PubMed Health⌕ Search

Biomedical subjects

P Chatterjee

Publications and source records attributed to P Chatterjee.

At least 19 recordsLinked to original sources
PubMed1997

Isolation and characterization of primordial follicles from fresh and cryopreserved human ovarian tissue.

OBJECTIVE: To develop an efficient isolation technique for human primordial follicles. DESIGN: Prospective, experimental study of ovarian biopsies collected from healthy women undergoing elective cesarean section. Ovarian blocks either were fixed for histology and follicle counting or partially disaggregated with type 1A collagenase before or after cryopreservation. After partial disaggregation, follicles were isolated by microdissection. SETTING: Leeds General Infirmary. MAIN OUTCOME MEASURE(S): Follicle viability was assessed with live-dead stains using 5-(and 6-) carboxyfluorescein diacetate, succinimidyl ester and propidium iodide, respectively, and using electron microscopy. The numbers recovered were expressed as a percentage of the numbers of primordial follicles in comparable blocks of tissue and the viability of the whole follicle and oocyte were scored separately. RESULT(S): On average, 18.0 +/- 3.8 and 15.9 +/- 2.2 (mean +/- SEM) follicles per block were recovered from fresh and cryopreserved ovarian tissue, respectively, corresponding to recovery rates of 57.9% +/- 8.8% and 56.2% +/- 16.7%. In the fresh group, the percent viability of whole follicles and oocytes were 71.6% +/- 2.4% and 91.3% +/- 2% compared with 71.5% +/- 4.7% and 95% +/- 4.3% in the frozen-thawed group. Electron microscopy confirmed that the majority of the cells lacked ultrastructural signs of damage after isolation and cryopreservation. CONCLUSION(S): Primordial follicles can be isolated from fresh and cryopreserved human ovarian tissue with similar high efficiency and viability rates.

Adult↗
PubMed1997

Potentiation of endothelium-dependent relaxation by epoxyeicosatrienoic acids.

Epoxyeicosatrienoic acids (EETs) are potent endothelium-derived vasodilators formed from cytochrome P-450 metabolism of arachidonic acid. EETs and their diol products (DHETs) are also avidly taken up by endothelial cells and incorporated into phospholipids that participate in signal transduction. To investigate the possible functional significance of EET and DHET incorporation into cell lipids, we examined the capacity of EETs and DHETs to relax porcine coronary arterial rings and determined responses to bradykinin (which potently activates endothelial phospholipases) before and after incubating the rings with these eicosanoids. 14,15-EET and 11,12-EET (5 mumol/L) produced 75 +/- 9% and 52 +/- 4% relaxation, respectively, of U46619-contracted rings, whereas 8,9-EET and 5,6-EET did not produce significant relaxation. The corresponding DHET regioisomers produced comparable relaxation responses. Preincubation with 14,15-EET, 11,12-EET, 14,15-DHET, and 11,12-DHET augmented the magnitude and duration of bradykinin-induced relaxation, whereas endothelium-independent relaxations to aprikalim and sodium nitroprusside were not potentiated. Pretreatment with 2 mumol/L triacsin C (an inhibitor of acyl coenzyme A synthases) inhibited [3H]14,15-EET incorporation into endothelial phospholipids and blocked 11,12-EET- and 14,15-DHET-induced potentiation of relaxation to bradykinin. Exposure of [3H]14,15-EET-labeled endothelial cells to the Ca2+ ionophore A23187 (2 mumol/L) resulted in a 4-fold increased release of EET and DHET into the medium. We conclude that incorporation of EETs and DHETs into cell lipids results in potentiation of bradykinin-induced relaxation in porcine coronary arteries, providing the first evidence that incorporated EETs and DHETs are capable of modulating vascular function.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1995

Return of fertility following discontinuation of Norplant-II subdermal implants. ICMR Task Force on Hormonal Contraception.

