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Biomedical subjects

M Gibson

Publications and source records attributed to M Gibson.

17 recordsLinked to original sources
PubMed2002

Apollo: a sequence annotation editor.

The well-established inaccuracy of purely computational methods for annotating genome sequences necessitates an interactive tool to allow biological experts to refine these approximations by viewing and independently evaluating the data supporting each annotation. Apollo was developed to meet this need, enabling curators to inspect genome annotations closely and edit them. FlyBase biologists successfully used Apollo to annotate the Drosophila melanogaster genome and it is increasingly being used as a starting point for the development of customized annotation editing tools for other genome projects.

Animals↗
PubMed1992

Somatostatin inhibits vasopressin-stimulated phosphoinositide hydrolysis and influx of extracellular calcium in clonal hamster beta (HIT) cells.

Vasopressin (VP) stimulates insulin secretion and inositol phosphate (InsP) production in clonal hamster beta cells (HIT) via a cyclic AMP-independent V1-receptor-mediated signal-transduction pathway. Somatostatin (SRIF) inhibited VP-stimulated insulin secretion, and the effects of SRIF were abolished by pretreatment with pertussis toxin. The Ca(2+)-channel blockers verapamil and nifedipine also inhibited VP-stimulated insulin secretion during 20 min incubations, but verapamil was ineffective at 2 min, and the effects of SRIF and nifedipine together were not addictive. SRIF failed to inhibit further the attenuated insulin response to VP in Ca(2+)-free medium. VP-stimulated InsP production was also inhibited by SRIF in a pertussis-toxin-sensitive manner. Whereas VP-stimulated insulin secretion was almost completely inhibited by SRIF at an equimolar concentration, VP-stimulated InsP production was much less sensitive to inhibition by SRIF, even at a 100-fold excess concentration. VP increased cytosolic Ca2+ in HIT cells loaded with fura 2, the fluorescent Ca2+ indicator. The increase was biphasic, with an initial rapid spike increase followed by a prolonged second phase. Both SRIF, at a concentration which inhibited VP-stimulated insulin secretion but not InsP production, and verapamil failed to inhibit the rapid spike increase in intracellular Ca2+, but did inhibit the second phase. We conclude that VP induces biphasic changes in cytosolic Ca2+, secondary to mobilization of intracellular Ca2+ and influx of extracellular Ca2+. SRIF inhibits insulin secretion by interrupting influx of extracellular Ca2+, likely by inhibiting Gi-subunit activity. Inhibition of VP-stimulated phosphoinositide hydrolysis, which is also pertussis-toxin-sensitive, may represent an additional mechanism of action of SRIF.

Animals↗
PubMed1992

A method for the independent assessment of the accuracy of hematology whole-blood calibrators.

An independent assessment of the accuracy with which a large manufacturer assigned values to hematologic calibrators was performed. Data were collected from 1,767 hospitals and clinics distributed over North America. Statistical analysis of the mean corpuscular volume, mean corpuscular hemoglobin, and mean corpuscular hemoglobin concentration of these patient data confirmed the accuracy of the values for hemoglobin, erythrocyte count, hematocrit, and erythrocyte indices for the calibrators manufactured and released during a 9-month period. This approach proved both workable and effective in detecting inaccuracies of less than 1%. Few technologist-users have the time or the equipment to verify independently the accuracy of hematologic calibrators. The manufacturers should perform ongoing, independent assessments of the accuracy of their products. The statistical analysis of patient data provides manufacturers with a suitable method.

Calibration↗
PubMed1992

A preliminary evaluation of the use of a redox agent in the treatment of chronic periodontitis.

