Single and multiple selenium-zinc-iodine deficiencies affect rat thyroid metabolism and ultrastructure.

This study was conducted to evaluate the effects of single and combined deficiencies of Se, Zn and I on thyroid function in rats. Rats were fed amino acid-based diets for 6 wk starting from weaning. The diets contained either low or adequate amounts of these minerals. In addition to the control and control pair-fed groups, seven experimental groups were formed: Se deficient (Se-); I deficient (I-); Zn deficient (Zn-); Se and I deficient (Se-I-); Zn and I deficient (Zn-I-); Se and Zn deficient (Se-Zn); and Se, I and Zn deficient (Se-I-Zn-). Serum triiodothyronine (T3) was significantly lower than in controls in Zn-, Se-Zn- and Se-I- groups. Serum total thyroxine (T4) and free T4 were significantly lower and thyroid-stimulating hormone (TSH) greater in all iodine-deficient groups, regardless of Se or Zn status. Thyroid glutathione peroxidase activity was significantly reduced in Se- and Se-Zn- groups. Nevertheless, in the groups with a concurrent I deficiency, the activity of this enzyme was significantly greater than in controls. Severe alterations of the follicle cellular architecture, including signs compatible with apoptosis, were observed in the Zn- and Se-Zn- groups. These alterations appeared to be less severe when iodine deficiency was simultaneously present. Single and multiple deficiencies of Se, Zn and I have distinct effects on thyroid metabolism and structure.

The effects of breathing pattern training on ventilatory function in patients with COPD.

The purpose of this study was to assess the effects of a particular breathing pattern training (BPT) on forced expiratory volume during the first second (FEV1) and forced vital capacity (FVC) in patients with chronic obstructive pulmonary disease (COPD). The subjects adjusted each breath to a target breath displayed on a video screen, by using visual feedback. This target was chosen in an individual sample recorded at rest. We used a randomized, controlled group design. Twenty patients with stable COPD, FEV1 less than 1.5 liters, undergoing a traditional rehabilitation program were randomly assigned to the BPT group or to the control group. Each BPT subject underwent 30-35 training sessions spread out over four weeks, in addition to the traditional program. FEV1 and FVC were performed before and after this program. ANOVAs showed that FEV1 and FVC significantly improved in BPT subjects, with a mean percent increase of 22% and 19%, respectively. Corresponding changes in controls were not significant. This study showed short-term increases in FEV1 and FVC in COPD patients practicing BPT in addition to respiratory rehabilitation, in comparison with controls. Further studies should incorporate outcome data to clarify the mechanisms and the duration of this effect.

Voluntary control of breathing pattern in asthmatic children.

15 asthmatic children and 15 healthy children were trained to adjust their breathing pattern to a target pattern displayed on a video screen by using visual feedback. The error scores in the two groups were not significantly different. These data did not support the hypothesis that voluntary control of respiratory muscles is impaired in asthmatics.

Characterization of the regional distribution of selenium in Chile using selenium in hens' eggs as a monitor.

Regional distribution of selenium (Se) in Chile was investigated by using the concentration of Se in hens' eggs as a monitor. Forty-one locations along the entire length of the country were sampled. Average (+/- SD) egg-white Se content (mg/kg dry) was 0.79 +/- 0.41, range 0.22-2.23. Corresponding yolk Se values were, mean 0.81 +/- 0.43, (mg/kg dry) range 0.26-2.23. Locations grouped in five main areas, according to their geographic-climatic characteristics, showed significant differences regarding both egg-white Se and yolk Se. Analyzed dietary Se intake from two distinct areas reflected the trends observed in the Se content of egg fractions from such regions. These data support the utilization of the concentration of Se in hens' eggs as a useful monitor of dietary selenium consumed by selected populations.

Performance and learning during voluntary control of breath patterns.

Fourteen subjects learned to adjust their breath pattern to two target breaths displayed on a video screen, by using visual feedback, during two sessions 24 h apart. These two targets were respectively the smallest and the largest breaths of a ten-breath sample previously recorded from each subject's resting spontaneous breathing. Performances were significantly better for the large than for the small target breath. This cannot be directly inferred from current knowledge related to the control of movement time and amplitude, but rather it may be inferred from the periodic character of breathing, to the higher mental load during the small breath task, or to the presumably different frequencies of target breaths in the whole span of spontaneous breathing. In the second session, performance on the two targets levelled out as a result of learning.