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Biomedical subjects

H Nyborg

Publications and source records attributed to H Nyborg.

17 recordsLinked to original sources
PubMed1992

Racial/ethnic variations in male testosterone levels: a probable contributor to group differences in health.

Racial and ethnic variations in serum testosterone levels were investigated among a large sample of male Vietnam era veterans. Based on geometric means, significant average differences were found between 3,654 non-Hispanic white and 525 black individuals. The geometric mean for testosterone levels among 200 Hispanic individuals was similar to that of non-Hispanic white individuals. Regarding two other racial/ethnic groups (Asian/Pacific Islanders and Native Americans), no significant differences were found, due perhaps to small sample sizes. Results were interpreted as having considerable potential for explaining some of the race differences in the incidences of cardiovascular diseases, hypertension, and prostate cancer.

Adult↗
PubMed1991

Neonatal hyperthyroidism disrupts hippocampal LTP and spatial learning.

Excess thyroid hormone at an early stage of development produces marked neurochemical and morphological alterations in the rat hippocampal formation. In order to better understand the functional significance of these changes, we tested adult rats treated neonatally with triiodothyronine (T3), and their control litter mates, in a spatial learning task and for the induction of long-term potentiation (LTP) in the dentate gyrus (DG) of the hippocampal formation. The T3-treated rats were significantly impaired in their performance on the spatial task in comparison to their matched controls. Similarly, the efficacy of LTP induction was significantly attenuated in the T3-treated animals. Further, a significant correlation was obtained between LTP induction and performance on the spatial learning task. Thus, a brief neonatal excess of thyroid hormone produces impairments in spatial learning along with decreases in LTP, long held as a model of learning and memory. This relationship provides a unique opportunity to study associations between behavioral, physiological, pharmacological and morphological processes intimately associated with the hippocampal formation.

Animals↗
PubMed1979

Critical analysis of a study on field dependence in young children.

Kojima's conclusion that our method of scoring performance in the rod-and-frame test did not produce satisfactory results in young children was invalid because our scoring method was used incorrectly, fallacious reasoning was used to reject our scoring method, subjects were classified wrongly, and the procedure used to test vertical perception in the children probably was unreliable.

Child↗
PubMed1977

Sex chromosome abnormalities and cognitive performance: III. Field dependence, frame dependence, and failing development of perceptual stability in girls with Turner's syndrome.

The Rod-and-Frame Test (RFT) was administered to Turner girls (N = 45), their normal sisters (N = 19), and to nonsiblings with primary amenorrhoea and growth retardation as seen in Turner girls (N = 15). The test was scored by the traditional method which gives a measure of field dependence, as well as by a new method that gives a measure of frame dependence and response inconsistency. The traditional method showed Turner girls to be extremely field dependent. The new method showed that the so-called field dependence in Turner girls was due to response inconsistency, rather than to significant frame dependence. It is concluded that response inconsistency is a characteristic of RFT performance in Turner girls, probably reflecting failing development of "perceptual stability".

Adolescent↗
PubMed1977

Pulpal reaction to polycarboxylate and zinc phosphate cements used with inlays in deep cavity preparations.

The purpose of the present investigation was to compare histologically pulpal reactions beneath inlays cemented with either a zinc phosphate or a polycarboxylate cement. No inflammatory reaction was seen beneath any of the 39 deep cavity preparations in teeth without pulpal lesions and with an inlay cemented with polycarboxylate cement. In the contralateral teeth, under 39 inlays cemented with zinc phosphate cement, an inflammatory reaction was seen beneath two cavity preparations. In one, bacteria were found on the floor of the preparation. On the basis of this result and the findings of our earlier investigations, it may be warranted to conclude that neither the polycarboxylate cement nor the zinc phosphate cement has any notable irritating effect on the pulp. If the irritation occurs after cementation of the restoration, it may be caused by debris containing bacteria and left behind on the prepared surfaces by bacterial growth from the surface of the tooth. The findings underline the importance of removing grinding debris and bacteria before cementation of the restoration.

Acrylic Resins↗
PubMed1976

Pulp reaction to a temporary zinc oxide/eugenol cement.

The pulpal irritation, such as inflammatory reaction and aspiration of pulpal cells, demonstrated after insertion of the zinc oxide/eugenol cement (Nobetec) seems to warrant the following recommendations: (1) A temporary restoration with a zinc oxide/eugenol base should not be inserted in deep cavities without a protective liner or a calcium hydroxide base covering the exposed dentinal tubules. (2) Before the temporary cementing of inlays and crowns with a zinc oxide/eugenol cement, not only should the dentin be properly cleaned and debris removed, but the prepared surfaces should be covered with a calcium hydroxide liner.

Dental Cavity Lining↗