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Biomedical subjects

M Wu

Publications and source records attributed to M Wu.

At least 397 records · Page 22Linked to original sources
PubMed1994

Molecular and functional analysis of a lymphocyte chemoattractant factor: association of biologic function with CD4 expression.

Lymphocyte chemoattractant factor (LCF) is a lymphocyte cell product that stimulates a migratory response in CD4+ lymphocytes, monocytes, and eosinophils. In concert with its chemoattractant activity, LCF induces human T-lymphocyte expression of interleukin 2 receptor. Here we describe the molecular cloning of cDNA encoding human LCF. It is a novel interleukin with no significant homology to any previously described cytokine families. There is an absolute requirement for both autoaggregation of LCF monomers and for membrane-expressed CD4 molecules for LCF-induced migration in lymphocytes.

Amino Acid Sequence↗
PubMed1994

Inhibition of human melanoma growth and metastasis in vivo by anti-CD44 monoclonal antibody.

CD44 is a M(r) 90,000 surface glycoprotein believed to be involved in cell adhesion and migration. We investigated the role of CD44 in tumor growth and metastasis using human melanoma cell lines SMMU-1 and SMMU-2. Both SMMU-1 and SMMU-2 form tumors in the s.c. tissues when injected s.c. in SCID mice but only SMMU-2 metastasizes. Approximately one-half of SCID mice receiving injections of SMMU-2 s.c. develop metastatic tumors. SMMU-2 but not SMMU-1 expresses high levels of the hematopoietic form of CD44 and binds fluorescence-conjugated hyaluronic acid in vitro. GKW.A2 is a monoclonal antibody specific for human CD44 that can completely inhibit the binding of hyaluronic acid to SMMU-2 tumor cells in vitro. Moreover, in vivo injection of GKW.A3 inhibited the growth and metastatic potential of SMMU-2 tumor cells. Administration of GKW.A3 i.v. 1 week after s.c. tumor injection did not inhibit local tumor development but inhibited the formation of metastatic tumors and prolonged animal survival. Therefore, interactions between CD44 on tumor cells and its ligands in vivo may be necessary for tumor growth and metastasis.

Animals↗
PubMed1994

Effective tumor vaccine generated by fusion of hepatoma cells with activated B cells.

Fusion of BERH-2 rat hepatocellular carcinoma cells with activated B cells produced hybrid cells that lost their tumorigenicity and became immunogenic. Syngeneic rats injected with BERH-2-B hybrid cells became resistant to challenge with parental BERH-2 cells, and rats with established BERH-2 hepatomas were cured by subsequent injection of BERH-2-B cells. Both CD4+ and CD8+ cells were essential for the induction of protective immunity; however, only CD8+ cells were required for the eradication of BERH-2 tumors. The generation of hybrid tumor cells that elicit antitumor immune responses may be a useful strategy for cancer immunotherapy.

Animals↗
PubMed1994

Potential use of soluble CD44 in serum as indicator of tumor burden and metastasis in patients with gastric or colon cancer.

Soluble CD44 is present in the serum of normal individuals (2.7 +/- 1.1 nM). The concentration of soluble CD44 in the serum is elevated in patients with advanced gastric (24.2 +/- 9.8 nM) or colon cancer (30.8 +/- 11 nM). Serum CD44 concentration correlated with tumor metastasis and tumor burden. Surgical resection of tumors resulted in decreases in serum CD44 levels. By Western blot analysis, monoclonal anti-CD44 antibody reacted with a major protein with molecular weight between 130,000 and 190,000. In addition, two proteins with molecular weights of 72,000 and 80,000 can also be identified. Therefore, different CD44 isoforms may be present in the serum of cancer patients. Serum CD44 concentrations may be an indicator of tumor burden and metastasis in patients with malignant diseases.

Adenocarcinoma↗
PubMed1994

In vivo and in vitro EPR oximetry with fusinite: a new coal-derived, particulate EPR probe.

