Vitamin D, Parathyroid Hormone, Insulin Sensitivity and Islet β-Cell Secretory Function in Diabetic Patients from South Kivu in the Democratic Republic of Congo: Cross-Sectional Study

Background: The role of vitamin D and parathyroid hormone in the metabolic profile of type 2 diabetes mellitus in sub-Saharan Africa has not been adequately assessed. The aim of this study was to determine the prevalence of low vitamin D level and secondary hyperparathyroidism and their association with insulin sensitivity and β-cell secretory function among Congolese type 2 diabetics. Methodology: Fasting glycaemia, fasting insulin, 25OH D3 and human parathyroid hormone (hPTH) were measured in one hundred and eighty-four type 2 diabetic patients followed as outpatients in South Kivu. Levels of 25OH D3 65 pg/ml defined low vitamin D and elevated parathyroid hormone levels, respectively. The HOMA model was used to measure insulin sensitivity and β-cell secretory function. Results: Medians (IQR) were 25.3 (20.4 - 32.4) ng/ml for 25OH D3 and 53.7 (38.4 - 115.7) pg/ml for hPTH. 58.7% of diabetics had insulin resistance, 126 (68.5%) had low vitamin D and 80 (43.5%) had hyperparathyroidism. In multivariate analysis, hPTH (partial r = −0.28;p = 0.0002) and 25OH D3 (partial r = 0.16;p = 0.03) showed an independent association with insulin sensitivity after adjustment for body mass index and waist circumference. Finally, hPTH (partial r = 0.27;p = 0.0002) was the sole determinant of β-cell secretory function. Conclusions: This study confirms the high prevalence of low vitamin D level and secondary hyperparathyroidism and their association with insulin resistance and impaired islet β-cell secretory function among Congolese with type 2 diabetes mellitus. Vitamin D and calcium supplementation should be envisaged for cases of deficiency in this region.

Post Thyroidectomy Assessment of Intact Parathyroid Hormone for Early Prediction of Hypocalcaemia

Background: As the half-life of intact parathyroid hormone (iPTH) is very low, it reflects parathyroid insufficiency within minutes to hours after total thyroidectomy. Therefore, iPTH level assessment in the postoperative period can be used to predict the development of hypocalcaemia. The optimal time point to measure serum iPTH is important for the accurate prediction of hypocalcaemia. Aim: This paper aims to evaluate the ability of iPTH as an early predictive marker of hypocalcaemia and determine which time iPTH is more able to predict postoperative hypocalcaemia. Method: This prospective observational study was conducted in the Department of Otolaryngology-Head & Neck Surgery, BSMMU, Dhaka, from July 2020 to December 2021, with 67 patients who underwent total thyroidectomy. iPTH levels were measured on the day before the operation and at 1 hour, 4 hours, and 24 hours after the operation. S.calcium levels were measured on the day before the operation and 1st postoperative day. All the data were compiled and sorted properly and were analyzed statistically. Results: Postoperative hypocalcaemia developed in 18 cases, with an incidence of 26.9%. Pearson correlation showed a significant correlation between postoperative iPTH at 1 hr, 4 h, and 24 hr with 1st postoperative calcium value. The Receiver operating characteristic (ROC) curve was processed for the postoperative iPTH at 1 hr, 4 h, and 24 hr. The sensitivity, specificity, cut-off value, and mean AUC found 93.9%, 94.4%, ≤14.0, 0.988;95.9%, 94.4%, ≤09.5, 0.993 and 91.8%, 94.4%, ≤11.0, 0.993 respectively. Conclusion: iPTH can be used as an early predictor of post-thy-roidectomy hypocalcaemia. 4 hr iPTH showed more sensitivity and specificity for a cut-off value near the laboratory reference range.

Safety,Tolerability and Pharmacokinetic Study of Recombinant Human Parathyroid Hormone [rhPTH(1-84)] in Chinese Healthy Volunteers

The current study was designed to determine the safety, tolerability and pharmacokinetic parameters of recombinant human parathyroid hormone [rhPTH （1-84）] used for the treatment of osteoporosis. In the single-dose format pharmacokinetic study, thirty-six healthy male volunteers received three dose levels of rhPTH （1-84） subcutaneously： 1, 2, and 4 μg/kg. The blood was timing drawn and the serum concentration of rhPTH （1-84） was determined by enzyme linked immunosorbent assay （ELISA）. Serum concentration-time curves of PTH （1-84） exhibited a double-peak pattern, the first peak appearing about 10 to 30 min after administration and the second peak occurring about 1.5 to2 h after administration. Serum terminal half-time of PTH （1-84） was approximately 2 h. The parameters indicated the serum levels were directly proportional to the administered dose, with the mean Cmax and AUC0_24 ranging from approximately 543.47 to 1845 pg/mL and 2358.6 to 9232.12 pg.h.mL^-1 over the dose range. The drug was well tolerated, the clinical symptoms were generally mild and of short duration.

