Search PubMed⌕ Search

Biomedical subjects

A Singh

Publications and source records attributed to A Singh.

At least 217 records · Page 12Linked to original sources
PubMed1999

Outcome of twin pregnancy in a renal transplant recipient treated with tacrolimus.

Our report describes the outcome of a twin pregnancy in a woman who was maintained on tacrolimus after a living related renal transplant. Both babies born at 32 weeks of gestation developed severe respiratory distress requiring ventilator assistance and went on to develop congestive heart failure. Echocardiograms on both babies showed dilated heart chambers. Twin A succumbed to complications, but twin B, who was treated more aggressively with vasopressors, recovered. Autopsy findings on twin A revealed a thrombotic cardiomyopathy with degeneration of cardiac muscle. We believe that the unusual outcome in this set of twins may have been a result of cardiomyopathy secondary to tacrolimus used by the mother during her pregnancy.

Azathioprine↗
PubMed1999

One-center experience with cyclosporine in refractory nephrotic syndrome in children.

Uncontrolled or refractory nephrotic syndrome (NS), seen in a variety of glomerular disorders, leads to end-stage renal disease (ESRD). This study describes the use and efficacy of cyclosporine (CSA) for the treatment of refractory NS in 83 children seen over a 10-year period. The histological diagnosis leading to the NS was focal segmental glomerulosclerosis (FSGS) in 51% (n = 42), IgM nephropathy in 20% (n = 17), membranoproliferative glomerulonephritis in 10% (n = 8), lupus nephritis in 6% (n = 5), human immunodeficiency virus (HIV) nephropathy in 5% (n = 4), minimal change disease in 7% (n = 6), and membranous nephropathy in 1% (n = 1) of patients. During CSA therapy the mean proteinuria of the study population decreased from 5.14 g/24 h (4.80 g/m2 per 24 h) to 1.23 g/24 h (0.92 g/m2 per 24 h) (P < 0.001), the mean serum albumin increased from 2.13 g/dl to 3.53 g/dl (P < 0.001), the mean serum cholesterol decreased from 364 mg/dl to 223 mg/dl (P < 0.001), and the mean serum creatinine increased from 0.77 mg/dl to 1.2 mg/dl (P < 0.01). When analyzed by histological diagnosis, similar significant trends of reduction in proteinuria were seen in all but the lupus group. There was a rise in serum creatinine following the use of CSA in patients with FSGS, lupus nephritis, and HIV nephropathy; however the elevated serum creatinine was only significant in patients with FSGS. At the end of the study period, 20 patients had reached ESRD, of which 11 had FSGS, 5 had lupus nephritis, and 4 were patients with HIV nephropathy. Fifty-four patients were in remission at the end of the study period (48 with proteinuria < 100 mg/24 h and 6 with proteinuria < 500 mg/24 h). In conclusion, among children with refractory NS, CSA induced a remission in a large proportion. However toxicity, as noted by the rise in serum creatinine, was observed in several patients. Since this toxicity may be drug induced or a natural progression of the disease, careful monitoring and close follow-up are essential.

Child↗
PubMed1999

Clinical presentation, diagnosis, and hospital outcome of patients with documented aortic dissection: the Albany Medical Center experience, 1986 to 1996.

BACKGROUND: In recent years, the diagnostic approach to patients with suspected aortic dissection has changed dramatically. Noninvasive studies such as transesophageal echocardiography (TEE), computed tomography, and magnetic resonance imaging have supplanted angiography as the initial tests of choice. The effect of this change in diagnostic approach has not previously been evaluated. METHODS AND RESULTS: The records of all patients discharged from Albany Medical Center Hospital between January 1, 1986, and December 31, 1996, were screened for an "aortic dissection" entry in the medical record database. For those records in which aortic dissection was confirmed, data concerning the diagnostic evaluation, treatment, and hospital course were recorded and analyzed. During the study period, there were 160 cases of documented aortic dissection discharged from the hospital. There were 100 type A and 60 type B dissections. The most commonly used diagnostic tests were TEE (83 of 160) and angiography (60 of 160). In patients who had TEE, diagnosis was made more quickly but overall mortality rate was not different from patients who had angiography. Renal dysfunction and neurologic events were less frequent in the TEE group. Hospital stay was significantly shorter in the TEE group (24.8 +/- 3.9 vs 14.0 +/- 1.8 days, P =.01). CONCLUSIONS: The use of TEE reduces morbidity rate and hospital stay in patients with aortic dissection but does not affect mortality rate.

