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Biomedical subjects

H Singh

Publications and source records attributed to H Singh.

At least 127 records · Page 7Linked to original sources
PubMed1999

Synthesis and fungicidal activity of some 5-(2-aminoalkanoyl)-8-aryl-4(5H)-oxo-1,2,4-triazolo[4,3-b]-1,4,2, 6-dithiadiazine 6,6-dioxide derivatives.

Title compounds (5) were conveniently prepared from 5-aryl-3-mercapto-1,2,4-triazoles (1) and chloro-sulphonyl isocyanate (CSI) to give 8-aryl-4-(5H)-oxo-1,2,4-triazolo-[4,3-b]-1,4,2,6-dithiadiazine -6,6-dioxide (2). The Compound (2) and one suspension of 2-(benzyloxycarbonylamino) akanoic acid (3) in the presence of BOP reagent afforded Z-derivatives 8-aryl-5-(2-benzyloxycarbamoyl)alkanoyl-4(5H)-oxo- 1,2,4-triazolo[4,3-b]-1,4,2,6-dithiadiazine 6,6-dioxide (4). The Z-derivatives (4) gave aspected product (5) when treated with Pd-c 5% and formic acid in DMF. These compounds have been tested in vitro for their fungicidal activity against Aspergillus niger, Fusarium oxisporum and Cephalosporium saccharii and results were compared with their parent dithidiazines.

Antifungal Agents↗
PubMed1998

PU.1 regulates both cytokine-dependent proliferation and differentiation of granulocyte/macrophage progenitors.

PU.1 is a unique regulatory protein required for the generation of both the innate and the adaptive immune system. It functions exclusively in a cell-intrinsic manner to control the development of granulocytes, macrophages, and B and T lymphocytes. We demonstrate that mutation of the PU.1 gene causes a severe reduction in myeloid (granulocyte/macrophage) progenitors. PU.1 -/- myeloid progenitors can proliferate in vitro in response to the multilineage cytokines interleukin-3 (IL-3), IL-6 and stem cell factor but are unresponsive to the myeloid-specific cytokines granulocyte-macrophage colony-stimulating factor (GM-CSF), G-CSF and M-CSF. The failure of PU.1 -/- progenitors to respond to G-CSF is bypassed by transient signaling with IL-3. In the presence of IL-3 and G-CSF, PU.1 -/- progenitors can differentiate into granulocytic precursors containing myeloperoxidase-positive granules. Thus PU.1 is not essential for specification of granulocytic precursors, but is required for their further differentiation. The failure of PU.1 -/- progenitors to respond to M-CSF is due to lack of c-fms gene transcription. Transduction of c-fms into PU.1 -/- myeloid progenitors bypasses the block to M-CSF-dependent proliferation but does not induce detectable macrophage differentiation. Therefore, PU. 1 appears to be essential for specification of monocytic precursors. Importantly, retroviral transduction of PU.1 into mutant progenitors restores responsiveness to myeloid-specific cytokines and development of mature granulocytes and macrophages. Thus PU.1 controls myelopoiesis by regulating both proliferation and differentiation pathways.

Animals↗
PubMed1998

Effect of adenotonsillectomy on arterial blood gases and acid-base balance.

Adenotonsillitis is quite common in children in India and untreated cases may land up with serious cardiopulmonary complications which promoted us to study arterial blood gases and acid-base balance in these patients. The study was conducted in 30 children with chronic adenotonsillitis and 30 age and sex matched controls. Arterialized capillary blood samples were taken before and 1 month after surgery while the subject was sleeping. Relative hypoxemia, rise in pCO2 and increased bicarbonates was observed in the study group, whereas change in pH was insignificant. The study showed that ventilatory impairment associated with adenotonsillar hypertrophy which manifests as hypoxia, hypercarbia and raised bicarbonate levels was reversed after adenotonsillectomy.

Acid-Base Equilibrium↗
PubMed1998

Destabilization of Oil-in-Water Emulsions Formed Using Highly Hydrolyzed Whey Proteins.

Oil-in-water emulsions (4 wt % soy oil) were prepared with 0.5-5 wt % whey protein hydrolysate (WPH) (27% degree of hydrolysis), in a two-stage homogenizer using various first-stage pressures of 10.3, 20.6, and 34.3 MPa and a constant second-stage pressure of 3.4 MPa. Destabilization studies on the emulsions were carried out for up to 24 h, using both laser light scattering and confocal laser microscopy. It was found that emulsions formed with <2% WPH showed oiling off and coalescence at all homogenization pressures. Emulsions formed with 2, 3, and 4% WPH showed coalescence and creaming only, while slight flocculation but no creaming occurred in emulsions formed with 5% WPH. Furthermore, the apparent rate of coalescence increased with homogenization pressure but decreased with WPH concentration. In contrast, the surface concentration of WPH increased with the WPH concentration in the emulsions but decreased with homogenization pressure. Analysis of WPH by high-performance liquid chromatography showed an increase in the concentration of high molecular weight peptides at the droplet surface compared to the WPH solution. This was considered very important for the stability of these oil-in-water emulsions.

