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Biomedical subjects

Q Li

Publications and source records attributed to Q Li.

At least 793 records · Page 44Linked to original sources
PubMed1996

[Mastoid pneumatization and secretory otitis media].

75 ears of 44 patients with secretory otitis and 80 ears of 40 patients with normal ear were observed and reserched. All of the cases were received X-ray examination of mastoid process in Schuller's lateral projection. The size of the air cell system was obtained by planimetry: the method what was originally devised by Diamant. The outline of the mastoid air cell system (MACS) was marked out on the radiograph and then transferred to graph paper where the number of mm2 can be counted directly. According to measuring the planimetric area of MACS. The mastoids were divided into two categories: pneumatization type and nopneumatization type. 5 of 69 ears with pneumatization mastoid (7.2%) were secretory otitis, while 70 of 86 ears with nopneumatization (81.4%) were secretory otitis. It was significantly different (P < 0.001) camparing the number of ears with secretory otitis. We believe that the degree of mastoid pneumatization is associated with the occurring and prognosis of secretory otitismedia.

Adolescent↗
PubMed1996

[Effects of oxymatrine on arrhythmia in dogs with myocardial infarction].

AIM: To study the effects of oxymatrine (Oxy) on arrhythmia in dogs with myocardial infarction. METHODS: Partly ligating the left anterior descending coronary artery in the open-chest dogs produced myocardial infarction of left anterior ventricular wall. After 5-8 d, the diastolic excitability threshold (DET), the effective refractory periods (ERP) and arrhythmias were determined by programmed electric stimulation (PES). RESULTS: Oxy (i.v. 50 mg.kg-1) increased DET from 2.53 +/- 1.28 to 3.19 +/- 1.62 V, lengthened ERP from 182 +/- 25 to 219 +/- 43 ms at normal region and from 206 +/- 49 to 235 +/- 55 ms at infarct region in left ventricle, but had no effects on dispersion of ERP, QTc interval and ventricular tachycardia (VT) or ventricular fibrillation (VF). Procainamide (Pro) (i.v. 25 mg.kg-1) increased DET and lengthened ERP and QTc interval, but decreased the dispersion of ERP. Pro prevented PES-induced VT/VF and spontaneous ischemia-related VF. CONCLUSION: The increased DET and lengthened ERP of Oxy are its anti-arrhythmic mechanism.

Alkaloids↗
PubMed1995

Evaluation of contact sensitivity to formaldehyde and tetramethylthiuram monosulfide using a modified lymphocyte transformation test.

To examine the validity of a modified lymphocyte transformation test for evaluating contact hypersensitivity from weak sensitizers, guinea pigs were sensitized with formaldehyde (F) or tetramethylthiuram monosulfide (TMTM) using the maximization test procedure. Lymph node cells from the animals were then cultured with F or TMTM, in the presence or absence of epidermal cells (EC). Transformed lymphocyte counts were evaluated by uptake of 3H-thymidine. Nonsensitized guinea pigs were used as controls. The lymphocytes from sensitized guinea pigs showed stronger blastogenesis when cultured with F or TMTM in the presence of EC than when the sensitizers were not added to the culture and the response depended on the concentration of F or TMTM. Cultures in the absence of EC also showed significant enhancement of blastogenesis by F or TMTM, but the responses were significantly weaker than those in the presence of EC. Lymphocytes from the control animals did not show significantly enhanced blastogenesis in response to F or TMTM, even when EC was added to the cultures. The results suggested that contact sensitivity for weak sensitizers can be evaluated by this modified lymphocyte transformation test, especially when lymph node cells were co-cultured with EC.

Analysis of Variance↗
PubMed1995

Involvement of a cellular surface factor(s) in lipid-free apolipoprotein-mediated cellular cholesterol efflux.

