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Biomedical subjects

D Shen

Publications and source records attributed to D Shen.

At least 91 records · Page 5Linked to original sources
PubMed1996

Observation and quantitation of lactate in oxidative and glycolytic fibers of skeletal muscles.

In 1H NMR spectroscopic studies of fatiguing skeletal muscles, two peaks consistently arise near 1.3 ppm, typically 15-20 Hz apart at 300 MHz. From a variety of NMR and biochemical evidence, both peaks are identified as lactate. Both the CH3 and CH protons of lactate experience the same shift in intact muscle; this rules out chemical bonding or complexation. The ratio of intensity of the two methyl peaks varies with muscle type and suggests a correlation with oxidative and glycolytic fiber populations. The shift can be accounted for by the presence of paramagnetic myoglobin in the oxidative fibers. Phantom studies, as well as oxygen, temperature, field, and orientation dependence of the muscle spectra are all consistent with an explanation based upon bulk magnetic susceptibility. It is concluded that the two lactate peaks represent separate contributions from glycolytic and oxidative muscle fibers.

Animals↗
PubMed1996

Localization of the human RGR opsin gene to chromosome 10q23.

The human RGR gene encodes an opsin protein (retinal G protein-coupled receptor), which is expressed in Müller cells and the retinal pigment epithelium and is thought to play a role in the visual process. To investigate a possible linkage of the RGR gene to retinal dystrophies, the locus of the gene was mapped on human metaphase chromosomes. Genomic and cDNA fragments of the human RGR gene were used as probes for fluorescence in situ hybridization. Analysis of the fluorescence signals on high-resolution banded chromosomes showed that the RGR gene is localized to human chromosome 10q23. This result now provides for the rapid analysis of this gene with respect to inherited diseases of the retina.

Chromosome Banding↗
PubMed1996

No enemies in the neighborhood: absence of inhibitory neighborhood effects in lexical decision and semantic categorization.

The effect of neighborhood density on visual word recognition was found to be facilitatory for words but inhibitory for nonwords in 3 lexical-decision experiments. However, the facilitation virtually disappeared when the task was changed to semantic categorization (animal vs. nonanimal), despite the presence of a strong frequency effect. None of these experiments showed a consistent inhibitory effect of a higher frequency neighbor. The absence of inhibitory effects suggests that competition does not play a key role in visual word recognition. The data also suggest that the neighborhood density effect is not an access effect but is a task-dependent effect instead.

Adult↗
PubMed1996

The design and preliminary evaluation of a home electrocardiography and blood pressure monitoring network.

A home electrocardiography (ECG) and blood pressure (BP) monitoring network was established in Beijing. The network consisted of three parts: (1) the home ECG and BP monitoring devices; (2) the monitoring centre at the hospital; and (3) the data communication network, for which we chose the public telephone network. The system was tested in our university hospital for two months with 30 patients and six normal volunteers. A preliminary evaluation by the users indicated that the system was acceptable in terms of its efficiency and effectiveness. This paper describes the system design, the preliminary testing procedure, and results.

Adult↗
PubMed1996

[Differential expression of HSU17714 gene in colorectal cancer and normal colonic mucosa].

HSU17714 is a new gene discovered by subtractive hybridization. Its cDNA is 2,932 bp long and the gene is located at human chromosome 22 as defined by fluorescence in- situ hybridization combined fluorescence R-banding technique. Northern blot and RNA dot blot analyses showed that the expression level of HSU17714 gene was significantly lower in 15 cases of colorectal cancer than that in adjacent normal colonic mucosa. The defective expression of HSU17714 in colorectal cancer suggests that it is a new candidate tumor suppressor gene.

Adult↗
PubMed1995

Alternative splicing in human retinal mRNA transcripts of an opsin-related protein.

An opsin-related gene encodes a putative RPE-retinal G-protein-coupled receptor (RGR) that is most homologous to the visual pigments and invertebrate retinochrome. A splice variant of human RGR mRNA can be demonstrated by the sequence of isolated cDNA clones and by the amplification and analysis of human retinal mRNA. The shortened transcript contains a deletion of 114 nucleotides that correspond exactly to the sequence of exon 6 in the human rgr gene. The predicted RGR variant lacks the putative sixth transmembrane domain and has a calculated molecular weight of 27,726. Variable amounts of a 28-kDa protein were found in the retinas of some individuals by immunoblot assay. Since a similar shortened RGR transcript was not detected in bovine retina or RPE, the RGR variant is not essential for vertebrate vision. Analysis of the structure of the rgr gene and of the sequences of cDNA clones indicates that the truncated mRNA may be produced through alternative splicing of pre-mRNA from which a cassette exon is removed and the predicted RGR variant is radically altered in primary structure.

