Four weeks of vitamin D supplementation improves nitric oxide-mediated microvascular function in college-aged African Americans

Interplay of race and neighborhood deprivation on resting and ambulatory blood pressure in young adults

Nighttime blood pressure (BP) and BP dipping (daytime-nighttime BP) are prognostic for cardiovascular disease. When compared with other racial/ethnic groups, Black Americans exhibit elevated nighttime BP and attenuated BP dipping. Neighborhood deprivation may contribute to disparities in cardiovascular health, but its effects on resting and ambulatory BP patterns in young adults are unclear. Therefore, we examined associations between neighborhood deprivation with resting and nighttime BP and BP dipping in young Black and White adults. We recruited 19 Black and 28 White participants (23 males/24 females, 21 ± 1 yr, body mass index: 26 ± 4 kg/m2) for 24-h ambulatory BP monitoring. We assessed resting BP, nighttime BP, and BP dipping (absolute dip and nighttime:daytime BP ratio). We used the area deprivation index (ADI) to assess average neighborhood deprivation during early and mid-childhood and adolescence. When compared with White participants, Black participants exhibited higher resting systolic and diastolic BP (Ps ≤ 0.029), nighttime systolic BP (114 ± 9 vs. 108 ± 9 mmHg, P = 0.049), diastolic BP (63 ± 8 vs. 57 ± 7 mmHg, P = 0.010), and attenuated absolute systolic BP dipping (12 ± 5 vs. 9 ± 7 mmHg, P = 0.050). Black participants experienced greater average ADI scores compared with White participants [110 (10) vs. 97 (22), P = 0.002], and select ADI scores correlated with resting BP and some ambulatory BP measures. Within each race, select ADI scores correlated with some BP measures for Black participants, but there were no ADI and BP correlations for White participants. In conclusion, our findings suggest that neighborhood deprivation may contribute to higher resting BP and impaired ambulatory BP patterns in young adults warranting further investigation in larger cohorts.NEW & NOTEWORTHY We demonstrate that young Black adults exhibit higher resting blood pressure, nighttime blood pressure, and attenuated systolic blood pressure dipping compared with young White adults. Black adults were exposed to greater neighborhood deprivation, which demonstrated some associations with resting and ambulatory blood pressure. Our findings add to a growing body of literature indicating that neighborhood deprivation may contribute to increased blood pressure.

Advanced cardiovascular physiology in an individual with type 1 diabetes after 10-year ketogenic diet

Adults with type 1 diabetes (T1D) have an elevated risk for cardiovascular disease (CVD) compared with the general population. HbA1c is the primary modifiable risk factor for CVD in T1D. Fewer than 1% of patients achieve euglycemia (<5.7% HbA1c). Ketogenic diets (KD; ≤50 g carbohydrate/day) may improve glycemia and downstream vascular dysfunction in T1D by reducing HbA1c and insulin load. However, there are concerns regarding the long-term CVD risk from a KD. Therefore, we compared data collected in a 60-day window in an adult with T1D on exogenous insulin who consumed a KD for 10 years versus normative values in those with T1D (T1D norms). The participant achieved euglycemia with an HbA1c of 5.5%, mean glucose of 98 [5] mg/dL (median [interquartile range]), 90 [11]% time-in-range 70-180 mg/dL (T1D norms: 1st percentile for all), and low insulin requirements of 0.38 ± 0.03 IU/kg/day (T1D norms: 8th percentile). Seated systolic blood pressure (SBP) was 113 mmHg (T1D norms: 18th percentile), while ambulatory awake SBP was 132 ± 15 mmHg (T1D target: <130 mmHg), blood triglycerides were 69 mg/dL (T1D norms: 34th percentile), low-density lipoprotein was 129 mg/dL (T1D norms: 60th percentile), heart rate was 56 beats/min (T1D norms: >1SD below the mean), carotid-femoral pulse wave velocity was 7.17 m/s (T1D norms: lowest quartile of risk), flow-mediated dilation was 12.8% (T1D norms: >1SD above mean), and cardiac vagal baroreflex gain was 23.5 ms/mmHg (T1D norms: >1SD above mean). Finally, there was no indication of left ventricular diastolic dysfunction from echocardiography. Overall, these data demonstrate below-average CVD risk relative to T1D norms despite concerns regarding the long-term impact of a KD on CVD risk.NEW & NOTEWORTHY Adults with type 1 diabetes (T1D) have a 10-fold higher risk for cardiovascular disease (CVD) compared with the general population. We assessed cardiovascular health metrics in an adult with T1D who presented with a euglycemic HbA1c after following a ketogenic diet for the past 10 years. Despite concerns about the ketogenic diet increasing CVD risk, the participant exhibited below-average CVD risk relative to others with T1D when considering all outcomes together.

The effect of endothelin a receptor inhibition and biological sex on cutaneous microvascular function in non-Hispanic Black and White young adults

The purpose of this study was to investigate whether endothelin-A receptor (ETAR) inhibition in non-Hispanic Black (NHB) and White (NHW) young adults depends on biological sex. We recruited females during low hormone (n = 22) and high hormone (n = 22) phases, and males (n = 22). Participants self-identified as NHB (n = 33) or NHW (n = 33). Participants were instrumented with two microdialysis fibers: (1) lactated Ringer's (control) and (2) 500 nM BQ-123 (ETAR antagonist). Local heating was used to elicit cutaneous vasodilation, and an infusion of 20 mM L-NAME to quantify NO-dependent vasodilation. At control sites, NO-dependent vasodilation was lowest in NHB males (46 ± 13 %NO) and NHB females during low hormone phases (47 ± 12 %NO) compared to all NHW groups. Inhibition of ETAR increased NO-dependent vasodilation in NHB males (66 ± 13 %NO), in both groups of females during low hormone phases (NHW, control: 64 ± 12 %NO, BQ-123: 85 ± 11 %NO; NHB, BQ-123: 68 ± 13 %NO), and in NHB females during high hormone phases (control: 61 ± 11 %NO, BQ-123: 83 ± 9 %NO). There was no effect for ETAR inhibition in NHW males or females during high hormone phases. These data suggest the effect of ETAR inhibition on NO-dependent vasodilation is influenced by biological sex and racial identity.

The Impact of Vitamin D and L-Cysteine Co-Supplementation on Upregulating Glutathione and Vitamin D-Metabolizing Genes and in the Treatment of Circulating 25-Hydroxy Vitamin D Deficiency

Vitamin D receptors are expressed in many organs and tissues, which suggests that vitamin D (VD) affects physiological functions beyond its role in maintaining bone health. Deficiency or inadequacy of 25(OH)VD is widespread globally. Population studies demonstrate that a positive association exists between a high incidence of VD deficiency and a high incidence of chronic diseases, including dementia, diabetes, and heart disease. However, many subjects have difficulty achieving the required circulating levels of 25(OH)VD even after high-dose VD supplementation, and randomized controlled clinical trials have reported limited therapeutic success post-VD supplementation. Thus, there is a discordance between the benefits of VD supplementation and the prevention of chronic diseases in those with VD deficiency. Why this dissociation exists is currently under debate and is of significant public interest. This review discusses the downregulation of VD-metabolizing genes needed to convert consumed VD into 25(OH)VD to enable its metabolic action exhibited by subjects with metabolic syndrome, obesity, and other chronic diseases. Research findings indicate a positive correlation between the levels of 25(OH)VD and glutathione (GSH) in both healthy and diabetic individuals. Cell culture and animal experiments reveal a novel mechanism through which the status of GSH can positively impact the expression of VD metabolism genes. This review highlights that for better success, VD deficiency needs to be corrected at multiple levels: (i) VD supplements and/or VD-rich foods need to be consumed to provide adequate VD, and (ii) the body needs to be able to upregulate VD-metabolizing genes to convert VD into 25(OH)VD and then to 1,25(OH)2VD to enhance its metabolic action. This review outlines the association between 25(OH)VD deficiency/inadequacy and decreased GSH levels, highlighting the positive impact of combined VD+LC supplementation on upregulating GSH, VD-metabolizing genes, and VDR. These effects have the potential to enhance 25(OH)VD levels and its therapeutic efficacy.

