Cystatin C: current position and future prospects.

Abstract Cystatin C is a low-molecular-weight protein which has been proposed as a marker of renal function that could replace creatinine. Indeed, the concentration of cystatin C is mainly determined by glomerular filtration and is particularly of interest in clinical settings where the relationship between creatinine production and muscle mass impairs the clinical performance of creatinine. Since the last decade, numerous studies have evaluated its potential use in measuring renal function in various populations. More recently, other potential developments for its clinical use have emerged. This review summarises current knowledge about the physiology of cystatin C and about its use as a renal marker, either alone or in equations developed to estimate the glomerular filtration rate. This paper also reviews recent data about the other applications of cystatin C, particularly in cardiology, oncology and clinical pharmacology. Clin Chem Lab Med 2008;46:1664-86

Negative effects of epilepsy and antiepileptic drugs on the trainability of dogs with naturally occurring idiopathic epilepsy

Epilepsy and anti-epileptic drug (AED) treatment have been found to induce or exacerbate underlying cognitive impairments in people, affecting learning ability, attention and memory. Idiopathic epilepsy (IE) is the most common chronic neurological condition in dogs. Whether IE impairs cognition, which may be reflected in affected dogs’ trainability, has not been explored. The aim of this study was to investigate whether IE and/or AED treatment compromise the trainability of dogs with IE compared to controls. An online cross-sectional study was conducted, resulting in a sample of 4051 dogs, of which 286 had been diagnosed with IE. Owners reported their dog’s trainability using a previously validated research questionnaire, along with their dogs’ training history (type of activities and training methods used) and clinical history. Four factors were significantly associated with trainability in a generalised linear mixed model: (i) epilepsy diagnosis: dogs with IE had significantly lower trainability than controls; (ii) age: dogs aged >12 years had significantly lower trainability than all other age groups; (iii) adult training history score: dogs with greater exposure to training activities were more trainable; and (iv) training method: dogs whose owners used a mix of both reward and punishment-based methods had lower trainability than those using solely reward-based methods. Within the sub-population of dogs with IE, those treated with (i) polytherapy (2–3 AEDs), (ii) zonisamide and/or (iii) potassium bromide exhibited lower trainability. This study provides initial evidence of cognitive impairment associated with IE and treatments for it, as measured by a metric of trainability. Further study is required to characterise these deficits. However, if these effects are confirmed, the merits of using the dog as a model of spontaneously occurring epilepsy will be strengthened, further consideration of the effects of AEDs will be required, and strategies to enhance cognition in affected dogs should be explored

CUX1-related neurodevelopmental disorder: deep insights into phenotype-genotype spectrum and underlying pathology

Heterozygous, pathogenic CUX1 variants are associated with global developmental delay or intellectual disability. This study delineates the clinical presentation in an extended cohort and investigates the molecular mechanism underlying the disorder in a Cux1+/− mouse model. Through international collaboration, we assembled the phenotypic and molecular information for 34 individuals (23 unpublished individuals). We analyze brain CUX1 expression and susceptibility to epilepsy in Cux1+/− mice. We describe 34 individuals, from which 30 were unrelated, with 26 different null and four missense variants. The leading symptoms were mild to moderate delayed speech and motor development and borderline to moderate intellectual disability. Additional symptoms were muscular hypotonia, seizures, joint laxity, and abnormalities of the forehead. In Cux1+/− mice, we found delayed growth, histologically normal brains, and increased susceptibility to seizures. In Cux1+/− brains, the expression of Cux1 transcripts was half of WT animals. Expression of CUX1 proteins was reduced, although in early postnatal animals significantly more than in adults. In summary, disease-causing CUX1 variants result in a non-syndromic phenotype of developmental delay and intellectual disability. In some individuals, this phenotype ameliorates with age, resulting in a clinical catch-up and normal IQ in adulthood. The post-transcriptional balance of CUX1 expression in the heterozygous brain at late developmental stages appears important for this favorable clinical course.CAG was supported by the Eunice Kennedy Shriver National Institute Of Child Health & Human Development of the National Institutes of Health under Award Number P50 HD103525. This work was funded by PID2020-112831GB-I00 AEI /10.13039/501100011033 (MN). SS was supported by a grant from the NIH/NINDS (K23NS119666). SWS is supported by the Hospital for Sick Children Foundation, Autism Speaks, and the University of Toronto McLaughlin Center. EM-G was supported by a grant from MICIU FPU18/06240. EVS. was supported by a grant from the NIH (EY025718). CRF was supported by the fund to support clinical research careers in the Region of Southern Denmark (Region Syddanmarks pulje for kliniske forskerkarriereforløb).Peer reviewe

Sandwich enzyme immunoassay of cystatin C in serum with commercially available antibodies

Abstract We developed a sandwich enzyme immunoassay for determining cystatin C in serum by using commercially available antibodies. We optimized each assay step (e.g., concentrations of coating rabbit anti-human cystatin C antibodies and horseradish peroxidase-conjugated antibodies) and studied the binding kinetics of antigen and antibodies. The within-assay CV was &amp;lt; 5%, the between-assay CV was 8.8%, the detection limit was 0.9 microgram/L, and the assay can be performed within 2 h. Cystatin C concentrations in sera from men were significantly higher than in women (mean and SD: 2.14 +/- 0.31 vs 1.78 +/- 0.26 mg/L). We studied the cystatin C concentrations in sera of 31 outpatients with suspected kidney damages to characterize the behavior of this low-M(r) protein as a possible indicator for estimating the glomerular filtration rate. The correlation with the values obtained by a standard isotopic method involving 99mTc-diethylenetriaminopentaacetic acid was rs = -0.89. The diagnostic sensitivity of cystatin C was 88.2% of that of the standard isotope clearance method and better than those of the conventional serum indicators of reduced kidney function, beta 2-microglobulin (64.7%) and creatinine (52.9%).</jats:p

Sialidase from different sources compared for electrophoretically separating serum alkaline phosphatase fractions from liver and bone.

Abstract We compared sialidase (neuraminidase; EC 3.2.1.18) from Vibrio cholerae, Clostridium perfringens, and Arthrobacter ureafaciens, seeking to improve the electrophoretic separation of the liver and bone isoenzymes of alkaline phosphatase (EC 3.1.3.1) on cellulose acetate membranes. Resolution is decisively determined by the type and activity of sialidase used in the preincubation of serum sample. Sialidase from Arthrobacter ureafaciens is not suited for this method. For optimal separation of the two isoenzymes we recommend the use of sialidase from Vibrio cholerae, determination of its activity with a standard procedure such as described here (mucin or sialyl lactose as substrates), and a final concentration of sialidase activity of 2.0 or 2.9 U/L (measured with mucin or sialyl lactose) in the incubation mixture.</jats:p

Isoelectric Point Separations of Peptides and Proteins

The separation of ampholytic components according to isoelectric point has played an important role in isolating, reducing complexity and improving peptide and protein detection. This brief review outlines the basics of isoelectric focusing, including a summary of the historical achievements and considerations in experimental design. Derivative methodologies of isoelectric focusing are also discussed including common detection methods used. Applications in a variety of fields using isoelectric point based separations are provided as well as an outlook on the field for future studies