bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bone histomorphometry of renal osteodystrophy in diabetic patients
Authors: Andress Dennis L. , Hercz Gavril , Kopp Jeffrey B. , Endres David B. , Norris Keith C. , Coburn Jack W. , Sherrard Donald J. 
Published: February 2010

Abstract
Bone biopsies and plasma parathyroid hormone (PTH) from 27 diabetic dialysis patients were compared to biopsies and PTH levels from matched patients without diabetes to determine if PTH has a role in preserving bone mass in diabetic renal osteodystrophy. Significantly lower values were present in the diabetic group for mineralized bone area (p &lt; 0.003), osteoblastic osteoid (p &lt; 0.01), resorptive surface (p &lt; 0.001), fibrosis (p &lt; 0.005), bone apposition rate (p &lt; 0.01), bone formation rate (BMU level) (p &lt; 0.04), and plasma PTH (p &lt; 0.05). Bone-surface aluminum was higher in the diabetic group (44 ± 5% vs. 20 ± 5%, p &lt; 0.005). Linear regression analysis revealed significant positive correlations of mineralized bone area with time on dialysis, bone formation rate, bone resorption, and PTH only in the group without diabetes. While both groups had significant positive correlations of PTH with osteoblastic osteoid and bone resorption, only in the nondiabetic group was there a positive correlation of PTH with bone apposition and bone formation rate (BMU level), observations suggesting that the lower bone formation in the diabetic patients may have arisen in part from a failure of PTH to promote bone mineralization. We conclude that relatively low PTH levels and high bone aluminum in diabetic patients with chronic renal failure may be responsible in part for low bone mass when compared to uremic patients without diabetes.
Effects of 1α,25- and 24R,25-dihydroxyvitamin D3 on aluminum-induced rickets in growing uremic rats
Authors: Vukičević Slobodan , Krempien Burkhard , Stavljenić Ana 
Published: February 2010

Abstract
Rats were subjected to a two-stage subtotal nephrectomy or sham operation, and treated with aluminum (Al) or both aluminum and vitamin D, metabolites for 5 weeks with a cumulative dose of 13.6 mg aluminum.
Animals were injected with 3H-thymidine and 3H-proline. The following analyses were performed: quantitative histology of tibial metaphyses and cytomorphometric electron microscopy of osteoclasts, quantitative (ICP-spectroscopy) and qualitative determination (histochemical staining) of aluminum within organs, and serum biochemistry (Ca, P, Mg, vitamin D3 metabolites, alkaline phosphatase, urea).
The following new facts of the aluminum-related bone disease became evident: (a) Application of aluminum to growing uremic rats induced rickets, whose major epiphyseal growth plate changes were 1α,25(OH)2D3-dependent. Addition of 1α,25(OH)2D3 prevented the formation of rachitic metaphysis, but failed to prevent osteoid accumulation on epiphyseal and metaphyseal trabecular surfaces. Moreover, calcitriol produced hyperosteoidosis and osteosclerosis in the same rats. Aluminum did not alter the function of osteoblasts, while osteoclasts seemed inactivated, (b) The development of rickets was associated with suppressed serum levels of 1,25(OH)2D3, reduced phosphorus level and the high content of aluminum in the bone, kidney, and liver. The addition of 24R,25(OH)2D3 markedly exaggerated the reduction of serum levels of calcitriol.
We suggested that aluminum induces rickets in growing uremic rats, which consists of two components: vitamin D refractory osteomalacia and 1α,25(OH)2D3-dependent epiphyseal growth plate changes.
An ultrastructural study on the multinucleation process of mouse alveolar macrophages induced by 1α,25-dihydroxyvitamin D3
Authors: Ejir Sadakazu , Segawa Akihisa , Miyaura Chisato , Abe Etsuko , Suda Tatsuo , Ozawa Hidehiro 
Published: February 2010