Hypoxia-inducible factor-1a restricts the anabolic actions of parathyroid hormone

The hypoxia inducible factors （Hifs） are evolutionarily conserved transcriptional factors that control homeostatic responses to low oxygen. In developing bone, Hif-1 generated signals induce angiogenesis necessary for osteoblast specification, but in mature bone, loss of Hif-1 in osteoblasts resulted in a more rapid accumulation of bone. These findings suggested that Hif-1 exerts distinct developmental functions and acts as a negative regulator of bone formation. To investigate the function of Hif-1a in osteoanabolic signaling, we assessed the effect of Hif-1a loss-of-function on bone formation in response to intermittent parathyroid hormone （PTH）. Mice lacking Hif-1a in osteoblasts and osteocytes form more bone in response to PTH, likely through a larger increase in osteoblast activity and increased sensitivity to the hormone. Consistent with this effect, exposure of primary mouse osteoblasts to PTH resulted in the rapid induction of Hif-1a protein levels via a post-transcriptional mechanism. The enhanced anabolic response appears to result from the removal of Hif-1a-mediated suppression of β-catenin transcriptional activity. Together, these data indicate that Hif-1a functions in the mature skeleton to restrict osteoanabolic signaling. The availability of pharmacological agents that reduce Hif-1a function suggests the value in further exploration of this pathway to optimize the therapeutic benefits of PTH.

Development and validation of RP-HPLC and RP-UPLC methods for quantification of parathyroid hormones (1-34) in medicinal product formulated with meta-cresol

Rapid and sensitive reversed phase high performance liquid chromatography (RP-HPLC) and ultra performance liquid chromatography (RP-UPLC) method with UV detection has been developed and validated for quantification of parathyroid hormone (PTH) in presence of meta-cresol as a stabilizer in a pharmaceutical formulation.Chromatography was performed with mobile phase containing 0.1% Trifluoroacetic acid (TFA) in MilliQ water and 0.1% TFA in acetonitrile with gradient program and flow rate at 0.3 mL/min for HPLC and 0.4 mL/min for UPLC.Quantification was accomplished with internal reference standard (qualified against innovator product and National Institute for Biological Standards and Control (NIBSC) standard).The methods were validated for linearity (correlation coefficient 0.99),range,accuracy,precision and robustness.Robustness was confirmed by considering three factors;mobile phase composition,column temperature and flow rate/age of mobile phase.Intermediate precision was confirmed on different equipments,different columns and on different days.The relative standard deviation (RSD) (<2% for RP-HPLC and <1% for UPLC,n=30) indicated a good precision.Retention time was found about 17 min and 2 min by HPLC and UPLC methods,respectively.Both methods are simple,highly sensitive,precise and accurate and have the potential of being useful for routine quality control.

Parathyroid hormone pulsatility: physiological and clinical aspects

Parathyroid hormone （PTH） secretion is characterized by an ultradian rhythm with tonic and pulsatile components. In healthy subjects, the majority of PTH is secreted in tonic fashion, whereas approximately 30% is secreted in low-amplitude and high-frequency bursts occurring every 10-20 min, superimposed on tonic secretion. Changes in the ultradian PTH secretion were shown to occur in patients with primary and secondary osteoporosis, with skeletal effects depending on the reciprocal modifications of pulsatile and tonic components. Indeed, pathophysiology of spontaneous PTH secretion remains an area potentially suitable to be explored, particularly in those conditions such as secondary forms of osteoporosis, in which conventional biochemical and densitometric parameters may not always give reliable diagnostic and therapeutic indications. This review will highlight the literature data supporting the hypothesis that changes of ultradian PTH secretion may be correlated with skeletal fragility in primary and secondary osteoporosis.

Alcohol-induced Wnt signaling inhibition during bone fracture healing is normalized by intermittent parathyroid hormone treatment

Nearly half of orthopaedic trauma patients are intoxicated at the time of injury, and excess alcohol consumption increases the risk for fracture nonunion. Previous studies show alcohol disrupts fracture associated Wnt signaling required for normal bone fracture repair. Intermittent parathyroid hormone(PTH) promotes bone growth through canonical Wnt signaling, however, no studies have investigated the effect of PTH on alcohol-inhibited bone fracture repair. Male C57 BL/6 mice received two-3 day alcohol binges separated by 4 days before receiving a mid-shaft tibia fracture. Postoperatively, mice received PTH daily until euthanasia. Wnt/β-catenin signaling was analyzed at 9 days post-fracture. As previously observed, acute alcohol exposure resulted in a >2-fold decrease in total and the active form of β-catenin and a 2-fold increase in inactive β-catenin within the fracture callus. Intermittent PTH abrogated the effect of alcohol on β-catenin within the fracture callus. Upstream of β-catenin, alcohol-treated animals had a 2-fold decrease in total LRP6, the Wnt co-receptor, which was restored with PTH treatment. Alcohol nor PTH had any significant effect on GSK-3β. These data show that intermittent PTH following a tibia fracture restores normal expression of Wnt signaling proteins within the fracture callus of alcohol-treated mice.

