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Biomedical subjects

V R Rao

Publications and source records attributed to V R Rao.

At least 19 recordsLinked to original sources
PubMed1992

Binary combination effects of some pharmacologically active chemicals as promoters of tumorigenesis.

Identification of potential interactions in exposures either to simultaneous or sequential combinations of carcinogenic chemicals and chemicals that modify carcinogenesis poses considerable difficulties in human health risk assessments. Studies of experimental carcinogenesis over the past four decades have revealed that many pharmacologically active agents possess tumorigenesis-promoting properties. The effort to identify the possible chemical structural basis of interactions of binary combinations of carcinogenic chemicals and chemical agents that modify carcinogenesis led to the identification of a class of structurally diverse and pharmacologically active tumorigenesis promoters that are known as pharmaceuticals. The chemical class-class interactions of carcinogens and pharmaceutical agents with reported tumorigenesis-promoting properties and the possible biochemical mechanism(s) that underlie such interactions are discussed.

Animals↗
PubMed1992

Histopathological evaluation of polymethyl methacrylate as an embolic agent.

Polymethyl methacrylate (PMMA) microspheres were used as an embolic agent to reduce the vascularity in eight patients with intracranial vascular tumours. Post embolization angiograms showed 30-60% reduction in the vascularity of the tumours. No patient developed any neurological complications in the immediate post-embolization period. These eight patients subsequently underwent surgery for the removal of their tumours. During surgery there was minimal blood loss and a good plane of cleavage was obtained between the tumour and the adjacent brain. The surgical specimens were examined histopathologically for the effects of PMMA. PMMA microspheres, in contrast to other cyanoacrylates--isobutyl-2-cyanoacrylate (IBCA)--did not elicit either inflammatory reaction or mural angionecrosis within the wall of the embolised vessels. The histopathological studies suggest that PMMA microspheres are an inert material and can be used as an adjunct in the management of intracranial vascular tumours.

Adult↗
PubMed1992

Genetic heterogeneity and population structure of Gond-related tribes in the Vidarbha region of Maharashtra.

Genetic heterogeneity in nine polymorphic loci is observed among Gond-related tribes in the Vidarbha region of Maharashtra. Pardhans, with their high ABO*A2 gene frequency (4.01%), low m gene frequency (57%), high P*1 gene frequency (42.7%), and high HbS trait (31.58%), differ significantly from other tribes. Per locus average heterozygosity among the studied tribes ranged from 36.24% to 40.37%, with Pardhans being more heterozygous. Analysis by FST and the empirical relationship between average allele frequencies and the ratio of within-gene to total gene diversity show that the tribes are isolated and that differentiation among them is at an early stage and approximately in conformity with expected differentiation under genetic drift. However, distances and principal components analysis reveal that Pardhans are far removed from the other tribes and from other central Dravidian tribes. Furthermore, of the various demographic parameters estimated, the high average heterozygosity in Pardhans is significantly correlated with mean marital distance (MMD), regression of MMD on wife's age, and effective population size. There is congruence between genetic and demographic data, showing that Pardhans are distinct. This conforms with Haimendorf's (1979) contention based on cultural traits that Pardhans are Gonds by historical accident and are later migrants to the Gond area from the north. The most significant and practical observation of the present study is that migration from an originally nontribal (Pardhan) to a tribal (Gond) area and admixture lead to severe disease course, differential selection pressure, and hence highly elevated HbS trait frequency.

Blood Group Antigens↗
PubMed1991

Disappearance of a cerebral aneurysm--an unusual angiographic event.

Spontaneous thrombosis of cerebral aneurysms demonstrated by angiography is infrequent. This article describes angiographically documented spontaneous thrombosis of an intracranial aneurysm at the posterior cerebral-posterior communicating artery junction in a 40-year-old woman. The initial angiogram done on 16th day after an episode of subarachnoid haemorrhage showed a medium sized aneurysm. Subsequent angiograms done on 30th, 40th and 60th day failed to demonstrate the aneurysm. The factors leading to this rare event remain obscure.

Adult↗
PubMed1991

Syringohydromyelia: radiological evaluation of 82 patients in a developing country.

