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Biomedical subjects

S C Sharma

Publications and source records attributed to S C Sharma.

At least 73 records · Page 4Linked to original sources
PubMed1998

Regeneration of ascending spinal axons in goldfish.

Regeneration of descending spinal cord tracts occur spontaneously in adult goldfish. Very little information is available regarding the fate of ascending fibers. Using Dextran amines as a tracer, we studied the normal and regenerated ascending axonal projection patterns in adult goldfish brain nuclei. Present study includes spinal projections to torus semicircularis, hypothalamus, thalamus and the telencephalon. Regenerated fibers had finer caliber axons and the terminal axonal arbors covered a larger area than the corresponding normal ones.

Afferent Pathways↗
PubMed1998

The patterns of retinal ganglion cell death in hypertensive eyes.

We have recently described a rat model of hypertensive eye in which cauterizing limbal derived episcleral veins leads to increase in the intraocular pressure [S.R. Shareef, E. Garcia-Valenzuela, A. Salierno, J. Walsh, S.C. Sharma, Chronic ocular hypertension following episcleral venous occlusion in rats, Exp. Eye Res. 61 (1995) 379-382.]. We have further documented that retinal ganglion cell death is apoptotic [E. Garcia-Valenzuela, S. Shareef, J. Walsh, S.C. Sharma, Programmed cell death of retinal ganglion cells during experimental glaucoma, Exp. Eye Res. 61 (1995) 33-44.]. Here, we describe the total loss of retinal ganglion cells at various time intervals following increased IOP. At early time points death of ganglion cells in the central, peripheral retina occurred with similar frequencies. Between 4-6 weeks after intraocular elevation, ganglion cells in the peripheral retina were more susceptible than the central retina. Percentage of total ganglion cell death over the 10 week period was presumably linear and was about 4% per week.

Animals↗
PubMed1998

Dose rate correction in medium dose rate brachytherapy for carcinoma cervix.

PURPOSE: To establish the magnitude of brachytherapy dose reduction required for stage IIB and III carcinoma cervix patients treated by external radiation and medium dose rate (MDR) brachytherapy at a dose rate of 220+/-10 cGy/h at point A. MATERIALS AND METHODS: In study-I, at the time of MDR brachytherapy application at a dose rate of 220+/-10 cGy/h at point A, patients received either 3060 cGy, a 12.5% dose reduction (MDR-12.5), or 2450 cGy, a 30% dose reduction (MDR-30), to point A and they were compared to a group of previously treated LDR patients who received 3500 cGy to point A at a dose rate of 55-65 cGy/h. Study-II was a prospective randomized trial and patients received either 2450 cGy, a 30% dose reduction (MDR-II (30)) or 2800 cGy, a 20% dose reduction (MDR-II (20)), at point A. Patients were evaluated for local control of disease and morbidity. RESULTS: In study-I the 5-year actuarial local control rate in the MDR-30 and MDR-12.5 groups was 71.7+/-10% and 70.5+/-10%, respectively, compared to 63.4+/-10% in the LDR group. However, the actuarial morbidity (all grades) in the MDR-12.5 group was 58.5+/-14% as against 34.9+/-9% in the LDR group (P < 0.05). Similarly, the grade III and IV morbidity also in the MDR-12.5 group was 12.5+/-9% as against 5.3+/-5% in the LDR group (P < 0.05). No statistically significant difference in morbidity was seen between the MDR-30 and LDR groups. In study-II the 3-year actuarial local control rate in the MDR-II (30) and MDR-II (20) groups was 66.6+/-10% and 74.8+/-9%, respectively. There was a significant correlation between the rectal BED received and the percentage of patients developing rectal morbidity. Only 10% of patients receiving a rectal BED of (100 < 120) Gy3 developed complication as against 62.5% of those receiving a rectal BED of (140 < 160) Gy3 (chi2 = 46.43; P < 0.001). CONCLUSION: We suggest that at a dose rate of 220+/-10 cGy/h at point A the brachytherapy dose reduction factor should be around 30%, as suggested by radiobiological data, to keep the morbidity as low as possible without compromising the local control rates.

Brachytherapy↗
PubMed1998

Clinical considerations in the use of missing tissue compensators for head and neck cases.

