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Biomedical subjects

Y Patel

Publications and source records attributed to Y Patel.

At least 91 records · Page 5Linked to original sources

Limited role of arteriography in penetrating neck trauma.

Of the patients with penetrating neck wounds treated between 1979 and 1986, 61 patients with 65 injuries had arteriography during their evaluation. Twenty-seven patients had stab wounds and 34 had gunshot wounds, with a relatively equal distribution between the zones of injury. Fifty-seven arteriograms were normal and six were abnormal. Of the six arteriographic defects, three were thought to be spurious on subsequent review, two were clinically insignificant, and one required surgery. No significant arterial injuries were identified by arteriography in the absence of suggestive physical findings. No major arterial injuries were discovered during neck surgery that were missed preoperatively. Neither abnormal nor normal angiograms significantly altered the course of management, including the approach to neck exploration. These data suggest that arteriography for penetrating neck trauma is usually unnecessary for observation of patients in stable condition without suggestive physical findings. Thorough neck exploration with dissection of the carotid sheath in patients with physical diagnostic criteria for surgery eliminates the need for angiography in most cases and avoids the consequences of a possible false-negative study.

Adolescent↗

Restriction endonucleases for pulsed field mapping of bacterial genomes.

Fundamental to many bacterial genome mapping strategies currently under development is the need to cleave the genome into a few large DNA fragments that can be resolved by pulsed field gel electrophoresis. Identification of endonucleases that infrequently cut a genome is of key importance in this process. We show that the tetranucleotide CTAG is extremely rare in most bacterial genomes with G+C contents above 45%. As a consequence, most of the sixteen bacterial genomes we have tested are cleaved less than once every 100,000 base pairs by one or more endonucleases that have CTAG in their recognition sequences: Xba I (TCTAGA), Spe I (ACTAGT), Avr II (CCTAGG) and Nhe I (GCTAGC). Similarly, CCG and CGG are the rarest trinucleotides in many genomes with G+C content of less than 45%. Thus, Sma I (CCCGGG), Rsr II (CGGWCCG), Nae I (GCCGGC) and Sac II (CCGCGG) are often suitable endonucleases for producing fragments that average over 100,000 base pairs from such genomes. Pulsed field gel electrophoresis of the fragments that result from cleavage with endonucleases that cleave only a few times per genome should assist in the physical mapping of many prokaryotic genomes.

Base Composition↗

Ethnic identity, self-esteem, and occupational aspirations of Indian and Anglo-Saxon British adolescents.

A questionnaire monitoring occupational aspiration, ethnic identification, adolescent experience, and self-esteem was administered to a large sample of Indian and Anglo-Saxon British male and female adolescents attending school in the West Midlands. The relationship between these variables and differences between the four groups were consistent with predictions derived from the social identity approach to intergroup relations and group behaviour (Tajfel & Turner, 1979). Indian males were found to possess a social mobility belief structure that mediates high occupational aspirations and keeness to marry out of their ethnic group. In contrast, Indian females were found to possess a social change belief structure associated with acceptance of the status quo and lower aspirations. Males and Anglo-Saxons reported higher self-esteem than females or Indians. The adolescent experience findings were less clear, but were consistent with the general interpretation of the data that the differences in intersex relations and gender-related experiences are contingent on ethnicity.

Adolescent↗

Lipid alterations induced by renal ischemia: pathogenic factor in membrane damage.

