PubMed Health⌕ Search

Biomedical subjects

S K Das

Publications and source records attributed to S K Das.

At least 163 records · Page 9Linked to original sources
PubMed1998

Effect of immunostimulation on cytotoxic activity of intestinal intraepithelial lymphocytes of chickens in infectious bursal disease and Eimeria tenella infections.

In chickens, intestinal intraepithelial lymphocytes (iIELs) exhibit spontaneous natural killer (NK) cell like activity, by which they are active in the first line of defence on gut epithelial linings. In the present study, the cytotoxic activity of iIELs was found to be drastically suppressed in chickens experimentally infected with infectious bursal disease (IBD) virus at the age of 5 weeks and also in chickens experimentally infected with Eimeria tenella oocysts at the age of 8 weeks (p < 0.01). As nonspecific immunostimulation is gaining importance, immunostimulants such as immunostimulating Mycobacterium phlei (ISMP) and bone marrow culture supernatant (BMCS) were tested for their influence on the functional activity of iIELs of chickens in IBD and E. tenella infections. In chickens primed with ISMP a week prior to respective experimental infections, it was found that the cytotoxic activity of iIELs was restored (p < 0.01) in both IBD and E. tenella infections. At the same time, in chickens primed with BMCS a week prior to respective experimental infections, the cytotoxic activity of iIELs was restored to a certain extent (p < 0.01) in E. tenella but not at all in IBD infection. These results showed that application of immunostimulation helped potentiate and restore the functional activity of iIELs of chickens in IBD and E. tenella infections.

Animals↗
PubMed1998

Short-term macrophage interleukin-1 response to injected silicone in a rat model.

The short-term effects of silicone particles on the ability of splenic and peritoneal macrophages to produce Interleukin-1 (IL-1) were assessed. Lewis rats were divided into three groups. Group 1 animals (n=12) were injected subcutaneously with 2.5 ml of sterile saline; Group 2 animals (n=12) received 2.5 ml of Freund's Complete Adjuvant (FCA); Group 3 animals (n=12) received subcutaneous injections (2.5 ml) of a sonicated slurry comprised of equal parts of FCA and silicone. At days 1, 4, and 7 single-cell suspensions of splenic (10(8) cells/ml) and peritoneal (10(6) cells/ml) macrophages of four animals from each group were prepared. The supernatants from macrophages cultured in the presence or absence of lipopolysaccharide (LPS) were added to IL-1 dependent mouse thymocytes for 72 hrs, and subsequently pulsed with 3H-thymidine. Radioactivity incorporation was determined after 18 hrs. Peritoneal macrophage culture supernatants had significantly higher activity than splenic macrophages and all macrophages stimulated with LPS had significantly higher activity. At days 1 and 7, there were no significant differences in 3H-thymidine uptake. At day 4 there was an elevation of 3H-thymidine uptake from supernatant of peritoneal macrophages treated with FCA/silicone suggesting subcutaneous silicone injection has short-term effects.

Animals↗
PubMed1997

Partial characterization of guinea pig cholinephosphotransferase cDNA.

An alternative molecular biology strategy is needed to characterize cholinephosphotransferase (CPT) gene because of the complexity of the problem associated with the solubilization of the membrane-bound enzyme without denaturation. We have synthesized five heterologous oligonucleotide probes based on the published yeast CPT gene sequence. Each probe (24 to 30 mers) was used as either forward or reverse flanking primers in combination with lambda gt11 primers to amplify a segment of DNA from a guinea pig liver 5'cDNA library by polymerase chain reaction (PCR). We detected several clones of varied size (0.1 kb to 2.2 kb) by subjecting the PCR products to 1.2% agarose gel electrophoresis. Southern blot of a 0.7 kb PCR product did hybridize with a 32P-labeled internal probe. Slot blot hybridization of guinea pig liver total RNA with the 32P-labeled 0.7 kb PCR product yielded positive transcripts with intensities proportional to the concentration of RNA. Furthermore, a 0.1 kb clone was sequenced and the observed sequence shared 96% homology with the yeast CPT gene sequence.

Animals↗
PubMed1997

Estrogenic responses in estrogen receptor-alpha deficient mice reveal a distinct estrogen signaling pathway.