A total of 627 women who had discontinued the use of the Norplant-II implants for various reasons and were exposed to the risk of pregnancy were followed-up for two years for return of fertility. The cumulative conception rates in women who had discontinued due to planning pregnancy were 80.3 per 100 women at one year and 88.3 per 100 women at two years. The majority of women who did conceive (90 percent), had full-term normal live births; about 4 percent of women had spontaneous abortions, the remaining 6 percent decided on elective termination of pregnancy (ETP). The cumulative conception rates in women who discontinued due to bleeding irregularities and 'other reasons' were 64.5 and 55.8 per 100 women at one year and 77.9 and 75.1 per 100 women at two years, respectively. These rates were significantly lower as compared to those observed in women who discontinued due to planning pregnancy. A large proportion, about 40 percent, of women who conceived after discontinuation of the method due to bleeding irregularities and "other reasons," opted for ETP indicating that many women in these two groups did not desire another child and that such women need to be counselled for adopting another method of contraception. The spontaneous abortion rates observed in ex-users of Norplant-II implants (1.7 to 4.4% pregnancies) were comparable to the spontaneous abortion rates prior to Norplant-II implant use (3.6% pregnancies) indicating that ex-users of Norplant-II implants were not at a higher risk of spontaneous abortion.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Nitric oxide production by human proximal tubular cells: a novel immunomodulatory mechanism?

It is believed that human proximal tubular cells may possess immunological function and play an important role in a variety of renal disease states such as interstitial nephritis, allograft rejection and drug induced nephrotoxicity. The role of cytokines and nitric oxide in the human forms of these disease states is not clear. In this study we examined the effect of stimulation with the cytokines IL-1 beta. TNF-alpha and IFN-gamma, individually and in combination, upon primary cultures of human proximal tubular cells. Nitric oxide production increased significantly within 24 hours following cytokine stimulation. This response was inhibited, in a dose dependent manner, by L-NMMA. PCR amplification of mRNA extracted from control and cytokine stimulated human proximal tubular cells revealed a NOS product with a > 97% homology with human hepatocyte inducible nitric oxide synthase. The results of this study clearly show that human proximal tubular cells, in primary culture, are capable of producing nitric oxide in response to an immune challenge secondary to the induction of nitric oxide synthase.

Amino Acid Oxidoreductases↗
PubMed1994

Production of linear polymers of HIV gp120-binding domains.

It has been demonstrated previously that molecular decoys of the acetylcholine receptor have therapeutic efficacy as antitoxins [Gershoni, J. and Aronheim, A. (1988) Proc. Natl Acad. Sci. USA, 85, 4087-4089], but surely a most challenging goal is to apply this approach towards the development of antiviral drugs. As viruses present multiple copies of their envelope proteins, it was proposed that polyvalent decoys could be advantageous. Here we report the design and expression of recombinant linear polymers of the HIV gp120-binding domains which are situated within the T-cell membrane protein CD4. Whereas the production of linear concatemers of CD4 variable domains is feasible, a number of conformational constraints must be considered when designing a polymeric molecule which retains biological function. Most significant is the contribution of domains flanking the binding site that apparently enable correct folding of the latter.

Antiviral Agents↗
PubMed1994

Ephedrine remains the vasopressor of choice for treatment of hypotension during ritodrine infusion and epidural anesthesia.

BACKGROUND: Historically, ephedrine has been the vasopressor of choice for treatment of most cases of hypotension in obstetric patients. However, the choice of vasopressor in the parturient receiving a beta-adrenergic agent for tocolysis has not been evaluated extensively. The current study evaluated whether ephedrine or phenylephrine better restores uterine blood flow and fetal oxygenation during ritodrine infusion and epidural anesthesia-induced hypotension in gravid ewes. METHODS: Fourteen chronically instrumented gravid ewes between 0.8 and 0.9 timed gestational age were used. On separate days, each animal underwent the experimental protocol with one of three agents: ephedrine, phenylephrine, and normal saline-control. The experimental protocol was as follows: (1) at time zero, intravenous infusion of ritodrine was begun; (2) at 120 min, 2% lidocaine was given epidurally to achieve a sensory level of at least T6; and (3) at 135 min, an intravenous bolus of either ephedrine, phenylephrine, or normal saline-control was given, followed by a continuous intravenous infusion of the same agent for 30 min. In the ephedrine and phenylephrine experiments, the rate of infusion was adjusted to maintain maternal mean arterial pressure close to baseline. RESULTS: Ritodrine infusion alone significantly increased maternal heart rate and cardiac output in all three groups. Epidural anesthesia during ritodrine infusion significantly decreased maternal mean arterial pressure, heart rate, cardiac output, uterine blood flow, and fetal arterial oxygen tension for each of the three groups. Both ephedrine and phenylephrine restored maternal mean arterial pressure to baseline, as designed. Ephedrine significantly increased uterine blood flow and fetal arterial oxygen tension when compared with normal saline--control, but phenylephrine did not. Phenylephrine significantly increased uterine vascular resistance when compared with normal saline--control, but ephedrine did not. CONCLUSIONS: Although ephedrine and phenylephrine provided similar restoration of maternal mean arterial pressure, ephedrine was superior to phenylephrine in restoring uterine blood flow during ritodrine infusion and epidural anesthesia-induced hypotension in gravid ewes. Also, ephedrine, but not phenylephrine, significantly improved fetal oxygenation, when compared to normal saline--control.