The irregular shape or contour of the patient's surface in the treatment field can alter the dose distribution resulting in non-uniformity of dose in the treatment volume. Missing tissue compensators have been most commonly used to improve this non-uniformity, especially in head & neck, breast, lung and supraclavicular regions. Two or three dimensional compensators have been typically designed to make the dose uniform at a specific depth. This compensation shifts the dose distribution within the treatment volume so that some structures may be under or over compensated. This study will examine how various sites in head and neck cases are affected by compensators. We have also analyzed the uncertainty in compensated dose due to the daily variations in patient repositioning. Computer isodose plans using Cobalt-60 gamma rays and 6 and 18 MV x-rays were generated using coronal contours. Results show that the dose uniformity is improved for the treatment sites, especially for the thinner sites, like the larynx and the anterior cervical neck nodes. Finally, patient movement or positioning errors of +/-1.0 cm will cause a change in dose distribution.

Head and Neck Neoplasms↗
PubMed1998

Autoimmune thrombocytopenic purpura in a splenectomised patient.

Splenectomy remains a treatment in patients with autoimmune thrombocytopenic purpura (ATP) who fail to respond adequately to conservative treatment. We report on a 78-year-old man who developed ATP after splenectomy performed six years earlier for iatrogenic injury to the spleen during hemicolectomy. Incidentally, he suffered from colonic and prostatic malignancies. To our knowledge, such a case has not been reported before. We discuss the mechanism of thrombocytopenia in ATP and its association with various malignancies.

Aged↗
PubMed1997

Emergency department use of aspirin in patients with possible acute myocardial infarction.

BACKGROUND: Efforts have been made to improve the suboptimal use of aspirin after hospitalization. OBJECTIVE: To assess the frequency and timing of aspirin administration in emergency department patients with possible myocardial infarction. DESIGN: Retrospective record review. SETTING: Emergency departments of four hospitals affiliated with the same university. PATIENTS: All patients who were admitted to the four hospitals in 1994 for evaluation and treatment of suspected acute myocardial infarction. MEASUREMENTS: The frequency and timing of aspirin administration and the definitive diagnosis established before discharge from the hospital. RESULTS: Aspirin was not given to 253 of 463 emergency department patients (55%) who had a definitive diagnosis of acute myocardial infarction. Seventy-eight percent of patients who did receive aspirin received it more than 30 minutes after arrival in the emergency department. CONCLUSION: Aspirin therapy is underutilized as the first intervention in patients who are admitted with suspected myocardial infarction.

Aged↗
PubMed1997

A possible role of trehalose in osmotolerance and ethanol tolerance in Saccharomyces cerevisiae.

The effect of salt stress on ethanol endurance of yeast cells was studied. Cells grown under increased NaCl concentrations were more ethanol tolerant than controls. The increase in trehalose content under hyper-saline conditions has been suggested to allow cells to withstand higher ethanolic conditions. There seems to be an overlap between osmotolerance and ethanol endurance in Saccharomyces cerevisiae.

Ethanol↗
PubMed1997

Axon-mediated gene transfer of retinal ganglion cells in vivo.

Modification of the intracellular functions of mature neurons through specific gene transfer has many potential applications. Here we present a new methodology for the successful transfection of retinal ganglion cells by administration of plasmid at the cut end of the optic nerve, or at their intact axon terminals; the latter is significantly more efficient. Plasmids contained either the SV40 promoter linked to the luciferase gene, or the CMV or RSV promoter linked to the lacZ gene. Assays for both reporter genes demonstrated significant expression of exogenous DNA in the retina for at least 10 days after retrograde transport. Duration of expression was extended to 20 days or more (duration of the experiment) when plasmid DNA was condensed with poly(L-lysine). beta-Galactosidase analysis revealed transfection of ganglion cells in high numbers. Such an approach for gene delivery to specific subpopulations of neurons might be useful in studies of molecular functions in vivo and as an experimental therapeutic strategy to extend survival and restore their function.

Animals↗
PubMed1997

Intracranial fungal granuloma.