Involvement of cellular surface factors in cellular lipid efflux mediated by lipid-free apolipoprotein has been investigated. Lipid-free human apolipoprotein (apo) A-I generated net efflux of cholesterol and phospholipid from mouse peritoneal macrophages and rat aorta smooth muscle cells. Ratio of cholesterol to phospholipid was much lower in the lipid released by this mechanism from the smooth muscle cells than that from the macrophages, in agreement with our previous observation (Li, Q., Komaba, A. and Yokoyama, S. (1993) Biochemistry 32, 4597-4603). On the other hand, free apoA-I did not cause any lipid efflux from human erythrocytes. In contrast, apparent efflux of cellular cholesterol to HDL was similarly observed from all of these three cellular membranes. Trypsin treatment of the cultured macrophages completely inhibited apoA-I-mediated efflux of cholesterol and phospholipid. Smooth muscle cells also showed complete inhibition of the apoA-I-mediated cellular lipid efflux by trypsin treatment except that it required longer incubation with the enzyme. The same cellular treatment with trypsin even by prolonged incubation had only a limited effect on apparent cellular cholesterol efflux to HDL and apolipoprotein-free lipid microemulsions. Thus, free apolipoprotein-mediated cellular lipid efflux seems to depend on a trypsin-susceptible cellular surface factor(s) that erythrocytes may lack, being distinct from physicochemical cholesterol exchange reaction between cell and lipoprotein.

Animals↗
PubMed1995

[14C]2-deoxyglucose uptake in the brain of the ring dove (Streptopelia risoria). I. Prolactin-induced uptake.

Quantitative [14C]2-deoxyglucose (2DG) autoradiography was used to identify areas of the ring dove brain involved in the expression of incubation behavior. Compared with non-breeding controls, 2DG uptake was increased in birds of both sexes during late incubation in all areas of the fore, mid- and hind-brain examined. This increase occurred irrespective of whether the birds were sitting on their eggs at the time of 2DG administration. A similar pattern of 2DG uptake into the brain was observed in non-breeding females treated with 30 I.U. ovine prolactin (i.p.) twice daily for 5 days. It is concluded that there is a generalised increase in neural activity in the brain of doves during late incubation which may be dependent on increased concentrations of plasma prolactin.

Animals↗
PubMed1995

Independent regulation of cholesterol incorporation into free apolipoprotein-mediated cellular lipid efflux in rat vascular smooth muscle cells.

Cholesterol was poorly available to free apolipoprotein (apo)A-I-mediated cellular lipid efflux from cholesterol-loaded rat vascular smooth muscle cells generating cholesterol-poorer pre-beta-HDL particles than those generated from macrophages by the same reaction (Li, Q., Komaba, A., and Yokoyama, S. (1993) Biochemistry 32, 4597-4603). The factors known to induce transformation of the smooth muscle cells into a macrophage-like stage were used in order to modulate this reaction, such as human platelet-derived growth factor, macrophage colony-stimulating factor, and phorbol 12-myristate-13-acetate (PMA). When the cells were stimulated by PMA following the pretreatment with platelet-derived growth factor plus macrophage colony-stimulating factor, cholesterol efflux mediated by free apoA-I increased 3-fold without changing phospholipid efflux, resulting in generation of pre-beta-HDL particles more rich in cholesterol. This treatment had only a little or no effect on apparent cellular cholesterol efflux to HDL or lipid microemulsion, respectively. Overall cellular free cholesterol pool size was unaffected by the treatment, and probing by extracellular cholesterol oxidase did not detect gross change in the cellular surface cholesterol. This specific enrichment of cholesterol in the apoA-I-mediated cellular lipid efflux was reversed by protein kinase C inhibitors. Measurement of intracellular cholesterol esterification suggested that PMA induced translocation of intracellular cholesterol to a specific pool for apoA-I-mediated efflux, and a protein kinase C inhibitor reversed this effect.

Animals↗
PubMed1995

Stimulation of fetal hemoglobin production by short chain fatty acids.

