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Biomedical subjects

A Singh

Publications and source records attributed to A Singh.

At least 397 records · Page 22Linked to original sources
PubMed1995

Cilia in the porcine bile ductule: motile or sensory?

Oligociliated epithelial cells or cells with a solitary cilium were observed lining hepatic bile ductules in pigs. The cilia were situated in the midst of microvilli, and arose from a basal body that was located in the vicinity of the free surface of the epithelium. The axonemal pattern revealed in transverse sections of the cilia was 7 + 1, 8 + 1, 8 + 2 or 9 + 0, Although devoid of the classical axoneme pattern, we assume some of the cilia to be motile, and other to be sensory structures that would assist bile formation and secretion.

Animals↗
PubMed1995

Presence of thyroid antibodies in early reproductive failure: biochemical versus clinical pregnancies.

OBJECTIVE: To evaluate the clinical usefulness of thyroid antibodies in determining early pregnancy outcome. SETTING: University-based facility at the Center for Reproductive Health, University of California, Irvine. PATIENTS: Four hundred eighty-seven infertile patients that successfully conceived with assisted reproductive techniques from January 1991 to December 1992. INTERVENTIONS: An enzyme immunoassay for semiquantification of thyroglobulin (TG) and thyroid peroxidase antibodies used to determine antibody status from stored serum of these patients. MAIN OUTCOME MEASURE: Thyroid antibody status in early pregnancy. RESULTS: Of the 487 patients studied, there were 106 women who were antibody positive for anti-TG, antithyroid peroxidase, or both, and 381 who were negative. The overall incidence of positivity was 22%. In the antibody-positive group there was a 32% clinical miscarriage rate in comparison to 16% in the antibody-negative group. This did reach statistical significance. There was no significant difference between the two groups in the incidence of biochemical or ectopic pregnancies. There also was no significant difference between the groups in age, gravidity, or number of prior pregnancy losses. CONCLUSION: In our patient population, thyroid antibodies proved to be a useful marker for identifying women at risk for clinical miscarriage but they appear not to have an association with biochemical pregnancies.

Abortion, Spontaneous↗
PubMed1995

Estimation of chronic disease load in a rural area of Haryana.

A key informant based survey was done in 1992 to enlist cases of chronic disorders in a rural area of Haryana. Thirty-nine villages selected purposely from a block were surveyed by a trained field worker. He made contacts with key informants like dais, anganwadi workers, health workers, teachers, village elders, etc, to enlist known cases of chronic disorders. In all 812 cases of chronic disease were encountered in 28844 population (28.2/1000). Prevalence of chronic disorders was more in higher age group. Males outnumbered females in younger age group and vice versa for higher age group. Asthma, poliomyelitis, mental illness/retardation were more prevalent in males while hypertension, obesity were reported more in females. Tuberculosis, diabetes, hypertension and asthma were significantly more prevalent in higher age group while poliomyelitis was reported more in children. Consultation rate was high in tuberculosis, asthma, hypertension and diabetes.

Adolescent↗
PubMed1995

Ultrastructural changes in ovarian follicles of monkeys administered hexachlorobenzene.

