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Biomedical subjects

P Vuagnat

Publications and source records attributed to P Vuagnat.

At least 19 recordsLinked to original sources
PubMed1991

Reaction mechanism of trypsin-catalysed semisynthesis of human insulin studied by fast atom bombardment mass spectrometry.

The production of semisynthetic human insulin for therapeutic purposes is of considerable importance. During trypsin-catalysed transformation of pig insulin into an ester of insulin of human sequence, the alanyl residue at position B30 is removed and replaced with an esterified residue of threonine. We have carried out this transformation in a medium enriched in 18OH2 and studied the product by MS. In contrast to a previous report, we find that incorporation of label into the B29 - B30 peptide bond occurs during the transformation with threonine methyl ester in aqueous N,N-dimethylacetamide. Quantitative data are presented and the implications of these findings are discussed.

Animals↗
PubMed1990

Increase of interproximal bone density after subgingival instrumentation: a quantitative radiographical study.

Ten interproximal sites, with periodontal pockets deeper than 5 mm and showing loss of bone on standard dental radiographs, were treated by subgingival instrumentation in 10 patients properly motivated and given thorough hygiene instructions. The index of gingival inflammation, the plaque index, the degree of mobility, the depth of the pockets, and the loss of attachment were measured before starting the treatment, and 2 months, 6 months, and 1 year after treatment. Standardized reproducible radiographs of the 10 sites were taken by using a recently developed paralleling instrument before treatment, immediately after and 2 months, 6 months, and 1 year afterwards. The density of the interdental bone was measured on the radiographs by a computer assisted densitometric technique at three levels of the interdental septum: the most occlusal or "superficial" level; the "deep" level, arbitrarily chosen 1.5 mm below; and the "control" level, in a much deeper area of interproximal bone. As further control, the density of the superficial crestal bone was also followed in 5 healthy untreated sites from 5 of the patients. As expected, a significant improvement of the clinical parameters was observed during the year following therapy. The results of the radiographical analysis showed statistically significant increases of both the superficial and deep average densities of interproximal bone at 6 months and 1 year after treatment. The superficial bone density was, on the average, 13% higher at 6 months and 16% higher at 1 year, as compared to that measured immediately after treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMed1988

The preparation of porcine (Tyr-A14-2H) insulin and its characterization by mass spectrometry.

The title compound was prepared by catalytic deiodination of (Tyr-A14-3-I) insulin with deuterium gas. Under special conditions (large excess of PdO in CH3OD/D2O at pH 9.2) developed to minimize problems due to poisoning of the catalyst, deuterated insulin was produced in yields of about 35% after purification by reversed phase HPLC. For analysis, the deuterated insulin was digested with V8 protease and was shown by mass spectrometry to have incorporated deuterium to an extent of 96.6 atom %, exclusively in a pentapeptide containing Tyr A14. The title compound should prove useful to those workers studying insulin by mass spectrometry, and use of the method with tritium gas in place of deuterium should permit the preparation of a specifically labelled radioactive insulin analogue which behaves identically to the natural hormone.

Animals↗
PubMed1987

Cytogenetic studies of human testicular germ cell tumours.

In a search for consistent cytogenetic alterations in testicular germ cell cancers we have thus far studied some twenty surgical specimens of seminomas and nonseminomatous tumours. From the literature and our results it is now clear that such testicular tumours generally have a hyperdiploid to hypotriploid chromosomal content, and frequently possess a possibly site-specific chromosomal marker, an isochromosome 12p. A significant correlation between the presence of the i(12p) and advanced clinical stages has been revealed in our study. Several other chromosomal regions are consistently involved in cytogenetic changes: 1p and 1q, 6q, 7p, 9q, 12p, 17q, and 22q. Although there is little doubt that characteristic chromosomal lesions exist in testicular germ cell tumours, the impact which specific lesions may have on tumour progression is still unclear.

Chromosome Aberrations↗
PubMed1985

Mating is random.

Human leukocyte antigen (HLA) typing was undertaken in 151 unrelated blood donors and in 35 normal couples having at least two living children. We compared observed and expected sharing of HLA antigens at four loci in normal couples. We also compared the observed sharing in couples with the expected sharing in unrelated blood donors if taken two by two and with the sharing observed after 1000 "synthetic matings" of normal couples. No statistically significant difference in HLA sharing appeared between these groups. Furthermore no differences were observed in the probabilities of sharing individual HLA antigens among the different groups. We thus conclude that the observed HLA sharing in normal couples is governed by chance alone and that mating is random in our population.

Female↗
PubMed1984

Absence of a direct inhibitory effect of the gonadotropin-releasing hormone (GnRH) agonist D-Ser (TBU)6, des-Gly-NH2(10) GnRH ethylamide (Buserelin) on testicular steroidogenesis in men.

