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Biomedical subjects

P D Gupta

Publications and source records attributed to P D Gupta.

At least 19 recordsLinked to original sources
PubMed2002

Conventional estrogen receptors are found in the plasma membrane of vaginal epithelial cells of the rat.

Estrogens induce rapid (non-genomic) and delayed (genomic) effects on the target cells. The early effects include induction of signal transduction pathway within seconds, whereas the delayed responses require hours and involve transcription and translation. The rapid effects of estradiol (E) on the vaginal epithelial cells (VEC) involved calcium uptake within seconds via the induction of phosphoinositol lipid metabolism as reported in our earlier studies. In this study, we demonstrate the presence of classical estrogen receptors (ER) on the plasma membrane of VEC of the rats. Immunoreactive bands of 67, 56 and 35 kDa are detectable in the membrane fractions (mf) using antibodies recognizing different epitopes of ER alpha. We have also been able to purify a protein having a mass of 67 kDa from the detergent-soluble fraction of the plasma membrane of VEC, which shows properties identical to the classical receptor purified from the cytosolic fraction of the cells. The membrane receptors get dissociated upon binding to the ligand. Besides a role in signal transduction events induced by estradiol, the membrane estrogen receptors may have an important role to play in translocation of the steroid to the cytosolic compartment.

Animals↗
PubMed2002

Nuclear localization of non-specific acid phosphatase(s) activity in rat vaginal epithelium.

The nuclear localization of non-specific acid phosphatase(s) in rat vaginal epithelial cells (VEC) by histochemical and biochemical techniques has been reported in the present work. By different histochemical methods, the enzyme activity was predominantly localized in certain nuclei but not in all of them, however, within the nucleus nucleoli are free from the enzyme activity. This enzyme is diffused in the nucleoplasm and perhaps tightly associated with the nuclear proteins. Very little activity was seen in the cytoplasm in the selective population of VEC. After 12 h treatment of estradiol 17beta in vivo the VEC lose the enzyme activity in the basal and intermediate layers, and the activity remains within the nuclei of luminal cells. Enzyme assay in low and high salt extracts of the isolated nuclei of the VEC with or without the enzyme inhibitors indicates that this enzyme may be present in isoforms in the VEC. No activity was observed in these cells at alkaline pH.

Acid Phosphatase↗
PubMed2001

Experimental study of harmonic generation from solid surfaces irradiated by multipicosecond laser pulses.

An experimental study is presented on harmonic generation from solid surfaces using 27 ps Nd:glass laser pulses (lambda=1053 nm) in the intensity range of 10(13)-10(15) W cm(-2). Second, third, and fourth harmonics emitted in the specular reflection direction showed intensity scaling exponents of 1.5, 1.8, and 3.8 for an obliquely incident p-polarized laser beam, providing a conversion efficiency of 2x10(-8), 10(-10), and 5x10(-12) at 10(15) W cm(-2), respectively. Second and third harmonic radiation generated using an s-polarized pump was about 10 and 100 times smaller, respectively, compared to that for the p-polarized laser radiation. Faraday rotation observed in the reflected fundamental radiation can explain the relative harmonic yields for the p and s polarizations of the pump beam.

Journal Article↗
PubMed2001

Altered expression of keratins during abnormal wound healing in human skin.

Keloids and hypertrophic scars are a result of aberrations of the normal wound healing processes of the skin. The expression of keratins, the proteins of an intermediate filament supergene family, closely parallel the division/differentiation of epithelial cells and therefore offer excellent molecular markers to examine wound healing. In this study, the expression of K5/K14, proliferation specific keratin polypeptides in normal skin, keloids and hypertrophic scars was analysed. Results indicated that unlike normal wounds and hypertrophic scars, keloid epidermis displayed increased expression of K5 and K14 at both the translational and transcriptional levels. The molecular mechanisms in the pathogenesis of keloids appear to be different from those of hypertrophic scars.

