bluuebunny/crossref_metadata_2025_split huggingface dataset:
Endothelin‐a receptors mediate vascular smooth‐muscle response to moderate acidosis in the canine tibial nutrient artery
Authors: Coessens Bruno C. , Miller Virginia M. , Wood Michael B. 
Published: February 2005

AbstractPerfusate pH may influence the tone of vascular smooth muscle by affecting the release of endothelium‐derived vasoactive factors or by directly modulating function of the smooth muscle. This study was designed to investigate the role of endothelium‐derived factors on acidosis‐induced responses of isolated canine tibial nutrient artery suspended in an organ chamber for the measurement of isometric contractile force. To investigate the specific role of the endothelium in half the rings, the endothelium was removed mechanically. Concentration‐response curves to KCl were obtained in the absence or presence of inhibition of two important endothelium‐derived relaxing factors, nitric oxide and prostacyclin, and an inhibitor of receptors for the endothelium‐derived contracting factor, endothelin‐1. Acidification of the perfusate from pH 7.45 to 7.0 significantly attenuated the contractions to KCl in arterial rings with endothelium (the mean of the effective concentration causing 50% of the maximal response for KCl at pH 7.45 and 7.0 was 12.31 ± 0.40 nM and 14.60 ± 0.55 nM, respectively). This difference was abolished by mechanical removal of the endothelium. In rings with endothelium, inhibition of nitric oxide or prostacyclin did not abolish the attenuation of KCl‐induced contractions occurring with acidosis (the mean of the effective concentration causing 50% of the maximal response for KCl at pH 7.45 and 7.0 was 11.18 ± 0.60 nM and 13.60 ± 0.60 nM, respectively). Inhibition of endothelin‐A receptors did not alter contractions to KCl at pH 7.45. However, the acidosisinduced attenuation of contractions with KCl was abolished by the endothelin‐A‐receptor antagonist BQ‐123 (the mean of the effective concentration causing 50% of the maximal response at pH 7.45 and 7.0 was 13.8 ± 1.34 nM and 13.2 ± 1.34 nM, respectively). These results suggest that acidosis‐induced relaxation of canine tibial nutrient artery is endothelium dependent and that activation of endothelin‐A receptors during acidosis is coupled to a release of an endothelium‐derived relaxing factor.
Long‐term study of the biochemistry and biomechanics of anterior cruciate ligament‐patellar tendon autografts in goats
Authors: Ng Gabriel Y. F. , Oakes Barry W. , Deacon Owen W. , McLean Iain D. , Eyre David R. 
Published: February 2005

AbstractThis study examined the change in type‐III collagen concentration and hydroxypyridinium crosslink density of anterior cruciate ligament‐patellar tendon autografts and their correlations with Young's modulus of the anterior cruciate autografts and anterior cruciate controls for as long as 3 years after surgery. Fifteen adult female goats (two control and 13 experimental) were tested. Each experimental animal received an anterior cruciate ligament‐patellar tendon autograft to the right knee. These animals were tested at 0 (n = 2), 6 (n = 2), 12 (n = 2), and 24 (n = 1) weeks and 1 (n = 3) and 3 (n = 3) years after surgery. After mechanical testing, the anterior cruciate autograft and control tissues were analysed for type‐III collagen concentration and hydroxypyridinium crosslink density. The results of sodium dodecyl sulfate gel electrophoresis showed a trend of initial increase in the percentage of type‐III collagen in the anterior cruciate ligament autografts and a subsequent decrease after 24 weeks following surgery. There was a nonsignificant (p > 0.05) negative correlation between type‐III collagen concentration and Young's modulus. The hydroxypyridinium crosslink density was highest at 1 year after surgery. There was a significant (p < 0.05) positive correlation between hydroxypyridinium crosslink density and Young's modulus in the anterior cruciate autografts and controls. This suggests that hydroxypyridinium crosslink density has a good linear relationship with the material strength of the anterior cruciate ligament autograft and hence could be used as an objective guide for rehabilitation with anterior cruciate autografts.
Migration of press‐fit cups fixed with poly‐L‐lactic acid or titanium screws: A randomized study using radiostereometry
Authors: Thanner J. , Kärrholm J. , Malchau H. , Herberts P. , Wallinder L. 
Published: February 2005

