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Biomedical subjects

A Singh

Publications and source records attributed to A Singh.

At least 469 records · Page 26Linked to original sources
PubMed1993

Prednisone inhibits the efficacy of recombinant human growth hormone in pediatric renal transplant recipients.

To test the efficacy and toxicity of recombinant human growth hormone (rhGH, Protropin, Genentech), we reviewed our experience of its administration of rhGH to pediatric renal transplant recipients. Endogenous growth hormone (GH) levels were measured after stimulation with L-dopa and clonidine in growth retarded children whose height (ht) was greater than or equal to 2 standard deviations (SD) below the mean for age. Criteria for receiving rhGH were either subnormal GH levels (< 10 ng/ml) or a zero growth velocity over the preceding year despite normal GH levels after stimulation. The dose of rhGH administered subcutaneously was 0.1 mg/kg/day for 6 days/week. The efficacy of rhGH was evaluated using growth velocity index (GVI) and height standard deviation (Z) score. Catch-up growth was defined as an increase in Z score (delta Z) > or = 0.4. Twenty patients (17 with subnormal GH levels and 3 with normal GH levels but zero GVI) consented to rhGH treatment. Seventeen patients (14 males, 6 pubertal) have completed one year or more of rhGH therapy and are the subjects of this analysis. All 17 patients were receiving cyclosporine and 12 were receiving prednisone during rhGH therapy. Six of the 17 patients (35%) demonstrated catch-up growth (delta Z + 1.3 +/- 0.13). By regression analysis, the only factor noted to affect rhGH response was the concurrent use of prednisone. All five patients not receiving prednisone demonstrated catch-up growth compared to only 1 of 12 patients receiving prednisone (P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Child↗
PubMed1993

Chronic lead exposure induces ultrastructural alterations in the monkey testis.

The purpose of this study was to establish the effects of lead on the non-human primate testis. Sixteen cynomolgus monkeys maintained in environmentally controlled conditions were administered 1500 micrograms lead acetate/kg bw/day in gelatin capsules. Monkeys were randomly assigned to the following groups: control (n = 3), which received 95% glycerol and 5% distilled water (vehicle) over their lifetime for 9 years; infancy group (n = 4), exposure limited to the first 400 days of life; post-infancy group (n = 5), dosed following 300 days of life to 9 years of age; lifetime group (n = 4), dosed for nine years. All the animals were treated with lead or vehicle for the entire duration of the experiment. The organs from animals in the control group consisted of seminiferous epithelium comprised of typical Sertoli cells containing nuclei with numerous infoldings and longitudinally-oriented profiles of endoplasmic reticulum, microtubules, mitochondria, and lipid droplets that were scarce. Spermatogenic cell types at different developmental stages were observed. Seminiferous epithelium from animals of the treated groups exhibited distortion in the general architecture of the epithelium such that a marked decrease in its height was revealed. In particular, Sertoli cells contained heightened number of lipid droplets and lysosomal elements, and the basal lamina was usually stratified. The magnitude of alterations in the seminiferous tubules was indistinguishable among the three treated groups. These findings support the conclusion that lead is a potent testicular toxin.

Aging↗
PubMed1993

Renal toxicity of nickel, sodium lauryl sulphate and their combination after dermal application in guinea pigs.

The guinea pigs were dermally exposed to nickel (Ni), sodium lauryl sulphate (SLS) and in their combination for 7 and 14 days. The exposure to Ni and SLS produced changes in enzymes and lipid peroxidation in kidney. The exposure to Ni or SLS depicted slight changes while combined exposure to Ni plus SLS exhibited more degenerative changes in kidney. The result of the study suggests that industrial workers and/or populations exposed simultaneously to Ni and SLS produces more damage to kidney.

Administration, Cutaneous↗
PubMed1993

Retained intraocular foreign body simulating choroidal melanoma. A report of two cases.

