New evidence for the structure of myxinol

1. Preliminary spectroscopic examination of a second component of hagfish bile salts suggested that it might be 3β,7α,26(27)-trihydroxy-5α-cholestane. 2. Impure reduction products of the 3β,26(27)-dihydroxycholestane-7,16-dione previously made from myxinol disulphate appeared also to have the 5α-configuration. 3. Infrared, nuclear-magnetic-resonance and mass-spectrographic as well as optical-rotatory-dispersion measurements on 3β,26(27)-dihydroxycholestane-7,16-dione showed that it was a 5α-compound. 4. Myxinol is thus 3β,7α,16α,26(27)-tetrahydroxy-5α-cholestane; new nuclear-magnetic-resonance measurements on myxinol tetra-acetate at higher resolution confirm this structure.     

Amino acid metabolism in various fractions of rat-brain homogenates with special reference to the effect of ethanol

1. The increase in brain γ-aminobutyrate, glutamate and aspartate and the decrease in brain glutamine that occur when ethanol is administered to rats in vivo could be reproduced by incubating brain homogenates from rats pretreated with ethanol. 2. For the demonstration of the effects of pretreatment with ethanol on the metabolism of γ-aminobutyrate and glutamine, the whole homogenate could be replaced by various supernatant preparations, and even by the soluble protein fraction, which was less active, however. The `postmitochondrial' sediment could likewise mediate the effects of pretreatment with ethanol. 3. When the brain homogenates from control and ethanol-treated rats were allowed to `age' at 2° for more than 7 days, the metabolic difference at incubation could no longer be demonstrated. The capacities of the homogenate from the control rats had changed to resemble those of ethanol-treated rats. 4. Data are given on the effects of the incubation time and of the concentration of homogenate.     

Studies on the biosynthesis of gramicidin S in a cell-free system from Bacillus brevis. Further attempts to elucidate its mechanism of synthesis

1. The pH optima for the incorporation of (14)C-labelled amino acids into gramicidin S by an 11000g cell-free extract from Bacillus brevis have been determined. The pH optima for leucine, proline, phenylalanine, ornithine and valine were 7.5-7.7, 7.5-7.7, 7.7-7.9, 7.7-7.9 and 8.0-8.2 respectively. Hence the greatest difference in pH optima existed between leucine and valine, where it was 0.5pH unit. 2. The 11000g cell-free extract incorporated into gramicidin S only the l-isomers of valine, proline and ornithine. However, both isomers of leucine are utilized and the experiments indicate that a leucine racemase exists in the 11000g cell-free extract. With phenylalanine the l-isomer is utilized much more effectively than the d-isomer. This is noteworthy since it is the d-isomer that occurs in gramicidin S. The experiments indicate that conversion of the l-isomer into the d-form takes place at a stage beyond that of the free amino acid.     

Transformation of sperm nuclei into male pronuclei in nucleate and anucleate fragments of parthenogenetic mouse eggs

Our objective was to examine the ability of nucleate and anucleate fragments of artificially activated mouse eggs to transform sperm nucleus into male pronucleus. To this end, zona-free oocytes in metaphase II were activated by ethanol and bisected into halves (one with the spindle, the other anucleate) either within 10 to 20 min (series A) or 3 or 5 hr later (series B). In series A, the fragments were inseminated 3,5, and 8 h after activation, and in series B. 3 and 5 h after activation. Both nucleate and anucleate fragments lose the capability of transforming sperm nucleus into fully formed pronucleus sometime between 3 and 5 h after activation. In 8 h old parthenogenetic fragments, the majority of sperm nuclei remain unchanged or begin decondensation but never reach the stage of an early pronucleus. In over 1/3 of anucleate fragments of this age group, sperm nuclei develop defectively: chromatin decondenses inside the persisting nuclear envelope. In other experimental groups, the incidence of these abnormal sperm nuclei varies between 0 and 10%. In general, the anuclcate fragments retain the capability to transform sperm nuclei (fully or partially) longer than their nuclear counterparts. This difference may be accounted for by a different level of substances required for pronuclcar growth (extrachromosomal constituents of the germinal vesicle and nuclear lamins): high and constant in the cytoplasm of anucleate egg halves and low and progressively decreasing in the nucleate halves because of their putative uptake by the female pronucleus. However, the cytoplasmic factors responsible for the initial stages of transformation (nuclear envelope breakdown, chromatin decondensation) become eventually inactivated both in the presence and in the absence of a female pronucleus.     

Pattern of simulated snoring is different through mouth and nose

Cineradiography of the pharynx during simulated snoring was done in 6 healthy volunteers, and supraglottic pressure and flow rate were recorded in 12 others. We observed, immediately before snoring, a decrease in the sagittal diameter of the oropharynx followed, during snoring, by high-frequency oscillations of soft palate and pharyngeal walls. The pattern of soft palate oscillations was different while snoring through the nose or mouth. During inspiratory snoring through the nose, the soft palate remained in close contact with the back of the tongue and only the uvula presented high-frequency oscillations. Snoring through the mouth resulted in ample high-frequency oscillations of the whole soft palate. Frequency of airflow and supraglottic pressure oscillations was less (P less than 0.05) during mouth (28.2 +/- 7.5 Hz) than during nasal snoring (77.8 +/- 36.7 Hz). This difference may be related to the smaller oscillating mass (i.e., uvula) during nasal snoring. At variance with our previous data, which showed that snoring during sleep, in both heavy (nonapneic) snorers and obstructive sleep apnea patients, was systematically preceded by flow limitation, this was not true during simulated snoring.