ISSN:0736-0266    

DOI:10.1002/jor.1100020101

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractWe measured erythrocyte, plasma, osteocyte, extravascular extracellular, and total water fluid spaces and calculated their K content in cortical bone of dogs of various age. Total and exchangeable K were measured by atomic absorption spectroscopy and by volume of distribution techniques, respectively. All fluid spaces in bone decreased with increasing age of the dogs. The total and exchangeable K contents of cortical bone and the K content calculated from the fluid spaces were within the same range in each age group. These values all fell with increasing age.

ISSN:0736-0266    

DOI:10.1002/jor.1100020102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractTo explore the changes in the relationship between skeletal and Ca2+homeostasis with age, we studied 50 dogs divided into four age groups. The skeletal uptake of85Sr decreased markedly with age, and the immunoreactive parathyroid hormone (iPTH) level increased. There was a significant correlation between iPTH value and the calculated short‐term exchange of Ca in bone (r = −0.55; p<0.001). Bone formation and bone resorption decreased with age except that in the oldest group of dogs the resorption increased (p<0.001). We suggest that in aging dogs the skeletal exchange of Ca falls to a very low level that decreases the immediate effect of PTH and thus leads to a chronic net increase in circulating PTH. Concomitant with this is an increase in osteoclastic bone resorption and, over a long time, loss of skeletal m

ISSN:0736-0266    

DOI:10.1002/jor.1100020103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractIsolated articular cartilage chondrocytes from 1‐ to 3‐week‐old male Holstein calf knee joints were formed into pellets containing 4 × 106isolated cells and were grown in tissue culture medium (minimum essential medium/NCTC 135) containing either 1 or 10% newborn calf serum (NBCS) in plastic Petri dishes in 5% CO2and air at 37°C in saturation humidity. On the 4th postisolation day either [35S]sulfate or [3H]thymidine was added to the medium, and the pellets were exposed for 24 h to capacitively coupled electrical fields (10, 100, 250, and 1,000 V peak‐to‐peak, 60 kHz, sine wave signals). The pellets were then harvested, dialyzed, hydrolyzed, and assayed for DNA, protein, [35S]sulfate incorporation, and [3H]thymidine incorporation. Results indicated that at 250 V peak‐to‐peak there was a statistically significant increase in [35S]sulfate in 1% NBCS and a statistically significant increase in [3H]thymidine in 10% NBCS. At potentials above or below 250 V no changes were noted. Thus, articular cartilage chondrocytes grown in pellet form can be stimulated to increase glycosaminoglycan synthesis or to increase cell proliferation by an appropriate capacitively coupled electrical field. The importance of the serum concentration in the medium in evaluation of biosynthesisi

ISSN:0736-0266    

DOI:10.1002/jor.1100020104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractAsymmetrical pulsing low voltage current was supplied via electrodes to cultured rat fracture callus cells and human peripheral blood lymphocytes. The [3H]thymidine incorporation of the callus cells and 5‐[125I]iodo‐2′‐deoxyuridine incorporation of the lymphocytes were determined. The growth pattern of callus cells (estimated by cellular density) did not respond to electrical stimulation. However, the uptake of [3H]thymidine was increased at the early phase of cell proliferation and inhibited at later phases of proliferation. The [3H]thymidine uptake of confluent callus cell cultures did not respond to electrical stimulation. Lymphocytes reacted in a similar way; stimulated cells took up more DNA precursor than control cells at the early phase of stimulation. During cell division, induced by the mitogens phytohemagglutinin and Concanavalin‐A, the uptake of DNA precursor by stimulated cells was constantly inhibited. The results suggest that electrical stimuli affect the uptake mechanisms of cell membranes. The duality of the effect seems to be dependent on the c

ISSN:0736-0266    

DOI:10.1002/jor.1100020105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractAn experiment was undertaken to obtain approximate values for the intrinsic elastic modulus of subchondral bone. Shallow spherical caps, with uniform and incrementally controlled thickness, were machined from subchondral bone in the weight‐bearing regions of 11 fresh‐frozen normal femoral head autopsy specimens. Under application of polar point loads, the measured deflections were compared with a corresponding analytical shell solution, thus allowing back‐calculation of the apparent modulus. Analogous tests were performed on similarly shaped specimens of stock Plexiglas® of known modulus in order to estimate the precision of the testing method. The aggregate results for subchondral bone showed that its intrinsic stiffness correlated inversely with nominal shell thickness, but even the thinnest (1.0 mm thick) of these shells had an apparent modulus (mean = 1.372 GN/m2, SD = 414 MN/m2) well below that generally accepted for “pure” cortical bone (about 14 GN/m2). This stiffness deficit was very likely due to the presence of histologically evident marrow spaces. However, the low apparent modulus values measured in this study may not be fully representative of complexin vivobehavior, because in the testing of excised shells there is no radial compressive stress transfer to underlying cance

