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Biomedical subjects

G Kumar

Publications and source records attributed to G Kumar.

At least 37 records · Page 2Linked to original sources
PubMed2000

"Development" is not essential to reduce infant mortality rate in India: experience from the Ballabgarh project.

BACKGROUND: India aims to reduce the infant mortality rate (IMR) to below 60 per 1000 live births by 2000. IMR is higher in northern India as compared with south Indian states like Kerala. Any further reduction in IMR needs identification of new strategies. The Ballabgarh project with an IMR of 36 in 1997 can help identify such strategies. OBJECTIVE: To see the trend in reduction of neonatal mortality rate (NNMR) and IMR at the Ballabgarh project, compare it with Kerala and rural India's trend and look at the causes of neonatal and infant mortality. DESIGN: The Comprehensive Rural Health Services Project, Ballabgarh, run by the All India Institute of Medical Sciences, covered an estimated population of 70,079 in 1997. The health care delivery system is on the national pattern. All the deaths are identified during the house visits by the male workers. The cause of death is ascertained by the health assistant based on the symptomatology at the time of death. RESULTS: The trends in reduction of IMR for Ballabgarh, Kerala and rural India are roughly parallel with the IMR of Ballabgarh lying somewhere in between the two. However, the NNMR of Ballabgarh (10.6 in 1996) was comparable to Kerala's NNMR (10.9 in 1992). The proportion of infant deaths occurring during the neonatal period had fallen from 50% in the early seventies to 30% during 1996-97. In 1992-1994, 33.8% of all neonatal deaths were attributable to low birth weight and 37.3% to infective causes. Acute respiratory infection and diarrhoea continue to be the chief cause of postneonatal mortality. CONCLUSION: It is possible to bring down neonatal mortality before postneonatal mortality. The Kerala model, which focuses on social development, may not apply to northern India for sociocultural reasons.

Acute Disease↗
PubMed2000

Cloning and functional expression of human retinal kir2.4, a pH-sensitive inwardly rectifying K(+) channel.

To identify novel potassium channel genes expressed in the retina, we screened a human retina cDNA library with an EST sequence showing partial homology to inwardly rectifying potassium (Kir) channel genes. The isolated cDNA yielded a 2,961-base pair sequence with the predicted open reading frame showing strong homology to the rat Kir2. 4 (rKir2.4). Northern analysis of mRNA from human and bovine tissues showed preferential expression of Kir2.4 in the neural retina. In situ hybridization to sections of monkey retina detected Kir2.4 transcript in most retinal neurons. Somatic hybridization analysis and dual-color in situ hybridization to metaphase chromosomes mapped Kir2.4 to human chromosome 19 q13.1-q13.3. Expression of human Kir2. 4 cRNA in Xenopus oocytes generated strong, inwardly rectifying K(+) currents that were enhanced by extracellular alkalinization. We conclude that human Kir2.4 encodes an inwardly rectifying K(+) channel that is preferentially expressed in the neural retina and that is sensitive to physiological changes in extracellular pH.

Amino Acid Sequence↗
PubMed2000

Lipoleiomyoma of broad ligament: a case report.

Lipoleiomyoma is a very uncommon tumor, and broad ligament of uterus is one of the rare sites. No case has been reported in last five years. This case is presented because of its rarity and its uncommon site of occurrence.

Adult↗
PubMed1999

Enzymatic grafting of a natural product onto chitosan to confer water solubility under basic conditions

Chitosan is a natural biopolymer whose rich amine functionality confers water solubility at low pH. At higher pH's (greater than 6. 5), the amines are deprotonated and chitosan is insoluble. To attain water solubility under basic conditions we enzymatically grafted the hydrophilic compound chlorogenic acid onto chitosan. Despite its name, chlorogenic acid is a nonchlorinated phenolic natural product that has carboxylic acid and hydroxyl functionality. The enzyme in this study was tyrosinase, which converts a wide range of phenolic substrates into electrophilic o-quinones. The o-quinones are freely diffusible and can undergo reaction with the nucleophilic amino groups of chitosan. Using slightly acidic conditions (pH = 6), it was possible to modify chitosan under homogeneous conditions. When the amount of chlorogenic acid used in the modification reaction exceeded 30% relative to chitosan's amino groups, the modified chitosan was observed to be soluble under both acidic and basic conditions, and to have a pH window of insolubility at near neutral pH. 1H NMR spectra confirmed that chitosan was chemically modified, although the degree of modification was low. Copyright 1999 John Wiley & Sons, Inc.

