Peter Slezak

Long-term social stress induces nitric oxide-independent endothelial dysfunction in normotensive rats

As chronic stress is a significant risk factor for several cardiovascular disorders, this study investigated the hypothesis that long-term stress produced by crowding may lead to alterations in nitric oxide (NO) production and NO-dependent relaxation in the course of stress, resulting in endothelial dysfunction and hypertension in Wistar–Kyoto (WKY) rats. For this purpose, male WKY rats were divided into control (480 cm2/rat, four rats/cage, n = 8) and crowded (200 cm2/rat, five rats/cage, n = 10) groups for 8 or 12 weeks. Vasorelaxation was evaluated in vitro as a response to acetylcholine (ACh) of femoral arteries pre-contracted by serotonin, before and after NO synthase inhibition (N G-nitro-l-arginine methyl ester, 300 μmol/l). Crowding increased plasma corticosterone concentration but failed to affect blood pressure (determined by tail-cuff plethysmography) of rats. NO production was unchanged in the hypothalamus and left ventricle of both stressed groups; however it was significantly elevated in the aorta. Maximal ACh-induced relaxation was elevated significantly after 8-week stress, but reduced after 12 weeks. Stress elevated the NO-dependent component and reduced the NO-independent component of ACh-induced relaxation in both crowded groups. However, a reduction in the NO-independent component was more pronounced after 12-week versus 8-week stress. In conclusion, elevated endothelium-dependent relaxation was observed after 8-week stress, while the extension of stress exposure resulted in a reduction in arterial relaxation associated with a more pronounced decrease of its NO-independent component. Thus, elevation of the NO-dependent component of relaxation can be considered as an adaptation mechanism, and impairment of NO-independent relaxation might be the initial step in chronic stress-induced cardiovascular disorders.

Predictive validity of MRI in detecting and following cholesteatoma

High recurrence rate of the middle ear cholesteatoma requires regular postoperative follow-up. This study evaluated data from the patients investigated with DW MRI to ascertain (1) the strength of the technique in detecting primary, and residual recurrent cholesteatoma, and (2) its accuracy in differentiating cholesteatoma from postoperative tissue changes. The diagnostic accuracy of two different DW imaging (EPI and non-EPI) techniques was evaluated. The data have been collected prospectively from 33 consecutive patients with either primary cholesteatoma, or with suspicious symptoms for potential cholesteatoma recurrence. The findings from non-EPI (HASTE) DW MR and EPI DW MR images were blindly compared with those obtained during a primary or secondary surgery. Preoperative non-EPI (HASTE) DWI pointed to a cholesteatoma in 25 out of 33 patients. In this subgroup, cholesteatoma were confirmed also by the surgery. In five cases, the non-EPI (HASTE) DWI did not show a cholesteatoma in the temporal bone, which agreed with the surgical findings. Three misclassifications were made by non-EPI (HASTE) DWI, all in the subgroup of patients indicated for primary surgery. The resulting pooled sensitivity of non-EPI (HASTE) DW imaging for diagnosing cholesteatoma in our study amounted to 96.15% (95% confidence interval (CI) 80.36–99.9), specificity was 71.43% (95% CI 29.04–96.33). Positive predictive value was 92.59% (95% CI 75.71–99.09) and negative predictive value 83.33% (95% CI 35.88–99.58). In conclusion, we recommend the non-EPI (HASTE) DW MRI as a valid method for diagnosing cholesteatoma and follow-up after cholesteatoma surgery.

The effects of atorvastatin treatment on the mean platelet volume and red cell distribution width in patients with dyslipoproteinemia and comparison with plasma atherogenicity indicators—A pilot study