Vitamin D and Parathyroid Hormone Profiles in Living Kidney Failure Patients in Côte d’Ivoire

Introduction: Abnormalities in mineral and bone metabolism, particularly phosphocalcic metabolism, are common in renal failure and are associated with a significant morbidity and mortality. The regulation of phosphocalcic metabolism is subject to a particularly precise and complex control of parathormone (PTH) and vitamin D. Assessment of vitamin D and parathyroid hormone concentrations would help to improve the medical management of patients with chronic kidney disease and ensure a better quality of life. Methods: The study population consisted of 138 individuals including 46 non- dialysis renal failure patients, 46 chronic hemodialysis patients and 46 non- renal failure volunteers to serve as controls. Serum Parathyroid hormone and Vitamin D concentrations were measured using the Vidas automated system. Results: 25-hydroxyvitamin D concentrations in controls (65 ± 2.41 nmol/L) and dialysis patients (70 ± 3.03 nmol/L) were significantly higher than those in CKD patients (48 ± 3.34 nmol/L). On the other hand, the mean values of Parathyroid hormone in dialysis patients (312 ± 36.22 pg/mL) and CKD patients (117 ± 10.68 pg/mL) were very high compared to that in controls (25 ± 2.34 pg/mL). Conclusion: Secondary hyperparathyroidism is common in renal failure. Parathyroid hormone and 25-hydroxyvitamin D assays would be adequate for better management of chronic renal failure.

Involvement of Met receptor pathway in aggressive behavior of colorectal cancer cells induced by parathyroid hormone-related peptide

