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Biomedical subjects

Y Luo

Publications and source records attributed to Y Luo.

At least 415 records · Page 23Linked to original sources
PubMed1995

Comparison of anesthesia induced by ketamine-fentanyl combination and maintained by propofol or etomidate in New Zealand white rabbits.

Ketamine-fentanyl-propofol and ketamine-fentanyl-etomidate combinations were administered intravenously to four groups of rabbits. Each group received ketamine (30 mg/kg of body weight) and fentanyl (0.025 mg/kg) for anesthesia induction. Either propofol or etomidate was administered by an infusion pump to maintain anesthesia. The rabbit's responses to noxious stimuli were determined before anesthesia was induced and at 10-min intervals thereafter until the rabbit recovered. The effects of the anesthetic combinations on the cardiopulmonary system were measured by monitoring respiratory and heart rates, blood pressure, and arterial blood gas tensions. Etomidate infused at the rate of 0.2 or 0.1 mg/kg/min could maintain surgical anesthesia with fewer effects on the cardiopulmonary system for 40 and 30 min respectively. However, the high mortality and side effects such as hemolysis in these two groups preclude the clinical use of etomidate for anesthesia maintenance. Propofol administered intravenously at rates of 0.8 and 0.4 mg/kg/min could maintain surgical anesthesia for 40 and 30 min respectively. However, relatively severe hypotension, hypercapnia, and respiratory acidosis were associated with this drug. Recovery from the propofol infusion was very rapid. Ketamine-fentanyl-etomidate combination is not recommended for clinical anesthesia in rabbits. Ketamine-fentanyl-propofol combination at a dosage of 30-0.025-0.4 mg/kg/min can be safely used for short-term surgery.

Anesthesia, Intravenous↗
PubMed1995

[Rapid identification and quantitation of barbiturates in plasma using solid-phase extraction combined with GC-FID and GC-MS method].

A rapid screening method for the quantitation and identification of 7 barbiturates in plasma is presented. The method employs solid-phase extraction at pH 3 using X-5 resin as absorbent. Identification of each barbiturate is achieved by retention time and GC-MS. Detection threshold (0.3-0.5 micrograms.ml-1 in a 0.5 ml plasma sample and 1 microliter injection volume), precision (RSD 3.46-6.41%), and linearity (r > 0.99) were satisfactory for blood level monitoring and clinical toxicological applications.

Barbiturates↗
PubMed1995

[Effects of the potassium channel activator cromakalim on human isolated bronchial smooth muscle].

The method which can be used to measure human small smooth muscle function in vitro with the bronchiolar strip preparation was described. The aim of the present study was to investigate the effect of cromakalim against histamine acetylcholine, prostaglandin F2 alpha in human isolated bronchiolar smooth muscle. The results showed the order of relaxant potencies was cromakalim > salbutamol > Theophylline. The relaxation responses to cromakalim, salbutamol, theophylline for histamine or prostaglandin F2 alpha were not significantly different. The relaxation responses to cromakalim, salbutamol, theophylline for acetylcholine were significantly different. Cromakalim was more potent and more effective than salbutamol and theophylline. Cromakalim was able to produce an additional relaxation response in the presence of a maximal relaxation induced by salbutamol and theophylline.

Adult↗
PubMed1995

[The adsorption mechanism of Pb2+, Cd2+, Ni2+ and Co2+ onto activated carbon particles].

The adsorption of Pb2+, Cd2+, Ni2+, Co2+ on activated carbon particles was studied as a function of pH and concentrations of adsorbates. These results showed that the adsorption was strongly pH-dependent and all the adsorption isotherms were in agreement with Freundlich equation. The adsorption could be explained by the surface complexation model. Conditional adsorption constants of surface complexes of Pb2+, Cd2+, Ni2+ and Co2+ with activated carbon particles were calculated by a simplified surface complexation model.

Adsorption↗
PubMed1995

[HPLC-DAD analysis of thirteen soporific sedative drugs in human blood].

An HPLC-DAD qualitative and quantitative method for the analysis of thirteen soporific sedative drugs in human blood established. These drugs were separated by HPLC with acetonitrile-water (35 : 65) (for barbital drugs), methanol-water (60 : 40) and methanol-10% triethylamine acetic acid solution (pH 7.5) (for benzodiazepam and phenothiazine drugs) as eluting phase systems and were detected with photodiode array detector (DAD). These drugs were identified by their spectral characteristics and retention times and quantitatively determined by their peak areas. In the concentration range 0.5-10 micrograms . ml-1, the concentration of all 13 drugs were in proportion to their peak areas. The correlation coefficients were all up to 0.99. The recovery rates from blood were all above 85% without interference from impurities. This method has been used to detect three poisoning samples from the clinic. Good results have been obtained.