A series of 82 patients presenting with syringohydromyelia and confirmed at operation were studied by conventional radiological techniques and computed tomography (CT). Cord collapse was demonstrated in 71% of the patients with wide bony canals and only 11% of patients with normal bony canals. It was most reliably shown with high resolution CT. Intrathecal CT metrizamide myelography (CTMM) failed to demonstrate contrast percolation into many cavities shown in the plain scans. Obliteration of the subarachnoid space at C1-2 levels appreciated in the plain scans strongly indicated coexisting tonsillar herniation, making CTMM unnecessary. In almost all patients, CTMM was found to be non-contributory if the high resolution plain CT scan failed to reveal cord cavitation.

Adolescent↗
PubMed1991

Binary effects of carcinogens and tumor promoters--a preliminary chemical structural analysis of BCIDB and PCIDB.

Identification of potential interactions in exposures, either to simultaneous or sequential combinations of carcinogenic chemicals and mixtures of carcinogen and carcinogenesis-modifying chemical agents, pose formidable difficulties in human health risk assessments. Studies over the past four decades have revealed synergistic interactions among various classes of carcinogenic chemicals. An earlier effort to identify a possible chemical structural basis of interaction of binary combinations of carcinogens led to the development of Binary Carcinogen Interaction Data Base (BCIDB). A recent endeavor to identify a structural basis of interactions of carcinogens and carcinogenesis modifying chemical agents resulted in Promoter-Carcinogen Interaction Data Base (PCIDB). An attempt will be made in this report to briefly discuss chemical class-class interaction and initiator-target organ orientation as recorded in BCIDB and PCIDB.

Animals↗
PubMed1991

Obstruction of the infrarenal portion of the abdominal aorta: results of treatment with balloon angioplasty.

Our experience in the treatment of stenoses of the infrarenal portion of the abdominal aorta with balloon angioplasty in 27 patients is reported. Clinical findings were lower limb claudication (all patients), impotence (eight patients), and blue-toe syndrome (two patients). The underlying disease was atherosclerosis in 24 patients and nonspecific aortoarteritis in three patients. Dilatation was successful in all patients. Embolic occlusions of the left common iliac artery (one patient) and left superficial femoral artery (one patient) were the only major complications. Claudication in the affected limb continued in the first patient; the second died when diagnostic angiography, performed 3 months after angioplasty, caused a severe atheroembolus. Of the other 25 patients, nine of the 10 followed up for 13-48 months and all seven followed up for 3-8 months were free of symptoms. Six of eight patients with sexual dysfunction had normal function after angioplasty. Seven patients still awaited follow-up and one was lost to follow-up. Our experience suggests that balloon angioplasty is an effective treatment of stenoses of the infrarenal portion of the abdominal aorta.

Adult↗
PubMed1991

Hydrolysed microspheres from cross-linked polymethyl methacrylate (Hydrogel). A new embolic material for interventional neuroradiology.

Highly hydrophilic, perfectly smooth and spherical microspheres have been synthetized. These non-biodegradable microspheres absorb water in varying degrees and can be injected easily through microcatheters due to their slippery and compressible characteristics. The material was successfully used for embolization of 4 vascular intracranial tumours and 2 spinal vascular lesions in the cervical region, by superselective delivery. Histopathology confirmed absolute inertness of the microspheres.

Adult↗
PubMed1990

Corpus callosum lipoma with frontal encephalocele.

Computed tomographic and plain X-ray observations in a patient with corpus callosum lipoma associated with frontal encephalocele are reported. The rarity of the lesion and the specific diagnostic criteria on CT are emphasised.

Brain Neoplasms↗
PubMed1990

Interactions of cryptosin with mammalian cardiac dihydropyridine-specific calcium channels.

Cryptosin -a new cardenolide was found to be a potent inhibitor of cardiac Na+ and K+ dependent Adenosinetri-phosphatase (7). In experiments with dog heart ex vivo, development of inotropic and toxic effect correlated with changes in the cardiac dihydropyridine-specific calcium channels as measured by the binding of 3[H]PN 200-110. A significant change in the PN 200-110 binding was observed when guinea pig and dog heart sarcolemmal membranes were pre-incubated with cryptosin in vitro. Binding analysis of 3[H]PN 200-110 (Isradipine) - -a 1,4-dihydropyridine analog with very specific calcium channel binding properties - in both in vitro and ex vivo studies were consistent and indicated a non-specific type of interaction of cryptosin with mammalian cardiac 1,4-dihydropyridine-specific calcium channels.

Animals↗
PubMed1990

Aneurysmal form of aortoarteritis (Takayasu's disease): analysis of thirty cases.

