Nutritional epidemiology and thyroid hormone metabolism.

Severe iodine deficiency was the main cause of endemic goiter and cretinism. Most of the previously iodine-deficient areas are now supplemented, mainly with iodized salt. The geographical distribution of severe endemic areas has been progressively reduced, and at present, approximately 200 million people living in remote places are still at risk of severe iodine deficiency. International public health programs should be focused first on reaching these populations, and second on auditing and monitoring the operational work of supplementation programs. This second point is essential to prevent iodine-induced hyperthyroidism or interruptions of iodine supplement distribution, which could be catastrophic for the fetus and the young infant. Echography brings a complementary tool to clinical assessment of goiter by palpation. Inductively coupled plasma-mass spectrometry brings at least a definitive gold standard for iodine measurement and thyroid hormone measurement. Thiocyanate overload has been clearly documented as a goitrogen in Central Africa, and when associated with selenium deficiency, it may be included as risk factor for endemic myxedematous cretinism. Variable exposure to different environmental risk factors is likely the explanation of the variable distribution of two types of endemic cretinism (neurological and myxedematous), and the clinical overlap of the pathogeny of both syndromes is more important than previously described. It is possible that Kashin-Beck osteoarthropathy is another evanescent endemic disease that will disappear with the correction of iodine deficiency.SCOPUS: re.jinfo:eu-repo/semantics/publishe

La maladie de Kashin-Beck en Chine: une ostéochondrodysplasie liée à la nutrition et à l'environnement

info:eu-repo/semantics/publishe

La maladie de Kashin-Beck en Chine, une ostéoarthropathie déformante liée à la nutrition et à l'environnement

info:eu-repo/semantics/nonPublishe

Erythrocyte vitamin E is oxidized at a lower peroxide concentration in neonates than in adults

Erythrocytes of neonates and adults were incubated with increasing concentrations of H2O2 in the presence of a catalase inhibitor and in the absence of glucose; the pattern of oxidation of vitamin E was analyzed in relationship to that of glutathione, hemoglobin, and polyunsaturated fatty acids (PUFA), and in relationship to hemolysis. The changes of these various parameters were analyzed in function of H2O2 concentration and in relation to incubation time, and were compared in erythrocytes from neonates and adults. In the absence of H2O2, erythrocyte glutathione and tocopherol levels were similar in neonates and adults, despite fourfold lower serum vitamin E level in neonates; α-tocopherolquinone, methemoglobin, and malonyldialdehyde (MDA) were not detectable. At 0.375 mmol/L of H2O2, glutathione was completely oxidized. Erythrocyte α-tocopherol remained unchanged up to 0.75 mmol/L of H2O2, then decreased linearly, with increasing H2O2 concentrations to 10% of its initial value at 1.5 mmol/L of H2O2 in erythrocytes from neonates, whereas those from adults required 2.0 mmol/L of H2O2 (P < .05) for the same level of oxidation. The formation of α-tocopherolquinone appeared inversely related to the decrease of α-tocopherol. The incubation time did not influence the level of vitamin E oxidation. MDA was generated autocatalytically and resulted in hemolysis at 1.5 mmol/L of H2O2 in erythrocytes from neonates and at 3.5 mmol/L of H2O2 in erythrocytes from adults (P < .001). After four hours of incubation, MDA reached a plateau at a greater level (365 + 46 nmol/L) in cells of neonates than in those of adults (208 ± 37 nmol/L/mL) (P < .001). Hemogloblin was oxidized in the same pattern in erythrocytes of neonates and adults, and 90% of it was oxidized at 0.625 mmol/L of H2O2. In conclusion, in the experimental conditions used, oxidation of glutathione precedes that of vitamin E, and tocopherol is the last antioxidant to be consumed before the autocatalytic generation of MDA. Differences in the pattern of vitamin E oxidation, MDA generation, and hemolysis in erythrocytes from neonates and adults may be due to a lower erythrocyte vitamin E-PUFA ratio in neonates.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Better stability of total homocysteine measurement with sodium fluoride than with EDTA

The total homocysteine (tHcy) plasma concentration increases 10% per hour when whole blood is collected on ethylene diamine tetraacetate (EDTA) and stored at room temperature. The aim of this study was to investigate the stability of tHcy plasma concentration during 24 hours of storage at room temperature in two different collection tubes: EDTA and sodium fluoride (NaF). The evolution of tHcy plasma concentration was also compared in two different populations: healthy individuals (controls) and patients with end-stage renal failure, known to have increased plasma tHcy concentrations. Plasma was separated from erythrocytes at 0, 2, 6 and 24 hours, tHcy was measured with a competitive immunoassay on Immulite 2000® (Diagnostic Products Corporation). Plasma tHcy concentration started to rise significantly on EDTA after two hours of storage in patients and controls in comparison to baseline (defined as time: 0 hour). It remained stable on NaF during the first two hours and started to rise significantly after six hours of storage for both populations. In conclusion, NaF tubes should be preferred to EDTA tubes for tHcy determination in routine clinical chemistry laboratories.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Discordance between reptilase time measured by the Hook manual method and the optical method in patients with high fibrinogen level

