Thomas Thulin

Serum Heat Shock Protein 70 Levels Predict the Development of Atherosclerosis in Subjects With Established Hypertension

Abstract—Although heat shock proteins (Hsp’s) are present in the sera of healthy individuals and at elevated levels in subjects with early cardiovascular disease, their physiologic role in and value for predicting the development and/or progression of atherosclerosis have not been evaluated. Serum was obtained from 218 subjects with established hypertension (diastolic pressure >95 mm Hg) before their enrollment in the European Lacidipine Study on Atherosclerosis. Hsp60 and Hsp70, and anti-human Hsp60, anti-human Hsp70, and anti-mycobacterial Hsp65 antibody levels were measured by enzyme immunoassay. As an indicator of the presence/progression of atherosclerosis, the means of the maximum intima-media (I-M) thicknesses in the far walls of common carotid arteries and bifurcations (CBMmax) were determined by ultrasonography at the time of enrollment and 4 years afterward. Increases in I-M thicknesses at follow-up were less prevalent in subjects having high serum Hsp70 levels (75th percentile) at the time of enrollment (odds ratio, 0.42; 95% confidence interval [CI], 0.22 to 0.8, P =0.008). Although a similar trend was observed for serum Hsp60 levels, this was not statistically significant (odds ratio, 0.6; 95% CI, 0.32 to 1.11, P =0.10). There was no relation between anti-Hsp antibody levels and changes in I-M thicknesses. The relation between Hsp70 levels and changes in I-M thickness was independent of age, atenolol or lacidipine treatment, smoking habits, and blood lipid levels. These findings indicate that circulating Hsp70 levels predict the development of atherosclerosis in subjects with established hypertension, and an intriguing possibility is that Hsp70 protects against or modifies the progression of atherosclerosis in this subject group.

Circulating heat shock protein and heat shock protein antibody levels in established hypertension

Objective Serum Hsp60 and anti-Hsp65 antibody levels are raised in subjects with borderline hypertension, and there is an association between circulating Hsp60 levels and early atherosclerosis. Given the recognized relationship between hypertension and atherosclerosis, this study determined heat shock protein and heat shock protein antibody levels in subjects with established hypertension. Methods Samples from 111 men with hypertension were obtained from the European Lacidipine study on Atherosclerosis and samples from 75 normotensive controls were taken from a population-screening programme (diastolic pressure, > 95 and < 80 mmHg, respectively). Hsp60, Hsp70 and anti-human Hsp60, anti-human Hsp70 and anti-mycobacterial Hsp65 antibody levels were measured by enzyme immunoassay. Intima–media thickness (I–M) and the presence of carotid atherosclerosis were determined by ultrasonography. Results Hsp60, Hsp70 and anti-Hsp60 antibody levels in hypertension were similar to those in normotensive controls, whereas anti-Hsp70 and anti-Hsp65 antibody levels were elevated (P < 0.001). Hsp60 levels and atherosclerosis were not associated. Anti-Hsp70 and anti-Hsp65 antibody levels were both associated with hypertension, independently of age, smoking habits and blood lipids. Conclusions This study demonstrates elevated levels of selected heat shock protein antibodies in subjects with hypertension. Although the association between heat shock protein antibody levels and human cardiovascular stress/disease appears to be robust, the relationship of the latter with heat shock protein levels is more complex. Further studies are required before the factors inducing, and the clinical significance of, circulating heat shock proteins can be evaluated.

A genetic polymorphism in connexin 37 as a prognostic marker for atherosclerotic plaque development

Abstract. Boerma M, Forsberg L, van Zeijl L, Morgenstern R, de Faire U, Lemne C, Erlinge D, Thulin T, Hong Y, Cotgreave IA (Karolinska Institute and Karolinska Hospital, Stockholm; Lund University, Lund, Sweden. Washington University School of Medicine, MO, USA). A genetic polymorphism in connexin 37 as a prognostic marker for atherosclerotic plaque development. J Intern Med 1999; 246: 211–218.

Increased plasma levels of neuropeptide Y-like immunoreactivity and catecholamines in severe hypertension remain after treatment to normotension in man

Circulating levels of neuropeptide Y (NPY)-like immunoreactivity (-LI), adrenaline and noradrenaline (NA) were analysed in 17 patients admitted to the emergency ward due to severe hypertension; blood pressure mean 204/127 mmHg. The levels of NPY-LI and NA were significantly higher (P less than 0.001) in the hypertensives as compared to a normotensive control group. HPLC analysis revealed that the plasma contained besides NPY-LI also several NPY-LI fragments of low hydrophobicity. Following 2 to 3 weeks treatment the blood pressure had decreased to a mean of 150/89 mmHg. However, circulating levels of NPY-LI (P less than 0.001) and NA (P less than 0.01) were still significantly higher than in controls in spite of the marked reduction in blood pressure. Simultaneous measurements of adrenaline did not reveal any significant changes and these values did not differ compared with those in the normotensive subjects. The findings suggest that peripheral markers of the sympathetic system (NPY-LI and NA) in severe hypertension is not directly related to the blood pressure level.