Abstract
The multinucleation process of isolated alveolar macrophages induced by 1α,25-dihydroxyvitamin D3 [1α,25(OH)2D3] was examined using a scanning electron microscope (SEM) and a transmission electron microscope (TEM).
At the beginning of culture, most of the macrophages were spherical in shape. During incubation with 1.2 × 10−8M 1α,25(OH)2D3, spreading macrophages appeared among the spherical macrophages, and they increased in number. Spreading macrophages extended many cytoplasmic processes toward adjacent macrophages, and interdigitations of these processes between those of neighboring cells were often seen. Two types of cell contact have been observed in the 1α,25(OH)2D3-treated cells. In some, cytoplasmic processes were put into the cytoplasm of the adjacent cells, where clathrinlike structures were observed at the inner membrane of the concave portion. In others, spreading macrophages occasionally came in contact with adjacent cells by a peripheral rim of their cytoplasm with gap junctions. Cytoplasmic continuity was rarely observed at the boundaries between the closely associated cells. The two types of cell contact were also found, though not frequently, in the untreated cells.
These results indicate that 1α,25(OH)2D3 promotes multinucleation of alveolar macrophages through spreading forms with the formation of gap junctions and the coated membrane invagination.
Actions of rat growth hormone-releasing factor and norepinephrine on cytosolic free calcium and inositol trisphosphate in rat C-cells
Authors: Dr. Fried Ronald M. , Tashjian Armen H. 
Published: February 2010

AbstractRat growth hormone-releasing factor (rGRF) and norepinephrine (NE) stimulate secretion of calcitonin (CT) and neurotensin (NT) from cultured C-cells. The mechanism by which these agents cause secretion has not been well studied. We have examined the actions of the CT and NT secretagogues rGRF and NE on cytosolic free calcium concentrations ([Ca2+]i) in the rat C-cell line rMTC 44-2. Because inositol trisphosphate (IP3) has been shown to cause release of intracellular calcium stores in several cell types, we have also examined the effects of rat GRF, NE, and increases in extracellular calcium on IP3 accumulation in rMTC 44-2 cells. Stimulation by 10−6M rGRF caused a biphasic response in [Ca2+]i consisting of a rapid spike to 136 ± 4% (mean ± SE) of basal [Ca2+]i. This increase in [Ca2+]i decayed to base line and then gradually increased to 173 ± 13% of basal [Ca2+]i. Stimulation by 10−6M NE gave a similar biphasic increase in [Ca2+]i. The increases in [Ca2+]i induced by both rGRF and NE were inhibited by pretreatment with EGTA or verapamil. rGRF, NE, and increasing concentrations of extracellular calcium, which all caused rapid increases in [Ca2+]i, failed to increase IP3 accumulation in rMTC 44-2 cells. These results suggest that rGRF- and NE-induced secretion in C-cells are mediated by changes in [Ca2+]i. These increases in [Ca2+]i appear to be generated by extracellular calcium influx rather than by release of intracellular calcium stores.
Detection of prefracture spinal osteoporosis using bone mineral absorptiometry
Authors: Ross Philip D. , Wasnich Richard D. , Vogel John M. 
Published: February 2010

Abstract
Bone mineral measurements have been criticized for their inability to clearly distinguish fracture and “non-fracture” populations. However, this failure is not unexpected, since some individuals in the “nonfracture” group have low bone mass and are at increased risk but have not yet experienced fractures. Although standard radiographs are not sensitive indicators of vertebral demineralization, they do identify some of the “prefracture” osteoporotic subpopulation within the nonfracture group. Prospective follow-up of 536 Japanese-American women demonstrated that 14 new spine fractures occurred in this prefracture osteoporosis group, whereas none occurred in the nonosteoporotic group (p ≤ 0.03). However, bone mineral content (BMC) measurements using photon absorptiometry were much more accurate than radiographs as indicators of spine fracture risk. BMC values were somewhat higher in the prefracture group than in those with existing fractures, but values for both groups were significantly lower than in nonosteoporotic patients even after adjusting for age, height, and weight (p &lt; 0.0001). The magnitude of the difference was proportional to the trabecular bone content of the measurement site; the differences were greatest for the os calcis and lumbar spine, smaller for the distal radius, and least for the proximal radius. The prevalence of spinal osteoporosis (including both fracture and prefracture cases) was inversely proportional to BMC (p &lt; 0.0001). Again, the relations were strongest for the os calcis and lumbar spine. These results indicate that BMC measurements are valid indicators of osteoporosis status, particularly when osteoporosis is defined to include both patients with existing fractures and those at increased risk for fractures. However, dual-photon spine BMC was adversely influenced by the presence of aortic calcification, arthritis, and other disease processes (p ≤ 0.0001).
Certain Vitamin D metabolites potentiate the expression of parathyroid hormone bioactivity
Authors: Bradbeer J.N. , Mehdizadeh S. , Fraher L.J. , Dr. Loveridge N. 
Published: February 2010