OBJECTIVE: To test hexachlorobenzene (HCB), an environmental pollutant, for its potential toxicity to the ovary. DESIGN: Nonhuman primates were orally administered the pollutant at doses between 0.01 and 10 mg of HCB/kg of body weight to test viability of ovarian follicles. At the end of dosing period, the monkeys received a compound that contained follicle-stimulating and luteinizing hormones to stimulate development of follicles that would be examined by electron microscopy. ANIMALS: Twenty, 6- to 13-year-old cynomolgus monkeys were randomly assigned to 5 groups. PROCEDURE: The HCB, in concentrations of 0.01, 0.1, 1.0, and 10.0 mg/kg, was orally administered with glucose in gelatin capsules for 13 weeks. Monkeys receiving capsules containing glucose only served as controls. After the 13th week, monkeys were given a compound that contained follicle-stimulating and luteinizing hormones daily during days 2 to 7 from the start of menses. On day 8 of the menstrual cycle, 5,000 IU of human chorionic gonadotropin was administered, and 35 to 38 hours later, 1 ovary from each monkey was obtained during laparotomy. Approximately 1-mm cubes of tissue from each ovary were harvested, fixed by immersion in buffered 2% glutaraldehyde, and processed for transmission electron microscopy. RESULTS: Ultrastructure of ovarian follicles was altered in the monkeys administered HCB. Lesions were observed in the follicles from monkeys given the lowest concentrations of HCB, and comprised condensed mitochondria in the developing ova and follicular cells that contained nuclei with deep indentations and abnormal accumulation of cytoplasmic lipid droplets. Alterations, such as herniation of the ooplasm, degeneration of the follicular cells, and appearance of abnormal spaces between follicular cells were observed in the follicles from monkeys of the 0.1 to 1.0 mg of HCB/kg dosage groups. The most relevant alterations were seen in the mitochondrion, an organelle that appeared to be most sensitive to the compound. Mitochondria were condensed, with abnormal intracristal spaces in the lower-dosage groups, and were markedly degenerated in the 10 mg/kg group. The effect of HCB were dose-related. CONCLUSION: The HCB is a reproductive system toxicant, and its damaging effects may be a result of augmentation of lipid peroxidation, especially in the primary follicle, which abnormally affects cellular membranes and thus, impairs their permeability.

Administration, Oral↗
PubMed1994

Formation and properties of a network gel formed from mixtures of diacetylenic and short-chain phosphocholine lipids.

A polymerizable gel superaggregate has been formed from low concentrations (6 mM) of phospholipid mixtures of polymerizable 1,2-bis(tricosa-10,12-diynoyl)-sn-glycero-3-phosphocholine and 1,2-bis(dinonoyl)-sn-glycero-3-phosphocholine. Transmission electron microscopy (TEM) revealed that the superaggregate structure consisted of a network of twisted, braided fibers and that the pore size of the gel ranged from 0.1 to 1.0 micron. TEM of gel plated with Ni revealed that the width of the fibers was 280 A. Optical microscopy demonstrated that the onset of the gel phase occurred at mole fraction 0.43 DNPC in the absence of salt and 0.36 in the presence of 0.25 M NaCl. Polymerization did not affect the morphology of the gel but did increase its temperature stability.

Calorimetry↗
PubMed1994

Differential effects of brefeldin A on hormonally regulated Na+ transport in a model renal epithelial cell line.

Na+ transport in renal epithelia is regulated by a wide variety of endogenous and exogenous cellular factors. Although most natriferic agents have an action on the amiloride-sensitive Na+ channel, the biochemical pathways which precede activation of the channel remain incompletely defined. One approach to dissecting such intricate pathways is to perturb a specific cellular process and determine its importance in the postulated mechanism. The current studies examine the effect of brefeldin A (BFA), an inhibitor of the central vacuolar system, on basal as well as aldosterone-, insulin-, and forskolin-stimulated Na+ transport. In the A6 cell line, BFA had a time-dependent effect on basal transport. Aldosterone-induced Na+ transport was sensitive to BFA while insulin's action was only partially blocked and forskolin-stimulated Na+ transport was relatively resistant to the action of the inhibitor. These studies highlight differences as well as points of convergence in the natriferic pathways.

Aldosterone↗
PubMed1994

Characterization of a predominantly pistil-expressed gene encoding a gamma-thionin-like protein of Petunia inflata.

We isolated a cDNA clone from a pistil cDNA library of Petunia inflata which encodes a protein, PPT, with sequence similarity to gamma-thionins. Characterization of a genomic clone containing a PPT gene revealed the presence of a single intron. Northern analysis revealed that the PPT gene was predominantly expressed in the pistil during all stages of flower development. Since thionins have been implicated in plant defense against pathogens, PPT may play a role similar to that of other defense-related proteins found in the pistil, defending the pistil against pathogen infection.

Amino Acid Sequence↗
PubMed1994

Evaluation of biomass.

