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Biomedical subjects

C Vincent

Publications and source records attributed to C Vincent.

At least 37 records · Page 2Linked to original sources

Reasons for not reporting adverse incidents: an empirical study.

A previous study (Stanhope et al. 1998) established that staff in two obstetric units reported less than a quarter of designated incidents to the units' risk managers. A questionnaire was administered to 42 obstetricians and 156 midwives at the same two obstetric units, exploring the reasons for low rates of reporting. Questions concerned their knowledge of their unit's incident reporting system; whether they would report a series of 10 designated adverse obstetric incidents to the risk manager; and their views on 12 potential reasons for not reporting incidents. Most staff knew about the incident-reporting system in their unit, but almost 30% did not know how to find a list of reportable incidents. Views on the necessity of reporting the 10 designated obstetric incidents varied considerably. For example, 96% of staff stated they would always report a maternal death, whereas less than 40% would report a baby's unexpected admission to the Special Care Baby Unit. Midwives said they were more likely to report incidents than doctors, and junior staff were more likely to report than senior staff. The main reasons for not reporting were fears that junior staff would be blamed, high workload and the belief (even though the incident was designated as reportable) that the circumstances or outcome of a particular case did not warrant a report. Junior doctors felt less supported by their colleagues than senior doctors. Current systems of incident reporting, while providing some valuable information, do not provide a reliable index of the rate of adverse incidents. Recommended measures to increase reliability include clearer definitions of incidents, simplified methods of reporting, designated staff to record incidents and education, feedback and reassurance to staff about the nature and purpose of such systems.

Attitude of Health Personnel

Biochemical properties of the protein tyrosine kinase of the bacterium Acinetobacter johnsonii.

The biochemical properties of the autophosphorylating protein tyrosine kinase of Acinetobacter johnsonii were analyzed in vitro. The study shows that the optimal pH value for the phosphorylation reaction is approximately 7. The enzyme activity is stimulated by magnesium and, to a lesser extent, by manganese ions, whereas calcium ions have no effect. The phosphorylation process is rapid reaching a maximum in < 2 min, and the enzyme is modified at multiple sites. Interestingly, the bacterial enzyme is insensitive to a series of molecules known to affect the activity of eukaryotic protein tyrosine kinases: genistein, quercetin, tosyllysine chloromethyl ketone, and vanadate. We concluded that, even though the overall phosphorylation reaction catalyzed by the A. johnsonii enzyme is identical to that occurring in eukaryotes, this bacterial kinase exhibits a number of specific properties and therefore probably belongs to a separate group in the general family of protein tyrosine kinases.

Acinetobacter

Expression of the granule-bound starch synthase I (Waxy) gene from snapdragon is developmentally and circadian clock regulated

The granule-bound starch synthase I (GBSSI or waxy) enzyme catalyzes one of the enzymatic steps of starch synthesis. This enzyme is responsible for the synthesis of amylose and is also involved in building the final structure of amylopectin. Little is known about expression of GBSSI genes in tissues other than storage organs, such as seeds, endosperm, and tuber. We have isolated a gene encoding the GBSSI from snapdragon (Antirrhinum majus). This gene is present as a single copy in the snapdragon genome. There is a precise spatial and developmental regulation of its expression in flowers. GBSSI expression was observed in all floral whorls at early developmental stages, but it was restricted to carpel before anthesis. These results give new insights into the role of starch in later reproductive events such as seed filling. In leaves the mRNA level of GBSSI is regulated by an endogenous circadian clock, indicating that the transition from day to night may be accompanied by abolition of expression of starch synthesis genes. This mechanism does not operate in sink tissues such as roots when grown in the dark.

Journal Article

Cells of Escherichia coli contain a protein-tyrosine kinase, Wzc, and a phosphotyrosine-protein phosphatase, Wzb.

