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R V Shohet

Publications and source records attributed to R V Shohet.

14 recordsLinked to original sources
PubMed2002

MarC-V: a spreadsheet-based tool for analysis, normalization, and visualization of single cDNA microarray experiments.

The comprehensive analysis and visualization of data extracted from cDNA microarrays can be a time-consuming and error-prone process that becomes increasingly tedious with increased number of gene elements on a particular microarray. With the increasingly large number of gene elements on today's microarrays, analysis tools must be developed to meet this challenge. Here, we present MarC-V, a Microsoft Excel spreadsheet tool with Visual Basic macros to automate much of the visualization and calculation involved in the analysis process while providing the familiarity and flexibility of Excel. Automated features of this tool include (i) lower-bound thresholding, (ii) data normalization, (iii) generation of ratio frequency distribution plots, (iv) generation of scatter plots color-coded by expression level, (v) ratio scoring based on intensity measurements, (vi) filtering of data based on expression level or specific gene interests, and (vii) exporting data for subsequent multi-array analysis. MarC-V also has an importing function included for GenePix results (GPR) raw data files.

DNA, Complementary↗
PubMed2001

Apoptosis and proliferation in the neonatal murine heart.

The spatial and temporal patterns of apoptosis and proliferation in timed fetal, neonatal, and adult murine hearts have been determined using an in situ end-labeling technique for detecting fragmented DNA, and bromodeoxyuridine immunofluorescence as a marker for DNA synthesis. Also, cardiac expression of apoptosis-related proteins was assessed by immunofluorescence. Prominent apoptotic labeling was found in the right ventricular subendocardium and the basal septum in the area of the developing conduction system. In the right ventricle, apoptotic labeling surged late in the first day postpartum, then declined to levels similar to the left ventricle by postpartum day 8.5. Apoptotic labeling at the basal septum was greatest peripartum and gradually declined to levels seen in the rest of the heart by postpartum day 8.5. Cessation of proliferation did not occur simultaneously throughout the neonatal heart. Through postpartum day 4.5, incorporation of BrdU was greater in the left ventricle than in the right ventricle, particularly in the subendocardium. Bax and Fas, proapoptotic proteins, were detected homogeneously throughout both ventricles in the neonate, while Bcl-2, an antiapoptotic protein, was not detectable. These data suggest that postnatal cardiac remodeling results from changes in both apoptosis and proliferation. Furthermore, the temporal and spatial pattern of these processes, coincident with the hemodynamic changes associated with parturition, suggests that both processes may be regulated by mechanical factors.

Animals↗
PubMed2000

Repeat polymorphisms within gene regions: phenotypic and evolutionary implications.

We have developed an algorithm that predicted 11,265 potentially polymorphic tandem repeats within transcribed sequences. We estimate that 22% (2,207/9,717) of the annotated clusters within UniGene contain at least one potentially polymorphic locus. Our predictions were tested by allelotyping a panel of approximately 30 individuals for 5% of these regions, confirming polymorphism for more than half the loci tested. Our study indicates that tandem-repeat polymorphisms in genes are more common than is generally believed. Approximately 8% of these loci are within coding sequences and, if polymorphic, would result in frameshifts. Our catalogue of putative polymorphic repeats within transcribed sequences comprises a large set of potentially phenotypic or disease-causing loci. In addition, from the anomalous character of the repetitive sequences within unannotated clusters, we also conclude that the UniGene cluster count substantially overestimates the number of genes in the human genome. We hypothesize that polymorphisms in repeated sequences occur with some baseline distribution, on the basis of repeat homogeneity, size, and sequence composition, and that deviations from that distribution are indicative of the nature of selection pressure at that locus. We find evidence of selective maintenance of the ability of some genes to respond very rapidly, perhaps even on intragenerational timescales, to fluctuating selective pressures.

Algorithms↗
PubMed2000

Echocardiographic destruction of albumin microbubbles directs gene delivery to the myocardium.