Evaluation of biomass concentration is an important problem encountered in many microbial and other bioprocesses. It determines the catalytic activity of the microbial cell in a given time. Various direct and indirect methods for the estimation of biomass have been developed using physical and biochemical techniques. Despite many promising classical methods available, the evaluation of microbial growth in bioprocesses may sometimes become laborious, impracticable and give erroneous values. Various methods for enumeration of organisms and determination of biomass, including recent developments in monitoring biomass concentration for the control of biotechnological processes, are discussed taking into the consideration their practical importance, usefulness and constraints in application.

Biotechnology↗
PubMed1994

Mediation of the trophic effects of short-chain fatty acids on the rat jejunum and colon.

BACKGROUND/AIMS: Short-chain fatty acids (SCFAs) are trophic to small intestinal and colonic mucosa. This study determined whether SCFAs infused into the cecum out of continuity stimulated jejunal and colonic cellularity and whether these effects were mediated by the autonomic nervous system and/or enterotrophic hormones. METHODS: To eliminate direct trophic effects of SCFAs in contact with mucosa, 60 rats underwent cecal isolation with placement of an infusion catheter into the proximal cecum, formation of distal cecocutaneous stoma, and restoration of intestinal continuity with ileocolonic anastomosis. Rats underwent cecal denervation or remained normally innervated and received 1 of 3 infusions for 10 days: SCFAs, saline, or no infusion. Twenty-four additional rats were assigned to the same groups but underwent infusion into the proximal colon (in circuit). RESULTS: Cecal infusion of SCFAs into innervated rats increased (P < 0.05) jejunal DNA, villous height, surface area, crypt depth, and gastrin without increasing colonic variables. In denervated rats, SCFAs did not significantly affect these variables. However, direct intracolonic infusions of SCFAs increased (P < 0.05) colonic mucosal DNA and crypt depth. CONCLUSIONS: Jejunotrophic effects of cecally infused SCFAs are mediated afferently by the autonomic nervous system and are associated with increased jejunal gastrin. SCFAs have local trophic effects on the colon.

Animals↗
PubMed1994

Hormonal modulation of atrial natriuretic factor receptors and effects on adrenal glomerulosa cells of female rats.

This study was done to determine if a decrease in the aldosterone-suppressant effect of atrial natriuretic factor (ANF) by progesterone and an increase by estrogen was caused by modulation of adrenal zona glomerulosa ANF receptors. Freshly dispersed glomerulosa cells from virgin, 13-15 day pregnant, ovariectomized (OVX) estradiol-17 beta-treated and OVX progesterone-treated rats were used. Competitive displacement of specifically bound [125I]ANF1-28 with unlabelled ANF1-28 yielded concentrations of guanylate cyclase-linked ANF-R1 plus ANF-R2 (clearance) receptors and the displacement with unlabelled ANF4-23 yielded ANF-R2 receptors; the difference between the two was treated as the concentration of ANF-R1 receptors. Pregnancy and progesterone decreased and estrogen increased the number of glomerulosa ANF-R1 receptors. ANF produced a significantly greater suppression of potassium-induced aldosterone secretion in cells from OVX estradiol-treated rats than in cells from OVX progesterone-treated animals. These data suggest that the inhibition of the aldosterone-suppressant activity of ANF by progesterone is the result of a downregulation of ANF-R1 receptors.

Aldosterone↗
PubMed1994

Fibrodysplasia (myositis) ossificans progressiva.

Fibrodysplasia ossificans progressiva (FOP) is a rare hereditary connective tissue disorder. Patients with FOP develop progressive ossification of muscle and connective tissue associated with pain and disability. Onset is typically in childhood, and congenital anomalies of the feet are an early sign of this condition. Pain and stiffness of the spine or an inflammatory mass are common presenting features of FOP. Involvement of the spine often leads to complete fusion mimicking ankylosing spondylitis. Studies of twins and families suggest that FOP is a genetically inherited autosomal dominant trait with complete penetrance but variable expressivity. While radionuclide imaging and computed tomography are very sensitive for new bone formation and greatly assist the diagnosis of FOP, unfortunately, effective therapy is unavailable. We present twins with FOP and review the clinical, radiographic, and genetic manifestations of this disorder.

Adult↗