Butyrate, a four-carbon fatty acid, and its two-carbon metabolic product, acetate, are inducers of gamma-globin synthesis. To test whether other short-chain fatty acids share this property, we first examined whether propionic acid, a three-carbon fatty acid that is not catabolized to acetate, induces gamma-globin expression. Sodium propionate increased the frequency of fetal hemoglobin containing erythroblasts and the gamma/gamma + beta mRNA ratios in adult erythroid cell cultures and F reticulocyte production in a nonanemic juvenile baboon. Short-chain fatty acids containing five (pentanoic), six (hexanoic), seven (heptanoic), eight (octanoic), and nine (nonanoic) carbons induced gamma-globin expression (as measured by increase in gamma-positive erythroblasts and gamma/gamma + beta mRNA ratios) in adult erythroid burst-forming unit cultures. There was a clear-cut relationship between the concentration of fatty acids in culture and the degree of induction of gamma-globin expression. Three-, four-, and five-carbon fatty acids were better inducers of gamma globin in culture as compared with six- to nine-carbon fatty acids. These results suggest that all short-chain fatty acids share the property of gamma-globin gene inducibility. The fact that valproic acid, a derivative of pentanoic acid, also induces gamma-globin expression suggests that short-chain fatty acid derivatives that are already approved for human use may possess the property of gamma-globin inducibility and may be of therapeutic relevance to the beta-chain hemoglobinopathies.

Adult↗
PubMed1995

Characterization of the murine gene encoding the hyaluronan receptor RHAMM.

We describe the isolation and characterization of the murine gene encoding RHAMM, a hyaluronan receptor which regulates focal adhesion turnover, is required for cell locomotion and is a critical downstream regulator of ras transformation. The RHAMM gene spans at least 20 kb and comprises 14 exons ranging in size from 75 to 1099 bp. Primer extension studies indicate that the major transcription start point is in position -31, relative to the start Met. Northern blot analysis of mouse fibroblast RNA identified two hybridizing species of 4.2 and 1.7 kb. Comparison of cDNA clones and RT-PCR products with the genomic clones identified alternately spliced exons in both the coding and 5' noncoding regions of RHAMM. In the coding region exon 4 is alternately spliced. The major RHAMM transcript (RHAMM1) in 3T3 fibroblasts does not contain exon 4 and encodes a protein of 70 kDa. A minor transcript containing exon 4, namely RHAMM v4, encodes a 73-kDa protein, as demonstrated by isoform-specific antibodies. Western analysis demonstrated both a major 70-kDa (RHAMM 1) and minor 73-kDa RHAMM protein (v4) in 3T3 murine fibroblast cell lysates. The functional significance of these two isoforms is currently being investigated.

Amino Acid Sequence↗
PubMed1995

Partial restoration of inactivated ribosomes with sodium borohydride or amino acids.

The aldehyde radical of ribose C1' at position 4324 in rat liver 28S rRNA generated by RNA N-glycosidase was either reduced to an hydroxyl group by sodium borohydride or converted into aldimine through a nucleophilic addition of amino acid used as a primary amine. Analysis of the R-fragment of 28S rRNA by polyacrylamide gel electrophoresis showed that the reduction of aldehyde to an hydroxyl group with sodium borohydride was highly specific. The protein synthesis activity of modified ribosomes was partially restored with the removal of the active aldehyde by sodium borohydride or amino acid. Reduction of aldehyde with sodium borohydride restored 43.1% of the protein synthesis activity. Among the twenty natural amino acids tested, tryptophan and histidine could restore 57.4% and 42.1% of the ribosome activity when brome mosaic virus RNA was used as mRNA. We came to the conclusion that the active aldehyde radical at position 4324 of 28S rRNA in modified ribosome may cause the inactivation of the ribosome for protein synthesis.

Algal Proteins↗
PubMed1995

The position of integration affects expression of the A gamma-globin-encoding gene linked to HS3 in transgenic mice.

