Biomedical subjects

A Singh

Publications and source records attributed to A Singh.

At least 991 records · Page 55Linked to original sources

PubMedDate not supplied

Pebbling of the skin: a marker of Hunter's syndrome.

A 9-year-old boy, the third child of nonconsanguinous parents, presented with asymptomatic, solid, raised skin lesions over the upper back. They first appeared at the age of 4 years. Gradually similar lesions appeared over the chest, neck, arms, and thighs. On examination, he had firm, hypopigmented to skin-colored papules and nodules which coalesced to form ridges in a reticular pattern (pebbling of the skin) and were arranged bilaterally and symmetrically over the scapulae, pectoral region of the chest, and lateral aspects of the arms and thighs. They resembled sulci and gyri of the brain. He had normal intelligence, short stature, coarse facial features, thick lips, a large tongue, clear corneas, a protuberant abdomen with hepatosplenomegaly, and broad hands with clawlike contractures of the distal interphalangeal joints. Investigations revealed cardiomegaly and proximal tapering of metacarpal bones. Although peripheral blood smear and urine spot test for mucopolysaccharides were negative, histopathology of a representative skin lesion was compatible with the diagnosis of Hunter's syndrome. The case is reported for its rarity and the typical skin lesions, the recognition of which may be helpful in diagnosis and genetic counseling.

Child↗

PubMedDate not supplied

Cutaneous manifestations of chronic renal failure in children of color.

One hundred percent of adult patients with chronic renal failure (CRF) develop cutaneous findings as a result of uremia or due to therapeutic interventions. To date, pediatric incidence studies have been limited to Caucasian children. However, recent reports have indicated that more African American patients progress to end-stage renal disease (ESRD). This is the first study to assess the prevalence of renal failure-related skin disease in children of color, including African American and Hispanic patients. Thirty children were evaluated by history and physical examination, with assignment to one of three treatment categories: transplanted (n = 10), dialyzed (n = 16), or medically managed (n = 4). Skin findings were divided into uremic, drug-related, or infectious disease types. The incidence of skin disease was 100%. Xerosis was the single most common finding, often accompanied by pruritus. Cushinoid features were common despite the addition of steroid-sparing agents. Cyclosporin A-treated African American children had a high incidence of gingival hypertrophy (72%) and an even higher incidence of hypertrichosis (100%). Acral warts and nevi were common findings, the latter correlating with the length of immunosuppression. There is a high incidence of cosmetically disfiguring side effects (Cushinoid facies, hypertrichosis, and gingival hypertrophy) in children within all treatment categories, primarily related to drug treatment. Further study is required to determine the long-term sequelae, including psychological disturbances, of cutaneous disease in children of color with CRF.

Adolescent↗

PubMedDate not supplied

Cancer of the buccal mucosa: are margins and T-stage accurate predictors of local control?

UNLABELLED: Cancer of the buccal mucosa is an uncommon and aggressive neoplasm of the oral cavity. Less than 2% of patients treated for cancer of the oral cavity at Roswell Park Cancer Institute (RPCI) from 1971 to 1997 had primary buccal cancers. Because the majority of these patients did not undergo any adjuvant treatment, this group provided us with the opportunity to assess the relationship between margin status and local recurrence for both small (T1-T2) and large (T3-T4) tumors treated with surgery alone. MATERIALS AND METHODS: The RPCI tumor registry database reported 104 patients who were treated for buccal carcinoma. A retrospective chart review identified 27 patients who met our criteria for a buccal mucosal primary tumor (epicenter of the mass in the buccal mucosa). There were 13 men and 14 women, ranging in age from 34 to 94 years (mean, 75). Data were collected regarding patient demographics, presenting symptoms, stage, treatment received, and outcome. RESULTS: All patients underwent surgical resection of their primary lesion; 21 (75%) had T1 or T2 tumors. The rate of local recurrence was 56% for the group as a whole. Patients with close or positive margins had a 66% local failure rate as compared with 52% when surgical margins were negative (greater than or equal to 5 mm from the resection margin after tissue fixation; P = ns). Among those in whom negative margins were achieved, patients with T1-T2 disease had a 40% local failure rate with surgical resection alone. CONCLUSIONS: Local excision of T1 and T2 buccal mucosa cancers with pathologically negative margins had a high rate of local recurrence in our series. Low T-stage and negative margins are not adequate predictors of local control. Even early buccal tumors may benefit from adjuvant therapy to enhance local control.

Adult↗

PubMedDate not supplied

Total pericardial replacement. Design and preliminary evaluation in greyhounds.

