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Biomedical subjects

A Mehta

Publications and source records attributed to A Mehta.

At least 37 records · Page 2Linked to original sources
PubMed2000

The HSV 1 genome in quiescently infected NGF differentiated PC12 cells can not be stimulated by HSV superinfection.

This study reports that quiescent herpes simplex virus (HSV) type 1 genomes, persisting in long-term infected nerve growth factor (NGF) differentiated PC12 cells, were not stimulated by superinfection with a HSV-1. We have previously shown that HSV-1 can establish long term, quiescent infections in NGF differentiated PC12 cells. To determine if virion associated factors or virus induced gene products could trans-activate the quiescent viral genomes, long term infected PC12 cell cultures were superinfected at a high moi (moi of 20) with a recombinant HSV 17alpha47/lacZ that contains the lacZ gene within the alpha 47 locus. Progeny virus and gene expression from the resident 'quiescent' viral genomes were not detected following superinfection with recombinant 17alpha47/lacZ. The failure to stimulate the quiescent genome appears to be related to the inability of the super infecting virus to induce any gene expression from its own genome following entry into the long term NGF treated PC12 cells. Interestingly, both primary and superinfecting viruses could be stimulated from the quiescently infected cultures following cocultivation with inducer cells. These data suggest that (i) HSV genomes in quiescently infected PC12 cells are unable to be stimulated by incoming virion associated factors and (ii) NGF differentiated PC12 cells maintained in tissue culture for longer than 3 weeks became completely refractory to viral gene expression. The possibilities that these results are reflective of populations of neural cells, in vivo in mouse central nervous system, which are completely refractory to virus gene expression, yet accommodating to the maintenance of viral genomes and thus favor 'latency', are discussed.

Animals↗
PubMed2000

The deadly double infarct syndrome treated by two-vessel primary angioplasty and stenting.

Percutaneous transluminal primary angioplasty (PTCA) has become an accepted therapy for treatment of acute myocardial infarction. Coronary stenting in the setting of acute myocardial infarction has been found to have several advantages, and has been successfully performed routinely at various centers. However, we are unaware of any report that describes successful angioplasty performed on two simultaneously occluded coronary arteries (the deadly double infarct syndrome). This is the first report of successful primary angioplasty with stenting performed on a patient with occlusion of two vessels simultaneously. We review the literature and suggest that this may prove to be a viable alternative in an emergency in two-vessel coronary artery bypass grafting.

Angioplasty, Balloon, Coronary↗
PubMed1999

Early repolarization.

Early repolarization (ER) is an enigma. The purpose of this review is to reemphasize the overall electrocardiographic (ECG) pattern of this normal ST variant which continues to challenge the clinician because of its similarity to the current of injury potential to myocardium or an acute pericarditis. The data were provided from the studies identified through computerized searches of Medline, Toxline, Oxford, Agricola, and Bios Afterdark, Cumulative index, and a review of bibliographies of relevant articles on the related subjects. Early repolarization has elevated, upward, concave ST segments, located commonly in precordial leads, with reciprocal depression in a VR, tall, peaked and slightly asymmetrical T waves with notch, and slur on the R wave. The other accompanying features in the ECG are vertical axis, shorter and depressed P-R interval, abrupt transition, counterclockwise rotation, presence of U waves, and sinus bradycardia. Males dominate and patients are often younger than 50 years of age. The incidence of 1 to 2% is found equally common in all races. Degree and incidence of ST elevation decrease as age advances. Exercise or isoproterenol administration may normalize the ST segment. Early repolarization is a benign condition. If the ECG conforms to a classical pattern of ER on serial ECGs, it would exclude the unnecessary hazards of present day revascularization therapy for myocardial infarction such as primary angioplasty or thrombolytic therapy, or aggressive management of acute pericarditis, and so forth. This review concludes with a discussion of comparative ECG features of ER, pericarditis, and myocardial infarction, and provides an algorithm for diagnostic management of patients suffering from these conditions.

Acute Disease↗
PubMed1999

Constrictive pericarditis.

