Biomedical subjects

B Singh

Publications and source records attributed to B Singh.

At least 235 records · Page 13Linked to original sources

PubMed1999

Evidence of an interaction between Mos and Hsp70: a role of the Mos residue serine 3 in mediating Hsp70 association.

c-Mos is a germ cell-specific MAP kinase kinase kinase (MAPKKK) that plays an essential role during meiotic divisions of oocytes. c-Mos is a key component of an activity, cytostatic factor, required for metaphase II arrest of unfertilized eggs in vertebrates. To understand the regulation of c-Mos, we are investigating c-Mos-interacting proteins. We provide evidence that mouse c-Mos binds to Hsp70, a molecular chaperone. Hsp70 was found to associate with Mos ectopically expressed in COS-1 cells. Mos-Hsp70 complexes could be immunoprecipitated with both Mos and Hsp70 antibodies. Despite a low-abundance of Mos, the Hsp70 antibody immunoprecipitated Mos as the major protein. Of importance, the Mos protein present in anti-Hsp70 immunoprecipitates functioned as an active MAPKKK indicating that it is not grossly misfolded. It is known that c-Mos protein kinase activity in cell extracts of transfected COS-1 or NIH3T3 cells is labile. We found that the inclusion of adenosine triphosphate (ATP) in cell extracts protected against the loss of Mos kinase activity. In the absence of ATP from cell extracts, protein kinase activity of Mos was lost within 6 h on ice even though the Mos protein was not degraded and remained bound to Hsp70. Based on our identification of c-Mos-Hsp70 interaction, one of the roles of ATP may be to assist the regulation of c-Mos via ATP involvement in the protein-folding function of Hsp70 and possibly other molecular chaperones. We also detected by coimmunoprecipitation a physical association between endogenous c-Mos and Hsp70 in Xenopus eggs. To provide further evidence for the functional significance of Hsp70 interaction to Mos function, we show that the residue serine 3 in Mos, which is important for the regulation of protein kinase activity of Mos is also important for Hsp70 association.

Animals↗

PubMed1999

Activity and stability of recombinant bifunctional rearranged and monofunctional domains of ATP-sulfurylase and adenosine 5'-phosphosulfate kinase.

Murine adenosine 3'-phosphate 5'-phosphosulfate (PAPS) synthetase consists of a COOH-terminal ATP-sulfurylase domain covalently linked through a nonhomologous intervening sequence to an NH2-terminal adenosine 5'-phosphosulfate (APS) kinase domain forming a bifunctional fused protein. Possible advantages of bifunctionality were probed by separating the domains on the cDNA level and expressing them as monofunctional proteins. Expressed protein generated from the ATP-sulfurylase domain alone was fully active in both the forward and reverse sulfurylase assays. APS kinase-only recombinants exhibited no kinase activity. However, extension of the kinase domain at the COOH terminus by inclusion of the 36 residue linker region restored kinase activity. An equimolar mixture of the two monofunctional enzymes catalyzed the overall reaction (synthesis of PAPS from ATP + SO42-) comparably to the fused bifunctional enzyme. The importance of the domain order and organization was demonstrated by generation of a series of rearranged recombinants in which the order of the two active domains was reversed or altered relative to the linker region. The critical role of the linker region was established by generation of recombinants that had the linker deleted or rearranged relative to the two active domains. The intrinsic stability of the various recombinants was also investigated by measuring enzyme deactivation as a function of time of incubation at 25 or 37 degrees C. The expressed monofunctional ATP-sulfurylase, which was initially fully active, was unstable compared with the fused bifunctional wild type enzyme, decaying with a t1/2 of 10 min at 37 degrees C. Progressive extension by addition of kinase sequence at the NH2-terminal side of the sulfurylase recombinant eventually stabilized sulfurylase activity. Sulfurylase activity was significantly destabilized in a time-dependent manner in the rearranged proteins as well. In contrast, no significant deactivation of any truncated kinase-containing recombinants or misordered kinase recombinants was observed at either temperature. It would therefore appear that fusion of the two enzymes enhances the intrinsic stability of the sulfurylase only.

