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Biomedical subjects

Manoj Kumar

Publications and source records attributed to Manoj Kumar.

52 records · Page 3Linked to original sources
PubMed2004

Mercury(II) ion-selective electrodes based on p-tert-butyl calix[4]crowns with imine units.

A PVC membrane incorporating p-tert-butyl calix[4]crown with imine units as an ionophore was prepared and used in an ion-selective electrode for the determination of mercury(II) ions. An electrode based on this ionophore showed a good potentiometric response for mercury(II) ions over a wide concentration range of 5.0 x 10(-5) - 1.0 x 10(-1) M with a near-Nernstian slope of 27.3 mV per decade. The detection limit of the electrode was 2.24 x 10(-5) M and the electrode worked well in the pH range of 1.3 - 4.0. The electrode showed a short response time of less than 20 s. The electrode also showed better selectivity for mercury(II) ions over many of the alkali (Na+, -1.69; K+, -1.54), alkaline-earth (Ca2+, -3.30; Ba2+, -3.32), and heavy metal ions (Co2+, -3.67; Ni2+, -3.43; Pb2+, -3.31; Fe3+, -1.82). Ag+ ion was found to be the strongest interfering ion. Also, sharp end points were obtained when the sensor was used as an indicator electrode for the potentiometric titration of mercury(II) ions with iodide and dichromate ions.

Journal Article↗
PubMed2004

Transcranial Doppler sonography evaluation in patients with vasospasm following subarachnoid haemorrhage.

Transcranial Doppler (TCD) sonography is emerging as a new ultrasonography technology to look at the interaction between the brain parenchyma and perfusion during cerebrovascular accident. Before TCD sonography the vasospasm following subarachnoid haemorrhage could only be diagnosed either clinically or by invasive method ie, angiography. TCD has been proved as a wonderful non-invasive, repeatable, beat-by-beat, non-expensive technique for detection and follow-up of vasospasm after subarachnoid haemorrhage. In the present series 12 patients suspected to have vasospasm after subarachnoid haemorrhage were confirmed and monitored with the help of TCD. Most of the patients were clinically presented with increasing headache and altered sensorium. It is noticed that vasospasm following subarachnoid haemorrhage has a typical course, which has increasing trend after 4th day of subarachnoid haemorrhage and declining trend after 14th day onwards. Six out of 12 patients were in moderate grade of vasospasm, 2 out of 12 were in severe grade and 4 out of 12 were mild grade of severity.

Blood Flow Velocity↗
PubMed2003

A novel membrane glycoprotein of Escherichia coli.

A novel glycoprotein (Gp45) has been isolated and purified from Escherichia coli. To our knowledge, Gp45 is the third glycoprotein isolated from E. coli membrane and it is the second in the non-pathogenic strain of the organism. For the isolation of Gp45, cell extract or membrane fraction was treated with sodium deoxycholate for 4 h and precipitated with trichloroacetic acid (TCA). The supernatant fraction of TCA containing the Gp45 was further purified on DEAE-Sephadex A-25. SDS-PAGE showed a single band at 45 kDa position that stained with periodic-Schiff reagent. It contained 60% carbohydrate and 40% protein content. The monosaccharide composition also substantiated the characteristics of the glycoprotein. The E. coli grown in presence of (14)C-glucosamine further confirmed the localization and biosynthesis of this glycoprotein on the membrane during the growth phase. Bacitracin, a general inhibitor of the glycosylation, inhibited its biosynthesis.

Bacterial Outer Membrane Proteins↗
PubMed2003

Bacterial glycoproteins: functions, biosynthesis and applications.

Although widely distributed in eukaryotic cells glycoproteins appear to be rare in prokaryotic organisms. The prevalence of the misconception that bacteria do not glycosylate their proteins has been a subject matter of discussion for a long time. Glycoconjugates that are linked to proteins or peptides, generated by the ribosomal translational mechanism have been reported only in the last two to three decades in a few prokaryotic organisms. Most studied prokaryotic glycoproteins are the S-layer glycoproteins of Archeabacteria. Apart from these, membrane-associated, surface-associated, secreted glycoproteins and exoenzymes glycoproteins are also well documented in both, Archea and Eubacteria. From the recent literature, it is now clear that prokaryotes are capable of glycosylating proteins. In general, prokaryotes are deprived of the cellular organelles required for glycosylation. In prokaryotes many different glycoprotein structures have been observed that display much more variation than that observed in eukaryotes. Besides following similar mechanisms in the process of glycosylation, prokaryotes have also been shown to use mechanisms that are different from those found in eukaryotes. The knowledge pertaining to the functional aspects of prokaryotic glycoproteins is rather scarce. This review summarizes developments and understanding relating to characteristics, synthesis, and functions of prokaryotic glycoproteins. An extensive summary of glycosylation that has been reported to occur in bacteria has also been tabulated. Various possible applications of these diverse biomolecules in biotechnology, vaccine development, pharmaceutics and diagnostics are also touched upon.