Journal Article↗
PubMed1999

The effect of patient reassignment on future continuity in a pediatric resident continuity practice.

BACKGROUND: When residents complete their pediatric training, patients from their continuity practices in academic settings must be reassigned to either a known resident of their selection or an unknown, incoming intern. OBJECTIVES: To determine what antecedent factors were associated with patient reassignment to a known resident of their selection, whether such reassignment was associated with increased health care use, and what factors were associated with continuity with the new resident provider. DESIGN: Nonconcurrent cohort study. SETTING: Hospital-based resident continuity clinic practice. PARTICIPANTS: Patients of residents graduating in June 1993. RESULTS: Seven hundred fifty-eight patients of 18 graduating residents required reassignment: 86 patients (11%) were assigned to a resident colleague, defined as the study group. From the remaining 673 patients who were assigned to unknown, incoming interns, a control group was randomly selected (n = 160), with approximately 2 patients for each study group subject. Looking at antecedent factors, study group patients were more likely to have chronic medical problems and to have seen their graduating resident more often and more recently. Univariate analysis explored the consequent factors of health care use and found that study group patients were more likely to return for a visit and to make more visits with the new provider. Multiple logistic regression analysis demonstrated that being in the study group, younger age at the original encounter with the graduating resident, and a shorter interval since the last visit with the graduating resident were all associated with increased continuity with the new resident. CONCLUSIONS: The method of patient reassignment at a continuity clinic was associated with chronic disease of the patient and regularity of visits with the graduating resident. Increased continuity with a new resident, as determined by multivariate analysis, was associated with the method of reassignment, a younger age at first encounter with the graduating resident, and a shorter interval since the last visit with the graduating resident. This study has implications at ambulatory sites where transitions occur.

Academic Medical Centers↗
PubMed1999

Malignant transformation of mesenchymal hamartoma of the liver: case report and review of the literature.

Here the first case in the literature of both mesenchymal hamartoma and malignant mesenchymoma occurring in a 6-year-old male child, at different times and at different sites in the liver, and also the possible malignant transformation of a mesenchymal hamartoma is reported. The tumor developed from a lesion in the right lobe that was overlooked initially during a left lateral segmentectomy at 18 months of age for a mesenchymal hamartoma. Malignant mesenchymoma is a rare and aggressive tumor. The origin of this tumor is not well understood. There has been no direct support to the hypothesis that malignant mesenchymoma may be the malignant counterpart of mesenchymal hamartoma. The authors provide clinical and histopathologic evidence in our case that suggests the possibility of malignant mesenchymoma arising from a mesenchymal hamartoma. This case emphasizes the need for complete removal of mesenchymal hamartoma and the need for long-term follow-up to detect multifocal lesion or malignant transformation.

Antineoplastic Agents↗
PubMed1999

The Internal Medicine Center--an integrated solution for information on internal medicine on the World Wide Web.

The World Wide Web (WWW) has grown from being a resource center for a select group of scientists to a large database of information that is available to both professionals and public. The amount of medical information on the Web has been increasing exponentially and thus, it has become increasingly difficult for anyone to be able to search for a specific quantum of information among this mass. Even in mid 1996, it was noted that the amount of information on internal medicine was growing rapidly. Hence, on 21 March 1997, the Internal Medicine Center (IMC) was created and launched. The IMC is an unique concept and it represents the first time that medical data on the web has been organized into a form that intimately parallels clinical medicine. The rationale behind the creation of the IMC can be summarized in three words: information, speed and convenience. The interface used by this center reflects these goals because overuse of large image files are avoided, hence decreasing the access time and yet keeping the information in an easily comprehensible manner. In conclusion, the IMC serves as a useful tool for the layman as well as the expert because the comprehensive information that it offers can be accessed rapidly and conveniently.

Information Services↗
PubMed1999

Asymmetric distribution of muscarinic acetylcholine receptors in Madin-Darby canine kidney cells.

