Phenotyping and Genotyping of Coagulation Factor V Leiden

The currently used activated Protein C resistance test demonstrated to be of limited diagnostic value for the detection of the mutant Factor V Leiden. Moreover, this assay is not useful for patients under anticoagulant therapy. A modification of the APC resistance test, applying Factor V deficient plasma is described which demonstrates a specificity and sensitivity of 1.0. The superiority of the modified APC resistance test over the existing APC resistance test was verified by genotyping.

For that purpose, the Amplification Refractory Mutation System (ARMS) was applied to the detection of the G to A mutation at position 1691 in the gene encoding coagulation Factor V. The mutation at that position could be easily detected by using each of two allele-specific oligonucleotide primers concomitantly with one common primer in two separate polymerase chain reactions, thereby amplifying a fragment of 186 base-pairs of the Factor V gene.

Vitamin B12 deficiency after esophagectomy with gastric tube reconstruction for esophageal cancer

The aim of this study is to determine the prevalence and incidence of vitamin B12 deficiency after esophagectomy for cancer. It is unknown if patients after esophagectomy with gastric tube reconstruction are at an increased risk for vitamin B12 deficiency. A cross-sectional cohort (group A) and a prospective cohort (group B) of patients who underwent esophagectomy for cancer in two tertiary referral centers in the Netherlands were included. Serum levels of holo-transcobalamin (Holo-TC) and methyl malonic acid (MMA) were determined. Vitamin B12 deficiency was defined as Holo-TC < 21 pmol/L and/or MMA > 0.45 μmol/L. Vitamin B12 status was assessed in group A at a single time point between one and three years postoperatively and before and every three months after resection in group B. Ninety-nine patients were analyzed in group A. The median time between surgery and analysis of vitamin B12 deficiency was 19.3 months. In 11 of 99 (11%) patients, vitamin B12 deficiency was detected. In group B, 5 of 88 (5.6%) patients had vitamin B12 deficiency preoperatively, and another 9 (10.2%) patients developed vitamin B12 deficiency after the operation at a median time of 6 months postoperatively. The estimated one-year incidence of vitamin B12 deficiency was 18.2%. None of the patients with vitamin B12 deficiency had a megaloblastic anemia. Vitamin B12 deficiency can be anticipated in 18% of patients after esophagectomy with gastric tube reconstruction for cancer. During follow-up, Holo-TC and MMA levels should be measured to detect vitamin B12 deficiency and commence treatment timely.

Early pregnancy maternal and fetal angiogenic factors and fetal and childhood growth: the Generation R Study

STUDY QUESTION

What are the effects of maternal and fetal soluble fms-like tyrosine kinase 1 (sFlt-1) and placental growth factor (PlGF) concentrations on fetal and childhood growth patterns?

SUMMARY ANSWER

An angiogenic profile that is characterized by both low early pregnancy maternal sFlt-1 and PlGF concentrations and higher sFlt-1 concentrations, lower PlGF concentrations or a higher sFlt-1:PlGF ratio in umbilical cord blood is associated with a reduced fetal and childhood growth.

WHAT IS KNOWN ALREADY

An imbalance in maternal and fetal sFlt-1 and PlGF concentrations has been suggested to affect pregnancy outcomes. However, their effects on longitudinal fetal and childhood growth remain largely unknown.

STUDY DESIGN, SIZE, DURATION

This study was performed in 5980 mothers and 4108 of their children, participating in the Generation R Study; a population-based prospective cohort study from fetal life onwards in Rotterdam, the Netherlands (2001-2005).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Blood samples were obtained from mothers in early and mid-pregnancy and from the umbilical vein at delivery. Fetal and childhood growth characteristics (weight and length) were measured repeatedly by ultrasound and physical examinations until the age of 6 years. We assessed the associations of maternal and fetal angiogenic factors with fetal and childhood growth using repeated measurement regression models. Logistic regression models were used to determine associations between angiogenic factors and small for gestational age at birth (SGA).

MAIN RESULTS AND THE ROLE OF CHANCE

Compared with early pregnancy maternal sFlt-1 concentrations in the lowest quintile, early pregnancy maternal sFlt-1 concentrations in the highest quintile were associated with a higher fetal weight growth resulting in a higher birthweight (difference in birthweight 0.33 standard deviation score (SDS); 95% Confidence Interval (CI) 0.25-0.41), a lower risk of SGA (Odds Ratio (OR) 0.36; 95% CI 0.27-0.48) and a subsequent higher weight growth until the age of 6 years. Early pregnancy maternal PlGF concentrations in the lowest quintile were associated with a reduced weight growth pattern resulting in a smaller birthweight (difference in birthweight -0.34 SDS; 95% CI -0.44, -0.25), an increased risk of SGA (OR 3.48; 95% CI 2.39-5.08) and a lower weight growth throughout childhood. An early pregnancy maternal sFlt-1:PlGF ratio in the highest quintile was associated with a higher fetal weight growth pattern from 30 weeks onwards, resulting in a higher weight at birth (difference in birthweight 0.09 SDS; P-value <0.05), which remained present until the age of 2 years. Newborns with higher umbilical cord sFlt-1 concentrations, lower PlGF concentrations or a higher sFlt-1:PlGF ratio showed a lower fetal and childhood weight growth from 30 weeks gestation onwards until the age of 6 years (P-value <0.05). Similar patterns were observed in relation to fetal and childhood length growth.

LIMITATIONS, REASONS FOR CAUTION

The study is an observational study. Therefore, no causal relationships can be established.

WIDER IMPLICATIONS OF THE FINDINGS

Both a maternal and fetal angiogenic imbalance may affect fetal and childhood growth. Changes in angiogenic profiles may be involved in the pathways linking fetal growth restriction with the long-term risk of vascular disease in adulthood.

STUDY FUNDING/COMPETING INTERESTS

The first phase of the Generation R Study is made possible by financial support from The Erasmus Medical Centre, Rotterdam, the Erasmus University Rotterdam, and the Netherlands Organization for Health Research and Development (ZonMw 21000074). V.W.V.J. received additional grants from the Netherlands Organization for Health Research and Development (ZonMw VIDI). M.I.B.-B. is financially supported by the Bo Hjelt foundation (grant 2009). The authors have no competing interests.

Homocysteine and folate concentrations in early pregnancy and the risk of adverse pregnancy outcomes: the Generation R Study

OBJECTIVE

To investigate associations between early pregnancy homocysteine, folate and vitamin B12 concentrations and placental weight, birthweight and adverse pregnancy outcomes.

DESIGN

Population-based birth cohort study.

SETTING

Rotterdam, the Netherlands.

POPULATION

Cohort of 5805 pregnant women.

METHODS

To analyse homocysteine, folate and vitamin B12 concentrations, blood was drawn in early pregnancy. These concentrations were divided into quintiles. Information on birth outcomes was retrieved from medical records. Multivariate regression analyses were used.

MAIN OUTCOME MEASURES

Placental weight, birthweight, small for gestational age at birth (SGA) (<5th centile), prematurity and pre-eclampsia.