BACKGROUND: The noninvasive, tissue-specific delivery of therapeutic agents to the heart would be a valuable clinical tool. This study addressed the hypothesis that albumin-coated microbubbles could be used to effectively deliver an adenoviral transgene to rat myocardium by ultrasound-mediated microbubble destruction. METHODS AND RESULTS: Recombinant adenovirus containing beta-galactosidase and driven by a constitutive promoter was attached to the surface of albumin-coated, perfluoropropane-filled microbubbles. These bubbles were infused into the jugular vein of rats with or without simultaneous echocardiography. Additional controls included ultrasound of microbubbles that did not contain virus, virus alone, and virus plus ultrasound. One group underwent ultrasound-mediated destruction of microbubbles followed by adenovirus infusion. Rats were killed after 4 days and examined for beta-galactosidase expression. The hearts of all rats that underwent ultrasound-mediated destruction of microbubbles containing virus showed nuclear staining with 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside substrate, indicating expression of the transgene. None of the control animals showed myocardial expression of the beta-galactosidase transgene. By quantitative analysis, beta-galactosidase activity was 10-fold higher in the treated group than in controls (P<0.0001). CONCLUSIONS: Ultrasound-mediated destruction of albumin-coated microbubbles is a promising method for the delivery of bioactive agents to the heart.

Albumins↗
PubMed1999

Plasma platelet-activating factor acetylhydrolase activity is not associated with premature coronary atherosclerosis.

Platelet-activating factor acetylhydrolase activity in plasma was compared between 72 subjects with angiographically normal coronary arteries and matched controls with clinically significant obstruction. No difference was seen, and we conclude that variation in plasma platelet-activating factor acetylhydrolase activity is not a risk factor for coronary artery disease.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗
PubMed1999

Hepatic lipase (LIPC) promoter polymorphism in men with coronary artery disease. Allele frequency and effects on hepatic lipase activity and plasma HDL-C concentrations.

Hepatic lipase is an important determinant of plasma HDL concentration and LDL subclass distribution and may therefore influence susceptibility to coronary artery disease (CAD). To assess the effect of genetic variation in hepatic lipase activity on CAD susceptibility, we determined the frequency of the -514T allele of hepatic lipase in white men with CAD and in controls who did not have CAD. In men with CAD, postheparin plasma hepatic lipase activity was 15% to 20% lower in heterozygotes and 30% lower in homozygotes for the -514T allele. Allele frequencies were similar in cases and controls, however, and were consistent with Hardy-Weinberg expectation in both groups. This finding was confirmed in a second group comprising cases with premature symptomatic CAD and controls who were free of disease. These data indicate that a primary decrease in hepatic lipase activity of as much as 30% does not influence susceptibility to CAD in white men.

Alleles↗
PubMed1998

Magnetic resonance imaging accurately estimates LV mass in a transgenic mouse model of cardiac hypertrophy.

Transgenic mice with a dysfunctional guanylyl cyclase A gene (GCA -/-) are unable to transduce the signals from atrial naturetic peptide and develop hypertension and cardiac hypertrophy. Magnetic resonance imaging (MRI) was performed to assess cardiac hypertrophy in these animals, using wild-type siblings as controls. Anesthetized mice were studied by gated multislice, multiphase cine MRI at 1.5 T. Simpson's rule was used to estimate left ventricle (LV) mass and volumes from short-axis images. Correlation between LV mass evaluated by MRI and at necropsy was excellent, with LVnecropsy = 1.04 x LVMRI + 4.69 mg (r2 = 0.95). By MRI, GCA -/- LV mass was significantly different when compared with isogenic controls [GCA -/-, 226 +/- 43 mg (n = 14) vs. controls, 156 +/- 14 mg (n = 10); P < 0.0001]. LV volumes and ejection fraction in the two groups were not significantly different. MRI provides an accurate means for the noninvasive assessment of murine cardiac phenotype and may be useful in following the effects of genetic modification.

Animals↗
PubMed1997

A human protein related to yeast Cdc6p.

The unstable proteins Cdc6p and cdc18+ are essential and rate limiting for the initiation of DNA replication in Saccharomyces cerevisiae and Schizosaccharomyces pombe, respectively, and also participate in checkpoint controls that ensure DNA replication is completed before mitosis is initiated. We have identified Xenopus and human proteins closely related to Cdc6p/cdc18. The human protein, p62(cdc6), is encoded on chromosome 17q21.3 and includes putative cyclin-dependent kinase phosphorylation sites, destruction boxes, a nucleotide binding/ATPase domain, and a potential leucine zipper. Expression of p62(cdc6) mRNA and protein is suppressed in human diploid fibroblasts made quiescent by serum starvation, and peaks as cells reenter the cell cycle and replicate DNA following serum stimulation. Conservation of structure among proteins involved in initiation suggests that fundamental features of replication complexes are maintained in all eukaryotes.

Amino Acid Sequence↗
PubMed1997

Analysis of the myoglobin gene in heart disease.

