Association of MTRR A66G polymorphism (but not of MTHFR C677T and A1298C, MTR A2756G, TCN C776G) with homocysteine and coronary artery disease in the French population

methylenetetrahydrofolate reductase polymorphism (MTHFR C677T) is an established determinant of homocysteine plasma level (t-Hcys) while its association with coronary artery disease (CAD) seems to be more limited. In contrast, the association of the substitutions A2756G of methionine synthase (MTR), A66G of methionine synthase reductase (MTRR) and C776G of transcobalamin (TCN) to both t-Hcys and CAD needs to be evaluated further. The objective was to evaluate the association of these polymorphisms with t-Hcys and CAD in a French population. We investigated the individual and combined effects of these polymorphisms and of vitamin B12 and folates with t-Hcys in 530 CAD patients and 248 matched healthy controls. t-Hcys was higher in the CAD group than in controls (11.8 vs 10.4 μM, P<0.0001) and in carriers of MTRR AA and MTHFR 677TT than in those carrying the most frequent allele of both polymorphisms (13.8 vs 11.4 μM, P=0.0102 and 12.5 vs 11.0 mM, P=0.0065 respectively). The frequency of MTRR A allele was higher in CAD patients than in controls (0.48 [95% CI: 0.44-0.52] vs 0.38 [95% CI: 0.32-0.44], P=0.0081) while no difference was observed for MTHFR 677T frequency. In multivariate analysis, t-Hcys > median and MTRR AA genotype were two significant independent predictors of CAD with respective odds ratios of 3.1 (95 % CI: 1.8-5.1, P<0.0001) and 4.5 (95% CI: 1.5-13.1, P=0.0051). In conclusion, in contrast to North Europe studies, MTRR AA genotype is a genetic determinant of moderate hyperhomocysteinemia associated with CAD in a French population without vitamin fortification.

Levocarnitine administration in multiple sclerosis patients with immunosuppressive therapy-induced fatigue

Nutritional factors and comedications are among the postulated causes of fatigue, a highly prevalent symptom in the multiple sclerosis (MS) population, with serious impact on patients’ quality of life. Deficiency of carnitine may play a role by reducing energy production through fatty acid oxidation and numerous MS therapies can induce fatigue syndrome. The aim of this prospective open-labelled study was to collect and study serum carnitine levels in MS patients with and without disease-modifying treatment-induced fatigue syndrome. We investigated whether restoration of the carnitine pool might improve treatment-induced fatigue in MS patients. In our study, there was no statistical difference in fatigue frequency between treated and untreated patients ( P=0.5). Matched to age, gender and treatments, carnitine levels were lower for MS treated patients compared to untreated MS patients ( P<0.05) or controls ( P<0.001). Consecutive patients with low plasma carnitine levels who experienced fatigue were substituted. Treatment consisted of oral levocarnitine, 3-6 g daily. All patients achieved normal plasma carnitine levels. For 63% of patients treated with immunosuppressive or immunomodulatory therapies, oral levocarnitine adjunction decreased fatigue intensity, especially in patients treated with cyclophosphamide and interferon beta.

Assessment of Folate Status: Measurement of Homocysteine versus Vitamin B12 and Folate

This study was based on 63 subjects (mean age 50 ± 9) including 41 patients with clinical and objective investigational evidence of vascular disease (age 30-66 years) and 22 control subjects (age 26-54 years). Dietary intake of folate was estimated from a food questionnaire of folate (Q.folate). There was no statistically significant difference between controls and patients for dietary folate. Also the plasma folate level did did noly slightly differ between the controls and patients (6.68 ± 2.52 ng/mL versus 5.62 +4.16 ng/mL, not significant). Patients had higher average homocysteine concentrations than control subjects (12.93 ± 8.79 vs 9.07 ± 3.08 μmol/l, p<0.05). A significant relationship was observed in controls between plasma folate concentrations and the homocysteine levels (rs = - 0.538; p<0.01), and the folate questionnaire (rs = 0.697; p<0.001). We found in controls significant positive correlation between vitamin B12 and vitamin B6 (rs = 0.475, p<0.05). By contrast, no association v/as found in patients between folate and homocysteine concentrations and the dietary nutrient intake of folate. On the other hand vitamin B12 is inversely associated with homocysteine (rs = -0.333, p<0.05). These data provide further evidence that plasma homocysteine is an independent risk factor for myocardial infraction. Homocysteine is a valuable functional index of micronutrient status and intakes for people, which can assist the development of the public health. In our population, folate was the most important determinant of plasma homocysteine, even in subjects with apparently adequate nutritional status of this vitamin.

Plasma Total Homocysteine, Folate, and Vitamin B12 Status and Hospitalizations for Cardiovascular Disease

Elevated plasma total homocysteine (tHcy) is an independent risk factor for cardiovascular disease (CVD). Also known is that plasma folate and vitamin B12 influence homocysteine metabolism as cosubstrate and cofactor, respectively. This population-based study was conducted to evaluate the plasma concentrations of tHcy, folate, and vitamin B12 in 54 older patients aged ≥51 years (40 males; 14 females) of Nice hospital cardiology service. After excluding cases with a serum creatinine >120 mmol/L, we established the test properties of a plasma tHcy concentration <15 μmol/L (Group 1) or ≥15 μmol/L (Group 2). In the population aged ≥51 years, plasma tHcy was higher in women (18.0 μmol/L) than in men (15.5 μmol/L; not significant), conversely, serum vitamin B12 was higher in men (376.9 pg/ml) than in women (340.7 pg/ml; not significant). Average plasma tHcy was 11.5 μmol/L in Group 1 and 21.6 μmol/L in Group 2. Vice versa, serum vitamin B12 was higher in Group 1 (419.5 pg/ml) than in Group 2 (307.2 pg/ml) (p <0.05). Correlation analysis (Pearson's r) in the total study population (20-84 years) indicated an inverse correlation between serum folate and age (r = -0.231, p <0.05). In the subjects, aged ≥51 years, there was a significant negative correlation between age and tHcy levels (r = -0.283, p <0.05) and serum vitamin B12 concentrations (r = -0.326, p <0.01) but not with serum folate. However, in subjects with tHcy <15 μmol/L, a significant inverse correlation existed between plasma tHcy and serum folate (r = -0.455; p <0.05). In conclusion, these results highlight the relevance of the vitamin status and particularly of folate levels in the modulation of fasting tHcy levels in the patients with clinical hyperhomocysteinemia, defined as plasma tHcy >15 μmol/L.

