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Biomedical subjects

J Hoover

Publications and source records attributed to J Hoover.

At least 19 recordsLinked to original sources
PubMed1991

Effect of chronobiological alteration of the circadian rhythm of prolactin and somatotropin release in the dairy cow.

The objective of this study was to determine if a skeletal photoperiod administered at the appropriate time of a 24-h day could stimulate prolactin and somatotropin release in dairy cattle. Cows in mo 8 of gestation were exposed to either 12 to 13 h of continuous light or to three skeletal photoperiods consisting of a total of 8 h of light. Cows in the skeletal photoperiod light regimens received 6 h of light from 0500 to 1100 h and a 2-h light pulse at either 1500 to 1700 h, 1800 to 2000 h, or 2100 to 2300 h. Cows exposed to the light regimen pulse at 1800 to 2000 h exhibited a circadian rhythm of prolactin and somatotropin release. The mean prolactin and somatotropin concentrations were also higher in this treatment. It is concluded that a circadian rhythm with a photosensitive phase is present for prolactin and somatotropin release in the lactating dairy cow. The photosensitive phase for both hormones occurs between 13 and 15 h after subjective dawn. The expression of the circadian rhythm of these hormones depends on the photoperiod to which cows are exposed.

Animals↗
PubMed1989

Histological and biomechanical assessment of articular cartilage from stored osteochondral shell allografts.

Normal and stored articular cartilage from the medial tibial plateaus of mature canine knee joints were evaluated histologically and biomechanically. The medial plateaus from the right knee (control) were assessed fresh, while the left (stored) were preserved in culture media at 4 degrees C for 3, 7, 14, or 28 days and then evaluated. Biomechanically, confined compression tests were performed on all specimens to determine the aggregate modulus and apparent permeability of the articular cartilage. Histologically, Safranin O- and hematoxylin and eosin (H&E)-stained sections were evaluated. All stored cartilage specimens had an aggregate modulus on average lower than normal, but the differences were not significant (p greater than 0.10). The apparent permeability was on average higher than but also not significantly different from normal (p greater than 0.10). Time in storage (up to 28 days) did not have a significant effect on the biomechanical properties of stored cartilage normalized by control values (p greater than 0.50). Safranin O and H&E histological evaluation also showed no overall changes in cell appearance or staining of the stored cartilage when compared with control for the time periods studied.

Animals↗
PubMed1989

Periodontal status in a Hutterite population.

The periodontal status of a population of 117 adult Hutterites living in Saskatchewan, Canada, was assessed. Despite poor oral hygiene levels, and inadequate dental knowledge, the presence of periodontitis was low. The findings are in accordance with data obtained recently from other selected populations.

Adolescent↗
PubMed1987

The intelligibility of synthesized speech: ECHO II versus VOTRAX.

The intelligibility of two speech synthesizers [ECHO II (Street Electronics, 1982) and VOTRAX (VOTRAX Division, 1981)] was compared to the intelligibility of natural speech in each of three different contextual conditions: (a) single words, (b) "low-probability sentences" in which the last word could not be predicted from preceding context, and (c) "high-probability sentences" in which the last word could be predicted from preceding context. Additionally, the effect of practice on performance in each condition was examined. Natural speech was more intelligible than either type of synthesized speech regardless of word/sentence condition. In both sentence conditions, VOTRAX speech was significantly more intelligible than ECHO II speech. No practice effect was observed for VOTRAX, while an ascending linear trend occurred for ECHO II. Implications for the use of inexpensive speech synthesis units as components of augmentative communication aids for persons with severe speech and/or language impairments are discussed.

Adult↗
PubMed1983

Effect of estrogen/progestin potency on lipid/lipoprotein cholesterol.

We studied 374 women taking oral contraceptives, 284 women taking estrogen preparations after menopause, and 1086 women taking no hormones, to determine the relation of plasma lipids and lipoprotein cholesterol concentrations to various types of estrogen/progestin formulations. Premenopausal women, using oral contraceptives containing a relatively low dose of estrogen combined with a medium or high dose of progestin (Norlestrin, Ovral, or Demulen) had a 24 per cent higher median concentration of low-density-lipoprotein cholesterol than did those not using hormones (P less than 0.05). Women using oral contraceptives that are high in estrogen and low in progestin (Enovid or Oracon) had significantly higher concentrations of high-density-lipoprotein cholesterol than did nonusers; those using Ovral, a low-estrogen and high-progestin formulation, had significantly lower levels of high-density-lipoprotein cholesterol. In postmenopausal women the use of estrogen was associated with concentrations of low-density-lipoprotein cholesterol that were 11 to 19 per cent below the levels in postmenopausal women who did not use hormones. The effects of estrogen-progestin balance on low-density and high-density lipoproteins may underlie the increased incidence of stroke and myocardial infarction in women of childbearing age who take oral contraceptives.