Analysis of the myoglobin gene from a large number of patients with cardiac disease disclosed a single substantive mutation. However, no evidence of biochemical or physiological dysfunction due to this mutation was detected. We conclude that, within the limits of presently available techniques, myoglobin mutations are unlikely to contribute substantially to the genotypic background of cardiac disease in the general population.

Carbon Monoxide↗
PubMed1995

Myocardial mRNA content and stability, and enzyme activities of Ca-cycling and aerobic metabolism in canine dilated cardiomyopathies.

Idiopathic dilated cardiomyopathy is associated with derangement of myocardial sarcoplasmic Ca-homeostasis and energy production. The molecular mechanism for these changes is unknown. Accordingly, we used genetic and experimentally-induced models of canine dilated cardiomyopathy and tested the hypothesis that these metabolic changes resulted from altered gene expression, as indicated by mRNA content. We studied dilated cardiomyopathy occurring naturally (n = 9) in Doberman pinschers, and in dogs subjected to rapid ventricular pacing (n = 5), in comparison with normal dogs (n = 9). We determined content and integrity of mRNA's using Northern and slot blotting, and measured activities of their translated product for the Ca-release channel and Ca-ATPase of sarcoplasmic reticulum, lactate dehydrogenase of glycolysis, citrate synthase of the tricarboxylic acid cycle, and for myoglobin, ATP-synthetase and the adenine nucleotide transporter, which are integral in oxidative phosphorylation. We found that, whereas both mRNA content and enzyme activity for markers of Ca-cycling, glycolysis, and oxidative phosphorylation were downregulated (20-80%) in dilated cardiomyopathy, they were upregulated (10-15%) for tricarboxylic acid cycling and for ribosomal RNA. RNA from cardiomyopathic tissue was up to 50% more degraded than for normal hearts in association with a 150% increase in ribonuclease activity. Downregulation of the Ca-cycle was asymmetric, with the Ca-channel being 65% more affected than the Ca-ATPase. This work supports the general paradigm that transcriptional and translational responses to pathophysiology are major determinants of the metabolic response seen in cardiac failure.

Animals↗
PubMed1994

Inhibitor-resistant tissue-type plasminogen activator: an improved thrombolytic agent in vitro.

Platelet-rich clots are inefficiently lysed by current fibrinolytic agents. Platelets contain a great deal of plasminogen activator inhibitor 1 (PAI-1), the principal endogenous inhibitor of tissue-type plasminogen activator (t-PA). We have tested whether PAI-1 resistant t-PAs would be more effective thrombolytic agents in an in vitro model of platelet-rich clots. Clots were formed with recalcified human plasma without or with the addition of platelets. The lysis of these clots was followed by the release of incorporated 125I-fibrinogen. Mutant and wild-type t-PA were almost equally effective against clots lacking platelets but the mutant was twice as effective at lysing platelet-rich clots. A mechanism for this effect is suggested by the demonstration that a complex between wild-type t-PA and extruded platelet contents resembles that between purified t-PA and PAI-1 and that the PAI-1 resistant t-PA does not interefer with formation of this adduct. Because of its enhanced ability to lyse platelet-rich clots in vitro, further in vivo work may find that PAI-1 resistant t-PA is a more efficacious therapeutic agent than wild-type t-PA in situations where platelets contribute to the failure of thrombolysis.

Animals↗
PubMed1989

Cloning of the cDNA encoding the myosin heavy chain of a vertebrate cellular myosin.

The complete amino acid sequence of a vertebrate cellular myosin heavy chain (MHC; 1,959 amino acids, 226 kDa) has been deduced by using cDNA clones from a chicken intestinal epithelial cell library. RNA blot analysis of kidney, spleen, brain, liver, and intestinal epithelial cells as well as smooth muscle cells from the aorta and gizzard indicates the presence of a 7.3-kilobase (kb) message that is larger than the message for chicken smooth and striated muscle MHC. The chicken intestinal epithelial cell MHC shows overall similarity in primary structure to other MHCs in the areas of the reactive thiol residues and in areas contributing to the ATP binding site and actin binding site. The globular head domain is followed by an alpha-helical coiled-coil region, and as in smooth muscle MHC there is a short uncoiled sequence at the carboxyl terminus of the molecule. Comparison of amino acid sequences in the rod regions between human and chicken cellular MHCs shows a remarkable 92% identity.

Amino Acid Sequence↗