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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
PubMed1992

Effect of starvation on glucose transport and membrane fluidity in rat intestinal epithelial cells.

Studies on the surface area of microvilli (MV), fluidity of brush border membranes (BBM) and D-glucose uptake were carried out in rat intestinal epithelial cells (IEC) during progressive starvation and under re-feed conditions. The surface area of MV, fluidity of BBM and D-glucose transport through IEC membranes showed an increase during starvation when compared to well-fed controls. Re-feeding experiments restored the control values of all the three parameters within a short time. The results showed that the increase in D-glucose transport through IEC membranes during starvation is due to increased surface area of MV and increased fluidity of BBM.

Alkaline Phosphatase↗
PubMed1992

Increased expression of keratin polypeptides in long term culture of adult rat hepatocytes.

Adult rat hepatocyte cultures showed the presence of albumin after 1 week of seeding. As the cultures aged, the cells commenced expressing alpha-foetoprotein and later keratin polypeptides 55 and 52 kD but ceased expressing albumin and alpha-foetoprotein. Enhanced expression of keratin polypeptides was confirmed by Western blot analysis in long term cultures. A possible mechanism for dedifferentiation of hepatocytes in culture is discussed.

Albumins↗
PubMed1992

Changes in membrane fluidity during human liver development.

The physico-chemical properties of the hepatic plasma membrane during prenatal period of development and in adult human liver were studied. Fluorescence polarization studies using the lipid probe pyrene, clearly demonstrated a significant reduction in the membrane fluidity with liver maturation. Lipid analysis showed an age dependent reduction in lipid/protein ratio while there was an increase in membrane cholesterol throughout the prenatal period and in adult human liver which decreased the membrane fluidity. Hepatic plasma membrane from prenatal liver also showed a decrease in phosphatidyl choline/phosphatidyl ethanolamine ratio and an increase in sphingomyelin/phosphatidyl choline ratio. These results suggest that there is a gradual decrease in lipid content and membrane fluidity during the prenatal period of development which might regulate the differentiation of membrane associated function in human liver.

Adult↗
PubMed1992

Glycogen metabolism during human liver development.

Development of enzymes of glycogen metabolism in human fetal and neonatal liver was investigated. Glycogen was present in quantitatable amount from early gestational age onwards; however, ultrastructurally it could not be detected earlier than 20 weeks. Increase in glycogen synthetase a activity during 21-36 weeks of gestation subsequently resulted in glycogen accumulation. A rapid degradation of this glycogen storage, at birth, was accompanied by an elevation in glycogen phosphorylase a activity. The present investigation to be the first to provide a complete profile of glycogen storage and differentiation of glycogen metabolising enzymes in preparing the prenatal fetus for its independent nutritional life.

Adult↗
PubMed1990

Keratinization of rat vaginal epithelium--V. Modulation of intracellular calcium by estradiol.

Changes in the calcium levels under the influence of estradiol were investigated in rat vaginal epithelial cells (VEC). After single estradiol injection, the immature rats showed 1.5-fold increase in Ca2+ levels within 15 min when compared to control animals. Progesterone priming brought calcium levels well below control values throughout the experimental period (up to 12 h). Ca2+ levels in serum did not show any appreciable change. Localization of calcium in VEC with electron microscopy showed aggregates of calcium oxalate on the inner nuclear membrane, nucleolus, mitochondria and keratohyaline granules. After 15 min of estradiol priming, maximum electron density was seen on all these cell organelles mentioned above, however, by 30 min the electron density was reduced considerably and did not increase during the experimental period (up to 12 h).

Animals↗
PubMed1990

Modulation of phosphorylation and dephosphorylation of keratin and other polypeptides by estradiol-17 beta in rat vaginal epithelium.

Phosphorylation of keratin polypeptides was studied by incubating vaginal tissues (removed from estradiol primed and unprimed 30-day-old rats) with 32Pi. Analysis by SDS-PAGE and autoradiography showed that on treatment with estradiol phosphorylation of 63 and 58 kDa keratin polypeptides increased 3- and 2-fold respectively. Phosphorylation was maximal after 30 min of estradiol priming and decreased thereafter. Phosphorylation of some non-keratin polypeptides (37, 34, 32 and 25 kDa) also showed time dependent variation. The results showed that estradiol can modulate phosphorylation-dephosphorylation of keratins and other polypeptides in rat vaginal epithelial cells.

Animals↗
PubMed1990

Studies on AK-5 tumor: further characterization of rat histiocytoma.

Properties of a transplantable rat histiocytoma which behaves like a macrophage-like cell, have been described. The AK-5 grows as ascites as well as solid subcutaneous tumor. The ascites from one animal can give between 10(8) and 10(9) cells whereas the subcutaneous tumor grows between 20 and 40 cm3 size. These cells possess various degradative enzymes, macrophage markers and glucocorticoid receptors. Beside histopathology the surface topography and ultrastructure of these cells are described.

Animals↗
PubMed1989

Effect of estradiol on the membrane fluidity of the rat vaginal epithelial cells.

Changes in the cell surface of vaginal epithelial cells were studied by scanning microscopy and fluorescence spectroscopy. Microvilli which are prominent features of the vaginal epithelial cells in proestrus and diestrus are replaced by sheet-like structures in the estrus phase. Surface morphology of vaginal epithelial cells of estradiol primed rat resembles the vaginal cells from estrus phase rats whereas vaginal cells from control rats resembles the diestrus phase. Measurement of the fluidity of the membranes indicated that the vaginal epithelial cell membrane of estrus rats is more fluid compared to proestrus and diestrus. Similarly, estradiol primed immature rat vaginal epithelial cell membrane was observed to be more fluid than the corresponding control.