Existing pericardial substitutes, used for the prevention of pericardial and pleural adhesions to the epicardium, are in the form of a patch. To improve on this concept, an elastic, anatomically correct, implantable sac has been developed for total pericardial replacement. Total pericardial substitutes fabricated from Silastic silicone rubber and Mitrathane polyetherurethane urea were implanted in greyhound dogs and harvested at 8 weeks. Pericardial adhesions were prevented by the substitutes that remained intact. Fibrous tissue formation had occurred on the epicardium underlying the substitutes, the extent being more severe in response to the Silastic compared with the Mitrathane. However, the Silastic was superior to the Mitrathane in retention of its tensile strength and elastic modulus over the implant period (p less than 0.05). Further development of total pericardial substitutes from different materials shows promise.

Animals↗

PubMedDate not supplied

Lean body mass estimation by creatinine kinetics, bioimpedance, and dual energy x-ray absorptiometry in patients on continuous ambulatory peritoneal dialysis.

Lean body mass (LBM), which is fat free body mass, can be used as an index of nutritional status. We evaluated three techniques for LBM estimation, including dual energy x-ray absorptiometry (DEXA), creatinine kinetics (CrKin), and bioimpedance (BI) in 10 patients on continuous ambulatory peritoneal dialysis (CAPD). Two different formulae were applied for BI LBM estimation, Segal (S) and Deurenberg (D). Mean values (+/- SEM) of LBM estimated were 48.2 +/- 3.6, 46.12 +/- 2.87, 43.32 +/- 3.87, and 41.27 +/- 4.26 by DEXA, BI-S, BI-D, and CrKin, respectively. LBM by CrKin was significantly lower than that by DEXA and BI-S values. There was no statistically significant difference between DEXA and BI-S values. Statistically significant correlations were found between LBM values by all methods. Particularly strong correlations were found between DEXA versus BI-S (r = 0.976) and BI-S versus BI-D (r = 0.98). Because clinical assessment of hydration status is inaccurate, and both BI and DEXA measure excess extracellular water in LBM, falling muscle mass may be missed by these techniques. The CrKin technique for estimating LBM at normal body fluid volumes (dry weight) may be a better index of nutritional status in patients on CAPD because this may truly reflect the dry LBM and changes in muscle mass. Both DEXA and BI include excess body water in LBM and may mask malnutrition in the presence of subclinical or clinical overhydration, which is common in patients on peritoneal dialysis.

Absorptiometry, Photon↗

PubMedDate not supplied

Experimental drug-induced changes in renal function and biodistribution of 99mTc-MDP.

Increased renal uptake of 99mTc methylene diphosphonate (MDP) was observed irregularly in rats after methotrexate, vincristine or gentamicin, administered separately. Cisplatin regularly induced a dose-related increased MDP uptake which correlated with the degree of tubular damage histologically. The augmented MDP renal uptake was not consistently accompanied by a decreased clearance of simultaneously injected I-131 Hippuran, particularly at lower drug dose levels. This observation agreed with previous evidence that the mechanisms of tubular transport of diphosphonates and organic acids like Hippuran are different. At higher dose levels, the augmented MDP uptake was accompanied by increased renal calcium, hypophosphatemia, elevated serum urea nitrogen and creatinine, and only occasional, mild hypercalcemia. The magnitude of the increased renal uptake of MDP observed could not be explained by alterations in iron metabolism or by dehydration. Drug-induced renal retention of MDP by a factor of 2 or more above normal appears to be a useful indicator of tubular damage when other parameters of renal function are sometimes normal.

Animals↗

PubMedDate not supplied

Uranyl nitrate-induced proximal tubule alterations in rabbits: a quantitative analysis.

