Histomorphological, histomorphometrical and biomechanical analysis of ceramic bone substitutes in a weight-bearing animal model

It was the purpose of this investigation to prove the biomechanical properties, the osteoconductive capacity and the degradation rate of tricalcium phosphate ( TCP), a neutralized glass ceramics (GB9N) and a composite material (GB9N+copolymers). In a weight-bearing animal model six substitutes each were implanted in the medial tibial head of the right lower leg of adult Merino-sheep in a standardized surgical technique. After nine months the implants were harvested and prepared for histomorphological and histomorphometrical investigations (undecalcified Masson Goldner staining). For additional biomechanical testing of the specimens, non-operated bone blocks from the contralateral tibia as well as native implants served as controls. No significant differences for the maximum fracture load as well as for the yield strength were detected between harvested specimens and bone blocks from the contralateral tibia. However there were marked differences to ceramics that were not implanted. All substitutes showed osteoconduction, leading to a continuous ingrowth of new formed bone. However in the composite material soft tissue could be identified within the scaffold and there were signs of ongoing bone remodeling, nine months after implantation. The bone per tissue volume of -TCP in conjunction to new bone (=percentage of trabecular bone volume plus percentage of residual substitute) was higher than for GB9N and the composite material. Nine months after implantation the percentage of residual -TCP was 48%, it was 32% for GB9N and 28% for the composite.The intention of further studies should be to accelerate the degradation rates of substitutes and to improve biomechanical properties of implants by either modifying the chemical composition or combining materials with agents as, e.g. growth factors.     

Scoring prevalence and severity in gonarthritis: the suitability of the Kellgren & Lawrence scale

OBJECTIVES: Infection with the high-risk strain of human papillomaviruses (HPVs) and the inactivation of the tumor suppressor gene p53 through mutation are important factors in cervical carcinogenesis. To know whether such events would occur in cervical carcinomas of Indians, 43 tumors (consisting of 36 of stage III B and 6 of stage II B) were screened for p53 and p16 gene mutations. METHODS: PCR followed by single-strand conformation polymorphism (SSCP) analysis were used to detect mutations in p53 and p16 genes and PCR for the presence of human papillomavirus genome. HPV status was ascertained by PCR amplification of parts of E6 and E7 genes using primers pU-1M and pU-2R and typing was carried out by restriction analysis. RESULTS: Of the 43 samples analyzed, 4 samples (9%) showed mobility shifts for p53 mutations; PCR products of the p16 gene did not show band shifts in SSCP analysis. HPV DNA was detected in 70% of the 43 samples analyzed: HPV 16 in 23 cases (53%), HPV 18 in 4 cases (13.3%), and HPV 33 in 1 case (3.3%). Two amplified HPV DNAs that were difficult to type with various restriction enzymes were cloned and the amplified regions were sequenced. One of these was 93% close to HPV 35 and the other was 80% close to HPV 58. Three samples had both p53 mutations and HPV genome. CONCLUSIONS: Our results indicate that HPV 16 infection was more common than HPV 18, the p53 mutations and HPV infection were not mutually exclusive events in the genesis of carcinoma of uterine cervix among Indian women, and p16 gene may not play a role in Indian cervical carcinomas.     

Evaluation of the Children's Activity Rating Scale (CARS) in young children

We describe the daily activity patterns and the between-day and -year reliabilities of the Children's Activity Rating Scale (CARS) measured in 180 Anglo-, African-, and Mexican-American children aged 3 or 4 yr. Reliabilities were assessed at up to 11 measurement periods over 3 yr. CARS scores were measured by two trained observers (alternating 2-h shifts) up to 12 working hours. There were no significant ethnic or day of week differences in the activity levels. Males had higher mean activity levels than females and higher activity was performed in the summer and fall than the spring or winter. The all-measurements reliability for a mean of 5.34 d of observation over the 3 yr of measurement was 0.57. The reliability across all days and years of measurement was 0.73. The highest level of reliability (0.75) was found for the percent of minutes spent at CARS levels 3, 4, or 5 followed by an intraclass correlation of 0.74 for percent of minutes spent at CARS levels 4 or 5. These data support the utility of using the CARS as a measure of physical activity in younger children from different ethnic groups.     

Age dependent possibilities for healing in cartilage injuries (experimental investigations with animals) (author's transl)

Regenerative and degenerative changes of cartilage were studied in animals by micromorphological methods and autoradiography. Cartilage lesions of defined size were set in the femoral condyle of rabbits of variing age by means of an electrical drill developed by us. We used juvenile animals, 3 months old, and senile animals 4 years old. The lesions were studied by lightmicroscopy, electronmicroscopy and scanning electron microscopy. In young animals we were able to demonstrate prevailing reparative changes after injury and the potency for genuine regeneration originating from cartilage. Isolated chondral lesions develop reactive tissue originating mainly from superficial parts of the cartilage. When subchondral bone is exposed we see granulation tissue filling up the defect and change by metaplasia. The replacing tissue originating from superficial cartilage as well as from subchondral bone is able to fill the defect within 3 months. In the replacing tissue originating from cartilage we find fibroblasts and fibrocytes with many mitoses. Consecutively the cells are rounding increasingly. Finally chondrocytes are developing. At the same time as these reparative changes occur we see degenerative changes with decreased mucopolysaccharide synthesis, cell necroses with consecutive decrease in number of cells and singular small cluster. In old animals we could not demonstrate any reparative or regenerative changes after injuries; the artificial defect in cartilage persists. Instead, degenerative changes with signs of arthrosis are developing rapidly: chondroitin sulfate synthesis is decreased, there is ample cluster formation, cell necrosis, decrease in number of cells, and incorporation of paraplasmatic substances in cartilage. We could not demonstrate any mitoses. The causes for the inability of cartilage of aged individuals for reparative changes are discussed.     