Nutritional and genetic determinants of vitamin B and homocysteine metabolisms in neural tube defects: a multicenter case-control study

Neural tube defects (NTDs) are severe congenital malformations due to failure of neural tube formation in early pregnancy. The proof that folic acid prevents NTDs raises the question of whether other parts of homocysteine (Hcy) metabolism may affect rates of NTDs. This French case-control study covered: 77 women aged 17-42 years sampled prior to elective abortion for a severe NTDs (cases) and 61 women aged 20-43 years with a normal pregnancy. Plasma and erythrocyte folate, plasma B6, B12 and Hcy were tested as five polymorphisms MTHFR 677 C --> T, MTHFR 1298 A --> C, MTR 2756 A --> G, MTTR 66 A --> G and TCN2 776 C --> G. Cases had significantly lower erythrocyte folate, plasma folate, B12 and B6 concentrations than the controls, and higher Hcy concentration. The odds ratio was 2.15 (95% CI: 1.00-4.59) for women with the MTRR 66 A --> G allele and it was decreased for mothers carrying the MTHFR 1298 A --> C allele. In multivariate analysis, only the erythrocyte folate concentration (P = 0.005) and plasma B6 concentration (P = 0.020) were predictors. Red cell folate is the main determinant of NTDs in France. Folic acid supplement or flour fortification would prevent most cases. Increased consumption of vitamins B12 and B6 could contribute to the prevention of NTDs. Genetic polymorphisms played only a small role. Until folic acid fortification becomes mandatory, all women of reproductive age should consume folic acid in a multivitamin that also contains B12 and B6.

Plasma vitamin values and antiepileptic therapy: case reports of pregnancy outcomes affected by a neural tube defect

BACKGROUND

Folic acid supplementation reduces the occurrence of neural tube defects (NTDs); however, it is not clear whether it protects against teratogenic effects of antiepileptic drugs.

METHODS

We report the cases of four pregnant women receiving valproic acid therapy, who all had NTD-affected offspring, despite periconceptional 5 mg/day of folic acid supplementation (cases), and investigated homocysteine metabolism, linked with folate metabolism. Their plasma homocysteine, folates, and vitamin B6 and B12 results were compared with values of two other women, who were also receiving valproic acid and folic acid complement, but who had normal pregnancies (valproic acid controls), and values of 40 pregnant women who had normal pregnancies and were not receiving any therapy (controls without therapy). Because of the possible existence of a genetic susceptibility, polymorphisms in homocysteine metabolism were sought.

RESULTS

Two cases showed a decreased phosphopyridoxal level, compared with levels in the controls not receiving therapy. The genotype TT (C677T) is an NTD genetic susceptibility, but it was observed in only one valproic acid control. Various polymorphisms were observed in the cases, but were also common in the controls. Several studies have reported that valproic acid therapy lowers vitamin B6 levels. Our case with the greatest decrease in plasma phosphopyridoxal, who was taking periconceptional folic acid plus pyridoxine therapy, had a normal second pregnancy outcome.

CONCLUSIONS

In addition to folates, other vitamins, such as vitamin B6, may have played a role in NTDs in our patients taking an antiepileptic drug.

Homocystéinémie et facteurs de thrombophilie dans des accidents de décompression immérités chez des plongeurs

INTRODUCTION

Decompression sickness with cerebral ischemic lesions occurs even in divers who have not committed any technical error. This study sought to determine whether an acquired or inborn thrombophilic factor might be involved.

METHODS

44 divers with ischemic medullar lesions (36 men, 8 women, mean age 39.9+/-4.7 yr) were compared with 44 controls (34 men, 10 women, mean age 38.2+/-5.1 yr). Coagulation screening included proteins S, C, and thrombin III and Factor VIII assays and circulating antibodies, Factor V Leiden, and mutation G20210A in Factor II gene research. Total plasma homocysteine (Hcy), an atherosclerosis factor (assayed by FPIA), folate and vitamin B12, (by microbiology), the cofactors of its metabolism, were assayed, and subjects were genotyped for mutation C677T on the MTHFR gene.

RESULTS

Coagulation screening--protein C, protein S, or antithrombin III deficit or mutation G20210A--was negative in all divers. 3/44 divers were heterozygous for Factor V Leiden, 1/44 had IgG antiphospholipid antibodies (9p.cent). While not found in controls, these percentages were not greater than those reported in the general population. 3/44 divers had elevated Factor VIII levels, but repeat assays on Day 2 were much lower. 11/44 divers had a moderate increase in Hcy value (20p.cent): in 7 divers, Hcy values were>15 micromol/L, and in 4 others>12, vs. 2.3p.cent of the controls; 2/11 had normal vitamin levels and 11 divers had folate or vitamin B12 deficiency or both, vs 2.3p.cent controls with a vitamin B12 deficit (percentage significantly different). 7/26 divers were homozygous for the C677T mutation, i.e. 27p.cent vs 12p.cent of 98 healthy controls (laboratory technicians).

