Growth hormone effect on accumulation of arterial basement membrane-like material studied on rabbit aortic myomedial cell cultures

Summary The effect of human growth hormone on arterial basement membrane-like (BM) material was studied. BM-like material was obtained from the cell layer of cultured aortic myomedial cells using a sonication-differential centrifugation technique. After the addition of small amounts of growth hormone (1 ng/ml) to the cultures, we observed a 26% increased incorporation of amino acids into BM-like material (2p<0.005). However, further increase in the incorporation was not observed using either 3 ng or 10 ng growth hormone per ml. Growth hormone inhibited removal/degradation of BM-like material by 16% (2p<0.01). However, pinocytosis rate and activity of major lysosomal enzymes: cathepsin D, acid phosphatase and -N-acetyl-glucosaminidase were unchanged. Incorporation of glycosaminoglycans as evaluated by [³⁵SO₄]-labelling was reduced by 8% when cells were exposed to growth hormone (2p<0.01). The present study demonstrates an effect of growth hormone on the turnover and composition of BM-like material in cultured arterial myomedial cells.     

Mutated Desmoglein‐2 Proteins are Incorporated into Desmosomes and Exhibit Dominant‐Negative Effects in Arrhythmogenic Right Ventricular Cardiomyopathy

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a hereditary cardiac condition associated with ventricular arrhythmias, heart failure, and sudden death. The most frequent ARVC genes encode desmosomal proteins of which mutations in desmoglein‐2 (DSG2), account for 10%–20% of cases. This study aimed to investigate how DSG2 mutations contribute to the pathogenesis of ARVC. Initial mutation analysis of DSG2 in 71 probands identified the first family reported with recessively inherited ARVC due to a missense mutation. In addition, three recognized DSG2 mutations were identified in 12 families. These results and further mutation analyses of four additional desmosomal genes indicated that ARVC caused by DSG2 mutations is often transmitted by recessive or digenic inheritance. Because desmosomal proteins are also expressed in skin tissue, keratinocytes served as a cell model to investigate DSG2 protein expression by Western blotting, 2D‐PAGE, and liquid chromatography–mass spectrometry. The results showed that heterozygous mutation carriers expressed both mutated and wild‐type DSG2 proteins. These findings were consistent with the results obtained by immunohistochemistry of endomyocardial biopsies and epidermal tissue of mutation carriers, which indicated a normal cellular distribution of DSG2. The results suggested a dominant‐negative effect of the mutated DSG2 proteins because they were incorporated into the desmosomes.     

Soluble intercellular adhesion molecule-1 (sICAM-1) and soluble interleukin-2 receptors (sIL-2R) in scleroderma skin

In order to investigate whether soluble intercellular adhesion molecule- 1 (sICAM-1) and soluble interleukin-2 receptors (sIL-2R) were present in scleroderma skin, and to compare their levels to concentrations measured in plasma and clinical parameters, we examined suction blister fluid and plasma from 13 patients with systemic sclerosis and 11 healthy volunteers. Suction blisters and biopsies were from the transition zone between normal skin and scleroderma, and uninvolved abdominal skin. The levels of sICAM-1 and sIL-2R were significantly increased in both plasma and suction blister fluid from systemic sclerosis patients compared with healthy volunteers. ICAM-1 was localized to vessels and perivascular mononuclear infiltrates by immunohistochemical methods. IL-2R was expressed by CD3-positive cells. The elevated levels of sICAM-1 and sIL-2R in suction blister fluid point towards activation of endothelial cells and T cells in both the transition zone and uninvolved skin of systemic sclerosis patients.      

Risk prediction in acute coronary syndrome from serial in-hospital measurements of N-terminal pro-B-type natriuretic peptide

There is limited information about the in-hospital plasma profile of N-terminal pro-B-type natriuretic peptide (NT-proBNP) in patients with non-ST-elevation acute coronary syndrome (NSTACS) and furthermore, the prognostic influence of the timing of NT-proBNP measurements in NSTACS is unsettled. These subject matters are elucidated in this study composed of 455 patients with NSTACS (symptoms <24 h). NT-proBNP was measured at 0, 6, 12, 24, 36, 48, 72 and 96 h following admission. Any death was registered at follow-up (median: 2.3 years). The study demonstrated a monophasic profile of the plasma NT-proBNP values, reaching a maximum at 6 hours, and it showed an independent prognostic significance of NT-proBNP irrespective of the sampling time. Risk prediction by NT-proBNP was improved by combining the baseline measurement and one value taken between 24 and 96 h (at 48 h, P<0.001). No additional prognostic information was provided by including more than one late in-hospital NT-proBNP value. Conclusions: The in-hospital NT-proBNP measurements exhibit a monophasic profile in patients with NSTACS and these values provide independent prognostic information as regards mortality irrespective of the sampling time. Moreover, risk prediction of NT-proBNP is strengthened by combining the admission measurement with an additional value during the hospitalization.     

