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Biomedical subjects

V M Patel

Publications and source records attributed to V M Patel.

11 recordsLinked to original sources
PubMed2006

A wandering fish bone.

A unique case is described of an ingested fish bone migrating into the common hepatic duct, without perforation. Most foreign bodies are known to pass through the gastrointestinal tract uneventfully. Sharper objects such as fish bones have been known to cause perforation. This is more common, in countries where fish consumption is considerably higher, such as, south east Asia. However, even in these regions there have been no reports of such a proximal migration.

Abdominal Pain↗
PubMed2006

Physicochemical characterization and evaluation of buccal adhesive patches containing propranolol hydrochloride.

Buccal adhesive patches containing 20 mg of propranolol hydrochloride were prepared using solvent casting method. Chitosan was used as a natural bioadhesive polymer. Patches were prepared at different ratios of PVP K-30 and evaluated for various physicochemical characteristics such as weight variation, drug content uniformity, folding endurance, surface pH, ex-vivo mucoadhesive strength, ex-vivo residence time, in vitro drug release and in vitro buccal permeation study. Patches exhibited sustained release over a period of 7 hours. The mechanism of drug release was found to be Non-Fickian diffusion. Addition of PVP K-30 generally enhanced the releasing rate. The ex-vivo mucoadhesive strength was performed using sheep buccal mucosa on modified physical balance. Optimized patches (batch F4) showed satisfactory bioadhesive strength (9.6 degrees 2.0 gram) and ex vivo residence time (272 degrees 0.25 minutes). Swelling index was proportional to PVP K-30. The surface pH of all batches was within satisfactory limit (7.0+/-1.5) and hence patches would not cause irritation in the buccal cavity. Good correlation was observed between in vitro drug release and in vitro drug permeation with correlation coefficient of 0.9364. Stability of optimized patches was performed in natural human saliva showed that both drug and dosage forms were stable in human saliva.

Adhesiveness↗
PubMed2002

Validation of image analysis for enzyme histochemical and immunocytochemical staining.

Immunocytochemical and enzyme histochemical analyses of cells and tissues are used to detect changes in the extent of injury and the expression of various molecules. Image analysis quantitation offers an easier, more efficient technique to evaluate these changes. We studied the application of image analysis for evaluating enzyme histochemistry and immunocytochemistry of cells and tissues as a way to assess stroke. Using brain sections, we compared investigator and computer-generated image analysis of 2,3,5-triphenyltetrazolium chloride stained cerebral infarcts in rats subjected to 2 h middle cerebral artery occlusion and 22 h re-perfusion. Both methods documented the infarct volumes with a comparison of means of less then 5%. This suggests no difference between computer- and hand-calculated values. Computer-generated analysis was easier and faster to use. Using endothelial cell monolayers, immunocytochemical staining of a time course of heat shock protein expression was compared to a grading system using fast red chromagen counterstained with hematoxylin. Results demonstrated greater ease and efficiency with computer-generated image analysis compared to other subjective systems of analysis. Image analysis is more useful for detecting small differences in staining, especially when using 3,3-diaminobenzidine as a chromagen. Investigator bias is also reduced using this system. Our comparisons validate the use of this versatile technology to assess more easily both cell and tissues in stroke research.

Animals↗
PubMed1994

Non-A, non-B fulminant hepatitis is also non-E and non-C.

