Biomedical subjects

Y Lin

Publications and source records attributed to Y Lin.

At least 577 records · Page 32Linked to original sources

PubMed1993

Structure, expression, and hormonal control of genes from the mosquito, Aedes aegypti, which encode proteins similar to the vitelline membrane proteins of Drosophila melanogaster.

Genomic and cDNA clones of a gene expressed after a blood meal in the mosquito, Aedes aegypti, were identified as having significant similarity to the vitelline membrane protein genes of Drosophila melanogaster. The predicted protein had unusually high contents of alanine, histidine, and proline and contained a region of hydrophobic amino acids that was highly conserved in the predicted protein of the D. melanogaster vitelline membrane protein genes. The 15a gene was expressed from 5 to 40 hr after a blood meal. It was expressed only in the follicle cells of the ovary, particularly in the cells surrounding the oocyte. The 15a gene was expressed in ovaries of the blood-fed, decapitated female in response to an injection of 20-hydroxyecdysone, and in ovaries from non-blood-fed females incubated with the hormone, even in the presence of cycloheximide. A second gene, with weaker homology to 15a, is presumably another member of a family of related genes, as is the case with D. melanogaster vitelline membrane protein genes. This second gene contained a coding sequence similar to a decapeptide recently isolated from mosquito ovaries as an "oostatic factor" (Borovsky et al., FASEB J. 4, 3015-3020, 1990).

Aedes↗

PubMed1993

A sequence-tagged site map of human chromosome 11.

We report the construction of 370 sequence-tagged sites (STSs) that are detectable by PCR amplification under sets of standardized conditions and that have been regionally mapped to human chromosome 11. DNA sequences were determined by sequencing directly from cosmid templates using primers complementary to T3 and T7 promoters present in the cloning vector. Oligonucleotide PCR primers were predicted by computer and tested using a battery of genomic DNAs. Cosmids were regionally localized on chromosome 11 by using fluorescence in situ hybridization or by analyzing a somatic cell hybrid panel. Additional STSs corresponding to known genes and markers on chromosome 11 were also produced under the same series of standardized conditions. The resulting STSs provide uniform coverage of chromosome 11 with an average spacing of 340 kb. The DNA sequence determined for use in STS production corresponds to about 0.1% (116 kb) of chromosome 11 and has been analyzed for the presence of repetitive sequences, similarities to known genes and motifs, and possible exons. Computer analysis of this sequence has identified and therefore mapped at least eight new genes on chromosome 11.

Amino Acid Sequence↗

PubMed1993

Medial vestibular neurons are endogenous pacemakers whose discharge is modulated by neurotransmitters.

1. Neurons in the medial vestibular nucleus (MVN), recorded in a rat brain slice preparation, exhibit a highly regular, high-frequency (5- to 35-Hz) spontaneous discharge. The rhythmic firing rate was constant (< 5% variation) and sustained for a long time (maximum observation, 4 hr). 2. The rhythmic firing was evident even in neurons (n = 15) completely isolated from exogenous input fibers, suggesting that it is due to an endogenous pacemaker property. When recorded intracellularly, the discharge was found to be associated with a smooth, concave pacemaker prepotential, and the rate of firing was reduced in proportion to applied hyperpolarizing current, indicating that these are pacemaker discharges. 3. This conclusion is supported by the observation that perfusion with a low-calcium/high-magnesium Krebs-Ringer solution, which completely and reversibly blocks all synaptic transmission, did not abolish the spontaneous discharge. The low-calcium/high-magnesium solution increased spontaneous firing in some neurons and decreased in others, suggesting that the firing is synaptically modulated and the synaptic influence is tonically active. 4. Application of kynurenate (10 mM), an antagonist of the excitatory amino acid receptors, gradually reduced neuronal discharges in most neurons (22 of 25), while the addition of 10 mM sucrose as an osmotic control had no effect. Depression of neuronal discharges reached its minimum (an average of 60% of the control level) and was maintained at that level until gradually washed out. The rhythmic firing pattern persisted in all neurons even after the excitatory receptors were blocked. 5. When the GABAA receptor antagonist, bicuculline (20 microM), was applied, elevation of neuronal discharges was evident in most neurons (30 of 32) tested. The firing increased gradually, with a final control level of 130% (121-160%). In contrast, the GABAB receptor antagonist, phaclofen (20 microM and 100 microM), had no effect in most neurons (19 of 23) tested. Further, the excitatory and inhibitory action could be detected on the same neuron when bicuculline and kynurenate were both evaluated (n = 10). 6. These results indicate that the spontaneous discharge of MVN neurons is due to an endogenous pacemaker under the tonic influence of both inhibitory and excitatory transmitter actions. The bicuculline-sensitive GABAA receptors and the kynurenate-sensitive glutamate receptors both mediate the tonic modulation.

