Magnetic resonance imaging findings of the proximal metacarpus in Quarter Horses used for cutting: Retrospective analysis of 32 horses 2009-2012.

BACKGROUND: Injury to the proximal suspensory ligament is a common cause of lameness in cutting horses. Radiographic and ultrasonographic imaging of lesions responsible for lameness can provide ambiguous results. MRI provides the most comprehensive diagnostic imaging evaluation of lesions specifically affecting cutting horses. OBJECTIVES: To describe the distribution and severity of bone and soft tissue lesions present in the proximal metacarpus of Quarter Horse cutting horses and to assess the impact of these lesions on return to competition. STUDY DESIGN: Retrospective case series. METHODS: Retrospective analysis of 32 cutting horses referred for MRI of the proximal metacarpus between 2009 and 2012 with a 2-year follow-up period. MRI studies were evaluated by a board-certified veterinary radiologist; the severity of lesions was graded from 0 (absent) to 3 (severe). RESULTS: A total of 20 right and 24 left forelimbs (12 bilateral studies) of 32 horses were evaluated. The most common findings were: third metacarpal (McIII) sclerosis at the proximal suspensory ligament (PSL) origin (42/44), McIII resorption at the PSL origin (32/44), PSL dorsal margin fibre irregularity (30/44) and McIII bone contusion (22/39). Of the 30 horses, 22 horses successfully returned to competition, irrespective of severity of injury. Strong correlation exists between the degree of resorption in the palmar cortex of proximal McIII, degree of McIII sclerosis and severity of dorsal margin fibre irregularity. MAIN LIMITATIONS: Statistical significance was limited by small study population. Further analysis of prognosis was limited by availability of comprehensive medical records. CONCLUSIONS: Cutting horses with proximal metacarpal pain have significant pathological change within the proximal suspensory ligament and its enthesis on the palmar cortex of McIII. Severity of lesions and degree of lameness at the time of diagnosis does not influence return to performance. Accurate diagnosis of proximal metacarpal lesions based on MRI offers clinicians the capacity to select treatment protocols targeted to each disease process.

Effects of thyrotrophin-releasing hormone on plasma catecholamine levels in acromegalics.

Plasma catecholamines assayed by a double isotope radio enzymatic method were studied in the basal state and during a thyrotrophin-releasing hormone (TRH)-test in 7 acromegalics, divided into 2 groups: active and non-active acromegalics, according to clinical and biological criteria. Basal plasma norepinephrine levels were significantly increased in the active group 648 +/- 22 pg/ml (P less than 0.001) and were in the normal range in the non-active group 439 +/- 26 pg/ml. Basal plasma epinephrine values were not significantly different in the 2 groups 59 +/- 15 pg/ml vs 34 +/- 7 pg/ml. During a TRH-test, norepinephrine levels remained elevated (P less than 0.001) in the active group, and the difference between the 2 groups was enhanced during the test. On the other hand the 2 patients who responded to TRH demonstrated an increase of norepinephrine levels. Our results suggest that TRH may stimulate norepinephrine release in acromegalics with an active response to TRH.

Determination of a virtually non-carcinogenic dose.

The various mathematical models of the dose-response relationship are briefly reviewed and it is concluded that the Weibull and gamma-multihit models are at present the best ones. They permit the computation of a 'virtually safe dose', for which the carcinogenic risk to man is reasonably negligible, but because of the unknown mechanism of the background response, the models should be used in a mixed form. A modified Crouch and Wilson approach is proposed to evaluate the risk from an actual environmental dose. This takes into account the various uncertainties in risk computations, and results in the application of a safety factor when extrapolating from animals to man.

Dietary no-effect level of a dithiocarbamate fungicide, thiram, evaluated from measurement data on rats. I. Choice of the model of the dose-response relationship.

Rats were fed diets containing various amounts of added thiram, a dithiocarbamate fungicide. As thiram feeding resulted in decreased appetite, control rats not receiving thiram were pair-fed to the experimental ones. On d 30 of the experiment the animals were weighed and sacrificed, and the following organs were weighed: liver, kidneys, heart, epididymal and perirenal fat pads, testes, seminal vesicles, tibia, adrenals, and thyroid. Liver concentrations of lactate, pyruvate, beta-hydroxybutyrate, acetoacetate, ATP, and ADP were determined by enzymatic-spectrofluorimetric assay. For each parameter studied and each thiram dosage, values for treated rats were compared to those for control rats and the probability under the null hypothesis was computed. These probabilities were transformed into probits, logits, or "Weibull transforms" and plotted against the logarithms of the respective doses. Models were fitted to the data by linear regression techniques. Finally, the dose inducing the least significant difference (LSD dose), and the dose considered "safe" at P = 0.95, 0.99, and 0.999 were calculated. Significant pesticide-induced changes in the following parameters were found: food intake; weights of the whole body, kidneys, epididymal and perirenal fat pads, testes, and seminal vesicles; and liver beta-hydroxybutyrate/acetoacetate and lactate/pyruvate ratios. As the models did not differ in fit to the experimental data or in computed LSD doses, they were discriminated on the grounds of their underlying theoretical assumptions and their prediction of safe doses in a long-term study. The log-probit model was rejected for the former reason, and it was shown that the Weibull model foresees a nonnegligible risk of change, with thiram feeding at low doses, for too many parameters. The analysis resulted in the selection of the log-probit model for further use. Weight of fatty tissues was the most sensitive parameter and, using the log-probit model, the predicted no-effect dose at the 95 percent confidence level was 38 ppm thiram in the diet.