The diagnosis of constrictive pericarditis remains a challenge because its physical findings and hemodynamics mimic restrictive cardiomyopathy. Various diagnostic advances over the years enable us to differentiate between these two conditions. This review begins with a case report of constrictive pericarditis, followed by a brief history and discussions of etiologies. Clinical features, radiologic, electrocardiographic, angiographic findings, and hemodynamics of constrictive pericarditis are reviewed. The echocardiographic findings are detailed and the recent advances in Doppler flow velocity patterns of pulmonary, mitral, tricuspid valves and hepatic veins are reported. Nuclear ventriculograms depict rapid ventricular filling in constrictive pericarditis and differentiate it from restrictive cardiomyopathy. Endomyocardial biopsy helps further in recognizing the various types of restrictive cardiomyopathies. Computed tomography and magnetic resonance imaging delineate abnormal pericardial thickness in constrictive pericarditis. Association of characteristic hemodynamic changes and abnormal pericardial thickness > 3 mm usually confirms the diagnosis of constrictive pericarditis. Effusive and occult varieties of constrictive pericarditis are briefly described. This review concludes with emphasizing the importance of pericardial resection.

Adult↗
PubMed1999

Enhancing availability of the electronic image record for patients and caregivers during follow-up care.

PURPOSE: To develop a personal computer (PC)-based software package that allows portability of the electronic imaging record. To create custom software that enhances the transfer of images in two fashions. Firstly, to an end user, whether physician or patient, provide a browser capable of viewing digital images on a conventional personal computer. Second, to provide the ability to transfer the archived Digital Imaging and Communications in Medicine (DICOM) images to other institutional picture archiving and communications systems (PACS) through a transfer engine. METHOD/MATERIALS: Radiologic studies are provided on a CD-ROM. This CD-ROM contains a copy of the browser to view images, a DICOM-based engine to transfer images to the receiving institutional PACS, and copies of all pertinent imaging studies for the particular patient. The host computer system in an Intel based Pentium 90 MHz PC with Microsoft Windows 95 software (Microsoft Inc, Seattle, WA). The system has 48 MB of random access memory, a 3.0 GB hard disk, and a Smart and Friendly CD-R 2006 CD-ROM recorder (Smart and Friendly Inc, Chatsworth, CA). RESULTS: Each CD-ROM disc can hold 640 MB of data. In our experience, this houses anywhere from, based on Table 1, 12 to 30 computed tomography (CT) examinations, 24 to 80 magnetic resonance (MR) examinations, 60 to 128 ultrasound examinations, 32 to 64 computed radiographic examinations, 80 digitized x-rays, or five digitized mammography examinations. We have been able to successfully transfer DICOM images from one DICOM-based PACS to another DICOM-based PACS. This is accomplished by inserting the created CD-ROM onto a CD drive attached to the receiving PACS and running the transfer engine application. CONCLUSIONS: Providing copies of radiologic studies performed to the patient is a necessity in every radiology department. Conventionally, film libraries have provided copies to the patient generating issues of cost of loss of film, as well as mailing costs. This software package saves costs and loss of studies, as well as improving patient care by enabling the patient to maintain an archive of their electronic imaging record.

CD-ROM↗
PubMed1999

Hepatitis C lookback programme: a single hospital experience.

As part of the national Hepatitis C (HCV) Lookback Programme, HCV-infected donors donating blood after September 1991 were identified and the fate of their previous donations received at a single hospital were traced; 123 of 160 implicated blood components were traceable and transfused. Only 19 recipients were alive and traceable and were tested for HCV. Nine of the 14 recipients (64%) of HCV-positive donations and 2 of 5 recipients (40%) of HCV-indeterminate donations had evidence of HCV infection. Neither the number of donor exposures nor the type of component was predictive of recipient HCV status. Three recipients have chronic active hepatitis. The Hepatitis C Lookback Programme successfully identifies some but not all cases of transfusion-transmitted HCV. Transfusion records, particularly in the medical case notes, should be substantially improved. Many of the traced recipients are young, so that identification of HCV is of great importance.

Adolescent↗
PubMed1999

Na+ and K+ regulate the phosphorylation state of nucleoside diphosphate kinase in human airway epithelium.

We describe how cations, in the presence of ATP, regulate the phosphorylated form of 19- and 21-kDa nucleoside diphosphate kinase (NDPK; EC 2.7.4.6), a kinase controlling K+ channels, G proteins, cell secretion, cellular energy production, and UTP synthesis. In apically enriched human nasal epithelial membranes, 10 mM Na+ inhibits phosphorylation of NDPK relative to other cations. Dose response showed that, whereas K+ induces a fourfold greater phosphate incorporation (EC50 10 mM), Na+ is inhibitory (EC50 10 mM) compared with respective buffer controls. Cation discrimination is nucleotide selective (not seen with [gamma-32P]GTP) and NDPK specific (not seen with p37h, a previously characterized Cl--sensitive phosphoprotein). Na+ does not exert an inhibitory effect on NDPK phosphorylation directly but is likely to act via an okadaic acid-insensitive phosphatase. We speculate that the ability of NDPK to discriminate between physiologically relevant cation concentrations provides a novel example of cross talk within the apical membrane.

