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S Jain

Publications and source records attributed to S Jain.

At least 199 records · Page 11Linked to original sources
PubMed2000

Kinetic model of ATP synthase: pH dependence of the rate of ATP synthesis.

Recently, a novel molecular mechanism of torque generation in the F(0) portion of ATP synthase was proposed [Rohatgi, Saha and Nath (1998) Curr. Sci. 75, 716-718]. In this mechanism, rotation of the c-subunit was conceived to take place in 12 discrete steps of 30 degrees each due to the binding and unbinding of protons to/from the leading and trailing Asp-61 residues of the c-subunit, respectively. Based on this molecular mechanism, a kinetic scheme has been developed in this work. The scheme considers proton transport driven by a concentration gradient of protons across the proton half-channels, and the rotation of the c-subunit by changes in the electrical potential only. This kinetic scheme has been analyzed mathematically and an expression has been obtained to explain the pH dependence of the rate of ATP synthesis by ATP synthase under steady state operating conditions. For a single set of three enzymological kinetic parameters, this expression predicts the rates of ATP synthesis which agree well with the experimental data over a wide range of pH(in) and pH(out). A logical consequence of our analysis is that DeltapH and Deltapsi are kinetically inequivalent driving forces for ATP synthesis.

Adenosine Triphosphate↗
PubMed2000

Kinetic modeling of ATP synthesis by ATP synthase and its mechanistic implications.

Based on the torsional mechanism of ATP synthesis by ATP synthase, a kinetic scheme has been developed in this work. The scheme considers adenine nucleotide transport, binding of substrates ADP and P(i), unbinding of product ATP, and ATP synthesis. This kinetic scheme has been analyzed mathematically, and a kinetic model has been obtained to explain the experimentally observed hyperbolic Michaellian dependence of the rate of ATP synthesis on the ADP concentration by ATP synthase under physiological steady-state operating conditions. The principal results of the kinetic model have been compared with the experimental data and an estimate of the enzymological kinetic parameters V(max), K(M), and K(I) has been determined. Mechanistic implications arising from further analysis of the kinetic model have been discussed. These biological implications provide deep insight into the sequence of events leading to ATP synthesis.

Adenosine Diphosphate↗
PubMed2000

Association analysis of 5HT transporter gene in bipolar disorder in the Indian population.

A variable number tandem repeat (VNTR) polymorphism consisting of multiple copies of a 17-bp repeat in the second intron of the serotonin transporter gene (SERT) has been reported. Different alleles of this VNTR have been found to be associated with bipolar disorder and schizophrenia. These findings have been confirmed in some populations, but disconfirmed in others. Furthermore, significant ethnic variations in the distribution of these alleles both in normal and patient populations also have been reported. We analyzed the VNTR polymorphism in 50 Indian patients with bipolar disorder and in ethnically matched controls. Two alleles corresponding to 10 and 12 repeats of the VNTR were found in both groups. There were no significant differences either in allele frequency or genotype frequency between the two groups. The nine-repeat allele that has been reported in Japanese and Caucasian populations was absent in our sample. Although it will be important to extend the present study in a larger sample, our initial results do not suggest any large association with alleles of the VNTR in the SERT gene and bipolar disorder in Indian patients. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 96:170-172, 2000.

Alleles↗
PubMed2000

NADPH dependent superoxide generation in the ovary and uterus of mice during estrous cycle and early pregnancy.

NADPH dependent O2- production in the ovary and uterus of cycling and pregnant mice was estimated employing a novel technique of time-lapse electron spin resonance enhancement of a superoxide-trapping spin trap. The NADPH dependent O2- generation in the mouse ovary increased during the early pre-ovulatory phase in cycling females and during extended luteal phase in pregnant animals. A peak of uterine NADPH dependent O2- production at proestrous in the cycling animals at pre-implantation phase in pregnant animals suggested a contribution of this enzyme towards generating high levels of superoxide anion radical during the respective stages. Both ovarian and uterine NADPH dependent O2- production appeared to be LH-inducible.

Animals↗
PubMed2000

Pedicled omental transfer for limb salvage in Buerger's disease.