OBJECTIVES: to define the roles of the hepatitis C and E viruses (HCV and HEV) in non-A, non-B (NANB) fulminant hepatitis. METHODS: we utilized the polymerase chain reaction to amplify HCV and HEV RNA sequences and assays to detect antibodies to HCV and HEV in the acute phase sera of eight presumed viral NANB and seven nonviral NANB fulminant hepatic failure (FHF) patients. RESULTS: none of the 15 patients had detectable HCV or HEV RNA or elevated HCV and IgM-HEV antibody titers in their acute phase sera. Three patients, all with features of autoimmune hepatitis, had raised IgG-HEV antibody titers. Due to the possibility of serologically undetectable hepatitis B virus (HBV) infection in fulminant hepatitis patients, we performed polymerase chain reaction amplification of HBV genomic DNA in acute phase sera of the presumed viral NANB FHF patients and subsequently found no evidence of HBV DNA. CONCLUSIONS: we did not find evidence implicating HCV or HEV in presumed viral NANB FHF or as agents contributing to or causing the liver failure in nonviral NANB FHF patients with autoimmune hepatitis, drug-induced hepatotoxicity, or halothane hepatotoxicity.

Adolescent↗
PubMed1991

Loss of heterozygosity suggests multiple genetic alterations in pheochromocytomas and medullary thyroid carcinomas.

Loss of heterozygosity (LOH) at specific loci may help localize tumor suppressor genes involved in the formation of various familial and sporadic tumors. In addition, the genetic loci for a number of familial tumor syndromes have been mapped by linkage analysis. To explore the possible role of tumor suppressor genes in endocrine tumors, we tested 41 pheochromocytomas (34 sporadic and 7 familial) and 11 medullary thyroid cancers (MTC) (10 sporadic and 1 familial) for LOH near a variety of potentially important genetic loci: (a) the multiple endocrine neoplasia type 2A (MEN 2A) locus on chromosome 10; (b) the von Hippel-Lindau locus on 3p; and (c) the p53 and neurofibromatosis 1 loci on 17. We also examined chromosomes 1p and 22q because previous studies in a small number of pheochromocytomas and MTCs suggested LOH in these regions. Background rates for LOH were assessed using several "random" probes. Finally, we examined a number of clinical and histologic characteristics of these tumors for possible correlations with specific genetic alterations. LOH in the region of the MEN 2A locus was uncommon (0% for MTCs, 5% for pheochromocytomas). However, we found significant allelic losses in pheochromocytomas on chromosomes 1p (42%), 3p (16%), 17p (24%), and 22q (31%). We also noted a correlation between LOH on 1p and urinary excretion of metanephrine by these patients (P = 0.02). LOH on 1p, 3p, and 17p also appeared to be associated with increased tumor volume. Analysis of the smaller number of MTCs demonstrated allelic losses on chromosomes 1p and 22q. Our results suggest that tumor formation and/or progression in pheochromocytomas and MTCs involves multiple genes, analogous with the model proposed for colon carcinoma.

Adolescent↗
PubMed1989

Hypothermic-induced electrocerebral silence, prolonged circulatory arrest, and cerebral protection during cardiovascular surgery.

Certain cardiovascular operations require cardiopulmonary bypass and prolonged circulatory arrest to provide an adequate operative field. Profound hypothermia is induced to protect brain function during these periods without cerebral perfusion. Because peripheral body temperatures may not be valid indicators of brain temperature, we conducted this study to establish an alternative, more reliable, method of determining the appropriate level of hypothermia. We measured peripheral body temperatures from 3 sites (rectum, nasopharynx, and esophagus) at the onset of hypothermic-induced electrocerebral silence (ECS) in the intraoperative electroencephalogram (EEG) of 56 adults undergoing cardiovascular procedures. The EEG in most patients showed a characteristic progression of changes from its normal resting state during cooling. Gradual depression and slowing of background rhythms was followed by generalized, periodic, slow-wave transients, prolongation of the intervals between the transients, and then the onset of ECS. In cases in which the slow-wave transients did not appear, the initial depression and slowing of background activity gradually progressed to ECS. No consistent relationship was found between peripheral body temperatures at various sites and the onset of ECS. Using EEG-guided hypothermia, there was low morbidity and mortality. These data suggest that ECS is a safe and reliable guide for determining the appropriate level of hypothermia during cardiovascular procedures.

Adult↗
PubMed1988

Determination of brain temperatures for safe circulatory arrest during cardiovascular operation.

