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Biomedical subjects

P Thibault

Publications and source records attributed to P Thibault.

At least 19 recordsLinked to original sources
PubMed1992

Characterization of a prolyl endopeptidase from Flavobacterium meningosepticum. Complete sequence and localization of the active-site serine.

A prolyl endopeptidase was purified from Flavobacterium meningosepticum. It was digested with trypsin. Two oligonucleotides, based on tryptic peptide sequences and used in PCR experiments, amplified a 300-base pair (bp) fragment. A 2.4-kilobase EcoRI fragment that hybridized to the 300-bp probe was cloned in lambda ZAP and sequenced from both strands. It contains a reading frame of 2115 bp, encoding the complete protein sequence of 705 amino acids. Ion-spray mass spectrometry experiments demonstrated the presence of an NH2-terminal signal peptide: the periplasmic mature protease is 685 residues in length for a molecular mass of 76784 Da. The prolyl endopeptidase showed no general sequence homology with known protein sequences except with that of porcine brain prolyl endopeptidase. In order to identify the active-site serine, the prolyl endopeptidase was labeled with [3H]diisopropyl fluorophosphate. One labeled peptide was purified and sequenced. The active-site serine was located in position 536 within the sequence GRSNGG. This sequence is different from the active-site sequence of the trypsin (GDSGGP) and subtilisin (GTSMAS) families.

Amino Acid Sequence↗
PubMed1992

Comparison of liquid-junction and coaxial interfaces for capillary electrophoresis-mass spectrometry with application to compounds of concern to the aquaculture industry.

The application of capillary electrophoresis-mass spectrometry (CE-MS) to the analysis of compounds of concern to the aquaculture industry is reported. Two different approaches to coupling the CE column to an IonSpray atmospheric pressure ionization (API) interface, viz., a liquid-junction and a coaxial arrangement, are describe and compared with regard to ruggedness, ease of use, sensitivity and electrophoretic performance. The different injection modes used in three commercial capillary electrophoresis systems were also evaluated for their applicability to CE-MS. The use of CE-MS for the analysis of a variety of classes of antibiotics used in the fish aquaculture industry, such as the sulfonamides and their potentiators (e.g., trimethoprim), is demonstrated and was used to confirm the presence of these components in shellfish extracts at the low ppm level. CE-MS was also applied to the analysis of marine toxins such as saxitoxin and its analogues which are associated with paralytic shellfish poisoning, and also the toxins responsible for amnesic and diarrheic shellfish poisoning. Tandem mass spectrometry (MS-MS) was used to provide structural information on these analytes, and the ability to distinguish isomeric compounds based on their different migration and fragmentation characteristics using CE-MS-MS is demonstrated.

Anti-Bacterial Agents↗
PubMed1992

Isolation, mass spectrometric characterization, and protein phosphatase inhibition properties of cyclic peptide analogues of gramicidin-S from Bacillus brevis (Nagano strain).

Six substitutional variants of gramicidin-S, present in a commercial extract of Bacillus brevis, have been characterized using a combination of liquid chromatographic/mass spectrometric analysis of the crude extract, plus accurate mass measurements, tandem mass spectrometric investigations, and amino acid analyses, of isolated high-performance liquid chromatographic fractions. Two of these variants were shown previously (Nozaki and Muramatsu, J. Antibiotics 37, 689 (1984)) to involve replacement of one or both Val residues in gramicidin-S by aminobutyric acid, and these findings are confirmed here. One of the four unknown variants corresponds to substitution of one Val residue by Leu, while the other three all involve substitution of one of the Orn residues in gramicidin-S by Lys, or by citrulline (gamma-carbamoyl ornithine), or by gamma-formyl ornithine. The biological activities of the purified fractions were assessed with respect to their in vitro inhibition of protein phosphatases PP1 and PP2A. For both protein phosphatases inhibition levels fell in the micromolar range, about four orders of magnitude higher than IC50 values for other small cyclic peptides such as microcystins and nodularins.

Amino Acids↗
PubMed1992

Ionspray mass spectrometry of marine toxins. III. Analysis of paralytic shellfish poisoning toxins by flow-injection analysis, liquid chromatography/mass spectrometry and capillary electrophoresis/mass spectrometry.

Ionspray mass spectrometry has been used to monitor the purification of saxitoxin, the parent compound in the family of toxins responsible for paralytic shellfish poisoning (PSP), from a strain of the dinoflagellate Alexandrium excavatum. Quantitative results obtained by flow-injection analysis are compared to those obtained by high-performance liquid chromatography with post-column oxidation and fluorescence detection. The coupling of liquid chromatography and capillary electrophoresis with ionspray mass spectrometry is described for the separation of mixtures of PSP toxins and the highly potent pufferfish toxin tetrodotoxin. Tandem mass spectrometry is used to provide the structural information, and the ability to distinguish isomeric PSP toxins both chromatographically and mass spectrometrically is demonstrated.

