level services beyond major medical centers has proved to be a major problem in health care delivery. Routine maternal serum alpha-fetoprotein screening for neural tube defects, and now also for aneuploidy, is a classic example in which there has been a schism between the clinical expertise to manage such a program within a tertiary level reproductive genetics center and the ability to reach patients in regions that are not routinely accessible to the tertiary center. To address this problem we have established a collaborative university-commercial laboratory statewide maternal serum alpha-fetoprotein program that we believe can serve as a model for others. In the first 4 months since its implementation, the program volume has increased tenfold. The detection frequency of neural tube defects has been consistent with that of other programs (1/1690). Three aneuploid karyotypes were found in amniotic fluid of 118 women less than 30 years old who underwent genetic amniocentesis because of a low maternal serum alpha-fetoprotein value. Thus we conclude that: the establishment of a joint university-commercial maternal serum alpha-fetoprotein program may provide a successful model for efficient tertiary center outreach, assessment of our data suggests that a population at high risk for abnormal fetuses can be identified among patients not generally considered at high risk, low maternal serum alpha-fetoprotein values may likely be a more important public health measure than high ones.

Adolescent↗
PubMed1992

Effects of dimethyl sulfone (DMSO2) on early gametogenesis in Caenorhabditis elegans: ultrastructural aberrations and loss of synaptonemal complexes from pachytene nuclei.

The free-living nematode Caenorhabditis elegans has been used extensively for studies in developmental and reproductive genetics. Recently, toxicologic studies have been initiated using specific sex chromosome mutations. In the present study, high incidence of male (him) mutants, him-5 and him-8, were treated with dimethyl sulfone (DMSO2), the primary metabolite of dimethyl sulfoxide (DMSO). In addition to differential effects on X-chromosome nondisjunction, loss of viability and fertility were observed. Much lower concentrations of DMSO2 were required to elicit the same aberrational effects characteristic of DMSO (1); thus, the toxicity of the former was significantly more potent. The observed decrease in life span was associated with senescent morphology of meiotic prophase nuclei, such that nuclei from young and old specimens could not be differentiated. Aging in oocytes at pachytene is characterized by nucleo-cytoplasmic aberrations, increased density of the nucleoplasm and cytoplasm, and decrease in numbers of mitochondria. Increasing concentrations of DMSO2 resulted in a corresponding decrease in fertility and increased production of abnormal gametes. At DMSO2 concentrations higher than 1.0%, synaptonemal complexes (SC) were absent from pachytene nuclei; thus, effective pairing and segregation of homologous chromosomes was prohibited. Since the SC is essential for regulating pairing and subsequent separation of bivalents, the lack of an SC explains the loss of fertility, due to the production of unbalanced gametes, observed in DMSO2-treated specimens.

Animals↗
PubMed2005

Isochromosome of Yp in a man with Sertoli-cell-only syndrome.

OBJECTIVE: To address phenotype/genotype correlation in a man with i(Y)(p10). DESIGN: Case report. SETTING: University-based reproductive genetics laboratory. PATIENT(S): A 27-year-old azoospermic man with i(Y)(p10), relatively normal stature, and testicular Sertoli-cell-only syndrome. INTERVENTION(S): Testicular biopsy, cytogenetic study, Y-chromosome deletion mapping analysis, fluorescence in situ hybridization (FISH). MAIN OUTCOME MEASURE(S): Expression of Y-chromosome genes. RESULT(S): We have identified one azoospermic man with i(Y)(p10) of 312 Taiwanese men presenting with a severe spermatogenic defect. Y-chromosome deletion mapping analysis confirmed deletions of all Yq sequences, including a putative growth controlling gene. Fluorescence in situ hybridization (FISH) analysis showed duplication of Yp material. The patient had normal stature considering midparental height. He also had no germ cells in the testicular tissue (Sertoli-cell-only syndrome) resulting from the loss of azoospermia factor in Yq. CONCLUSION(S): Among structural rearrangements of the Y-chromosome, the isochromosome of Yp occurs very rarely. This case is the first reported case of an isochromosome Yp with a detailed description of testicular histology and body height.

Adult↗
PubMed2005

Breast cancer risk in the WHI study: the problem of obesity.