Base Sequence↗
PubMed1995

Touch-evoked agitation produced by spinally administered phospholipid emulsion and liposomes in rats. Structure-activity relation.

BACKGROUND: Phospholipid-based liposomes can alter the kinetics of spinally administered agents. We have observed that spinal delivery of these preparations results in an unexpected touch-evoked agitation, a state in which light touch evokes vocalization by the rat. In the current study we characterized this agitated state induced by various liposome preparations. METHODS: Rats prepared with lumbar intrathecal catheters received a variety of phospholipids delivered spinally as emulsions or as liposomes. Before and after injection, the animal's hot-plate latency (52.5 degrees C surface), spontaneous mobility, and spontaneous and evoked pain behavior were assessed. RESULTS: Spinal delivery of L-alpha-phosphatidylcholine of egg yolk (L-EPC) and the phospholipase hydrolysis product (lyso-L-alpha-phosphatidylcholine [lyso-L-EPC]) produced dose-dependent touch-evoked agitation; the order of potency and rapidity of onset was lyso-L-EPC > L-EPC, with no difference in activity whether administered as an emulsion or as a liposome preparation. Examination of the activity of a series of pure phospholipids revealed the ordering of touch-evoked agitation potency (where PC = phosphatidylcholine) to be L-monopalmitoyl-PC (lyso product of L-dipalmitoyl-PC) > L-dipalmitoyl-PC > L-distearoyl-PC, L-dioleoyl-PC >> L-dilauroyl-PC > L-dimyristoyl-PC; D-dipalmitoyl-PC = 0. The effect of unsaturation on touch-evoked agitation cannot be predicted because dioleoyl-PC and dioleoyl phosphatidylglycerol produced touch-evoked agitation but dipalmitoleoyl-PC did not. Substitution of glycerol for choline as the head group had no influence on touch-evoked agitation. Spinal treatment with an inhibitor of phospholipase (mepacrine) or a cyclooxygenase (ketorolac) blocked the touch-evoked agitation of L-EPC but not that of lyso-L-EPC. CONCLUSIONS: These results emphasize that certain L-isomeric phospholipids with their gel-transition temperatures near body temperature can produce prominent touch-evoked agitation after spinal delivery, an effect likely mediated by a phospholipase hydrolysis product. This touch-evoked agitation, which is consistent with neurotoxicity reported in the early literature on lysophospholipids, suggests that the choice of lipids for the formulation of liposomes intended for spinal drug delivery should be carefully considered.

Animals↗
PubMed1995

[Clinical and immunophenotyping features of CD34-positive acute nonlymphoblastic leukemia].

Antigen CD34 and other markers of cell membrane were investigated in cells from 43 patients with primary acute nonlymphoblastic leukemia (ANLL) by immunofluorescence test. The blast cells of 13 patients (30.2%) expressed antigen CD34. The patients with positive CD34 were no significantly different from the remaining 30 patients with negative CD34 with respect to age, serum lactate dehydrogenase (LDH), hemoglobin, white blood cell count, platelet count and the proportion of blast cells in blood and bone marrow, but their blasts were more likely to express HLA-DR, CD38, CD7 and lack of CD15 antigen. These patients had FAB M1 or M5a morphologic characteristics and lower complete remission (CR) rate. This result demonstrated that CD34 positive ANLL is poorly differentiated.

Adolescent↗
PubMed1995

[Clinical evaluation of serum collagen type IV in diagnosing liver fibrosis].

UNLABELLED: Serum collagen type IV (CIV) levels determined by one step sandwich EIA kit were compared with the serum procollagen type III (PCIII) and hyaluronic acid (HA) in 114 patients with various liver diseases, 30 patients without liver diseases (NL) and 30 controls. RESULTS: serum CIV was significantly increased in chronic active hepatitis, liver cirrhosis and primary hepatic carcinoma. So were PCIII and HA. Serum CIV PCIII and HA were found to be closely related to the degree of fibrosis in 69 patients' liver biopsy studies, but no correlation could be found between these 3 markers. The sensitivity of CIV, PCIII, HA in detecting liver fibrosis were 73.9%, 67.4%, 67.4% with specificity of 95.7%, 91.3%, 100.0% respectively. The early diagnostic value of CIV is better than PCIII and HA; their combination could further raise the diagnostic sensitivity to more than 90.0%.

