Effect of cardiogenic gas mixing on arterial O2 and CO2 tensions during breath holding

To examine the effect of cardiogenic gas mixing on gas exchange we measured arterial tension of O2 (PaO2) and arterial tension of CO2 (PaCO2) during 3- to 5-min breath holds (BH) before and after infusing 50 ml of saline into the pericardial space (PCF) of seven anesthetized, paralyzed, mechanically ventilated dogs. During BH the ventilator was disconnected and a bias flow of 50% O2 at 4-5 l/min was delivered through the side ports of a small catheter whose tip was positioned 1 cm cephalad of the carina. Paired runs, alternately with and without PCF, were performed in triplicate in each dog. Initial PaO2 was similar for control runs [81 +/- 3 mmHg (SE)] and PCF runs (78 +/- 3 mmHg; P greater than 0.1). After 3-min BH, PaO2 in PCF runs (33 +/- 3 mmHg) was less than that in control runs (58 +/- 4 mmHg) (P less than 0.001). In contrast, the pattern of PaCO2 during BH did not differ with PCF. After 3-min BH, PaCO2 was 49 +/- 3 mmHg with PCF and 49 +/- 2 mmHg in the control runs (P greater than 0.7). In two dogs, repeated 50-ml reductions in lung volume, produced by rib cage compression, did not alter the time course of PaO2 during BH. Although cardiac output decreased slightly with PCF, hemodynamic changes due to PCF were unlikely to account for the observed fall in PaO2. Our results indicate a substantial effect of cardiogenic gas mixing on O2 uptake when tracheal gas is O2 enriched during breath holding.(ABSTRACT TRUNCATED AT 250 WORDS)     

Steroids and related products. LIV. The synthesis of 11-oxa steroids. VI. The synthesis of 11-oxatestosterone

The synthesis of 11-oxatestosterone from 11-oxa-5 alpha-androstane-3,17-dione, which is available from hecogenin, is described. The product shows, in comparison with the natural hormone, diminished androgenic and anabolic activities.     

A single amino acid substitution in v-erbB confers a thermolabile phenotype to ts167 avian erythroblastosis virus-transformed erythroid cells.

A library of recombinant bacteriophage was prepared from ts167 avian erythroblastosis virus-transformed erythroid precursor cells (HD6), and integrated proviruses from three distinct genomic loci were isolated. A subclone of one of these proviruses (pAEV1) was shown to confer temperature-sensitive release from transformation of erythroid precursor cells in vitro. The predicted amino acid sequence of the v-erbB polypeptide from the mutant had a single amino acid change when compared with the wild-type parental virus. When the wild-type amino acid was introduced into the temperature-sensitive avian erythroblastosis virus provirus in pAEV1, all erythroid clones produced in vitro were phenotypically wild type. The mutation is a change from a histidine to an aspartic acid in the temperature-sensitive v-erbB polypeptide. It is located in the center of the tyrosine-specific protein kinase domain and corresponds to amino acid position 826 of the human epidermal growth factor receptor sequence.     

Proacrosin and the differentiation of the spermatozoa

Using the indirect immunofluorescence staining technique, the occurrence and localization of proacrosin, the zymogen form of acrosin, was studied during spermatogenesis in the bull, ram, boar and rabbit. Proacrosin staining was demonstrable for the first time in the early haploid spermatid and increased with the differentiation of the spermatid to spermatozoon. The spermatozoon is covered by a cap-like structure of uniform fluorescence corresponding to the acrosomal compartment of the male gamete. No fluorescence could be found in diploid spermatogenic cells, i.e., in spermatogonia and spermatocytes. An identical developmental pattern of proacrosin was observed with the indirect immunoperoxidase staining technique. However, with this staining technique a distinct distribution of proacrosin staining was observed in the acrosome of epididymal and ejaculated spermatozoa of the bull, ram, boar, rabbit and man. Proacrosin seems to be distributed in the acrosome in granules rather than in the homogeneous form, as was indicated by the results of indirect immunofluorescence staining.     

Inactivation of Naegleria gruberi cysts by chlorinated cyanurates.

The resistance of Naegleria gruberi cysts to chlorine in the presence of cyanuric acid was compared at pH 5 and 7. An amperometric membrane electrode was used to measure HOCl concentrations independently of the chlorinated cyanurate species, thus permitting an analysis of the role of free chlorine versus chlorinated cyanurates in cyst inactivation. In the presence of cyanuric acid, the products of the HOCl residual and the contact time required for 99% cyst inactivation were 8.5 mg . min/liter and 13.9 mg . min/liter at pH 5 and 7, respectively. The Watson's Law coefficients of dilution (n) were 1.3 and 1.6 at pH 5 and 7, respectively. The results strongly suggest that HOCl is the predominant cysticide with no measurable cysticidal effect of the chlorinated cyanurate species.     

Growth in the area of the inferior dental foramen of rats

The object of the present investigation was to see if the bone around the inferior dental nerve remodelled during mandibular growth and development. The investigation was carried out by injecting 27 albino Lewis rats with three fluorescent bone seeking dyes--oxytetracycline HCl (OTC), alizarin red S (ARS), and 2,4 bis-[N,N'-di' (carbomethyl-aminomethyl)] fluorescein (DCAF)--and then studying the bone around the inferior dental foramen. The mandibles of the animals were studied both macroscopically and microscopically under ultraviolet light to investigate the growth processes occurring and to see if the inferior dental foramen was relocated during growth. A quantitative analysis utilizing two specimens was also carried out for the same purpose. The results of both the qualitative and the quantitative analyses showed that the bone around the inferior dental nerve remodeled during mandibular growth. The mandible grew in an upward and backward direction, and the inferior dental foramen was correspondingly relocated in an upward and backward direction to maintain exactly the same position relative to the condyle and the posterior border of the ramus. This study, then, supports Moss's concept of the "unloaded" nerve, and is in keeping with his view of mandibular growth based on the functional matrix theory.     

Growth rate stimulation of marine pseudomonads by thiosulfate

The oxidation of thiosulfate to tetrathionate exerts a definite growth rate stimulation in glucose, acetate, and yeast extract cultures of some marine pseudomonads. The failure to find this effect in earlier studies with terrestrial isolates may lie in the particular conditions used in the present experiments (constant pH, high ratio of thiosulfate to organic substrate) or in the different metabolic characteristics of the marine isolates.Contribution No. 3220 from the Woods Hole Oceanographic Institution.     

Genetic polymorphism of lactate dehydrogenase isoenzymes in the carp (Cyprinus carpio) apparently due to a “null allele”

As a consequence of polyploidization, the carp is endowed with three genetic loci coding for LDH in most tissues (and additional ones in liver). However, each such duplicated gene may not be functionally essential for the organism and could be eliminated. In a population survey, an electrophoretic polymorphism was detected which may best be interpreted by the assumption of a null allele, which is apparently not subject to selective pressure. Thus this originally duplicated gene would have diverged in the course of evolution without the origin of differences in function, so that one or the other of the genes is dispensable.