We performed pedicled omental transfer in 62 patients with Buerger's disease at the Department of Surgery, J.L.N. Hospital, Ajmer between January 1990 and December 1996. All were male and had evidence of limb ischaemia. Post-operative results in these patients consisted of relief of intermittent claudication in 92%, disappearance of rest pain in 94%, disappearance of limb coldness in 83%, disappearance of discolouration in 82%, and healing of ischaemic ulcers in 83%. Tissue oxygen saturation in the affected limb improved from a mean of 84.8+/-3.6% in the preoperative period, to 89+/-1.5% at 12 h, 93.1+/-1.8% at 72 h and 96+/-1.2% at the end of 2 months of follow-up. Claudication distance improved from a mean of 75+/-20 m in the pre-operative period to 1000+/-110 m at 2 months of follow-up in 57 of 62 patients. Major amputations were not required in any patient, thus conserving the limb. We conclude that pedicled omental transfer offers promising results in patients with limb ischaemia due to Buerger's disease.

Adult↗
PubMed2000

A new surgical technique of microkeratome-assisted deep lamellar keratoplasty with a hinged flap.

We describe a new surgical technique of microkeratome-assisted deep lamellar keratoplasty for treating patients with corneal stromal disease and normal endothelium. A microkeratome is used to create a hinged anterior stromal flap in the host cornea, and the diseased stroma is resected or ablated. A complementary donor stromal button, prepared using a microkeratome and an artificial anterior chamber, is transplanted prior to repositioning of the flap. The flap may be lifted at a later date, and an excimer laser used to correct residual refractive errors. Notwithstanding the preliminary and theoretical nature of this report, this technique may improve the outcomes of deep lamellar keratoplasty and may allow for decreased postoperative complications. Arch Ophthalmol. 2000;118:1112-1115

Corneal Diseases↗
PubMed2000

Aspiration cytology of mesoblastic nephroma in an adult: diagnostic dilemma.

A case of adult mesoblastic nephroma (MN) was erroneously interpreted as a benign mesenchymal tumor on fine-needle aspiration (FNA) cytology. MN is a rare tumor in infants and is extremely uncommon in adults. A 50-yr-old female presented with a renal lump with the clinicoradiological possibility of renal-cell carcinoma. Giemsa-stained smears were highly cellular and showed cohesive interlacing fragments of spindle cells embedded in abundant pink fibrillary stromal matrix. Epithelial component was seen in the form of tubules. Pleomorphism, mitosis, and necrosis were absent. Cytologic features in both adult and infantile MN are similar, but in an adult can be mistaken for benign or malignant mesenchymal tumor and the sarcomatoid variant of renal-cell carcinoma. FNA in such a rare yet cytomorphologically characteristic lesion can be helpful in guiding the management. Awareness on the part of both the clinician and the cytopathologist is necessary to resolve the diagnostic dilemma.

Biopsy, Needle↗
PubMed2000

Disseminated histoplasmosis with reactive hemophagocytosis: aspiration cytology findings in two cases.

Two cases of disseminated histoplasmosis associated with reactive hemophagocytic syndrome are described. The clinical presentation was with prolonged unexplained fever and hepatosplenomegaly. On a strong clinical possibility of tuberculosis, antitubercular treatment was initiated in both patients. Lymph node (case 1), splenic (case 2), and bone marrow aspiration, however, showed sheets of proliferating histiocytes, and intracellular and extracellular histoplasma organisms. Aspiration cytology was thus valuable in establishing the final diagnosis. The patients had a fulminant clinical course and died of hemorrhagic shock within 48 hr of hospital admission before specific therapy could be initiated. Histoplasmosis can mimic tuberculosis clinically. There is a need for an increased awareness of the clinicopathological spectrum of histoplasmosis, especially its rarer manifestations as hemophagocytic syndrome. In suspected cases, aspirations from the lymph node, liver, and spleen can be performed safely and should be utilized for early diagnosis.

Adult↗
PubMed2000

Anemia in children: early iron supplementation.

Iron deficiency anemia is the most wide spread micronutrient deficiency disorder in the world, being most prevalent in women and young children. The present study was conducted to find out the prevalence of anemia in children and its contributory factors with reference to early iron supplementation. It was a cross sectional study done on 137 children of age 1-2 years in urban slums of Meerut. Prevalence of anemia in the study group was 59.9%. The socio-economic status, mother's educational status, birth weight, sibling order, and type of weaning food did not show any significant relationship with the prevalence of anemia in these children, whereas, weaning time, nutritional status and early iron supplementation had a positive impact on it. Exclusive breast feeding upto 4 months followed by weaning, adequate nutritional status and early iron supplementation have a definite role in prevention of anemia in children.

Age Factors↗
PubMed2000

Randomized controlled trial and economic evaluation.