Chromatography, High Pressure Liquid↗
PubMed1995

[Detection of the expression of P21, P53, P185 proteins and the mutation of ras, p53 genes in colorectal adenoma and carcinoma].

Expression of P21, P53, P185 proteins, mutations of ras, p53 genes in colorectal adenoma, carcinoma and transitional mucosa were studied using immunohistochemicstry and PCR-RFLP methods. The results showed that the positive rates of P21, P53 and P185 proteins in colorectal adenoma were 53.3%, 27.6% and 13.3% respectively, the expression of P21 and P53 were associated with the malignant potential of adenoma. The positive rates of P21, P53 and P185 proteins in colorectal carcinoma were 72.9%, 37.8% and 47.2% respectively. 9 adenomas and 40 carcinomas contained more than two protein expressions and their co-expression was associated with the malignant potential of adenoma and the prognosis of carcinoma. The mutation rates of ras gene in colorectal adenoma and carcinoma were 26.7% and 41.9% respectively. The ras gene mutation was associated with the malignant potential of adenoma. The mutation rates of p53 gene (codon 248) in adenoma and carcinoma were 3.3% and 14.9% respectively. The prognosis of patients having gene mutation of both ras and p53 were poor. The results suggested that the alterations of ras, p53 and c-erbB-2 genes are involved in the tumorigenesis and development of colorectal carcinoma.

Adenocarcinoma↗
PubMed1995

[Extraction of intraocular magnetic foreign body using intraocular earth magnet].

PURPOSE: To determine the effects of extraction of intraocular magnetic foreign body with intraocular earth magnet (IOEM). METHOD: From 1992 to 1994, 22 cases with intraocular foreign body were treated with self-made intraocular earth magnet (IOEM): 2 patients with foreign body remained on lens, 7 on posterior segment of global wall, 12 lodged in the post pole of retina and 1 on the surface of optic disk. These patients were operated under microscope. The foreign bodies on the posterior segment were removed by using IOEM combined with pars plana vitrectomy. RESULT: The foreign bodies of these 22 patients were successfully removed with one operation respectively. The minimum volume of the foreign bodies was 0.5 x 0.5 x 0.5 mm3. The maximum volume of the foreign bodies was 5 x 2 x 1.5 mm3. The average maximum diameter of the foreign bodies was 2.47 +/- 1.2 mm. CONCLUSION: Intraocular earth magnet (IOEM) is a permanent magnetic instrument with moderate magnetic power. Direct observation and detachment of the foreign body with ocular tissue are necessary during the remowal of the forreign body. This instrument is suitable for intraocular microsurgery, can be handled easily, used for extraction of foreign bodies in anterior chamber, on turbid lens and in vitreous body, in removing foreign bodies in vitreous chamber with obvious injured retina and on posterior segment, the surface of retina, and can also be applied toextract foreign bodies on optic disk as well asforeign bodies partly oldged on global wall.

Adolescent↗
PubMed1994

Three chemically distinct types of oxidants formed by iron-mediated Fenton reactions in the presence of DNA.

Exposure of Escherichia coli to H2O2 leads to two kinetically distinguishable modes of killing: mode I killing occurs maximally near 2 mM H2O2, whereas mode II killing is essentially independent of H2O2 concentrations up to 20 mM. A major portion of H2O2 toxicity is attributed to DNA damage caused by the iron-mediated Fenton reaction. By studying DNA damage during Fenton reactions in vitro, the same complex kinetics were observed and three types of oxidants were distinguished based upon their reactivities toward H2O2 and alcohols and upon iron-chelator effects. Type I oxidants are sensitive to H2O2 but moderately resistant to ethanol; type II oxidants are resistant to both H2O2 and ethanol; type III oxidants are sensitive to H2O2, ethanol, and t-butanol. To explain these results, we hypothesize that type I oxidants are generated upon Fe2+ associated with DNA only through electrostatic interactions and cause mode I killing of E. coli; type II oxidants arise upon Fe2+, which is at least partially base-associated, and cause mode II killing; type III oxidants arise on Fe2+ free in solution and probably do not cause killing. Therefore, particular interactions of DNA with transition metals should be considered to be an integral part of the chemistry and toxicity of H2O2.

DNA↗
PubMed1994

Transformation by homeobox genes can be mediated by selective transcriptional repression.

