Genetic risk factors for insidious equine recurrent uveitis in Appaloosa horses.

Appaloosa horses are predisposed to equine recurrent uveitis (ERU), an immune-mediated disease characterized by recurring inflammation of the uveal tract in the eye, which is the leading cause of blindness in horses. Nine genetic markers from the ECA1 region responsible for the spotted coat color of Appaloosa horses, and 13 microsatellites spanning the equine major histocompatibility complex (ELA) on ECA20, were evaluated for association with ERU in a group of 53 Appaloosa ERU cases and 43 healthy Appaloosa controls. Three markers were significantly associated (corrected P-value <0.05): a SNP within intron 11 of the TRPM1 gene on ECA1, an ELA class I microsatellite located near the boundary of the ELA class III and class II regions and an ELA class II microsatellite located in intron 1 of the DRA gene. Association between these three genetic markers and the ERU phenotype was confirmed in a second population of 24 insidious ERU Appaloosa cases and 16 Appaloosa controls. The relative odds of being an ERU case for each allele of these three markers were estimated by fitting a logistic mixed model with each of the associated markers independently and with all three markers simultaneously. The risk model using these markers classified ~80% of ERU cases and 75% of controls in the second population as moderate or high risk, and low risk respectively. Future studies to refine the associations at ECA1 and ELA loci and identify functional variants could uncover alleles conferring susceptibility to ERU in Appaloosa horses.

Estimated prevalence of the Type 1 Polysaccharide Storage Myopathy mutation in selected North American and European breeds.

The GYS1 gene mutation that is causative of Type 1 Polysaccharide Storage Myopathy (PSSM) has been identified in more than 20 breeds of horses. However, the GYS1 mutation frequency or Type 1 PSSM prevalence within any given breed is unknown. The purpose of this study was to determine the frequency of the GYS1 mutation and prevalence of genetic susceptibility to Type 1 PSSM in selected breeds from Europe and North America. The GYS1 mutation was detected in 11 breeds, including, in order of increasing allele frequency, Shires, Morgans, Appaloosas, Quarter Horses, Paints, Exmoor Ponies, Saxon-Thuringian Coldbloods, South German Coldbloods, Belgians, Rhenish German Coldbloods and Percherons. The prevalence of genetic susceptibility to Type 1 PSSM in these breeds varied from 0.5% to 62.4%. The GYS1 mutation was not found in the sampled Thoroughbreds, Akhal-Tekes, Connemaras, Clydesdales, Norwegian Fjords, Welsh Ponies, Icelandics, Schleswig Coldbloods or Hanoverians, but failure to detect the mutation does not guarantee its absence. This knowledge will help breed associations determine whether they should screen for the GYS1 mutation and will alert veterinarians to a possible differential diagnosis for muscle pain, rhabdomyolysis or gait abnormalities.

A 4,103 marker integrated physical and comparative map of the horse genome.

A comprehensive second-generation whole genome radiation hybrid (RH II), cytogenetic and comparative map of the horse genome (2n = 64) has been developed using the 5000rad horse x hamster radiation hybrid panel and fluorescence in situ hybridization (FISH). The map contains 4,103 markers (3,816 RH; 1,144 FISH) assigned to all 31 pairs of autosomes and the X chromosome. The RH maps of individual chromosomes are anchored and oriented using 857 cytogenetic markers. The overall resolution of the map is one marker per 775 kilobase pairs (kb), which represents a more than five-fold improvement over the first-generation map. The RH II incorporates 920 markers shared jointly with the two recently reported meiotic maps. Consequently the two maps were aligned with the RH II maps of individual autosomes and the X chromosome. Additionally, a comparative map of the horse genome was generated by connecting 1,904 loci on the horse map with genome sequences available for eight diverse vertebrates to highlight regions of evolutionarily conserved syntenies, linkages, and chromosomal breakpoints. The integrated map thus obtained presents the most comprehensive information on the physical and comparative organization of the equine genome and will assist future assemblies of whole genome BAC fingerprint maps and the genome sequence. It will also serve as a tool to identify genes governing health, disease and performance traits in horses and assist us in understanding the evolution of the equine genome in relation to other species.

Allele frequency and likely impact of the glycogen branching enzyme deficiency gene in Quarter Horse and Paint Horse populations.

