The Svalbard Study: risk of coronary heart disease at 78 degrees north.
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Adult↗
Biomedical subjects
T Brenn
Publications and source records attributed to T Brenn.
The Svalbard Study: increased body weight at 78 degrees north.
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Adult↗
The Tromsø Study. Distribution and population determinants of gamma-glutamyltransferase.
Gamma-glutamyltransferase was measured in 10,942 males aged 12-62 years and 10,840 females aged 12-59 years screened in a health survey program. The distribution was right-skewed, with medians of 17 and 12 units/liter for males and females, respectively. Fewer than 5.5% of the males and 1.5% of the females had values exceeding 50 units/liter, reflecting the modest use of alcohol in Norway. In sex-specific multiple regression analyses, gamma-glutamyl-transferase showed a strong positive association with body mass index, alcohol use, and total serum cholesterol and a somewhat weaker positive association with serum triglycerides, high density lipoprotein cholesterol, heart rate, blood pressure, use of analgesics, and time since last meal. Strong negative associations were found for coffee consumption, hour of the day at which the examination was performed and, in males, physical activity. In females, use of oral contraceptives and menopause were positively associated with gamma-glutamyltransferase, whereas pregnant females had lower values. In conclusion, the gamma-glutamyltransferase level in the Tromsø population was low, with marked and consistent sex differences which probably are physiologic. Within its normal range, gamma-glutamyltransferase has many other, even stronger determinants than alcohol consumption.
Adolescent↗
Midwinter insomnia in the subarctic region: evening levels of serum melatonin and cortisol before and after treatment with bright artificial light.
"Midwinter insomnia" (MI), mainly characterized by difficulties in falling asleep at night, is a common complaint during the period of obscuration or "dark period" north of the arctic circle. We hypothesize that MI is a result of a phase delay of the sleep-wake cycle due to insufficient exposure to daylight. In the present study based on this hypothesis, we wanted to find out whether otherwise healthy subjects with MI show abnormalities in the endocrine markers melatonin and cortisol late in the evening, and whether exposure to intensive light for one half hour in the morning for 5 days has any effect on the insomnia and on the endocrine variables. Nine subjects with typical MI were compared to eight controls. Before light exposure, the MI group had a significantly lower level of plasma melatonin in the evening than the controls, and a nonsignificant increase of plasma cortisol. After light exposure, the following results were seen in the MI group: sleep latency was moderately but significantly shortened, plasma melatonin increased to the same level as in the controls, and there was a nonsignificant increase of plasma cortisol. These results are largely in accordance with the predictions made from the phase delay hypothesis. However, other explanations cannot be ruled out.
Adult↗
The Tromsø heart study: alcoholic beverages and coronary risk factors.
Frequency of beer, wine, and spirits drinking and inebriation by alcohol were associated with serum lipids and blood pressure in 14,667 free-living men and women aged 20 to 54 years. Regression analysis including several background variables revealed that alcohol was more "favourably" associated with coronary risk factors than previously reported, due to the small consumption of alcohol in the population (only 2.0% of men and 0.3% of women reported drinking every day) or to unknown confounding factors: wine (p less than 0.05) and inebriation (p less than 0.01) were inversely related with total cholesterol in women; the strong positive relation with HDL-cholesterol in both sexes previously reported was confirmed; beer (p less than 0.05) and inebriation p(less than 0.05) in men and spirits (p less than 0.01) in women seemed to decrease triglycerides; and a new observation may be the negative association between wine and blood pressure (systolic p less than 0.01 in both sexes) as opposed to the positive relation with beer (p less than 0.01 both pressures in men) and spirits (p less than 0.05 systolic pressure and p less than 0.01 diastolic pressure in men and p less than 0.05 diastolic pressure in women). Women showed more "favourable effects" of alcohol than men, and one reason may be that they drank less often. Wine gave lower risk factor readings than beer, and especially lower than spirits.
Adult↗
The Tromsø Heart Study: distribution of, and determinants for, gamma-glutamyltransferase in a free-living population.
Gamma-glutamyltransferase (GGT) was measured in 1579 men, aged 20-54 years, and 1654 women, aged 20-49 years, screened for coronary risk factors. The distribution was right-skewed with medians 15 and 10 U/l for men and women, respectively. Less than 3.8% of the men and 0.8% of the women had GGT greater than or equal to 50 U/l. The low level of GGT matched well with the low mortality of cirrhosis and the modest use of alcohol in Norway. Multiple regression analysis for each sex showed a strong positive association with body mass index, use of alcohol and, unexpectedly, a negative association with coffee consumption, whereas serum triglycerides and the time since the last meal showed a weaker positive association. In women, use of oral contraceptives was positively associated with GGT.