Spectral changes in skin blood flow during pressure manipulations or sympathetic stimulation

Skin blood flow is commonly determined by laser Doppler flowmetry (LDF). It has been suggested that pathophysiological conditions can be assessed by analysis of specific frequency domains of the LDF signals. We tested whether physiological stimuli that activate myogenic and neurogenic mechanisms would affect relevant portions of the laser Doppler spectrum. LDF sensors were placed on the right forearm of 14 healthy volunteers for myogenic (six females) and 13 for neurogenic challenge (five females). Myogenic responses were tested by positioning the arm ∼50° above/below heart level. Neurogenic responses were tested by immersing the left hand into an ice slurry with and without topical application of local anaesthetic. Short-time Fourier analyses were computed over the range of 0.06 to 0.15 Hz for myogenic and 0.02 to 0.06 Hz for neurogenic. No significant differences in spectral density were observed (P = 0.40) in the myogenic range with arm above (7 ± 54 × 10-4 dB) and below heart (7 ± 14 × 10-4 dB). Neurogenic spectral density showed no significant increase from baseline to cold pressor test (0.0017 ± 0.0013 and 0.0038 ± 0.0039 dB; P = 0.087, effect size 0.47). After application of anaesthetic, neurogenic spectral density was unchanged between the baseline and cold pressor test (0.0014 ± 0.0025 and 0.0006 ± 0.0005 dB; P = 0.173). These results suggest that changes in the myogenic and neurogenic spectral density of LDF signals did not fully reflect the skin vascular function activated by pressure manipulation and sympathetic stimulation. Therefore, LDF myogenic and neurogenic spectral density data should be interpreted with caution.

Association Between Adequate Serum 25(OH)D Levels and Atherogenic Dyslipidemia in Young Adults

AIM

This study aimed to investigate the association between vitamin D deficiency and novel biomarkers of atherogenic dyslipidemia among young adults.

METHOD

A total of 976 young adults were recruited between 2011 and 2019. Their serum 25(OH)D levels were measured, and lipid profile markers, including low-density lipoprotein cholesterol (LDL-C), low-density lipoprotein triglyceride (LDL-TG), and small-dense low-density lipoprotein cholesterol (sdLDL-C), were assessed as novel biomarkers of atherogenic dyslipidemia. Multivariable linear regression was used to analyze the association between vitamin D levels and lipid profile markers. Odds ratios were calculated to assess the risk of atherogenic dyslipidemia in individuals with serum 25(OH)D levels below 30 ng/mL compared to those with levels above 30 ng/mL. Structural equation modeling (SEM) was employed to explore potential mediation pathways.

RESULTS

The study found a significant association between vitamin D levels and lower levels of LDL-C, LDL-TG, sdLDL-C, non-high-density lipoprotein cholesterol (non-HDL-C), triglycerides, and total cholesterol. Individuals with serum 25(OH)D levels below 30 ng/mL exhibited significantly higher odds ratios for developing atherogenic dyslipidemia in a dose-response pattern compared to those with vitamin D levels above 30 ng/mL. Notably, structural equation modeling (SEM) analysis revealed that vitamin D did not affect atherogenic lipid markers through the mediation of insulin resistance markers or high-sensitivity C-reactive protein.

CONCLUSION

This study provides evidence of an association between vitamin D deficiency and atherogenic dyslipidemia in young adults. It further highlights that individuals with serum 25(OH)D levels below 30 ng/mL are at a significantly higher risk of developing atherogenic dyslipidemia in a dose-response manner compared to those with higher vitamin D levels. These findings underscore the potential role of vitamin D in dyslipidemia management and emphasize the importance of maintaining sufficient vitamin D levels for cardiovascular health in young adults.

Inhibition of superoxide and iNOS augment cutaneous nitric oxide-dependent vasodilation in non-Hispanic black young adults

We assessed the combined effect of superoxide and iNOS inhibition on microvascular function in non-Hispanic Black and non-Hispanic White participants (n = 15 per group). Participants were instrumented with four microdialysis fibers: (1) lactated Ringer's (control), (2) 10 μM tempol (superoxide inhibition), (3) 0.1 mM 1400 W (iNOS inhibition), (4) tempol + 1400 W. Cutaneous vasodilation was induced via local heating and NO-dependent vasodilation was quantified. At control sites, NO-dependent vasodilation was lower in non-Hispanic Black (45 ± 9% NO) relative to non-Hispanic White (79 ± 9% NO; p < 0.01; effect size, d = 3.78) participants. Tempol (62 ± 16% NO), 1400 W (78 ± 12% NO) and tempol +1400 W (80 ± 13% NO) increased NO-dependent vasodilation in non-Hispanic Black participants relative to control sites (all p < 0.01; d = 1.22, 3.05, 3.03, respectively). The effect of 1400 W (p = 0.04, d = 1.11) and tempol +1400 W (p = 0.03, d = 1.22) was greater than tempol in non-Hispanic Black participants. There was no difference between non-Hispanic Black and non-Hispanic White participants at 1400 W or tempol + 1400 W sites. These data suggest iNOS has a greater effect on NO-dependent vasodilation than superoxide in non-Hispanic Black participants.

Vitamin D and ischemic stroke - Association, mechanisms, and therapeutics

Confronting the rising tide of ischemic stroke and its associated mortality and morbidity with ageing, prevention and acute management of ischemic stroke is of paramount importance. Mounting observational studies have established a non-linear association of vitamin D status with cardiovascular diseases, including ischemic stroke. Paradoxically, current clinical trials fail to demonstrate the cardiovascular benefits of vitamin D supplementation. We aim to update recent clinical and experimental findings on the role of vitamin D in the disease course of ischemic stroke, from its onset, progression, recovery, to recurrence, and the established and alternative possible pathophysiological mechanisms. This review justifies the necessities to address stroke etiological subtypes and focus on vitamin D-deficient subjects for investigating the potential of vitamin D supplementation as a preventive and therapeutic approach for ischemic stroke. Well-powered clinical trials are warranted to determine the efficacy, safety, timing, target individuals, optimal dosages, and target 25OHD concentrations of vitamin D supplementation in the prevention and treatment of ischemic stroke.

Cross-sectional analysis of racial differences in hydration and neighborhood deprivation in young adults

BACKGROUND

Inadequate hydration is associated with cardiovascular and kidney disease morbidity and all-cause mortality. Compared with White individuals, Black individuals exhibit a higher prevalence of inadequate hydration, which may contribute to racial health disparities. However, the underlying reasons for these differences in hydration remain unclear.

