Validating lactate dehydrogenase (LDH) as a component of the PLASMIC predictive tool (PLASMIC-LDH).

Background: The PLASMIC score is a convenient tool for predicting ADAMTS13 activity of <10%. Lactate dehydrogenase (LDH) is widely used as a marker of haemolysis in thrombotic thrombocytopenic purpura (TTP) monitoring, and could be used as a replacement marker for lysis. We aimed to validate the PLASMIC score in a multi-centre Asia Pacific region, and to explore whether LDH could be used as a replacement marker for lysis. Methods: Records of patients with thrombotic microangiopathy (TMA) were reviewed. Patients' ADAMTS13 activity levels were obtained, along with clinical/laboratory findings relevant to the PLASMIC score. Both PLASMIC scores and PLASMIC-LDH scores, in which LDH replaced traditional lysis markers, were calculated. We generated a receiver operator characteristics (ROC) curve and compared the area under the curve values (AUC) to determine the predictive ability of each score. Results: 46 patients fulfilled the inclusion criteria, of which 34 had ADAMTS13 activity levels of <10%. When the patients were divided into intermediate-to-high risk (scores 5‒7) and low risk (scores 0‒4), the PLASMIC score showed a sensitivity of 97.1% and specificity of 58.3%, with a positive predictive value (PPV) of 86.8% and negative predictive value (NPV) of 87.5%. The PLASMIC-LDH score had a sensitivity of 97.1% and specificity of 33.3%, with a PPV of 80.5% and NPV of 80.0%. Conclusion: Our study validated the utility of the PLASMIC score, and demonstrated PLASMIC-LDH as a reasonable alternative in the absence of traditional lysis markers, to help identify high-risk patients for treatment via plasma exchange.

Estradiol-Responsive miR-365a-3p Interacts with Tissue Factor 3'UTR to Modulate Tissue Factor-Initiated Thrombin Generation.

BACKGROUND: High estradiol (E2) levels are linked to an increased risk of venous thromboembolism; however, the underlying molecular mechanism(s) remain poorly understood. We previously identified an E2-responsive microRNA (miR), miR-494-3p, that downregulates protein S expression, and posited additional coagulation factors, such as tissue factor, may be regulated in a similar manner via miRs. OBJECTIVES: To evaluate the coagulation capacity of cohorts with high physiological E2, and to further characterize novel E2-responsive miR and miR regulation on tissue factor in E2-related hypercoagulability. METHODS: Ceveron Alpha thrombin generation assay (TGA) was used to assess plasma coagulation profile of three cohorts. The effect of physiological levels of E2, 10 nM, on miR expression in HuH-7 cells was compared using NanoString nCounter and validated with independent assays. The effect of tissue factor-interacting miR was confirmed by dual-luciferase reporter assays, immunoblotting, flow cytometry, biochemistry assays, and TGA. RESULTS: Plasma samples from pregnant women and women on the contraceptive pill were confirmed to be hypercoagulable (compared with sex-matched controls). At equivalent and high physiological levels of E2, miR-365a-3p displayed concordant E2 downregulation in two independent miR quantification platforms, and tissue factor protein was upregulated by E2 treatment. Direct interaction between miR-365a-3p and F3-3'UTR was confirmed and overexpression of miR-365a-3p led to a decrease of (1) tissue factor mRNA transcripts, (2) protein levels, (3) activity, and (4) tissue factor-initiated thrombin generation. CONCLUSION: miR-365a-3p is a novel tissue factor regulator. High E2 concentrations induce a hypercoagulable state via a miR network specific for coagulation factors.

Molecular diversity, trafficking and subcellular localization of GABAB receptors.

GABAB receptors are the G-protein coupled receptors for the main inhibitory neurotransmitter in the brain, gamma-aminobutyric acid (GABA). While native studies predicted pharmacologically distinct GABAB receptor subtypes, molecular studies failed to identify the expected receptor varieties. Mouse genetic experiments therefore addressed whether the cloned receptors can account for the classical electrophysiological, biochemical and behavioral GABAB responses or whether additional receptors exist. Among G-protein coupled receptors, GABAB receptors are unique in that they require 2 distinct subunits for functioning. This atypical receptor structure triggered a large body of work that investigated the regulation of receptor assembly and trafficking. With the availability of molecular tools, substantial progress was also made in the analysis of the receptor protein distribution in neuronal compartments. Here, we review recent studies that shed light on the molecular diversity, the subcellular distribution and the cell surface dynamics of GABAB receptors.

The effect of age on serum creatinine levels in an aging population: relevance to vascular surgery.

BACKGROUND AND AIM: Serum creatinine is commonly used to assess and monitor renal function in the management of abdominal aortic aneurysm with endoluminal grafting, and for intervention of renal artery occlusive disease. The majority of patients selected for these procedures are elderly and serum creatinine is used post-operatively to monitor renal function. There is a need to adjust the serum creatinine concentration for age to determine the changes that might be due to the procedure: especially with endoluminal grafting using transrenal manipulation and fixation, and procedures involving interventions directly on the renal arteries. A single reference interval for serum creatinine is usually given for each sex but does not take into account variation due to age. The objective of this study was to establish age related reference intervals for serum creatinine, especially for those over 60 years of age to assist in the clinical interpretation of creatinine levels in the years following endoluminal grafting for aneurysms of the abdominal aorta. METHODS: A pathology services database was established for serum creatinine measurements from 98,688 patients (44,784 males and 53,904 females). Data was stratified into five year age groups and reference intervals assigned for each age group after a reference population was determined. The heterogeneous population was refined firstly by removing patients with extreme (> or =200 micromol/l) concentrations of serum creatinine, outliers and repeated values. Secondly, a putative "healthy" population was determined by removing values outside three standard deviations of the mean. Two statistical methods, the Bhattacharya and Hoffmann methods, were then applied to obtain a putative reference population. Serum creatinine data was obtained from the Busselton Population Research Foundation for comparison. FINDINGS: Serum creatinine concentration increased steadily with age; in females from the age of 40 years and 60 years for males. Reference intervals for males and females aged from 20 to 94 years were established. Advancing age affects serum creatinine levels, especially in the "vascular" age group of 60 to 80 years. The changes in serum creatinine concentration that occur with age is relevant in interpretation of the results of renal monitoring after intervention.