SCOPUS: le.jinfo:eu-repo/semantics/publishe

Historical aspects of iodine deficiency control

In 1895, iodine was characterized as an essential element of thyroid tissue by Baumann. The efficacy of iodine to prevent goiter was demonstrated by Marine in Northern USA in 1916-1920. Severe endemic goiter and cretinism had been almost entirely eliminated from continental Western Europe and Northern America before the 1930's; however large populations elsewhere and even some places in Western Europe (Sicily) were still affected up to the 2000's. Public health consequences of iodine deficiency are not limited to endemic goiter and cretinism. Iodine deficiency disorders include also increased neonatal death rate and decreased intellectual development, although these consequences are not included in the current estimation of the Global Burden Disease related to iodine deficiency. Severe iodine deficiency as a public health problem is now largely under control worldwide, but can still affect isolated places, in hard-To-reach and/or politically neglected populations. We emphasize the importance of maintaining international cooperation efforts, in order to monitor iodine status where iodine deficiency is now adequately controlled, and identify at-risk population where it is not. The goal should be now global eradication of severe iodine deficiency. Commercial distribution of iodized salt remains the most appropriate strategy. A randomized clinical trial in New Guinea clearly showed in the 1970's that correcting severe iodine deficiency early in pregnancy prevents endemic neurological cretinism. This supports the essential role of thyroid hormones of maternal origin on the normal fetal development, during the first trimester of pregnancy (i.e. when fetal thyroid is still not functional). A randomized clinical trial in Congo (RD) in the 1970's also showed that correcting severe iodine deficiency during pregnancy prevents myxoedematous cretinism, particularly prevalent in affected Congolese areas.SCOPUS: re.jinfo:eu-repo/semantics/publishe

Role of vitamin E in the protection of the resident macrophage membrane against oxidative damage

SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Surcharge en thiocyanate et carence en sélénium: des cofacteurs dans l'étiologie du goitre et du crétinisme endémiques au Nord-Zaïre.

Endemic goitre is accompanied by a spectrum of iodine deficiency disorders (IDD). From work undertaken by CEMUBAC in Ubangui Zaïre, the role of thiocyanate overload is recalled while this work demonstrates for the first time in man an action of selenium supplementation (and thus deficiency) on thyroid function in iodine deficient areas. The extreme severity of the selenium deficiency may intervene either on the central and/or peripheral deiodination of thyroxine, or on the synthesis of the thyroid hormones. Together with thiocyanate overload, selenium deficiency may be responsible of the high frequency of myxedematous cretins in Zaïre.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Wording the trajectory of the three-year COVID-19 epidemic in a general population – Belgium

The trajectory of COVID-19 epidemic waves in the general population of Belgium was analysed by defining quantitative criteria for epidemic waves from March 2020 to early 2023. Peaks and starting/ending times characterised nine waves numerated I to IX based on the daily reported incidence number (symbol INCID) and three “endemic” interval periods between the first four waves. The SIR compartmental model was applied to the first epidemic wave by fitting the daily prevalence pool (symbol I) calculated as the sum of the daily incidence rate and estimated number of subjects still infectious from the previous days. The basic reproductive number R0 was calculated based on the exponential growth rate during the early phase and on medical literature knowledge of the time of generation of SARS-CoV-2 infection. The first COVID-19 wave was well fitted by an open SIR model. According to this approach, dampened recurrent epidemic waves evolving through an endemic state would have been expected. This was not the case with the subsequent epidemic waves being characterised by new variants of concern (VOC). Evidence-based observations: 1) each epidemic wave affected less than a fifth of the general population; 2) the Vth epidemic wave (VOC Omicron) presented the greatest amplitude. The lack of recurrence of the same VOC during successive epidemic waves strongly suggests that a VOC has a limited persistence, disappearing from the population well before the expected proportion of the theoretical susceptible cohort being maximally infected. Fitting the theoretical SIR model, a limited persistence of VOCs in a population could explain that new VOCs replace old ones, even if the new VOC has a lower transmission rate than the preceding one. In conclusion, acquisition of potential defective mutations in VOC during an epidemic wave is a potential factor explaining the absence of resurgence of a same VOC during successive waves. Such an hypothesis is open to discussion and to rebuttal. A modified SIR model with epidemic waves of variable amplitude related not only to R0 and public health measures but also to acquisition of defective fitting in virus within a population should be tested.SCOPUS: ar.jinfo:eu-repo/semantics/publishe