Abstract
With the development of a sensitive bioassay for the skeletal effects of parathyroid hormone (PTH), it has become possible to investigate the possible interaction between PTH and vitamin D3 metabolites. This assay is based on the stimulation of glucose-6-phosphate dehydrogenase (G6PD) activity in either the hypertrophic chondrocytes of the growth plate or the osteoblasts lining the metaphyseal trabeculae of rat metatarsals. The response to PTH is paralleled by the activity of dibutyryl cAMP. None of the vitamin D3 metabolites tested had any effect on enzyme activity when tested by themselves. However, both 1,25(OH)2D3 and 25(OH)D3 caused a dose-related potentiation of the response to PTH. Neither 1,24,25(OH)3D3 nor 1,25(OH)2D3 26,23-lactone potentiated the response to PTH. Because this potentiation of the response to PTH occurs after only 8 minutes, it is suggested that it represents a nongenomic response to the vitamin D3 metabolites.
Effect of prostaglandin F2alpha on human parathyroid adenomas: Evidence for uncoupling of parathyroid hormone secretion and cAMP accumulation
Authors: Fitzpatrick Lorraine A. , Martin Cathryn , Sharp Mark , Aurbach Gerald D. , Norton Jeffrey 
Published: February 2010

Abstract
Human parathyroid adenomas are aberrantly regulated by extracellular calcium. We tested pertussis toxin, which ADP-ribosylates and inactivates several guanine nucleotide regulatory proteins, to test the role of these proteins in the secretory control of adenomatous parathyroid tissue. Pertussis toxin did not affect basal cAMP accumulation in 12 adenomas and enhanced parathyroid hormone (PTH) release in 6 of 10 adenomas. Prostaglandin F2alpha (PGF2alpha) inhibited cAMP in three of six adenomas, and pertussis toxin pretreatment did not affect this result. PTH release in 7 of 10 adenomas was inhibited by PGF2alpha and pertussis toxin did not significantly alter PTH release. Pertussis toxin catalyzed ADP-ribosylation of a 40-kDa protein in all adenomas tested (n = 8). We conclude that cAMP accumulation was not affected by pertussis toxin but that in 6 of 10 adenomas, the toxin enhanced PTH release. We suggest that cAMP accumulation and PTH release may be uncoupled from negative control by inhibitory ligands in adenomatous tissue or that the G-proteins involved do not couple to regulatory receptors or to effector.
Osteoclasts in human osteopetrosis contain viral-nucleocapsid-like nuclear inclusions
Authors: Mills Barbara G. , Yabe Hiroo , Singer Frederick R. 
Published: February 2010

Abstract
We report the discovery of nuclear inclusions in the osteoclasts of three unrelated patients with benign osteopetrosis that resemble the osteoclast inclusions characteristic of Paget's disease of bone. These inclusions are morphologically and dimensionally identical to the nucleocapsids of a virus of the Paramyxoviridae family. Supporting a possible viral association with benign osteopetrosis is the observation of the presence of antigens of respiratory syncytial virus, measles virus, and/or mumps virus in the cells of all five patients whose paraffin-embedded bone specimens were tested. These included two patients whose osteoclasts contained nuclear inclusions. No patients with the malignant form of the disease have been studied. There is as yet no proof that a virus is causally related to human osteopetrosis even though a virus can produce an avian form of the disease.
Charged beads: Generation of bone and giant cells
Authors: Professor Krukowski Marilyn , Simmons David J. , Summerfield Anita , Osdoby Philip 
Published: February 2010

Abstract
Based on reports of electrically induced bone formation and findings that some materials used to promote bone ingrowth are stimulatory in bead form, the osteogenic potential of beads with different surface charges was examined. In this preliminary study, three types of Sephadex beads were injected into chick femora: type I, DEAE beads, positively charged; type II, CM beads, negatively charged; type III, G-25, uncharged. Beads were injected into the femoral midshaft, and after 3 days, 4 days, and 1 week, birds were sacrificed and femora were processed for histology. Type I beads: at 3 days, were surrounded by multinucleated giant cells; by 4 days, patches of bead-associated new bone were present along with giant cells; after 1 week, occasional bead-associated multinucleated cells were seen, but now most beads were surrounded by new intramedullary bone, forming an extensive bead-bone lattice. With bead types II and III, bead-associated new bone was seen at 3 days and 4 days only when beads lodged near the endosteum or in the metaphysis. At 7 days, no bone was seen with either of these two bead types. The response to the type I beads may be likened to a remodeling phenomenon with large numbers of giant cells at 3 days, new bone and giant cells at 4 days, and evidence only of bone formation at 7 days.
Sequential bone mineral content in small preterm infants with and without fractures and rickets
Authors: Dr. Koo Winston W.K. , Sherman Roberta , Succop Paul , Oestreich Alan E. , Tsang Reginald C. , Krug-Wispe Susan K. , Steichen Jean J. 
Published: February 2010