AbstractThe early migration of porous acetabular cups was studied in 43 patients with osteoarthrosis. The patients were randomly allocated to additional fixation of the cup with either biodegradable poly‐L‐lactic acid screws or titanium screws. Radiostereometric evaluation was done during the first 2 years after the procedure in 43 hips (23 with poly‐L‐lactic acid screws and 20 with titanium screws). At the 2‐year follow‐up, cups fixed with poly‐L‐lactic acid screws had migrated significantly more in the proximal‐distal (p < 0.05) and medial‐lateral (p < 0.05) directions. Cups with titanium screws displayed more pronounced rotations around the longitudinal axis (p < 0.05). Postoperatively, on the lateral view, there was an increased occurrence of radio‐lucencies at the dome of the cups fixed with poly‐L‐lactic acid screws (p < 0.05). The clinical result did not differ between the two groups. Inferior implant‐bone contact in the poly‐L‐lactic acid group, local changes of the bone quality, and diminishing support of the poly‐L‐lactic acid screws caused by their degradation with time could be reasons for the different pattern of migration observed.
Osteogenic potential of allogeneic rat marrow cells in porous hydroxyapatite ceramics: A histological study
Authors: Sempuku Takeo , Ohgushia Hajime , Okumur Motoaki , Tamai Susumu 
Published: February 2005

AbstractHydroxyapatite ceramics facilitate osteogenesis but cannot induce bone formation by themselves. We studied the feasibility of bone formation supported by allogeneic bone marrow cells in porous hydroxyapatite ceramics. Coralline hydroxyapatite discs were soaked in a marrow cell suspension harvested from either ACI (RT1a), Lewis (RT11), or Fischer 344 (RT11v) male rats, and these discs were implanted subcutaneously into 56 male Fischer 344 rats. FK‐506 (tacrolimus hydrate), an immunosuppressant, or saline was injected intramuscularly into the recipients every day for 2 weeks after surgery, and additional injections were given to 19 of the rats every 2 days for 2 more weeks. Neither of the mismatched major (ACI rat) or minor (Lewis rat) marrow cell transplants showed any bone formation without administration of FK‐506. However, in rats treated with FK‐506, bone formed in the pores of all the three types of ceramics implanted, which each contained the marrow cells from one of the three kinds of rats used. There were no differences among the three groups of donors with regard to the bone formation ratio. We previously reported that subcutaneous implantation of porous hydroxyapatite combined with isogeneic marrow cells resulted in consistent bone formation, even at ectopic sites. Since it would be difficult to harvest a large number of autologous marrow cells in clinical cases, we attempted to use allogeneic marrow cells and have shown the allogeneic murine marrow cells to have osteogenic potential.
Effect of human adrenomedullin on a canine tibial perfusion model in the absence of vascular endothelium
Authors: Kato Teiji , Bishop Allen T. , Wood Michael B. 
Published: February 2005

AbstractThe effect of human adrenomedullin was investigated using an ex vivo perfused canine tibial model in the absence of vascular endothelium. Adrenomedullin is a novel peptide with known vasodilator properties. In this model. a 0.1 ml bolus injection of 10−5 M of either acetylcholine or adrenomedullin decreased vascular resistance in tibial preparations precontracted with prostaglandin F2α by 88.3 ± 3.0% and 92.8 ± 2.8%, respectively, in the presence of vascular endothelium. Conversely, a 0.1 ml bolus injection of 10−5 M acetylcholine produced a constrictor response after removal of vascular endothelium. A 0.1 ml bolus injection of 10−5 M adrenomedullin decreased the baseline perfusion pressure in a dose‐dependent manner for a duration of 20 minutes and also attenuated the pressor response to exogenous norepinephrine injection for at least 10 minutes compared with the control study (p < 0.05) in the absence of vascular endothelium. These data suggest that human adrenomedullin relaxes blood vessels in bone by a direct action on vascular smooth‐muscle cells. In addition, the attenuation effect of human adrenomedullin on pressor responses to exogenous norepinephrine injection is independent of vascular endothelium.
Technique for generating submicrometer ultra high molecular weight polyethylene particles
Authors: Shanbhag Arun S. , Hasselman Carl T. , Rubash Harry E. 
Published: February 2005