Adenosine Triphosphate↗
PubMed1999

A World Wide Web Internet engine for collaborative entry and peer review of radiologic teaching files.

OBJECTIVE: Radiologists can now use the Internet as a dissemination medium for radiologic teaching files. This has greatly increased the availability of radiologic information to a larger number of people. However, the creation of the teaching files themselves remains a static and labor-intensive process. As a partial solution to this problem, we set out to create a World Wide Web-based Internet engine for the collaborative entry and peer review of radiologic teaching files. CONCLUSION: We created a system that facilitates, simplifies, and improves the generation of radiologic teaching files. We used the Internet to help promote the creation of teaching files in a more timely, efficient, and effective manner.

Audiovisual Aids↗
PubMed1999

Effect of Salmonella typhimurium enterotoxin (S-LT) on lipid peroxidation and cell viability levels of isolated rat enterocytes.

Reactive oxygen species (ROS) are potent mediators of inflammatory disorders and may be of pathophysiological importance in S. typhimurium induced tissue damage. This study was carried out to investigate if ROS play a role in mediating the enterocyte damage during in vitro exposure to Salmonella typhimurium enterotoxin (S-LT). The ROS generation was detected by measuring the changes in the enterocyte arachidonic acid (AA) metabolism (measured indirectly by estimating the level of enterocyte damage in the absence and presence of the cyclooxygenase inhibitor, indomethacin) and xanthine oxidase activity. The enterocyte damage was estimated by measuring the changes in the level of lipid peroxidation and cell viability. The results obtained showed that the exposure of isolated rat enterocytes to S-LT resulted in an increased XO activity; an increased arachidonic acid metabolism, dose and time dependent increase in the level of lipid peroxidation and decreased cell viability. Lipid peroxidation decreased and cell viability increased in the presence of the antioxidant enzymes superoxide dismutase (SOD) or catalase. Thus the in vitro exposure of the enterocytes to S-LT is accompanied by an increased generation of ROS which may induce the lipid peroxidation of the enterocyte membrane thereby leading to a loss of cell viability.

Animals↗
PubMed1999

Unusual mode of spread and presentation of meningioma: a case report.

Although rare, extracranial extension of a meningioma has been well documented. An interesting natural history of neglected meningioma with skull vault hyperostosis and predominantly extracranial extension is described. Following surgical resection of the highly vascular meningioma, the patient developed fatal coagulopathy.

Adult↗
PubMed1998

Rapid quantitation of free fatty acids in human plasma by high-performance liquid chromatography.

We report a rapid and sensitive method for separation and quantitation of free fatty acids (FFAs) in human plasma using high-performance liquid chromatography (HPLC). Two established techniques of lipid extraction were investigated and modified to achieve maximal FFA recovery in a reasonably short time period. A modified Dole extraction method exhibited greater recovery (approximately 90%) and short processing times (30 min) compared to the method of Miles et al. Reversed-phase HPLC using UV detection was used for plasma FFA separation and quantitation. Two phenacyl ester derivatives, phenacyl bromide and p-bromophenacyl bromide, were investigated in order to achieve optimal separation of individual plasma FFAs (saturated and unsaturated) with desirable detection limits. Different chromatographic parameters including column temperature, column type and elution profiles (isocratic and gradient) were tested to achieve optimal separation and recovery of fatty acids. Phenacyl bromide esters of plasma fatty acids were best resolved using an octadecylsilyl column with endcapped silanol groups. An isocratic elution method using acetonitrile-water (83:17) at 2 ml/min with UV detection at 242 nm and a column temperature of 45 degrees C was found to optimally resolve the six major free fatty acids present in human plasma (myristic [14:0], palmitic [16:0], palmitoleic [16:1], stearic [18:0], oleic [18:1] and linoleic [18:2]), with a run time of less than 35 min and detection limits in the nmol range. The entire process including plasma extraction, pre-column derivatization, and HPLC quantitation can be completed in approximately 90 min with plasma samples as small as 50 microl. Over a wide physiological range, plasma FFA concentrations determined using our HPLC method agree closely with measurements using established TLC-GC methods (r2 < or = 0.95). In addition, by measuring [14C] or [3H] radioactivity in eluent fractions following HPLC separation of plasma FFA, this method can also quantitate rates of FFA turnover in vivo in human metabolic studies employing isotopic tracers of one or more fatty acids.

Chromatography, High Pressure Liquid↗