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Biomedical subjects

B S Sharma

Publications and source records attributed to B S Sharma.

At least 55 records · Page 3Linked to original sources
PubMed1993

Value of precraniotomy shunts in children with posterior fossa tumours.

Seventy children with posterior fossa tumours treated over a period of 6 1/2 years were studied. Most patients presented in the late stage of disease. Sixty-four required insertion of a precraniotomy shunt for one or more of the following: persistent vomiting, severe headache, dehydration, poor general condition, failing vision, altered sensorium, marked periventricular lucency, and brain stem involvement deferring total removal of the tumour. Insertion of precraniotomy shunt improved the general condition and signs and symptoms of increased intracranial pressure. It also provided a lax brain during definitive surgery and a smooth postoperative course. Shunt-related complications, consisting of block and/or infection, were observed in 21 patients. It was concluded that precraniotomy shunt is important in the management of children with posterior fossa tumours in developing countries where these patients present in the late stage of disease.

Adolescent↗
PubMed1993

Complete dislocation with burst fracture of the lower cervical spine. Case report.

A patient with a complete fracture dislocation of the C6 vertebra without any neurological deficit is presented. The absence of neurological changes in an area of the spinal canal which is almost completely filled with the spinal cord is remarkable. The mechanism of injury in this patient is believed to be hyperextension associated with significant axial loading. Hyperextension first ruptured the anterior and the posterior longitudinal ligaments and then injured the pedicles of C6. The associated axial loading resulted in a 'bursting' of the posterior elements, thereby providing room for the spinal cord to move dorsally with the avoidance of a major neurological deficit.

Accidental Falls↗
PubMed1993

Multicentric gliomas: report of 2 cases.

Two cases of multicentric gliomas with long survival are reported. One patient underwent multiple surgical procedures while another had two separate surgical procedures at the same time. Presence of calcification of CT scan in one case raised suspicion for a preoperative diagnosis of oligodendroglioma. Lack of direct continuity or subarachnoid enhancement on CT scan and low histological grade of the tumours suggested their primary multicentric origin. The incidence of multicentric gliomas in our experience is 0.4% amongst 500 glial tumours over a period of eight years.

Adult↗
PubMed1993

Posterior fossa extradural haematoma--experience of nineteen cases.

Twenty-four cases of posterior fossa extradural haematoma constituted 4.16% of all extradural haematomas (576) and 1.12% of all craniocerebral trauma requiring surgery (2150). Five cases were excluded from this study. Of the remaining nineteen cases (the study group), lucid interval was present in eight (42.10%) cases. In half of the cases, the clinical course was acute. Neck stiffness and drowsiness were the commonest clinical signs. Occipital bone fracture was present in 57.89% cases. CT scan was the most valuable investigation in the diagnosis and detection of the associated intracranial injury in 18 cases. Associated intracranial injury was present in seven (36.84%) of these cases. Two (11.1%) of these patients died despite emergency surgery. The Glasgow Coma Scale prior to operation and the presence of associated supratentorial injuries were important prognostic factors. It is concluded that posterior fossa extradural haematoma should be suspected in the presence of a fall on the back of the head, drowsiness, neck stiffness or an occipital bone fracture.

Adolescent↗
PubMed1992

Intracranial olfactory neuroblastoma: evidence for olfactory epithelial origin.

AIMS: To determine the possible histogenesis of the intracranial variant of olfactory neuroblastoma. METHODS: Four specimens from three cases of intracranial olfactory neuroblastoma were studied by light microscopy and immuno-histochemistry, and electron microscopy in two cases. RESULTS: Light microscopical examination showed small cell tumour with additional features of epithelioid cells in one case and ganglion cells in another. Olfactory and Homer-Wright rosettes were present. All the specimens showed a uniform positive reaction to neurone specific enolase, S-100, and cytokeratin antibodies. Glial fibrillary acidic protein was absent. The salient electron microscopic features were the presence of cell junctions, cytoplasmic intermediate filaments, basal bodies and cytolasmic processes. Dense cored vesicles were absent. CONCLUSIONS: The results strongly support the view that intracranial olfactory neuroblastomas are of olfactory epithelial origin and differ from conventional neuroblastomas.

Adult↗
PubMed1992

Immunomodulatory activity of a novel nucleoside, 7-thia-8-oxoguanosine: I. Activation of natural killer cells in mice.

