Calcitonin (thyrocalcitonin)

Vitamin D3 supplementation improves spatial memory, muscle function, pain score, and modulates different functional physiological biomarkers in vitamin D3 deficiency diet (VDD)-induced rats model

BACKGROUND

Vitamin D Deficiency is recognized as a pandemic, which is associated with high mortality. An inadequate level of vitamin D is associated with autoimmune diseases, hypertension, and cancer. The study was aimed to assess the pharmacological effects of chronic vitamin D3 supplementation on the manipulation diet regiment of deprived cholecalciferol (vitamin D3 deficient diet, VDD) rats.

METHODS

Memory performance (Y-maze task), muscular function (muscle grip strength), and pain score (pressure application measurement meter) were measured. Functional biomarkers were measured using ELISA method in different matrix viz. in serum (parathyroid hormone; PTH, calcitonin, thyroxine, and C-reactive protein; CRP, 25-OH Vit D3), and in CSF (klotho and β-endorphin). 25-OH Vit D3 was also estimated in liver and kidney homogenate using ELISA. Vitamin D receptor (VDR) was measured spectrophotometrically in liver and adipose tissue.

RESULTS

VDD-induced rats showed a decrease in number of entries and time spent in the novel arm and spontaneous alternations in the Y-maze task. Significant improvements of neuromuscular function and pain score after addition of vitamin D3. In comparison to the VDD group, VDR expression (liver) and active metabolites of vitamin D3 (25-OH vit.D3) in serum were significantly higher by 48.23% and 280%, respectively. The PTH and CRP levels were significantly reduced by 32.5% and 35.27%, respectively, whereas calcitonin was increased by 36.67% compared with the VDD group. Klotho and β-endorphin expressions in cerebrospinal fluid were significantly elevated by 19.67% and 133.59%, respectively, compared to VDD group.

CONCLUSIONS

Overall, the results indicate that supplementation of cholecalciferol significantly improved spatial memory impairment, VDR expression, and may provide an opportunity to manage vitamin D deficiencies.

COVID-19: the CaMKII-like system of S protein drives membrane fusion and induces syncytial multinucleated giant cells

The SARS-CoV-2 S protein on the membrane of infected cells can promote receptor-dependent syncytia formation, relating to extensive tissue damage and lymphocyte elimination. In this case, it is challenging to obtain neutralizing antibodies and prevent them through antibodies effectively. Considering that, in the current study, structural domain search methods are adopted to analyze the SARS-CoV-2 S protein to find the fusion mechanism. The results show that after the EF-hand domain of S protein bound to calcium ions, S2 protein had CaMKII protein activities. Besides, the CaMKII_AD domain of S2 changed S2 conformation, facilitating the formation of HR1-HR2 six-helix bundles. Apart from that, the Ca²⁺-ATPase of S2 pumped calcium ions from the virus cytoplasm to help membrane fusion, while motor structures of S drove the CaATP_NAI and CaMKII_AD domains to extend to the outside and combined the viral membrane and the cell membrane, thus forming a calcium bridge. Furthermore, the phospholipid-flipping-ATPase released water, triggering lipid mixing and fusion and generating fusion pores. Then, motor structures promoted fusion pore extension, followed by the cytoplasmic contents of the virus being discharged into the cell cytoplasm. After that, the membrane of the virus slid onto the cell membrane along the flowing membrane on the gap of the three CaATP_NAI. At last, the HR1-HR2 hexamer would fall into the cytoplasm or stay on the cell membrane. Therefore, the CaMKII_like system of S protein facilitated membrane fusion for further inducing syncytial multinucleated giant cells.

Subtype-specific parafollicular localization of the neuropeptide manserin in the rat thyroid gland

The thyroid gland is an endocrine organ which is involved in metabolism, neuroexcitability, body growth and development. The thyroid gland is also involved in the regulation of calcium metabolism, which is not yet fully understood. In this study, we investigated the localization of the granin-derived neuropeptide, manserin, in the adult rat thyroid gland. Manserin immunoreactivity was detected in thyroid follicular epithelial cells. Intense manserin signals were also detected in some, but not all, parafollicular cells, indicating that parafollicular manserin may be subtype-specific. These results indicate that thyroid manserin may play pivotal roles in parafollicular cells and follicular epithelial cells such as in calcium metabolism and/or thyroid hormone secretion.