We have characterized the muscarinic ACh receptors (mAChRs) expressed in Madin- Darby canine kidney (MDCK) strain II epithelial cells. Binding studies with the membrane-impermeable antagonist N-[(3)H]methylscopolamine demonstrated that mAChRs are approximately 2.5 times more abundant on the basolateral than on the apical surface. Apical, but not basolateral, mAChRs inhibited forskolin-stimulated adenylyl cyclase activity in response to the agonist carbachol. Neither apical nor basolateral mAChRs exhibited detectable carbachol-stimulated phospholipase C activity. Carbachol application to the apical or the basolateral membrane resulted in a threefold increase in intracellular Ca(2+) concentration, which was completely inhibited by pertussis toxin on the apical side and partially inhibited on the basolateral side. RT-PCR analysis showed that MDCK cells express the M(4) and M(5) receptor mRNAs. These data suggest that M(4) receptors reside on the apical and basolateral membranes of polarized MDCK strain II cells and that the M(5) receptor may reside in the basolateral membrane of a subset of cells.

Adenosine Triphosphate↗
PubMed1999

Clinical case definition of malaria at a secondary level hospital in northern India.

Malaria has re-emerged as a major public health problem in India. At present, under the National guidelines; all fevers are presumed to be due to malaria and chloroquine is given as presumptive treatment. This results in overtreatment. We did a pilot study to see whether some clinical predictors of malaria could be identified in the Indian setting. This case control study was done in a secondary level hospital. All those with fever who were smear positive for malaria were enrolled as cases and other patients fever who were smear negative for malaria served as the controls. All the factors under study were ascertained by a history or detailed clinical examination. A total of 41 cases and 95 controls were enrolled. Of the 41 cases, 35 were positive for P. vivax and six were positive for P. falciparum. After multivariate analysis, only splenomegaly (OR = 2.11; 95% CI = 1.27-3.50) and pallor (OR = 2.01; 95% CI = 1.16-3.48) were significantly associated with malaria. It appears that history of fever along with one or both of these two signs can be a useful predictor of malaria in a secondary level hospital in India. The utility and feasibility of a similar approach in a field setting needs to be studied further.

Analysis of Variance↗
PubMed1998

Human serum attenuates the activity of protease inhibitors toward wild-type and mutant human immunodeficiency virus.

The potency of therapeutic regimens containing human immunodeficiency virus (HIV) protease inhibitors is related to the ability to maintain concentrations of drug in the plasma of patients that are sufficient for blocking viral replication. The estimation of concentrations required for in vivo activity using in vitro assays is complicated by the fact that extensive binding of many protease inhibitors to serum proteins attenuates their antiviral potency. To provide insight into the relative in vivo potency of current protease inhibitors, we assayed their in vitro activity against wild-type and mutant HIV in the presence of human serum (HS). Using this assay, ABT-378, a new protease inhibitor with trough levels in humans far in excess of the EC50 in the presence of 50% HS, was identified. The antiviral activity of ABT-378 was only modestly attenuated by HS, in contrast to ritonavir, saquinavir, and nelfinavir. Examination of the effect of individual serum components suggested that the activity of ABT-378 is affected predominantly by binding to alpha1-acid glycoprotein (AGP) while the activity of ritonavir is modulated by both AGP and albumin. The method described here may provide insight into the in vivo potency of protease inhibitors and be useful for the preclinical evaluation and selection of new protease inhibitors for clinical studies.

Blood Proteins↗
PubMed1998

The combination of photocatalysis and ozonolysis as a new approach for cleaning 2,4-dichlorophenoxyaceticacid polluted water.

Treatment of 2,4-D polluted waters with photocatalysis leads to the buildup of high concentrations of the long living intermediate 2,4-DCP. A new approach using a combination of ozonolysis and photocatalysis gave better degradation results with lower intermediate concentrations. The advantages of photocatalysis giving a constant decline in TOC and of ozonolysis giving no buildup of high intermediate concentrations were combined. Degradation data of 2,4-D for photocatalysis, ozonolysis and the combination of both for different pH ranges are given. Data on the main intermediate 2,4-DCP are given for the three different approaches.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1998

Failed magnetic resonance imaging examinations due to claustrophobia.