Amino Acid Sequence↗

PubMed1999

Bacterial superantigens induce down-modulation of CC chemokine responsiveness in human monocytes via an alternative chemokine ligand-independent mechanism.

Staphylococcal superantigens (SAgs) are very potent T cell mitogens, but they can also activate monocytes by binding directly to MHC class II molecules in a manner independent of TCR coengagement. Induction of proinflammatory cytokines and chemokine expression in monocytes by superantigens has recently been reported. Here we report that superantigen stimulation of human peripheral blood monocytes results in a rapid, dose-dependent, and specific down-regulation of chemokine (macrophage inflammatory protein-1alpha (MIP-1alpha), monocyte chemotactic protein-1 and MIP-1beta) binding sites (e.g., CCR1, CCR2, and CCR5), which correlates with a concomitant hyporesponsiveness of human monocytes to these CC chemokine ligands. This down-regulation occurs 15-30 min following superantigen stimulation and is specific to chemokine receptors, in that binding and responsiveness of monocytes to the chemoattractant formyl-tripeptide FMLP are not affected. We further demonstrate that SAg-induced down-modulation of chemokine binding and monocyte hyporesponsiveness to the chemokines MIP-1alpha, monocyte chemotactic protein-1, and MIP-1beta is mediated through cellular protein tyrosine kinases, and the down-modulation can be mimicked by an MHC class II-specific mAb. Additionally, our observations indicate that SAg-induced loss of chemokine binding and monocyte responsiveness is probably mediated by secreted serine proteinases. Bacterial SAg-induced down-modulation of chemokine responsiveness represents a previously unrecognized strategy by some bacteria to subvert immune responses by affecting the intricate balance between chemokine and chemokine receptor expression and function.

Antigens, Bacterial↗

PubMed1999

Hippocampal volume in first-episode psychoses and chronic schizophrenia: a high-resolution magnetic resonance imaging study.

BACKGROUND: It has been proposed that the hippocampus is a potential site for a neurodevelopmental lesion in schizophrenia. While smaller hippocampal volumes have been described in chronic schizophrenia, there have been few magnetic resonance imaging studies in first-episode psychosis. Furthermore, no studies have examined the specificity of this finding to first-episode schizophrenia, compared with first-episode affective psychosis. METHODS: Hippocampal and whole-brain volumes were estimated using high-resolution magnetic resonance imaging in 140 controls, 46 patients with chronic schizophrenia, and 32 patients with first-episode psychosis. RESULTS: Patients with chronic schizophrenia and first-episode psychosis had significantly smaller hippocampal volumes as compared with controls. Within the first-episode group, both patients with schizophrenia/schizophreniform psychosis and those with affective psychosis had smaller left hippocampal volumes as compared with controls. Smaller right hippocampal volumes were associated with age and illness duration in patients with chronic schizophrenia. Hippocampal volumes were not correlated with age of illness onset or medication dosage in either patient group. CONCLUSIONS: These data show that smaller hippocampal volumes are present from the onset of illness. While these findings would support the neurodevelopmental model of schizophrenia, the finding of smaller left hippocampal volume in patients with first-episode schizophrenia and affective psychosis does not support the prediction that smaller hippocampi are specific to schizophrenia. The association of smaller right hippocampal volumes with increased illness duration in chronic schizophrenia suggests either that there is further neurodegeneration after illness onset or that bilateral small hippocampi predict chronicity.

Adult↗

PubMed1999

Primary stenting in acute myocardial infarction: a 30-day follow up study.

Primary coronary stenting is being increasingly used in patients undergoing primary coronary angioplasty for acute myocardial infarction. In this prospective study we evaluated our experience of direct angioplasty in 68 patients with acute myocardial infarction of whom 57 received intracoronary stents using high-pressure deployment (> or =12 atmospheres) with adjunct aspirin and ticlopidine therapy without coumadin. All patients underwent pre-discharge follow-up angiography. Stent implantation was successful in all patients. Stent thrombosis was not seen in any patient. However, TIMI grade 3 flow was obtained in only 51 patients (89.6%) with evidence of slow flow present in remaining six patients. Follow-up angiograms showed no stent thrombosis but five out of the six patients (83%) with slow-flow phenomenon persisted to have slow flow. These patients had lower left ventricular ejection fraction as compared to patients with TIMI 3 flow at follow-up angiography (27.5 +/- 10.2% vs. 42.1 +/- 15.2%, P < .001) and a high mortality (two out of six) within 30 days. Primary stenting is safe and feasible in the majority of patients with good short-term outcomes, but persistent slow-flow phenomenon with adverse clinical outcome is seen in a small but significant number of patients.

