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Biomedical subjects

S Kumar

Publications and source records attributed to S Kumar.

At least 991 records · Page 55Linked to original sources
PubMed1997

Glucosaminylmuramyl dipeptide (GMDP) modulates endothelial cell activities in vitro but has no effect on angiogenesis in vivo.

OBJECTIVE AND DESIGN: The aim of the study was to evaluate the effects of GMDP on angiogenesis in vivo and as a modulator of human umbilical vein endothelial cell proliferation, cell surface antigen expression and cell adhesion in vitro. MATERIALS: Human umbilical vein endothelial cells (HUVEC), fertilized white leghorn chicken eggs, antibodies against adhesion molecules and glucosaminylmuramyl dipeptide (GMDP). TREATMENT: GMDP [0.01-100 micrograms/ml] applied to cell cultures for 6-72 h and to the chick chorioallantoic membrane (CAM) for four days. METHODS: Angiogenic activity of GMDP in vivo was assessed using the CAM assay; HUVEC proliferation was measured by tritiated thymidine incorporation and cell cycle studies; cell surface antigen expression by indirect immunofluorescence and flow cytometry; cell adhesion by quantification of [3H]-thymidine labeled leukocyte adherence to HUVEC monolayers. Statistical analysis was performed using one-way ANOVA and if necessary was followed by Duncan's multiple range test for variables. RESULTS: GMDP induced [3H]-thymidine incorporation in a concentration- and time-dependent manner (p < 0.003) and significantly increased the porportion of cells in the S phase of the cell cycle (p < 0.03). It weakly augmented the expression of ICAM-1 and CD31 but not adhesion of leukocytes to HUVEC monolayers GMDP was not angiogenic in the CAM assay. CONCLUSIONS: GMDP can modulate endothelial cell activity without the induction of angiogenesis in vivo which may have implications for its use as a therapeutic agent.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1997

MRI in Japanese encephalitis.

We document the MRI features in seven patients with Japanese encephalitis. MRI was carried out on a 1.5 T system within 10-60 days of onset. In all the patients MRI revealed bilateral thalamic lesions, haemorrhagic in five. Signal changes were present in the cerebrum in four patients, the midbrain and cerebellum in three each, the pons in two and the basal ganglia in one. The lesions were haemorrhagic in three of the four patients with lesions in the cortex, two of the three with lesions in the midbrain and cerebellum, but the pontine lesions were haemorrhagic in both patients. Spinal cord involvement was seen in one of the three patients who underwent MRI. In two patients MRI was repeated 3 years after the onset, showing marked reduction in abnormal signal; and all the lesions gave low signal on both T1- and T2-weighted images. Bilateral thalamic involvement, especially haemorrhagic, may be considered characteristic of Japanese encephalitis, especially in endemic areas.

Adolescent↗
PubMed1997

Takayasu's arteritis: evaluation with three-dimensional time-of-flight MR angiography.

Three-dimensional time-of-flight MR angiography was performed in 16 patients with Takayasu's arteritis. Two regions were evaluated, the arch of aorta and its intrathoracic major branches, and the abdominal aorta with proximal portions of its major visceral and renal branches. Individual arteries and aortic segments, i. e. aortic arch and abdominal aorta, were evaluated for abnormalities such as stenosis, occlusion, dilatation and aneurysm formation. The results were compared with contrast angiography. Follow-up MR angiography was performed in three patients after 9-12 months. MR angiography demonstrated steno-occlusive lesions in all the patients and aneurysms in 2. In comparison with contrast angiography, good correlation was found in 129 of the 145 arteries and aortic segments. For the 12 false-positive results, incorrect slab placement and overestimation of stenosis were implicated. Interestingly, there were three false-negative results and one occlusion was underestimated as stenosis. A new lesion developed in 1 patient and one stenosis progressed in another patient upon follow-up. Three-dimensional time-of-flight MR angiography is a simple and fairly accurate method for documenting the lesions in Takayasu's arteritis and for its follow-up.