Acid-Base Equilibrium↗
PubMed1994

The effects of epidural anesthesia on uterine vascular resistance, plasma arginine vasopressin concentrations, and plasma renin activity during hemorrhage in gravid ewes.

In an earlier study, epidural anesthesia increased uterine vascular resistance and fetal acidosis during hemorrhage in gravid ewes. But, it is unclear whether epidural anesthesia modifies the uterine vascular resistance response during hemorrhage, independent of changes in arterial blood pressure. The purpose of this study was to determine the effects of epidural anesthesia on: 1) the mean arterial pressure/uterine vascular resistance relationship; and 2) arginine vasopressin concentrations and plasma renin activity during hemorrhage in gravid ewes. Twenty-four experiments were performed in 12 chronically instrumented animals between 0.8 and 0.9 of timed gestation. The experimental sequence included: 1) T = 0 min: epidural administration of 0.5% bupivacaine (epidural group) or normal saline (control group); 2) T = 30 min: maternal hemorrhage 0.5 mL.kg-1 x min-1 until maternal mean arterial pressure was 60% of baseline measurements (time H); 3) T = H to H + 60 min: adjust hemorrhage to maintain maternal mean arterial pressure at 60% of baseline. At 30 min, epidural bupivacaine resulted in a median sensory level of T-8 in the epidural group. At that time, uterine vascular resistance was similar in both groups despite lower (P = 0.0001) mean arterial pressure in the epidural group. Between H and H + 60 min, uterine vascular resistance was lower (P = 0.045) in the epidural group than in the control group. Also, fetal PCO2 was lower (P = 0.020) in the epidural group than in the control group, but fetal pH and PO2 did not differ significantly between groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Epidural↗
PubMed1993

Hormonal regulation of sialic acid-binding (SAS) protein synthesis of rat uterus.

Sialic acid binding proteins (SAS) of rat uteri have been found in all three stages of the estrous cycle. To study the control of synthesis of these proteins two different animal models were used I-immature female rats (25 d) where the hormones estradiol (E2) and progesterone (P4) were given separately and together, and II-adult female rats where hormone treatment commenced 14 days after ovariectomy. The data indicated that E2 initiated the synthesis of SAS proteins in the immature animals, while P4 could inhibit SAS synthesis, either given alone or together with E2. However, prior priming of the rat with E2 and subsequent administration of P4 stimulated SAS protein synthesis.

Agglutinins↗
PubMed1993

Human immunodeficiency virus type 2 multiply spliced transcripts.

Viral transcripts, particularly those of the regulatory genes (e.g., rev) in lymphocytic cells chronically infected with human immunodeficiency virus type 2, consist of two types, differing in the structure of the leader sequence derived from the 5' long terminal repeat (LTR). Some transcripts undergo a specific splicing event within the 5' LTR, removing an intron consisting of a part of the R region whereas others do not. Because this spliced-out R region is a part of the trans-activation response element (TAR), it could influence trans-activator (Tat)-mediated trans-activation of viral gene expression. Moreover, this part of the R region is predicted to contain a stable secondary structure that could affect the efficiency of translation of the transcripts without this splicing. Thus, the 5' LTR splicing could have important consequences for virus replication, latency, and pathogenicity.