Aged↗

PubMed1999

Percutaneous transluminal myocardial revascularization with a holmium laser system: procedural results and early clinical outcome.

Surgical transmyocardial laser revascularization has been reported to improve clinical outcome in patients with refractory angina who are not candidates for angioplasty or bypass surgery. We investigated the feasibility and safety of a nonsurgical, percutaneous technique for laser channel creation using energy from a holmium:yttrium-aluminium-garnet (YAG) laser. The laser energy was directed through a fiber enclosed in a catheter to the ventricular myocardium creating channels between the blood pool and the myocardium. Thirty-five patients with angina and coronary anatomy not amenable to revascularization with coronary angioplasty or bypass surgery underwent percutaneous transluminal myocardial revascularization. A total of 15 +/- 5 channels were formed per patient. There was no procedure-related mortality. One patient developed cardiac tamponade requiring thoracotomy and another a minor self-limiting pericardial effusion. There was no worsening of regional wall motion function in any patient. All patients were discharged alive after a postprocedure hospital stay of 2.1 +/- 1.4 days. Mean Canadian Cardiovascular Society (CCS) functional class declined from 3.68 +/- 0.4 before procedure to 0.82 +/- 0.7 at 30 days (P < 0.01). At 3 months, mean angina class was 0.94 +/- 0.65 (n = 35; P < 0.01) and at 6 months, mean angina class was 1.08 +/- 0.58 (n = 26; P < 0.01). One patient required repeat revascularization after 5 months for progression of disease in a degenerated saphenous venous graft supplying different region of myocardium. We conclude that transmyocardial revascularization using holmium:YAG laser by percutaneous technique can be carried out safely with encouraging early results and a very low complication rate. The symptomatic relief seen up to 6 months has been excellent. The long-term effects of this technique on mortality and relief of angina, however, remain to be defined. Cathet. Cardiovasc. Intervent. 47:287-291, 1999.

Angina Pectoris↗

PubMed1999

Leukocytes utilize both alpha4 and alpha5 integrins for intraislet infiltration in non-obese diabetic mice.

The loss of insulin-producing cells during the development of type 1 diabetes is dependent on leukocyte infiltration of beta-islets in the pancreas. Injection of antibodies to integrins and their ligands has been shown to prevent the development of diabetes in non-obese diabetic (NOD) mice. However, little is known about the progression of infiltration by leukocytes after their homing and extravasation into the pancreas. In the present study, the effect of monoclonal antibodies (mAbs) to alpha4 and alpha5 integrins on leukocytes that had infiltrated the islets was characterized in NOD mice at 10 weeks of age when insulitis was in progress, or in mice with recent onset of diabetes. Injection of mAbs to either alpha4 or alpha5 integrins had little effect on the extent of leukocyte infiltration in 10-week-old or diabetic mice. In contrast, leukocyte infiltration was significantly reduced upon injection of mAbs to both alpha4 and alpha5 integrins. The reduction in leukocyte infiltration was due to decreases in the percentage of islets with intraislet infiltration. However, the observed effect of mAbs to alpha4 and alpha5 integrins was reversible, since intraislet infiltration resumed upon termination of antibody treatment. Results suggest that after homing to the pancreas, leukocytes utilize both alpha4 and alpha5 integrins for intraislet infiltration.

Animals↗

PubMed1999

Tolerance induction by acylated peptides: effect on encephalitogenic T cell lines.

