Ciprofloxacin susceptible Salmonella typhi with treatment failure.
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Anti-Infective Agents↗
Biomedical subjects
S Datta
Publications and source records attributed to S Datta.
The effect of magnesium on coagulation in parturients with preeclampsia.
UNLABELLED: Preeclampsia is associated with complex coagulation abnormalities that include altered platelet function and consumption and activation of the fibrinolytic system. Magnesium sulfate, which is used as a therapeutic modality for the prevention of seizures in preeclamptic parturients, has anticoagulant and antiplatelet effects. We sought to determine the effects of magnesium on various components of the coagulation system in patients with preeclampsia. We assessed the coagulation status of 18 parturients with preeclampsia being treated with magnesium. The assessment was performed with the thromboelastograph test, which provides an overall assessment of blood coagulation via the coagulation index. Thromboelastography was performed before beginning magnesium therapy and 30 min and 2 h after a 6-g bolus of IV magnesium. The R value (time to first clot formation) was found to be significantly slower (P < 0.05) at 30 min after the magnesium bolus. This result suggests increased coagulant factor activity resulting from the magnesium bolus. However, there was no effect of magnesium on the overall coagulation, as evidenced by the lack of change in the coagulation index either at 30 min or at 2 h after the completion of the initial magnesium bolus. Therefore, this therapy should have no effect on the use of neuraxial techniques. IMPLICATIONS: On the basis of the thromboelastography assessment, we found that the current practice of administering magnesium did not influence overall coagulation in preeclamptic women. Therefore, magnesium administration should not affect the use of neuraxial techniques.
Adult↗
Microinjection of glutamate into the pedunculopontine tegmentum induces REM sleep and wakefulness in the rat.
The aim of this study was to test the hypothesis that the cells in the brain stem pedunculopontine tegmentum (PPT) are critically involved in the normal regulation of wakefulness and rapid eye movement (REM) sleep. To test this hypothesis, one of four different doses of the excitatory amino acid L-glutamate (15, 30, 60, and 90 ng) or saline (control vehicle) was microinjected unilaterally into the PPT while the effects on wakefulness and sleep were quantified in freely moving chronically instrumented rats. All microinjections were made during wakefulness and were followed by 6 h of polygraphic recording. Microinjection of 15- ng (0.08 nmol) and 30-ng (0.16 nmol) doses of L-glutamate into the PPT increased the total amount of REM sleep. Both doses of L-glutamate increased REM sleep at the expense of slow-wave sleep (SWS) but not wakefulness. Interestingly, the 60-ng (0.32 nmol) dose of L-glutamate increased both REM sleep and wakefulness. The total increase in REM sleep after the 60-ng dose of L-glutamate was significantly less than the increase from the 30-ng dose. The 90-ng (0.48 nmol) dose of L-glutamate kept animals awake for 2-3 h by eliminating both SWS and REM sleep. These results show that the L-glutamate microinjection into the PPT can increase wakefulness and/or REM sleep depending on the dosage. These findings support the hypothesis that excitation of the PPT cells is causal to the generation of wakefulness and REM sleep in the rat. In addition, the results of this study led to the identification of the PPT dosage of L-glutamate that optimally induces wakefulness and REM sleep. The knowledge of this optimal dose will be useful in future studies investigating the second messenger systems involved in the regulation of wakefulness and REM sleep.
Animals↗
even skipped is required to produce a trans-acting signal for larval neuroblast proliferation that can be mimicked by ecdysone.
Development of a multicellular organism requires precise coordination of cell division and cell type determination. The selector homeoprotein Even skipped (Eve) plays a very specific role in determining cell identity in the Drosophila embryo, both during segmentation and in neuronal development. However, studies of gene expression in eve mutant embryos suggest that eve regulates the embryonic expression of the vast majority of genes. We present here genetic interaction and phenotypic analysis showing that eve functions in the trol pathway to regulate the onset of neuroblast division in the larval CNS. Surprisingly, Eve is not detected in the regulated neuroblasts, and culture experiments reveal that Eve is required in the body, not the CNS. Furthermore, the effect of an eve mutation can be rescued both in vivo and in culture by the hormone ecdysone. These results suggest that eve is required to produce a trans-acting factor that stimulates cell division in the larval brain.
Alleles↗
Tracheal granulation tissue after percutaneous tracheostomy treated with Nd:Yag laser: three cases.
