Effects of low-chloride solutions on action potentials of sheep cadiac purkinje fibers

The rapid repolarization during phase 1 of the action potential of sheep cardiac purkinje fibers has been attributed to a time- and voltage-dependent chloride current. In part, this conclusion was based on experiments that showed a substantial slowing of phase 1 when larger, presumably impermeant, anions were substituted for chloride in tyrode’s solution. We have re- examined the electrical effects of low-chloride solutions. We recorded action potentials of sheep cardiac purkinje fibers in normal tyrode’s solution and in low-chloride solutions made by substituting sodium propionate, acetylglycinate, methylsulfate, or methanesulfonate for the NaCl of Tyrode’s solution. Total calcium was adjusted to keep calcium ion activity of test solutions equal to that of control solutions. Propionate gave qualitatively variable results in preliminary experiments; it was not tested further. Low-chloride solutions made with the other anions gave much more consistent results: phase 1 and the notch that often occurs between phases 1 and 2 were usually unaffected, and the action potential duration usually increased. The only apparent change in the resting potential was a transient 3-6 mV depolarization when low-chloride solution was first admitted to the chamber, and a symmetrical transient hyperpolarization when chloride was returned to normal. If a time- and voltage-dependent chloride current exists in sheep cardiac purkinje fibers, our results suggest that it plays little role in generating phase 1 of the action potential.     

Antibody responses against natural Taenia hydatigena infection in dogs in Kenya

Antibody responses (IgG) against Taenia hydatigena infection in dogs in Kenya were analysed in ELISA using excretory/secretory products of T. hydatigena scoleces derived from goat cysticercus cysts. Helminth infections of individual dogs were confirmed at autopsy. T. hydatigena worms were found in 89.5% of 143 dogs, and positive anti-T. hydatigena antibody levels were detected in 58.7% of infected dogs. Positive antiscolex antibody levels were detected in 40.0% of Turkana dogs uninfected with T. hydatigena, suggesting previous infection. Antibody was not detected in 34.4% of infected dogs. There was no relationship between individual T. hydatigena worm burdens and absorbance values for sera in ELISA. It was not possible to distinguish between sera from T. hydatigena-infected and uninfected dogs.     

Complete and Defective Bacteriophages of Classical Vibrio cholerae: Relationship to the Kappa Type Bacteriophage

The Classical Vibrio cholerae strain NIH 41 contains two temperate bacteriophages, designated VcA-1 and VcA-2, that are distinguished by immunity, plaque morphology, induction kinetics, and particle morphology. Both phage are serologically related to phage Kappa. However, only phage VcA-2 has the Kappa type host range and immunity. The induction kinetics and immunity patterns of Classical vibrios suggest that these strains may contain defective phage related to the phages isolated from NIH 41. Classical strain 569B releases phage-tail structures upon induction that are morphologically and serologically related to both phages VcA-1 and VcA-2. The possible reason for the defectiveness of these phages in 569B is discussed. It is concluded that complete or defective bacteriophages of the Kappa type morphology and serology are extremely prevalent in V. cholerae, regardless of biotype.     

Milbemycin oxime in a new formulation, combined with praziquantel, does not reduce the efficacy of praziquantel against Echinococcus multilocularis in cats

Twenty European domestic cats were each infected with 15,000 protoscoleces of Echinococcus multilocularis extracted from metacestodes grown in experimentally infected common voles (Microtus arvalis). Sixteen days after infection, ten cats were treated with a broad-spectrum anthelmintic and acaricide comprising praziquantel and milbemycin oxime. Five days later treated and untreated cats were euthanized and the intestine examined for E. multilocularis. Five of ten untreated cats were infected with E. multilocularis with worm burdens ranging from 235 to 1920 worms per cat. No E. multilocularis were recovered from any of the treated cats. This study has demonstrated that this new combination broad spectrum anthelmintic and acaricide for cats is highly efficacious against E. multilocularis and the relevance of this is discussed.     

Efficacy of Droncit Spot-on (praziquantel) 4% w/v against immature and mature Echinococcus multilocularis in cats

The causative agent of alveolar hydatidosis in humans, the fox tapeworm Echinococcus multilocularis, is extending its geographical range in Europe and has been found in domestic cats in some areas. A dermally applied cestocidal treatment for domestic cats has been developed and the efficacy of this treatment is reported. Thirty purpose-bred cats were experimentally infected each with 10000 protoscoleces of Echinococcus multilocularis. Ten days later one group of ten cats was treated with Droncit(R) Spot-on (Praziquantel) 4% w/v dermally in one place on the dorsal aspect of the neck at a dose of 8 mg/kg. Eleven days later (21 days p.i.) a second group of ten cats was also treated with Droncit(R) Spot-on the same way. One group of ten cats was left untreated as controls. Twenty three days after infection the cats were examined for the presence of E. multilocularis tapeworms. No E. multilocularis were recovered from any of the cats in either of the treated groups. Echinococcus multilocularis were recovered from eight of the ten cats left untreated as controls. The worm burdens in the untreated cats were 0, 0, 5, 15, 75, 110, 220, 815, 2635, and 3045 worms per cat. The worms ranged in development from the three to four segment stage. Many of the E. multilocularis with four segments contained unshelled eggs in the terminal segment. This study indicates that Droncit(R) Spot-on (Praziquantel) 4% w/v applied dermally at 8 mg/kg is highly effective in removing E. multilocularis from the small intestine of cats infected with immature and mature (prepatent) infections of E. multilocularis. In the cats with the mature infections all tapeworms were absent from the small intestine within 2 days of treatment.     

