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Biomedical subjects

S Bonnet

Publications and source records attributed to S Bonnet.

47 records · Page 3Linked to original sources
PubMed1993

Case report: associated retinal neovascularization and choroidal hemangioma.

Choroidal hemangiomas are vascular hamartomas that may be associated with secondary changes. Although subretinal fluid and associated neurosensory retina and retinal pigment epithelial changes are well documented, two cases in which retinal neovascularization was felt to be secondary to choroidal hemangiomas are presented. Long term follow-up reveals mild changes of the retinal neovascularization in both cases. The neovascularization did not affect the visual prognosis of the involved eyes.

Adult↗
PubMed1992

Assessment of vitamin A deficiency in a rural area in Mali. Estimation of sample size for the impression cytology test.

The prevalence of vitamin A deficiency among two to ten years old children in a rural area of Mali was assessed by ophthalmic examination, determination of plasma retinol levels and impression cytology with transfer tests. A Public Health problem of vitamin A deficiency was identified in this rural area by: the prevalence of nightblindness significantly (p < 0.001) above the cut-off (1%) defined by the World Health Organization (WHO); the prevalence of corneal scarring significantly (p < 0.001) above the WHO's cut-off (0.05%); the percentage of subjects with plasma retinol levels below 0.35 mumol/l (10 micrograms/dl) significantly (p < 0.001) higher than the WHO's threshold (5%); and 52.8 +/- 8.2% children with "Abnormal" impression cytology as determined by the impression cytology test (IC). This preliminary survey confirmed widespread vitamin A deficiency in Mali. The minimum sample size required for a study using the impression cytology test to determinate a Public Health problem in a population was calculated for different situations. Ophthalmic examination indicated a very high rate of active trachoma (29.6 +/- 7.0%), and a relationship between active trachoma and impression cytology results was identified.

Child↗
PubMed1992

[Influence of arterial hypertension on diabetic retinopathy].

In the industrialized countries, diabetic retinopathy represents the most frequent cause of blindness during the period of active life. It occurs as two distinct clinical entities: non proliferating retinopathy characterized by dilatation of the retinal capillary bed and alterations in their vascular wall responsible for an increase in permeability, and proliferating retinopathy characterized by the appearance of pre-retinal neovessels secondary to the presence of vast zones of retinal ischemia. Numerous risk factors are implicated in the development of diabetic retinopathy: the primordial factor is the optimal equilibration of blood glucose levels. The primum movens of these diabetic lesions could be intoxication of the pericipets and endothelial cells of the retinal capillaries by an accumulation of sorbitol and fructose in this region. Additionally, the hyperglycemia suppresses the functioning of the retinal blood flow feed back system. An increase in systemic blood pressure will therefore be transmitted directly to the damaged capillary bed. In type II diabetes (NID), worsening of the diabetic retinopathy correlates with elevation of the systolic blood pressure. In type I diabetes (ID), worsening of the diabetic retinopathy correlates with an elevated diastolic blood pressure. A diastolic pressure of less than 74 mm Hg is a statistically significant protective factor against the worsening of type I diabetic retinopathy.

Blood Pressure↗
PubMed1991

[Trachoma and the conjunctival impression test].

The Transferred Conjunctival Impression test (test d'Impression Conjonctivale Transférée) is a simple, sensitive and non-invasive method enabling populations at risk from Xerophthalmia to be identified. Nevertheless, the results of the test do seem to be influenced by the conjunctival pathology, trachomatous in particular. It appears that conjunctival deficit is noticeably more frequent in trachomatous than non-trachomatous subjects. The trial, involving a random sample of 450, four- to six-year-old children living in the Sahelian zone, enabled us to confirm and quantify this relation. In terms of relative risk, with age, place of residence and nutritional state all being equal, the rate of abnormal TCI tests was 1.7 times higher in trachomatous than non-trachomatous children. Using the Transferred Conjunctival Impression test is thus especially indicated in zones with a low prevalence of trachoma. When high, an eye examination must be carried out during the trial in order to present the results in two categories: trachomatous and non-trachomatous. Failing this, estimates may be obtained using the formulae put forward by the authors.

Alcian Blue↗
PubMed1991

[Irvine-Gass syndrome or cystoid macular edema due to aphakia].

Angiographically confirmed cystoid macula edema occurs in 8% of aphakic patients and 3% of these patients will suffer permanent reduction of visual acuity. This is apparently due to inflammatory reactions and to alterations of the vitreo-macular interface. Intracapsular cataract extraction has a higher incidence of angiographically confirmed CME clinical or persistent than extracapsular extraction. YAG-laser capsulotomy does not have any significant risk of CME. At present, there is no definitive clinically effective treatment.

Aphakia, Postcataract↗
PubMed1990

[A case of post-traumatic occlusion of the central retinal artery].

We report a case of central retinal artery occlusion following a minor ocular injury. The occlusions are an uncommon but well following some surgical operations on the eyeball, the eyelids or the nose. They probably result from an arterial spasm which trigger mechanisms are not very well known.

Adult↗
PubMedDate not supplied

Comparison of artificial membrane feeding with direct skin feeding to estimate infectiousness of Plasmodium falciparum gametocyte carriers to mosquitoes.

Human infectiousness to mosquitoes can be estimated by 2 tests: direct feeding on the skin and membrane feeding on venous blood. To validate the membrane feeding assay, the infectiousness of Plasmodium falciparum gametocyte carriers to Anopheles gambiae was estimated by these 2 methods in the same individuals in a rural area of Cameroon. Results from 37 experiments showed that direct feeding gave significantly higher infection rates than membrane feeding. We observed an average of 19.4% infected mosquitoes by direct feeding compared with 12.1% by membrane feeding, and a mean oocyst load of 5.63 by direct feeding compared with 2.65 by membrane feeding. However, there was a very good concordance between the 2 tests: 84.3% with the Kappa test on percentages of infected mosquitoes and 98.7% with the interclass correlation coefficient on oocyst loads. In addition, we found a good linear correlation between the 2 methods.

Animals↗
PubMedDate not supplied

Estimation of malaria transmission from humans to mosquitoes in two neighbouring villages in south Cameroon: evaluation and comparison of several indices.

Malaria transmission from humans to mosquitoes was assessed in two neighbouring villages in a rural area near Yaoundé, Cameroon during high and low transmission seasons during 1998-2000, using several indices previously evaluated in different areas endemic for malaria but never directly compared. These indices were estimated from human parasitological data and mosquito infection rates and, for each individual, thick blood films were prepared at the same time as experimental infection of laboratory-bred mosquitoes. Among the 685 volunteers examined, the prevalence of Plasmodium falciparum gametocyte carriers was 16%, and 8% of individuals were able to infect mosquitoes. The percentage of mosquitoes that became infected by feeding on the infectious individuals was 21%. Children aged < 10 years contributed to about 75% of the infectious reservoir, although they constituted only 35% of the total population. Differences were found between the transmission seasons and the villages, and varied according to the index examined. Although there were more infectious individuals in one of the two villages, they were less infectious than those in the other village during the high transmission season. Comparative analysis of the transmission indices suggests the existence of functioning transmission-blocking immunity in one of the villages, which until now has been only hypothetically considered to play a role in malaria transmission in a natural setting. The epidemiological value of all the indices used and their accuracy in estimating the human infectious reservoir and its natural or induced variations are discussed.

Adolescent↗