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At least 127 records · Page 7Linked to original sources
PubMed1998

[Liver and endocrine system. Part I: pituitary-thyroid axis activity disorders].

Recent studies have demonstrated that more and more young people suffer from liver diseases. There is a close relationship between endocrine system and the liver, where the hormone inactivation and synthesis of protein binding hormones takes place. Impairment of hepatocyte function may lead to disturbed homeostasis of the endocrine system. In part I current opinions on thyreometabolic state as well as plasma levels of pituitary-thyroidal axis hormones and their binding proteins in chronic hepatic disorders are presented.

Chronic Disease↗
PubMed2001

Problem-based learning (PBL) as an approach in the teaching of biochemistry of the endocrine system at the Angeles University College of Medicine.

INTRODUCTION: Biochemistry is a basic science subject introduced in the first year of the medical curriculum. At the Angeles University College of Medicine, the approach used in teaching biochemistry has always been the conventional lecture-based strategy. This study described the factors involved in the development of modules and the use of problem-based learning (PBL) as an innovative strategy in teaching the biochemistry of the endocrine system. MATERIALS AND METHODS: Four PBL modules consisting of clinical problems, student's and facilitator's guides and a list of learning objectives were developed and used by 68 first year medical students under the supervision of a tutor during small group tutorial sessions. A 5-point Likert scale questionnaire was employed to ascertain the perceptions of the students on the influences of the components of PBL on the learning process. RESULTS: The respondents affirmed that the PBL approach motivated them to actively control the direction of their learning needs and encouraged them to acquire self-learning skills. Ninety per cent of the students found the PBL approach to have inspired them to take charge of their own learning of the biochemistry of the endocrine system. CONCLUSION: The study showed that the students found this alternative method acceptable particularly in motivating to clarify biochemical concepts that facilitated their understanding of selected endocrine problems.

Biochemistry↗
PubMed1986

Chromogranin A (CGA) in the gastro-entero-pancreatic (GEP) endocrine system. I. CGA in the mammalian endocrine pancreas.

Chromogranin A (CGA), a protein at first detected in the adrenal medulla, has recently been found also in other organs, e.g. the endocrine pancreas. However, immunohistochemical findings concerning the cellular source of pancreatic CGA were controversial. Therefore, the endocrine pancreas of 10 mammalian species (man, tupaia, mole, cat, dog, pig, guinea pig, rabbit, rat) was investigated immunohistochemically for CGA-like immunoreactivities on serial semithin plastic sections using a high-titer polyclonal antiserum against bovine CGA. The results show that basically all pancreatic endocrine cell types are CGA-immunoreactive; however, every species has its own pattern of CGA-immunoreactive cell types. Other findings of the present studies indicate that the physiological function of CGA in pancreatic endocrine cells is related to the storage mechanisms of peptide hormones. Finally, a methodological approach is given to obtain not only qualitative but also semi-quantitative data during immunohistochemical investigations.

Animals↗
PubMed2005

Selenium and endocrine systems.

The trace element selenium (Se) is capable of exerting multiple actions on endocrine systems by modifying the expression of at least 30 selenoproteins, many of which have clearly defined functions. Well-characterized selenoenzymes are the families of glutathione peroxidases (GPXs), thioredoxin reductases (TRs) and iodothyronine deiodinases (Ds). These selenoenzymes are capable of modifying cell function by acting as antioxidants and modifying redox status and thyroid hormone metabolism. Se is also involved in cell growth, apoptosis and modifying the action of cell signalling systems and transcription factors. During thyroid hormone synthesis GPX1, GPX3 and TR1 are up-regulated, providing the thyrocytes with considerable protection from peroxidative damage. Thyroidal D1 in rats and both D1 and D2 in humans are also up-regulated to increase the production of bioactive 3,5,3'-tri-iodothyronine (T3). In the basal state, GPX3 is secreted into the follicular lumen where it may down-regulate thyroid hormone synthesis by decreasing hydrogen peroxide concentrations. The deiodinases are present in most tissues and provide a mechanism whereby individual tissues may control their exposure to T3. Se is also able to modify the immune response in patients with autoimmune thyroiditis. Low sperm production and poor sperm quality are consistent features of Se-deficient animals. The pivotal link between Se, sperm quality and male fertility is GPX4 since the enzyme is essential to allow the production of the correct architecture of the midpiece of spermatozoa. Se also has insulin-mimetic properties, an effect that is probably brought about by stimulating the tyrosine kinases involved in the insulin signalling cascade. Furthermore, in the diabetic rat, Se not only restores glycaemic control but it also prevents or alleviates the adverse effects that diabetes has on cardiac, renal and platelet function.