We reported previously that acylation of an encephalitogenic peptide of myelin basic protein (MBP68-86) by attachment of palmitoyl chloride (PAL68-86) converted this peptide into a powerful tolerogen for EAE in the Lewis rat. In this study we show that T cell lines derived from a PAL68-86-protected rat proliferated poorly to MBP68-86 in vitro, even after repeated passages in this peptide and IL-2. Conversely, T cell lines derived from untreated rats that were challenged with MBP68-86 or PAL68-86 in CFA responded vigorously to MBP68-86 when propagated for many passages in this peptide but became gradually unresponsive after being propagated in the presence of PAL68-86. The modulation of the T cell lines by PAL68-86 in vitro was reflected by a significant reduction in their ability to transfer EAE to recipients. A high percentage of cells stained with an anti-Vbeta8.2 antibody, regardless of whether they were propagated in the presence of unmodified or acylated peptide. The results are consistent with the notion that tolerance induced by PAL68-86 operates by functional inactivation and provide the basis for the use of acylated peptides in the antigen-specific treatment of autoimmune diseases.

Acylation↗

PubMed1999

Congenital absence of the gall bladder.

Congenital absence of the gall bladder is an extremely rare embryological aberration with a reported incidence ranging between 0.013 and 0.075%. This report, the first from South Africa, discusses 2 cases of gall bladder agenesis, bringing to 413 the number of cases reported in the literature. In confirming the diagnosis of an agenesis of the gall bladder, it is necessary to exclude the abnormal locations which are intrahepatic, retrohepatic, on the left side, or within the lesser omentum or falciform ligament and retroperitoneal. Patients with gall bladder agenesis are classified into 3 categories: i) Multiple foetal anomaly (12.9%), ii) Asymptomatic (31.6%) and iii) Symptomatic (55.6%). Notwithstanding current diagnostic modalities, this rare condition may still present a dilemma to the abdominal surgeon. Agenesis of the gall bladder is a well-recognised but uncommon congenital abnormality. With the advent of minimal access surgery laparotomy may be avoided as the condition, when suspected, may be confirmed by ERCP and CT scan.

Adult↗

PubMed1999

Left renal vein variations.

The highly complex embryological development of the left renal vein compared to its right counterpart results in greater variations which are clinically significant. The study aimed to identify these variations and to document its incidence. Cadaveric study: 153 kidney pairs were harvested en bloc, dissected, 100 resin casts prepared and 53 plastinated; renal venography performed on further 58 adults and 20 foetal cadavers. Clinical study: (retrospective analysis): a) radiological study, 104 renal venograms; b) live related renal transplantation, 148 donor left kidneys; c) abdominal aortic aneurysm surgery, 525 patients. Total sample size: 1008. Renal collars observed in 0.3%; retro-aortic vein 0.5%; additional veins 0.4%; posterior primary tributary 23.2%, (16.7% Type IB; 6.5% Type IIB, cadaveric series, only). Our results differ significantly in incidence to that reported in the literature: renal collar 0.2-30%; retro-aortic vein 0.8-7.1%; additional renal vein 0.8-6%. Variations are clinically silent and remain unnoticed until discovered during venography, operation or autopsy. To a transplant surgeon, morphology acquires special significance, since variations influence technical feasibility of operation. Prior knowledge of circum-aortic vein is important when blood samples from suprarenal or renal veins are collected. Collar may provide developed collateral pathway immediately after surgery if renal interruption planned without awareness of its presence. Variations restrict availability of vein for mobilisation procedures. In aortic aneurysm repair, retro-aortic vein is important. During retroperitoneal surgery, the surgeon may visualise a pre-aortic vein but be unaware of an additional retroaortic component or a posterior primary tributary, and may avulse it while mobilising the kidney or clamping the aorta.

Adult↗

PubMed1999

Thyroid functions in lithium-treated psychiatric patients: a cross-sectional study.