BACKGROUND Parathyroid hormone-related peptide(PTHrP)plays a key role in the development and progression of many tumors.We found that in colorectal cancer(CRC)HCT116 cells,the binding of PTHrP to its receptor PTHR type 1(PTHR1)activates events associated with an aggressive phenotype.In HCT116 cell xenografts,PTHrP modulates the expression of molecular markers linked to tumor progression.Empirical evidence suggests that the Met receptor is involved in the development and evolution of CRC.Based on these data,we hypothesized that the signaling pathway trigged by PTHrP could be involved in the transactivation of Met and consequently in the aggressive behavior of CRC cells.AIM To elucidate the relationship among PTHR1,PTHrP,and Met in CRC models.METHODS For in vitro assays,HCT116 and Caco-2 cells derived from human CRC were incubated in the absence or presence of PTHrP(1-34)(10-8 M).Where indicated,cells were pre-incubated with specific kinase inhibitors or dimethylsulfoxide,the vehicle of the inhibitors.The protein levels were evaluated by Western blot technique.Real-time polymerase chain reaction(RT-qPCR)was carried out to determine the changes in gene expression.Wound healing assay and morpho logical monitoring were performed to evaluate cell migration and changes related to the epithelialmesenchymal transition(EMT),respectively.The number of viable HCT116 cells was counted by trypan blue dye exclusion test to evaluate the effects of irinotecan(CPT-11),oxaliplatin(OXA),or doxorubicin(DOXO)with or without PTHrP.For in vivo tests,HCT116 cell xenografts on 6-wk-old male N:NIH(S)_nu mice received daily intratumoral injections of PTHrP(40μg/kg)in 100μL phosphate-buffered saline(PBS)or the vehicle(PBS)as a control during 20 d.Humanitarian slaughter was carried out and the tumors were removed,weighed,and fixed in a 4%formaldehyde solution for subsequent treatment by immunoassays.To evaluate the expression of molecular markers in human tumor samples,we studied 23 specimens obtained from CRC patients which were treated at the Hospital Interzonal de Graves y Agudos Dr.JoséPenna(Bahía Blanca,Buenos Aires,Argentina)and the Hospital Provincial de Neuquén(Neuquén,Neuquén,Argentina)from January 1990 to December 2007.Seven cases with normal colorectal tissues were assigned to the control group.Tumor tissue samples and clinical histories of patients were analyzed.Paraffin-embedded blocks from primary tumors were reviewed by hematoxylin-eosin staining technique;subsequently,representative histological samples were selected from each patient.From each paraffin block,tumor sections were stained for immunohistochemical detection.The statistical significance of differences was analyzed using proper statistical analysis.The results were considered statistically significant at P<0.05.RESULTS By Western blot analysis and using total Met antibody,we found that PTHrP regulated Met expression in HCT116 cells but not in Caco-2 cells.In HCT116 cells,Met protein levels increased at 30 min(P<0.01)and at 20 h(P<0.01)whereas the levels diminished at 3 min(P<0.05),10 min(P<0.01),and 1 h to 5 h(P<0.01)of PTHrP treatment.Using an active Met antibody,we found that where the protein levels of total Met decreased(3 min,10 min,and 60 min of PTHrP exposure),the status of phosphorylated/activated Met increased(P<0.01)at the same time,suggesting that Met undergoes proteasomal degradation after its phosphorylation/activation by PTHrP.The increment of its protein level after these decreases(at 30 min and 20 h)suggests a modulation of Met expression by PTHrP in order to improve Met levels and this idea is supported by our observation that the cytokine increased Met mRNA levels at least at 15 min in HCT116 cells as revealed by RT-qPCR analysis(P<0.05).We then proceeded to evaluate the signaling pathways that mediate the phosphorylation/activation of Met induced by PTHrP in HCT116 cells.By Western blot technique,we observed that PP1,a specific inhibitor of the activation of the protooncogene protein tyrosine kinase Src,blocked the effect of PTHrP on Met phosphorylation(P<0.05).Furthermore,the selective inhibition of the ERK 1/2 mitogen-activated protein kinase(ERK 1/2 MAPK)using PD98059 and the p38 MAPK using SB203580 diminished the effect of PTHrP on Met phosphorylation/activation(P<0.05).Using SU11274,the specific inhibitor of Met activation,and trypan blue dye exclusion test,Western blot,wound healing assay,and morphological analysis with a microscope,we observed the reversal of cell events induced by PTHrP such as cell proliferation(P<0.05),migration(P<0.05),and the EMT program(P<0.01)in HCT116 cells.Also,PTHrP favored the chemoresistance to CPT-11(P<0.001),OXA(P<0.01),and DOXO(P<0.01)through the Met pathway.Taken together,these findings suggest that Met activated by PTHrP participates in events associated with the aggressive phenotype of CRC cells.By immunohistochemical analysis,we found that PTHrP in HCT116 cell xenografts enhanced the protein expression of Met(0.190±0.014)compared to tumors from control mice(0.110±0.012;P<0.05)and of its own receptor(2.27±0.20)compared to tumors from control mice(1.98±0.14;P<0.01).Finally,assuming that the changes in the expression of PTHrP and its receptor are directly correlated,we investigated the expression of both Met and PTHR1 in biopsies of CRC patients by immunohistochemical analysis.Comparing histologically differentiated tumors with respect to those less differentiated,we found that the labeling intensity for Met and PTHR1 increased and diminished in a gradual manner,respectively(P<0.05).CONCLUSION PTHrP acts through the Met pathway in CRC cells and regulates Met expression in a CRC animal model.More basic and clinical studies are needed to further evaluate the PTHrP/Met relationship.

Engineering of a NIR-activable hydrogel-coated mesoporous bioactive glass scaffold with dual-mode parathyroid hormone derivative release property for angiogenesis and bone regeneration

Osteogenesis,osteoclastogenesis,and angiogenesis play crucial roles in bone regeneration.Parathyroid hormone(PTH),an FDA-approved drug with pro-osteogenic,pro-osteoclastogenic and proangiogenic capabilities,has been employed for clinical osteoporosis treatment through systemic intermittent administration.However,the successful application of PTH for local bone defect repair generally requires the incorporation and delivery by appropriate carriers.Though several scaffolds have been developed to deliver PTH,they suffer from the weaknesses such as uncontrollable PTH release,insufficient porous structure and low mechanical strength.Herein,a novel kind of NIR-activable scaffold(CBP/MBGS/PTHrP-2)with dual-mode PTHrP-2(a PTH derivative)release capability is developed to synergistically promote osteogenesis and angiogenesis for high-efficacy bone regeneration,which is fabricated by integrating the PTHrP-2-loaded hierarchically mesoporous bioactive glass(MBG)into the N-hydroxymethylacrylamide-modified,photothermal agent-doped,poly(N-isopropylacrylamide)-based thermosensitive hydrogels through assembly process.Upon on/off NIR irradiation,the thermoresponsive hydrogel gating undergoes a reversible phase transition to allow the precise control of on-demand pulsatile and long-term slow release of PTHrP-2 from MBG mesopores.Such NIR-activated dual-mode delivery of PTHrP-2 by this scaffold enables a well-maintained PTHrP-2 concentration at the bone defect sites to continually stimulate vascularization and promote osteoblasts to facilitate and accelerate bone remodeling.In vivo experiments confirm the significant improvement of bone reparative effect on critical-size femoral defects of rats.This work paves an avenue for the development of novel dual-mode delivery systems for effective bone regeneration.