The peak-to-peak line width (LW) of the first derivative electron spin resonance (EPR) spectrum of the coal maceral fusinite is reversibly broadened by O2. The extent of broadening per unit of partial pressure of oxygen (pO2) is unusually large, exceeding that of nitroxides by almost two orders of magnitude. This paramagnetic property of fusinite, combined with its very stable physicochemical properties and low toxicity, is shown to be of utility in the measurement of pO2 in vitro and in vivo. Fusinite particles are endocytosed by chinese hamster ovary (CHO) cells in vitro; this is useful for intracellular O2 measurements with commercially available EPR spectrometers operating at 9.1-9.3 GHz. For measurement of oxygen in vivo using low frequency EPR (1.1-1.3 GHz), fusinite provides a sensitive and persistent means to measure pO2 in tissues. Particles implanted into the gastrocnemius muscle of A/J mice remained interstitially in the same position for months with undiminished sensitivity to pO2 and no specific toxic effects.

Adsorption↗
PubMed1994

Steady-state coexistence of three pure and simple competitors in a four-membered reactor network.

In this study we investigate the dynamics of pure and simple competition among three microbial populations in a spatially heterogeneous environment. The environment is modeled as a network of four interconnected bioreactors. Growth has been assumed to be noninhibitory, while maintenance requirements have been neglected. Results of numerical studies indicate that the three competitors may coexist in a stable steady state in a domain of the operating parameters space. Results are presented in the form of two-dimensional operating diagrams. No domain was found in the operating parameter space where more than one steady state is meaningful and stable. Since earlier theoretical studies have shown that two pure and simple microbial competitors may coexist in two interconnected bioreactors while numerical studies have shown that three pure and simple competitors cannot coexist in three interconnected bioreactors, the results of the present study may lead one to speculate the N pure and simple competitors may coexist in a network made of 2N-1 bioreactors.

Ecosystem↗
PubMed1994

Responses of inferior collicular neurons of the FM bat, Eptesicus fuscus, to pulse trains with varied pulse amplitudes.

Under free field stimulation conditions, we studied the responses of inferior collicular neurons of the FM bat, Eptesicus fuscus, to pulse trains with varied pulse amplitudes. Each pulse train consisted of 7 pulses of 4 ms delivered at 24 ms interpulse-intervals (i.e. 42 pulses/s). For a control pulse train, all pulse amplitudes were equal to a neuron's best amplitude which, when delivered in single pulses, elicited maximal number of impulses from the neuron. The amplitudes of individual pulses of the remaining pulse trains were linearly increased or decreased at a slope of 0, 14, 28, 42, 56 and 69 dB/s. All 56 inferior collicular neurons discharged to pulse trains were of two main types. Type I (N43, 77%) neurons discharged to each pulse within a train while type II (N11, 20%) neurons discharged to the first pulse of a train stimulus only. Discharge patterns of the remaining (N2, 3%) neurons changed between type I and type II when stimulated with different pulse trains. The number of impulses discharged by a neuron varied with different pulse trains. In addition, the number of impulses discharged to each pulse by type I neurons also varied among individual pulses within the train. Only 14 neurons (25%) discharged maximally to the control pulse train. Responses of the remaining neurons to other pulse trains were either 30%-120% larger than (N17, 30%) or within 30% (N25, 45%) of the control pulse train response. Furthermore, half of 56 neurons selectively discharged to a most preferred pulse train with a response magnitude which was at least 50% larger than the response to the least preferred pulse train. Possible mechanisms underlying the different discharge patterns are discussed in terms of a neuron's recovery cycle, minimum threshold and inhibitory period relative to the temporal characteristics (pulse repetition rate and amplitude) of the pulse trains.

Acoustic Stimulation↗
PubMed1994

Fatal overdose of 2,4-dichlorophenoxyacetic acid (2,4-D).

An ingestion of an unknown quantity of U 46 D-Fluid (500 g dichlorophenoxyacetic acid/l) in a suicide is described. Although 2,4-dichlorophenoxyacetic acid (2,4 D) is widely used as a herbicide, intoxications are relatively rare. Quantitation of 2,4-D was performed by diethyl ether extraction from acidified samples (viscera) or by deproteinization (blood, plasma) with methanol before HPLC analysis. Postmortem concentrations of 2,4-D in body fluids and tissues are given. The proposed method resulted in a rapid procedure most useful in cases of deliberate poisoning with phenoxyacetic herbicides.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1994

The 1993 Walter Hubert Lecture: the role of the p53 tumour-suppressor gene in tumorigenesis.