RESULTS

High homocysteine concentrations (highest quintile) were associated with lower placental weight (difference 30 g; P < 0.001) and birthweight (difference 110 g; P < 0.001), and increased risk of SGA [odds ratio (OR) 1.7; P = 0.006] compared with lowest quintile (reference). Low folate concentrations (lowest quintile) were associated with lower placental weight (difference 26 g; P = 0.001) and birthweight (difference 125 g; P < 0.001), and increased risks of SGA (OR 1.9; P = 0.002), prematurity (OR 2.2; P = 0.002) and pre-eclampsia (OR 2.1; P = 0.04) compared with highest quintile (reference). The risk of developing SGA and pre-eclampsia was substantially higher in women who had higher homocysteine and lower folate concentrations. No associations were found with vitamin B12.

CONCLUSIONS

Higher homocysteine and lower folate concentrations in early pregnancy are associated with lower placental weight and birthweight, and higher risk of adverse pregnancy outcomes. These findings suggest that high homocysteine and low folate concentrations in early pregnancy may adversely influence placentation and subsequently affect the success of pregnancy and birth outcomes.

A derangement of the maternal lipid profile is associated with an elevated risk of congenital heart disease in the offspring

BACKGROUND AND AIMS

Maternal hyperglycaemia and hyperhomocysteinaemia are risk factors for congenital heart disease (CHD). These metabolic derangements and deranged lipid levels are associated with adult cardiovascular disease. We examined whether maternal lipid levels are associated with the risk of CHD offspring.

METHODS AND RESULTS

From 2003 onwards, a case-control study was conducted. Participants were mothers of children with (n = 261) and without (n = 325) CHD. At around 16 months after the index-pregnancy, maternal lipid levels were determined. Maternal characteristics and lipid levels were compared by Student's t-test. In a multivariable logistic regression model, risk estimates were calculated for associations between CHD and lipid levels. Adjustments were made for maternal age, diabetes, ethnicity, body mass index (BMI), parity, periconception folic acid use and total homocysteine levels. Outcome measures are presented in (geometric) means (p5-p95) and odds ratios (ORs) with 95% confidence intervals (CIs). Case mothers showed higher cholesterol (4.9 vs. 4.7 mmol l(-1), P < 0.05), low-density lipoprotein (LDL)-cholesterol (3.2 vs. 3.0 mmol l(-1), P < 0.05), apolipoprotein B (84.0 vs. 80.0 mg dl(-1), P < 0.01) and homocysteine (10.8 vs. 10.2 μmol l(-1), P < 0.05) than controls. LDL-cholesterol above 3.3 mmol l(-1) (OR 1.6 (95%CI, 1.1-2.3)) and apolipoprotein B above 85.0 mg dl(-1) were associated with an almost twofold increased CHD risk (OR 1.8 (95%CI, 1.2-2.6)). This was supported by elevated CHD risks per unit standard deviation increase in cholesterol (OR 1.2 (95% CI 1.03-1.5)), LDL-cholesterol (OR 1.3 (95%CI, 1.1-1.6) and apolipoprotein B (OR 1.3 (95% CI 1.1-1.6)). Apolipoprotein B was most strongly associated with CHD risk.

CONCLUSION

A mildly deranged maternal lipid profile is associated with an increased risk of CHD offspring.

Prognosis of vascular surgery patients using a quantitative assessment of troponin T release: is the crystal ball still clear?

BACKGROUND

Cardiac troponin T (cTnT) assays with increased sensitivity might increase the number of positive tests. Using the area under the curve (AUC) with serial sampling of cTnT an exact quantification of the myocardial damage size can be made. We compared the prognosis of vascular surgery patients with integrated cTnT-AUC values to continuous and standard 12-lead electrocardiography (ECG) changes.

METHODS

513 Patients were monitored. cTnT sampling was performed on postoperative days 1, 3, 7, 30 and/or at discharge or whenever clinically indicated. If cTnT release occurred, daily measurements of cTnT were performed, until baseline was achieved. CTnT-AUC was quantified and divided in tertiles. All-cause mortality and cardiovascular events (cardiac death and myocardial infarction) were noted during follow-up.

RESULTS

81/513 (16%) Patients had cTnT release. After adjustment for gender, cardiac risk factors, and site and type of surgery, those in the highest cTnT-AUC tertile were associated with a significantly worse cardiovascular outcome and long-term mortality (HR 20.2; 95% CI 10.2-40.0 and HR 4.0; 95% CI 2.0-7.8 respectively). Receiver operator analysis showed that the best cut-off value for cTnT-AUC was <0.01 days*ng m for predicting long-term cardiovascular events and all-cause mortality.

CONCLUSION

In vascular surgery patients quantitative assessment of cTnT strongly predicts long-term outcome.

Associations between dietary patterns and semen quality in men undergoing IVF/ICSI treatment

BACKGROUND This study investigates whether dietary patterns, substantiated by biomarkers, are associated with semen quality. METHODS In 161 men of subfertile couples undergoing in vitro fertilization treatment in a tertiary referral clinic in Rotterdam, the Netherlands, we assessed nutrient intakes and performed principal component factor analysis to identify dietary patterns. Total homocysteine (tHcy), folate, vitamin B12 and B6 were measured in blood and seminal plasma. Semen quality was assessed by sperm volume, concentration, motility, morphology and DNA fragmentation index (DFI). Linear regression models analyzed associations between dietary patterns, biomarkers and sperm parameters, adjusted for age, body mass index (BMI), smoking, vitamins and varicocele. RESULTS The 'Health Conscious' dietary pattern shows high intakes of fruits, vegetables, fish and whole grains. The 'Traditional Dutch' dietary pattern is characterized by high intakes of meat, potatoes and whole grains and low intakes of beverages and sweets. The 'Health Conscious' diet was inversely correlated with tHcy in blood (beta = -0.07, P = 0.02) and seminal plasma (beta = -1.34, P = 0.02) and positively with vitamin B6 in blood (beta = 0.217, P = 0.01). An inverse association was demonstrated between the 'Health Conscious' diet and DFI (beta = -2.81, P = 0.05). The 'Traditional Dutch' diet was positively correlated with red blood cell folate (beta = 0.06, P = 0.04) and sperm concentration (beta = 13.25, P = 0.01). CONCLUSIONS The 'Health Conscious' and 'Traditional Dutch' dietary pattern seem to be associated with semen quality in men of subfertile couples.

Association of graded allele-specific changes in CYP2D6 function with imipramine dose requirement in a large group of depressed patients

The inactivation and clearance of the tricyclic antidepressant imipramine is dependent on CYP2D6 activity. First, CYP2C19 converts imipramine into the active metabolite desipramine, which is then inactivated by CYP2D6. This retrospective single center study aimed to prove whether CYP2C19 and ample CYP2D6 genotyping (taking into consideration four null alleles and three decreased-activity alleles) could be used to predict imipramine and desipramine plasma concentrations in depressed patients, and whether genotype-based drug dose recommendations might assist in the early management of imipramine pharmacotherapy. In 181 subjects with major depressive disorder, drug doses were recorded, imipramine and desipramine plasma concentrations were monitored and CYP2C19 (*2) and CYP2D6 genotype (*3, *4, *5, *6, *9, *10, *41 and gene duplication) were obtained, yielding graded allele-specific CYP2D6 patient groups. Desipramine and imipramine+desipramine plasma concentration per drug dose unit, imipramine dose at steady state, and imipramine dose requirement significantly depended on CYP2D6 genotype (Kruskal-Wallis test, P<0.0001). Mean (+/-s.d.) drug dose requirements were 131 (+/-109), 155 (+/-70), 217 (+/-95), 245 (+/-125), 326 (+/-213), and 509 (+/-292) mg imipramine/day in carriers of 0, 0.5, 1, 1.5, 2, and >2 active CYP2D6 genes, respectively. Our protocol for CYP2D6 genotyping will thus importantly aid in the prediction of imipramine metabolism, allowing for the use of an adjusted starting dose and faster achievement of predefined imipramine+desipramine plasma levels in all genetic patient subgroups. Therefore, therapeutic efficacy and efficiency may be improved, the number of adverse drug reactions decreased, and hospital stay reduced.

