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M Zhou

Publications and source records attributed to M Zhou.

At least 145 records · Page 8Linked to original sources
PubMed1999

Adrenomedullin is upregulated in the heart and aorta during the early and late stages of sepsis.

Although circulating levels of adrenomedullin (ADM), a newly reported vasodilatory peptide with 52 amino acid residues in the human and 50 amino acid residues in the rat, are elevated during the early and late stages of sepsis, ADM levels in cardiovascular tissues and its precise localization remain to be determined. To study this, rats were subjected to sepsis by cecal ligation and puncture (CLP), followed by administration of 3 ml/100 g b.wt. normal saline to these and sham-operated animals. The heart and thoracic aorta were harvested at 5 h (i.e. the early stage of sepsis) and 20 h (late sepsis) after CLP. Tissue levels of ADM were determined by radioimmunoassay. The localization of ADM in the left ventricle and thoracic aorta was examined by using immunohistochemistry and electron microscopy techniques. The results indicated that ADM levels in the heart and thoracic aorta increased significantly at 5 h after CLP and remained elevated at 20 h after the onset of sepsis. Immunohistochemistry findings showed that ADM immunoreaction products were localized in the cytoplasm of the cardiac myocytes and aortic endothelial cells. Using electron microscopy, ADM immunoreaction products were found in the cytoplasmic matrixes. The immunostainings were also associated with the outer membranes of mitochondria and vesicles of the myocytes as well as vascular endothelial cells. It appears that the cardiovascular tissues, among other organ systems, contribute to the increased levels of plasma ADM under those conditions. Since ADM is localized in different cell populations in the heart and the large blood vessel (i.e. myocytes versus vascular endothelial cells), this peptide may play a differential role in regulating cardiac and vascular functions during sepsis as an autocrine and/or paracrine mediator.

Adrenomedullin↗
PubMed1999

Alternative splicing and hypermutation of a nonproductively rearranged TCR alpha-chain in a T cell hybridoma.

Like Ig genes, TCR genes are formed by somatic rearrangements of noncontiguous genomic V, J, and C regions. Unlike Ig genes, somatic hypermutation of TCR V regions is an infrequent event. We describe the occurrence of spontaneous hypermutation in a nonproductively rearranged TCR alpha-chain gene in a clonal T cell hybridoma that had lost its productively rearranged alpha-chain. The mutating hybridoma was eventually supplanted in culture by a nonmutating variant that had restored an open reading frame in the nonproductively rearranged TCR alpha-chain through the use of cryptic splice sites in the V alpha region. Evidence is presented for the presence of cDNA reverse transcripts of the TCR alpha-chain within the hybridoma, suggesting a role for reverse transcriptase in the generation of mutations.

Alternative Splicing↗
PubMed1999

Fluorometric method for the enzymatic determination of cholesterol.

A fluorometric method for the enzymatic determination of cholesterol content has been developed using a novel fluorogenic H2O2 probe, Amplex Red. This assay is performed in a 96-well microplate, and it is a one-step method amenable to automated procedures. Using commercially available cholesterol, our assay allows detection of 5 pmol (2 ng) cholesterol per well, which is 100-fold more sensitive than published fluorometric and colorimetric methods. When applied to the measurement of cholesterol levels in serum and food samples, the Amplex Red-based method has been found more attractive since the oxidation product of the Amplex Red method has superior long wavelength spectra which are less susceptible to interference from the biological compounds.

Ampyrone↗
PubMed1999

Cloning, expression and crystallization of pyrimidine nucleoside phosphorylase from Bacillus stearothermophilus.

Pyrimidine nucleoside phosphorylase (PYNP) from B. stearothermophilus has been cloned and purified for crystallization. Crystals of a potential protein-inhibitor complex have been prepared by co-crystallization techniques using the substrate analog pseudouridine. These crystals provide good-quality diffraction images to 2.7 A and belong to space group P21. The asymmetric unit contains the dimer structure of PYNP with unit-cell parameters a = 53.9, b = 71.9, c = 123.3 A and beta = 96.9 degrees.

Amino Acid Sequence↗
PubMed1999

Reduction in vascular responsiveness to adrenomedullin during sepsis.