A small-scale clinical trial was carried out to evaluate the effect of a redox agent, methylene blue, on microbiological and clinical indices of chronic periodontitis. Methylene blue was applied subgingivally on a daily basis for 7 d to 25 test sites in 7 patients and the sites evaluated clinically and microbiologically for up to 14 d: 25 control sites in the same patients received sterile water. The test sites showed statistically significant differences from the control sites in terms of changes in a number of clinical and microbiological indices. In the test sites the proportions of anaerobes, Gram-negative anaerobes, spirochetes and motile bacteria decreased, as did the crevicular fluid flow, while the proportions of facultative anaerobes and cocci increased. These changes are indicative of a shift towards periodontal health. No significant differences were observed between the test and control sites in terms of bleeding on probing or pocket depth. The encouraging results of this preliminary study suggest that the use of redox agents in the treatment of chronic periodontitis warrants further investigation.

Adult↗
PubMed1992

Radiography for back pain presenting to accident and emergency departments.

In order to determine the relevance of radiographs of the lumbar spine in an A&E department 225 consecutive patients presenting in a 6-month period with acute back pain were studied. An analysis of the number of radiographs performed and their association with particular factors in the history and examination of the patient was performed. A total of 108 patients had radiographs (48%), with a total of seven fractures (6% of radiographs). All the patients with fractures had a history of direct trauma. Radiographs had no bearing on the decision to admit the patient. The indications for radiography of the lumbar spine in the A&E department are discussed.

Adolescent↗
PubMed1992

Interleukin 4 induces the maturation of idiotype-specific regulatory B cell populations.

CD5+ B cells have been shown to be disproportionately associated with autoimmune diseases and transformation. In many cases, their apparent ability to bypass self-tolerance is manifested by the production of autoantibodies. These observations, plus the hypothesis that CD5+ B cells represent a distinct B cell lineage, encourage studies into the conditions and factors that influence their development. In the present study, we employed a well-established assay for murine CD5+ B cell function, i.e., their ability to augment the responses of IgHb-linked idiotypic determinants on anti-(4-hydroxy-3-nitrophenyl) acetyl (NP) antibody (Nbb) idiotype-bearing CD5- B cells to a T-independent antigen, together with multiple methods of cell surface phenotyping, to evaluate the potential for interleukin (IL) 4 to effect maturation of CD5+ B cells, CD5+, IgM+, Thy-1-, and NPb idiotype-specific cells panned on antibody-coated petri dishes or sorted by flow cytometry from spleen were capable of augmenting NPb idiotypic responses of NP-KLH-primed responder cells to NP-Ficoll. Splenic B cell populations depleted of CD5+ B cells failed to affect idiotype expression even after 2 days in culture, a time when a small percentage of CD5+ B cells appeared to be regenerated. However, idiotype-specific regulatory activity could be restored in CD5- splenic B cell populations by culture for 2 days with recombinant IL-4. Cells responsible for idiotype-specific regulatory activity after culture with IL-4 were in fact CD5+, IgM+, and Thy-1.2- B cells, demonstrating that IL-4 can drive the functional, if not the phenotypic, maturation of splenic B cells associated with the CD5+ B cell lineage. The results illustrate one possible mechanism by which T cells could control the maturation of cells belonging to the CD5+ B cell lineage.

Animals↗
PubMed1992

Investigation and treatment of poor drains of dialysate fluid associated with anterior abdominal wall leaks in patients on chronic ambulatory peritoneal dialysis.

Reduced dialysate fluid volume and genital and abdominal-wall oedema occurring many months after initiation of continuous ambulatory peritoneal dialysis (CAPD) has been investigated in 20 patients using computed tomographic peritoneography. Leaks into the anterior abdominal wall at the site of insertion of the Tenckhoff catheter have been demonstrated in a series of 14 patients. Nocturnal peritoneal dialysis alone led to resolution of leaks in four of the nine patients who underwent this mode of treatment. Four of the failures plus a further four patients successfully underwent either resuture of the peritoneum or replacement of the catheter. A policy for management of proven anterior abdominal-wall leaks in CAPD patients is described, consisting of nocturnal peritoneal dialysis for 2 weeks followed by surgical intervention if the former is unsuccessful.

