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P Dandekar

Publications and source records attributed to P Dandekar.

16 recordsLinked to original sources
PubMed2001

p62/p56 are cortical granule proteins that contribute to formation of the cortical granule envelope and play a role in mammalian preimplantation development.

The purpose of this study was to identify specific cortical granule protein(s) that form the cortical granule envelope and examine their role(s) in fertilization and preimplantation development. The polyclonal antibody A-BL2 was used to show that the cortical granules of mice, rats, hamsters, cows, and pigs contain a pair of proteins designated p62/p56. These proteins are released from hamster cortical granules at fertilization and contribute to formation of the cortical granule envelope, an extracellular matrix present in the perivitelline space of fertilized mammalian oocytes. P62/p56 were present in the cortical granule envelope throughout preimplantation development and were found in blastomere cortices of 4-cell to blastocyst stage embryos. Hamster oocytes fertilized in vivo in the presence of A-BL2 were all monospermic, suggesting that p62/p56 do not function in blocking polyspermy. Likewise treatment of morula to blastocyst stage hamster embryos with A-BL2 had no effect on the implantation of blastocysts. However, cleavage divisions were inhibited in vivo in a dose-dependent manner when fertilized oocytes or 2-cell embryos were treated with A-BL2. Inhibition of cell division was more pronounced in 2-cell embryos than in fertilized oocytes. This study identifies p62/p56 as cortical granule proteins that contribute to the formation of the cortical granule envelope and further supports the idea that after their release at fertilization, p62/p56 function in regulating preimplantation development at the level of oocyte and blastomere cleavage.

Animals↗
PubMed1999

Antral histopathological changes in acid peptic disease associated with Helicobacter pylori.

The histopathology of the antral mucosa of patients with acid peptic disease was studied in relation to Helicobacter pylori infection. Three hundred and fifty-five patients underwent gastroscopy and biopsy on 443 occasions. During each gastroscopy, two antral samples were taken for Rapid Urease Test (RUT) for H. pylori and two antral samples for histopathology. Haematoxylin and Eosin and modified Giemsa stained sections were studied. Histopathological changes in the antrum and the density of H. pylori were graded according to the Sydney System criteria. There was a significant association between the RUT and histology results for detection of H. pylori. The overall prevalence of H. pylori was 61.4% with a maximum incidence in the third and fourth decades of life, and an equal sex distribution. H. pylori colonisation was seen in 90.7% of patients with duodenal ulcer, 66.7% with gastric ulcer and 44.3% with non-ulcer dyspepsia. H. pylori colonisation was associated with more severe antral chronic active gastritis, lymphoid follicles, intestinal metaplasia and dysplasia. Elimination of H. pylori by treatment with anti-H. pylori regimens resulted in regression of the changes.

Adolescent↗
PubMed1998

Spectral imaging in preconception/preimplantation genetic diagnosis of aneuploidy: multicolor, multichromosome screening of single cells.

PURPOSE: Our purpose was to evaluate the utility of spectral imaging for multicolor, multichromosome enumeration in human interphase cell nuclei. METHODS: Chromosome-specific probes labeled with different fluorochromes or nonfluorescent haptens were obtained commercially or prepared in-house. Metaphase spreads, interphase lymphocytes, or blastomeres cells were hybridized with either 7 or 11 distinctly different probes. Following 46 hr of hybridization, slides were washed and detected using either a filter-based quantitative image processing system (QUIPS) developed in-house or a commercial spectral imaging system. RESULTS: The filter-based fluorescence microscope system is preferred for simultaneous detection of up to seven chromosome targets because of its high sensitivity and speed. However, this approach may not be applicable to interphase cells when 11 or more targets need to be discriminated. Interferometer-based spectral imaging with a spectral resolution of approximately 10 nm allows labeling of chromosome-specific DNA probes with fluorochromes having greatly overlapping emission spectra. This leads to increases in the number of fluorochromes or fluorochrome combinations available to score unambiguously chromosomes in interphase nuclei. CONCLUSIONS: Spectral imaging provides a significant improvement over conventional filter-based microscope systems for enumeration of multiple chromosomes in interphase nuclei, although further technical development is necessary in its application to embryonic blastomeres. When applied to preconception/preimplantation genetic diagnosis, presently available probes for spectral imaging are expected to detect abnormalities responsible for 70-80% of spontaneous abortions caused by chromosomal trisomies.

Aneuploidy↗
PubMed1997

Adjunctive growth hormone during ovarian hyperstimulation increases levels of insulin-like growth factor binding proteins in follicular fluid: a randomized, placebo-controlled, cross-over study.