OBJECTIVE

This cross-sectional study aimed to investigate whether neighborhood deprivation contributes to racial differences in hydration status.

METHODS

We assessed 24 Black and 30 White college students, measuring 24-hour urine osmolality, urine flow rate, urine specific gravity, and plasma copeptin concentration. Participants recorded their food and fluid intake for 3 d to assess total water intake from food and beverages. Neighborhood socioeconomic deprivation was measured using a tract-level Area Deprivation Index.

RESULTS

Black participants exhibited higher urine osmolality (640 [314] compared with 440 [283] mOsm/kg H2O, respectively, P = 0.006) and lower urine flow rate (1.06 [0.65] compared with 1.71 [0.89] ml/min, respectively, P = 0.009) compared with White participants, indicating greater hypohydration among Black participants. Black participants reported lower total water intake from food and beverages than White participants (2.3 ± 0.7 compared with 3.5 ± 1.1 L/day, respectively, P < 0.01). Black participants exhibited higher copeptin than White participants (6.3 [3.1] compared with 4.5 [2.3] pmol/L, P = 0.046), and urine osmolality mediated 67% of the difference (P = 0.027). Black participants reported greater cumulative exposure to neighborhood deprivation during childhood (ages 0-18 y). Furthermore, neighborhood deprivation during childhood was associated with urine specific gravity (P = 0.031) and total water intake from food and beverages (P = 0.042) but did not mediate the racial differences in these measures.

CONCLUSION

Our data suggest that compared with White young adults, Black young adults are hypohydrated and exhibit higher plasma copeptin concentration, and that greater neighborhood deprivation is associated with chronic underhydration irrespective of race. This trial was registered at clinicaltrials.gov as NCT04576338.

Interplay of Race and Neighborhood Deprivation on Ambulatory Blood Pressure in Young Adults

Background

Ambulatory blood pressure (BP) monitoring measures nighttime BP and BP dipping, which are superior to in-clinic BP for predicting cardiovascular disease (CVD), the leading cause of death in America. Compared with other racial/ethnic groups, Black Americans exhibit elevated nighttime BP and attenuated BP dipping, including in young adulthood. Social determinants of health contribute to disparities in CVD risk, but the contribution of neighborhood deprivation on nighttime BP is unclear. Therefore, we examined associations between neighborhood deprivation with nighttime BP and BP dipping in young Black and White adults.

Methods

We recruited 21 Black and 26 White participants (20 M/27 F, mean age: 21 years, body mass index: 25±4 kg/m2) for 24-hour ambulatory BP monitoring. We assessed nighttime BP and BP dipping (nighttime:daytime BP ratio). The area deprivation index (ADI) was used to measure neighborhood deprivation. Associations between ADI and ambulatory BP were examined.

Results

Black participants exhibited higher nighttime diastolic BP compared with White participants (63±8 mmHg vs 58±7 mmHg, p=0.003), and attenuated BP dipping ratios for both systolic (0.92±0.06 vs 0.86±0.05, p=0.001) and diastolic BP (0.86±0.09 vs 0.78±0.08, p=0.007). Black participants experienced greater neighborhood deprivation compared with White participants (ADI scores: 110±8 vs 97±21, p<0.001), and ADI was associated with attenuated systolic BP dipping (ρ=0.342, p=0.019).

Conclusions

Our findings suggest neighborhood deprivation may contribute to higher nighttime BP and attenuated BP dipping, which are prognostic of CVD, and more prevalent in Black adults. Targeted interventions to mitigate the effects of neighborhood deprivation may help to improve nighttime BP.

Clinical Trial Registry

URL: https://www.clinicaltrials.gov; Unique identifier: NCT04576338.

Impact of Environmental Factors on Hypertension and Associated Cardiovascular Disease

Hypertension is the primary cause of cardiovascular diseases and is responsible for nearly 9 million deaths worldwide annually. Increasing evidence indicates that in addition to pathophysiologic processes, numerous environmental factors, such as geographic location, lifestyle choices, socioeconomic status, and cultural practices, influence the risk, progression, and severity of hypertension, even in the absence of genetic risk factors. In this review, we discuss the impact of some environmental determinants on hypertension. We focus on clinical data from large population studies and discuss some potential molecular and cellular mechanisms. We highlight how these environmental determinants are interconnected, as small changes in one factor might affect others, and further affect cardiovascular health. In addition, we discuss the crucial impact of socioeconomic factors and how these determinants influence diverse communities with economic disparities. Finally, we address opportunities and challenges for new research to address gaps in knowledge on understanding molecular mechanisms whereby environmental factors influence development of hypertension and associated cardiovascular disease.

Acute beetroot juice reduces blood pressure in young Black and White males but not females

A complex interplay of social, lifestyle, and physiological factors contribute to Black Americans having the highest blood pressure (BP) in America. One potential contributor to Black adult's higher BP may be reduced nitric oxide (NO) bioavailability. Therefore, we sought to determine whether augmenting NO bioavailability with acute beetroot juice (BRJ) supplementation would reduce resting BP and cardiovascular reactivity in Black and White adults, but to a greater extent in Black adults. A total of 18 Black and 20 White (∼equal split by biological sex) young adults completed this randomized, placebo-controlled (nitrate (NO3-)-depleted BRJ), crossover design study. We measured heart rate, brachial and central BP, and arterial stiffness (via pulse wave velocity) at rest, during handgrip exercise, and during post-exercise circulatory occlusion. Compared with White adults, Black adults exhibited higher pre-supplementation resting brachial and central BP (Ps ≤0.035; e.g., brachial systolic BP: 116(11) vs. 121(7) mmHg, P = 0.023). Compared with placebo, BRJ (∼12.8 mmol NO3-) reduced resting brachial systolic BP similarly in Black (Δ-4±10 mmHg) and White (Δ-4±7 mmHg) adults (P = 0.029). However, BRJ supplementation reduced BP in males (Ps ≤ 0.020) but not females (Ps ≥ 0.299). Irrespective of race or sex, increases in plasma NO3- were associated with reduced brachial systolic BP (ρ = -0.237, P = 0.042). No other treatment effects were observed for BP or arterial stiffness at rest or during physical stress (i.e., reactivity); Ps ≥ 0.075. Despite young Black adults having higher resting BP, acute BRJ supplementation reduced systolic BP in young Black and White adults by a similar magnitude, an effect that was driven by males.

Contribution of sensory nerves to cutaneous reactive hyperaemia in non-Hispanic Black and White young adults

NEW FINDINGS

What is the central question of this study? Does cutaneous sensory nerve-mediated vasodilatation differ between non-Hispanic Black and White young adults? What is the main finding and its importance? The magnitude of cutaneous reactive hyperaemia is lower in non-Hispanic Black relative to non-Hispanic White young adults, but the overall sensory nerve contribution is the same, suggesting that sensory nerve function is similar in both non-Hispanic Black and White young adults.

