The downregulation of asparagine synthetase expression can increase the sensitivity of cells resistant to l-asparaginase.
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Biomedical subjects
Publications and source records attributed to H L Xue.
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Apoptotic cell death induced by cross-linking Fas receptor (FasR/CD95) has been investigated in human acute myelogenous leukemia (AML) cells. FasR-mediated growth inhibition and DNA fragmentation could be induced in certain cases of AML. Interestingly, when DNA synthesis and G1 -> S transition in the cell cycle were enhanced by interleukin-3 or granulocyte-macrophage colony-stimulating factor, Fas-insensitive blast cells acquired cellular susceptibility toward FasR-mediated growth inhibition. To further evaluate an association between the Fas-R-mediated action and a specific phase of the cell cycle, a FasR+ leukemic cell line, MML-1, was established from a patient with AML. The morphologic feature of dying cells and DNA fragmentation indicated that FasR cross-linking induced apoptotic cell death in MML-1 cells. Cell cycle arrest in G1A phase with the treatment of phorbol 12-myristate 13-acetate or thymidine rendered MML-1 cells resistant to FasR-mediated apoptosis without downregulation of surface FasR expression. However, S-phase arrest with 5-fluorouracil could neither enhance nor inhibit FasR-mediated apoptosis. Simultaneous DNA/RNA quantification analysis revealed the selective loss of cells in G1B compartment, accompanied by the increase of apoptotic nuclei in sub-G1 fraction. These findings suggested that FasR-mediated apoptotic signals could be transduced into cells in G1B compartment and G1A -> G1B transition might augment the induction of FasR-mediated apoptosis.
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Comparisons between x-ray and B-mode ultrasonic examinations were carried out in 32 divers in both shoulders and both hips (128 comparisons in all). The x-rays showed dysbaric osteonecrosis (DON) in 46 sites; in 43 of these, the B-mode ultrasonogram result coincided with the x-ray finding. We suggest that B-mode ultrasonograms can depict the location, form, and size of the lesions. It is an easy, efficient, and noninvasive method of diagnosing DON, worthy of further investigation and application. Similar good agreement between x-rays and ultrasonograms was found with the now-obsolete A-mode technique.
In a prospective investigation of 164 cases of dysbaric osteonecrosis out of a total of 1269 hyperbaric workers, we found that lesions are apt to occur more frequently in some sites of the head and neck of the femur and humerus than in others. Defining the susceptibility of sites with radiographs has improved our ability to make early diagnoses because we are able to estimate the likelihood of a definite lesion of osteonecrosis developing. We have found that when the trabeculae in a susceptible site appear disordered or have translucent areas, the site often develops into osteonecrosis in a few years.
Rabbits developed acute decompression sickness after staying at 6 ATA for 30 min followed by decompression to 1 ATA in 20 min or less. If the rabbits received an i.v. injection of 25% ethanol upon surfacing, all survived, whereas half the untreated control group died within 15-35 min after decompressing. In ethanol-treated animals, no bubbles were seen in blood vessels of visceral organs, muscles, and subcutaneous tissues at autopsy 60 min after treatment. Decompression reduced platelet counts markedly in all rabbits, but in the control group the count stayed low, whereas with ethanol treatment the counts had reached the precompression level after 1 h and 24 h.
Dysbaric osteonecrosis was found in 259 cases among 2260 examined hyperbaric workers from several occupations. No positive cases were found in the divers in shipyards and diving experiments. Naval divers showed the lowest incidence (2.1%) and fishery divers the highest (19.8%). Distribution of long bone lesions was 46.0% in upper humerus, 37.7% in upper femur, 8.3% in lower femur, and 8.0% in upper tibia. We classify long bone lesions into three radiographic stages, the first two on the basis of size of the bone lesions as projected on the radiographs, and the third stage on the basis of extension of the lesion toward articular destruction. The three-stage classification system correlates with the clinical symptoms, and the working capacity of the individual patients tends to correlate with the severity of dysbaric osteonecrosis and can be understood by the general public.
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