bluuebunny/crossref_metadata_2025_split huggingface dataset:
Giant cell formation in rabbit long-term bone marrow cultures: Immunological and functional studies
Authors: Dr. Horton M. A. , Rimmer E. F. , Chambers T. J. 
Published: February 2010

Abstract
A method for the long-term culture of rabbit newborn bone marrow has been developed. It is characterized by the rapid appearance of an adherent, adipocyte-containing stromal layer, proliferation of mature myeloid cells, and the formation of numerous, large multinucleate giant cells. By the combined use of morphological, immunological, and functional criteria these giant cells have been characterized as macrophage polykaryons and not osteoclastic giant cells. We conclude that long-term bone marrow culture in the rabbit favors the proliferation, maturation, and fusion of macrophage, but not osteoclast, precursors — new experimental models will have to be developed to enable the developmental biology of osteoclasts to be studied in the rabbit.
Activity of ornithine decarboxylase and creatine kinase in soft and hard tissue of vitamin D-deficient chicks following parenteral application of 1,25-dihydroxyvitamin D3 or 24R,25-dihydroxyvitamin D3
Authors: Ittel Thomas H. , Ross F. P. , Professor Norman Anthony W. 
Published: February 2010

AbstractWe investigated the stimulation of creatine kinase (CK) and ornithine decarboxylase (ODC) by 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] and 24R,25-dihydroxyvitamin D3 [24R,25(OH)2D3] in doses ranging from 1.625 to 6500 pmol in 4-week-old vitamin D-deficient chicks. Enzyme activities were monitored for 72 h. 1,25(OH)2D3 but not 24R,25(OH)2D3 enhanced the activity of ODC in duodenum and bone. The time course of ODC activity in bone was biphasic, with an increase after 1 h and a higher peak after 24 h. Diaphyses and epiphyses responded equally well after a dose of 6500 pmol. The kidney, liver, and lung showed 1.5–3.8-fold increase in CK activity following 1,25(OH)2D3, reaching a maximum between 3–5 h. However, sustained stimulation of CK activity could still be demonstrated after 72 h, and the 48-h levels in the lung even exceeded the 5-h values. No change of activity of either enzyme was noted in heart and brain after application of 1,25(OH)2D3. There was no coincidence of stimulation of ODC and CK by 1,25(OH)2D3 in the same tissue, and the dose-responsiveness of both enzymes differed considerably. Near maximum activities of ODC were achieved with 19.5 pmol 1,25(OH)2D3 in duodenum and pancreas, while maximum responses of CK occurred in the liver at 195 pmol and in lung and kidney at 6500 pmol. 24R,25(OH)2D3 failed to produce any consistent effects of either enzyme in all tissues examined. These results, particularly the lack of response to 24R,25(OH)2D3, are different from those reported in rats.
Renal adaptation to phosphorus deprivation: Characterization of early events
Authors: Dr. Levine Barton S. , Ho Letitia D. , Pasiecznik Karen , Coburn Jack W. 
Published: February 2010

AbstractRenal adaptation to low dietary phosphorus (P) can occur within 4 h. To characterize events preceding adaptation, rats were gavaged with 0.6% P (+P) or 0.03% P (-P) diet and killed 1, 2, or 4 h later. Brush border membrane vesicles were prepared and Na-dependent phosphate (Pi), glucose, and 1-proline transport were measured. In intact rats, 1 h after gavage, serum P in +P was 8.0 ± 0.5 and in -P, 6.1 ± 0.4 mg/dl, p &lt; 0.01. One and 2 h after gavage, Pi uptake was similar between groups; at 4 h, 0.25 min Pi uptake was increased by 59.3% ± 14.8 in -P, p &lt; 0.02, n = 11. In thyroparathyroidectomized rats, Pi uptake increased in -P by 40.1% ± 7.4 compared to +P at 2.5 h after gavage, and by 51.3 ± 9.3 at 4 h, p &lt; 0.025, n = 11. When actinomycin D or cycloheximide were administered both 16 h prior to and at gavage, 0.25 min Pi uptake 4 h after gavage was 59.1% ± 14 and 60.6% ± 19 higher in -P than +P, respectively, p &lt; 0.025. The adaptation was detected only when measured with an inward-directed Na-gradient. Na-dependent glucose and proline uptakes were not changed by -P diet.These studies demonstrate that early renal adaptation to low dietary P is preceded by a fall in serum P, is independent of parathyroid hormone, and does not require protein synthesis. Early adaptation may represent an increased rate of carrier movement or a change in availability of already synthesized carrier. The signal for adaptation may be the decrease in serum P, or filtered load of phosphorus.
Parathyroid hormone and calcitonin modify inositol phospholipid metabolism in fetal rat limb bones
Authors: Rappaport Mark S. , Dr. Stern Paula H. 
Published: February 2010

AbstractInositol-containing phospholipids are believed to be intimately involved in the first steps of cellular signalling by certain hormones and neurotransmitters. We examined whether parathyroid hormone (PTH) and calcitonin (CT), two hormones that affect bone physiology, would elicit changes in inositol-phospholipid metabolism in cultured bone. [3H]inositol readily entered into the tissue phospholipid pool in fetal rat limb bones, and incorporated into phosphatidylinositol (92.9%), phosphatidylinositol-4-P (4.5%), and phosphatidylinositol-4,5-P2 (2.6%). PTH enhanced the incorporation of inositol into PtdIns in limb bones following 2- or 24-h hormone treatments. The effect of PTH was dose dependent (EC50 of 0.3–0.4 nM) and occurred in a concentration range similar to that for hormone-stimulated bone resorption. In contrast, 24-h treatment with CT-inhibited inositol incorporation, also in a dose-dependent manner. Two-hour CT treatment had variable effects on labeling. CT inhibited the stimulatory effect of PTH at both 2 and 24 h. The effects induced by PTH and CT were specific for PtdIns and were independent of the [3H]inositol pool size. These results indicate that inositol-phospholipid turnover can be modified during the action of these hormones on bone tissue. Although the time course of hormone-stimulated inositol incorporation observed here is slower than that found in other tissues, the change in phosphatidylinositol metabolism could mediate delayed effects of PTH or CT. Alternatively, alterations induced by PTH and CT in bone cell membranes, cell populations, or in the mineralized matrix could conceivably result in secondary changes in phosphatidylinositol metabolism.
Skeletal response to dietary calcium in a rat model simulating weightlessness
Authors: Globus Ruth K. , Bikle Daniel D. , Halloran Bernard , Morey-Holton Emily 
Published: February 2010

Abstract
Unweighting the hindlimbs of a rat by tail suspension leads to a decrease in bone in the unweighted hindlimbs, but not in the normally weighted forelimbs. We evaluated whether increments in dietary calcium could prevent this. Growing rats were fed diets ranging in calcium content from 0.1% to 2.4%. After the rats were suspended for two weeks, we found no differences between suspended and control animals fed the same diet with respect to calcium transport or serum levels of calcium, phosphorus, 1,25-dihydroxyvitamin D, and parathyroid hormone. In both groups, increasing dietary calcium reduced active intestinal calcium transport and serum 1,25-dihydroxyvitamin D levels. The calcium content of the tibia and lumbar vertebra (but not the humerus) was reduced in suspended rats compared to control rats fed the same diet. However, increasing dietary calcium increased the calcium content of all bones in both suspended and control animals. The bone formation rate at the tibiofibular junction (measured by double-label tetracycline) was reduced in the suspended animals compared to controls and was not altered by dietary calcium. However, the marrow area of the tibia, an indication of bone resorption, did not differ between suspended and control animals and was equally reduced in both groups when dietary calcium was increased. Our data suggest that the deleterious effects of skeletal unweighting on bone formation cannot be explained by changes in the calciotropic hormones and are not reversed by increments in dietary calcium. However, increasing dietary calcium can increase bone calcium, even in unweighted limbs, by decreasing bone resorption.
Reduced bone mass in calcitonin-deficient rats whether lactating or not
Authors: Dr. Hirsch Philip F. , Hagaman John R. 
Published: February 2010

Abstract
Calcitonin deficiency was produced in lactating and age-matched nonmated rats by thyroidectomy (TX) after transplantation of the parathyroid glands to a thigh muscle. At the end of lactation and a comparable period in the nonlactating rats, this condition resulted in femurs, vertebrae, and tibiae that weighed less than those in the thyroid-intact controls. Furthermore, the femurs of the CT-deficient rats were narrower at midshaft and shorter, indicating reduced bone growth. The reduction in bone mass in CT-deficient rats, although highly significant, was much smaller than that caused by lactation.
Adequate thyroid hormone replacement therapy was provided by giving all the TX rats L-thyroxine (T4) sc or in the drinking water. The body weights of the lactating rats were heavier than those of their nonmated controls but TX had no significant effect on the mean body weight of either group. The previously observed lower concentration of serum calcium in lactating rats than in nonlactating thyroid-intact rats was also seen in TX rats, indicating that CT is not responsible for the relatively low serum calcium during lactation.
Our results showing that the bones of TX rats (with T4 replacement) were smaller and lighter than those from thyroid-intact controls whether lactating or not do not support the concept that CT has a special physiological function to protect the skeleton during lactation.
Differential effect of caffeine administration on calcium and vitamin D metabolism in young and adult rats
Authors: Yeh James K. , Aloia John F. 
Published: February 2010

Abstract
Since coffee drinking may lead to a worsening of calcium balance in humans, we studied the serial changes of serum calcium, PTH, 1,25-dihydroxyvitamin D (1,25(OH)2D) and calcium balance in young and adult rats after daily administration of caffeine for 4 weeks.
In the young rats, there was an increase in urinary calcium and endogenous fecal calcium excretion after four days of caffeine administration that persisted for the duration of the experiment. Serum calcium decreased on the fourth day of caffeine administration and then returned to control levels. In contrast, the serum PTH and 1,25(OH)2D remained unchanged initially, but increased after 2 weeks of caffeine administration. The intestinal absorption coefficient of calcium remained unchanged, instead of declining gradually as observed in the young control group. This finding suggests that the intestinal absorption of calcium was stimulated by the increase in 1,25(OH)2D production after chronic administration of caffeine.
In the adult rat group, an increase in the urinary calcium and endogenous fecal calcium excretion and serum levels of PTH was found after caffeine administration. However, the serum 1,25(OH)2D levels and intestinal absorption coefficient of calcium remained the same as in the adult control group. A decrease in the net balance of calcium occurred as a result of increased calcium excretion.
The current study, using an animal model, supports the suggestion that chronic administration of caffeine could lead to negative calcium balance when there is an impaired ability to increase the efficiency of calcium absorption. Such a situation exists in elderly human subjects, since they have a reduced capacity to synthesize 1,25(OH)2D.
Differential cyclic AMP responses to calcitonin among human ovarian carcinoma cell lines: A calcitonin-responsive line derived from a rare tumor type
Authors: Upchurch Katherine S. , Parker Leroy M. , Scully Robert E. , Krane Stephen M. 
Published: February 2010

Abstract
Several human tumor cell lines have been reported to have specific receptors for calcitonin (CT) and CT-responsive adenylate cyclase. In order to correlate patterns of responsiveness to CT, parathyroid hormone (PTH) and prostaglandin E2 (PGE2) with tumor morphology and intermediate filament protein expression, we examined four human ovarian tumor cell lines (BIN-16, BIN-22, BIN-53, BIN-67) which had been cultured from cells of metastatic foci. In two cell lines (BIN-53 and −16) there were small increases in cAMP content after exposure to CT and in three cell lines (BIN-53, −16, and −22) larger increases with PGE2. There was no cAMP response in any of the cells to PTH. In BIN-67 cells, however, CT induced a striking (&gt; 20-fold) increase in cAMP content. Histologically, the CT-nonresponsive tumor lines were derived from serous adenocarcinomas while the CT-responsive tumor line was from a rare small cell carcinoma. Gel electrophoretic and immunofluorescence microscopic analyses had previously disclosed that the CT-nonresponsive cell lines contained high levels of simple epithelial keratins and no or very low levels of vimentin (characteristic of ovarian surface epithelial cells), while the CT-responsive cell line contained almost exclusively vimentin. Thus, cells cultured from a rare type of ovarian tumor were CT-responsive and were distinguishable from CT-nonresponsive ovarian tumor cells by initial tumor histology and intermediate filament protein expression.
Alterations in hormone-sensitive adenylate cyclase of cloned rat osteosarcoma cells during long-term culture
Authors: Gutierrez Gloria E. , Mundy Gregory R. , Dr. Katz Michael S. 
Published: February 2010

Abstract
The hormone-sensitive adenylate cyclase system of a cloned bone cell line (UMR-106) derived from a rat osteosarcoma was compared in preparations from cells of early passages (&lt; 50) and cells maintained in continuous culture for over two years (late passages). Late passage cells showed greater calcitonin (CT)-stimulated adenylate cyclase activity than did early passages, whereas stimulation by PTH and the β-adrenergic agonist isoproterenol decreased in late passages. Hormone concentrations giving half-maximal stimulation were the same in early and late passages. Stimulation by agents (GTP and fluoride) which act at the stimulatory guanine nucleotide regulatory component (Ns) of adenylate cyclase was equivalent in early and late passages. Forskolin stimulation, which assessed catalytic component (and possibly Ns) activity, was reduced in late passages. These results are consistent with acquisition by cultured UMR-106 cells of CT receptors linked to adenylate cyclase and loss of PTH and β-adrenergic receptors. Alteration of catalytic component (and/or Ns) function may also occur after long-term culture. Since late passage cells appear dedifferentiated by chromosomal analysis and since cAMP may regulate differentiation, altered hormone-sensitive adenylate cyclase may be a marker for and a potential modulator of differentiation occurring in UMR-106 cells over long periods.
Limitations of forearm bone densitometry as an index of vertebral or femoral neck osteopenia
Authors: Pocock Nicholas A. , Dr. Eisman John A. , Yeates Michael G. , Sambrook Phillip N. , Eberl Stefan , Wren Barry G. 
Published: February 2010

Abstract
Osteoporosis of the spine and femoral neck is a major problem in aging populations, but detection prior to a fracture remains a challenge. Forearm bone mineral content has been advocated as a useful screening test in this situation. We have examined the correlation between distal forearm bone mineral content, by single photon absorptiometry, and lumbar vertebral and femoral neck bone mineral density, by dual photon absorptiometry. Eighty women aged 20 to 76 years were studied and significant correlations (p &lt; .001) were found between the measurements on the forearm and at the two axial sites (r = 0.66 and 0.69, respectively). However, forearm bone mineral content was an unreliable predictor of axial bone mineral density. For prediction of lumbar spine osteopenia with a sensitivity of 88%, the false positive rate was 91%. Conversely, to achieve a specificity of 82%, the false negative rate was 65%. Similarly, for prediction of femoral neck osteopenia at a sensitivity of 92%, the false positive rate was 87%, and at a specificity of 90%, the false negative rate was 33%. These data demonstrate that forearm bone densitometry cannot be used as a screening procedure for osteopenia of the lumbar spine or femoral neck.
In vivo hydroxyapatite formation induced by lipids
Authors: Raggio C.L. , Boyan B.D. , Dr. Boskey Adele L. 
Published: February 2010

Abstract
Proteolipids and complexed acidic phospholipids that cause in vitro hydroxyapatite formation, similarly cause hydroxyapatite deposition in 10-μ pore Millipore chambers when implanted in rabbit muscle pouches. The amount of mineral deposited during a 3-week period, based on the calcium and phosphate contents of the chambers, was directly related to the dry weight of the lipid implanted in the chamber. Chambers containing total lipid extract from rabbit bone from which the complexed acidic phospholipids had been removed, acidic phospholipids from which the the proteolipids had been removed, and empty chambers did not accumulate any detectable mineral during the course of the study. Chambers implanted with synthetic hydroxyapatite served as controls for chemical analyses. The presence of hydroxyapatite in the chambers was established 3 weeks after implantation based on electron microscopic, compositional, and wide-angle X-ray diffraction analyses of the deposits. In the cell-free chambers, lipid-induced hydroxyapatite deposition, but not bone matrix formation occurred. This study demonstrates that proteolipids and complexed acidic phospholipids can cause hydroxyapatite mineral deposition in a physiologic environment. To date, these lipids are the only materials isolated from mineralizing tissues, other than reconstituted collagen, that have been shown capable of causing in vivo mineralization in the absence of cells.
The effect of 1,25-dihydroxyvitamin D3 on the cytoskeleton of rat calvaria and rat osteosarcoma (ROS 17/2.8) osteoblastic cells
Authors: Dr. Gronowicz Gloria , Egan J.J. , Rodan G.A. 
Published: February 2010

Abstract1,25-dihydroxy vitamin D3 produces pronounced shape changes in fetal rat calvaria and osteosarcoma-derived (ROS 17/2.8) osteoblastic cells, characterized by retracting processes and cell rounding followed by aggregation of cells. The 1,25(OH)2D3 effect on ROS 17/2.8 morphology was determined morphometrically on scanning electron micrographs. The hormone effect was found to be dose dependent between 10−12 and 10−9M. The shape changes appeared 12 h after hormone (10−10M) addition and were present in 80% of the ROS 17/2.8 cells and in 50% of the calvaria cells at 72 h. Cycloheximide at 1 μM, inhibited the hormone-dependent change in morphology. The 1,25(OH)2D3 effects were partially mimicked by 10−8M 25(OH)D3 but not by 10−10M 25(OH)D3 or 10−11-10−8M 24,25(OH)2D3. 1,25-dihydroxy vitamin D3 also increased cell proliferation twofold at 14 days in serum-free medium.1,25(OH)2D3 treatment produced changes in microfilament organization, visualized with rhodamine-conjugated phalloidin. Microfilaments were localized at the terminal attachment points and in the perinuclear region, and few if any, were seen in the retracting processes themselves. Estimation of cytoskeletal actin and myosin by gel electrophoresis of Triton X-100 nonextractable proteins showed a 30% reduction in these proteins in the hormone-treated cells. Microtubules visualized by indirect immunofluorescence showed no major changes in organization. Both colchicine and cytochalasin D altered the hormone-induced shape change, suggesting that both microfilaments and microtubules were required for this process.Thus, 1,25(OH)2D3 had pronounced effects on cell shape in osteoblastic cells, probably via de novo protein synthesis. These changes lead to rearrangement of the cytoskeleton, primarily the microfilaments.
On the problem of covalent linkages between phosphoproteins and collagen in bovine dentin and bone
Authors: Dr. Glimcher Melvin J. , Lefteriou Beatrice , Kossiva Dora 
Published: February 2010

Abstract
The majority of phosphoproteins in bovine bone and dentin are insoluble in EDTA and guanidine hydrochloride (Gu · HCl) at 2°C. After removal of EDTA and Gu · HCl-soluble proteins at 2°C, collagen α-chains and α-chain polymers were extracted from bovine bone and dentin in Gu · HCl at elevated temperatures and purified by several chromatographic techniques and SDS-PAGE. Small amounts of O-phosphoserine were found in all collagen components. In contrast, O-phosphoserine was not detected in the purified collagen components soluble in EDTA or Gu · HCl at 2°C nor was hydroxyproline detected in the EDTA-soluble phosphoproteins. In contrast, although the vast majority of EDTA-insoluble collagen and phosphoprotein molecules can be readily dissociated by a variety of molecular sieving and ion-exchange chromatographic procedures, a small number are very strongly associated or covalently cross-linked. These results are consistent with the findings that both hydroxyproline and hydroxylysine are present in purified phosphoprotein components released from the EDTA-insoluble tissue by bacterial collagenase. The hydroxylysine/100 hydroxyproline ratios in the phosphoprotein-collagen complexes are much higher than those in dentin or bone collagens.
Serum osteocalcin (BGP) in tumor-associated hypercalcemia
Authors: Dr. Body J.J. , Cleeren A. , Pot M. , Borkowski A. 
Published: February 2010

Abstract
Serum osteocalcin (BGP) is a new marker of bone turnover that reportedly evaluates bone formation. Thus, its measurement could assess the bone formation rate in tumor-associated hypercalcemia. We measured concentrations of BGP and other parameters of bone metabolism in 54 untreated hypercalcemic cancer patients as compared to 109 healthy subjects. Primary tumor sites were breast (19), lung (11), head and neck (6), multiple myeloma (3), kidney (2), and various (11) or multiple (2). Mean BGP levels were higher in the hypercalcemic subjects, 4.6 ± 0.4 (SEM) ng/ml, than in the normal subjects, 3.6 + 0.1 ng/ml (p &lt; .05), and were normalized in the 22 patients who could be reevaluated after successful treatment of hypercalcemia with intravenous aminohydroxypropylidene diphosphonate (APD). There was no correlation of BGP levels with age, sex, or renal function. Compared with the Gaussian distribution in the normal subjects, there was a considerable scatter of the data in hypercalcemic patients, suggesting the existence of defined subgroups with abnormally low or abnormally high values. However, we found no significant relationship of BGP concentrations with tumor site or histology or with bone metastatic involvement. We found also no significant correlation between concentrations of serum BGP and total or ionized calcium, alkaline phosphatase, parameters of bone resorption, and indices of parathyroid function. In summary, serum BGP levels were slightly elevated in tumor-associated hypercalcemia and were normalized after successful treatment of hypercalcemia. More importantly, BGP concentrations varied widely even in the subgroups of patients with hypercalcemia accompanying massive bone metastatic involvement or in the patients without detectable skeletal metastases. Thus, BGP determination cannot help to differentiate between paraneoplastic hypercalcemia and hypercalcemia due to metastatic bone lysis; moreover, our findings suggest great variability of the bone formation rate in tumor-associated hypercalcemia, whether bone metastases are present or not.