In the present cross-sectional study, thyroid functions (viz. thyroid radioiodine uptake [RAIU] and serum T3, T4, and thyroid-stimulating hormone [TSH]) were evaluated in 24 healthy controls and 132 outdoor affective disorder patients. Eleven of these patients were to receive lithium (Li) and the remaining 121 patients were at different stages of Li treatment ranging from 0.7 to 240 mo. RAIU was found to increase significantly throughout the Li therapy and was associated with the corresponding rise in TSH levels. In totality, Li treatment induced subclinical hypothyroidism in 51/132 (39%) of patients. However, 8/51 patients who belonged to known iodine-deficient belt had abnormally high TSH (range 15.2-76.0 microIU/mL), low T4 (5.3+/-2.5 microg/dL), and normal T3 and at least 4 of these 8 patients were clinically hypothyroid. T4 levels declined significantly (p < 0.05) with Li treatment ranging from 61 to 240 mo as compared to the corresponding values in the pre-Li group. The T3/T4 ratio was found to be significantly higher with Li treatment ranging from 0.7 to 6 mo in comparison with the pre-Li group and this value returned to base levels after long-term Li therapy. High T3 and T4 were observed in 13% and 12% of the patients, respectively, as compared to the corresponding control values.

Adolescent↗

PubMed1999

Thoracoscopic splanchnicectomy: pilot evaluation of a simple alternative for chronic pancreatic pain control.

Achieving adequate pain control in patients with chronic pancreatitis remains a surgical challenge. The quest for a procedure that retains all of the residual pancreatic tissue in the absence of ductal dilatation remains elusive. This study sought to evaluate the feasibility and efficacy of thoracoscopic splanchnicectomy and attempted to outline the surgical anatomy appropriate to an adequate denervation. Of 17 patients considered suitable for the procedure, 16 had a sucessful outcome, which was statistically significant (p < 0.001). The longest follow-up of 30 months suggests that the procedure may be more enduring than percutaneous procedures. However, the surgical anatomy is not predictable owing to the racemose arrangement of the splanchnic fibers, and a long pleurotomy with transection of all medial fibers is necessary to effect denervation. Thoracoscopic splanchnicectomy may effect immediate pain relief with negligible morbidity and absent mortality. Although the follow-up period is short, the patient with the longest follow-up remains pain-free at 30 months. This procedure warrants scrutiny for its role in long-term pancreatic pain control.

Adult↗

PubMed1999

Effect of lithium on thyroidal 131iodine uptake, its clearance, and circulating levels of triiodothyronine and thyroxine in lead-treated rats.

The influence of lead acetate (50 mg per kg body weight) on the 131iodine (131I) biokinetics (uptake and retention) in rat thyroid and serum levels of triiodothyronine (T3) as well as thyroxine (T4) was evaluated as a function of time and in combination with lithium treatment. The 2-h and 24-h uptake of 131I in the thyroid was stimulated significantly by lead treatment. The 24-h uptake showed a maximum stimulation after 4 months of lead treatment. Lithium supplementation, however, showed the opposite effect by reducing the iodine uptake whereby the maximum decrease was noticed after 2 months of treatment. Further, simultaneous lead and lithium treatment resulted in an even more pronounced increase of 2-h 131I uptake with a maximum after 3 months. However, the 24-h uptake after 3 months and 4 months of treatment did not differ significantly from the lead treated reference groups. The thyroidal biological half-life of 131I (Tbiol) was found to have clearly increased following the lead/lithium treatment. Interestingly, the combined lead/lithium treatment applied for 4 months caused a further growth of Tbiol, thus reflecting an increased retention of 131I. A maximum increase of Tbiol was seen after 2 months of combined treatment. A progressive decline of the circulating T3 and T4 levels following lead or lithium treatment was noticed and was more pronounced after combined treatment.

Animals↗

PubMed1999

Radial artery in CABG: could the early results be comparable to internal mammary artery graft?

BACKGROUND: The accidental detection of patency of radial artery grafts, by Acar, which had been labeled as blocked 18 years earlier, has led to its revival as a conduit in coronary artery bypass surgery. We used radial artery as one of the grafts in 287 patients from February 1996 to June 1998. Here we present our early clinical experience and the midterm angiographic follow up of the initial 62 patients. METHODS: A no touch, atraumatic harvesting technique coupled with gentle hydrostatic and pharmacological dilatation of the radial artery graft was employed. Radial artery was used to revascularize coronary vessels with >80% proximal stenosis. Postoperatively, the patients were administered a low dose nifedipine that was continued for 6 months thereafter. The patients were followed up clinically after discharge from the hospital and angiographic evaluation of the grafted radial artery by selective injection was done at a mean interval of 16.2 +/- 5.1 months (3-24 months) postoperatively. RESULTS: There was no perioperative or late myocardial infarction or mortality. No significant complications related to the harvesting of radial artery were encountered. Angiographically, the radial artery grafts were found to be patent in 96.8% of patients (60/62). Mild distal anastomotic narrowing was seen in angiogram of one patient with good filling of the target vessel. Another patient showed diffuse spasm of radial artery graft. The patency of the pedicled left internal mammary grafts was also 98.2% (56/57). All the patients were asymptomatic. CONCLUSIONS: Radial artery seems to be an excellent alternate arterial conduit for myocardial revascularization with early and midterm patency rates equivalent to that of pedicled internal mammary artery, and it should be used more often for myocardial revascularization as an adjunct to pedicled internal mammary artery graft.