Comparison of parathyroid hormone （1-34） and elcatonin in postmenopausal women with osteoporosis： an 18-month randomized, multicenter controlled trial in China

Background Recombinant human parathyroid hormone （1-34） （rhPTH （1-34）） is the first agent in a unique class of anabolic therapies acting on the skeleton. The efficacy and safety of long-term administration of rhPTH （1-34） in Chinese postmenopausal women had not been evaluated. This study compared the clinical efficacy and safety of rhPTH （1-34） with elcatonin for treating postmenopausal women with osteoporosis in 11 urban areas of China. Methods A total of 453 postmenopausal women with osteoporosis were enrolled in an 18-month, multi-center, randomized, controlled study. They were randomized to receive either rhPTH （1-34） 20 μg （200 U） daily for 18 months, or elcatonin 20 U weekly for 12 months. Lumbar spine （L1-4） and femoral neck bone mineral density （BMD）, fracture rate, back pain as well as biochemical markers of bone turnover were measured. Adverse events were recorded. Results rhPTH （1-34） increased lumbar BMD significantly more than did elcatonin after 6, 12, and 18 months of treatment （4.3% vs. 1.9%, 6.8% vs. 2.7%, 9.5% vs. 2.9%, P 〈0.01）. There was only a small but significant increase of femoral neck BMD after 18 months （2.6%, P 〈0.01） in rhPTH groups. There were larger increases in bone turnover markers in the rhPTH （1-34） group than those in the elcatonin group after 6, 12, and 18 months （serum bone-specific alkaline phosphatase （BSAP） 93.7% vs. -3.6%; 117.8% vs. -4.1%; 49.2% vs. -5.8%, P 〈0.01; urinary C-telopeptide/creatinine （CTX/Cr） 250.0% vs. -29.5%; 330.0% vs. -41.4%, 273.0% vs. -10.6%, P 〈0.01）. rhPTH （1-34） showed similar effect of pain relief as elcatonin. The incidence of clinical fractures was 5.36% （6/112） in elcatonin group and 3.2% （11/341）in rhPTH （1-34）group （P=0.303）. Both treatments were well tolerated. Hypercaluria （9.4%） and hypercalcemia （7.0%） in rhPTH （1-34） group were transient and caused no clinical symptoms. Pruritus （8.2% vs. 2.7%, P=0.044） and redness of injection site （4.4% vs. 0,P=0.024） were more frequent in rhPTH （1-34）. Nausea/vomiting （16.1% vs. 6.2%, P=0.001） and hot flushes （7.1% vs. 0.6%, P 〈0.001） were more common in elcatonin group. Conclusions rhPTH （1-34） was associated with greater increases in lumbar spine BMD and bone formation markers. It could increase femoral BMD after 18 months of treatment, rhPTH could improve back pain effectively. The results of the present study indicate that rhPTH （1-34） is an effective, safe agent in treating Chinese postmenopausal women with osteoporosis. （ChiCTR- TRC-10000924）

A randomized, multicenter controlled trial to compare the efficacy of recombinant human parathyroid hormone （1-34） with elcatonin in postmenopausal women with osteoporosis in China

Background Recombinant human parathyroid hormone （1-34） （rhPTH （1-34）） given by injection is a new seventh class drug of biological products, which is prepared by adopting gene recombination technique, rhPTH （1-34） is mainly used to treat osteoporosis, especially for postmenopausal women. This study compared the clinical efficacy and safety of rhPTH （1-34） with elcatonin for treating postmenopausal women with osteoporosis in 11 urban areas of China. Methods Two hundred and five women with osteoporosis were enrolled in a 6-month, multicenter, randomized, controlled study. They were randomized to receive either rhPTH （1-34） 20 ug （200 U） daily or elcatonin 20 U weekly. Lumbar spine （L1-4） and femoral neck bone mineral density （BMD）, as well as biochemical markers of bone turnover were measured. Adverse events were recorded. Results rhPTH （1-34） increased lumbar BMD significantly more than did elcatonin at 3 months and 6 months （2.38% vs 0.59%, P 〈0.05; 5.51% vs 1.55%, P 〈0.01）, but there were no significant increases of BMD in these two groups at femoral neck. There were larger mean increases in bone markers in the rhPTH （1-34） group than in the elcatonin group at 3 months and 6 months （serum bone-specific alkaline phosphatase （BSAP） 36.79% vs 0.31%; 92.42% vs -0.17%; urinary N-telopeptide/creatinine （NTX/Cr） 48.91% vs -5.32%; 68.82% vs -10.86%）. Both treatments were well tolerated and there were no significant differences detected between the two groups in the proportion of any adverse events and any serious adverse events （67.0% vs 59.0%; 0 vs 0）. Conclusions rhPTH （1-34） has more positive effects on bone formation, as shown by the larger increments of lumbar BMD and bone formation markers, than elcatonin, with only mild adverse events and no significant change in the liver, kidney or hematological indices.