Collagen↗
PubMed1995

[Value of dobutamine technetium-99m-MIBI SPECT in detecting coronary artery disease].

The value of dobutamine 99mTc-MIBI SPECT (Dobu-ECT) for detecting coronary artery disease (CAD) was assessed in 39 patients. Compared with coronary angiography, the overall sensitivity and specificity of Dobu-ECT for detecting CAD were 92.9% and 90.9%. Of 13 patients with CAD without myocardial infarction, the sensitivity of Dobu-ECT was 84.6%. In detecting CAD with single, double or triple vessel diseases, the sensitivity of Dobu-ECT was 90.9%, 87.5% and 100% respectively. Furthermore, 88.2% of the patients (15/17) with multivessel (two or three vessels) diseases were correctly identified as having multivessel involvement. For detecting CAD, the sensitivity and specificity of dobutamine ECG were 53.5% and 82%. No serious side effects were observed in the study. The results showed that Dobu-ECT is a feasibie, safe and noninvasive method for diagnosing CAD.

Adult↗
PubMed1995

[Preparation of 125I-F(ab')2-DNR-liposomes and radioimmunoassay of their specific conjugating ability].

The F(ab')2-DNR-liposomes were prepared using F(ab')2 obtained from digested monoclonal antibody against human white cells HI30 (CD45). Their affinity constant for peripheral blood mononuclear cells was determined by radioimmunoassay. Ka = 2.0 x 10(9). A good specific conjugation ability was demonstrated. In preparing the immunoliposomes, it was found that F(ab')2 coupled to the smaller liposomes with higher conjugation ratio.

Antibiotics, Antineoplastic↗
PubMed1995

[Effects of electroacupuncture on gastrin, mast cell and gastric mucosal barrier in the course of protecting rat stress peptic ulcer].

The experimental Wistar rats were divided into two groups, the acupuncture group and the control group. Stress-induced gastric ulcer models were established by immersion of restrained rats in water. The electroacupuncture was able to protect stress rat from stress induced peptic ulcer. The results indicated that electroacupuncture protecting rat from stress ulceration was relevant to enhancing gastric mucosal barrier, stabilizing gastric mast cell and inhibiting the gastrin levels in gastric mucous.

Animals↗
PubMed1995

[The study of the relationship between the granule size of immunoliposomes and the conjugate ratio of F(ab')2 of McAb HI30 (CD45)].

The immunoliposomes were prepared by conjugating the F(ab')2 of monoclonal antibodies HI30(CD45) labelled by 125I with the liposomes labelled by 131I, and then were separated by a sephacryl S-300 column. The chromatography showed that the liposomes prepared by ultrasonic method were not homogeneous, and the liposomes of smaller granule size had a higher conjugate ratio. It was also found that the fragment F(ab')2 of McAb conjugated to liposomes could enlarge their granule size.

Animals↗
PubMed1994

A human opsin-related gene that encodes a retinaldehyde-binding protein.

The ligand-binding property of a cytoplasmic membrane-bound protein from bovine retinal pigment epithelium (RPE) has been demonstrated. The putative RPE-retinal G protein coupled receptor (RGR) covalently binds both all-trans- and 11-cis-retinal after reduction by sodium borohydride. The 32-kDa receptor binds all-trans-retinal preferentially, rather than the 11-cis isomer. The amino acid sequence of the opsin-related protein in humans is 86% identical to that of bovine RGR, and a lysine residue, analogous to the retinaldehyde attachment site of rhodopsin, is conserved in the seventh transmembrane domain of RGR in both species. The human gene that encodes the novel retinaldehyde receptor spans 14.8 kb and is split into seven exons. The structure of the gene is distinct from that of the visual pigment genes. These findings support the notion that the rgr gene represents the earliest independent branch of the vertebrate opsin gene family. A second form of human RGR in retina is predicted by alternative splicing of its precursor mRNA. This RGR variant results from the alternative use of an internal acceptor splice site in the second intron of the human gene, and it contains an insertion of four amino acids in the connecting loop between the second and thrid transmembrane domains. Since RGR binds all-trans-retinal preferentially, one of its functions may be to catalyze isomerization of the chromophore by a retinochrome-like mechanism.

Amino Acid Sequence↗