Adult↗

PubMed1999

Simple blood-spot sampling with nested polymerase chain reaction detection for epidemiology studies on Brugia malayi.

In the absence of a suitable Brugia malayi antigen detection assay, PCR remains one of the more sensitive alternatives to Giemsa-stained thick blood films for B. malayi detection. The need for refrigerated storage and transportation of blood has limited the use of PCR for large-scale epidemiology studies in remote endemic areas. Here we report simple finger-prick blood-spot collection, a one-tube DNA template extraction method and the development of a B. malayi-specific nested PCR assay. The assay was tested on 145 field samples and was positive for all 30 microscopy-positive samples and for an additional 13 samples which were microscopy-negative.

Animals↗

PubMed1999

A microstructural analysis of the control of water and isotonic saline ingestion by postingestional stimulation.

This study investigated the behavioral expression of the mechanisms of satiation from stimulation of the gastrointestinal tract by water and isotonic saline. We compared the licking behavior of water-deprived rats ingesting water or isotonic saline under real- and sham-drinking conditions. In real-drinking tests the rate of ingestion of both types of fluids declined after about 5 min of drinking, and had virtually ceased by 20 min, while in the sham-drinking tests the rate of drinking remained constant during this period. To assess the impact of postingestional stimulation on the microstructure of licking, we compared the size of the clusters (SC) of licking and the duration of the pauses between them (ICIs), during the 15-min period that began 5 min after the start of drinking in the real- and sham-drinking tests. With both fluids postingestional stimulation significantly reduced the number of clusters. With water, but not with isotonic saline, postingestional stimulation also reduced SC, an effect that was shown to be due to differential postingestional not oropharyngeal stimulation. Postingestional stimulation had no overall effect on the ICIs, but in tests with water, but not saline, it altered the shape of the ICI distribution by increasing the duration of the long ICIs. We concluded that the different mechanisms of satiation stimulated by the postingestional effects of water and isotonic saline are expressed in different patterns of the microstructure of licking.

Analysis of Variance↗

PubMed1999

Treatment of recurrent pleomorphic adenomas of the parotid gland.

Recurrent pleomorphic adenomas (RPAs) of the parotid gland are an uncommon but challenging problem. The records of 31 patients with RPAs were reviewed to assess the clinical presentation and treatment results. More than half of these patients underwent total parotidectomy. Local control was achieved in 94% of patients at 7 years (median follow-up 7.3 years). Patients who had surgery for recurrence after a formal parotidectomy were more likely to have another recurrence (63% local control at 7 years) than patients whose initial procedure was a limited excision (100% local control at 7 years; P < 0.01). Better local control was seen in 11 patients who received postoperative irradiation (100% at 10 years) than in 20 patients who did not (71% at 10 years; P < 0.28). Adequate surgical resection yields an acceptable local control rate in patients with RPAs. Postoperative radiation therapy may improve control in patients at high risk for another recurrence.

Adenoma, Pleomorphic↗

PubMed1999

A new amide from zanthoxylum armatum

A new amide designated as armatamide (1)-along with two lignans, asarinin and fargesin, alpha- and beta-amyrins, lupeol, and beta-sitosterol-beta-D-glucoside-has been isolated from the bark of Zanthoxylum armatum. The structure of the new compound was deduced by spectral and chemical analysis as N-(4'-methoxyphenyl ethyl)-3, 4-methylenedioxy cinnamoyl amide.

Journal Article↗