Two proteins of Escherichia coli, termed Wzc and Wzb, were analyzed for their capacity to participate in the reversible phosphorylation of proteins on tyrosine. First, Wzc was overproduced from its specific gene and purified to homogeneity by affinity chromatography. Upon incubation in the presence of radioactive ATP, it was found to effectively autophosphorylate. Two-dimensional analysis of its phosphoamino acid content revealed that it was modified exclusively at tyrosine. Second, Wzb was also overproduced from the corresponding gene and purified to homogeneity by affinity chromatography. It was shown to contain a phosphatase activity capable of cleaving the synthetic substrate p-nitrophenyl phosphate into p-nitrophenol and free phosphate. In addition, it was assayed on individual phosphorylated amino acids and appeared to dephosphorylate specifically phosphotyrosine, with no effect on phosphoserine or phosphothreonine. Such specificity for phosphotyrosine was confirmed by the observation that Wzb was able to dephosphorylate previously autophosphorylated Wzc. Together, these data demonstrate, for the first time, that E. coli cells contain both a protein-tyrosine kinase and a phosphotyrosine-protein phosphatase. They also provide evidence that this phosphatase can utilize the kinase as an endogenous substrate, which suggests the occurrence of a regulatory mechanism connected with reversible protein phosphorylation on tyrosine. From comparative analysis of amino acid sequences, Wzc was found to be similar to a number of proteins present in other bacterial species which are all involved in the synthesis or export of exopolysaccharides. Since these polymers are considered important virulence factors, we suggest that reversible protein phosphorylation on tyrosine may be part of the cascade of reactions that determine the pathogenicity of bacteria.

Adenosine Triphosphate

Anti-perinuclear factor compared with the so called "antikeratin" antibodies and antibodies to human epidermis filaggrin, in the diagnosis of arthritides.

OBJECTIVE: Antiperinuclear factor (APF), "antikeratin antibodies" ("AKA"), and antibodies to human epidermis filaggrin (AFA), are highly specific serological markers of rheumatoid arthritis (RA), which recognise epitopes on various isoforms of (pro)filaggrin. It was proposed that these antibodies are globally named antifilaggrin autoantibodies. Here the diagnostic value of the detection of each one is compared and the overlap between the three tests evaluated. METHODS: 492 serum samples were tested, including 279 RA serum samples, taken from patients in France and Belgium. APF and "AKA" titres were estimated by indirect immunofluorescence, and AFA titres by immunoblotting on filaggrin enriched human epidermis extracts. RESULTS: By a convenient choice of the positivity thresholds, the diagnostic sensitivity and specificity of the tests were shown to be similar (0.52 and 0.97, respectively). Although the antibody titres were strongly correlated, the associations APF-AFA or AFA-"AKA" permitted more than 52% or 55% of RA to be diagnosed, with a specificity of 0.99. CONCLUSION: APF, "AKA", and AFA detection have a similar diagnostic value. However, because the three tests do not totally overlap, associating APF with "AKA" or AFA with "AKA" can improve diagnostic sensitivity. None of the three antigens used bear all the epitopes recognised by antifilaggrin autoantibodies.

Adolescent

[Utilizing assistive devices: comparison of the American model with the reality of the needs of Quebec].

In order to understand better the nature of the success or failure of a recommendation of a technical aid, a group of occupational therapists from Québec became interested in an American assessment called "Assistive technology device predisposition assessment". This assessment is based on the "Matching Person and Technology" model proposed by Scherer in 1994. The model describes 40 factors that can influence the use (or the non use) of technical aids. A participative and qualitative study was conducted with the collaboration of 10 francophone occupational therapists, in order to verify if the tool can be adapted to Québec's context. Each had to reconstruct two case studies following the recommendation of a technical aid: the first showing a satisfactory use of a technical aid and the second, a non use of a technical aid. According to the participants' experience, the results show that the American assessment focuses well on the pertinent factors of technical aids, providing that seven other specific factors are added. This article describes four of the case studies that show the importance of considering different influential factors that could render other significant results. Finally, the study generated two proposals for further research in the area of technical aids.

Decision Making

Practices of recycling assistive technology in Quebec.