Three adult patients who received percutaneous serial dilatational tracheostomy post-cardiac surgery developed histologically confirmed tracheal granulation tissue superior to the point of entry of the tracheostomy tube into the trachea. This tissue significantly occluded the trachea in all patients and, in two, led to serious haemorrhage. Each patient had serial dilatational percutaneous tracheostomy using the Cook/Ciaglia technique. On each patient fibre-optic bronchoscopy confirmed satisfactory position of the guidewire and tracheostomy tube. Nd:Yag laser therapy was applied to areas of tracheal granulation tissue and was also employed to secure haemostasis. In each patient endobronchial Nd:YAG laser therapy successfully cleared the granulation tissue and secured haemostasis. Follow-up bronchoscopy showed no recurrence. Fibre-optic bronchoscopy at the time of tracheal decannulation may identify granulation tissue requiring appropriate referral and intervention.
Aged↗
Exploring relationships in gene expressions: a partial least squares approach.
Microarray technology has revolutionized the way gene functions are monitored. Analysis of microarray data is a fast growing research area that interfaces various disciplines such as biology, biochemistry, computer science, and statistics. While various clustering and classification techniques have been successfully employed to group genes based on the similarity of their expression patterns, much is yet to be learned about the interrelationship of the expression levels among various genes. We approach this problem with a statistical technique called partial least squares that is capable of modeling a large number of variables each with relatively few observations. This property of the partial least squares methodology appears to be attractive for application to microarray data sets where the simultaneous expression levels of many genes are collected each at a few time points (or individuals). We use it to analyze publicly available microarray data on sporulation of budding yeast (Saccharomyces cerevisiae). We investigate a number of representative genes, one from each temporal group (based on the time of first induction) of positively expressed genes and show that in each case most of the variability was explained by only two partial regression terms based on all remaining genes. Moreover, the predicted expression levels of the representative genes from partial least squares fit very well on the average with the true expression levels over time. Finally, we compare the biological functions of the genes with largest coefficients with those of the predicted genes. In many cases, the genes are involved in similar or related biological functions including negative relationships. We show that this method can identify established gene relationships; we argue that it can be an exploratory tool for identifying potential gene relationships requiring further biological investigation.
Gene Expression Profiling↗
Ataxica telengiectasia (Louis-Bar syndrome).
A case of ataxia telengiectasia in a 7-year-old girl with symptoms for last 3 years has been reported in detail. The necessary literature has been reviewed with proper references.
Ataxia Telangiectasia↗
Tracheal stenting for rupture of the posterior wall of the trachea following percutaneous tracheostomy.
Perforation of the posterior wall of the trachea during percutaneous tracheostomy is a recognised complication. Treatment by either conservative or surgical management has been described. We report two patients who developed posterior tracheal wall perforation following percutaneous tracheostomy who were successfully treated by insertion of covered, expandable metallic stents. This is a well tolerated procedure that has minimal complications and can be performed at the bedside. We recommend that tracheal stenting should be considered for the management of posterior tracheal wall perforation following percutaneous tracheostomy in those patients unsuitable for surgical intervention.
Aged↗
Estimation of vacuolating cytotoxin secreted by different strains of Helicobacter pylori using bead enzyme-linked immunosorbent assay & its correlation with bacterial genotype.
BACKGROUND & OBJECTIVES: A highly sensitive bead enzyme-linked immunosorbent assay was applied for the quantitative determination of vacuolating cytotoxin (VacA) released in the culture supernatant of 40 well characterized Helicobacter pylori strains in order to clarify the significance of allelic combination of the vacA gene as the predictor of the level of toxin secretion and also to determine the most appropriate genotype of H. pylori associated with high VacA release. Attempts were also made for the detection of VacA in the gastric juice of patients for the rapid diagnosis of H. pylori infection. METHODS: The genotypes of 40 H. pylori strains cultured from the gastric biopsy samples were determined by specific PCRs. The cell-free culture supernatant of the strains as well as the gastric juice of the patients were used for bead-ELISA and the purified VacA from the H. pylori strain ATCC49503 was used as positive control. RESULTS: Ninety per cent of the strains with vacAs1m1 allele combination secrete on an average 146.4 ng/ml of VacA while the corresponding value was 19.1 ng/ml for s1m2 strains. None of the s2m2 as well as the ice negative H. pylori strains produced detectable VacA in the medium while strains expressed the toxin irrespective of the presence or absence of cagA gene. Fifteen of 22 gastric juice samples yielded positive bead-ELISA results. INTERPRETATION & CONCLUSION: vacAs1, vacAm1 and iceA1 could be considered as the determinants of high VacA secretion. Also, the detection of VacA by bead-ELISA in the gastric juice could be considered as an alternative approach in the diagnosis of H. pylori infection.
Adult↗
Crystal structures of Mycobacterium tuberculosis RecA and its complex with ADP-AlF(4): implications for decreased ATPase activity and molecular aggregation.
