Biomedical subjects

W J Ginda

Publications and source records attributed to W J Ginda.

10 recordsLinked to original sources

PubMed2001

Evidence for a functional role of cholecystokinin receptors in the rat thyroid gland.

The aim of the present study was to examine the role of cholecystokinin (CCK) and/or cholecystokinin receptors subtypes (CCK1R and CCK2R) in the regulation of the thyroid gland structure and function. Animals were autopsied after 6 days of treatment with CCK or CCK receptor-specific antagonists (CCK1a--PD 140,548 or CCK2a--PD 135,158) solely or in combination with CCK. Results suggest that CCK exerts a stimulatory effect on follicular thyroid cells manifested by increased epithelium/colloid volume fraction ratio (E/C). Application of selective antagonists of CCK receptor subtypes has demonstrated that CCK acts through the CCK1 receptor subtype at the level of pituitary TSH. The model of endogenous hormone action reveals that thyroid CCK1 is responsible for the thyroid growth. It can be concluded that the physiological activity of CCK1 receptor plays a significant role in a complex interrelationship between TSH, vagal system and CCK1-dependent function of the thyroid gland.

Animals↗

PubMed2000

Decrease of TSH levels and epithelium/colloid ratio in rat thyroid glands following administration of proadrenomedullin N-terminal peptide (12-20).

Adrenomedullin (AM) exerts a potent and long-lasting hypotensive effect and is considered to be an important hormone in blood pressure control. AM is a 52-amino-acid peptide synthesized as part of a 185-amino-acid preprohormone that also contains 20-amino-acid residues in the N-terminus, which has similar biological activity. This sequence is named a proadrenomedullin N-terminal 20 peptide (PAMP). Also, proadrenomedullin N-terminal peptide (PAMP)(12-20) exerts vasodepressor response, however this response is 3-fold less potent than the effect evoked by full-sequence peptide. Both AM and PAMP controls secretory activity of the pituitary gland and adrenal cortex, however, their action on the other endocrine glands is not recognized. Therefore, the aim of the study was to examine whether PAMP(12-20) is able to affect the structure and function of the rat thyroid gland. In adult female rats, subcutaneous PAMP(12-20) administration (1 or 4 nmol/rat/day for 6 days, autopsy 60 min after the last injection) had no effect on the weight of the thyroid gland. Peptide administration however, resulted in a dose-dependent increase in the volume of thyroid colloid, and lowered epithelium/colloid ratio in the gland (3.76 +/- 0.49, 2.66 +/- 0.27, 2.38 +/- 0.26, means +/- SE, n = 6, control, 1 and 4nmol PAMP/rat, respectively). PAMP administration changed neither the length of thyroid capillaries per unit area of surface nor their diameter. Lower dose of PAMP(12-20) significantly lowered blood TSH concentration (p < 0.01) while total and free T3 and T4 concentrations remained unchanged. Collectively, these findings suggest that PAMP(12-20) exerts a mild inhibitory effect on secretory activity of the rat thyroid gland.

Adrenomedullin↗

PubMed1999

Effects of bilateral splanchnic-nerve section and chemical sympathectomy on PACAP38 content in the rat adrenals.

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a basic 38-amino acid regulatory peptide contained in the adrenal gland and involved in the control of its secretory activity. Bilateral splanchnic-nerve section caused in the rat a significant decrease in PACAP38 adrenal content and concentration, as measured by RIA. In contrast, chemical sympathectomy, obtained by administering newborn rats with 6-hydroxydopamine, was ineffective. Our findings support the view that splanchnic nerves play an important role in the control of rat adrenal function.

Adrenal Glands↗

PubMed1999

Effects of bilateral splanchnic-nerve section and chemical sympathectomy on PACAP38 content in the rat adrenals.

Adrenal Glands↗

PubMed1999

[Compensatory mechanisms of food transmission and lower respiratory tract protection after classical and extended supraglottic laryngectomies. Computerized topokinetic analysis of roentgen-cinematographic images].

Studies were performed on 22 patients, aged from 17 to 78 years, in whom, owing to laryngeal cancers, partly classical or extended supraglottic laryngectomy was carried out. The evaluation involving the pharyngeal deglutition course was accomplished by resorting to computerized topokinetic analysis of the roentgen-cinematographic images. The completed observation revealed good mobility of the anatomical structures participating in deglutition, small volume and number of glossolaryngeal recesses. There were few patients in whom the contrast medium passed to the trachea. Better passage of food as well as protection of lower respiratory tract were associated with the improvement of parameters facilitating the deglutition.