A recognized cause of incomplete or cancelled MRI examinations is anxiety and claustrophobic symptoms in patients undergoing MR scanning. This appears to be a problem in many MRI centres in Western Europe and North America, where it is said to be costly in terms of loss of valuable scan time, and has led to researchers suggesting several anxiety-reducing approaches for MRI. To determine the incidence of failed MRI examination among our patients and if there are any associations with a patient's sex, age and education level, we studied claustrophobia that led to premature termination of the MRI examination in the University Malaya Medical Centre (UMMC) in 3324 patients over 28 months. The incidence of failed MRI examinations due to claustrophobia in the UMMC was found to be only 0.54%. There are associations between claustrophobia in MRI with the patients' sex, age and level of education. The majority of those affected were male patients and young patients in the 25-45-years age group. The patients' education level appears to be the strongest association with failed MRI examinations due to claustrophobia, where the majority of the affected were highly educated individuals. Claustrophobia in MRI is more of a problem among the educated individuals or patients from a higher socio-economic group, which may explain the higher incidence in Western European and North American patients.

Adult↗
PubMed1997

Plant cell biodegradation of a xenobiotic nitrate ester, nitroglycerin.

The ability of plants to metabolize the xenobiotic nitrate ester, glycerol trinitrate (GTN, nitroglycerin), was examined using cultured plant cells and plant cell extracts. Intact cells rapidly degrade GTN with the initial formation of glycerol dinitrate (GDN) and the later formation of glycerol mononitrate (GMN). A material balance analysis of these intermediates indicates little, if any, formation of reduced, conjugated or cell-bound carbonaceous metabolites. Cell extracts were shown to be capable of degrading GTN with the simultaneous formation of GDN in stoichiometric amounts. The intermediates observed, and the timing of their appearance, are consistent with a sequential denitration pathway that has been reported for the microbial degradation of nitrate esters. The degradative activities of plant cells are only tenfold less than those reported for bacterial GTN degradation. These results suggests that plants may serve a direct degradative function for the phytoremediation of sites contaminated by organic nitrate esters.

Biodegradation, Environmental↗
PubMed1997

Human peripheral mononuclear cell responses to UV damage are affected by radiation-induced changes in plasma.

To evaluate the effects of environmental or therapeutic stress adequately, it is important to study cells or tissues under conditions that simulate as closely as possible the in vivo environment. To determine whether the responses of irradiated cells are significantly affected by radiation-induced changes in plasma, human mononuclear cells were isolated from peripheral blood and cultured in their autologous plasma. Freshly isolated cells were irradiated in phosphate-buffered saline. The plasma was irradiated separately. Irradiation of the plasma suppressed mitogen-induced DNA synthesis in unirradiated cells. For cells that were UV-damaged and subsequently stimulated with mitogen, DNA synthesis was enhanced by irradiation of the plasma. Medium in which irradiated cells had previously been incubated enhanced DNA, synthesis in unirradiated cells that had been mitogen stimulated but did not affect the UV-induced shutoff of DNA synthesis in replicating cells or unscheduled DNA synthesis in irradiated cells.

Cell Division↗
PubMed1997

Pharmacokinetic enhancement of inhibitors of the human immunodeficiency virus protease by coadministration with ritonavir.

Coadministration with the human immunodeficiency virus (HIV) protease inhibitor ritonavir was investigated as a method for enhancing the levels of other peptidomimetic HIV protease inhibitors in plasma. In rat and human liver microsomes, ritonavir potently inhibited the cytochrome P450 (CYP)-mediated metabolism of saquinavir, indinavir, nelfinavir, and VX-478. The structural features of ritonavir responsible for CYP binding and inhibition were examined. Coadministration of other protease inhibitors with ritonavir in rats and dogs produced elevated and sustained plasma drug levels 8 to 12 h after a single dose. Drug exposure in rats was elevated by 8- to 46-fold. A > 50-fold enhancement of the concentrations of saquinavir in plasma was observed in humans following a single codose of ritonavir (600 mg) and saquinavir (200 mg). These results indicate that ritonavir can favorably alter the pharmacokinetic profiles of other protease inhibitors. Combination regimens of ritonavir and other protease inhibitors may thus play a role in the treatment of HIV infection. Because of potentially substantial drug level increases, however, such combinations require further investigation to establish safe regimens for clinical use.

Animals↗