Lipids of the renal cortex and outer stripe of outer medulla were analyzed in rats during ischemia and 2 hr after blood reflow. After 15 min of ischemia, there were marked elevations of free fatty acids (FFA) and diacylglycerol (DG), increasing further at 60 min. Percentile increases were greater for polyunsaturated FFA. These elevations were accompanied by alterations in phospholipids (PL): Elevations of lysophosphatidylcholine (LPC) at 15 min, phosphatidic acid at 15 and 60 min, and declines of phosphatidylcholine and phosphatidylinositol at 60 min. Triacylglycerol (TG) showed only modest decline, at 60 min, and in insufficient degree to account for increments in FFA and DG. Two hours after 15 min of ischemia, LPC returned to control levels and other PL were normal except phosphatidylinositol which was decreased, and phosphatidic acid, which remained elevated. FFA and DG approached or reached control values. Two hours after 60 min of ischemia, LPC, FFA, DGs and phosphatidic acid remained elevated; phosphatidylcholine and phosphatidylinositol remained decreased. Histological injury was seen 2 and 24 hr after blood reflow only in kidneys injured by 60 min of ischemia. Thus, irreversible ischemic damage correlates with persistent abnormalities of phosphatidylcholine metabolism and persistent elevations of FFA, LPC, and DG. It is not known whether lipids break down at normal or accelerated rates during ischemia. In this context, accumulation of lipid breakdown products in ischemic cells may be due to failure of their reutilization, or disposal. Similarly, depletion of phospholipids during ischemia may be due to the inability of cells to reconstitute the lipid following degradation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Insulin and multiplication stimulating activity (an insulin-like growth factor) stimulate islet (beta-cell replication in neonatal rat pancreatic monolayer cultures.

A possible role for insulin in stimulating islet beta-cell replication was examined in neonatal rat pancreatic monolayer cultures. Addition of insulin to serum-free medium increased the mitotic index and stimulated dose-dependent increases in [3H]-thymidine incorporation in nuclei of islet beta-cells in aldehyde-thionine-stained autoradiographs. The effects of insulin were not associated with any significant changes in glucagon or somatostatin levels in the culture media. Multiplication stimulating activity (MSA), an insulin-like growth factor, was about 100-fold more potent than insulin: 3 ng/ml MSA stimulated a half-maximal increase in thymidine labeling of beta-cell (+63%, P less than 0.005), whereas 300 ng/ml insulin was required for a similar effect. The maximal effects of insulin and MSA were similar, and the combination of maximal stimulatory concentrations of MSA (30 ng/ml) and insulin (3000 ng/ml) was not more effective than either substance added alone, suggesting that both peptides act on the same mechanism(s) regulating beta-cell replication. Furthermore, an antibody to the insulin receptor did not prevent the stimulatory effects of either insulin or MSA on thymidine labeling of beta-cells. These results demonstrate that insulin can stimulate islet beta-cell replication directly, possibly through a receptor for MSA or another insulin-like growth factor.

Animals↗

Quantitation of endocrine cell content in the pancreas of nondiabetic and diabetic humans.

The application of immunofluorescence technique with anti-insulin, anti-glucagon, anti-somatostatin, and anti-pancreatic polypeptide (PP) antisera to sections of precisely sampled regions of the human pancreas allowed the quantitative evaluation of the total content of these four endocrine cell populations in 13 nondiabetics, in 2 insulin-dependent diabetics (IDDM), and in 2 non-insulin-dependent diabetic subjects (NIDDM) of various age and sex. In nondiabetic subjects, PP-cells appear sex-related. Male individuals have a significantly greater volume of PP-cells than female. In diabetic subjects, the only marked difference as compared with nondiabetics is the reduction of insulin cell volume in IDDM. Other small differences between individual endocrine cell volumes are detectable in both IDDM and NIDDM as compared with nondiabetics, but their significance is at present unclear. The qualitative changes of islet structure accompanying insulin cell reduction in IDDM were not considered in the present study.

Adolescent↗

Preparation of rat islet B-cell-enriched fractions by light-scatter flow cytometry.