Sequencing of the complete genome of Mycobacterium tuberculosis, combined with the rapidly increasing need to improve tuberculosis management through better drugs and vaccines, has initiated extensive research on several key proteins from the pathogen. RecA, a ubiquitous multifunctional protein, is a key component of the processes of homologous genetic recombination and DNA repair. Structural knowledge of MtRecA is imperative for a full understanding of both these activities and any ensuing application. The crystal structure of MtRecA, presented here, has six molecules in the unit cell forming a 6(1) helical filament with a deep groove capable of binding DNA. The observed weakening in the higher order aggregation of filaments into bundles may have implications for recombination in mycobacteria. The structure of the complex reveals the atomic interactions of ADP-AlF(4), an ATP analogue, with the P-loop-containing binding pocket. The structures explain reduced levels of interactions of MtRecA with ATP, despite sharing the same fold, topology and high sequence similarity with EcRecA. The formation of a helical filament with a deep groove appears to be an inherent property of MtRecA. The histidine in loop L1 appears to be positioned appropriately for DNA interaction.
Adenosine Diphosphate↗
Avoidance task training potentiates phasic pontine-wave density in the rat: A mechanism for sleep-dependent plasticity.
Behavioral studies of learning and memory in both humans and animals support a role for sleep in the consolidation and integration of memories. The present study explored possible physiological mechanisms of sleep-dependent behavioral plasticity by examining the relationship between learning and state-dependent phasic signs of rapid eye movement (REM) sleep. Cortical electroencephalogram, electromyogram, eye movement, hippocampal theta-wave, and pontine-wave (P-wave) measures were recorded simultaneously in freely moving rats after a session of conditioned avoidance learning or a control session. After learning trials, rats spent 25.5% more time in REM sleep and 180.6% more time in a transitional state between slow-wave sleep and REM sleep (tS-R) compared with that in control trials. Both REM sleep and tS-R behavioral states are characterized by the presence of P-waves. P-wave density was significantly greater in the first four episodes of REM sleep after the learning session compared with the control session. Furthermore, the P-wave density change between the first and third REM sleep episodes was proportional to the improvement of task performance between the initial training session and the post-sleep retest session. These findings show that the increase in P-wave density during the post-training REM sleep episodes is correlated with the effective consolidation and retention of avoidance task learning.
Animals↗
Clogging time of a filter.
We study the time until a filter becomes clogged due to the trapping of suspended particles as they pass through a porous medium. This trapping progressively impedes and eventually stops the flow of the carrier fluid. We develop a simple description for the pore geometry and the motion of the suspended particles which, together with extreme-value statistics, predicts that the distribution of times until a filter clogs has a power-law long-time tail, with an infinite mean clogging time. These results and its consequences are in accord with simulations on a square lattice porous network.
Journal Article↗
Studies on the modeling and simulation of a sequential bienzymatic reaction system immobilized in emulsion liquid membrane.
Experiments have been carried out to study the reaction engineering behavior of the liquid membrane-encapsulated, sequential bienzymatic reaction system, n 2n glucose. A dynamic mathematical model, free from adjustable parameters, has been developed taking into account peri-emulsion mass transfer, intra-emulsion diffusion, membrane-related mass transfer limitations and substrate and product inhibitions. A finite difference-based, user-friendly software has been developed to solve the model equations. Experimental data satisfactorily correlate with the model. While it is understood that study of sequential bienzymatic reaction system immobilized in emulsion liquid is essential for their industrial exploitation, reaction engineering behavior of such a system in presence of both substrate and product inhibitions has not yet been reported in the literature. Therefore, the model predictions of the present investigations are expected to pave the way for scale-up and design of industrial bioreactors in this field.
Journal Article↗
Interleukin-1-mediated stabilization of mouse KC mRNA depends on sequences in both 5'- and 3'-untranslated regions.
mRNA transcribed from the mouse KC chemokine gene accumulated to significantly higher levels in multiple cell types after treatment with interleukin 1alpha (IL-1alpha) as compared with tumor necrosis factor-alpha (TNFalpha). Although TNFalpha and IL-1alpha both signaled the activation of nuclear factor kappaB and enhanced transcription of the KC gene with equal potency, only IL-1alpha treatment resulted in stabilization of KC mRNA. Nucleotide sequences that confer sensitivity for IL-1alpha-mediated mRNA stabilization were identified within the 5'- and 3'-untranslated regions (UTRs) of KC mRNA using transient transfection of chimeric plasmids containing specific portions of KC mRNA linked to the chloramphenicol acetyltransferase (CAT) gene. When plasmids containing either the 3'- or 5'-UTR of KC mRNA were used, the half-life of CAT mRNA was unaltered either in untreated or IL-1alpha-stimulated cells. In contrast, CAT mRNA transcribed from plasmids that contained both the 5'- and 3'-UTRs of the KC mRNA decayed more rapidly than control CAT mRNA, and this enhanced decay was prevented in cells treated with IL-1alpha. A cluster of four overlapping AUUUA motifs within the 3'-UTR was required, whereas the 5'-UTR region exhibited orientation dependence. These findings indicate that cooperative function of the two nucleotide sequences involves a distinct signaling pathway used by IL-1alpha but not TNFalpha.