Abstract
Seventy-four infants with birth weights 1009 ± 28 grams and gestational age 28.6 ± 0.3 weeks (M ± SEM) were studied prospectively to test the hypotheses that bone mineral content (BMC) measured by photon absorptiometry, would be: (1) lower in very low birth weight (VLBW) infants with radiographic evidence of fractures and/or rickets (F/R), and (2) will continue to be lower over the first year when compared to VLBW infants without F/R. BMC and bone width (BW) of the distal one-third of left radius and ulna were measured at 5 weeks (n = 8), 14 weeks (n = 61), 26 weeks (n = 58), 40 weeks (n = 59), and 1 year (n = 52). Standardized radiographs of both forearms, and weight, length, and head circumferencce were also determined at each study age. Investigators and technicians involved in the photon absorptiometry measurements were unaware of the radiographic findings and vice versa. Twenty-three of 74 infants were found to have F/R. BMC of studied infants remained markedly below our previously determined range of “intrauterine bone mineralization,” even at 26 weeks after birth. There was no significant difference in BMC or BW between infants with and without F/R, either at the time of confirmation of F/R or during early follow-up; however, BMC was lower at ≥6 months and BW was lower at ≥9 months in infants with F/R. We suggest that the extremely low BMC measurements in early infancy predispose all VLBW infants to fractures and rickets.
Effect of parathyroid hormone on amino acid transport by cultured neonatal mouse calvarial bone cells
Authors: Yee John A. 
Published: February 2010

Abstract
The effect of synthetic bovine parathyroid hormone [bPTH-(1–34)] on amino acid uptake by confluent primary cultures of osteoblast-like cells isolated from neonatal mouse calvaria was studied. The uptake of proline and leucine by membrane transport Systems A, ASC, and L was discriminated on the basis of their sodium dependency and sensitivity to the system-specific amino acid analogs 2-(methylamino)-isobutyric acid (MeAIB) for System A and 2-amino-(2,2,1)-heptane-2-carboxylic acid (BCH) for System L. Treatment with 24 nM bPTH-(1–34) in serum-free EBSS for 4 hr increased the initial uptake rate of proline by 50–80% but had no effect on the uptake of leucine. Temporally, the increase in proline uptake was preceded by a 2-hr lag period and plateaued after 5–6 hr. A 5-min exposure to the hormone was sufficient to cause a significant increase in proline uptake measured 4 hr later. The magnitude of the increase was dose-related from 0.24 to 240 nM bPTH-(1–34), with the half-maximal effect occurring at 2.4 nM. Only the sodium-dependent, MeAIB-inhibitable component of proline uptake was elevated. Eadie-Hofstee analysis indicated that bPTH-(1–34) increased Vmax without changing the Km. Actinomycin D and cycloheximide prevented the hormone-stimulated increase, suggesting that RNA and protein synthesis were required. Treatment with either inhibitor alone caused a 30–35% decrease in proline transport that was not observed in the presence of bPTH-(1–34), indicating an effect not dependent on macromolecular synthesis. DBcAMP also increased proline uptake. Maximally effective concentrations of bPTH-(1–34) and DBcAMP did not increase transport above the level of bPTH-(1–34) alone. These results confirm that PTH and DBcAMP increase amino acid uptake in bone. In addition, they (1) identify osteoblast-like cells as targets for this action of PTH, (2) demonstrate that the effect is on amino acid transport System A, (3) suggest that the rise in proline uptake is a direct action of PTH that may involve effects on both synthesis and degradation of System A transport proteins, and (4) indicate that the effect may be mediated by cAMP.
The effects of transplantation of granulocyte-macrophage progenitors on bone resorption in osteopetrotic rats
Authors: Dr. Schneider G.B. , Relfson M. 
Published: February 2010