Validation of the assessment of folate and vitamin B12 intake in women of reproductive age: the method of triads

OBJECTIVE

To validate the folate and vitamin B12 intakes estimated by a food-frequency questionnaire (FFQ) designed to be used in a case-control study on the association between maternal dietary intake and the risk of having a child with a congenital heart defect.

DESIGN AND SUBJECTS

The FFQ was filled out by 53 women of reproductive age. Immediately thereafter, blood samples were taken to determine serum folate, red blood cell (RBC) folate and serum vitamin B12 concentrations. Subsequently, three dietary 24-h recalls (24HR) were completed during a period of three successive weeks and used as a reference method. The recalls comprised two weekdays and one weekend day. Using the method of triads, validity coefficients were calculated by comparing nutrient intakes derived from the FFQ and 24HR with the corresponding nutritional biomarkers in blood. The validity coefficient is the correlation between the dietary intake reported by the FFQ and the unknown 'true' dietary intake.

RESULTS

The comparison of B-vitamin intakes reported by the FFQ and the mean of the 24HR revealed deattenuated correlation coefficients of 0.98 for folate and 0.66 for vitamin B12. The correlation coefficients between the B-vitamin intakes estimated by the FFQ and concentrations of serum folate, RBC folate and serum vitamin B12 were 0.20, 0.28 and 0.21, respectively. The validity coefficients for serum folate, RBC folate and serum vitamin B12 were 0.94, 0.75 and 1.00, respectively. The estimated folate and vitamin B12 intakes were comparable with the results of the most recent Dutch food consumption survey.

CONCLUSIONS

The adapted FFQ is a reliable tool to estimate the dietary intake of energy, macronutrients, folate and vitamin B12 in women of reproductive age. Therefore, this FFQ is suitable for the investigation of nutrient-disease associations in future.

SPONSORSHIP

Funding was provided by the Netherlands Heart Foundation (Grant 2002.B027).

Maternal hyperhomocysteinaemia is a risk factor for congenital heart disease

OBJECTIVE

To investigate the inter-relation between mother and infant homocysteine, folate and vitamin B12 status and the risk of a child with congenital heart disease (CHD).

DESIGN

Case-control study.

SETTING

Erasmus MC, University Medical Centre, Rotterdam, the Netherlands.

POPULATION

Participants were 149 case-mothers and their children with CHD (n = 151) and 183 control-mothers with their children (n = 175).

METHODS

Approximately 17 months after the index-pregnancy maternal fasting, children's random venous blood samples were drawn to measure plasma total homocysteine, serum and red blood cell (RBC) folate, and serum vitamin B12 concentrations. Data were compared between cases and controls using the Mann-Whitney U test. The biochemical parameters were dichotomised according to the cutoff value of the 10th percentile of vitamin concentrations and the 90th percentile of homocysteine concentrations based on control data. Risk estimates for the association between CHD and the biochemical parameters were estimated in a logistic regression model.

MAIN OUTCOME MEASURES

Medians (minimum-maximum) and odds ratios (OR) (95% confidence intervals [CI]).

RESULTS

The OR (95% CI) of having a child with CHD was 2.9 (1.4-6.0) for maternal hyperhomocysteinaemia (>14.3 micromol/l). This finding is substantiated by a significant concentration-dependent risk (Ptrend = 0.004). Hyperhomocysteinaemic case-mothers showed significantly lower serum folate and vitamin B12 concentrations than normohomocysteinaemic case-mothers. Serum and RBC folate concentrations were significantly higher in case-children than that in control-children.

CONCLUSIONS

Maternal hyperhomocysteinaemia is associated with an increased risk of CHD, partially due to low folate and vitamin B12 status. The folate status of children warrants further investigation.

Acute and concomitant deterioration of hyponatremia and renal dysfunction associated with heart and liver failure

BACKGROUND

Although hyponatremia with concomitant renal dysfunction has been described anecdotally, little is known about how these two conditions are related, which type of renal dysfunction usually occurs, and which patients are at risk.

METHODS

From 3029 measured serum sodium (S(Na)) concentrations in 3 months, patients with at least one S(Na) < or =125 mmol/l were selected, and divided in patients with at least 1 S(Creat) > or =125 micromol/l (study group, n=20), and patients whose S(Creat) remained normal (control group, n=50).

RESULTS

During the first 5 days of hospitalization, S(Creat) almost doubled in the study group from 125 +/- 40 micromol/l to 207 +/- 72 micromol/l, while S(Na) decreased concurrently from 130 +/- 2 mmol/l to 122 +/- 3 mmol/l. The peak S(Creat) and S(Na) values coincided, and the average courses were highly correlated (r = 0.88, p < 0.001). The study group more often had heart failure (10/20 vs. 1/50, p < 0.001) and liver failure (7/20 vs. 4/50, p = 0.009), and received more often loop diuretics (13/20 vs. 12/50, p = 0.002), spironolactone (11/20 vs. 7/50, p = 0.001), and/or angiotensin-converting enzyme inhibitors (5/20 vs. 2/50, p = 0.02). Four patients were admitted to the intensive care (10 in control group, p = 1.0), and 5 patients died (10 in control group, p = 0.7).

CONCLUSIONS

Renal dysfunction is common in severe hyponatremia and usually develops in an acute-on-chronic fashion with concomitant deterioration of both conditions. This concourse is associated with heart failure, liver failure, and/or a renal drug regimen. Given the recent results of clinical trials, this patient group may be especially suitable for treatment with vasopressin antagonists.

A shift to a peripheral Th2-type cytokine pattern during the carcinogenesis of cervical cancer becomes manifest in CIN III lesions

BACKGROUND

A shifted balance between T helper 1 (Th1)-type and Th2-type cytokines has been hypothesised in cervical dysplasia.

AIMS

To evaluate possible deregulation of the cytokine network by estimating the expression of peripheral cytokines in different stages of cervical disease and in relation to the presence or absence of high risk human papillomavirus (HR-HPV).

METHODS

Twenty one HR-HPV positive women with high grade cervical intraepithelial neoplasia (CIN II-III) and 12 patients with invasive cervical carcinoma formed the study groups. Two control groups consisted of 10 HR-HPV positive and 11 HR-HPV negative women without CIN. Differences in leucocyte subgroups were evaluated by a differential leucocyte count. Plasma concentrations of tumour necrosis factor alpha (TNFalpha), TNFalpha receptors TNFRI and TNFRII, interferon gamma (IFNgamma), interleukin 2 (IL-2), IL-12, IL-4, and IL-10 were determined by enzyme linked immunosorbent assays.

