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Biomedical subjects

S Datta

Publications and source records attributed to S Datta.

At least 145 records · Page 8Linked to original sources
PubMed1996

Identification and characterization of a generic DNA probe capable of detecting plasmodial infections in blood.

DNA-based detection systems are being rapidly adapted for diagnostic technologies. The currently available non-radioactive DNA techniques for malaria detection are primarily based on probes which are species-specific. The major requirement of a cross-species (generic) diagnostics is the identification of an universal probe which is long enough to be used in either PCR amplification or solid state capture of the hybrids, the two principal techniques currently used in the field of non-radioactive DNA detection. This paper describes a DNA sequence (pARC 178), originally obtained from P. falciparum genomic library, which is also present in other malarial species. Southern-blot analysis indicates that this sequence is derived from a repetitive DNA element. This DNA fragment encodes for a small RNA species of approximately 120 bases. PCR primers based on this sequence amplifies the expected size (157 bp) product from the genomic DNA isolated from P. falciparum, P. vivax, P. berghei, P. yoelii, P. vinckei and P. chabaudi thus confirming its generic nature. The utility of this probe is further demonstrated by its capability in successfully detecting P. falciparum and P. vivax infections in clinical samples when used in a PCR assay.

Animals↗
PubMed1996

Dynamics and equilibrium behavior of cytonuclear disequilibria under genetic drift, mutation, and migration.

A simple two-locus drift model for cytonuclear systems is developed, in which the stochastic dynamics of cytonuclear genotypic frequencies are specified. Random union of zygotes is assumed. Trajectories for the first two moments of both genotypic and allelic disequilibria are given under three scenarios: (i) random drift alone; (ii) random drift with mutation; and (iii) random drift with migration. Steady state solutions for the cytonuclear disequilibria are reported. The utility of this simple two-locus drift model in testing the neutrality of mitochondrial DNA markers in artificial hybrid zones is briefly illustrated

DNA, Mitochondrial↗
PubMed1996

Laparoscopic cholecystectomy during pregnancy. Review of anesthetic management, surgical considerations.

BACKGROUND: We present our experience with laparoscopic cholecystectomy in pregnant patients, with consideration of the physiological changes of pregnancy affecting anesthetic and surgical management. METHODS: We reviewed the medical records of all pregnant patients undergoing laparoscopic surgery at Brigham and Women's Hospital between January 1, 1991 and April 30, 1995. RESULTS: Laparoscopic cholecystectomy was performed without complication in ten patients (gestational age 9-30 weeks). Details of anesthetic and surgical management are described. The anesthetic and surgical implications of pregnancy-associated physiological changes in the gastrointestinal, respiratory, cardiovascular, and central nervous system are reviewed. CONCLUSIONS: With appropriate attention to the altered physiology of pregnancy, laparoscopic cholecystectomy can be performed safely and effectively during pregnancy.

Adult↗
PubMed1996

Hemodynamic effects of intrathecal sufentanil compared with epidural bupivacaine in laboring parturients.

STUDY OBJECTIVES: To provide information on the central hemodynamic effects of intrathecal sufentanil after a standard intravenous preload using thoracic bioimpedance monitoring to obtain noninvasive measurements of cardiac index (CI), stroke index (SI), and systemic vascular resistance (SVR). To compare hemodynamic parameters after intrathecal sufentanil labor analgesia to those after a standard dose of epidural bupivacaine in laboring parturients. DESIGN: Randomized, double-blind study. SETTING: Labor and delivery unit in a university hospital. STUDY DESIGN: 40 ASA status I parturients were randomized into two groups receiving analgesia with combined spinal-epidural technique. Group SUF received 10 micrograms of intrathecal sufentanil followed by 12 ml of saline through an epidural catheter; Group BUP received 2 ml of intrathecal saline followed by 12 ml of 0.25% epidural bupivacaine. Heart rate (HR), blood pressure (BP), and thoracic bioimpedance monitoring were recorded. Pain scores, fetal HR, and side effects were noted. MEASUREMENTS AND MAIN RESULTS: No significant changes from baseline were seen in CI, SI, or SVR index. Mean arterial pressure was lower in Group BUP at 10 and 20 minutes after induction of analgesia. Mean HR was lower in Group SUF at 20 and 30 minutes after induction. Two patients in Group SUF and four patients in Group BUP experienced hypotension requiring ephedrine. Pain scores were lower in Group SUF at 10 minutes after induction of analgesia; subsequent pain scores and duration of analgesia were similar. Fourteen patients in Group SUF experienced itching. CONCLUSIONS: No significant differences in CI, SI, or SVR index were seen after either method of analgesia. A few patients in both groups experienced hypotension requiring treatment with ephedrine. Both techniques of labor analgesia appear to provide effective pain relief but care must be taken with either method to monitor maternal BP.

