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Biomedical subjects

D Singh

Publications and source records attributed to D Singh.

At least 145 records · Page 8Linked to original sources
PubMed1998

Functional role of cysteine residues in the Na+/H+ exchanger effects of mutation of cysteine residues on targeting and activity of the Na+/H+ exchanger.

We investigated the role of cysteine residues in activity and localization of the NHE1 isoform of the Na+/H+ exchanger. Each of the nine cysteine residues was mutated to serine or arginine. Mutation of the first serine (amino acid number 9) and serine number six (amino acid number 477) resulted in dramatic decreases in detectable activity of the Na+/H+ exchanger when transfected into AP-1 cells. Some other mutations resulted in minor decreases in activity of the protein. Confocal and light microscopy of mutant cells with decreased activity showed that the antiporter protein was mostly retained in an intracellular compartment which colocalized with the medial-Golgi cisternae. Smaller amounts of active protein still remained targeted to the plasma membrane in these mutants. Treatment of wild-type cells with DTT also caused the retention of the Na+/H+ exchanger to the same intracellular compartment. The results suggest that cysteines play an important role in intracellular folding and trafficking of the Na+/H+ exchanger.

Amino Acid Substitution↗
PubMed1998

Penetration and intracellular routing of nucleus-directed peptide-based shuttles (loligomers) in eukaryotic cells.

Loligomers are multitasking, peptide-based shuttles that are able to penetrate cells and self-localize into distinct cellular compartments. In particular, loligomer 4 incorporates internalization and nuclear import sequences as well as reporter groups. The intracellular routing of loligomer 4 was analyzed by microscopy and flow cytometry, to define and demonstrate localization events. Electron micrographs of CHO cells exposed to a biotinylated derivative of loligomer 4 as well as confocal images of CHO cells treated with rhodamine-labeled loligomer 4 indicate their presence in the cytosol, endocytic vesicles, and the nucleus of CHO cells. Loligomer 4 accumulates irreversibly inside cells. Uptake of loligomer 4 by six mammalian cell lines (Daudi, EL4, CHO, COS-7, VERO, and HeLa) was proven by flow cytometry, establishing the generality of the principle. Cells presented as monolayers typically were less able to endocytose the construct than cells grown in suspension. Cellular accumulation of loligomer 4 varied between cell lines with COS-7 and VERO cells showing the highest level of uptake. Plasmids harboring reporter genes could be transported efficiently inside CHO cells, suggesting that loligomer 4 either alone or noncovalently associated with large macromolecules can effectively reach the nucleus of cells. In summary, loligomer 4 constructs provide a simple synthetic platform for the design of guided intracellular agents.

Animals↗
PubMed1998

Continuous ethanol production from sugarcane molasses using a column reactor of immobilized Saccharomyces cerevisiae HAU-1.

A fermentation system for the continuous ethanol production from sucrose and molasses using calcium alginate immobilized Saccharomyces cerevisiae strain HAU-1 has been optimised. Immobilization of active yeast cells (30%, w/v) was accomplished in 1.5% calcium alginate and these yeast-beads were employed for ethanol production in a vertical column reactor. High ethanol productivity was achieved with a medium containing 10%, w/v sucrose at a dilution rate of 0.20 h-1. Alginate beads containing 30-50% yeast cell--mass resulted in high productivity 60.4 g l-1 h-1). Sugarcane molasses containing 15% total sugars was fermented in column reactor to produce 6.0%, v/v ethanol in continuous system. These yields could be improved to 7.0% with overall 11% increase in fermentation--efficiency with the use of acid-clarified sugar cane molasses medium.

Alginates↗
PubMed1998

Laparoscopic surgery for abdominal aortic aneurysms. Technical elements of the procedure and a preliminary report of the first 22 patients.

BACKGROUND: Laparoscopic surgery for infrarenal aortic aneurysms is based on the principle of retropertoneal exclusion of the aneurysms sac with aortofemoral or aortoiliac bypass. METHODS: Of 22 patients who met the selection criteria, 20 successfully underwent laparoscopic aortic surgery at Morristown Memorial Hospital between February and October 1997. Technical elements and steps of this operation are described and illustrated. RESULTS: Within 30 days of surgery, 2 patients died and 9 had various major and minor perioperative complications. As a group, the laparoscopic patients had less postoperative pain, needed fewer hours of ventilator support, had shorter intensive care unit (ICU) and hospital lengths of stay, and resumed diet and normal activity earlier than the historical norms of patients undergoing transabdominal or retroperitoneal aortic resections at the same institution. CONCLUSIONS: These early observations suggest that the laparoscopic treatment of infrarenal abdominal aneurysms may have several significant potential benefits. Long-term results and randomized prospective studies with patients matched by risk stratification will be needed to confirm these impressions.