RESULTS

Leucocyte counts in patients with CIN III and carcinoma were significantly higher than in controls. Plasma IFNgamma concentrations were significantly lower in patients with CIN III and carcinoma than in women with CIN II or controls. Plasma concentrations of IL-12, IL-2, IL-4, and TNFalpha did not differ significantly between groups, but significantly lower plasma concentrations of TNFRII were found in CIN III and carcinoma compared with CIN II. IL-10 was detected with increased frequency in the plasma of patients with CIN III and carcinoma.

CONCLUSIONS

These results indicate that a shift to a Th2-type cytokine pattern during the carcinogenesis of cervical cancer occurs in women with CIN III lesions.

New approach for the identification of folate-related pathways in human embryogenesis

The role of natural folate intake and synthetic folic acid supplementation in the prevention of some congenital malformations is known, but on a molecular biological level poorly understood. In a first approach to identify folate-regulated pathways in human embryogenesis, tryptic digests of Epstein Barr Virus-immortalized B-lymphoblasts proteins from 6 cleft lip and/or palate patients and 2 controls were compared using matrix assisted laser desorption ionisation--time of flight (MALDI-TOF) mass spectrometry. After immortalisation, the lymphoblasts were cultured for 22 days in folate-rich, i.e. 5-methyltetrahydrofolate (5-mTHF), or folate-free medium. On day 22, 5-mTHF was added to the folate-free cultures and the profiles on day 22 and 23 were compared. After background correction for the peptide profiles of the folate-rich cultures, we found in the folate-free mediaseveral differentially expressed peptide peaks upon addition of 5-mTHF. These peptide peaks were mass annotated and matched withthe MSDB human database. The results suggest some folate-regulated protein candidates as Frizzled and the Rho GTP-ases WRCH and Chp that are known in human embryogenesis. Differential folate expressed proteins in patients and controls, however, have to be further investigated.

Significance of elevated cobalamin (vitamin B12) levels in blood

Elevated levels of serum cobalamin may be a sign of a serious, even life-threatening, disease. Hematologic disorders like chronic myelogeneous leukemia, promyelocytic leukemia, polycythemia vera and also the hypereosinophilic syndrome can result in elevated levels of cobalamin. Not surprisingly, a rise of the cobalamin concentration in serum is one of the diagnostic criteria for the latter two diseases. The increase in circulating cobalamin levels is predominantly caused by enhanced production of haptocorrin. Several liver diseases like acute hepatitis, cirrhosis, hepatocellular carcinoma and metastatic liver disease can also be accompanied by an increase in circulating cobalamin. This phenomenon is predominantly caused by cobalamin release during hepatic cytolysis and/or decreased cobalamin clearance by the affected liver. Altogether it can be concluded that an observed elevation of cobalamin in blood merits the a full diagnostic work up to assess the presence of disease.

Automated counting of white blood cells in synovial fluid

OBJECTIVES

To evaluate the performance of automated leucocyte (white blood cell; WBC) counting by comparison with manual counting.

METHODS

The number of WBC was determined in heparinized synovial fluid samples by the use of (i) a standard urine cytometer (Kova) and a microscope (reference method) and (ii) a haematology analyser (Sysmex XE-2100; WBC/BASO and DIFF channels). Imprecision within and between days was determined by replicate analysis of a low (level A; WBC approximately 0.560 x 10(9)/l) and a high (level B; WBC approximately 1.081 x 10(9)/l) dedicated synovial fluid control (Quantimetrix).

RESULTS

The WBC count of the DIFF channel was highly correlated with the WBC count of the microscopic reference method (r = 0.99; WBC analyser = 0.870 x WBC reference method + 0.413). In contrast, no agreement existed between WBC counts generated by the WBC/BASO channel of the analyser and the reference method (r = 0.52; WBC analyser = 0.008 x WBC reference method + 0.079). Within-day imprecision (4-7%) and between-day imprecision (10%) of the haematology analyser were smaller than the within-day imprecision (12%) and the between-day imprecision (20-22%) of the manual reference method. For manual counting, inter-observer coefficients of variation were 35.9% (control level A) and 21.0% (control level B).

CONCLUSIONS

The WBC count in synovial fluid can be reliably determined using the DIFF channel of the Sysmex XE-2100. Automated counting of WBC in synovial fluid offers more precise and faster results than manual counting.

[The significance of an elevated cobalamin concentration in the blood]

Elevated levels of serum cobalamin may be a sign of a serious, even life-threatening, disease. Diseases such as chronic myeloid leukaemia, promyelocytic leukaemia, polycythaemia vera and hypereosinophilic syndrome are often accompanied by markedly elevated levels of cobalamin in the blood. A rise in the serum cobalamin concentration is one of the diagnostic criteria for polycythaemia vera and hypereosinophilic syndrome. In haematological disorders, the increase in circulating cobalamin levels is predominantly caused by enhanced production of haptocorrin. Several liver diseases such as acute hepatitis, cirrhosis of the liver, hepatocellular carcinoma and metastatic liver disease can also be accompanied by an increase in circulating cobalamin. In liver diseases, the increase in cobalamin is predominantly caused by cobalamin release during hepatic cytolysis and/or through decreased clearance of circulating cobalamin by the affected liver. Liver disorders are not an indication for determining the serum cobalamin concentration. However, a coincidentally observed elevated serum cobalamin concentration is reason for further investigation.

The effect of hormone replacement therapy on serum homocysteine levels in perimenopausal women: a randomized controlled trial

Serum homocysteine levels may be lowered by hormone replacement therapy, but randomized controlled trial data are scarce. We performed a single center randomized placebo-controlled trial to assess the 6 months effect of hormone replacement therapy compared with placebo on fasting serum homocysteine levels in 121 perimenopausal women free of cardiovascular disease, and recruited from the general population. The trial was double-blind with respect to a sequential combined regimen of oral 17 beta-estradiol and desogestrel (17 beta E(2)-D) and the placebo group and open with respect to a combination of conjugated equine estrogens and norgestrel (CEE-N). At baseline and after 6 months, fasting serum homocysteine levels were measured. Differences in 6 months serum homocysteine levels from baseline between treatment and placebo groups were calculated, and expressed as a percentage of the 6 months placebo level. After 6 months, the difference in serum homocysteine levels between women receiving 17 beta E(2)-D and placebo was -6.3% (95% CI, -12.4%; 0.0%, P=0.06). The difference between women receiving CEE-N and placebo was -10.1% (95% CI, -16.7%; -2.9%, P<0.01). The difference between the combined group of both types of hormone replacement therapy users and placebo was -7.8% (95% CI, -13.2%; -2.0%, P=0.01). No significant difference was observed between the two active regimens. Our results indicate that hormone replacement therapy decreases homocysteine levels in perimenopausal women.

Does iron-deficient erythropoiesis in pregnancy influence fetal iron supply?

BACKGROUND

It was investigated whether the iron status in newborns is negatively influenced by iron-deficient erythropoiesis of the mother during pregnancy.