Adult↗
PubMed1996

Association of epidural analgesia with cesarean delivery in nulliparas.

OBJECTIVE: To evaluate whether epidural analgesia during the first stage of labor is associated with an increased risk of cesarean delivery. METHODS: The association of epidural analgesia and cesarean delivery was examined in a retrospective study of 1733 low-risk, term nulliparas with singleton infants in vertex presentations, in which labor began spontaneously. To evaluate the effect of epidural analgesia on cesarean deliveries, independent of other factors influencing the use of epidural analgesia, we used propensity scores to create five subgroups (quintiles) of women who, based on characteristics discernible at admission, appeared equally likely to receive epidural analgesia. Multivariate logistic regression analysis was used to control for confounding. RESULTS: Overall, the cesarean rate among women receiving epidural analgesia was 17% (168 of 991), compared with 4% (30 of 742) among those who did not receive epidural analgesia. An increased cesarean rate among women receiving epidural analgesia was present in all propensity quintiles. In an adjusted logistic regression analysis, women receiving epidural analgesia were 3.7 times more likely to undergo a cesarean (95% confidence interval 2.4, 5.7). The greatest increase in cesarean risk was noted when epidural analgesia was administered earlier in labor, but there was a more than twofold increase regardless of the dilation and station at administration of epidural analgesia. CONCLUSIONS: Epidural analgesia may increase substantially the risk of cesarean delivery. Although the causal nature of this association remains open to debate, prenatal care providers should routinely discuss the risks and benefits of epidural analgesia with women during their pregnancies so that they can make informed decisions about the use of pain relief during labor.

Adult↗
PubMed1996

A statistical test of a neutral model using the dynamics of cytonuclear disequilibria.

In this paper we use cytonuclear disequilibria to test the neutrality of mtDNA markers. The data considered here involve sample frequencies of cytonuclear genotypes subject to both statistical sampling variation as well as genetic sampling variation. First, we obtain the dynamics of the sample cytonuclear disequilibria assuming random drift alone as the source of genetic sampling variation. Next, we develop a test statistic using cytonuclear disequilibria via the theory of generalized least squares to test the random drift model. The null distribution of the test statistic is shown to be approximately chi-squared using an asymptotic argument as well as computer simulation. Power of the test statistic is investigated under an alternative model with drift and selection. The method is illustrated using data from cage experiments utilizing different cytonuclear genotypes of Drosophila melanogaster. A program for implementing the neutrality test is available upon request.

Animals↗
PubMed1996

Pulmonary function changes during epidural anesthesia for cesarean delivery.

Although changes in pulmonary function in parturients are documented, little is known about effects of regional anesthesia on these changes. This study was undertaken to determine if two local anesthetics, often used for epidural anesthesia for cesarean delivery, have different effects on pulmonary function testing. Nineteen ASA physical status I parturients undergoing elective cesarean delivery with epidural anesthesia were randomly assigned in double-blind fashion to receive either 0.5% bupivacaine or 2% lidocaine with epinephrine (1/200,000). Pulmonary function tests were measured using a calibrated spirometer with computer-recorded flow volume loops. Peak inspiratory pressure and peak inspiratory flow rate, peak expiratory pressure (PEP) and peak expiratory flow rate, forced vital capacity (FVC), and forced expiratory volume in 1 s (FEV1) were measured. Measurements were taken prior to epidural placement and at T-10 and T-4 levels. Peak inspiratory pressure, FEV1/FVC, FEV1, FVC, peak expiratory flow rate, and peak inspiratory flow rate did not differ from baseline in either group. Patients receiving lidocaine showed a significantly greater decrease in PEP at both T-10 and T-4 levels. Pep is largely dependent on abdominal musculature. If a denser motor block is provided by 2% lidocaine with epinephrine than by 0.5% bupivacaine, these muscles would be more affected, resulting in a greater decrease in PEP. These results may have implications regarding choice of local anesthetic for epidural anesthesia in parturients with some degree of respiratory compromise undergoing cesarean delivery.

