Search PubMed⌕ Search

Biomedical subjects

P Bastiani

Publications and source records attributed to P Bastiani.

29 records · Page 2Linked to original sources
PubMed1982

Correlation between thyroid-follicle fusion and structural modifications of the epithelial cells. A quantitative study in the adult rat.

Changes in thyroid structure induced by a decrease in TSH or iodide-dependent stimulation were quantified by stereological analysis of light micrographs. Studies were carried out on intact (R5) and hypophysectomized (R5H) rats receiving 5 micrograms iodide, and on intact rats (R5O) receiving 50 micrograms iodide daily. For R5H- and R5O-thyroids, the mean parameters of the epithelial cells, height, volume and lateral membrane area, were smaller than those of R5-thyroids. An inverse shift was observed for the apical membrane area, whereas the peripheral membrane area was unchanged. The number of epithelial cells was similar in each of the three groups; however, the number of follicles was greater in R5-thyroids, suggesting that follicular fusion occurs in R5O- and R5H-thyroids. This was confirmed by direct observation. The present results demonstrate that in adult rats a lack of TSH or an increased iodide diet (insufficient to produce a physiopathological state) induce follicle fusion probably by means of cellular reorganization. This increase in follicle size could be involved in the regulation of thyroid iodine turnover.

Animals↗
PubMed1982

Thyroid iodide compartments and their implication in the rat thyroid iodine organification.

To estimate the relative participation of transported and intrathyroidally generated iodide (internal iodide) in the iodination of newly synthesized and preexisting thyroglobulin (Tg) in the rat thyroid, the specific radioactivities (SRAs) of thyroid iodide, Tg, lysosomal iodine, and plasma hormones were followed for 92 h after radioactive iodide injection in intact or hypophysectomized rats. In control rats, the SRA of Tg and lysosomal iodine reached a maximum at 12 h. However, the SRA of lysosomal iodide was always smaller than that of Tg. In contrast, the SRA of hormonal iodide attained a maximum at 48 h. Thus, newly labeled iodine is endocytosed and mixed inside the lysosomes with older previously iodinated molecules; hormone secretion is mainly due to old labeled iodine (i.e. iodine with a high SRA from 48-96 h). These results are consistent with the presence of least two Tg compartments, with different turnover rates and hormone contents. On the other hand, in hypophysectomized rats, the SRA of Tg, lysosomes, and hormones showed only one maximum, at 24 h. Furthermore, the SRAs of Tg and lysosomes were similar at each time interval. It is inferred that in such rats, the old labeled iodine compartment is strongly reduced, and that inside the lysosomes, newly labeled iodine is predominant. Since in hypophysectomized rats, the recycling of iodide is abolished, it is concluded that in normal rats: 1) transported iodide is organified mainly by direct iodination of newly synthesized Tg, independently of TSH, and 2) internal iodide is organified mainly by delayed iodination of preexisting Tg, this process being TSH dependent.

Animals↗
PubMed1980

Intrafollicular re-cycling of organic iodine in the hypophysectomized rat as observed by a long-term kinetic study.

A long-term kinetic study was started 8 days after hypophysectomy in rats previously adapted to receive 5 micrograms iodide daily, and maintained on the same diet after surgery. At each time, the renewed fraction for thyroglobulin (Tg) and lysosomes in the gland, and hormones in the plasma was calculated by the method of isotropic equilibrium. All the pools studied are renewed very slowly, but with different kinetics. Between time zero and the 25th day of the experiment, the renewed fraction in plasma hormones always exceeds that of Tg. Thus, in hypophysectomized rats, Tg pool is composed of at least two compartments with different turn-over rates. Tg molecules of both compartments are endocytosed, but that of the faster compartment participate in secretion in a preferential way. Peeling of the data for the 60-day period of experiment confirms these results. In addition, peeling demonstrates a 15-day delay in the turn-over of the second compartment. Such a delay was not found in the turn-over of this compartment in lysosomes. Thus, we may again postulate, in hypophysectomized rats, a recycling of iodine in organic form from the lysosomes back to the luminal colloid, as previously porposed for control rats.

Animals↗
PubMed1980

Impairment of the mental status of patients on regular dialysis treatment.

The purpose of this study was to assess the mental status of 42 patients on regular dialysis treatment (RDT) by using the Wechsler Adult Intelligence Scale (WAIS) and Wechsler Memory Scale (WMS). Findings were correlated with serum aluminium levels, PTH levels, residual renal function (RRF) and duration of RDT. An impairment of neuropsychological performance related to the duration of RDT was found. However, a possible role of PTH and of absence of RRF could not be excluded. These observations suggest that standard haemodialysis strategies are not able to prevent pathological changes in the brain of uraemic patients.

Adolescent↗
PubMed1979

The follicular iodide pool as a two-compartment system: evidence from the unstimulated thyroid gland.

The isotopic equilibrium method was used for a 60-day period to follow iodine turnover in control and hypophysectomized rats. After the suppression of TSH by hypophysectomy, only the captured iodide is used for iodination of thyroglobulin, the iodide recycling being abolished. In unstimulated gland, two metabolically distinct iodide compartments do exist which differ either in their chemical form or in their morphological distribution, or both.