Profound hypothermia protects cerebral function during circulatory arrest in the surgical treatment of a variety of cardiac and aortic abnormalities. Despite its importance, techniques to determine the appropriate level of hypothermia vary; studies of temperatures recorded from multiple peripheral body sites show inconsistent findings. The purpose of this study is to establish objective criteria to consistently identify intraoperatively the safe level of hypothermia. Our studies are based on experimental evidence showing a correlation between brain temperature and development of electrocerebral silence (ECS) on the electroencephalogram (EEG), and the recognition that the EEG, as an objective measure of brain function, can easily be recorded intraoperatively. We studied 56 patients who required circulatory arrest during operation for replacement of the ascending aorta or aortic arch (N = 55) or aortic valve replacement (N = 1). Peripheral body temperatures from the nasopharynx, esophagus, and rectum and the EEG were continuously recorded during body cooling. Circulatory arrest time ranged from 14 to 109 minutes. No peripheral body temperature from a single site or from a combination of sites consistently predicted ECS. There was a wide variation in temperature among body sites when ECS occurred: nasopharyngeal, 10.1 degrees to 24.1 degrees C; esophageal, 7.2 degrees to 23.1 degrees C; rectal, 12.8 degrees to 28.6 degrees C. Fifty-one (91%) of the 56 patients survived. Three had neurological deficits, none clearly related to hypothermia. Two patients (3.6%) required reexploration for postoperative bleeding. We conclude that monitoring the EEG to identify ECS is a safe, consistent, and objective method of determining the appropriate level of hypothermia.

Aorta↗
PubMed1988

The impact of distal aortic perfusion and somatosensory evoked potential monitoring on prevention of paraplegia after aortic aneurysm operation.

Temporary distal aortic perfusion and somatosensory evoked potential monitoring were attempted prospectively in 198 patients to prevent neurologic complications from occurring after operation for descending thoracic and thoracoabdominal aortic aneurysm. These 198 patients were divided into two groups. Group 1 consisted of 99 (50%) patients in whom adequate (60 mm Hg) distal bypass was achieved and combined with somatosensory evoked potential monitoring. Group 2 consisted of 99 (50%) in whom this could not be achieved. Of the latter, four patients were excluded because of operative death in one and preexisting neurologic deficits in three. The rates of early and delayed neurologic complications were 8% and 12%, respectively, in the former and 7% and 8%, respectively, in the latter. Using the logistic regression method of statistical analysis, adjusting for the difference in patient mix, we found no statistical difference in the incidence of neurologic complications in the two groups. The incidence of false negative somatosensory evoked potential response was 13% and false positive response 67%. Localization of critical spinal arteries for reattachment was not possible. Thus, the method had no significant impact upon the prevention of neurologic deficits, which varied from mild or transient to severe and which either occurred during the operation or were delayed from 12 hours to 21 days.

Aorta, Thoracic↗
PubMed1987

How hyperventilation alters the electroencephalogram: a review of controversial viewpoints emphasizing neurophysiological mechanisms.

This paper reviews the literature on the EEG effects of hyperventilation, with particular emphasis on the literature concerning the mechanism of EEG slowing with hyperventilation. We suggest that there is no definite evidence to support the theory that the EEG slowing and "activation" are caused by hypoxia secondary to cerebral vasoconstriction induced by hypocapnia during voluntary hyperventilation. Since it is known that hypocapnia produces decreased activity in the mesencephalic reticular formation and that lesions of the thalamus abolish the hyperventilation response, we propose a strong, albeit speculative, analogy between awake-sleep transitory states and the mechanism of EEG "activation" by hyperventilation. Furthermore, it is proposed that both the EEG changes and the associated clinical symptomatology (as well as changes in level of anesthesia, which vary with arterial PCO2) may be explained by altered arousal, and that the vasoconstriction observed during hyperventilation is a central neurogenic response to hypocapnia at a brainstem level.

Electroencephalography↗