Flow cytometry has been examined as a method to separate islet cells into homogeneous subpopulations. Collagenase-isolated rat islets were dissociated into single cells and these were analyzed and sorted according to their low forward angle light scattering properties by using automated flow cytometry. Light scatter histograms showed two peaks of viable cells. Radioimmunoassay of hormone content in cell fractions collected across the the two peaks showed that glucagon-containing cells were concentrated towards the left side of the left peak and somatostatin-containing cells were concentrated towards the right side of the left peak, whereas insulin-containing cells were clearly enriched in the right peak. The B-cell-enriched fraction (90% B cells, 3% A cells, 2% D cells) exhibited significant insulin secretory responses to glucose (16.7 mM), and 3-isobutyl-1-methylxanthine (0.1 mM), during a 24-h culture period, and these responses were slightly greater than those observed in the original mixed islet cell preparation (66% B cells, 14% A cells, and 4% D cells). These results indicate that flow cytometry can be applied to sort pancreatic islet cells into populations enriched in specific endocrine cell types for further study of the functions of individual cell types.

Animals↗

Mechanism of proximal tubule brush border loss and regeneration following mild renal ischemia.

Left kidneys of rats were made ischemic for 25 minutes and proximal tubule brush border alterations studied in the S1 and S2 segments. Scanning electron microscopy revealed that brush border microvilli became unstable, fused with one another, and were interiorized into proximal tubule cytoplasm soon after reflow of blood following ischemia. Rapid regeneration followed; scanning electron microscopy showed that regeneration occurred in a fashion whereby clusters of microvilli in flower-like configurations were extruded from the cell interior toward the surface. Such unique patterns of microvillus formation have not been reported before. Activity of the brush border enzymes, alkaline phosphatase and maltase, were not significantly depressed throughout the cycle of brush border loss and regeneration. Likewise, there were no alterations in the activity of beta-glucuronidase, a lysosomal enzyme. Alkaline phosphatase cytochemistry showed that microvillus membranes that were interiorized into the cell cytoplasm retained enzyme activity on their surfaces during the early period of brush border loss as well as during regeneration. These results strongly suggest that in reversibly injured proximal tubule cells regeneration of the brush border occurs primarily by a process of recycling of damaged, previously incorporated membrane. The nature of the initial membrane damage and the mechanism of recycling remain unknown.

Alkaline Phosphatase↗

Diagnostic significance of thyroid microsomal antibodies in randomly selected population.

A longitudinal study among the population of Busselton, Western Australia, has identified individuals with persistent and transient thyroid microsomal antibodies (TMA). 59 (72%) of 82 subjects with persistent TMA, 18 (72%) of 25 with recently developed TMA, and 12 (23%) of 53 with transient antibody were found to have subclinical hypothyroidism, as indicated by high serum thyroid stimulating hormone concentrations. This study reveals the high specificity, sensitivity, and predictive value of persistent or recently required TMA.

Adult↗

Pancreatic fat.

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Adipose Tissue↗

Glomerular filtration of proteins: clearance of anionic, neutral, and cationic horseradish peroxidase in the rat.

Glomerular permeability to horseradish peroxidase, a protein slightly smaller than rat albumin but similar in shape, was studied in Wistar-Furth rats by using a purified neutral isozyme (HRP; molecular radius, a(e) = 29.8 A) as well as an anionic succinyl-derivative (sHRP a(e) = 31.8 A) and a cationized enzyme (cHRP, a(e) = 30 A). The clearance rate of the proteins was determined over a 20-min period using the amounts of enzyme actually filtered (i.e., protein in the urine and protein reabsorbed by tubules). Fractional clearance of cationic HRP (0.338 +/- 0.019) exceeded that of neutral HRP (0.061 +/- 0.005) by a factor of 5.5 and that of anionic HRP (0.007 +/- 0.000) by a factor of 48. Tubular reabsorption was less than 10% of the filtered load. The experimental results indicate marked charge dependency of the filtration of proteins across the glomerulus. Fractional clearances for these proteins are significantly lower than those reported in the literature for dextrans of similar molecular radii. Other molecular properties such as shape and deformability may explain these differences.

Animals↗

Somatostatin biosynthesis occurs in pancreatic islets.