Journal Article↗
PubMed1998

Conjugation in archaea: frequent occurrence of conjugative plasmids in Sulfolobus.

We describe five novel conjugative plasmids (CPs) and two subfamilies, each comprising several closely related variants of CPs isolated from colony-cloned strains of the extremely thermophilic, heterotrophic archaeon Sulfolobus islandicus, which were obtained by plating of samples from Icelandic solfataras after liquid enrichment. They are related to each other and to the previously described CP pNOB8 from a Japanese Sulfolobus strain in that they share essential functions and limited similarity of genomes as demonstrated by DNA cross-hybridization and sequences. All these plasmids thus form a family of highly efficient self-spreading elements directly transferred from donor into recipient cells. Conjugation is initiated by pair formation, followed by selective transfer of the plasmids into the recipient and expression of transfer functions. Some of these CPs exclude superconjugation of the transcipients with closely related CPs. The novel CPs are stable upon conjugative transfer, but vary upon growth of transcipients. The stability of the CPs is higher in their original hosts or in related S. islandicus strains, than in Sulfolobus solfataricus strain PH1 as recipient. The deletion variant pING3 has lost the ability to transfer itself but is still subject to being transferred by the transfer apparatus of its complete relative, pING6. The dissection of genes and functions has been initiated by characterizing this incomplete variant.

Bacteriological Techniques↗
PubMed1998

Functional magnetic stimulation for restoring cough in patients with tetraplegia.

OBJECTIVE: To evaluate the usefulness of functional magnetic stimulation (FMS) as a noninvasive method for assisting cough in patients with tetraplegia. DESIGN: A prospective before-after trial. SETTING: The functional magnetic stimulation laboratory of a spinal cord injury (SCI) service. PARTICIPANTS: Thirteen male SCI patients, with injury levels between C4 and C7. INTERVENTION: A commercially available magnetic stimulator with a round magnetic coil (MC) was used. Expiratory muscle activation was achieved by placing the MC along the lower thoracic spine. MAIN OUTCOME MEASURE: The planned major outcome measures were the maximal expired pressure (MEP), expiratory reserve volume (ERV), and forced expiratory flow rate (FEF) by FMS compared with voluntary maximal efforts. Another outcome was the optimal MC placement and stimulation intensity that would result in highest expired pressure. RESULTS: The mean (+/-SEM) MEP, ERV, and FEF generated by FMS were 66.40 +/- 6.69 cmH2O, .77 +/- .14 L, and 5.28 +/- .42 L/sec, respectively. They were 118%, 169%, and 110% of voluntary maximum efforts. MC placement at the T10 to T11 spinous process and stimulation intensity at 80% produced the highest MEP and FEF. CONCLUSION: FMS of the expiratory muscles produced significant expired pressures, volumes, and flow rates when compared with voluntary maximum efforts; therefore, FMS can be used as an effective method to restore cough in tetraplegic patients.

Abdominal Muscles↗
PubMed1998

Electron tomography of ice-embedded prokaryotic cells.

Whole cells of archaea were embedded in vitreous ice by plunge freezing and investigated by automated energy-filtered electron tomography at 120 kV. The embedded cells were between 300 and 750 nm thick, and their structures were reconstructed to a resolution of 20-40 nm from tilt series comprising 50-140 images. The dose was kept within tolerable limits. A resolution of 20 nm allowed visualization of the individual stalks of the S-layer of Pyrobaculum aerophilum cells, which had undergone partial lysis, in three dimensions. The attainable resolution for low-dose electron tomography under different experimental conditions was theoretically investigated in terms of the specimen thickness. To obtain 2-nm resolution at 120 kV (300 kV), the specimen must not be thicker than 100 nm (150 nm). For a resolution of 10 nm, the maximum thickness is 450 nm (700 nm). An accelerating voltage of 300 kV is advantageous, mainly for specimens thicker than 100 nm. Experimental investigations so far have resulted in a resolution that is worse by a factor of 2-5 as compared to theory.

Automation↗
PubMed1998

Cardiff repair of incisional hernia: a university hospital experience.

OBJECTIVE: To analyse our results of the "Cardiff' (far and near) repair in incisional hernias. DESIGN: Prospective study. SETTING: University hospital, Varanasi, India. SUBJECTS: 50 patients who presented with incisional hernias between January 1990 and December 1994. INTERVENTION: Interrupted far-and-near sutures inserted after excision of the sac. The contents were pushed into the abdomen and the peritoneum sutured with non-absorbable polypropylene (prolene). MAIN OUTCOME MEASURES: Early and late morbidity. Six patients developed postoperative complications (wound infection, n=3; flap necrosis, n=2; and wound sinus, n=1). No patient has been lost to follow up and there have been no signs of recurrence after a mean follow up of 52 months. CONCLUSION: The meticulous application of this simple surgical technique has low morbidity and is cost effective. We recommend it for small and medium size defects.

