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Biomedical subjects

K Tewari

Publications and source records attributed to K Tewari.

14 recordsLinked to original sources
PubMed1996

Studies on the effects of monosodium glutamate (MSG) on oxidative stress in erythrocytes of adult male mice.

Subcutaneous administration of monosodium glutamate (MSG) to normal adult male mice for 6 days at dose levels of 4 and 8 mg/g body weight caused a significant increase in erythrocyte glucose content accompanied by increased lipid peroxidation. The levels of total glutathione and protein-bound glutathione were significantly increased in the erythrocytes, whereas non-protein glutathione was significantly decreased. The administration of 4 and 8 mg/g body weight of MSG significantly increased the activities of glutathione reductase (GR), glutathione-S-transferase (GST) and glutathione peroxidase (GPX). It was observed that MSG, above 4 mg/g body weight, produced oxidative stress which was counteracted by the body by maintaining the level of glutathione, which was done by increasing the activity of its metabolizing enzymes.

Animals↗
PubMed1995

Acetyl-L-carnitine arginyl amide (ST857) increases calcium channel density in rat pheochromocytoma (PC12) cells.

We used the patch clamp technique to study the effect of acetyl-L-carnitine arginyl amide (ALCAA) and of nerve growth factor (NGF) on availability of L-type Ca2+ channels in rat pheochromocytoma (PC12) cells maintained in defined medium. Channel availability was measured as number of channels in the patch x the probability of opening (n.Po). In patches from control cells, cells exposed to NGF (10 ng/ml) for six days, and cells exposed to ALCAA (1 mM) for six days, n.Po, measured during 200-240 ms pulses to -10 mV (holding potential, -60 mV), was 0.102 +/- 0.089 (5 cells), 0.173 +/- 0.083 (5 cells), and 0.443 +/- 0.261 (7 cells), respectively. The 4.3-fold increase for the ALCAA-treated cells was significantly different from control (P < 0.05), whereas that for the NGF-treated cells was not. For the same conditions, the maximum number of superimposed openings at -10 mV was 1.3 +/- 0.5 (6 cells), 1.6 +/- 0.5 (8 cells), and 3.3 +/- 1.8 (8 cells), with the value for the ALCAA-treated cells being significantly different from control (P < 0.001). Additional analysis showed that the distribution of channel open times, the time constants, and the voltage dependence of activation were not changed by prolonged exposure to ALCAA. Short-term exposure to both ALCAA as well as to the parent compound, acetyl-L-carnitine (ALCAR), did not cause an increase but rather a decrease in n.Po, and this short-term effect of both compounds was blocked by neomycin, an inhibitor of phospholipase C.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Does perioperative blood transfusion affect survival in patients with cervical cancer treated with radical hysterectomy?

OBJECTIVE: To determine if blood transfusions during or after radical hysterectomy adversely affect survival in patients with invasive cervical carcinoma. METHODS: Two hundred eighty-three women with stage IA2-IIA cervical cancer were treated with radical hysterectomy and pelvic lymphadenectomy from 1980-1989. Thirteen were lost to follow-up, and five others received adjuvant chemotherapy. Among the remaining 265 patients, 131 were given blood transfusions during surgery or within 30 days, whereas 134 were not. The clinical and pathologic characteristics of these two groups were reviewed and analyzed statistically. RESULTS: Transfused and nontransfused patients did not differ with respect to mean age (45.0 versus 43.4 years, respectively), stage, grade, cell type, depth of invasion, or prevalence of nodal metastasis. Transfused patients more frequently received adjuvant pelvic irradiation than did nontransfused (47 versus 33%, respectively, chi 2 P < .05). After a mean follow-up of 51 months (range 13-125), 19 women (14%) in each group were diagnosed as having recurrent disease, predominantly in the pelvis. Using life-table analysis, the calculated 5-year survival was 86% for transfused and 84% for nontransfused patients, a nonsignificant difference. Disease-free survival was also similar. In the study population, grade, depth of invasion, and nodal status predicted survival. When patients were stratified according to age, cell type, stage, depth of invasion, nodal involvement, and use of adjuvant radiation, blood transfusion still did not adversely influence survival. Using the Cox proportional hazards model, only nodal status was an independent predictor of death. CONCLUSION: Perioperative blood transfusion does not impact overall survival or time to recurrence after radical hysterectomy.