Bacterial Proteins↗
PubMed2003

Fish bone as a foreign body.

Fish bones are one of the most common foreign bodies in the upper aero-digestive tract. The use of plain X-ray in identifying fish bones has questionable value. We believe that the knowledge of the type of the fish ingested improves the diagnostic value of the neck X-rays. This study was designed to evaluate the relative radio-densities of the bones of commonly eaten fish in the UK. Twenty-three species of fish were studied and their bones were grouped into three depending upon their ratio-densities. This information is expected to be useful in identifying fish bones while reading plain radiography.

Animals↗
PubMed2002

Is the mitral valve area flow-dependent in mitral stenosis? A dobutamine stress echocardiographic study.

OBJECTIVES: The purpose of this study was to compare the effect of changes in flow rate on the mitral valve area (MVA) derived from two-dimensional echocardiographic planimetry and Doppler pressure half-time (PHT) methods in patients with mitral stenosis (MS). BACKGROUND: Dobutamine stress echocardiography has been proposed as a means of assessing the severity of MS. However, data regarding the effect of an increase in flow rate on MVA are limited. If MVA is indeed flow-dependent, this has important implications for the assessment of the severity of MS, particularly in the setting of reduced cardiac output (CO). METHODS: Dobutamine echocardiography was performed in 57 patients with isolated MS who were in sinus rhythm. The MVA was determined by planimetry and Doppler PHT methods. RESULTS: Cardiac output increased by > or =50% in 27 patients (group I) and by <50% in 30 patients (group II). In group I, the MVA by planimetry increased by only 10.6 +/- 2% and the MVA by PHT increased by 21.9 +/- 4.8%. These changes were similar to those observed in group II (10.7 +/- 3% and 14.8 +/- 4%, respectively; p = NS), despite a much smaller increase in CO. A clinically important change (from the severe to mild category) occurred in only one patient when using the PHT method and in none by planimetry. CONCLUSIONS: Changes in flow rate result in small but clinically insignificant changes in echocardiographic MVA measurement. These methods provide an accurate assessment of MS severity in a majority of patients, independent of changes in flow rate.

Adolescent↗
PubMed2002

Rapid kinetic studies of acetyl-CoA synthesis: evidence supporting the catalytic intermediacy of a paramagnetic NiFeC species in the autotrophic Wood-Ljungdahl pathway.

CO dehydrogenase/acetyl-CoA synthase (CODH/ACS), a key enzyme in the Wood-Ljungdahl pathway of anaerobic CO(2) fixation, is a bifunctional enzyme containing CODH, which catalyzes the reversible two-electron oxidation of CO to CO(2), and ACS, which catalyzes acetyl-CoA synthesis from CoA, CO, and a methylated corrinoid iron-sulfur protein (CFeSP). ACS contains an active site nickel iron-sulfur cluster that forms a paramagnetic adduct with CO, called the nickel iron carbon (NiFeC) species, which we have hypothesized to be a key intermediate in acetyl-CoA synthesis. This hypothesis has been controversial. Here we report the results of steady-state kinetic experiments; stopped-flow and rapid freeze-quench transient kinetic studies; and kinetic simulations that directly test this hypothesis. Our results show that formation of the NiFeC intermediate occurs at approximately the same rate as, and its decay occurs 6-fold faster than, the rate of acetyl-CoA synthesis. Kinetic simulations of the steady-state and transient kinetic results accommodate the NiFeC species in the mechanism and define the rate constants for the elementary steps in acetyl-CoA synthesis. The combined results strongly support the kinetic competence of the NiFeC species in the Wood-Ljungdahl pathway. The results also imply that the methylation of ACS occurs by attack of the Ni(1+) site in the NiFeC intermediate on the methyl group of the methylated CFeSP. Our results indicate that CO inhibits acetyl-CoA synthesis by inhibiting this methyl transfer reaction. Under noninhibitory CO concentrations (below 100 microM), formation of the NiFeC species is rate-limiting, while at higher inhibitory CO concentrations, methyl transfer to ACS becomes rate-limiting.