The aim of this study was to document professional factors to be considered in implementing a provincial policy of recycling assistive technology in Quebec. A qualitative study was conducted with 22 experts from various sectors: health professionals (including occupational therapists), industry and community. They were interviewed using a semi-structured questionnaire. Data collection also involved observing recycling practices and analyzing working documents. Implementation strategies were considered from the perspectives of health professionals, the commercial sector, users of assistive technology and government administrators. Factors that contribute to tension between occupational therapists and other players are discussed. It is recommended that occupational therapists take a united position on this issue such that their voices may have more weight in intersectoral collaborations.

Data Collection

Anterior cephalic neural crest is required for forebrain viability.

The prosencephalon, or embryonic forebrain, grows within a mesenchymal matrix of local paraxial mesoderm and of neural crest cells (NCC) derived from the posterior diencephalon and mesencephalon. Part of this NCC population forms the outer wall of capillaries within the prosencephalic leptomeninges and neuroepithelium itself. The surgical removal of NCC from the anterior head of chick embryos leads to massive cell death within the forebrain neuroepithelium during an interval that precedes its vascularization by at least 36 hours. During this critical period, a mesenchymal layer made up of intermingled mesodermal cells and NCC surround the neuroepithelium. This layer is not formed after anterior cephalic NCC ablation. The neuroepithelium then undergoes massive apoptosis. Cyclopia ensues after forebrain deterioration and absence of intervening frontonasal bud derivatives. The deleterious effect of ablation of the anterior NC cannot be interpreted as a deficit in vascularization because it takes place well before the time when blood vessels start to invade the neuroepithelium. Thus the mesenchymal layer itself exerts a trophic effect on the prosencephalic neuroepithelium. In an assay to rescue the operated phenotype, we found that the rhombencephalic but not the truncal NC can successfully replace the diencephalic and mesencephalic NC. Moreover, any region of the paraxial cephalic mesoderm can replace NCC in their dual function: in their early trophic effect and in providing pericytes to the forebrain meningeal blood vessels. The assumption of these roles by the cephalic neural crest may have been instrumental in the rostral expansion of the vertebrate forebrain over the course of evolution.

Animals

Rheumatoid factor and antikeratin antibody are independent from presence of DR4 or DR1 in rheumatoid arthritis.

BACKGROUND: Presence of HLA-DR4, rheumatoid factor, and antikeratin antibody may predict severe rheumatoid arthritis. OBJECTIVE: To investigate potential associations between HLA DR4, rheumatoid factor and antikeratin antibody in rheumatoid arthritis patients. PATIENTS AND METHODS: Retrospective review of 169 patients followed at the Rangueil Teaching Hospital rheumatology department for rheumatoid arthritis. RESULTS: No differences in prevalences of DR4 and DR1 were found between patients with and without rheumatoid factor or between patients with and without antikeratin antibody, suggesting that the production of rheumatoid factor and/or antikeratin antibody is not dependent on genetic factors. Substantial overlap was seen between rheumatoid factor and antikeratin antibody. All three parameters can be identified at first evaluation of a patient with joint disease. CONCLUSION: It would be of interest to evaluate the cumulative predictive value of DR4 or DR1, rheumatoid factor and antikeratin antibody at disease onset.

Arthritis, Rheumatoid

The growth of acoustic neuromas in volumetric radiologic assessment.

OBJECTIVE: The volumetric assessments of neuroma were applied for radiologic observation of tumor growth. The hypothesis that most of neuromas are stable or show only slight growth was tested. STUDY DESIGN: This was an observational study. SETTING: The study was performed in the university centers. PATIENTS: The study group included 27 patients with 15 unilateral tumors and 12 bilateral tumors. All patients had at least 2 magnetic resonance imaging (MRI) examinations, and the average interval between initial and control examinations was 11.4 months. MAIN OUTCOME MEASURE: Volume measurements were performed on T1- weighted MRI spin echo sequences after injection of gadolinium using special software. Growth of the tumors was estimated by comparison of the results of three measurements from the initial and control MRI examinations. RESULTS: The growth was confirmed in 17 of 27 tumors (63%). Growth was found in 10 of 12 neuromas of neurofibromatosis type 2 (83.7%). In 15 unilateral neuromas, growth was found in 7 (43%). Unilateral neuromas were observed for a shorter period of time (6.3 months) than bilateral tumors (14.7 months). The correlation between a neuroma volume gain and the follow-up period was statistically significant (p = 0.003, r = 0.544). CONCLUSIONS: The growth of tumors can be confirmed despite a short follow-up period.