BACKGROUND: Intracranial fungal granulomas are uncommon and their pathogenesis, clinical picture, and effectiveness of therapy remains unclear. METHODS: Thirty-two cases were studied retrospectively in two groups: (1) Rhinocerebral group (22 cases) had a chronic paranasal sinus (PNS) disease with secondary involvement of skull base, cranial nerves, and/or brain. The granulomas were adherent to dura, firm, avascular, and tough, requiring a knife to cut. (2) Primary intracranial group (10 cases) had no detectable PNS lesion at initial presentation. The granulomas were soft, suckable, and contained pus or necrotic material. RESULTS: Postoperative and overall mortality were 37.5% and 50%, respectively. Meningoencephalitis was the most common cause of death. Altered sensorium, pus in the granuloma, and/or severe brain edema were poor prognostic factors. All survivors except four have symptomatic residual or recurrent lesions. CONCLUSION: Early diagnosis with MRI or stereotactic biopsy, radical surgery, and high dose and chronic suppressive chemotherapy may improve overall results in these cases.

Adolescent↗
PubMed1997

Clinical considerations in the use of missing tissue compensators for thoracic cases.

The irregular shape or contour of the patient's surface in the treatment field can alter the dose distribution resulting in non-uniformity of dose in the treatment volume. Missing tissue compensators have been most commonly used to improve this non-uniformity, especially in head and neck, breast, lung and supraclavicular regions. Two or three dimensional compensators have been typically designed to make the dose uniform at a specific depth. This compensation shifts the dose distribution within the treatment volume so that some structures may be under or over compensated. This study will examine how various thoracic sites are affected by compensators, with and without heterogeneity corrections. We have also analyzed the uncertainty in compensated dose due to the daily variations in patient repositioning. Computer isodose plans using Cobalt-60 gamma rays and 6 and 18 MV X-rays were generated using sagittal contours. Results show that superficial sites, like the supraclavicular nodes and the spinal cord, do not receive as consistent a dose compensation as the midplane sites. In addition, the compensated lung dose increases. Finally, patient movement or positioning errors of +/- 1.0 cm causes only a slight change in dose distribution.

Humans↗
PubMed1997

Expression of progesterone receptor mRNA in the first trimester human placenta.

The human placenta produces large quantities of progesterone, the function and target tissues of action of which during pregnancy are not completely understood. Although it has been suggested that placenta itself could be a potential target tissue for progesterone action, there is no conclusive evidence for the presence of progesterone receptors in the human placenta. We provide evidence for the expression of progesterone receptor mRNA in the human placenta by reverse transcription coupled to polymerase chain reaction (RT-PCR). This was further confirmed by Southern hybridization, restriction analysis and sequencing of the PCR amplified fragment.

Base Sequence↗
PubMed1997

Effect of calcium ion channel antagonists on chorionic gonadotropin secretion.

By using calcium ion channel antagonists such as Verapamil and Nifedipine, we demonstrated that calcium ion channels are involved in human chorionic gonadotropin (hCG) secretion stimulated by gonadotropin releasing hormone (GnRH). Addition of 1 microM Verapamil (Class II inhibitor) resulted in an inhibition of GnRH-stimulated hCG secretion by placenta without affecting basal release. However, while addition of 10 microM Nifedipine (Class I inhibitor) resulted only in partial inhibition, significant inhibition was observed at 100 microM concentration and above. These results suggest that calcium ion channels in placenta appear to be similar although not identical with the channels reported in the pituitary.

Calcium Channel Blockers↗
PubMed1997

Craniofacial zygomycosis caused by Apophysomyces elegans.

A fatal case of craniofacial zygomycosis caused by Apophysomyces elegans in a 52-year-old man was diagnosed by the presence of broad aseptate, branched hyaline hyphae in tissue from paranasal sinuses and surrounding areas, and isolation of the fungus from the same tissue. The patient suffered from idiopathic myelofibrosis as underlying disease, he was thrombocytopenic and was mildly hyperglycaemic. The infection represents the second case of craniofacial zygomycosis due to A. elegans.

Blood Vessels↗
PubMed1997

Subcutaneous and osteolytic rhinosporidiosis.

A young man presented with multiple Subcutaneous nodules over scalp, hand, feet and osteolytic lesions of small bones of hand. Clinically and radiologically he was diagnosed as a case of Giant Cell Tumour. Aspiration cytology and biopsy proved it to be rhinosporidiosis. Epidemiological study revealed that he perhaps contracted this infection as an occupational hazard. This is the third reported case of osteolytic lesions due to rhinosporidiosis. Diagnostic dilemmas of subcutaneous and osteolytic rhinosporidiosis are discussed.