Adolescent↗
PubMed1997

Influence of vanadium on acclimatization of humans to high altitude.

The study was conducted on human volunteers as controls as well as after administration of vanadyl sulphate on induction to high altitude (HA) at 3500 m. The plasma vanadium contents were significantly reduced in the control group on abrupt induction to HA on days 3 and 10, indicating redistribution to other organs/tissues under the stressful situation. In the vanadium salt-treated group, plasma vanadium contents were similar to those obtained at sea-level. Administration of vanadyl sulphate did not act as a diuretic. Moreover the vanadium supplemented group drank more water and also excrete less urine than the control group.

Acclimatization↗
PubMed1997

Isolated traumatic denervation of the extensor pollicis longus.

This report describes a case of isolated denervation of the extensor pollicis longus (EPL), which has not previously been reported. The patient was a healthy 13-year-old boy who sustained multiple lacerations to the left forearm secondary to a dog bite. No motor responses were evident in the EPL, but the remainder of the exam findings were normal. Electromyography confirmed complete isolated denervation of the EPL. This patient was managed nonoperatively and had no significant functional deficits at final follow-up.

Adolescent↗
PubMed1997

Iatrogenic renal vascular injuries and their radiological management.

Twenty-nine patients with significant haematuria after a renal invasive procedure (27 of whom had undergone a percutaneous renal procedure and 2 surgical pyelolithotomy) were investigated with angiography. Out of the 21 patients with evidence of arterial injury, 19 were treated by transarterial embolization with gelfoam with or with hydrogel particles; (n = 11), steel coils with gelfoam (n = 4), hydrogel particles (n = 1), surgicel (n = 2), silk with gelfoam (n = 1). The efficacy and technique of the therapeutic embolization procedure is emphasized.

Aneurysm, False↗
PubMed1997

Phase II clinical trial of a vas deferens injectable contraceptive for the male.

Following up on an earlier clinical trial demonstrating the safety of an intra-vas deferens injection of a contraceptive drug named Risug, comprised of styrene maleic anhydride (SMA) in a solvent vehicle of dimethylsulphoxide (DMSO), a study to assess the contraceptive effectiveness of a specific dose (60 mg) of SMA bilaterally was planned and implemented. Male subjects and their wives with normal reproductive profiles were the volunteer subjects. The wives were not using any contraceptives. The results reconfirm the safety and show that for a period of at least 1 year, the treatment leads to azoospermia in the male and gives pregnancy protection.

Adult↗
PubMed1997

Autologous lymphoblastoid cell lines stably transfected with Plasmodium falciparum circumsporozoite protein as targets in cytotoxic T-lymphocyte assays.

To produce cell lines that can be used as a continuous source of antigen presenting cells for stimulating T-cell lines and clones and as targets in cytotoxic T-lymphocyte (CTL) assays, we used a retroviral vector with a simian virus (SV40) early promotor to transfer a Plasmodium falciparum circumporozoite (PfCSP) gene into human EBV transformed B-lymphoblastoid cell lines (B-LCL). We herein report successful, stable transfection and cell surface expression of this gene, as confirmed by PCR, Western blot analysis and immunoelectron microscopy. One of three successfully transfected autologous cell lines expressed PfCSP on the cell surface and was lysed by CD8+ T-cell dependent CTL from a donor volunteer who had been immunized with irradiated P. falciparum sporozoites. Such cell lines should provide excellent tools for characterizing human CD8+ T-cell responses against Plasmodium sp. proteins.

Animals↗
PubMed1997

Detection of HHV-6 genotypes by in situ hybridization with variant-specific oligonucleotide probes.

