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Biomedical subjects

A Price

Publications and source records attributed to A Price.

At least 55 records · Page 3Linked to original sources
PubMed2000

A Ypt/Rab effector complex containing the Sec1 homolog Vps33p is required for homotypic vacuole fusion.

Yeast vacuoles undergo priming, docking, and homotypic fusion, although little has been known of the connections between these reactions. Vacuole-associated Vam2p and Vam6p (Vam2/6p) are components of a 65S complex containing SNARE proteins. Upon priming by Sec18p/NSF and ATP, Vam2/6p is released as a 38S subcomplex that binds Ypt7p to initiate docking. We now report that the 38S complex consists of both Vam2/6p and the class C Vps proteins [Reider, S. E. and Emr, S. D. (1997) Mol. Biol. Cell 8, 2307-2327]. This complex includes Vps33p, a member of the Sec1 family of proteins that bind t-SNAREs. We term this 38S complex HOPS, for homotypic fusion and vacuole protein sorting. This unexpected finding explains how Vam2/6p associates with SNAREs and provides a mechanistic link of the class C Vps proteins to Ypt/Rab action. HOPS initially associates with vacuole SNAREs in "cis" and, after release by priming, hops to Ypt7p, activating this Ypt/Rab switch to initiate docking.

Adaptor Proteins, Vesicular Transport↗
PubMed2000

A new role for a SNARE protein as a regulator of the Ypt7/Rab-dependent stage of docking.

The homotypic fusion of yeast vacuoles occurs in an ordered cascade of priming, docking, and fusion. The linkage between these steps has so far remained unclear. We now report that Vam7p (the vacuolar SNAP-23/25 homolog) signals from the cis-SNARE complex to Ypt7p (the vacuolar Rab/Ypt) to initiate the docking process. After Vam7p has been released from the cis-SNARE complex by Sec18p-mediated priming, it is still required for Ypt7p-dependent docking and it needs Ypt7p to remain on the vacuole. Thus, after priming, Vam7p is released from the vacuole altogether if Ypt7p has been extracted by Gdi1p or inactivated by antibody but is not released if docking is blocked simply by vacuole dilution; it is therefore Ypt7p function, and not docking per se, that retains Vam7p. In accord with this finding, cells deleted for the gene encoding Ypt7 have normal amounts of Vam7p but have little Vam7p on their isolated vacuoles. Interaction of Vam7p and Ypt7p is further indicated by two-hybrid analysis [Uetz, P., Giot, L., Cagney, G., Mansfield, T. A., Judson, R. S., Knight, J. R., Lockshon, D., Narayan, V., Srinivasan, M., Pochart, P., et al. (2000) Nature (London) 403, 623-627] and by the effect of Vam7p on the association of the Rab/Ypt-effector HOPS complex (homotypic fusion and vacuole protein sorting; Vam2p and Vam6p plus four vacuole protein sorting class C proteins) with Ypt7p. Vam7p provides a functional link between the priming step, which releases it from the cis-SNARE complex, and docking.

Membrane Proteins↗
PubMed2000

Drosophila dumbfounded: a myoblast attractant essential for fusion.

Aggregation and fusion of myoblasts to form myotubes is essential for myogenesis in many organisms. In Drosophila the formation of syncytial myotubes is seeded by founder myoblasts. Founders fuse with clusters of fusion-competent myoblasts. Here we identify the gene dumbfounded (duf) and show that it is required for myoblast aggregation and fusion. duf encodes a member of the immunoglobulin superfamily of proteins that is an attractant for fusion-competent myoblasts. It is expressed by founder cells and serves to attract clusters of myoblasts from which myotubes form by fusion.

Amino Acid Sequence↗
PubMed2000

Proteins needed for vesicle budding from the Golgi complex are also required for the docking step of homotypic vacuole fusion.

Vam2p/Vps41p is known to be required for transport vesicles with vacuolar cargo to bud from the Golgi. Like other VAM-encoded proteins, which are needed for homotypic vacuole fusion, we now report that Vam2p and its associated protein Vam6p/Vps39p are needed on each vacuole partner for homotypic fusion. In vitro vacuole fusion occurs in successive steps of priming, docking, and membrane fusion. While priming does not require Vam2p or Vam6p, the functions of these two proteins cannot be fulfilled until priming has occurred, and each is required for the docking reaction which culminates in trans-SNARE pairing. Consistent with their dual function in Golgi vesicle budding and homotypic fusion of vacuoles, approximately half of the Vam2p and Vam6p of the cell are recovered from cell lysates with purified vacuoles.

Adaptor Proteins, Vesicular Transport↗
PubMed2000

The docking stage of yeast vacuole fusion requires the transfer of proteins from a cis-SNARE complex to a Rab/Ypt protein.