METHODS

The iron status is characterized by hemoglobin, erythrocyte zinc protoporphyrin and serum ferritin values. Iron-deficient erythropoiesis of the mother is characterized by erythrocyte zinc protoporphyrin values. Measurement of erythrocyte zinc protoporphyrin was performed in 103 non-anemic females within 24 hours after delivery. The iron status of their newborns was measured in cord blood.

RESULTS

Erythrocyte zinc protoporphyrin concentrations were normal in 62% and elevated in 38% of the females, hence 39 women had iron-deficient erythropoiesis. There were no significant differences in mean values of the iron status parameters between neonates born to females with iron-deficient erythropoiesis and neonates born to females not having iron-deficient erythropoiesis. No correlation was found between maternal erythrocyte zinc protoporphyrin values and any of the neonatal parameters.

CONCLUSION

It is concluded that fetal iron supply is not negatively influenced by iron-deficient erythropoiesis in the mother.

Erythrocyte zinc protoporphyrin testing in pregnancy

BACKGROUND

To compare the usefulness of serum ferritin, hemoglobin and erythrocyte zinc protoporphyrin estimations as indicators of the need of iron supplementation in pregnancy.

METHODS

In 97 healthy pregnant women serum ferritin, hemoglobin and erythrocyte zinc protoporphyrin concentrations were measured at each trimester period. Iron supplementation was prescribed at hemoglobin values below 113 g/L.

RESULTS

Neither in the first nor in the second trimester differences in serum ferritin and erythrocyte zinc protoporphyrin values have been found between women who got iron therapy prescribed and women who did not get iron therapy, whereas already in the first trimester hemoglobin values were lower in the group that got iron therapy. These results indicate that hemodilution rather than iron deficiency determined which women got iron therapy. In the third trimester 14 out of 80 women without iron supplementation had depleted iron stores and a significant erythrocyte zinc protoporphyrin increase, indicating evolving iron deficiency anemia. However, only five of them showed hemoglobin levels below 113 g/L and got iron therapy. Low serum ferritin levels were found in 23% of the women at booking and in 92% in the third trimester. Serum ferritin levels neither predicted the development of iron deficient erythropoiesis nor of anemia.

CONCLUSIONS

Iron deficiency can neither be diagnosed nor predicted by serum ferritin or hemoglobin measurements at booking or later on in pregnancy. Erythrocyte zinc protoporphyrin measurements can be of help in determining which women have iron deficient erythropoiesis and may benefit by iron therapy.

Total homocysteine and cognitive decline in a community-based sample of elderly subjects: the Rotterdam Study

Homocysteine has been associated with an increased risk of cardiovascular disease. Cardiovascular diseases have been related to cognitive decline. The authors investigated the association of homocysteine with concurrent cognitive impairment and subsequent cognitive decline in a random sample of 702 community-dwelling respondents aged 55 years or over to the prospective Rotterdam Study in 1990-1994. Multiple logistic regression was used to calculate odds ratios and 95 percent confidence intervals for the association between total homocysteine levels and cognitive impairment (Mini-Mental State Examination (MMSE) score <26) and cognitive decline (drop in MMSE score of >1 point/year). Mean duration of follow-up was 2.7 years. After adjustment for age, sex, and education, there was no relation between total homocysteine and cognitive impairment (highest vs. lowest tertile: odds ratio (OR) = 1.30, 95% confidence interval (CI): 0.50, 3.38) or cognitive decline (middle vs. lowest tertile: OR = 1.14, 95% CI: 0.67, 1.93; highest vs. lowest tertile: OR = 0.91, 95% CI: 0.52, 1.58). Subjects who were lost to follow-up due to death or nonresponse had slightly higher age-adjusted homocysteine levels and lower MMSE scores at baseline. Sensitivity analyses showed that selective loss to follow-up was not a likely explanation for the absence of an association in the participants. Although a relation between homocysteine and reduced cognitive function is biologically plausible, this study suggests no such association in a community-based sample of the elderly.

Serum ferritin and risk of myocardial infarction in the elderly: the Rotterdam Study

BACKGROUND

Elevated body iron stores have been suggested to be a risk factor for ischemic heart disease.

OBJECTIVE

We examined whether elevated serum ferritin concentrations, other indicators of iron status, and dietary iron affected the incidence of myocardial infarction (MI) in an elderly population.

DESIGN

A nested, case-control study of 60 patients who had their first MI and 112 age- and sex-matched control subjects embedded in the population-based cohort of the Rotterdam Study.

RESULTS

The age- and sex-adjusted risk of MI for subjects with serum ferritin concentrations > or = 200 microg/L was 1.82 (95% CI: 0.90, 3.69; P = 0.096). The odds ratio (OR) was 1.26 (95% CI: 0.98, 1.64; P = 0.078) for the highest tertile of serum ferritin and was only slightly altered in a multivariate model. Risk of MI associated with the highest tertile of ferritin was most evident in current or former smokers (OR: 1.68; 95% CI: 1.17, 2.47; P for trend = 0.008) and in subjects with hypercholesterolemia (OR: 1.43; 95% CI: 0.99, 2.11; P for trend = 0.056) or diabetes (OR: 2.41; 95% CI: 1.12, 7.67; P for trend = 0.027). No association with risk of MI was observed for tertiles of serum iron, serum transferrin, or total dietary iron. For dietary heme iron, risk of MI was significantly increased in a multivariate model in which dietary energy, fat, saturated fat, and cholesterol were adjusted for (OR: 4.01; 95% CI: 1.17, 15.87; P for trend = 0.031).

CONCLUSION

In the presence of other risk factors, serum ferritin may adversely affect ischemic heart disease risk in the elderly.

Optimization of apolipoprotein(a) genotyping with pulsed field gel electrophoresis

BACKGROUND

Increased lipoprotein(a) is a risk factor for atherosclerosis, and its concentration in serum is inversely correlated with the size of the apoliprotein(a) [apo(a)] component. The size of the apo(a) gene is determined mainly by the Kringle IV size polymorphism. We have optimized and characterized pulsed field gel electrophoresis (PFGE) for apo(a) genotyping.

METHODS

Established PFGE protocols were adjusted. The changes included the following: (a) increased DNA yields by the use of all leukocytes for isolation from either 3 mL of fresh EDTA whole blood or 250 microL of frozen buffy coats; (b) increased efficiency of Kpn1 digestion by the inclusion of a digestion buffer wash; (c) reduction of assay time by the use of capillary blotting; (d) increased sensitivity by the use of four digoxigenin-labeled apo(a) probes; and (e) identification using a single film by the inclusion of a digoxigenin-labeled lambda marker probe in addition to apo(a) probes in the hybridization mix.

RESULTS

In older Caucasians, 93% (buffy coats, n=468) were heterozygous for apo(a) gene size. An inverse correlation between serum lipoprotein(a) and the sum of Kringle IV alleles was found (y = -23x + 1553; r = -0.442; n = 468). Gel-to-gel variation was minimal (3%). Imprecision (SD) was one Kringle IV repeat (control sample containing eight fragments of 72-233 kb; n=34 electrophoretic runs).