Glycogen Branching Enzyme Deficiency (GBED), a fatal condition recently identified in fetuses and neonatal foals of the Quarter Horse and Paint Horse lineages, is caused by a nonsense mutation in codon 34 of the GBE1 gene, which prevents the synthesis of a functional GBE protein and severely disrupts glycogen metabolism. The aims of this project were to determine the mutant GBE1 allele frequency in random samples from the major relevant horse breeds, as well as the frequency with which GBED is associated with abortion and early neonatal death using the tissue archives from veterinary diagnostic laboratories. The mutant GBE1 allele frequency in registered Quarter Horse, Paint Horse, and Thoroughbred populations was 0.041, 0.036, and 0.000, respectively. Approximately 2.5% of fetal and early neonatal deaths in Quarter Horse-related breeds submitted to 2 different US diagnostic laboratories were homozygous for the mutant GBE1 allele, with the majority of these being abortions. Retrospective histopathology of the homozygotes detected periodic acid Schiff's (PAS)-positive inclusions in the cardiac or skeletal muscle, which is characteristic of GBED, in 8 out of the 9 cases. Pedigree and genotype analyses supported the hypothesis that GBED is inherited as a simple recessive trait from a single founder. The frequency with which GBED is associated with abortion and neonatal mortality in Quarter Horse-related breeds makes the DNA-based test valuable in determining specific diagnoses and designing matings that avoid conception of a GBED foal.

A 1.3-Mb interval map of equine homologs of HSA2.

A comparative approach that utilizes information from more densely mapped or sequenced genomes is a proven and efficient means to increase our knowledge of the structure of the horse genome. Human chromosome 2 (HSA2), the second largest human chromosome, comprising 243 Mb, and containing 1246 known genes, corresponds to all or parts of three equine chromosomes. This report describes the assignment of 140 new markers (78 genes and 62 microsatellites) to the equine radiation hybrid (RH) map, and the anchoring of 24 of these markers to horse chromosomes by FISH. The updated equine RH maps for ECA6p, ECA15, and ECA18 resulting from this work have one, two, and three RH linkage groups, respectively, per chromosome/chromosome-arm. These maps have a three-fold increase in the number of mapped markers compared to previous maps of these chromosomes, and an increase in the average marker density to one marker per 1.3 Mb. Comparative maps of ECA6p, ECA15, and ECA18 with human, chimpanzee, dog, mouse, rat, and chicken genomes reveal blocks of conserved synteny across mammals and vertebrates.

[Risk factors: environment, tobacco smoke]. / Facteurs de risque: environnement, tabac.

Environmental factors are usually considered as risk factors for increase of asthma prevalence. They may act isolately but are frequently associated. They act either directly by inducing asthma or more likely by increasing allergenic sensitization. Geographic situation is a well known risk factor. Important differences are noted between countries. The western lifestyle is evocated, including type of alimentation, small size of siblings, increased allergen exposure in houses. Intrauterine environment may play a role, particularly tobacco smoke during pregnancy and its respiratory effects on infant. Maternal allergenic exposure during pregnancy is an important factor because of maternofetal immunologic interactions. Outdoor pollution acts by enhancing bronchial responsiveness, allergenic sensitization and worsening respiratory diseases. Its effect is probably less important in infants and small children who are living indoor most of the time. Infections seems to have a complex action. Some virus, including respiratory syncytial virus, act to induce asthma or sensitization. Other type of infections (viral ou microbial) have a protector effect. Exposure to tobacco smoke, particularly maternal smoking, is identified in all studies, as one of the most important factors to be considered in childhood asthma. Exposure to allergen increases the risk of sensitization. Its direct responsibility to induce asthma is not established. Some of recent studies are suggesting the concept of a protective effect of early exposure. As far as preventive intervention is concerned, the recognition of these factors is important to limit the prevalence of childhood asthma.

Antiviral activity of Petiveria alliacea against the bovine viral diarrhea virus.

BACKGROUND: Natural products are a relevant source of antiviral drugs. Five medicinal plants used in Argentina have been assayed to detect inhibition of viral growth. METHODS: Antiviral activity of the infusions and methanolic extracts of Aristolochia macroura, Celtis spinosa, Plantago major, Schinus areira, Petiveria alliacea and four extracts obtained from the leaves and stems of the last plant were evaluated by the plaque assay. RESULTS: P. alliacea, unlike A. macroura, C. spinosa, P. major and S. areira, inhibited bovine viral diarrhea virus (BVDV) replication. Neither P. alliacea nor the assays of the other plants were active against herpes simplex virus type 1, poliovirus type 1, adenovirus serotype 7 and vesicular stomatitis virus type 1. Four extracts of P. alliacea were assayed to detect anti-BVDV activity. Ethyl acetate (EC(50) of 25 microg/ml) and dichloromethane (EC(50) of 43 microg/ml) extracts were active; moreover, promising SI (IC(50)/EC(50)) values were obtained. CONCLUSION: BVDV is highly prevalent in the cattle population, there are no antiviral compounds available; additionally, it is a viral model of the hepatitis C virus. For these reasons and in view of the results obtained, the isolation and characterization of the antiviral components present in the P. alliacea extracts is worth carrying out in the future.

Cytotoxic effect of Argentine medicinal plant extracts on human hepatocellular carcinoma cell line.