ABSTRACT

The aim of this study was to assess cutaneous sensory nerve function, independent of nitric oxide, in non-Hispanic Black and White young adults. We tested the hypothesis that cutaneous reactive hyperaemia and sensory nerve-mediated vasodilatation would be lower in non-Hispanic Black young adults relative to non-Hispanic White young adults. Twenty-four participants who self-identified as non-Hispanic Black (n = 12) or non-Hispanic White (n = 12) were recruited. All participants underwent three bouts of reactive hyperaemia. An index of skin blood flow was measured continuously using laser-Doppler flowmetry at a control site and at a site treated with topical 4% lignocaine to inhibit sensory nerve function. Peak reactive hyperaemia was lower in non-Hispanic Black relative to non-Hispanic White participants (P < 0.001). Total reactive hyperaemia was lower in non-Hispanic Black [mean (SD); control, 4085 (955)%CVCmax  s; lignocaine, 2127 (639) percent maximal cutaneous vascular conductance * seconds, %CVCmax  s] relative to non-Hispanic White [control: 6820 (1179)%CVCmax  s; lignocaine, 3573 (712)%CVCmax  s] participants (P < 0.001 for both sites). There was no difference between groups for the calculated contribution of sensory nerves to either the peak [non-Hispanic Black, 25 (14)%; non-Hispanic White, 19 (13)%] or total reactive hyperaemic response [non-Hispanic Black, 48 (10)%; non-Hispanic White, 47 (10)%]. These data suggest that cutaneous reactive hyperaemia is lower in non-Hispanic Black young adults, but the sensory nerve contribution is similar in non-Hispanic Black and White young adults.

Within-limb variation in skin pigmentation does not influence cutaneous vasodilation

Ultraviolet radiation (UVR) exposure acutely reduces nitric oxide (NO)-dependent cutaneous vasodilation. In addition, increased constitutive skin melanin is associated with attenuated NO-dependent cutaneous vasodilation. However, the impact of within-limb variation in skin melanization, associated with seasonal UVR exposure, on NO-dependent cutaneous vasodilation is unknown. We investigated the effect of within-limb variation in skin melanin on NO-dependent cutaneous vasodilation. Intradermal microdialysis fibers were placed in the inner-upper arm, ventral forearm, and dorsal forearm of seven adults (33 ± 14 yr; 4 M/3 F) with constitutively light skin pigmentation. Melanin-index (M-index; an index of skin pigmentation), measured via reflectance spectrophotometry, confirmed differences in sun exposure among sites. A standardized local heating (42°C) protocol induced cutaneous vasodilation. After attaining a stable elevated blood flow plateau, 15 mM NG-nitro-l-arginine methyl ester (l-NAME; NO synthase inhibitor) was infused to quantify the NO contribution. Laser-Doppler flowmetry (LDF) measured red cell flux and cutaneous vascular conductance (CVC = LDF/mean arterial pressure) and was normalized to maximal (%CVCmax; 28 mM sodium nitroprusside + 43°C local heating). Dorsal forearm M-index was higher [50.5 ± 11.8 au (arbitrary units)] compared with the ventral forearm (37.5 ± 7.4 au; P ≤ 0.03) and upper arm (30.0 ± 4.0 au; P ≤ 0.001) M-index. Cutaneous vasodilation responses to local heating were not different among sites (P ≥ 0.12). Importantly, neither the magnitude of the local heating plateau (dorsal: 85 ± 21%; ventral: 70 ± 21%; upper: 87 ± 15%; P ≥ 0.16) nor the NO-mediated component of that response (dorsal: 59 ± 15%; ventral: 54 ± 13%; upper: 55 ± 11%; P ≥ 0.79) was different among sites. These data suggest that within-limb differences in skin pigmentation secondary to seasonal UVR exposure do not alter NO-dependent cutaneous vasodilation.NEW & NOTEWORTHY Locally derived endothelial nitric oxide (NO) contributes to the full expression of cutaneous vasodilation responses. Acute ultraviolet radiation (UVR) exposure attenuates NO-mediated vasodilation of the cutaneous microvasculature. Our findings suggest that in constitutively lightly pigmented skin, variation in skin melanin due to seasonal exposure to UVR does not alter the NO contribution to cutaneous vasodilation. Seasonal UVR exposure does not impact the NO-mediated cutaneous microvascular function.

Endothelin A receptor inhibition increases nitric oxide-dependent vasodilation independent of superoxide in non-Hispanic Black young adults

Young non-Hispanic Black adults have reduced microvascular endothelial function compared with non-Hispanic White counterparts, but the mechanisms are not fully elucidated. The purpose of this study was to investigate the effect of endothelin-1 A receptor (ET_AR) and superoxide on cutaneous microvascular function in young non-Hispanic Black (n = 10) and White (n = 10) adults. Participants were instrumented with four intradermal microdialysis fibers: 1) lactated Ringer's (control), 2) 500 nM BQ-123 (ET_AR antagonist), 3) 10 μM tempol (superoxide dismutase mimetic), and 4) BQ-123 + tempol. Skin blood flow was assessed via laser-Doppler flowmetry (LDF), and each site underwent rapid local heating from 33°C to 39°C. At the plateau of local heating, 20 mM l-NAME [nitric oxide (NO) synthase inhibitor] was infused to quantify NO-dependent vasodilation. Data are means ± standard deviation. NO-dependent vasodilation was decreased in non-Hispanic Black compared with non-Hispanic White young adults (P < 0.01). NO-dependent vasodilation was increased at BQ-123 sites (73 ± 10% NO) and at BQ-123 + tempol sites (71 ± 10%NO) in non-Hispanic Black young adults compared with control (53 ± 13%NO, P = 0.01). Tempol alone had no effect on NO-dependent vasodilation in non-Hispanic Black young adults (63 ± 14%NO, P = 0.18). NO-dependent vasodilation at BQ-123 sites was not statistically different between non-Hispanic Black and White (80 ± 7%NO) young adults (P = 0.15). ET_AR contributes to reduced NO-dependent vasodilation in non-Hispanic Black young adults independent of superoxide, suggesting a greater effect on NO synthesis rather than NO scavenging via superoxide.NEW & NOTEWORTHY Endothelin-1 A receptors (ET_ARs) have been shown to reduce endothelial function independently and through increased production of superoxide. We show that independent ET_AR inhibition increases microvascular endothelial function in non-Hispanic Black young adults. However, administration of a superoxide dismutase mimetic alone and in combination with ET_AR inhibition had no effect on microvascular endothelial function suggesting that, in the cutaneous microvasculature, the negative effects of ET_AR in non-Hispanic Black young adults are independent of superoxide production.

Vitamin D and neurodegenerative diseases

Neurodegenerative diseases, featured by progressive loss of structure or function of neurons, are considered incurable at present. Movement disorders like tremor and postural instability, cognitive or behavioral disorders such as memory impairment are the most common symptoms of them and the growing patient population of neurodegenerative diseases poses a serious threat to public health and a burden on economic development. Hence, it is vital to prevent the occurrence of the diseases and delay their progress. Vitamin D can be transformed into a hormone in vivo with both genomic and non-genomic actions, exerting diverse physiological effects. Cumulative evidence indicates that vitamin D can ameliorate neurodegeneration by regulating pertinent molecules and signaling pathways including maintaining Ca²⁺ homeostasis, reducing oxidative stress, inhibiting inflammation, suppressing the formation and aggregation of the pathogenic protein, etc. This review updates discoveries of molecular mechanisms underlying biological functions of vitamin D in neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, multiple sclerosis, and vascular dementia. Clinical trials investigating the influence of vitamin D supplementation in patients with neurodegenerative diseases are also summarized. The synthesized information will probably provoke an enhanced understanding of the neuroprotective roles of vitamin D in the nervous system and provide therapeutic options for patients with neurodegenerative diseases in the future.