Abdominal Muscles↗
PubMed1992

Fetal ascitic fluid: a new source of lymphocytes for rapid chromosomal analysis.

BACKGROUND: The cells found in ascites can be processed like amniotic fluid for fetal karyotyping. We have characterized these cells and used them for a rapid cytogenetic result. CASES: Three patients presented with massive fetal ascites detected by sonography. Samples of ascitic fluid were obtained at fetal paracentesis. Cells from the fluid were cultured using standard methods for fetal blood, and were compared with fetal blood lymphocytes and amniocytes. The length of time in culture, chromosome morphology, and mitotic index of ascitic fluid cells were equivalent to those of fetal blood. In the third case, we performed immunophenotyping on the ascitic fluid cells. CONCLUSION: Ascitic fluid contains lymphocytes that permit rapid chromosomal analysis within 96 hours.

Adult↗
PubMed1992

CA-125 levels in human uterine fluid.

OBJECTIVE: To measure uterine fluid CA-125 concentration and to determine if any menstrual cycle phase dependent changes exist in its level. Serum levels are measured for comparison. DESIGN: CA-125 levels in uterine fluid were measured during the follicular and luteal phases of the menstrual cycle. In a sequential study, paired uterine fluid and serum samples were obtained once in both midfollicular and midluteal phases of the same menstrual cycle. RESULTS: CA-125 in uterine fluid during the follicular phase (n = 14) ranged from 16.4 x 10(3) to 616.5 x 10(3) U/mL, and from 6.2 x 10(3) to 567.3 x 10(3) U/mL in the luteal phase (n = 11). In the paired sequential uterine fluid and serum samples, (1) the means (+/- SEM) CA-125 in uterine fluid were 81.5 x 10(3) +/- 37.9 x 10(3) U/mL and 91.4 x 10(3) +/- 56.8 x 10(3) U/mL in the midfollicular and midluteal phases, respectively (P = 0.75); (2) the CA-125 levels in serum increased in the midluteal phase (P less than 0.05); and (3) compared with serum, uterine fluid levels were greater with a wider range. CONCLUSIONS: When compared with serum CA-125, uterine fluid contains high concentrations varying over a wide range without fluctuation between the follicular and luteal phases of the menstrual cycle.

Adult↗
PubMed1990

Characterization of a B cell helper factor(s) derived from CD5+ B cell hybridomas.

Work from our laboratory suggests that the selective advantage of frequently autoreactive CD5+ B cells is to provide activation signals to CD5- antigen-specific B cells. This hypothesis is supported by the observation that supernatants from CD5+ B cell hybridomas replace CD5+ B cell populations in helping idiotypic B cell subsets respond to antigen plus anti-idiotype antibody. The present study was designed to initiate the characterization of CD5+ B hybridoma-derived helper factor(s) (BHF) and to compare BHF to previously described cytokines. Elution of BHF from a lectin column enabled significant enrichment of the apparently glycosylated helper factor(s) from serum-free hybridoma supernatant. Gel filtration of this enriched activity revealed two significant peaks of helper activity, one at approximately 19-22 kDa and a second at 29-32 kDa. BHF activity in each fraction was sensitive to protease treatment. To determine if some previously described cytokines of approximately the same molecular weights were responsible for BHF activity, BHF fractions were tested for cytokine activity in respective bioassays. At least 2000 units of BHF did not contain detectable levels of IL-1, IL-2, IL-3, IL-4, IL-6, GM-CSF, G-CSF, or IFN-gamma activity. Furthermore, three hybridomas which produced BHF did not transcribe detectable levels of mRNAs specific for IL-1, IL-2, IL-3, IL-4, IL-5, IL-6, GM-CSF, or IFN-gamma. The results suggest that CD5+ B cell hybridomas produce a lymphokine(s) distinct from cytokines commonly associated with B cell activation. The potential roles of this lymphokine in immunity and disease are discussed.