Naturally occurring uranium in drinking water is a significant health concern in several areas of North America. Because the kidney is a known target organ to examine the effects of uranium or its compounds, the objective of this study was to determine whether kidney repair occurs after exposure to, and withdrawal of, uranyl nitrate (UN). This work, part of a larger study to establish safe levels of uranium in drinking water supplies, examined the ultrastructural changes in proximal tubule cells of New Zealand white rabbits following subchronic exposure to UN in water and for 91 days after exposure ended. The rabbit was chosen as the experimental animal because of its high sensitivity to uranium. Animals were exposed to 24 or 600 mg UN per liter (UN/L) in drinking water for 91 days, with no recovery or recovery periods of 45 or 91 days. Ultrastructural changes, quantified by a stereological image analysis system based on point counting, were observed in renal proximal tubules (PTs). Each electron micrograph was statistically considered an experimental unit. The severity of lesions was directly proportional to the dose. Animals exposed to 600 mg UN/L had the most severe lesions; nevertheless, alterations were remarkable in animals exposed to the low dose. At both recovery periods, the lesions were significantly more severe than those in animals of the no-recovery group, which may result from the kidney's ability to store uranium. The PT cells had increased lysosomal and vacuolar mass as well as variations in mitochondrial mass. In addition, there was epithelial cell degeneration with a focal loss of brush borders, thickening and splitting of tubular basement membrane, and occasionally cell necrosis. Interstitial fibrosis of the renal cortex persisted as the recovery period increased in the animals of UN-dosed groups. Alterations may be due to disturbed fluid transport across the PT and other cells and decreased cell respiration resulting from damaged cell constituents. Cell damage caused by UN in drinking water persisted throughout the 91-day recovery period. By eventually determining the no observable effect level for the kidney by UN, this study may assist in devising a model to ascertain the safe levels of uranium in water.

Animals↗

PubMedDate not supplied

Nitecapone and selegiline as effective adjuncts to L-DOPA in reserpine-induced catatonia in mice.

Reserpine-induced catatonia is a widely accepted animal model of Parkinson's disease. In the present study, reserpine (5 mg/kg i.p.) and alpha-methylpara-tyrosine (AMPT) (200 mg/kg i.p.) induced catatonia in mice 20 h and 1 h before the experiment, respectively, as assessed using the rota-rod and bar tests after reserpine treatment. There was a significant decrease in fall-off time in the rota-rod test and a significant increase in time spent on the bar in the bar test as compared to the untreated control mice. Combination therapy with L-DOPA (100 mg/kg i.p.) and carbidopa (10 mg/kg i.p.) was less effective in reversing catatonia as compared to higher doses of L-DOPA (200 mg/kg i.p.) and carbidopa (20 mg/kg i.p.), which showed intense hyperactivity in reserpinized mice. Pretreatment with nitecapone (30 mg/kg i.p.), a COMT inhibitor, or selegiline (10 mg/kg i.p.), a MAO-B inhibitor potentiated the motor stimulant actions of subthreshold doses of the L-DOPA (100 mg/kg i.p.) and carbidopa (10 mg/kg i.p.) combination. Amantadine (40 mg/kg i.p.), but not bromocriptine, potentiated the effects of L-DOPA treatment. The NMDA antagonistic action of amantadine may have beneficial effects. It is concluded that COMT and MAO-B enzymes play an important role in the metabolism of dopamine and administration of a COMT or MAO-B inhibitor may prove to be a better adjunct to L-DOPA therapy than a dopamine receptor agonist in Parkinson's disease.

Animals↗

PubMedDate not supplied

Subchronic toxicity of 2,4,4'-trichlorobiphenyl in the rat liver: an ultrastructural and biochemical study.

2,4,4'-Trichlorobiphenyl or PCB congener 28 was given to Sprague-Dawley weanling rats and the experimental diets were prepared by mixing the congener in 4% corn oil. The congener was administered to animals placed in four groups, each comprising 10 males or females. The diets contained 0.05, 0.5, 5, or 50 ppm congener. The fifth or control group comprised animals that received diets mixed with corn oil. Thirteen weeks after commencement of dosing, animals were euthanized and liver specimens were harvested from the animals and prepared for electron microscopy and biochemical analyses. The hepatocyte architectural modifications included an augmentation of SER profiles and an elevation of peroxisome numbers in animals regardless of gender, and mitochondrial abnormalities in the females only. Mitochondrial aberrations consisted of abnormal shapes and cristae in atypical orientation. The alterations were revealed in animals of the 5-and 50-ppm groups and were more extensive in the females. Ethoxyresorufin-O-de-ethylase activity was significantly high in the animals of the 50-ppm group. The results suggest that the female rats were more sensitive than the males to congener 28, and the no observable adverse effect level (NOAEL) was believed to be 0.5 ppm for the congener.

Animals↗

PubMedDate not supplied

Toxicity of PCB 105 in the rat liver: an ultrastructural and biochemical study.