Post-Inflammatory Hyperpigmentation in Dark Skin: Molecular Mechanism and Skincare Implications

Human skin is characterized by significant diversity in color and tone, which are determined by the quantity and distribution of melanin pigment in the epidermis. Melanin absorbs and reflects ultraviolet radiation (UVR), preventing the damage to genomic DNA in the epidermis and degradation of collagen in the dermis; therefore, darker skin types are thought to be well protected from the photodamage because of the high melanin content. However, increased content of melanin in combination with the extrinsic stress factors causing inflammation such as excess UVR, allergic reactions, or injury can also frequently lead to cosmetic problems resulting in discoloration and scarring. This review summarizes current knowledge on histopathology and likely molecular signatures of one of the most common problems, post-inflammatory hyperpigmentation (PIH). The mechanisms proposed so far are subsequently discussed in the context of other factors characterizing darker skin types. This includes the common cellular features, organization of upper skin layers, and major biomarkers, with particular emphasis on increased propensities to systemic and localized inflammation. Enhanced or prolonged inflammatory responses can not only affect the process of melanogenesis but also have been implicated in injury-related skin pathologies and aging. Finally, we summarize the major cosmetic treatments for PIH and their known anti-inflammatory targets, which can be beneficial for darker skin tones and combined with broad-spectrum filters against UVR.

Skin pigmentation is negatively associated with circulating vitamin D concentration and cutaneous microvascular endothelial function

Darkly pigmented individuals are at the greatest risk of hypovitaminosis D, which may result in microvascular endothelial dysfunction via reduced nitric oxide (NO) bioavailability and/or increased oxidative stress and inflammation. We investigated the associations among skin pigmentation (M-index; skin reflectance spectrophotometry), serum vitamin D concentration [25(OH)D], circulating inflammatory cytokine (TNF-α, IL-6, and IL-10) concentrations, and the NO contribution to local heating-induced cutaneous vasodilation (%NO-mediated vasodilation) in a diversely pigmented cohort of young adults. An intradermal microdialysis fiber was placed in the forearms of 33 healthy adults (14 men/19 women; 18-27 yr; M-index, 30-81 AU) for local delivery of pharmacological agents. Lactated Ringer's solution was perfused through the fiber during local heating-induced (39°C) cutaneous vasodilation. After attaining stable elevated blood flow, 15 mM NG-nitro-l-arginine methyl ester (l-NAME; NO synthase inhibiter) was infused to quantify %NO-mediated vasodilation. Red cell flux was measured (laser-Doppler flowmetry; LDF) and cutaneous vascular conductance (CVC = LDF/MAP) was normalized to maximal (%CVCmax; 28 mM sodium nitroprusside + 43°C). Serum [25(OH)D] and circulating cytokines were analyzed by ELISA and multiplex assay, respectively. M-index was negatively associated with [25(OH)D] (r = -0.57, P < 0.0001) and %NO-mediated vasodilation (r = -0.42, P = 0.02). Serum[25(OH)D] was positively related to %NO (r = 0.41, P = 0.02). Controlling for [25(OH)D] weakened the association between M-index and %NO-mediated dilation (P = 0.16, r = -0.26). There was a negative curvilinear relation between [25(OH)D] and circulating IL-6 (r = -0.56, P < 0.001), but not TNF-α or IL-10 (P ≥ 0.14). IL-6 was not associated with %NO-mediated vasodilation (P = 0.44). These data suggest that vitamin D insufficiency/deficiency may contribute to reduced microvascular endothelial function in healthy, darkly pigmented young adults.NEW & NOTEWORTHY Endothelial dysfunction, an antecedent to hypertension and overt CVD, is commonly observed in otherwise healthy Black adults, although the underlying causes remain unclear. We show that reduced vitamin D availability with increasing degrees of skin pigmentation is associated with reduced microvascular endothelial function, independent of race or ethnicity, in healthy young adults. Greater prevalence of vitamin D deficiency in more darkly pigmented individuals may predispose them to increased risk of endothelial dysfunction.

Nitric oxide-related gene and microRNA expression in peripheral blood in pregnancy vary by self-reported race

Adverse pregnancy outcomes disproportionately affect non-Hispanic (NH) Black patients in the United States. Structural racism has been associated with increased psychosocial distress and inflammation and may trigger oxidative stress. Thus, the nitric oxide (NO) pathway (involved in the regulation of inflammation and oxidative stress) may partly explain the underlying disparities in obstetric outcomes.Cohort study of 154 pregnant patients with high-risk obstetric histories; n = 212 mRNAs and n = 108 microRNAs (miRNAs) in the NO pathway were evaluated in circulating white blood cells. NO pathway mRNA and miRNA transcript counts were compared by self-reported race; NH Black patients were compared with women of other races/ethnicities. Finally, miRNA-mRNA expression levels were correlated.Twenty-two genes (q < 0.10) were differentially expressed in self-identified NH Black individuals. Superoxide dismutase 1 (SOD1), interleukin-8 (IL-8), dynein light chain LC8-type 1 (DYNLL1), glutathione peroxidase 4 (GPX4), and glutathione peroxidase 1 (GPX1) were the five most differentially expressed genes among NH Black patients compared to other patients. There were 63 significantly correlated miRNA-mRNA pairs (q < 0.10) demonstrating potential miRNA regulation of associated target mRNA expression. Ten miRNAs that were identified as members of significant miRNA-mRNA pairs were also differentially expressed among NH Black patients (q < 0.10).These findings support an association between NO pathway and inflammation and infection-related mRNA and miRNA expression in blood drawn during pregnancy and patient race/ethnicity. These findings may reflect key differences in the biology of inflammatory gene dysregulation that occurs in response to the stress of systemic racism and that underlies disparities in pregnancy outcomes.

Short-term salicylate treatment improves microvascular endothelium-dependent dilation in young adults with major depressive disorder

Reactive oxygen species (ROS)-mediated reductions in nitric oxide (NO)-dependent dilation are evident in adults with major depressive disorder (MDD); however, the upstream mechanisms remain unclear. Here, we hypothesized that nuclear factor-κB (NF-κB) activation-induced ROS production contributes to microvascular endothelial dysfunction in MDD. Thirteen treatment-naive adults with MDD (6 women; 19-23 yr) and 10 healthy nondepressed adults (HAs; 5 women; 20-25 yr) were tested before and after (open-label design) systemic NF-κB knockdown (nonacetylated salicylate; 3,000-4,500 mg/day × 4 days). Red cell flux (laser Doppler flowmetry) was measured during graded intradermal microdialysis perfusion of the endothelium-dependent agonist acetylcholine (ACh), alone and in combination with NO synthase inhibition [NG-nitro-l-arginine methyl ester (l-NAME)] or ROS scavenging (apocynin). Serum salicylate concentrations following treatment were not different between groups (22.8 ± 7.4 HAs vs. 20.8 ± 4.3 mg/dL MDD; P = 0.46). When compared with HAs, the NO-dependent component of ACh-induced dilation was blunted in adults with MDD before (P = 0.023), but not after (P = 0.27), salsalate treatment. In adults with MDD, the magnitude of improvement in endothelium-dependent dilation following salsalate treatment was inversely related to the degree of functional impairment at baseline (R2 = 0.43; P = 0.025). Localized ROS scavenging improved NO-dependent dilation before (P < 0.01), but not after (P > 0.05), salsalate treatment. Salsalate did not alter systemic concentrations of pro- or anti-inflammatory cytokines (all P > 0.05). These data suggest that NF-κB activation, via increased vascular ROS production, contributes to blunted NO-dependent dilation in young adults with MDD but otherwise free of clinical disease. These data provide the first direct evidence for a mechanistic role of vascular inflammation-associated endothelial dysfunction in human depression.NEW & NOTEWORTHY Our data indicate that short-term treatment with therapeutic doses of the nuclear factor-κB (NF-κB) inhibitor salsalate improved nitric oxide (NO)-mediated endothelium-dependent dilation in adults with major depressive disorder (MDD). In adults with MDD, acute localized scavenging of reactive oxygen species (ROS) with apocynin improved NO-dependent dilation before, but not after, salsalate administration. These data suggest that activation of NF-κB, in part via stimulation of vascular ROS production, contributes to blunted NO-mediated endothelium-dependent dilation in young adults with MDD.