CONCLUSIONS

The practicality and sensitivity of the apo(a) genotyping technique by PFGE were improved, and accuracy and reproducibility were preserved. The optimized procedure is promising for apo(a) genotyping on frozen buffy coats from large epidemiological studies.

Serum caeruloplasmin as a coronary risk factor in the elderly: the Rotterdam Study

Serum Cu and caeruloplasmin levels have been suggested to be independent risk factors for CHD operating through oxidative modification of LDL. However, given its function as an acute-phase protein, the question has been raised whether an elevated caeruloplasmin level is not merely an indicator of inflammation. In the current study, we investigated whether serum caeruloplasmin was associated with subsequent myocardial infarction, taking into account indices of inflammation. The study population consisted of 210 cases of first myocardial infarction and controls, frequency-matched on age (5-year categories) and sex, selected from the population-based cohort of the Rotterdam Study. Serum caeruloplasmin levels were significantly elevated in cases of myocardial infarction compared with controls (510 (SD 110) v. 470 (SD 100) mg/l; P = 0.007). Risk of myocardial infarction for the highest compared with the lowest quartile of caeruloplasmin was 2.46 (95% CI 1.04, 6.00; Ptrend = 0.043) after adjustment for age, sex, BMI, pack-years smoked, serum cholesterol, systolic blood pressure, and income. The relative risk was most evident in current smokers. Adjustment for C-reactive protein and leucocyte count reduced the excess risk by 33%. This suggests that a substantial part of the observed association between serum caeruloplasmin and CHD may be attributed to inflammation processes rather than to the pro-oxidant activity of caeruloplasmin.

Influence of iron deficiency anaemia on haemoglobin A2 levels: possible consequences for beta-thalassaemia screening

Iron deficiency modulates the synthesis of HbA2, resulting in reduced HbA2 levels in patients with iron deficiency anaemia. The diagnosis heterozygous beta-thalassaemia is based on a raised HbA2 level. Patients with beta-thalassaemia and concomitant iron deficiency can show normal HbA2 levels. It is of clinical importance to know the quantitative effect of iron-deficient erythropoiesis on the levels of HbA2 in order to be able to determine which iron-deficient patients with normal HbA2 levels have to be retested after iron therapy in thalassaemia screening programmes. In this study, HbA2 levels in 150 patients with iron-deficiency anaemia and 71 healthy controls have been measured. A linear correlation is found in the patient group between HbA2 and Hb, HbA2 and MCV, and HbA2 and erythrocyte zinc protoporphyrin (ZPP). In future studies, the correlation between HbA2 and erythrocyte parameters in patients with heterozygous beta-thalassaemia and concomitant iron deficiency has to be examined. We recommend that ZPP be measured in these studies too, as ZPP levels may be a better indicator of concomitant iron deficiency than Hb or MCV in thalassaemic patients.

Homocysteine and short-term risk of myocardial infarction and stroke in the elderly: the Rotterdam Study

BACKGROUND

Elevated homocysteine level increases vascular disease risk. Most data are based on subjects younger than 60 years; data for the elderly are more limited. We examined the relationship of homocysteine level to incident myocardial infarction and stroke among older subjects in a nested case-control study.

METHODS

Subjects were participants in the Rotterdam Study, a cohort study among 7983 subjects residing in the Ommoord district of Rotterdam, the Netherlands. Baseline examinations were performed from March 1, 1990, to July 31, 1993. The analysis is restricted to myocardial infarction and stroke that occurred before December 31, 1994. One hundred four patients with a myocardial infarction and 120 with a stroke were identified with complete data. Control subjects consisted of a sample of 533 subjects drawn from the study base, free of myocardial infarction and stroke. Nonfasting total homocysteine levels were measured.

RESULTS

Results were adjusted for age and sex. The risk of stroke and myocardial infarction increased directly with total homocysteine. The linear coefficient suggested a risk increase by 6% to 7% for every 1-micromol/L increase in total homocysteine. The risk by quintiles of total homocysteine level was significantly increased only in the group with levels above 18.6 micromol/L (upper quintile): odds ratios were 2.43 (95% confidence interval, 1.11-5.35) for myocardial infarction and 2.53 (95% confidence interval, 1.19-5.35) for stroke. Associations were more pronounced among those with hypertension.

CONCLUSIONS

The present study, based on a relatively short follow-up period, provides evidence that among elderly subjects an elevated homocysteine level is associated with an increased risk of cardiovascular disease.

Portable blood gas and electrolyte analyzer evaluated in a multiinstitutional study

A recently introduced blood gas/electrolyte analyzer (SenDx 100((R)), renamed ABL70) intended for point-of-care, near-patient, or stat laboratory use was evaluated simultaneously in four different institutions and compared with three different laboratory bench analyzers with respect to imprecision, inaccuracy (assessed by tonometry), and patient-sample analyses. The analyzer is equipped with a sensor cassette and a reagent cartridge for 50, 100, or 200 analyses and 100 or more traditional quality-control measurements. One analysis requires 170 microL of whole blood and takes <90 s. Statistically, the instrument performed somewhat better (lower CVs) for PO2 and potassium and somewhat worse for pH, PCO2, and ionized calcium than the respective comparison analyzers. However, the overall performance (in terms of CV and accuracy) was satisfactory in terms of clinical (e.g., CLIA '88) goals in all institutions. The mean difference and the CV of that difference in some 400 patient-sample comparisons were as follows: 0.010 (+/- 0.002%) for pH, -0.65 mmHg (+/- 4%) for PCO2, -0.49 mmHg (+/- 6%) for Po2, 0.44 mmol/L (+/- 1.2%) for sodium, -0.013 mmol/L (+/- 2.9%) for potassium, -0.016 mmol/L (+/- 2.6%) for ionized calcium, and -0.016 L/L (+/- 7. 1%) for the hematocrit. Its acceptable analytical performance and ease of operation make the SenDx 100 suitable for the analysis of blood gases and electrolytes.

Combined use of erythrocyte zinc protoporphyrin and mean corpuscular volume in differentiation of thalassemia from iron deficiency anemia

In a retrospective study the diagnostic value of erythrocyte zinc protoporphyrin (ZPP) measurement as a means of distinguishing iron deficiency anemia from thalassemia syndromes in patients with microcytosis was explored. ZPP values were increased in all patients with iron deficiency and in part of the patients with thalassemia. The combined measurement of erythrocyte mean corpuscular volume (MCV) and ZPP resulted in a correct classification of patients with iron deficiency and with thalassemia in more than 95%. The predictive value of this method is better than the results obtained by using formulae derived from red cell indices. In population screening programs for thalassemia syndromes, in which MCV determination is used as the initial test, the ZPP test is recommended as a second test, in order to discriminate between patients with microcytosis due to iron deficiency and patients with microcytosis due to thalassemia syndromes.

Zinc protoporphyrin as screening test in female blood donors

Erythrocyte zinc protoporphyrin (ZPP) was measured in 102 women blood donors to evaluate its usefulness in screening for evolving iron deficiency anemia, a reason for the deferral of donors. The results were compared with serum ferritin determinations. Five women were deferred before their first donation and eight women were deferred after one or two donations. Women with increased ZPP values all had low serum ferritin concentrations, indicating iron-deficient erythropoiesis that was caused by iron depletion. The positive predictive value of an increased ZPP in predicting deferral of the donor after one or two donations was 75%, whereas a serum ferritin concentration < or = 12 microg/L predicted deferral in 26% of the donors. The results indicate that the ZPP test can be recommended as a feasible and inexpensive predonation test to determine a subset of donors with iron-deficient erythropoiesis at risk of developing iron deficiency anemia.

