ISSN:0884-0431    

DOI:10.1002/jbmr.5650050502

出版商:John Wiley and Sons and The American Society for Bone and Mineral Research (ASBMR)    

年代:1990

数据来源: WILEY

摘要:

AbstractWe report the presence of reverse transcriptase activity in the supernatant of long‐term culture of mononuclear blood cells (monocytes and lymphocytes) isolated from a 27‐year‐old patient suffering from benign osteopetrosis. The enzyme was purified to homogeneity according to the technique of Chandra and Steel, by chromatography, first on DEAE‐cellulose (DE 52) and then on phosphocellulose (P11). After purification, the enzyme was characterized biochemically for its template specificity and ionic requirements. The purified enzyme was able to transcribe poly(rA) ··(dT)12‐18and poly(rC) ··(dG)12‐18very efficiently and had a marked preference for Mg2+ions over Mn2+ions. The pattern of ionic dependency for this enzyme is similar to that of reverse transcriptases purified from human lymphotropic viruses. The patient was tested and found seronegative for HIV‐1, HIV‐2, and HTLV‐I and seropositive (immunoglobulin C ) for cytomegalovirus. Epstein‐Barr virus nuclear antigens (EBNA) were detected in the patient's B lymphocytes. Since reverse transcriptase is the hallmark of retroviruses, we suggest that a retrovirus may be involved in the et

ISSN:0884-0431    

DOI:10.1002/jbmr.5650050503

出版商:John Wiley and Sons and The American Society for Bone and Mineral Research (ASBMR)    

年代:1990

数据来源: WILEY

摘要:

AbstractTo determine the effect of a 72 Hz pulsating electromagnetic field (PEMF) on bone density of the radii of osteoporosis‐prone women, the nondominant forearms of 20 subjects were exposed to PEMF 10 h daily for a period of 12 weeks. Bone density before, during, and after the exposure period was determined by use of a Norland‐Cameron bone mineral analyzer. Bone mineral densities of the treated radii measured by single‐photon densitometry increased significantly in the immediate area of the field during the exposure period and decreased during the following 36 weeks. A similar but weaker response occurred in the opposite arm, suggesting a “cross‐talk” effect on the nontreated radii, from either possible arm proximity during sleep or very weak general field effects. The data suggest that properly applied PEMFs, if scaled for whole‐body use, may have clinical application in the prevention and treatment of

ISSN:0884-0431    

DOI:10.1002/jbmr.5650050504

出版商:John Wiley and Sons and The American Society for Bone and Mineral Research (ASBMR)    

年代:1990

数据来源: WILEY

摘要:

AbstractCharacterized human thrombins and two commercial bovine thrombin preparations were examined for their effects on bone resorption and on the cyclic AMP and phosphoinositide second messenger systems in bone. Human α‐ and γ‐thrombins, as well as both bovine thrombin preparations, stimulated bone resorption in vitro, whereas catalytically inactivated human diisopropylfluorophosphate (DIP)‐α‐thrombin did not significantly stimulate resorption. Human α‐thrombin and a commercial bovine thrombin preparation increased cyclic AMP production in fetal rat limb bones, but another bovine commercial thrombin preparation and γ‐thrombin did not. Except for DIP‐α‐thrombin, all thrombins increased production of inositol phosphates in fetal rat limb bones at concentrations that stimulated resorption. In time course studies, bovine thrombin increased label in inositol trisphosphate at 30 s, with decreasing effects at later times. Inositol monophosphate increased progressively over 30 min. Our results are consistent with thrombin‐stimulated bone resorption being mediated at least partially through the ino

ISSN:0884-0431    

DOI:10.1002/jbmr.5650050505

出版商:John Wiley and Sons and The American Society for Bone and Mineral Research (ASBMR)    

年代:1990

数据来源: WILEY

摘要:

AbstractWe have compared two assays for osteocalcin (BGP, bone gla protein), one based on a monoclonal antibody, the other based on a polyclonal serum, in an effort to better understand the factors that contribute to the wide variation reported for osteocalcin normal ranges. The two assays compared well using serum samples, with a correlation coefficient of 0.9071 (n= 48). However, the monoclonal antibody assay returns values increased over the polyclonal assay by approximately 1.5‐fold. Gel permeation studies indicate that these larger values are due primarily to increased reactivity in the monoclonal assay with high‐ and low‐molecular‐weight forms of osteocalcin in plasma; both assays give similar reactions to intact osteocalcin. Analysis of samples from individuals with increased bone resorption due to parathyroid hormone administration reveals that the decrease seen in osteocalcin values after hormone infusion occurs primarily in the fraction that corresponds to intact osteocalcin.During the course of these studies, we re‐evaluated the extinction coefficient for osteocalcin, arriving at the value E = 1.33 mg/ml−1, cm−1. We also observed a significant negative interference in both assays (and a commercial assay) caused by hemolysis. This interference is due to proteolysis of osteocalcin by enzymatic activity released from the ly

ISSN:0884-0431    

DOI:10.1002/jbmr.5650050506

出版商:John Wiley and Sons and The American Society for Bone and Mineral Research (ASBMR)    

年代:1990

数据来源: WILEY

摘要:

AbstractSeveral studies have reported that short‐term thyroid replacement to the euthyroid state in hypothyroid patients produces loss of both cortical and trabecular bone. However, long‐term follow‐up studies on this subject have not been reported. We conducted a 3 year follow‐up study on 35 white male patients, including 24 patients (groups 1 and 2) with hypothyroidism receiving thyroid hormone replacement to the euthyroid state and 11 patients (groups 3 and 4) with Graves' disease. The bone mineral content of the distal radius was determined by single‐photon absorption techniques with an iodine 125 source. It was found that there was no statistically significant difference in bone mineral content by year for any group, indicating no evidence of significant loss of cortical bone mineral by thyroid hormone replacement to the euthyroid state in hypothyroid

ISSN:0884-0431    

DOI:10.1002/jbmr.5650050507

出版商:John Wiley and Sons and The American Society for Bone and Mineral Research (ASBMR)    

年代:1990

数据来源: WILEY

摘要:

AbstractTo determine if chronic hypophosphatemia causes myocardial dysfunction, we explored one model for this metabolic derangement by prospectively investigating 11 patients (aged 5‐18 years) with X‐linked hypophosphatemic rickets (XLH) by M‐mode, two‐dimensional, and Doppler echocardiography. Inorganic phosphate and calcitriol (1,25‐dihydroxyvitamin D3) treatment was withheld 72 h prior to study.None of the patients had cardiovascular symptoms. Fasting serum inorganic phosphate concentrations were subnormal in all: 2.6 + 0.5 mg/dl (SD). Serum total and ionized calcium, magnesium, sodium, potassium, and creatine kinase myocardial fraction (CK‐MB) levels were unremarkable. Electrocardiograms revealed early repolarization abnormalities in 3 of the 11 patients: 1 had significant QT prolongation (corrected for heart rate), and 2 had T wave abnormalities. Exaggerated U waves occurred in 4 subjects. Resting echocardiograms were normal in 9 patients. In 1 subject there was mitral valve prolapse, and 1 patient possibly had an atrial septal defect (these findings were considered unrelated to hypophosphatemia). All M‐mode measurements were normal. The two‐dimensionally derived end‐diastolic and end‐systolic left ventricular volumes were 60.3 + 18.0 and 20.5 + 6.9 ml, respectively. Left ventricular ejection fraction was 66.1 + 4.7%, and the cardiac index by Doppler study was 4.1 + 0.8 liters/min per m2(both values were within normal limits).Although the precise pathogenesis of XLH is unknown and our findings suggest that some electrocardiographic abnormalities may be common in this disorder, we found no evidence for left ventricular dysfunction in this human model of clinically significant long‐stan

ISSN:0884-0431    

DOI:10.1002/jbmr.5650050508

出版商:John Wiley and Sons and The American Society for Bone and Mineral Research (ASBMR)    

年代:1990

数据来源: WILEY

摘要:

AbstractSince plasma calcium levels are higher in the fetus than in the mother at the end of gestation, it has been suggested that calcitonin (CT) biosynthesis would be very active in the fetus. This hypothesis was tested in rabbit fetuses and newborns by measuring the amount of CT mRNAs found in the thyroid glands and the thyroidal CT stores. Dot‐blot and Northern hybridizations with a specific CT cDNA probe (aBglII‐NsiIfragment of the human CT cDNA) were used to determine the CT mRNA level. In fetuses, newborns, and mothers, only one molecular species of mRNA around 1 kb was detected by Northern hybridization with the specific CT cDNA probe. By dot‐blot, CT mRNAs could be detected at 20 days of gestation on pooled fetal thyroid glands as a weak positive signal. The amount of CT mRNAs increased on day 24; at this stage they were also observed by Northern hybridization. During the last 6 days of gestation a 3‐fold increase in CT mRNAs occurred in rabbit fetuses; concomitantly a 5‐fold rise in the total thyroidal CT content was observed. Fetal plasma concentrations of both CT and calcium increased slightly between 24 and 30 days of gestation. After birth, the CT mRNA level was 10‐fold increased between 2 and 30 days; these changes were not reflected in the plasma CT level but were probably accounted for by a rise in the number of C cells of the th

ISSN:0884-0431    

DOI:10.1002/jbmr.5650050509

出版商:John Wiley and Sons and The American Society for Bone and Mineral Research (ASBMR)    

年代:1990

数据来源: WILEY

摘要:

AbstractThis study examined the effects of aminohydroxybutylidene bisphosphonate in 30 patients with Paget's disease of bone, administered as an intravenous infusion for 5 consecutive days. Treatment (5 mg IV daily) induced marked suppression of biochemical indices of disease activity. Urinary excretion of hydroxyproline fell to 50% of pretreatment values within 2 weeks and was followed by a similar, but later, decline in the serum activity of alkaline phosphatase. Disease activity remained suppressed throughout the 6 months of observation, and only 1 patient showed biochemical signs of an early relapse. Symptomatic improvement was noted in 27 of the 30 patients. Bone biopsies, undertaken in 10 patients, indicated no adverse effects on mineralization. Transient falls were noted in the total white cell count, particularly the lymphocyte and neutrophi1 fractions, and were associated with short‐lived fever in 3 patients. We conclude that short courses of intravenous AHButBP provide a promising treatment for active Paget's disease of bon

ISSN:0884-0431    

DOI:10.1002/jbmr.5650050510

出版商:John Wiley and Sons and The American Society for Bone and Mineral Research (ASBMR)    

年代:1990

数据来源: WILEY

摘要:

AbstractChildren with monostotic and polyostotic bone dysplasias often exhibit localized bone overgrowth. We investigated the presence of nuclear estrogen and nuclear progesterone receptors by solid‐phase radioimmunoassay, immunocytochemistry, and radioligand binding in osteoblast cell cultures derived from the areas of overgrowth of membranous bone, noninvolved membranous bone, and normal membranous bone from children undergoing elective craniotomy. Membranous bone of normal children had demonstrable levels of nuclear estrogen and progesterone receptors identified by radioimmunoassay and immunocytochemical assay. Two‐ to threefold increased levels of these receptors (p<0.001 versus normals) were found in cultures derived from the involved bone of two children with monostotic fibrous dysplasia and in one patient with polyostotic dysplasia (McCune‐Albright syndrome). The noninvolved bone in our patients with fibrous dysplasia exhibited nuclear sex steroid hormone receptor levels similar to those in the normal children. Radioligand binding studies demonstrated increased sex steroid hormone receptors in cultures derived from involved osteoblasts. The presence of an increased level of sex steroid hormone receptor was accompanied by increased alkaline phosphatase activity and increased production of osteocalcin in vitro compared to normal or noninvolved bone. The mechanisms by which sex steroid hormone receptor levels are increased in the ostotic dysplasias remain to be establ

ISSN:0884-0431    

DOI:10.1002/jbmr.5650050511

出版商:John Wiley and Sons and The American Society for Bone and Mineral Research (ASBMR)    

年代:1990

数据来源: WILEY