Human herpesvirus-6 exists in two forms, HHV-6A which has not been clearly associated with any disease, and HHV-6B, the causative agent of exanthem subitum. The two variants have been distinguished by techniques such as dot blotting and restriction fragment length polymorphism of PCR products. This study aims to establish the prevalence of HHV-6A and HHV-6B in carcinoma tissues using variant-specific oligonucleotide probes. A total of 73 archived carcinoma biopsies from the oral, salivary gland, larynx, breast and cervix were obtained with seven histologically normal controls. In situ hybridization was carried out with nonradioactively labelled variant-specific probes. Samples that hybridized with both variant A and B probes were subjected further to nested PCR and digested with HindIII to distinguish the variants. A hybridization signal was observed in 76.2% of oral carcinoma tissue and 75.0% of salivary gland carcinoma tissue. In contrast, only 33.3% of cervical carcinoma tissue were positive for HHV-6 DNA. A hybridization signal was noted in all 4 laryngeal carcinoma tissues studied. However, the 10 breast carcinoma tissues studied were negative, as was the histologically normal tissue. The virus possesses tumourigenic potential and demonstrates virus transactivating properties. The frequency of HHV-6 variants in certain tumours suggest a cofactorial role in multistep carcinogenesis. While PCR amplifies selectively the predominant variant in a sample, this was not seen by in situ hybridization. The in situ hybridization technique allowed the localization of both HHV-6A and HHV-6B in the nuclei of transformed regions.

DNA, Viral↗
PubMed1997

Up-regulation of brain N-methyl-D-aspartate receptors following multiple intracerebroventricular injections of [D-Pen2, D-Pen5] enkephalin and [D-Ala2, Glu4]deltorphin II in mice.

The effects of chronic administration of [D-Pen2, D-Pen5]enkephalin and [D-Ala2, Glu4]deltorphin II, the selective agonists of the delta 1- and delta 2-opioid receptors, on the binding of [3H]MK-801, a noncompetitive antagonist of the N-methyl-D-aspartate receptor, were determined in several brain regions of the mouse. Male Swiss-Webster mice were injected intracerebroventricularly (i.c.v.) with [D-Pen2, D-Pen5]enkephalin or [D-Ala2, Glu4]deltorphin II (20 micrograms/mouse) twice a day for 4 days. Vehicle injected mice served as controls. Previously we have shown that the above treatment results in the development of tolerance to their analgesic activity. The binding of [3H]MK-801 was determined in brain regions (cortex, midbrain, pons and medulla, hippocampus, striatum, hypothalamus and amygdala). At 5 nM-concentration, the binding of [3H]MK-801 was increased in cerebral cortex, hippocampus, and pons and medulla of [D-Pen2, D-Pen5]enkephalin treated mice. In [D-Ala2, Glu4]deltorphin II treated mice, the binding of [3H]MK-801 was increased in cerebral cortex and hippocampus. The changes in the binding were due to increases in the Bmax value of [3H]MK-801. It is concluded that tolerance to delta 1- and delta 2-opioid receptor agonists is associated with up-regulation of brain N-methyl-D-aspartate receptors, however, some brain areas affected differ with the two treatments. The results are consistent with the recent observation from this laboratory that N-methyl-D-aspartate receptors antagonists block tolerance to the analgesic action of delta 1- and delta 2-opioid receptor agonists.

Animals↗
PubMed1997

Serodiagnosis of Babesia equi infection--a comparison of Dot-ELISA, complement fixation test and capillary tube agglutination test.

The present study aimed to develop Dot-ELISA, complement fixation test (CFT) and capillary tube agglutination test (CAT) for serodiagnosis of Babesia equi infection and to compare their sensitivity with each other. For this study, sequential serum samples were collected from four donkeys experimentally infected with B. equi up to 90 days post infection (P.I.). B. equi antigen was prepared from the blood of a donkey showing more than 80% parasitaemia. Dot-ELISA, CF and CA tests were standardized as per the standard method. While performing CFT, it was observed that CFT standardized for the donkey system could not be applied to the horse system, and different units of the same antigen and complement were required for each. Dot-ELISA detected antibodies from 3-6 days P.I. onwards, whereas CF and CA tests could detect antibodies from the 6th day P.I. indicating that Dot-ELISA is the more sensitive. The efficacy of these three tests was also determined by testing 211 field serum samples of apparently healthy horses. By Dot-ELISA 49.76%, by CAT 42.18% and by CFT 27.86% of the serum samples were found positive. As the results of Dot-ELISA and CAT are comparable, it is proposed that CAT may be used as a screening test.