Adult↗
PubMed1982

Alteration in blood pressures associated with combined alcohol and oral contraceptive use-the lipid research clinics prevalence study.

Alterations in systolic and diastolic blood pressure levels associated with combined oral contraceptive (OC) and alcohol use were investigated in white women 20-49 years of age from 10 North American Lipid Research Clinics study populations. OC users had systolic pressures 2-3 mm Hg higher than non-users, but no difference was noted for diastolic pressures. Among non-OC users, both systolic and diastolic blood pressures were positively associated with reported alcohol consumption, though participants reporting no alcohol use had blood pressures slightly higher than those reporting minimal intake. The blood pressure correlates of OC's and alcohol appeared to be independent, and systolic pressures levels were over 8 mm Hg higher in those reporting heavier alcohol intake and OC use than among those reporting minimal alcohol intake and no OC use.

Adult↗
PubMed1981

Alterations of plasma lipid and lipoprotein levels associated with benzodiazepine use--the LRC Program Prevalence Study.

In a study of white adults from 10 North American Lipid Research Clinics populations, plasma lipid and lipoprotein levels in benzodiazepine (diazepam, chlordiazepoxide, flurazepam) users were compared to both the entire population of non-users and matched control non-users. Significantly higher plasma triglyceride and very low density lipoprotein cholesterol levels and by one method of analysis, lower high density lipoprotein cholesterol levels were noted in male benzodiazepine users. No significant differences were noted in total plasma cholesterol or low density lipoprotein cholesterol levels.

Adult↗
PubMed1980

Alterations of plasma high-density lipoprotein cholesterol levels associated with consumption of selected medications. The Lipid Research Clinics Program Prevalence Study.

From the 10 North American study populations of the Lipid Research Clinics Program, mean levels of plasma high-density (HDL) cholesterol were contrasted between users of eight categories of prescribed medications and a control group of nonusers of those categories matched for age, sex, study population and ponderosity. Women taking propranolol had a mean HDL cholesterol level 12 mg/dl lower than nonusers (p < 0.05). Men taking phenytoin had a mean HDL cholesterol level more than 18 mg/dl higher than nonusers (p < 0.05). Men taking benzodiazepine derivatives had a mean HDL cholesterol level 3.3 mg/dl lower than nonusers (p < 0.05). No significant differences were found between users and nonusers of thiazide diuretics, chlorthalidone, barbiturates, sympathomimetics or antihistamines.

Barbiturates↗
PubMed1979

Altered plasma lipid and lipoprotein levels associated with oral contraceptive and oestrogen use. Report from the Medications Working Group of the Lipid Research Clinics Program.

In a study of women attending ten North American Lipid Research Clinics plasma total cholesterol, triglyceride, low density (L.D.L.), very low density (V.L.D.L.), and high density (H.D.L.) lipoprotein levels in those taking oral contraceptives (O.C.) and in those taking oestrogens for menopausal symptoms were compared with those in women not taking gonadal hormones, after adjustment for age, educational attainment, and body-mass index, O.C. and oestrogen users were leaner than non-users. Compared with controls, O.C. users showed increased cholesterol, triglyceride, and L.D.L.-cholesterol and V.L.D.L.-cholesterol levels, but H.D.L.-cholesterol levels were similar. Cholesterol, triglyceride, and H.D.L.-cholesterol and V.L.D.L.-cholesterol levels were positively associated with the quantity of the oestrogen component of the O.C. preparations. Compared with non-users, menopausal oestrogen users had slightly lower cholesterol and triglyceride levels, significant decreases in L.D.L.-cholesterol and V.L.D.L.-cholesterol, and a significant increase in H.D.L.-cholesterol.

Adolescent↗
PubMed1977

Altered plasma-lipids associated with oral contraceptive or oestrogen consumption. The Lipid Research Clinic Program.

Mean plasma cholesterol and triglyceride concentrations were measured in White female users and non-users of oral contraceptives and oestrogens in 10 diverse, demographically defined North American populations. About 50% of the younger women (20-24 years old) were taking oral contraceptives. In these women mean triglyceride concentrations were up to 48% higher and mean cholesterol concentrations were about 5% higher than in non-users. The 95% percentile of the total lipid distribution among non-users was used to define hyperlipidaemia. In young women on oral contraceptives hypercholesterolaemia was up to three times more common and hypertriglyceridaemia was up to five times more common than in non-users. 37% of older women (50-54 years) (presumably intramenopausal and postmenopausal) were hormone users, and in this group there were small, inconsistent alterations in plasma-triglyceride and a modest but consistent reduction in mean cholesterol concentration.

Adolescent↗