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Biomedical subjects

L Pederson

Publications and source records attributed to L Pederson.

8 recordsLinked to original sources
PubMed1991

Calcitonin, an important factor in the calcemic response to parathyroid hormone in the rat.

The role of calcitonin on the calcemic response to parathyroid hormone (PTH) in renal failure has not been evaluated previously. Often animal studies evaluating the calcemic response to PTH in renal failure are performed in thyroparathyroidectomized (TPTX) animals, and thus eliminate any potential physiologic effect of calcitonin. In addition, parathyroidectomy (PTX), presumably by reduction of high PTH levels, has corrected the calcemic response to PTH in animals with renal failure. The present study was designed to evaluate the effect of endogenous calcitonin production on the calcemic response to PTH in rats with renal failure and secondary hyperparathyroidism, and in rats with normal renal function with diet induced hyperparathyroidism. Four groups of rats were evaluated: 1) chronic renal failure plus TPTX with autotransplant of the parathyroid gland, (CT-) CRF; 2) chronic renal failure plus selective PTX with autotransplant of the parathyroid gland, (CT+) CRF; 3) normal renal function plus TPTX with autotransplant of the parathyroid gland, (CT-) NRF; and 4) normal renal function plus selective PTX with autotransplant of the parathyroid gland, (CT+) NRF. Renal failure was surgically induced by a two-stage 5/6 nephrectomy, and exogenous thyroxine was administered to the two thyroidectomized (CT-) groups. Hyperparathyroidism was induced with a high phosphate diet (1.2%), and thus at the time of PTH infusion, PTH levels were (CT-) CRF 84 +/- 16, (CT+) CRF 89 +/- 21, (CT-) NRF 37 +/- 7, and (CT+) NRF 31 +/- 4 pg/ml, respectively (normal 21 +/- 3 pg/ml). Rat 1-34 PTH (2.6 U/hr) was infused for 48 hours via a subcutaneously implanted Alzet pump.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

A longitudinal study of smoking status and weight loss following gastroplasty in a group of morbidly obese patients.

A study of morbidly obese patients was carried out to determine the frequency of preoperative smoking, the effect of smoking status on weight loss after vertical banded gastroplasty, and the effect of gastroplasty on postoperative smoking. There were 93 of 104 eligible patients (89.4 percent) available for study, 86 percent female and 14 percent male. All had a gastroplasty more than one year before with a mean follow-up of 22.9 +/- 7.8 months. Preoperative and postoperative weights were 124.4 +/- 19.5 kg and 89.4 +/- 17.9 kg for females and 156.5 +/- 22.3 kg and 102 +/- 17.4 kg for males. Preoperatively 38 percent smoked (females 36.7 percent, males 46.2 percent) and 57 percent were heavy smokers (greater than 25 cigarettes per day). Ten smokers quit postoperatively but seven nonsmokers started smoking. Those who smoked before operation lost more weight (43.26 kg) than nonsmokers (34.97 kg) and ex-smokers (32.41 kg); P less than 0.05. Those who smoked postoperatively lost more weight (44.47 kg) than nonsmokers (35.06 kg) and ex-smokers (33.07 kg); P less than 0.05. Because of the health risks of smoking, cessation is encouraged in spite of the advantage in weight loss for smokers after gastroplasty. More effective methods of controlling smoking and severe obesity are needed.

Adult↗
PubMed1987

Smoking habits of the morbidly obese prior to gastroplasty.

Smokers weigh less on average than nonsmokers, but there is little data on the smoking habits of the severely obese. Cigarette smoking increases the risk of cardiovascular disease and may add to the existing risk among obese individuals. The purpose of this article is to report on smoking habits of a group of morbidly obese individuals being considered for surgery, to compare these smoking levels to those in the general population, and to assess the relationship between smoking and hypertension in this group. In Canada as in other countries, smoking prevalence has decreased in recent years, but it remains a major health problem.

Adolescent↗
PubMed1987

Smoking status among a group of morbidly obese men and women referred for gastroplasty.

The smoking habits of all morbidly obese patients referred for possible gastroplasty (between January 1, 1983 and December 31, 1985) were assessed. There were 240 patients, 198 women 83 percent) and 42 men (17 percent). Mean age for women was 38 +/- 9 years and weight 121 +/- 17 kg. Men were 36 +/- 9 years old and weighed 154 +/- 24 kg. Forty percent of each group smoked cigarettes daily and 10 percent of women and 12 percent of men were ex-smokers. Twenty percent of the females and 47 percent of the males were heavy smokers (greater than 25 cigarettes per day). Female ex-smokers were much more apt to be on treatment for hypertension than non-smokers (55 vs 10 percent, P less than 0.001). These morbidly obese patients in Southern Ontario smoked more heavily and in higher proportion than reported for adults in Ontario or Canada. Low socioeconomic status may partially explain these results. Better methods of controlling smoking and eating are needed for the morbidly obese.

Adult↗
PubMed1985

Monaural and binaural adaptation in sequence: SDLB analogue?

Magnitude estimates (M.E.) of loudness of a 1-kc/s tone in the R ear at 60 db SPL were required over three 3-phase sessions from 15 normal-hearing young adults. The initial tone in the session was arbitrarily assigned a value of "60 units" in instructions to the S. The session was arranged to be analogous to that commonly used in Simultaneous Dichotic Loudness Balancing (SDLB). In a baseline Phase I in any of 3 sessions both ears received identical, simultaneous, intermittent stimulation. In each session, one of 3 duty cycles (randomized) were used (all on-times of .5 sec, off-times of .5, 4.5, or 24.5 sec). An M.E. judgment was requested every 10 sec for just over 1 min. Then immediately in Phase II the L ear received nothing while the R ear received continuous stimulation at 60 db SPL for 7 min, with M.E. Judgements requested every 10 sec during Min 1 and every min thereafter. Then in Phase III the R ear continued to receive continuous stimulation at 60 db SPL for 1 min while in the contralateral ear the condition of Phase I was re-introduced. M.E. loudness judgements for the R ear were requested as in Phase I. During Phase I there was, as expected, no loudness adaptation. During the adapting Phase II, M.E. group values declined progressively and significantly, but without significant differences among duty cycles. M.E. values in Phase III continued to decline significantly even though the contralateral ear was being given intermittent stimulation (irrespective of duty cycle). Previous studies had found that, for most listeners, M.E. loudness adaptation does not occur when the continuous stimulation is presented by itself. As far as is known, the present study is the first M.E. loudness adaptation study to present binaural intermittent stimulation before the continuous monaural stimulus. It is suggested that the redundancy of the continuous monaural stimulation, in comparison with the similar intermittent stimulus, is associated with the diminution of loudness.

Adaptation, Physiological↗
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