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Biomedical subjects

Shiv K Sharma

Publications and source records attributed to Shiv K Sharma.

28 records · Page 2Linked to original sources
PubMed2003

A comparison of the effects of epidural and meperidine analgesia during labor on fetal heart rate.

OBJECTIVE: To estimate the effects of initiation of epidural analgesia on fetal heart rate (FHR) patterns compared with intravenous meperidine analgesia. METHODS: Fetal heart rate patterns in 200 nulliparous women with term pregnancies randomized to epidural analgesia with 0.25% bupivacaine were compared with those of 156 similar women given intravenous meperidine. Fetal heart rate patterns occurring within 40 minutes of initiation of labor analgesia were retrospectively read by three maternal-fetal medicine specialists who were blind to clinical events, including type of labor analgesia. RESULTS: Meperidine, compared with epidural analgesia, was associated with statistically significantly less beat-to-beat variability (absent or less than 5 beats per minute) of the FHR (30% versus 7% of fetuses, P <.001) in the first 40 minutes after initiation of analgesia, as well as with fewer FHR accelerations (88% versus 62% of fetuses, P <.001). Neither the incidence of FHR decelerations nor the type of deceleration were significantly different between methods of labor analgesia. Specifically, 41% of women given meperidine exhibited FHR decelerations within 40 minutes, compared with 34% given epidural analgesia (P =.353). CONCLUSION: Epidural analgesia does not have deleterious effects on FHR.

Adult↗
PubMed2003

Stand-off Raman spectroscopic detection of minerals on planetary surfaces.

We have designed and developed two breadboard versions of stand-off Raman spectroscopic systems for landers based on a 5-in. Maksutov-Cassegrain telescope and a small (4-in. diameter) Newtonian telescope receiver. These systems are capable of measuring the Raman spectra of minerals located at a distance of 4.5-66 m from the telescope. Both continuous wave (CW) Ar-ion and frequency doubled Nd:YAG (532 nm) pulsed (20 Hz) lasers are used as excitation sources for measuring remote Raman spectra of rocks and minerals. We have also made complementary measurements on the same rock samples with a micro-Raman system in 180 and 135 degrees geometry for evaluating the system performance and for estimating effect of grain size and laser-induced heating on the spectra of minerals using alpha-quartz as a model mineral. A field portable remote pulsed Raman spectroscopic system based on the 5-in. telescope and an f/2.2 spectrograph has been developed and tested. We have also demonstrated a prototype of a combined Raman and laser-induced breakdown spectroscopy (LIBS) system, capable of providing major element composition and mineralogical information on both biogenic and inorganic minerals at a distance of 10 m from the receiver.

Minerals↗
PubMed2003

Effects of particle size and laser-induced heating on the Raman spectra of alpha quartz grains.

Raman spectra of alpha-quartz (Qz) grains of various size (250 microm to < 11 microm) and arrangement (individual and aggregated) have been investigated with a combination of confocal Raman and micro-Raman systems. Frequency downshift and line broadening of the 464 cm(-1), v,(Si-O-Si) band are observed in the smallest size group (< 11 microm, both individual grains and aggregates) because of laser-induced heating and are used to estimate the temperature of the sampled region. The intensity ratio of the anti-Stokes to Stokes Raman lines is also used to estimate the vibrational temperature of the samples under different excitation power. The degree of laser-induced heating is more noticeable in the aggregates than in the individual grains with the use of medium-level laser excitation (< or = 150 mW). Heating diminishes with increasing grain size, and it can only be detected in grain aggregates between 11 and 20 microm in diameter using 150 mW excitation. Intensity studies of the v(s)(Si-O-Si) band using individual grains show no noticeable signs of grain size effects. However, grain size effects become an important factor in the study of aggregates in which spectral intensity diminishes with respect to decreasing grain size.

Hot Temperature↗
PubMed2002

The cdk5 homologue, crp, regulates endocytosis and secretion in dictyostelium and is necessary for optimum growth and differentiation.

Dictyostelium Crp is a member of the cyclin-dependent kinase (Cdk) family of proteins. It is most related in sequence to mammalian Cdk5, which unlike other members of the family, has functions that are unrelated to the cell cycle. In order to better understand the function of Crp in Dictyostelium, we overexpressed a dominant negative form, Crp-D144N, under the control of the actin 15 promoter. Cells overexpressing Crp-D144N exhibit a reduced growth rate in suspension culture and reduced rates of fluid-phase endocytosis and phagocytosis. There is no reduction in Cdc2 kinase activity in extracts from cells overexpressing Crp-D144N, suggesting that the growth defect is not due to inhibition of Cdc2. In addition to the growth defect, the act15::crp-D144N transformants aggregate at a slower rate than wild-type cells and form large aggregation streams. These eventually break up to form small aggregates and most of these do not produce mature fruiting bodies. The aggregation defect is fully reversed in the presence of wild-type cells but terminal differentiation is only partially rescued. In act15::crp-D144N transformants, the countin component of the counting factor, a secreted protein complex that regulates the breakup of streams, mostly appears outside the cell as degradation products and the reduced level of the intact protein may at least partially account for the initial formation of the large aggregation streams. Our observations indicate that Crp is important for both endocytosis and efflux and that defects in these functions lead to reduced growth and aberrant development.

Animals↗
PubMed2002

Epidural analgesia lengthens the Friedman active phase of labor.

