Assessment of radiofrequency current-induced myocardial damage based on analysis of cardiac troponin T serum concentration.

The present study investigated the effect of radiofrequency (RF) current energy energy on the release pattern of myocardial marker proteins in 44 patients undergoing RF catheter ablation of supraventricular and ventricular tachycardia serial measurements of the activity of enzyme creatine kinase (enzymatic method), CK-MB isoneration TnT Enzymum ELISA, Boehringer Mannheim). The results showed that nearly all (91 percent) of the patients studied demonstrated a significant elevation in cTnT concentration following transcatheter applications of RF energy, whereas only 12 (27 percent) and 13 (29 percent) patients exhibited a postprocedural increase in CK and CK-MB activity, respectively. In contrast to the variable time for peak activity of CK and CK-MB, 40 of the 44 patients displayed an early peak cTnT concentration at eight hours after the procedure with a subsequent decline thereafter. Levels of cTnT and, to a lesser extent, CK but not CK-MB activity corressory pathways or atrioventricular nodal reentrant tachycardia. In conclusion, cardiac troponin T is a more sensitive indicator of RF energy-induced myocardial injury and has a more uniform pattern of myocardial release than the conventional CK and CK-MB. Determinations of cTnT serum concentration may thus provide a reliable method for assessing the extent of myocardial damage and for monitoring complications developed after radiofrequency or other froms of treascatheter ablation procedures.

Cyclosporine monitoring in patients with renal, cardiac and bone marrow transplants: A comparison between clone enzyme donor immunoassay and fluorescence polarization immunoassay methods.

In the present study a new method for selectively determining parent cyclosporine in whole blood, a clone enzyme donor immunoassay (CEDIA; Boehringer Mannheim), was compared with a fluorescence polarization immunoassay (FPIA; TDxAbbott). A total of 429 samples were collected, comprising 371 renal, 34 cardiac, 14 bone marrow and 10 corneal transplant recipients. Regression equations in 429 samples is CEDIA cyclosporine (ng/mL) = 0.999 x FPIA (ng/mL) + 1.684, (r=0.997). The linearity analysis was done from 0 – 1,000 ng/mL, which gave a good analytical range of between 15-600 ng/mL. The new CEDIA method also has within-rin CV = 1.77 – 3.69 percent which is better than the FPIA method (2.20 – 6.10 percent). The advantages of the new CEDIA method are the lower cost of the reagents and the fact that there is no need to purchase a new automated clinical chemistry analyser since it can be applied to routine chemistry instruments immediately after the reagents become available to the laboratory.

Glucose dehydrogenase biosensor for glucose monitoring: An accurate oxygen-insensitive electrochemical biosensor.

In severely hypotensive patients, fingerstick glucose determinations often do not accurately represent venous glucose levels. Those fingerstick glucose values that fall outside the acceptable range in hypotensive patient group are all lowere than the standard glucose values because the strip used is the oxygen-sensitive glucose oxidase method. This condition will be incorrectly diagnosed as a hypoglycaemic condition instead of normal. The objective of this study was to evaluate the O2-insensitivity of a new electrochemical biosensor test strip that can be used for different types of blood samples. This biosensor uses an O2-independent glucose dehydrogenase enzyme instead of an O2-dependent glucose oxidase enzyme in the reaction. We compared glucose measurements between venous blood by biosensor with the standard method which gave a coefficient of correlation (r)=0.998 (n=216). In cases of arterial blood with a wide range of pO2 varying from 21.7 mmHg to 388.7 mmHg, we compared the glucose levels measured by biosensor with standard method which gave r=0.997 (n=148). The precision analysis was tested in three glucose levels and gave a coefficient of variation (CV) less than 3 percent. The results showed that the new electrochemical biosensor was oxygen-insensitive and provided rapid, precise and accurate glucose measurements.

Analytical performance of direct LDL-cholesterol assay compared with friedewald LDL-cholesterol and apolipoprotein B assay.

Clinical laboratory currently estimate low-density lipoprotein cholesterol using the Friedewald formula, which requires fasting specimens and is subject to error with increasing triglyceride levels. The direct LDL Immunoseperation Reagent for LDL-cholesterol assay also have some disadvantages: 1. pipetting sample, 2. mixing and 3. centrifugation before subsequent measurement of cholesterol by conventional assay. We describe a rapid non-percipitating LDL-cholester assay using tentaclepolynion (PAMPS) reagent which base on precision with within-run and run-to-run coefficients of variation less than 3%. Results are in good agreement with the apolipoprotein assay (direct LDL-C = 1.745 apolipoprotein B-49.764 mg/dL, r=0.805) and also show very good linear regression with Friedewald LDL-C which triglyceride level below 400 mg/dL (Friedewald LDL-C=0.978 direct LDL-C-1.616 mg/dL, r=0.968). This method overcomes drawbacks the Friedewald formula and appears to be useful tool in managing hyperlipidemic patients by using an accurate quantification of LDl-C in the routine laboratory.

