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Biomedical subjects

J Blondel

Publications and source records attributed to J Blondel.

11 recordsLinked to original sources
PubMed2003

[Retinal vein occlusion and hyperhomocysteinemia].

INTRODUCTION: Previous studies have reported that an elevated plasma homocysteine level is a risk factor for vascular disease. The aim of this study is to determine whether hyperhomocysteinemia is a risk factor for retinal vein occlusion (RVO) and whether it is a prognostic factor. PATIENTS AND METHODS: The plasma homocysteine level was measured in 101 patients and compared to the plasma homocysteine level of controls. The relation between plasma homocysteine level and the other known risk factors of retinal vein occlusion was studied, as well as the correlation between the clinical outcome of the RVO and the plasma homocysteine level. RESULTS: The mean plasma homocysteine level was significantly higher in the 101 RVO patients than in the 29 controls (11.9 mmol/l vs 8.6, p<0.001). We found no relation between plasma homocysteine and other risk factors of vascular disease except for the hematocrit level. Hyperhomocysteinemia was more frequent in the ischemic forms and in bilateral RVO, but the difference was not statistically significant. CONCLUSIONS: Hyperhomocysteinemia seems to be an independent risk factor for RVO and was more frequent in severe RVO, but our study did not evidence an association with a severe prognosis. Vitamin therapy can decrease homocysteinemia but its efficacy in the prevention and in the treatment of RVO remains to be demonstrated.

Adult↗
PubMed2001

Energetic and fitness costs of mismatching resource supply and demand in seasonally breeding birds.

By advancing spring leaf flush and ensuing food availability, climatic warming results in a mismatch between the timing of peak food supply and nestling demand, shifting the optimal time for reproduction in birds. Two populations of blue tits (Parus caeruleus) that breed at different dates in similar, but spatially distinct, habitat types in Corsica and southern France provide a unique opportunity to quantify the energetic and fitness consequences when breeding is mismatched with local productivity. As food supply and demand become progressively mismatched, the increased cost of rearing young pushes the metabolic effort of adults beyond their apparent sustainable limit, drastically reducing the persistence of adults in the breeding population. We provide evidence that the economics of parental foraging and limits to sustainable metabolic effort are key selective forces underlying synchronized seasonal breeding and long-term shifts in breeding date in response to climatic change.

Adaptation, Physiological↗
PubMed2000

[Optic neuropathy after proton-beam therapy for malignant choroidal melanoma].

Proton-beam irradiation is a conservative therapy commonly used for the treatment of uveal malignant melanomas. Some adverse effects such as optic neuropathy can compromise the visual outcome. We were interested in determining the risk factors for radiation papillopathy. Since there is currently no effective therapy, this is an interesting way to improve prevention of optic neuropathy. Six hundred sixty-two eyes had more than 24 month follow-up after proton-beam irradiation for uveal melanoma. In five hundred twenty-two cases, the clinical examination of the optic nerve head by ophthalmoscopy was possible. One-hundred eleven optic discs were pathologic, whereas 411 remained disease-free. Retrospective study of these two groups allowed to quantify the risk factors for optic neuropathy. The irradiation of more than 2mm of optic nerve at 30 Grays-equivalents appeared to be the major risk factor for optic neuropathy. For a given irradiation dose, the observed pattern of clinical responses was heterogeneous. These results are discussed and compared to the previous published reports. Visual results and life prognosis are also discussed, considering the optic nerve head status. Proton-beam therapy can preserve the optic nerve when the tumor location allows to keep it away from the irradiation-field. Patients must be informed about the risk of optic neuropathy after proton-beam irradiation.

Choroid Neoplasms↗
PubMed1999

Selection-Based Biodiversity at a Small Spatial Scale in a Low-Dispersing Insular Bird.

The blue tit is a highly mobile small passerine found in deciduous and evergreen oaks. In mainland populations, gene flow results in local maladaptive timing of breeding in evergreen oak forests, the rarer habitat. However, on the island of Corsica, two populations only 25 kilometers apart are highly specialized and differ between the two habitat types in breeding and morphological traits. In contrast to theoretical predictions about the homogenizing effects of gene flow, this highlights evolutionary consequences of habitat diversification and isolation at a small spatial scale in insular organisms, which should be taken into account in conservation policies.

