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Biomedical subjects

M Chatterjee

Publications and source records attributed to M Chatterjee.

At least 145 records · Page 8Linked to original sources
PubMed1989

An unusual case presentation. Cellular schwannoma in pregnancy: an unusual cause of low back pain.

A cellular schwannoma is a benign hypercellular variant of a peripheral nerve sheath tumor. It usually arises in the posterior roots of the neck, mediastinum or pelvis. It produces neurologic symptoms by direct pressure on neural elements, local swelling and/or tissue necrosis. In general, the rate of progression of symptoms will determine the need for surgical intervention, which consists of total local excision. We present the first reported case of a cellular schwannoma in pregnancy; the main symptom was intractable low back pain.

Adult↗
PubMed1988

Effect of amiloride on regulatory mechanisms of vascular smooth muscle contraction.

Experiments were conducted to characterize the effects of amiloride on the regulatory mechanisms of vascular smooth muscle contraction. Intact, saponin-skinned and A23187-treated strips of rabbit aorta were used for these studies. Amiloride significantly (P less than 0.05) reduced the norepinephrine bitartrate (NE)-stimulated increase in intracellular Ca2+ in intact arteries. In saponin-skinned arteries, amiloride depressed both stress and concomitant levels of myosin light chain phosphorylation. This inhibition of stress appeared to be competitive with MgATP. In A23187-treated preparations, where the effects of amiloride were studied at physiological [MgATP] in the absence of functional membrane Ca2+-channels, amiloride caused a reduction in both stress and myosin light chain phosphorylation. In other experiments on intact arteries, the contractile response to phorbol 12,13-dibutyrate, an activator of protein kinase C, was reduced by amiloride. We conclude that the vasorelaxant effects of amiloride are mediated via inhibition of myosin light chain kinase and protein kinase C, in addition to the inhibition of Ca2+ influx.

Adenosine Triphosphate↗
PubMed1988

Phorbol 12,13-dibutyrate, an activator of protein kinase C, stimulates both contraction and Ca2+ fluxes in dog saphenous vein.

The vascular effects of phorbol 12,13-dibutyrate (PDBu) were studied in the dog saphenous vein. PDBu (1 microM) caused contraction (0.58 +/- 0.22 g/mg wet wt.) and Ca uptake (74.2 +/- 41.2 mumol/kg wet wt.) which were unaffected by 10 microM phentolamine (N = 6). The PDBu-induced contraction was greatly (60-80%) inhibited in Ca2+-free solution. 45Ca efflux measurements performed in Ca2+-free solution showed that PDBu did not cause Ca release from intracellular storage sites. The contractile response to PDBu (1 nM-1 microM) was significantly correlated with the magnitude of Ca uptake; contraction and the rise in tissue Ca2+ also had a similar time course. Correlation between the two measures persisted when the responses to PDBu were augmented by co-administration with 20 mM KCl. However, no synergism occurred between the two agonists. Both the contraction and Ca uptake responses to PDBu were reduced by nifedipine and verapamil, each at 1 microM. In the Triton X-100 skinned saphenous vein, where the voltage-dependent Ca channel is not functional, 10 microM PDBu did not cause contractions in the presence of 0.1 microM Ca2+. Thus, contraction of the intact saphenous vein by PDBu characteristically exhibits great Ca dependence and PDBu seems to activate the voltage-dependent Ca channel, presumably through stimulation of protein kinase C; the ensuing Ca entry is primarily responsible for contraction. However, the mechanism responsible for the PDBu-induced contractions that are resistant to Ca2+-free PSS or Ca entry blockers remains to be defined.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Preparation and evaluation of technetium-99m labeled cardiac glycoside derivatives as potential myocardial imaging agent.

Three cardiac glycosides, two natural, cymarin and convallotoxin and one synthetic, strophanthidin-beta-D-glucoside were converted to their thiosemicarbazone and subsequently radiolabeled with 99mTc by chelation. The resulting radioactive chelate complexes were evaluated in animals to determine the suitability of this class of compounds for myocardial imaging. It was observed from the animal biodistribution data of the three radioactive compounds, there was a considerable variation in the heart to non-target organ uptake ratio. A possible explanation of this variation was offered in the light of their lipophilic character, protein binding ability and affinity towards non-target receptors. It is anticipated that this study may help to develop a 99mTc-cardiac glycoside complex with better distribution characteristics, and such a compound may offer a suitable alternative to 201Tl, which is at present used for myocardial imaging.

Animals↗
PubMed1987

Intrapartum suctioning of meconium: comparative efficacy of bulb syringe and De Lee catheter.