Methanolic extracts from Achyrocline satureioides (Dc.) Lam, Aristolochia macroura Gomez, Lithraea molleoides (Vell.) Engl., Schinus molle L., unlike those from Celtis spinosa Spreng, Chenopodium ambrosioides L., Petiveria alliacea L., and Plantago major L. showed cytotoxic activity against a human hepatocellular carcinoma cell line, Hep G2. Schinus molle L. was the most active (IC50=50+/-7 microg/ml). These results call for further studies of these extracts.

Reconstituted syntaxin1a/SNAP25 interacts with negatively charged lipids as measured by lateral diffusion in planar supported bilayers.

According to the soluble N-ethylmaleimide-sensitive factor (NSF)-attachment protein (SNAP) receptor hypothesis (SNARE hypothesis), interactions between target SNAREs and vesicle SNAREs (t- and v-SNAREs) are required for membrane fusion in intracellular vesicle transport and exocytosis. The precise role of the SNAREs in tethering, docking, and fusion is still disputed. Biophysical measurements of SNARE interactions in planar supported membranes could potentially resolve some of the key questions regarding the mechanism of SNARE-mediated membrane fusion. As a first step toward this goal, recombinant syntaxin1A/SNAP25 (t-SNARE) was reconstituted into polymer-supported planar lipid bilayers. Reconstituted t-SNAREs in supported bilayers bound soluble green fluorescent protein/vesicle-associated membrane protein (v-SNARE), and the SNARE complexes could be specifically dissociated by NSF/alpha-SNAP in the presence of ATP. The physiological activities of SNARE complex formation were thus well reproduced in this reconstituted planar model membrane system. A large fraction (~75%) of the reconstituted t-SNARE was laterally mobile with a lateral diffusion coefficient of 7.5 x 10(-9) cm(2)/s in a phosphatidylcholine lipid background. Negatively charged lipids reduced the mobile fraction of the t-SNARE and the lipids themselves. Phosphatidylinositol-4,5-bisphosphate was more effective than phosphatidylserine in reducing the lateral mobility of the complexes. A model of how acidic lipid-SNARE interactions might alter lipid fluidity is discussed.

Tethered polymer-supported planar lipid bilayers for reconstitution of integral membrane proteins: silane-polyethyleneglycol-lipid as a cushion and covalent linker.

There is increasing interest in supported membranes as models of biological membranes and as a physiological matrix for studying the structure and function of membrane proteins and receptors. A common problem of protein-lipid bilayers that are directly supported on a hydrophilic substrate is nonphysiological interactions of integral membrane proteins with the solid support to the extent that they will not diffuse in the plane of the membrane. To alleviate some of these problems we have developed a new tethered polymer-supported planar lipid bilayer system, which permitted us to reconstitute integral membrane proteins in a laterally mobile form. We have supported lipid bilayers on a newly designed polyethyleneglycol cushion, which provided a soft support and, for increased stability, covalent linkage of the membranes to the supporting quartz or glass substrates. The formation and morphology of the bilayers were followed by total internal reflection and epifluorescence microscopy, and the lateral diffusion of the lipids and proteins in the bilayer was monitored by fluorescence recovery after photobleaching. Uniform bilayers with high lateral lipid diffusion coefficients (0.8-1.2 x 10(-8) cm(2)/s) were observed when the polymer concentration was kept slightly below the mushroom-to-brush transition. Cytochrome b(5) and annexin V were used as first test proteins in this system. When reconstituted in supported bilayers that were directly supported on quartz, both proteins were largely immobile with mobile fractions < 25%. However, two populations of laterally mobile proteins were observed in the polymer-supported bilayers. Approximately 25% of cytochrome b(5) diffused with a diffusion coefficient of approximately 1 x 10(-8) cm(2)/s, and 50-60% diffused with a diffusion coefficient of approximately 2 x 10(-10) cm(2)/s. Similarly, one-third of annexin V diffused with a diffusion coefficient of approximately 3 x 10(-9) cm(2)/s, and two-thirds diffused with a diffusion coefficient of approximately 4 x 10(-10) cm(2)/s. A model for the interaction of these proteins with the underlying polymer is discussed.

The prevalence of dental erosion in a United States and a United Kingdom sample of adolescents.

PURPOSE: A high prevalence of tooth surface loss due to erosion is well recognized in the United Kingdom (UK), but not in the United States (US). This could be due to prevalence or perception or a combination of both. The aim of this study was to measure the prevalence of erosion of the upper permanent incisors in US and UK samples of 11-13 year old children. METHODS: Convenience samples of 129 subjects were examined in the US and 125 in the UK by two trained examiners. The palatal and buccal surfaces of the upper permanent incisors were assessed for the presence of erosion. Subjects also completed a questionnaire investigating any association between the presence of erosion and possible etiological factors. RESULTS: The prevalence of erosion was 41% in the US and 37% in the UK samples, this difference was not statistically significant. Similarly no statistically significant difference was found between the sexes. The erosion present was confined to enamel in the vast majority of subjects. The questionnaire did not detect any link between the presence of erosion and possible etiological factors. CONCLUSION: The results of this study suggest that dental erosion is common in both US and UK adolescent populations. There is a need for a larger study to investigate this issue further.