The expression of insulin-like growth factor-Ⅰ mRNA and polypeptide in rat osteoblasts with exposure to parathyroid hormone

Objective To investigate the insulin-like growth factor-Ⅰ (IGF-Ⅰ) gene and polypeptide expression in cultured rat osteoblast (ROB) and the role of IGF-Ⅰ in mediating the cell-to-cell communication by mimicking the pharmacokinetics of parathyroid hormone (PTH). Methods The ROB was cultured with three kinds of treatment: (1) Control (Ctr), the cells were cultured without PTH during the first 6 hours and the subsequent 42 hours in a 48-hour cycle; (2) Intermittent exposure to PTH (Itm), the cells were cultured with PTH during the first 6 hours, but without PTH in the subsequent 42 hours; and (3) Continuous exposure to PTH (Ctu), the cells were cultured with PTH during the first 6 hours and the subsequent 42 hours. Results The bone-forming activities of ROB were increased in Itm and inhibited in Ctu. The IGF-Ⅰ mRNA content in Itm cells was elevated only during the first 6 hours and that in Ctu cells was elevated at any time during an incubation cycle. The free IGF-Ⅰ concentration in the medium of Itm cells was generally higher and that of the Ctu cells was generally lower compared with those of the Ctr cells. The IGF-Ⅰ antibody significantly reduced the alkaline phosphatase activity within the cells of Ctr and Itm. Conclusions PTH rapidly and constantly stimulates the IGF-Ⅰ gene transcription of osteoblast. There was an obvious discrepancy between the IGF-Ⅰ mRNA content within the osteoblast and the free IGF-Ⅰ level around the osteoblast in either mode of PTH action. The IGF-Ⅰ might be important for osteoblast-osteoblast communication and bone-forming activity, not only in intermittent PTH administration, but also in the physiological functioning of osteoblasts.

Parathyroid hormone-mitogen-activated protein kinase axis exerts fibrogenic effect of connective tissue growth factor on human renal proximal tubular cells

Background Enhanced and prolonged expression of connective tissue growth factor （CTGF） is associated with kidney fibrosis. Parathyroid hormone （PTH） is involved in the genesis of disturbed calcium/phosphate metabolism and ostitis fibrosa in renal failure. PTH activated mitogen-activated protein kinase （MAPK） signaling pathway is present in renal tubular cells. The aim of this study was to identify the mechanism how the signal is transduced to result in extracellular signal-regulated protein kinase （ERK） activation, leading to upregulation of CTGF.Methods The levels of CTGF mRNA and protein in human kidney proximal tubular cells （HK-2） treated with PTH in the presence or absence of the MAPK inhibitor PD98059 were analyzed by quantitative real-time polymerase chain reaction （RT-PCR） and immunoblotting assay. The activation of the CTGF promoter in HK-2 cells was determined by the dual-luciferase assay. The effects of the protein kinase A （PKA） activator 8-Br-cAMP and protein kinase C （PKC） activator phorbol 12-myristate 13-acetate （PMA） on MAPK phosphorylation, and the effects of the PKA inhibitor H89 and PKC inhibitor calphostin C on MAPK phosphorylation and CTGF expression were detected by immunoblotting assay.Results PD98059 inhibited the PTH stimulated expression of CTGF, which strongly suggested that the MAPK signaling pathway plays an important role in the PTH-induced CTGF upregulation in renal tubular cells. A PKA activator as well as PKC activators induced MAPK phosphorylation, and both PKA and PKC inhibitors antagonized PTH-induced MAPK phosphorylation and CTGF expression.Conclusion CTGF expression is upregulated by PTH through a PKC/PKA-ERK-dependent pathway.

EFFECTS OF PARATHYROID HORMONE AND ESTRADIOL ON PROLIFERATION AND FUNCTION OF HUMAN OSTEOBLASTS FROM FETAL LONG BONE AN IN VITRO STUDY

The effect of parathyroid hormone (PTH) (0.01 nM-10 nM) and 17 -estradiol (E2, 1 nmol-10 nM) alone or in combination on 3H thymidine incorporation, alkaline phosphatase and adenylate cyclase activities were investigated in human fetal osteoblasts using serum-free monolayer primary cultures. The results showed that PTH inhibited cell proliferation while E, promoted it. On alkaline phosphatase activity, PTH showed a complex results while E, were slightly inhibitory. PHT-E2 combination suggested that E2 could alter the effect of PTH alone, also potentiated the anabolic and antagonize the catabolic effects of PTH on bone formation.

Update on the current management of persistent and recurrent primary hyperparathyroidism after parathyroidectomy

Primary hyperparathyroidism(pHPT)is the third most common endocrine disease.The surgical procedure aims for permanent cure,but recurrence has been reported in 4%-10%of pHPT patients.Preoperative localization imaging is highly valuable.It includes ultrasound,computed tomography(CT),single-photonemission CT,sestamibi scintigraphy and magnetic resonance imaging.The operation has been defined as successful when postoperative continuous eucalcemia exists for more than the first six months.Ongoing hypercalcemia during this period is defined as persistence,and recurrence is defined as hypercalcemia after six months of normocalcemia.Vitamin D is a crucial factor for a good outcome.Intraoperative parathyroid hormone(PTH)monitoring can safely predict the outcomes and should be suggested.PTH≤40 pg/mL or the traditional decrease≥50%from baseline minimizes the likelihood of persistence.Risk factors for persistence are hyperplasia and normal parathyroid tissue on histopathology.Risk factors for recurrence are cardiac history,obesity,endoscopic approach and low-volume center(at least 31 cases/year).Cases with double adenomas or four-gland hyperplasia have a greater likelihood of persistence/recurrence.A 6-mo calcium>9.7 mg/dL and eucalcemic parathyroid hormone elevation at 6 mo may be associated with recurrence necessitating long-term follow-up.18F-fluorocholine positron emission tomography and 4-dimensional CT in persistent and recurrent cases can be valuable before reoperation.With these novel advances in preoperative imaging and localization as well as intraoperative PTH measurement,the recurrence rate has dropped to 2.5%-5%.Sixmonth serum calcium≥9.8 mg/dL and parathyroid hormone≥80 pg/mL indicate a risk of recurrence.Negative sestamibi scintigraphy,diabetes and elevated osteocalcin levels are predictors of multiglandular disease,which brings an increased risk of persistence and recurrence.Bilateral neck exploration was considered the gold-standard diagnostic method.Minimally invasive parathyroidectomy and neck exploration are both effective surgical techniques.Multidisciplinary diagnostic and surgical management is required to prevent persistence and recurrence.Long-term follow-up,even up to 10 years,is necessary.

Parathyroid carcinoma:Three case reports

BACKGROUND Parathyroid carcinoma(PC)is a rare,slow-growing malignant tumor and a rare cause of primary hyperfunctioning of the parathyroid,with a highly variable clinical course,depending on the aggressiveness of the individual tumor and the degree of hypercalcemia.CASE SUMMARY The aim of this report is to summarize the diagnosis and treatment of three cases of PC and to review and conclude aspects regarding the three collected cases with reference to other relevant cases to explore the value of ultrasound in the diagnosis of PC.All three patients had hypercalcemia,consisting of a high serum calcium level and a high level of parathyroid hormone that was>2-fold(even>30-fold)of the normal upper limit.The ultrasonographic findings of the parathyroid gland showed that the glands were all>30 mm,and the internal echo was uneven.All patients underwent surgery.PC in three cases was confirmed by routine histopathology and immunohistochemistry.CONCLUSION As clinical signs and laboratory results are nonspecific,it is difficult to diagnose PC preoperatively,so imaging examinations are often needed.

Parathyroid ultrasonography and bone metabolic profile of patients on dialysis with hyperparathyroidism

AIM To evaluate the parathyroid ultrasonography and define parameters that can predict poor response to treatment in patients with secondary hyperparathyroidism due to renal failure.METHODS This cohort study evaluated 85 patients with chronic kidney disease stage V with parathyroid hormone levels above 800 pg/mL. All patients underwent ultrasonography of the parathyroids and the following parameters were analyzed: Demographic characteristics(etiology of chronic kidney disease, gender, age, dialysis vintage, vascular access, use of vitamin D), laboratory(calcium, phosphorus, parathyroid hormone, alkaline phosphatase, bone alkaline phosphatase), and the occurrence of bone changes, cardiovascular events and death. The χ~2 test were used to compare proportions or the Fisher exact test for small sample frequencies. Student t-test was used to detect differences between the two groups regarding continuous variables.RESULTS Fifty-three patients(66.4%) had parathyroid nodules with higher levels of parathyroid hormone, calcium and phosphorus. Sixteen patients underwent parathyroidectomy and had higher levels of phosphorus and calcium × phosphorus product(P = 0.03 and P = 0.006, respectively). They also had lower mortality(32% vs 68%, P = 0.01) and lower incidence of cardiovascular or cerebrovascular events(27% vs 73%, P = 0.02). Calcium × phosphorus product above 55 mg^2/dL^2 [RR 1.48(1.06, 2.08), P = 0.03], presence of vascular calcification [1.33(1.01, 1.76), P = 0.015] and previous occurrence of vascular events [RR 2.25(1.27, 3.98), P < 0.001] were risk factors for mortality in this population. There was no association between the occurrence of nodules and mortality.CONCLUSION The identification of nodules at ultrasonography strengthens the indication for parathyroidectomy in patients with secondary hyperparathyroidism due to renal failure.