Glycine 384 is required for presenilin-1 function and is conserved in bacterial polytopic aspartyl proteases

Endoproteolysis of beta-amyloid precursor protein (betaAPP) and Notch requires conserved aspartate residues in presenilins 1 and 2 (PS1 and PS2). Although PS1 and PS2 have therefore been proposed to be aspartyl proteases, no homology to other aspartyl proteases has been found. Here we identify homology between the presenilin active site and polytopic aspartyl proteases of bacterial origin, thus supporting the hypothesis that presenilins are novel aspartyl proteases.     

Infection pressure of human alveolar echinococcosis due to village and small town foxes (<Emphasis Type="Italic">Vuples vulpes</Emphasis>) living in close proximity to residents

This study investigated the epidemiological and ecological factors to assess the infection pressure of alveolar echinococcosis to human which are living in villages and small towns. Foxes and fox faeces were examined for Echinococcus multilocularis and foxes were observed by radio telemetry in Upper Bavaria, Germany. Forty-three percent of the village foxes (n = 65) had been infected with E. multilocularis. This prevalence rate did not differ significantly from the prevalence among rural foxes, which was 39% (n = 33; χ ² = 0.12, df = 1, p = 0.727) determined by the intestinal scraping technique. PCR analyses of fox faeces showed a higher infection rate of 35% (n = 26) among rural foxes than among foxes in villages and small towns (26%, n = 69; χ ² = 0.68, df = 1, p = 0.411). One quarter of the fox faecal samples come from private gardens of residents. The radio-tracking study on 17 foxes showed that foxes preferred the built-up area and grassland outside the villages. Village foxes concentrated their activity within a range of 500 m around the settlement. Sixty-four percent of all bearings for radio-tracked foxes showed positions in areas outside the town, and 36% of bearings were within the settlement. Village foxes, which are infected with E. multilocularis, are able to carry the parasite continuously into settlements and fox faeces present an immediate source of infection to humans, especially within their gardens. Therefore, foxes are responsible for environmental E. multilocularis egg contamination in the vicinity of humans, leading to an infection risk to inhabitants of villages and small towns.     

Using co-occurrence network structure to extract synonymous gene and protein names from MEDLINE abstracts

Background  

Text-mining can assist biomedical researchers in reducing information overload by extracting useful knowledge from large collections of text. We developed a novel text-mining method based on analyzing the network structure created by symbol co-occurrences as a way to extend the capabilities of knowledge extraction. The method was applied to the task of automatic gene and protein name synonym extraction.     

An IGF-I promoter polymorphism modifies the relationships between birth weight and risk factors for cardiovascular disease and diabetes at age 36

BACKGROUND: Biochemical testing for pheochromocytoma by measurement of fractionated plasma metanephrines is limited by false positive rates of up to 18% in people without known genetic predisposition to the disease. The plasma normetanephrine fraction is responsible for most false positives and plasma normetanephrine increases with age. The objective of this study was to determine if we could improve the specificity of fractionated plasma measurements, by statistically adjusting for age. METHODS: An age-adjusted metanephrine score was derived using logistic regression from 343 subjects (including 33 people with pheochromocytoma) who underwent fractionated plasma metanephrine measurements as part of investigations for suspected pheochromocytoma at Mayo Clinic Rochester (derivation set). The performance of the age-adjusted score was validated in a dataset of 158 subjects (including patients 23 with pheochromocytoma) that underwent measurements of fractionated plasma metanephrines at Mayo Clinic the following year (validation dataset). None of the participants in the validation dataset had known genetic predisposition to pheochromocytoma. RESULTS: The sensitivity of the age-adjusted metanephrine score was the same as that of traditional interpretation of fractionated plasma metanephrine measurements, yielding a sensitivity of 100% (23/23, 95% confidence interval [CI] 85.7%, 100%). However, the false positive rate with traditional interpretation of fractionated plasma metanephrine measurements was 16.3% (22/135, 95% CI, 11.0%, 23.4%) and that of the age-adjusted score was significantly lower at 3.0% (4/135, 95% CI, 1.2%, 7.4%) (p < 0.001 using McNemar's test). CONCLUSION: An adjustment for age in the interpretation of results of fractionated plasma metanephrines may significantly decrease false positives when using this test to exclude sporadic pheochromocytoma. Such improvements in false positive rate may result in savings of expenditures related to confirmatory imaging.