Amino Acids↗

PubMed1993

Are leukotrienes or PAF involved in hyperbaric oxygen toxicity?

Several very selective leukotriene inhibitors, and a PAF inhibitor, suitable for in vivo use, have been tested for their effects on hyperbaric oxygen toxicity. The leukotriene D4 inhibitor, L660771, and the 5-lipoxygenase pathway inhibitor L663536, failed to affect convulsions or lung damage induced by hyperbaric oxygen (pressure range 515-615 kPa) in either rats or mice. The specific PAF antagonist L659989 showed marginal protection against hyperoxic convulsions and did not alter pulmonary damage. The specific LTB4 antagonist SC-41930 was very effective in inhibiting hyperbaric oxygen-induced convulsions in both rats and mice. SC-41930 also very significantly protected rats against pulmonary oxygen toxicity, but had only marginally significant effects on pulmonary protection in mice.

Animals↗

PubMed1993

Agglutination activity of Limulus polyphemus coagulogen following limited proteolysis.

1. A 14 kDa protein with cell agglutination properties has been purified from endotoxin-activated L. polyphemus amebocyte lysate. Amino terminal sequence analysis indicates that this protein corresponds to a proteolytically cleaved product (coagulin) of coagulogen. 2. Similar cell agglutination activity can be generated, in vitro, by proteolytic cleavage of the coagulogen with either trypsin, endogenous protease or an alpha 2M/enzyme complex isolated from amebocytes. 3. Studies with [125I]-labeled coagulogen showed that only coagulin, not the intact coagulogen, binds to rabbit erythrocytes and formalin-fixed amebocytes. 4. The cell agglutination activity of coagulin towards erythrocytes was not inhibited by various sugars tested, and was not Ca(2+)-dependent. 5. These findings suggest that coagulogen and coagulin are reminiscent of their mammalian counterparts, fibrinogen and fibrin, in their clotting and relative adhesive properties.

Amino Acid Sequence↗

PubMed1993

Effects of a fish oil rich diet on hyperoxic lung damage in mice.

Mice were fed a chow diet plus 10% cellulose, 10% fish oil or 10% sunflower oil for 3 weeks, then exposed to 100% oxygen for 75 h. Large changes in lung fatty acid composition occurred, but this did not affect hyperoxic lung damage nor levels of thiobarbituric acid reactive substances or myeloperoxidase in lungs of mice following exposure to hyperoxia. Thus there is no evidence that the ingestion of large quantities of fish oil increased the susceptibility to the oxidative stress induced by hyperoxia.

Animals↗

PubMed1993

Organic-phase biosensors for monitoring phenol and hydrogen peroxide in pharmaceutical antibacterial products.

Organic-phase biosensors open new opportunities for assays of challenging pharmaceutical products. Such opportunities are illustrated for the rapid determination of phenol and peroxide antiseptics in different anti-infective formulations. The tyrosinase and peroxidase enzyme electrodes offer reliable quantification of these antibacterial agents following sample dissolution in the organic solvent. The dynamic properties of these enzyme electrodes are exploited for rapid and reproducible flow-injection assays of the pharmaceutical products (relative standard deviation = 1.6-1.9%). Such developments should facilitate rapid quality control testing in the pharmaceutical industry and should be applicable to other therapeutic agents and products. Applicability to cosmetic products containing hydrogen peroxide is also demonstrated.

Anti-Infective Agents, Local↗

PubMed1993

Renal allograft rejection: examination of adhesion blockade by antilymphocyte antibody drugs.