We reported recently that a novel immunomodulator, 7-thia-8-oxoguanosine (7T8OG)2 inhibited formation of pulmonary melanoma metastases (1), prevented against viral infection in mice (2) and potentiated the efficacy of a weakly immunogenic leukemia vaccine (3). Since certain tumor metastases and virus infected cells are targets to natural killer cells (NK cells), we now investigated whether 7T8OG is capable of activating NK cells in mice using NK cell sensitive YAC-1 and B16 and NK cell insensitive P815 targets. CBA/CaJ spleen cells incubated in vitro with 7T8OG at concentrations ranging from 0.005 to 0.5 mM responded with increased NK cell activity (32-62%) compared to controls (4-8%) to YAC-1 targets. Similar levels of augmentation in NK cell activity were observed when 40-168 mg/kg of 7T8OG was administered in vivo. In addition to the spleen, 7T8OG activated NK cells in the bone marrow (BM), the lungs, the liver, and in peritoneal exudate cells (PE). Although 7T8OG elicited activation of NK cells was observed as early as three hours after treatment, the maximal activity was observed after 24 h in the spleen; 12 h in the BM; 48 h in the lungs, and 72 h in PE. Administration of the drug by s.c., i.v., and i.p. routes all induced activation of NK cells in spleen, BM and PE. 7T8OG was found to activate NK cells in seven inbred and an outbred mouse strain, suggesting that the induced cytotoxicity against allogeneic and syngeneic tumor cells is not strain specific as well as independent of MHC restriction. C3H/He, CBA/CaJ and BDF/1 displayed higher levels of increased NK cell activity, whereas AKR mice were low responders. Low concentrations of IL-2 (0.25-5 U/ml) that induce little or no NK cell activity, when used in combination with 7T8OG, elicited significant enhancement of NK cell cytotoxicity. In contrast, IFN and 7T8OG showed no such synergism.

Adjuvants, Immunologic↗
PubMed1992

Immunomodulatory activity of a novel nucleoside, 7-thia-8-oxoguanosine. II. Characterization of induced effector cells and the mechanism of induction.

In a preceding paper we characterized the in vivo and in vitro induction of cytotoxic effector cells elicited by a novel synthetic immuno-stimulator 7-thia-8-oxoguanosine (7T8OG)2. In the present study we further characterized the cells responsible for the induced cytotoxicity and the mechanisms together with the lymphokines mediating the immunological response to 7T8OG. Removal of macrophages from 7T8OG activated spleen cell suspensions by various methods resulted in a significant increase in cytotoxicity to YAC-1 targets. 7T8OG induced effectors did not exert cytotoxic effect on macrophage sensitive P815 target cells. In vivo activated effectors when incubated with anti-asialo-GM1 antibody plus complement lost completely their ability to lyse YAC-1 targets. Together, these findings indicate that the 7T8OG induced effector cells are not macrophage like. Spleen cells from nude mice were readily activated by 7T8OG. The induced effectors were resistant to complement mediated lysis using anti-L3T4, anti-Lyt1 or anti-Lyt2 antibodies. Pretreatment of spleen cells with macrophage depleting agents both, in vitro and in vivo and subsequent activation of cells by 7T8OG resulted in effectors with reduced cytotoxicity. When injected in vivo, 7T8OG induced strong IFN production which paralelled the kinetics of NK cell activation. Furthermore, antibodies to alpha & beta-IFN but not to gamma-IFN diminished the induction of the cytotoxic activity. Although these findings suggest that activation of NK cells by 7T8OG is most likely to be mediated by alpha & beta-IFN involvement of other cytokines can not be ruled out.

Adjuvants, Immunologic↗
PubMed1991

Potentiation of the efficacy of murine L1210 leukemia vaccine by a novel immunostimulator 7-thia-8-oxoguanosine: increased survival after immunization with vaccine plus 7-thia-8-oxoguanosine.

We have investigated the ability of a novel immunopotentiator, 7-thia-8-oxoguanosine (7T8OG) to increase the efficacy of a weakly immunogenic murine L1210 leukemia vaccine. The vaccine was prepared by irradiating L1210 leukemia cells in a cesium source with a total of 6000-R dose. DBA/2 mice were treated with 150 mg/kg 7T8OG and/or with vaccine consisting of 10(7) irradiated cells. In combination therapy, mice first received the vaccine and then were injected with 75 mg/kg 7T8OG 2 h and 4 h after vaccination. One week after the last treatment all mice were inoculated with 10(4) live leukemia cells intraperitoneally. Control, untreated mice (n = 66) injected with 10(4) live leukemia cells had a mean survival time +/- standard error of 10.5 +/- 0.2 days. Treating mice (n = 66) with one, two or three doses of 7T8OG administered i.p. 1 week apart did not increase survival (mean survival time = 10.7 days). Mice immunized with one, two or three doses of vaccine had 14.5 +/- 1.1, 45.4 +/- 6.2 and 68.3 +/- 10.6 days mean survival, respectively. 7T8OG-stimulated vaccination increased the survival dramatically. The best survival was noted when the mice were treated with 2x (vaccine + 7T8OG). Immunization of mice (n = 30) with this treatment regimen increased the mean survival to 156 +/- 10.0 days. Over 90% of mice that were treated this way had a cumulative survival time greater than 160 days. In contrast, only 12% of the mice immunized twice with the leukemia vaccine alone survived over 160 days. These results suggest a rationale for the use of this immuno-potentiator with various vaccines for a more effective immunization.

Adjuvants, Immunologic↗
PubMed1991

Immunoenhancing properties and antiviral activity of 7-deazaguanosine in mice.