Mechanisms of thyroid development and dysgenesis: an analysis based on developmental stages and concurrent embryonic anatomy

Thyroid dysgenesis is the most common cause of congenital hypothyroidism that affects 1 in 3000 newborns. Although a number of pathogenetic mutations in thyroid developmental genes have been identified, the molecular mechanism of disease is unknown in most cases. This chapter summarizes the current knowledge of normal thyroid development and puts the different developmental stages in perspective, from the time of foregut endoderm patterning to the final shaping of pharyngeal anatomy, for understanding how specific malformations may arise. At the cellular level, we will also discuss fate determination of follicular and C-cell progenitors and their subsequent embryonic growth, migration, and differentiation as the different thyroid primordia evolve and merge to establish the final size and shape of the gland.

Modulators of amyloid protein aggregation and toxicity: EGCG and CLR01

Abnormal protein folding and self-assembly causes over 30 cureless human diseases for which no disease-modifying therapies are available. The common side to all these diseases is formation of aberrant toxic protein oligomers and amyloid fibrils. Both types of assemblies are drug targets, yet each presents major challenges to drug design, discovery, and development. In this review, we focus on two small molecules that inhibit formation of toxic amyloid protein assemblies — the green-tea derivative (−)-epigallocatechin-3-gallate (EGCG), which was identified through a combination of epidemiologic data and a compound library screen, and the molecular tweezer CLR01, whose inhibitory activity was discovered in our group based on rational reasoning, and subsequently confirmed experimentally. Both compounds act in a manner that is not specific to one particular protein and thus are useful against a multitude of amyloidogenic proteins, yet they act via distinct putative mechanisms. CLR01 disrupts protein aggregation through specific binding to lysine residues, whereas the mechanisms underlying the activity of EGCG are only recently beginning to unveil. We discuss current in vitro and, where available, in vivo literature related to EGCG and CLR01’s effects on amyloid β-protein, α-synuclein, transthyretin, islet amyloid polypeptide, and calcitonin. We also describe the toxicity, pharmacokinetics, and mechanism of action of each compound.

Identification of a signaling pathway involving progesterone receptor, calcitonin, and tissue tranglutaminase in Ishikawa endometrial cells

Previous studies indicated that calcitonin (CT), a peptide hormone involved in calcium (Ca(2+)) homeostasis, is transiently induced by steroid hormone progesterone (P) in the uterine epithelia of the rat and human within the window of implantation. Targeted disruption of uterine CT expression markedly impaired implantation in the rat. To gain insight into the molecular events underlying CT action in the endometrium, we performed gene expression profiling in response to CT in a human endometrial adenocarcinoma cell line, Ishikawa. We identified the gene encoding tissue tranglutaminase type II (tTGase), which participates in Ca(2+)-dependent, protein-protein cross-linking, as a downstream target of CT. Interestingly, addition of P alone to Ishikawa cells led to a marked induction in the level of both CT and tTGase, indicating the existence of a pathway involving P receptors, CT, and tTGase in these cells. Other studies revealed that regulation of the tTGase gene by CT occurs via its cell surface receptor and uses both cAMP and Ca(2+) signaling pathways. We also noted that tTGase protein is expressed in human endometrium during the P-dominated midsecretory phase of the menstrual cycle, and it is localized at the basal membrane of glandular epithelium and the surrounding stroma. The spatio-temporal expression of tTGase in human endometrium during the cycle closely overlapped with that of CT. In summary, we have uncovered a novel steroid-regulated signaling cascade in which P induces CT, which, in turn, induces tTGase and potentially plays a critical role in the human endometrium during implantation.