Abstract
Osteopetrosis in the ia (incisors absent) rat is the result of reduced bone resorption due to abnormal osteoclasts. This mutant and others have been used to determine the precursor(s) to osteoclasts. Hemopoietic stem cells, isolated from bone marrow of normal littermates, cure the skeletal sclerosis and result in the formation of normal osteoclasts when transplanted into ia rats. These studies were conducted to define further the precursor to the osteoclast by evaluating the effects of the transplantation of granulocyte-macrophage progenitors on bone resorption in the ia rat. Granulocyte-colony forming cells (G-CFC), granulocyte-macrophage-colony forming cells (GM-CFC), and macrophage-colony forming cells (M-CFC) were isolated from normal bone marrow using an FITC-labeled monoclonal antibody directed against rat Thy-1.1 and fluorescence-activated cell sorting. The isolates were evaluated in soft agar culture; granulocyte isolates generated 71% G-CFC of all colonies formed and were enhanced 27 times over unfractionated cells. Mixed isolates generated 57% GM-CFC of all colonies formed and were 15 times enhanced, while macrophage isolates were 75% M-CFC with an enhancement factor of 18. The isolated populations were injected into 3-week-old ia recipients and evaluated for the ability of these cellular isolates to correct the bone resorption defect by measuring the size of the tibial marrow cavity and by identifying morphologically normal osteoclasts. In addition, isolated populations of cells were labeled with FITC and injected into ia donors to determine if labeled osteoclasts developed. G-CFC isolates, which apparently contained osteoclast precursors that were co-purified with the G-CFC, were effective in correcting the skeletal defect and giving rise to FITC-labeled osteoclasts; GM-CFC were intermediate in their effect; and M-CFC were ineffective in both curing the osteopetrotic condition and giving rise to labeled osteoclasts.
Properties of parathyroid hormone receptors on circulating bovine lymphocytes
Authors: Yamamoto Itsuo , Bringhurst F. Richard , Potts John T. , Segre Gino V. 
Published: February 2010

AbstractBinding of parathyroid hormone (PTH) to circulating bovine lymphocytes was studied using, as the radioligand, a synthetic sulfur-free analog of bovine PTH, [Nle8,Nle18,Tyr34]bPTH-(1–34)amide, which was labeled to high specific activity with 125I and was purified by reverse-phase high-performance liquid chromatography. Binding of PTH to lymphocytes satisfies several criteria indicative of a specific interaction between the hormone and its receptor. Specific binding is saturable at 3.3 fmoles of radioligand bound per 107 cells, occurs more rapidly at 37°C than at lower temperatures, and reaches equilibrium within 2 hr at 15°C. Inhibition of specific binding occurs with intact PTH, with biologically active PTH analog or fragment, and with synthetic PTH antagonists, but not with biologically inactive PTH fragments, or peptide hormones unrelated to PTH. There is an excellent correlation between the binding affinities of PTH agonists with receptors on lymphocytes and those previously reported with receptors in canine renal membranes, and on rat osteosarcoma cells. The dissociation constant (Kd) is approximately 10−9M, as calculated from the association and dissociation rate constants. This correlates very closely both with the apparent Kd, as estimated from Scatchard analysis of radioligand saturation and competition studies, and with previously reported Kd of PTH receptors in canine renal membranes and on intact rat osteosarcoma and opossum kidney cells. In addition, the relative binding affinity of intact hormone and a synthetic PTH agonist to receptors on lymphocytes correlates closely with the relative biologic potency of these peptides in stimulating adenylate cyclase in membranes from these cells. The presence of PTH specific receptors on lymphocytes is consistent with evidence suggesting that PTH-lymphocyte interactions may modulate bone resorption in vitro. Also, the ready accessibility of circulating lymphocytes may serve as a useful model system for examining PTH-receptor regulation in vivo.
Bone mineral content in the senescent rat femur: An assessment using single photon absorptiometry
Authors: Kiebzak Gary M. , Smith Ronald , Howe Juliette C. , Sacktor Bertram 
Published: February 2010

Abstract
The single photon absorptiometry technique was evaluated for measuring bone mineral content (BMC) of the excised femurs of the rat, and the system was used to examine the changes in cortical and trabecular bone from young adult (6 mo), mature adult (12 mo), and senescent (24 mo) male and female animals. BMC of the femur midshaft, representing cortical bone, apparently increased progressively with advancing age. The width of the femur at the scan site also increased with age. Normalizing the midshaft BMC by width partially compensated for the age-associated increase. However, when bone mineral values were normalized by the cortical area at the scan site, to take into account the geometric differences in the femurs of different aged animals, maximum bone densities were found in the mature adult and these values decreased slightly in the femurs from senescent rats. In contrast, the BMC of the femur distal metaphysis, representing trabecular bone, decreased markedly in the aged rat. The loss of trabecular bone was also evident from morphological examination of the distal metaphysis. These findings indicated that bone mineral loss with age was site specific in the rat femur. These studies provided additional evidence that the rat might serve as a useful animal model for specific experiments related to the pathogenesis of age-associated osteopenia.