AbstractUltra high molecular weight polyethylene wear debris is believed to have a major role in aseptic loosening of prosthetic joints. In order to study the cellular and host response to this and other such particulate debris, a source of fine ultra high molecular weight polyethylene debris is needed. We have described a technique to fracture the GUR 4150 primary ultra high molecular weight polyethylene grain, which reproducibly generated particles less than 1 μm in size. Furthermore, the particle morphology was similar to that of ultra high molecular weight polyethylene particles generated in vivo and retrieved from interfacial tissues. The fabricatd polyethylene particls ranged from 0.1 to 33 μm in diameter, with a mean of 2.3 ± 0.2 μm. Sixty percent of the particles were smaller than 1 μm and 90% were smaller than 7 μm. Using filtration and sedimentation, it is possible to acquire finer particle fractions. These particles are currently being used for biological response studies.
Human monocyte/macrophage response to cobalt‐chromium corrosion products and titanium particles in patients with total joint replacements
Authors: Lee S‐H. , Brennan F. R. , Jacobs J. J. , Urban R. M. , Ragasa D. R. , Glant T. T. 
Published: February 2005

AbstractThe responses of human peripheral blood monocytes of 10 normal volounteers and 14 patients with total hip replacements to particles of commercially pure titanium and chromium orthphosphate (a corrosion product from cobalt‐chromium alloy implants) were studied. In addition, these phagocytosable particles were added to cultured mononuclear cells isolated from the interfacial membrane of 14 patients with failed implants. Peripheral blood monocytes from patients who had had a total hip replacement produced significantly higher levels of interleukin‐1 (both interleukin‐1α and interleukin‐1β) and prostaglandin E2 follwing particulate stimulation than those from normal volunteers. Supernatants from both titanium and chromium orthophosphate‐stimulated peripheral blood monocytes from the volunteers and patients with total hip replacement induced bone resorption (assayed in organ cultures of newborn mouse calvariae)and the proliferation of human fibroblasts. The levels of bone resorption were significantly higher (p < 0.05) in patients with implants that in normal volunteers. There were no significant differences in the responses of cells between patients with focal osteolysis and those without osteolysis. Interfacial membrane mononuclear cells also produced high levels of interleukin‐1α, interleukin‐1β, and prostaglandin E2 and expressed bone resorptive activities following stimulation with either titanium or chromium orthophosphate. More importantly, interfacial membrane mononuclear cells “spontaneously” produced high levels of prostaglandin E2 that were comparable with the response of peripheral blood monocytes stimulated with particulate wear debris. The clinical relevance of this study is 2‐fold. First, mononuclear cells from patients with total hip replacement were some‐how “sensitized” to metal particles in comparison with mononuclear cells from individuals without an implant. Second, the chromium orthophosphate corrosion product was a potent macrophage/monocyte activator and may contribute to macrophage‐mediated osteolysis and aseptic loosening.
Effects of ionizing radiation on the mechanical properties of human bone
Authors: Currey John D. , Foreman James , Laketić Ira , Mitchell Julie , Pegg David E. , Reilly Gwendolen C. 
Published: February 2005

AbstractAllogeneic bone grafts are frequently sterilized by means of ionizing radiation. We investigated the effects of ionizing radiation on both quasistatic and impact mechanical properties of human bone. Specimens from four paired femora of four donors received doses of 29.5 kGy (“Standard” frequently used by tissue bandks), 94.7 kGy (“high”) or 17 kGy (“low”) of ionizing radiation. Young's modulus was unchanged by any level of radiation. Radiation significantly reduced bending strength, work to fracture, and impact energy absorption; in each case, the severity of the effect increased from low to standard to high doses of radiation. Work to fracture was particularly severely degraded; specimens irradiated with the high dose absorbed only 5% of the energy of the controls. Radiation. even at relatively low doses, makes the bone more brittle and thereby reduces its energy‐absorbing capacity. We suggest that because the level of radiation required to produce an acceptable level of viral inactivation (90 kGy) produces an unacceptable reduction in the mechanical integrity of the bone. low levels of radiation, sufficient to produce bacterial safety, should be used in conjunction with biological tests to ensure viral safety.
Comparison of the fixation of subcapital femoral neck osteotomies with absorbable self‐reinfoced poly‐L‐lactide lag‐screws or metallic screws in sheep
Authors: Jukkala‐Partio Kirsi , Laitinen Outi , Partio Esa K. , Vasenius Jarkko , Vainionpää Seppo , Pohjonen Timo , Törmälä Pertti , Rokkanen Pentti 
Published: February 2005