[Preservation of bread and pastry products in a controlled atmosphere]. / Conservation des produits de boulangerie et de patisserie sous atmosphère controlée.

Industrial soft pastries and the various breads are cereals products containing a humidity which is favorable to the development of mouldiness. Different or various methods of conservation has been attempted. One interesting approach to the problem is packaging in controlled atmosphere. It requires adequate machinery and suitable conditioning materials. Jardry-Buquet and Hayssen's machines are rapidly described as well as some of the packing film used for making air-tight bags. Bad results were observed with nitrogen, argon and a mixture of nitrogen-carbon dioxide. The satisfactory results obtained with the nitrous oxide for cakes (especially fruit-cakes) and for the bread with a mixture of ethylene oxide-carbon dioxide are: a good conservation for a period of 4 to 6 months in both cases. Organoleptic qualities of the products are not significantly diminished after eight weeks of preservation. The gases contained on the bags are analysed at different periods and the progressive disappearance of the nitrous oxide as well as the athylene dioxide was measured. The compounds derivated from these gases were researched on different extracts. No derivatives of the nitrous oxide were observed. From the ethylene oxide, the derivatives found in the bread are diethylene glycol and 2-chloroethanol; their concentrations are respectively 100 and 300 ppm in the case of 85 : 15 mixture, but decrease to a mere trace and 45 ppm in the case of 98 : 2 mixture. The measure of humidity, of peroxides and of the staleness of crumb are favourable for a good conservation.

[Various toxic effects of nitrates and nitrites]. / Effets toxiques divers des nitrates et des nitrites.

The main features of the long-term toxicity of nitrates and/or nitrites in man and experimental animals are reviewed; the possible formation of carcinogenic nitrosamines is dealt with in another paper of this series. It appears that the allowable daily intake of nitrates and nitrites for the healthy adult man has been evaluated chiefly from the no-effect levels in rats. First, the no-effect levels in rats are questionable, since some experiments have pointed out adverse effects of nitrates and nitrites with dosages near, or lower than, the so-called no-effect levels. Second, there is a risk that the allowable daily intake is outpassed in the diet of a man. Third, nutritional conditions, such as the vitamin A or C, or the iodine content of the diet, as well as other factors which are discussed, might alter theno-effect levels. From the cell metabolism viewpoint, nitrites are inhibitors of oxidative phosphorylation and of microsomal enzymes. Our present lack of knowledge does not yet allow us to explain the long-term toxicity of nitrates and nitrites in terms of cell metabolic disturbances.

[Diminution of activity of liver microsomal oxygenase in a rat fed with a diet with added zineb]. / Diminution d'activité des oxygénases microsomales du foie chez le rat nourri avec un régime additionné de zinébe

Young Wistar CF male rats were fed with diets containing 6,15,60,600,3600 p.p.m of zineb (a zinc thiocarbamate used as fongicide). Four weeks after the beginning of the treatment, a calcic precipitation method is used for obtaining a preparation of liver microsomes from these animals. The microsomes are then used for measuring the activity of both aminophenazone demethylase and aniline hydroxylase as well as the liver concentration of cyt. P 450 and cyt. b5. The weight growth was reduced by the highest dose of zineb, which corresponds to about a daily intake of twentieth of the LD 50 per os. The fongicide brings down the activity of the microsomal monoxygenases and reduces the P 450 quantity. The lessening of the aminophenazone demethylation is apparent starting from a dose between 60 and 600 p.p.m...

[Effect of methyl parathion and zineb administration on the activity of some hepatic enzymes in rats]. / Influence de l'administration de parathion-méthyle ou de zinèbe sur l'activité de quelques enzymes hépatiques chez le rat

Male albinos rats were fed diets containing parathion-methyl or Zineb so that the average daily intake is 1/10 or 1/20 lethal dose 50, for a period of 4 or 8 weeks. The activity of hepatic microsomal enzymes, namely :aminopyrine N-demethylase, BHT oxidase, aniline hydroxylase, Butter Yellow & Amaranth reductases, NADPH-cyt. c reductase, G6P phosphatase, were measured. The activities of G6P & 6PG deshydrogenases were also determined. With the application of the parathion-methyl doses, the only effect showed is the lowering of the microsomal protein concentration.