The effect of iron and zinc supplementation and discontinuation of this practice on iron and zinc level in tissues in rats fed deficient diets

The effect of iron and iron/zinc supplementation on their levels in tissues of rats fed initially one of the three following regimen: C – control AIN-93 diet, D – iron deficient diet and R – diet with 50% reduction of all vitamins and minerals was investigated. The study was conducted on 6-week male Wistar rats, in 3 stages: (1) 4-week adaptation to the diets (C, D or R); (2) 4-week supplementation with the same regimen enriched with 10-times more iron (CSFe, DSFe, RSFe) or iron/zinc (CSFeZn, DSFeZn, RSFeZn); (3) 2-week post-supplementation period (the same diets as the stage I). Iron and zinc content in serum, the initial segment of intestine, liver and kidney were measured using FAAS method. After supplementation period (stage II) the content of iron in the intestine, liver and kidney in groups of rats fed DSFe and DSFeZn-diet were significantly higher (all p-values ≤ 0.05) than in rats fed D-diet (intestine: DSFe = 50.1 ± 9.0 μg/g wet weight, DSFeZn = 43.0 ± 9.9 μg/g vs. D = 16.5 ± 2.1 μg/g; liver: DSFe = 149 ± 30 μg/g, DSFeZn = 152 ± 25 μg/g vs. D = 56 ± 13 μg/g; kidney: DSFe = 74.0 ± 8.1 μg/g, DSFeZn = 72.7 ± 6.6 μg/g vs. D = 59.3 ± 9.5 μg/g). The same significant associations (all p-values ≤ 0.05) were observed in R rats in the intestine and liver (intestine: RSFe = 60.8 ± 6.6 μg/g, RSFeZn = 54.8 ± 6.6 μg/g vs. R = 31.5 ± 8.2 μg/g; liver: RSFe = 161 ± 10 μg/g, RSFeZn = 166 ± 21 μg/g vs. R = 136 ± 24 μg/g). After post-supplementation period the statistically significant differences between supplemented and non-supplemented rats fed D- and R-diets were still observed. There was not found the effect of applied treatments on zinc status. In conclusion, iron or iron/zinc supplementation increased similarly iron level in tissues of rats fed D-diet or R-diet with prolonged effect after supplementation discontinuation.     

Physiological growth hormone secretion in children with short stature and intra-uterine growth retardation

31 prepubertal children with short stature [mean height standard deviation score (SDS) -2.84] and low birth weight (mean -2.82 SDS) were studied. Mean age was 6.0 years and mean height velocity SDS was -0.76. Patients were classified as having either the clinical characteristics of Russell-Silver syndrome (RSS) (4 F, 13 M) or not (4 F, 10 M). All children had an overnight profile of spontaneous growth hormone (GH) secretion. 4 children achieved a maximum GH concentration of less than 20 mU/l. 9 children with RSS secreted only one large GH peak during the night. Most of the non-RSS group had normal GH pulse frequency but 3 boys had a fast-frequency pattern. Abnormal GH secretion may contribute towards growth failure in children with low birth weight/RSS.     

Spontaneous growth hormone secretion and plasma somatomedin-C in children of short stature

We studied 17 short prepubertal children, aged 7.5 to 17.0 years (mean +/- SD: 11.7 +/- 2.4) more than 2.0 SD below the mean height for their age and of delayed bone age (M +/- SD: 8.1 +/- 2.3), to clarify their physiological GH secretory status. The mean concentration of GH (MCGH) was calculated and was compared with the subjects' GH responses to insulin and arginine tolerance tests (IATT) and plasma somatomedin-C (SM-C). The mean 24-h MCGH value was 3.2 +/- 1.3 ng/ml (range 1.6-5.5). The mean peak GH response to the IATT was 13.0 +/- 7.5 ng/ml (range 2.4-33.9). In addition to the two patients with abnormally low GH responses to the IATT, seven with normal responses showed low 24-h MCGH values, a small number of GH pulses and low mean GH amplitude. The mean plasma SM-C in all patients was 0.60 +/- 0.20 U/ml. This was significantly lower than that of age-matched children of normal height (p less than 0.001). The 24-h MCGH was significantly correlated with plasma SM-C levels (r = 0.51, p less than 0.05) and with that of the first three hours of sleep at night (r = 0.84, p less than 0.01). These results indicate that: 1) some short children with normal GH response to pharmacological tests secrete a low amount of GH physiologically and 2) blood sampling during the first three hours of sleep as well as 24-hour sampling is suitable in evaluating the physiological secretion of GH.     