Adolescent↗
PubMed2001

Steroid hormones regulate programmed cell death: a review.

Programmed cell death (PCD) is a physiologically active process which is essential for the proper functioning of any living tissue. The steroid hormones modulate the programme in the immunological and reproductive organs and tissues, such as the thymus gland, circulating thymocytes, uterus, vagina, testis, ovary and prostrate gland. The influence of steroid hormones on cell death is tissue specific; the same hormone can inhibit PCD in one tissue, and may promote PCD in another tissue. The roles of apoptosis and terminal differentiation have been examined, and the regulation of PCD by steroid hormones, assessed.

Animals↗
PubMed2000

Mechanism of dye binding in the protein assay using eosin dyes.

Eosin B and eosin Y have been used to estimate micro- and submicrogram quantities of proteins respectively as shown in our previous reports. In the present study we describe the mechanism of eosin binding to proteins. At pH lower than 3.0 the absorbance of unbound dye is greatly reduced. After the dye binds to protein, the absorption maximum of the dye changes from 514 to 530 +/- 5 nm. The absorbance and bathochromatic shift in absorption maximum of the protein-dye complex are proportional to the concentration of protein. The pH of the assay solution does not change due to protein. Arginine, histidine, and lysine (at both acidic and neutral pH) and tryptophan (at acidic pH) residues of a protein bind electrostatically to carboxylic and phenolic groups of the dye to produce a stable water-soluble protein-dye complex. The binding constants of eosin B with poly-L-arginine, poly-L-histidine, poly-L-lysine, and poly-L-tryptophan at pH 1.96 are 0.37, 0.32, 0.33 and 0.33 nmol/nmol of amino acid, respectively. The binding constants of eosin B and eosin Y with bovine serum albumin (BSA) at pH 1.96 are essentially the same, i.e., 0.82 nmol/nmol of reactive amino acid of BSA. The binding constant varies with solution pH so that a wide range of protein concentrations can be estimated. The reason for the higher absorbance of protein-eosin Y complex compared to that of protein-eosin B complex is discussed.

Animals↗
PubMed2000

Estimation of submicrogram quantities of protein using the dye eosin Y.

Eosin B is used to estimate proteins above 1 microg/ml concentration [Waheed AA, Gupta, PD. Anal. Biochem. 1996:233:249-256; Waheed AA, Gupta PD. J. Biochem. Biophys. Meth. 1996;33:187-196]. In the present report we describe a method for estimating submicrogram quantities of proteins using the dye eosin Y. The increase in sensitivity of this assay is approximately two fold under optimal assay condition. The optimum concentration of eosin Y and citric acid for submicrogram assay is 0.01 and 0.05%; (final concentration) respectively. The protein-dye complex formation is completed within 2 min and its absorbance is stable up to 60 main with a variation of +/-4.0%. The interference due to sugars, reducing agents, glycerol and some neutral detergents like Triton X-100, NP-40 and Tween-20 is less than 12% whereas Brij-35, ethanol, acetone and chelators like EGTA and EDTA suppress the absorbance by about 12-18%. However, basic buffers like Tris, urea, CHAPS and NaN, interfere with the formation of the protein-dye complex. The increase in absorbance of protein-eosin Y complex compared to that of protein-eosin B complex is due to the higher extinction co-efficient of eosin Y compared to eosin B.

Animals↗
PubMed2000

Mandibular invasion in oral cancers.

Mandibular resection for oral cancers has significant aesthetic and functional sequelae. A reliable preoperative predictor of mandibular invasion is required to guide the need for and extent of mandibular resection. An orthopantomogram of the mandible is an accurate, reliable, cost-effective predictor of bony involvement except for central arch lesions. The feasibility of outer table rim mandibulectomy alone in patients with floor of mouth tumors needs to be examined carefully.

Female↗
PubMed2000

A novel and single step ultrastructural method for staining biological tissues embedded in common embedding media.