Adaptation, Physiological↗

PubMed1996

Chromogranin A immunoreactivity in epithelial cells of the thymus.

We have examined the localisation of chromogranin A (CGA) in rat thymus using immunocytochemistry. In the adult female animals we found CGA-like immunoreactivity in the epithelial cells in the subcapsular zone, the outer part of medullary region and associated with Hassall bodies. In pregnant rats more epithelial cells were immunolabelled, suggesting an increase in CGA synthesis during pregnancy. Our results indicate that CGA may be colocalised with the thymic hormones in the epithelial cells of some regions of the thymus.

Animals↗

PubMed1994

Three dimensional analysis of thymic medulla.

In consecutive serial paraffin sections centers of gravity were defined for individual cross-sections of thymic medulla of the rat. Coordinates of the centers provided grounds for a three-dimensional reconstruction of thymic medulla using for the purpose computer techniques. In all cases the medulla exhibited continuity throughout the organ and showed dendritic character with up to IVth order branching. Moreover, analysis of thymic medulla structure allowed to exclude existence of a structure which would correspond to thymic lobuli. Apart from volume and area of the cortex and the medulla, lengths of the medulla and of its branches were determined. Statistical analysis of the results demonstrated that length of individual types of medulla branches was the least variable character of the thymus while the most variable one included area of the cortex and the medulla and their volume. All parameters describing volume and area of the thymic cortex/thymic medulla were found to correlate with each other. No significant relation was observed between the parameters on one hand and length of the medulla on the other.

Animals↗

PubMed1993

Distribution of dividing thymocytes in rat thymic cortex during daily cycle.

In the present study, frequency of thymocyte divisions was analyzed in the rat thymic cortex, as related to (1) distance from thymic capsule and (2) the daily cycle. Frequency of thymocyte divisions was estimated in successive 10 micron(s) thick layers of the cortex. An evident daily cycle was detected in the thymic cortex with increase in the number of cell divisions around 8 pm.

Animals↗

PubMed1992

ACTH-induced ultrastructural changes in the zona fasciculata of the hamster adrenal cortex. Are intraadrenal thrombi regulators of corticosteroid secretion?

Correlated stereological and functional studies were performed on the effect of massive ACTH doses on adrenal cortex of the female hamster. ACTH resulted in a marked increase in adrenal gland weight at day 6 of treatment followed by a drop at day 9. Stereology showed significant enlargement of the zona fasciculata (ZF) cells with the highest value at day 6 and subsequent drop at day 9 of treatment. This hypertrophy was due to a notable increase in the volume of mitochondrial, SER, Golgi apparatus and lipid droplet compartments. Cortisol secretion by adrenal slices and homogenates was also highest at day 6 of ACTH administration and notably lower at day 9. At day 6 of ACTH treatment in outer ZF thrombi were seen. In their vicinity the subendothelial space was dilated and endothelial cells dissociated from the basal lamina. Numerous erythrocytes were also visible among dissociated ZF cells. At day 9 of experiment in outer part of ZF numerous spaces devoid of parenchymal cells appeared. The earlier authors considered the "empty spaces" or "holes" in hyperstimulated adrenal cortex as a sign of holocrine secretion of steroid hormones. The present findings enable us to introduce a new hypothesis on the development of these spaces. In our opinion in hyperstimulated adrenal cortex numerous thrombi may be formed leading thus to the degeneration of adrenocortical cells. Thus, the appearance of the "empty spaces" or "holes" in the gland is not connected with the holocrine secretion but with the regulation of the number of secretory cells in adrenal cortex by the thrombi-dependent mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenocorticotropic Hormone↗

PubMed1988

Autoradiographic studies on glucose utilization in individual zones of the rat thymus.

Wistar rats were injected intraperitoneally with 2-(14C)deoxyglucose and their thymuses were processed for thaw-mount autoradiography after 5, 10 or 35 min. Highest levels of radioactivity were demonstrated in the thymic medulla (5-fold higher than in the cortex). Scanning of autoradiograms for regional differences in grain densities indicated particularly intense glucose utilization in the cortico-medullary zone. Differences in glucose utilization between individual thymic zones seem to reflect differences in cellular composition, i.e., ratio of stroma cells to thymocytes.

Animals↗