Biomedical subjects
E Barth
Publications and source records attributed to E Barth.
Bone ingrowth into weight-bearing porous fiber titanium implants. Mechanical and biochemical correlations.
Bone ingrowth into weight-bearing porous fiber Ti-6Al-4V implants in rat tibias was assessed for the amount, composition, and mineralization rate 3, 12, and 26 weeks after implantation. The data were compared with the ipsi- and contralateral metaphyseal controls and related to the ultimate bending stresses of the distal bone/implant interfaces. From the 3rd to the 12th week there was rapid bone ingrowth and also marked decline in mineralization rate of the ingrowing bone. After 12 weeks the implants were macroscopically pervaded by bone. The ultimate bending stresses increased from the 3rd to the 12th week and reached 45% of that of controls after 26 weeks. There was a linear proportionality between the amount of bone ingrowth and interfacial strength but a curvilinear relationship between bone maturity in terms of calcium/hydroxyproline and calcium/phosphorous ratios and interfacial strength. Stepwise multiple regression analysis showed that the interfacial strength depends on the amount and the maturity of the ingrown bone. Compared with the calcium/hydroxyproline ratio, the calcium/phosphorous ratio was an unreliable predictor of interfacial strength.
Bioactive glass ceramic on titanium substrate: the effect of molybdenum as an intermediate bond coating.
Bioactive glass ceramic coatings have been proposed for cementless prosthetic fixation. However, a coating procedure that results in a bond of adequate strength with the metal substrate is one of several factors that has to be resolved. In this work a glass ceramic coating was plasma flame sprayed onto a titanium substrate with and without molybdenum as an intermediate bond coating. The higher bond strength of the compound (20 MN m-2) compared to the simple (6 MN m-2) coating could be due to an increased roughness offered by the molybdenum surface, and possibly improved chemical bonding to the glass ceramic.
Effects of acetylsalicylic acid and naproxen on the mechanical and biochemical properties of intact skin in rats.
Acetylsalicylic acid, ASA (150 mg/kg/12 h), and naproxen (20 mg/kg/12 h) were administered to young male rats for 9 and 18 days. The doses were set to provide serum concentrations comparable with anti-inflammatory steady state levels in humans. Mechanical tests were performed on skin from the back of the rats. The drugs did not affect the tensile strength of intact skin, nor were differences found in the dry weight or content and concentration of collagen in the skin. However, the rate of collagen synthesis decreased significantly during the study in the ASA treated rats. The naproxen, on the other hand, had no effect. The results may be interpreted as the ASA having an inhibitory effect both on the synthesis and degradation of collagen in skin.
Osteogenesis promoted by bone matrix combined with marrow. Titanium implants studied in rats.
We evaluated the bone-forming potential of isogeneic bone marrow combined with antigen-extracted, autolyzed allogeneic bone matrix (AAA bone a.m. Urist). The purpose of the experiment was to evaluate bone-inducing materials for application in orthopaedic devices designed for fixation by bone ingrowth into a porous surface. The bone-forming materials were packed into tubes of porous fiber titanium and placed in the back musculature of rats for 12 or 25 days. At 12 days the combination of bone marrow and AAA bone had produced more bone than marrow only. At 25 days, however, there was no difference. The bone-inducing materials produced substantial amounts of new bone, and may become an adjuvant for achieving fixation by bone ingrowth. In particular, a combination of AAA bone and marrow might enhance fixation at a very early postoperative stage.
Bone fixation of ceramic-coated and fiber titanium implants. A study in weight-bearing rats.
We compared the fixation of glass ceramic-coated titanium and fiber titanium implants using a simple weight-bearing model in rats. The chemical composition of the glass ceramic was similar to 45S5F Bioglass. One hundred and eight male Wistar rats were operated on. A segment of their right tibias was replaced by a disc-shaped implant with a central hole. A stable osteosynthesis was completed by means of an intramedullary nail and a tension band. Thirty-six rats received glass ceramic-coated and 36 fiber titanium implants. In 36 rats osteotomies were performed. All animals survived without complications until scheduled sacrifice at 3, 12 and 26 weeks, postoperatively. The ultimate bending moments of the fiber titanium-bone interfaces and the osteotomies increased with time, and approached the levels of the contralateral, intact tibias at the 12th and 26th week. Also, the ultimate bending stresses increased from the 3rd to 12th week. After 26 weeks the fiber titanium-bone interfaces had reached about 45 per cent, and the osteotomies about 75 per cent of the strength of the intact tibias. All the glass ceramic-coated implants were loose, and at 26 weeks there was no coating left.
Effect of cis-platinum on bone ingrowth into porous fiber titanium. Mechanical and biochemical correlations.
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[Epidemiology of focal chorioretinitis].
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Comparison of ceramic and titanium implants in cats.