Adult↗
PubMed1997

Primary gastrointestinal lymphoma--disease spectrum and management: a 15-year review from north India.

OBJECTIVE: To analyze retrospectively the disease spectrum and outcome of primary gastrointestinal lymphoma (PGIL) in a tertiary referral center in north India. MATERIAL: Seventy five patients presenting with PGIL between January 1971 and December 1985 were evaluated. RESULTS: The 49 males and 26 females were aged 3.5-69 years (mean 34) at presentation. Abdominal pain, weight loss and vomiting were cardinal symptoms at presentation; the stomach was the most common site of involvement. Histologically, a majority of patients were classified as having diffuse poorly-differentiated lymphocytic lymphoma (46.7%) and diffuse histiocytic type (30.7%). Twenty seven (36%) patients had stage I disease, 31 (40%) stage II, 11 (14.7%) stage III, and 6 (8%) stage IV. At laparotomy, primary resection and anastomosis was carried out in 66 patients, while only biopsies were taken in nine. Forty eight patients received adjuvant radiation with or without chemotherapy. The mean follow-up was 3.9 years (range 1-14). The 5-year actuarial survival was 34%, 25% and 16% for stages I, II, and higher-stage disease, respectively. The survival was significantly better (p < 0.01) for gastric location (44%) compared to other sites (24%). CONCLUSION: PGIL was more common in the 3rd and 4th decades of life, with the stomach being the predominant site of involvement. Survival was better among patients with stages I and II disease, and gastric location of lesion.

Adolescent↗
PubMed1997

An update on eicosanoids and inhibitors of cyclooxygenase enzyme systems.

There are 3 main enzymatic pathways for synthesis of eicosanoids from arachidonic acid, however, some compounds are also formed non-enzymatically. Among the enzymatic pathways, cyclooxygenase (COX) also known as prostaglandin synthase (PGHS), generates endoperoxides (PGG/H). These are converted into prostaglandins (PGs) and thromboxanes (TXs). The second pathway involves lipooxygenase (LOX) group of enzymes to provide hydroperoxyeicosatetraenoic acid (HpETEs) which in turn can be converted into leukotrienes (LTs), hepoxilins (HXs), trioxilins and lipoxins (LXs). The third pathway involves cytochrome P-450 which catalyses the formation of a number of monohydroxy fatty acids (hydroxyeicostetraenoic acids or HETEs) dihydroxy fatty acids (dihydroxyeicostetrienoic acids or DiHETrEs) and epoxyeicosatrienoic acids (EpETrEs: formerly called EETs). This system also provides leukotoxins. The non-enzymatic pathway leads to the formation of isoprostanes by free radical catalysed peroxidation of arachidonic acid. In addition, brain cells also convert arachidonic acid into arachidonylethanolamide (anandamide) which have the ability to bind to cannabinoid receptors. Most of these eicosanoids are either biologically active or are converted into metabolites which have biological activities. Cyclooxygenase is now known to exist in two separate isoforms which are called COX-1 and COX-2. While both isoforms catalyse the same reactions, the former is a constitutive enzyme and its activity is not markedly changed once the cell is fully grown. The later isoform is however inducible and its activity is several fold increased following the exposure of body cells to a number of stimuli and its contribution in the process of inflammation is now well documented. It is now believed that eicosanoids produced by COX-1 activity are essential for the physiological (house keeping) functions while those produced by COX-2 lead to various pathological changes in body tissues. Older nonsteroidal antiinflammatory drugs like aspirin and indomethacin are non selective inhibitors of COX activity and therefore, in addition to inhibiting COX-2 activity, inhibit the formation of eicosanoids by COX-1. The later are required for normal house keeping functions such as secretion of mucus for protection of gastrointestinal mucosa, maintenance of renal function and control of haemostasis. Use of older non-selective NSAIDs has been associated with a number of gastrointestinal, renal and other side effects. Recently drugs such as nimesulide and meloxicam with selective action on COX-2 have been discovered and introduced into medicine. Evidence available so far has indicated the low incidence of side effects with these drugs. While being useful for various arthritic and other conditions, it is unlikely that these drugs will replace aspirin for the cardiovascular disease.

Animals↗