Estrogens are thought to regulate female reproductive functions by altering gene transcription in target organs primarily via the nuclear estrogen receptor-alpha (ER-alpha). By using ER-alpha "knock-out" (ERKO) mice, we demonstrate herein that a catecholestrogen, 4-hydroxyestradiol-17beta (4-OH-E2), and an environmental estrogen, chlordecone (kepone), up-regulate the uterine expression of an estrogen-responsive gene, lactoferrin (LF), independent of ER-alpha. A primary estrogen, estradiol-17beta (E2), did not induce this LF response. An estrogen receptor antagonist, ICI-182,780, or E2 failed to inhibit uterine LF gene expression induced by 4-OH-E2 or kepone in ERKO mice, which suggests that this estrogen signaling pathway is independent of both ER-alpha and the recently cloned ER-beta. 4-OH-E2, but not E2, also stimulated increases in uterine water imbibition and macromolecule uptake in ovariectomized ERKO mice. The results strongly imply the presence of a distinct estrogen-signaling pathway in the mouse uterus that mediates the effects of both physiological and environmental estrogens. This estrogen response pathway will have profound implications for our understanding of the physiology and pathophysiology of female sex steroid hormone actions in target organs.

Animals↗
PubMed1997

Multiple female reproductive failures in cyclooxygenase 2-deficient mice.

Cyclooxygenase (COX) is the rate-limiting enzyme in the synthesis of prostaglandins (PGs) and exists in two isoforms, COX-1 and COX-2. In spite of long-standing speculation, definitive roles of PGs in various events of early pregnancy remain elusive. We demonstrate herein that the targeted disruption of COX-2, but not COX-1, in mice produces multiple failures in female reproductive processes that include ovulation, fertilization, implantation, and decidualization. Using multiple approaches, we conclude that these defects are the direct result of target organ-specific COX-2 deficiency but are not the result of deficiency of pituitary gonadotropins or ovarian steroid hormones, or reduced responsiveness of the target organs to their respective hormones.

Animals↗
PubMed1997

Expression of betacellulin and epiregulin genes in the mouse uterus temporally by the blastocyst solely at the site of its apposition is coincident with the "window" of implantation.

In the mouse, the process of implantation is initiated by the attachment reaction between the blastocyst trophectoderm and uterine luminal epithelium that occurs at 2200-2300 h on day 4 (day 1 = vaginal plug) of pregnancy. Several members of the EGF family are considered important in embryo-uterine interactions during implantation. This investigation demonstrates that the expression of two additions to the family, betacellulin and epiregulin, are exquisitely restricted to the mouse uterine luminal epithelium and underlying stroma adjacent to the implanting blastocyst. These genes are not expressed during progesterone-maintained delayed implantation, but are rapidly switched on in the uterus surrounding the implanting blastocyst following termination of the delay by estrogen. These results provide evidence that expression of betacellulin and epiregulin in the uterus requires the presence of an active blastocyst and suggest an involvement of these growth factors in the process of implantation.

Animals↗
PubMed1997

Production and physiological actions of anandamide in the vasculature of the rat kidney.

The endogenous cannabinoid receptor agonist anandamide is present in central and peripheral tissues. As the kidney contains both the amidase that degrades anandamide and transcripts for anandamide receptors, we characterized the molecular components of the anandamide signaling system and the vascular effects of exogenous anandamide in the kidney. We show that anandamide is present in kidney homogenates, cultured renal endothelial cells (EC), and mesangial cells; these cells also contain anandamide amidase. Reverse-transcriptase PCR shows that EC contain transcripts for cannabinoid type 1 (CB1) receptors, while mesangial cells have mRNA for both CB1 and CB2 receptors. EC exhibit specific, high-affinity binding of anandamide (Kd = 27.4 nM). Anandamide (1 microM) vasodilates juxtamedullary afferent arterioles perfused in vitro; the vasodilation can be blocked by nitric oxide (NO) synthase inhibition with L-NAME (0.1 mM) or CB1 receptor antagonism with SR 141716A (1 microM), but not by indomethacin (10 microM). Anandamide (10 nM) stimulates CB1-receptor-mediated NO release from perfused renal arterial segments; a similar effect was seen in EC. Finally, anandamide (1 microM) produces a NO-mediated inhibition of KCl-stimulated [3H]norepinephrine release from sympathetic nerves on isolated renal arterial segments. Hence, an anandamide signaling system is present in the kidney, where it exerts significant vasorelaxant and neuromodulatory effects.