The mechanical strengths of the bone-implant interfaces of titanium coated with glass ceramic and pure titanium implants were compared. The glass ceramic had a chemical composition similar to 45S5F Bioglass. Cylindrical implants were placed in feline femurs. Six weeks later the strength of the fixation was tested using pull-out tests. Energy dispersive X-ray microanalysis was applied to pursue any possible relationship between mechanical strength and changes in elemental composition at the bone-implant interface. The ultimate shearing force for the pure titanium implants was higher than for the implants coated with glass ceramic. Also, the glass ceramic coating was partly degraded by the tissues. Evidently, the mechanical properties of the glass ceramic to bone interface were governed by some sort of chemical reaction that implied transfer of elements from the implant to bone. It appears that this reaction eventually will destroy the coating which makes this kind of material unsuitable for prosthesis fixation.
Quantitative cell survival from growth curves following anti-neoplastic drug treatment.
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Surgical treatment of dislocations of the sternoclavicular joint.
Six patients with dislocation of the sternoclavicular joint are presented. Their main complaints were chronic recurrent spontaneous dislocation and local tenderness and discomfort during normal use of the shoulder. Two patients were treated according to Brown's modified procedure while four patients were operated with Burrow's technique. Ten weeks immobilization postoperatively is recommended to obtain a satisfactory result.
[Treatment of bacterial arthritis. A 16-years' material].
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Juxta-articular bone cyst.
Juxta-articular bone cyst was first described as a distinct clinical entity by Hicks in 1956 and called "intraosseous ganglion". Hitherto, some 150 similar cases have been described. The cyst, which is usually solitary, occurs in the epiphysis near a weight-bearing joint in middle-aged persons. It may cause persistent pain but is easily overlooked on ordinary X-rays. The histogenesis is uncertain. Six patients treated by thorough curettage and autologous bone transplantation are presented. All achieved immediate relief from pain. Some theoretical aspects concerning the histogenesis are discussed.
[Jejuno-ileal bypass in obesity].
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The effect of splenectomy on the appearance of specific antibody-forming cells in lungs of dogs after intravenous immunization with sheep erythrocytes.
Effector cells of both T-lymphocyte-mediated and B-lymphocyte-mediated immunity can be induced experimentally to appear in the lung. It is not known whether such effector lymphocytes arise from precursor cells resident in the lung or if they are recruited from systemic sources. Previous studies demonstrated that IV administration of sheep erythrocytes to dogs consistently resulted in the appearance of specific antibody-forming cells, B-cell effectors, in lavage preparations obtained from the lung. In the present study, experiments were performed to determine the mechanism of appearance of effector B-cells in the lung after IV immunization. Control, sham-operated, and splenectomized dogs were immunized IV with 10(10) sheep erythrocytes. The concentrations of antibody-forming cells appearing in lymphocytes obtained from the lung and from peripheral blood were measured during both the primary and the secondary immune responses. Control and sham-operated dogs developed high concentrations of antibody-forming cells in blood 5 days after immunization, but splenectomized dogs did not. Antibody-forming cells consistently appeared in substantial numbers in lymphocytes obtained by lavage from lungs of control and sham-operated animals, however, they failed to appear in lungs of animals which had undergone splenectomy. Similar results were obtained both after primary and after secondary IV immunization. The data indicate that in this model, namely after IV immunization, with sheep erythrocytes, pulmonary antibody-forming cells or their precursors are derived from systemic sources (spleen) via the circulating blood. The observations provide strong in vivo evidence that lung antibody-forming cells are not generated locally after IV priming and boosting. The results of the present study relate directly to the mechanism of appearance of antibody-forming cells in lungs after IV, not local immunization. The study defines and documents one mechanism by which immune effector cells can appear in lung tissue.
Endocrinological studies in patients with metastatic malignant testicular germ cell tumours.
In this study, various serum hormone levels were determined in patients with metastatic testicular germ cell tumours. Raised LH levels, due to a cross reaction with hCG in the radioimmunoassay, were observed in 20 out of 29 patients with active disease and were mainly caused by gonadotrophin production in the tumour tissue. Increased LH levels were frequently observed in the patients with non-seminomatous tumours, but were also found in 4 (out of 6) patients with metastatic seminoma. One should, however, preferably use a specific hCG radioimmunoassay in order to measure tumour hCG as a tumour marker with a high diagnostic accuracy. In patients with active disease despite ongoing combination chemotherapy which included LH suppressing medication, serum testosterone remained above 6 nmol/l in 11 out of 16 patients. These patients remained sexually potent, while testosterone values below 6 nmol/l usually were combined with sexual impotence in patients during combination chemotherapy. These data strongly suggest that the tumour hCG has a biological activity, stimulating the remaining testis to increased testosterone secretion in these patients. The serum E2-17 beta levels were slightly to moderately increased in half of the patients with metastatic disease. Markedly increased serum E2-17 beta levels (> 0.30 nmol/l) and very high prolactin values (> 32 micrograms/l) were observed only in patients with high LH levels (> 9.5 micrograms/l) and a large tumour burden. These observations indicate that E2-17 beta and prolactin determinations are of minor value for early detection of tumour manifestations. Serum FSH cannot serve as a tumour marker in patients with testicular germ cell tumours.
[Influence of salmon calcitonin on acute pancreatitis (author's transl)].
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