Serum cholesterol and osteoarthritis. The baseline examination of the Ulm Osteoarthritis Study

OBJECTIVE: To assess the association between serum cholesterol and osteoarthritis (OA). METHODS: OA patterns were studied in 809 patients with knee or hip joint replacement due to OA in 4 hospitals in southwest Germany. Participants had a standardized interview and examination. Radiographs of the contralateral joint as well as both hands and a blood sample were obtained. Serum cholesterol levels were divided into tertiles and hypercholesterolemia was defined as > or = 6.2 mmol/l or use of antihyperlipidemic drugs. According to the presence or absence of radiographic OA in the contralateral joint, participants were categorized as having bilateral or unilateral OA. If radiographic OA of different finger joints was present, participants were categorized as having generalized OA. Odds ratios and 95% confidence intervals for the association of serum cholesterol with OA patterns were calculated with logistic regression, adjusting for potential confounders. RESULTS: Eighty-five percent of participants with radiographs had bilateral OA and 26% generalized OA. No association was observed between hypercholesterolemia and bilateral OA. Hypercholesterolemia (OR 1.61; 95% CI 1.06-2.47) and high serum cholesterol levels (3rd versus 1st tertile: OR 1.73; 95% CI 1.02-2.92) were independently associated with generalized OA. This association was almost exclusively due to participants with knee OA. CONCLUSION: These data add to the evidence regarding the independent role of serum cholesterol as a systemic risk factor for OA. The discrepant associations observed for different OA patterns are likely due to the relative weight of other risk factors.     

Untersuchung über die Zusammenhänge zwischen Fehlerursachen und Fehlererscheinungen bei unberuhigtem Automatenstahl

Statistische Untersuchung der Zusammenhänge zwischen 13 Betriebskennwerten und dem Putzausfall bei unberuhigtem Automaienstahl mit ≤ 0,12% C, 0,25 bis 0,90% Mn sowie 0,02 bis 0,10 oder 0,20 bis 0,30% S. Versuche zur Ermittlung des Einflusses der Gehalte an Mangan und Schwefel im Stahl auf den Sauerstoffgehalt, die Viskosität, die Oberflächenspannung und das Kochverhalten in der Kokille. Maβnahmen zur Verbesserung des Kochverhaltens. Zusammenhänge zwischen dem Kochverhalten, der Werkstoffheterogenität und der Fehlerhäufigkeit am Halbzeug. Wirkung von Spurenelementen auf die Warmrissigkeit. Einfluβ der Walzbedingungen auf die Fehleranfälligkeit.     

Lack of an association between insulin-like growth factor-I and body composition, muscle strength, physical performance or self-reported mobility among older persons with functional limitations

OBJECTIVE: The hypothesis that decreased growth hormone (GH) secretion contributes to the functional decline that occurs with aging is far from substantiated. There have been few studies addressing the distribution and correlates of IGF-I, an indicator of GH activity, in nonclinical populations. As part of a growth hormone intervention trial, we examined the cross-sectional relations between IGF-I levels and multiple measures of physical function, body composition, and strength in a group of older men and women exhibiting mild to moderate reductions in measured physical performance. METHODS: Using a variety of advertising techniques, 155 older subjects were recruited from a metropolitan area to participate in a growth hormone and exercise intervention study. At baseline, all subjects had blood drawn for IGF-I and underwent testing of body composition using dual X-ray absorptiometry, muscle strength using isokinetic dynamometry, and functional assessment using timed performance measures and self-report. Associations between levels of IGF-I, body composition, strength, and physical function were assessed after dividing men and women separately into tertiles of IGF-I as well as treating IGF-I as a continuous variable. RESULTS: Men had higher IGF-I levels than women, and a significant inverse correlation was observed between age and IGF-I in men (r=-0.29, P=.009). There were no clear trends for associations between tertiles of IGF-I, and any of the variables tested. Linear regression models with IGF-I treated as a continuous measure were not associated significantly with any of the measures of physical function, body composition, or strength (all P > 0.05). CONCLUSIONS: In conclusion, although IGF-I levels declined with age in men, these data did not demonstrate an association between IGF-I and measures of muscle strength, body composition, or physical functioning. These findings support the growing body of evidence that IGF-I levels may not be an indicator of growth hormone activity in older persons.     

Do calcium and zinc ions influence matrix molecule synthesis of chondrocytes?

The experiments described here tested the effect of various calcium (Ca) and Zinc (Zn) concentrations on cell proliferation and matrix molecule synthesis of fetal and adult bovine chondrocytes in monolayer cultures. Levels of Ca < 0.2 mM in a culture medium or the addition of Zn (0.1-50 microM) selectively promoted the production of collagen but did not affect significantly synthesis of proteoglycans. No change in proliferation of fetal and adult chondrocytes could be observed. In contrast 10 mM Ca promoted the hypertrophic differentiation of chondrocytes (e.g. expression of collagen type X). The results are related to calcium channel configurations in chondrocytes in the discussion.