OBJECTIVES The mean platelet volume (MPV) and red cell distribution width (RDW) have recently arisen interest because of their association with an increased cardiovascular risk. The aim of our study was, therefore, to determine whether an association exists between MPV, RDW and lipoprotein sub-fractions, and to show the impact of statin therapy on these new possible biomarkers of atherosclerotic risk. DESIGN AND METHODS A cohort of 40 patients with hypercholesterolaemia (29 females, mean age 62.9±9 years), without previous hypolipidaemic treatment were enrolled. The patients were treated with atorvastatin 40 mg/day for 12 weeks. Total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), high density cholesterol (HDL-C), triglycerides (TG), LDL-C sub-fractions [large LDL-C 1-2 and small dense (sd)-LDL-C 3-7], apolipoproteins (apoA1, apoB), apoB/apoA1 ratio, atherogenic index of plasma (AIP), haematological parameters (including MPV, RDW) and safety parameters (renal, hepatic) were measured before and after 12 weeks of atorvastatin treatment. RESULTS At baseline, a strong correlation between HDL-C, TG, sd-LDL-C, apoB, apoB/apoA1, and AIP with MPV (r=-0.55, p<0.001; r=0.57, p<0.001; r=0.73, p<0.001; r=0.41, p<0.05; r=0.52, p<0.001; r=0.61, p<0.001, respectively) and RDW (r=-0.49, p<0.001; r=0.62, p<0.001; r=0.67, p<0.001; r=0.41, p<0.05; r=0.43, p<0.05; r=0.65, p<0.001, respectively) was found. After 12 weeks of treatment with atorvastatin, MPV and RDW values underwent significant modification only in those patients displaying the strongest lipid-lowering effect. CONCLUSIONS Values of MPV and RDW seem to reflect a pro-atherogenic lipoprotein profile mainly represented by the presence of sd-LDL-C.

Genotype-Related Effect of Crowding Stress on Blood Pressure and Vascular Function in Young Female Rats

This study investigated the influence of chronic crowding stress on nitric oxide (NO) production, vascular function and oxidative status in young Wistar-Kyoto (WKY), borderline hypertensive (BHR) and spontaneously hypertensive (SHR) female rats. Five-week old rats were exposed to crowding for two weeks. Crowding elevated plasma corticosterone (P < 0.05) and accelerated BP (P < 0.01 versus basal) only in BHR. NO production and superoxide concentration were significantly higher in the aortas of control BHR and SHR versus WKY. Total acetylcholine (ACh)-induced relaxation in the femoral artery was reduced in control SHR versus WKY and BHR, and stress did not affect it significantly in any genotype. The attenuation of ACh-induced relaxation in SHR versus WKY was associated with reduction of its NO-independent component. Crowding elevated NO production in all strains investigated but superoxide concentration was increased only in WKY, which resulted in reduced NO-dependent relaxation in WKY. In crowded BHR and SHR, superoxide concentration was either unchanged or reduced, respectively, but NO-dependent relaxation was unchanged in both BHR and SHR versus their respective control group. This study points to genotype-related differences in stress vulnerability in young female rats. The most pronounced negative influence of stress was observed in BHR despite preserved endothelial function.

Age-Related Alterations in Endothelial Function of Femoral Artery in Young SHR and WKY Rats

The present study was designed to evaluate the effects of vascular aging in juvenescence on endothelial function in femoral arteries and to assess differences between normotensive and hypertensive rats. The aim of the study was to determine if age affected nitric oxide- (NO-) mediated relaxations in normotensive and hypertensive rats. Juvenile (7-week-old) and young adult (22-week-old) male Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR) were used in this study. Femoral artery (FA) reactivity was determined by wire myograph and NO synthase activity by conversion of [3H]-L-arginine. During juvenescence systolic blood pressure (tail-cuff) increased significantly only in SHR, while NO synthesis decreased significantly in both strains. Endothelium-dependent relaxations to acetylcholine were reduced in the FA of SHR compared to age-matched WKY at both ages, yet these parameters were unchanged in adult rats compared with juvenile animals. The NO-dependent component of vasorelaxation was markedly reduced, whereas the NO-independent component was increased in adult compared to juvenile rats in both strains. The endothelial dysfunction in SHR at both ages was associated with reduction of NO-independent mechanisms. In conclusion, aging in early periods of life was associated with reduction of vascular NO production and bioavailability in both strains investigated. This reduction was however fully compensated by accentuation of NO-independent mechanisms.

One-day session LINAC-based stereotactic radiosurgery of posterior uveal melanoma.