BMD improvements after operation for primary hyperparathyroidism

Purpose

This study aims to quantify bone mineral density (BMD) changes following surgery in patients with primary hyperparathyroidism (PHPT) and to assess their relationship with clinical and biochemical variables.

Methods

A historic cohort of 236 PHPT patients with DXA scans pre- and 1-year postoperatively, clinical data, and biochemical data was analyzed.

Results

The mean age was 60 years (range 19–86) and 81 % of the patients were women. A significant postoperative 2.6 % (95 % CI, 2.1; 3.1) increase in lumbar spine BMD was seen. The increase in BMD was positively associated with preoperative plasma PTH (p?=?0.002), Ca²⁺ (p?<?0.001), and alkaline phosphatase (p?=?0.014). Hip BMD increased 1.5 % (1.1; 1.9). The increase in BMD was positively associated with preoperative plasma PTH (p?=?0.005) and Ca²⁺ (p?<?0.001) and inversely associated with plasma creatinine (p?=?0.004) and age (p?=?0.018). Total forearm BMD did not change significantly (?0.2 % (?0.5; 0.1)). An increase in forearm BMD was seen in 38 % of all patients, and the changes were positively associated with plasma PTH (p?<?0.001) and Ca²⁺ (p?=?0.009). In all 91 patients with mild PHPT (plasma Ca²⁺?<?1.45 mmol/l), there was a significant postoperative increase in spine BMD (1.9 % (1.2; 2.7)) and in hip BMD (1.0 % (0.4; 1.6)), but not in the forearm BMD (?0.3 % (?0.7; 0.2)). The postoperative BMD gain was higher in the hip and forearm in patients operated for adenomas compared with patients treated for hyperplasia.

Conclusions

We found significant postoperative BMD improvements both at the hip and the spine. BMD improvements were also significant in mild cases. At all scan sites, there were positive associations between preoperative plasma PTH levels and postoperative BMD increases. The measured BMD changes may mainly be due to a decrease in PTH-induced bone turnover with refilling of the remodeling space.     

Double-blind, placebo-controlled study of oral calcitriol for the treatment of localized and systemic scleroderma

BACKGROUND: Various treatments including corticosteroids, nonsteroidal anti-inflammatory drugs, D-penicillamine, interferon gamma, cyclosporine, and cytostatic drugs have been used with limited success in both morphea and systemic sclerosis (SSc). OBJECTIVE: We investigated the effect of treatment with oral calcitriol in patients with localized or systemic scleroderma. METHODS: A randomized, double-blind, placebo-controlled study of 9 months' duration with a 6-month follow-up was performed at the Department of Dermatology. A total of 27 patients (7 patients with SSc and 20 with morphea) were selected on a minimal skin score of 3 for patients with morphea and 12 for those with SSc. Each patient received calcitriol (0.75 microg/day for 6 months plus 1.25 microg/day for 3 months) or placebo for 9 months. Efficacy parameters included skin score, measurement of serum markers of collagen synthesis and degradation and, additional for the patients with SSc, oral aperture measurements, lung function studies, and esophagus motility. RESULTS: The skin score in patients with morphea after 9 months' treatment showed no significant difference between the placebo and calcitriol groups (mean percentage reduction [SD] in skin score in the placebo group was -29.3 [57.9]; in the calcitriol group it was -19.4 [46.6]). The small group of patients with SSc was inadequate to allow us to draw any conclusions regarding efficacy. No significant change was found in the serum markers of collagen metabolism. CONCLUSION: In this study calcitriol was not more effective than placebo in patients with morphea. Because of the small group of patients with SSc treated, no conclusions regarding efficacy in SSc can be drawn.     

Vitamin D Insufficiency in Greenlanders on a Westernized Fare: Ethnic Differences in Calcitropic Hormones Between Greenlanders and Danes