Altered transcription is a recurrent theme in the field of cancer biology. But despite the central role of transcription in transformation, little is known about the mechanism by which dominant nuclear oncogenes induce malignancies. Homeobox family proteins are prominent examples of transcriptional regulators which control development and can function as oncogenes. Here we explore the molecular basis for transformation by this class of regulators using Oct-2 and Oct-1. We show that the DNA binding POU domains of these proteins are selective and sequence-specific transcriptional repressors that produce malignant lymphomas when they are expressed in T cells of transgenic mice. Mutagenesis experiments identified a specific set of promoters, those containing octamer regulatory elements, as the targets for transformation by selective inhibition of gene expression.

Animals↗
PubMed1994

Biologic activities of the murine beta-chemokine TCA3.

The murine beta-chemokine TCA3 was purified to homogeneity. The biologic activities of the purified glycoprotein were evaluated in vivo and in vitro. Mice injected i.p. with 1- to 100-ng purified rTCA3 exhibited a rapid influx of neutrophils and macrophages. Increased numbers of neutrophils and monocytes were observed in peripheral blood within 15 min and peak at 45 min. After 45 min neutrophil and macrophage levels were increased in the peritoneal exudate with peak levels occurring at 2 h, followed by a subsequent decline by 24 h. Inflammatory responses were induced in a dose-dependent fashion. The in vivo inflammatory responses were mirrored by the pattern of TCA3-induced chemotaxis in vitro. Neutrophils and macrophages responded to similar concentrations of TCA3 (3 x 10(-9) to 10(-8) M). Lymph node cells responded to other chemokines but did not migrate to TCA3. We also demonstrated that rTCA3 stimulates a transient increase in cytoplasmic free calcium in monocytic cells through a PTX-sensitive pathway. Cross-desensitization studies indicate that TCA3 acts independently of other beta-chemokines (MIP-1 alpha and RANTES) and the alpha-chemokine IL-8. Furthermore, TCA3 does not induce a Ca2 lux in cells transfected with cDNA for the C-C CKR-1 chemokine receptor, supporting the conclusion that there are distinct receptors for TCA3.

Amino Acid Sequence↗
PubMed1994

Inhibition of in vivo tumor growth by the beta chemokine, TCA3.

TCA3 is a proinflammatory murine glycoprotein that shares structural features with cytokines of the beta chemokine family and is a chemoattractant for neutrophils and monocytes. To assess the in vivo functions of TCA3, the cDNA was expressed in two mouse myeloma cell lines. Although the transfected and control cells had similar growth rates in vitro, TCA3-expressing tumors demonstrated impaired growth in both normal and immunodeficient mice. Histologic evaluation of the injection sites demonstrated that TCA3 expression resulted in an early neutrophil and monocyte infiltrate accompanied by tumor necrosis. There was complete regression of the TCA3-transfected tumor in some immunocompetent syngeneic mice. The TCA3-transfected cells induced specific and long-lasting immunity in mice that showed complete tumor regression; these animals were resistant to challenge with nontransfected tumor cells. In contrast, priming with irradiated tumor cells provided little protection against challenge with nontransfected tumor, which indicates that TCA3 specifically augments tumor immunogenicity. Mixing TCA3-transfected cells with normal tumor cells causes retarded growth of the normal tumor cells provided the latter are injected into the same site. Furthermore, direct in situ injection of soluble rTCA3 early during the course of tumor implantation also inhibits tumor growth. The data suggest that TCA3 may perform two roles in tumor protection: it induces lymphocyte-independent antitumor activity and stimulates tumor-specific immunity. We speculate that TCA3 has natural adjuvant activities that result in augmented immune responses.

Animals↗
PubMed1994

Serologic analysis of the mouse beta chemokine JE/monocyte chemoattractant protein-1.

Mouse monocyte chemoattractant protein-1 (MCP-1), previously termed JE, is a member of the beta chemokine gene family and a homologue of the human monocyte chemoattractant protein, MCP-1. Mouse rMCP-1 was used to immunize hamsters for the production of mAb. Seven mouse MCP-1-specific mAbs were characterized: two of these mAbs cross-reacted with the human MCP-1, as determined by ELISA. A sensitive and specific capture ELISA for MCP-1 quantitation, which allowed measurement of mouse MCP-1 levels in supernatants from cells stimulated with inflammatory agents, was developed. LPS-stimulated astrocytes produce the highest levels of MCP-1 (80 ng/ml); macrophages and mesangial cells produce lower levels of MCP-1 (2 to 14 ng/ml) after LPS stimulation. IL-1 and TNF-alpha stimulation also can induce low levels of MCP-1 production. Western blot analysis demonstrated that the predominant native form of mouse MCP-1 is a 30-kDa glycoprotein. Two mAbs (2H5 and 6C7) demonstrated dose-dependent neutralization of mouse MCP-1 chemotactic activity. To localize the epitope recognized by one of these neutralizing Abs, the mAb was used to bind a series of genetically engineered truncated variants of human MCP-1. The C-terminal residues 62 to 67 on human MCP-1 molecules seem to be critical to express the epitope recognized by the neutralizing 2H5 anti-MCP-1 mAb. However, multiple sites on the MCP-1 molecule seem to be critical for bioactivity. Thus, these Ab reagents provide a useful tool to explore the biology of the mouse MCP-1 beta chemokine.