Adolescent

Expression cloning of human corneodesmosin proves its identity with the product of the S gene and allows improved characterization of its processing during keratinocyte differentiation.

In human epidermis and other cornified squamous epithelia, corneodesmosin is located in the desmosomes of the upper living layers, and in related structures of the cornified layers, the corneodesmosomes. During maturation of the cornified layers, the protein undergoes a series of cleavages, thought to be a prerequisite of desquamation. Partial amino acid sequencing of corneodesmosin fragments suggested that it is related to the product of the S gene, previously identified in the human major histocompatibility complex. We report the expression cloning of corneodesmosin cDNA from a human epidermis library screened with monoclonal antibodies. Sequencing demonstrated that corneodesmosin is really the product of the S gene. However, analysis of 20 alleles of the gene revealed that its product is 27 amino acids longer than initially reported. Two additional polymorphic sites were described, and the position of the unique intron was ascertained. Corneodesmosin cDNA expression in COS-7 cells led to secretion of the protein. Precise epitope mapping allowed further characterization of the molecular forms of corneodesmosin present in the most superficial cornified layers, where fragments corresponding to the central region of the protein were detected. This indicated a cleavage of the N- and C-terminal domains of corneodesmosin before desquamation. These serine- and glycine-rich domains are proposed to mediate an adhesive function.

Amino Acid Sequence

Functional characterization of the low-molecular-mass phosphotyrosine-protein phosphatase of Acinetobacter johnsonii.

The ptp gene of Acinetobacter johnsonii was previously reported to encode a low-molecular-mass protein, Ptp, whose amino acid sequence, predicted from the theoretical analysis of the nucleotide sequence of the gene, exhibits a high degree of similarity with those of different eukaryotic and prokaryotic phosphotyrosine-protein phophatases. We have now overexpressed the ptp gene in Escherichia coli cells, purified the Ptp protein to homogeneity by a single-step chromatographic procedure, and analysed its functional properties. We have shown that Ptp can catalyse the dephosphorylation of p-nitrophenyl phosphate and phosphotyrosine, but has no effect on phosphoserine or phosphothreonine. Its activity is blocked by ammonium molybdate and sodium orthovanadate, which are strong inhibitors of phosphotyrosine-protein phosphatases, as well as by N-ethylmaleimide and iodoacetic acid. Such specificity of Ptp for phosphotyrosine has been confirmed by the observation that it can dephosphorylate endogenous proteins phosphorylated on tyrosine, but not proteins modified on either serine or threonine. In addition, Ptp has been shown to quantitatively dephosphorylate two exogenous peptides, derived respectively from leech hirudin and human gastrin, previously phosphorylated on tyrosine. Moreover, site-directed mutagenesis experiments performed on Cys11 and Arg16, which are both present in the sequence motif (H/V)C(X5)R(S/T) typical of eukaryotic phosphotyrosine-protein phosphatases, have demonstrated that each amino acid residue is essential for the catalytic activity of Ptp. Taken together, these data provide evidence that Ptp is a member of the phosphotyrosine-protein phosphatase family. Furthermore, in search for the biological function of Ptp, we have found that it can specifically dephosphorylate an endogenous protein kinase, termed Ptk, which is known to autophosphorylate at multiple tyrosine residues in the inner membrane of Acinetobacter johnsonii cells. This represents the first identification of a protein substrate for a bacterial phosphotyrosine-protein phosphatase, and therefore constitutes a possible model for analysing the role of reversible phosphorylation on tyrosine in the regulation of microbial physiology.

