Adjusting the aortic augmentation index for the resting heart rate

Vascular function in multiple sclerosis: Systematic review with meta-analysis

BACKGROUND

Vascular comorbidities are prevalent in persons with multiple sclerosis (MS), yet less is known about underlying vascular function (VF). We performed a systematic review with meta-analysis of studies that compared VF in persons with MS and healthy controls and examined factors that may moderate the difference in vascular outcomes between groups.

METHODS

We conducted a systematic search using PubMed/MEDLINE, CINAHL, and Embase from inception through March 2024. The search identified studies that included comparisons of VF between MS and controls on a range of function and structure outcomes (e.g., pulse wave velocity, augmentation index, arterial diameter, intima-media thickness, flow-mediated dilation). Effect sizes were calculated as standardized mean differences (SMD) using Hedge's g with a positive effect indicating worse VF in MS than controls. The meta-analysis involved a multilevel random effects model with follow-up moderator analyses.

RESULTS

Fourteen studies met the inclusion criteria and yielded 49 effect sizes for meta-analysis. The MS subjects (N = 614) were predominantly female (72.0 %), with mean ages ranging from 29.9 to 54.4 years. There was a moderate difference in VF between persons with MS and healthy controls (SMD [95 % CI] = 0.56 [0.08, 1.03]; p = 0.02), and the effects were heterogenous (Q48=634.5, p < 0.01; I2=94.39 %). There was a greater difference in arterial stiffness between MS and controls (0.78 [0.21, 1.36], p = 0.008), but not in other arterial structure or function outcomes (p > 0.05). No significant moderators were detected (p > 0.05).

CONCLUSIONS

The cumulative evidence supports that persons with MS have worse VF, notably greater arterial stiffness, than healthy controls. Such findings support future research on the cause, consequences, and management of arterial stiffness among persons with MS.

Vascular function and cognition in persons with multiple sclerosis: Preliminary examination

BACKGROUND

Cognitive dysfunction is one of the most common consequences of multiple sclerosis (MS). Recent studies have noted a high incidence of vascular comorbidity that might be associated with cognitive decline among persons with MS. However, there is a lack of evidence on vascular biomarkers (e.g., arterial stiffness indices) that are associated with cognition in MS. The current study characterized differences in vascular function between persons with MS and healthy controls, and examined the association between vascular and cognitive function in persons with MS compared with healthy controls.

RESULTS

The MS group had significantly worse cognitive performance and higher cfPWV than healthy controls. There were significant bivariate correlations between the Symbol Digit Modalities Test (SDMT) score with AIx75 (r_s = -0.45) and cfPWV (r_s = 0.30) in the MS sample, but not in healthy controls. Regression analyses further indicated a nonlinear association between cfPWV and the SDMT in the MS sample (p-values for β coefficients < 0.05; adjusted R² = 0.10). No significant associations were observed among other cognitive and vascular outcomes.

CONCLUSION

Our findings suggest significant associations between arterial stiffness and cognitive processing speed in MS. This preliminary examination provides initial, cross-sectional support for future population-based research on cognitive and vascular function in persons with MS. Such results may be clinically important for developing interventions that focus on regulating vascular dysfunction as an early treatment for preventing cognitive impairment in the MS population.

Central aortic hemodynamics following acute lower and upper-body exercise in a cold environment among patients with coronary artery disease

Exercise is beneficial to cardiovascular health, evidenced by reduced post-exercise central aortic blood pressure (BP) and wave reflection. We assessed if post-exercise central hemodynamics are modified due to an altered thermal state related to exercise in the cold in patients with coronary artery disease (CAD). CAD patients (n = 11) performed moderate-intensity lower-body exercise (walking at 65–70% of HR_max) and rested in neutral (+ 22 °C) and cold (− 15 °C) conditions. In another protocol, CAD patients (n = 15) performed static (five 1.5 min work cycles, 10–30% of maximal voluntary contraction) and dynamic (three 5 min workloads, 56–80% of HR_max) upper-body exercise at the same temperatures. Both datasets consisted of four 30-min exposures administered in random order. Central aortic BP and augmentation index (AI) were noninvasively assessed via pulse wave analyses prior to and 25 min after these interventions. Lower-body dynamic exercise decreased post-exercise central systolic BP (6–10 mmHg, p < 0.001) and AI (1–6%, p < 0.001) both after cold and neutral and conditions. Dynamic upper-body exercise lowered central systolic BP (2–4 mmHg, p < 0.001) after exposure to both temperatures. In contrast, static upper-body exercise increased central systolic BP after exposure to cold (7 ± 6 mmHg, p < 0.001). Acute dynamic lower and upper-body exercise mainly lowers post-exercise central BP in CAD patients irrespective of the environmental temperature. In contrast, central systolic BP was elevated after static exercise in cold. CAD patients likely benefit from year-round dynamic exercise, but hemodynamic responses following static exercise in a cold environment should be examined further.

Clinical trials.gov: NCT02855905 04/08/2016.

Critical role of the SPAK protein kinase CCT domain in controlling blood pressure

The STE20/SPS1-related proline/alanine-rich kinase (SPAK) controls blood pressure (BP) by phosphorylating and stimulating the Na-Cl (NCC) and Na-K-2Cl (NKCC2) co-transporters, which regulate salt reabsorption in the kidney. SPAK possesses a conserved carboxy-terminal (CCT) domain, which recognises RFXV/I motifs present in its upstream activator [isoforms of the With-No-lysine (K) kinases (WNKs)] as well as its substrates (NCC and NKCC2). To define the physiological importance of the CCT domain, we generated knock-in mice in which the critical CCT domain Leu502 residue required for high affinity recognition of the RFXI/V motif was mutated to Alanine. The SPAK CCT domain defective knock-in animals are viable, and the Leu502Ala mutation abolished co-immunoprecipitation of SPAK with WNK1, NCC and NKCC2. The CCT domain defective animals displayed markedly reduced SPAK activity and phosphorylation of NCC and NKCC2 co-transporters at the residues phosphorylated by SPAK. This was also accompanied by a reduction in the expression of NCC and NKCC2 protein without changes in mRNA levels. The SPAK CCT domain knock-in mice showed typical features of Gitelman Syndrome with mild hypokalaemia, hypomagnesaemia, hypocalciuria and displayed salt wasting on switching to a low-Na diet. These observations establish that the CCT domain plays a crucial role in controlling SPAK activity and BP. Our results indicate that CCT domain inhibitors would be effective at reducing BP by lowering phosphorylation as well as expression of NCC and NKCC2.