Methionine synthase deficiency without megaloblastic anaemia

We report findings on a child presenting with neonatal homocystinuria, hypomethioninaemia and severe neurological symptoms, including developmental delay and seizures. Methylmalonic aciduria was not present. The activity of methionine synthase in fibroblasts was severely deficient and formation of methylcobalamin from 57Co labelled cyanocobalamin was very low. The patients cells complemented with those of a cblE patient but not with those of two cblG patients. No biochemical or clinical response to injections of hydroxycobalamin was found. Both off treatment and on betaine and methionine supplementation the patient, at age 8 years, has not developed megaloblastic anaemia. In addition, the patient is homozygous for the C677T polymorphism in the 5,10 methylenetetrahydrofolate reductase (MTHFR) gene and the concomitant existence of this mutation with the methionine synthase defect may prevent folate <<trapping>> and thus anaemia.

CONCLUSION

We report the lack of megaloblastic anaemia in a patient with severe methionine synthase deficiency who is also homozygous for C677T in MTHFR, hypothesize that the MTHFR polymorphism protects the patient against anaemia and speculate that homozygosity for MTHFR C677T could cause the dissociation between haematological and neurological disease seen in some patients with vitamin B12 deficiency.

Modulation of lipoprotein(a) atherogenicity by high density lipoprotein cholesterol levels in middle-aged men with symptomatic coronary artery disease and normal to moderately elevated serum cholesterol. Regression Growth Evaluation Statin Study (REGRESS) Study Group

OBJECTIVES

This study sought to examine whether lipoprotein(a) levels predict coronary artery lumen changes in patients with symptomatic coronary artery disease (CAD) and normal to moderate hypercholesterolemia.

BACKGROUND

Recent conflicting reports have confirmed or refuted the association of lipoprotein(a) with clinical events or angiographically verified disease progression.

METHODS

The association between serum lipoprotein(a) and changes in coronary artery lumen was studied in 704 men entered into the Regression Growth Evaluation Statin Study (REGRESS), a double-blind, placebo-controlled, quantitative angiographic study that assessed the effect of 2 years of pravastatin treatment. The primary end points were changes in average mean segment diameter (MSD) and average minimal obstruction diameter (MOD). Pravastatin- and placebo-treated patients were classified as having progressing, regressing or stable CAD, and median lipoprotein(a) concentrations were compared. Bivariate and multivariate regression analyses were performed in the overall patient group and in high risk subgroups.

RESULTS

Pravastatin treatment did not affect serum apolipoprotein(a) levels. Median in-trial (sampled at 24 months) apolipoprotein(a) levels for regressing, stable and progressing CAD were, respectively, 130, 162 and 251 U/liter in placebo-treated patients and 143, 224 and 306 U/liter in pravastatin-treated patients. Predictors of MSD and MOD changes were baseline MSD and MOD, in-trial apolipoprotein(a), in-trial high density lipoprotein (HDL) cholesterol and baseline use of long-acting nitrates. The multivariate models predicted 14% of MSD changes and 12% of MOD changes; apolipoprotein(a) predicted only 2.6% and 4.8%, respectively. However, in patients with in-trial HDL cholesterol levels <0.7 mmol/liter, apolipoprotein(a) predicted up to 37% of the arteriographic changes.

CONCLUSIONS

Serum lipoprotein(a) levels predict coronary artery lumen changes in normal to moderately hypercholesterolemic white men with CAD; its atherogenicity is marked in the presence of concomitant hypoalphalipoproteinemia.

Folate-responsive homocystinuria and megaloblastic anaemia in a female patient with functional methionine synthase deficiency (cblE disease)

This first detailed report of a female patient with functional methionine synthase deficiency due to the cblE defect describes treatment with several vitamins and cofactors and clinical progress for 17 years. Before treatment, major findings were microcephaly, psychomotor retardation, episodic reduced consciousness, megaloblastic anaemia, increased plasma free homocystine (> 20 mumol/L), low plasma methionine (< 10 mumol/L) and increased excretion of formiminoglutamate. On high-dose folic acid, biochemical abnormalities such as formiminoglutamate excretion and homocystinuria nearly normalized, but clinical and haematological abnormalities remained. On replacement of folate with methylcobalamin, alertness, motor function, speech and the electroencephalogram improved, biochemical features were similar, but the mean corpuscular volume increased. The best control was observed on a combination of folate and methylcobalamin. At 17 years of age she remains severely mentally retarded. In cultured fibroblasts methionine synthesis was reduced (0.03 nmol/mg/per 16 h, controls 2.4-6.9); methionine synthase activity was normal under high reducing conditions but decreased on limiting the reducing agent, dithiothreitol, to 5 mmol/L (18% of total, controls 51-81%); formation of methylcobalamin was low (4.5% of total cobalamins, control 57.5%) and complementation studies indicated the cblE defect. Methionine formation showed only minor increases in cells grown in folate- or cobalamin-supplemented medium. Serine synthesis, which was low in normal medium, increased with cobalamin supplementation. These studies suggest further heterogeneity within cblE mutants, show the difficulty of establishing the enzyme defect in vitro, and indicate a role for folate in addition to cobalamin in treatment.

Thermolabile methylenetetrahydrofolate reductase in coronary artery disease

BACKGROUND

Hyperhomocysteinemia, an independent and graded risk factor for coronary artery disease (CAD), may result from both environmental and hereditary factors. Methylenetetrahydrofolate reductase (MTHFR) catalyzes the conversion of methylenetetrahydrofolate to methyltetrahydrofolate, the methyl donor in the remethylation of homocysteine to methionine. A 677C-->T mutation in the MTHFR gene has been associated with elevated homocysteine concentrations in homozygous (+/+) individuals.

METHODS AND RESULTS

We assessed the frequency of this common mutation in 735 CAD patients from the Regression Growth Evaluation Statin Study (REGRESS), a lipid-lowering coronary-regression trial, and in 1250 population-based control subjects. Furthermore, the association between the mutation and serum homocysteine concentrations was studied. The frequency of the homozygous (+/+) mutation was 9.5% among patients versus 8.5% among control subjects, resulting in an odds ratio of 1.21 (95% confidence interval [CI], 0.87 to 1.68), relative to the (-/-) genotype. Homocysteine concentrations were significantly elevated in both (+/+) and (+/-) individuals compared with (-/-) individuals (median homocysteine levels, 15.4, 13.4, and 12.6 micromol/L, for (+/+), (+/-), and (-/-) individuals, respectively). For a summary estimation of the risk of the (+/+) genotype for CAD, we performed a meta-analysis on 8 different case-control studies on thermolabile MTHFR in CAD. In the meta-analysis, the homozygous (+/+) genotype was present in 299 of 2476 patients (12.1%) and in 257 (10.4%) of 2481 control subjects, resulting in a significant odds ratio of 1.22 (95% CI, 1.01 to 1.47) relative to the (-/-) genotype.

