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Biomedical subjects

J Bryan

Publications and source records attributed to J Bryan.

At least 109 records · Page 6Linked to original sources
PubMed1996

The predictive value of KT/V and peritoneal solute transport in CAPD patients is dependent on the type of comorbidity present.

Comorbidity, age, dialysis dose (KT/V(urea)), plasma albumin, and peritoneal function (D/P(creat) were measured cross-sectionally in 228 continuous ambulatory peritoneal dialysis (CAPD) patients, who were then followed up for a mean of two years. Comorbidity, utilizing a semi-quantitative score described previously, was the most powerful predictor of mortality in both univariate and multivariate analysis. Using univariate analysis, all the variables predicted outcome with statistical significance, mortality being associated with lower KT/V and plasma albumin and a higher D/P(creat). On multivariate analysis only comorbidity, age, and KT/V remained independent predictors. Data was further analyzed on the basis of type of comorbid condition. In those patients without comorbid disease (n = 127) neither KT/V, albumin nor D/P(creat) predicted outcome. In patients with clinical evidence of ischemic heart disease the KT/V was a significant predictor of favorable outcome. In those with clinical evidence of left ventricular function, mortality was significantly and independently associated with low plasma albumin, high D/P(creat), and KT/V. It is suggested that the concept of treatment adequacy in CAPD patients must include both measures of dialysis dose and peritoneal function, particularly in the context of the patient's comorbidity.

Adolescent↗
PubMed1995

Reconstitution of IKATP: an inward rectifier subunit plus the sulfonylurea receptor.

A member of the inwardly rectifying potassium channel family was cloned here. The channel, called BIR (Kir6.2), was expressed in large amounts in rat pancreatic islets and glucose-responsive insulin-secreting cell lines. Coexpression with the sulfonylurea receptor SUR reconstituted an inwardly rectifying potassium conductance of 76 picosiemens that was sensitive to adenosine triphosphate (ATP) (IKATP) and was inhibited by sulfonylureas and activated by diazoxide. The data indicate that these pancreatic beta cell potassium channels are a complex composed of at least two subunits--BIR, a member of the inward rectifier potassium channel family, and SUR, a member of the ATP-binding cassette superfamily. Gene mapping data show that these two potassium channel subunit genes are clustered on human chromosome 11 at position 11p15.1.

ATP-Binding Cassette Transporters↗
PubMed1995

Versatile E. coli thioredoxin specific monoclonal antibodies afford convenient analysis and purification of prokaryote expressed soluble fusion protein.

A recently developed E. coli thioredoxin (Trx) gene fusion expression system has circumvented the difficulties associated with inclusion body formation. Although ample quantities of soluble recombinant protein can be expressed using this system, no universal means of quantifying or purifying the fusion product exists. To facilitate the study of Trx fusion proteins, anti-E. coli Trx monoclonal antibodies (mAb) were generated. Two distinct Trx epitopes were defined by competitive ELISA. Both mAb were capable of detecting Trx fusion proteins by sandwich ELISA, and by immunoblot analysis under reducing and non-reducing conditions. In addition, these mAb enabled purification of Trx fusion proteins by immunoprecipitation, as well as affinity chromatography. This report provides the first description of anti-Trx antibodies. These reagents represent a major advance in the isolation and analysis of prokaryote expressed recombinant Trx fusion proteins.

Chromatography, Affinity↗
PubMed1995

Cloning and expression of a murine fascin homolog from mouse brain.

The fascins are a widely distributed family of proteins that organize filamentous actin into bundles. We have cloned, sequenced, and expressed the murine homolog. Fascin is most abundant in brain and is found in other tissues including uterus and spleen. The deduced open reading frame encodes a protein of 493 amino acids with a molecular mass of 54,412 Da. Previous solubility problems with bacterially expressed fascins were overcome by producing the mouse protein as a fusion with Escherichia coli thioredoxin. A method for cleaving the fusion protein and for purifying active recombinant fascin is described. The N-terminal sequence and molecular mass estimated on SDS gels indicate that recombinant fascin is full-length. Two-dimensional gel electrophoresis suggests that recombinant fascin is post-translationally modified in a manner similar to that observed in mouse brain. Recombinant fascin and the fusion protein are recognized by monoclonal anti-fascin antibodies and will bundle rabbit skeletal muscle F-actin in vitro at a stoichiometry of 4.1:1 actin to fascin. Electron cryomicroscopy images show that the reconstituted bundles are highly ordered. However, their fine structure differs from that of echinoid fascin-actin bundles. This structural difference can be attributed to fascin.

