Profilin gene expression and regulation in a temperature-sensitive breast cancer cell line: tsFT101

 The temperature-sensitive mutant cells (tsFT101) derived from a mouse mammary carcinoma cell line, FM3A, become multinucleated at a non-permissive temperature of 39°C. To further understand the molecular mechanism of such cytokinetic disturbance, we examined the expression of profilin, the main regulator of the transition of globular actin (G-actin) to filamentous actin (F-actin). RT-PCR analysis of mouse profilin cDNA from tsFT101 showed a point mutation (177 A → G) which was a wobble mutation causing no change in the encoded amino acid. The expression level of profilin mRNA was, however, diminished in cultured tsFT101 cells under non-permissive temperatures compared with wild-type FM3A cells in association with multinucleation. A stable transfection of profilin cDNA expression vector to tsFT101 cells prevented multinuclear cell formation when cultured at 39°C. In contrast, antisense profilin cDNA expression vector did not alter multinuclear cell formation. The primary cause of the cytokinetic disturbance of tsFT101 cells may be due to the diminished level of profilin gene expression. Received: 6 January 1997 / Received after revision and accepted: 17 April 1997     

A model of global cerebral ischemia in C57 BL/6 mice.

A reproducible model of global cerebral ischemia in mice is essential for elucidating the molecular mechanism of ischemic neuronal injury. Such a model is particularly important in the mouse because many genetically engineered mutant animals are available. In C57BL/6 and SV129/EMS mice, we evaluated a three-vessel occlusion model. Occlusion of the basilar artery with a miniature clip was followed by bilateral carotid occlusion. The mean cortical cerebral blood flow was reduced to less than 10% of the preischemic value, and the mean anoxic depolarization was attained within 1 minute. In C57BL/6 mice, there was CA1 hippocampal neuronal degeneration 4 days after ischemia. Neuronal damage depended upon ischemic duration: the surviving neuronal count was 78.5 +/- 8.5% after 8-minute ischemia and 8.4 +/- 12.7% after 14-minute ischemia. In SV129/EMS mice, similar neuronal degeneration was not observed after 14-minute ischemia. The global ischemia model in C57BL/6 mice showed high reproducibility and consistent neuronal injury in the CA1 sector, indicating that comparison of ischemic outcome between wild-type and mutant mice could provide meaningful data using the C57BL/6 genetic background. Strain differences in this study highlight the need for consideration of genetic background when evaluating ischemia experiments in mice.     

Expression of the large myelin-associated glycoprotein isoform in rat oligodendrocytes around cerebral infarcts

An immunohistochemical method that uses two specific antisera-distinguishable myelin-associated glycoprotein (MAG) isoforms showed an expression of large MAG isoform (L-MAG) protein in the oligodendrocyte cytoplasms in the white matter around experimental cerebral infarcts produced by occlusion of the left middle cerebral artery in the rat. L-MAG protein also was detected in the white matter on the contralateral side. This protein appears prior to S-MAG protein in myelination and remyelination in the central and peripheral nervous systems, and is believed to function in myelin formation. Because L-MAG protein has been found in the oligodendrocyte cytoplasm only in the early development period, its appearance in this cytoplasm after ischemic insult is evidence of MAG regeneration.     

Unilateral renal hypoplasia associated with bicuspid aortic valve.

A 20-year-old man with congestive heart failure (CHF) and hypertension (HT) was admitted to hospital. Ultrasonic echocardiography showed that he had aortic stenosis caused by a bicuspid aortic valve. The plasma renin concentration was slightly elevated, and enhanced magnetic resonance imaging and renography revealed a hypoplastic kidney that had almost lost its normal function. It is postulated that the increased afterload and preload of the left ventricle induced by both of these abnormalities contributed to the onset of CHF and HT. Pharmacological therapy alone failed to control the CHF and HT, but surgical removal of the hypoplastic kidney was effective in reducing the plasma renin concentration and treating the CHF and HT.     