Animals↗
PubMed1986

Evidence that obesity does not influence the vitamin D-endocrine system in blacks.

As compared to nonobese white men and women, age-matched nonobese black subjects and obese white individuals show alterations in the vitamin D-endocrine system that are characterized by increases in mean serum immunoreactive parathyroid hormone (PTH), serum 1,25-dihydroxyvitamin D [1,25-(OH)2D], and urinary cyclic adenosine 3,5-monophosphate (cAMP) and by decreases in mean serum 25-hydroxyvitamin D (25 OHD) and in urinary calcium. Thus, both groups show secondary hyperparathyroidism which is associated with increased renal tubular reabsorption of calcium and increased renal synthesis of 1,25-(OH)2D. In view of these findings, studies were conducted in 10 obese black subjects (3 men and 7 women) and in 12 nonobese black individuals (7 men and 5 women), ranging in age from 20 to 35 yr, to determine whether obesity influences the vitamin D-endocrine system in blacks. Body weight averaged 99 +/- 4 kg in the obese and 73 +/- 3 kg in the nonobese subjects (p less than .001). All of them were hospitalized on a metabolic ward and were given a constant daily diet containing 400 mg of calcium, 900 mg of phosphorus, 110 meq of sodium, 65 meq of potassium, and 18 meq of magnesium.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1982

[Undifferentiated small cell carcinoma and diffuse endocrine system (author's transl)].

Oat cell carcinomas of the lung are sometimes associated with endocrine secretion. Resulting syndromes, first regarded as "paraneoplasic", are in fact imputable to secretory activity of the tumoral cells, as demonstrated by electron microscopy and immunofluorescence studies. Such ascertainments are explained by the existence in the bronchial tree of a diffuse endocrine system sector, from which carcinoid and oat cell carcinoma originate. However, the authors consider other histogenetic hypotheses and rapidly survey the extra-pulmonary oat cell carcinomas.

Carcinoid Tumor↗
PubMedDate not supplied

[Diagnostic value of immunohistochemistry in lesions of the endocrine system].

The aim of immunohistochemistry and immunocytochemistry is to reveal specific antigens in cells and tissue samples. Those techniques are based on an antigen-antibody reaction and visualization of its product in microscopic examination. The precursor of this new diagnostic procedure was an immunofluorescent reaction in frozen tissue samples performed by Albert Coons in 1940. Then the immunohistochemical techniques were perfected to increase sensitivity and specificity. Currently it is hard to imagine a modern pathological examination without immunohistochemistry. At the end of XXth century it was believed that 75% of cases is possible to be diagnosed due to immunohistochemical stains. Microscopic examination of endocrine glands tissue samples is extremely difficult because of coexistence of the presence of neoplasms and endocrine dysfunction. It is necessary to establish the type of hormones in the cells of the endocrine system lesions to make a proper diagnosis. Thanks to the use of antibodies against hormones and its precursors it becomes possible. At present most of the antigens are easily detected in both: formalin fixed paraffin embedded tissues samples and ethanol fixed cytological smears so immunohistochemocal and immunocytological stains can be a part of routine diagnostic procedures in pathology. However most of the biologically active substances are revealed in many organs and tissues and it is necessary to perform a satisfactory immunohistochemical panel to be sure the diagnosis. It is important to notice that there is no need to make a wide panel of antibodies in all of the cases and the economical aspect of examination is also important. Of course immunohistochemistry sometimes is the guarantee of proper diagnosis but in some cases too wide panel of antibodies can be a loss for the patient and for medical department. We discussed the proper diagnostic procedures and immunohistochemical profile in pathological lesions of endocrine system (thyroid and adrenal gland, adenohypophysis, neuroendocrine tumours and some hormones-secreting tumours of gonads).