Acetylation↗
PubMed1995

Cloning of the beta cell high-affinity sulfonylurea receptor: a regulator of insulin secretion.

Sulfonylureas are a class of drugs widely used to promote insulin secretion in the treatment of non-insulin-dependent diabetes mellitus. These drugs interact with the sulfonylurea receptor of pancreatic beta cells and inhibit the conductance of adenosine triphosphate (ATP)-dependent potassium (KATP) channels. Cloning of complementary DNAs for the high-affinity sulfonylurea receptor indicates that it is a member of the ATP-binding cassette or traffic ATPase superfamily with multiple membrane-spanning domains and two nucleotide binding folds. The results suggest that the sulfonylurea receptor may sense changes in ATP and ADP concentration, affect KATP channel activity, and thereby modulate insulin release.

ATP-Binding Cassette Transporters↗
PubMed1995

Mutations in the sulfonylurea receptor gene in familial persistent hyperinsulinemic hypoglycemia of infancy.

Familial persistent hyperinsulinemic hypoglycemia of infancy (PHHI), an autosomal recessive disorder characterized by unregulated insulin secretion, is linked to chromosome 11p14-15.1. The newly cloned high-affinity sulfonylurea receptor (SUR) gene, a regulator of insulin secretion, was mapped to 11p15.1 by means of fluorescence in situ hybridization. Two separate SUR gene splice site mutations, which segregated with disease phenotype, were identified in affected individuals from nine different families. Both mutations resulted in aberrant processing of the RNA sequence and disruption of the putative second nucleotide binding domain of the SUR protein. Abnormal insulin secretion in PHHI appears to be caused by mutations in the SUR gene.

ATP-Binding Cassette Transporters↗
PubMed1995

Fascins, a family of actin bundling proteins.

Fascin is an actin-bundling protein that was first isolated from cytoplasmic extracts of sea urchin eggs [Kane, 1975: J. Cell Biol. 66:305-315] and was the first bundling protein to be characterized in vitro. Subsequent work has shown that fascin bundles actin filaments in fertilized egg microvilli and filopodia of phagocytic coelomocytes [Otto et al., 1980: Cell Motil. 1:31-40; Otto and Bryan, 1981: Cell Motil. 1:179-192]. Fifteen years later, the molecular cloning of sea urchin fascin [Bryan et al., 1993: Proc. Natl. Acad. Sci. U.S.A. 90:9115-9119] has led to the identification and characterization of homologous proteins in Drosophila [Cant et al., 1994: J. Cell Biol. 125:369-380], Xenopus [Holthuis et al., 1994: Biochim. Biophys. Acta. 1219:184-188], rodents [Edwards et al,. 1995: J. Biol. Chem. 270:10764-10770], and humans [Duh et al., 1994: DNA Cell Biol. 13:821-827; Mosialos et al., 1994: J. Virol. 68:7320-7328] that bundle actin filaments into structures which stabilize cellular processes ranging from mechanosensory bristles to the filopodia of nerve growth cones. Fascin has emerged from relative obscurity as an exotic invertebrate egg protein to being recognized as a widely expressed protein found in a broad spectrum of tissues and organisms. The purpose of this review is to relate the early studies done on the sea urchin and HeLa cell fascins to the recent molecular biology that defines a family of bundling proteins, and discuss the current state of knowledge regarding fascin structure and function.

Actins↗
PubMed1995

Over-expression of smooth muscle caldesmon in mouse fibroblasts.

