Hyperkalemic periodic paralysis and the adult muscle sodium channel alpha-subunit gene

Hyperkalemic periodic paralysis (HYPP) is an autosomal dominant disorder characterized by episodes of muscle weakness due to depolarization of the muscle cell membrane associated with elevated serum potassium. Electrophysiological studies have implicated the adult muscle sodium channel. Here, portions of the adult muscle sodium channel alpha-subunit gene were cloned and mapped near the human growth hormone locus (GH1) on chromosome 17. In a large pedigree displaying HYPP with myotonia, these two loci showed tight linkage to the genetic defect with no recombinants detected. Thus, it is likely that the sodium channel alpha-subunit gene contains the HYPP mutation.     

Uncommon associations in target resistance among French populations of Myzus persicae from oilseed rape crops

Within the framework of a molecular exploration of target resistance in populations of Myzus persicae on oilseed rapes in France, (1) the S431F mutation (coding gene ace2), although previously reckoned to be rare, revealed to be frequent, (2) M918L (phenotypically characterised) and L932F (both on para) were found for the first time in M. persicae, and (3) a linkage was revealed between M918L and S431F. While until recently populations developing on French oilseed rapes were dominated by genotypes possessing pyrethroid target resistance and esterase overproduction, to date a different type of dominating genotype, equipped with carbamate and pyrethroid target resistance, seems to be invading such fields.     

Antioxidant properties of trans-epsilon-viniferin as compared to stilbene derivatives in aqueous and nonaqueous media

trans-Epsilon-viniferin, the dimer of resveratrol, extracted from Vitis vinifera, has been evaluated for its antioxidant capacity. Its properties have been compared to those of resveratrol and synthetic stilbenic derivatives (4-hydroxystilbene, 4,4'-dihydroxystilbene, 3,5-dihydroxystilbene, and trimethylresveratrol), in regard to their liposolubility using two media with different polarity. The bleaching of beta-carotene by lipoperoxyl (LOO.) radicals in an oil/water (O/W) emulsion and the scavenging of superoxide anions (O(-)(2) in dimethyl sulfoxide (DMSO) using 5,5-dimethyl-1-pyrroline-N-oxide as a spin trap were followed using UV-visible and electron paramagnetic resonance, respectively. Epsilon-viniferin exhibits the best antioxidant capacity in the DMSO/O(-)(2) polar system (IC(50) = 0.14 mM) while 4,4'-dihydroxystilbene presents the highest antioxidant capacity in the O/W/LOO. system (inhibition of beta-carotene bleaching, 82%). Partition coefficients and kinetics of partition between 1-octanol and water were measured to discuss the antioxidant efficiency of the compounds in relation with their chemical structure.     

Comparisons of endocrinological and testis parameters in 18-month-old Ile de France and Romanov rams

Endocrinological and testis parameters of adult 18-month-old Ile de France (IF) and Romanov (Ro) rams were compared during sexual season. Testis weights, total volumes of intertubular tissue, and of blood and lymph vessels, total seminiferous tubule length, rete testis flow rate and daily production of germ cells were significantly higher in IF than in Ro rams. These variations originated from differences in Sertoli cell numbers, which were established before puberty. When daily productions of germ cells, of ABP or of RTF were expressed per Sertoli cell, they were higher in Ro than in IF rams. Quality of spermatids, as measured by their cellular size prior to elongation, was lower in Ro than in IF. The number of FSH-binding sites per Sertoli did not differ between the two breeds but FSH plasma levels were higher in Ro than in IF rams. Total numbers of Leydig cells per testis, their individual size or their LH-binding capacity did not differ significantly between the two breeds. However, the ratio of mean testosterone upon mean LH plasma levels were greater in Ro than in IF rams while both breeds had identical LH mean plasma levels.     

Studies on vitamin E and selenium deficiency in young pigs. III. Effect on kinetics of erythrocyte production and destruction.

The effect of vitamin E and/or selenium deficiency on the kinetics of erythrocyte production and destruction has been investigated in swine. The plasma iron turnover rate, 59Fe incorporation into newly formed red cells as well as the 51Cr apparent red cell half-life, were not found to be significantly affected by either vitamin E deficiency, selenium deficiency or deficiency of both, as compared to replete animals. The results of this study suggest that vitamin E is not a limiting factor for normal erythropoiesis in young growing pigs. Erythropoiesis appeared, however, to be slightly decreased in selenium deficient pigs and will need to be further investigated.     

Systemic lupus erythematosus in a colony of dogs

A colony of dogs was obtained by the mating of a female German Shepherd Dog crossbred and a male Belgian Shepherd Dog crossbred, both with systemic lupus erythematosus (SLE). The colony also contained 16 dogs representing F1, F2, and F3 generations. Ten colony dogs had circulating antinuclear antibodies, and 5 of the 10 had clinical signs of SLE. Two F3-generation females had signs of severe SLE. Two dogs had antibodies to extractable nuclear antigen, notably 1 dog had antibodies to Smith (Sm) antigen and 1 had antibodies to Sjogren syndrome A (SSA) antigen. Thymulin (serum thymic factor associated with zinc) titers were generally low in the descendants, but fluctuations were detected within the same dog. In vitro response of lymphocytes from these colony dogs to concanavalin A was maximal for lower mitogenic concentrations, compared with response of lymphocytes from 10 healthy dogs. The suppressive lymphocyte activity in 6 autoimmune colony dogs was diminished in comparison with the activity in 5 nonautoimmune colony dogs and 6 healthy dogs.     

Studies on vitamin E and selenium deficiency in young pigs. II. The hydrogen peroxide hemolysis test and the measure of red cell lipid peroxides as indices of vitamin E and selenium status.

The usefulness of the hydrogen peroxide hemolysis test and the measure of red cell lipid peroxides as indices of vitamin E and selenium deficiency in swine has been evaluated. Results indicated that although the hydrogen peroxide hemolysis test may be of some indication of the vitamin E status, it is not a reliable index of vitamin E deficiency in swine, at least on an individual basis. In contrast, the measure of red cell lipid peroxides can be considered a reliable test for vitamin E deficiency in swine. The hydrogen peroxide hemolysis test and the red cell lipid peroxides were not significantly affected by selenium deficiency.     

Pharmaceutical and nutraceutical management of canine osteoarthritis: present and future perspectives

Osteoarthritis (OA) is one of the most common chronic musculoskeletal diseases and causes of lameness in the dogs. The osteoarthritic disease process involves the entire synovial joint, encompassing the synovium, cartilage and underlying bone. Joint failure results from an abnormal mechanical strain causing damage to normal tissue or failure of pathologically impaired articular cartilage and bone under the influence of normal physiological strain or a combination of both. In both cases, the end point is cartilage loss and joint impairment. Osteoarthritic chondrocytes show an altered phenotype characterised by an excess production of catabolic factors, including metalloproteinases and reactive oxygen species. These factors constitute potential therapeutic targets and some new drugs and nutraceuticals have been proposed to promote the return to homeostasis. Until now, the therapeutic management of OA in dogs has been dominated by nonsteroidal anti-inflammatory drugs, but some new compounds, including diacerhein, with potential structure-modifying effects, are already used to treat OA in humans and could be helpful to manage OA in the dog. In addition, novel nutraceuticals, such as avocado/soybean unsaponifiable substances, have shown symptomatic effects in knee OA in humans, and could offer an alternative to prevent OA progression. This paper provides an overview of recent discoveries in the pathophysiology and in the therapeutic management of osteoarthritis in dogs.