CONCLUSIONS

A high percentage of unexplained diving accident victims had moderate HHC, a folate or vitamin B12 deficiency or both, that are easy to detect, plus a genetic predisposition to HHC or to coagulation abnormality. Easy-to-perform homocysteine, vitamin B12, and folate assays might prove helpful for primary prevention of diving accidents.

Antiepileptic drugs: a case report in a pregnancy with a neural tube defect

While receiving lamotrigine, a patient pregnant with triplets suffered a double fetal neural tube defect. Plasma homocysteine, folate, vitamins B12 and B6 (pyridoxal phosphate), and red cell folate levels were measured in samples while she was receiving folic acid therapy for 1 month during the second trimester of pregnancy. Some mutations were sought, involved in homocysteine metabolism and linked with the folate metabolism. Her results were compared with those of a pregnant woman with normal triplets and with those of 58 pregnant women, with a normal pregnancy. Results indicated a decrease in vitamin B12 and B6 values in plasma in the patient, and a genotype AG (polymorphism A66G) was observed, but was not found in the pregnant woman with normal triplets. Even if lamotrigine therapy is not known to be associated with significant changes in red cells or in serum folate, periconceptional folic acid supplementation is counseled for women, along with periconceptional B12 and B6 vitamin supplementation when their plasma values are decreased.

[Thrombophilic factors in divers with undeserved decompression sickness]

In divers with a vascular disease in decompression sickness, who have not committed any technical error, thrombophilic risk factors were sought. Six cases of confirmed divers, without diving technical error, were investigated. Thrombophilic screening included proteins C, S, antithrombin III, and factor VIII assays, and circulating antibodies, Factor V Leiden, and mutation G20210A mutation in Factor II gene research. Total plasma homocysteine (Hcy), an atherosclerosis factor, even when slightly increased, nutitional factors: folate and vitamins B12 and B6, the cofactors of its metabolism, and inversely correlated with Hcy values, were assayed, and subjects were genotyped for mutation C677T in the MTHFR gene.

RESULTS

In five divers, Hcy values were moderately increased, and in all the six, folate and/or B12 values were decreased. Three of them showed a genotype TT (mutation C677T), two, the genotype CT, and the sixth, an heterozygous Factor V Leiden. In these divers, a predisposition for vascular diseases, was detected, which was partially curable.

The number of consultant clinical chemists in the 15-nation European Union

The number of consultant clinical chemists (NCCC) in the 15-nation European Union (EU) (Austria, Belgium, Denmark, Finland, France, Germany, Greece, Ireland, Italy, Luxembourg, The Netherlands, Portugal, Spain, Sweden, United Kingdom) has been ascertained. These data were analysed in relation to several established national parameters, including demographics, gross domestic product (GDP), cost of healthcare, cost of in vitro diagnostic (IVD) testing and the number of physicians and pharmacists. Large differences in the population-corrected costs of IVD testing (range approximately 2.4-fold) and NCCC (range approximately 30-fold) were observed between the countries, which could not be satisfactorily explained by any of the parameters assessed. The differences in IVD testing and NCCC might reflect different practices in laboratory medicine across the EU, but could not be estimated independently. In recognition of the different scope of laboratory medicine practised under the title of clinical chemistry, a simple staffing model was derived in an attempt to give a better estimate of the appropriate number of consultant laboratory medicine specialists. This model allocated a fixed number of laboratory specialists per million inhabitants for the five disciplines: clinical chemistry, 10; haematology, 10; serology, 7.5; microbiology, 12.5; and blood banking, 2. The staffing model also allowed for the contribution of the primary care sector by including one full-time consultant laboratory medicine specialist for each small private laboratory and two extra consultant laboratory specialists per million inhabitants where there are not large numbers of private laboratories. Application of the model to the available data helped to reduce the variation observed in the primary analysis of NCCC (range approximately 9-fold) but still revealed important differences between countries. These differences could arise from the poor quality of published data as much as from true differences in laboratory medicine practice. We conclude that a more sophisticated analysis of laboratory practice and of all professionals working in laboratory medicine disciplines would be required before any conclusions could be drawn about relative staffing, efficiency or cost effectiveness. The staffing model derived is a first step towards objective estimation of the number of consultant laboratory specialists in the EU.

Influence of Meal on Plasma Folate and Vitamin Β12, by Three Methods - and on Vitamin B6, Homocysteine and Red Blood Cell Folate

Vitamins are brought by meals. Some of them are cofactors in homocysteine metabolism, and, if plasma homocysteine values are not known to have a circadian rhythm, little is known about meal influence on blood folate, and vitamins Β12 and B6. The aim of this study is to analyze the effect of breakfast and lunch on plasma folate, vitamins B12 and B6. homocysteine and red cell folate (RCF) in 13 subjects; and, in 6 of them, to compare plasma folate and vitamin Β12 values with three analytical methods. In the 13 subjects, folate, vitamins B12 and B6 and RCF were analyzed by RIA, homocysteine by fluorescence polarization immunoassay and vitamin B6 by HPLC. In 6 of the subjects, additionally, plasma folate and vitamin Β12 were analyzed by microbiology and by enzymoimmunoassay (EIA). Mean plasma folate levels at 11AM. 2PM, and 4PM were not significantly different, compared with 9AM mean values, independent of the method, while, when analyzed by microbiology, mean vitamin B12 concentrations decreased significantly (-12%), but not by RIA or by microbiology. Plasma folate concentrations, obtained by the different methods, and RCF concentrations were correlated, as for vitamin B12 concentrations. But, when analyzed by EIA. vitamin B12 v alues were higher than by the two other methods. We conclude that plasma folate levels were constant at the different sampling hours, while vitamin B12 levels were decreased at 11AM, 2PM and 4PM, when compared with the fasting concentrations, and when assayed by microbiology. No difference was seen by RIA or by EIA. The evaluation of clinical data is not easy, due to the lack of a standardized analytical method, and international standards are needed.

