Search

Le parasite Varroa destructor provoque depuis plus de 30 ans la perte de nombreuses colonies à travers le monde. L’utilisation d’acaricides de synthèse s’est avérée inefficace au Canada et ailleurs dans le monde à la suite de la sélection de varroas résistants. Dans ce contexte, il est devenu impératif de trouver de nouveaux moyens pour contrôler cette peste apicole. Ce travail original de recherche a pour but de déterminer les paramètres fondamentaux d’une lutte intégrée contre la varroase fondée sur l’utilisation périodique de différents pesticides organiques (l’acide oxalique, l’acide formique et le thymol) associée à des seuils d’interventions. Les seuils d’intervention ont été déterminés à l’aide de régressions linéaires entre les taux de parasitisme par V. destructor et la formance zootechnique des colonies d’abeilles mellifères (production de miel et force des colonies). Un total de 154 colonies d’abeilles du Centre de recherche en sciences animales de Deschambault (CRSAD) ont été suivies de septembre 2005 à septembre 2006. Les seuils calculés et proposés à la suite de cette recherche sont de 2 varroas par jour (chute naturelle) au début mai, 10 varroas par jour à la fin juillet et de 9 varroas par jour au début septembre. L’efficacité des traitements organiques avec l’acide oxalique (AO), l’acide formique (AF) et le thymol a été vérifiée en mai (avant la première miellée) en juillet (entre deux miellées), en septembre (après la miellée et pendant le nourrissage des colonies) et en novembre (avant l’hivernage). L’acide oxalique a été appliqué en utilisant la méthode d’égouttement (4% d’AO p/v dans un sirop de sucrose 1 :1 p/v). L’acide formique a été appliquée sous forme de MiteAwayII™ (tampon commercial imbibé d’AF 65% v/v placé sur le dessus des cadres à couvain), Mitewipe (tampons Dri-Loc™ 10/15cm imbibés de 35 mL d’AF 65% v/v placés sur le dessus des cadres à couvain) ou Flash (AF 65% coulé directement sur le plateau inférieur d’une colonie, 2 mL par cadre avec abeilles). Le thymol a été appliqué sous forme d’Apiguard™ (gélose contenant 25% de thymol p/v placée sur le dessus des cadres à couvain). Les essais d’efficacité ont été réalisés de 2006 à 2008 sur un total de 170 colonies (98 appartenant au CRSAD et 72 appartenant au privé). Les résultats montrent que les traitements de printemps testés ont une faible efficacité pour le contrôle des varroas qui sont en pleine croissance durant cette période. Un traitement avec l’AF à la mi-été permet de réduire les taux de parasites sous le seuil en septembre mais il y a risque de contaminer la récolte de miel avec des résidus d’AF. Les traitements en septembre avec le MiteAwayII™ suivis par un traitement à l’acide oxalique en novembre (5 mL par égouttement entre chaque cadre avec abeilles, 4% d’AO p/v dans un sirop de sucrose 1 :1 p/v) sont les plus efficaces : ils réduisent les niveaux de varroase sous le seuil de 2 varroas par jour au printemps. Nos résultats montrent également que les traitements réalisés tôt en septembre sont plus efficaces et produisent des colonies plus fortes au printemps comparativement à un traitement réalisé un mois plus tard en octobre. En conclusion, ce travail de recherche démontre qu’il est possible de contenir le développement de la varroase dans les ruchers au Québec en utilisant une méthode de lutte intégrée basée sur une combinaison d’applications d’acaricides organiques associée à des seuils d’intervention., For nearly 30 years, Varroa destructor has been responsible for the loss of many honey bee colonies around the world. The continued use of synthetic acaricides has resulted in their reduced efficacy against this pest in Canada and in other countries because of the selection of resistant mite populations. With this situation still present, it has become of utmost importance to develop efficient methods to control this apicultural pest. The major goal of this original work is to determine the fundamental parameters underlying the use of an integrated pest management (IPM) strategy against the varroa mite. The IPM strategy developed in this research is based on the periodic use of organic pesticides (oxalic acid, formic acid and thymol) and treatment threshold. Treatment thresholds were determined from linear regressions between the varroa mite levels and the zootechnical performances (honey production and colony strength) of honey bee colonies. A total of 154 honey bee colonies from the livestock of the “Centre de recherche en sciences animales de Deschambault” (CRSAD) were monitored from September 2005 to September 2006. Based on our findings, we propose economic treatment thresholds for three periods in the year: early May, late July and early September that are respectively 2, 10 and 9 varroa mites per day. Efficacy of the various organic treatments: formic acid (FA), oxalic acid (OA) and thymol was evaluated in May (before the first honey flow), in July between two honey flows, in September (after the honey flow and before the fall feeding of colonies) and in November (before wintering). OA was applied using the trickling method (4% OA w/v in a sucrose syrup 1:1 w/v). FA was applied using MiteAwayII™ (pads imbedded with FA 65% v/v placed on top of brood frames), Mitewipe (Dri-Loc™ pads 10/15cm imbedded with 35 mL FA 65% v/v placed on top of brood frames), Flash (FA 65% poured directly on the bottom board of colonies, 2 mL per frame with bees). Thymol was applied using Apiguard™ (gel with 25% de thymol w/v placed on top of the brood frames). Efficacy trials were realised from 2006 to 2008 on a total of 170 colonies (98 from the CRSAD and 72 owned by a commercial beekeeper). Results show that treatments applied in spring give low efficacy on reducing varroa mite populations that are in full growth at this time because of large amounts of brood available for mite reproduction. Application of a FA treatment in mid-summer offers the opportunity to reduce mite populations at the 11 mites per day September threshold but FA summer application is accompanied by a risk of incorporating residues in the harvested honey. Application of MiteAwayII™ in September followed by an oxalic acid treatment in November (trickling method 4% OA w/v in a sucrose syrup 1 :1 w/v, 5 mL between frames with bees) gave the best efficacy results: varroa mite levels are reduced below the 2 mites per day spring threshold. Our results also show that an early September management strategy of colonies for winter preparation (varroa treatment and fall feeding) gives greater varroa control, higher colony winter survival and stronger colonies in spring when compared to a later treatment in October. In conclusion, this work shows that varroa mite control in honey bee colonies in Québec is possible by using an integrated pest management strategy based on the application of a combination of organic acaricides in association with treatment thresholds.