3' Untranslated Regions↗
Transcutaneous electrical nerve stimulation does not augment combined spinal epidural labour analgesia.
PURPOSE: The spinal portion of the combined spinal epidural technique (CSE) provides dramatic but limited labour analgesia. Transcutaneous Electrical Nerve Stimulation (TENS) has been noted to modulate pain, in part by the frequency of stimulation chosen. Because nerve action potentials are blocked by local anesthetics in a frequency dependent manner, we speculated that a TENS unit could increase the quality and duration of the spinal portion of a CSE. METHODS: Forty parturients in active spontaneous labour, with a singleton, vertex, term fetus, requesting analgesia were enrolled in a randomized, double blind fashion to receive a standardized CSE with either an active or inactive TENS unit. Prior to CSE placement, TENS intensity thresholds were determined with electrodes placed on the paraspinus muscles at T10-L1, and S2-4; TENS settings for mode, cycle, and pulse width were standardized. Data were collected at timed intervals on pain (VAS), sensory level (pinprick), motor blockade (Bromage), cervical dilatation, and duration of analgesia, and at delivery on fetal and neonatal outcome. RESULTS: The duration of the spinal portion of the CSE did not differ between groups (TENS off 91.1+/-33 [mean +/- SD] vs. TENS on 83.1+/-28 min, P = .42). Kaplan-Meier survival analysis and Mantel-Cox log rank analysis showed no difference between the two treatments (P = .28). Analgesia was comparable throughout the first hour of spinal analgesia. CONCLUSION: In healthy labouring parturients, the application of a TENS unit did not alter the quality or duration of labour analgesia provided by the spinal portion of CSE analgesia.
Adult↗
Airway changes during Cesarean hysterectomy.
PURPOSE: To document whether hemorrhage and fluid administration during peripartum hysterectomy results in changes in the airway that may predispose to subsequent difficult intubation, in the event that intraoperative general anesthesia is required during regional anesthesia. CLINICAL FEATURES: A 32-yr-old underwent peripartum hysterectomy for placenta accreta. Blood loss of 5.5 L occurred during surgery requiring 6 L crystalloid, 1 L hetastarch, five units packed RBCs and two units fresh frozen plasma. Airway changes were followed using Samsoon's modification of Mallampati airway classification. In addition, airway photographs were obtained using a Polaroid camera. The airway of the patient changed from class 2 preoperatively to class 4 in the immediate postoperative period. The airway gradually returned to normal over the ensuing 48 hr, during which a negative fluid balance of 4 L occurred due to substantial postoperative diuresis. CONCLUSION: Peripartum airway changes were detected during Cesarean hysterectomy and fluid resuscitation that gradually returned to normal within 48 hr after surgery.
Adult↗
Setting the target for a better cervical screening test: characteristics of a cost-effective test for cervical neoplasia screening.
OBJECTIVE: To determine the potential effects on costs and outcomes of changes in sensitivity and specificity with new screening methods for cervical cancer. METHODS: Using a Markov model of the natural history of cervical cancer, we estimated the effects of sensitivity, specificity, and screening frequency on cost-effectiveness. Our estimates of conventional Papanicolaou test sensitivity of 51% and specificity of 97% were obtained from a meta-analysis. We estimated the effect of reducing false-negative rates from 40-90% and increasing false-positive rates by up to 20%, independently and jointly. We varied the marginal cost of improving sensitivity from $0 to $15. RESULTS: When specificity was held constant, increasing sensitivity of the Papanicolaou test increased life expectancy and costs. When sensitivity was held constant, decreasing specificity of the Papanicolaou test increased costs, an effect that was more dramatic at more frequent intervals. Decreased specificity had a substantial effect on cost-effectiveness estimates of improved Papanicolaou test sensitivity. Most of those effects are related to the cost of evaluation and treatment of low-grade lesions. CONCLUSION: Policies or technologies that increased sensitivity of cervical cytologic screening increased overall costs, even if the cost of the technology was identical to that of conventional Papanicolaou smears. These effects appear to be caused by relatively high prevalence of low-grade lesions and are magnified at frequent screening intervals. Efficient cervical cancer screening requires methods with greater ability to detect lesions that are most likely to become cancerous.
Adolescent↗