Increase in beta-thromboglobulin during exercise.
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Biomedical subjects
Publications and source records attributed to K Gjesdal.
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Beta-thromboglobulin (BTG) is a platelet-specific release product. Plasma BTG was significantly increased (p less than 0.01) in 50-year-old, untreated essential hypertensive men (1.22 +/- 0.13 nmol/L, n = 39, mean +/- SE) compared to 50-year-old, healthy normotensive control men (0.82 +/- 0.07 nmol/L, n = 31). Plasma BTG in the hypertensive group correlated significantly with the total serum cholesterol concentration (r = 0.47, p less than 0.01) and with the atherogenic cholesterol fractions low-density lipoprotein (LDL) and very low-density lipoprotein (VLDL) cholesterol (r = 0.50, p less than 0.01). In the normotensive group, no significant correlation was observed between plasma BTG and total serum cholesterol (r = 0.14) or between plasma BTG and LDL + VLDL cholesterol (r = 0.08). Neither was any significant correlation found between plasma BTG and serum high-density lipoprotein (HDL) cholesterol or total triglycerides in either group. Thus, middle-aged men with untreated essential hypertension have an increased blood platelet release reaction related to their concentrations of atherogenic blood lipids. This relationship may be of pathogenetic importance for atherogenesis in hypertension.
Thirty-four patients without IgG antibodies against cytomegalovirus (CMV) prior to open heart surgery were studied. The patients were randomized to receive blood either from unselected donors, or from donors without detectable CMV antibodies. Fresh whole blood was mainly used. Eleven patients received CMV seronegative blood only. All had an uneventful convalescence period and remained seronegative. Ten of the 23 patients who received blood from unselected donors had typical CMV disease with the onset of symptoms in the third or fourth postoperative week, and fever lasting for two to three weeks. They all had liver enzyme release and later seroconversion against CMV. Four patients were hospitalized during this period. The incidence of symptomatic CMV infection after open heart surgery was higher than usually reported among the CMV seronegative patients. Selection of blood donors who lack antibodies against CMV may be an adequate protective measure. Avoidance of fresh blood and reduced use of blood products are presumably also of importance.
Basal platelet function was measured in 35 40-year-old men with untreated mild essential hypertension and compared with 44 age-matched normotensive men. The groups differed significantly with respect to platelet size in venous blood (hypertensive, 7.46 +/- 0.10 X 10(-15) l versus normotensive, 7.11 +/- 0.09 X 10(-15) l; P = 0.01) and arterial concentration of the platelet-specific protein beta-thromboglobulin (hypertensive, 1.11 +/- 0.23 nmol/l versus normotensive, 0.59 +/- 0.04 nmol/l; P = 0.02). The normotensive subjects had significantly higher beta-thromboglobulin (BTG) in venous than in arterial blood (P less than 0.01). The hypertensive men showed no such difference. In contrast to the normotensive subjects, the hypertensive group had reduced arterial compared with venous platelet count (P less than 0.01). This may reflect an increased liability in the hypertensive subjects to lose platelets through adherence to the cannula during arterial blood sampling. The above findings point to increased platelet activity in essential hypertension, particularly in arterial blood.
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Seventeen 50-year old hypertensive men, previously untreated with blood pressure 157 +/- 4/110 +/- 2 mmHg (means +/- SE) were given a low sodium diet for 2 weeks. During the second week, the diet was supplemented with potassium. The urinary Na+/K+ excretion ratio changed from 2:1 to 1:4 and 1:11, respectively. Sympathetic noradrenergic tone increased considerably during the first week. Thus, venous plasma noradrenaline increased from 254 +/- 22 to 347 +/- 28 pg/ml (p less than 0.001) and arterial concentration from 253 +/- 36 to 317 +/- 42 pg/ml (n = 10, p less than 0.001). No significant change was observed in sympathetic adrenal tone as reflected by normal plasma adrenaline in venous (42 +/- 5 vs 43 +/- 6 pg/ml, ns) or arterial blood (71 +/- 10 vs 82 +/- 15 pg/ml, n = 10, ns) or in venous plasma concentration of the blood platelet release product beta-thromboglobulin (BTG) (50 +/- 8 vs 43 +/- 5 ng/ml, ns). During the second week sympathetic noradrenergic tone remained highly significantly elevated compared to baseline but still no change in plasma adrenaline or plasma BTG was found. Thus, whereas sodium depletion did increase plasma noradrenaline concentration markedly in these hypertensive men, no change in adrenaline concentration was observed, and blood platelet release reaction was unchanged. Plasma noradrenaline within the physiological concentration range does not seem to serve as a regulator of in vivo platelet function.
In a study of GTN absorption during exercise and high ambient temperature, 12 healthy volunteers carried 10 mg glyceryl trinitrate (GTN, nitroglycerin) transdermal patches for 6 hours during each of 3 days. During a control day the mean plasma GTN concentration ranged from 1.0 nmol/L (SD +/- 0.8 nmol/L) to 1.5 nmol/L (SD +/- 1.0 nmol/L), whereas during a bicycle ergometer day mean GTN concentration was increased to 3.1 nmol/L (SD +/- 1.7 nmol/L, p less than 0.001). During a sauna day volunteers stayed for 20 minutes in a sauna, and mean GTN concentration in plasma rose to 7.3 nmol/L (SD +/- 1.7 nmol/L, p less than 0.001). Systolic blood pressure increased during exercise (p less than 0.01) but decreased significantly in the sauna (p less than 0.01). Headache was noted frequently (9 of 12 subjects) and dizziness by a few (3 of 12). The demonstrated increased transdermal absorption in our study may infer an increased effect during workload. Whereas the increase in transdermally absorbed GTN may be beneficial to the exercising angina patient, increased effects of GTN may be undesirable in hot surroundings. A study on angina patients is justified to assess whether this phenomenon bears clinical relevance.
