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Biomedical subjects

M Wu

Publications and source records attributed to M Wu.

At least 523 records · Page 29Linked to original sources
PubMed1990

[Superoxide dismutase activity in tissues from 19 cases of hepatocellular carcinoma].

Superoxide dismutase (SOD) activity in hepatocellular carcinoma (HCC) tissue was studied. It was observed that activities of total SOD, Cu, Zn-SOD and Mn-SOD in HCC tissue were lower than those in normal liver tissues respectively (P less than 0.001 & 0.01 less than P less than 0.05). SOD activity in poorly differentiated HCC tissue was lower than that in well differentiated HCC tissue. Contents of copper, zinc and manganese in HCC tissues were lower than those in normal liver tissues respectively (P less than 0.001 & P less than 0.01). This study suggests that decreased content of copper, zinc and manganese may be one of the factors that lead to impairment of SOD activity. The characteristic of lower SOD activity in HCC tissue and poorly differentiated HCC tissue may be a negative regulation to limitless proliferation and poor differentiation of liver cancer cells.

Adult↗
PubMed1990

[Establishment of hybridoma cell lines producing monoclonal antibodies against-p30 antigen].

BALB/c mice were immunized with the purified p30 antigen. SP2/0 myeloma cells and immune spleen cells were fused with 50% PEG (Sigma, MW 3,350-4,000). The cell fusion rate was 93.95%, and the antibody producing rate 21.01%. The technique of limiting dilution was used for cloning of the hybridoma cells. Two hybridoma cell lines E8 and G1 secreting McAb against p30 antigen were obtained. The number of chromosome of both E8 and G1 cell lines was 98.7 +/- 6.54 and 97.7 +/- 7.77, respectively. Results of the PAGE of the ascites generated by the hybridoma cell lines E8 and G1 showed a thick protein band at the gamma-region which was absent from the ascites generated by the SP 2/0 myeloma cells. The immunoglobulin of the McAb E8 and G1 belonged to IgG2 subclass. The results of the immunohistochemical method using the horseradish peroxidase conjugated antibody showed that both E8 and G1 McAb only reacted with epithelial cells of the normal human prostatic glands and their ducts, but did not cross-react with other thirty-four different kinds of normal human tissues. The results of inhibiting ELISA test showed that both E8 and G1 McAb were only inhibited by the human seminal plasma and p30, weakly inhibited by the adult male's urine, but were not inhibited by other eight different kinds of human body fluids and secretions as well as semen from eight different species of animals. It was concluded that McAb of E8 and G1 were organ and species specific.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Treatment of experimental disseminated Mycobacterium avium complex infection in mice with recombinant IL-2 and tumor necrosis factor.

Mycobacterium avium complex (MAC) is the most common bloodstream pathogen isolated from patients with AIDS. We have previously shown that TNF alone or in combination with IL-2 can activate human and murine macrophages in vitro to kill MAC strains isolated from disseminated infections. To determine whether treatment with TNF and IL-2 could effect the course of disseminated MAC infections in a murine model of disseminated MAC infection, we infected C57BL mice with 3 x 10(8) bacteria i.v. and 1 wk later administered: 1) IL-2, 100 micrograms/kg; 2) TNF, 25 micrograms/kg; 3) IL-2, 50 micrograms/kg, and TNF, 12.5 micrograms/kg; and 4) saline. IL-2 was injected i.p. daily with TNF being administered in cycles of 3 out of 4 consecutive days. Fourteen days after starting therapy, blood was cultured and mice were sacrificed for quantitative cultures of liver and spleen homogenates. IL-2, TNF, and IL-2/TNF treated groups showed an 87 +/- 5%, 57 +/- 9%, 88 +/- 6% decrease in bacteremia (p = 0.05 for TNF-treated animals and less than 0.04 for the other two groups, compared with control). The combination IL-2/TNF was the only treatment that showed a trend toward an absolute decrease in the number of bacteria in the blood. Reduction in colony counts of liver and spleen were 77 +/- 4% and 87 +/- 6%, respectively, for treatment with IL-2, 58 +/- 7% and 87 +/- 5% for TNF, and 60 +/- 10% and 82 +/- 6% for IL-2/TNF, respectively. These results suggest that both cytokines may play a role in the control of Mycobacterium avium infection and that the combination of a half-dose of IL-2 and TNF, despite not showing any greater efficacy, can be less toxic than TNF or IL-2 alone and might be useful for the therapy of disseminated infection.

Animals↗
PubMed1989

A comparison of the effects of electrical stimulation of the amygdala and hippocampus on subpallidal output neurons to the pedunculopontine nucleus.