AbstractSeven subcapital femoral osteotomies of adult sheep were each fixed with two absorbable selfreinforced poly‐L‐lactide lag‐screws, and seven other osteotomies were each fixed with two metallic cancellous bone screws. At 3 and 12 weeks, radiographs were taken and callus formation, displacement, and union were evaluated. At 12 weeks, the animals were killed and strength measurements were carried out. According to the radiographs, union was achieved in six of seven osteotomies in both groups, while after 3 weeks one fixation in both the group treated with absorbable screws and the group treated with metallic screws had failed. There were no statistical differences between the groups with respect to callus formation or displacement. Regarding the strength of the ostecotomized bones, at 12 weeks there were no statistically significant differences in the load‐carrying capacity between the bones fixed with self‐reinforecd poly‐L‐lactide screws and those fixed with metallic screws. These results showed that self‐reinforced poly‐L‐lactide screws, which have been used successfully in fractures and osteotomies in cancellous bone, are strong enough to support this more demanding fixation of weight‐bearing bones.
Calcitonin gene‐related peptide, substance P, and tyrosine hydroxylase‐immunoreactive innervation of rat bone marrows: An immunohistochemical and ultrastructural investigation on possible efferent and afferent mechanisms
Authors: Imai Shinji , Tokunaga Yoshimitsu , Maeda Toshihiro , Kikkawa Masanori , Hukuda Sinsuke 
Published: February 2005

AbstractThe presence of nerve fibers in bone marrow has been noted by various investigators, and recent developments in immunohistochemistry have enabled differential localization of the intramedullary nerve fibers. Much interest has been devoted to the efferent activities of the afferent fibers, which probably act on the target tissues by secreting a variety of neurotransmitters. The present study aimed to further characterize intramedullary substance P, calcitonin gene‐related peptide, and tyrosine hydroxylase‐immunoreactive nerve fibers of the rat lower limb by comparing those of the knee, ankle, and tarsal joints. The ultrastructural details of intramedullary calcitonin gene‐related peptide‐immunoreactive axons were also investigated to provide a morphological basis for their possible efferent actions. Intramedullary calcitonin gene‐related peptide and substance P‐immunoreactive fibers in the proximal tibia and the knee joint were found to be as reported earlier, but the marrow of the distal metaphysis was also noted to be richly innervated, and the tarsal joints displayed dense innervation at the subchondral regions that underlie the joint cartilage. The articular and intramedullary innervations that function for joint protection might participate in characteristic clinical features of joint damage secondary to the neuropathies. Ultrastructurally, the intramedullary calcitonin gene‐related peptide‐immunoreactive axons were minimally engulfed by the Schwann cell, and naked intramedullary calcitonic gene‐related peptide‐immunoreactive axons were noted along an extraordinarily long extension, suggesting much efferent activity.
Compressive strains at physiological frequencies influence the metabolism of chondrocytes seeded in agarose
Authors: Lee David A. , Bader Dan L. 
Published: February 2005