Lipoprotein and apolipoprotein profile in children with primary nephrotic syndrome: Metabolic alterations and consequences.

Serum levels of lipoprotein and apolipoprotein from 50 children, aged between 2 and 16 years, were measured by the enzymatic method and by immunoturbidimetric assay respectively, to determine abnormalities of lipid metabolism during the course of primary nephritic syndrome. There was a highly significant correlation between serum levels of both total cholesterol and low density lipoprotein cholesterol (LDL-C) and those of apolipoprotein B (apo B) (n=114, r=0.946, p<0.001 and n=99, r=0.943, p<0.001, respectively) and, to a lesser extent, between serum high density lipoprotein cholesterol (HDL-C) and apolipoprotein A-I (apo A-I) levels (n=123, r=0.679, p<0.001). HDL-C levels of apo A-I did not exhibit an association with those of albumin. The ratio of HDL-C to apo A-I, on the other hand, was low (<1.0) at very low levels of serum albumin (<2.0 g/dI) but showed a gradual rise with increasing albumin levels. These results may indicate a compositional change in HDL particles in the clinical course of nephritic syndrome, with a relatively high level of apolipoprotein-rich HDL particle (HDL)3 at very low albumin levels and predominantly HDL2 particles, which contain relatively more cholesterol, at increasing levels of albumin. Serum levels of LDL-C and apo B correlated significantly and inversely with serum albumin levels (n=101, r=-0.836, p<0.001 and n=114, r=-0.825, p<0.001, respectively). Compared with levels from healthy control children (2.52+0.67 mmol/L (97+26 mg/dI) and 0.86+0.21 g/L) matched for age and serum albumin levels, however, a relatively high concentration of both parameters of 3.59+1.02 mmol/L (139+40 mg/dI) and 1.47+0.32 g/L, respectively, was still observed at high serum albumin levels (> 4 g/dI). The finding of a persistance of abnormalities in lipid profile, despite a response to treatment of nephritic syndrome, may have some prognostic significance and should been given therapeutic consideration in the long-term management of children with primary nephrotic syndrome.

Direct measurement of high-density lipoprotein cholesterol compared with the precipitation-based methods.

We compared the performance of the direct measurement for quantifying high-density lipoprotein cholesterol (HDL-C) with the precipitation-based method for HDL-C, using samples with a wide range of HDL-C concentrations (7-144 mg/dL). The coefficient of correlation for the two methods was 0.98 (n=500). Both methods were precise with a run-to-rum CV of < 4.4 per cent. By using direct measurement for HDL-C we can reduce errors which occurred in the precipitation-based method, especially from centrifugation and recovery of the supernatant. The direct measurement method strongly appears to successfully discriminate between the serum HDL fractions and completely measures the HDL-C.

Determination of the apolipoprotein E genotype using PCR-RFLP in kidney diseases.

Using polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP), genotypes of the apolipoprotein E (Apo E) were determined in 50 control subjects and 60 Thai kidney diseases patients including nephritic syndrome and chronic renal failure (CRF) (30 each). Exon 4 of the Apo E genomic DNA was amplified between nucleotide numbers 2849 and 3071 (270 base pairs) then digested with HhaI. It is observed that E3/3 was the most common genotype found in the control subjects (80%). In nephritic syndrome patients, E4/3 was found to be the most frequent (53.3%). On the contrary, E3/3 was found to be the most prominent in CRF patients (80%). There was a significant different of the Apo E genotype in hephrotic syndrome from the normal control subjects (p < 0.05 by X2 analysis). One the other hand, there was no significant difference of the Apo E genotype in CRF patients from the control subjects (p>0.5). Cholesterol and triglyceride levels of the E4/3 nephrotic syndrome patients were significantly different from the normal controls of the same genotype (p<0.05). Similarly, in CRF patients, triglyceride level of the E3/3 genotype was also significantly different from the normal controls of the same genotype (p<0.05). These results suggested that polymorphism of the Apo E genotypes may be associated with the lipid abnormalities in renal diseases.