Hormonal regulation of implantation

Implantation is a complex process that requires synchronization between the embryo and a receptive endometrium. Hormones, such as the female sex steroids, prostaglandins, and peptide hormones, regulate the cellular and molecular mediators of endometrial receptivity, which include pinopodes, cell adhesion molecules, cytokines, homeobox genes, and growth factors. These mediators can be altered, despite the presence of normal hormone levels and endometrial histology; this limits the usefulness of the luteal phase endometrial biopsy. Therefore, analysis of markers of endometrial receptivity may predict successful implantation better. Elevated androgen and estrogen levels, as seen with polycystic ovary syndrome and controlled ovarian hyperstimulation, respectively, also can have detrimental effects on the endometrium, and therefore, implantation.

Epidural Calcitonin: Does it Provide Better Postoperative Analgesia? An Analysis of the Haemodynamic, Endocrine, and Nociceptive Responses of Salmon Calcitonin and Opioids in Epidural Anesthesia for Hip Arthroplasty Surgery

Calcitonin is an endogenous regulator of calcium homeostasis, which acts principally on bone. At present, the principal indications for the therapeutic use of calcitonin are disorders involving hypercalcemia Paget's disease, acute pancreatitis, high-bone-turnover osteoporosis, pain associated with osteoporosis or bone metastases, and Sudeck's atrophy. The aim of this study was to compare the analgesic effects on postoperative pain of salmon calcitonin versus opioids administered epidurally. Our prospective study included 53 ASA I-II patients who were scheduled for total hip arthoplasty under epidural anaesthesia and who did not fulfill 1 or more of the exclusion criteria: a history of pituitary gland dysfunction; diabetes mellitus; obesity; contraindications to performing an epidural block and/or an allergy to calcitonin. These patients were randomly allocated into 3 groups (A, B, and C), each of which received postoperatively a different analgesic epidural mixture of 10 mL to control postoperative pain. Group A was given bupivacaine 0.5% (5 mL) + fentanyl 100 (2 mL) + NaCl 0.9% (3 mL). Group B was given bupivacaine 0.5% (5 mL) + salmon calcitonin 100IU (1 mL) + NaCl 0.9% (4 mL). Group C was given salmon calcitonin 100IU (1 mL) + NaCl 0.9% (9 mL). Perioperatively, 4 blood samples were taken from each patient at the following specific times: 1. Before the induction of anesthesia; 2. At the end of the operation and before the epidural administration of the analgesic mixture; 3. At the end of the first postoperative hour (1 hour after the administration of the analgesic mixture); and 4. At the end of the second postoperative hour (2 hours after the administration of the mixture). In each blood sample, glucose, cortisol, growth hormone, and prolactin plasma levels were determined in order to investigate the changes of these parameters as a result of the endocrine reaction to stress, and to pain relief. The analgesic solution was administered immediately after the second blood sample was taken. At the same time as the 4 blood samples were taken, haemodynamic parameters and pain scores were recorded. Epidural salmon calcitonin in combination with local anaesthetic produces an analgesic effect similar to fentanyl and with stable hemodynamic results. It also eliminates postoperative hyperglycaemia. The cortisol plasma level does not increase during the first postoperative hour, but increases significantly during the second postoperative hour. Growth hormone and prolactin plasma levels were stable in all patients in all 3 groups. This study shows that calcitonin is a suitable alternative for the treatment of acute postoperative pain.

Role of steroid hormone-regulated genes in implantation

The endometrium acquires the ability to implant the developing embryo within a specific time window, termed the "receptive phase." During this period, the endometrium undergoes pronounced structural and functional changes induced by the ovarian steroids, estrogen and progesterone, which prepare it to be receptive to invasion by the embryo. These steroid-induced molecules, when identified, may serve as useful markers of uterine receptivity. In this article, we provide a brief description of one such molecule that has emerged as candidate marker of steroid hormone action in rats and humans during implantation.

