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Biomedical subjects

R Xu

Publications and source records attributed to R Xu.

At least 325 records · Page 18Linked to original sources
PubMed1991

Cyclic AMP stabilizes the degradation of original junctional acetylcholine receptors in denervated muscle.

We used mouse diaphragm muscle in organ culture to study the stabilization of acetylcholine receptor (AChR) degradation at denervated neuromuscular junctions. After denervation, the degradation rate of the AChRs present prior to denervation (slowly degrading, or Rs, AChRs) accelerates from the predenervation degradation half-life (t1/2) of approximately 8-10 days to a t1/2 of approximately 2-3 days. We report that addition to the organ culture medium of pharmacological agents that elevate cytoplasmic cAMP levels (forskolin, dibutyryl cAMP, and 8-bromo-cAMP) reversed the change in t1/2 caused by denervation, whereas addition of 1,9-dideoxyforskolin, a forskolin analog that does not elevate cytoplasmic cAMP levels, did not reverse the effect of denervation. The degradation rate of AChRs in primary myotube cultures and that of the newly synthesized AChRs in denervated muscle were little affected by forskolin or dibutyryl cAMP. The possibility is raised that the modulation of Rs AChR degradation by innervation may be mediated by cAMP.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1991

[Effect of 654-2 on the cerebral blood flow in patients with ischemic cerebrovascular disease by measurement of 133Xe rCBF and the microcirculation of bulbar conjunctiva].

Eighteen patients with cerebrovascular disorder were observed comparatively using 133Xe rCBF measurement and microcirculation test of bulbar conjunctiva before and after treatment with 654-2. Remarkable decreasing of blood flow in the brain and improving of bulbar conjunctiva microcirculation were found after treatment. We consider that the same drug caused the different change of blood flow in and out brain may due to the reaction of micrangium tissue construction, nerve regulation and different organ's micrangium to Ach. We recommend 133Xe as a objective measurement to estimate brain blood flow. The value of treatment of ischemic cerebrovascular disorder by 654-2 and raising microcirculation test as a objective measurement remains to discussed.

Adult↗
PubMed1990

Allele specific oligonucleotide probes for mouse I-A region and gene: I-A beta.

MHC Class II gene expression is being intensively studied in vitro. In vivo class II gene expression that occurs during G.V.H.R. and allograft reaction has not been studied as well as the gene expression in vitro because such studies require unambiguous detection of graft or host specific MHC class II genes. Although this is possible by using allele specific oligonucleotide probes for individual class II genes, such probes for class II genes in mice have not been described before. We compared the nucleotide sequences of I-A beta genes from various haplotypes and selected a region of minimal homology in the 2nd exon of this gene. We synthesized two oligonucleotide probes corresponding to a 20 nucleotide stretch in the hypervariable region of the I-A beta 1 genes of H-2k and H-2d haplotype mice. These probes specifically detect I-A beta mRNA from mice of appropriate haplotypes. These allele-specific probes should help study the in vivo expression of graft or host specific I-A genes in G.V.H.R. or allograft reaction.

Animals↗
PubMed1990

[Morphometric observation on the mast cells under the acupuncture meridian lines].

Observation of the number, distribution and characteristics of the mast cells under the low impedance acupuncture meridian lines of 19 amputated limbs of patients suffered from osteoblastoma and 21 rats was carried out microscopically after sectioned and toluidine blue stained. Results revealed that the number of the mast cell was more concentrate under the meridian lines in comparison with their control areas. The difference was significant. This experiment reflexed another aspect of the morphological basis of the biophysical nature of the acupuncture meridian.

Acupuncture Therapy↗
PubMed1990

[Study on the biological properties of solubilized HeLa cell receptors for group B coxsackieviruses].

The properties of solubilized receptors for coxsackieviruses B (CBV) on HeLa cells were investigated. It was found that the receptor activity and antigenicity were comparatively sensitive to pH change and were rather stable over a wide range of temperatures (4 degrees C-60 degrees C) but they were destroyed completely when the temperature rose to 100 degrees C. Oxidation and reduction augmented the receptor antigenicity, while the receptor activity was lowered only by oxidation and not by reduction. After lipoprotein was precipitated with heparin buffer, the receptor activity and antigenicity remained in the supernatant. Treatment of the solubilized receptors with proteinase K, trypsin and elastase could partially or completely inactivate the viral receptors. The results suggest that the receptors for CBV on HeLa cells are glycoproteins insensitive to temperature and their sulfhydryl groups are unnecessary for receptor activity.

Endopeptidase K↗