Animals↗
PubMed1989

Sonographic appearance of hepatic hydatid disease.

The sonographic appearance of 25 proved cases of hepatic hydatid disease was characterized and correlated with surgical and pathologic findings. Sonography has a very high accuracy in detecting the type, size, number and location of hepatic hydatid cysts. It also indicates whether they are live (Type I, IR, II) or dead (Type III). The presence of hydatid cysts in the rest of peritoneal cavity and their complications can also be detected. It is of immense help in the selection of cases in which urgent surgery is needed e.g. contained (Type IR), communicating and direct rupture of hydatid cysts. When hydatid cysts are infected, they lose their characteristic sonographic appearance and become hyperechoic. This article details the findings and emphasize the criteria for recognizing hepatic hydatid disease.

Adult↗
PubMed1989

Keratinization of rat vaginal epithelium. III. Effect of estradiol on keratinization.

Effect of estradiol-17 beta on rat vaginal epithelial cells (VEC) was studied by transmission electron microscopy. During the normal estrous cycle in adult rats keratinization and exfoliation of VEC was observed only in the estrus phase, though tonofilament bundles were seen distributed in the cytoplasm of the VEC during the proestrus and, to a lesser extent, in the diestrus phase. Electron microscope data on adult ovariectomised, immature and neonatally estradiol-primed rats demonstrated keratinization of the VEC within 24 h of injection. Proliferative activity was observed in the basal cells in primed animals. The basal cells remained cuboidal whereas cells of intermediate and luminal layers became flattened. These cells showed irregular profiles and, therefore, enhanced numbers of cellular junctions (desmosomes) were observed compared to control groups. Many tonofilament bundles were seen in the cytoplasm of cells belonging to intermediate and luminal layers in primed animals.

Animals↗
PubMed1989

Localization of intracellular zinc under conditions of altered permeability control of the plasma membrane.

Intracellular zinc was located as electron dense granules associated with the plasma membrane, endoplasmic reticular membranes, mitochondrial membranes, nuclear membranes and chromatin in Zajdela ascitic hepatoma and AK5 macrophage ascitic tumour cells. The quantity of intracellular zinc estimated by atomic emission spectrometer was different in the two cell lines. However, after loss of permeability control by the plasma membrane, involving glutaraldehyde and heat-shock treatments, the quantity of intracellular zinc was increased to almost the same extent in both cases.

Animals↗
PubMed1989

Localization of bovine seminal plasma RNA-A BS1, on the surface of bovine spermatozoa.

Using IgG antibodies raised against RNA-A BS1, the presence of this seminal RNA-A on the surface of bovine spermatozoa has been demonstrated. Indirect immunofluorescence and immunoferritin methods showed that this protein coats the surface of ejaculated bovine spermatozoa, but the pattern of binding of the label varied from cell to cell. More than 50% of the spermatozoa showed labelling all over, except the anterior head region; about 30% showed labelling all over except the region below the equatorial plate region; and the remaining were either completely labelled or showed labelling only in the head or the tail region. The head-tail junction (the neck region) was not labelled in any case.

Animals↗
PubMed1987

Tachycardia of carotid chemoreceptors originates in apneic asphyxia in dogs.

Using various anesthetics, we investigated the heart rate changes resulting from apneic asphyxia in paralyzed artificially ventilated dogs with 1) low control heart rate (LCHR) and 2) high control heart rate (HCHR). We observed that apneic asphyxia produced by stopping the ventilation pump for 1 min evoked tachycardia in dogs with LCHR and bradycardia in dogs with HCHR. In dogs breathing 100% O2 in the preapneic period, the tachycardia response was almost wholly abolished, whereas the bradycardia response was attenuated. Intracarotid injection of sodium cyanide induced a tachycardia response in dogs with LCHR and a bradycardia response in dogs with HCHR. The results suggest that 1) apneic asphyxia evokes tachycardia or bradycardia response depending on whether the resting cardiac vagal tone is high or low, respectively, and 2) both types of heart rate responses are in part due to stimulation of carotid chemoreceptors.

Animals↗
PubMed1987

Keratinization of rat vaginal epithelium. I. Cell surface study during natural and induced keratinization.

Morphological changes on surfaces of vaginal epithelial cells from normal cycling (all the four phases) and estrogen primed rats (during neonatal period) at various time points were studied. Non-keratinized cells were covered with uniformly distributed short microvilli. Epithelial cells at 60 day old estrogen primed animals and from estrus rats showed characteristic microridges on their surfaces. Estrus cycle starts only after 90-100 days in normal growing rats, however, in estrogen primed rats epithelial cells of 60 day old animals showed microridges which are comparable to those of exfoliated cell surfaces. Under in vitro condition, vaginal epithelial cells grown in Ca++ and steroid free medium showed sparsely distributed short, blunt microvilli on the surface, but when the medium was supplemented with estradiol 17 beta, the cell surface showed microridges instead of microvilli. Present in vivo and in vitro studies indicated that the microridges on cell surface are the characteristic feature of the keratinized cells of vaginal epithelium.

Animals↗
PubMed1986

Interaction between lanthanum and lipid moieties of biological membranes.

The binding of colloidal lanthanum to isolated biological membranes and lipid vesicles was studied by optical and X-ray spectroscopy, and by electron microscopy. Excellent correlation was observed using these techniques. The increase in turbidity and electron density appeared to be directly proportional to the extent of negative charge in the system. X-ray microanalysis confirmed the presence of lanthanum on the lipid vesicles. Among the negatively charged phospholipids, phosphatidylinositol showed the greatest affinity for lanthanum.

Animals↗