Journal Article↗
PubMed1997

A single response mechanism is responsible for evolutionary adaptive variation in a bird's laying date.

Many proximate factors determine a bird's laying date, including environmental and social stimuli as well as individual responses to internal and external factors. However, the relative importance of these factors has not been experimentally demonstrated. Here we show that (i) large differences in the onset of first clutches between different populations result from variation in different responses to photoperiod and not from variation in responses to any other proximate factors and (ii) the same response mechanism causes maladaptive laying dates in habitats modified by humans. We present, to our knowledge, the first experimental demonstration that a single response mechanism is responsible for evolutionary adaptive intraspecific variation in a vertebrate life history trait.

Journal Article↗
PubMed1995

[Ambulatory laser and turbinectomy in the treatment of nasal obstruction. Apropos of 68 cases].

The purpose of this prospective study was to compare subjectively and objectively the efficiency of laser vaporisation against surgical procedure in treatment of nasal obstruction related to vasomotor rhinitis. 40 inferior nasal turbinates laser vaporisations were compared to 28 surgical inferior turbinectomies. This trial was based on rhinomanometric data before and after laser or surgical management and on appreciation of individual nasal comfort. The results obtained with conventional surgery were slightly better than laser vaporisation; however this new procedure succeed in 75% of cases with a mean of one year follow-up. The rhinomanometric++ findings appeared especially contributing when significant disorders exist before treatment.

Adolescent↗
PubMed1994

Nosocomial pneumonia in mechanically ventilated patients receiving antacid, ranitidine, or sucralfate as prophylaxis for stress ulcer. A randomized controlled trial.

OBJECTIVE: To assess three anti-stress ulcer prophylaxis regimens in mechanically ventilated patients for bacterial colonization, early- and late-onset nosocomial pneumonia, and gastrointestinal bleeding. DESIGN: Randomized controlled trial. PATIENTS: Consecutive eligible patients with mechanical ventilation and a nasogastric tube. Of 258 eligible patients, 244 were assessable. SETTING: Medical and surgical intensive care units. INTERVENTION: At intubation, patients were randomly assigned to receive one of the following: antacid (a suspension of aluminum hydroxide and magnesium hydroxide), 20 mL every 2 hours; ranitidine, 150 mg as a continuous intravenous infusion; or sucralfate, 1 g every 4 hours. MEASUREMENTS: Using predetermined criteria, the incidence of gastric bleeding, gastric colonization, early-onset pneumonia, and late-onset pneumonia was assessed in patients intubated for more than 24 hours. RESULTS: Of 244 assessable patients, macroscopic gastric bleeding was observed in 10%, 4%, and 6% of patients assigned to receive sucralfate, antacid, and ranitidine, respectively (P > 0.2). The incidence of early-onset pneumonia was not statistically different among the three treatment groups (P > 0.2). Among the 213 patients observed for more than 4 days, late-onset pneumonia was observed in 5% of the patients who received sucralfate compared with 16% and 21% of the patients who received antacid or ranitidine, respectively (P = 0.022). Mortality was not statistically different among the three treatment groups. Patients who received sucralfate had a lower median gastric pH (P < 0.001) and less frequent gastric colonization compared with the other groups (P = 0.015). Using molecular typing, 84% of the patients with late-onset gram-negative bacillary pneumonia were found to have gastric colonization with the same bacteria before pneumonia developed. CONCLUSION: Stress ulcer prophylaxis with sucralfate reduces the risk for late-onset pneumonia in ventilated patients compared with antacid or ranitidine.

Adult↗
PubMed1991

[Pneumological exercise test and pulmonary hypertension].

The aims of and indications for exercise testing as a noninvasive method in pneumology are described with special emphasis on the diagnosis of chronic thrombo-embolic disease and primary pulmonary hypertension. The methodology and the criteria of interpretation as well as the diagnostic value are exposed.

Chronic Disease↗
PubMed1972

[The Am system].

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Antibody Specificity↗
PubMed1972

[The Am system].

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Alleles↗