The nucleotide analog 7-deazaguanosine has not previously been reported to possess biological (antiviral or antitumor) properties in cell culture or in vivo. Up to 10(5) U of interferon per ml was detected in mouse sera 1 to 4 h following oral (200-mg/kg of body weight) and intraperitoneal (50-mg/kg) doses of the compound. 7-Deazaguanosine also caused significant activation of natural killer and phagocytic cells but did not augment T- and B-cell blastogenesis. Intraperitoneal treatments of 50, 100, and 200 mg/kg/day administered 24 and 18 h before virus inoculation were highly protective in mice inoculated with lethal doses of Semliki Forest or San Angelo viruses. Less but still significant survivor increases were evident in treated mice infected with banzi or encephalomyocarditis viruses. In most cases, the degree of antiviral activity was similar to that exhibited by the biological response modifier 7-thia-8-oxoguanosine. 7-Thia-8-oxoguanosine was more potent than 7-deazaguanosine against encephalomyocarditis virus in mice, however. Oral efficacy was achieved with 7-deazaguanosine treatments of greater than or equal to 100 mg/kg against all virus infections, whereas 7-thia-8-oxoguanosine is reported to be devoid of oral activity in rodents. Thus, 7-deazaguanosine represents the first reported orally active nucleoside biological response modifier exhibiting broad-spectrum antiviral activity against particular types of RNA viruses.

Adjuvants, Immunologic↗
PubMed1991

Hemangioma of the temporalis muscle.

A rare case of an intramuscular hemangioma of the temporalis muscle is reported. The clinical examination, carotid arteriogram, computed tomographic scan, and aspiration cytology suggested the vascular nature of the tumor, but an exact diagnosis could only be made after histopathologic examination. Temporary occlusion of the ipsilateral external carotid artery and subperiosteal dissection permitted complete, wide excision without much bleeding.

Adult↗
PubMed1990

Inhibition of pyrimidine metabolism in myeloid leukemia cells by triazole and pyrazole nucleosides.

Two triazole nucleosides, 1 (3-beta-D-ribofuranosyl-1,2,4-triazole-5-carboxamide) and 2 (2-beta-D-ribofuranosyl-1,2,3-triazole-4,5-dicarboxamide), and a pyrazole nucleoside, 3 (1-beta-D-ribofuranosylpyrazole-3,4-dicarboxamide), were found to inhibit pyrimidine nucleotide biosynthesis in the human myeloid leukemia cell line, K562. Cells treated with these inhibitors released orotate in quantities of 8-35 nmol/10(5) cells/day. Treatment with these compounds caused the K562 cells to accumulate in the S phase of the cell cycle and induced the cells to synthesize hemoglobin.

Adenosine Triphosphate↗
PubMed1990

Controversies in the management of subdural empyema. A study of 41 cases with review of literature.

Forty one cases of subdural empyema treated between 1977 and 1988 at the Postgraduate Institute of Medical Education and Research. Chandigarh, have been analysed. The patients ranged from 9 days to 80 years of age. There were 22 children, including 11 infants. Fever, altered sensorium and seizures were the most common symptoms present for 1 day to 6 months. Otogenic infection was the commonest aetiological factor followed by postoperative and posttraumatic causes. Thirty seven patients had supratentorial empyemas, including 4 with parafalcine collections, three had infratentorial empyemas, and in one there was extension of the empyema from the supratentorial to the infratentorial compartment. Therapeutic modalities used included percutaneous needle aspirations in infants and burr hole evacuation and craniotomies in adults. A wide spectrum of organisms was detected. Mortality in this series was 24%, which was mainly attributable to the deteriorated neurological status prior to treatment. A detailed review of the literature has been given, highlighting various controversies in the management of SDE. Important prognostic factors and a treatment plan are suggested.

Adolescent↗
PubMed1990

Roles of interferon and natural killer cells in the antiviral activity of 7-thia-8-oxoguanosine against Semliki Forest virus infections in mice.

7-Thia-8-oxoguanosine is a novel biological response modifier with broad-spectrum antiviral activity against many DNA and RNA viruses in vivo. Since two of its properties are to induce interferon and to activate natural killer (NK) cells, we investigated the roles of the lymphokine and NK cells in the antiviral activity of the compound against Semliki Forest virus. Antibody to interferon alpha/beta could completely abolish the protective activity of the nucleoside against virus infection in mice, whereas antibodies to interferons beta and gamma could not, indicating that interferon alpha was of major importance to confer protection to the animals. Reduced activation of NK cells was also observed in mice treated with 7-thia-8-oxoguanosine and antibody to interferon alpha/beta. The role of NK cells in the protective activity of the compound was directly assessed in beige mice or in Swiss Webster mice treated with asialo GM1 antibody. In both experiments, the animals were protected from lethal virus infection by treatment with nucleoside. Spleen cells primed by 7-thia-8-oxoguanosine and adoptively transferred to untreated mice could not save them from virus-induced mortality. These three results provide evidence that natural killer cells activated by 7-thia-8-oxoguanosine play a minimal role in protection from acute Semliki Forest virus infections in mice.

Animals↗