A new single step staining method is described which is very simple, rapid and reproducible with better contrast than the widely employed uranyl acetate-lead citrate double staining method for observation of cell organelles in various tissue sections using transmission electron microscope. A copper uranyl acetate solution was employed to stain the ultrathin sections of tissues embedded in either water-miscible or water-immiscible resin media. The staining results are excellent. Cell organelles and extracellular matrix are stained with no artifactual precipitation or granulation.

Animals↗
PubMed1999

Pineal rhythms are synchronized to light-dark cycles in congenitally anophthalmic mutant rats.

Genetically mutant anophthalmic rats lacking a complete visual system due to the absence of eyeballs and optic nerves up to the optic chiasma were used as a model to study photo-regulated physiological activities. The photoreception in these mutant rats was determined by measuring the neuroendocrine response of the pineal gland-melatonin levels in the serum, and synaptic ribbon complexes (SRCs) in the pinealocytes. These parameters were studied in both normal and anophthalmic rats maintained under light-dark (LD 12:12), continuous dark (DD) and light (LL) conditions. Both normal and mutant anophthalmic animals showed nocturnal increases in serum melatonin levels and in the number and diameter of SRC and their vesicles in the pinealocytes in LD. The daily rhythms persisted even upon transfer to DD both in normal and mutant rats, whereas in LL, the nocturnal elevation of both the parameters disappeared. These observations suggested that congenitally blind rats can perceive light. The studies of these parameters in both normal and mutant rats in reversed-LD conditions confirmed that pineal rhythms can be entrained by light-dark cycles in congenitally anophthalmic mutant rats through a nonvisual system for light perception.

Animals↗
PubMed1999

Importance of the role of calcium in programmed cell death: a review.

Calcium plays an important role in physiological cell death processes such as terminal differentiation and apoptosis. Cell injury occurs when the intracellular calcium pool is disturbed, which in turn may lead to cell death. Calcium in calcium-dependent enzymes, transglutaminases, various proteases, phosphorylases and kinase, is involved in the process of cell death. Examples of such enzymes involved in cell death, and the role of calcium levels in regulation of these enzymes, are described and discussed.

Animals↗
PubMed1998

Decreased densities of intramembranous particles and cytochemically detectable cholesterol in microvilli of starved rat enterocytes.

The densities of intramembranous particles (IMPs) and of sterol complexes induced by treatment of filipin were studied by freeze-fracture replication of intact intestine and/or isolated brush border membranes (BBM) of well-fed and starved rats. The density of IMPs and filipin-sterol complexes (FSCs) decrease considerably during starvation. Biochemical estimations show a decrease in the levels of cholesterol and proteins with respect to phospholipids during starvation which is in agreement with morphological findings. It is suggested that these changes may play a role in regulating membrane fluidity which in turn affects absorption of nutrients through BBM.

Animals↗
PubMed1998

Oestradiol regulated programmed cell death in rat vagina: terminal differentiation or apoptosis?

Rat vaginal epithelial cells (VEC) undergo division and differentiation under the influence of oestradiol in a programmed manner. The differentiation process of VEC leads to keratinization, cornification and subsequent desquamation of the dead cells. This process of programmed cell death, referred to as terminal differentiation may share some common pathways with cell death by apoptosis but differ substantially in many aspects. Terminal differentiation of VEC is accompanied by the loss of majority of the organelles including the nucleus. To understand the mechanisms that underlie this process we have analysed the regulation of DNase I (a key effector of apoptotic cell death) in rat VEC under the influence of oestradiol. The present study demonstrates that under physiological conditions, cell death in the VEC is mainly through terminal differentiation although a few cells may undergo apoptotic death involving DNA fragmentation. Unaltered levels of bcl-2 message upon oestradiol administration suggest an important role played by this molecule in preventing death of the VEC by apoptosis.

Animals↗
PubMed1998

Lipid and fatty acid composition of brush border membrane of rat intestine during starvation.