ISSN:0736-0266    

DOI:10.1002/jor.1100020106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractFlexor tendon healing in four different animal species was explored in a tissue culture system. Ninety percent transverse lacerations were made in 88 tendon segments obtained from rabbits, chickens, dogs, and monkeys. The tendons were removed from culture and studied by light and electron microscopy at intervals of 3, 6, 9, and 12 weeks. A characteristic sequence of repair including epitenon thickening, cellular differenctiation, cell migration, and phagocytosis was seen in each of the repaired tendons. The endotenon cells of several animal tendons appeared to be synthesizing collagen. There was a consistent difference in the rate of healing between the four species. The rabbit tendons demonstrated nearly complete closure of the repair site by 12 weeks. A lesser response was seen in the chicken, followed by the dog and monkey. The differences in healing rate appeared to be due to the non‐species‐specificin vitroculture media. Thein vitroflexor tendon culture system is particularly useful in studying the tendon repair responses of various species with the contributions of vascularity and synovial cells exclu

ISSN:0736-0266    

DOI:10.1002/jor.1100020107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractWe measured forces in the quadriceps tendon and ligamentum patellae in six human cadaver knee joints loaded through a range of flexion angles from 30 to 120°. Using standardized loads based on one‐sixth of maximum isometric quadriceps moments reported in human volunteers, we measured maximum average forces at 60° flexion of 532 N in the quadriceps tendon (FQ) and 470 N in the ligamentum patellae (FL). Linear extrapolation to full maximum extensor moments results in estimates of 3,200 N forFQand 2,800 N forFL. The force ration (FL/FQ) reached a maximum value of 1.27 at 30° and minimums of 0.7 at 90 and 120° knee flexion. Contrary to prevailing opinion, our results indicate that the patella is not a simple pulley that serves only to change the direction of equal forces in the quadriceps tendon and ligamentum patellae. Instead, the ratio of forces in these structures varies significantly with flexion angle. The ratio appears to be determined by the changing location of the patellofemoral contact area relative to the insertions of the tendon and ligament. These findings emphasize the biomechanical importance of patellar length and of the vertical dimensions and locations of the patellofemoral contact area. Attempts at surgical intervention for the treatment of disorders of the extensor apparatus should recognize these variations. Procedures that tend to move the contact area more proximally (at a particular flexion angle) will also tend to decrease theFL/FQ

ISSN:0736-0266    

DOI:10.1002/jor.1100020108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractViable articular cartilage from the medial femoral condyles of rabbits was storedin vitroin tissue culture medium with various additives and the same site of each specimen was mechanically tested sequentially throughout a 12‐day storage period. Indentation testing was performed with instantaneous and sustained loads. Preservation of sustained‐load carrying capacity was observed in the condyles stored with additives, indicating maintenance of an intact cartilage matrix. However, initial testing with small sustained loads (preload) showed changes not observed at higher load levels. The changes noted at small sustained initial loads may reflect alterations in cartilage surface structure and may be an early indicator of its mechanical integrity. Chondrocyte viability and proteoglycan content, as measured by35S incorporation and hexosamine concentration, were unchanged in comparison to fresh articular cartil

ISSN:0736-0266    

DOI:10.1002/jor.1100020109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractAn epidemiologic case‐control study undertaken in Connecticut during 1979–1981 indicated that persons with jobs requiring lifting objects of more than 11.3 kg (25 lb) an average of more than 25 times per day had over three times the risk for acute prolapsed lumbar intervertebral disc as people whose jobs did not involve lifting objects of this weight. If the body was usually twisted while the lifting was done, this elevation in risk was apparent with less frequent lifting. An especially high risk for prolapsed lumbar disc was associated with jobs involving lifting objects of more than 11.3 kg with the body usually twisted and the knees not bent while the lifting was done. Neither lifting objects of less than 11.3 kg nor twisting without lifting was associated with an increase in r

ISSN:0736-0266    

DOI:10.1002/jor.1100020110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY