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Biomedical subjects

K C Patel

Publications and source records attributed to K C Patel.

At least 19 recordsLinked to original sources
PubMed2000

Stimulation of Na/Ca exchange by the beta-adrenergic/protein kinase A pathway in guinea-pig ventricular myocytes at 37 degrees C.

We investigated the effect of beta-adrenergic stimulation on Na/Ca exchange in whole-cell patch-clamped guinea-pig ventricular myocytes at 37 degrees C. With ion channel and Na/K pump currents blocked, the Na/Ca exchange current (I(Na-Ca) was measured selectively as membrane current inhibited by 10 mM nickel (Ni) during a voltage ramp applied between +80 and -120 mV. Isoprenaline (1 microM) caused an increase in both inward and outward current generated by the Na/Ca exchange, which was prevented by the beta-adrenoceptor blocker propranolol. These data suggest that isoprenaline caused a receptor-mediated up-regulation of Na/Ca exchange activity. Mimicking beta-adrenoceptor activation, either by stimulation of adenylate cyclase with forskolin or by internal dialysis of cells with cyclic AMP (3':5'-cyclic adenosine monophosphate), also increased I(Na-Ca). Using fluorescence Ca measurement, an increase of internal cAMP was shown to increase the rate of transmembrane Ca transport via the Na/Ca exchange. A selective inhibitor of protein kinase A prevented stimulation of Na/Ca exchange by isoprenaline. These data suggest that the underlying mechanism of stimulation was phosphorylation of the Na/Ca exchange protein by protein kinase A. Isoprenaline did not stimulate I(Na-Ca) when experiments were carried out at 20 degrees C, in contrast to the findings at 37 degrees C. Modulation of Na/Ca exchange by the beta-adrenergic pathway may have important physiological consequences for intracellular Ca regulation and electrical activity during hormonal stimulation, or during sympathetic nerve stimulation.

Adenylyl Cyclases↗
PubMed1998

Methods for providing probe position and temperature information on MR images during interventional procedures.

Interventional magnetic resonance imaging (MRI) can be defined as the use of MR images for guiding and monitoring interventional procedures (e.g., biopsy, drainage) or minimally invasive therapy (e.g., thermal ablation). This work describes the development of a prototype graphical user interface and the appropriate software methods to accurately overlay a representation of a rigid interventional device [e.g., biopsy needle, radio-frequency (RF) probe] onto an MR image given only the probe's spatial position and orientation as determined from a three-dimensional (3-D) localizer used for interactive scan plane definition. This permits 1) "virtual tip tracking," where the probe tip location is displayed on the image without the use of separate receiver coils or a "road map" image data set, and, 2) "extending" the probe to predict its path if it were directly moved forward toward the target tissue. Further, this paper describes the design and implementation of a method to facilitate the monitoring of thermal ablation procedures by displaying and overlaying temperature maps from temperature sensitive MR acquisitions. These methods provide rapid graphical updates of probe position and temperature changes to aid the physician during the actual interventional MRI procedures without altering the usual operation of the MR imager.

Animals↗
PubMed1991

Ribavirin in acute viral hepatitis.

Sixty-four patients suffering from acute viral hepatitis (excluding those suffering from hepatitis B) were selected for the double blind clinical trial. They were randomly allocated to either ribavirin therapy (200 mg four times a day) or placebo. Four patients were lost to follow up and therefore final analysis was carried out on 60 patients (thirty had received ribavirin and the rest placebo). Patients receiving ribavirin showed significant rapid improvement, with the disappearance of annoying symptoms (e.g., nausea, vomiting, etc) and return of good appetite; moreover, the abnormal blood parameters showed significant rapid changes towards normal values in ribavirin treated patients as compared to those observed in placebo group. Ribavirin was well tolerated and there were no side effects. Since acute viral hepatitis is endemic with outbreaks of epidemics in many areas at various times and as yet there is no effective anti-viral drug available with the physicians in India, ribavirin is indeed a most welcome drug for its therapy.

Double-Blind Method↗
PubMed1989

Modified sham feeding and Congo red test in determining completeness of vagotomy.

Gastric acid response to modified sham feeding was evaluated in 14 patients with duodenal ulcer prior to vagotomy and in 18 patients after vagotomy. Nine patients in the latter group had recurrent ulcer, suggesting inadequate vagotomy. Based on values in the 32 tests (14 pre and 18 postoperative), cut-off levels of six secretory indices were selected to provide a specificity of 1.00 for the presence of ulcer. When applied separately to the 18 postoperative patients and to the 13 patients who underwent the endoscopic congo red test, observed volume of 75 ml/h and peak volume of 90 ml/h following sham feeding gave specificity, sensitivity and efficiency of 1.00 each in determining inadequate vagotomy. The endoscopic congo red test done in 13 post-vagotomy cases showed a sensitivity of 1.00, and high specificity (0.89) and efficiency (0.92). Measurement of crude gastric juice response to modified sham feeding is a convenient bedside test to confirm inadequate vagotomy. The endoscopic congo red test is also useful, especially as a screening test, and has the added advantage that it can be used intra-operatively.

Adult↗
PubMed1984

Plasma exchange.

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Collagen Diseases↗
PubMed1981

Transcutaneous PO2 monitoring during pediatric surgery.

The value of continuous transcutaneous oxygen (PtcO2) monitoring in the presence of halothane and nitrous oxide (N2O) was studied in 10 infants. All infants were continuously monitored during the study with a Clark-type skin electrode with Mylar membrane. The polarization voltage of the membrane was changed to 600 mV to make it insensitive to N2O and halothane. The accuracy of PtcO2 electrode was compared with simultaneously measured PaO2 at different intervals. Correlation of PaO2 with PtcO2 was sought during hypoxic-normoxic state (PaO2 between 27--92 torr) and hyperoxic state (PaO2 between 105--439 torr). During hypoxic-normoxic state, the correlation between PaO2 and PtcO2 values was 0.94. During the hyperoxic state, poor correlation existed between PaO2 and PtcO2 (r = 0.51). Although PtcO2 did not correlate with PaO2 during hyperoxia, it consistently overestimated PaO2 and thereby, provided a predictive ability by over-diagnosing hyperoxia. When combined with continuous monitoring of inspired oxygen tension to maintain normoxia, continuous monitoring of PtcO2 will reduce the frequency of PaO2 analysis and improve patient care during anesthesia.

Anesthesia, Inhalation↗