Animals↗
PubMed1994

The POX1 gene encoding peroxisomal acyl-CoA oxidase in Saccharomyces cerevisiae is under the control of multiple regulatory elements.

Transcription of POX1, the gene encoding peroxisomal acyl-CoA oxidase in the yeast Saccharomyces cerevisiae, is controlled by the carbon source given for cell growth. The gene is repressed in glucose, derepressed in glycerol, and induced in oleate. This regulation is controlled by cis-acting elements in the 5' region of the gene, which bind regulatory proteins. By deletion analysis and DNA band shift assays, we have characterized three such elements in the POX1 upstream sequence, two upstream repression sequences and an upstream activating sequence. Each was able to regulate the transcription of a heterologous gene construct iso-1-cytochrome-c (CYC1)/lacZ.

Acyl-CoA Oxidase↗
PubMed1994

Investigation of meperidine and its metabolites in urine of an addict by gas chromatography-flame ionization detection and gas chromatography-mass spectrometry.

A gas chromatographic method with flame ionization detection (FID) for the quantitative analysis of meperidine and mass spectrometry (MS) for the qualitative analyses of meperidine and its metabolites in urine was established. Meperidine, normeperidine and acetyl normeperidine in urine were extracted with ether. Free and conjugated meperidinic and normeperidinic acids in urine, which are hydrophillic, were hydrolyzed by acid, esterified with methanol and derivatized with acetic anhydride. Meperidine and its four metabolites were identified by GC-MS. Meperidine was measured by GC-FID during 72 h after intramuscular administration of meperidine to an addict.

Biotransformation↗
PubMed1994

Only one of the paired Schizophyllum commune A alpha mating-type, putative homeobox genes encodes a homeodomain essential for A alpha-regulated development.

The A alpha mating-type locus is one of four master regulatory loci controlling sexual development in Schizophyllum commune. The A alpha locus contains two homeobox genes, Y and Z, encoding two homeodomain-related proteins, Y and Z. Y and Z are each multiallelic genes. When haploid strains form fusion cells, only particular combinations of Y and Z alleles activate A alpha-regulated sexual development. The role of the putative homeodomain was examined in several Y and Z alleles by site-directed mutagenesis of regions critical to secondary structure and function of homeodomains. Mutations of the Z homeobox do not affect the function of Z proteins in A alpha-activated development, but mutations of Y homeoboxes destroy the ability of Y proteins to activate development. We conclude that only one of two A alpha homeodomain-related regulators relies upon the homeodomain motif to effect gene expression in sexual development. This conclusion affords a refinement of our working hypothesis for the mechanism by which A alpha proteins may regulate target gene expression. On the basis of our results with the Z protein, we speculate that the DNA-binding motifs of some transcriptional regulators may be lost or modified during evolution once these regulators have been recruited to participate in complexes with other DNA-binding proteins.

Amino Acid Sequence↗
PubMed1994

NDF/heregulin stimulates the phosphorylation of Her3/erbB3.

Her3/erbB3 has been identified as a third member of the epidermal growth factor receptor (EGFR) family [(1989) Proc. Natl. Acad. Sci. USA 86, 9193-9197; (1990) Proc. Natl. Acad. Sci. USA 87, 4905-4909]. The natural ligand for Her3 has not been identified. Although recently NDF has been proposed as a specific ligand for Her4 [(1993) Nature 366, 473-475; (1993) J. Biol. Chem. 268, 18407-18410], we report here that Her3 was phosphorylated on tyrosine not only in three breast carcinoma cell lines, MDAMB453, MDAMB468 and SKBR3, but also in Her3-transfected CHO cells in response to NDF stimulation. In further studies, cells were reacted with 125I-labeled NDF and then chemically crosslinked. Immunoprecipitation with anti-Her3 revealed a dense high Mw band, greater than 400 kDa. The results suggest that NDF may be a ligand of Her3 and induces receptor hetero-oligomerization.

Animals↗