Aged↗
PubMed1998

Burn mortality in Chandigarh zone: 25 years autopsy experience from a tertiary care hospital of India.

An analysis of autopsy records of burn victims revealed that most burn deaths occurred in the age group 21-40 years (67 per cent) with female preponderance (61 per cent) in all age groups except in the extreme age groups. 62 per cent of burn cases originated in urban areas. The majority of subjects (99 per cent females and 76 per cent males) died as a result of flame burns. Kerosene was the most common factor (76 per cent) in burn deaths. 11 per cent of deaths were due to the stove bursting and 27 per cent of victims died due to leakage of oil from the stove. 39 per cent of subjects sustained burns when their clothes caught fire. Scalds (3.3 per cent), electrical (4.7 per cent) and chemical (2.3 per cent) burns were more commonly seen in males, mainly sustained at their working place. Accidental burns were observed in 80 per cent of subjects followed by suicidal (16.2 per cent) and homicidal burn assaults (4.1 per cent). Peak incidence of burns in females was observed between 5.01 a.m. and 11 a.m. (38 per cent), which was the time of least incidence in males (10.3 per cent). The opposite trend was seen between 11.01 p.m. and 5 a.m. Among males, burn deaths were more common (85 per cent) in those who were living alone, away from their families; whereas in women the incidence of burn deaths was higher (74 per cent) in those living with their families. The majority of deaths due to burns occurred within one week (77 per cent) of the incident. Septicaemia was the major cause of death (55 per cent).

Accidents↗
PubMed1998

Iris-claw lens in phakic eyes to correct hyperopia: preliminary study.

PURPOSE: To evaluate the results of implanting convex, iris-fixated, anterior chamber intraocular lenses (IOLs) in phakic eyes to correct high hyperopia. SETTING: Robert Koch Hospital, Hannover-Gehrden, Germany (Center A), and Dr. Daljit Singh Eye Hospital, Amritsar, India (Center B). METHOD: Two eyes at Center A and 67 at Center B had implantation of an anterior chamber, convex, iris-fixated IOL. Follow-up of the 2 eyes at Center A was 91 months. Mean follow-up at Center B was 78 months +/- 24 (SD) (range 12 to 120 months). RESULTS: At Center B, all eyes except two in one patient had clear corneas and no iritis or glaucoma at the last follow-up. The patient with complications (glaucoma and corneal degeneration in both eyes) did not return for follow-up until more than 4 years postoperatively and thus did not have adequate postoperative care. CONCLUSION: Implantation of a convex iris-claw lens into the anterior chamber of phakic eyes to correct high hyperopia was successful from a refractive aspect. The clinical risks appear tolerable. However, life-long observation by endothelial microscopy is mandatory.

Adolescent↗
PubMed1998

Solid-state characterization of chlordiazepoxide polymorphs.

A novel crystal form (form II) of the benzodiazepine chlordiazepoxide is reported. The new polymorphic phase was characterized and distinguished from the standard form (form I) by X-ray diffractometry, differential scanning calorimetry, infrared spectroscopy, microscopy, solution calorimetry, and solid-state nuclear magnetic resonance. The formation of form II was dependent on the crystallizing solvent, being the predominant form isolated from methanol. Recrystallization from other alcoholic solutions (ethanol, propanol, and butanol) and toluene yielded form I. Differential scanning calorimetry and powder X-ray diffraction indicated that the two forms were enantiotropically related with a transition of form II to form I occurring between 200 and 225 degreesC. Visual examination by hot stage microscopy in this temperature range revealed a dramatic solid-state transition. Single-crystal X-ray analysis was performed on form II which was found to crystallize in the triclinic space group P1 with a = 10.736(2) A, b = 16.921(4) A, c = 17.041(4) A, alpha = 100.76(1) degrees, beta = 95.27(1) degrees, gamma = 97.53(1) degrees, Z = 8, and dcal = 1.33 g/cm3. When compared with the published crystal structure of form I, the cell symmetry, volume, and density were similar. Both structures consisted of four crystallographically independent molecules linked in pairs through intermolecular hydrogen bonding. Differences were observed in the packing arrangement of the dimers in the polymorphs. The small heat of transition calculated from solution calorimetry (1.5 kJ mol-1) was sufficient to effect a crystallographic rearrangement of the dimers.

Calorimetry, Differential Scanning↗
PubMed1998

Comparative disposition kinetics of albendazole in sheep following oral and intraruminal administration.