No information is at present available on the mode of SRIF biosynthesis. Since anglerfish pancreatic islet tissue is comprised of approximately 30% D cells, we have examined this tissue for SRIF synthesis . The following known differences in amino acid composition of islet peptides were used advantageously in this study: anglerfish proinsulin: Trp-0, Ile-2, Cys-6; anglerfish glucagon: Trp-1, Ile-0, Cys-0; mammalian SRIF: Trp-1, Ile-0, Cys-2. After incubating islet tissue with [3H]tryptophan and [14C]isoleucine or [35S]cystine for various time periods, proteins were extracted in 2 M acetic acid and desalted by Bio-Gel P-2 gel filtration. P-2 void volume proteins were then subjected to P-10 gel filtration and isolated by polyacrylamide gel electrophoresis (PAGE) at alkaline pH. The predominant amount of the immumoreactive SRIF in the extracts appeared in a peak eluting just before the salt volume on P-10 filtration and migrated slowly toward the cathode during PAGE. The behavior of synthetic SRIF was identical. The anglerfish SRIF immunoreactive peptide could be labeled with Trp and Cys but not Ile during incubations longer than 1 h. The Trp- and Cys-labeled peptide could be bound on columns to which the immunoglobulin fraction of antisera to SRIF had been complexed. Cycloheximide inhibited isotope incorporation into all islet proteins. These results indicate that islet SRIF is synthesized in situ. Moreover, the immunological activity, size, and charge characteristics of anglerfish islet SRIF appear to be similar to those of mammalian hypothalamic SRIF. When islets were subjected to short pulse incubations with labeled Trp and Cys, only peptides eluting in the 7,000-13,000 dalton portion of the filtration eluate became labeled. No appreciable isotope incorporation into SRIF was observed. However, when pulse incubations were followed by incubation in the presence of cycloheximide or excess unlabeled amino acids in isotope-free medium (chase), the incorporation of Trp and Cys into SRIF increased with the length of chase, suggesting the participation of a larger precursor in SRIF synthesis.

Animals↗

Somatostatin in human cerebrospinal fluid.

To determine whether somatostatin is found in the hypothalamus and extrahypothalamic brain, we studied autopsy brain tissue by specific immunoassay. The hypothalamus contained the highest concentration (16.7 +/- 2.4 S.D. pg per microgram of protein), with small amounts in brainstem, cerebral cortex, cerebellum, pineal gland and spinal cord. Cerebrospinal fluid of seven neurologically normal persons also contained somatostatin in concentrations ranging from 15 to 55 pg per milliliter. To determine whether brain disease leads to abnormal cerebrospinal-fluid somatostatin, we examined 30 patients with neurologic disease, of whom 20 of 24 with cord or cerebral disease had concentrations above the highest normal level. The wide variety of diseases with somatostatin elevation suggests nonspecific leakage from damaged brain tissue. Cerebrospinal-fluid somatostatin may provide a good index of brain damage. Although correlated statistically with cerebrospinal-fluid protein, somatostatin concentration in five of 24 cases exceeded the upper limit of normal by 3 S.D. while protein was normal.

Adolescent↗

Post-translationally modified 14-3-3 isoforms and inhibition of protein kinase C.

This report compares the ability of individual members of the 14-3-3 protein family to inhibit particular protein kinase C (PKC) isoforms. We also show that two of these 14-3-3 isoforms (alpha and delta) specific to mammalian and avian brain are in vivo post-translationally modified forms of beta and zeta respectively. The presence of this modification enhances the activity of 14-3-3 as an inhibitor of protein kinase C nearly two fold. A method for analysing isoforms of 14-3-3 on acid-urea gels is also described. This permits the complete separation of all major isoforms and their unequivocal identification by a range of isoform specific antisera. The activity of recombinant 14-3-3 and isoforms renatured by a novel method after separation by reverse phase HPLC are compared. The effects of diacylglycerol and the phorbol ester, PMA (phorbol 1 2-myristate 13 acetate) on the inhibition suggest that one of the sites of interaction of 14-3-3 may be the cysteine-rich (C1) domain in PKC.

14-3-3 Proteins↗