GH increases circulating insulin-like growth factor I (IGF-I), which can promote the growth and differentiated function of ovarian granulosa and theca cells. Reported studies of GH as an adjunct to menotropin stimulation in women, largely those with ovarian dysfunction, have not consistently shown a benefit of GH, despite increases in serum and follicular fluid IGF-I. We hypothesized that changes in intrafollicular IGF-binding proteins (IGFBPs), which can antagonize IGF actions on granulosa cells, may underlie the inconsistent effects of GH. In the present study of GH, administered in double-blind, placebo-controlled, cross-over fashion to regularly cycling women undergoing in vitro fertilization, we found that follicular fluid levels of IGFBP-1, -3, and -4 and serum levels of IGFBP-3, as well as follicular fluid and serum IGF-I, were significantly increased in the GH-treated cycles, when compared with the placebo cycle of the same patient. We suggest that the net increase in intrafollicular IGFBPs in GH cycles may mitigate the potential beneficial effect of increased IGF-I.

Adult↗
PubMed1995

The effects of anaemia on heart, placenta and body weight, and blood pressure in fetal and neonatal rats.

1. Reports that maternal anaemia in pregnancy is associated with a greater placental: birth weight ratio, which predisposes towards high postnatal blood pressure in the human, led us to examine the effects of maternal anaemia during pregnancy on placental size, fetal and neonatal growth, and blood pressure development in the rat. 2. Nutritional anaemia was induced in female rats prior to mating and maintained throughout pregnancy and up until weaning of the pups. Fetuses were studied at 20 days of gestation (E20). Pups were studied on postnatal days 20 (P20) and 40 (P40), having been weaned onto normal rat chow at 21 days. 3. In the anaemic group placental: fetal body weight ratios were lower compared with controls. Body weights at all ages were lower in the anaemic group than in controls, despite a greater rate of growth in the anaemic group between P20 and P40. 4. At P20 heart weights of the anaemic group were almost twice that of controls, suggesting an alteration in their cardiovascular development. However, paradoxically, the systolic blood pressure of the anaemic group was lower than that of controls. 5. By P40 the systolic blood pressure of the anaemic group (136 +/- 3 mmHg) had increased and was greater than that in control pups (126 +/- 3 mmHg). 6. In conclusion, we have shown that there is a pronounced postnatal rise in systolic blood pressure associated with maternal anaemia during pregnancy, which is not related to a greater placental: birth weight ratio. Before weaning, anaemic pups have a lower systolic blood pressure than controls and there is an important association between the rate of postnatal growth and blood pressure.

Anemia↗
PubMed1995

Perivitelline space of marsupial oocytes: extracellular matrix of the unfertilized oocyte and formation of a cortical granule envelope following the cortical reaction.

The purpose of this study was to characterize the structure of the vestments surrounding unfertilized and cortical granule-reacted oocytes from a marsupial, the grey short-tailed opossum Monodelphis domestica and to determine if a cortical granule envelope (CGE) forms in the perivitelline space (PVS) following the cortical reaction. Unfertilized oocytes collected from mature ovarian follicles and oviducal oocytes that had undergone a cortical reaction were fixed for electron microscopy in the presence of ruthenium red which stabilizes extracellular matrices (ECM) and facilitates demonstration of a CGE. Unfertilized oocytes were surrounded by a zona pellucida and had a PVS which contained a thick ECM comprised of granules and filaments. This matrix appeared to attach to the oolemma and was structurally similar to matrices reported previously in the PVS of unfertilized oocytes from eutherian mammals and two other marsupials, the Virginia opossum and the fat-tailed dunnart. The cortex of unfertilized oocytes contained cortical granules which were absent in oocytes recovered from the oviducts of mated females. Oviducal oocytes which lacked cortical granules exhibited a new coat within the PVS between the zona pellucida and the tips of the oocyte microvilli. This coat, the CGE, appeared structurally similar to CGEs described previously around fertilized eutherian oocytes. The CGE of the grey short-tailed opossum is approximately 1 microns thick and is made up of numerous small dense granules. The coats of the opossum oocyte are compared to those present around other marsupial and eutherian oocytes.

Animals↗
PubMed1992

Perivitelline space of mammalian oocytes: extracellular matrix of unfertilized oocytes and formation of a cortical granule envelope following fertilization.