The pharmacokinetics of albendazole was studied in sheep following single oral and intraruminal administration at nematocidal dose rates. The disposition curves of its metabolites indicated increased uptake of the drug in sheep following intraruminal as compared to oral dosing (p < 0.05). The increased bioavailability of benzimidazole anthelmintics given by the intraruminal route could be exploited for optimizing the use of anthelmintic for sustained parasite control in small ruminants.

Administration, Oral↗
PubMed1998

Frequency and timing of coital orgasm in women desirous of becoming pregnant.

Generally, no functional role, except pleasure, is assigned to a women's coital orgasm. Recently, however, researchers have suggested that women can regulate the number of sperm accepted or rejected by manipulation coital orgasm timing. Baker and Bellis (1995) demonstrated that women retain more sperm if coital orgasm occurs after, rather than before male ejaculation. The present study investigated (i) factors associated with coital orgasm frequency and (ii) whether women desirous of becoming pregnant report more coital orgasms after than before their partners. Sixty-nine women rated their desire for pregnancy and answered questions about their sexual behaviors, coital orgasm frequency, and coital orgasm timing in relation to their partners. In regression analysis, coital orgasm frequency was predicted by foreplay duration, masturbation frequency, and active sexual participation; desire for pregnancy did not predict coital orgasm frequency. Desire for pregnancy was predicted by age (negatively), active sexual participation (positively), and positively by orgasm after partner ejaculation. Consistent with the Baker and Bellis hypothesis, frequency of orgasm after partner's orgasm remained a significant predictor for desire for pregnancy after controlling for degree of marital happiness, sexual foreplay duration, and coital orgasm frequency.

Adult↗
PubMed1998

Variation in the immune status of two Australian pig breeds.

OBJECTIVE: To investigate the variation in immune competence of two Australian pig breeds. DESIGN: A panel of immune tests were used to assess breed and sire differences in weaner piglets of Large White and Duroc breeds. PROCEDURE: All piglets were immunised against porcine leptospirosis. Blood samples were taken for studies on lymphocyte phenotypes, mitogenic responses of blood cells and serological analysis. RESULTS: Significantly larger blood leucocyte numbers were found in Large White piglets compared with Duroc piglets after vaccinations. No significant difference in concanavalin A induced blood cell proliferation was found between these two breeds before or after vaccinations. Some significant breed variation in blood lymphocyte phenotypes was found. While the age-related changes of lymphocyte phenotypes were similar for the two breeds, the Large White breed had significantly larger numbers of CD2+ and CD4+ cells than the Duroc breed after the two vaccinations. There were also significant sire effects on CD8+ cells within the Large White breed after the first vaccination. No significant breed difference was detectable in serum IgG concentrations but sire differences within each breed before the primary vaccination were found. The serum antibody response to vaccination against leptospirosis was generally small, and showed no variations due to either breed or sire. No gender effects were found during the entire study. CONCLUSION: The study demonstrated significant differences in some important immune components of the pig breeds studied. This may in turn indicate the variation in their immune competence or disease resistance. However, further investigation into the heritability and correlation with specific immune responses is required.

Agglutination Tests↗
PubMed1998

Laparoscopic aortic aneurysm resection.

PURPOSE: To describe a laparoscopic technique for resection of infrarenal abdominal aortic aneurysms (AAAs). METHODS: The operation is based on the principle of retroperitoneal reinforced staple exclusion of the aneurysm sac with aortobifemoral or aortoiliac bypass using gas and gasless laparoscopic techniques. Patients were eligible for this procedure if their infrarenal AAAs (with or without iliac artery involvement) were considered appropriate for surgical resection; however, renal or other visceral arterial stenoses, aneurysmal disease requiring surgical treatment, and/or aneurysms of the hypogastric arteries excluded patients from laparoscopic AAA resection. RESULTS: Of 31 candidates for this procedure, 9 were excluded owing to high surgical risk. Twenty-two patients (16 males; age range 62 to 88 years) were deemed appropriate for the laparoscopic procedure. Maximum aneurysm diameter ranged from 4.0 to 8.0 cm. The operation was completed successfully in 20 (91%) patients. Two (9%) deaths in high-risk patients admitted early to the study occurred within 30 days of surgery. The only major complication was an injured ureter, for which a nephrectomy was performed. Comparison to a historical cohort of conventionally treated patients showed that the study group needed less ventilator support, had shorter intensive care and hospital stays, and resumed diet earlier despite relatively prolonged anesthesia and aortic clamping times. CONCLUSIONS: The laparoscopic approach to infrarenal AAAs appears feasible, with several potential advantages in low- and moderate-risk patients. Once the technique is optimized, randomized prospective studies will be needed to verify the apparent benefits demonstrated by these initial patients.