Effect of riboflavin supplementation on zinc and iron absorption and growth performance in mice

Diets prevalent in vegetarian populations using rice and other whole grains as staples with little consumption of yellow vegetables are low in riboflavin. These diets have poor bioavailability of iron and zinc because metals are present as inorganic salts with low solubility. Riboflavin has the capacity to form complexes, and supplementation of riboflavin may result in increased absorption of zinc and iron, thus increasing the cellular transport. Therefore, riboflavin may have direct as well as indirect effects on growth. Using this as the conceptual basis, experiments were conducted on pregnant and lactating mice. Two groups, each of 12 mice (9 females and 3 males), were observed on a low-riboflavin rice-based diet (adequate in all other nutrients), one with and one without supplementation of 10 mg riboflavin/kg diet. There was significant improvement in the growth parameters like percent conception, mean weight gain in pregnancy, mean weight of pups at the age of 21 d, and percentage hemoglobin due to riboflavin supplementation (p < 0.05). Percent zinc absorption, for the low-riboflavin diet, the supplemented diet, and the synthetic control diet were 16.4 ± 5.7, 33.7 ± 8.9, and 44.6 ± 4.0, respectively, indicating the beneficial effect of riboflavin supplementation on iron and zinc utilization.     

Effect of dietary nickel and iron on the trace element content of rat liver

The level and/or form of dietary iron, dietary nickel, and the interaction between them affected the trace element content of rat liver. Livers were from the offspring of dams fed diets containing 10–16 ng, or 20 μg, of nickel/g. Dietary iron was supplied as ferric chloride (30 μg/g) or ferric sulfate (30 μg, or 60 μg). In nickel-deprived rats fed 60 μg of iron/g of diet as ferric sulfate, at age 35 days, levels of iron and zinc were depressed in liver and the level of copper was elevated. At age 55 days, iron was still depressed, copper was still elevated, but zinc also was elevated. In rats fed 30 μg of iron/g of diet as ferric chloride, liver iron content was higher in nickel-deprived than in nickel-supplemented rats at 30, but not at 50, days of age. Also manganese and zinc were lower in nickel-deprived than in nickel-supplemented rats at age 35 days if their dams had been on experiment for an extended period of time (i.e., since age 21 days). Thus, the levels of copper, iron, manganese, and zinc in liver were affected by nickel deprivation, but the direction and extent of the affects depended upon the iron status of the rat.     

Euthyroid hypothyrotropinemia in children of short stature

Unique association of hypothyrotropinemia with euthyroidism was described in 2 children of short stature. Both had a history of intrauterine growth retardation (IUGR), but showed an appropriate growth rate after infancy (5 cm/y). Growth hormone secretion after provocation tests was normal, whereas TSH response to TRH was absent. With a highly sensitive TSH radioimmunoassay (RIA) and a specific RIA for TSH-alpha-subunit, both responded to a high dose of TRH stimulation. Serum thyroid hormones were within the normal range, while prolactin response to TRH was exaggerated. Exogenous thyroxine (T4) supplement in case 1 did not improve his growth rate, indicating absence of hypothyroidism. Case 2 was treated with stanozolol, which accelerated his growth velocity to 8 cm/y. During the treatment, serum T4 gradually decreased to 50% of the initial level, but blunted TSH response to TRH remained unchanged. These results indicate that their thyrotrophs are resistant to TRH stimulation and the pituitary setpoint of TSH release is unusually high. The exact mechanism involved in maintaining euthyroidism despite hypothyrotropinemia remains to be elucidated, but a common history of IUGR appears to play a role in producing this pituitary-thyroid state.     

Effect of chronic clonidine treatment on urinary growth hormone excretion and linear growth in children with short stature

Eleven prepubertal children with short stature were treated with clonidine (0.15 mg/m2 daily) for a period of 1 year. The effect of this drug was evaluated on both clinical (growth velocity, height standard deviation scores for chronological age and bone age) and hormonal (urinary growth hormone excretion and insulin-like growth factor I) parameters. Our study shows that long-term clonidine administration in children with short stature did not result in significant differences in growth velocity, height standard deviation scores for chronological age and bone age, insulin-like growth factor I or in urinary growth hormone excretion.     

