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Biomedical subjects

J Bryan

Publications and source records attributed to J Bryan.

At least 127 records · Page 7Linked to original sources
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↗
PubMed1993

Sulfonylurea receptors and ATP-sensitive K+ channels in clonal pancreatic alpha cells. Evidence for two high affinity sulfonylurea receptors.

We tested for the presence of sulfonylurea receptors in pancreatic alpha cells. Two high affinity sulfonylurea receptors were identified in clonal pancreatic alpha cells (alpha TC-6): a 140-kDa species observed previously in clonal pancreatic beta cells (HIT) and a second 150-kDa protein. The dissociation constant (Kd) for both receptors is approximately 3.5 nM for an iodinated glyburide analog, 5-iodo-2-hydroxyglyburide. The estimated number of receptors (Bmax) increases approximately 2-fold, from 3.1 to 6.8 pmol/mg of membrane protein as the pH of the binding buffer is reduced from 7.5 to 6. Consistent with the notion that high affinity sulfonylurea receptors are integral components of the ATP-sensitive K+ channel, we demonstrated the presence of ATP-sensitive K+ channels in inside-out patches of alpha TC-6 cells. Whole cell K+ currents that activated with time showed inward rectification at positive potentials (above 0 mV) and were almost completely suppressed by 5 nM glyburide. Likewise, glyburide blocked 86Rb+ efflux from ATP-depleted alpha TC-6 cells, an effect that was reversed by 400 microM diazoxide. The presence of sulfonylurea receptors provides a mechanism by which sulfonylureas can directly modulate alpha cell function. The properties of the 150-kDa receptor and the role of ATP-sensitive K+ channels in alpha cells remain to be elucidated, but as in beta cells, ATP-sensitive K+ channels may be involved in metabolic regulation of alpha cells by glucose.

ATP-Binding Cassette Transporters↗
PubMed1993

Clinical evaluation of the peritoneal equilibration test: a population-based study.

A total of 143 Peritoneal Equilibration Tests (PETs) were performed in 104 CAPD patients over a period of 18 months. A normal range (95% confidence limits) was constructed from 100 tests (68 consecutive new patients, 32 routine tests on problem-free patients) using a 2-dimensional plot of solute transfer (D/Pcreat) and ultrafiltration volume. These two parameters correlated inversely (r = -0.59, P < 0.0001) allowing calculation of a regression line. In the short term (< 3 months) D/Pcreat was stable across a wide range of values (0.45-0.98) with good correlation between tests indicating reproducibility (r = 0.94, P < 0.001). Repeated tests beyond 3 months were variable, explaining changes in the clinical picture, and in the majority of cases shifts in D/Pcreat and ultrafiltration parallelled the regression line for the whole population. Six of seven (85%) of patients with mechanical problems and 14 of 15 (93%) with poor ultrafiltration had at least one abnormal test, and these two problems could be distinguished in 90% of cases by 2-dimensional plotting. In five with ultrafiltration failure, dialysate volumes were less than predicted by solute clearance, and these patients failed continuous cycling peritoneal dialysis (CCPD). In contrast, a good response to CCPD was predicted correctly in five patients with high solute clearance. In nine patients with plasma creatinine > 1250 mumol/l the PET was normal. The PET is a useful adjunct to understanding and prescribing peritoneal dialysis, particularly when repeated tests are compared to a well-defined normal population.

Adolescent↗
PubMed1993

Long-term urodynamic effects of finasteride in benign prostatic hyperplasia: a pilot study.

A group of 69 men with bladder outflow obstruction due to benign prostatic hyperplasia (BPH) were treated in a double-blind placebo-controlled study with finasteride (Proscar), a 5 alpha-reductase inhibitor, 5 mg or 10 mg/day, or an identical placebo for 3 months; subsequently, 20 patients received finasteride 5 mg/day in an open extension study. Ten of these patients have now completed 3 years of therapy and have been reevaluated with pressure/flow urodynamics. In finasteride-treated patients dihydrotestosterone (DHT) declined by over 60%, remaining unchanged with placebo. Symptom scores fell in both groups of patients, maximum flow rate values decreased on placebo but improved by a mean of 1.5 ml/s in the 10-mg group and 3.3 ml/s in the 5-mg group. After 1 year of therapy, the reduction in symptom score was well maintained and the flow rate had increased by a mean of 2.7 ml/s; the mean prostate volume was reduced by 14% and prostate-specific antigen (PSA) had declined by 28%. In the 10 patients treated for 3 years who consented to further urodynamic study, the maximum urinary flow rate had improved from a mean baseline value of 8.7 ml/s to a mean of 13.8 ml/s, while maximum subtracted voiding pressure had decreased from a mean baseline value of 72 cm H2O to an unobstructed mean value of 44 cm H2O. Side effects were minimal and reversible on stopping the medication.(ABSTRACT TRUNCATED AT 250 WORDS)

5-alpha Reductase Inhibitors↗
PubMed1992

Characterization of the murine thymidine kinase-encoding gene and analysis of transcription start point heterogeneity.

We have determined the molecular organization and transcription start points (tsp) for the murine gene (TK) encoding thymidine kinase. The exon/intron structure and sequences present at the splice junctions of the mammalian TK genes have been highly conserved; however, the promoter sequences of these genes have diverged widely. Both the human and Chinese hamster TK promoter regions contain CCAAT and TATA consensus motifs, whereas the mouse promoter has neither element. This difference between species is reflected in that, unlike the hamster and human TK genes, transcription initiates from numerous specific tsp within a 100-bp region in the mouse TK gene. The complex pattern of tsp seen in the endogenous gene was not maintained in transfected cell lines containing TK promoter::beta-globin (HBB) fusions. Transcription from the murine TK:HBB fusion genes initiated from a small number of tsp that were clustered downstream from the ATG in hybrids containing TK coding sequences, and in the HBB 5' UTR in hybrids that did not. Few or no specific tsp were detected from the upstream sites used in the endogenous mouse TK gene.

Amino Acid Sequence↗