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Biomedical subjects

S Datta

Publications and source records attributed to S Datta.

At least 217 records · Page 12Linked to original sources
PubMed1992

l(1)trol and l(1)devl, loci affecting the development of the adult central nervous system in Drosophila melanogaster.

Adult optic lobes of Drosophila melanogaster are composed of neurons specific to the adult which develop postembryonically. The structure of the optic lobes and aspects of its development have been described, and a number of mutants that affect its development have been identified. The focus of every screen to date has been on disruption of adult structure or function. Although these loci were originally identified on the basis of viable mutants, some have proven capable of giving rise to lethal alleles. It seems reasonable to assume that mutants which strongly affect development of the imaginal-specific central nervous system may evidence abnormalities during the late larval or pupal stages when the adult central nervous system is undergoing final assembly and might show a lethal phase prior to eclosion (as is true for mutations at the previously defined l(1)ogre locus). We have carried out the first screen of autosomal and sex-linked late larval and pupal lethals to identify mutations that affect the development of the optic lobes. Our screen yielded nine mutants that could tentatively be grouped into three classes, depending on the neuroblast population affected and imaginal disc phenotypes. Two of these, including one that is allelic to l(1)zw1, were chosen for further analysis.

Animals↗
PubMed1992

Does epidural administration of butorphanol offer any clinical advantage over the intravenous route? A double-blind, placebo-controlled trial.

The differential effects of intravenous versus epidural administration of short-acting, lipid-soluble opioids is controversial. This study was undertaken to compare these two routes of administration using the mixed agonist-antagonist opioid, butorphanol. Forty-five women undergoing elective cesarean delivery at term under epidural lidocaine anesthesia were randomized to receive a single bolus of either epidural or intravenous butorphanol 2 mg or saline control for postoperative analgesia. At precisely 60 min after the last dose of epidural local anesthetic, all patients received a simultaneous epidural and intravenous injection in a randomized, double-blinded fashion. The intravenous group received butorphanol intravenous and saline epidurally; the epidural group received saline intravenous and butorphanol epidurally; and a control group received saline via both routes. When additional analgesia was requested, all patients received patient-controlled analgesia (PCA) with intravenous morphine (2-mg demand dose, 7-min lockout interval). Analgesia was quantitated using a visual analogue scale and subsequent PCA morphine requirements. The interval from study drug injection until first request for PCA use was equivalent for the intravenous and epidural groups (89 +/- 9 and 83 +/- 8 min, respectively) and significantly longer than in control group (39 +/- 4 min, P less than 0.001, intravenous and epidural vs. control). Analgesia was equivalent in the intravenous and epidural groups at all observation points, and pain scores were significantly lower than control for the first 120 min after study drug injection.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Effects of progesterone on the cardiac electrophysiologic action of bupivacaine and lidocaine.

Pregnancy is accompanied by an increased cardiac and neural sensitivity to some local anesthetic agents such as bupivacaine. The current study was initiated to investigate the relationship between increased progesterone concentrations and the electrophysiologic effects of bupivacaine, and lidocaine in isolated Purkinje fiber (PF)-ventricular muscle (VM) preparations. Twenty-four oophorectomized female white rabbits were killed after receiving 30 mg.kg-1.day-1 of progesterone intramuscularly or peanut oil alone for 4 days. PF and VM action potentials were recorded using standard electrophysiologic procedures. Plasma progesterone concentrations were 5 +/- 2.9 ng/ml in control animals compared to 59.8 +/- 11.0 ng/ml in progesterone-treated animals (P less than 0.05). Bupivacaine (3.5-17.4 microM) depressed the maximal rate of depolarization (Vmax) of PF to a significantly greater extent in tissues from progesterone-treated animals as compared to control animals. For example, at 3.5 microM bupivacaine decreased PF Vmax 52% in progesterone-treated tissues compared to 32% in controls (P less than 0.05); the Vmax of VM was also depressed to a greater extent in tissues from progesterone-treated animals (P less than 0.001). Lidocaine did not demonstrate an enhanced depressant effect in tissues from progesterone-treated animals. These results indicate that progesterone selectively increases the cardiac membrane depressant effects of bupivacaine but not lidocaine. This may contribute to the enhanced toxicity of bupivacaine in pregnant animals.

Action Potentials↗
PubMed1992

A comparison of intrathecal, epidural, and intravenous sufentanil for labor analgesia.