Effects of long duration exercise on cognitive function, blood glucose, and counterregulatory hormones in male cyclists

Electrocortical effects of long duration exercise on cognitive function were investigated by analyzing P300 amplitude and latency changes during a 3-h cycling exercise. P300 components were measured in 12 well-trained cyclists and blood glucose, cortisol, insulin, glycerol, and free fatty acids (FFAs) epinephrine and norepinephrine were analyzed. Results indicated that P300 components were affected by exercise with a temporary increase in amplitude between the 1st and the 2nd hour and an increase in latency after 2 h of exercise concomitant with some hormonal changes, including an increase in cortisol and epinephrine and a decrease in blood glucose. These findings suggest a combined effect of arousal and central fatigue on electrocortical indices of cognitive function during acute physical exercise.

[Neural tube defects and vitamin B12: a report of three cases]

Periconceptional folic acid supplementation reduces the frequency of embryological neural tube defects (NTD). This fact led the USA to fortify grain products with folic acid (140 microg/100 g) starting in January 1998, with a resultant decrease in the incidence of NTD. Folate deficiency is thus confirmed to be a risk factor for NTD. However, in a prospective study, we investigated three women who conceived a fetus with NTD; no folate deficiency was found in these women but all three had decreased vitamin B12 levels (cobalamin), which can be an other risk factor. Samples were obtained from two women in Algeria, 2 days after interruption of pregnancy, and from a vegetarian woman, in France, one month after interruption of pregnancy. Red cell folate and plasma folate, vitamin B12, B6 and homocysteine were assayed and the mutations C677T (in metylenetetrahydrofolate reductase gene), A2756G (in methionine synthase gene) and A66G (in methionine synthase reductase gene) were sought. Elevated plasma folate levels were found in both Algerian women. Vitamin B 12 levels in all three women were decreased or in the lowest quartile of normal values. One woman presented simultaneously a vitamin B 12 deficiency, and heterozygous mutations in the three genes. The second woman presented a A66G homozygous mutation and the third heterozygous C677T and A66G mutations. Acquired and inborn factors are intricated in some cases of pregnancies with NTD and B 12 deficiency can be responsible for intracellular folate cycle failure. It would therefore be advisable to consider fortifying grain products with both folic acid and vitamin B12.

Clinical B12 deficiency in one case of recurrent spontaneous pregnancy loss

Moderate hyperhomocysteinaemia (HHcy) and the homozygous mutation C677T in the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene are associated with increased risk of recurrent pregnancy loss. This HHcy is currently reported as a consequence of folate rather than of vitamin B12-deficient status. We describe one case of recurrent early pregnancy loss with HHcy caused by B12 deficiency. A 38-year old woman had four episodes of early spontaneous pregnancy loss. Biological data: no haemostasis disorders, HHcy (25.9 micromol/l), normal folate (5 ng/ml), B12 deficiency (< 150 pg/ml) and the MTHFR C677T homozygote genotype. A bone marrow biopsy gave evidence of moderate megaloblastosis. Parenteral B12 therapy led to normal homocysteine level within 2 months and to a successful pregnancy. In conclusion, vitamin B12 deficiency is one of the causes of recurrent pregnancy loss associated with HHcy, and serum B12 should be measured systematically in this circumstance.

Genetic Determinants of Folate and Vitamin B12 Metabolism: A Common Pathway in Neural Tube Defect and Down Syndrome?

One-carbon metabolism is under the influence of folate, vitamin B12 and genetic polymorphisms of methylenetetrahydrofolate reductase (MTHFR 677 C --> T and 1298 A --> C), of methionine synthase (MTR 2756 C --> G), methionine synthase reductase (MTRR 66 A --> G) and transcobalamin (TCN 776 C --> G). The pathogenesis of neural tube defect (NTD) may be related to this metabolism. The influence of the MTHFR 677 C --> T polymorphism reported in The Netherlands and Ireland can be questioned in southern Italy, France and Great Britain. MTRR, combined with a low level of vitamin B12, increases the risk of NTD and of having a child with NTD in Canada, while TCN 776 GG and MTRR 66 GG mutated genotypes associated with the MTHFR 677 CC wild-type are predictors of NTD cases in Sicily. Down syndrome (DS) is due to a failure of normal chromosomal segregation during meiosis, possibly related to one-carbon metabolism. MTHFR 677 C --> T and MTRR 66 A --> G polymorphisms are associated with a greater risk of having a child with DS in North America, Ireland and The Netherlands. In contrast, MTHFR 677 C --> T has no influence on DS risk in France and Sicily, while homocysteine and MTR 2756 AG/GG genotypes are predictors of DS risk in Sicily. In conclusion, NTD and DS are influenced by the same genetic determinants of one-carbon metabolism. The distinct data produced in different geographical areas may be explained by differences in the nutritional environment and genetic characteristics of the populations.

Methods for homocysteine analysis and biological relevance of the results

It is now widely accepted that increased total plasma homocysteine (tHcy) is a risk factor for cardiovascular disease. Hyperhomocysteinemia can be caused by impaired enzyme function as a result of genetic mutation or vitamin B (B(2), B(6), B(9), B(12)) deficiency. A lot of methods are now available for tHcy determination. High-pressure liquid chromatography (HPLC) with fluorescence detection are at present the most widely used methods but immunoassays, easier to use, begin to supplant in-house laboratory methods. In order to help with the choice of a main relevant homocysteine analytical method, the characteristics, performances and limits of the main current methods are reviewed. One major drawback among all these available methods is the transferability which is not clearly established to date. The impact of both inter-method and inter-laboratory variations on the interpretation of the tHcy results are discussed.