Acinetobacter

Influence of digital rectal massage on urinary prostate-specific antigen: interest for the detection of local recurrence after radical prostatectomy.

BACKGROUND: Following radical prostatectomy, urinary prostate-specific antigen (uPSA) may originate from periurethral glands or from recurrent carcinomatous prostatic cells. We evaluated massage of the urethro-vesical anastomosis as a uPSA-releasing method for the detection of local recurrence. METHODS: PSA was assessed (PSA IMx, Abbott Diagnostic, Rungis, France) in serum and in the first voided urine before and after massage in 59 patients: 7 after cystoprostatectomy for bladder cancer, 22 with prostate in situ, and 30 after radical prostatectomy for prostate cancer. RESULTS: No significant changes of uPSA were induced by the massage in cystoprostatectomy patients and in 4 radical prostatectomy patients with a negative biopsy of the anastomosis. In contrast, a significant increase of uPSA was observed after massage in the patients with prostate in situ and in 6 radical prostatectomy patients with biopsy-proven local relapse. CONCLUSIONS: uPSA before and after massage of the prostatic fossa may constitute a new and efficient tool for the detection of local recurrence, if these preliminary results are confirmed on a larger scale.

Adult

IL-4 addition during differentiation of CD34 progenitors delays maturation of dendritic cells while promoting their survival.

Dendritic cells (DC) are the most effective cells for antigen presentation in primary immune responses. Human cord blood CD34+ progenitors cultured in the presence of GM-CSF and TNF alpha generate a heterogeneous population of DC including Langerhans-like DC (LLDC) and monocytes. We describe here that IL-4 exerts different effecs in such culture according to the cells considered. Thus, IL-4 favors DC components at the expense of monocytic development, and permits long-time persistence of DC which can be maintained up to one month in culture. These results show an IL-4-dependent inhibition of proliferation and emergence of CD14+ cells. Notably, however, IL-4 also acts on the DC precursors. Thus, IL-4 enhances survival and delays maturation of LLDC from CD1a+ CD14- precursors. In addition, IL-4 also favors orientation of CD14+ CD1a- DC/monocyte precursors towards dermal-type CD1a+ DC. DC recovered from IL-4 treated cultures display reduced allostimulatory capacity, but this function is restored upon IL-4 weaning. Finally, a short (48h) IL-4 pulse is sufficient to favor DC development. The present study demonstrates that IL-4 positively regulates DC development at several levels on distinct precursor cells.

Antigens, CD1

Evaluation of pleural CYFRA 21-1 and carcinoembryonic antigen in the diagnosis of malignant pleural effusions.

CYFRA 21-1 assay, measuring cytokeratin 19 fragments, was compared with carcinoembryonic antigen (CEA) assay, as an addition to cytological analysis for the diagnosis of malignant effusions. Both markers were determined with commercial enzyme immunoassays in pleural fluid from 196 patients. Cytological analysis and/or pleural biopsy confirmed the malignant origin of the effusion in 99 patients (76 carcinomas, nine pleural mesotheliomas and 14 non-epithelial malignancies). Effusions were confirmed as benign in 97 patients (33 cardiac failures, 39 infectious diseases--including 12 tuberculosis-- and 25 miscellaneous effusions). Both markers were significantly higher in malignant than in benign effusions. All the patients with non-epithelial malignancies presented CYFRA and CEA values lower than the 95% diagnostic specificity thresholds (100 and 6 ng ml(-1) respectively). The diagnostic sensitivity in the group of carcinomas and mesotheliomas was similar for CYFRA (58.8%) and CEA (64.7%). However, CEA had a significantly higher sensitivity in carcinomas (72.4% vs 55.3%), while CYFRA had a clearly higher sensitivity in mesotheliomas (89.9% vs 0%). Interestingly, 12 out of the 16 malignant effusions with a negative cytology were CEA and/or CYFRA positive. Regarding their high diagnostic sensitivity and their complementarity, CEA and CYFRA appear to be very useful for the diagnosis of malignant pleural effusions when cytology is negative.

Adolescent

The bearded airway.

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Emergency Treatment