Agglutination Tests↗
PubMed1997

Time course of the changes in central nitric oxide synthase activity following chronic treatment with morphine in the mouse: reversal by naltrexone.

1. The time course of the effect of chronic administration of morphine on the activity of nitric oxide synthase (NOS) in the brain regions and spinal cord of the mouse was determined. The effect of naltrexone by itself on the NOS activity and that induced by morphine also were determined. 2. Male Swiss Webster mice were implanted subcutaneously with a pellet containing 25 mg of morphine free base for 4 days. Placebo pellet implanted mice served as controls. 3. Twenty-four hours after treatment with morphine, NOS activity decreased in the cerebellum, midbrain, cortex and remainder of the brain as well as in the spinal cord. Forty-eight and 72 hr after the treatment with morphine, NOS activity increased in the cerebellum and cortex, but no change was observed in the other brain regions and spinal cord. Twenty-four hours after morphine pellet removal (withdrawal), NOS activity in all brain regions and the spinal cord has returned to normal. 4. Implantation of a pellet containing 10 mg of naltrexone did not alter NOS activity in any brain region or spinal cord for 24, 48 and 72 hr or 24 hr after removal of the pellet. 5. Implantation of a naltrexone pellet in conjunction with a morphine pellet blocked the changes in NOS activity in the brain region and spinal cord induced by morphine. 6. It is concluded that the initial decrease in NOS activity by morphine may be related to enhanced motor activity, whereas the increase in NOS activity in certain brain regions may be associated with tolerance-physical dependence development. Additionally, the changes in central NOS activity by morphine appear to be mediated by opioid receptors because they were blocked by concurrent treatment with naltrexone.

Animals↗
PubMed1997

Effect of multiple injections of U-50, 488H, a kappa-opioid receptor agonist, on the activity of nitric oxide synthase in brain regions and spinal cord of mice.

1. The time course of the effects of multiple injections of U-50,488H, a kappa-opioid receptor agonist, and its subsequent termination on its analgesic action and nitric oxide synthase (NOS) activity was determined in the brain regions and spinal cord of the mouse. 2. Male Swiss-Webster mice were rendered tolerant to U-50,488H by twice-daily injections of the drug (25 mg/kg, IP) for 4 days. Vehicle-injected mice served as controls. 3. In tolerant mice, NOS activity was unchanged in brain regions and the spinal cord after treatment with U-50,488H. During abstinence from U-50,488H, NOS activity was found to be increased in the cortex and remainder of the brain, but no change was noted in the cerebellum, midbrain and spinal cord. 4. These studies demonstrate that withdrawal from the short-term treatment with U-50,488H in mice causes induction of NOS in certain brain regions. However, long-term treatment and withdrawal from U-50,488H are not associated with changes in the central NOS activity and indicate a possible adaptation in the NOS activity.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1997

Management of large vascular lesions of the lip: case reports.

Vascular lesions of the head and neck region have been classified as either hemangiomas or vascular malformations. In adults, the lesions usually seen are malformations which may be large. Total resection of these lesions necessitates extensive reconstructive procedures and involves the risk of massive hemorrhage. It is for localized vascular malformations which arise in accessible areas of the face, e.g., the lip, that we developed a technique of circumferential ligation and partial resection. In our experience, this technique successfully circumvents the above problems. We present three cases which illustrate our contention.

Adolescent↗
PubMed1997

Oral pilocarpine improves radiotherapy-induced dry eyes.

We report a patient with angiosarcoma of the scalp, who was treated with radiotherapy that included both orbits. Following treatment, he developed dry eyes, which improved with oral pilocarpine. Although this drug is used to stimulate salivary flow in patients with radiotherapy-induced xerostomia, it has not been reported before as a treatment for dry eyes following radiotherapy.

Aged↗