Intrapartum suctioning of the newborn's pharynx with a De Lee catheter (DL) has reduced the incidence of meconium aspiration syndrome (MAS) in neonates born with meconium staining of the amniotic fluid. However, the bulb syringe (BLB) is used more often for this purpose because of greater technical convenience. In a prospective study, 60 offspring of such deliveries received intrapartum pharyngeal suctioning either by BLB (29 cases) or by DL (31 cases), according to random selection. The presence and amount of meconium in the trachea, incidence and severity of MAS, and mortality from the disease were similar between the two groups. This study suggests that the BLB is as effective as the DL for intrapartum removal of nasopharyngeal meconium in deliveries with meconium staining of the amniotic fluid. Since the BLB is easier to use, less expensive and probably safer, our results suggest that it may be the preferable method.

Amniotic Fluid↗
PubMed1986

In utero-exposure to saccharin: a threat?

In-utero or immediate post-utero exposure of rats to saccharin results in an increased incidence of bladder tumors when compared to post-weaning exposure only. We studied 6 human mother-infant pairs following maternal intake of saccharin close to delivery. High performance liquid chromatography revealed the presence of saccharin in all 6 newborn cord sera as well as their mothers' sera and urine. This constitutes the first report of placental transfer of saccharin in humans. Despite the relative weakness in carcinogenicity of saccharin, this in-utero exposure, coupled with ex-utero exposure, may possibly contribute to an increased incidence of neoplasms.

Adult↗
PubMed1986

Phorbol ester-induced contraction in chemically skinned vascular smooth muscle.

We studied the contractile response to phorbol esters and its relationship to myosin light chain phosphorylation in intact and Triton X-100-skinned porcine carotid preparations. Muscle contraction was activated by phorbol 12,13-dibutyrate (PDBu) and phorbol 12,13-didecanoate (PDD). Dose-dependent contractions to PDBu were obtained both in the intact and skinned preparations. The maximal values of stress in response to PDBu were 1.11 +/- 0.10 X 10(5) N/m2 (n = 7) in the intact and 5.72 +/- 0.59 X 10(4) N/m2 (n = 10) in the skinned muscles. The skinned tissues responded to PDD, which has been shown to activate protein kinase C, but not to the inactive isomer 4 alpha-PDD, thus ruling out nonspecific phorbol effects. The phorbol ester response exhibited a Ca2+ dependence. High stresses in the skinned muscles (5.53 +/- 0.69 X 10(4) N/m2, n = 8) were associated with low values of myosin light chain phosphorylation (0.18 +/- 0.01 mol Pi/mol light chain, n = 8). Thus phorbol esters can contract vascular smooth muscle by a mechanism that is not proportional to myosin light chain phosphorylation and that may involve activation of protein kinase C.

Animals↗
PubMed1984

Beta-carotene inhibition of 7,12-dimethylbenz[a]anthracene-induced transformation of murine mammary cells in vitro.

The chemopreventive action of beta-carotene during chemically-induced transformation of the epithelial cells in organ culture of the whole mammary glands from BALB/c female mice was studied. The mammary epithelial cells in the whole mammary organ in a hormone supplemented, serum-free medium were transformed after 24 h exposure to 7.8 microM 7,12-dimethylbenz[a]anthracene (DMBA) between 3rd and 4th day of a total 10 day culture period. The transformation process was associated with appearance of nodule-like alveolar lesions (NLAL) in glands in vitro. The epithelial cells transformed by DMBA are potentially neoplastic, and NLAL serves as a morphological marker of preneoplasia in the glands in vitro. Treatment with beta-carotene (10(-6) M) during DMBA exposure (3rd-4th day) caused 68% inhibition in the number of glands with incidence of NLAL. A 49% inhibition of NLAL was evident when the glands were incubated with beta-carotene (days 4-10) after exposure to DMBA. Results indicate that beta-carotene inhibits DMBA-induced transformation of the mammary glands in vitro acting both at the initiation and the promotional stages. This inhibitory effect is likely due to the action of beta-carotene itself since no accumulation of retinol, the metabolic derivative of the vitamin A precursor, was detectable in the mammary glands during the 10 day culture period.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1983

Calcium-dependent stress maintenance without myosin phosphorylation in skinned smooth muscle.

Stress development depended on calcium-stimulated myosin phosphorylation in an arterial smooth muscle preparation in which the concentration of calcium was controlled. However, developed stress was maintained at a concentration of calcium that did not support phosphorylation. These results, in conjunction with other evidence, suggest that the interaction of two regulatory mechanisms with different calcium sensitivities regulate both stress and the rate and energetics of contraction.

Animals↗
PubMed1983

Lysine production from hydrocarbon by Micrococcus varians 2Fa.

A bacterium isolated from Assam (India) soil was found to accumulale l-lysine from hydrocarbon and was identified as a strain of Micrococcus varians. The strain is able to grow and accumulate lysine in a purely synthetic medium though supplementation of the synthetic medium with casamino acids significantly improves the yield. The yield of l-lysine under optimal conditions was found to be 2.6 g X 1(-1) of the compound isolated in crystalline form.

Alkanes↗