Base Sequence↗
PubMed1992

Epidural anesthesia worsens uterine blood flow and fetal oxygenation during hemorrhage in gravid ewes.

Recent studies suggest that epidural anesthesia initiated before hemorrhage may improve survival and acid-base status in laboratory animals. However, studies of hemorrhagic shock in nonpregnant animals may not be applicable to less severe hemorrhage in pregnant animals. The purpose of this study was to determine whether epidural anesthesia alters maternal and fetal hemodynamic and acid-base responses to hemorrhage in gravid ewes. Twenty-four experiments were performed in twelve chronically instrumented animals between 0.8 and 0.9 of timed gestation. The experimental sequence included: 1) T = 0 min: normal saline 500 ml intravenously; 2) T = 15 min: epidural administration of 0.5% bupivacaine (epidural group) or normal saline (control group); 3) T = 30 min: epidural administration of additional 0.5% bupivacaine (epidural group only) if the sensory level of anesthesia was below T10; 4) T = 45 min: maternal hemorrhage 20 ml/kg over 55 min; and 5) T = 110 min: transfusion of collected maternal blood over 55 min. At 45 min (i.e., 30 min after the epidural injection of bupivacaine), epidural bupivacaine resulted in a median sensory level of T9 in the epidural group. At that time, maternal mean arterial pressure was less (P less than 0.05) in the epidural group than in the control group (14 +/- 2% below baseline versus 4 +/- 1% above baseline, respectively). Maternal mean arterial pressure, heart rate, cardiac output, and uterine blood flow, and fetal PO2 and pH all were significantly less during hemorrhage (P less than 0.05) in the epidural group than in the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Epidural↗
PubMed1992

Which vasopressor should be used to treat hypotension during magnesium sulfate infusion and epidural anesthesia?

Ephedrine restores and/or protects uterine blood flow and fetal well-being in laboratory animals. In contrast, alpha 1-adrenergic agonists worsen uterine blood flow and fetal condition. We previously demonstrated that magnesium sulfate (MgSO4) attenuates the detrimental effects of phenylephrine on uterine vascular resistance in gravid ewes. Therefore, we performed this study to determine whether ephedrine or phenylephrine better restores and protects uterine blood flow and fetal oxygenation during epidural anesthesia-induced hypotension in hypermagnesemic gravid ewes. Twelve chronically instrumented gravid ewes were each used for three experiments: 1) ephedrine, 2) phenylephrine, and 3) normal saline (NS)-control. For each experiment the protocol was as follows: 1) at time zero, intravenous infusion of MgSO4 was begun; 2) at 150 min a thoracic level of epidural anesthesia was achieved with 2% lidocaine; and 3) at 165 min, an intravenous infusion of ephedrine, phenylephrine, or NS was begun and continued through 195 min. Epidural anesthesia uniformly decreased maternal mean arterial blood pressure (MAP), heart rate, cardiac output, uterine blood flow, and fetal PO2 in each of the three groups. Both ephedrine and phenylephrine restored maternal MAP to baseline, as expected from the experimental design. Ephedrine significantly increased cardiac output and uterine blood flow when compared with NS-control, but phenylephrine did not. Phenylephrine significantly increased uterine vascular resistance when compared with NS-control, but ephedrine did not. As a result, fetal pH and PO2 were significantly greater during ephedrine infusion than during infusion of NS-control. Fetal pH was stable during ephedrine infusion, but it continued to decrease during phenylephrine infusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Epidural↗
PubMed1992

Does calcium chloride help restore maternal blood pressure and uterine blood flow during hemorrhagic hypotension in hypermagnesemic gravid ewes?