Adult↗
PubMed1995

The patch clamp technique.

The introduction of the patch clamp technique less than two decades ago revolutionized the study of cellular physiology by providing a high-resolution method of observing the function of individual ionic channels in a variety of normal and pathological cell types. By the use of variations of the basic recording methodology, cellular function and regulation can be studied at a molecular level by observing currents through individual ionic channels. At a cellular level, processes such as signaling, secretion, and synaptic transmission can be examined. In addition, by combining the information from high-resolution electrophysiological recordings obtained by the patch clamp method with modern molecular biological techniques, further insight can be gained into the gene expression and protein structure of ionic channels. Given the ubiquity and importance of ionic channels, it is not surprising that their study has led to a new understanding of the mechanisms of certain disease processes and has given insight into treatments for these diseases. This review gives an historical perspective of the development of the patch clamp technique and an overview of the methodologies currently in use. Examples are shown to illustrate typical uses of the patch clamp technique with emphasis on the variety of recording configurations available and the advantages and drawbacks of each method.

Animals↗
PubMed1994

Open interstitial brachytherapy for the treatment of local-regional recurrences of uterine corpus and cervix cancer after primary surgery.

Patients who develop locally recurrent uterine corpus or uterine cervix cancer after primary surgery are usually treated with radiotherapy. The optimal radiotherapeutic approach, however, has not been defined. We report the use of exploratory laparotomy, omental pedicle grafting, and intraoperative transperineal interstitial brachytherapy in the treatment of 28 such patients (10 with recurrent corpus and 18 with recurrent cervix cancer). In addition, 22 patients also received perioperative whole pelvic teletherapy while 21 also received a second closed interstitial application. Local control was achieved in 20 patients (71%), but only 10 (36%) continue to be alive without disease after a median of 44 months. Eighteen patients have died (17 of disease) a median of 13 months after open implant. Patients treated with a single implant (n = 7), with side wall involvement (n = 5), with tumors greater than 6 cm in size (n = 4), with a history of previous pelvic irradiation (n = 8), or with persistent disease after open interstitial therapy (n = 8), were not salvaged. Ten patients suffered acute morbidity which included deep venous thrombosis (n = 1), wound separation (n = 1), urinary infection (n = 2), wound infection (n = 2), pneumonia (n = 1), and fever (n = 3). Two other patients experienced chronic non-tumor-related comorbidities. These included a vesicovaginal fistula with a rectovaginal fistula in 1 patient and a small bowel obstruction with a ureteral stricture in another. A single individual suffered from both acute and chronic complications (fever, ureterointestinal fistula).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Protein kinase A increases availability of calcium channels in smooth muscle cells from guinea pig basilar artery.

We studied single Ca2+ channels in smooth muscle cells from the basilar artery of the guinea pig using conventional patch-clamp techniques. With 40 mM or 90 mM Ba2+ as the charge carrier, a 23-pS inward current channel was observed in 46/187 cell-attached patches studied without the dihydropyridine, BAY K8644, in the pipette solution. At 0 mV, this channel exhibited short and long openings with time constants of 1.03 and 3.65 ms, respectively. The probability of channel opening was voltage dependent with half-activation occurring at +9.9 mV. In 14/26 patches tested, addition of 8-bromo-cyclic adenosine monophosphate (8-Br-cAMP) to the bath increased the probability of opening at -10 mV by a factor of 2.6, from 0.0272 +/- 0.0429 to 0.0695 +/- 0.0788 (P < 0.01, paired t-test). Mean data from five patches fit to a Boltzmann function indicated that at positive potentials, the probability of opening increased by a factor of 1.7, from 0.352 to 0.600, whereas the voltage dependence, the number of channels, the number of open states, the time constants of the open states, and the proportion of time spent in each open state were unchanged. When BAY K8644 was added to the pipette solution, the 23-pS channel was observed in nearly all patches (62/66), but the voltage dependence of activation was shifted -15.3 mV compared to control. In some patches studied with 90 mM Ba2+, a 9-pS inward current channel also was observed and its activity also was increased significantly by 8-Br-cAMP.(ABSTRACT TRUNCATED AT 250 WORDS)

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1994

Calcium channels in smooth muscle cells from cerebral precapillary arterioles activate at more negative potentials than those from basilar artery.

