Ischemic stroke and hypertension in a child — a case report of two patients

Ischemic stroke is a rare condition in children and is typically a complication of systemic diseases, such as congenital or acquired arterial diseases. The article discusses cases of two patients: a 2.5-year-old girl and a 3.5-year-old boy with ischemic stroke, severe hypertension and with multiple medium-caliber arterial stenosis involving the intracranial segments of the carotid arteries and renal arteries stenoses. Medical imaging showed a developed collateral circulation in the central nervous system typical of moyamoya disease. Molecular confirmation of the RNF213 gene variant was obtained in one patient. Complex drug treatment managed to achieve normotension. In further observation, the development of stenosis in medium-caliber arteries, including the pulmonary vascular bed, was observed. Presented cases show the evolution of vascular alterations in a patient with molecularly confirmed moyamoya disease and in a patient with a similar clinical phenotype without molecular confirmation

High-resolution cryo-EM structures of plant cytochrome b6fb_{6}f at work

Plants use solar energy to power cellular metabolism. The oxidation of plastoquinol and reduction of plastocyanin by cytochrome $b_{6}f$ (Cyt $b_{6}f$) is known as one of the key steps of photosynthesis, but the catalytic mechanism in the plastoquinone oxidation site ($Q_{p}$) remains elusive. Here, we describe two high-resolution cryo-EM structures of the spinach Cyt $b_{6}f$ homodimer with endogenous plastoquinones and in complex with plastocyanin. Three plastoquinones are visible and line up one after another head to tail near $Q_{p}$ in both monomers, indicating the existence of a channel in each monomer. Therefore, quinones appear to flow through Cyt $b_{6}f$ in one direction, transiently exposing the redox-active ring of quinone during catalysis. Our work proposes an unprecedented one-way traffic model that explains efficient quinol oxidation during photosynthesis and respiration. Structures of cytochrome $b_{6}f$ with and without plastocyanin imply a one-way traffic of quinones for efficient photosynthesis

Assessment of hypertension-mediated organ damage in children and adolescents with hypertension

Purpose: Arterial hypertension (HT) is a main, potentially reversible cardiovascular risk factor. Long lasting HT leads to hypertension mediated organ damage (HMOD) of heart, vascular bed, and kidneys. Assessment of HMOD is a standard diagnostic procedure in hypertensive adults and presence of HMOD is associated with increased cardiovascular risk. The assessment of main HMOD markers includes the assessment of left ventricular mass, carotid intima-media thickness, arterial stiffness expressed as pulse wave velocity, and assessment of microcirculation. In contrast to adults, proper interpretation of obtained results of HMOD must be adjusted to age and sex referential values. In the last two decades, numerous studies describing HMOD in children with hypertension have been published, including meta-analyses evaluating various methods of HMOD assessment. Here, we present current state of the art and discuss recommendations on HMOD evaluation in hypertensive children