50 year old men with moderate, essential hypertension (n = 39) were compared to normotensive males of similar age (n = 31). The hypertensive men were heavier (10 kg in average, p less than 0.01), and had a higher pulse rate (5 beats per minute (p less than 0.05). Plasma beta-thromboglobulin, a marker of platelet release reaction, was 49% higher in the hypertensive group (p less than 0.01). Total cholesterol, LDL + VLDL cholesterol and serum triglycerides were not significantly different between the groups. In the hypertensive group, plasma beta-thromboglobulin concentration correlated significantly with total cholesterol (r = 0.47, p less than 0.01) as well as with LDL + VLDL cholesterol (r = 0.50, p less than 0.01). In the normotensive group no such correlation was found. The results suggest activation of platelets in hypertension, and suggest that in hypertension, even a normal cholesterol concentration may influence platelet function.
Hypertensive men aged 42 (n = 35) were compared to normotensive men of similar age (n = 44). Platelet numbers were similar in the two groups, but hypertensive men had larger venous platelets than the normotensive (7.46 versus 7.12 femtoliter, p = 0.01). Plasma concentration of beta-thromboglobulin (BTG), a marker of platelet release reaction, was increased in arterial blood in hypertension (40 versus 21 micrograms/l, p = 0.02). The normotensive subjects had markedly higher BTG concentration in venous compared to arterial blood (p less than 0.01), but this arterio-venous difference was not present in the hypertensive group. Twelve normotensive subjects received infused saline, which did not induce changes in platelet variables. Adrenaline was infused to 13 hypertensive and 12 normotensive subjects, with dose gradually increasing to 0.04 microgram/kg/min. Platelet count increased in both groups, but significantly more in the hypertensive group. Platelet volume and BTG both increased markedly in the hypertensive group, but not in the normotensive men. Thus, young men with hypertension have increased platelet activity and increased sensitivity to exogenous adrenaline.
The platelet release product beta-thromboglobulin (BTG) in venous plasma, and arterial and venous catecholamines were measured in 13 severe pre-eclamptic and 13 normotensive pregnant women. In the pre-eclamptic group, BTG was significantly higher and the platelet count significantly lower than in the normotensive pregnant group. In the pre-eclamptic group, arterial concentrations were significantly higher for adrenaline, noradrenaline and dopamine, whereas in venous plasma only adrenaline and dopamine were higher. Significant positive correlations appeared in the pre-eclamptic patients between venous BTG and arterial adrenaline (r = 0.82), arterial noradrenaline (r = 0.76) and venous adrenaline (r = 0.55). In the pre-eclamptic group, BTG also highly correlated with systolic (r = 0.84) and diastolic blood pressure (r = 0.77) and heart rate (r = 0.67). These findings indicate that sympathetic nervous tone, as measured by arterial and venous plasma catecholamines, is a good predictor of in-vivo blood platelet activation. In pre-eclampsia, increased sympathetic tone may play a key role in platelet activation and consumption and thus in the activation of the coagulation system.
At the end of a diagnostic right heart catheterization ten patients received an intravenous infusion of l-adrenaline which gradually increased the arterial plasma adrenaline concentration from resting physiological values to high values as seen during myocardial infarction, pheochromocytoma and hypoglycemia. Blood was sampled from the brachial artery, femoral vein and hepatic vein. During the adrenaline infusion venous beta-thromboglobulin concentrations increased 23% from 61 +/- 5 to 80 +/- 7 micrograms/l (mean +/- SE), arterial platelet counts 20% from 212 +/- 17 to 253 +/- 25 X 10(9)/l and arterial platelet volume 4% from 7.25 +/- 0.20 to 7.56 +/- 0.21 femtoliter. All changes were significant at the 5% level. Thus, acute increments of arterial plasma adrenaline significantly stimulated the blood platelet parameters studied.
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Among 674 patients undergoing open heart surgery in 1981-82, 86 (13%) were cytomegalovirus (CMV) antibody-negative when tested by an enzyme-linked immunosorbent assay prior to operation. At follow-up, 54 (67%) of 80 patients restudied had seroconverted after the operation, and 35 of the 54 seroconvertants had been ill with fever and elevated liver enzymes. Among the latter 35 patients, 26 demonstrated a significant rise in CMV antibody titre, most often detected in the third week following the onset of illness. The older patients were more susceptible to illness and seroconversion, and there was a positive correlation between age and the number of blood units given. Thus, at least one third of the seronegative patients developed symptomatic CMV illness after open heart surgery. This is a much higher incidence than earlier reported.
Plasma glyceryl trinitrate (GTN) concentration was studied in 12 volunteers producing gun powder. Serial blood samples were obtained from the cubital vein before and during work at two sites of production; high concentrations of GTN were detected in the plasma. Control specimens from a femoral vein contained much less GTN, indicating that blood in the cubital vein was enriched by dermally absorbed GTN. In the roll mill area concentrations of GTN in the cubital vein were higher than in the press area, but individual factors were also important since some workers consistently had higher concentration of GTN than others. Differences in absorption were more important than differences in the metabolism of GTN since only a small variation in disappearance rate was found after a sublingual test dose of GTN. Moderate changes in pulse rate and blood pressure were noted during the day. The major discomfort experienced was a headache that increased during working hours, but this was not significantly related to GTN concentrations in the air or in the blood from the cubital vein. The observations imply that major efforts should be made to reduce dermal contact with GTN during production work.