[Clinical relevance of homocysteine monitoring in the diabetic patient]

Accelerated atherosclerosis is common in diabetes mellitus, although its extent is not always related to its strong association with classical cardiovascular risk factors. Diabetic patients, especially with type 2 diabetes, are prone to cardiovascular disease which is the leading cause of death in this population. Recent clinical studies among general population have shown that an even mild increase of homocysteinemia play an important role in the progression of atherosclerosis, either in coronary or peripheral arteries. An increasing amount of in vitro data is providing evidence that excess of homocysteine has a toxic effect on the arterial wall. This aminoacid thus appears to be not only a risk marker but also an emerging cardiovascular risk factor. The measurement of plasma homocysteine contributes to the identification, among the diabetic population, of patients at high cardio-vascular risk, with the aim of improving their global management. Moreover the addition of group B vitamins provides an easy and low-cost treatment to lower hyperhomocysteinemia.

[Comparison of plasma total homocysteine determinations in 9 French hospital laboratories by using 6 different methods]

A lot of methods are now available for total plasma homocysteine (tHcy) determination. Commercial kits using immunoassay, easier to use, begin to supplant in-house laboratory methods. Our aim is to evaluate the interchangeability of tHcy measurements in 9 French hospital laboratories. Six different method types were used: 2 gas chromatography-mass spectrometry (GC-MS), 2 HPLC with fluorescence detection subdivided in one in-house method and one commercial kit (Bio-Rad ), 3 fluorescence polarization immunoassays (FPIA), 1 enzyme immunoassay, 1 amino acid analyser, 1 capillary electrophoresis coupled with laser-induced fluorescence detection (EC-LIF). Each laboratory analysed 41 patient's plasma samples in which 8 samples contained added homocystine. Results were analysed for imprecision, recovery, and methodological differences. The mean among-laboratory imprecision (CV) ranged from 12.5 to 18% in function of plasma sample type and was identical to the mean among-method variation. In terms of recovery, we obtained underestimated results with immunoassays. The bias relative to the GC-MS method was less than 12.5% except for two laboratories, one using FPIA assay and the other EC-LIF. In conclusion, the interchangeability of tHcy results between laboratories is not satisfactory and does not allow us to evaluate cardiovascular risk linked to moderate increases of tHcy.

[Biochemical diagnosis of pheochromocytoma and neuroblastomas]

Pheochromocytoma and neuroblastoma are distinct tumours, but their biological diagnosis is based on secretion increase of one or several catecholamines. Assays have to be very sensible and specific for an early diagnosis. 24 hours urinary catecholamines and metabolites are currently measured, but technical improvements permit plasma metanephrine assay, an excellent indicator of pheochromocytoma. HPLC coupled to electrochemical detection represents the most efficient methodology. After a review of urinary and plasma assay methods, the authors show usual values of catecholamines, metanephrines, HVA and VMA, according to ages, and give examples of results encountered in classical or not tumours and in falsely positive cases. Urinary metanephrine assay is the most sensible and specific in biological diagnosis of pheochromocytoma, while catecholamines and VMA assays lack of sensibility. Results have to be given by 24 hours and by creatinine ratio. Metanephrine assay can be performed also in plasma and exhibits the same interest. However, in urine as in plasma, in case of renal failure, results cannot be interpreted. Neuroblastoma biological diagnosis is based classically on HVA, VMA, and dopamine assays, nowadays only in 24 hours urine (or in urinary micturition for screening), and results are also expressed as creatinine ratio. But even if several assays are advisable, 5% of the neuroblastoma cases do not produce increased catecholamine values. In some cases, metanephrine assay could be of interest. After the age of 12 months, clinical expression of neuroblastoma is dramatic in 70% of cases. So, a biological screening has been experimented in several countries including France. A French translation of the consensus conference report (1998) is appended, which shows the complexity of neuroblastoma screening. Now, there is no evidence that early tumour detection by screening lessens the mortality rate, but a weak benefit is not excluded.

Effects of strength exercise and training on the natural killer cell counts in elderly humans

BACKGROUND

To investigate the effects of strength exercise and training on the natural killer cell counts in elderly humans.

METHODS

The study examined strength exercise-induced changes in the number of NK cells and changes in stress hormones in 16 sedentary elderly subjects before and after a 8-week strength training intervention. Blood samples were obtained before, immediately and 6 hours after a standardized strength test. Blood samples were also obtained from ten sedentary young subjects, under the same conditions and from ten resting elderly subjects serving as time controls.

RESULTS

Prior to training, older adults immediately decreased (from 165.4+/-19.5 microL to 110.6+/-14.3 microL; mean+/-SEM) their NK cell count in response to the standardized strength test, whereas young controls increased their count (from 157.6+/-28.8 microL(-1) to 241.4+/-39.8 microL(-1)). After strength training, the same old subjects slightly increased (from 159+/-19.8 microL(-1) to 166.6+/-19.7 microL(-1)) their NK cell counts in response to the standardized strength test. In elderly subjects, no increase in stress hormone was observed following the strength test either before or after the strength training programme.

CONCLUSIONS

The results suggest that in sedentary older adults, unlike young subjects, strength exercises can induce a transient decrease in NK cell count which can be cancelled by a short-term strength conditioning. Therefore, caution should be taken regarding immunocompetence of older adults when initiating a rehabilitation programme based on strength.

[Acute polyradiculoneuritis and dysautonomia: contribution of assaying catecholamines and their methoxylated metabolites]

Guillain-Barré syndrome is an acute demyelinating polyradiculoneuritis usually evolving with rapid, functional recovery. In severely paralysed patients, cranial nerve palsy and autonomic nervous system dysfunctions are common. Lesions of the spinal roots predominate but segmentary demyelination of peripheral nervous system reflects various clinical subtypes. Twelve patients (42,8 p. cent) had clinical dysautonomia. Ten had an increase of urinary methoxylated metabolites. Patients exempt of dysautonomia had normal biological parameters. The elevated level of urinary methoxylated metabolites is statistically correlated to clinical dysautonomia and can be used as a biological marker to monitoring demyelinating polyradiculoneuritis.

