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  • 1
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Science Ltd
    Scandinavian journal of immunology 55 (2002), S. 0 
    ISSN: 1365-3083
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Chlamydia pneumoniae is an obligate intracellular pathogen with a tendency to cause persistent infections that has been associated with many chronic conditions such as asthma and coronary artery disease. However, its immunopathogenic mechanisms are poorly understood. When aiming to study the impact of C. pneumoniae infection on host cell apoptosis, we found that epithelial infected (HL) cells and macrophages (U937-line) were resistant to staurosporine and tumour necrosis factor (TNF)-α-induced physiological apoptosis 48, 72 or 120 h post-infection, as determined by flow cytometry, DNA fragmentation assay and fluorescence microscopy. The antiapoptotic influence was observed even at a late stage of the chlamydial life cycle and was dependent on the chlamydial protein synthesis. The mechanisms involved blockage of mitochondrial cytochrome c release and caspase 3 activation. We also found that during a persistent C. pneumoniae infection induced in vitro by penicillin treatment of cell cultures, the inhibition of apoptosis was extended for up to 120 h of follow-up post-infection and was restricted to the cells carrying chlamydial inclusions. Our findings suggest that inhibition of apoptosis may be one of the pathogenetic mechanisms by which C. pneumoniae infection can mediate the development of chronic diseases.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1365-2133
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Background  Hailey–Hailey disease (HHD) (OMIM 16960) and Darier disease (DD) (OMIM 124200) are dominantly inherited acantholytic skin diseases, respectively, caused by mutations in the genes encoding the Golgi secretory pathway Ca2+-ATPase (SPCA1, ATP2C1) and the sarco/endoplasmic reticulum Ca2+-ATPase type 2 (SERCA2, ATP2A2) genes.Objectives  To investigate calcium regulation in keratinocytes cultured from patients with HHD and DD by measuring intracellular calcium resting levels and the cellular responses to ATP and thapsigargin.Methods  The study was carried out using keratinocyte cultures established from four patients with HHD and four with DD. Calcium concentrations were measured with fluorescence ratio imaging using fura-2 loading.Results  Control and HHD keratinocytes displayed approximately the same Ca2+ levels in resting phase, while DD keratinocytes showed elevated Ca2+ levels. Application of ATP caused less pronounced elevation of intracellular calcium concentration ([Ca2+]i) in both HHD and DD keratinocytes than in control cells. HHD keratinocytes did not lower their [Ca2+]i as efficiently as control keratinocytes after treatment with thapsigargin. In addition, DD keratinocytes were practically incapable of lowering their [Ca2+]i after treatment with thapsigargin.Conclusions  The results demonstrate that the defects in SPCA1 and SERCA2 calcium ATPases result in distinct patterns of calcium metabolism. This is also supported by the different clinical features of the diseases.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 60 (1997), S. 441 -448 
    ISSN: 1432-0827
    Schlagwort(e): Key words: Osteopenia — Training — Bone — Mechanical strength — Rat.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Abstract. Fifty-six Sprague-Dawley rats were either ovariectomized (OVX, n= 24), sham-operated (Sham, n= 24), or sacrificed (n= 8) at the beginning of the experiment to serve as a baseline group. The OVX and Sham groups were further randomly divided into control (CTRL), slow running (R10), and faster running (R18) groups. R10 and R18 groups ran for 2 × 30 min/day for 8 weeks at speeds of 10 m/min and 18 m/min, respectively. Exercise did not affect the mechanical or histomorphometric parameters of bone in the sham-operated rats. There was no effect of exercise on body weight gain in the OVX-R10 group, but in OVX-R18 it decreased the gain of body weight. In the OVX–CTRL group the maximal load and energy absorption of the femoral neck were 16.7% (P 〈 0.001) and 30.0% (P 〈 0.001) lower than in the Sham–CTRL group, respectively. In OVX animals, slow running had a positive effect on the maximal load of the femoral neck (86.5 N) when compared with OVX–CTRL rats (77.1 N, P 〈 0.07). 51.7% of the trabecular bone was lost in the distal femur as a result of OVX and exercise reduced this loss to 30.2% (R10) and 39.9% (R18). Ovariectomy increased the bone formation rate (BFR) and the mineral apposition rate (MAR) on the periosteum of the femoral shaft. Exercise decreased the periosteal BFR and MAR in OVX rats, but increased it at the endosteum. Osteoclast numbers in the femoral metaphysis were increased after OVX and running exercise inhibited this effect significantly. The maximal bending load of the humerus increased after OVX by 12.1% (P 〈 0.05). Exercise enhanced this effect, the slow running being more effective. These results suggest that bone in OVX rats is either more sensitive to exercise than in sham-operated rats or that the higher body weight with slow running induces optimal loading and strengthens the bones.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 66 (2000), S. 288-291 