Caldesmon is an actin, calmodulin, tropomyosin, and myosin binding protein implicated in the regulation of actomyosin interactions. We have investigated the effect of overexpression of the higher molecular weight smooth muscle isoform of caldesmon on mouse L cell physiology. Mouse L(TK-) cells were transfected stably with plasmids carrying the TK+ gene and a full length human smooth muscle caldesmon cDNA under control of the adenovirus major late promoter. Two clones displaying four and eight times the level of the endogenous mouse high molecular weight caldesmon were isolated. These cells acquire a distinct phenotype characterized by an altered morphology, including an increased number of processes and larger area due to enhanced cell spreading, and a significantly slower growth rate than that of untransfected control cells, or cells transfected with the TK+ gene alone. The majority of the overexpressed caldesmon appears to be active and localized on cytoskeleton structures as determined by detergent lysis. Immunofluorescence analysis of the clones revealed that the caldesmon is localized as punctate staining on stress-fibers and in membrane ruffles. The immunofluorescence images suggest that caldesmon overexpressing cells have more total filaments than control cells. The effects of excess caldesmon on cell mobility are ambiguous: one clone displayed increased motility compared to the control, while the motility of the second clone was decreased relative to the control.

Actins↗
PubMed1995

Comorbidity, urea kinetics, and appetite in continuous ambulatory peritoneal dialysis patients: their interrelationship and prediction of survival.

Comorbidity, urea kinetics (Kt/V and normalized protein catabolic rate), dietary protein, total calorie intake, and plasma albumin were measured in 97 continuous ambulatory peritoneal dialysis patients followed prospectively for 30 months. Comorbid disease was graded severe in 12 patients, intermediate in 29, and absent in 56. At entry to the study comorbidity was associated with increased age (P = 0.001), lower dietary protein (P = 0.015) and calorie intake (P = 0.02), and a lower plasma creatinine (P = 0.026). Trends toward lower Kt/V and albumin were not significant, and normalized protein catabolic rate was unaffected. Ability of these measures to predict mortality was assessed by univariate and multivariate analysis using Cox's proportional hazard model. On univariate analysis, comorbidity (P < 0.0001), age (P = 0.0001), Kt/V (P = 0.009), plasma albumin (P = 0.009), calorie intake (P = 0.035), and dietary protein intake (P = 0.03) predicted outcome, whereas normalized protein catabolic rate did not (P = 0.46). Multivariate analysis indicated that comorbidity (P = 0.0003) and age (P = 0.0085) were the only independent predictors of outcome. The addition of plasma albumin and Kt/V increased the significance of the Cox model. Further analysis of comorbidity demonstrated the relative importance of vascular disease and left ventricular dysfunction. This study illustrates the profound influence of comorbid disease on mortality in continuous ambulatory peritoneal dialysis patients and suggests that it causes suppression of appetite independent of the dialysis dose.

Adolescent↗
PubMed1995

National survey of emergency medicine resident moonlighting. SAEM Inservice Examination Survey Task Force.

OBJECTIVES: To survey emergency medicine (EM) residents regarding moonlighting practices and perceptions for clarifying: 1) resident moonlighting remuneration; 2) any association of perceived educational debt with moonlighting income and hours; and 3) perceptions related to moonlighting (including motivations, impact on resident training, and potential medicolegal difficulties). METHODS: A confidential, voluntary survey was administered to all allopathic EM residents in the United States. This written survey was provided to residents at their in-service examinations. Completed forms were anonymously returned by residents or local administrative staff to a central site where all identifiers were removed prior to mailing en mass to the investigators. Comparisons between groups were made using chi-square tests and correlations were assessed using the Pearson correlation coefficient. RESULTS: Seventy-six percent (1,826/2,407) of the surveys were returned. There was a weak correlation (r = 0.11) between educational debt and moonlighting hours for residents in the second year and above, but no association of debt with moonlighting income. Most (88%) of the residents reported that their programs permitted moonlighting. Nearly half (49%) reported that they did moonlight in some way. Most (82%) thought moonlighting provided experience not available in the residency. Only 13 (2%) respondents stated they had been sued for malpractice while moonlighting. Most (66%) moonlighting respondents stated that they moonlighted for financial reasons, with educational debt the primary motivating factor. Of the moonlighting residents, 28% were unsure of their type of malpractice insurance coverage, and 9% had no coverage at all. CONCLUSIONS: Education about EM practice matters including the risks of moonlighting should begin early in residency, because moonlighting is widespread. Residents are vulnerable to medicolegal action while moonlighting and have insufficient knowledge of their malpractice insurance coverage. Although educational debt is perceived as a strong motivating factor for moonlighting, there is only a weak relationship between educational debt and moonlighting hours.