We studied the influence of age, gender, latitude, season, diet and ethnicity on plasma 25-hydroxyvitamin D 25 OHD, PTH, 1,25-dihydroxyvitamin D, vitamin D-binding protein, bone-specific alkaline phosphatase, and osteocalcin levels in 46 Greenlanders living in Nuuk (64°N) on a traditional fare (group A), 45 Greenlanders living in Nuuk on a westernized fare (group B), 54 Greenlanders (group C), and 43 Danes (Group D) living in Denmark (55°N) on a westernized fare. Blood specimens were drawn both summer and winter. Vitamin D insufficiency (plasma 25 OHD <40 nmol/l) was common in all four study groups during summer (23–74%) and winter (42–81%). Compared to groups A and D, vitamin D insufficiency was significantly more frequent in groups B and C. In all groups, summer levels of 25 OHD were above winter levels. Multiple regression analysis revealed a significant effect of ethnicity. Compared to Danes, Greenlanders had higher 1,25-dihydroxyvitamin D levels, but lower 25 OHD and PTH levels despite relatively low plasma calcium concentrations. In addition to ethnicity, 25(OH)D levels were influenced by age, season (summer > winter), and diet (a traditional Inuit diet>westernized diet). Ethnical differences exist between Greenlanders and Danes. Our results suggest that Greenlanders may have an inherent lower set-point for calcium-regulated PTH release or an enhanced renal 1,25(OH)₂D production. In addition to ethnicity, age, season, and diet were important determinants of vitamin D status. Changes from a traditional to a westernized fare are associated with a reduced vitamin D status in Greenlanders. Vitamin D supplementation should be considered.     

Loop diuretics alter the diurnal rhythm of endogenous parathyroid hormone secretion. A randomized-controlled study on the effects of loop- and thiazide-diuretics on the diurnal rhythms of calcitropic hormones and biochemical bone markers in postmenopausal women

BACKGROUND: Thiazide diuretics (TD) reduce urinary calcium, bone loss and fracture risk. Loop diuretics (LD) may have opposite effects. These effects could depend on induced rhythmic changes in bone and calcium homeostasis. DESIGN: After a run-in period of 7 days, we studied (in a factorial design) the diurnal rhythms of plasma levels of calcium, phosphate, parathyroid hormone (PTH), 1,25-dihydroxyvitamin D and osteocalcin, as well as renal excretions rates of calcium, phosphate, and cross-linked N-terminal telopeptide of type 1 collagen (NTx) in 50 postmenopausal women randomized to treatment with either a thiazide diuretic (TD; bendroflumethiazide, n = 14), a loop diuretic (LD; bumetanide, n = 13), LD plus TD (bendroflumethiazide plus bumetanide, n = 11), or placebo (n = 12). RESULTS: In all four groups, all measured quantities showed a diurnal variation. LD caused a steep increase, with a subsequent decrease, in urinary calcium and plasma PTH. The mean 24 h plasma PTH concentration was increased (8.5 +/- 0.9 mmol L-1) compared with placebo (4.4 +/- 0.4 mmol L-1), whereas net 24 h renal calcium excretion did not differ from that of the placebo group due to a rebound hypocalciuria. Compared with placebo, diurnal rhythms of plasma phosphate and osteocalcin were changed with an increase during daytime and a decrease during the night. TD did not alter the diurnal rhythm of any of the measured quantities. However, the 24-h renal calcium excretion decreased, whereas the mean 24-h plasma calcium concentration increased without PTH suppression. LD plus TD caused changes similar to those observed with LD alone. CONCLUSION: One daily dose of LD increases parathyroid activity with alterations in the diurnal pattern of osteocalcin. This could indicate a potential anabolic effect of LD.     

Dose-effect relations of loop- and thiazide-diuretics on calcium homeostasis: a randomized,double-blinded Latin-square multiple cross-over study in postmenopausal osteopenic women

BACKGROUND: Thiazide diuretics (TDs) reduce whereas loop diuretics (LDs) increase urinary calcium. We studied the effects of different doses of a TD and LD on electrolytes, calcitropic hormones and biochemical bone markers. SUBJECTS AND METHODS: In a five-period crossover study, comparing four active doses with placebo, 40 postmenopausal women with osteopenia were treated with different doses of LD bumetanide (n = 20, 0.5-2.0 mg per day) or TD bendroflumethiazide (n = 20, 2.5-10 mg per day). Each treatment period lasted 1 week. RESULTS: Urinary calcium decreased dose-dependently in response to the bendroflumethiazide. The best hypocalciuric effect was achieved by 5 mg day-1 of bendroflumethiazide. Total plasma calcium levels increased, whereas ionised calcium at ambient pH-values decreased because of increased pH-values in response to the bendroflumethiazide. Plasma PTH levels did not change, whereas a slight dose-dependent increase occurred in plasma 1,25(OH)2D levels. As a marker of bone formation, plasma osteocalcin levels increased. Conversely, bumetanide dose-dependently increased renal calcium losses with a concomitant increase in plasma PTH and 1,25(OH)2D levels. Plasma osteocalcin levels increased and bone-specific alkaline phosphatase levels decreased dose-dependently. CONCLUSION: Whether a LD or TD is chosen as diuretic therapy affects calcium homeostasis. The effects of LDs are potentially harmful to bone. Further studies are needed to evaluate whether long-term treatment with LDs causes osteoporosis. Until then, we suggest using, if possible, a TD rather than a LD as diuretic therapy in order not to risk deleterious effects on bone metabolism.