    ISSN: 1432-0827
    Schlagwort(e): Key words: Fracture healing — Callus — Quantitative tomography — X-ray densitometry — Image analysis.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Abstract. Fracture healing and callus formation have traditionally been evaluated by using X-ray radiography. Here we compared X-ray radiography and peripheral quantitative computed tomography (pQCT) in evaluating the healing callus of standardized tibial fractures in 141 female rats after a 4- or 8-week follow-up. The results were compared with the tensile (4-week) and compressive (8-week) failure load of the callus. The projectional size of callus, as defined from lateral ex vivo radiographs, correlated significantly with the pQCT-defined cross-sectional area (CSA) of mid-callus. This relationship was dependent on the pQCT attenuation threshold, being higher for the CSA of compact bone (r = 0.85, P 〈 0.0001) than for the total bone CSA (r = 0.68, P 〈 0.0001). Radiographically defined callus projectional area also correlated strongly with bone mineral content (BMC) (r = 0.84–0.86, P 〈 0.0001). The mean optical density of the callus analyzed from the radiographs had only a weak correlation with the pQCT-defined bone mineral density (BMD) of callus. A weak negative relationship was found between CSA and BMD. The optical density analyzed from lateral radiographs did not correlate with the tensile or compressive failure load of callus. Callus size, BMC, and BMD were associated with the compressive failure load, whereas both radiographs and pQCT were poor in explaining the failure load in tension.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 55 (1994), S. 33-37 
    ISSN: 1432-0827
    Schlagwort(e): Osteoporosis ; Rat ; Orchidectomy ; Exercise ; Strength
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Abstract The effect of exercise on castration-induced osteoporosis in 3-month-old male rats weighing 264±4 g at the beginning of the experiment was studied. A testosterone deficiency was induced by orchidectomy (ORC), and the exercise group ran 10 m/minute for 1 hour a day on a treadmill at 0% grade. There were seven groups of eight rats (n=56) randomized into a control group killed at time 0, and sham, ORC and ORC and exercise groups killed at 4 and 8 weeks. ORC reduced body weight gain (with analysis of variance (ANOVA) P〈0.001), and at 4 weeks the body weight was 343±14 g in ORC group and 301±4 g in the ORC and exercise group (P〈0.01). The increase in femoral length was slower in the ORC+exercise groups. The ash weight of the tibia did not decrease significantly after ORC or ORC+ exercise. ORC did not affect 45Ca incorporation, but exercise slightly increased it in the whole tibia 8 weeks after ORC (with ANOVA P=0.057). ORC had significantly lowered the trabecular bone volume in the secondary spongiosa of the distal femur at 4 and 8 weeks, and exercise did not prevent this. This is an opposite finding to our previous study with ovariectomized female rats [12]. ORC also significantly had reduced the osteoblast-lined trabecular bone surface and the number of osteoclasts by 8 weeks after the operation. Exercise increased the osteoblast-lined surface and the number of osteoclasts. The mechanical strength of the femoral neck also was reduced after ORC and this was not prevented by exercise either. In conclusion, ORC reduces bone growth and turnover which leads to osteopenia in growing rats. Moderate treadmill exercise does not reverse the ORC-induced loss of trabecular bone and the reduced mechanical strength of the femoral neck, although it has a positive effect on the osteoblast and osteoclast indices and on calcium incorporation into bone.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    ISSN: 1432-5195
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Résumé  Nous avons étudié l’effet d’un implant composite, fait de corail imprégné de protéine de la morphogenèse osseuse (BMP) bovine, sur la consolidation d’une perte de substance de 2 cm de l’os ulnaire canin. Des implants comprennent du corail simple ou des autogreffes d’os cortical étaient employées comme contrôles. Une fixation temporaire intramedullaire de 9 semaines était réalisée, soit avec des broches de Kirschner (6 os ulnaires avec un implant composite, 6 avec du corail simple, et 6 avec une autogreffe), soit avec une plaque-à-vis (3 avec un implant composite et 3 avec du corail simple). Des radiographies étaient prises 3, 6, 9, 12, 16, 26 et 36 semaines aprés la mise en place des implants, et des tests mécaniques de torsion étaient réalisées en fin d’étude. Aprés 16 semaines, les taux de formation et d’union osseuses étaient significativement plus élevés avec les implants composites qu’avec les implants de corail simple, mais des taux encore plus élevés étaient observés dans les essais avec les autogreffes. La BMP a accéleré la résorption de l’implant de corail. La résistance mécanique des os avec un implant composite était plus forte que celle des os ayant un implant de corail simple (P〈0.05), alors que la résistance mécanique des os traités par une autogreffe était plus forte (P〈0.01) que celle des os ayant un implant de corail, avec ou sans BMP. En conclusion, la BMP améliore le pouvoir de consolidation des implants de corail qui reste cependant inférieur à celui observé avec les autogreffes.
