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Biomedical subjects

P Hessel

Publications and source records attributed to P Hessel.

7 recordsLinked to original sources
PubMed1993

Hyperparathyroidism induced by hypothyroidism.

The coexistence of hyperparathyroidism and thyroid tumors and/or chronic thyroiditis has raised the possibility of an etiologic relationship. The present study was designed to test the hypothesis that the chronic elevation of thyroid-stimulating hormone (TSH) is related to the development of hyperparathyroidism. Three groups of 24 rats each were treated for 12 weeks as follows: group 1 received propylthiouracil (PTU) in their deionized water; group 2 received PTU and thyroid hormone to suppress TSH and to serve as a control group for possible direct effects of PTU; and group 3 was not treated at all and served as another control group. At 12 weeks, 95% of group 1 rats (PTU only) showed hyperplasia of the parathyroids with a 30% mean increase in circulating parathormone.

Administration, Oral↗
PubMed1992

Canadian heart health surveys: a profile of cardiovascular risk. Survey methods and data analysis. Canadian Heart Health Surveys Research Group.

OBJECTIVE: To describe the methods used in nine provincial surveys carried out as part of the Canadian Heart Health Initiative. DESIGN: Population-based cross-sectional surveys, following a core standardized protocol, implemented by provincial departments of health in collaboration with Health and Welfare Canada. Data were obtained through a home interview and a clinic visit. A standard manual of field operations and standardized training procedures were used in all provinces. SETTING: Nine Canadian provinces during the period 1986 to 1990. PARTICIPANTS: A probability sample of 26,293 men and women aged 18 to 74 years was selected from the health insurance registries in each province. Over 30% of the participants had post-secondary education. About 50% were 18 to 34 years old. OUTCOME MEASURES: Data on sociodemographic characteristics, hypertensive and diabetic status, knowledge and awareness of the causes and consequences of cardiovascular disease and two blood pressure measurements were obtained in a home interview. During a clinic visit, data were collected on height, weight (waist and hip circumferences in four provinces), two blood pressure measures and a blood sample. Total plasma cholesterol, triglycerides and high- and low-density lipoprotein cholesterol were measured in the Lipid Research Laboratory, University of Toronto and St. Michael's Hospital. MAIN RESULTS: Of the subjects invited to participate in the survey, 78% were interviewed, 69% attended the clinic and 64% provided a fasting specimen (8 hours or more). The response rates were slightly lower for men aged 18 to 34, for women aged 65 to 74 and for those with fewer years of education. Data from the provincial surveys (Ontario will complete the survey in 1992) are being compiled in the Canadian Heart Health Database. CONCLUSION: The process followed in the implementation of the provincial heart health surveys is a model of how provincial departments of health may carry out epidemiologic investigations in support of their mandate. The approach illustrates how a country-wide database can be built through partnerships among different levels of government. The use of community health nurses was instrumental in the efficient implementation of the surveys and in the realization of the relatively high rates of response attained.

Adult↗
PubMed1991

High phosphate diet-induced primary hyperparathyroidism: an animal model.

Primary hyperparathyroidism (PHPT) is increasing in incidence and detection, primarily because of the aging of our population and the widespread use of automated serum calcium determination. As a result, a substantial number of "early" cases or "biochemical" PHPT are being detected. The indications for parathyroidectomy in such early cases of PHPT are currently under debate, primarily because of economic issues. These factors underscore the importance of research into the basic mechanisms and natural history of PHPT. We investigated an animal model of diet-induced PHPT that retains two crucial aspects of PHPT: elevation of endogenously produced parathyroid hormone (PTH), accompanied by gross and microscopic changes in the native parathyroid glands. Female Long-Evans rats were divided into six groups of 15 each and fed a control diet (Ca/P of 1:2) or a high-phosphate diet (Ca/P of 1:7) for 1-, 2-, or 3-month intervals. Compared with the control animals, serum PTH levels were elevated at all three time intervals in the experimental group, whereas serum calcium levels were decreased at all time intervals. Serum creatine levels were also elevated at all time intervals, whereas serum phosphorus levels did not change. Parathyroid histopathologic studies demonstrated no change at 1 month, whereas nine of 15 experimental animals showed mild hyperplasia at 2 months and 13 of 14 showed mild to moderate hyperplasia with gland enlargement at 3 months compared with control animals. Histopathologic examination of the kidneys showed no change at 1 month but focal parenchymal inflammation with calcium deposition at 2 and 3 months in the experimental groups. In conclusion, the high-phosphate diet successfully induced the earliest changes of PHPT: elevated PTH levels and parathyroid hyperplasia. However, because renal function was mildly compromised early on, some element of early secondary (renal) hyperparathyroidism may have supervened quickly. Because this model is simple, it may be useful to investigate this complex syndrome further, as well as its natural history and the complications it produces in other organs such as the kidneys.

