Homocysteine, hyperhomocysteinemia and vascular contributions to cognitive impairment and dementia (VCID).

Homocysteine is produced physiologically in all cells, and is present in plasma of healthy individuals (plasma [HCy]: 3-10μM). While rare genetic mutations (CBS, MTHFR) cause severe hyperhomocysteinemia ([HCy]: 100-200μM), mild-moderate hyperhomocysteinemia ([HCy]: 10-100μM) is common in older people, and is an independent risk factor for stroke and cognitive impairment. As B-vitamin supplementation (B6, B12 and folate) has well-validated homocysteine-lowering efficacy, this may be a readily-modifiable risk factor in vascular contributions to cognitive impairment and dementia (VCID). Here we review the biochemical and cellular actions of HCy related to VCID. Neuronal actions of HCy were at concentrations above the clinically-relevant range. Effects of HCy <100μM were primarily vascular, including myocyte proliferation, vessel wall fibrosis, impaired nitric oxide signalling, superoxide generation and pro-coagulant actions. HCy-lowering clinical trials relevant to VCID are discussed. Extensive clinical and preclinical data support HCy as a mediator for VCID. In our view further trials of combined B-vitamin supplementation are called for, incorporating lessons from previous trials and from recent experimental work. To maximise likelihood of treatment effect, a future trial should: supply a high-dose, combination supplement (B6, B12 and folate); target the at-risk age range; and target cohorts with low baseline B-vitamin status. This article is part of a Special Issue entitled: Vascular Contributions to Cognitive Impairment and Dementia edited by M. Paul Murphy, Roderick A. Corriveau and Donna M. Wilcock

PDGF-BB homodimer serum level – a good indicator of the severity of alcoholic liver cirrhosis

Introduction. Liver cirrhosis is a chronic disease in which progressive fibrosis is noted. This process leads to changed architectonics of the liver parenchyma and the appearance of regenerative nodules, all of which are caused by pathological activation of the hepatic stellate cells. This process is enhanced on a molecular level by many cytokines, with platelet-derived growth factors (PDGFs) playing the key role. Objective. The aim of the study was to assess serum concentrations of PDGFs active biodymers (PDGF-AA, PDGF-BB and PDGF-AB) in patients with alcoholic liver cirrhosis, and to correlate them with the stage of disease. Materials and method. 64 patients with alcoholic cirrhosis and a control group of 16 healthy individuals were analysed. Liver cirrhosis was determined based on clinical image, history of the patients’ alcohol consumption, laboratory findings and abdominal ultrasonography. The serum PDGF-AA, PDGF-BB and PDGF-AB concentrations were determined using ELISA kits. Results. Serum concentration of PDGF-AA and PDGF-BB homodimers increases in patients with alcoholic liver cirrhosis (p=0.034 and p0.05). When the stage of the disease increases, the concentrations of PDGF-AA and PGFD-BB in blood also oncrease. Furthermore, the serum level of both PDGF-AA and PDGF-BB correlates significantly with the severity of alcoholic liver cirrhosis (measured by Pugh-Child’s scale), the correlation being stronger in the case of PDGF-BB levels than PDGF-AA (R=0.28; p=0.027 and R=0.26; p=0.038, respectively). Conclusions. The plasma levels of PDGF-AA and -BB may be indicators of alcohol-induced liver fibrosis process, and might be considered as future possible treatment targets, with PDGF-BB levels being an even better indicator than PDGF-AA levels