Extracellular matrices (ECM) present around unfertilized and fertilized mammalian oocytes were studied ultrastructurally in samples prepared in the presence of ruthenium red to facilitate stabilization of extracellular materials. Unfertilized mouse, hamster, and human oocytes have an ECM comprising granules and filaments in their perivitelline spaces (PVS). This matrix is more abundant in the human than in hamsters and mice. The granule/filament matrix appears identical to the matrix seen between cumulus and corona radiata cells following ruthenium red processing and previously shown to comprise protein and hyaluronic acid. By including ruthenium red during fixation, it is possible to demonstrate the existence of cortical granule exudate in the PVS of fertilized oocytes from hamsters, mice, and humans. Much of the cortical granule exudate is trapped in the PVS and forms a new coat around the fertilized oocyte. This material is particulate when stained with ruthenium red and appears to be uniformly dispersed around the entire oocyte surface. We refer to this new coat as the cortical granule envelope. This envelope is observed in the PVS of all developmental stages up to and including blastocysts in all three species. Following hatching of mouse and hamster blastocysts, the cortical granule envelope is no longer present. Possible functions of this envelope are discussed.

Animals↗
PubMed1992

Structure, distribution and composition of the extracellular matrix of human oocytes and cumulus masses.

The structure, distribution and composition of the extracellular matrix present around the human oocyte and in the cumulus was examined following fixation in the presence of ruthenium red. An extracellular matrix comprising granules and filaments is present in the cumulus layer, in the corona radiata, in the outer pores of the zona pellucida and in the perivitelline space surrounding unfertilized oocytes. In replicate samples, the extracellular matrix comprised filaments which were mostly very long, occasionally cross-connected by shorter filaments, and usually decorated with numerous small granules. Enzymatic digestion with affinity-purified trypsin or Streptomyces hyaluronidase removes the granules and filaments, respectively, at all levels of the oocyte-cumulus complex. These results are interpreted to mean that protein and hyaluronic acid are present in all extracellular compartments of the human oocyte-cumulus complex. The significance of this distribution of hyaluronic acid with respect to the role of sperm hyaluronidase in fertilization is discussed.

Extracellular Matrix↗
PubMed1990

Insulin-like growth factor I (IGF-I) levels in follicular fluid from human preovulatory follicles: correlation with serum IGF-I levels.

Insulin-like growth factor I (IGF-I) levels were measured in both serum and fluid of preovulatory follicles (n = 156) in 43 women undergoing in vitro fertilization (IVF). The mean IGF-I level in follicular fluid (FF) was significantly lower than in serum (0.52 +/- 0.02 IU/L versus 0.66 +/- 0.23 IU/L), and FF levels were significantly correlated with individual serum IGF-I levels as well as with follicular size and FF volume but not with oocyte maturity, granulosa cell appearance, or IVF. This suggests that FF IGF-I levels cannot serve as a clinical indicator for the degree of oocyte/granulosa cell differentiation or a predictor for IVF. Serum IGF-I levels were inversely correlated with the number of human menopausal gonadotropin ampules administered during treatment, suggesting that IGF-I might enhance ovarian gonadotropic stimulation.

Estradiol↗
PubMed1988

Human sperm acrosome reaction-initiating activity associated with the human cumulus oophorus and mural granulosa cells.

This report describes the detection and partial characterization of preovulatory human cumulus oophorus and mural granulosa cell-associated activity capable of initiating the human sperm acrosome reaction (AR) in vitro. Fragments of preovulatory human cumulus (cells plus extracellular matrix) were washed 3 times, incubated for 24 hr and the spent media and washes assayed for their ability to initiate the human sperm acrosome reaction (AR) in vitro. AR activity was present in the first two washes but not the third wash; however, AR activity was recovered in the spent medium after 3 X-washed fragments were incubated for 24 hr under conditions which maintained the viability of the cumulus cells. The spent media of preovulatory human mural granulosa cells contained AR-initiating activity after 1-3, 3-6, and 6-9 days of culture. The properties of the AR activity present in spent media of human cumulus fragments included resistance to loss of activity during treatment with pronase; resistance to loss of activity during treatment with chondroitinase ABC or bacterial hyaluronidase; heat stability after overnight incubation; lack of extraction by chloroform-methanol; an apparent molecular weight (MW) of 50,000, as determined by Sephadex G-75 column chromatography; conversion to a lower apparent MW activity by incubation with pronase. These properties are also characteristic of a fraction derived by Sephadex G-75 chromatography of preovulatory human follicular fluid which also has been shown to stimulate the human sperm acrosome reaction in vitro. The AR activity from spent media of human mural granulosa cells is also found in a 50,000 MW Sephadex G-75 fraction. We propose that the sources of the 50,000 MW human follicular fluid AR activity are the cumulus oophorus and the mural granulosa cells.

Acrosome↗
PubMed1984

Sperm concentration and the fertilization of human eggs in vitro.