Recordings were made of the electrical activity of neurons in the subpallidal area of urethane-anesthetized rats. Output neurons from the subpallidal area to the pedunculopontine nucleus were identified by antidromic activation. The inputs to subpallidal neurons to single-pulse stimulation of the amygdala and hippocampus were investigated. More than two-thirds of the subpallidal neurons antidromically activated by pedunculopontine stimulation were inhibited by hippocampal stimulation and activated by amygdala stimulation. Subpallidal neurons not antidromically activated by pedunculopontine stimulation also responded to stimulation of the amygdala and hippocampus but no differential effects were observed. The relation of these findings to limbic influences on locomotor activity is discussed.

Action Potentials↗
PubMed1989

Identification and characterization of a new gene (CBP3) required for the expression of yeast coenzyme QH2-cytochrome c reductase.

Respiratory defective mutants of Saccharomyces cerevisiae assigned to complementation group G28 display a deficiency, in the respiratory chain complex coenzyme QH2-cytochrome c reductase. The mutants define a new nuclear gene, designated CBP3, required for the assembly of the complex. Mutations in CBP3 are expressed in the absence of spectrally and immunologically detectable cytochrome b, a catalytic subunit of coenzyme QH2-cytochrome c reductase. The mutational block responsible for the cytochrome b deficiency has been ascribed to a post-translational step based on the observation that cbp3 mutants have wild type concentrations of cytochrome b mRNA and are capable of synthesizing the apoprotein. Western analysis has revealed that cbp3 mutants have reduced levels of a subset of subunit polypeptides of the coenzyme QH2-cytochrome c reductase complex that include apocytochrome b, the iron-sulfur protein, core 4 (14-kDa subunit), and core 5 (11-kDa subunit). A similar phenotype has previously been reported in strains that fail to assemble the complex as a result of mutations in the noncatalytic core subunits. The CBP3 gene has been cloned by transformation of a mutant from complementation group G28 with a yeast genomic library. The gene is 1005 nucleotides long and codes for a primary translation product of 39 kDa. A transcript of a size commensurate with the length of the CBP3 reading frame is detected in total and poly(A+)-enriched RNA. The amino-terminal region of the CBP3 product is basic and probably corresponds to a cleavable mitochondrial targeting signal. An antibody obtained against a trpE/CBP3 fusion protein detects a protein of 40 kDa in wild type yeast mitochondria. This protein is absent in a mutant construct containing a partially deleted copy of the gene. The CBP3 protein is a membrane constituent, although attempts to demonstrate its physical association with the other subunits of coenzyme QH2-cytochrome c reductase have been unsuccessful.

Amino Acid Sequence↗
PubMed1989

Subpallidal-pedunculopontine projections but not subpallidal-mediodorsal thalamus projections contribute to spontaneous exploratory locomotor activity.

The contribution of the pedunculopontine nucleus to exploratory locomotion was investigated in rats. Locomotor activity recorded in a standard open-field apparatus was increased more than two-fold when wooden panels were inserted. This novelty-elicited locomotion was reduced significantly when procaine was injected bilaterally into the pedunculopontine nucleus but not when procaine was injected bilaterally into the mediodorsal thalamus, a second major projection site of the subpallidal area. These results support observations from earlier studies implicating hippocampal-accumbens-subpallidal-pedunculopontine projections in exploratory locomotion.

Animals↗
PubMed1989

Changes of glycoconjugates in human hepatocellular carcinoma.

Receptors of 12 lectins in 25 cases of human hepatocellular carcinomas (HCC) were histochemically investigated by avidin-biotin-peroxidase complex (ABC) method. Liver tissues of five cirrhotic patients and five normal subjects were used as controls. SJA receptor was absent both in HCC and controls, while LCA and PSA receptors were present in all tissues studied here. Receptors of DBA, PHA, PNA, UEAI and SBA which did not bind to normal, cirrhotic and pericarcinomatous liver tissues had the positive rates of 4%, 44%, 16%, 4% and 12% in HCC, respectively. Four lectins which strongly bound to the non-cancer liver tissues had their receptors in 96% (ConA, WGA, RCAI) and 36% (BSAI) of HCC. The pretreatment of tissue sections with neuraminidase abolished most of WGA receptors and exposed some PNA binding sites. There were many differences in lectin distribution between HCC and noncancer liver tissues. The changes of glycoconjugates in HCC were discussed.

Avidin↗
PubMed1989

Hyperdorsoanterior embryos from Xenopus eggs treated with D2O.

