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Biomedical subjects

S Datta

Publications and source records attributed to S Datta.

At least 91 records · Page 5Linked to original sources
PubMed1999

In vitro fertilization. Do short-term changes in estrogen levels produce increased fibrinolysis?

High estrogen levels have been implicated as a cause of thrombosis. Patients undergoing in vitro fertilization (IVF) present an opportunity to study isolated estrogen effects on the coagulation system, since hormonal manipulation is used to achieve varying estrogen concentrations. We evaluated the effect of estrogen levels on the fibrinolytic and clotting systems of 32 patients undergoing IVF from whom venous samples were obtained during a period of several weeks at baseline and retrieval times. Flow cytometric studies were performed to assay platelet activation. Hemostasis markers measured thrombin-antithrombin complexes (TAT), fibrinogen, plasmin-alpha 2-antiplasmin complexes (PAP), plasminogen activator inhibitor (PAI-1), and D-dimer. A significant decrease in PAI-1 and an increase in PAP were observed at high estrogen levels, suggesting an increase in fibrinolytic potential. However, the products of fibrinolysis, as measured by D-dimer levels, decreased at high estrogen levels. No changes were seen in platelet activation indicators or TAT levels. The fact that a decrease in products of fibrinolysis was seen at high estrogen levels despite concurrent changes in PAI-1 and PAP that normally accompany increased fibrinolysis may be due to alterations in the overall balance of the fibrinolytic system or to a delay in onset of fibrinolysis.

Estradiol↗
PubMed1999

Anesthesia for in vitro fertilization: the addition of fentanyl to 1.5% lidocaine.

UNLABELLED: Ultrasonically guided transvaginal oocyte retrieval is relatively short procedure that is performed on an out-patient basis. The optimal anesthetic technique should allow good surgical anesthesia with minimal side effects, a short recovery time, and, if possible, a high rate of successful pregnancy. Spinal anesthesia is often used in this institution, as well as many others, for this procedure. The addition of fentanyl may be effective for both intraoperative and postoperative pain relief. We assessed the effect of adding fentanyl to 1.5% lidocaine in women undergoing ultrasonically guided oocyte retrieval. Seventy-eight women were randomized to receive 45 mg of hyperbaric 1.5% lidocaine with or without 10 microg of fentanyl. Visual analog scale (VAS) pain scores were lower in the operating room (OR) (P < 0.05) and postanesthesia care unit (PACU) (P < 0.0005) for the group that received fentanyl. In addition, the amount of narcotic required in the PACU was less in the fentanyl group (P < 0.005). There was no difference in VAS scores the evening of or 24 h after the procedure. The amount of analgesics and narcotics required after discharge was the same for both groups. Timed variables, such as time to urination, ambulation, and discharge, were the same for both groups of women. The addition of fentanyl to lidocaine for transvaginal oocyte retrieval results in a more comfortable patient in the OR and PACU. IMPLICATIONS: This study demonstrates that when fentanyl is added to a local anesthetic, lidocaine, with spinal anesthesia for egg retrieval procedures, patients are more comfortable during the procedure compared with those who receive lidocaine alone. In addition, the narcotic requirements of patients are less in the postanesthesia care unit.

Adult↗
PubMed1999

Measurements of maternal protein binding of bupivacaine throughout pregnancy.

UNLABELLED: Pregnancy-related decreases in protein binding may contribute to altered effects of local anesthetics in the parturient. Previous studies have measured protein binding of bupivacaine in term parturients; the current study defines the ratio of bound-to-free bupivacaine throughout gestation at both therapeutic and toxic systemic concentrations of bupivacaine. Venous samples were obtained from 81 women, including 70 parturients, ranging from 7 to 42 wk of gestation and 11 nonpregnant controls. The percent bound bupivacaine at a fixed concentration was determined for each sample at both therapeutic (1 microg/mL) and toxic (5 microg/mL) concentrations using an ultrafiltration technique. Albumin and alpha-1-glycoprotein levels were also measured. Linear regression analysis showed a significant increase in concentration of free bupivacaine throughout gestation at the 5-microg/mL concentration, corresponding to a decrease demonstrated in both albumin and alpha-1-glycoprotein levels. A similar correlation was not found at the 1-microg/mL concentration. Although the relative magnitude of these changes is small, the relative change in free drug throughout gestation is large. Protein binding is only one of several mechanisms that may influence the susceptibility to local anesthetic toxicity in the parturient; however, its relative importance remains unclear. IMPLICATIONS: When venous samples taken from pregnant women were mixed with 5 microg/ml bupivacaine and analyzed, an increase in the free fraction of drug was seen with increasing gestational age, corresponding to decreases in alpha-1-glycoprotein and albumin.