Interindividual variation in the responses of cultured human lymphocytes to exposure from DNA damaging chemical agents: Interindividual variation to carcinogen exposure

Human population variability to standardized doses of N-acetoxy-2-acetylaminofluorene (NA-AAF) and 7, 12-dimethylbenz(a) anthracene (DMBA) was determined in cultured lymphocytes by measuring (a) differential stimulation of unscheduled DNA synthesis after 1 h induction of DNA damage by 10 micrometer NA-AAF, (b) the level of NA-AAF induced chromosome aberrations remaining after 8 h of DNA-repair synthesis, and (c) the level of [3H]DMBA bound to DNA after 18 h incubation of resting lymphocytes in 5 micrometer DMBA. All 3 parameters indicated individual variation to carcinogen exposure and were correlated to the population differences in age, sex, blood pressure and mortality rates. Males always had a greater potential to accumulate DNA-damage than did females regardless of the sampled population. DNA-damage potentials increased with increasing age, blood pressure or mortality rates. There was always proportionally greater DNA-damage potentials in the males than in females. The in vitro response of mature granulocytes to a 10 micrometer NA-AAF dose, as estimated by [3H] thymidine incorporation from unscheduled DNA synthesis, was much lower than lymphocyte response. Nevertheless, individual variations in granulocyte NA-AAF induced unscheduled DNA synthesis paralleled the inter-individual fluctuations observed in the lymphocyte responses to NA-AAF.

Circulating oxidized low-density lipoprotein is increased in hypertension

Oxidized low-density lipoprotein (OxLDL) and autoantibodies to OxLDL (aOxLDL) are implicated in the development of atherosclerosis. The objective of this study was to determine the importance of these factors in hypertension, a major risk factor for atherosclerosis. Samples were obtained from 111 men with established hypertension (diastolic pressure >95 mmHg) from the Swedish component of an ongoing hypertension study (European Lacidipine study on Atherosclerosis, ELSA) and from 75 normotensive control men, who were from a Swedish population-screening programme (diastolic pressure <80 mmHg). The presence of carotid atherosclerosis and the intima-media thicknesses were determined by ultrasonography. A monoclonal antibody to OxLDL, EO6, was used to determine oxidation epitopes in LDL. aOxLDL of IgG and IgM subclass were tested by ELISA against OxLDL. Hypertensive men had increased OxLDL levels compared with normotensives ( P =0.002), whereas autoantibodies tested were largely similar between groups. There was no association between the antibodies tested, or OxLDL and carotid atherosclerosis. Age was not associated with OxLDL or aOxLDL measurements. Taken together, our findings indicate that OxLDL is elevated in hypertensive men, which may predispose to atherosclerosis in hypertension. In contrast, aOxLDL levels were unchanged and the role of aOxLDL may depend on disease stage and/or type.

Neuropeptide Y-like immunoreactivity and hypertension

Objective: Neuropeptide Y is a co-transmitter with noradrenaline in sympathetic neurons supplying arteries and veins with potent contractile effects. To investigate the role of neuropeptide Y in hypertension, we measured the circulating levels of neuropeptide Y and noradrenaline in patients with severe hypertension. Design: Samples were collected from patients with untreated, severe hypertension (diastolic blood pressure > 120 mmHg) and in age- and sex-matched controls. After treatment with β-adrenoceptor blockers, diuretics, angiotensin converting enzyme inhibitors or calcium antagonists, samples were taken from the patients during 12 months. Methods: The circulating levels of neuropeptide Y-like immunoreactivity (NPY-LI) were measured with a radioimmunoassay using a rabbit antiserum. Catecholamines were measured using high-performance liquid chromatography and electrochemical detection. Results: There was a significantly higher level of NPY-LI in the patients when they were compared with the controls. However, there was no correlation either in the controls or in the hypertensives between systolic blood pressure, diastolic blood pressure and NPY-LI or noradrenaline. The increased level of NPY-LI in plasma remained elevated for up to 12 months despite reduction in blood pressure to acceptable levels. The noradrenaline level was not increased before treatment, after 2—4 weeks or after 2—12 months treatment. Conclusion: The high level of NPY-LI may represent a marker for higher activity of the sympathetic nervous system which is not controlled by the treatment of blood pressure to normotension.