Chromatography, High Pressure Liquid↗
PubMed1992

Postsclerotherapy hyperpigmentation. The role of serum ferritin levels and the effectiveness of treatment with the copper vapor laser.

Cutaneous pigmentation is a common complication of sclerotherapy of dilated lower limb veins. Histologic examination has shown that the pigment is due to hemosiderin deposition predominantly in the superficial dermis. Optimal technique will reduce the incidence of pigmentation but it is likely that patient factors such as total body iron storage may explain why some patients are more prone to develop pigmentation. Traditional exfoliation therapies have not given reliable reproducible results and there is need to develop an effective treatment without adverse sequelae. In this study 16 patients with refractory postsclerotherapy pigmentation were treated with the copper vapor laser. Within 3 months of treatment 11 (69%) had significant clearing of the pigmentation. Four (25%) had slight improvement and one patient had no discernible improvement. No adverse sequelae were reported or observed. The treated patients and 16 matched control patients who had not developed pigmentation were investigated with serum iron, ferritin and transferrin levels. There was a trend towards higher serum iron and ferritin levels and lower transferrin levels in the patients who developed pigmentation compared with those who did not develop this sequela. This trend was statistically significant for ferritin levels in patients 50 years of age and younger. The results indicate that serum ferritin may be a good indicator of susceptibility to postsclerotherapy pigmentation.

Adult↗
PubMed1992

[Sub-venous iliac lymphatic dissection with celioscopy for the staging of prostatic cancer (16 patients)].

Subvenous external iliac lymph node dissection is an essential element for the staging of prostatic cancer. 7 to 30% of patients with intracapsular prostatic cancer have lymph node metastases despite normal imaging examinations. Laparoscopic surgery allows lymph node dissection through a limited incision. Sixteen patients underwent laparoscopic lymph node dissection (LLND) for prostatic cancer. The mean duration of the operation was 100 +/- 50 minutes (35-180 min: 130 minutes for the first nine operations, then 60 minutes for the last seven operations). One patient died on the second day from a cerebral vascular accident. There was one technical failure (pneumoperitoneum leak), one vascular injury, one ureteric injury, one transient paresis of the obturator nerves and one case of perineal lymphoedema. The mean number of lymph nodes removed in bilateral lymph node dissection was 7.5 +/- 2 (14-20) per patient. Three patients had lymph node metastases. The mean hospital stay related to laparoscopy was 4 +/- 2 days with a median of 2 days. Laparoscopic surgery, like any conventional or innovative surgical technique, requires specific training to become safe and effective. It allows complete histological examination of the lymph nodes removed and planning of prostatectomy, which may be subsequently performed through a perineal approach.

Abdomen↗
PubMed1992

[Vesico-ureteral reimplantation on psoas bladder in lesions of the pelvic ureter. Review of 50 patients].

Between 1979 and 1991, the authors performed 50 psoas bladder ureterovesical reimplantations for lesions of the pelvic ureter. 90% of very good results were obtained with this technique at the cost of a low morbidity. This series confirms the influence of previous pelvic radiotherapy on the postoperative complication rate. On the basis of the excellent results in this series, confirmed by those reported in the literature, this technique can be proposed as treatment of choice for lesions of the pelvic ureter when suture-resection or simple reimplantation cannot be performed after failure of endoluminal dilatation in patients with a life expectancy greater than 6 months to one year.

Adolescent↗
PubMed1992

Bladder reconstruction with ileum after cystoprostatectomy for bladder cancer: analysis of the micturition and continence of 44 consecutive patients.

From October, 1987, to August, 1990, 47 patients underwent an ileal low pressure bladder replacement using the Hautmann procedure after radical cystoprostatectomy for bladder cancer. The qualities of micturition and continence were evaluated from a questionnaire mailed to the patients and by urodynamic examinations in 44 consecutive patients over a follow-up period of more than 3 (mean 10.7) months. The 44 patients (100%) were perfectly dry during the daytime and voided every 4 (2-6) h with a micturitional volume of 357 (200-500) ml. Forty-two of the 44 patients had no residual urine. Thirty-three of the 44 patients (75%) were perfectly dry at night with a voiding frequency of 1.5 (0-3). Seven of the 44 patients (16%) were occasionally incontinent (spotting less than 2/week). Four of the 44 patients (9%) had night incontinence and used as external device. Only two patients showed high pressure waves of greater than 50 cm H2O. The maximum urethral pressure was 59.07 +/- 13.6 (30-80) cm H2O. The maximum flow rate was 17.2 +/- 9.7 (4.5-35) ml/sec. The different factors responsible for the new micturitional balance were discussed. With its very good functional results and its ease of performance, the ileal neobladder is, for us, the procedure of choice for bladder reconstruction after cystectomy.