Plasma somatomedin activity and urinary hydroxyproline excretion during administration of human growth hormone in children with short stature. Long-term effects and relation with short-term changes

Growth velocity, somatomedin activity (SM-act) and total urinary hydroxyproline excretion (THP) were studied in 9 prepubertal short children on long-term human growth hormone (hGH) therapy, and compared to the short-term responses to hGH, described in the accompanying paper. Positive correlations were found between the short-term increases of either SM-act or THP and growth acceleration, but these were too weak to be used as a predictor. On a schedule of biweekly injections, pre-injection SM-act values were only slightly higher than pre-treatment values, but post-injection values were considerably higher and similar to the values obtained with comparable hGH doses in the short-term study. There was an excellent relationship of the increment of SM-act during chronic therapy over untreated values and the increases of growth velocity. During the first year on hGH therapy the mean SM-act, mean THP and growth acceleration showed strong correlations.     

Comparison of spontaneous growth hormone secretion during daytime and sleep in children with short stature

The authors compared diurnal growth hormone (GH) secretion with GH secretion during sleep in 24 children with delayed growth. In group I (children with normal response to provocative tests), the level of daytime secretion was lower than that of nocturnal secretion. In 3 of 9 cases, daytime secretion was abnormal, whereas nocturnal secretion was normal. In 2 cases, both diurnal and nocturnal secretion were abnormal, but response to provocative stimuli was normal. In group II (children with a false partial GH deficiency, i.e. with inadequate response to provocative tests, GH peak less than 11 ng/ml and normal nocturnal secretion), the results were comparable with those of group I, with extremely low diurnal secretion in 6 of 9 cases. In group III (children presenting true partial GH deficiency, i.e. GH less than 11 ng/ml in response to provocative tests together with abnormal nocturnal secretion), both diurnal and nocturnal GH secretion were insufficient, with nonexistent diurnal secretion in 5 of 6 cases. Diurnal secretion does not seem to be a reliable indicator of 24-hour spontaneous secretion.     

A proteomic approach identified growth hormone-dependent nutrition markers in children with idiopathic short stature

Background  

The broad range in growth observed in short prepubertal children receiving the same growth hormone (GH) dose is due to individual variation in GH responsiveness. This study used a pharmaco-proteomic approach in order to identify novel biomarkers that discriminate between short non-GH-deficient (GHD) children who show a good or poor growth response to GH treatment.     

Reduced pituitary volume in children with short stature: clinical and radiological correlates

A retrospective evaluation of 80 cases of growth retardation evaluated at the H?pital Sainte-Justine of Montreal has revealed that 20 of them (25%; 15 boys and 5 girls) had a reduction of pituitary volume as revealed by high-resolution CT scanning of the pituitary gland. Of these patients, 8 had complete growth hormone (GH) deficiency, as evaluated by arginine infusion and L-Dopa-propranolol testing and nocturnal blood sampling, and 3 had GH neurosecretory dysfunction. Five patients had combined or multiple hormonal deficiencies. A statistically significant correlation was found between nocturnal plasma GH values and pituitary volumes. From this study it can be concluded that reduced pituitary volume is a frequent finding in growth-retarded children with hypopituitarism.     

Anaerobic digestion of chicken manure: Influence of trace element supplementation

In this study, anaerobic digestion of nitrogen‐rich chicken (egg‐laying hen) manure at different trace element (TE) mix doses and different total ammonia nitrogen (TAN) concentrations was investigated in batch digestion experiments. With respect to nonsupplemented TE sets, addition of TE mixture containing 1 mg/L Ni, 1 mg/L Co, 0.2 mg/L Mo, 0.2 mg/L Se, 0.2 mg/L W, and 5 mg/L Fe at TAN concentrations of 3000 mg/L and 4000 mg/L, cumulative CH₄ production and CH₄ production rate improved by 7–8% and 5–6%, respectively. The results revealed that at a very high TAN concentration of 6000 mg/L, the effect of TE addition was significantly high and the cumulative CH₄ production and production rate were increased by 20 and 39.5%, respectively. Therefore, it is concluded that at elevated TAN concentrations the CH₄ production that was stimulated by TE supplementation was presumably occurred through syntrophic acetate oxidation.     

Stress simulation: ACTH and zinc effect on trace metals in liver and spleen.

Effect of ACTH and zinc acetate subcutaneous injection on the trace metals in liver and spleen was investigated in male Wistar rats. Iron, copper, zinc and manganese in liver, and iron, copper and zinc in spleen were analyzed by AAS method. The iron, copper and zinc levels in liver, and iron levels in spleen showed a significant decrease at 1-1 h 30 min after administration of 30 UI of ACTH but values returned to normality or showed slightly higher levels at 4 h 30 min-7 h 45 min. Zinc acetate injection only elicited an increase in liver and spleen zinc levels. Results are discussed in relation with results given in previous papers.