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Biomedical subjects

G Bonnet

Publications and source records attributed to G Bonnet.

13 recordsLinked to original sources
PubMed2002

Laparoscopic vertical banded gastroplasty for morbid obesity. Assessment of efficacy.

BACKGROUND: The advantages of treating morbidly obese patients via the laparoscopic approach have been demonstrated, in particular, for adjustable silicone gastric banding, but this operation is associated with a high rate of late complications. Gastric bypass and malabsorbitive procedures are feasible via the laparoscopic approach, but they entail a prolonged operating time and a consistently high morbidity rate. Laparoscopic vertical banded gastroplasty represents an effective alternative. METHODS: We performed 250 consecutive LVBG between November 1995 and February 2000. The procedure consisted of a personal technique designed to reproduce, by laparoscopy, MacLean's modification of the standard open Mason vertical-banded gastroplasty, with a calibrated transgastric window, a complete division between the staple lines, and a 5-cm-circumference polypropylene collar. RESULTS: The operative time was 95 min and the conversion rate was 0.8%. Operative mortality was nil; early and late complications, respectively, were 4.4% and 4%; the reoperation rate was 2%. Global results at 4 years were as follows: excess weight loss (EWL) 61%, success rate (excess weight <50%) 76.9%, body mass index (BMI) 29.4 kg/m2. In morbidly obese patients, the EWL at 4 years was 62.2%, with a 77.4% success rate and a 28.4 kg/m2 BMI; in superobese patients, the EWL at 4 years was 54.9% with a 50% success rate and a 35.5 kg/m2 BMI. The overall follow-up rate was 92%. CONCLUSIONS: LVBG is an effective and safe operation in morbidly obese patients, providing good weight loss with a low morbidity rate, no mortality, and minimum discomfort. However, in superobese patients, the weight loss results are disappointing; in these patients, LVBG is questionable and more complex procedures should be considered.

Adolescent↗
PubMed2000

Sequence dependent rigidity of single stranded DNA.

Single stranded DNA (ssDNA) equilibrium dynamics are investigated using a fluorophore/quencher-labeled hairpin structure which thermally fluctuates between open and closed states. Temporal correlations of the fluorescence fluctuations are used to determine the energy barrier to conformational change. We find that ssDNA distortion is purely entropic for poly(T) but requires an additional enthalpy of +0.5 kcal x mol(-1) x base(-1) for poly(A), consistent with the disruption of base stacking. Such sequence dependent dynamics challenge the classical model of ssDNA as a completely flexible coil.

DNA, Single-Stranded↗
PubMed1999

Thermodynamic basis of the enhanced specificity of structured DNA probes.

Molecular beacons are DNA probes that form a stem-and-loop structure and possess an internally quenched fluorophore. When they bind to complementary nucleic acids, they undergo a conformational transition that switches on their fluorescence. These probes recognize their targets with higher specificity than probes that cannot form a hairpin stem, and they easily discriminate targets that differ from one another by only a single nucleotide. Our results show that molecular beacons can exist in three different states: bound to a target, free in the form of a hairpin structure, and free in the form of a random coil. Thermodynamic analysis of the transitions between these states reveals that enhanced specificity is a general feature of conformationally constrained probes.

Base Sequence↗
PubMed1998

Kinetics of conformational fluctuations in DNA hairpin-loops.

The kinetics of DNA hairpin-loop fluctuations has been investigated by using a combination of fluorescence energy transfer and fluorescence correlation spectroscopy. We measure the chemical rates and the activation energies associated with the opening and the closing of the hairpin for different sizes and sequences of the loop and for various salt concentrations. The rate of unzipping of the hairpin stem is essentially independent of the characteristics of the loop, whereas the rate of closing varies greatly with the loop length and sequence. The closing rate scales with the loop length, with an exponent 2.6 +/- 0.3. The closing rate is increased at higher salt concentrations. For hairpin closing, a loop of adenosine repeats leads to smaller rates and higher activation energies than a loop with thymine repeats.

DNA↗
PubMed1998

An analysis of meiotic pairing in trisomy 21 oocytes using fluorescent in situ hybridization.

We report the use of chromosome 21-specific painting probes to analyze early stages of oogenesis in nine trisomy 21 fetuses. The proportion of cells in zygotene and pachytene in the trisomic ovaries ranged from 8 to 70% with a mean of 42% +/- 19 while the comparable values of euploid specimens ranged from 34 to 90% with a mean of 65% +/- 19. The low proportion of pairing cells may be the basis for the ovarian dysgenesis observed in some trisomy infants. Five percent of trisomic pachytene cells exhibited complete asynapsis which is an order of magnitude higher than that observed in euploid cells. A large fraction of the asynaptic cells were atretic which is consistent with the hypothesis of meiotic pairing as a signal for atresia. In addition, the asynaptic cells exhibited asynapsis of chromosomes other than 21, which we interpret as an interchromosomal effect of trisomy 21.