Adult↗
Selecting risk factors: a comparison of discriminant analysis, logistic regression and Cox's regression model using data from the Tromsø Heart Study.
For comparative evaluation, discriminant analysis, logistic regression and Cox's model were used to select risk factors for total and coronary deaths among 6595 men aged 20-49 followed for 9 years. Groups with mortality between 5 and 93 per 1000 were considered. Discriminant analysis selected variable sets only marginally different from the logistic and Cox methods which always selected the same sets. A time-saving option, offered for both the logistic and Cox selection, showed no advantage compared with discriminant analysis. Analysing more than 3800 subjects, the logistic and Cox methods consumed, respectively, 80 and 10 times more computer time than discriminant analysis. When including the same set of variables in non-stepwise analyses, all methods estimated coefficients that in most cases were almost identical. In conclusion, discriminant analysis is advocated for preliminary or stepwise analysis, otherwise Cox's method should be used.
Adult↗
Dual effect of nicotine on cardiac noradrenaline release during metabolic blockade.
Nicotine-induced noradrenaline was investigated in perfused guinea pig hearts subjected to metabolic blockade that was caused either by anoxia or by cyanide intoxication. Noradrenaline, neuropeptide Y, and dihydroxyphenylethyleneglycol (DOPEG) were determined in the coronary venous overflow Neuropeptide Y is a sympathetic cotransmitter of noradrenaline, and concomitant release of both transmitters indicates an exocytotic, calcium-dependent release mechanism, whereas neuropeptide Y overflow does not occur during nonexocytotic noradrenaline release. Nonexocytotic, calcium-independent noradrenaline release, however, is associated with an increase of DOPEG overflow, which is the main intraneuronal metabolite of noradrenaline formed by monoamine oxidase if oxygen is present. Anoxia per se caused a nonexocytotic release of noradrenaline starting after 10 min of anoxia and reaching peak levels at 30 min. During anoxia, nicotine (3 and 10 mumol/l) accelerated and enhanced noradrenaline overflow, i.e., the period between the onset of anoxia and the begin of noradrenaline release was shortened and peak levels were increased. Nicotine-induced noradrenaline release was accompanied by neuropeptide Y overflow. The action of nicotine was further evaluated during energy depletion caused by cyanide. As anoxia did, cyanide administration alone resulted in noradrenaline release. In accordance with a nonexocytotic mechanism and due to the presence of oxygen, this release of noradrenaline was accompanied by an increase of DOPEG. When added 10 min after the onset of energy depletion, nicotine (10 mumol/l) caused a brief but marked enhancement of exocytotic noradrenaline release, since this release was calcium-dependent and was accompanied by a significant rise of neuropeptide Y overflow. In absence of extracellular calcium to avoid exocytosis, concomitant administration of nicotine (3-100 mumol/l) and cyanide caused a concentration-dependent acceleration of both the overflow of noradrenaline and DOPEG, whereas overflow of neuropeptide Y was not increased, thus indicating a nonexocytotic release mechanism. In conclusion, the application of nicotine during myocardial energy depletion increases overflow of noradrenaline by both calcium-dependent exocytotic release and calcium-independent nonexocytotic release mechanisms.
Animals↗
Coronary heart disease risk factors in subjects whose brothers, sisters or husbands developed premature myocardial infarction during 12 years of follow-up. The Finnmark Study (1977-1989).
BACKGROUND: In individuals whose relatives have experienced heart disease, levels of classic risk factors may have been underestimated because of life style changes after serious family disease or inaccurate disease reports. METHODS: To overcome pitfalls noted in previous research, risk factors were measured at a screening of the general population aged 20-52 years in four Norwegian municipalities. After 12 years of follow-up, a first myocardial infarction was evident in 51 of 753 sibships and in 68 of 1518 spouse pairs. RESULTS: Multiple adjusted means were higher in men with than in men without a brother or sister who became affected: 7.17 versus 6.84 mmol/l (P=0.07) for serum total cholesterol, 140.8 versus 135.6 mmHg (P=0.02) and 85.7 versus 82.5 mmHg (P=0.04) for systolic and diastolic blood pressure. Total cholesterol readings were higher the younger (P < 0.01 ) the sibling who experienced heart disease. Elevations were less pronounced in women, but smoking was more frequent among wives of affected than wives of unaffected husbands (58.3% versus 41.2%, P<0.01). CONCLUSIONS: The markedly adverse levels of modifiable risk factors found in individuals whose brothers or sisters developed heart disease offer a potential for prevention in families with heart disease.
Adult↗