Magnesium sulfate worsens maternal hypotension and fetal oxygenation during hemorrhage in gravid ewes. The purpose of this study was to determine whether calcium chloride administration is a useful adjunct to blood transfusion during hemorrhagic hypotension in hypermagnesemic gravid ewes. Sixteen experiments were performed in eight chronically instrumented animals between 0.8 and 0.9 of timed gestation. The experimental sequence included (a) T = 0: magnesium sulfate 4 g IV; (b) T = 5: infusion of magnesium sulfate 4 g/h IV; (c) T = 90: maternal hemorrhage 20 mL/kg over 55 min; (d) T = 147: calcium chloride 10 mg/kg or normal saline (NS-control) 0.1 mL/kg IV; (e) T = 160: transfusion of collected maternal blood over 55 min. Magnesium sulfate alone slightly decreased maternal mean arterial pressure (P = 0.002) and increased uterine blood flow (P = 0.0001) in both groups before hemorrhage. During hemorrhage, maternal mean arterial pressure, cardiac output, and uterine blood flow, and fetal PO2 and pH all decreased sharply (P = 0.0001). Cardiac output increased (P = 0.0005) modestly just after the intravenous bolus of calcium chloride. Maternal mean arterial pressure was significantly higher (P = 0.03) during transfusion in the calcium chloride group than in the NS-control group, but only after mean arterial pressure was near baseline measurements. Maternal uterine blood flow and fetal PO2 and pH responses over time were similar in the two groups. We conclude that intravenous administration of calcium chloride (10 mg/kg) transiently increased cardiac output during hemorrhagic hypotension and slightly increased mean arterial pressure during transfusion in hypermagnesemic gravid ewes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Does magnesium sulfate alter the maternal cardiovascular response to vasopressor agents in gravid ewes?

Magnesium sulfate (MgSO4) attenuates the maternal compensatory response to hemorrhage in gravid ewes, perhaps by decreasing the response to endogenous vasopressors. The purpose of this study was to determine whether MgSO4 alters the cardiovascular response of gravid ewes to vasopressor agents. Sixteen gravid ewes underwent a series of experiments consisting of administration of two exogenous and two endogenous vasopressors, each with and without a concurrent MgSO4 infusion. Dose-response curves were constructed for phenylephrine (an alpha 1-adrenergic agonist), ST-91 (an alpha 2-adrenergic agonist), angiotensin II, and arginine vasopressin (AVP). MgSO4 significantly attenuated the increase in maternal mean arterial pressure and systemic vascular resistance and the decrease in cardiac output during ST-91 infusion but not during phenylephrine, angiotensin II, or AVP infusions. MgSO4 significantly attenuated the increase in uterine vascular resistance during phenylephrine, ST-91, and angiotensin II infusions and the decrease in uterine blood flow during phenylephrine and angiotensin II infusions. MgSO4 also appeared to attenuate the decrease in uterine blood flow during ST-91 infusion (P = 0.067). The present study suggests that MgSO4 antagonizes the effects of alpha 1-adrenergic agonists, alpha 2-adrenergic agonists, and angiotensin II on the uterine vasculature, thus providing a level of protection for the fetus in situations of maternal stress.

Angiotensin II↗
PubMed1991

Recurrent outbreaks of Japanese encephalitis in Nagaland (1985-1989)--a seroepidemiological study.

Recurrent epidemics of encephalitis in Nagaland, a North-Eastern State of India, following its first appearance in 1985, were investigated both epidemiologically and virologically. Although, no viral agent could be isolated from any of the clinical samples and mosquitoes, detection of JE specific IgM antibodies in many of the CSF and acute blood samples, together with presence of HI and CF antibodies to JE antigen in a number of acute and convalescent sera established the etiologic role of JE virus in this region. A total number of 83 clinically diagnosed cases could only be investigated virologically between 1985-89, where evidence of JE could be established in 34 (40.9 per cent) and flavivirus (including JE in majority) in 17 (21.5 per cent) cases. A limited serological survey among the close contacts of the victims in 1985 revealed JE antibody in 26.6 per cent of them. Analysis of the epidemiological and serological findings of different years revealed that while the outbreaks of 1985, 1987 and 1988 were due to JE infection, the episodes of 1986 and 1989, on the other hand, had chiefly features of high and prolonged fever with limited number of CNS involvement of undetermined origin, where the possibility of malarial infection has been a suspect apart from JE etiology.

Adolescent↗
PubMed1991

Insulin sensitivity is increased in Friend erythroleukemia cells enriched in polyunsaturated fatty acid.