Chromosomes, Human, Pair 21↗
PubMed1991

A multicenter study of doxazosin in the treatment of essential hypertension in France.

This study was designed to assess the efficacy and tolerance of doxazosin in patients with mild, moderate, or severe essential hypertension in a general practice setting. Ninety-six adults of a mean age of 55 1/2 years took part in the 14-week study, consisting of a placebo phase (2 weeks), a dose-adjustment phase with doxazosin (8 weeks), and a maintenance phase (4 weeks). Doxazosin, at a final mean daily dose of 3.4 mg, produced a significant (p less than 0.05) reduction in blood pressure at all points of measurement during the study. The mean change in sitting blood pressure at the end of treatment was -15.4/-15.8 mm Hg. Of the 85 patients who could be categorized as a success or failure, 78 (92%) were considered a therapeutic success; 78 (89%) of the 88 efficacy-evaluable patients demonstrated an improvement in the severity category of their hypertension. Treatment with doxazosin produced a reduction in serum cholesterol (-3.1%) and triglyceride (-3.8%) levels, although these changes did not attain statistical significance. The calculated probability of developing coronary heart disease in 10 years (according to the Framingham equation) was significantly (p less than 0.001) reduced by 22%, from 16.7 chances per 100 (baseline) to 14.3 chances per 100 (final visit). Twenty-six patients (27.1%) reported side effects that were possibly related to treatment, the most prevalent of which were vertigo (7.3%) and headache (6.3%). In four (4.2%) patients the dose of doxazosin was reduced and two (2.1%) were withdrawn prematurely. The investigator's assessments of tolerance was reduced and two (2.1%) were considered to be excellent or good in 85 (88%) patients.

Antihypertensive Agents↗
PubMed1987

Evaluation of antihypertensive efficacy of lisinopril compared to metoprolol in moderate to severe hypertension.

A double-blind controlled, randomized, parallel, multicenter 12-week study was conducted to compare the antihypertensive efficacy of lisinopril with that of metoprolol in treatment of moderate to severe hypertension. Initially, 118 patients were recruited on lisinopril and 61 on metoprolol; and for the purpose of efficacy analysis at week 8, 115 patients on lisinopril and 60 on metoprolol were included. The doses of lisinopril or metoprolol were 40-80 mg/day and 100-200 mg/day, respectively. At week 4, the pretreatment diastolic blood pressure of 111 mm Hg was decreased to 97 mm Hg (p less than 0.01) with lisinopril: metoprolol decreased the diastolic blood pressure from 110 to 99 mm Hg (p less than 0.01). Similar decreases were noted at week 8; however, the drop in blood pressure with lisinopril was not significantly different from that with metoprolol. Systolic blood pressure also demonstrated a decrease of about 18 mm Hg with lisinopril and 12 mm Hg with metoprolol (p less than 0.01). This larger decrease in systolic blood pressure with lisinopril was statistically significant at week 4 (p less than 0.05). These decreases in systolic blood pressures were maintained at week 8, again with statistical significance (p less than 0.01). Of the 118 lisinopril-treated patients, four were discontinued from lisinopril therapy because of headache, dizziness, rash, flushing, or lymphadenopathy. Four patients out of 61 (9.8%) were discontinued from metoprolol therapy because of fatigue, somnolence, asthenia, weight gain, flatulence, tremor, or bronchospasm. In conclusion, lisinopril 40-80 mg once daily is as effective as metoprolol 100-200 mg once daily in reducing diastolic blood pressure in patients with moderate to severe hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMedDate not supplied

[Osteosynthesis by adherent plates. An experimental physical study].

The creation of ridges of the deep surface of plates used for osteosynthesis increases their adherence to bone. By increasing the coefficient of friction between the plate and the bone, the stresses taken by the screws can be diminished by a third. The procedures diminishes by the same amount the risk of stripping or loosening of screws and thus the risk of pseudarthrosis. Experimental study has been made by measurement with the aid of an elliptometer and modifications in the state of polarization of a Lawer beam under the influence of shearing strains. The strains were those imposed on screws in Araldite fixing a plate whose inferior surface was smooth on one end and ridged on the other. The ridges should not be such as to prevent the later removal of the plate. Screws should be applied for preference with a dynamometric screwdriver because the stress relief is maximal with a tightening force of 12 inch pounds.

Animals↗