The clinical and radiological features, and outcome of 30 patients including 22 females, with the aneurysmal form of aortoarteritis were analysed. The average age at diagnosis was 27.4 +/- 7.2 years. Features which indicated the diagnosis of aneurysmal aortoarteritis included young age, female sex, characteristic location, associated stenotic lesions and the presence of multiple aneurysms. There were 41 fusiform and 18 saccular aneurysms, mostly located in the descending aorta. Diffuse dilatation (n = 24) was seen mainly in the ascending aorta. Two patients had dissecting aneurysms, while one patient had an aneurysm of the left main coronary artery. Both these lesions are rare in aortoarteritis. The aneurysmal form was associated with a higher incidence of aortic incompetence (P less than 0.01) and elevated ESR (P less than 0.001) as compared to the more common non-aneurysmal form. The average follow-up period was 59.7 (+/- 48.1) months. The event-free survival rate was 82.9% at 5 years, similar to that seen in the non-aneurysmal form. These data should be useful to the clinician in the diagnosis and management of the aneurysmal form of aortoarteritis.

Adolescent↗
PubMed1990

Vitamin and provitamin A levels in epithelial cancers: a preliminary study.

A major physiological role of retinoids is the regulation of epithelial and epidermal cell differentiation. A total of 285 patients with clinically and histopathologically confirmed diagnosis of various carcinomas (untreated) were selected for the study. The control values of serum beta-carotene and vitamin A levels were established from 50 subjects free of any known pathology. The controls were matched for age and sex. The mean serum levels of beta-carotene and vitamin A have shown a significant difference (p less than 0.001) in all the cancers compared with the controls. In cancer of the oral cavity, the males showed significantly lower levels (p less than 0.01) compared with their female counterparts. In cancer of the lung, however, the mean serum levels of beta-carotene and vitamin A were higher in males compared with females (p less than 0.02). Our results suggest a possible association between vitamin A and epithelial cancer, but whether the deficiency is the cause of the disease or if it is due to the tumor remains unknown.

Carcinoma↗
PubMed1990

Embolization of large saccular aneurysms with Gianturco coils.

In five patients embolization of large saccular aneurysms involving the popliteal artery, common carotid artery, arch of the aorta, and abdominal aorta was performed with custom-designed spring coils. Surgery was attempted before embolization for the aneurysm involving the popliteal artery. The other aneurysms were considered nonresectable due to their critical location. Although maximal packing of the aneurysmal sac was attempted, delayed follow-up angiography revealed displacement of the coils away from the parent vessel as well as further expansion of the residual aneurysmal sac. In these cases complete embolization of the aneurysmal sac was not possible without obstructing the parent artery.

Adult↗
PubMed1990

Interactions of cryptosin with mammalian cardiac beta-adrenoceptors.

Cryptosin - a new cardenolide from the leaves of Cryptolepis buchanani R & S was found to be a potent positive inotropic agent. In experiments with dog heart ex vivo, the rise in the cardiac rate associated with an increase in dP/dtmax and left ventricular pressure (LVP) correlated with changes in the beta-adrenoceptor densities as measured by the binding of 3H-Dihydroalprenolol (DHA). A significant change in the beta-adrenoceptor densities was observed when cryptosin was incubated with guinea pig and dog heart sarcolemmal membranes in vitro. Analysis of the binding of 3H-DHA in post-cryptosin treated membranes indicated a non-specific type of interaction of cryptosin with mammalian cardiac beta-adrenoceptors.

Adrenergic beta-Antagonists↗
PubMed1990

Sickle cell hemoglobin, beta-thalassemia and G6PD deficiency in tribes of Maharashtra, India.

The prevalence of sickle cell hemoglobin (HbS), beta-thalassemia trait and G6PD deficiency are reported in some important Gond related endogamous tribes in Maharashtra, India. The HbS gene frequency varies from 0.0530 to 0.1805, the beta-thal gene from 0 to 0.0283 and Gd- gene from 0.0189 to 0.1120. The Pardhan tribe has been identified as a high risk group for sickle cell diseases. Statistically significant differences are observed between tribes.

Child↗
PubMed1990

Prevalence of HBsAg carriers among some tribes of Madhya Pradesh.

Prevalence of HBsAg was determined in 1314 sera obtained from 11 different tribal populations of five districts of Madhya Pradesh. Reversed passive haemagglutination assay was used for screening showed a HBsAg carrier rate of 2.99 to 21.54 per cent among the various tribes. Significant regional variation was also observed.

Carrier State↗