Richard Spooner

Apolipoprotein E phenotyping : a word of caution

Using two different techniques, phenotyping and genotyping, we have studied allelic variation at amino acids 112 and 158 of the apolipoprotein E gene locus in 52 patients with insulin-dependent diabetes and in 58 non-diabetic controls. Phenotypes were determined by isoelectric focusing and immunoblotting of delipidated, neuraminidase-treated plasma. Genotypes were determined by using the polymerase chain reaction to amplify a 227 base pair fragment of the apolipoprotein E gene spanning both allelic sites. This was then digested with the restriction endonuclease CfoI and the alleles identified by Polyacrylamide gel electrophoresis. Discrepancies between phenotype and genotype were observed in 16 (15%) of the individuals studied, 7 (13%) in the diabetics and 9 (17%) in the controls. From these results it is concluded that isoelectric focusing can lead to the erroneous assignment of apolipoprotein E phenotype even after pretreatment with neuraminidase. It is suggested that genotyping by DNA analysis is the method of choice in determining apolipoprotein E status.

Polymorphisms in VKORC1 have more impact than CYP2C9 polymorphisms on early warfarin International Normalized Ratio control and bleeding rates.

Poor warfarin control with resultant high International Normalized Ratios (INRs) and bleeding events is most common during the first months of treatment. The effects of genetic polymorphisms at the vitamin K epoxide reductase [VKORC1] and cytochrome P450 2C9 [CYP2C9] loci have been increasingly acknowledged as contributory factors of enhanced warfarin sensitivity. In our prospective, blinded study, 557 patients (49·1% male, mean age 65·4 years, range 18–91 years) commencing warfarin (target INR 2·5) were genotyped and monitored through the first 3 months of anticoagulation. Homozygosity for the −1639 G>A single nucleotide functional promoter polymorphism of the VKORC1 gene (genotype AA; 14·5% of cases) was associated with a significantly shortened time to therapeutic INR ≥ 2 (P < 0·01), reduced stable warfarin dose (P < 0·01), and an increased number of INRs > 5 (P < 0·001) and occurrence of bleeding events (P < 0·01) during the first month, as compared to the GG genotype. CYP2C9 genetic variations *2 and *3 were not associated with significant effect on these factors. Neither VKORC1 nor CYP2C9 polymorphisms influenced these parameters beyond the first month of treatment. These findings imply possible benefits of assessing VKORC1 polymorphisms prior to anticoagulation, particularly as a low dose induction regime in VKORC1 AA individuals appears to reduce the incidence of high INRs.

Vitamin Status During Total Parenteral Nutrition

Plasma concentrations of vitamins A and E, serum and erythrocyte folic acid, serum B12 and erythrocyte enzyme activations (to assess vitamins B1, B2 and B6 status) were measured at the start and finish of 39 courses of total parenteral nutrition (TPN). The daily regimen was standard. Plasma vitamin A, E, and folate concentrations and vitamin B6 status improved significantly during TPN. Three patients developed low levels of vitamin A and two patients developed high transketolase activations (B1 depletion) during therapy. The adequacy of vitamin replacement and the monitoring of vitamin status during TPN is discussed.

Profile of microvolt T-wave alternans testing in 1003 patients hospitalized with heart failure.

Observational studies in selected populations have suggested that microvolt T‐wave alternans (MTWA) testing may identify patients with heart failure (HF) at risk of sudden cardiac death. The aims of this study were to investigate the utility of MTWA testing in an unselected population of patients with HF and to evaluate the clinical characteristics associated with the MTWA results.

Spectral microvolt T‐wave alternans testing has no prognostic value in patients recently hospitalized with decompensated heart failure

Microvolt T‐wave alternans (MTWA) testing identifies beat‐to‐beat fluctuations in T‐wave morphology, which have been linked to ventricular arrhythmias. However, clinical studies have produced conflicting results and data in heart failure (HF) have been limited. The aim of this study was to determine the prevalence and incremental prognostic value of spectral MTWA testing in an unselected cohort of patients recently hospitalized with HF.