Amidohydrolases↗
PubMed1997

Selection of coplanar or noncoplanar beams using three-dimensional optimization based on maximum beam separation and minimized nontarget irradiation.

PURPOSE: The design of an appropriate set of multiple fixed fields to achieve a steep dose gradient at the tumor edge, with minimal normal tissue exposure, is a very difficult problem, since a virtually infinite number of possible beam orientations exists. In practice we have selected beams in an iterative and often time-consuming process. This work proposes an optimization method, based on geometric and dose elements, to effectively arrive at a set of beam orientations. METHODS AND MATERIALS: Beams are selected by minimizing a goal function including an angle function (beam separation for steep dose gradient at target edge) and a length function (related to normal tissue dose volume histogram). The relative importance of these two factors may be adjusted depending on the clinic situation. The model is flexible and can include case specific practical anatomic and physical considerations. RESULTS: In extremely simple situations, the goal function yields results consistent with well-known analytical solutions. When applied to more complex clinical situations, it provides clinically reasonable solutions similar to those empirically developed by the clinician. The optimization process takes approximately 25 min on a UNIX workstation. CONCLUSION: The optimization scheme provides a practical means for rapidly designing multiple field coplanar or noncoplanar treatments. It overcomes limitations in human three-dimensional visualization such as trying to visualize beam directions and keeping track of the hinge angle between beams while accounting for anatomic/machine constraints. In practice, it has been used as a starting point for physicians to make modifications, based on their clinical judgment.

Brain Neoplasms↗
PubMed1997

Expression of matrix metalloproteinases and tissue inhibitors of metalloproteinases in the mouse uterus during the peri-implantation period.

The attachment of the blastocyst to the uterine luminal epithelium and the subsequent invasion by trophoblast cells through the stroma and deciduum occur in a highly regulated manner by remodeling of the extracellular matrix. We investigated the temporal and spatial expression of mRNAs for four matrix metalloproteinases (MMPs; MMP-2 [gelatinase A], MMP-3 [stromelysin 1], MMPs; MMP-2 [gelatinase B], and MMP-13 [collagenase 3]) and tissue inhibitors of metalloproteinases (TIMPs; TIMP-1, TIMP-2, and TIMP-3) in the mouse uterus from days 1 to 8 of pregnancy. Northern blot analyses showed the transcripts for MMP-2, MMP-3, RNA on these days. However, MMP-13 mRNA was not detected in the uterus, and only weak signals for MMP-3 mRNA were detected in the myometrium. Striking expression was observed with MMP-2 mRNA in the subepithelial stroma on days 3-5. With the progression of decidualization on day 6, signals were primarily in the secondary decidual zone. On day 8, MMP-2 mRNA was localized at the site of placenta formation in the mesometrial pole. Signals for MMP-9 mRNA were first detected in a small population of stromal cells exclusively at the site of implantation on day 5 at the antimesometrial pole. However, the most pronounced expressed was noted in trophoblast giant cells on day 8. TIMP-1 mRNA was present in the myometrium on day 1. On days 2-5, modest signals were detected in the stroma, and on days 6 and 8, they were in the secondary decidual zone. Localization of TIMP-2 mRNA was similar to that of TIMP-1 except it was restricted to the stroma on day 1. The regulation of TIMP-3 was more pronounced. While a gradual increase in signals was observed in stromal cells from days 1 to 4, strong signals were detected in antimesometrial stromal cells at the sites of blastocyst attachment on day 5. On days 6 and 7, even stronger signals were present in the primary decidual zone surrounding the embryo, and on day 8 signals were localized primarily in the mesometrial decidual bed. These results suggest that MMP-2 may participate in the early phase of decidualization and neovascularization required for placentation. The restricted MMP-9 expression in stromal cells on day 5 and in trophoblast giant cells on day 8, coupled with the expression of TIMP-3 in the stroma surrounding the embryo, suggests that a fine balance between MMP-9 and TIMP-3 may regulate trophoblast invasion in the uterus.

Animals↗
PubMed1997

Phase II clinical trial of a vas deferens injectable contraceptive for the male.