Analysis of Variance↗
PubMed1995

A 32-nucleotide exon-splicing enhancer regulates usage of competing 5' splice sites in a differential internal exon.

Large alternatively spliced internal exons are uncommon in vertebrate genes, and the mechanisms governing their usage are unknown. In this report, we examined alternative splicing of a 1-kb internal exon from the human caldesmon gene containing two regulated 5' splice sites that are 687 nucleotides apart. In cell lines normally splicing caldesmon RNA via utilization of the exon-internal 5' splice site, inclusion of the differential exon required a long purine-rich sequence located between the two competing 5' splice sites. This element consisted of four identical 32-nucleotide purine-rich repeats that resemble exon-splicing enhancers (ESE) identified in other genes. One 32-nucleotide repeat supported exon inclusion, repressed usage of the terminal 5' splice site, and functioned in a heterologous exon dependent on exon enhancers for inclusion, indicating that the caldesmon purine-rich sequence can be classified as an ESE. The ESE was required for utilization of the internal 5' splice site only in the presence of the competing 5' splice site and had no effect when placed downstream of the terminal 5' splice site. In the absence of the internal 5' splice site, the ESE activated a normally silent cryptic 5' splice site near the natural internal 5' splice site, indicating that the ESE stimulates upstream 5' splice site selection. We propose that the caldesmon ESE functions to regulate competition between two 5' splice sites within a differential internal exon.

Alternative Splicing↗
PubMed1995

Nerve damage associated with inferior alveolar nerve blocks.

The authors reviewed 12 cases in which altered sensation occurred in the distribution of the inferior alveolar or lingual nerves following injection of a local anesthetic for restorative treatment only. Most patients suffered only partial damage, but recovery was poor. The exact mechanism of the nerve damage is unknown, but a number of theories are proposed. The extent of this problem is also unknown, but many more cases probably exist than have been reported to date.

Adult↗
PubMed1995

Posterior cortical violation of the femoral tunnel during endoscopic anterior cruciate ligament reconstruction.

Endoscopic reaming of the femoral tunnel has several advantages over "two-incision" techniques but has a greater potential for posterior cortical violation. Proper guide pin placement and adequate knee flexion during endoscopic reaming are key to avoiding posterior cortical violation. When the posterior femoral cortex is compromised, options include "over-the-top" graft passage and fixation with screw and post or conversion to the traditional "two-incision" technique. The two-incision tunnel should be started more anterior on the lateral femoral cortex to achieve greater divergence from the endoscopic tunnel. This may allow interference screw fixation of a patella tendon anterior cruciate ligament graft. This article examines the technical factors affecting the development of posterior cortical violation and discusses options for management.

Anterior Cruciate Ligament↗
PubMed1994

Colocalization of human papillomavirus type 11 E1[symbol: see text]E4 and L1 proteins in human foreskin implants grown in athymic mice.