Acetate-CoA Ligase↗
PubMed2002

Intracardiac echocardiography guided radiofrequency catheter ablation of the slow pathway in atrioventricular nodal reentrant tachycardia.

BACKGROUND: ICE has demonstrated its utility in imaging right atrial structures but its utility in slow pathway (SP) ablation has not been documented in a randomized trial. METHODS: The feasibility of using ICE as a imaging modality to identify the effective site of SP ablation was done in part one of the study comprising 10 patients of typical AVNRT. Subsequently, a prospective randomized study was done comparing the conventional (group A) and ICE guided (group B) ablation of the SP. Each group had 20 patients of typical AVNRT. Ablation in the conventional arm was guided by intracardiac electrograms and fluoroscopy. Group B patients underwent SP ablation guided primarily by ICE imaging; fluoroscopy was used mainly for initial placement of catheters. RESULTS: Reliable & stable ICE images were obtained in all patients. Part I of the study showed that RF pulses given when the ablation catheter was seen to cross the atrioventricular muscular septum (AVMS), always resulted in junctional rhythm. In Group B, RF pulse was delivered only when the ablation catheter was at the AVMS making an obtuse angle with the image of the His-bundle catheter. Consistent junctional rhythm and abolition of SP resulted at this site. Compared to group A, patients in group B required fewer pulses (mean 1.4 +/- 0.6 vs. 4.4 +/- 3.0; p < 0.05, median 1 vs. 5; p < 0.01), achieved a higher temperature (56 +/- 4 degrees C vs. 50 +/- 6 degrees C) and had more frequent junctional rhythm (100% vs. 70%) during RF pulse. CONCLUSIONS: A critical portion of SP exists adjacent to Tricuspid valve overlying the AVMS. ICE imaging consistently and reliably localizes this site and RF applications here result in interruption of antegrade SP conduction.

Adult↗
PubMed2002

Short-term complications of percutaneous tracheostomy: experience of a district general hospital--otolaryngology department.

Percutaneous tracheostomy is a procedure frequently carried out in a critical care setting. It is performed in the majority of cases by anaesthetists in the United Kingdom. The ENT surgeon is only called in situations where it is deemed by the intensivist that percutanous tracheostomy would prove too great a risk. In this situation the patient was taken to the operating theatre for a surgical tracheostomy. In our paper, a retrospective analysis was performed of all percutaneous tracheostomies carried out by ENT surgeons in the Royal Glamorgan Hospital, during a two-year period from July 1999 to July 2001, to assess whether percutaneous tracheostomy is a feasible option as a first line procedure in all elective tracheostomies. Thirty-six patients were included in the study. The mean age was 60.2 years. Haemorrhage was noted to be a problem in only one patient and two patients developed postoperative wound infection that was treated with systemic antibiotics. No other complications were encountered. We propose that all ENT surgeons should be trained in performing percutaneous tracheostomy and that it should be used as the gold standard in elective tracheostomy insertion. In cases where difficulties are likely to be anticipated, percutaneous tracheostomy can still be considered as the first option. This can be performed in the operating theatre setting with the knowledge that if any complication should occur then conversion to surgical tracheostomy can be done without delay.

Adult↗
PubMed2002

Effect of dietary administration of Lathyrus sativus pulse on intestinal biochemical parameters in normal and scorbutic guinea pigs.