Many different lesions can be difficult to distinguish from malignant melanomas of the choroid. With the use of modern diagnostic facilities the misdiagnosis rate has been greatly reduced. In a recent report from the Collaborative Ocular Melanoma Study Group the incidence of misdiagnosis was only 0.48%. The presence of a retained intraocular foreign body presenting as a raised pigmented choroidal mass similar to a uveal melanoma is rare. We report two cases in which retained intraocular foreign bodies presented clinically as raised pigmented intraocular lesions. Retained intraocular foreign bodies should be considered in the differential diagnosis of ocular tumours, especially if there are any atypical features.

Aged↗
PubMed1993

Effects of arecoline on phase I and phase II drug metabolizing system enzymes, sulfhydryl content and lipid peroxidation in mouse liver.

The modifying potential of arecoline alkaloid was studied on hepatic drug metabolizing system enzymes, acid soluble sulfhydryl (-SH) content and microsomal lipid peroxidation. Arecoline was administered intraperitoneally to Swiss albino mice at the dose levels of 10, 20 or 40 mg/kg body wt./day for 10 or 30 days. Significant increase in the levels of glutathione S-transferase (GST), cytochrome b5 (Cyt.b5), cytochrome P-450 (Cyt.P-450) and malondialdehyde (MDA) was observed in the arecoline treated groups. Decreased -SH content was apparent by the administration of 40 mg arecoline for 10 or 30 days. The modulation in biotransformation system enzymes has wide significance in the process of neoplastic development as well as in detecting the further role of biometabolized chemicals.

Animals↗
PubMed1993

Ultrastructure of granulosa lutein cells from rats fed hexachlorobenzene.

Corpora lutea from Sprague-Dawley rats that were orally administered 0.0 (control), 1.0, 10.0, and 100.0 mg/kg hexachlorobenzene (HCB) for 21 days were analyzed by electron microscopy. Granulosa lutein cells (GLC) from animals of the 10.0 mg group showed differences from the cells of animals that served as the controls. Golgi complexes and smooth endoplasmic reticulum appeared more conspicuous, possibly due to dilation resulting from hyperactivity. Free polysomes seemed more prominent in the cells of the 10.0 mg group. The GLC architecture from animals of the 1.0 and 100.0 mg groups was similar to that of the corresponding cells in the control group. Since smooth endoplasmic reticulum is involved in the synthesis of steroid hormones, and that free polysomes are engaged in synthesis of cytoplasmic proteins, it is suggested that HCB at a dose of 10.0 mg/kg given for 21 days may alter the synthetic activity of the GLC of the rat.

Animals↗
PubMed1993

Dietary intakes and biochemical profiles of nutritional status of ultramarathoners.

Nutritional status was determined in 17 ultramarathoners registered to participate in the Old Dominion 100-Miler. They had a mean age of 40 +/- 2 yr and ran 67.7 +/- 9.0 miles.wk-1. Subjects maintained 4-d dietary records on two occasions: usual and prerace. Fasting blood samples and 24-h urine collections were also obtained, and concentrations of selected vitamins and minerals were analyzed. Usual and prerace energy, carbohydrate and fat intakes of the ultramarathoners were not significantly different, but usual protein and alcohol intakes were significantly (P < 0.05) higher than prerace intakes. The amount of energy supplied by carbohydrates rose from a usual intake of 54.2 +/- 2.3% to 60.1 +/- 2.4% in the prerace period. Twelve subjects reported taking vitamin/mineral supplements and mean usual and prerace intakes of vitamin and minerals from food and supplements combined met the current recommendations. Biochemical indices of vitamin and mineral status were normal. However, our findings suggest that vitamin B12 metabolism may be altered in ultraendurance runners. Further research is required to determine whether ultraendurance athletes have special nutrition needs.

Adult↗
PubMed1993

Chronic lead exposure induces ultrastructural alterations in the monkey seminal vesicle.