    Notizen: Abstract  We studied the effect of a composite implant consisting of coral and native bovine bone morphogene-tic protein (BMP) on the healing of 2 cm segmental defects in the canine ulna. Plain coral and cortical autograft bone implants were used as controls. The fixation was temporary for 9 weeks with an intramedullary Kirschner wire (6 ulnas with a composite implant of coral and BMP, 6 with plain coral and 6 with an autograft) or a plate and screws (3 ulnas with a composite implant and 3 with plain coral). X-rays were taken at 3, 6, 9, 12, 16, 26 and 36 weeks, and mechanical torsion tests were performed at the end of the study. The score for bone formation and bone union evaluated from radiographs was significantly higher in the composite implant group than in the plain coral group at 16 weeks, but the score was even higher with autografts. BMP accelerated the resorption of the coral implant. The mechanical strength of the composite implants was higher than that of the bones with a plain coral implant (P〈0.05), while the mechanical strength of the coral implants, even with BMP, was significantly lower than the strength of autografts (P〈0.01). In conclusion, BMP enhanced the capacity of a coral implant to heal a segmental ulnar defect by increasing bone formation, but the effect of this combination was not as good as that of a cortico-cancellous autograft.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 7
    ISSN: 0021-9304
    Schlagwort(e): biocompatibility ; Nitinol ; shape memory alloy ; tissue response ; perineural response ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Nickel-titanium shape memory alloy (Nitinol) has properties that could be very useful in surgical applications. Thermal shape memory, superelasticity, and high damping properties make such alloys behave differently compared to other implant metals. There has previously been a lack of sufficient evidence on the biocompatibility of Nitinol. The purpose of this study was to evaluate general soft tissue response and biocompatibility to Nitinol in vivo, and to clarify neural and perineural responses, previously unreported. Seventy-five rats were randomized into three groups. Test specimens were implanted into paravertebral muscle and near the sciatic nerve. A comparison was made between Nitinol, stainless steel, and Ti-6Al-4V. The animals were euthanized at 2, 4, 8, 12, and 26 weeks after implantation. General morphologic and histologic observations were made under light microscopy. Semiautomatic computerized image analysis was used to measure the encapsule membrane thickness around the implants. The muscular tissue response to Nitinol was clearly nontoxic, regardless of the time period. The overall inflammatory response to Nitinol was very similar to that of stainless steel and Ti-6Al-4V alloy. There were no necroses, granulomas, or signs of dystrophic soft tissue calcification. The immune cell response to Nitinol remained low. Only a few foreign-body giant cells were present. The detected neural and perineural responses were also clearly nontoxic and nonirritating with Nitinol. No qualitative differences in histology between the different test materials could be seen. At 8 weeks, the encapsule membrane of Nitinol was thicker than that of stainless steel (mean 62 ± 25 μm vs. 41 ± 8 μm). At the end of the study, the encapsule thickness was equal to all the materials tested. We concluded that Nitinol had good in vivo biocompatibility after intramuscular and perineural implantation in rats in the 26-week follow-up. Based on the results of the present study, Nitinol appears to have good potential for clinical use. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 41, 481-488, 1998.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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