Cholecalciferol supplementation lowers leptin and TMAO but increases NO and VEGF-A levels in obese vitamin D deficient patients: Is it one of the potential cardioprotective mechanisms of vitamin D?

Background

Vitamin D deficiency is one of the most common health issues in developed countries. Obese patients are most at risk of having serum 25-hydroxyvitamin D₃ (25(OH)D₃) levels that are too low due to the accumulation of vitamin D in adipose tissue. While the effects of a deficiency on the skeletal or immune system are known, the effects on the cardiovascular system are not yet clear. Our study investigates the effect of cholecalciferol supplementation in obese patients on selected biomarkers associated with cardiovascular diseases (CVDs).

Methods

The study enrolled 33 obese patients with insufficient 25(OH)D₃ levels. For three months, the subjects supplemented with cholecalciferol at a dose of 2000 IU/day. Concentrations of nitric oxide (NO), vascular endothelial growth factor A (VEGF-A), leptin, trimethylamine N-oxide (TMAO) and soluble suppression of tumorigenicity 2 (sST2) were measured in baseline samples using ELISA (BioTek EPOCH). 25(OH)D₃ levels measured on Beckman Coulter DXI 800 by chemiluminescence method.

Results

After supplementation, 25(OH)D₃ levels increased significantly. Normal levels were achieved in most patients. A statistically significant reduction leptin and TMAO levels was observed. At the same time, NO and VEGF-A levels increased statistically significantly.

Conclusion

This study indicates that restoring normal 25(OH)D₃ levels in obese people reduces the concentration of pro-inflammatory factors associated with cardiovascular diseases. Reducing inflammation and the potential impact on vascular reactivity leads to the conclusion that cholecalciferol supplementation in obese patients may benefit the cardiovascular system.

Racial and ethnic disparities in cardiometabolic disease and COVID-19 outcomes in White, Black/African American, and Latinx populations: Social determinants of health

Racial and ethnic-related health disparities in the United States have been intensified by the greater burden of Coronavirus Disease 2019 (COVID-19) in racial and ethnic minority populations. Compared to non-Hispanic White individuals, non-Hispanic Black and Hispanic/Latinx individuals infected by COVID-19 are at greater risk for hospitalization, intensive care unit admission, and death. There are several factors that may contribute to disparities in COVID-19-related severity and outcomes in these minority populations, including the greater burden of cardiovascular and metabolic diseases as discussed in our companion review article. Social determinants of health are a critical, yet often overlooked, contributor to racial and ethnic-related health disparities in non-Hispanic Black and Hispanic/Latinx individuals relative to non-Hispanic White individuals. Thus, the purpose of this review is to focus on the essential role of social factors in contributing to health disparities in chronic diseases and COVID-19 outcomes in minority populations. Herein, we begin by focusing on structural racism as a social determinant of health at the societal level that contributes to health disparities through downstream social level (e.g., occupation and residential conditions) and individual level health behaviors (e.g., nutrition, physical activity, and sleep). Lastly, we conclude with a discussion of practical applications and recommendations for future research and public health efforts that seek to reduce health disparities and overall disease burden.

Reactive hyperemia augments local heat-induced skin hyperemia

NEW FINDINGS

What is the central question of this study? It is valuable to be able to monitor disease or treatment related changes in the microcirculation. Laser doppler flowmetry with local heating allows noninvasive monitoring of the skin microcirculation and its ability to vasodilate. Does reactive hyperemia augment the increase in skin blood flow elicited by local heating? What is the main finding and its importance? The results of this study show that the addition of reactive hyperemia to local heating results in greater vasodilation than heating alone. Thus, reactive hyperemia can augment local heat-induced hyperemia in the skin.

ABSTRACT

The skin circulation has been proposed as a model of generalized microvascular function which could be monitored noninvasively using laser doppler flowmetry (LDF). The response to heat hyperemia (HH) is commonly used to monitor disease or treatment related changes in microvascular function. We hypothesized that reactive hyperemia would augment the increase in skin blood flow elicited by local heating. Fourteen healthy young adults were subjected to 3 different conditions: reactive hyperemia (RH; skin temperature controlled at 33°C), heat hyperemia (HH; 42°C held for 40 minutes), and HH+RH. Two Peltier-controlled thermomodules with laser LDF probes were placed on the right forearm to continuously monitor skin blood flow. A cuff was placed on the right upper arm to elicit RH by inflation to 220 mmHg for 5 minutes. This procedure was performed with skin temperature at 33°C and again after 40 min of local heating to 42°C. Beat-by-beat mean arterial pressure (MAP) obtained by a photoplethysmographic sensor on the middle finger of the left hand allowed calculation of cutaneous vascular conductance (CVC) as LDF / MAP. Both HH and RH increased LDF (p<0.0001 and p <0.0001, respectively) and CVC (p = 0.0001 and p<0.0001) above baseline values. LDF and CVC values were significantly higher during HH+RH when compared to RH or HH alone (p<0.0001). In summary, HH+RH resulted in greater vasodilation when compared to HH or RH alone. These results indicate that RH can augment local heat-induced hyperemia in the skin. This article is protected by copyright. All rights reserved.

Nitric oxide-mediated cutaneous microvascular function is not altered in young adults following mild-to-moderate SARS CoV-2 infection

Vascular dysfunction has been reported in adults who have recovered from COVID-19. To date, no studies have investigated the underlying mechanisms of persistent COVID-19-associated vascular dysfunction. Our purpose was to quantify nitric oxide (NO)-mediated vasodilation in healthy adults who have recovered from SARS-CoV-2 infection. We hypothesized that COVID-19-recovered adults would have impaired NO-mediated vasodilation compared with adults who have not had COVID-19. In methods, we performed a cross-sectional study including 10 (5 men/5 women, 24 ± 4 yr) healthy control (HC) adults who were unvaccinated for COVID-19, 11 (4 men/7 women, 25 ± 6 yr) healthy vaccinated (HV) adults, and 12 (5 men/7 women, 22 ± 3 yr) post-COVID-19 (PC, 19 ± 14 wk) adults. COVID-19 symptoms severity (survey) was assessed. A standardized 39°C local heating protocol was used to assess NO-dependent vasodilation via perfusion (intradermal microdialysis) of 15 mM NG-nitro-l-arginine methyl ester during the plateau of the heating response. Red blood cell flux was measured (laser-Doppler flowmetry) and cutaneous vascular conductance (CVC = flux/mmHg) was expressed as a percentage of maximum (28 mM sodium nitroprusside + 43°C). In results, the local heating plateau (HC: 61 ± 20%, HV: 60 ± 19%, PC: 67 ± 19%, P = 0.80) and NO-dependent vasodilation (HC: 77 ± 9%, HV: 71 ± 7%, PC: 70 ± 10%, P = 0.36) were not different among groups. Neither symptom severity (25 ± 12 AU) nor time since diagnosis correlated with the NO-dependent vasodilation (r = 0.46, P = 0.13; r = 0.41, P = 0.19, respectively). In conclusion, healthy adults who have had mild-to-moderate COVID-19 do not have altered NO-mediated cutaneous microvascular function.NEW & NOTEWORTHY Healthy young adults who have had mild-to-moderate COVID-19 do not display alterations in nitric oxide-mediated cutaneous microvascular function. In addition, healthy young adults who have COVID-19 antibodies from the COVID-19 vaccinations do not display alterations in nitric oxide-mediated cutaneous microvascular function.