Excessively dorsalized embryos of Xenopus laevis develop from eggs treated with 30-70% D2O for a few minutes within the first third of the cell cycle following fertilization. As the concentration of D2O and the duration of exposure are increased, the anatomy of these embryos shifts in the direction of enlarged dorsal and anterior structures and reduced ventral and posterior ones. Twinning of dorsoanterior structures is frequent. Intermediate forms include embryos with large heads but no trunks or tails. The limit form of the series has cylindrical symmetry, with circumferential bands of eye pigment and cement gland, a core of notochord-like tissue, and a centrally located beating heart. D2O treatment seems to increase the egg's sensitivity to the dorsalizing effects of cortical rotation and to stimulate the egg to initiate two or more directions of rotation. Such eggs probably establish thereafter a widened and/or duplicated Nieuwkoop center in the vegetal hemisphere, with the subsequent induction of a widened and/or duplicated Spemann organizer region in the marginal zone, which leads to excessive dorsal development. The existence of these anatomical forms indicates the potential of the egg to undertake dorsal development at all positions of its circumference and suggests that normal patterning depends on the limited and localized activation or disinhibition of this widespread potential.

Animals↗
PubMed1989

The 18-kD protein that binds to the chloroplast DNA replicative origin is an iron-sulfur protein related to a subunit of NADH dehydrogenase.

From a high-salt extract of the purified thylakoid membrane, an 18-kD protein was detected. This protein was translated by the chloroplast ribosomes and could form a stable DNA-protein complex with a cloned chloroplast DNA replicative origin [Nie, Z.Q., Chang, D.Y., and Wu, M. (1987) Mol. Gen. Genet. 209, 265-269]. In this paper, the 18-kD protein is linked to frxB, a chloroplast-encoded, ferredoxin-type, iron-sulfur protein, by N-terminal microsequencing of the purified protein and computer analysis. The identification is further supported empirically by the fact that the electron paramagnetic resonance spectra of the protein indicate the presence of iron-sulfur clusters. A polyclonal antibody raised against a synthetic pentadecameric peptide with amino acid sequence corresponds to the highly conserved region of the frxB protein and reacts strongly and specifically with the 18-kD protein band in protein gel blot analyses. The 18-kD iron-sulfur protein is found to be related to a subunit of the respiratory chain NADH dehydrogenase by its cross-reaction with a polyclonal antibody raised against highly purified NADH-ubiquinone oxidoreductase, a key enzyme of the respiratory chain. These data are consistent with chlororespiration, and, thus, possible implication of chlororespiration in regulating the initiation of chloroplast DNA replication is discussed.

Amino Acid Sequence↗
PubMed1989

Amikacin, ciprofloxacin, and imipenem treatment for disseminated Mycobacterium avium complex infection of beige mice.

The Mycobacterium avium complex (MAC) is a common cause of disseminated infection in patients with acquired immunodeficiency syndrome and is increasingly seen as a cause of infection in other immunocompromised patients. Traditional antimycobacterial therapy often is ineffective, and there is a clear need for antibiotics with proven activity against the MAC. Three agents, amikacin, ciprofloxacin, and imipenem, were tested in vitro for activity against MAC strain 101. Amikacin was bacteriostatic, with an MIC of 4.8 micrograms/ml, which is significantly lower than the concentration in serum obtained with standard dosing. Imipenem and ciprofloxacin had little or no activity alone (MICs, greater than 16 and 4.7 micrograms/ml, respectively), but when they were combined with amikacin there was bactericidal activity. Each agent was tested individually and in combination by using the beige mouse model of disseminated MAC infection. There was no mortality in a group of animals infected with MAC 101 and treated with amikacin alone; also, there was a significant decrease in the infection of the blood, liver, and spleen. There was no apparent improvement in therapeutic effectiveness when amikacin was combined with the other agents. Neither ciprofloxacin nor imipenem was active as a single agent, which was consistent with the in vitro activities of these agents. Amikacin in combination with traditional antimycobacterial agents warrants further study as potential therapy for disseminated MAC infections.

Amikacin↗
PubMed1989

The role of cyclin synthesis, modification and destruction in the control of cell division.

This paper reviews our current knowledge of the cyclins based on observations of the oocytes and eggs of sea urchins, clams and frogs. Cyclins are proteins found in all eukaryotes whose special property is rapid destruction at specific stages in the cell cycle. The cyclins fall into three families. A-type cyclins have been found in clams, flies and frogs. B-type cyclins have been found in clams, flies, frogs, sea urchins and fission yeast. A more distantly related family of three genes is found in Saccharomyces cerevisiae. B-type cyclins appear to be required for cells to enter mitosis, and their destruction is thought to be necessary for exit from mitosis. We describe evidence in support of these ideas, and describe various conditions under which cyclin destruction is delayed or deranged. We conclude with a discussion of the relationship between the cyclins and maturation- (or M phase-) promoting factor and some ideas on how the cyclins may work.

Animals↗
PubMed1989

Transmission electron microscopic study of maize pachytene chromosome 6.