CONCLUSIONS

Both the homozygous (+/+) and heterozygous (+/-) genotype result in elevated homocysteine concentrations. From our meta-analysis, we conclude that the homozygous (+/+) genotype is a modest but significant risk factor for CAD.

Significance of various parameters derived from biological variability of lipoprotein(a), homocysteine, cysteine, and total antioxidant status

Analytical and biological components of variability and various derived indices have been determined for lipoprotein(a) [Lp(a)], homocysteine (Hcy), cysteine (Cys), and total antioxidant status (TAOS) in ostensibly healthy adult Caucasians and in stable outpatients with an increased serum Lp(a). In healthy Caucasians, average intraindividual biological CVs (CVb) were 20.0% for Lp(a), 9.4% for Hcy, 5.9% for Cys, and 2.8% for TAOS, CVbs being similar in men and women. In the outpatient group, CVbs were comparable for Hcy, Cys, and TAOS, but significantly lower for Lp(a) (7.5% vs 20.0%; P <0.0001). Moreover, a significant inverse relation between both biological and analytical CVs (CVa) and serum Lp(a) concentrations was demonstrated. We conclude that average CVa and CVb values, and hence average derived indices, are adequate for Hcy, Cys, and TAOS, whereas individual values should be used for Lp(a).

Homocysteine, atherosclerosis and prevalent cardiovascular disease in the elderly: The Rotterdam Study

OBJECTIVES

Elevated homocysteine increases the risk of vascular disease, in particular amongst younger subjects (< 60 years). Very few studies have been performed amongst older subjects. We evaluated the relation of plasma total homocysteine (tHcy) to atherosclerosis and symptomatic cardiovascular disease amongst older men and women.

DESIGN

A cross-sectional study.

SETTING

General population.

SUBJECTS

A random sample of 630 men and women, participating in the Rotterdam Study, a prospective population-based cohort study amongst 7983 subjects aged 55 years and over residing in the Ommoord district of Rotterdam, the Netherlands.

MAIN OUTCOME MEASURES

Carotid atherosclerosis (carotid plaques and common carotid intima-media thickness) assessed by ultrasonography; lower extremity (peripheral) artery atherosclerosis measured by the ratio of the ankle to arm systolic blood pressure; prevalent cardiovascular disease assessed as a history of myocardial infarction or stroke.

RESULTS

Subjects, 55-74 years of age, with elevated tHcy levels (+/- 18.6 mumol L-1) had a thicker common carotid intima-media (difference 0.037 mm; 95% CI 0.001, 0.073), a lower ankle-arm index (-0.054; -0.104, -0.004), and an increased risk of cardiovascular disease (odds ratio 3.0; 1.5, 6.1), after adjusting for sex and age. There was no appreciable association of tHcy levels to atherosclerosis and cardiovascular disease in subjects aged 75 years and older.

CONCLUSIONS

In subjects aged 55-74 years elevated tHcy is associated with an increased risk of atherosclerosis and cardiovascular disease. The lack of association in those aged > or = 75 years most probably reflect selective mortality.

Serum LP(a) levels in African aboriginal Pygmies and Bantus, compared with Caucasian and Asian population samples

Serum lipoprotein(a) (Lp(a)) and its correlates were studied in African Aboriginal Pygmies (n = 146) and Bantus (n = 208) from Cameroon. Geometric mean Lp(a) levels were 274 and 289 mg/l in Bantu males and females, respectively, and 220 and 299 mg/l in Pygmy males and females, the gender difference being significant in Pygmies (p = 0.024). In Pygmies 41% and 52% of the males and females, respectively, had Lp(a) levels above 300 mg/l, compared with 47% and 55% in Bantus. Overall, Lp(a) levels did not significantly differ between Pygmies and Bantus, and did not correlate with age, body mass index (BMI), systolic and diastolic blood pressure. Compared with healthy Asian and Caucasian population samples, age- and BMI-adjusted geometric Lp(a) means were 2.3- to 5.0-fold higher in Pygmy and Bantu males, and 2.9- to 3.6-fold higher in Pygmy and Bantu females (p < or = 0.05). Across the population samples studied ethnicity predicted 12% and 17% of serum Lp(a) variance in males and females, respectively.

Chromogranin A as serum marker for neuroendocrine neoplasia: comparison with neuron-specific enolase and the alpha-subunit of glycoprotein hormones

Chromogranin A (CgA) is gaining acceptance as a serum marker of neuroendocrine tumors. Its specificity in differentiating between neuroendocrine and nonneuroendocrine tumors, its sensitivity to detect small tumors, and its clinical value, compared with other neuroendocrine markers, have not clearly been defined, however. The objectives of this study were to evaluate the clinical usefulness of CgA as neuroendocrine serum marker. Serum levels of CgA, neuron-specific enolase (NSE), and the alpha-subunit of glycoprotein hormones (alpha-SU) were determined in 211 patients with neuroendocrine tumors and 180 control subjects with nonendocrine tumors. The concentrations of CgA, NSE, and alpha-SU were elevated in 50%, 43%, and 24% of patients with neuroendocrine tumors, respectively. Serum CgA was most frequently increased in subjects with gastrinomas (100%), pheochromocytomas (89%), carcinoid tumors (80%), nonfunctioning tumors of the endocrine pancreas (69%), and medullary thyroid carcinomas (50%). The highest levels were observed in subjects with carcinoid tumors. NSE was most frequently elevated in patients with small cell lung carcinoma (74%), and alpha-SU was most frequently elevated in patients with carcinoid tumors (39%). Most subjects with elevated alpha-SU levels also had elevated CgA concentrations. A significant positive relationship was demonstrated between the tumor load and serum CgA levels (P < 0.01, by chi 2 test). Elevated concentrations of CgA, NSE, and alpha-SU were present in, respectively, 7%, 35%, and 15% of control subjects. Markedly elevated serum levels of CgA, exceeding 300 micrograms/L, were observed in only 2% of control patients (n = 3) compared to 40% of patients with neuroendocrine tumors (n = 76). We conclude that CgA is the best general neuroendocrine serum marker available. It has the highest specificity for the detection of neuroendocrine tumors compared to the other neuroendocrine markers, NSE and alpha-SU. Elevated levels are strongly correlated with tumor volume; therefore, small tumors may go undetected. Although its specificity cannot compete with that of the specific hormonal secretion products of most neuroendocrine tumors, it can have useful clinical applications in subjects with neuroendocrine tumors for whom either no marker is available or the marker is inconvenient for routine clinical use.

A computer program for constructing multivariate reference models

From a statistical point of view the simultaneous interpretation of multiple variables should be performed with a multivariate reference model rather than with multiple univariate reference intervals. A computer program for constructing and testing multivariate reference models is described. The use of the computer program is illustrated with a data set of total serum calcium concentrations and serum albumin concentrations from 222 2nd year medical students. Using a single univariate reference interval for total serum calcium, 17 students were classified as having an abnormal calcemic status while using a bivariate reference model for total serum calcium and serum albumin, 13 of these 17 students had in fact normal total serum calcium concentrations, taking into account their serum albumin concentrations.