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Biomedical subjects

A Raut

Publications and source records attributed to A Raut.

8 recordsLinked to original sources
PubMed2004

Inhibition of type A GABA receptors by L-type calcium channel blockers.

Modulation of type A GABA receptors (GABAA) by L-type Ca++ channel blockers was investigated. The dihydropyridines nifedipine and nitrendipine, and the phenylalkylamine verapamil inhibited recombinant rat alpha1beta2gamma2 receptors recorded from human embryonic kidney (HEK) 293 cells; nifedipine at low concentrations also elicited modest stimulatory effects on GABA-gated current. The IC50 for GABA current inhibition was lowest for nitrendipine (17.3 +/- 1.3 microM), so subsequent studies were focused on further exploring its mechanism and possible site of action. When co-applied with GABA, nitrendipine had minimal effects on initial current amplitude, but significantly enhanced current decay rate. Nitrendipine-mediated inhibition was subunit-selective, as its IC50 was 10-fold lower in alpha1beta2 receptors. Nitrendipine's effect in recombinant human alpha1beta2gamma2 receptors was similar (IC50=23.0 +/- 1.3 microM) to that observed in rat receptors of the same configuration, indicating the site of action is conserved in the two species. The inhibitory effects were dependent on channel gating, were independent of transmembrane voltage, and were also observed in GABAA receptors recorded from hypothalamic brain slices. The pharmacologic mechanism of inhibition by nitrendipine was non-competitive, indicating it does not act at the GABA binding site. Nitrendipine block was retained in the presence of the benzodiazepine antagonist flumazenil, indicating it does not interact at the benzodiazepine site. The actions of nitrendipine were not affected by a mutation (beta2T246F) that confers resistance to the channel blocker picrotoxin, and they were not altered in the presence of the picrotoxin site antagonist alpha-isopropyl-alpha-methyl-gamma-butyrolactone, demonstrating nitrendipine does not act at the picrotoxin site of the GABAA receptor. Possible interaction of nitrendipine with the Zn++ site was also eliminated, as mutation of beta2 H267 to A, which confers resistance to Zn++, had no effect on nitrendipine-mediated inhibition. Our data suggest some of the central effects of dihydropyridines may be due to actions at GABAA receptors. Moreover, the effects may be mediated through interaction with a novel modulatory site on the GABAA receptor.

4-Butyrolactone↗
PubMed2001

Sequelae and complications related to dental extractions in patients with hematologic malignancies and the impact on medical outcome.

OBJECTIVE: The purpose of this retrospective study was to evaluate sequelae and complications after dental extractions and to analyze their impact on medical treatment in patients with myelodysplastic syndrome, acute and chronic leukemia, and multiple myeloma during a 3-year period. STUDY DESIGN: The study population included 388 patients with hematologic malignancies. All medical and dental charts were reviewed in a retrospective fashion to identify patients who received dental extractions. Preexisting dental disease and intervention (extraction) were evaluated, and parameters such as days of hospitalization and survival rate were compared with those of the remainder population who did not receive dental extractions. RESULTS: Of the 388 patients, 69 underwent dental extractions and 9 had sequelae and complications after the intervention. The resulting complication rate of 13% was reported. Although some patients did experience delay of chemotherapy or bone marrow transplant (BMT), or both, no significant difference was found in the number of days in the hospital for BMT and the survival rate for the patients with sequelae and complications (n = 9) and for the remainder population (n = 319) ( >.05). CONCLUSION: Dental extraction intervention provided in the prechemotherapy and pre-BMT time frame did not have a negative bearing on medical outcome.

Acute Disease↗
PubMed2001

Development of a thermoresistant tissue culture rinderpest vaccine virus.

The currently used Plowright's tissue culture rinderpest vaccine (RBOK strain) gives full protection and lifelong immunity, but it is highly thermolabile and requires maintenance of cold chain from vaccine production till delivery. Keeping in view the need for a thermostabile vaccine in tropical developing countries with limited refrigeration facilities, we passaged serially the RBOK strain of rinderpestvirus (RPV) at gradually elevated temperature up to 40 degrees C to obtain a thermoresistant RPV (TR-RPV) mutant. The thermoresistance (thermostability) and antigenicity of TR-RPV were compared with those of the vaccine virus by various methods, confirming the acquired properties. Thus, the infectivity titres of the TR-RPV mutant and vaccine virus were determined after incubation for various times at 37 degrees C. Regression analysis indicated that TR-RPV had a half-life of 1.81 hr and a degradation constant of 0.1656, while the parent vaccine virus had a half-life of 1.11 hr and a degradation constant of 0.2686. In capture ELISA with four different monoclonal antibodies (MAbs) to the N protein of RPV, TR-RPV showed a 10-fold higher reactivity with one MAb as compared to the vaccine virus. Although TR-RPV did react also with the other three MAbs, its reactivity was only 4-5 times higher than that of the vaccine virus. A treatment of the virus with Triton X-100 resulted in 2-4 times higher reactivity with the MAbs. The 35S-methionine-labeled vaccine virus-and TR-RPV-infected Vero cell lysates showed 6 polypeptide bands with identical pattern of migration in polyacrylamide gel electrophoresis in the presence of SDS (SDS-PAGE). Radioimmunoprecipitation assay (RIPA) of the TR-RPV and vaccine virus with a rabbit anti-RPV immune serum (RHIS) and bovine anti-RPV hyperimmune serum (BHIS) showed the presence of four identical antigenic proteins, namely H, N, F and M, for both viruses. It can be concluded that TR-RPV has indeed retained the antigenic properties of the parental vaccine virus besides acquiring thermoresistance.

Animals↗
PubMed2000

Unusual gingival presentation of post-transplantation lymphoproliferative disorder: a case report and review of the literature.

Post-transplantation lymphoproliferative disorder is a well-documented complication of solid organ or bone marrow transplantation. Histologically, it is characterized by an abnormal proliferation of lymphocytes, which can range from benign B-cell hyperplasia to malignant lymphoma. Non-Hodgkin's lymphoma (NHL) is associated with several risk factors, such as congenital or acquired immunodeficiency states, autoimmune disorders, and infectious agents (eg, Epstein-Barr virus). Primary sites of presentation in the head and neck are Waldeyer's ring, paranasal sinuses, salivary glands, the oral cavity, and the larynx. Clinical appearance of gingival NHL varies but is usually found to be an asymptomatic gingival enlargement or mass resembling a pyogenic granuloma. We present a patient with a gingival ulceration that was subsequently diagnosed as Epstein-Barr virus malignant lymphoma resulting from the immunosuppression needed to prevent graft-versus-host disease after bone marrow transplantation.

Adult↗
PubMedDate not supplied

Hemoperitoneum complicating snake bite: rare CT features.

Russels's viper bite victims with systemic poisoning may present with hemorrhagic manifestations, including spontaneous bleeding and incoagulable blood associated with disseminated intravascular coagulation and primary fibrinolysis, two of the most prominent manifestations of the systemic envenoming by this species. Various vascular complications of viperine snake bite have been reported in the literature. We report the computed tomographic findings in a case of snake bite resulting in hemoperitoneum, which, to the best of our knowledge, has not been reported in the literature.

Adult↗