Purpose LINAC-based stereotactic radiosurgery (SRS) of posterior uveal melanoma is a conservative method to treat uveal melanoma. Methods This was a retrospective clinic-based study of patients with posterior uveal melanoma in stage T2/T3 who underwent 1-day session SRS at LINAC accelerator or SRS plus combined methods from 2001 to 2008. Results Thirty-nine patients with posterior uveal melanoma were treated with SRS (age 25-80 years, median 54 years). Median tumor volume at baseline was 0.6 cm3 (range 0.2-1.3 cm3). The therapeutic dose (TD) was 35.0 Gy, median of maximal dose applied was 49.0 Gy (range 37.0-60.0 Gy). Patient data were analyzed in groups: group 1, single SRS irradiation; group 2, SRS with subsequent endoresection or cyclectomy or additional transpupillary thermotherapy (TTT) or brachytherapy by Ru106 plaques; group 3a, enucleation after single SRS; group 3b, enucleation after SRS and endoresection/cyclectomy or TTT or brachytherapy Ru106. In patients with visual acuity of 20/40 or better, the median rate of best-corrected visual acuity (BCVA) decline was higher than that of the total and significantly higher than the rate of decline in the complementary group of patients with BCVA less than 20/40 (p=0.0077; Mann-Whitney U test). Conclusions One-step LINAC-based SRS with a single dose 35.0 Gy is a method to treat middle-stage posterior uveal melanoma and to preserve the eye globe or as the first step of combined methods: irradiation before endoresection or cyclectomy.

107 ENDOTHELIAL DYSFUNCTION IN YOUNG MALE AND FEMALE SPONTANEOUSLY HYPERTENSIVE RATS ARE SIMILAR

Objective: Spontaneously hypertensive rats (SHR) are experimental model of human essential hypertension. Despite many studies there is less information on sex-related differences in endothelial function of young SHR, including nitric oxide (NO)-dependent and independent components of acetylcholine (ACh)-induced vasorelaxation. This study investigated endothelial function in young (7 weeks old) male and female SHR as compared to age-matched normotensive Wistar-Kyoto rats (WKY). Design and methods: Blood pressure (BP) was determined non-invasively by tail-cuff method. Vascular studies were conducted in the femoral artery rings by wire myograph. The NO-dependent component of ACh-induced relaxation was calculated as the difference between ACh-induced relaxation before and after acute NG-nitro-L-arginine methyl ester pre-treatment. Results: In both, male and female SHR, BP was increased significantly as compared to WKY, however, there were not observed sex-related differences in BP. Endothelium-independent sodium nitroprusside-induced relaxation was similar in both phenotypes and genders. Endothelium-dependent ACh-induced relaxation was reduced significantly in both male and female SHR vs. WKY. Endothelial dysfunction in SHR was associated with reduced NO-independent component of vasorelaxation while NO-dependent component was similar in all groups investigated. ACh (at higher concentrations) induced endothelium-dependent contractions in SHR males but not in females and both WKY groups. Additionally, no sex-related differences in NO-dependent and NO-independent components of relaxation were seen in young rats. Conclusions: Endothelial dysfunction was present already in young spontaneously hypertensive females and it was qualitatively and quantitatively similar to that observed in males. Supported by the grants APVV-0523-10 and VEGA 2/0084/10.

835 AGE-RELATED CHANGES IN VASCULAR FUNCTION OF NORMOTENSIVE AND SPONTANEOUSLY HYPERTENSIVE RATS

Objective: Spontaneously hypertensive rat (SHR) serves as an experimental model of human essential hypertension. However, the role of endothelium-derived relaxing and endothelium-derived constricting (EDCFs) factors in the arteries of hypertensive rats remains controversial. This study investigated endothelial function in male, 7- and 22-week-old SHR and age-matched Wistar-Kyoto rats (WKY). Design and methods: Blood pressure (BP) and heart rate (HR) were determined by tail-cuff method. Acetylcholine (ACh)-induced nitric oxide (NO)-dependent and NO-independent components of vasorelaxation were determined in the femoral artery (FA) rings by wire myograph. Results: In SHR, BP and HR were increased significantly as compared to age-matched WKY. BP of 22-week-old SHR was increased vs. young SHR (197 ± 4 mmHg vs. 163 ± 4 mmHg, p < 0.01). Endothelium-dependent ACh-induced relaxation of the FA was reduced significantly in both young and adult SHR vs. age-matched WKY. However, the extent of endothelial dysfunction was similar in both SHR groups. Interestingly, endothelial dysfunction in SHR was associated with reduced NO-independent component of vasorelaxation while NO-dependent component of vasorelaxation was similar to age-matched WKY. However, in both WKY and SHR NO-dependent component of vasorelaxation was reduced in adult rats vs. young. ACh at higher concentrations caused endothelium-dependent contractions in both SHR groups but not in WKY. Conclusions: We showed that endothelial dysfunction was present already in young SHR and it was associated with reduction of NO-independent component of vasorelaxation and release of EDCFs. Interestingly, age-related reduction of NO-dependent component of relaxation was present in both phenotypes. Supported by APVV-0523-10 and VEGA 2/0084/10.