Disseminated mycobacterium avium-intracellulare infection in a patient with myelodysplastic syndrome (refractory anemia)

A 31-year-old woman presented with fever and arthralgla. Despite treatment with antimicrobials and cortlcosteroids, her symptoms persisted. A diagnosis of myelodysplastic syndrome (MDS)-refractory anemia (RA) was made by pancytopenia, dysplasia, and trisomy 8. Cultures of bone marrow, blood, and gastric juice showed Mycobacterium aviumintraceliuiare (MAI). She was treated with antimycobacterial drugs and recombinant human G-CSF/M-CSF and showed an initial response, but spike fever recurred and pancytopenia progressed. Hepatospienomegaly and marked retroperitoneal lymphade-nopathy were revealed, indicating further dissemination of MAI. Treatment with recombinant human GM-CSF and very-low-dose cytosine arabinoside, was started but was not effective. This case showed significant reduction in peripheral blood 1-lymphocytes, especially the CD4⁺ population, and low immunoglobulin levels. immunodeficiency state associated with long-term steroid therapy and MDS seemed to contribute to the development of the disseminated infection with MAI. © 1994 Wiley-Liss, Inc.     

Alterations in in vitro function and protein oxidation of rat sarcoplasmic reticulum Ca2+-ATPase during recovery from high-intensity exercise.

The hypothesis tested in this study was that the extent to which sarcoplasmic reticulum (SR) Ca(2+)-ATPase is oxidized would correlate with a decline in its activity. For this purpose, changes in the SR Ca(2+)-sequestering ability and the contents of carbonyl and sulfhydryl groups during recovery after exercise were examined in the superficial portions of vastus lateralis muscles from rats subjected to 5 min running at an intensity corresponding to maximal oxygen uptake (50 m min(-1), 10% gradient). A single bout of exercise elicited a 22.4% reduction (P < 0.05) in SR Ca(2+)-ATPase activity. The decreased activity progressively reverted to normal levels during recovery after exercise, reaching normal levels after 60 min of recovery. This change was paralleled by a depressed SR Ca(2+)-uptake rate, and the proportional alteration in these two variables resulted in no change in the ratio of Ca(2+)-uptake rate to Ca(2+)-ATPase activity. The contents of SR Ca(2+)-ATPase protein and sulfhydryl groups in microsomes were unchanged after exercise and during recovery periods. In contrast, the content of carbonyl groups in SR Ca(2+)-ATPase behaved in an opposite manner to that of SR Ca(2+)-ATPase activity. An approximately 80% augmentation (P < 0.05) in the carbonyl group content occurred immediately after exercise. The elevated carbonyl content decreased towards normal levels during 60 min of recovery. These results are strongly suggestive that oxidation of SR Ca(2+)-ATPase is responsible, at least in part, for a decay in the SR Ca(2+)-pumping function produced by high-intensity exercise and imply that oxidized proteins may be repaired during recovery from exercise.     

Patellar tracking and patellofemoral geometry in deep knee flexion.

Patellar tracking and femoral condylar geometry in deep knee flexion were evaluated using magnetic resonance imaging. The patellar tilting angle, patellar shift, and patellar anteroposterior translation from 0 degrees to 135 degrees flexion were measured. The depth of the femoral condylar articular surface and the curvature of the femoral condylar articular surface also were measured at 135 degrees flexion. The patella shifted laterally, tilted medially, and sank deeply into the intercondylar notch during deep knee flexion. The articular surface of the lateral condyle, existing deep within the intercondylar notch, began to curve steeply at a point farther from the center of the intercondylar notch than did the medial condyle. The geometry of the femoral condyle is adequate to fit the patellar geometry. Results of the current study suggest that the geometry of the lateral femoral condyle allows the patella to track smoothly with a larger patellofemoral contact area and less patellofemoral pressure during deep flexion.