[Plasma homocysteine measurement: a study of pre-analytical variation factors for conditions for total plasma homocysteine concentration]

An increase in homocysteine, a sulphur amino acid, is nowdays considered as a risk factor for cardiovascular diseases, and is independent of other risk factors. Reference range for total plasma homocysteine level in adults is usually 5-15 mmol/l. Hyperhomocysteinemia is defined as a fasting total plasma homocysteine level > 15 mmol/l. There may be also graded increased risks for subjects with homocysteinemia from 10 to 15 mmol/l. However, no threshold has been defined, partly because of the lack of standardization in pre-analytical and analytical steps. The aim of the present work was to evaluate three pre-analytical parameters on plasma homocysteine levels: i) the influence of three anticoagulants (EDTA, sodium citrate and lithium heparin); ii) the delay period of blood sample on ice before centrifugation; and iii) the advantages of strong acidic citrate at room temperature. The mean concentrations of total plasma homocysteine were different in function of the anticoagulant. These differences (EDTA minus lithium heparin or EDTA minus sodium citrate) were less than 10% however the used methods and could explain the good correlation between the results. However we recommend to keep the anticoagulant constant in the same study. When EDTA blood samples were immediately put on crushed ice, the maximum delay period before centrifugation could reach 4 hours. If ice is unavailable, strong acidic citrate at room temperature is a good alternative until for 4 hours.

Plasma total homocysteine and other thiols analyzed by capillary electrophoresis/laser-induced fluorescence detection: comparison with two other methods

We present a new analytical method for thiol quantification in plasma, based on the use of capillary electrophoresis (CE) and laser-induced fluorescence (LIF) to analyze 6-iodoacetamidofluorescein derivatives. Quantitative results of homocysteine, glutathione, cysteinylglycine, and cystationine are presented. A comparison of the quantitation of homocysteine in plasma, using high performance liquid chromatography/fluorescence detection and fluorescence polarization immunoassay is proposed. The results indicate that these techniques for plasma total homocysteine (tHcy) determination can be used interchangeably. The major advantage of CE-LIF is that it can quantitate the thiols in one run while keeping the price of consumables reasonable.

Fasting, postprandial, and post-methionine-load homocysteinaemia and methylenetetrahydrofolate reductase polymorphism in vascular disease

Hyperhomocysteinaemia is an independent risk factor for cardiovascular disease. The C677T mutation of the methylenetetrahydrofolate reductase (MTHFR) is a common genetic cause of increased homocysteine (HCY) levels. Post-methionine-load HCY concentrations allow identification of certain cases of hyperhomocysteinaemia not demonstrated by fasting levels. This study investigated the relationship between MTHFR polymorphism and (1) fasting HCY levels (77 patients); (2) post-methionine HCY levels (54 patients); and (3) postprandial HCY concentrations (36 patients) in cardiovascular disease. As expected, mean fasting HCY value was higher in the +/+ patients. Moreover, patients who were homozygous for the mutation exhibited significantly increased mean post-methionine-load HCY; in contrast, literature results are conflicting. Mean postprandial HCY, which is not known to be increased in controls, was also increased in the (+/+) patients, although the difference did not reach statistical significance, probably owing to the small size of the sample. MTFHR polymorphism is known to be aggravated by a drop in circulating folate. Additional risk factors may be more prevalent in patients with cardiovascular disease.

Effects of a short-term strength training programme on lymphocyte subsets at rest in elderly humans

The effects of a short-term strength training programme on resting lymphocyte subsets and stress hormone concentrations were analysed in 32 elderly sedentary subjects. Out of these 32 subjects, 8 women and 8 men [mean age 70.1 (SEM 1.0) years] were randomly assigned to a 8-week strength training programme which consisted of three sets of eight repetitions at 80% of one repetition maximum, for leg press, bilateral leg extension and seated chest press, 3 days a week. The remaining 8 women and 8 men [mean age 70.5 (SEM 0.9) years] served as controls. Absolute counts of lymphocyte subsets (CD20+, CD3+, CD3+CD4+, CD3+CD8+, CD3-CD56+CD16+) were measured with a new technique combining fluorescent microspheres and flow cytometry. In the trained subjects, substantial increases in strength took place in one repetition maximum during the 8-week training period for leg press [from means of 20.7 (SEM 1.0) to 23.6 (SEM 1.0) N x kg(-1) LBM (lean body mass)], chest press [from means of 5.4 (SEM 0.3) to 6.2 (SEM 0.3) N x kg(-1) LBM] and bilateral leg extension [from means of 6.3 (SEM 0.2) to 7.4 (SEM 0.3) N x kg(-1) LBM] movements. Baseline cortisol concentration (P < 0.01), CD20+ cell count (P < 0.05), CD3+ cell count (P < 0.05), and CD4+ cell count (P < 0.01) decreased in both groups secondary to circannual variations between winter and summer. No significant effect of strength training on resting adrenaline, noradrenaline and cortisol concentrations or distributions of lymphocyte subsets at rest was observed. The main finding of this study was to demonstrate that 8-week is too short a duration for a strength training programme to modify counts of lymphocyte subsets at rest in elderly sedentary adults.

Whole blood serotonin content, tryptophan concentrations, and impulsivity in anorexia nervosa

BACKGROUND

We hypothesized that anorectics with or without bulimic features would differ on impulsivity and indices of central serotoninergic function (high impulsivity being correlated with reduced serotoninergic function).

METHODS

For all patients impulsivity rating scales and questionnaires detailing severity of eating disorder were assessed, and whole blood serotonin concentration (5-HT), free and total tryptophan (TT) concentrations, and large neutral amino acids (LNAA) were assayed.