The purpose of this study is to evaluate the effect of fluid and diet restriction in fasting on biochemical factors of stone formation. Our study concernes 90 patients divided in three groups: healthy fasting patient (GI), healthy non fasting patient (G2) and non fasting patient with calcium lithiasis (G3). The promotors (oxalate, calcium, uric acid, phosphates) and inhibitors (citrate, magnesium) are statistically significant between G1, G2 and G3, G2. Supersaturation of urine with oxalate, uric acid and brushite are the same for (G1) and (G3) and higher than (G2). Crystalluria is more important in lithiasis subjects compared with healthy non fasting patients (58% vs 11,4%). Oxalate monohydrate (Whewellite) and uric crystal don't exist in the healthy non fasting people but reached 4% and 12% respectively in the lithiasis patient. The crystalluria profil is the same in the heathy fasting patients and calcium lithiasis patients. However healthy patients have equilibria between promotors and inhibitors of crystal formation which minimize the risk of crystalluria and subsequent stone formation.

In the microelectronic industry using the dasmacene process, dendritic growth is observed on some parts of the circuits in some conditions during the post chemical mechanical polishing cleaning step.; Lors du procédé dasmacène utilisé pour le dépôt du cuivre dans l'industrie microélectronique, un phénomène de croissance dendritique peut-être observé sur certains plots de cuivre, dans des conditions critiques, pendant le nettoyage qui suit le polissage mécano-chimique du cuivre.

The prevalence of urolithiasis is higher in patients with cystic fibrosis than in the normal population. We report on a case of a 12-year-old child with cystic fibrosis who presented flank pain which revealed a calcium oxalate urolithiasis. Evolution was satisfactory with pharmacological and dietary treatment. The principal mechanisms of lithogenesis in patients with cystic fibrosis are described and preventive treatment is discussed.

Pulmonary oxalosis is a very rare pseudotumoral lesion; it is often secondary to an aspergillus infection. Oxalic acid (C(2)H(2)O(4)) is a mycotoxin released by Aspergillus niger and sometimes by several other fungi, including A flavus and A fumigatus. We report a case of a 69 year old man, with previous history of pulmonary tuberculosis, followed for recurrent hemoptysis. On the chest radiography, the right upper lobe lung showed a cavitary lesion with thick and irregular walls and a dense material that suggested a pulmonary aspergilloma. Microscopically, it was a pulmonary oxalosis associated with chronic necrotising pulmonary aspergillosis. Our aim is to discuss the epidemiological characteristics, the diagnosis and the histogenesis of this unusual lesion.

