Williams syndrome is caused by the deletion of 26 to 28 genes, including elastin, on human chromosome 7. Elastin insufficiency leads to the cardiovascular hallmarks of this condition, namely focal stenosis and hypertension. Extrapolation from the Eln+/− mouse suggests that affected people may also have stiff vasculature, a risk factor for stroke, myocardial infarction, and cardiac death. NCF1 , one of the variably deleted Williams genes, is a component of the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase complex and is involved in the generation of oxidative stress, making it an interesting candidate modifier for vascular stiffness. Using a case–control design, vascular stiffness was evaluated by pulse wave velocity in 77 Williams cases and matched controls. Cases had stiffer conducting vessels than controls ( P <0.001), with increased stiffness observed in even the youngest children with Williams syndrome. Pulse wave velocity increased with age at comparable rates in cases and controls, and although the degree of vascular stiffness varied, it was seen in both hypertensive and normotensive Williams participants. Use of antihypertensive medication and extension of the Williams deletion to include NCF1 were associated with protection from vascular stiffness. These findings demonstrate that vascular stiffness is a primary vascular phenotype in Williams syndrome and that treatment with antihypertensives or agents inhibiting oxidative stress may be important in managing patients with this condition, potentially even those who are not overtly hypertensive.
16 January 2024 in Journal of Clinical Investigation
Vascular aging affects multiple organ systems, including the brain, where it can lead to vascular dementia. However, a concrete understanding of how aging specifically affects the brain vasculature, along with molecular readouts, remains vastly incomplete. Here, we demonstrate that aging is associated with a marked decline in Notch3 signaling in both murine and human brain vessels. To clarify the consequences of Notch3 loss in the brain vasculature, we used single-cell transcriptomics and found that Notch3 inactivation alters regulation of calcium and contractile function and promotes a notable increase in extracellular matrix. These alterations adversely impact vascular reactivity, manifesting as dilation, tortuosity, microaneurysms, and decreased cerebral blood flow, as observed by MRI. Combined, these vascular impairments hinder glymphatic flow and result in buildup of glycosaminoglycans within the brain parenchyma. Remarkably, this phenomenon mirrors a key pathological feature found in brains of patients with CADASIL, a hereditary vascular dementia associated with NOTCH3 missense mutations. Additionally, single-cell RNA sequencing of the neuronal compartment in aging Notch3-null mice unveiled patterns reminiscent of those observed in neurodegenerative diseases. These findings offer direct evidence that age-related NOTCH3 deficiencies trigger a progressive decline in vascular function, subsequently affecting glymphatic flow and culminating in neurodegeneration.
1 July 2018 in American Journal of Physiology-Heart and Circulatory Physiology
Increased vascular stiffness correlates with a higher risk of cardiovascular complications in aging adults. Elastin (ELN) insufficiency, as observed in patients with Williams-Beuren syndrome or with familial supravalvular aortic stenosis, also increases vascular stiffness and leads to arterial narrowing. We used Eln+/−mice to test the hypothesis that pathologically increased vascular stiffness with concomitant arterial narrowing leads to decreased blood flow to end organs such as the brain. We also hypothesized that drugs that remodel arteries and increase lumen diameter would improve flow. To test these hypotheses, we compared carotid blood flow using ultrasound and cerebral blood flow using MRI-based arterial spin labeling in wild-type (WT) and Eln+/−mice. We then studied how minoxidil, an ATP-sensitive K+channel opener and vasodilator, affects vessel mechanics, blood flow, and gene expression. Both carotid and cerebral blood flows were lower in Eln+/−mice than in WT mice. Treatment of Eln+/−mice with minoxidil lowered blood pressure and reduced functional arterial stiffness to WT levels. Minoxidil also improved arterial diameter and restored carotid and cerebral blood flows in Eln+/−mice. The beneficial effects persisted for weeks after drug removal. RNA-Seq analysis revealed differential expression of 127 extracellular matrix-related genes among the treatment groups. These results indicate that ELN insufficiency impairs end-organ perfusion, which may contribute to the increased cardiovascular risk. Minoxidil, despite lowering blood pressure, improves end-organ perfusion. Changes in matrix gene expression and persistence of treatment effects after drug withdrawal suggest arterial remodeling. Such remodeling may benefit patients with genetic or age-dependent ELN insufficiency.NEW & NOTEWORTHY Our work with a model of chronic vascular stiffness, the elastin ( Eln)+/−mouse, shows reduced brain perfusion as measured by carotid ultrasound and MRI arterial spin labeling. Vessel caliber, functional stiffness, and blood flow improved with minoxidil. The ATP-sensitive K+channel opener increased Eln gene expression and altered 126 other matrix-associated genes.
To evaluate the efficacy of ChatGPT 4 (GPT-4) in delivering genetic information about BRCA1, HFE, and MLH1, building on previous findings with ChatGPT 3.5 (GPT-3.5). To focus on assessing the utility, limitations, and ethical implications of using ChatGPT in medical settings. A structured survey was developed to assess GPT-4’s clinical value. An expert panel of genetic counselors and clinical geneticists evaluated GPT-4’s responses to these questions. We also performed comparative analysis with GPT-3.5, utilizing descriptive statistics and using Prism 9 for data analysis. The findings indicate improved accuracy in GPT-4 over GPT-3.5 (P < .0001). However, notable errors in accuracy remained. The relevance of responses varied in GPT-4, but was generally favorable, with a mean in the “somewhat agree” range. There was no difference in performance by disease category. The 7-question subset of the Bot Usability Scale (BUS-15) showed no statistically significant difference between the groups but trended lower in the GPT-4 version. The study underscores GPT-4’s potential role in genetic education, showing notable progress yet facing challenges like outdated information and the necessity of ongoing refinement. Our results, while showing promise, emphasizes the importance of balancing technological innovation with ethical responsibility in healthcare information delivery.