Analysis of Variance↗
PubMed1999

Clinical effects and maternal and fetal plasma concentrations of 0.5% epidural levobupivacaine versus bupivacaine for cesarean delivery.

BACKGROUND: Bupivacaine exists as a mixture of two enantiomers, levobupivacaine and dexbupivacaine. Data suggest that levobupivacaine has equal local anesthetic potency, with reduced potential for central nervous system and cardiovascular toxicity. The present study compares the efficacy of 0.5% levobupivacaine with 0.5% bupivacaine for epidural anesthesia in parturients undergoing elective cesarean delivery. METHODS: Sixty healthy obstetric patients undergoing elective cesarean delivery with epidural anesthesia completed the study. Patients were randomized to receive 30 ml of either 0.5% levobupivacaine or 0.5% bupivacaine in a double-blind fashion. The efficacy endpoint measures included onset, offset, and quality of anesthesia. Neonatal blood gas analyses, Apgar score determinations, and neurobehavioral examinations were performed. Venous samples for pharmacokinetic studies and serial electrocardiograms were obtained in 10 patients in each group. RESULTS: Levels of sensory block, motor block, muscle relaxation, and overall quality of anesthesia did not differ between groups. The frequency of hypotension was 84.4% in the levobupivacaine group and 100% for the bupivacaine group (P < or = 0.053). No significant difference in observed maximum concentration of drug after dosing or area under the plasma drug concentration versus time curve were seen. The maximum concentrations were 1.017 and 1.053 microg/ml, and the areas were 4.082 and 3.765 h(microg/ml) for the levobupivacaine and bupivacaine groups, respectively. Umbilical vein-to-maternal vein ratios were 0.303 for the levobupivacaine group and 0.254 for the bupivacaine group. CONCLUSIONS: The use of epidural 0.5% levobupivacaine for cesarean delivery results in equally efficacious anesthesia compared with 0.5% bupivacaine. Pharmacokinetic parameters were similar in the two groups.

Adult↗
PubMed1999

The influence of the obstetrician in the relationship between epidural analgesia and cesarean section for dystocia.

BACKGROUND: The association between epidural analgesia for labor and the risk of cesarean section for dystocia remains controversial The authors hypothesized that if epidural analgesia were an important factor in determining cesarean section rates, then obstetricians with higher rates of utilization of epidural analgesia for labor would have higher rates of cesarean section for dystocia. METHODS: The frequency of use of epidural analgesia and frequency of occurrence of various patient risk factors for cesarean section were calculated for 110 obstetricians caring for > or = 50 low-risk parturients. These frequencies were compared by linear regression to obstetricians' rates of cesarean section for dystocia. Stepwise regression was used to attempt to predict obstetricians' cesarean rates from the incidence of various patient and provider risk factors. RESULTS: There was no relationship between frequency of epidural analgesia and rate of cesarean section for dystocia across practitioners (R2 = 0.019; P = 0.156). Weighting each obstetrician's data for the number of patients cared for during the study period did not change this result. Stepwise linear regression only modestly predicted obstetricians' cesarean section rates for dystocia, yielding a model containing 12 variables not including epidural analgesia (gestational age, induction of labor, maternal age, provider volume, nulliparity, and seven interactions; adjusted R2 = 0.312; P < 0.0001). CONCLUSIONS: The frequency of use of epidural analgesia does not predict obstetricians' rates of cesarean section for dystocia. After accounting for a number of known patient risk factors, obstetrical practice style appears to be a major determinant of rates of cesarean section.

Adult↗
PubMed1999

Is combined spinal-epidural analgesia associated with more rapid cervical dilation in nulliparous patients when compared with conventional epidural analgesia?