Primary hyperparathyroidism presenting as acute pancreatitis: An institutional experience with review of the literature

BACKGROUND Acute pancreatitis(AP)presenting as an initial manifestation of primary hyperparathyroidism(PHPT)is uncommon,and its timely diagnosis is crucial in preventing recurrent attacks of pancreatitis.AIM To determine the clinical,biochemical,and radiological profile of PHPT patients presenting as AP.METHODS This is a retrospective observational study,51 consecutive patients admitted with the diagnosis of PHPT during January 2010 and October 2021 at a tertiary care hospital in Puducherry,India was included.The diagnosis of AP was established in the presence of at least two of the three following features:abdominal pain,levels of serum amylase or lipase greater than three times the normal,and characteristic features at abdominal imaging.RESULTS Out of the 51 consecutive patients with PHPT,twelve(23.52%)had pancreatitis[5(9.80%)AP,seven(13.72%)chronic pancreatitis(CP)].PHPT with AP(PHPT-AP)was more common among males with the presentation at a younger age(35.20±16.11 vs 49.23±14.80 years,P=0.05)and lower plasma intact parathyroid hormone(iPTH)levels[125(80.55-178.65)vs 519.80(149-1649.55,P=0.01)]compared to PHPT without pancreatitis(PHPT-NP).The mean serum calcium levels were similar in both PHPT-AP and PHPT-NP groups[(11.66±1.15 mg/dL)vs(12.46±1.71 mg/dL),P=0.32].PHPT-AP also presented with more gastrointestinal symptoms like abdominal pain,nausea,and vomiting with lesser skeletal and renal manifestations as compared to patients with PHPT-NP.CONCLUSION AP can be the only presenting feature of PHPT.Normal or higher serum calcium levels during AP should always draw attention towards endocrine causes like PHPT.

Analysis of the successful clinical treatment of 140 patients with parathyroid adenoma:A retrospective study

BACKGROUND Parathyroid adenoma(PA) sometimes recurs after surgery,how to improve the surgical success rate of PA is the key to the treatment of this disease.AIM To investigate the clinical features,diagnosis,and surgical treatment of patients with PA.METHODS Patients who were pathologically confirmed with PA and had undergone surgery for the first time between January 2010 and December 2017 at the Beijing Shijitan Hospital affiliated to Capital Medical University were included in the study.The clinical features,localization diagnosis,and surgical treatment of these patients were analyzed.RESULTS Of the 140 patients,32 were male and 108 were female;132 cases had one adenoma,and 8 had two adenomas.In addition,114 cases had clinical symptoms,among which 51,28,23,8,and 4 had urinary system,skeletal system,digestive system,neuromuscular system,and neuropsychiatric symptoms,respectively,while 26 cases had no obvious symptoms.The median level of preoperative parathyroid hormone(PTH) was 201.0 pg/m L.The positive detection rate of technetium-99m sestamibi(Tc-99m MIBI) single-photon emission computed tomography/computed tomography(SPECT/CT),ultrasound examination,and the combined use of Tc-99m MIBI SPECT/CT and ultrasound examination was 92.9%,85.5%,and 96.4%,respectively.Open surgery was performed in all patients,and PTH was monitored during surgery.The success rate of surgery was 98.6%.After surgery,21 cases developed hypocalcemia,1 case developed temporary hoarseness,and 19 cases had transient hypoparathyroidism but there was no permanent hypoparathyroidism,postoperative hemorrhage,or hematoma in the surgical area.CONCLUSION For patients with clinically unexplained skeletal system,urinary system,and neuropsychiatric symptoms,the possibility of PA should be considered.Imaging examinations such as ultrasound and Tc-99m MIBI SPECT/CT could be integrated before surgery to obtain accurate localization diagnosis.Precise preoperative localization,intraoperative PTH monitoring,and delicate surgery to protect the integrity of the PA capsule ensure a minimally invasive and successful surgery.