RESULTS

Nineteen patients with anorexia nervosa were included, 10 presented associated bulimic features and nine did not. Twelve healthy matched controls were also included. Our hypothesis was not verified. However, tryptophan concentration and the ratio of tryptophan concentration to LNAA allow us to separate controls from anorectics, whereas 5-HT concentration does not. Two significant and positive correlations were found: between impulsivity and anxiety in the total anorectic population, and between anxiety and serotonin in the impulsive group.

CONCLUSIONS

All measured peripheral biologic indices except 5-HT concentration may be of interest in this pathology. Impulsivity and anxiety seem to be two personality components involved in anorexia nervosa. This study lead us to the necessity of redefining impulsivity in anorexia nervosa.

[Blood levels of homocysteine in patients under 55 years of age with acute coronary insufficiency]

OBJECTIVES

High blood levels of homocysteine have been recently described as a risk factor for thromboembolic events and early development of atherosclerosis. The aim of this work was to study homocysteine blood levels in patients under 55 years of age with acute coronary artery disease.

PATIENTS AND METHODS

The study included 110 patients (98 men, 12 women) with poorly controlled angina pectoris (n = 35) or in the acute phase of myocardial infarction (n = 65). Homocysteine was assayed by liquid chromatography in all patients on the day of the acute episode and 24 hours later. Homocysteine levels were also determined in 40 controls under 55 years of age with no history of coronary artery disease.

RESULTS

Blood level of homocysteine was 10.6 +/- 6.2 mumol/l in the patients and 7.7 +/- 2.5 mumol/l in the controls (p < 0.01). The difference was greater in the 30-40 year age rang with 14.4 +/- 2 mumol/l in patients versus 6.4 +/- 1.5 mumol/l in controls (p < 0.001). The assays were reproducible at 24 hours (difference less than 10%). The levels were significantly higher in patients with several diseased arteries than those with single-artery disease. The difference between patients and controls was especially remarkable for non-smokers and those with high cholesterol levels.

CONCLUSION

Hyperhomocysteinemia would be a factor favoring early development of coronary atherosclerosis.

[Cerebral vascular complication of hyperhomocysteinemia. Controlling thromboembolic complications with folates]

BACKGROUND

Young patients who experience cardiovascular events may have raised levels of homocysteine. There may be several causes for this hyperhomocysteinemia.

CASE REPORT

Cerebrovascular disease occurred in a 40-year-old female smoker with hyperhomocysteinemia. This patient subsequently had several episodes of thromboembolism involving the brain and lower limb arteries. Prothrombin concentration was difficult to control with antivitamin K anticoagulants. Investigations to identify a genetic cause of hyperhomocysteinemia revealed that she was homozygous for the C677T mutation on the methylenetetrahydrofolate reductase gene. There was no G1691A mutation of the factor V gene, a risk factor for familial thrombosis. Supplementation with folic acid successfully halted episodes of thromboembolism (follow-up 2 years) and prothrombin levels stabilized under treatment.

DISCUSSION

The C677T mutation, which is common in the general population (15.7%), cannot explain the effect of folate supplementation alone. Other mutations affecting homocysteine metabolism could have a potentializing effect on vascular events.

Total plasma homocysteine determination by liquid chromatography before and after methionine loading. Results in cerebrovascular disease

Elevated homocysteine (HCY) levels in tissues and blood are associated with premature occlusive diseases. A number of techniques have been developed to assay HCY, including high-performance liquid chromatography (HPLC) with fluorimetric or electrochemical detection, and radioenzymatic methods. The present study evaluated the adaptation of a liquid chromatographic, ion-exchange technique with postcolumn derivatization using ninhydrin. Fasting and moreover post-methionine load total plasma HCY were assayed in 50 patients three months after a stroke and in 20 age-matched controls. Ion-exchange liquid chromatography was performed on an amino acid analyzer using a modified procedure to improve methionine and HCY separation. HCY values in the fasting state were moderately but significantly increased (P<0.05) in the patients compared to the controls: 10.5+/-3.4 versus 9.3+/-2.3 micromol/l. The difference between the two groups was amplified in post-load HCY results, which were significantly increased (P<0.05) in the patients: 41.6+/-17.8 versus 29.2+/-5.5 micromol/l in controls. The relationship between cerebrovascular disease and impaired HCY metabolism has previously been emphasized by other investigators. Our findings suggest that certain inherited and/or acquired HCY disorders observed in the fasting state (14%) and especially in post-methionine load conditions (32%) may occur during acute disease, and that total plasma HCY can be determined by ion-exchange chromatography even after oral methionine loading.

Increased urinary catecholamines in a hypertensive child with renal artery stenosis

We report a hypertensive child with renal artery stenosis who exhibited increased urinary excretion of norepinephrine (NE) and normetanephrine (NMN), while vanillylmandelic acid (VMA) excretion was within the normal range. The NMN values prompted us to investigate the patient for pheochromocytoma; for this purpose, NE was determined by plasma catecholamine assays in venous samples obtained by catheterization. The moderately increased NE levels could not be localized to any particular sampling site. Arteriography demonstrated right renal artery abnormalities. Following right nephrectomy with preservation of the right adrenal gland, arterial blood pressure returned to normal. The cause of increased NMN excretion without a concomitant rise in VMA during hypertension is discussed.

Homocysteine response to methionine challenge in four obligate heterozygotes for homocystinuria and relationship with cystathionine beta-synthase mutations

Fasting and post-methionine load plasma total homocysteine concentrations were investigated in the parents of two homocystinuric patients. Three genetic mutations in the cystathionine beta-synthase gene were found. In the patient of family 1, a frequent Caucasian mutation. T833C, was found on one allele, while the mutation on the other allele has not yet been defined. In the patient of family 2, a mutation C569T, recently described by Sperandeo and colleagues, was found on one allele, while a novel mutation, G346A, was characterized on the other allele. The frequent gene mutation T833C was detected in a heterozygous mother who, surprisingly, exhibited strictly normal fasting and post-methionine load homocysteinaemia. In contrast, in the other family, we found a novel mutation (G346A) in the mother located near Lys 119, the putative binding site of phosphopyridoxal phosphate. This mother exhibited increased fasting and post-methionine load homocysteinaemia. These observations could explain the conflicting results reported for vascular pathologies in parents of homocystinuric patients and direct the search for genetic mutations in these vascular pathologies.