BACKGROUND: Although sepsis is characterized by an early, hyperdynamic phase followed by a late, hypodynamic phase, the mechanism responsible for the transition from the hyperdynamic to the hypodynamic state remains unknown. Since recent studies have shown that adrenomedullin (ADM), a novel potent vasodilatory peptide, is upregulated during sepsis, the aim of this study was to determine whether the reduced vascular responsiveness to ADM is associated with the transition from the hyperdynamic phase to the hypodynamic phase of sepsis. MATERIALS AND METHODS: Adult male Sprague-Dawley rats were subjected to sepsis by cecal ligation and puncture (CLP). At 5 and 10 h (i.e., the hyperdynamic phase of sepsis) or 20 h (the hypodynamic phase) after CLP, the thoracic aorta or small intestine was harvested and preconstricted with norepinephrine. Adrenomedullin (10(-7) M) was applied and the percentage of ADM-induced vascular relaxation in the aortic ring and isolated small intestine was determined. RESULTS: The responsiveness to ADM in the thoracic aorta was not altered at 5-10 h, but decreased significantly at 20 h after CLP. Although ADM-induced relaxation in resistance blood vessels of the small intestine did not change at 5 h, it decreased markedly at 10 and 20 h after the onset of sepsis. CONCLUSIONS: Since the transition from hyperdynamic to hypodynamic sepsis takes place between 10 and 20 h after CLP, it is likely that reduced vascular responsiveness to ADM may be responsible for such an event during the course of polymicrobial sepsis. In view of this, maintenance of vascular ADM responsiveness by pharmacologic agents appears to be a novel approach for preventing or delaying the occurrence of hypodynamic sepsis and septic shock.

Adrenomedullin↗
PubMed1999

A mutational analysis of the acetylcholine receptor channel transmitter binding site.

Mutagenesis and single-channel kinetic analysis were used to investigate the roles of four acetylcholine receptor channel (AChR) residues that are candidates for interacting directly with the agonist. The EC50 of the ACh dose-response curve was increased following alpha-subunit mutations Y93F and Y198F and epsilon-subunit mutations D175N and E184Q. Single-channel kinetic modeling indicates that the increase was caused mainly by a reduced gating equilibrium constant (Theta) in alphaY198F and epsilonD175N, by an increase in the equilibrium dissociation constant for ACh (KD) and a reduction in Theta in alphaY93F, and only by a reduction in KD in epsilonE184Q. This mutation altered the affinity of only one of the two binding sites and was the only mutation that reduced competition by extracellular K+. Additional mutations of epsilonE184 showed that K+ competition was unaltered in epsilonE184D and was virtually eliminated in epsilonE184K, but that neither of these mutations altered the intrinsic affinity for ACh. Thus there is an apparent electrostatic interaction between the epsilonE184 side chain and K+ ( approximately 1.7kBT), but not ACh+. The results are discussed in terms of multisite and induced-fit models of ligand binding to the AChR.

Acetylcholine↗
PubMed1999

Outcome for adjustment disorder with depressed mood: comparison with other mood disorders.

BACKGROUND: A review of the research literature on the diagnostic category of adjustment disorder indicates that its construct validity has not been established. Nevertheless, the diagnosis is made frequently, with an estimated incidence of 5-21% in psychiatric consultation services for adults. METHODS: Retrospective data was used to evaluate the construct validity of the adjustment disorder diagnostic category. The data primarily consisted of SF-36 Health Status Survey responses by a large group of adult psychiatric outpatients before treatment and again six months after beginning treatment. Subjects were divided into five diagnostic groups, and MANOVA, MANCOVA and chi square were used to clarify relationships among diagnoses, sociodemographic data and SF-36 scores. RESULTS: Diagnostic categories were significantly different at baseline, but did not differ in terms of outcome at six-months follow-up. There was a significant gender difference at baseline and a significant difference in gender distribution across diagnostic categories. LIMITATIONS: Structured interviews were not used for initial diagnoses, nor is there an estimate of the reliability of diagnoses among the clinicians. The patient attrition rate for six-months follow-up data was about 50%. Finally, patients received individualized treatment, with some patients receiving both medication and psychotherapy. CONCLUSIONS: Female patients were significantly more likely to be diagnosed with major depression or dysthymia than with an adjustment disorder. Females were also more likely than males to score lower on the mental health related scales of the SF-36 at admission. Patients diagnosed with an adjustment disorder scored higher on all SF-36 scales than did the other diagnostic groups at baseline and again at follow-up. There was no significant difference among diagnostic groups with regard to treatment outcome, suggesting that the adjustment disorder group can benefit as much as the other groups from treatment.