BACKGROUND: The combined spinal-epidural technique provides rapid onset of labor analgesia and, anecdotally, is associated with labors of shorter duration. Epidural analgesia, by contrast, has been suggested to prolong labor modestly. It is unclear, however, whether more rapid cervical dilation in patients who receive combined spinal-epidural analgesia is a physiologic effect of the technique or an artifact of patient selection. The authors hypothesized that anesthetic technique may influence the rate of cervical dilation, and we compared the effects of combined spinalepidural with those of epidural analgesia on the rate of cervical dilation. METHODS: One hundred healthy nulliparous parturients in spontaneous labor with singleton, vertex, full-term fetuses were enrolled in a double-blinded manner when their cervical dilation was less than 5 cm. The patients were randomly assigned to receive analgesia via a standardized combined spinal-epidural (n = 50) or epidural (n = 50) technique. Data were collected on cervical dilation, pain, sensory level, and motor blockade. RESULTS: When regional analgesia was induced in comparable groups at a mean of 3 cm cervical dilation, the mean initial cervical dilation rates were significantly faster in the combined spinal-epidural group (mean values, 2.1 +/- 2.1 cm/h vs. 1 +/- 1 cm/h; P = 0.0008). Five parturients in the combined spinal-epidural group had a very rapid (> 5 cm/h) rate of mean initial cervical dilation, compared with none of the women in the epidural group. Overall mean cervical dilation rates in patients who achieved full cervical dilation were 2.3 +/- 2.6 cm/h and 1.3 +/- 0.71 cm/h (P = 0.0154) in the combined spinal-epidural and epidural groups, respectively. CONCLUSIONS: In healthy nulliparous parturients in early labor, combined spinal-epidural analgesia is associated with more rapid cervical dilation compared with epidural analgesia. Further study is needed to elicit the cause and overall effect of this difference.

Adult↗
PubMed1999

Beta-estradiol acutely potentiates the depression of cardiac excitability by lidocaine and bupivacaine.

Pregnancy is known to increase myocardial susceptibility to bupivacaine-induced cardiovascular collapse, and prolonged pretreatment of rabbits with high doses of progesterone potentiates bupivacaine's depression of the maximal rate of increase (Vmax) of the cardiac action potential. Short-term effects of progesterone are not detected in vitro, but other steroids elevated during pregnancy might be acutely active in this model. These experiments tested whether acute exposure to beta-estradiol potentiates local anesthetic/antiarrhythmic depression of Vmax and conduction velocity in rabbit cardiac tissue in vitro. Standard intracellular microelectrodes were used to measure electrophysiologic changes produced by beta-estradiol, local anesthetics, or both in dissected segments of heart containing the Purkinje fiber and ventricular muscle cells from ovariectomized rabbits. In tissues preincubated in beta-estradiol (3.3 nM), addition of bupivacaine (10.4 microM), or lidocaine (85.4 and 129 microM) decreased Vmax significantly more than in steroid-free Tyrode's (p<0.001). Alone, beta-estradiol had no effect on Vmax and depression of Vmax by the nonanesthetic Na+ channel blocker tetrodotoxin (TTX, 3 microM) was not potentiated by beta-estradiol. In preparations initially exposed to bupivacaine for 30 min, subsequent addition of beta-estradiol decreased Vmax further within 10 min (p<0.05). Bupivacaine's greater depression of Vmax at higher frequencies (3 Hz) was exaggerated by beta-estradiol. However, the rate-dependent slowing of conduction by bupivacaine was lessened or even reversed by beta-estradiol addition. Such rapid physiologic changes cannot be due to genomic actions by the hormone that take hours to manifest. Nor is the potentiation due to a general decrease in membrane excitability because the comparable inhibition by TTX is insensitive to estradiol. Because beta-estradiol potentiates the inhibition of myocardial excitability, but alleviates the slowing of impulse conduction between the Purkinje fiber and ventricular muscle produced by local anesthetics, the hormone must produce changes in more than one ionic conductance. Both pregnancy and conditions that abnormally alter levels of steroid hormones have ramifications for local anesthetic-induced cardiotoxicity and antiarrhythmic pharmacotherapeutics.

Action Potentials↗
PubMed1999

Efficiency of estimating vaccine efficacy for susceptibility and infectiousness: randomization by individual versus household.

In designing vaccine efficacy studies based on the secondary attack rate (SAR) or transmission probability in which both vaccine efficacy for susceptibility, VE(S), and vaccine efficacy for infectiousness, VE(I), are estimated, the allocation of vaccine and placebo within transmission units has an important influence on the efficiency of the study. We compared the following randomization schemes that result in different allocations of vaccine and placebo within two-member households: (1) randomization by individual for a mixed allocation, (2) randomization by transmission unit for concordant allocation, and (3) randomization of only one individual in each transmission unit to either vaccine or placebo. There is a complex interaction among the VE(S), VE(I), and the SAR that determines which allocation of vaccine and placebo within households provides the most information. In general, individual randomization with a mixed allocation of vaccine and placebo is better for estimating both VE(S) and VE(I) than is randomizing by household. However, for estimation of VE(I), at very low SARs and low VE(S), randomization by household is slightly more efficient than randomization by individual.