OBJECTIVE: To estimate the effect of epidural analgesia on the Friedman labor curve. METHODS: This study was a secondary analysis of a previously reported randomized trial of the effects of patient-controlled epidural analgesia during labor compared with patient-controlled meperidine on cesarean delivery rate. All subjects had a singleton, cephalic, nonanomalous fetus at or beyond 37 weeks' gestation. This secondary analysis was limited to women who had cervical dilatation commencing of at least 3 cm (ie, active phase of labor). RESULTS: A total of 459 women were randomized. Twenty-five women were excluded for a cervix less than 3 cm dilated, leaving 220 women allocated to patient-controlled epidural analgesia and 214 to patient-controlled intravenous meperidine available for analysis. There were no significant demographic differences between the two groups, including age, race, gestational age, and cervix on admission. The active phase of labor was 1 hour longer in the epidural-treated group (6.0 +/- 3.2 hours versus 5.0 +/- 3.2 hours, P <.001). The rate of cervical dilation was significantly less with epidural analgesia (1.4 cm/h versus 1.6 cm/h, P <.002). The duration of the second stage tended to be longer in the epidural group (1.1 +/- 1.5 hours versus 0.9 +/- 1.0 hours, P =.079). CONCLUSION: Epidural analgesia prolonged the active phase of labor by 1 hour compared with Friedman's original criteria.

Adolescent↗
PubMed2002

Cesarean delivery: a randomized trial of epidural analgesia versus intravenous meperidine analgesia during labor in nulliparous women.

BACKGROUND: Controversy concerning increased cesarean births as a result of epidural analgesia for relief of labor pain has been attributed, in large part, to difficulties interpreting published studies because of design flaws. In this study, the authors compared epidural analgesia to intravenous meperidine analgesia using patient-controlled devices during labor to evaluate the effects of labor epidural analgesia, primarily on the rate of cesarean deliveries while minimizing limitations attributable to study design. METHODS: Four hundred fifty-nine nulliparous women in spontaneous labor at term were randomly assigned to receive either epidural analgesia or intravenous meperidine analgesia. Epidural analgesia was initiated with 0.25% bupivacaine and was maintained with 0.0625% bupivacaine and fentanyl 2 microg/ml at 6 ml/h with 5-ml bolus doses every 15 min as needed using a patient-controlled pump. Women in the intravenous analgesia group received 50 mg meperidine with 25 mg promethazine hydrochloride as an initial bolus, followed by 15 mg meperidine every 10 min as needed, using a patient-controlled pump. A written procedural manual that prescribed the intrapartum obstetric management was followed for each woman randomized in the study. RESULTS: A total of 226 women were randomized to receive epidural analgesia, and 233 women were randomized to receive intravenous meperidine analgesia. Protocol violations occurred in 8% (38 of 459) of women. There was no difference in the rate of cesarean deliveries between the two analgesia groups (epidural analgesia, 7% [16 of 226; 95% confidence interval, 4-11%] vs. intravenous meperidine analgesia, 9% [20 of 233; 95% confidence interval, 5-13%]; P = 0.61). Significantly more women randomized to epidural analgesia had forceps deliveries compared with those randomized to meperidine analgesia (12% [26 of 226] vs. 3% [7 of 233]; P < 0.001). Women who received epidural analgesia reported lower pain scores during labor and delivery compared with women who received intravenous meperidine analgesia. CONCLUSIONS: Epidural analgesia compared with intravenous meperidine analgesia during labor does not increase cesarean deliveries in nulliparous women.

Adult↗
PubMed2002

Analgesia in labour and fetal acid-base balance: a meta-analysis comparing epidural with systemic opioid analgesia.

OBJECTIVE: To assess the effect of epidural versus systemic labour analgesia on funic acid-base status at birth. DESIGN: A systematic review of trials, both randomised and non-randomised, comparing epidural with systemic opioid analgesia. POPULATION: Babies of 2102 mothers taking part in trials comparing epidural with systemic analgesia in five countries. METHODS: From the published and unpublished figures obtained from authors, fetal pH data from 12 studies (eight randomised) (1098 babies in the epidural group + 1004 controls) and base excess from 8 studies (four randomised) (856 epidural + 842 controls) were subjected to random effect meta-analysis. MAIN OUTCOME MEASURES: Umbilical artery pH and base excess values. RESULTS: Fetal pH was higher in the epidural than in the control group in the randomised trials (difference +0.009, 95% CI +0.002 to +0.015), but when all studies were included, the difference was not significant (+0.004, 95% CI -0.005 to +0.014). Fetal base excess was higher in the epidural group in the four randomised studies (difference +0.779 mEq/L, 95% CI +0.056 to +1.502) and in all eight studies (difference +0.837 mEq/L, 95% CI +0.330 to +1.343). CONCLUSION: Umbilical artery pH is influenced by maternal hyperventilation. Base excess is therefore a better index of metabolic acidosis after labour. Epidural analgesia is associated with improved neonatal acid-base status, suggesting that placental exchange is well preserved in association with maternal sympathetic blockade and good analgesia. Although epidural analgesia may cause maternal hypotension and fever, longer second stage of labour and more instrumental vaginal deliveries, these potentially adverse factors appear to be outweighed by benefits to neonatal acid-base status.

Acid-Base Equilibrium↗
PubMedDate not supplied

The roles of MAPK cascades in synaptic plasticity and memory in Aplysia: facilitatory effects and inhibitory constraints.

Synaptic plasticity is thought to contribute to memory formation. Serotonin-induced facilitation of sensory-motor (SN-MN) synapses in Aplysia is an extensively studied cellular analog of memory for sensitization. Serotonin, a modulatory neurotransmitter, is released in the CNS during sensitization training, and induces three temporally and mechanistically distinct phases of SN-MN synaptic facilitation. The role of protein kinase A and protein kinase C in SN-MN synaptic facilitation is well documented. Recently, it has become clear that mitogen-activated protein kinase (MAPK) cascades also play a critical role in SN-MN plasticity. Here, we summarize the roles of MAPK cascades in synaptic plasticity and memory for sensitization in Aplysia.

Animals↗