Electrophysiologic effects of betaxolol on conduction properties of the antegrade and retrograde pathway in patients with typical atrioventricular node reentry tachycardia following intravenous and oral administration

The electrophysiologic effects of the beta-1 selective beta adrenergic blocking drug Betaxolol were investigated after intravenous (0.15 mg/kg body weight) and oral (20 mg/day) administration in 11 patients with atrioventricular-nodal reentrant tachycardia. Betaxolol significantly (p less than 0.01) prolonged cycle length, sinus node recovery time, AH-interval, as well as the antegrade functional refractory period of the slow and fast AV-nodal pathway. The effective refractory period of the fast AV-nodal pathway was also markedly increased (p less than 0.05). In only six patients could the effective refractory period of the slow AV-nodal pathway be determined; in the other patients, it was shorter than the effective refractory period of the atrium. The effective refractory period of the atrium and the ventricle was not significantly altered by Betaxolol. Intravenous administration of Betaxolol suppressed induction of tachycardia in eight patients, whereas after oral Betaxolol, tachycardia was not inducible in ten patients. Betaxolol prevented induction of tachycardia in two patients by prolonging antegrade conduction over the slow AV-nodal pathway. The retrograde fast AV-nodal pathway was blocked in eight patients. Presumably the increased effectiveness of oral Betaxolol can be attributed to higher Betaxolol plasma concentrations, reached after oral treatment (58 +/- 38 ng/ml), as compared to intravenous administration (40 +/- 40 ng/ml). There were no false positive results after intravenous testing of Betaxolol.     

Evidence for a maternal yolk factor associated with increased tolerance and resistance of feral white sucker (Catostomus commersoni) to waterborne copper

White suckers, collected from lakes containing elevated levels of copper (12 micrograms liter-1) and zinc (250 micrograms liter-1), were evaluated for reproductive performance, growth and survival of the larvae, and tolerance of the larvae to waterborne copper. Fertilization success was not impaired in white suckers from contaminated sites; metal-exposed males performed better than control males in fertilization trials with control eggs. Larvae hatched from eggs collected at contaminated sites and fertilized in clean water were smaller, developed at a slightly increased rate, and exhibited poorer growth and survival than larvae from control sites. Larvae showed significant changes in resistance and tolerance to copper with age. During the period of endogenous nutrition, larvae from eggs taken at contaminated sites showed increased resistance and tolerance to waterborne copper relative to controls. The effect was not seen in larvae at first feeding, at ages older than 4 days after the onset of feeding (25 days posthatch) or in larvae hatched from control eggs fertilized with sperm from males taken at contaminated sites. This study provides evidence for a maternal yolk factor associated with increased tolerance and resistance of larvae to copper.     

Double immunoelectron microscopic labelings of human chorionic gonadotropin and human placental lactogen in human chorionic villi

Simultaneous immunoelectron microscopic localization of human chorionic gonadotropin (HCG) and human placental lactogen (HPL) was examined on the same ultrathin section of human chorionic villi by means of the double labeling technique. Using specific rabbit antisera against HCG and HPL followed by goat anti-rabbit IgG-coated colloidal gold of different sizes (15 nm and 5 nm), immunoreactions of HCG were concentrated on middle-sized secretory granules of 200-300 nm and large dense bodies of 500-1000 nm, while those of HPL were exclusively located on small secretory granules of 80-180 nm. The present experiment provides direct evidence for our previous data that HCG and HPL seem to be stored in different granular components in the syncytiotrophoblast.     

Lens alpha-neoproteins

The formation of lens alpha-neoprotein molecules which are built by the association of A and B subunit chains of alpha-crystallin but have a different quaternary structure than the native protein is a posttranslational process that progresses through the life span. Alpha-neoproteins occur regularly in all mature mammalian lenses tested. The mechanisms that have been identified for the formation of alpha neoproteins are imbalance in the biosynthesis of A- to B-chains, which leads to a ratio of less than 2A-chains to 1B-chain, and derivation of the chains after their initial association into native alpha-crystallin. In terms of quantity of neoproteins, no significant differences have been found between lenses with developing cataracts and normal control lenses of corresponding age. The possibility that there are structural differences between alpha-neoproteins in normal and cataractous lenses of the same age, as well as potential differences among alpha-neoproteins isolated from normal lenses of different ages, are presently under investigation.     

A new member of the Anopheles quadrimaculatus complex, species C

A new member, species C, of the Anopheles quadrimaculatus complex was recently found in collections from the northwest coast of Florida. This new species cannot be differentiated from the other 2 species with available taxonomic keys. Evidence for this taxon as a sibling species includes data on hybrid sterility and distorted sex ratios in the progeny of crosses to species A and B, chromosomal differences, and diagnostic allozymes.     

Progressive peripheral cone dysfunction

A 22-year-old man had a three-year history of progressive day blindness, most notably peripherally, and denied difficulty with central vision or color vision. Visual function studies demonstrated a diffuse dysfunction of the photopic system and normal scotopic function. The central cone function, however, was essentially normal. Visual acuity was 20/20 in each eye, results on AO-HRR and Ishihara color plate testing were normal, color naming visual fields demonstrated color discrimination in the central 10 degrees, and foveal adaptation was normal.     

The relationship between intestinal Campylobacter species isolated from animals and humans as determined by BRENDA

Intestinal thermophilic Campylobacter species produce stable patterns when subjected to bacterial restriction endonuclease DNA analysis (BRENDA); this technique is therefore of considerable value in epidemiological studies. BRENDA was used to examine thermophilic Campylobacter species from humans, wild and domestic animals. One hundred and ninety-four (61%) of 316 isolates of Campylobacter jejuni from humans had BRENDA patterns which could be matched to those of animal isolates. Poultry appear to be a major source of infection for C. jejuni in humans with nearly half (49.7%) of the human isolates giving patterns which were indistinguishable from those isolated from poultry. A total of 60 BRENDA types were identified from 316 human isolates and 11 of these had the same pattern as those isolated from poultry. One of the three Campylobacter coli BRENDA types recovered from poultry was indistinguishable from a human isolate type. Pigs appear to be only a minor source of C. coli infection for humans in New Zealand. Rats were found to be infected with strains of C. jejuni with BRENDA patterns indistinguishable from those infecting humans, poultry and a horse. None of the 102 isolates of Campylobacter species from wild birds gave BRENDA patterns similar to those of isolates from humans.