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Biomedical subjects

R Howard

Publications and source records attributed to R Howard.

13 recordsLinked to original sources
PubMed1979

Dolphin lung collapse and intramuscular circulation during free diving: evidence from nitrogen washout.

Intramuscular nitrogen tensions in Tursiops truncatus after a schedule of repetitive ocean dives suggest a lung collapse depth of about 70 meters and suggest that intramuscular circulation is maintained during unrestrained diving in the open ocean. Therefore, the bottle-nosed dolphin is not protected by lung collapse from the decompression hazards of dives to depths shallower than 70 meters.

Adipose Tissue↗
PubMed1979

Contingent negative variation and evoked potential amplitude as a function of inspired nitrous oxide concentration.

Nine subjects were given to breath 10%, 20%, 30% and 40% nitrous oxide in oxygen. The inhaled gas concentrations were monitored by a mass spectrograph. At each gas concentration the CNV was measured in a standard long S1-S2 CNV paradigm to a click and tone with a mandatory button press at S2. The results confirmed the previous observations of Lader and Morris (1974) that the cortical evoked potential decreases rapidly with increasing concentrations of nitrous oxide. The CNV, however, against prediction remains surprisingly well preserved up to the borders of unconsciousness. In this situation there is little correlation between CNV amplitude and attention, arousal or reaction time.

Adult↗
PubMed1977

G2+M arrest of cultured mammalian cells after incorporation of tritium-labeled nucleosides.

Novikoff rat hepatoma cells were propagated in suspension cultures containing 0.5 to 10 muC of 3H-methyl-thymidine, 3H-5-uridine, 3H-G-adenosine or 3H-8-adenine. The presence of the 3H-labeled precursors caused an inhibition of cell replication which was due to a delay or arrest of the cells in G2 and M. The degree of inhibition was proportional to the amount of radioactivity incorporated into nucleic acids. Almost immediate and complete inhibition resulted from incubation with 10 muC 3H-thymidine/ml. The presence of 0.5 muC 3H-thmidine/ml caused a significant increase in the relative proportion of cells in G2+M, even though the population doubling time of the culture appeared to be unaltered.

Adenine↗
PubMed1976

Vesicocolonic fistulas in diverticulitis.

Diverticulitis is a disease affecting patients in the fifth to sixth decades. The charts of 12 patients with cesicocolonic fistulas secondary to diverticulitis were reviewed. Their presentation was primarily urological with pneumaturia present in 10 of 12 patients and fecaluria present in 5 of 12. The process of fistulization occurs in stages. If the incipient stage can be identified early fistulization can be prevented and the morbidity and mortality rates will be reduced significantly. In older patients with bladder irritation (with or without positive urine cultures) a high degree of suspicion for diverticular disease will ensure an accurate diagnosis earlier. Patients with penumaturia or fecaluria present less of a diagnostic challenge. Cystoscopy is a reliable procedure and we recommend its use in discovering a vesicocolonic fistula. Surgical therapy should be individualized for each patient and good results were obtained with primary resection as well as staged repair.

Aged↗