The epizootiology and pathogenesis of thyroid hyperplasia in coho salmon (Oncorhynchus kisutch) in Lake Ontario.
(1/1350)
The thyroid glands of coho salmon collected at different stages of their anadromous migration exhibited progressive and extensive hyperplasia and hypertrophy. The incidence of overt nodule formation rose from 5% in fish collected in August to 24% in fish collected in October. The histological picture of the goiters was similar to that found in thiourea-treated teleosts and thiouracil-treated mammals. There was a concomitant, significant decrease in serum thyroxine and triiodothyronine values between September and October (thyroxine, 1.0+/-0.3 mug/100 ml and 0.4 mug/100 ml in September and October, respectively; triiodothyronine, 400.3+/-51.6 ng/100 ml and 80.2 ng/100 ml in September and October, respectively) and marked hypertrophy and hyperplasia of thyrotrophs. These data indicate a progressive hypothyroid condition which, although it may be linked to iodide deficiency, may well be enhanced by other environmental factors. The evidence for involvement of other factors is discussed. (+info)
Thyroid volumes and urinary iodine in Swiss school children, 17 years after improved prophylaxis of iodine deficiency.
(2/1350)
Salt iodine content in Switzerland was raised from 7.5 to 15 mg per kg in 1980, and since then dietary iodine intake has been considered to be sufficient, even though a slight decrease due to imported food has recently been reported. The aim of this study was to establish normal values for thyroid volumes of school children who can be assumed to have had a sufficient iodine intake all their lifetime. Moreover. the present investigation was undertaken to verify that iodine sufficiency had been achieved equally in two regions each served by one of the two Swiss salt producers. Mean iodine concentration in urine spot samples from school children was 16.1 microg/dl, and it was identical in both the city of Lausanne (n=215) and the city of Solothurn (n=208). Thus it can be stated that in both cities (served by two different salt producers) iodine intake is equal and sufficient. Accordingly, thyroid volumes measured by ultrasound in school children aged 6 to 16 years were the same in both Lausanne (n=202) and Solothurn (n=207). Moreover, the age-adjusted median volumes at the 97th percentiles closely agree with and validate provisional international reference values recently proposed by the World Health Organisation and by the International Council for Control of Iodine Deficiency Disease. (+info)
Folding of apocytochrome c induced by the interaction with negatively charged lipid micelles proceeds via a collapsed intermediate state.
(3/1350)
Unfolded apocytochrome c acquires an alpha-helical conformation upon interaction with lipid. Folding kinetic results below and above the lipid's CMC, together with energy transfer measurements of lipid bound states, and salt-induced compact states in solution, show that the folding transition of apocytochrome c from the unfolded state in solution to a lipid-inserted helical conformation proceeds via a collapsed intermediate state (I(C)). This initial compact state is driven by a hydrophobic collapse of the polypeptide chain in the absence of the heme group and may represent a heme-free analogue of an early compact intermediate detected on the folding pathway of cytochrome c in solution. Insertion into the lipid phase occurs via an unfolding step of I(C) through a more extended state associated with the membrane surface (I(S)). While I(C) appears to be as compact as salt-induced compact states in solution with substantial alpha-helix content, the final lipid-inserted state (Hmic) is as compact as the unfolded state in solution at pH 5 and has an alpha-helix content which resembles that of native cytochrome c. (+info)
Perspectives from micronutrient malnutrition elimination/eradication programmes.
(4/1350)
Micronutrient malnutrition cannot be eradicated, but the elimination and control of iron, vitamin A and iodine deficiencies and their health-related consequences as public health problems are currently the targets of global programmes. Remarkable progress is occurring in the control of goitre and xerophthalmia, but iron-deficiency anaemia (IDA) has been less responsive to prevention and control efforts. Subclinical consequences of micronutrient deficiencies, i.e. "hidden hunger", include compromised immune functions that increase the risk of morbidity and mortality, impaired cognitive development and growth, and reduced reproductive and work capacity and performance. The implications are obvious for human health and national and global economic and social development. Mixes of affordable interventions are available which, when appropriately adapted to resource availability and context, are proven to be effective. These include both food-based interventions, particularly fortification programmes, such as salt iodization, and use of concentrated micronutrient supplements. A mix of accompanying programmes for infection control, community participation, including education, communication and information exchange, and private sector involvement are lessons learned for overcoming deterrents and sustaining progress towards elimination. (+info)
Important micronutrient deficiencies in at-risk populations can be addressed simultaneously with programmatically cost-effective results. Because of the interaction between many micronutrients, this would also be biologically effective. With adequate investment and political support, the chances of eliminating iodine deficiency as a problem in women of reproductive age and young children and of eliminating vitamin A deficiency as a problem in young children in the future are high. To eliminate iron deficiency and folic-acid-dependent neural tube defects (FADNTDs) in low-income populations, a new set of approaches will have to be developed. These same approaches, if successful, could be used to tackle other important micronutrient deficiencies. (+info)
Effect of iron-, iodine-, and beta-carotene-fortified biscuits on the micronutrient status of primary school children: a randomized controlled trial.