Assessment of casual blood pressure variations.

All residents in a suburban community in southern Sweden, 8 years of age and older, were invited to an ophthalmological examination. The examination included a blood pressure determination. Of the 1917 persons invited 85·5% took part in the study. 3·5% of these were excluded because they were taking antihypertensive drugs. The investigations were conducted during 14 consecutive months and at different times of the day. The systolic and diastolic blood pressure distribution curves exhibited a positive skewing. The blood pressures rose to a plateau with essentially unchanged pressures in the age groups 28-32 years up to 38-42 years. In these ages, the systolic blood pressure was significantly higher among the males than among the females. The relation was reversed in the age groups above 48 years. The diastolic blood pressure showed no significant sex differences in the various age groups. A multiple linear regression analysis was used to determine whether there were diurnal and seasonal effects on the blood pressure independent of the age and sex. The systolic blood pressure during the winter months was 4·1 and 5·0 mmHg higher in the male and female subjects respectively, while the diastolic blood pressure during the winter months was 1·7 and 1·9 mmHg higher in the male and female subjects respectively. The time of day had no effect on the systolic blood pressure while the diastolic blood pressure increased by 0·24 and 0·27 mmHg/hr from 8 a.m. to 9 p.m. in the male and female subjects respectively. It is concluded that the small genuine effects of the time of measurement of casual blood pressure lack practical importance in screening of hypertension.

How good are standardized blood pressure recordings for diagnosing hypertension? A comparison between office and ambulatory blood pressure.

Ambulatory blood pressure monitoring was compared with office blood pressure in 48 normotensive, 81 borderline hypertensives and 35 untreated hypertensives. The studied groups were chosen from a geographically defined population of middle-aged men in southern Sweden. The mean 24-h ambulatory blood pressure values for the normotensives, borderline hypertensives and untreated hypertensives were 120/76, 127/82 and 140/92 mmHg, respectively. The diurnal mean ambulatory blood pressure in the three groups was 126/80, 134/86 and 146/96 mmHg, respectively. The percentage of 24-h diastolic blood pressure peaks greater than or equal to 95 mmHg in the groups were 7%, 22% and 53%, respectively. The corresponding values greater than or equal to 90 mmHg were 16%, 38% and 69%, respectively. In the untreated hypertensive group, there was a more pronounced (P less than 0.05) systolic blood pressure increase during the morning hours (0600-1000 h) than in the normotensive and borderline hypertensive groups. Fourteen per cent of the hypertensives showed normal blood pressure values during 24-h blood pressure monitoring. Fifteen per cent of the borderline hypertensives were normotensive during ambulatory blood pressure monitoring despite repeated office diastolic blood pressure greater than or equal to 90 mmHg. The opposite (increased blood pressure during ambulatory blood pressure monitoring and at screening but normal office blood pressure) was seen in 14% of the borderline hypertensives. Normotensives were characterized by lower mean blood pressure values, fewer blood pressure peaks and a lower systolic blood pressure increase during the morning hours than hypertensives in this study of middle-aged men. The established way of diagnosing hypertension, borderline hypertension and normotension correlated well with the results of ambulatory blood pressure monitoring.

Monitoring 24-hour blood pressure in a drug trial. Evaluation of a noninvasive device.

To test the usefulness of noninvasive ambulatory 24-hour blood pressure recording, the Del Mar Avionics system was used in a double-blind clinical trial in which 31 hypertensive patients were randomly allocated to receive placebo or pafenolol (25 mg or 50 mg), a novel, long-acting, highly selective beta-blocker, once daily. The results of 24-hour blood pressure and heart rate recording after 4 weeks of treatment were compared with a previous 24-hour recording performed after a 4-week placebo run-in period using the 3-hour mean of recordings performed every 7.5 minutes both day and night. Furthermore, 24-hour means were analyzed in each patient before and after 4 weeks. The system was easy to use and, judging from two placebo periods in the same patients, the reproducibility was good. The 24-hour blood pressure and heart rate recordings showed a clear dose-response relationship for pafenolol that could not be detected by ordinary casual readings. A daily dose of 25 mg of pafenolol significantly reduced blood pressure during the 9 hours after tablet intake (p less than 0.01), while 50 mg per day of pafenolol resulted in a significant reduction throughout the 24-hour period (p less than 0.01). The same pattern was seen for heart rate, which indicates a greater degree of beta-blockade during treatment with the higher dose. These results indicate that the tested noninvasive equipment is a useful tool for monitoring ambulatory 24-hour blood pressure. It gives important information impossible to obtain from single casual readings. This noninvasive method should be further evaluated to define its place in clinical work and as a research tool.