We compared Ca2+ channels in cell-attached patches of smooth muscle cells from cerebral precapillary arterioles and basilar artery of guinea pig. Patches were studied without Ca2+ channel activators in the pipette solution. In both preparations, a 23 pS channel (40 mM Ba2+) sensitive to block by nifedipine was identified. In arteriolar but not in basilar artery patches, channel activity was recorded without apparent inactivation at potentials of -40 to -20 mV. Values for the number of channels in a patch x probability of channel opening (n.Po) at various potentials were fit to a Boltzmann function. For the arteriolar patches (n = 5) and for patches from basilar artery (n = 5), the midpoint potentials for the voltage dependence of n.Po were -9.3 mV and +8.9 mV, and maximum values of n.Po at positive potentials were 1.23 and 0.33. At potentials > or = 0 mV, the average for the maximum number of superimposed openings in basilar artery patches was 1.7 (n = 17) and in arteriolar patches was 6.5 (n = 6). For both preparations, histograms of channel open times at -10 mV required two time constants, 0.48 and 3.95 ms, and the shorter open state accounted for 88% of openings. Our data indicate that Ca2+ channel activity is likely to be more prominent near resting membrane potentials in arteriolar cells than in basilar artery cells.

Animals↗
PubMed1994

Zinc levels in maternal and cord blood and in amniotic fluid--a possible marker for foetal malformation.

Zinc levels were estimated from the maternal and cord blood drawn at delivery and in the amniotic fluid drawn before delivery in 9 pregnancies resulting in congenitally abnormal foetuses and 21 pregnancies resulting in normal healthy babies. Zinc levels were significantly lower (P < 0.01) in maternal and cord blood serum in congenitally malformed babies as compared to healthy normal controls. Amniotic fluid zinc levels were significantly higher (P < 0.01) in pregnancies with malformed babies. The use of zinc levels as marker for foetal malformation has been suggested.

Amniotic Fluid↗
PubMed1993

Ionic channel currents in cultured neurons from human cortex.

Ionic channels in human cortical neurons have not been studied extensively. HCN-1 and HCN-1A cells, which recently were established as continuous cultures from human cortical tissue, have been shown by histochemical and immunochemical methods to exhibit a neuronal phenotype, but expression of functional ionic channels was not demonstrated. For the present study, HCN-1 and HCN-1A cells were cultured in Dulbecco's modified Eagle's medium with 15% fetal calf serum, in some cases supplemented with 10 ng/ml nerve growth factor, 10 microM forskolin, and 1 mM dibutyryl cyclic adenosine monophosphate to promote differentiation. Cells or membrane patches were voltage clamped using conventional patch clamp techniques. In HCN-1A cells, we identified a tetrodotoxin-sensitive Na+ current, two types of Ca2+ channel current, including L-type current and a second type that in some respects resembled N-type current, and four types of K+ current, including a delayed outward rectifier that showed voltage-dependent inactivation, two types of noninactivating Ca(2+)-activated K+ channels with slope conductances of 146 and 23 pS (K+i/K+o 145 mM/5 mM), and less frequently, a noninactivating, intermediate conductance channel that was not sensitive to internal Ca2+. When HCN-1A cells were examined after 3 days of exposure to differentiating agents, pronounced morphological changes were evident but no differences in ionic currents were apparent. HCN-1 cells also exhibited K+ and Ca2+ channel currents, but Na+ currents were not detected in these cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium Channels↗
PubMed1984

C3 polymorphism in North India.

C3 polymorphism has been studied in 428 individuals from four populations of North India. The frequency of the C3F gene ranges between 0.086 to 0.139. The C3F gene frequency is comparatively higher in the studied samples as compared to other Indian populations, but lower than in most European and West Asian populations.

Complement C3↗