Apolipoprotein E and epilepsy

The overall frequencies of the apolipoprotein f2, f3 and f4 alleles in the epilepsy patients were no different to those of the control group (Table 1). Subgroups consisting of patients with either an unknown aetiology for epilepsy (71% of patients), a family history of epilepsy (21% of patients), idiopathic generalized epilepsy, or cryptogenic partial seizures showed no significant difference in allele frequency when compared with controls. Likewise, the age of onset of epilepsy was no

Delayed Diagnosis of Addison's Disease

Addisons disease may be difficult to diagnose because of the nonspecificity of the most frequently occurring symptoms. Hyponatraemia, hyperkalaemia, and uraemia are commonly detected in sera from patients with Addisons disease. We report two patients in whom the diagnosis was delayed, despite typical biochemical abnormalities in their sera during initial presentation. A computer search of 4 weeks of biochemical data (9862 requests for electrolytes) indicated that these typical biochemical abnormalities occurred commonly in other patients, increasing the difficulty of the clinical biochemist in detecting Addisons disease. Awareness of this problem, in combination with adequate clinical information, should enable the clinical biochemist to assist in the earlier diagnosis of Addisons disease.

Acute B-type natriuretic peptide response and early postoperative right ventricular physiology following tetralogy of Fallot's repair

B-type natriuretic peptide (BNP) response early after a tetralogy of Fallots repair remains unclear. BNP was measured pre- and post-operatively (immediately, day 1) in 18 children undergoing corrective repair with concurrent echocardiography (pre-, post-op day 1) to assess right ventricular (RV) systolic dysfunction, restrictive physiology, wall motion and pulmonary regurgitation (PR). In the first 24 h postoperatively, BNP rose acutely in all patients (mean 34.9 vs 144.4 vs 716.9 pg/ml at pre-op, days 0 and 1; P < 0.001). Immediate postoperative BNP correlated with preoperative haematocrit (rho = 0.52, P = 0.03) and inversely with preoperative oxygen saturation (rho = -0.63, P = 0.007). All patients showed reduced RV systolic function and abnormal wall motion with at least moderate PR in six patients (33.3%) and restrictive physiology in four (24%). Subsequent BNP expression (post-op day 1) correlated with a low RV fractional area change (rho = -0.51, P = 0.04), high oxygen extraction ratio (rho = 0.56, P = 0.02) and high central venous pressure (rho = 0.79, P < 0.001). The LV function and wall motion remained preserved in all patients. The mechanism of BNP expression is likely to be multi-factorial in the presence of a complex postoperative RV physiology in tetralogy of Fallot. An acute BNP response in the early postoperative period reflects an important physiological role and may be used as an adjunct biomarker to assess the RV function.

Glycemic control and raised serum alanine aminotransferase activity in treated diabetes mellitus

The prevalence of raised serum liver-associated enzyme activity in stabilised, treated diabetic outpatients without concurrent hepatobiliary disease was investigated using a retrospective computer search of biochemical data. The frequency of raised alanine aminotransferase, aspartate aminotransferase, or gamma glutamyl transferase activity found among diabetic, general medical and respiratory outpatients was compared with that found in apparently healthy controls. It was established that a raised activity of any of the three enzymes occurred with a similar frequency in each outpatient group. However, only with alanine aminotransferase did the frequency of elevation (7.1%) in the patients with previously diagnosed hepatobiliary disease exceed that of healthy controls. A raised alanine aminotransferase activity in diabetic outpatients was associated with good glycemic control (hemoglobin A1 less than 8%, p less than 0.02) and treatment with oral hypoglycaemic agents (p less than 0.001).

A Simple Side-Room Test to Screen for Microalbuminuria in Diabetes Mellitus

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