OBJECTIVE: In order to investigate that ascorbic acid deficiency is responsible for lathyrus toxicity, the effect of dietary feeding of lathyrus pulse in normal and scorbutic guinea pigs for 3 months, on intestinal biochemical parameters was undertaken. METHODS: The intestinal brush border membrane (BBM) marker and xenobiotic metabolising enzymes (XME) were assayed. RESULTS: Exposure to 80% lathyrus alone and in scorbutic conditions showed significant inhibition of alkaline phosphatase (28%-30%), sucrase (19%) and gamma-glutamyl transpeptidase (GGT) (15%-27%) enzymes, while Ca(2+)-Mg(2+)-ATPase was significantly inhibited (38%) in scorbutic plus lathyrus treated group. The phase I XME (AHH) remained unchanged while the phase II enzyme glutathione-S-transferase (GST) was significantly decreased (20%-22%) in lathyrus and scorbutic plus lathyrus treated groups. Quinone reductase (QR) activity was found to be significantly decreased in lathyrus exposed group (20%). The intestinal biomarker contents including hexose (25%-34%) and phospholipids (20%-40%) were significantly reduced in lathyrus and scorbutic plus lathyrus exposed animals, while sialic acid showed a significant decrease (28%) in scorbutic plus lathyrus treated group. However, cholesterol levels were significantly enhanced (15%-28%) in lathyrus and scorbutic plus lathyrus treated animals. CONCLUSION: The results indicate that oral feeding of lathyrus pulse to guinea pigs can alter BBM parameters as well as XME, which may result in the intestinal toxicity. Further, ascorbic acid deficiency could be one of the pre-disposing factors of lathyrus toxicity.

Administration, Oral↗
PubMedDate not supplied

Citrinin and endosulfan induced teratogenic effects in Wistar rats.

Dietary exposures to food pollutants such as mycotoxin(s) or pesticide(s) are most significant due to their adverse effects on the production and reproduction in animals and the human population. The present investigation was conducted to evaluate the teratogenic potential of citrinin (CIT) and endosulfan either alone or in combination in pregnant rats during gestational days 6-20. Endosulfan (1 mg kg(-1) body weight, by oral intubation) and CIT (10 mg kg(-1) feed, through diet) when administered either alone or in combination in pregnant rats caused significant teratogenic effects in the developing fetuses. There was no maternal mortality, however, reduced maternal weight gain and number of live fetuses and increased fetal resorptions were recorded in all the treated groups. The fetal body weights and crown to rump lengths were significantly decreased and the per cent gross, visceral and skeletal anomalies were significantly increased in the fetuses of dams of all the treated groups. The internal hydrocephalus, cerebellar hypoplasia, microphthalmia, contracted and notched kidneys, multilobulated liver, dilated renal pelvis, incomplete ossification of skull bones, rib anomalies and sacral and caudal vertebrae agenesis were the important fetal malformations. The occurrence of fetal gross, skeletal and visceral malformations was more severe in the combination group, suggesting an additive interaction of CIT and endosulfan in inducing developmental toxicity in Wistar rats.

Abnormalities, Drug-Induced↗
PubMedDate not supplied

Epidural opioid analgesia and neonatal respiratory depression.

Epidural opioid analgesia is commonly employed as a therapeutic modality in the management of pain during labor. The general perception among health-care providers is that administered drugs remain in the maternal epidural space and do not compromise the respiratory status of newborns. We describe the clinical course of two newborns who developed respiratory depression following epidural fentanyl analgesia requiring administration of naloxone. The article further reviews the maternal-fetal-placental pharmacokinetics of epidural fentanyl and the possible mechanisms for the causation of neonatal respiratory depression.

Analgesia, Epidural↗
PubMedDate not supplied

Development of pulsatile systems for targeted drug delivery of celecoxib for prophylaxis of colorectal cancer.

The aim of the present study was to formulate fast release enteric-coated tablets for drug delivery to the colon. Two different approaches were used for the preparation of these tablets. The first included making use of superdisintegrant (SD) in the tablet. The amount of super disintegrant (cross-linked PVP) in the tablet and the coat weight were varied to formulate a suitable time-controlled release system, that would provide colon-specific drug delivery. The second approach consisted of development of osmogen-based tablets for drug delivery into the tracts of the colon. Two different osmogens, sodium chloride and potassium chloride, were used. These also were coated at different coat levels. Celecoxib was used as a model drug. In vitro drug release studies showed that superdisintegrants were more effective in showing burst effect in the tablets and therefore showed a rapid drug release as compared with osmogens, which would show a sustained drug release all through the colon. Osmotic tablets were formulated making use of a high concentration of osmogen sodium chloride (OM-SC) and potassium chloride (OM-KC) were further enteric-coated. These also were found to be useful in providing a sustained delivery of nearly 80-90% of the drug into the colonic region. The coat weight required in these tablets for protection in the upper gastrointestinal conditions varied from 9.69% in OM-KC tablets to 4.65% in OM-SC tablets.

Anti-Inflammatory Agents, Non-Steroidal↗