The homotypic fusion of yeast vacuoles requires Sec18p (NSF)-driven priming to allow vacuole docking, but the mechanism that links priming and docking is unknown. We find that a large multisubunit protein called the Vam2/6p complex is bound to cis-paired SNAP receptors (SNAREs) on isolated vacuoles. This association of the Vam2/6p complex with the cis-SNARE complex is disrupted during priming. The Vam2/6p complex then binds to Ypt7p, a guanosine triphosphate binding protein of the Rab family, to initiate productive contact between vacuoles. Thus, cis-SNARE complexes can contain Rab/Ypt effectors, and these effectors can be mobilized by NSF/Sec18p-driven priming, allowing their direct association with a Rab/Ypt protein to activate docking.

Adaptor Proteins, Vesicular Transport↗
PubMed2000

Assessment of ileal pouch inflammation by single-stool calprotectin assay.

PURPOSE: Assessment of inflammation within the ileal pouch to establish a diagnosis of "pouchitis" requires both pouch endoscopy and biopsy because there can be a poor correlation between macroscopic and histologic assessments of inflammation. A simplified diagnostic test would be of clinical advantage. Calprotectin is a stable myelomonocytic protein, measurable in feces. It quantitatively relates to inflammation within the gastrointestinal tract. This study was designed to compare single and 24-hour stool measurements of calprotectin in patients with and without evidence of ileal pouch inflammation with endoscopic, histologic, and immunohistochemical indices. METHODS: Twenty-four-hour stool collections were made in ileal pouch patients, 9 with and 15 without (7 with ulcerative colitis and 8 with familial polyposis coli) evidence of pouch inflammation. First-morning stool concentration and total 24-hour calprotectin were quantified by use of a single step enzyme-linked immunosorbent assay. Biopsies from the reservoir were taken for conventional histology and scoring of intraepithelial neutrophil infiltrate. Cells positive for CD3, CD45RO, CD14, and CD15 within the lamina propria were quantified by use of immunohistochemistry. RESULTS: The mean first-morning stool calprotectin concentration correlated with the 24-hour level (r = 0.91; P = <0.0001). The median single-stool calprotectin concentrations were 39 mg/l, 4 mg/l, and 8.5 mg/l (normal range, 0.2-10 mg/l) in patients with inflamed, noninflamed ulcerative colitis, and familial adenomatous polyposis, respectively. All nine patients with endoscopic and histologic evidence of pouch inflammation had raised stool calprotectin. Two of 15 patients without evidence of pouch inflammation had abnormal stool calprotectin. Single-stool calprotectin concentration correlated with the percentage of mature granulocytes (CD15; r = 0.46; P = 0.04) and activated macrophages (CD14; r = 0.65; P = 0.006), but not memory T cells (CD45RO; r = -0.05; P = 0.4) within the lamina propria. CONCLUSION: Single first-morning stool calprotectin levels provide a quantitative measure of pouch inflammation, which may be helpful in the diagnosis and assessment of pouchitis.

Biomarkers↗
PubMed2000

Improving shoulder and elbow function in children with Erb's palsy.

Many children who sustain birth injuries to the brachial plexus suffer significant functional limitations due to various sequelae affecting the shoulder and elbow or forearm. The maintenance of full passive mobility during the period of neurological recovery is essential for normal joint development. Early surgical correction of shoulder contractures and subluxations reduces permanent deformity. Reconstruction of forearm rotation contractures significantly improves the appearance and use of the extremity for many basic activities. Each child must be carefully evaluated, therapy maximized, and the surgical approach individualized to obtain the best result.

Brachial Plexus Neuropathies↗
PubMed2000

Fibrosing colonopathy in an adult owing to over use of pancreatic enzyme supplements.

A woman, then in her late 20s, underwent a cholecystectomy in 1962 for gallstone disease and subsequent common bile duct stones were managed endoscopically. However, because of unrelenting pain, a pylorus preserving pancreaticoduodenectomy was done in 1990 and in the following years the patient took large amounts of pancreatic enzyme supplements. She developed large bowel obstruction in 1997 and a right hemicolectomy was undertaken. Histology confirmed fibrosing colonopathy of the ascending colon and caecum. Her pancreatic enzyme dose was reduced and her subsequent course has been uncomplicated.

Adult↗
PubMed2000

Glucagon-like peptide-2 increases sucrase-isomaltase but not caudal-related homeobox protein-2 gene expression.

To determine the effect of glucagon-like peptide-2 (GLP-2) on sucrase-isomaltase and caudal-related homeobox protein-2 (Cdx-2) gene expression, male Wistar rats were divided into total parenteral nutrition (TPN)-fed and GLP-2-treated, TPN-fed groups. TPN was given via a jugular line, inserted under anesthesia, for 7 days. The treatment group received 40 microg/day of GLP-2 intravenously with the TPN diet. The small intestine and colon were weighed and measured. Tissue was obtained from the jejunum, terminal ileum, and midcolon. RNA analysis, morphometry, and microdissection were performed. The weight of the small intestine of GLP-2-treated rats was greater than that of TPN-fed rats (P < 0.001). GLP-2 increased the mean metaphase arrests/crypt in both the jejunum and ileum (P < 0.001). Ileal expression of sucrase-isomaltase was increased by 1. 6-fold (P < 0.05). Jejunal expression was increased by a similar amount, although not significantly (P = 0.08). There was no change in Cdx-2 gene expression. Thus GLP-2 can maintain small intestinal morphology and function, but effects on gene expression are not mediated by gross changes in the level of the mRNA for the homeobox protein Cdx-2.