Adjustment Disorders↗
PubMed1999

HLA-G transgenic mice.

We have generated a number of transgenic mice using DNA segments derived from the HLA-G gene. Using these mice we have examined the pattern of expression dictated by HLA-G promoter elements in mice and shown that HLA-G functions both as a restriction element and a transplantation antigen recognized by murine T cells. In addition, we have shown that trophoblast cells expressing H-2Kb under the control of HLA-G promoter elements affect maternal T cell phenotype and responsiveness during pregnancy. Using these same HLA-G/H-2Kb transgenic mice we have shown that trophoblast cells, expressing an inducible enzyme that degrades tryptophan, protects allogeneic conceptus expressing paternally-inherited transgenes from attack by maternal T cells that leads to fetal rejection.

Animals↗
PubMed1999

Chromosomal aneuploidy in leukemic blast crisis: a potential source of error in interpretation of bone marrow engraftment analysis by VNTR amplification.

BACKGROUND: Polymerase chain reaction (PCR) amplification of polymorphic microsatellite or minisatellite DNA markers has proven to be a fast, sensitive, and specific technique in post-transplantation monitoring of bone marrow engraftment, as well as early detection of residual disease and relapse. Deletion or amplification of chromosomal segments carrying marker loci, as can occur in leukemia and other hematologic malignancies, may result in loss or increased dosage of marker alleles. Examination of these marker alleles by PCR therefore may give aberrant results, which might lead to misinterpretation of bone marrow transplantation (BMT) engraftment studies. METHODS AND RESULTS: We report a case of chronic myelogenous leukemia treated by BMT. PCR amplification of the minisatellite at the apoB locus on chromosome 2 was used to monitor the donor bone marrow engraftment. The patient experienced relapse in blast crisis with a near-haploid karyotype with loss of recipient-specific apoB allele causing an aberrant PCR result for bone marrow engraftment that mimicked full donor engraftment. CONCLUSIONS: Loss or gain of polymorphic DNA markers because of chromosomal losses or gains in some hematologic malignancies may affect the interpretation of bone marrow engraftment studies by PCR. When choosing polymorphic markers for such studies, it is important to avoid those that will be affected by expected chromosomal alteration, if possible. In addition, any abberant post-transplantation typing should prompt further investigation to rule out the possibility of chromosomal aberration. Review of all pertinent laboratory studies is important to avoid misinterpretation of results from a single test for engraftment analysis.

Adult↗
PubMed1999

The engagement of Sec61p in the ER dislocation process.

Sec61p comprises the endoplasmic reticulum (ER) channel through which nascent polypeptides are imported and from which malfolded proteins have been suggested to be exported, or dislocated, back to the cytoplasm. We have devised a genetic screen for dislocation-specific mutant alleles of SEC61 from S. cerevisiae by employing the unfolded protein response to report on the accumulation of misfolded proteins in the ER. Three of the isolated sec61 alleles are fully proficient in protein translocation into the ER, but defective in the elimination of a misfolded ER luminal substrate and a short-lived ER membrane-spanning model protein, which are otherwise rapidly degraded by cytoplasmic proteolysis in wild-type cells. Our results point to the fourth luminal loop and third transmembrane domain of Sec61p that markedly influence dislocation. We suggest that distinct features of the Sec61-translocon direct the two-way translocation processes.

Alleles↗
PubMed1999

Analysis of volatile compounds and their contribution to flavor in cereals.

Recent developments in methods for isolation and measurement of volatiles from cereals are reviewed. The main types of isolation methods, namely, direct extraction, distillation, and headspace, have recently been complemented by solid phase microextraction. Direct solvent extraction provides efficient recovery of compounds with a broad range of polarities and volatilities, whereas headspace techniques provide relatively clean extracts. Supercritical fluid and solid phase microextractions have not yet been fully evaluated for cereals. GC and GC/MS remain the dominant techniques for measurement of the extracted compounds, although new electronic noses show promise. Relating these results to human perception requires careful control to ensure valid comparisons and, in this respect, aroma extract dilution analysis is a useful procedure.

Chromatography, Gas↗
PubMed1999

Changes in cerebral cortex size are governed by fibroblast growth factor during embryogenesis.