(6/1350)
BACKGROUND: Deficiencies of iron, iodine, and vitamin A are prevalent worldwide and can affect the mental development and learning ability of schoolchildren. OBJECTIVE: The aim of this study was to determine the effect of micronutrient-fortified biscuits on the micronutrient status of primary school children. DESIGN: Micronutrient status was assessed in 115 children aged 6-11 y before and after consumption of biscuits (fortified with iron, iodine, and beta-carotene) for 43 wk over a 12-mo period and was compared with that in a control group (n = 113) who consumed nonfortified biscuits. Cognitive function, growth, and morbidity were assessed as secondary outcomes. RESULTS: There was a significant between-group treatment effect on serum retinol, serum ferritin, serum iron, transferrin saturation, and urinary iodine (P <0.0001) and in hemoglobin and hematocrit (P <0.05). The prevalence of low serum retinol concentrations (<0.70 micromol/L) decreased from 39.1% to 12.2%, of low serum ferritin concentrations (<20 microg/L) from 27.8% to 13.9%, of anemia (hemoglobin <120 g/L) from 29.6% to 15.6%, and of low urinary iodine concentrations (<100 microg/L) from 97.5% to 5.4%. There was a significant between-group treatment effect (P <0.05) in cognitive function with the digit span forward task (short-term memory). Fewer school days were missed in the intervention than in the control group because of respiratory- (P = 0.097) and diarrhea-related (P = 0.013) illnesses. The intervention had no effect on anthropometric status [corrected]. CONCLUSIONS: Fortified biscuits resulted in a significant improvement in the micronutrient status of primary school children from a poor rural community and also appeared to have a favorable effect on morbidity and cognitive function [corrected]. (+info)
Amylopectinosis in fetal and neonatal Quarter Horses.
(7/1350)
Three Quarter Horses, a stillborn filly (horse No. 1), a female fetus aborted at approximately 6 months of gestation (horse No. 2), and a 1-month-old colt that had been weak at birth (horse No. 3), had myopathy characterized histologically by large spherical or ovoid inclusions in skeletal and cardiac myofibers. Smaller inclusions were also found in brain and spinal cord and in some cells of all other tissues examined. These inclusions were basophilic, red-purple after staining with periodic acid-Schiff (both before and after digestion with diastase), and moderately dark blue after staining with toluidine blue. The inclusions did not react when stained with Congo red. Staining with iodine ranged from pale blue to black. Their ultrastructural appearance varied from amorphous to somewhat filamentous. On the basis of staining characteristics and diastase resistance, we concluded that these inclusions contained amylopectin. A distinctly different kind of inclusion material was also present in skeletal muscle and tongue of horse Nos. 1 and 3. These inclusions were crystalline with a sharply defined ultrastructural periodicity. The crystals were eosinophilic and very dark blue when stained with toluidine blue but did not stain with iodine. Crystals sometimes occurred freely within the myofibers but more often were encased by deposits of amylopectin. This combination of histologic and ultrastructural features characterizes a previously unreported storage disease in fetal and neonatal Quarter Horses, with findings similar to those of glycogen storage disease type IV. We speculate that a severe inherited loss of glycogen brancher enzyme activity may be responsible for these findings. The relation of amylopectinosis to the death of the foals is unknown. (+info)
A negative iodine balance is found in healthy neonates compared with neonates with thyroid agenesis.
(8/1350)
We studied the effects of the presence or absence of the thyroid gland on the iodine metabolism and excretion in term Dutch newborns by performing a retrospective study of the urinary iodine excretion in 193 term newborns with abnormal congenital hypothyroidism screening results. Thirty-six euthyroid newborns with decreased thyroxine-binding globulin levels were compared with 157 hypothyroid patients, 54 due to thyroid agenesis and 103 due to thyroid dysgenesis. A significant difference in the urinary iodine excretion was observed between the agenesis group (mean: 28 micrograms/24 h) and the euthyroid newborns (mean: 46 micrograms/24 h, P=0.001). In conclusion, healthy, euthyroid, term newborns excreted more iodine in their urine than newborns with thyroid agenesis. These results strongly indicated the existence of a temporarily negative iodine balance: the excretion of iodine prevailed over the intake and the newborn's thyroidal iodine, stored during pregnancy, could be used for thyroxine synthesis in the postnatal period. Since healthy term neonates were able to maintain adequate plasma free thyroxine concentrations under normal TSH stimulation, the prenatally acquired iodine stores could be considered sufficiently high to compensate for the transient postnatal losses. (+info)