A number of recent studies have suggested that the analgesic effects of highly lipid-soluble opioids are similar when these agents are administered either epidurally or intravenously. We sought to test whether the lipid-soluble opioid sufentanil was more effective when administered intrathecally than when administered epidurally or intravenously. Twenty-four women during active labor received sufentanil 10 micrograms either intrathecally (n = 9), epidurally (n = 8), or intravenously (n = 7), using a combined spinal-epidural technique. The sufentanil was administered alone, without concomitant local anesthetics. Analgesia was assessed using the visual analogue score as well as the time elapsed from the administration of study drug to the patient's request for additional analgesia via the epidural catheter (bupivacaine 0.25%). The median duration of analgesia (median, interquartile range) was 84 (70-92) min in the intrathecal group, 30 (23-32) min in the epidural group, and 34 (17-30) min in the intravenous group (P < 0.001). The intrathecal group showed rapid and significant decrease in visual analogue scale scores, whereas visual analogue scale scores in the other two groups did not decrease and remained significantly elevated compared to those of the intrathecal group at all observation points. Side effects were limited to pruritus in 3 patients (2 moderate and 1 severe) in the intrathecal group. No patient developed post-dural puncture headache. We conclude that sufentanil 10 micrograms intrathecally provides rapid and effective analgesia of 1-2-h duration during labor. Epidural and intravenous use of this dose of sufentanil did not provide evidence of satisfactory analgesia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Thyroid hormone receptor mediates transcriptional activation and repression of different promoters in vitro.

The thyroid hormone receptor (TR) has the dual ability to activate or repress transcription of specific genes. A cell-free transcription system was used to study the effects of TR on transcription by positively (TREpMLP) and negatively (TSH alpha) regulated promoters. Receptor-deficient HeLa cell extracts were complemented with baculovirus-produced TR. TR stimulated transcription from the TREpMLP promoter by 3-fold, and trans-activation did not require hormone. Transcriptional stimulation by TR required the presence of the TRE sequence and was diminished by the addition of competitor TRE binding sites. Baculovirus-produced TR repressed transcription in vitro from the TSH alpha promoter by 30-50%, also in a hormone-independent manner. Transcription from a control adenovirus 2 major late promoter was unaffected by added TR. Receptor-specific antisera and competition with TRE binding sites impaired TR-mediated repression of the TSH alpha promoter. Unlike transcriptional stimulation, which was optimal when TR and HeLa extracts were added concomitantly, transcriptional repression by the TR was most effective when the receptor was preincubated with the alpha-promoter, suggesting that receptor binding to the promoter may block access of other proteins to cause transcriptional repression. These results indicate that baculovirus-expressed TR mediates transcriptional activation and repression in a promoter-specific manner in vitro. This system provides a valuable model for examining transcriptional control by the TR.

Baculoviridae↗
PubMed1992

Demographic survey of opinions towards smoking: a pilot study.

A survey was conducted by means of a questionnaire, on 865 smokers to analyse their opinions towards some general aspects of smoking. The subjects were mostly males (97.11%) and belonged to the age group of 21 to 50 years (80%). Heavy smoking is injurious to health is the opinion of most of the smokers (90.41%) particularly when maintained with other addictions (80%); tobacco is harmful not only when smoked but also when used in other forms (63%) and moderate smoking may not be much harmful (43%). However, smoking is not necessary to make or maintain relations with others (70%). Statutory warning has no marked effect on the habit (69.83%), the role of legal restrictions is dubious but advertisements encourage the habit definitely (62.54%). Three out of 4 persons know the problems of smoking and almost the same proportion of the people think that smoking can be stopped or at least checked. But there is difference of opinion about the person to be consulted, if any such problems arises from the habit of smoking. Family physicians may play an important role in controlling the habit.

Adolescent↗
PubMed1992

The natural history of smoking.

This study is a small collection of the natural history of smoking of 865 persons - all smokers and majority (97.11%) of them were males, more than 80% were between 21-50 years, most (90%) were Hindus and 75% were service holders. It revealed that most of the subjects started smoking between 10 and 25 years of age, frequently being requested by their friends but felt nothing mentionable at their first experience. Most of them (64%) were smoking for more than 10 years, 48.56% were smoking more than 10 cigarettes in a day, filter-tipped more often (by 64% subjects) and without any history of break by 56% subjects. Majority (80%) used to inhale the smoke and 40% had no specific time of choice. Most of the subjects (80%) like to smoke in deep thoughts, 66% during excitement, 60% when depressed, 82% when relaxed and 62.5% when alone. But most of them (64%) did not smoke when busy. Majority (70.87%) felt relaxed when smoking. Most of the people (45%) stood reasonable having no cigarette in their stock. Majority (84%) used to smoke even when not offered. Tobacco was consumed largely as smoke by 75% subjects; 78% subjects smoked only cigarettes and about half of the smokers smoked even when they did not enjoy it.

Adult↗
PubMed1992

Cholinergic microstimulation of the peribrachial nucleus in the cat. I. Immediate and prolonged increases in ponto-geniculo-occipital waves.

The cholinergic agonist carbachol was injected into the pontine Pb area where PGO bursting cells have been recorded. When microinjections were localized to the ventrolateral aspect of the caudal Pb nucleus near aggregates of ChAT immunolabeled cholinergic neurons, carbachol produced an immediate onset of state-independent PGO waves in the ipsilateral LGB. These state-independent PGO waves persisted for 3-4 days. After the first 24 hrs PGO wave activity increasingly became associated with REM sleep and with REM transitional SP sleep as both of these PGO-related states increased in amount to 3-4 times baseline levels. The increase in amount of PGO-related states peaked on days 2-4 following one carbachol injection and persisted for 10-12 days. These results suggest a two stage process: stage one, PGO enhancement, is the direct consequence of the membrane activation of cholinoceptive PGO burst neurons by carbachol; stage two, REM enhancement, is the consequence of metabolic activation of endogenous cholinergic neurons. This experimental preparation is a useful model for the study of the electrophysiology and functional significance of PGO wave and REM sleep generation.