An assay was developed to investigate the binding of lymphocytes to cultured human renal epithelial cells. This binding was increased following lymphocyte activation by culture either with a polyclonal mitogen or with allogeneic stimulator cells. It was shown that such activation increased lymphocyte expression of the adhesion molecules CD2, LFA-1, and VLA-4. The ligand for each of these molecules was demonstrated on the surface of cultured renal epithelial cells. Polyclonal antilymphocyte antibody (ALA) preparations are used frequently to reverse intractable episodes of acute renal allograft rejection. It was demonstrated that such agents reduce the binding of activated lymphocytes to renal epithelial cells and subsequent cell lysis with a similar dose-response curve. Application of this assay may allow improved evaluation and titration of therapeutic antibody preparations. A range of monoclonal antibodies specific for components of the three adhesion molecule systems investigated in this work were added to lymphoid cell binding assays. It was found that combinations of these antibodies designed to interfere simultaneously with each of these adhesion interactions inhibited binding less well than the ALA preparation. It is likely that the superior inhibition of binding produced by ALA is due to the polyclonality of the antibodies which can block multiple epitopes on a wide range of potential adhesion molecules.

Antibodies, Monoclonal↗

PubMed1993

Stimulatory effect of calponin on myosin ATPase activity.

Calponin, a calmodulin-binding protein of smooth muscle that inhibits the actin-myosin interaction by binding to actin, was shown to bind to myosin and to stimulate the ATPase activity of myosin to some extent. Actin abolished this myosin-linked, stimulatory effect of calponin. Ca(2+)-calmodulin affected neither the myosin-binding activity nor the stimulatory effect of calponin. We further presented a few data which suggest that calponin may exert regulatory activity toward myosin in quite a different way from caldesmon, another smooth muscle protein that binds to myosin, actin, and calmodulin.

Animals↗

PubMed1993

Role of myosin in the stimulatory effect of caldesmon on the interaction between actin, myosin, and ATP.

We have previously shown that caldesmon at low concentrations stimulates the interaction between actin, myosin, and ATP, while at high concentrations it inhibits the interaction [Ishikawa, R., Okagaki, T., Higashi-Fujime, S., & Kohama, K. (1991) J. Biol. Chem. 266, 21784-21790]. When the effect of caldesmon at low concentrations was monitored by measuring myosin ATPase activity in the absence of actin, the effect was slightly but significantly stimulatory; and at higher concentrations no inhibitory effect was observed. Therefore, we related the stimulatory effect with the myosin-binding property of caldesmon. In the presence of actin, a low concentration of caldesmon was not enough to evince the stimulatory effect: myosin concentration must also be low. This is because the stimulatory effect was obscured when myosin concentration was elevated. Ca(2+)-calmodulin abolished the stimulatory effect of caldesmon. However, the concentration of calmodulin required to abolish the stimulation was higher than that required to abolish the inhibition.

Actins↗

PubMed1993

Renal allograft rejection: expression and function of VCAM-1 on tubular epithelial cells.

The interaction between vascular cell adhesion molecule-1 (VCAM-1) and very late antigen-4 (VLA-4) is known to play an important role in stabilizing the adhesion of lymphocytes to endothelial cells. Such cellular adhesion is crucial to many immunological processes including lymphocyte-mediated cell lysis. In this study the expression of VCAM-1 on renal tubular epithelial cells is demonstrated on biopsy sections recovered during acute renal allograft rejection. Experiments performed using epithelial cells cultured from renal tubules show that VCAM-1 is up-regulated by addition of the inflammatory cytokines tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma). Combination of TNF-alpha and IFN-gamma synergized to induce high levels of VCAM-1 expression. Further experiments demonstrated that the cytokines produced by activated lymphocytes in mixed leucocyte culture also up-regulate expression of VCAM-1. Assays of the adhesion of lymphoid cells to cultured renal epithelial cells showed that cytokine pretreatment of the renal cells enhanced the binding of lymphoid cells. The proportion of bound lymphoid cells was significantly reduced by addition of an antibody capable of blocking the interaction of VCAM-1 with VLA-4. This result indicated that the VCAM-1 induced on renal epithelial cells by inflammatory cytokines is functionally capable of binding VLA-4, thereby enhancing the adhesion of potentially graft-damaging lymphoid cells.

Cell Adhesion↗

PubMed1993

Effect of humidity on hyperoxic toxicity.

Time to onset of hyperbaric oxygen-induced convulsions was measured in mice and rats exposed to hyperbaric oxygen (515-585 kPa) under conditions of low humidity (dry gas, < 10% relative humidity) or in a humidified environment (60% relative humidity). At all pressures tested, the duration of convulsive activity was markedly increased (P < 0.001), because of the earlier onset of severe generalized convulsions, in the groups of rodents exposed to the higher humidity. Pulmonary oxygen poisoning was determined by increases in lung wet and dry weights. Such pulmonary damage was also significantly (P < 0.001) increased in the humidified groups. Hyperoxic toxicity was also measured in rats and mice exposed to approximately 100% oxygen (normobaric hyperoxia) under conditions of 30 or 62% relative humidity. In contrast to the results obtained with hyperbaric oxygen exposure, there was slightly less toxicity in the rodents maintained at 62% compared with 30% humidity in normobaric hyperoxia.

Animals↗

PubMed1993

In vitro molecular reconstitution of the respiratory burst in B lymphoblasts from p47-phox-deficient chronic granulomatous disease.

Epstein-Barr virus-transformed lymphocytes generate superoxide in response to various agonists in an enzymatic reaction similar to that which occurs in stimulated phagocytes. We generated transformed B lymphoblast cell lines from controls, from four patients with p47-phox-deficient chronic granulomatous disease, and from three parents. The cells from controls and from the parents generated 7.0-35 nmol of O2-/10(7) cells per 30 min in response to phorbol myristate acetate. None of the patient cell lines generated any detectable superoxide. Both p47-phox and p67-phox were detected by immunoblot in the cytosol of control and parent cell lines and, as in neutrophils, these proteins had affinity for GTP-agarose. The patients' cell lines contained no detectable p47-phox by immunoblot. mRNA for both cytosolic proteins was detected in all cell lines. We generated cDNA and obtained multiple clones from two patients by polymerase chain reaction. One patient was a compound heterozygote with each allele resulting in an early stop codon. Clones derived from the other patient demonstrated only a GT deletion at base 75. The cDNA for p47-phox was inserted into an EBV-expression vector and stably transfected cell lines were obtained using hygromycin B selection. Transfected cell lines from a p47-phox-deficient patient generated normal levels of superoxide and had readily detectable cytosolic p47-phox. Thus, B lymphoblasts provide an excellent model system for studies of the NADPH oxidase, for expression of functional recombinant forms of oxidase components, and for initial experimental approaches to genetic reconstitution in CGD.

B-Lymphocytes↗

PubMed1993

Collagen production and maturation at the experimental ligament defect stimulated by pulsing electromagnetic fields in rabbits.

Eighty rabbits receiving the square resection (4 x 4 mm) of both patellar ligaments in full thickness at their center were divided into 4 groups, and each group (20 rabbits) were electromagnetically stimulated with different magnetic intensities, 0 (control group), 2, 10, or 50 gauss (G), for 6 hr daily. Pulse frequency and pulse width were 10 Hz and 25 microseconds, respectively. Five animals of each group were sacrificed weekly from 1st to 4th week after operation and the defect tissue was collected for biochemical and ultrastructural evaluations. Before sacrificing, the blood flow of the central portion of patellar defects were measured. Significant increases in blood flow at the defect were observed in 50 G group compared to those of other groups from 2 to 4 weeks after operation. The collagen content in PEMFs groups showed a significant increase compared to that of control group. Furthermore, those increases were higher according to the increase in magnetic intensity. Electronmicroscopically, massive developmental rough endoplasmic reticulum was seen in the fibroblasts at 2 weeks after operation in 50 G group compared to other groups, which suggests the more active collagen production in this group. These results suggest that PEMFs enhanced the blood flow and increased the fibroblasts at the defect. At the same time, PEMFs directly stimulated the collagen production from the fibroblasts, thus accelerate the healing process of the ligament.

Animals↗

PubMed1993

Interaction between T lymphocytes and kidney epithelial cells during renal allograft rejection.

Cultured human renal epithelial cells were treated with the cytokines IFN-gamma and TNF-alpha and alteration in expression and function of markers including Classes I and II MHC antigens and the adhesion molecules LFA-3 and ICAM-1 was examined. It was found that a mixture of IFN-gamma and TNF-alpha induced Class II MHC antigens, up-regulated expression of Class I, LFA-3 and ICAM-1 molecules and enhanced binding of 51Cr-labeled mononuclear immune cells. However, lymphocytes failed to proliferate in response to allo-stimulation by renal epithelial cells. Lymphocytes recovered after four days in mixed culture with allogeneic renal cells were purified and re-stimulated with irradiated spleen cells for five days prior to measurement of proliferation. These lymphocytes failed to proliferate if the spleen cells were syngeneic with the renal cells used in the primary stimulation. However, if the renal cells were from a third-party donor the lymphocytes showed a normal proliferative response to the allogeneic spleen cells. It has been demonstrated that cytokine-stimulated renal epithelial cells bind, but fail to initiate proliferation of, resting allogenic lymphocytes and that activated renal cells can specifically anergise potentially graft damaging allospecific T lymphocytes.