In the climacteric, about 40% of the women have occult breast tumors the growth of which may be stimulated by hormones. Many genetic, reproductive and lifestyle factors may influence the incidence of breast cancer. Epidemiological data suggest that the increase in the relative risk (RR) of breast cancer induced by hormone replacement therapy (HRT) is comparable with that associated with early menarche, late menopause, late first birth, alcohol consumption, etc. One of the most important risk factors is obesity which exceeds the effect of HRT by far, and in overweight postmenopausal women the elevated risk of breast cancer is not further increased by HRT. As in the WHI study the majority of women was overweight or obese, this trial was unsuitable for the investigation of breast cancer risk. In the women treated with an estrogen/progestin combination, the RR of breast cancer rose only in those women who have been treated with hormones prior to the study, suggesting a selection bias. In the women not pretreated with hormones, it was not elevated. In the estrogen-only arm of the WHI study, there was no increase but a steady decrease in the RR of breast cancer during 6.8 years of estrogen therapy. This result was unexpected, as estrogens are known to facilitate the development and growth of breast tumors, and the effect is enhanced by the addition of progestins. Obese women are at high risk to develop a metabolic syndrome including insulin resistance and hyperinsulinemia. In postmenopausal women, elevated insulin levels are not only associated with an increased risk for cardiovascular disease, but also for breast cancer. This might explain the effects observed in both arms of the WHI study: HRT with relative low doses of estrogens may improve insulin resistance and, hence, reduce the elevated breast cancer risk in obese patients, whereas this beneficial estrogen effect may be antagonized by progestins. The principal options for the reduction of breast cancer risk in postmenopausal women are the prevention of overweight and obesity to avoid the development of hyperinsulinemia, the medical treatment of insulin resistance, the use of low doses of estrogens and the reduction of exposure to progestins. The latter might include long-cycles with the sequential use of appropriate progestins every 3 months for 14 days. There are large inter-individual variations in the proliferative response to estrogens of the endometrium. Control by vaginalsonography and progestin challenge tests may help to identify those women who may be candidates for low-dose estrogen-only therapy.

Body Weight↗
PubMed2000

Expression of the platelet-activating factor receptor in human spermatozoa: differences in messenger ribonucleic acid content and protein distribution between normal and abnormal spermatozoa.

OBJECTIVE: To determine the expression and distribution of the platelet-activating factor (PAF) receptor in normal and abnormal specimens of human spermatozoa. DESIGN: Prospective analysis of membrane-bound PAF receptors by immunofluorescence and PAF receptor messenger RNA by quantitated reverse transcription-polymerase chain reaction in normal and abnormal spermatozoa. SETTING: University-based reproductive genetics laboratory. PATIENT(S): Men undergoing routine semen analysis. INTERVENTION(S): Normal and abnormal spermatozoa were exposed to rabbit anti-PAF receptor antibody, fluorescein isothiocyanate-conjugated goat anti-rabbit antibody, and fluorescent microscopy or subjected to RNA isolation by acid-phenol extraction and quantitated (MIMIC Construction Kit [Clontech Laboratories, Inc., Palo Alto, CA]) reverse transcription-polymerase chain reaction. MAIN OUTCOME MEASURE(S): Fluorescent intensities at six locations along spermatozoa (end piece, principal tail, midpiece, neck, proximal head, and acrosomal region) and PAF receptor expression (messenger RNA) levels. RESULT(S): Immunofluorescence demonstrated a significant difference in PAF receptor distribution between normal and abnormal human spermatozoa, specifically at the neck region. Additionally, abnormal spermatozoa were found to have statistically significantly more PAF receptor messenger RNA than normal spermatozoa. CONCLUSION(S): Platelet-activating factor receptor expression and distribution are significantly altered in abnormal spermatozoa and this may be the result of some defect in gene transcription.

Animals↗
PubMed2002

Presence of DAZL transcript and protein in mature human spermatozoa.

OBJECTIVE: To identify the DAZL transcript and protein location in human spermatozoa. DESIGN: In vitro experiment. SETTING: University-based reproductive genetics laboratory. PATIENT(S): A fertile volunteer. INTERVENTION(S): Reverse transcription-polymerase chain reaction (RT-PCR), Western blot, and immunostaining for DAZL. MAIN OUTCOME MEASURE(S): Expression of DAZL in human spermatozoa. RESULT(S): The DAZL-specific primers yield a 128 bp product in ejaculate. A protein of approximately 33.5 kDa was detected by Western blot analysis. Immunofluorescence staining showed strong homogeneous staining in the midpiece of spermatozoa and weak staining in the principal piece. A speckled-type distribution was found in the head region. CONCLUSION(S): The DAZL transcript and protein are present in human spermatozoa. The roles of DAZL protein in sperm motility and in the sperm-oocyte interaction await further investigation.

Amino Acid Sequence↗
PubMed1998

Chromosomal aberrations and alkaline comet assay in families with habitual abortion.