Acetylcholine↗
PubMed1992

Cholinergic microstimulation of the peribrachial nucleus in the cat. II. Delayed and prolonged increases in REM sleep.

The hypothesis that REM sleep is cholinergically mediated is supported by the identification of a cholinoceptive trigger zone in the FTG. Since this trigger zone is devoid of cholinergic neurons, the aim of the present study was to test the hypothesis that a cholinergic drive for REM sleep may come from the cholinergic cells of the PBL region. Chronically implanted freely moving cats with electrodes for sleep and PGO wave recordings were used. Guide tubes were implanted for carbachol microinjections (4 micrograms/250 nl) in the PBL and FTG. All microinjections were delivered in close vicinity of ChAT+ cholinergic cells in the PBL region. Results showed that a single unilateral carbachol microinjection into the PBL induced sustained (24 hr) state-independent ipsilateral PGO wave activity. This PGO wave activity was followed by a prolonged enhancement of REM sleep lasting for more than six days. We also observed that REM enhancement was followed by a delayed but marked enhancement of S sleep episodes with PGO waves (SP), which are normally brief transitions from S to REM sleep. Our findings strongly support the hypothesis that cholinergic drive for REM sleep comes from the lateral pontine tegmentum and we suggest that the PBL region plays a major role in both PGO wave generation and long-term regulation of REM sleep induction.

Acetylcholine↗
PubMed1991

Substantia nigra reticulata neurons during sleep-waking states: relation with ponto-geniculo-occipital waves.

We have previously hypothesized that the spike bursts of brainstem peribrachial (PB) neurons, leading to ponto-geniculo-occipital (PGO) waves in thalamocortical systems, are triggered by phasic hyperpolarizations of sufficient magnitude or by excitatory inputs reaching a steadily hyperpolarized membrane. We have proposed that the source of these hyperpolarizing actions are substantia nigra pars reticulata (SNr) cells that project to, and exert inhibitory effects upon, PB neurons. Here we tested this hypothesis by recording antidromically identified SNr-PB cells in chronically implanted, naturally sleeping cats. A subpopulation of SNr-PB cells exhibited tonically increased firing preceding by 70-200 ms the thalamic PGO wave. These data support the hypothesis that an enhancement in SNr-cells' discharges may lead to hyperpolarization of PB neurons, with the consequence of spike bursts in one class of PGO-related PB-thalamic neurons.

Animals↗
PubMed1991

Effect of recombinant fibroblast interferon and recombinant immune interferon on growth and the antigenic phenotype of multidrug-resistant human glioblastoma multiforme cells.

To study the effect of drug resistance on the response of stage IV astrocytomas to interferon, a human glioblastoma multiforme cell line, GBM-18, was transfected with an expression-vector plasmid containing a human multidrug resistance (MDR) gene (pHaMDR1/A), and clones surviving in colchicine were isolated. GBM-18 multidrug-resistant subclones displayed cross-resistance to other chemotherapeutic agents, including vincristine, doxorubicin, and dactinomycin. The multidrug-resistant phenotype was reversible when GBM-18 multidrug-resistant cells were cultured in colchicine and the calcium-channel blocker verapamil. The level of the MDR1 gene (also known as PGY1) message was increased in GBM-18 multidrug-resistant cells selected for increased resistance to colchicine, and this effect was not correlated with an amplification of the MDR1 gene. In both parental GBM-18 and GBM-18 multidrug-resistant cells, growth was suppressed to a greater degree when cultures were treated with the combination of fibroblast interferon (IFN-beta) and immune interferon (IFN-gamma). Parental cells and multidrug-resistant subclones varied in their de novo and/or interferon-modulated expression of HLA class I and class II antigens, a high-molecular-weight melanoma-associated antigen, and intercellular adhesion molecule 1 (ICAM-1). Of the antigens tested, ICAM-1 and HLA class I antigens were the most sensitive to enhanced expression induced by IFN-beta and IFN-gamma when used alone or in combination. The results of the present study indicate that multidrug-resistant human glioblastoma multiforme cells retain their increased sensitivity to the antiproliferative activity of the combination of IFN-beta plus IFN-gamma, and differences in antigenic phenotype are apparent in independent multidrug-resistant glioblastoma multiforme clones.

Antibodies, Monoclonal↗
PubMed1991

Human thyroid hormone beta 1 receptor produced by recombinant baculovirus-infected insect cells.

Thyroid hormone receptors are nuclear proteins which regulate transcription in a hormone dependent manner. The baculovirus expression system was used for the overexpression of the beta 1 isoform of the human thyroid hormone receptor. The baculovirus produced receptor binds tri-iodothyronine with high affinity, is specifically immunoprecipitated with a beta 1 specific antibody, and binds to DNA that contains a known thyroid hormone receptor recognition site. Large scale production and purification of baculovirus produced receptor will be useful for structure-function analyses and studies of transcriptional regulation.

Animals↗