Aged↗
PubMed1999

Postpartum cerebellar herniation in von Hippel-Lindau syndrome.

PURPOSE: To describe exacerbation during pregnancy of cerebellar hemangioblastoma in von Hippel-Lindau syndrome. METHOD: Case-report. A 21-year-old woman with von Hippel-Lindau syndrome was found on routine ocular examination to have severe papilledema 1 week after giving birth. RESULTS: Immediate magnetic resonance imaging disclosed a large cerebellar cyst from hemangioblastoma causing cerebellar tonsillar herniation. Immediate neurosurgical intervention was life saving. CONCLUSION: Worsening of intracranial hemangioblastoma during pregnancy in cases of von Hippel-Lindau syndrome should be realized and periodic neurologic and ophthalmologic observation is warranted.

Acute Disease↗
PubMed1999

Toxic effect of synthetic pyrethroid permethrin on the enzyme system of the freshwater fish Channa striatus.

Treatment with 40% and 80% of the LC50 (24h) of the pyrethroid permethrin after 24h exposure causes significant reduction in the activity of lactate dehydrogenase and cytochrome oxidase and enhanced the succinate dehydrogenase activity in the tissues of the freshwater fish Channa striatus. The results indicate that permethrin blocks aerobic as well as anaerobic metabolism in the exposed fishes.

Animals↗
PubMed1999

Tyrosine improves working memory in a multitasking environment.

Previous studies indicate that tyrosine may prove useful in promoting improved performance in situations in which performance is compromised by stress. To extend the generality of previous tyrosine findings, the present study examined the effects of tyrosine ingestion on performance during both a Multiple Task and a Simple Task battery. The multiple task battery was designed to measure working memory, arithmetic skills, and visual and auditory monitoring simultaneously, whereas the simple task battery measured only working memory and visual monitoring. Ten men and 10 women subjects underwent these batteries 1 h after ingesting 150 mg/kg of l-tyrosine or placebo. Administration of tyrosine significantly enhanced accuracy and decreased frequency of list retrieval on the working memory task during the multiple task battery compared with placebo. However, tyrosine induced no significant changes in performance on the arithmetic, visual, or auditory tasks during the Multiple Task, or modified any performance measures during the Simple Task battery. Blood levels of ACTH and cortisol were not, but heart rate and blood pressure were significantly increased during the performance tasks. The present results indicate that tyrosine may sustain working memory when competing requirements to perform other tasks simultaneously degrade performance, and that supplemental tyrosine may be appropriate for maintaining performance when mild to severe decrements are anticipated.

Adrenocorticotropic Hormone↗
PubMed1999

A macrophage fusion assay for rapid screening of cloned HIV-1 Env using dual recombinant vaccinia viruses expressing distinct RNA polymerases.

HIV-1 cell tropism is determined initially at the level of fusion mediated by the viral envelope glycoprotein (Env). Cell-cell fusion assays are employed widely to study Env-mediated fusion, and generally require transfection of target cells with a reporter plasmid that is activated upon fusion with Env-expressing effector cells. Macrophages are an important target for HIV-1, but fusion studies using primary macrophages are limited by their resistance to transfection. An assay described previously used recombinant vaccinia virus to express T7 polymerase in macrophages, and effector cells transfected with a T7-driven reporter plasmid and infected with recombinant vaccinia virus expressing Env. However, this requires a recombinant vaccinia virus for each Env. We developed a method to study fusion using primary macrophages and HIV-1 env plasmid clones under control of the T7 promoter. Macrophages were infected with a recombinant vaccinia virus expressing the SP6 RNA polymerase. Effector 293T cells were infected with a recombinant vaccinia virus expressing T7 polymerase, and co-transfected with T7-driven env plasmids and an SP6-driven reporter gene plasmid. Cell-cell fusion mediated by T7-driven Env results in SP6-driven reporter gene transactivation. This approach is suitable for rapid analysis of multiple primary isolate, chimeric, or mutant env genes cloned into plasmid vectors.

Cell Fusion↗
PubMed1999

Modulatory potential of clocimum oil on mouse skin papillomagenesis and the xenobiotic detoxication system.