Within the pathology of human reproduction, genetic abnormalities play an important role in spontaneous abortions. This paper describes the morphologic, karyotypic features of a consecutive series of singleton spontaneous abortions collected as part of this study and also reports the application of the alkaline comet assay to assess levels of DNA damage in 31 couples comprised of 13 control couples and a patient group of 18 couples with a history of more than one fetal loss. For the cytogenetic analyses, the conventional lymphocyte culture method was applied to all subjects. In this analysis, two women with habitual abortion were determined to carry balanced chromosomal translocation. The alkaline comet assay (single cell gel electrophoresis technique) was applied also to lymphocytes. The comparison of the results of alkaline comet assay in patient and control individuals showed a significant difference in the number of damaged cells. The cells were evaluated according to their grades of damage as: normal (undamaged-no migration), limited migration, (at low damage level) and extensive migration (comet imaged cells-with increasing numbers of breaks, DNA pieces migrate freely into the tail forming a comet image). The frequency of limited migrated and extensive migrated cells in the women in the patient group were higher than in the women in the control group (p<0.001). However, all above parameters were equal for husbands in both the control and patient group (p>0.05).

Abortion, Habitual↗
PubMed2006

Wildlife biomaterial banking in Africa for now and the future.

The Wildlife Biological Resource Centre (wBRC) together with its partners in BioBank SA, have created a Biological Resource Bank (BRB) that is dedicated to the acquisition, processing, banking, using and provision of biomaterials to the scientific and conservation industry that are viable, diverse and representative of southern Africa's wildlife populations. Banked biomaterials include tissue such as muscle, kidney, fat, liver, embryos, fibroblast cultures, blood, sperm, hair, egg shells and other tissue, fluids and cells. Biomaterials are made available for research, biodiversity conservation and biotechnology development. Biomaterials are used in many disciplines, including genetics, reproduction, nutrition, and disease studies. Biomaterials from selected species are also useful for the detection and monitoring of Persistent Organic Pollutants and other potentially harmful substances found in the environment. Biomaterials are made available to third parties with prior consent from the biomaterials "owner" and only after the signing of a customised Material Transfer Agreement (MTA) or Cooperative Research and Development Agreement (CRADA). The training of staff from National and Provincial Game Reserves, Zoological Gardens, Animal Breeders and laboratories is carried out on a regular basis with the aim of securing good quality biomaterials. Sampling kits are made available to persons tasked with the collection of wildlife biomaterials. The Biobank SA consortium acts as an integrated resource centre linking partner collections. The consortium's operational arm, namely wBRC, is active in the development of relevant policy, regulations and legislation pertaining to biomaterials, including Access and Benefit Sharing systems. The main sponsor of the project is the Department of Science and Technology, National Government of South Africa.

Africa↗
PubMed1999

Does winter darkness in the Artic protect against cancer? The melatonin hypothesis revisited.

The melatonin hypothesis states that excess exposure to environmental light may contribute to breast cancer risks via impaired pineal secretion of melatonin. A corollary, not considered previously, is that a net annual increase in oncostatic melatonin would be expected in persons who experience a light deficit during extended winter darkness periods; thus, hormone-dependent cancers should occur less frequently in people who reside north, rather than south, of the Arctic circle. Consistent with our prediction, epidemiological data indicate uniformly low risks for hormone-dependent cancers in the Arctic. The available literature on genetic, reproductive, nutritional, life-style, and environmental risk factors provides no obvious clues to the observed cancer patterns. Moreover, diurnal and 24-hour melatonin concentrations in humans living in Arctic regions were reported as high in November-January, when light intensity is low. Since these observations are consistent with our corollary and the associated prediction, we suggest that research on a melatonin-inhibited carcinogenesis in the low-risk populations of the Arctic should be pursued.

Alaska↗
PubMed2000

Presence of ribonucleic acid in human spermatozoa: differences in content between normal and abnormal spermatozoa.

OBJECTIVE: Our purpose was to determine whether there are any differences in total ribonucleic acid content between normal and abnormal human spermatozoa. STUDY DESIGN: Spermatozoa were obtained from men undergoing routine semen analysis at a university-based reproductive genetics laboratory. Specimens were classified as normal or abnormal according to World Health Organization criteria. Total ribonucleic acid was removed by acid-phenol extraction, and ribonucleic acid expression levels were determined by spectrophotometric analysis. RESULTS: Abnormal spermatozoa were found to have significantly more ribonucleic acid (0.14 +/- 0.02 mg/10(6) spermatozoa) than normal spermatozoa (0.05 +/- 0.01 mg/10(6) spermatozoa; P <.001). CONCLUSION: Ribonucleic acid content is significantly altered in abnormal spermatozoa, and this alteration may be the result of some defect in the posttranscriptional pathway.

Humans↗
PubMedDate not supplied

Laser technologies in toxicopathology.