PCB 105 (2,3,3',4,4'-pentachlorobiphenyl) congener was fed to weanling Sprague-Dawley rats in a diet combined with 4% corn oil. The animals were distributed randomly into 10 groups, each of which contained 10 males and 10 females, and rats in 8 groups received diets containing PCB at concentrations of 0.05, 0.5, 5, and 50 ppm. Animals in the other 2 groups served as controls. After 13 weeks, the animals were humanely killed and liver samples were obtained and prepared for transmission electron microscopy. Ultrastructural alterations revealed in the hepatocytes of animals fed the PCB included smooth endoplasmic reticulum proliferation, atypical mitochondrial cristae, and augmentation of peroxisome numbers (in animals fed high PCB concentrations). Biochemical alterations were estimated by using hepatic microsomal pentoxyresorufin-O-dealkylase (PROD) and ethoxyresorufin-O-deethylase (EROD) activities. A dose-dependent increase in EROD and PROD activities was discovered; only in the animals of highest PCB dose group, however, was EROD found to be significant (p < .05). Based on our previous work, this congener is relatively less toxic than PCB 126, 118, and 153 and is similar in toxicity to 156.

Animals↗

PubMedDate not supplied

Chronic lead exposure effects in the cynomolgus monkey (Macaca fascicularis) testis.

Although reproductive consequences of high circulating blood lead levels (> or = 60 micrograms/dL) have been reported, potential adverse effects of chronic lead exposure in males that result in low to moderate blood lead levels (10-25 and 26-60 micrograms/dL, respectively) are unknown. Effects of chronic lead exposure to testis ultrastructure were determined in the cynomolgus monkey after oral administration of lead acetate (1500 micrograms/kg BW/day) in a vehicle in the following groups: from birth to 10 years (lifetime), postnatal day 300 to 10 years (postinfancy), and postnatal day 0-400 (infancy); monkeys in the control group received only the vehicle (95% glycerol and 5% distilled water). At age 10 years, circulating lead concentrations in lifetime and postinfancy-dosed monkeys were approximately 35 micrograms/dL, and in control and infancy animals the concentrations were < 1.0 microgram/dL. Sertoli and spermatogenic cells of dosed monkeys from the infancy and lifetime groups revealed injuries. Chronic exposure to lead that results in moderate blood lead concentrations induced persistent ultrastructural alterations in the cynomolgus monkey testis. Results of this study on the primate, following extrapolation to humans, could influence further refining of the impact of environmental lead contamination concentrations vis-à-vis the health of children, adults, and aged human beings.

Animals↗

PubMedDate not supplied

Iris neovascularization in children as a manifestation of underlying medulloepithelioma.

PURPOSE: To report the occurrence of unilateral iris neovascularization in children secondary to medulloepithelioma. METHODS: Presenting features and the clinical course of patients confirmed to have medulloepithelioma were reviewed. RESULTS: Seven patients with medulloepithelioma had iris neovascularization during the clinical course. Associated cataract and lens coloboma occurred in two and three cases, respectively. In six (86%) cases, no apparent cause for iris neovascularization could be detected at presentation. Two cases had tube shunts for management of neovascular glaucoma before medulloepithelioma was recognized. All cases eventually required enucleation. CONCLUSION: Presence of iris neovascularization is an early manifestation of medulloepithelioma. Children with iris neovascularization of unknown cause should be evaluated to exclude underlying medulloepithelioma.

Cataract↗

PubMedDate not supplied

Inhibitory potential of Chlorella vulgaris (E-25) on mouse skin papillomagenesis and xenobiotic detoxication system.

The present study assesses the modulatory potential of Chlorella vulgaris (E-25) on murine skin papillomagenesis, and the role of xenobiotic detoxication system in modulating the papillomagenesis pattern. Topical application of E-25 (500 mg/kg b.w./day) during peri-, post- or peri- and post-initiational stages of 7,12-dimethylbenz [a] anthracene (DMBA)-induced papillomagenesis, significantly modulated the a) tumor burden to 5.00, 4.33 and 3.94 (positive control value: 5.88 b) cumulative number of papillomas to 90, 78 and 67 (positive control value: 106); and c) percent incidence of mice bearing papillomas to 94, 90 and 89 respectively (positive control value: 100). E-25 treatment alone or during peri-, post- or peri- and post-initiational stages significantly elevated the sulfhydryl (-SH) and glutathlone S-transferase (GST) levels in the liver and skin tissues. However, the levels of microsomal cytochrome b5 (Cyt. b5) and cytochrome P-450 (Cyt. P-450) were not appreciably modulated by the topical treatment of E-25. The results suggest the chemopreventive potential of E-25 during peri-, post- or peri- and post-initiational stages of murine skin papillomagenesis. The possible significance of xenobiotic detoxication system in modulating the papillomagenesis pattern is discussed.

9,10-Dimethyl-1,2-benzanthracene↗

PubMedDate not supplied

Risk behaviour in an urban and a rural male adolescent population.