Animals↗
PubMed2000

A model for a multicentre approach to the derivation of reference intervals for thyroid hormones and testosterone for laboratories using identical analysers.

Ideally, every laboratory should derive their own reference intervals for all analytes, but this is difficult in practice. A survey, by questionnaire, of UK laboratories using the Chiron Diagnostics ACS:180 (Chiron Diagnostics Limited, Halstead, Essex, UK), for thyroid function tests, showed that 10% of laboratories derived their own reference intervals, 60% quoted values "adapted" from intervals for previous methods, whilst the remaining 40% quoted (often incorrectly) reference intervals supplied by the manufacturer. In addition only 13% of respondent laboratories derived their own reference intervals for testosterone. As a result of this survey, a study was devised to enable the users of the Chiron Diagnostics ACS:180 immunoassay system to develop and use within-method, between-laboratory reference intervals for thyroid hormones and testosterone. Laboratory collaboration provided the recommended minimum number of data points by establishing a reference sample group. This sample group was used for the calculation of appropriate reference intervals for each hormone according to the guidelines published by the IFCC. We propose this approach as a model for laboratories using identical instrumentation to produce, through collaboration, within-method, between laboratory reference intervals.

Female↗
PubMed2000

Stability of cardiac troponins and CK-MB mass isoenzyme.

The stability of an analyte can have an important influence on its diagnostic performance and therefore should be documented before an analyte is introduced into routine practice. The stability of creatine kinase MB isoenzyme (CK-MB), troponin I and troponin T was studied by incubating samples at temperatures between 26 degrees C and 39 degrees C for periods up to 5400 min. Arrhenius plots were made which showed that all three proteins demonstrated a rapid decrease in stability between 15 degrees C and 20 degrees C. The activation energies for CK-MB, troponin I and troponin T were 7.7, 6.34 and 6.34 cal/mol, respectively.

Creatine Kinase↗
PubMed1999

Outcome of surgical treatment for forearm pronation deformities in children with obstetric brachial plexus injuries.

Seven children were operated on for pronation contractures of the forearm due to obstetric brachial plexus injuries. All underwent extensive preoperative evaluations to determine the extent of injury, secondary deformities, and capacity to perform a few basic tasks. Sequential video studies were used to document these findings. Operative procedures performed included various combinations of tendon/muscle lengthenings and/or transfers. Postoperative evaluations focused on function rather than gains in active range of motion and the patient/parental assessment of the benefit of the procedure by response to a questionnaire. All patients were followed for a minimum of I year following surgery. The average gain in active supination was 45 degrees. Each patient showed significant functional gains with a high degree of satisfaction.

Adolescent↗
PubMed1999

Investigation of female survival benefit in metastatic melanoma.

Epidemiological studies show female survival benefit in advanced metastatic melanoma. In investigating a possible mechanism for this female survival benefit, we have previously reported that the female steroid 17beta-oestradiol significantly reduces invasion of a human melanoma cell line (A375-SM cells) and ocular melanoma cells through fibronectin. Neither cell type was found to possess oestrogen receptor-alpha. The aim of the current study was to obtain further information on the extent to which progression of cutaneous melanoma might be sex steroid sensitive by (a) examining the relationship between circulating sex steroids, sex hormone binding globulin and disease progression; (b) examining the relationship between sex steroid structure and the ability of steroids to reduce invasion of a melanoma cell line in vitro; and (c) examining the effects of sex steroids on proliferation of these cells in vitro. We report a significant reduction in circulating oestrone with disease progression in male but not female patients. Examining steroids for their ability to inhibit invasion of A375-SM cells through fibronectin in vitro, oestrogenic compounds (17beta-oestradiol and oestrone) were found to inhibit invasion; in this respect, oestrone was approximately 50 times more potent than 17beta-oestradiol; steroids lacking the benzene ring structure did not inhibit invasion, indeed dehydroepiandrosterone (DHEA) which acts as a precursor to androgenic steroids significantly enhanced invasion. Proliferation of A375-SM cells was unaffected by 17beta-oestradiol, oestrone or dihydrotestosterone when cells were cultured on plastic; in contrast, all three steroids induced modest proliferation of cells when grown on fibronectin with dihydrotestosterone the most mitogenic of the three steroids. These data are consistent with sex steroids playing a role in melanoma progression.

Adolescent↗