Antigens, CD↗

PubMed1993

The study of relationships between the damage of visual function and hemorrheology, ocular rheography, as well as other related factors in patients with primary open angle glaucoma (POAG).

Researches of glaucoma visual function damage, hemorheology, ocular rheography and other related multiplex factors, with computed multifactorial stepwise regression analysis, indicate that the elevation of intraocular pressure (IOP) is not the only factor to induce visual impairment. POAG patients are shown to have markedly reduced diastolic perfusion pressure in ophthalmic artery, besides prolonged filling time of the retinal artery and vein, diminished erythrocyte deformability and increased platelet adhesion rate. The characteristic of ocular rheographic changes in POAG patients of controlled IOP suggest that the abnormal changes of hemorheology be responsible for the damage of visual function. The abnormal changes of plasma viscosity, blood apparent viscosity, blood viscoelasticity, hematocrit, mean red cell volume etc could be found in addition to the reduction of PO2, SO2% and trace elements (Cr, Zn, Mg, Fe) in patients with POAG. Computed multiply stepwise regression analysis and Bayes discrimination were made among the deteriorate rate of quantitative visual field and 28 factors from the combined investigation. Only the hemorrheological index could be introduced into the multiply regression equations. The more the damage of visual function in POAG patients, the more accurate the discriminatory effect. Based upon the results, and the reports of articles published as well as the search of 1982-1989 Compact Combridge MEDLINE Medical data base, the new clinical concept could be presented that POAG might belong to the scope of blood hyperviscosity syndromes. When IOP elevation and the decrease of ocular artery pressure existed, the damage of visual function in POAG patients should be deteriorated.

Adult↗

PubMed1993

[The isolation of Vibrio alginolyticus bacteriophage].

We identified 4 bacteriophages of V. alginolyticus in 29 ones, which were first isolated from seafood. According to their character of the plaques, they were classified into two kinds: one plaque was clear, the other was opaque. The size of these plaques were different and their diameters are 0.5-3.0mm. By electron microscopy observation, they could be classified into two kinds; one has a long axie and hexagemal head, and a thin-long tail, the other has an equal axie hexagenal head and a very short tail, but the edges and corners aren't clear. The multiplication valence of the phages attained to 10(8-9) pfu/ml. Total lysis rate of 4 bacteriophages was 72.22% to V. alginolyticus. However, the lysis rate of single phage was 9.72-44.4%. 4 bacteriophages all had high host specificity. Cross-lysis reaction wasn't found in the test of original solution of bacteriophages to 612 strains of different genus bacteria and 697 strains of genus Vibrio, but they only showed 39% cross-lysis rate to V. parahaemolyticus and most part of this phenomenon disappeared at 10 RTD of the phages. Thus, the obvious relation of consanguinity was showed between two kinds of bacteria strains.

Bacteriophages↗

PubMed1993

[Application of in situ hybridization using digoxigenin--labeled HBV DNA probe and comparison with biotinylated probe].

A method of in situ hybridization for HBV DNA on liver tissue with digoxigenin-labeled probe is described. We have detected the HBV DNA of sixteen liver biopsies. The results showed that the sensitivity and specificity of digoxigenin-labeled probe for in situ hybridization were hig er and stronger then those of biotinylated probe. The practicality of digoxigenin-labeled probe is better. It is an excellent non-radioactive probe for in situ hybridization, which may eventually replace the biotinylated probe. The localization of HBV DNA in hepatocytes could be classified into 4 types, namely, the whole cytoplasmic, focal cytoplasmic, whole nucleic and nuclear membranous-nucleolus. The results of in situ hybridization using digoxigenin-labeled probe could reflect the free or integrated status of HBV genome and the levels of its genomic replication in hepatocytes. The procedure of in situ hybridization using digoxigeninlabeled probe was also discussed.

Biotin↗