1064 Effect of chronic social stress on vascular function OF YOUNG normotensive and hypertension-prone female rats

Objective: Despite many experimental studies the effect of chronic social stress on vascular function in young rats is unclear. We investigated the influence of chronic crowding stress on superoxide production and vascular function in young female rats with various genetic predisposition to high blood pressure. Design and methods: Five-week females of borderline hypertensive (BHR) and normotensive Wistar-Kyoto (WKY) rats were exposed to crowding for two weeks. Crowding was induced by placement of 5 rats per cage (70 cm2/100 g of body weight). Controls were kept 4 rats per cage (160 cm2/100 g of body weight). Vascular studies were conducted in the femoral artery by wire myograph. The nitric oxide (NO)-dependent component of acetylcholine (ACh)-induced relaxation was calculated as the difference between ACh-induced relaxation before and after acute NG-nitro-L-arginine methyl ester pre-treatment. The superoxide production was evaluated using lucigenin enhanced chemiluminiscence. Results: There were no differences in overall endothelium-dependent ACh-induced relaxation among the groups investigated. Superoxide level was elevated and NO-dependent component of relaxation was reduced significantly in control BHR vs.WKY. Crowding stress elevated superoxide production and reduced NO-dependent component of relaxation only in WKY while no changes in these parameters were seen in BHR vs. control. Conclusion: Chronic social stress accelerated oxidative stress and reduced vascular NO bioavailability only in normotensive rats. In BHR, despite reduced basal NO bioavailability, crowding did not modify their oxidative stress and vascular function. Data suggest effective, but qualitatively different, adaptation to stress in young females of both strains. Supported by the APVV-0523-10 and VEGA 2/0084/10.

1063 Effect of chronic social stress on blood pressure and nitric oxide production in young hypertension-prone female rats

Objective: Despite many experimental and population-based observational studies there is still conflicting information regarding causal relation between stress and hypertension. We investigated the influence of chronic crowding stress on blood pressure (BP) and nitric oxide synthase activity (NOS) in young female rats with genetic predisposition to high blood pressure. Design and Methods: Five-week females of borderline hypertensive (BHR) and normotensive Wistar-Kyoto rats (WKY) were exposed to crowding for two weeks. BHR were F1 offspring of spontaneously hypertensive dams and WKY sires. Crowding was induced by placement of 5 rats per cage (70 cm2/100 g of body weight). Controls were kept 4 rats per cage (160 cm2/100 g of body weight). Results: BP (determined by tail-cuff) of 5-week WKY and BHR was 107 ± 2 and 130 ± 2 mmHg, respectively (p < 0.01) and crowding failed to affect BP significantly vs. age-matched controls. NOS activity was determined by conversion of [3H]-L-Arginine to [3H]-L-citrulline in the aorta, hypothalamus and brain steam. NO production was significantly higher in the aorta of control BHR vs. WKY (p < 0.05) and stress significantly increased NOS activity in both strains approximately by 82 and 62% vs. the control group, respectively. In contrast stress reduced significantly NO production in the hypothalamus and brain steam in both strains. Conclusion: Chronic social stress did not accelerate development of hypertension in young hypertension-prone female rats. We assume that elevated vascular NO production can act as an adapting mechanism, protecting young females from development of hypertension despite reduced NO production in the central nervous system. Supported by the APVV-0523-10 and VEGA 2/0084/10.