Calcium loss and muscle atrophy are two of the main metabolic changes experienced by astronauts and crew members during exposure to microgravity in space. Calcium and cytoskeletal events were investigated within sea urchin embryos which were cultured in space under both microgravity and 1 g conditions. Embryos were fixed at time-points ranging from 3 h to 8 days after fertilization. Investigative emphasis was placed upon: (1) sperm-induced calcium-dependent exocytosis and cortical granule secretion, (2) membrane fusion of cortical granule and plasma membranes; (3) microfilament polymerization and microvilli elongation; and (5) embryonic development into morula, blastula, gastrula, and pluteus stages. For embryos cultured under microgravity conditions, the processes of cortical granule discharge, fusion of cortical granule membranes with the plasma membrane, elongation of microvilli and elevation of the fertilization coat were reduced in comparison with embryos cultured at 1 g in space and under normal conditions on Earth. Also, 4% of all cells undergoing division in microgravity showed abnormalities in the centrosome-centriole complex. These abnormalities were not observed within the 1 g flight and ground control specimens, indicating that significant alterations in sea urchin development processes occur under microgravity conditions.

Animals↗

PubMed1999

Septic arthritis caused by Corynebacterium amycolatum following vascular graft sepsis.

A case of septic arthritis caused by Corynebacterium amycolatum in a native hip joint occurred in an adult man following contralateral vascular graft sepsis, and was successfully treated with intravenous vancomycin followed by oral doxycycline and rifampicin. To the authors' knowledge, this is the only reported case of septic arthritis due to C. amycolatum.

Anti-Bacterial Agents↗

PubMed1999

Torsional stability of primary total knee replacement tibial prostheses: a biomechanical study in cadaveric bone.

The significance of torsional loads on the tibial component of total knee replacement prostheses is not clearly established. This study investigated the micromotion induced by torsion, under physiologic loads. Three forms of fixation were sequentially tested in cadaveric tibiae: press-fit, press-fit plus 4 peripheral corticocancellous screws, and horizontally cemented. The implanted tibia was loaded with an axial force between 0.5 and 2.2 kN and a cyclic torque of +/- 5 Nm. The relative motion between the prosthesis and the bone was measured. Our results show little difference between the 3 methods of fixation at high axial loads. At low axial loads, however, the press-fit prosthesis may permit micromotions high enough to interfere (theoretically) with bone ingrowth. Motion is reduced when the same prosthesis is augmented with screws. The cemented prosthesis produces the lowest average micromotion. Our study indicates that rotational micromotion is unlikely to contribute to the failure of ingrowth into the uncemented tibial prosthesis under normal physiologic loads. At low axial loads, which may be encountered in the immediate postoperative period, ingrowth may be compromised. Thus, initial rotational stability is an important consideration in uncemented total knee replacement design and postoperative management. In poor-quality tibiae, cementation may be the only method of fixation to provide sufficient torsional stability.

Adult↗

PubMed1999

Upregulation of basic fibroblast growth factor in breast carcinoma and its relationship to vascular density, oestrogen receptor, epidermal growth factor receptor and survival.

BACKGROUND: Angiogenesis, the process whereby endothelial cells divide and migrate to form new blood capillaries, has been assessed in tumours by measuring microvessel density. High microvessel density is a significant adverse prognostic factor in breast cancer. The angiogenic factor, basic fibroblast growth factor (bFGF), has been associated with tumourigenesis and metastasis in several human cancers. There are few quantitative studies of bFGF expression in normal tissues compared to cancer. PATIENTS AND METHODS: We have measured bFGF levels in 149 human primary breast carcinomas and assessed the findings in relation to microvessel density, oestrogen receptor (ER) and epidermal growth factor receptor (EGFR). Basic FGF levels were measured by ELISA. Western blotting and immunohistochemistry were carried out to confirm the presence of bFGF. RESULTS: Levels of bFGF were more than 10-fold higher in tumour cytosols compared to reduction mammoplasty tissue and 3-fold compared to non neoplastic cytosols from the same breast as the tumour (P < 0.0001). Immunohistochemistry showed bFGF protein was localised exclusively in the stroma whereas no bFGF staining was observed in the epithelial cells. High bFGF levels were significantly related to high ER (P = 0.01). Similarly, high bFGF levels were significantly related to low grade (P = 0.046) and to small tumour size (P = 0.04). No significant relationship was observed between bFGF and microvessel count, EGFR or age. In univariate analysis and in a Cox proportional hazard model bFGF did not reach significance for overall or relapse free survival. CONCLUSIONS: Our results show that although bFGF is elevated in breast carcinomas compared to normal breast tissue it is not related to microvessel density and it is not an independent predictor of survival in breast cancer patients. Basic FGF may be one of multiple factors that synergise with other growth factors such as VEGF to enhance angiogenesis.

Adult↗