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Biomedical subjects

R A Harrison

Publications and source records attributed to R A Harrison.

At least 199 records · Page 11Linked to original sources
PubMed1980

Changes in intrapulmonary shunting with administration of 100 percent oxygen.

The effects of increasing the fractional concentration of oxygen in the inspired gas to 1.0 on intrapulmonary shunting (Qsp) was evaluated in 82 intubated cardiovascularly stable patients in intensive care, regardless of airway pressure therapy or preexistent pulmonary pathologic abnormalities. Intrapulmonary shunting following administration of 100 percent oxygen increased in 132 of 140 measurements, decreased in seven, and remained unchanged in one measurement. The direction of change of Qsp with 100 percent oxygen shows no correlation with either airway pressure therapy or preexisting pulmonary disease.

Adult↗
PubMed1979

The maintenance of motility and the surface properties of epididymal spermatozoa from bull, rabbit and ram in homologous seminal and epididymal plasma.

Epididymal spermatozoa from bull, rabbit and ram were incubated in homologous epididymal plasma or seminal plasma in a buffered saline-based medium with or without serum albumin. The spermatozoa were either diluted directly into the medium or were washed first. No effect of washing was observed on the subsequent reaction of the cells to the different media. A considerable proportion of the populations of epididymal spermatozoa survived (i.e. continued to exhibit motility) for up to 22 h at 30 degrees C in the simple saline-based medium. Initially epididymal plasma had a slight stimulatory effect on sperm motility in ram and bull but it had no effect on sperm survival in any of the 3 species. Seminal plasma stimulated motility markedly in ram initially, but in all 3 species seminal plasma was detrimental to survival: in ram even a 15-min exposure to the fluid reduced survival. Serum albumin also stimulated motility; it delayed, but did not prevent, the detrimental effect of seminal plasma, although it had no effect itself on survival. The effects of epididymal plasma, seminal plasma and serum albumin on surface properties of epididymal spermatozoa, i.e. agglutination, sticking-to-glass and eosinophilia, were also noted. These varied between species and there was no correlation between these effects and the effects on motility and survival.

Animals↗
PubMed1978

The activation of proacrosin in spermatozoa from ram bull and boar.

Acrosin activity was estimated in fractions from washed ram, bull and boar spermatozoa that had been disrupted using a Stansted Cell Disruptor. When p-aminobenzamidine was included in the medium during disruption, all the acrosin (acrosomal proteinase, EC 3.4.21.10) was recovered as its inactive zymogen form, proacrosin. But if spermatozoa were damaged before disruption, of were disrupted in the absence of p-aminobenzamidine, considerable amounts of active acrosin were detectable. It was concluded that conversion of proacrosin to acrosin takes place in spermatozoa only after the acrosome has been rutured. In a sucrose medium, all the proacrosin was bound to the sperm heads. Conversion to acrosin took place readily with all components in a bound state. Using arm sperm heads, the conversion was found to be relatively insensitive to pH, proceeding rapidly above pH 6.5; the rate of conversion was not affected by physiological levels of Ca2+, Mg2+, or Zn2+, although elevated ionic strength caused a solubilization of the acrosin activity and some slowing of the rate. Electrophoretic analysis revealed that several active forms of acrosin were involved, but the final product was a single stable form. Final levels of the active acrosin (expressed as mu mol N-alpha-benzoyl-L-arginine ethyl ester utilised/min per 10(9) heads) were: ram 26.2; bull, 15.9; boar, 133.8. But active site titration revealed that these different levels were not reflected in the numbers of active enzyme molecules on the sperm head; boar acrosin appears to be about three times more active towards benzoyl-arginine ethyl ester than do the acrosins from the other species.

Acrosin↗
PubMed1978

The validity of determinations of pulmonary wedge pressure during mechanical ventilation.

Changes in the mean pulmonary wedge pressure were measured during temporary disconnection from a ventilator in 29 patients to assess the effects of therapy with controlled-volume ventilation on determinations of pulmonary wedge pressure. In 16 observations performed during therapy with intermittent positive-pressure ventilation, the mean value for the pulmonary wedge pressure was the same (10.3 mm Hg) with the patients connected to or disconnected from the ventilator. Thirteen of the patients were also maintained on therapy with positive end-expiratory pressure (PEEP); the mean (+/- SD) of 17 measurements of pulmonary wedge pressure did not show a significant variation on cessation of mechanical ventilation (12.5 +/- 6.7 mm Hg vs 11.7 +/- 6.9 mm Hg; P greater than 0.05). We conclude that pulmonary wedge pressure can be measured accurately at the end of exhalation during the administration of positive-pressure ventilation with 10 cm H2O of PEEP. The suggested practice of discontinuing mechanical ventilation in order to obtain a more exact measurement is not warranted.

Blood Pressure↗
PubMed1978

Effect of ionic strength, serum albumin and other macromolecules on the maintenance of motility and the surface of mammalian spermatozoa in a simple medium.

The seminal plasma in sperm suspensions from boar, bull, rabbit, ram and stallion was replaced with simple defined media as completely as possible by a combination of centrifugation through Ficoll and dilution. After this process, motility declined and the cells showed a tendency to agglutinate and/or stick to glass. Varying the ionic strength of the medium had little effect upon these parameters but sperm motility was preserved better in the presence of serum albumin. When a number of purified proteins and other macromolecules were tested individually in this way for their motility-preserving ability, bovine or human serum albumin was consistently the most effective. Defatting the albumin or altering its nature by mild reduction, oxidation or alkylation had little detectable effect on its motility-preserving ability; the protein did not appear to be acting as a chelator of metal ions, for it could not be replaced by EDTA. The response of the spermatozoa to replacemrnt of seminal plasma varied between species: bull spermatozoa were particularly sensitive and serum albumin had little effect upon their subsequent motility.

Animals↗
PubMed1976

A highly efficient method for washing mammalian spermatozoa.

A simple method has been developed for washing spermatozoa: the cell suspension is layered over a solution containing Ficoll and, after centrifugation, the original suspending medium remains as an undiluted layer above the Ficoll solution while the spermatozoa form a loose pellet at the bottom. Removal of the supernatant layers is easily and completely accomplished by aspiration. When ram spermatozoa were washed by this method, as much as 99-6% of the original medium could be removed during a single washing cycle, while up to 98% of the cells were recovered. Mechanical damage to the cells was minimal and repeatability was high.

Animals↗