Adult↗
PubMed1996

The effects of varying volumes of crystalloid administration before cesarean delivery on maternal hemodynamics and colloid osmotic pressure.

The value of intravenous crystalloid administration in preventing spinal-induced hypotension in the parturient has recently been questioned. Also, the association between increasing crystalloid volume and decreasing postpartum colloid osmotic pressure (COP) raises concern regarding the risk of maternal and fetal pulmonary edema. To study the dose-response effect of varying amounts of crystalloid volume prior to spinal anesthesia, we measured maternal hemodynamic variables and maternal and fetal COP in three groups of healthy parturients receiving spinal anesthesia for elective cesarean delivery. Fifty-five parturients were randomized in a double-blind fashion to receive one of 10, 20, or 30 mL/kg of crystalloid volumes prior to induction of spinal anesthesia. Measurements included mean arterial blood pressure (MAP), cardiac index (CI), and systemic vascular resistance index (SVRI) recorded using noninvasive thoracic impedance monitoring until delivery. Maternal and neonatal COP were measured. All groups showed declines in MAP and SVRI from baseline at 5 min after spinal anesthesia, but the amount of decline did not differ among groups. Total ephedrine and additional intravenous (i.v.) fluid administered did not differ among groups. The 20- and 30- mL/kg groups showed a larger decline in maternal COP than the 10-mL/kg group; no differences in neonatal COP were seen with varying preload. We conclude that increasing the amount of i.v. crystalloid administered to 30 mL/kg in the healthy parturient does not significantly alter maternal hemodynamics or ephedrine requirements after spinal anesthesia and has no apparent benefit.

Adult↗
PubMed1996

Observation of a mixed antiparallel and parallel beta-sheet motif in the crystal structure of Boc-Ala-Ile-Aib-OMe.

A diastereomeric mixture of the tripeptide Boc-Ala-Ile-Aib-OMe crystallized in the space group P1 from CH3OH/H2O. The unit cell parameters are a = 10.593(2) A, b = 14.377(3) A, c = 17.872(4) A, alpha = 104.41(2) degrees, beta = 90.55(2) degrees, gamma = 106.91(2) degrees, V = 2512.4 A3, Z = 4. X-Ray crystallographic studies show the presence of four molecules in the asymmetric unit consisting of two pairs of diastereomeric peptides, Boc-L-Ala-L-Ile-Aib-OMe and Boc-L-Ala-D-Ile-Aib-OMe. The four molecules in the asymmetric unit form a rarely found mixed antiparallel and parallel beta-sheet hydrogen bond motif. The Ala and (L,D)-Ile residues in all the four molecules adopt the extended conformations, while the phi, psi values of the Aib residues are in the right-handed helical region. In one of the molecules the Ile sidechain adopts the unusual gauche conformation about the C beta-C gamma bond.

Crystallization↗
PubMed1996

Role of hypo-osmotic sperm swelling test in assisted reproduction.

Hypo-osmotic sperm swelling (HOS) profile is found to be a better predictor of the fertilisability in those husbands possessing subnormal semen parameters. The group where husband's HOS gradings were less than 60%, no one could conceive his fertile wife even after intra-uterine insemination (IUI) for 8 times. However, in the other group where the HOS values were greater than 60%, conception were registered in 6 oligospermic and 2 asthenospermic husbands after 2 to 8 IUI amongst 22 married couples. No conception occurred in any normal coital cycle. All the pregnancies were delivered by elective caesarean section (4 females and 3 males), their birth weights were 2.705 +/- 0.425 kg. One aborted spontaneously at 10 weeks' gestation. The emerging fact in this study is where the HOS values are below 60% the male fertility is reduced, the chances of conception are trivial but fecundity is relatively fair where HOS reading is greater than 60%. It is also a no risk and high benefit method to pick and choose subfertile husbands who are likely to conceive their fertile wives by assisted reproductive techniques.

Adult↗
PubMed1995

A clinical trial of active management of labor.