Protective actions of vitamin D, anandamide and melatonin during vascular inflammation: Epigenetic mechanisms involved

Vascular inflammation is one of the main activating stimuli of cardiovascular disease and its uncontrolled development may worsen the progression and prognosis of these pathologies. Therefore, the search for new therapeutic options to treat this condition is undoubtedly needed. In this regard, it may be better to repurpose endogenous anti-inflammatory compounds already known, in addition to synthesizing new compounds for therapeutic purposes. It is well known that vitamin D, anandamide, and melatonin are promising endogenous substances with powerful and wide-spread anti-inflammatory properties. Currently, the epigenetic mechanisms underlying these effects are often unknown. This review summarizes the potential epigenetic mechanisms by which vitamin D, anandamide, and melatonin attenuate vascular inflammation. This information could contribute to the improvement in the therapeutic management of multiple pathologies associated with blood vessel inflammation, through the pharmacological manipulation of new target sites that until now have not been addressed.

Na+-K+-ATPase plays a major role in mediating cutaneous thermal hyperemia achieved by local skin heating to 39°C

Na⁺-K⁺-ATPase is integrally involved in mediating cutaneous vasodilation during an exercise-heat stress, which includes an interactive role with nitric oxide synthase (NOS). Here, we assessed if Na⁺-K⁺-ATPase also contributes to cutaneous thermal hyperemia induced by local skin heating, which is commonly used to assess cutaneous endothelium-dependent vasodilation. Furthermore, we assessed the extent to which NOS contributes to this response. Cutaneous vascular conductance (CVC) was measured continuously at four forearm skin sites in 11 young adults (4 women). After baseline measurement, local skin temperature was increased from 33°C to 39°C to induce cutaneous thermal hyperemia. Once a plateau in CVC was achieved, each skin site was continuously perfused via intradermal microdialysis with either: 1) lactated Ringer solution (control), 2) 6 mM ouabain, a Na⁺-K⁺-ATPase inhibitor, 3) 20 mM l-NAME, a NOS inhibitor, or 4) a combination of both. Relative to the control site, CVC during the plateau phase of cutaneous thermal hyperemia (∼50% max) was reduced by the lone inhibition of Na⁺-K⁺-ATPase (-19 ± 8% max, P = 0.038) and NOS (-32 ± 4% max, P < 0.001), as well as the combined inhibition of both (-37 ± 9% max, P < 0.001). The magnitude of reduction was similar between NOS inhibition alone and combined inhibition (P = 1.000). The administration of both Na⁺-K⁺-ATPase and NOS inhibitors fully abolished the plateau of CVC with values returning to preheating baseline values (P = 0.439). We show that Na⁺-K⁺-ATPase contributes to cutaneous thermal hyperemia during local skin heating to 39°C, and this response is partially mediated by NOS.NEW & NOTEWORTHY Cutaneous thermal hyperemia during local skin heating to 39°C, which is highly dependent on nitric oxide synthase (NOS), is frequently used to assess endothelium-dependent cutaneous vasodilation. We showed that Na⁺-K⁺-ATPase mediates the regulation of cutaneous thermal hyperemia partly via NOS-dependent mechanisms although a component of the Na⁺-K⁺-ATPase modulation of cutaneous thermal hyperemia is NOS independent. Thus, as with NOS, Na⁺-K⁺-ATPase may be important in the regulation of cutaneous endothelial vascular function.

Effects of calcitriol on peripheral endothelial progenitor cells and renal renovation in rats with chronic renal failure

BACKGROUND

The role of calcitriol (1,25-dihydroxyvitamin D₃ or 1,25-(OH)₂D₃) in physiological processes, such as anti-fibrosis, anti-inflammation, and immunoregulation is known; however, its role in the remodeling of the glomerular capillary endothelium in rats with chronic renal failure (CRF) remains unclear.

METHODS

Here, we analyzed the role/number of endothelial progenitor cells (EPCs), renal function, and pathological alterations in rats with CRF, and compared the results before and after supplementation with calcitriol in vivo.

RESULTS

Amongst the three experimental groups (sham group, CRF group, and calcitriol-treated group (0.03 μg/kg/d), we observed substantially elevated cell adhesion and vasculogenesis in vivo in the calcitriol-treated group. Additionally, lower levels of serum creatinine (Scr) and blood urea nitrogen (BUN) was recorded in the calcitriol-treated group than the CRF group (p > 0.05). Calcitriol treatment also resulted in an improvement in renal pathological injury.

CONCLUSIONS

Thus, calcitriol could ameliorate the damage of glomerular arterial structural and renal tubules vascular network integrity, maybe through regulating the number and function of EPCs in the peripheral blood of CRF rats. Treatment with it may improve outcomes in patients with renal insufficiency or combined cardiac insufficiency. Calcitriol could ameliorate CRF-induced renal pathological injury and renal dysfunction by remodeling of the glomerular capillary endothelium, thus, improving the function of glomerular endothelial cells.

Skin pigmentation and vitamin D-folate interactions in vascular function: an update

PURPOSE OF REVIEW

Vitamin D and folate promote vascular endothelial health and may therefore help mitigate the development of cardiovascular disease (CVD). Ultraviolet radiation (UVR) exposure stimulates cutaneous vitamin D synthesis but degrades the bioactive metabolite of folate, 5-methyltetrahydrofolate (5-MTHF). Skin melanin absorbs UVR, thereby modulating the impact of UVR exposure on vitamin D and 5-MTHF metabolism. This review presents recent findings regarding the inter-relations among UVR, skin pigmentation, folate and vitamin D, and endothelial function.

RECENT FINDINGS

Evidence for roles of folic acid or vitamin D supplementation on CVD endpoints is inconsistent, although preclinical and clinical studies have demonstrated the efficacy of both micronutrients for improving endothelial function. Vitamin D deficiency is most prevalent in darkly pigmented individuals living in relatively low-UVR environments. Conversely, there is a negative relation between accumulated UVR exposure and serum folate concentration in lightly pigmented adults. The interactions among UVR and bioavailable folate and vitamin D differentially impact endothelial function in differently pigmented skin.

SUMMARY

UVR exposure disparately impacts folate and vitamin D metabolism in differently pigmented skin depending upon regional UVR intensity and seasonality. These findings present new clinical research questions regarding the interactions among UVR, skin pigmentation, folate and vitamin D bioavailability, and endothelial health.