Proper expression of the human beta-globin (beta Glb) locus is dependent on the presence of a major regulatory element located upstream from the beta Glb gene cluster, the locus control region (LCR). The LCR, as well as the individual DNase-I-hypersensitive sites from which it is composed, have been shown to provide position-of-integration-independent expression in transgenic mice. Here, we report that a transgenic founder carrying multiple integrations of a hypersensitive site 3::A gamma globin gene (HS3::A gamma) construct produced three types of progeny, one with zero A gamma expression in the adult stage, one with minimal A gamma expression (1% of A gamma-expressing cells) and one with abundant A gamma expression (100% A gamma-expressing cells). The possibility that these phenotypes were due to parental imprinting or to DNA rearrangements of the transgene or to point mutations of the HS3 core or the A gamma promoter were excluded. The pattern of inheritance of the three HS3::A gamma transgene phenotypes indicate that the transgene has integrated into three different chromosomes. These results provide direct evidence that the HS3 of the LCR is not sufficient to protect the A gamma gene from position effects excerted by the surrounding chromatin.

Animals↗
PubMed1995

A novel cell-cycle-dependent 350-kDa nuclear protein: C-terminal domain sufficient for nuclear localization.

We have screened human scleroderma patients for immunoreactivity with the components of the nucleus and the mitotic apparatus. We announce the identification of a novel cell-cycle-dependent nuclear protein using serum from a CREST patient AH. AH protein first appears at the nucleus of G2-phase and associates with the centrosome throughout the cell cycle. As chromosomes condense during the prophase, AH protein becomes enriched at the kinetochores. During mitosis, AH protein progressively disperses from the kinetochore and becomes diffusely localized in the cytoplasm and in telophase; it appears to be enriched within the intracellular bridge. Molecular cloning and transfection studies reveal that the 350-kDa AH protein contains a coiled-coil and a globular domain at the C-terminus that is sufficient for nuclear localization.

Amino Acid Sequence↗
PubMed1995

Simian virus 40 T antigen-induced amplification of pre-parietal cells in transgenic mice. Effects on other gastric epithelial cell lineages and evidence for a p53-independent apoptotic mechanism that operates in a committed progenitor.

Gastric units in the glandular epithelium of the mouse stomach contain several types of continuously renewing epithelial cells. Acid-producing parietal cells are derived from a multipotent stem cell that also gives rise to mucus-producing pit cells and pepsinogen- and intrinsic factor-producing zymogenic cells. We used nucleotides -1035 to +24 of the mouse H+/K(+)-ATPase beta subunit gene (H+/K(+)-ATPase beta subunit-1035 to +24) to examine the consequences of expressing simian virus 40 T antigen (SV 40 TAg) in the normally rare, nonproliferating, short-lived pre-parietal cell progenitor. Light and electron microscopic morphologic studies plus multilabel immunohistochemical analyses of postnatal day (P) 14-80-day transgenic mice revealed that SV40 TAg produces a 50-70-fold amplification of pre-parietal cells which become the predominant cell type in gastric units. Differentiation to mature parietal cells is blocked, resulting in hypochlorhydria and an associated systemic iron deficiency. SV40 TAg-induced pre-parietal proliferation is accompanied by apoptosis. Examination of adult transgenic mice homozygous for p53 wild type or p53 null alleles established that the apoptosis occurs through a p53-independent pathway. H+/K(+)-ATPase beta subunit -1035 to +24/SV40 Tag is not expressed during differentiation of the zymogenic lineage. Nonetheless, P28-P80 transgenic mice exhibit an apparent block in the conversion of pre-zymogenic to zymogenic cells. This block appears to be quite specific: conversion of preneck to neck cells and neck to pre-zymogenic cells is not affected. Comparison of normal and transgenic mice that are p53+/+ or p53-/- confirmed that the loss of mature zymogenic cells is not dependent upon p53. Although H+/K(+)-ATPase beta subunit -1035 to +24 is not active in pit cell progenitors or their differentiated descendants, there is a 2-3-fold increase in mature pit cells in transgenic animals. Our findings (i) demonstrate an approach for amplifying and characterizing pre-parietal or other progenitor cell populations in gastric units, (ii) reveal an SV40 TAg-inducible, p53-independent apoptotic mechanism that operates in a committed epithelial progenitor cell, and (iii) provide a transgenic mouse model for defining factors that may mediate progression through specific points in the differentiation programs of the parietal and zymogenic cell lineages or that may influence decisions about allocation to the pit cell lineage.

Animals↗