Primary hyperoxalurias are inborn errors of metabolism with recessive autosomal transmission. Type 1 is due to the deficiency of the hepatic-specific peroxisomal enzyme alanine: glyoxylate aminotransferase, and type 2 to that of the glyoxylate reductase/D-glycerate dehydrogenase, present in the cytosol of hepatocytes and leucocytes. Type 3 is due to increased intestinal absorption of oxalate of unknown pathophysiology. In the 3 types, increased oxalate load may lead to systemic oxalosis when glomerular filtration rate decreases below 30 ml/min/1.73 m2, calcium oxalate saturation occurring in plasma when oxalate level approximates 50 mumol/l. High fluid intake and long-term co-administration of pyridoxine and orthophosphate could perhaps efficiently prevent renal failure in a majority of patients. However, combined liver-kidney transplantation presently constitutes the most adequate therapy of end-stage renal failure in type 1 and perhaps in type 2 hyperoxaluria.

A preliminary diagnosis of the disease responsible for the stones is essential to allow appropriate medical treatment of renal stones. In this paper, the authors describe their diagnostic and treatment protocol based on computer-assisted urinary metabolic analysis. 413 subjects, divided into four groups, were prospectively evaluated to calculate their specificity, sensitivity, reproducibility and efficacy and to demonstrate the usefulness of this protocol.

Oxalate lithiasis was induced in control rats and rats previously given a vitamin A supplement for one week at the dose for 200 UI/d/kg body weight. Oxalate and calcium deposits in renal tissue measured 24 hours after the induction of lithiasis were found to be significantly lower in the vitamin A supplemented rats (p0.001 and p0.01) respectively). Renal function in these animals was also improved as compared with controls (p0.05). However, when vitamin A supplements were given for the same period and at the same dose, but after the induction of oxalate lithiasis, no difference regarding oxalate and calcium deposits was found between the two groups of animals. The same applied to renal function, which showed no improvement in the supplemented animals as compared with controls. These results suggest that vitamin A supplements have an inhibitory effect on lithogenesis but probably no litholytic action as such. The effect of vitamin A is probably related to its action on tubular cellular repair or an inhibitory effect on necrosis of these cells.

We have recently suggested that vitamin A could protect against experimental lithiasis by repairing tubular membrane cells or protection against membrane damage caused by free radicals generated during experimental lithiasis. Although vitamin E treatment demonstrated no beneficial effect on stone formation, it promoted the repair mechanism by vitamin A during experimental lithiasis and by supported the hypothesis that oxalate crystals may be destructive to renal epithelium because they are large and irregular.

Administration of ascorbic acid, at 150 mg/100 ml of water intake, for one month, induced hyperoxaluria in the rats (P less than 0.001) and decreased citraturia (P less than 0.001) magnesuria (P less than 0.001) and pyrophosphaturia (P less than 0.01). The same disorders were observed when the dose administered was 300 mg/100 ml, excepted that oxaluria was considerably enhanced in this group. Despite these variations, renal deposits were not observed, even in the animals receiving 300 mg of ascorbate/100 ml of water intake. This protection was due to decreased calcium excretion (P less than 0.01 in two groups) and probably to acidification of the urine.

This paper review the effects of orthophosphoric acid and other acidic agents on dental enamel. The effects of other treatments such as proteolytic agents or of mixture able to remove the lipids are also described. Specific problems are related to the dentine treatment. Acids and chelators should be avoided, because of the dentine tubules, the odontoblasts and pulp. We review also the problem of the smear layer, the surface of the carious dentine and the consequences for dental treatment. Researches which are still in progress are reported including the use of enzymes and alcali gels submitted to feeble electrolysis, this latter being able to prepare dentine, cementum and bone surfaces in order to increase the adhesion of biomaterials.

Administration of high doses of vitamin D3 (2,600 IU/100 ml of drinking water) to adult rats, for one month, significantly altered renal function (P less than 0.01) and enhanced renal accumulation of oxalate (71.44 x 18.82 micrograms/g of tissue in treated rats vs 38.87 +/- 11.96 micrograms/g in untreated rats; P less than 0.001), phosphate (1.388 +/- 188 micrograms/g in treated rats vs 870 +/- 171 micrograms/g in untreated rats; P less than 0.01) and calcium (477 +/- 107 micrograms/g in treated rats vs 326 +/- 104 micrograms/g in untreated rats; P less than 0.01). Urinary analyses of principal promotors and inhibitors of lithogenesis revealed high calcium excretion (1,576 +/- 0.419 mg/24 hr in treated rats vs 0.969 +/- 0.214 mg/24 hr in untreated rats; p less than 0.01) and decreased magnesium excretion (0.330 +/- 0.135 mg/24 hr in treated rats vs 0.910 +/- 0.168 mg/24 hr in untreated rats; p less than 0.001). Microscopic calcium deposits were found in the medulla, especially in renal papilla. These results suggested that vitamin D3, when administered at high doses for a long time, may induce nephrocalcinosis and alter renal function.