The antigonadal effects of GnRH agonists (GnRH-A) are mediated both through pituitary and testicular inhibitory mechanisms in the rat. To investigate these effects in men, we studied patients having no gonadotropin secretion and compared their testicular response to hCG in the absence or in the presence of GnRH-A. Thirteen patients with acquired pituitary hypogonadotropism had plasma testosterone levels below 1.5 ng/ml and no gonadotropin responses to acute GnRH administration (100 micrograms iv). Testicular responsiveness was evaluated using a single im injection of hCG (5000 IU im). Plasma levels of testosterone, dihydrotestosterone, androstenedione, 17-hydroxyprogesterone (17-OHP), and progesterone were determined before and 4, 12, 24, 48, and 72 h after hCG stimulation. The same protocol was also used in the same patients on day 4 of a 6-day course of treatment with the GnRH-A, D-Ser-(TBU)6, des-Gly NH2 GnRH ethylamide (Buserelin) (3 sc injections of 250 micrograms/day). During the first 4 days of GnRH-A administration, plasma LH, FSH, and testosterone levels were measured daily in order to establish the completeness of the gonadotropin deficiency. Before treatment with hCG, plasma testosterone levels were 0.56 +/- 0.15 and 0.96 +/- 0.22 ng/ml (mean +/- SE) in the absence of GnRH-A and during GnRH-A administration, respectively. The administration of hCG elicited a significant increase in plasma testosterone in both situations; integrated testosterone concentrations were 123.7 +/- 24.9 and 155.5 +/- 27.9 ng/ml . 72 h (P greater than 0.1) in the absence of GnRH-A and during GnRH-A administration, respectively. Likewise the ratios of 17-OHP to progesterone, androstenedione to 17-OHP, and dihydrotestosterone to testosterone after hCG injection were similar in the presence or absence of GnRH-A. Since short term administration of buserelin did not inhibit hCG-induced testosterone secretion in patients with gonadotropin deficiency, we suggest that Buserelin does not grossly modify the function of testicular steroidogenesis enzymes. The antigonadal effects of GnRH-A in man appear to be mediated exclusively through the pituitary.

Buserelin↗
PubMed1983

Longitudinal radiographical study on the rate of alveolar bone loss in patients of a dental school.

Two sets of radiographs, taken at an interval of 4-14 years in 105 patients of a dental school, were examined in order to determine the rate of resorption of alveolar bone. The percentage loss of maximum alveolar bone height was measured in the interproximal and interradicular sites by means of the Schei ruler. The average percentage of interproximal bone resorption was 0.51% (0.07 mm) per year. Age, sex, professional status, type of periodontal treatment and general state of health did not seem to affect the annual resorption rate. However, crowned teeth had a significantly greater rate of resorption than uncrowned teeth. Loss of bone tended to be more rapid in interdental as compared to interradicular areas. A positive and statistically significant correlation was found between initial resorption and annual tooth loss.

Adolescent↗
PubMed1983

Humeral retrotorsion and glenohumeral relationship in the normal shoulder and in recurrent anterior dislocation (scapulometry).

The authors' roentgenographic technique provides precise assessment of the glenohumeral relationship on the basis of two-plane examination. A group of 50 normal male subjects serve as the basis for determining normal values for the following angles or lines: projected and corrected cephalodiaphyseal angle, projected and corrected humeral retrotorsion, glenoid inclination, angle of attack, glenoid retroversion, dimension of glenoid, width of humeral head, and contact index. Two groups of patients suffering from recurrent anterior dislocation (RAD) are compared with the normal group. The shoulders with RAD do not differ significantly from the normal ones. Humeral retrotorsion, in particular, is identical. Significant differences are found between affected and unaffected sides in unilateral RAD. The diameter of the glenoid and the contact index are smaller on the dislocated side. Because the projected values seldom differ by more than 10 degrees from the calculated values, if the authors' roentgenographic technique is used, the figures can generally be accepted without correction.

Humans↗
PubMed1977

Further studies on the biological properties of guinea-pig IgG1 antibodies. III. Haemolytic efficiency in vitro.

The capacity of non-reciprocally contaminated guinea-pig IgG1 and IgG2 antibodies for sensitizing antigen-coated sheep erythrocytes for lysis was studied in the presence of serial dilutions of normal guinea-pig serum as the source of complement. IgG1 antibodies were highly efficient, provided complement was little diluted and not heated at 56 degrees. Chelation of Ca2+ by EGTA affected lysis of IgG1-sensitized cells by only 50%, while completely blocking lysis of IgG2-sensitized cells. The F(ab')2 fragment of IgG1, in contrast to the F(ab')2 fragment of IgG2, was almost as efficient as the parent antibody.

Animals↗
PubMed1975

Further studies on the biologic properties of guinea pig IgG1 antibodies. II. In vivo activation of C3 by anti-glomerular basement membrane antibodies.

Normal rats were injected with guinea pig anti-rat glomerular basement membrane antibodies of the IgG1 or IgG2 class or with their F (ab') 2 fragments, in order to study which antibody site triggers the alternate complement pathway in vivo. Both IgG classes were able to induce a heavy proteinuria and led to C3 deposition in the glomeruli in a pattern similar to their own distribution along the glomerular basement membrane, as shown by the immunofluorescence technique. The Fab(ab')2 fragment of IgG2 did not produce C3 binding or proteinuria. The F(ab')2 fragment of IgG1 was difficult to obtain devoid of Fc determinants. A F(ab')2 fragment of IgG1 still bearing Fc determinants led to C3 binding and proteinuria, whereas the true F(ab')2 fragment of IgG1 had none of these effects in two out of three animals.

Animals↗
PubMed1973

Immunodeviation by passive antibody, an expression of selective immunodepression. II. Action of guinea pig IgG1 and IgG2 anticarrier antibodies.

The effect of passively administered IgG1 and IgG2 anticarrier antibodies on the IgG1 and IgG2 antihapten response has been studied. Guinea pigs were immunized with dinitrophenylated bovine gamma globulin mixed with purified IgG1 or IgG2 antihuman gamma globulin antibodies, i.e., antibodies directed against a limited range of the carrier determinants. Humoral IgG1 and IgG2 anti-DNP antibody contents were assayed at weekly intervals and 4 to 10 days after a booster injection of antigen in saline given on the 12th wk. The main finding was the sustained suppressive effect of passive IgG1 anti-carrier antibodies on the active IgG1 antihapten response. This result is compared with the enhancing effect of passive IgG1 antihapten antibodies and is discussed in the light of T cell-B cell and hapten-carrier relationships, leading to the proposal of a regulatory function of the Fc portion of the IgG1 anticarrier antibody, combined with the antigen, on the T cell.

Animals↗