BACKGROUND: Active management of labor is a multifaceted program that, as implemented at the National Maternity Hospital in Dublin, is associated with a lower rate of cesarean delivery than the rate usually found in the United States. We conducted a randomized trial to evaluate the efficacy of this approach in lowering the rate of cesarean section among women delivering their first babies. METHODS: We randomly assigned 1934 nulliparous women at low risk of complications of pregnancy, before 30 weeks' gestation, to active management of labor or to a usual-care group. The components of active management were customized childbirth classes; strict criteria for the diagnosis of labor; standardized management of labor, including early amniotomy and treatment with high-dose oxytocin; and one-to-one nursing. A low-risk subgroup was defined as including women with full-term, uncomplicated pregnancies who spontaneously went into labor (the protocol-eligible subgroup). Women meeting these criteria who had been randomly assigned to the active-management group were admitted to a separate unit where their labor was managed by trained, certified nurse-midwives. RESULTS: There was no difference between groups in the rate of cesarean section either among all women (active management, 19.5 percent; usual care, 19.4 percent) or in the protocol-eligible subgroup (active management, 10.9 percent; usual care, 11.5 percent). In the protocol-eligible subgroup, the median duration of labor was shortened by 2.7 hours by active management (from 8.9 to 6.2 hours), and the rate of maternal fever was lower (7 percent vs. 11 percent, P = 0.007). The percentage of women in whom labor lasted longer than 12 hours was three times higher in the usual-care group than in the active-management group (26 percent vs. 9 percent, P < 0.001). CONCLUSIONS: Active management of labor did not reduce the rate of cesarean section in nulliparous women but was associated with a somewhat shorter duration of labor and less maternal fever.

Adult↗
PubMed1995

Neuronal activity in the peribrachial area: relationship to behavioral state control.

Extensive studies have ascribed a role to the brainstem cholinergic system in the generation of rapid eye movement (REM) sleep and ponto-geniculo-occipital (PGO) waves. Much of this work stems from systemic and central cholinergic drug administration studies. The brainstem cholinergic system is also implicated in cortical activation via basal forebrain, thalamic, and hypothalamic relay neurons. This cholinergic ascending reticular activating hypothesis has also been suggested by in vivo experiments under anesthetics and by in vitro studies using cholinergic agonists in thalamic and hypothalamic slices. During the last ten years, brainstem cholinergic neurons have been discovered to be in the peribrachial area (PBL). With the discovery of PBL cholinergic neurons, many studies were devoted to the examination of PBL neuronal activity and their connectivity. This article reviews PBL neuronal activity in behaving animals and the anatomical features of these neurons in relation to behavioral state control. The role of the PBL in the generation of REM sleep, PGO waves, and the ascending reticular activating system (ARAS) has been evaluated at the cellular and neurochemical level. Based on recent literature, tentative mechanisms of REM sleep generation, PGO waves generation, and the cortical activation process are also outlined.

Animals↗
PubMed1995

Suppression of ponto-geniculo-occipital waves by neurotoxic lesions of pontine caudo-lateral peribrachial cells.

Ponto-geniculo-occipital waves precede rapid eye movement sleep and play an important role in triggering and maintaining rapid eye movement sleep. Ponto-geniculo-occipital waves have been implicated in several important functions such as sensorimotor integration, learning, cognition, development of the visual system, visual hallucination, and startle response. Peribrachial area neurons have long been thought to play a key role in the triggering of ponto-geniculo-occipital wave. However, the exact location within the peribrachial area for triggering pontine ponto-geniculo-occipital wave has not been unequivocally demonstrated. In an attempt to address this issue, kainic acid was microinjected (1.0 micrograms) unilaterally into the caudo-lateral peribrachial area of four cats in order to destroy the cell bodies located in that region and thus to study the effects of their destruction upon waking-sleep states and ponto-geniculo-occipital waves. The kainic acid produced a small spherical area of nerve cell loss and/or gliosis centered on the stereotaxic coordinates of P: 4.0, L: 4.5, and H: -2.5. The maximum diameter of that spherical area of cell loss was 0.9 mm. Unilateral lesioning of the caudo-lateral peribrachial area decreased ponto-geniculo-occipital waves during rapid eye movement sleep by 85% ipsi-laterally and 15% contralaterally in the lateral geniculate body without significantly changing the amounts of time spent in wake, slow-wave sleep, and rapid eye movement sleep. These results suggest that the caudo-lateral peribrachial area cells are critical to the genesis of ponto-geniculo-occipital waves, and provide compelling evidence that the different parts of the peribrachial area have quite different roles in the generation of discrete rapid eye movement sleep signs. We propose that caudo-lateral peribrachial cells exert an excitatory influence on rostral peribrachial cells, which then directly activate the ponto-geniculo-occipital waves that are recorded in the lateral geniculate body. Results of this study are not only important to understand the mechanisms generating ponto-geniculo-occipital waves but also could be used as an experimental tool to study the functions of this wave.

Animals↗