The effect of sperm concentration on the fertilization of preovulatory and immature human eggs was studied in the context of an ongoing in vitro fertilization-embryo transfer (IVF-ET) program. Fertilization success was independent of the follicular recruitment protocol used, and with preovulatory eggs, was inversely related to sperm concentration over the range of 2.5 - 50 X 10(4) motile sperm/ml. Maximum fertilization (80.8%) occurred at a concentration of 2.5 X 10(4) motile sperm/ml. The incidence of polyspermic fertilization was directly related to the sperm concentration, decreasing from 5.5% at 10 X 10(4) to 0% at 1-2.5 X 10(4) motile sperm/ml. Immature eggs cultured in vitro, then inseminated, also demonstrated an inverse relationship between fertilization and sperm concentration with a maximum fertilization rate of 66.6% at 5 X 10(4) motile sperm/ml. The percentage of motile sperm in the inseminating population had no influence on fertilization rates unless the value dropped below 40%. Fertilization success using sperm from oligospermic and polyzoospermic males was also examined. In contrast to males with normal semen parameters, oligospermic males demonstrated highest fertilization success at 50 X 10(4) motile sperm/ml. The IVF of preovulatory eggs using sperm from polyzoospermic males was comparable to that for males with normal semen parameters at equivalent sperm concentrations. The implications of these findings to the application of IVF-ET technology to the infertile couple is discussed.

Embryo Transfer↗
PubMed1983

Characterization of human sperm surface antigens with monoclonal antibodies.

Monoclonal antibodies (McAb) against human ejaculated sperm were developed from mice immunized with sperm membrane preparations. A solid-phase radioimmunoassay, with dried sperm as antigen, was employed in McAb screening. The tissue and species specificity of monoclonal antibodies HS 2, 4 and 6 were evaluated after absorption of antibody preparations with heterologous sperm, human serum or seminal plasma or cells from other human organs. The sensitivity of HS 2, 4 and 6 antigens to trypsin exposure was determined: HS 4 antigen was highly sensitive while HS 2 and 6 were not. The regional distribution of McAb 4 on intact sperm cells was determined by immunofluorescence staining. HS 4 may be a sperm-coating antigen based on its presence on sperm and in seminal plasma. This possibility led to an investigation of its role in sperm capacitation. HS 4 antibody binding was reduced when capacitated sperm were compared with noncapacitated cells. HS 4 antibody, when present during capacitation and insemination, was without effect on sperm motility or fusion with zona-free hamster eggs. Trypsin removal of as much as 60% of HS 4 antigen from the cell population also did not impact on sperm function. To identify the molecular correlate of HS 4 antigen, membrane components were extracted from washed sperm with Nonidet P-40, concentrated by acetone precipitation and analyzed electrophoretically in SDS-urea on 10% polyacrylamide slab gels. Immunoassays on protein blots with peroxidase-coupled second antibody identified a single reactive species in the molecular weight range of 130,000. Multiple reactive components were detected in blot transfers of seminal plasma.

Animals↗
PubMed1976

A comparison of in-vitro fertilization of rabbit eggs using spermatozoa recovered from the uterus or vagina.

Spermatozoa were recovered from the uterine horns or vagina of mated rabbit does 12-20 hr p.c. and their fertilizing capacity tested in an in-vitro system. Uterine spermatozoa gave consistently high fertilization (93-100%) throughout. Vaginal spermatozoa gave good results (81-85%) 12-14 hr p.c. but fertilization then declined with time. Vaginal spermatozoa recovered from mated females with or without ligation of the uterine horns were equally able to fertilize eggs. Fragmentation of uncleaved eggs was noted in experiments with vaginal spermatozoa, but never with uterine spermatozoa. The former were slower in penetrating eggs and the zygotes were correspondingly slower in cleaving. Triploidy, possibly due to ageing, was found in approximately 15% of the embryos fertilized by vaginal spermatozoa.

Animals↗
PubMed1975

Localization of prostaglandin on the plasmalemma of rabbit sperm.

Prostaglandin and prostaglandin receptors were localized on unwashed ejaculate rabbit sperm utilizing ferritin conjugated antibody to prostaglandin. Reaction was obtained over the acrosomal portion of the plasma membrane, with a greater aggregation over the apex of the head. The remainder of the head plasmalemma and flagellum showed no deposits of of reaction product. The reaction did not occur if the sperm were washed prior to incubation with the labelled antisera. However enhanced binding of ferritin was demonstrated if washed sperm were pre-incubated in PGE1. No reaction was seen in similar studies with human sperm.

Animals↗