Alterations in the lipid and fatty acid composition of brush border membrane (BBM) of small intestine were studied in well-fed, starved, and refed rats. The ratios of cholesterol/phospholipid (mol/mol), sphingomyelin/phosphatidylcholine (mol/mol), protein/lipid (w/w), and free fatty acids (w/w) decreased whereas the total phospholipid (w/w) ratio and the double-bond index increased in BBM of the intestine of the starved rat compared to that of the well-fed rat. Analyses of fatty acids showed higher percentage of stearic and arachidonic acids whereas oleic and linoleic acids decreased under starvation. The acyl chain of starved rat BBM was less ordered compared with that of well-fed rat BBM. On refeeding, these changes were restored to well-fed levels. The change in membrane state under starvation is associated with alterations in the lipid and fatty acid composition of BBM and may be responsible for functional changes that occur under nutritional stress.

Animals↗
PubMed1997

Heme biosynthesis by the malarial parasite. Import of delta-aminolevulinate dehydrase from the host red cell.

The mouse and human malarial parasites, Plasmodium berghei and Plasmodium falciparum, respectively, synthesize heme de novo following the standard pathway observed in animals despite the availability of large amounts of heme, derived from red cell hemoglobin, which is stored as hemozoin pigment. The enzymes, delta-aminolevulinate dehydrase (ALAD), coproporphyrinogen oxidase, and ferrochelatase are present at strikingly high levels in the P. berghei infected mouse red cell in vivo. The isolated parasite has low levels of ALAD and the data clearly indicate it to be of red cell origin. The purified enzyme preparations from the uninfected red cell and the parasite are identical in kinetic properties, subunit molecular weight, cross-reaction with antibodies to the human enzyme, and N-terminal amino acid sequence. Immunogold electron microscopy of the infected culture indicates that the enzyme is present inside the parasite and, therefore, is not a contaminant. The parasite derives functional ALAD from the host and the enzyme binds specifically to isolated parasite membrane in vitro, suggestive of the involvement of a receptor in its translocation into the parasite. While, ALAD, coproporphyrinogen oxidase, and ferrochelatase from the parasite and the uninfected red cell supernatant have identical subunit molecular weights on SDS-polyacrylamide gel electrophoresis and show immunological cross-reaction with antibodies to the human enzymes, as revealed by Western analysis, the first enzyme of the pathway, namely, delta-aminolevulinate synthase (ALAS) in the parasite, unlike that of the red cell host, does not cross-react with antibodies to the human enzyme. However, ALAS enzyme activity in the parasite is higher than that of the infected red cell supernatant. We therefore conclude that the parasite, while making its own ALAS, imports ALAD and perhaps most of the other enzymes of the pathway from the host to synthesize heme de novo, and this would enable it to segregate this heme from the heme derived from red cell hemoglobin degradation. ALAS of the parasite and the receptor(s) involved in the translocation of the host enzymes into the parasite would be unique drug targets.

Animals↗
PubMed1997

Changes in structural and functional properties of rat intestinal brush border membrane during starvation.

Changes in surface area of microvilli, fluidity of brush border membrane and transport of L-amino acids through intestinal epithelial cells were studied in wellfed and starved (2,4 and 6 days) rats. The surface area of microvilli per unit area of intestinal epithelial cells increased during starvation. Studies with fluoroprobes - pyrene, 1-anilinonaphthalene-8-sulphonate and 1,6-diphenyl-1,3,5-hexatriene, showed increased fluidity of brush border membrane on progressive starvation. Transport of five amino acids representing five different transport systems was studied during starvation in everted intestinal sleeves. Transport of L-proline, glycine and L-glutamic acid which represent imino, glycine and acidic systems respectively increased significantly in Na+-dependent pathway whereas transport of L-lysine representing basic system increased significantly in Na+-independent pathway during starvation.

Amino Acids↗