Following up on an earlier clinical trial demonstrating the safety of an intra-vas deferens injection of a contraceptive drug named Risug, comprised of styrene maleic anhydride (SMA) in a solvent vehicle of dimethylsulphoxide (DMSO), a study to assess the contraceptive effectiveness of a specific dose (60 mg) of SMA bilaterally was planned and implemented. Male subjects and their wives with normal reproductive profiles were the volunteer subjects. The wives were not using any contraceptives. The results reconfirm the safety and show that for a period of at least 1 year, the treatment leads to azoospermia in the male and gives pregnancy protection.

Adult↗
PubMed1997

Replacement of serum and hormone additives with follicular fluid in the IVM medium: effects on maturation, fertilization and subsequent development of buffalo oocytes in vitro.

Buffalo follicular fluid was used in the IVM medium in place of serum and hormone additives for stimulating nuclear and cytoplasmic maturation of buffalo oocytes in vitro. Follicular fluid (buFF) was aspirated from visible surface follicles from buffalo ovaries. Cumulus oocyte complexes (COCs) were matured for 24 to 26 h at 38.5 degrees C, 5% CO(2) in air in the maturation medium (TCM-199). When used, the concentration of fetal bovine serum (FBS) was 10% and that of FSH-P was 5 mug/ml. In Experiment 1 TCM-199 was supplemented with 1) FBS, 2) FBS + FSH-P, 3) 20% buFF and 4) 40% buFF. The matured oocytes were denuded and stained with Giemsa stain to study nuclear maturation. The proportion of oocytes which completed nuclear maturation was similar in medium containing FSH (74%) and 20 or 40% buFF (67%), which was higher (P < 0.05) than in medium with FBS but without FSH or buFF (47%). In Experiment 2, which was aimed at examining the effects of buFF on cumulus expansion and rates of fertilization and subsequent development to the blastocyst stage after IVF, the maturation medium was supplemented with 1) FBS + FSH-P, 2) 20% buFF and 3) 40% buFF. The COCs matured in medium containing 20 or 40% buFF had significantly higher (P < 0.01) cumulus expansion than those matured in medium with FBS + FSH-P. Of the COCs matured in medium with FBS + FSH-P and 20 or 40% buFF, the fertilization rates indicated by the incidence of cleavage (56, 51 and 52%, respectively) and the proportion of cleaved COCs developing to morula (58, 54 and 57%, respectively) and blastocyst stage (30, 31 and 35%, respectively) were not significantly different. In Experiment 3, supplementation of the maturation medium with 1) FBS + FSH-P and 2) FBS + FSH-P + 20% buFF resulted in similar rates of morulae (41 and 38%, respectively) and blastocysts (31 and 25%, respectively), indicating that simultaneous presence of FBS, FSH-P and buFF did not have an additive effect on embryo yield. The results show that the gonadotropin and serum source in the IVM medium can be replaced by buFF at the 20% level to achieve comparable morula and blastocyst yields.

Journal Article↗
PubMed1997

The occurrence of beta-thalassemia mutation and its interaction with hemoglobin E in the eastern India.

The distribution of variant hemoglobin in India has been related to various ethnic groups among other factors. beta-Thalassemia is the most frequent monogenic disorder in the country. Analysis of hemoglobin of 435 cases from Eastern India was performed by electrophoresis and by other quantitative methods. Analysis of the beta-globin gene of 112 cases used ARMS (amplification refractory mutation system)-PCR (polymerase chain reaction) techniques showing that IVS-1 nt 5 (G-->C) is the most prevalent mutation in populations from Eastern India. IVS-1 nt 5 (G-->C) interacts with the codon 26 (G-->A) mutation to produce E beta-thalassemia phenotype in the samples from West Bengal, India.

Hemoglobin E↗
PubMed1997

Ontogeny of neurotransmitter amino acids in human fetal brains.

A wide spectrum of developmental profiles is presented for a few important neurotransmitter amino acids, namely gamma-aminobutyric acid, glycine, glutamic acid, aspartic acid and taurine as well as the key enzymes involved in their metabolism in human fetal brains of different gestational ages. Besides taurine almost all these amino acids and their key metabolic enzymes were found to be progressively enhanced upto the mid period of third trimester of pregnancy indicating a rapid growth of nerve processes, myelination and maturation of fetal brains particularly during this period. Interestingly taurine showed an inverse relationship of ontogenic pattern with respect to its biosynthesizing enzyme in fetal brains.