Urinary excretion of methylated catecholamine metabolites in a child with neuroblastoma maturing into ganglioneuroma

Neuroblastomas are malignant tumors derived embryonically from the neural crest. Biological diagnosis relies on assay of urinary excretion of homovanillic acid (HVA), vanillylmandelic acid (VMA), and dopamine (DA). Spontaneous regression of these neoplasms has been reported by numerous investigators. The authors report the case of a child with neuroblastoma that illustrates the relationship between catecholamine metabolites and tumor maturation. At 1 month of age, this infant presented an adrenal neuroblastoma with multiple metastases (stage IV); the initial histological diagnosis based on examination of cutaneous metastases was neuroblastoma. At the age of 6 months, after chemotherapy, the primary tumor was resected; hepatic metastases were discovered at laparotomy. The histological diagnosis for all lesions was highly differentiated, mature ganglioneuroma-like tissue. The main biochemical abnormality at the time of diagnosis was an elevation in normetanephrine (NMN). HVA was only slightly increased but rose progressively during chemotherapy; it dropped back to normal levels after the sixth course. This case illustrates the potential benefits of separate assays of urinary methylated catecholamine metabolites for biochemical diagnosis and therapeutic management of neuroblastoma in addition to assays of HVA, VMA, and DA. Case findings suggest existence of a transformation process with maturation of the tumor involving enzymatic regulation and expression of MAO.

Plasma catecholamine assays: calibration with spiked plasma versus aqueous solutions

Both aqueous standards and plasmas spiked with standards are used for assays of plasma constituents. In a previous study, high-performance liquid chromatographic (HPLC) assays of plasma norepinephrine, epinephrine, and dopamine performed with spiked plasma reference solutions resulted in lower thresholds and thus gave higher concentrations. To verify the hypothesis that spiked catecholamines bind to plasma proteins (like physiological catecholamines) and thus escape extraction by alumina prior to HPLC, the recovery of standards in human albumin solution was compared with similar investigations using aqueous standards. Our findings confirm that (a) albumin is responsible to a great extent for the drop in recovery and (b) calibration by extraction of aqueous standards is preferable to calibration by spiked plasma for free catecholamine assays.

Stability of 3,4-dihydroxyphenylacetic acid in plasma extracts assayed by high-performance liquid chromatography with electrochemical detection

3,4-Dihydroxyphenylacetic acid (DOPAC) can be easily assayed by high-performance liquid chromatography (HPLC) with electrochemical detection at the same time as norepinephrine (NE), epinephrine (E), and dopamine (DA). The latter catecholamines are stable in perchloric acid extracts for over 6 h at 4 degrees C in the dark whereas DOPAC levels drop rapidly by more than 50% in 6 h at 4 degrees C in the dark. This study investigated the effects of reducing agents [ascorbic acid, dithiothreitol (DTT), reduced glutathione with or without a metal chelating agent (diethylenetriaminepentaacetic acid or ethylenediaminetetraacetic acid)] on DOPAC. Extracted with alumina using 0.65 mmol/1 DTT prior to HPLC and electrochemical detection, DOPAC remained stable in the perchloric acid extract for 2 h at 4 degrees C in the dark.

Abnormal alpha-aminoadipic acid excretion in a newborn with a defect in platelet aggregation and antenatal cerebral haemorrhage

alpha-Aminoadipic acid (alpha AA) is an intermediate in lysine metabolism. We report a new case with alpha AA excess in urine and plasma, without alpha-ketoadipic acid, in a full-term male child born to unrelated parents; he presented at 24h of life with seizures that failed to respond to phenobarbital, clonazepam, and Vigabatrin and death occurred on the 38th day of life. Brain imaging suggested antenatal haemorrhage. Small quantities of alpha AA were also detected in the blood and urine of both parents and a healthy brother, all three of whom exhibited the same defect in platelet aggregation as the deceased child. Both parents had decreased levels of plasma neopterin, a finding that might be related to the immunodeficiency described in other cases.

Type 1 diabetes mellitus and homocyst(e)ine

High Homocyst(e)ine levels (H) have been recently recognized as a risk factor for atherosclerosis. Patients with Diabetes Mellitus (DM) are prone to atherosclerosis. Therefore, this study was designed to search for the effect of DM on H and their relationship. Forty-one Type 1 diabetic subjects (DS, age 34.8 +/- 12 yr, DM duration: 10.7 +/- 11.1 yr) were compared to 40 age-matched control subject (CS, age 34.2 +/- 9.1 yr). H (measured by ion-exchange chromatography, units: mumol/l) and several parameters (creatininemia; triglycerides; total, HDL, LDL cholesterol; Lp(a); HbA1c; vitamins B9 and B12) were determined after an overnight fast. H were significantly (p = 0.0001) lower in DS (6.8 +/- 2.2) than in CS (9.5 +/- 2.9). This difference was still apparent in male and female subgroups compared to matched CS (p = 0.003 for each). No correlation was found between H and: lipids, vitamins, renal or retinal status. But H seemed to increase with age, especially in women (p = 0.03; r = 0.32). While there is, at this time, no explanation for the lower H observed in DS, it appears that H cannot directly account for accelerated atherosclerosis in DM. Nevertheless, it remains to be established if high, or even normal, H could identify a subgroup of DS at higher risk of precocious and severe atherosclerosis.