Animals↗
PubMed1990

A CD5+ B cell hybridoma derived factor(s), which induces maturation of CD5+, idiotype-specific B-cell populations.

A number of investigators have demonstrated the association of CD5+ (Ly-1/Leu-1) B cells with autoimmunity, excessive B-cell proliferation, and transformation. Previous work from our laboratory, among others, suggests that the selective advantage of this frequently autoreactive B-cell subset is to provide activation signals to conventional antigen-specific B cells. If one current hypothesis is correct then the overrepresentation of CD5+ B cells in some diseases and their novel capacity to act as helper cells reflect the activities of a separate B-cell lineage. Because of these observations it is of particular interest to evaluate the factors which contribute to the maturation of the CD5+ B-cell subset. The possibility that CD5+ B cells produce a factor or factors capable of influencing their own development was the focus of the present investigation. Rather than attempt to obtain soluble factors from heterogeneous CD5+ B-cell populations which could be contaminated with cytokine secreting monocytes or which could require as yet undefined activation signals in order to secrete putative factors, we chose to evaluate the production of CD5+ B-cell inducing factor(s) by monoclonal CD5+ B-cell hybridomas. Added incentive to this approach was provided by the observation that these hybridomas elaborate a factor(s) which, together with (NPb) idiotype-specific antibody produced by the hybridoma, substitutes for CD5+ B-cell populations in activating antigen-specific (NPb idiotypic) B cells in vitro. Furthermore, because of the low percentage of CD5+ B cells in the spleen and their relatively low level of CD5 antigen expression, we employed a sensitive functional assay rather than surface antigen expression alone to detect small numbers of mature CD5+ B helper cells. With this previously described system it was possible to observe the induction of functional CD5+ B cells following a 40 h culture of apparently CD5- B-cell populations with a 19-22 kd factor or factors derived from a CD5+ B hybridoma. Data presented here and elsewhere suggest that this CD5+ B-cell inducing activity is not mediated by IL-1, IL-2, IL-3, IL-4, IL-5, IL-6, IFN-gamma, GM-CSF, or TNF. The role that such a B cell derived, B-cell directed factor may play in immunity and disease is discussed.

Animals↗
PubMed1979

Testicular testosterone concentration following testicular vein ligation.

UNLABELLED: A rat model to study the local effects of testicular vein ligation is described. One hour after unilateral testicular vein ligation, the testicular concentration of testosterone was significantly greater (P less than 0.01) on the side that was ligated than in the contralateral testis (177.1 +/- 19.7 [SEM] ng/gm of tissue as compared with 108.8 +/- 11.8 ng/gm of tissue, respectively). This effect was not seen 1 week after the testicular vein ligation. The testosterone concentration in the ligated testis was also higher than that in sham-operated animals. These differences in testicular testosterone concentration were not associated with changes in peripheral serum testosterone levels. CONCLUSION: ligation of the testicular vein causes an acute rise in the testicular concentration of testosterone and may thus mediate changes in testicular function.

Animals↗
PubMed1978

Haemophilus influenzae amnionitis associated with prematurity and premature membrane rupture.

Prematurity and premature rupture of the membranes present major obstetric problems. When associated with amnionitis, the result may be disastrous. A case of Haemophilus influenzae aminionitis in association with premature rupture of the membranes is presented. The rarity of this organism as a causative agent in amnionitis and its possible causative role in premature membrane rupture are considered in review of the scant relevant literature.

Adult↗
PubMed1977

Use of discriminant analysis in relating maternal anti-D levels to the severity of haemolytic disease of the Newborn.

The automated assay of maternal anit-D levels has been compared with manual methods and correlated with the severity of haemolytic disease of the newborn using discriminant analysis. The automated assay of anti-D proved to be marginally better than manual techniques in predicting the need for amniocentesis. The level at which amniocentesis should be considered has been calculated to be 4IU/ml of maternal serum.

Animals↗