Lead is a toxic and carcinogenic metal that has been extensively associated with male reproductive abnormalities. The purpose of this study was to establish the effects of lead on the primate seminal vesicle. Sixteen cynomolgus monkeys maintained in environmentally controlled conditions were orally administered gelatin capsules containing 1500 micrograms lead acetate/kg bw/day. Monkeys were randomly assigned to the following groups: control (n = 3) which received 95% glycerol and 5% distilled water (vehicle) over their lifetime, infancy (limited to the first 400 days of life; n = 4), post-infancy (dosed following 300 days of life to 9 years of age; n = 5) and lifetime exposure (9 years; n = 4). At necropsy, the seminal vesicles from each animal were removed, fixed in glutaraldehyde, and processed for ultrastructural analysis by conventional methods. The glands from animals in the control group consisted of acini lined by two cell types, viz., tall columnar secretory cells, and round basal cells. Secretory cells possessed microvilli, basally located nuclei surrounded by much rough endoplasmic reticulum, a few lipid droplets, and supra-nuclear regions dominated by pleomorphic membrane-limited secretory granules. All the treated groups exhibited an augmentation in the number of lipid droplets within the secretory cells. In both the infancy and post-infancy groups, a marked reduction in electron-dense cores of the secretory droplets was observed in severely affected regions of the glands. These findings support the evidence that lead is a potent reproductive toxicant, however, further research is needed to determine the consequences of this damage on reproductive performance.

Age Factors↗
PubMed1993

Effects of social support and undermining on African American workers' perceptions of coworker and supervisor relationships and psychological well-being.

Although social undermining is a commonly experienced stressor in human services workplaces, it has received little study in contemporary models of social work stress and burnout. Furthermore, African Americans currently make up nearly 25 percent of self-identified social workers in the United States, yet most literature on personnel relationships in human services does not reference this group. Data collected from a national sample of 288 African American members of the National Association of Social Workers were used to investigate the impact of undermining among coworker and supervisor-supervisee relationships. Multiple regression analyses revealed substantial increases in irritability, depression, anxiety, and depersonalization among social workers when social undermining was included in a set of predictor variables (age, gender, and social support). The presence of social support, however, did not diminish the impact of undermining. The authors discuss several practice and training implications of these findings.

Adult↗
PubMed1992

Analgesia for the reduction of Colles fracture. A comparison of hematoma block and intravenous sedation.

OBJECTIVE: An alternative to general anesthesia was tested against conventional sedation by a double-blind, randomized clinical trial in reduction of Colles fracture. SETTINGS: A large teaching hospital where cases of Colles fracture are not different from those seen in district hospitals. PATIENTS: Sixty-six out of 80 consecutive cases with this fracture were selected from March to August 1990 on the basis of: 1) informed consent; 2) no contraindication to any method of analgesia; 3) no analgesic during the past 8 hours; 4) injury duration less than 96 hours; 5) no mental, auditory, or visual impairment; and 6) no associated injury. INTERVENTIONS: Patients were randomized into 2 equal groups. After tests for Xylocaine (Astra brand of lidocaine hydrochloride) sensitivity in both groups, the A group received 30 mg of pentazocine with 5 mg of diazepam intravenously on the dorsum of the affected wrist (sedation group), whereas the B group received 20 cc of 1.5% Xylocaine into the fracture hematoma. Five minutes later the fracture was reduced and immobilized by Lakhtakia or A. Singh. MAIN OUTCOME MEASURES: Thirteen to 15 hours later Manglik, blinded to the analgesia status of the patient, recorded pain before, during, and after reduction using Visual Analogue Scale (VAS). MAIN RESULTS: Statistically, randomization and blinding were found to be effective. The pain scores during reduction in the local anesthetic group (median = 1.8) were significantly less than those in the sedation group (median = 8.7), P < 0.001 using the Wilcoxon rank sum test. The difference persisted in regression analysis. The 2 methods proved comparable in safety and other measures of effectiveness. CONCLUSIONS: Hematoma block by local anesthetic is a safe and effective alternative to sedation in reduction of Colles fracture.

Adult↗
PubMed1992

Purification of cationic cystine-rich peptides from rat bone marrow. Primary structures and biological activity of the rat corticostatin family of peptides.