Animals↗
PubMed1990

Parathyroid autotransplantation in total thyroidectomy.

Although parathyroid autotransplantation during the course of thyroidectomy was first described by Halsted in 1907, it is only during the past 20 years that this simple and effective method of preserving parathyroid function is being used by an increasing number of surgeons. Our group has autotransplanted normal parathyroids since 1965, whenever these glands could not be preserved in situ with adequate blood supply. With increasing experience, we find it much simpler to autotransplant parathyroid glands attached to the thyroid, than to dissect their precarious blood supply, hoping they will survive postoperative edema and fibrosis. Furthermore, it is our impression that in operations for thyroid carcinoma, attempts to preserve the blood supply to the parathyroids may compromise the completeness of the thyroidectomy or of the dissection of cervical nodes in the tracheoesophageal groove. In a review of our experience during the past four years (January 1, 1984 to December 31, 1988), 87 patients underwent total thyroidectomy. Parathyroid glands that could not be saved in situ were biopsied to confirm their identity by frozen section and autotransplanted in the ipsilateral sternocleidomastoid muscle. Among the 87 patients undergoing total thyroidectomy, 34 required no autotransplantation, whereas 52 had one to three glands autotransplanted, and one had four glands autotransplanted. Postoperatively, 23 patients (26 percent) developed hypocalcemia, whereas 18 required CaCO3 and five required vitamin D in addition. All patients (98%) except two had normal parathyroid function at four-month follow-up and thereafter, as judged by serum calcium, phosphorus and parathormone, when indicated.

Adult↗
PubMed1989

Altered TSH levels associated with increased serum 1,25-dihydroxyvitamin D3: a possible link between thyroid and parathyroid disease.

The physiologic relationship between the thyroid and parathyroid glands remains poorly understood. A high incidence of coexistent thyroid disease and primary hyperparathyroidism has been well documented. Elevation of serum 1,25-dihydroxyvitamin D3 (vitamin D) has been detected in some patients with primary hyperparathyroidism. A report of specific binding sites and uptake of vitamin D by the thyrotrophs of the anterior pituitary indicates that vitamin D may modulate production or secretion of thyroid-stimulating hormone (TSH). To test this concept, we investigated the influence of elevated serum levels of vitamin D on basal and stimulated TSH. Vitamin D was administered by subcutaneously implanted sustained-release pellets at four dosages. Thyrotropin releasing hormone (TRH) stimulation tests were performed at time zero, 72 hours, 1 week, 2 weeks, and 5 weeks. Animals administered vitamin D became significantly hypercalcemic and demonstrated elevations of vitamin D, which peaked at 72 hours and remained elevated for 2 weeks after pellet implantation. TRH-stimulated TSH levels were significantly elevated at 72 hours and at 1 week and returned to normal after 5 weeks. Parathyroid hormone levels were suppressed at 72 hours and at 1 week and displayed significant elevation at 2 weeks. These results provide in vivo evidence for an interaction and a possible regulatory role of 1,25 on pituitary TSH secretion and parathyroid function.

Animals↗
PubMed1985

Cellular responses elicited by insulin mimickers in cells lacking detectable plasma membrane insulin receptors.

Madin-Darby canine kidney (MDCK) cells were previously shown to have few or no plasma membrane insulin binding sites (Hofmann et al: J Biol Chem 258:11774, 1983]. Accordingly, neither insulin-stimulated incorporation of [14C]glucose into glycogen, nor insulin-induced uptake of radiolabeled alpha-aminoisobutyrate ([3H]AIB) could be demonstrated. To probe for receptors, MDCK cultures were surface-labeled with Na125I or were labeled with [35S]methionine. When solubilized cells were immunoprecipitated with sera containing antibodies to the insulin receptor, and immunoprecipitates were analyzed on SDS-gel electrophoresis, no evidence for insulin receptor components was found. Also, when intact MDCK cells wee incubated first with serum containing antibodies to the insulin receptor and then with 125I-protein A, no radiolabeling of insulin receptors occurred. Various agents reported to have insulin-like activity were tested on MDCK cells. The insulinomimetic lectins concanavalin A and wheat germ agglutinin as well as hydrogen peroxide enhanced incorporation of [14C]glucose into glycogen and induced stimulated [3H]AIB uptake, whereas trypsin, vanadate, and serum containing antibodies to the insulin receptor were without effects. Altogether, these results showed that MDCK cells had few or no insulin receptors and were correspondingly insulin-insensitive. However, since insulin-associated responses could be elicited by some insulin mimickers, the post-receptor limb of response in MDCK cells was apparently intact.

Animals↗