Adult↗
PubMed1991

Analysis of paralytic shellfish poisons by capillary electrophoresis.

A capillary electrophoresis (CE) method with UV detection is described for the separation and determination of underivatized toxins associated with paralytic shellfish poisoning (PSP). Confirmation of the electrophoretic peaks was facilitated by mass spectrometric (MS) detection using an ionspray CE-MS interface and by high-performance liquid chromatography with fluorescence detection. The determination of PSP toxins, such as saxitoxin and neosaxitoxin, in toxic dinoflagellates and scallops is demonstrated and comparisons are made with existing techniques.

Animals↗
PubMed1991

Analysis of peptides and proteins by capillary electrophoresis/mass spectrometry using acidic buffers and coated capillaries.

The direct coupling of capillary electrophoresis (CE) and mass spectrometry, combined with ionspray ionization using a coaxial capillary arrangement, is described. The CE/mass spectrometer interface is shown to be effective for the analysis of native and tryptic peptides and of proteins of high molecular weight such as bovine serum apotransferrin (approximately 78 kDa). Adsorption of cationic analytes under acidic buffer conditions is minimized through the use of a non-covalent coated capillary possessing an overall positive charge. Since the direction of the electroosmotic flow is thus reversed, compared to that in conventional CE separation on uncoated capillaries, migration of cations is achieved by applying a negative voltage (typically -30 kV) at the injector end of the capillary. In addition to the inherent advantage of providing pre-formed cationic species for mass spectral detection, this arrangement permits analysis of proteins of high isoelectric points even at low pH. The ability to conduct electrophoresis of globular proteins under acidic conditions also provides a means of monitoring their conformational changes, as reflected both by the variation of migration times and by concurrent changes in the multiply charged ion envelopes.

Amino Acid Sequence↗
PubMed1991

[Adrenal myelolipoma. Review of the literature and case report].

Adrenal myelolipoma is a rare, benign tumour composed of adipose and haematopoietic cells. It is usually an incidental finding or may present in the form of a complication, the most severe being spontaneous retroperitoneal rupture. Computed tomography is the best examination, providing a preoperative diagnosis in 90% of cases. Adrenal aspiration cytology is useful in the case of a persistent doubt concerning the diagnosis. The principal differential diagnosis consists of an angiomyolipoma of the upper pole of the kidney. The indications for surgical resection are limited to symptomatic tumours, tumours larger than 5 cm in diameter and in the case of a doubtful diagnosis.

Adrenal Gland Neoplasms↗
PubMed1991

[Should adrenalectomy be performed systematically as part of radical nephrectomy for renal cancer? Review of 119 cases].

Systematic histological examination of 119 operative specimens of radical nephrectomies performed for renal cell carcinoma revealed adrenal invasion in 6 cases (5.04%). Preoperative computed tomography visualised the adrenal lesions with a sensitivity of 100%. Adrenal involvement was due to either contiguous invasion (3 cases) or metastatic spread (3 cases). Other visceral or lymph node metastases were detected in every case. The mean survival of patients with an adrenal lesion was 16.5 months. These data and those reported in the literature suggest the value of systematic adrenalectomy as part of radical nephrectomy.

Adrenalectomy↗
PubMed1991

[Functional analysis of micturition and continence after a Hautmann type enterocystoplasty (27 patients)].

Twenty seven patients treated by Hautmann enterocystoplasty completed a detailed questionnaire concerning the quality of their micturition and continence. The mean capacity of the neobladder was 250 cc with a diurnal interval between micturitions of about 3 hours. 79% of patients experienced an urge to micturate. The mean frequency of nocturnal micturition was 1.6. Diurnal continence was perfect in 100% of patients, while nocturnal continence was excellent in 78% of cases and good in 18% of cases, while one patient (4%) suffered from nocturnal incontinence. Hautmann enterocystoplasty is therefore an excellent technique for bladder replacement, ensuring diurnal and nocturnal continence for the great majority of patients.

Aged↗
PubMed1990

Determination of the primary structure of peptides using fast atom bombardment mass spectrometry.

The determination of the amino acid composition and sequence of a peptide, using both conventional and tandem fast atom bombardment mass spectrometry, is presented. First a list of potential empirical formulae is generated using the accurate mass and isotopic peak intensity ratios from the molecular ion cluster. The formulae are mathematically analyzed to ensure that they correspond to linear peptides composed of 19 common amino acids. Then using the ions below m/z 160 Da, which are characteristic of the amino acid content of the peptide, the formulae are decomposed into possible amino acid compositions. From each composition sequences are generated and their predicted fragment ions are compared to ions present in the mass spectrum. A score based on the intensities and the occurrence of consecutive sequence fragments is calculated. Finally sequences with the ten highest scores are retained. Analyses performed on typical peptides with molecular weights below 1500 Da indicate that identification can generally be achieved using this approach.

Amino Acid Sequence↗