BACKGROUND: There is an increasing trend of risk behaviour in adolescents worldwide but very little literature is available in India on this important subject. We surveyed an urban male adolescent population and a comparable rural population to determine the difference in their risk behaviour. METHODS: A comparative cross-sectional study was conducted among 199 and 152 male adolescents from an urban village of south Delhi and a rural village in Uttar Pradesh. A pretested semi-structured interview schedule with 36 items was applied on all subjects by trained interviewers. RESULTS: Consuming alcohol, smoking, pre-marital sexual intercourse and consuming bhang (cannabis) were present in 32.2%, 25.1%, 12.5% and 11.5% of the urban village adolescents and in 1.3%, 48.7%, 11.2%, and 16.5% of those residing in the rural village, respectively. About 66.8% of urban and 51.3% of rural adolescents had indulged in physical fights and 12.5% of urban and 6.6% of rural adolescents were in possession of assault weapons such as iron rods, chains or knives sometime in the 30 days prior to the interview. CONCLUSION: The results of our study indicate that there is a high prevalence of risk behaviour in both urban and rural adolescents. However, except for smoking which was more common amongst rural adolescents all the other risk behaviours were more in those residing in urban areas. The reasons for this need to be ascertained, taking the geographical and socio-cultural factors into account, prior to considering the introduction of behaviour modification programmes.

Adolescent↗

PubMedDate not supplied

Expression of p53 and pRb in bladder and prostate cancers of patients having both cancers.

Evidence has been presented that tumor suppressor genes p53 and Rb play a crucial role in the development of both human prostate and bladder cancer. Patients with either cancer are at an increased risk for developing the other malignancy as compared to the general population. The purpose of the present study was to investigate whether there is abnormal expression of these two suppressor proteins in both the bladder and prostate cancers of the same patient. The expression of p53 and pRb in bladder and prostate cancer specimens obtained from 15 patients having both cancers was studied using immunohistochemical staining with antibodies against these proteins. The expression of p53 and pRb in both bladder and prostate cancers of the same patient was congruent in 8 of 15 cases (53%) for p53 and 9 of 15 cases (60%) for pRb. The significance of these findings warrants further investigations.

Aged↗

PubMedDate not supplied

Comparative evaluation of the effect of simulated porcelain firing cycle on the mechanical properties and microstructure of base metal ceramic alloys.

A comparison of mechanical properties and microstructure of four metal ceramic alloys in as-cast and heat-treated conditions resulted in significant differences. The alloys that were tested included two nickel-based and two cobalt-based metal ceramic alloys. Mechanical properties tested included strength, percent elongation and hardness. Ten tensile bars were cast for each alloy. Five of the ten bars for each alloy were randomly selected for heat treatment with the simulated porcelain firing cycle. Results indicated that the nickel-based alloys were weakened by the heat treatment and showed a decreased hardness and an increased elongation. The effects of heat treatment on the strength of cobalt-based alloys were variable, showing an increase in hardness and a decrease in elongation. Differences in mechanical properties exhibited by the alloys were related to compositional and microstructural changes.

Analysis of Variance↗

PubMedDate not supplied

Paraesophageal mediastinal drainage with diversion for delayed presentation of esophageal perforation.

Esophageal perforation is a serious condition; a delay of more than 48 hours in initiation of treatment leads to increased morbidity and mortality. Management of such patients is a surgical dilemma. We successfully managed 4 patients (2-iatrogenic, 1-tuberculous, 1-Boerhaave's syndrome) with delayed presentation of esophageal perforation by esophageal exclusion and paraesophageal mediastinal drainage, achieving good control of mediastinal sepsis, healing of perforation and at the same time avoiding thoracotomy and subsequent second surgery.

Adult↗

PubMedDate not supplied

Isolated splenic lymphoma: an elusive preoperative diagnosis.

Four patients underwent splenectomy for various clinical and radiological diagnoses and were found to have primary splenic lymphoma at surgery and histology. The diagnosis was classical Hodgkin's lymphoma, mixed cellularity type (one case); marginal zone B-cell non-Hodgkin's lymphoma (one case); and large B cell type non-Hodgkin's lymphoma (two cases). The first two patients had multiple nodules in the spleen measuring 0.1-0.5 cm while large cell lymphomas had large nodules (largest measuring 11 cm x 7 cm x 4 cm). The diagnoses were confirmed by immunohistochemical analysis. Mean follow up of these patients was 11 months; all patients received chemotherapy. One patient died, of causes not related to the disease process.

Adolescent↗