Increases in membrane lipid unsaturation and drug-induced increases in membrane fluidity have been shown to be associated with increases in insulin receptor concentration in animals, cultured cells, and liposomes. In the current study, we have examined the effect of increased membrane fatty acid unsaturation on insulin action. Friend Erythroleukemia cells were grown with exogenous polyunsaturated fatty acids for three days. After growth in medium supplemented with fatty acids, the unsaturation index of the phospholipids increased from 1.08 to 1.92, and this was associated with a significant decrease in anisotropy, as measured by fluorescence polarization. When measured at 15 degrees C, insulin receptor number rose from 9000 to 22,000 per cell with increased fatty acid unsaturation. The affinity for insulin in the polyunsaturated fatty acid treated cells decreased, however, resulting in similar amounts of insulin binding at low insulin concentrations but more binding at high insulin concentrations when compared to control cells. In contrast, binding of IGF-I was not influenced by increased membrane fatty acid unsaturation. When measured at 37 degrees C there were no changes in binding of insulin or IGF-I. Internalization of insulin was identical in control cells and in cells with increased membrane fatty acid unsaturation. Thymidine incorporation, an insulin-dependent function in these cell, was measured in control and fatty acid treated cells. In control cells, insulin increased thymidine incorporation by 80%, with an ED50 of about 5 nM. In cells treated with polyunsaturated fatty acids, the insulin stimulated thymidine incorporation was slightly higher and the ED50 was about 0.2 nM. In contrast, there was no increase in the sensitivity or responsiveness of fatty acid treated cells to IGF-I. We conclude that increased membrane fatty acid unsaturation greatly influences insulin binding and biological sensitivity, but not that of IGF-I. At low insulin levels, there was a greater insulin bioeffectiveness, despite the same or lower insulin binding, suggesting more efficient coupling of the insulin-effector complex.

Animals↗
PubMed1989

Chronic effect of smoking on the electrocardiogram.

The electrocardiograms (ECG) of 232 male non-smokers and 224 male smokers, aged 20-60 years, devoid of cardiovascular diseases, were studied. Among these subjects 5.2% of non-smokers and 6.7% of smokers had pathological ECGs. Non-pathological ECGs of 220 non-smokers and 209 smokers were analyzed for R, S and T-wave amplitudes, P and QRS axes and P-R, QRS and Q-Tc intervals. The 2 groups did not differ significantly from each other for R and T-wave amplitudes in any of the age groups except for 40-60 years, in which R-amplitude obtained from standard limb leads was significantly lower in smokers. S-amplitude recorded from standard limb leads was significantly lower in smokers of all ages combined. The reverse phenomenon was noted for S-amplitude obtained from precordial leads. R, S and T-amplitudes decreased with the advancement of age at a relatively higher rate in smokers. These waves had significant negative correlation with pack years of smoking habit. QRS and P axes differed significantly between smokers and non-smokers. The rate of shifting of these axes to the left with increasing age was relatively higher in non-smokers. Lung function did not show any relation to electrocardiogram in normal healthy subjects. These results indicate that aging affects electrocardiographic wave patterns and that this aging effect is modified by long term smoking.

Adult↗
PubMed1988

Capacity of aquatic bacteria to act as recipients of plasmid DNA.

A total of 68 gram-negative freshwater bacterial isolates were screened for their ability to receive and express plasmids from Pseudomonas aeruginosa donors. The plate mating technique identified 26 of the isolates as recipient active for the self-transmissible wide-host-range plasmid R68; 10 were recipient active by R68 mobilization for the wide-host-range plasmid cloning vector R1162. Frequencies of transfer were compared by using three conjugal transfer procedures: broth, plate, and filter mating. For every recipient tested, a solid environment was superior to a liquid environment for transfer. The broth mating technique failed to demonstrate R68 transfer in 63% of the recipient-active isolates. Filter mating, in general, yielded the highest transfer frequencies. The more-rapid plate mating procedure, however, was just as sensitive for testing the capacity of natural isolates to participate in conjugal plasmid transfer.

Conjugation, Genetic↗