We show that fibroblast growth factor 2 (FGF2) and FGF receptors are transiently expressed by cells of the pseudostratified ventricular epithelium (PVE) during early neurogenesis. A single microinjection of FGF2 into cerebral ventricles of rat embryos at E15.5 increased the volume and total number of neurons in the adult cerebral cortex by 18% and 87%, respectively. Microinjection of FGF2 by the end of neurogenesis, at E20.5, selectively increased the number of glia. Mice lacking the FGF2 gene had fewer cortical neurons and glia at maturity. BrdU studies in FGF2-microinjected and FGF2-null animals suggested that FGF2 increases the proportion of dividing cells in the PVE without affecting the cell-cycle length. Thus, FGF2 increases the number of rounds of division of cortical progenitors.

Animals↗
PubMed1999

The clinical significance of Fas expression in leukemia: questions and controversies.

Binding of agonistic anti-Fas (APO-1/CD95) antibodies or Fas ligand (Fas-L) induces apoptosis in some Fas+ leukemias, and anti-Fas antibody was originally investigated as a possible therapeutic reagent. More recently, a number of studies have examined a potential role for the Fas/Fas-L pathway in chemotherapy-induced apoptosis as well as the effect of Bcl-2 on this pathway. These studies are briefly reviewed here.

Antibodies, Monoclonal↗
PubMed1999

Effect of gender, treatment site and psychiatric comorbidity on quality of life outcome in substance dependence.

Patients receiving treatment for substance dependence frequently endorse high rates of psychological impairment and other measures of reduced quality of life. We conducted a baseline and six-month follow-up study of a series of one hundred and three unselected patients receiving treatment for a substance abuse or dependence problem. Women and patients requiring in-patient detoxification demonstrated the most psychological impairment at baseline, as measured by the mental component summary of the SF-36. Inpatient site of treatment was associated with continued psychological impairment six months following treatment. More aggressive psychiatric and psychological interventions may be indicated for women and for inpatient substance dependence populations.

Adult↗
PubMed1999

An NMR study of the structural basis of the wide range of pharmacological functions of acetylsalicylic acid.

The interaction between acetylsalicylic acid (aspirin) and membrane was studied by NMR spectra. (1) NMR spectra showed acetylsalicylic acid did not insert into membrane; (2) 1H NMR spectrum recorded by spin-echo pulse sequence showed protons of the aromatic ring interacted with membrane; (3) the change of spin-lattice relaxation (T1) of 31P was ascribed to the association of acetylsalicylic acid to the polar head of lecithin; (4) the self-diffusion coefficient measured by pulsed field gradients NMR showed the mobility of acetylsalicylic acid was restricted by membrane and that acetylsalicylic acid changed membrane viscosity. Based on the results, the relationship between the interaction and the mechanism of the wide pharmacological functions of acetylsalicylic acid is discussed.

Aspirin↗
PubMed1999

Inflammatory disease in HLA-B27 transgenic rats.

UNLABELLED: A spontaneous inflammatory disease in rats transgenic for HLA-B27 resembles the B27-associated human spondyloarthropathies. Colitis and arthritis, the two most important features, require T cells, gut bacteria, and high expression of B27 in bone marrow-derived cells. Control rats with HLA-B7 remain healthy. Most rats with HLA-Cw6 (associated with psoriasis vulgaris) remain healthy; a minority develop mild and transient disease. Rats with a mutant B27 with a Cys67-->Ser substitution resemble wild-type B27 transgenics, but with a lower prevalence of arthritis. A similar phenotype is seen in B27 rats co-expressing a viral peptide that binds B27. Disease-prone LEW but not F344 B27 rats develop high serum IgA levels concurrent with disease progression. Colitis is associated with high interferon-gamma, arthritis with high interleukin-6. Disease is similar in B27 LEW, F344, and PVG rats, but the DA background is protective. CONCLUSIONS: The spondyloarthropathy-like disease in rats is specific for HLA-B27 but does not require Cys67. Arthritis but not colitis is particularly sensitive to B27 peptide-binding specificity. Genetic background exerts a strong influence, but some phenotypic differences exist between permissive strains that do not influence disease susceptibility. The data favor a role for B27 peptide presentation in arthritis, but other mechanisms to explain the role of B27 have not been excluded.

Amino Acid Sequence↗