Animals↗
PubMed1977

Long-term turnover of thyroid iodine in the rat as studied by the isotopic equilibrium method.

A long-term kinetics study was made in rats in a steady state for iodine metabolism and receiving either 5 microng iodine (group5) or 50 microng iodine (group 50) daily. By using the isotopic equilibrium method, the value of the renewed fraction was followed during at least 120 days in the thyroglobulin (Tg) and the lysosomes of the thyroid and in the plasma hormones. For both groups, only part of the total iodine pool in the Tg as well as in the lysosomes is directly available for secretion. Furthermore, the direct precursor pool of iodine for secretion in the lysosomes is dependent on the daily iodine intake (1.3 times greater in group 50 than in group 5) while the Tg iodine supply in the colloid is not (80% of the total Tg iodine pool for both groups). An iodine pool with a very slow turnover is present in the lysosomes (about 50% in each group), in the Tg of group 5 (more than 15%) and probably in the Tg of group 50 (less than 5%). Thus, the distribution of such a pool between lysosomes and Tg is dependent on the daily iodine intake. The very slow iodine pool is probably not accumulated into the follicles, since every studied pool is in steady state. It is practically not secreted since hormones in the plasma are entirely renewed. Again, it is practically not deiodinated since the thyroid iodide pool is also entirely renewed. These three criteria are valuable for both groups. Although one cannot entirely exclude its participation in secretion, it is postulated that the major part of this pool is re-cycled without deiodination. Both lysosome-lysosome and lysosome-colloid pathways of re-cycling have been postulated. The second pathway is supposed to increase when the daily iodine intake is decreased.

Animals↗
PubMed1975

[Isotopic equilibrium and thyroid secretion].

The long-term iodine turnover (140 days) of thyroid gland and plasma has been studied in rats in a steady state and receiving either 5 (group 5) or 50 (group 50) mug of iodine daily. At 60 days, the turnover of Thyroglobin is total (group 50) or 80% (group 5) but is total for PBI in the two groups. An iodine pool with a very slow turnover participates neither in the PBI secretion nor in the iodide recycling within the gland.

Animals↗
PubMed1975

Iodinated particles in the rat thyroid. II. Lysosomal characteristics.

In a previous study (Simon et al. 1971) a procedure for the preparation and separation of iodinated particles was described in the rat. The present paper deals with further investigations on the nature of these particles. Acid phosphatase and iodine are conjointly sedimentable and display a latency that is unmasked on dilution in a hypo-osmotic medium and under acidification to pH 5.0. These properties together with the sensitivity to Triton X-100 are best accounted for by assuming that iodinated particles of the thyroid gland are lysosomes. Part of the particulate iodine is soluble in n-butanol (BEI fraction). The existence of this BEI fraction demonstrates that hydrolysis of thyroglobulin occurs within the particles which thus exhibit an acid protease activity. Both the sedimentable iodine pool and acid phosphatase are increased under TSH stimulation and decreased after thyroxine treatment. In addition, the general activity of the iodinated particles is dependent on the daily iodine intake as shown by the variation of their iodine pool, acid phosphatase activity and BEI fraction with the iodine diet. It is concluded that iodinated particles of the thyroid gland are secondary lysosomes which participate in iodine secretion under TSH control. By in vitro treatment with destabilizing media or after in vivo treatment with thyroxine, iodinated particles exhibit a parallel loss of iodine and acid phosphatase. After a short-term TSH treatment in vivo, their iodine pool is more increased than their acid phosphatase activity. It is concluded that, at least in the normal rat thyroid, iodinated particles are essentially secondary lysosomes; true colloid droplets actually accumulate only after sufficient TSH stimulation.

Acid Phosphatase↗
PubMedDate not supplied

Antioxidant enzyme activities in healthy old subjects: influence of age, gender and zinc status: results from the Zincage Project.

Enzymatic activities of plasma superoxide dismutase (pSOD), catalase (CAT) and glutathione peroxidase (GPx) and erythrocyte superoxide dismutase (eSOD) were assayed in 981 healthy community dwelling old subjects participating in the Zincage Project. The relationship between antioxidant enzyme activities and, respectively, gender, age and zinc status were assessed. eSOD activity was higher in nonagenarians than in 80 year old subjects. Plasma Zn was lower in nonagenarians compared with younger subjects. The prevalence of Zn deficiency increased with age, with normal Zn levels observed in about 80% of adult subjects and only in 37% of the nonagenarians. Women showed higher eSOD and CAT activities compared to men, whereas plasma Zn was higher in men than in women. There was a positive correlation between eSOD activity and age and a negative correlation between eSOD activity and plasma Zn concentrations. An inverse correlation was also found between plasma Zn concentration and age. Further studies on different aspects of Zn metabolism--intake, plasma concentration, peripheral cell concentration, activity and amount of Zn-dependent enzymes--are warranted.

Age Distribution↗