Biomedical subjects
Publications and source records attributed to B Ritchie.
The authors describe a rare case of priapism in a newborn infant. Treatment with intravenous ketamine hydrochloride produced rapid detumescence. The literature is reviewed with respect to priapism in the newborn and its management, and the authors propose injection of ketamine hydrochloride as an alternative method of management for this condition in newborn infants.
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The Neodymium YAG laser energy source can be readily adapted for cystoscopic use by some simple modifications of existing urologic equipment. Both the fiberoptic resectoscope and a deflecting cystourethroscope have been adapted for this purpose. Fixation of the fiber tip 1 cm. from the target and use of a divergent beam of 36 degrees allows the delivery of standardized dosage to a relatively large bladder tissue volume. Animal experiments involving 35 mongrel dogs established that repetitive overlapping doses of 200 joules ech can successfully treat a large area of bladder resulting in a full thickness bladder wall injury. This technique has been used in 4 high risk patients with infiltrating bladder cancer without adverse sequelae. The ability to reliably produce a full thickness lesion may give this modality a therapeutic advantage over conventional cautery techniques especially for the treatment of residual infiltrative carcinoma.
Dunning R3327H prostatic adenocarcinoma was bilaterally transplanted in the flanks of animals at the Papanicolaou Institute in Miami, and the animals were received at the Cross Cancer Institute (Edmonton, Alberta, Canada) each month. The animal flanks were palpated weekly, and when tumor volumes reached a size of approximately 300 mm3 the animals were randomized into treatment groups for the assessment of various therapies. Tumor volumes were determined each week before and after various treatments, and tumor growth was compared to that in untreated controls. Ionizing radiation at relatively small single doses completely inhibits tumor growth for a period of up to 6 months. Some interesting characteristics of this radiation-induced growth arrest are that tumors do not die and shrink away as with some other tumor models but remain static in size and show histologic evidence of viable tumor cells. The hypoxic cell radiosensitizer misonidazole potentiates radiation response in this tumor model. Cisplatin, vincristine, etoposide, and estramustine phosphate administered in drug doses approaching their toxic limits have a partial effect on tumor growth.
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Development of autonomic nervous control of basal heart rate was studied in unanesthetized fetal lambs (93 days to term) and newborn lambs (2--29 days), using atropine and/or propranolol blockade. Fetal lambs showed a progressive increase in parasympathetic restraint of heart rate; vagal influence in the newborn lamb was similar to the term fetus. Sympathetic stimulation of fetal heart rate declined toward term, possibly due to the strongly increasing parasympathetic influence. Sympathetic influence in the newborn was similar to the early-gestation fetus. Intrinsic heart rate was about 185 beats/min throughout the fetal and newborn life span studied. Thus changes in basal heart rate resulted from a different balance of the sympathetic and parasympathetic components of the autonomic nervous outflow.
The immediate transient baroreceptor sensitivity was measured in 9 conscious fetal and 7 conscious newborn lambs for periods of at least 35 days following bolus injections of phenylephrine (20-50 mug/kg). Mean sensitivities were unchanged throughout gestation from 105 days at 6.7 +/- 0.4 msec/cm H2O (n = 45) and were insignificantly different from those in the newborn period, 5.9 +/- 0.4 msec/cm H2O (n = 78). In contrast, baroreflex sensitivities were less in 2 fetuses and 2 newborn lambs when pressures were increased by chronically implanted thoracic aortic balloon cuff; they were 3.03 +/- 0.11 (n = 127) and 0.91 +/- 0.11 msec/cm H2O (n =61), respectively. "Steady-state" heart period-arterial pressure curves indicate that the baroreflex operates down to levels of 40 cm H2O in the fetus which is lower than that achieved in the adult of other species, rabbit and man.
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