Biometry↗
PubMed1999

Validating marker-based incidence estimates in repeatedly screened populations.

Disease incidence (new cases of disease per person per year) is usually measured by using longitudinal data. However, several recent proposals for measuring the incidence of human immunodeficiency virus (HIV) rely on cross-sectional data only. These methods assume each person is only sampled once; however, in some instances, it is necessary to consider these cross-sectional methods when individuals are represented more than once in the survey sample. We derive an extension of the cross-sectional incidence estimator that is valid for data from repeatedly screened populations and show under what conditions our new estimator reduces to the old estimator. An example involving estimation of HIV incidence among repeat blood donors is presented.

Biometry↗
PubMed1999

Mechanism-Based Inhibitors: Development of a High Throughput Coupled Enzyme Assay to Screen for Novel Antimalarials.

Identifying potent enzyme inhibitors through a robust HTS assay is currently thought to be the most efficient way of searching for lead molecules. We have developed a HTS assay that mimics a crucial step in an essential metabolic pathway, the purine salvage pathway of the malarial parasite Plasmodium falciparum. In this assay we have used purified recombinant enzymes: hypoxanthine guanine phosphoribosyl transferase (HGPRT) and inosine monophosphate dehydrogenase (IMPDH) from the malarial parasite and the human host, respectively. These two enzymes, which work in tandem, are used to set up a coupled assay that is robust enough to meet the stringent criteria of an HTS assay. In the first phase of our screen we seem to have identified novel inhibitors that kill the parasite by inhibiting the salvage pathway of the parasite.

Journal Article↗
PubMed1999

Cardiovascular effects of yellow oleander ingestion.

Yellow oleander (Thevetia neriifolia) is a commonly grown tree found widely in Eastern India. The seeds of yellow oleander are highly poisonous and contain three glycosides--thevetin, thevetoxin and peruvoside. Yellow oleander seed ingestion is usually with suicidal intent in Eastern India. Manifestations range from mild to potentially fatal. It has significant cardiovascular effects with varying rhythm abnormalities. Effects of yellow oleander seed ingestion (YOI) were studied in 300 patients from 1986 to 1990 at BS Medical College, Bankura. Majority i.e., 246 (82%) were females and 226 (75.33%) were young in the age group 11-20 years. Most reported for treatment 6 to 8 hours after ingestion of seeds. The number of seeds swallowed varied from half to fifteen. Two hundred and ninety-two (97.33%) ingested seeds in the crushed form; 156 (52%) were asymptomatic, 92 (30.66%) had vomiting and 36 (12%) had palpitation. In electrocardiogram (ECG), 138 (46%) revealed varying types of arrhythmias including sinus bradycardia in 68 cases (49.27%). Ischaemic changes were present in 118 cases (39.33%). Number of seeds ingested did not bear any relationship with ECG changes in YOI. All 14 cases of death were autopsied. Subendocardial and perivascular haemorrhage with focal myocardial oedema was present in all. Median hospital stay was 5 days (range 2 to 24). During discharge, 256 (85.33%) had normal ECG, 14 (4.66%) had sinus bradycardia and 16 (5.33%) demonstrated ischaemic changes.

Adolescent↗
PubMed1999

Current concepts in cardiopulmonary resuscitation in adults.

Cardiopulmonary resuscitation (CPR) provides artificial circulation and ventilation during cardiopulmonary arrest. CPR is further categorised as basic life support (BLS), advanced cardiac life support (ACLS) and postresuscitation support. BLS consists of provision of a patent upper airway, ventilation and circulation of blood by closed chest cardiac compressions. ACLS includes use of specialised equipment to maintain the airway, early defibrillation and pharmacologic therapy. Successful outcome from an arrest depends on the total duration of an arrest and early defibrillation, as ventricular fibrillation is the most common cardiac rhythm found in adult cardiac arrest. Initial drug therapy during CPR aims at correction of arterial hypoxaemia and restoring coronary and cerebral perfusion. Oxygen and epinephrine constitute the mainstay of drug therapy during CPR. In patients with ventricular tachycardia, lidocaine is the drug of choice, followed by bretylium. Magnesium has proved to be useful in both refractory pulseless ventricular tachycardia and fibrillation. Atropine has not been demonstrated to improve outcome from arrest but can be administered in bradyasystolic cardiac arrest. The routine administration of bicarbonate and calcium is no longer recommended but situations exist where they can be used appropriately. Administration of drugs during CPR should preferably be via a central route, but epinephrine, lidocaine and atropine can be administered via the endotracheal tube if intravenous access has not been established. Postresuscitation care includes mechanical ventilation if necessary to optimise oxygenation and ventilation and steps to maintain vital organ and optimal brain protection, which includes avoidance of hypertension, hypotension and hyperglycaemia.