Diagnosis, Differential↗
PubMedDate not supplied

Temporal changes in neuro-immuno endocrine system with adjuvant radiotherapy for advanced rectal cancer.

The purpose of this study was to evaluate the effect of adjuvant radiotherapy for advanced rectal cancers on the human neuro-immuno-endocrine system. Fifty-seven patients with rectal cancer were investigated. Abdominoperineal resection (APR) was carried out on all of them. The levels of serum IAP in 4-12 weeks after operation were significantly higher in the preoperative radiotherapy group compared with those of non-preoperatively irradiated (p < 0.05). With preoperative radiotherapy, serum IAP levels in patients with postoperative intracavitary cone irradiation returned to normal values within three months of operation; however, those with postoperative external pelvic irradiation continued to be significantly elevated until six months after operation. We conclude that preoperative radiotherapy combined with post-operative external pelvic irradiation is likely to exert unfavorable effects on the human immuno-endocrine system.

Adrenocorticotropic Hormone↗
PubMedDate not supplied

Ligands for the vitamin D endocrine system: different shapes function as agonists and antagonists for genomic and rapid response receptors or as a ligand for the plasma vitamin D binding protein.

The integrated operation of the vitamin D endocrine system which produces the steroid hormone 1alpha,25(OH)(2)-vitamin D(3) (1alpha,25(OH)(2)D(3)) is dependent on four classes of proteins each of which have inherent in their secondary and tertiary structure a ligand binding domain (LBD) that allows the stereospecific binding of 1alpha,25(OH)(2)D(3) or related analogs as a substrate or ligand. These LBDs include: (a) the cytochrome P450 enzymes in the liver, kidney, and other tissues which metabolize vitamin D(3) into biologically active metabolites; (b) the plasma vitamin D binding protein (DBP) which selectively transports these hydrophobic molecules to the various target organs of the vitamin D endocrine system; (c) the nuclear receptor VDR(nuc) that is involved in regulation of gene transcription in over 30 cell types which possess this receptor; and (d) a plasma membrane receptor, VDR(mem), that is involved in initiation of signal transduction pathways which generate rapid biological responses. This article reviews the evidence that supports the conclusions that the LBD of the DBP, VDR(mem) and VDR(nuc) each select as their preferred ligand a unique shape of the conformationally flexible 1alpha,25(OH)(2)D(3). Two critical aspects of the conformationally flexible 1alpha,25(OH)(2)D(3) molecule which defines the optimum ligand shape are (a) the orientation and relative rigidity of the flexible 8 carbon side chain and (b) the position of the A ring in relation to the C/D rings as determined by the extent of rotation around the 6,7 single carbon bond of the seco B ring. These conclusions are based on consideration of structure-function studies of over 300 analogs of 1alpha,25(OH)(2)D(3), of these, 22 analogs are highlighted in this presentation.

Animals↗
PubMed2002

[Effects of fenvalerate on reproductive and endocrine systems of male rats].

OBJECTIVES: To evaluate the impairment of fenvalerate on reproductive and endocrine systems and clarify the mechanism of action. METHODS: Different doses of fenvalerate (0, 2, 4, 12, 60 mg/kg) were orally treated to the adult male SD rats for 15 days and 30 days, respectively. The levels of serum follicle stimulating hormone(FSH), luteinizing hormone (LH), testosterone(T) and testis homogenate T were determined by radioimmunoassay(RIA). Besides, the activity of testicular marked enzymes such as acid phosphatases(ACP) and gamma-glutamyl transpeptidase(gamma-GT) were examined, and sperm head counts were measured to explain the changes of daily sperm production(Spr). RESULTS: In fifteen days, serum FSH levels markedly increased in rats exposed to fenvalerate of < or = 12 mg/kg groups(P < 0.01) and serum levels of LH increased in 12 mg/kg group(P < 0.01). In addition, T levels in testis homogenates decreased after treated with the doses of > or = 12 mg/kg groups compared with the control group(P < 0.01). In thirty days, serum contents of FSH were significantly elevated in the doses of > or = 12 mg/kg groups(P < 0.01) and homogenate levels of T were diminished in the low dose group(2.4 mg/kg) (P < 0.05). Activity of ACP increased in 12 mg/kg group after fifteen days(P < 0.05) and was restrained in the high dose group(60 mg/kg) in thirty days(P < 0.05), but the contents of gamma-GT were arrested with different doses dependently in the testis(P < 0.05). Fenvalerate caused dose-dependent reduction in sperm head counts and daily sperm production, which markedly reduced at the doses of > or = 12 mg/kg groups(P < 0.01). CONCLUSIONS: Fenvalerate has obvious reproductive toxicity on male rats and can change their serum and testis homogenate levels of sex hormone or activity of testicular marked enzymes, which may be correlated with the impairment of Sertoli cell and spermatogenic epithelium.