Aged↗
PubMed1998

Changes in superoxide dismutase activity and estradiol-17 beta content in follicles of different sizes from ruminants.

Subcellular distribution of oxygen free radical scavenging enzymes has recently been demonstrated in goat ovary. In the present study the follicles of the follicular phase were isolated mechanically from goat and sheep ovaries and grouped as small (< 3 mm), medium (3-6 mm) and large (> 6 mm) follicles. The specific (units/mg protein) and total (units/g tissue) activity of superoxide dismutase (SOD) was estimated in homogenate of different sizes of follicles. The small follicles of both the species contained highest specific and total activity (6.99 +/- 1.49, 107.9 +/- 3.1 in sheep and 3.57 +/- 0.09, 76.5 +/- 4.0 in goat, respectively), whereas large follicles showed lowest specific and total activity (32.02 +/- 0.25, 80.4 +/- 5.5 in sheep and 1.71 +/- 0.06, 63.20 +/- 2.20 in goat, respectively). The estradiol-17 beta was also estimated and expressed as ng/follicle. The results show that estradiol-17 beta content was highest in large follicle (8.00 +/- 0.46 in sheep and 4.5 +/- 0.73 in goat). The content of estradiol-17 beta was increased progessively as the size of the follicles increased. From these findings, an inverse relationship was observed between SOD activity and estradiol-17 beta content in the follicles of different sizes from ruminants which may have functional role in follicle development and steroidogenesis.

Animals↗
PubMed1998

Changes in catalase activity and hydrogen peroxide level in rat ovary during estrous cycle and induction of catalase in rat ovary by estradiol-17 beta.

Catalase activity in the whole ovary homogenate and hydrogen peroxide level in the differentially centrifuged fractions of the ovary homogenate during each stage of estrous cycle were measured. The highest catalase activity was observed in the metestrous which declined in the estrous and proestrous and was lowest in the diestrous. An inverse relationship was found between catalase activity and hydrogen peroxide production. Treatment of immature (28-29 days old) female rats with estradiol-17 beta (5 micrograms in 0.2 ml oil/animal/day for consecutive 3 days, s.c.) increased the ovarian catalase activity. The findings indicate that the free radical-scavanger system may have functional role in the ovary.

Animals↗
PubMed1997

The Na+/H+ antiporter potentiates growth and retinoic acid-induced differentiation of P19 embryonal carcinoma cells.

The Na+/H+ exchanger is a ubiquitous plasma membrane protein that is responsible for pH regulation and is activated by growth factors. We examined the role of the Na+/H+ exchanger in cell growth and differentiation. Treatment of P19 cells with the Na+/H+ exchanger inhibitor Hoe 694 eliminated retinoic acid-induced differentiation in this cell line. We developed a P19 embryonal carcinoma cell line that was deficient in the Na+/H+ antiporter. Na+/H+ exchanger-deficient cells were reduced in the rate of cell growth and this effect was enhanced by the removal of added HCO3- and by reducing extracellular pH. The antiporter-deficient cells were also markedly deficient in their ability to differentiate to neuronal-like cells and recovered this ability when the Na+/H+ antiporter was reintroduced. The results show that the absence of Na+/H+ antiport as a pH regulatory mechanism can result in deficiencies in both cell growth and differentiation in embryonal carcinoma cells.

Animals↗
PubMed1997

Interactions of a high mobility group-like protein with human mitochondrial DNA.

A number of nuclear-encoded proteins are known to bind to the mitochondrial genome and may be involved in mitochondrial replication and in mitochondrial diseases. Mitochondrial diseases such as Kearns-Sayre syndrome (KSS) are flanked by common direct repeats. To study protein binding to these mitochondria DNA regions we used gel mobility shift binding assays. Proteins present in nuclear or in mitochondrial extracts from normal or KSS-derived fibroblasts bound to a 280-bp mitochondrial DNA fragment encompassing a deletion breakpoint in the mitochondrial genome. In addition, nuclear and mitochondrial protein bound to a nearby surrounding fragment and to a synthetic oligonucleotide with a related consensus DNA sequence. Southwestern blot analysis showed that the DNA binding ability resided in a 35-kDa protein. The amino terminal sequence of the 35-kDa protein was very similar to human high mobility group proteins. These results suggest that this protein may be involved in mitochondrial DNA deletions.

Amino Acid Sequence↗