Conducting economic evaluation alongside clinical trials is an efficient way of getting valid and reliable information with minimum assumptions made during data collection. However, design of a randomised control trial (RCT) takes away several of the real world situations, the variations in resource utilisation, their cost due to close supervision and monitoring of the study subjects. Suitable sensitivity analysis has to be done to make the economic data obtained more pragmatic and hence utilised by the policy makers.

Cost-Benefit Analysis↗
PubMed2000

Sub-clinical acute rejection detected using protocol biopsies in patients with delayed graft function.

Acute rejection in renal transplants is difficult to diagnose when patients have delayed graft function (DGF) in the early post-transplant period. In this study protocol, renal transplant biopsies were performed in an attempt to detect sub-clinical acute rejection episodes. Eighty-three patients were eligible for the study, of whom 33 had DGE All had protocol renal transplant biopsies performed under ultrasound control at 7 days post-transplant, and those with DGF had further biopsies weekly until the graft functioned. All histologically confirmed acute rejection episodes were treated. Sub-clinical acute rejection was detected in 6/33 (18%) patients with DGF compared to 2/50 (4%) in the other patients (P < 0.05). Borderline rejection was present in 4/33 (12%) and 4/50 (8%) patients, respectively. Because of the high detection rate of sub-clinical acute rejection and the low morbidity of renal transplant biopsies, their use is recommended in patients with DGF.

Acute Disease↗
PubMed2000

Targeted disruption of sti35, a stress-responsive gene in phytopathogenic fungus Fusarium oxysporum.

sti35 is one of the heat-shock genes in Fusarium oxysporum, which is a fungal pathogen for wilt disease in plants. We have isolated a genomic clone of sti35 and used it to create disruption mutations. Disruption of the sti35 coding region resulted in the loss of a 32-kDa protein present in heat-shocked cells. The disruption had no detectable effect on growth and development at various temperatures, nor on the ability to acquire thermotolerance in nutrient medium. But the sti35 disruptants showed increased thermotolerance, relative to the wild-type strain, when incubated in minimal medium after heat treatment.

Carbohydrates↗
PubMed2000

Molecular analysis of autosomal dominant hereditary ataxias in the Indian population: high frequency of SCA2 and evidence for a common founder mutation.

Expansion of CTG/CAG trinucleotide repeats has been shown to cause a number of autosomal dominant cerebellar ataxias (ADCA) such as SCA1, SCA2, SCA3/ MJD, SCA6, SCA7, SCA8 and DRPLA. There is a wide variation in the clinical phenotype and prevalence of these ataxias in different populations. An analysis of ataxias in 42 Indian families indicates that SCA2 is the most frequent amongst all the ADCAs we have studied. In the SCA2 families, together with an intergenerational increase in repeat size, a horizontal increase with the birth order of the offspring was also observed, indicating an important role for parental age in repeat instability. This was strengthened by the detection of a pair of dizygotic twins with expanded alleles showing the same repeat number. Haplotype analysis indicates the presence of a common founder chromosome for the expanded allele in the Indian population. Polymorphism of CAG repeats in 135 normal individuals at the SCA loci studied showed similarity to the Caucasian population but was significantly different from the Japanese population.

Female↗
PubMed2000

Neurological evaluation and intelligence testing in the child with operated congenital heart disease.

BACKGROUND: The immediate and intermediate-term neurodevelopmental outcome in infants undergoing open heart procedures using deep hypothermic cardiopulmonary bypass was assessed prospectively. METHODS: One hundred consecutive infants (age 2 to 174 days) were operated on using either deep hypothermic bypass only (group A, n = 28), or with associated circulatory arrest (group B, n = 72). Early neurological outcome was recorded. Survivors underwent mental development evaluation after 31 to 55 months. Fifty other children of similar demographic profile but without heart disease were also tested as controls. RESULTS: In group A, there were two neurological deaths. In group B, 5 patients had clinical seizures, 1 had monoparesis and 1 had hyperkinetic syndrome with decreased attention span. Mean mental performance quotient was 90.0+/-8.2 in group A, and 89.1+/-6.8 in group B, (group A vs. B, p = 0.60). Mean mental performance quotient in the control group was 101.4+/-8.4, which was significantly higher than the patient population (p << 0.001). No correlation was found between duration of circulatory arrest and postoperative mental performance quotient. CONCLUSIONS: There was significant retardation of mental development in infants operated with deep hypothermic cardiopulmonary bypass. However, use of total circulatory arrest and its duration did not affect clinical outcome up to preschool age.

Brain Damage, Chronic↗