AbstractArticular cartilage is subjected to dynamic compressive loading that is known to influence chondrocyte metabolism. While the exact signalling mechanisms are unclear, it has been proposed that cell deformation plays a role and may stimulate a metabolic response through distinctive pathways. In this study, a well characterized model system in which chondrocytes are embedded in agarose was used to study the effect of dynamic cellular strain on three key metabolic processes, namely the synthesis of glycosaminoglycan, of DNA, and of total protein. Using a specially designed apparatus, 15% compressive strain amplitude was applied to agarose‐chondrocyte cylinders statically or dynamically over a range of frequencies (0.3‐3 Hz). Static and low‐frequency strain (0.3 Hz) inhibited the synthesis of glycosaminoglycan, while a frequency of 1 Hz stimulated synthesis. Static strain reduced the level of thymidine uptake, whereas dynamic strain at all frequencies induced an increase in chondrocyte proliferation. Incorporation of tritiated proline was suppressed by all strain regimens tested. The three parameters investigated were each influenced by the dynamic strain regimens in a distinct manner, implying that the signalling mechanisms involved are uncoupled.
Calcitonin gene‐related peptide and reperfusion injury
Authors: Allen Diane M. , Chen Long‐En , Seaber Anthony V. , Urbaniak James R. 
Published: February 2005

AbstractCalcitonin gene‐related peptide is a potent intrinsic vasodilator, can induce prostacyclin release, and may inhibit membrane lipid peroxidation. This study examines the effect of calcitonin gene‐related peptide on vessel diameters, capillary perfusion and contractile function of skeletal muscle after 4 or 5 hours of ischemia and during immediate reperfusion using the rat cremaster muscle model. Forty‐two male rats were used; half of these received 0.2 ml of 10−7 M calcitonin gene‐related peptide after 0, 15, and 30 minutes of reperfusion, while the other half received normal saline as a control. By means of intravital videomicroscopy, the diameters of 10 vessels per muscle were measured prior to ischemia and during reperfusion. The fluorescein filling area was determined at 15, 30, and 60 minutes of reperfusion. After 1 hour of reperfusion, muscle function was examined in vitro by quantifying the contractile response to electric field stimulation of the muscles in an organ bath system. There was a significant increase in the diameter of the arterioles, but not the small arteries, at every time point from 10 to 60 minutes of reperfusion. The fluorescein filling area was increased in treated muscles at every time point. Contractile function was not significantly preserved. In light of the ability of calcitonin gene‐related peptide to relieve vasospasm and improve capillary perfusion, it may be useful in reducing reperfusion injury in the future.
Biochemical and density assessment of the new bone in late remodeling after callus distraction
Authors: Lammens Johan , Aerssens Jeroen , Nijs Jos , Mokassa Luc , Dequeker Jan , Bouillon Roger , Fabry Guy 
Published: February 2005

AbstractBiochemical changes in a canine bone‐lengthening model were characterized 5 months after surgery. The mineral content and the total amount of EDTA‐extractable noncollagenous proteins, insulin‐like growth factor‐I, and osteocalcin were determined for the lengthened callus, and a gradient density fractionation analysis of bone powder particles was performed. The results were compared with two other areas of the lengthened tibia and one region of the contralateral tibia. The mineral and osteocalcin contents showed significant decreases, whereas the hydroxyproline concentration was significantly increased. Neither the insulinlike growth factor‐I content nor the concentration of EDTA‐extractable proteins was significantly different in any of the examined regions.
Small‐angle HeNe laser light scatter and the compressive modulus of articular cartilage
Authors: Kovach Ian S. , Athanasiou Kyriacos A. 
Published: February 2005

AbstractLight scattering is a widely used technique for probing the microarchitecture and interactions of biological materials and solutions. In this paper, we describe the use of this method in the study of articular cartilage. The experiments presented utilize small‐angle static scattering of HeNe laser light (632.8 nm) from 40 μm thick samples of cartilage taken from the superficial zone of baboon femoral condyle. The specimens were taken from a total of 26 sites in eight animals of various ages. In addition to measuring the dependence of the intensity of scattered light on scatter angle, we performed mechanical testing at the test sites using creep‐indentation techniques. The results from the optical and mechanical experiments were compared, and a significant correlation was noted between the average scatter angle and the compressive aggregate modulus. In addition, it was noted that the cartilage of skelelally immature animals had a smaller aggregate modulus and scattered to a higher average angle than the cartilage of skeletally mature animals. A quantitative theory was developed to explain the relation between mechanical and optical properties in terms of the degree of order in the spatial arrangement of the collagen fibers in cartilage.