Calcitonin and calcitonin gene-related peptide in the human prostate gland

BACKGROUND

Calcitonin-related peptides have been found in the human prostate, and calcitonin (CT) and calcitonin gene-related peptide (CGRP) have been demonstrated in subpopulations of neuroendocrine (NE) cells. The purpose of this study was to determine the concentrations of CT and CGRP as well as the densities of NE cells in normal prostates, benign prostatic hyperplasia (BPH), and carcinoma of the prostate (CAP).

METHODS

In 42 specimens of radical prostatectomy, the number of CT- and CGRP-immunoreactive NE cells in areas of normal and BPH tissue was determined, and compared with CAP tissue using immunocytochemistry. In addition, by radioimmunoassay (RIA), tissue levels of CT and CGRP were analyzed in extracts from areas of normal, BPH, and CAP tissue, as verified by adjacent histologic sections.

RESULTS

A significant decrease in CT-immunoreactive NE cells was observed in hyperplastic nodules of BPH in comparison to normal tissue. These findings were in parallel with a significant reduction in tissue CT level in BPH compared to normal tissue. There was also a marked, but statistically nonsignificant, reduction in CT levels in CAP tissue. In contrast, levels of CGRP in BPH and CAP tissue did not show any significant differences compared to normal tissue.

CONCLUSIONS

CT and CGRP are present in NE cells of the human prostate. Calcitonin levels are significantly reduced in BPH, in parallel with a decreased number of CT-immunoreactive NE cells, whereas no significant changes in tissue levels of CGRP were observed. The functional significance of these findings is discussed.

Calcitonin receptor binding properties in bone and kidney of the chicken during the oviposition cycle

The binding property of calcitonin (CT) in the membrane fraction of calvaria and kidney of egg-laying and nonlaying hens was analyzed using a [125I] CT binding assay system. Binding properties of CT receptors in both tissues satisfy the authentic criteria of a receptor-ligand interaction in terms of specificity, reversibility, and saturation. Scatchard plots revealed a single class of binding sites. Values of the equilibrium dissociation constant (Kd) and binding capacity (Bmax) in laying hens showed a decrease during the period between 3 h before and 2 h after oviposition. No change was observed in nonlaying hens. In vivo administration of 17beta-estradiol or progesterone caused the decrease in Kd and Bmax values. The results suggest that the binding affinity and capacity of the CT receptor in the calvaria and the kidney of the hen may be modulated by the ovarian steroid hormone.

Attenuation of calcitonin gene expression in pregnant rat uterus leads to a block in embryonic implantation

The peptide hormone calcitonin plays a key role in calcium homeostasis in many tissues, such as bone and kidney. Our previous studies revealed that the expression of calcitonin is dramatically induced in the glandular epithelium of rat uterus between days 3-5 of pregnancy before the onset of blastocyst implantation on day 5. Calcitonin expression is switched off once implantation has progressed to day 6. The coincidence in timing suggested that calcitonin may function as a regulatory signal in the uterus during the early events leading to implantation. Here we report that the implantation stage-specific expression of calcitonin can be specifically attenuated by administering antisense oligodeoxynucleotides (ODNs) directed against exon IV of calcitonin messenger RNA into the uterine horns on day 2 of gestation. The loss of calcitonin messenger RNA and protein expression upon antisense ODN treatment is accompanied by a severe impairment in implantation of embryos. Based on the observations that 1) treatment with two different antisense ODNs possessing different base compositions produced similar phenotypes; and 2) treatment with the complementary sense ODNs did not affect either calcitonin expression or implantation, we conclude that the effects of antisense ODNs on calcitonin expression and implantation are specific and functionally linked. Our study strengthens the hypothesis that a transient expression of calcitonin in the preimplantation phase uterus is critical for blastocyst implantation.

Tumour markers in diagnosis and management

The 20-year period since the discovery of AFP by Abelev has seen the introduction of a wide range of new tumour markers and it is now clear that PLC is biologically heterogeneous. Hepatoblastomas, fibrolamellar carcinomas, hepatocellular carcinomas and cholangiocarcinomas may secrete a variety of distinctive markers which are predominantly glycoproteins, and may resemble those found in placenta or fetal liver. Diagnostically, AFP remains the best marker for HCC, both in sensitivity and specificity; it is known to consist of isoforms. In patients with elevated serum AFP and filling defects on liver scan, Con A reactive AFP may differentiate PLC from hepatic metastases, whilst fucosylated AFP may distinguish PLC from benign disorders when AFP is non-diagnostically elevated. With this recognition of tumour heterogeneity the value of a multiple-marker approach has become apparent. The measurement of vitamin B12 binding protein and neurotensin should lead to the detection of most patients with the fibrolamellar variant of HCC and many of these should be resectable. In patients with normal serum AFP levels, HCC-associated GGTP is of major value whilst in low-incidence areas for HCC, patients should also be screened for H-ALP; using a multiple marker approach in high-risk groups, 90% of clinically diagnosed hepatocellular carcinomas are serologically positive. The Chinese and Alaskan studies, in which small, potentially resectable tumours were detected, suggest that it is now possible to achieve 5-year survival figures of up to 60% in HCC patients detected by screening. The value of such a strategy in low-incidence countries is currently under study. In patient monitoring, as in diagnosis, AFP remains the outstanding marker. In AFP-negative patients, other markers including vitamin B12-binding protein, neurotensin, HCC-specific isoenzymes, des-gamma-carboxy-prothrombin and alpha-fucosidase, are of undoubted diagnostic value, but their value as indicants of disease progression remains to be established. In monitoring the response of hepatic metastases, CEA remains the least unsatisfactory marker but should always be used in conjunction with serial ultrasound scans. Tumour markers now play an important role in the diagnosis and monitoring of PLC but a role is also emerging in tumour imaging and drug targeting. The next 20 years should see the introduction of tumour markers of high sensitivity and specificity which make a fundamental contribution not only to detection and monitoring, but also to the effective treatment of liver cancer.

Reduced tubular reabsorption of phosphate during post-operative glucose infusions in humans

It is well-known that serum phosphate concentration decreases considerably during post-operative glucose infusions. The purpose of this study was to elucidate whether the renal handling of phosphate could be responsible for this fall. Twelve patients were studied during glucose and saline infusions on the 2 first post-operative days. The maximal tubular capacity for reabsorption of phosphate per litre of glomerulus filtrate (TmP/GFR) was significantly reduced during glucose infusions in relation to saline infusions. The glucose induced fall in serum phosphate concentration was correlated to the change in TmP/GFR (r2 = 0.71). This study did not explain the reduced TmP/GFR during the glucose infusions, but a high correlation was found between TmP/GFR and the changes in plasma glucose concentration during the infusions (r = -0.91).

In vitro interaction between calcitonin and calmodulin

The effects of salmon calcitonin and human calcitonin on the fluorescence spectra of a fluorescent conjugate of calmodulin with dansyl-chloride and on the calmodulin mediated activation of phosphodiesterase have been studied. We showed that salmon calcitonin provoked calcium-dependent modifications of the spectra of dansyl-calmodulin and completely inhibited the calmodulin mediated activation of phosphodiesterase with a maximum effect at the dose of 5.8 X 10(-7)M and 10(-7) M respectively. No appreciable effect of human calcitonin was observed in either system. This interaction of salmon calcitonin with calmodulin is similar to the interaction of certain neuropeptides and antipsychotic drugs to calmodulin and may explain certain of the peptide's pharmacological effects.

[Experimental acceleration of fracture repair by biochemical media (author's transl)]

The influence of calcitonine, amino acids, ribonucleid acids, kallikrein, growth hormone, and cyclic adenosine 3'5' monophosphate on fracture repair was tested in rabbits. To obtain an objective measurement of callus stability the bones were bent mechanically. The force applied and the degree of bending were recorded continuously. The slope of the curve was taken as a parameter of callus stability. In the series with calcitonine no influence on fracture healing was found. Injections of ribonucleic acids, amino acids, kallidrein, and growth hormone demonstrated a limited effect on bone repair. Callus formation was stimulated by adenosine 3'5' monophosphate. Optimal results were achieved by a combination of adenosine 3'5' monophosphate, amino acids, ribonucleic acids, and kallikrein.

Evidence for interference of 25 (OH) vitamin D3 with phosphaturic action of calcitonin

The present study evaluated the effect of 25(OH)vitamin D3[25(OH)vit D3] on the phosphaturic action of calcitonin in anesthetized parathyroidectomized rats. In group 1, calcitonin was given intravenously over six clearance periods. In group 2, after three periods of calcitonin given intravenously, 25(OH)vit D3 was added and given together with calcitonin for three additional periods. During calcitonin infusion, Cp/CIn 0.18 +/- 0.02 (mean +/- SE) in group 1 was not different from the corresponding Cp/CIn 0.18 +/- 0.03 in group 2; but when 25(OH)vit D3 was added, Cp/CIn 0.12 +/- 0.01 in group 2 was lower (P less than 0.001) than the corresponding Cp/CIn 0.26 +/- 0.02 in group 1. With intravenous calcitonin the urinary excretion of cycle AMP (UcAMP) 97 +/- 29 in group 1 did not differ from the corresponding UcAMP 86 +/- 27 pmol/min in group 2, but when 25(OH)vit D3 was added UcAMP 41 +/- 12 in group 2 was lower (P less than 0.001) than the corresponding UcAMP 131 +/- 14 pmol/min in group 1. This study demonstrated that 25(OH)vit D3 blocks the phosphaturic action of calcitonin. The associated fall in Uctamp suggests that25 (OV)vit D3 acts possibly by inhibiting the calcitonin-induced activation of adenylate cyclase in the kidney. However, other alternative mechanisms of action have not been excluded.

The psysiological role of calcitonin assessed through chronic calcitonin deficiency in rats

1. An attempt was made to assess the physiological role of calcitonin by producing its prolonged deficiency in rats.2. Three groups of young rats viz. (I) sham-operated controls, (II) thyroidectomized with thyroxine replacement and (III) thyroidectomized with thyroxine as well as calcitonin replacement, all with parathyroid autografts, were studied for 5 weeks. Groups II and III showed impaired Ca tolerance and group II also showed significant reduction in total (organic and inorganic) mass of femora as compared to group I.3. Three similar groups of old mature rats were studied as under (2) for 9 weeks. Groups II and III in this case showed no significant changes as compared to group I.4. In intact mature rats, Ca tolerance is impaired, thyroid content of calcitonin is high and the hypocalcaemic action of calcitonin is much reduced as compared to intact young rats.5. It is concluded that calcitonin plays a useful but non-essential role in Ca metabolism and bone development of young growing rats. Its function, if any, in mature rats on a normal diet remains doubtful.

Glucagon in the treatment of Paget's disease of bone

Glucagon given by intravenous infusion at a dosage of 0.2 to 0.8 mg/hour to four patients with Paget's disease of bone resulted in a dramatic fall in plasma alkaline phosphatase. This was associated with a fall in 24-hour urinary calcium and in total urinary hydroxyproline excretion and a marked relief of bone pain.GLUCAGON MAY INDUCE THESE CHANGES BY THREE POSSIBLE MECHANISMS: (1) by stimulating release of calcitonin; (2) by a direct action of the hormone on bone; and (3) by stimulation of certain bone pyrophosphatases, thus altering the local mechanisms controlling the rate of bone formation and resorption.

Medullary carcinoma of the thyroid. Bumpy lip syndrome

Medullary carcinoma of the thyroid occurred in a young girl with an unusual facies, neuromas of the lips and tongue, bilateral pes cavus and a slipped capital femoral epiphysis. These abnormalities may rep resent the phenotypic manifestations of a single gene. Patients with this type of face and lips or any of the other findings should be followed carefully for the presence of thyroid and adrenal tumors.