The most abundant viral mRNA species in tissues infected with HPV 11 consists of two exons, joining a short segment of open reading frame (ORF) E1 to ORF E4, potentially encoding an protein of 10 kDa. E4 gene products have previously been identified by immunohistochemistry in human tissues infected with HPV 1 and HPV 16, and in HPV 11-infected raft cultures. The E1[symbol: see text]E4 mRNA is produced in abundance in HPV 11-infected human foreskin implants grown in athymic mice. In contrast, the L1 mRNA is present at low levels and appears late in the course of infection. To characterize the relationship of these proteins, polyclonal rabbit antisera were produced against bacterially expressed HPV 11 trpE/E1[symbol: see text]E4 and trpE/L1 fusion proteins and tested in an immunohistochemical assay of paraffin-embedded sections of HPV 11-infected human foreskin tissue fixed with 10% buffered formalin phosphate or zinc formalin. In sections fixed with either fixative, the anti-L1 serum stained nuclei of cells in the upper spinous and granular layers. In contrast, the anti-E1[symbol: see text]E4 serum stained the cell membrane and, to a lesser degree, the cytoplasm of cells in the upper spinous and granular layers of tissue fixed with zinc formalin, but not 10% buffered formalin phosphate. In sections treated with both the E1[symbol: see text]E4 and L1 antisera, cell membrane staining occurred in the same cells that exhibited nuclear staining. The HPV 11 E1[symbol: see text]E4 protein appears to be a cell membrane-associated protein. Expression of the HPV 11 E1[symbol: see text]E4 and L1 proteins may be influenced by similar factors in differentiating cells.

Animals↗
PubMed1994

A three month double-blind study of doxazosin as treatment for benign prostatic bladder outlet obstruction.

OBJECTIVE: To evaluate the efficacy and tolerability of doxazosin in the treatment of bladder outflow obstruction resulting from benign prostatic hyperplasia (BPH). PATIENTS AND METHODS: One-hundred and thirty-five patients with symptomatic urodynamically confirmed obstructive BPH were treated for 12 weeks with either doxazosin (67 patients) or placebo (68 patients) after an initial 2 week baseline evaluation. The main outcome measures were urodynamic and symptomatic evaluation for efficacy. Blood pressure and adverse events were monitored. RESULTS: Data were obtained in 122 patients (60 doxazosin, 62 placebo). Doxazosin produced increases in both mean and maximum urinary flow rates of 1.01 ml/s and 3.2 ml/s respectively, compared with 0.21 ml/s and 2.2 ml/s on placebo. The increase in mean flow rate was statistically significant (P = 0.04), while that for maximum flow rate approached significance (P = 0.09). The maximum subtracted voiding pressure was substantially reduced (P = 0.007) and 19 of 53 (36%) patients had an increase in maximum flow rate of 50% or more compared with 9 of 54 (17%) on placebo (P = 0.024). Twelve weeks' therapy with doxazosin resulted in significant improvements (compared with placebo) in: hesitancy (doxazosin 26 of 46, placebo 11 of 43; P = 0.003), impaired urinary stream (doxazosin 31 of 55, placebo 16 of 48; P = 0.019) nocturia (doxazosin 22 of 56, placebo 10 of 54; P = 0.017) and urgency (doxazosin 27 of 45, placebo 16 of 42; P = 0.041). Frequency improved with doxazosin therapy (doxazosin 26 of 59, placebo 15 of 55; P = 0.062). Adverse events, most frequently dizziness and headache, were usually mild and transient and led to a discontinuation of doxazosin therapy in one patient. No clinically significant changes in sexual function or blood pressure were seen. CONCLUSION: Doxazosin was well-tolerated and produced both urodynamic and symptomatic improvement in men with BPH, thereby providing a satisfactory alternative to existing drugs with the additional benefit of once daily dosage.

Aged↗
PubMed1993

Fascin, an echinoid actin-bundling protein, is a homolog of the Drosophila singed gene product.

A cDNA for fascin, an actin-bundling protein in echinoderms, has been cloned, sequenced, and expressed. The predicted mass of the protein is approximately 55 kDa, similar to that observed for fascin purified from sea urchin eggs. Bacterially expressed fascin reacts with antibodies prepared against sea urchin egg fascin. Fascin has a strong sequence similarity to the singed gene (sn) product in Drosophila and has similarities with a 55-kDa human actin-bundling protein. No extensive similarities were found with other known actin-binding/bundling proteins, indicating that this is a separate gene family.

Amino Acid Sequence↗