Biomedical subjects

V R Rao

Publications and source records attributed to V R Rao.

At least 37 records · Page 2Linked to original sources

PubMed1994

Angiographic analysis and results of endovascular therapy of aneurysm of vein of Galen.

Angioarchitecture of the aneurysmal malformation of the vein of Galen in 9 patients is analysed. An arterial maze arborised directly into the vein of Galen in 6 patients. Direct fistulous communication from one or two pedicles was noted in three children. Unilateral choroidal arterial contribution via an eccentric cul-de-sac in two infants suggested embryonic involvement of the ipsilateral internal cerebral vein along with the median prosencephalic vein of Markowski. Unusually, a sylvian branch of the middle cerebral artery drained directly into the basal vein of Rosenthal which in turn communicated to the aneurysm of vein of Galen in another patient. Two adult patients had curvilinear rim calcification of the venous sac with rapid circulation. All but two showed venous sinus anomalies. Two children had prior shunt surgery at the referring hospitals. The pathophysiology of hydrocephalus and the possible consequences of shunt, question the need for CSF diversion as a routine in these patients. Percutaneous trans-arterial embolotherapy, in five patients achieved complete obliteration of the malformation in four patients and partial reduction of flow in another. While transvenous/trans-torcular approach is reserved for selected patients and direct surgery carries high morbidity, this report emphasises the efficacy of trans-arterial embolotherapy.

Adult↗

PubMed1993

Logistic regression of inhalation toxicities of perchloroethylene--application in noncancer risk assessment.

Unlike the impressive advancement of cancer risk assessment, the "cutoff approach" based on hazard quotient in noncancer risk assessments recommended by the EPA has crucial deficiencies. Several alternative approaches have been suggested in the literature to modify the noncancer risk characterization based on reference doses. Recent studies have indicated that the effects of perchloroethylene (PERC) on the central nervous system (CNS) is a much more sensitive noncancer endpoint than cancer which is currently the basis for deriving its public health criteria and standards. Studies indicate that 20 ppm of inhaled PERC concentration elicited adverse effects on the CNS in experimental animals and humans. However, the existing EPA oral reference dose (RfD), a noncancer toxicity parameter for PERC (0.01 mg/kg/day), is based on the induction of hepatotoxicity and increased body weight gain induced by PERC in rats. An attempt was made in this paper to examine whether logistic regression of dose-response data could be applied to assess the noncancer risks. In order to perform logistic regression the inhalation toxicity data of PERC were classified according to the severity of toxicity paradigm used in toxicity analysis. Based on the sensitive noncancer endpoints identified from severity classification, a logistic regression analysis of the data was performed and its potential applicability in noncancer risk characterization was described for workers exposure to PERC in dry-cleaning operations.

Administration, Inhalation↗

PubMed1993

Arteriovenous aneurysm of the occipital artery.

We report an unique case of a giant aneurysm of the occipital artery, with a venous connection to the transverse sinus via an emissary vein. Because of this connection, the term arteriovenous aneurysm is used.

Catheterization↗

PubMed1993

Aortoarteritis of abdominal aorta: an angiographic profile in 110 patients.

The angiographic appearances in 110 patients (49 males, 61 females, age range 11-46 years, mean 27.8 years) with aortoarteritis involving the abdominal aorta and/or its branches were analysed. There were 41 aneurysms of the abdominal aorta in 37 patients and eight aneurysms of its branches in as many patients. In 50 patients, 53 obstructive lesions involved the abdominal aorta and were classified as stenoses of focal, segmental and diffuse types and total occlusions. Branch obstructions (182 lesions in 85 patients) affected in order of frequency, the renal, superior mesenteric, coeliac, iliac and the inferior mesenteric arteries. Mesenteric arterial lesions were significantly more common in males (P = 0.01). Collateral circulation through a prominent mesenteric arcade was a distinctive angiographic feature in 28 patients. Computed tomography done in four patients showed peri-adventitial thickening and layered thrombus within aneurysms in three patients, and luminal occlusion of the upper abdominal aorta in one patient. Angiographic appearances in aortoarteritis of the abdominal aorta are characteristic and sufficiently distinctive for definitive diagnosis and appropriate management.

