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Biomedical subjects

D R Kennedy

Publications and source records attributed to D R Kennedy.

13 recordsLinked to original sources
PubMed1988

Dating infidelity: behaviors, reasons and consequences.

Older adolescents were surveyed concerning three issues: behaviors which constitute infidelity in a dating relationship, reasons for a dating partner to be unfaithful, and reactions to a dating partner's infidelity. Responses from 247 participants indicated more similarities than differences between dating infidelity and extramarital affairs with regard to behaviors, causes, and consequences. Results are discussed in terms of similarities between dating and marital infidelity, and the rationale for professionals to interact with adolescents concerning the potential long-term consequences of dating infidelity.

Adolescent↗
PubMed1987

A comparison of two radiological path length algorithms.

Most radiation therapy dose calculation methods require the determination of the effective path length of the primary radiation from the radiation source to the point at which the dose is calculated. This usually involves representing the patient anatomy as a set of polygons (contours) as approximations to plane curves. Several algorithms are known for determining the length of a segment or segments on a ray through a planar contour, that are interior to the contour. We have implemented two of these algorithms in a test program to benchmark their relative efficiency. One algorithm uses a linear search over all the contour segments, and the other method represents the contour as a binary tree of "strips," of successively increasing resolution. In general, the tree search should give times proportional to log(n) where n is the number of contour segments, and the linear search time should be proportional to n. Thus, one might expect the tree search to run faster once the number of segments reaches some sufficiently large value. We found that this value is a number of contour points far in excess of that typical for contours representing radiation therapy patient anatomy. Therefore, for this application the linear search method is more efficient.

Algorithms↗
PubMed1978

Adrenergic influences on rabbit oviduct: effect of muscle size and ovarian hormones.

This study attempts to distinguish between a direct action of ovarian steroids on adrenergic neurons in the oviduct and an indirect effect mediated by changes in muscle size. Mature rabbits were treated as follows: group 1, ovariectomized and a polyethylene catheter (1 mm OD) inserted into isthmus of one oviduct (CT) with contralateral oviduct as control (C); group 2, normal, estrous animals with one intubated isthmus (ET) and contralateral control (E). Fourteen days postoperatively, oviducts were removed and muscle-wall thickness, norepinephrine (NE) content, and response to nerve stimulation were measured. Although castration atrophy was prevented in CT, NE content of CT was significantly less than C, 0.032 +/- 0.07 versus 1.09 +/- 0.10 nmol. NE content of ET was also significantly less than E (1.32 +/- 0.03 versus 1.81 +/- 2.0) despite a greater wall thickness of ET. It was concluded that: a) withdrawal of ovarian hormones reduces NE contents by a direct action on nerves; b) moderate stretch, per se, increases muscle size and reduces NE content; c) nerve stimulation induces muscle contraction despite large reduction in transmitter content.

Adrenergic Fibers↗
PubMed1977

The surgical treatment of retrocaval ureter.

Ureteric obstruction resulting from retrocaval ureter may be due to either compression of the ureter by the vena cava or stenosis of the postcaval segment. If obstruction is due to stenosis, the commonly described operation of division and anastomosis through the proximal dilated ureter or pelvis, after repositioning of the ureter, is likely to fail, as is division of the vena cava itself. Excision of the postcaval segment with anastomosis of the spatulated ureter over a Silastic splint is therefore recommended. Three case histories of patients with retrocaval ureter treated surgically are presented and support this view.

Adult↗
PubMed1977

Thyroid cold acclimation influences on norepinephrine metabolism in brown fat.

Norepinephrine turnover rates and tyrosine hydroxylase activities were determined in the interscapular brown fat pad of the rat during cold acclimation, hyperthyroxinism, and after thyroidectomy. Rats were cold acclimated by placement in a cold room, one rat to a cage, for a period of 6 wk. Hyperthyroxinism was induced by daily subcutaneous injections of L-thyroxine (1 mg/kg) for 6 days. Norepinephrine turnover rate and enzyme activity were determined at the end of each experimental period and at 8 wk after thyroidectomy. The rate of norepinephrine turnover increased during cold acclimation and hyperthyroxinism and decreased after thyroidectomy. Cold acclimation resulted in a significant increase in tyrosine hydroxylase activity, whereas no significant effect on enzyme activity was observed in hyperthyroxinism or after thyroidectomy. None of the conditions produced a change compared to controls in the apparent Km of tyrosine hydroxylase for L-tyrosine. Cold acclimation resulted in a significant decrease in the apparent Km of tyrosine hydroxylase for pterin cofactor, whereas thyroxine treatment and thyroidectomy had no effect.

Acclimatization↗