Adolescent↗
PubMed1998

Profile of young acute myocardial infarction in Harayana.

Profile of acute myocardial infarction (AMI) in young patients (below 40 years) was studied in a rural/semi-urban population. Out of the total 338 patients who were admitted to ICCU over a period of one year, 65 (19.2%) were aged 40 years or below (Range 14-40 years). Male:female ratio was 20:1. Majority of these young patients were thinly built, engaged in heavy physical work and belonged to lower socio-economic group. Smoking was the most common risk factor (87%); other risk factors were few. Majority of these young patients ignored chest pain and reported late to the hospital. However, despite this, incidence of complications/mortality was less in comparison to their older counterparts. The overall mortality was only 6% as compared to 21% in older age group. The study focuses our attention to the rising incidence of AMI in young individuals even in populations least prone to ischaemic heart disease. Smoking was the only modifiable risk factor which needs to be curbed with full force.

Adolescent↗
PubMed1998

Cardiac arrhythmias in aluminium phosphide poisoning studied by on continuous holter and cardioscopic monitoring.

Variable incidences of cardiac arrhythmias (based on isolated 12 lead ECG records) have been reported in patients of aluminium phosphide (ALP) poisoning. We did continuous holter and cardioscopic monitoring in ICU in 30 patients of acute ALP poisoning. Supraventricular and ventricular ectopics were recorded in each and every patient. Life threatening ventricular tachycardia was recorded in 40% cases and ventricular fibrillation in 23.3% cases. Supraventricular tachycardia and atrial flutter/fibrillation occurred in 46.7% and 20% patients, respectively. ST-T changes simulating myocardial ischaemia were also present in all patients (S-T depression in 90%, S-T elevation in 10%). One-third of the patients developed variable degrees of heart block, IV amiodarone/xylocard could revert dangerous ventricular arrhythmias to sinus rhythm in 4 cases. Toxic myocarditis produced by phosphine seems to be responsible for the development of these arrhythmias.

Adolescent↗
PubMed1997

Using altered specificity Oct-1 and Oct-2 mutants to analyze the regulation of immunoglobulin gene transcription.

Oct-1 and Oct-2 represent the prototypical example of related transcription factors with identical DNA recognition properties. They bind functionally critical octamer elements found in diverse regulatory sequences. It has not been possible to determine directly if these factors are functionally redundant or selective when interacting with different regulatory sequences in the appropriate cell type. An equivalent pair of altered DNA-binding specificity mutants of Oct-1 and Oct-2 are used to examine their function from varied regulatory contexts in B cells. These factors function as redundant activators of immunoglobulin (Ig) gene promoters (Vkappa and VH) and a histone H2B promoter. The structural basis of redundancy resides in the highly conserved DNA-binding POU domain, because this domain of either protein can activate transcription from both Ig and H2B promoters. We find that the nature of a distal enhancer dictates the relative potency of Oct-1 versus Oct-2 bound to a promoter. Oct-1 preferentially stimulates transcription from a VH or Vkappa promoter in combination with enhancers from the IgH or Igkappa locus, respectively. In this context, the more potent action of Oct-1 is dependent on a region external to the POU domain. These results suggest that Oct-1 may be the critical regulator of Ig gene transcription during B cell development and provide an explanation for selective Ig isotype expression defects in Oct-2 and OCA-B null mice.

Animals↗
PubMed1997

Perioperative anaesthetic considerations for patients undergoing lung transplantation.

PURPOSE: Five thousand, two hundred and eight lung transplants were performed worldwide before April, 1996. This review will discuss lung transplantation from an historical perspective, its indications, donor and recipient selection criteria, donor lung preparation, surgical considerations, perioperative anaesthetic management, and associated morbidity and mortality. SOURCE: Recent literature on perioperative anaesthetic management of lung transplantation and experience from international centres including the Toronto Lung Transplant Group and the St. Louis Lung Transplant Group. PRINCIPAL FINDINGS: Lung transplantation comprises of a family of operations, including single lung transplant, bilateral single lung transplant, lobar transplant and block heart-lung transplant. Improved donor lung preservation techniques have increased the duration of cold ischaemic time. The advent of bilateral single lung transplant has decreased the requirement for cardiopulmonary bypass, and airway complications have been reduced by adoption of the telescoping bronchial anastomoses. Advances in perioperative monitoring (including transoesophageal echocardiography), pulmonary vasodilators (e.g., nitric oxide and prostaglandin E1), cardiopulmonary bypass and ventilatory management, and a better understanding of the pathophysiological processes during the procedure have improved perioperative anaesthetic management. Also, advances in broad spectrum antibiotics and immunosuppressant drugs have improved the outcome by better management of the complications of infection and rejection. CONCLUSION: Lung transplantation improves the quality of life with marginal improvement in life expectancy of the recipients. It is an expensive procedure requiring continued resources for long term management of these patients.

Anesthesia↗