4-Aminobutyrate Transaminase↗
PubMed1997

Potential sites of prostaglandin actions in the periimplantation mouse uterus: differential expression and regulation of prostaglandin receptor genes.

Prostaglandins (PGs), especially PGE2 and PGF2alpha, are considered important for blastocyst spacing, implantation, and decidualization in the rodent uterus. However, information regarding uterine sites of PG actions in these processes is lacking. PGE2 or PGF2alpha interacts with specific G protein-coupled membrane receptors. PGE2 receptors are classified into four subtypes, EP1, EP2, EP3, and EP4. While EP1 is coupled to Ca2+ mobilization, activation of EP2 and EP4 triggers stimulation of adenylyl cyclase. In contrast, activation of EP3 inhibits adenylyl cyclase. PGF2alpha receptor (FP) is coupled to stimulation of phospholipase C-inositol trisphosphate (IP3) pathway and Ca2+ mobilization. This investigation demonstrates that PGE2 and PGF2alpha receptor genes are expressed in a temporal and cell-specific manner in the periimplantation mouse uterus. In the mouse, the attachment reaction occurs in the evening (2200-2300 h) of Day 4 of pregnancy and is preceded by embryo spacing, uterine edema, and luminal closure resulting in an intimate apposition of the blastocyst with the uterine luminal epithelium. Expression of EP3 and FP primarily in the circular muscle of the myometrium on Days 3-5 of pregnancy suggests that the circular muscle, not the longitudinal muscle, is the primary target for PG-mediated uterine contractions required for embryo transport, spacing, and/or accommodation in the uterus. In contrast, expression of EP3 in a subpopulation of cells in the stromal bed at the mesometrial side, and of EP4 in the epithelium and stroma on these days, suggests that PGE2 effects on uterine preparation for implantation (such as epithelial cell differentiation, stromal cell proliferation, uterine edema, luminal closure, and increased localized endometrial vascular permeability at the sites of blastocyst attachment) are mediated by these receptor subtypes. Similar expression patterns of EP3 and EP4 in the Day 4 pseudopregnant mouse uterus or in the ovariectomized uterus under combined treatment with estrogen and progesterone suggest that these genes are regulated by ovarian steroids rather than by the embryo during the preimplantation period (Days 1-4). In contrast, the expression of these genes during the postimplantation period (Days 5-8) is associated with the onset of decidualization.

Animals↗
PubMed1997

Expression of vascular endothelial growth factor (VEGF) and VEGF-receptor messenger ribonucleic acids in the peri-implantation rabbit uterus.

The endometrial vasculature undergoes expansion during preimplantation stages and, even more prominently, after implantation. In addition to angiogenesis, vascular hyperpermeability accompanies the attachment and invasion of blastocysts into the uterine lining. Vascular endothelial growth factor (VEGF) is an angiogenic factor expressed in mammalian uteri that also has potent activity in inducing vascular permeability. Rabbit uteri were examined using Northern and in situ hybridization to assess the temporal and spatial expression of VEGF and its receptor (Flk-1, Flt-1) mRNAs during the pre- and peri-implantation periods (Days 0-8). Steady-state levels of VEGF mRNA were highest in endometrium at estrous and peri-implantation stages (Days 6-8). In situ hybridization revealed a shift from uniform expression of VEGF transcripts throughout the uterus at estrus and Day 4, to an endometrial epithelial localization just before and during implantation. At implantation sites, a pronounced signal was present in the trophoblastic knobs, the syncytial aggregates that attach to and invade the endometrium. VEGF protein was detected by immunoblot analysis in peri-implantation-stage uteri but was below the limit of detection in estrous endometrium. VEGF receptor mRNAs were expressed in the uterus at all stages examined, with high levels of Flk-1 and Flt-1 at estrus and again just before implantation, 6-3/4 days pregnant. The high level just before implantation correlates with in situ hybridization results showing a prominent, but transient, signal for Flk-1 mRNA in the endometrial epithelium. During implantation, Flk-1 mRNA was associated with blood vessels of the endometrial stroma. We conclude that VEGF is a candidate factor for the induction of vascular hyperpermeability at implantation in the rabbit and in the angiogenic process that follows.

Animals↗