Cytoplasm-free chromosomes are frequently obtained in meiotic chromosome spreads prepared from mildly-fixed maize microsporocytes. These chromosomes are suitable for detailed structural analysis using a published electron microscopic technique. In the electron micrograph, the knobs and heterochromatin regions that have been used for karyotype analyses in the light microscope are clearly visible. Therefore, the electron microscopic map can be easily aligned with the traditional cytological map. In addition to these prominent structural features, numerous electron-dense bands also are observed. To determine whether the bands can be used as markers for the identification of each chromosomal subregion, the banding pattern of chromosome 6 is analyzed. Chromosome 6 is frequently associated with the nucleolus and can be easily recognized. We observed that at the zygotene stage in prophase I, electron-dense regions are detected on each homolog of the synapsing chromosome. During synapsis, the electron-dense regions on both homologs are brought into register to form more conspicuous bands. At the early pachytene stage, the banding pattern is stable and reproducible. Chromosome 6 contains eight dark bands, 19 medium bands and 14 light bands. The bands can be used as intrachromosomal markers for regional assignment of genes in detailed in situ hybridization mapping or cytogenetic studies. As the pachytene stage progresses, condensation of the chromosome bivalents is accompanied by fusion of adjacent bands.

Chromosomes↗
PubMed1989

[Analysis of and repair capacity in 247 cancer patients and normal persons by nucleoid sedimentation technique].

The nucleoid sedimentation technique was developed to analyze DNA repair capacity in 108 cancer patients (esophageal cancer 34, lung cancer 24 and ovarian cancer 50) and 139 normal persons. After exposing lymphocytes to UV in radiation at the dose of 2.5 microJ/mm2, the cells were incubated for different periods of time at 37 degrees C for repairing the damaged DNA. The nucleoid sedimentation distance which corresponds to DNA repair capacity was determined. It was found that most normal persons finished the process of DNA repair in II hours while the cancer patients could not do so even 17 hours after incubation. This study showed that decreased DNA repair capacity may be a component of the genetically determined susceptibility to cancer.

Adolescent↗
PubMed1989

Transfer of foreign genes by electroporation and their expression in mammalian cells.

Expression of foreign genes transferred into mammalian cells by electroporation has been studied. The pX1TK gene, pSV2Neo gene and pUCEJ oncogene have been introduced into MLTK- cells and NIH/3T3 cells, respectively. Stable transformation transient expression of TK gene by MLTK- cells as well as stable and malignant transformation of NIH/3T3 cells have been obtained. Transient expression frequency is about 80% and stable transformation frequency is about 10(-4). Integration of foreign genes into the cellular genome was verified with molecular hybridization. Tumor development was observed after inoculation of transformed cells into nude mice.

Animals↗
PubMed1989

Increased catabolism of phosphatidylcholine to betaine regulates the liver phosphatidylcholine content in rats fed orotic acid.

Feeding a semi-synthetic diet containing 1% orotic acid to rats for one day stimulates the CDPcholine pathway of liver phosphatidylcholine synthesis 4.5-fold without significantly increasing the liver phosphatidylcholine level. The liver betaine level increases 1.6-fold. The present experiments were performed to investigate the source of the increased liver betaine. Orotic acid feeding did not alter the rate of oxidation of 1,2[14C] choline to betaine. After liver phosphatidylcholine was labelled in vivo with 2[14-C]-ethanolamine, over 90% of the choline-derived radioactivity was recovered in liver betaine and this was consistently increased in rats fed orotic acid. It is concluded that the increased synthesis of liver phosphatidylcholine caused by dietary orotic acid is accompanied by an increased rate of liver phosphatidylcholine catabolism, with betaine as the major end-product of the choline moiety.

Animals↗
PubMed1989

[Diagnosis of iron deficiency anemia with an optimum combination of tests].

Basing on the analysis of five tests including serum ferritin, erythrocyte protoporphyrin, serum iron, total iron binding capacity and transferrin saturation in 92 anemic patients who were classified into iron deficient anemia (IDA) and non-iron deficient anemia by their bone marrow iron status, three models of combination of tests were designed by varying the test combination and diagnostic levels in model 1 and 2 and multiple regression analysis in model 3. The sensitivity and specificity for IDA were 93.7% and 93.1% respectively with the optimum scheme of combination of tests from model 2 in which serum ferritin has more weight than other tests. With the optimum scheme from the model 3 which was the discriminant function, the sensitivity and specificity were 93.3% and 100% respectively when the scheme tests the cases who are not included in the calculation of the function. It will decrease the number of false-positive or false-negative diagnosis due to the complex results of combination of test when the optimum combination of tests is used in the investigation of iron status and clinical work.

Anemia, Hypochromic↗