Adult↗
PubMed1999

Role of closed mitral commissurotomy for mitral restenosis.

Out of 1184 consecutive cases of rheumatic mitral stenosis treated surgically by closed mitral commissurotomy (CMC) at NRS Medical College and Hospital, Calcutta, 20 (1.68%) were mitral valve restenosis. Twelve cases (60%) were females, The median age was 32 years. Duration between the first operation and reappearance of symptoms varied with a mean of 8 years. The previous operations were digital dilatation and instrumental dilatation in 6 and 14 cases respectively. History of thromboembolism was present in 4 cases. On echocardiography, calcification of the mitral valve was present in 2 cases, left atrial clot in 4 cases, associated mild to moderate mitral regurgitation in 6 cases and mild aortic regurgitation in 4 cases. All cases presented with New York Heart Association (NYHA) III and IV symptoms. Critical stenosis (mitral valve orifice less than 0.5 cm2) was present in 12 cases. Re-do CMC was undertaken in all cases with Tubb's dilator. Median operating time was 2.5 hours. Satisfactory split was achieved in 13 cases. One patient died during surgery. Four cases having less than satisfactory split were asymptomatic on follow-up. In one case no split was possible and in another, gross mitral regurgitation was noted postoperatively. These 2 cases had to undergo open heart surgery. It is concluded that re-do CMC is a feasible and suitable alternative in mitral restenosis even in the presence of complications.

Adult↗
PubMed1999

Brainstem afferents of the cholinoceptive pontine wave generation sites in the rat.

The present study was designed to investigate the distribution of brainstem neurons projecting to the pontine wave (P-wave)-generating sites in the rat. In six rats, biotinylated dextran amine (BDA) was microinjected into the physiologically identified cholinoceptive P-wave generation site. In all cases, microinjections of BDA in the cholinoceptive P-wave generating site resulted in retrograde labeling of cell bodies in many parts of the brainstem. The majority of those retrogradely labeled cells were in the pedunculopontine tegmentum, pontine reticular nucleus oralis, parabrachial nucleus, vestibular nucleus, and gigantocellular reticular nucleus. The results presented in this study provide anatomical evidence that the cholinoceptive P-wave generation site in the rat receives anatomical projections from other parts of the brainstem known to be involved in the REM sleep-generation mechanism.

Afferent Pathways↗
PubMed1999

Influence of cadmium intoxication on hepatic lipid peroxidation, glutathione level, and glutathione S-transferase and gamma-glutamyl transpeptidase activities: correlation with chromosome aberrations in bone marrow cells.

We examined whether there was any correlation between chromosome aberrations (CAs) in bone marrow cells with hepatic lipid peroxidation (LPO), reduced glutathione (GSH) level, glutathione S-transferase (GST), and gamma-glutamyl transpeptidase (GGT) activity after cadmium (Cd) intoxication in both a dose- and a time-dependent manner. Cadmium chloride was administered subcutaneously in doses of 0.5, 1.5, 2.5, and 5.0 mg/kg body weight to Swiss albino Balb/c male mice. The animals were exposed for 8, 16, and 24 days, i.e., 4, 8, and 12 doses, respectively. Biochemical parameters were measured in hepatic tissue for a correlation with chromosome aberrations in bone marrow. With the increment of dose and advancement of time points, the biochemical, as well as the cytogenetic, parameters altered significantly. Hepatic lipid peroxidation and GGT activity increased significantly along with an increased percentage of chromosome aberrations in the bone marrow, but the hepatic reduced glutathione level and GST activity were found to decrease following Cd administration. Up to 5.0 mg Cd/kg body weight, lipid peroxidation did not exhibit threshold levels of toxicity as shown by the two-way (fixed effect) analysis of variance test. In contrast, the observed values of reduced glutathione levels, GST and GGT activity, and chromosome aberrations in bone marrow showed threshold activity levels. Therefore, there might be a relationship between an increase in the frequency of chromosome aberrations, elevated lipid peroxidation, and depleted glutathione levels and GST and GGT activity. The clastogenic efficacy of Cd may be mediated through the biochemical pathways.

Animals↗