One of the main concepts in toxicology and risk assessment is the identification of compounds with the least toxicity, gaining increased understanding of the underlying mechanisms of efficacy and toxicity so as to accelerate the early selection of compounds for development. For this purpose, "cutting-edge" technologies, such as flow cytometry (FC), laser scanning cytometry (LSC) and confocal laser scanning microscopy (CLSM), have proved to be valuable tools. FC, LSC and CLSM have been successfully applied in a wide range of areas within toxicology and research including genetics, reproduction, dermatology, pathology and target organ toxicity. The scope of this paper is to give a short overview of the usefulness of the different laser applications. Specific examples of the impact of these technologies will be presented or can be found in the references. Flow cytometry methods have been successfully applied in immunophenotyping, micronuclei scoring, polyploidy determination, apoptosis and cell cycle evaluation, cell proliferation and quantification. A three-parameter FC method for the analysis of testicular toxicity has also been established as an alternative to traditional histopathological methods. This method allows a large number of cells to be analysed in a short time and provides quantitative values to evaluate testicular damage in the rat. Laser scanning cytometry has been used in our unit for rat blood cell immunophenotyping, tumor proliferation, apoptosis and cell cycle analysis on minipig and rat skin and cardiac cells identification. The wide range of applications that can be applied with the LSC shows the enormous potential of this technology in research and development. Confocal laser scanning microscope was used in our laboratory, in collaboration with the research department, to investigate the mechanisms underlying hepatic lesions found in dogs, to detect fibrinogen influx into rat lung, to explore the mechanism of eye toxicity and to quantify dopaminergic fibers in brain sections. Integrating these technologies within discovery pathology allowed us to understand disease processes with respect to their development and subsequent consequences. It contributes to descriptive pathologic diagnostic and allows a productive interaction with research and development. These technologies offer a range of novel applications and have been shown to be useful tools in terms of specificity, sensitivity, reliability, rapidity and quantification. Expertise in cutting-edge technologies, pathology and cell and molecular biology is essential to a successful and flexible interaction across all therapeutic areas in drug discovery.

Animals↗
PubMed2000

Origin and persistence of the mitochondrial genome.

The mitochondrial genome comprises a circular, histone-free 'chromosome' of 16.6 kb of DNA, present in one or more copies in every mitochondrion. This chromosome has been tightly conserved for more than half a billion years, coding in every multicellular animal so far investigated, both vertebrate and invertebrate: (i) the same 13 protein subunits required for oxidative phosphorylation; (ii) a component of each of the two mitochondrial ribosome subunits; and (iii) the 22 transport RNAs present within the mitochondrion. Exons on the circle are tightly packed, with no spacing introns. Mitochondrial DNA is histone-free, has limited repair ability, and has a relatively high mutation-fixation rate. Inheritance is cytoplasmic and maternal, with epidemiological evidence (namely the familial distribution of polymorphisms) indicating that recombination with mtDNA of paternal origin is exceedingly rare. Thus the maintenance and evolution of mtDNA (its remarkably successful symbiotic persistence with the nuclear genome) has been essentially asexual. The machinery for homologous recombination is present in mitochondria of at least some species, however, and it might be surprising if it did not occur between circles in some circumstances. By bringing together the fields of mitochondrial biochemistry, evolutionary genetics, reproductive physiology, and neuromuscular medicine in focusing on the inheritance of normal and abnormal human mtDNA, we can hope to better understand the forces behind this genome's inheritance and what might be required of ovarian function to satisfy its accurate persistence over millions of years. Clinically we can hope also for a better understanding of ooplasmic factors in human fertility and in the wide manifestations of mitochondrial genomic disease.

Animals↗
PubMed2000

Parental decision-making differences between patients in two healthcare systems for choroid plexus cysts.

We evaluated the medical-sociological implications of parental perception of risk and decision-making choices for prenatally ascertained choroid plexus cysts (CPC) between two obstetric populations. The Wayne State University (WSU) Reproductive Genetics database and the Madigan Army Medical Center (MAMC) experience were reviewed to compare the rates of aneuploidy and invasive testing for cases with CPC. Aneuploidy rates were compared between those with isolated CPC, CPC with advanced maternal age (AMA), and CPC associated with multiple anomalies. In the WSU cohort 186 cases were identified, of whom 27 (15%) declined invasive fetal testing. In the remaining 159 cases, aneuploidy was present in 2/132 (1.5%) isolated CPC, 3/11 (27%) CPC with AMA, and 15/16 (93%) CPC with multiple anomalies. In the MAMC cohort 107 cases were identified, of whom 99 (92%) declined invasive fetal testing. No aneuploidy cases were found in the 3/12 AMA cases or 5/95 non-AMA cases that underwent amniocentesis. The two cases of aneuploidy with isolated CPC cannot be ignored, and provide an estimated attributable risk of at least 0.8%, a higher risk than 38 years of age. However, the parental sociologic context may be as important for decision-making as the genetic-prognostic risk.

Abnormalities, Multiple↗