The present study was designed to elucidate the mechanistic inhibitory efficacy of clocimum (an eugenol rich variety of Ocimum gratissimum; Labiatae) oil on murine skin papillomagensis. Topical application of clocimum oil (50 microl/animal/day) during peri-initiation stage (1 week before and 2 weeks after initiation) of 7,12-dimethylbenz[a]anthracene (DMBA)-induced papillomagenesis and/or during the tumour promotion stage reduced (P < 0.05) the (i) tumour burden to 5.00, 4.41 and 4.50 (positive control value 5.27); (ii) cumulative number of papillomas to 85, 75 and 72 (positive control value : 95); and (iii) percent incidence of mice bearing papillomas to 94, 89 and 88, respectively (positive control value 94). Significant (P < 0.01) elevation in the hepatic levels of glutathione S-transferase (GST), sulfhydryl (-SH) and cytochrome b5 (Cyt. b5) was observed by the respective topical treatment of clocimum oil. Even in the skin tissue of the mouse, the topical treatment of clocimum oil enhanced (P < 0.05) the -SH content. The results suggest the modest chemopreventive potential of clocimum oil against the murine skin papillomagenesis, and such effects may be partly due to the modulated xenobiotic detoxication system enzymes.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1999

Wide spectrum antibacterial and antifungal activities in the seeds of some coprophilous plants of north Indian plains.

In a survey at Lucknow, India, the seedlings of plant species which are prescribed in the Indian traditional system of medicine for a variety of infectious diseases were found to predominate on fresh or decomposing cattle dung, a harsh medium for plant growth due to high microbial load and other abiotic factors. Plants of most of the common species did not occur on the cattle dung heaps. It was hypothesized that plant species which are able to grow on cattle dung may have antimicrobial compounds in their seeds to protect them from microbial attack. In confirmation, the seeds of 15 of the coprophilous (kopros--dung, philein--to love) plant species, identified as occurring most frequently on fresh/decomposing cattle dung were directly tested against eight bacterial and three fungal strains. Interestingly, seeds of all the examined species exhibited antimicrobial activity. The seeds of the species found more frequently on the cattle dung heaps possessed higher levels of antimicrobial activities.

Animals↗
PubMed1999

Mechanism of biochemical action of substituted 4-methylbenzopyran-2-ones. Part 4: hyperbolic activation of rat liver microsomal NADPH-cytochrome C reductase by the novel acetylator 7,8-diacetoxy-4-methylcoumarin.

The effect of 7,8-diacetoxy-4-methylcoumarin (DAMC) has been studied on hepatic NADPH cytochrome C reductase-- an enzyme participating in the microsomal electron transport. The preincubation of liver microsomes with DAMC resulted in a time-dependent activation of NADPH cytochrome C reductase. The catalytic activity of the enzyme enhanced nearly 600% by 25 microM concentration of DAMC after 10 min of preincubation. The action of DAMC on the reductase resulted in enhanced v(max) while Km remained constant. A plot of 1/v(max) as a function of DAMC concentration resulted in a non-linear, but rectangular hyperbola indicative of hyperbolic activation. DAMC was also proved to be effective in significantly enhancing the activity of NADPH cytochrome C reductase in vivo. 7,8-Dihydroxy-4-methylcoumarin (DHMC), the deacetylated product of DAMC failed to irreversibly activate the enzyme. The activation effect of DAMC upon the enzyme was abolished by p-hydroxymercury benzoate. The role of a transacetylase in transferring the acetyl group of DAMC to the amino acid(s) of the active site of NADPH cytochrome C reductase causing irreversible enzyme activation is enunciated.

Acetylation↗
PubMed1999

Biotransformation of lantadene A (22 beta-angeloyloxy-3-oxoolean-12-en-28-oic acid), the pentacyclic triterpenoid, by Alcaligenes faecalis.

A bacterial strain capable of biotransformation of lantadene A (22 beta-angeloyloxy-3-oxo-olean-12-en-28-oic acid), the pentacyclic hepatotoxin of lantana (Lantana camara var. aculeata) has been isolated from soil using lantadene A as the sole carbon source. The organism is Gram negative, rod shaped, motile, catalase positive and has been identified as Alcaligenes faecalis. The isolate has been found to be specific for lantadene A and did not utilize lantadene B. In studies using sucrose as an additional carbon source, A. faecalis elicited biotransformation of lantadene A to its trans isomer 22 beta-tigloyloxy-3-oxoolean-12-en-28-oic acid, designated as lantadene X and two other minor metabolites which could not be isolated in pure state.

Alcaligenes↗
PubMed1999

Effect of lithium augmentation on the trace elemental profile in diabetic rats.