Serum of limb remote ischemic postconditioning inhibits fMLP-triggered activation and reactive oxygen species releasing of rat neutrophils

Objectives

The study explores the protective role of the peripheral serum of limb remote ischemic postconditioning (LRIP) in reducing the reactive oxygen species (ROS) levels and neutrophil activation, which are responsible for the deleterious reperfusion injury.

Methods

LRIP was induced in Sprague–Dawley rats by three cycles of 5 min occlusion /5 min reperfusion on the left hind limb. The blood samples were collected before LRIP or 0 and 1 h after LRIP (named Serum_Sham, Serum_LRIP0, Serum_LRIP1, respectively). The effects of LRIP serum on ROS level and neutrophils activation were determined. The expression of MyD88-TRAF6-MAPKs and PI3K/AKT pathways in neutrophils were examined.

Results

When compared with Serum_Sham, Serum_LRIP0 and Serum_LRIP1 significantly reduced the ROS released from neutrophils activated by fMLP. Meanwhile, the mRNA expression levels of NADPH oxidase subunit p22^phox and multiple ROS-producing related key proteins, such as NADPH oxidase subunit p47^phox ser 304, ser 345. MyD88, p-ERK, p-JNK and p-P38 expression of neutrophils were downregulated by Serum_LRIP0 and Serum_LRIP1. Serum_LRIP1 also downregulated p47^phox mRNA expression and tumor necrosis factor receptor-associated factor 6 (TRAF6) protein expression.

Conclusion

LRIP serum protects against ROS level and neutrophils activation involving the MyD88-TRAF6-MAPKs. This finding provides new insight into the understanding of LRIP mechanisms.

Impact of Vitamin D Supplementation on Inflammatory Markers' Levels in Obese Patients

In view of research suggesting a possible beneficial impact of vitamin D on systemic inflammatory response, the authors decided to investigate an influence of vitamin D supplementation on serum levels of certain inflammatory markers in obese patients. The current study included such biomarkers as interleukin-6 (IL-6), pituitary adenylate cyclase-activating peptide (PACAP), advanced oxidation protein products (AOPP), C-X3-C Motif Chemokine Ligand 1 (CX3CL1), monocyte chemoattractant protein-1 (MCP-1), and nitric oxide (NO). The measurements were performed with the ELISA method before and after 3-month-long supplementation of 2000 IU of vitamin D orally. The results showed that the therapy did not induce any statistically significant changes in serum levels of MCP-1, IL-6, CX3CL1, and PACAP. The supplementation was related to a significant increase in measurements of NO and AOPP levels, although the correlation analysis between vitamin D concentration after its supplementation and the concentration of the molecular parameters did not show significant relation. In conclusion, our study seems to contradict certain aspects of findings available in the literature regarding the vitamin D's impact.

The evolution of human skin pigmentation involved the interactions of genetic, environmental, and cultural variables

The primary biological role of human skin pigmentation is as a mediator of penetration of ultraviolet radiation (UVR) into the deep layers of skin and the cutaneous circulation. Since the origin of Homo sapiens, dark, protective constitutive pigmentation and strong tanning abilities have been favored under conditions of high UVR and represent the baseline condition for modern humans. The evolution of partly depigmented skin and variable tanning abilities has occurred multiple times in prehistory, as populations have dispersed into environments with lower and more seasonal UVR regimes, with unique complements of genes and cultural practices. The evolution of extremes of dark pigmentation and depigmentation has been rare and occurred only under conditions of extremely high or low environmental UVR, promoted by positive selection on variant pigmentation genes followed by limited gene flow. Over time, the evolution of human skin pigmentation has been influenced by the nature and course of human dispersals and modifications of cultural practices, which have modified the nature and actions of skin pigmentation genes. Throughout most of prehistory and history, the evolution of human skin pigmentation has been a contingent and non-deterministic process.

Second-trimester maternal serum vitamin D and pregnancy outcome: The Western Australian Raine cohort study

AIMS

To assess the effect of maternal serum 25(OH)-vitamin D levels during the second trimester of pregnancy on the risk for gestational diabetes (GDM), pregnancy and infantile outcomes.

METHODS

This study is based on the Western Australian Pregnancy Cohort (Raine) study. Maternal serum 25(OH)-vitamin D concentrations of 890 pregnant women were evaluated at 18 weeks pregnancy and grouped into serum Vitamin D quartiles (>30, 30-49, 50-74 and >75 nmol/L).

RESULTS

Participants with de-seasonalized 25 (OH)-vitamin D levels <30 nmol/L were more likely to develop GDM, but not after controlling for ethnicity. Women with high body mass index (BMI) >30 were at a greater risk of developing GDM. Additionally, women with GDM were at a greater risk of primary caesarean delivery. Maternal serum levels of 25(OH)-vitamin D were positively associated with birth weight, body length and head circumference of the neonate.

CONCLUSION

Low maternal serum levels of 25(OH)-vitamin D are associated with GDM gestational diabetes, and race/ethnicity may modify this relationship. High pre-gestational BMI may predict GDM risk. GDM in pregnancy may increase the risk for delivery by caesarean section. Maternal 25(OH)-vitamin D is associated with anthropometric measures of the neonate.

Vitamin D and Its Role in the Lipid Metabolism and the Development of Atherosclerosis

Vitamin D, a crucial hormone in the homeostasis and metabolism of calcium bone, has lately been found to produce effects on other physiological and pathological processes genomically and non-genomically, including the cardiovascular system. While lower baseline vitamin D levels have been correlated with atherogenic blood lipid profiles, 25(OH)D supplementation influences the levels of serum lipids in that it lowers the levels of total cholesterol, triglycerides, and LDL-cholesterol and increases the levels of HDL-cholesterol, all of which are known risk factors for cardiovascular disease. Vitamin D is also involved in the development of atherosclerosis at the site of the blood vessels. Deficiency of this vitamin has been found to increase adhesion molecules or endothelial activation and, at the same time, supplementation is linked to the lowering presence of adhesion surrogates. Vitamin D can also influence the vascular tone by increasing endothelial nitric oxide production, as seen in supplementation studies. Deficiency can lead, at the same time, to oxidative stress and an increase in inflammation as well as the expression of particular immune cells that play a pivotal role in the development of atherosclerosis in the intima of the blood vessels, i.e., monocytes and macrophages. Vitamin D is also involved in atherogenesis through inhibition of vascular smooth muscle cell proliferation. Furthermore, vitamin D deficiency is consistently associated with cardiovascular events, such as myocardial infarction, STEMI, NSTEMI, unstable angina, ischemic stroke, cardiovascular death, and increased mortality after acute stroke. Conversely, vitamin D supplementation does not seem to produce beneficial effects in cohorts with intermediate baseline vitamin D levels.

Examining "race" in physiology

Racial disparities in cardiovascular and cerebrovascular health outcomes are well described, and recent research has shed light on the mechanistic underpinnings of those disparities. However, "race" is a social construct that is poorly defined and continually evolving and is historically based on faulty premises. The continued categorization by race in physiological research suggests that there are inherent differences between races, rather than addressing the specific underlying factors that result in health disparities between groups. The purpose of this Perspectives article is to provide a brief history of the genesis of categorization by race, why such categorization should be reconsidered in physiology research, and offer recommendations to more directly investigate the underlying factors that result in group disparities in cardiovascular and cerebrovascular health.