Biomedical subjects
Publications and source records attributed to H Luo.
From the root of Salvia trijuga three triterpenoids were isolated. Based on the analysis of their spectra, they were identified as coleonolic acid with a contracted A-ring, euscaphic acid and 2 alpha-hydroxyursolic acid.
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The time course of interaction of caldesmon with actin may be monitored by fluorescence changes that occur upon the binding of 12-(N-methyl-N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl))-labeled caldesmon to actin or to acrylodan actin. The concentration dependence of the observed rate of caldesmon-actin binding was analyzed to a first approximation as a single-step reaction using a Monte Carlo simulation. The derived association and dissociation rates were 10(7) M-1 s-1 and 18.2 s-1, respectively. Smooth muscle tropomyosin enhances the binding of caldesmon to actin, and this was found to be due to a reduction in the rate of dissociation to 6.3 s-1. There is no evidence from this study for a different mechanism of binding in the presence of tropomyosin. The fluorescence changes that occurred with the binding of 12-(N-methyl-N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl))-labeled caldesmon to actin or actin-tropomyosin were reversed by the addition of myosin subfragment 1 as predicted by a competitive binding mechanism.
The effect of rapamycin (RAPA) as graft pretreatment was evaluated in orthotopic small bowel and kidney allotransplantation (Tx) in the rat. In the small bowel Tx model, six groups were involved, each including three combinations for evaluation of host-versus-graft (HVG) [Lewis (LEW) x Brown Norway (BN) (LBN)-F1-->Lewis], graft-versus-host (GVH) (LEW-->F1), and combined HVG and GVH immune responses (BN-->LEW). RAPA graft pretreatment alone (16 micrograms/ml x 3 ml) was able to induce a modest but significant prolongation of survival in all three combination models compared with controls (P < 0.05). The same was observed for low dose CsA treatment (2 mg/kg/day x 14 days) of the recipient only (P < 0.05). Combination of graft pretreatment with RAPA and CsA recipient treatment produced a marked prolongation of survival especially in HVG response. Recipients treatment with one 48-microgram bolus of RAPA i.v. immediately after graft revascularization failed to achieve any prolongation of survival for the GVH or combined HVG and GVH responses. This seems to exclude a "carry-over" effect of RAPA from graft to recipient. RAPA efficacy was also clearly confirmed in the kidney graft pretreatment model as compared to recipient treatment with an equivalent RAPA dose. These results demonstrate that graft RAPA pretreatment prolongs SB survival after Tx in the rat for HVG, GVH, and bidirectional immune responses. Intragraft interaction with passenger leukocytes or APC function appears as one of the possible mechanisms. RAPA graft pretreatment potentiates low dose CsA recipient treatment suggesting a possible use in clinical organ Tx.
Proteins of the Jak family of non-receptor kinases play important roles in mammalian hematopoietic signal transduction. They mediate the cellular response to a wide range of cytokines and growth factors. A dominant mutation in a Drosophila Jak kinase, hopscotchTumorous-lethal (hopTum-l), causes hematopoietic defects. Here we conduct a molecular analysis of hopTum-l. We demonstrate that the hopTum-l hematopoietic phenotype is caused by a single amino acid substitution of glycine to glutamic acid at residue 341. We generate a true revertant of the hopTum-l mutation, in which both the molecular lesion and the mutant hematopoietic phenotype revert back to wild type. We also examine the effects of the G341E substitution in transgenic flies. The results indicate that a mutant Jak kinase can cause leukemia-like abnormalities.
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The aim of this study was to determine the effect of intravascular ultrasound (IVUS) imaging on decision making in the performance of coronary interventions. One hundred lesions were assessed in 87 patients undergoing balloon or laser angioplasty, atherectomy, stent placement, and additional diagnostic examination. Angiographically acceptable results were deemed inadequate by IVUS in 29% of angioplasties and 30% of stent deployments, and planned procedures subsequently were altered. Abnormalities commonly identified by IVUS and not by angiography were 13 coronary dissections after the procedure and 14 significant stenoses in apparently normal angiograms and significant stenoses were excluded in 7 patients with ambiguous angiograms. The apparent contribution of coronary IVUS imaging led to its significantly increased use over a 1-year period, as coronary interventional decisions on the basis of IVUS findings increased from 4 (17%) of 19 to 60 (74%) of 81. These data suggest that IVUS is a useful adjunct to angiography in selected patients for (1) identification or exclusion of dissection, (2) assessment of the adequacy of balloon angioplasty, (3) identification or exclusion of thrombus, (4) measurement of the depth of tissue removal, (5) determination of stent size and the result of stent deployment, and (6) assessment of the severity of stenoses, especially at ostial sites.
The endometrium was studied by morphometry in 34 healthy women before and after one year's use of an IUD releasing levonorgestrel at a rate 20 micrograms/24 hr (LNG-IUD-20). The effect was compared with that of an IUD releasing 2 micrograms levonorgestrel/24 hr (LNG-IUD-2). The appearance of suppressed endometrial proliferative activity and increased inflammatory reaction was similar in the two experimental groups, suggesting that the morphological alterations were independent of the LNG dosage. The result of this study, combined with clinical data, suggests that LNG-IUD-20 could replace LNG-IUD-2 without any additional side effects. The efficacy of LNG-IUD-20 is also likely to last for a longer period than the LNG-IUD-2.
The specimens of endometria were obtained from 18 women using an intrauterine device releasing levonorgestrel at 20 micrograms/day (LNG-IUD-20). An immunoperoxidase reaction, PAP method, with the antiserum of Factor VIII as the primary antibody, was carried out in the endometrial biopsies to detect the Factor VIII activity in the endometrial endothelium before and after insertion of LNG-IUD-20. The immunoperoxidase activity was quantitatively assessed by a computer digital image analyser. The results revealed that there were a lower Factor VIII activity in the endometrial endothelial cells after insertion of LNG-IUD-20 (p < 0.001) when compared with the control. From the results of the present study, it is suggested that the synthesis and release of endometrial endothelial Factor VIII might be inhibited by the insertion of LNG-IUD20.
The major histocompatibility (MHC) class I antigens are coordinately expressed in most cells. However, some tumors or virus-infected cells lack expression of one MHC class I antigen, while expression of the other MHC class I antigens is unaffected. We previously described the selective expression of MHC class I antigens on a B-cell lymphoma from SJL/J mice called RCS5. This tumor expresses H-2Ks, but has lost cell surface expression of H-2Ds. To understand the mechanism responsible for the selective loss of H-2Ds on the cell surface, we analysed H-2Ds mRNA and protein in the RCS5 tumor. Here we report that H-2Ds mRNA was expressed in RCS5, but H-2Ds protein was not detected in cell lysates. To determine whether the H-2Ds mRNA from RCS5 was able to direct the synthesis of H-2Ds protein, we performed cDNA cloning, in vitro translation and gene transfer experiments using a cell line related to RCS5 (cRCS-X). Our results indicated that the inhibition of H-2Ds expression in cRCS-X occurred after transcription of a non-defective H-2Ds mRNA. Furthermore, H-2Ds antigen expression was restored in cRCS-X using a retroviral vector to express the recombinant H-2Ds cDNA. These results indicate that the inhibition of H-2Ds expression could be overcome either by out competing an inhibitor that functions in trans or by removing cis-acting regulatory sequences from the endogenous H-2Ds mRNA.
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