Animals↗
PubMed1985

Evidence for alteration of the vitamin D-endocrine system in obese subjects.

Serum immunoreactive parathyroid hormone (PTH) is increased in obese as compared with nonobese subjects and declines with weight loss. To determine whether alteration of the vitamin D-endocrine system occurs in obesity and whether ensuing secondary hyperparathyroidism is associated with a reduction in urinary calcium, a study was performed in 12 obese white individuals, five men and seven women, and 14 nonobese white subjects, eight men and six women, ranging in age from 20 to 35 yr. Body weight averaged 106 +/- 6 kg in the obese and 68 +/- 2 kg in the nonobese subjects (P less than 0.01). Each of them were hospitalized on a metabolic ward and were given a constant daily diet containing 400 mg of calcium and 900 mg of phosphorus. Whereas mean serum calcium, serum ionized calcium, and serum phosphorus were the same in the two groups, mean serum immunoreactive PTH (518 +/- 48 vs. 243 +/- 33 pg/ml, P less than 0.001), mean serum 1,25-dihydroxyvitamin D [1,25(OH)2D] (37 +/- 2 vs. 29 +/- 2, P less than 0.01), and mean serum Gla protein (33 +/- 2 vs. 24 +/- 2 ng/ml, P less than 0.02) were significantly higher, and mean serum 25-hydroxyvitamin D (25-OHD) (8 +/- 1 vs. 20 +/- 2 ng/ml, P less than 0.001) was significantly lower in the obese than in the nonobese men and women. Mean urinary phosphorus was the same in the two groups, whereas mean urinary calcium (115 +/- 10 vs. 166 +/- 13 mg/d, P less than 0.01) was significantly lower, and mean urinary cyclic AMP (3.18 +/- 0.43 vs. 1.84 +/- 0.25 nM/dl GF, P less than 0.01) and creatinine clearance (216 +/- 13 vs. 173 +/- 6 liter/d, P less than 0.01) were significantly higher in the obese than in the nonobese individuals. There was a significant positive correlation between percentage of ideal body weight and urinary cyclic AMP (r = 0.524, P less than 0.01) and between percentage of ideal body weight and serum immunoreactive PTH (r = 0.717, P less than 0.01) in the two groups. The results provide evidence that alteration of the vitamin D-endocrine system in obese subjects is characterized by secondary hyperparathyroidism which is associated with enhanced renal tubular reabsorption of calcium and increased circulating 1,25(OH)2D. The reduction of serum 25-OHD in them is attributed to feedback inhibition of hepatic synthesis of the precursor by the increased serum 1,25(OH)2D.

Adult↗
PubMed1984

Tumors of the diffuse endocrine system, histochemical and electron-optic aids, and pitfalls in diagnosis.

Tumors of the Diffuse Endocrine System are a heterogeneous group of malignant neoplasms which have rather characteristic light microscopic and cytologic features. These are, however, not diagnostic and their identification with separation from non-neuroendocrine carcinomas require important adjunctive evaluations including histochemical analysis, immunocytochemical characterization and electron-optic identification of endocrine secretory products and paracrine effects in the cytoplasm of the neoplastic cells. The importance of proper classification cannot be over-emphasized because of the often considerable biologic and prognostic differences between neuroendocrine carcinomas and other types of carcinoma, notably metastatic carcinomas from the breast and the prostate. Furthermore, the separation of these lesions into two groups; a small cell type and those with large cells (carcinoid type) appears to have clinical significance in both diagnosis and response to therapy.

Adenocarcinoma↗