Adolescent↗

PubMed1993

Heterozygous missense mutation in the rhodopsin gene as a cause of congenital stationary night blindness.

A number of mutations in the rhodopsin gene have been shown to cause both dominant and recessive retinitis pigmentosa. Here we describe another phenotype associated with a defect in this gene. We discovered a patient with congenital stationary night blindness who carries the missense mutation Ala292Glu. When coupled with 11-cis-retinal in vitro, Ala292Glu rhodopsin is able to activate transducin in a light-dependent manner like wild-type rhodopsin. However, without a chromophore, Ala292Glu opsin anomalously activates transducin. We speculate that the rod dysfunction in this patient is due to an abnormal, continuous activation of transducin by mutant opsin molecules in photoreceptor outer segments.

Adult↗

PubMed1993

Multiple pulmonary-artery aneurysms due to mucoid vasculopathy--angiographic and histological observations.

Multiple peripheral pulmonary artery aneurysms were diagnosed by computed tomography and confirmed angiographically in a 7-year-old boy. On histological examination unusual mucoid vasculopathic changes were noted in the pulmonary artery aneurysms and pulmonary vasculature as a part of systemic vascular involvement. This case demonstrates a new association between mucoid vasculopathic changes and pulmonary aneurysms. Mucoid vasculopathy could represent one more disorder having a causative role in the etiology of intrapulmonary arterial aneurysms.

Aneurysm↗

PubMed1993

Endovascular management of carotid cavernous fistulae: observation on angiographic and clinical results.

Twenty-five patients with carotid cavernous fistulae (CCFs) were managed at our institute during a five-year period. Transarterial and transvenous treatment of traumatic carotid cavernous fistulae using the detachable balloon technique was performed in 21 patients resulting in angiographic and clinical cure in 20 patients and fatal outcome in one patient following venous rerouting. Surgical ligation of the infraclinoid internal carotid artery was needed in one patient. Preservation of the carotid artery was possible in 16 patients. Four patients with spontaneous CCFs were advised digital compression of carotid arteries resulting in complete closure of the fistula in one and considerable clinical improvement in two patients. One patient required transarterial obliteration of the fistula via the middle meningeal artery by means of a platinum coil and normal butyl cyanoacrylate (NBCA) resulting in total radio anatomical cure.

Adolescent↗

PubMed1993

Takayasu arteritis: initial and long-term follow-up in 16 patients after percutaneous transluminal angioplasty of the descending thoracic and abdominal aorta.

PURPOSE: To analyze results of percutaneous transluminal angioplasty (PTA) for stenosis of the descending thoracic and/or abdominal aorta caused by Takayasu arteritis (TA). MATERIALS AND METHODS: Subjects were 16 patients (12 female and four male, aged 6-46 years) with symptoms of hypertension or severe bilateral lower limb claudication. Total aortography revealed stenotic lesions in the descending thoracic aorta in five, in the abdominal aorta in 10, and in both vessels in one patient. Involvement of arch vessels in four patients and of the renal artery in four patients was also noted. Double-balloon angioplasty was performed in eight patients. RESULTS: Initial technical and clinical success was 100%. The maximum follow-up period was 52 months (mean, 21 months 2 weeks). Ankle-brachial index as determined with Doppler ultrasound improved considerably in 10 patients. Three patients had symptoms of restenosis during follow-up. Cumulative patency rate by life-table analysis was 67%. CONCLUSION: PTA has a definite role in the management of TA in view of its procedural simplicity, cost-effectiveness, and results compared with surgical revascularization procedures.

Adolescent↗

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↗