Energy dispersive X-ray fluorescence technique was employed to study the interactions among various elements, viz.: K, Zn, Br, Fe, Cu, Br & Rb in 4 groups of rats viz. control-GI, diabetic-GII (diabetes induced by i.p. administration of alloxan monohydrate at a dose level of 150 mg/kg b.w; single injection), lithium treated-GIII (lithium administered as Li2 Co3 at a dose level of 1.1 g of Li2 Co3/kg animal diet; free access; serum lithium levels--0.5-1.2 mEq/L) and lithium + diabetic rats-GIV. The different treatments continued for a total duration of 1 month. The K contents were found to be significantly lowered in all the treatment groups which was maximum (28%) in lithium treated diabetic rats. Depression in the levels of Rb was noticed in lithium treated and lithium treated diabetic (G-III and G-IV) groups. However, the levels (Rb) remained unaltered in diabetic (G-II) group. Interestingly, a significant decline was observed in Fe levels in G-III following lithium administration but the levels remained unchanged in G-IV with lithium administration to diabetic rats. On the other hand, lithium treatment to normal (G-III) and diabetic (G-IV) rats indicated statistically significant elevation in the levels of Cu and Br. However, diabetic (G-II) rats did not indicate any elevation in the levels of these two elements. Interestingly, the concentrations of Zn were found to be significantly elevated in all the treatment groups, which was maximum (37%) in G-III (lithium) group. A comparison of various elements from lithium treated diabetic group G-IV with the corresponding elements from the diabetic group G-II, implied a significant depression in K and Rb levels and a significant elevation in the levels of Br.

Animals↗
PubMed1999

High concentrations of tricyclic antidepressants increase intracellular Ca2+ in cultured neural cells.

We examined the effect of tricyclic antidepressants on intracellular Ca2+ signalling in cultured cells of neuronal and glial origin. High concentrations of amitriptyline and desipramine increased the intracellular Ca2+ in PC-12 and U-87 MG cells. In PC-12 cells amitriptyline induced a biphasic rise in intracellular Ca2+. A rapid and transient increase due to release of Ca2+ from intracellular pools was followed by sustained elevation of [Ca2+]i due to influx from the extracellular medium. Desipramine evoked the Ca2+ release from intracellular pools but the influx of Ca2+ was not elicited. In U-87 MG cells both the drugs induced Ca2+ release from intracellular pools, however amitriptyline also induced a transient influx of Ca2+. To delineate the mechanisms involved in mobilization of Ca2+ by the drugs pharmacological agents that inhibit IP3 formation in cells and Ca2+ channel blockers were used and changes in [Ca2+]i and membrane potential were monitored. The results show that both the drugs release Ca2+ from IP3 sensitive pools by activation of phospholipase C and amitriptyline in addition activates a non specific cation channel in the plasma membrane of cells. Paradoxically at relatively lower concentrations (< 50 microM) amitriptyline and desipramine inhibited the Ca2+ signal induced by adenosine triphosphate in both the cell types. Our data demonstrate that tricyclic antidepressants at different doses may have inhibitory or stimulatory effects on cellular Ca2+ signalling.

Amitriptyline↗
PubMed1999

Periarteritis nodosa presenting as a breast lesion: report of a case and review of the literature.

We describe a 34-year-old woman with periarteritis nodosa (PAN) presenting as a breast lesion. Localized involvement of the breast is an unusual manifestation of PAN. To date, 10 cases have been reported: all were in women with an age range of 45-78 years (mean 63). In most cases, breast lesions were an isolated finding, and the prognosis was favourable, setting them apart from the more common form of systemic PAN. The case presented is unusual in that vasculitis developed in the postpartum period, and was associated with cutaneous PAN-like lesions elsewhere on the body, and digital artery occlusion. The most important differential diagnoses of PAN of the breast are infectious mastitis, mammary malignancy and other forms of idiopathic vasculitides of the breast, e.g. giant cell arteritis and Wegener granulomatosis.

Adult↗
PubMed1999

Degradation of Japanese encephalitis virus by neutrophils.

The ability of neutrophils to degrade the phagocytosed Japanese encephalitis (JE) virion, via triggering of the respiratory burst and generation of toxic radicals has been investigated. JEV or JEV-induced macrophage derived factor (MDF) induces increase in intracellular oxidative signals with generation of superoxide anion (O2-), via activation of cytosolic NADPH and subsequent formation of hydrogen peroxide, with maximum activity on day 7 post infection. The response was sensitive to anti-MDF antibody treatment. Further, the study revealed rapid degradation of phagocytosed JE viral protein and nucleic acid. The viral protein degradation was partially dependent on the generation of toxic oxygen species as it could be abrogated by pretreatment of the cells with staurosporine.

Animals↗