Seven cationic, cystine-rich peptides of 29 to 32 amino acid residues have been purified from extracts of rat bone marrow (R-1, R-1a, R-1b, R-2, R-3, R-4 and R-5). Structural analysis clearly indicated that all seven peptides belong to the corticostatin/defensin family of leukocyte-derived peptides known to participate in oxygen-independent killing of phagocytosed bacteria. For R-1 to R-5, six cysteine residues were found at characteristic and highly conserved positions. R-1a and R-1b were partially characterized and appear to be structural variants of R-1. Aside from the conserved cysteines, there is a remarkable degree of structural diversity evident within the sequences of those members of the corticostatin/defensin family characterized so far. The structures of the peptides that we have purified can be compared directly with the sequences obtained for rat defensins isolated from extracts of peritoneal neutrophils (Lehrer, Ganz and Selsted, Cell, 64 (1991) 229-230). Some discrepancies are apparent which can be explained in terms of proteolytic cleavage of several of these peptides at both amino- and carboxyl-termini. The corticostatins owe their bioactivity to their ability to compete with corticotropin for occupancy of the corticotropin receptor (Zhu, Hu, Mulay, Esch, Shimasaki and Solomon, Proc. Natl. Acad. Sci. USA, 85 (1988) 592-596). The potency of these peptides can be expressed in terms of their capacity to inhibit the steroidogenic response of isolated rat adrenocrotical cells half-maximally stimulated by corticotropin (i.e., at the ED50 concentration for corticotropin in this assay, namely 33 pM). In this assay, the rat peptides R-1, R-2 and R-3 were shown to be inactive. In contrast, the more cationic peptides R-4 and R-5 were found to inhibit steroidogenesis. R-4 was somewhat less active than rabbit corticostatin (IC50 25 nM) showing an IC50 value of 50 nM. R-5 appeared to be significantly less potent than R-4. The lower yield of R-5 precluded an accurate estimate of the corticostatic potency of this peptide. R-4 differs in structure from R-5 in having an arginine to serine substitution at position 7. It can be concluded that an arginine at this position accounts, at least in part, for the corticostatic activity of R-4.(ABSTRACT TRUNCATED AT 400 WORDS)

Adrenocorticotropic Hormone↗
PubMed1992

Lipid accumulation by a cellulolytic strain of Aspergillus niger.

Lipid accumulation by a cellulolytic mold, Aspergillus niger, was studied. The amount of lipid accumulated ranged from 13.6-16.6% on various carbon sources, namely glucose, xylose, avicel (microcrystalline cellulose) and bagasse (a natural lignocellulosic substrate). Neutral lipids, phospholipids and glycolipids of the mycelia varied from 41.0-46.2%, 34.9-38.4% and 18.7-22.6% of total lipids, respectively. Unsaturated fatty acids comprised around 80% of total fatty materials with linoleic and oleic acid predominating. Of the four nitrogen sources tested, NH4Cl was the best source for lipid synthesis from cellulose (bagasse). Optimum temperature range for growth and lipid synthesis was 25-30 degrees C.

Aspergillus niger↗
PubMed1992

The familial occurrence of Parkinson's disease. Lack of evidence for maternal inheritance.

A questionnaire concerning the occurrence of Parkinson's disease in parents was administered for 252 patients with Parkinson's disease. Eleven fathers and five mothers of patients were reported to also have had this disease. These data fail to provide support for the hypothesis that Parkinson's disease is the result of maternal inheritance of an abnormal mitochondrial gene. This conclusion is further supported by a review of similar studies in the literature and an additional unpublished study, which revealed that of 922 patients with this disease, 37 fathers and 19 mothers were reportedly affected.

Aged↗
PubMed1992

Lack of major olfactory dysfunction in MPTP-induced parkinsonism.

The olfactory function of 6 patients whose parkinsonism was the result of intravenous administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) was compared to that of 12 age-matched patients with idiopathic Parkinson's disease (PD) and 10 age-matched normal control subjects. Unlike their PD counterparts, the olfactory test scores of patients with MPTP-induced parkinsonism did not differ significantly from those of control subjects. These findings suggest that MPTP-induced parkinsonism, unlike idiopathic PD, is unaccompanied, on average, by major alterations in the ability to smell.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