Coadministration of phenytoin and felbamate: evidence of additional phenytoin dose-reduction requirements based on pharmacokinetics and tolerability with increasing doses of felbamate.

PURPOSE: This open-label study investigated the pharmacokinetic interaction of phenytoin (PHT) and felbamate (FBM). METHODS: Ten subjects with epilepsy receiving PHT monotherapy were administered increasing doses of FBM (1,200, 1,800, 2,400-3,600 mg/day) at 2-week intervals. PHT doses were reduced by 20% on an individual basis when evidence of clinically significant intolerance was present. With intolerance, the PHT dose was reduced before the next incremental FBM dose. Blood samples were analyzed for FBM, PHT, and PHT metabolite 5-(4-hydroxyphenyl)-5-phenylhydantoin (HPPH). RESULTS: Total PHT plasma concentrations increased with coadministered FBM. PHT Cmax increased from 15.9 microg/ml at baseline to 20.9 microg/ml after 1,200 mg/day FBM and to 26.8 microg/ml after 1,800 mg/day FBM. Four subjects required a 20% PHT dose reduction after 1,800 mg/day FBM and six after the administration of 2,400 mg/day FBM. All subjects required further 20% PHT reductions before 3,600 mg/day FBM. FBM Cmax and AUCT were reduced, and apparent clearance increased compared with data from FBM monotherapy. CONCLUSIONS: With the initiation of FBM therapy in subjects receiving PHT, the PHT dosage should be reduced by 20%. Further PHT dose reductions are likely to be necessary if the FBM dose is increased. The requirements for reductions in dose might be predicted by clinical signs of PHT intolerance.

Hepatosplenic cat-scratch disease in children: selected clinical features and treatment.

We reviewed 19 cases of hepatosplenic cat-scratch disease at Texas Children's Hospital (Houston). The range of the patients' ages was 2 years 4 months to 11 years 8 months. The chief complaint was fever for all patients. The duration of fever before diagnosis was 7 to 56 days (mean, 22 days). Abdominal pain was present in 13 patients (68%). Thirteen children were treated with rifampin alone, and three received rifampin therapy plus gentamicin or trimethoprim-sulfamethoxazole. Once rifampin therapy was initiated alone or in combination, improvement was noted within 1 to 5 days (mean, 2.6 days) for patients who had had prolonged fever the duration of which before rifampin therapy averaged 3 weeks. The most common dosage and duration for our patients were 20 mg/[kg x d] every 12 hours and 14 days, respectively. Rifampin should be considered in the initial antimicrobial treatment of hepatosplenic cat-scratch disease.

Pharmacoeconomic analysis of using Sinemet CR over standard Sinemet in parkinsonian patients with motor fluctuations.

OBJECTIVE: To compare the costs of pharmacotherapy in patients with Parkinson's disease before and after converting from standard Sinemet to extended-release Sinemet CR. DESIGN: Investigators retrospectively reviewed records of patients converting from Sinemet to Sinemet CR for efficacy and total drug costs. Cost-effectiveness was evaluated retrospectively from data collected in prospective Sinemet CR efficacy trials. SETTING: Parkinson's disease clinic at a tertiary care university teaching hospital. PATIENTS: 100 patients with motor fluctuations who had undergone an initial 6-month course of Sinemet therapy, followed by a 6-month course of Sinemet CR. MAIN OUTCOME MEASURES: Total cost was measured as the cost of Sinemet formulations plus the costs of other antiparkinson medications. Differences in pre- and postconversion costs were compared by using the paired, two-tailed Student's t-test. A substudy of 39 patients on the cost-effectiveness of conversion measured the ratio of daily medication costs to the daily hours "on" without chorea. RESULTS: While total daily medication costs after conversion increased by 21%, patients experienced either a comparable or an improved degree of disease control with Sinemet CR. Patients who were also taking selegiline were able to decrease selegiline expense by 20%. The costs of other adjunctive medications did not differ significantly after conversion. The cost-effectiveness analysis revealed an increase in postconversion on time by 2.2 hours (p = 0.0001), accompanied by a $2.85 decrease in total cost per hour on without chorea (p = 0.11). CONCLUSIONS: Although Sinemet CR is more costly, it may be more cost-effective in patients with motor fluctuations. Some patients may be able to reduce adjunctive medications.