The p53 tumour-suppressor gene is mutated in 60% of human tumours, and the product of the gene acts as a suppressor of cell division. It is thought that the growth-suppressive effects of p53 are mediated through the transcriptional transactivation activity of the protein. Overexpression of the p53 protein results either in arrest in the G1 phase of the cell cycle or in the induction of apoptosis. Both the level of the protein and its transcriptional transactivation activity increase following treatment of cells with agents that damage DNA, and it is thought that p53 acts to protect cells against the accumulation of mutations and subsequent conversion to a cancerous state. The induction of p53 levels in cells exposed to gamma-irradiation results in cell cycle arrest in some cells (fibroblasts) and apoptosis in others (thymocytes). Cells lacking p53 have lost this cell cycle control and presumably accumulate damage-induced mutations that result in tumorigenesis. Thus, the role of p53 in suppressing tumorigenesis may be to rescue the cell or organism from the mutagenic effects of DNA damage. Loss of p53 function accelerates the process of tumorigenesis and alters the response of cells to agents that damage DNA, indicating that successful strategies for radiation therapy may well need to take into account the tissue of origin and the status of p53 in the tumour.

Animals↗
PubMed1994

Glucocorticosteroids up-regulate human elastin gene promoter activity in transgenic mice.

Recent characterization of the human elastin gene identified three putative glucocorticoid responsive elements (GRE) within the 5'-flanking DNA. To test the functionality of these cis-elements, transgenic mice that express a human elastin promoter-reporter gene (CAT) construct in a tissue-specific manner were injected with triamcinolone acetonide (TMC) or dexamethasone (DEX), two glucocorticosteroids in clinical use. Subcutaneous injection of these glucocorticoids resulted in a marked, up to 28-fold, enhancement of the CAT activity in the skin at the site of injection. Similarly, intraperitoneal injection of DEX resulted in significant increases in the elastin promoter activity in various internal organs. Furthermore, incubation of skin fibroblast and aortic smooth muscle cell cultures established from the transgenic animals with TMC (10 ng/ml) resulted in marked increases in the elastin promoter activity. These studies demonstrate that glucocorticosteroids act as powerful up-regulators of human elastin promoter activity in transgenic mice.

Animals↗
PubMed1994

Activities of the benzoxazinorifamycin KRM 1648 and ethambutol against Mycobacterium avium complex in vitro and in macrophages.

KRM 1648 is a 4-aminobenzoxazine derivative of rifamycin S with potent in vitro activity against the Mycobacterium avium complex (MAC); the MIC for 90% of 24 MAC isolates from AIDS patients was 0.25 microgram/ml as determined by a radiometric broth macrodilution assay. KRM 1648 was bactericidal for MAC isolates in Middlebrook 7H9 broth, with a reduction in viability of 1 to 4 orders of magnitude over 72 h. In human macrophages, KRM 1648 also was bactericidal, with a reduction of 3 to 4 orders of magnitude in CFU per ml of macrophage lysate at a concentration of 1 microgram/ml; however, the bactericidal activity varied approximately 10-fold among the three MAC serovars tested. In growth medium, ethambutol potentiated the effect of KRM 1648, but this potentiation was modest when tested against MAC in macrophages and also varied between MAC strains. KRM 1648 has potential as an antimycobacterial agent for MAC disease, perhaps in combination with other agents so that the use of lower dosages of KRM 1648 than are needed with other rifamycins may be possible.

Antibiotics, Antitubercular↗
PubMed1994

Four distinct and unusual linker proteins in a mitotically dividing nucleus are derived from a 71-kilodalton polyprotein, lack p34cdc2 sites, and contain protein kinase A sites.

Tetrahymena thermophila micronuclei contain four linker-associated proteins, alpha, beta, gamma, and delta. Synthetic oligonucleotides based on N-terminal protein sequences of beta and gamma were used to clone the micronuclear linker histone (MLH) gene. The MLH gene is single copy and is transcribed into a 2.4-kb message encoding all four linker-associated proteins. The message is translated into a polypeptide (Mic LH) that is processed at the sequence decreases RTK to give proteins whose amino acid sequences differ markedly from each other, from the sequence of macronuclear H1, and from sequences of typical H1s of other organisms. This represents the first example of multiple chromatin proteins derived from a single polyprotein. The delta protein consists largely of two high-mobility-group (HMG) boxes. An evolutionary analysis of HMG boxes indicates that the delta HMG boxes are similar to the HMG boxes of tsHMG, a protein that appears in elongating mouse spermatids when they condense and cease transcription, suggesting that delta could play a similar role in the micronucleus. The micronucleus divides mitotically, while the macronucleus divides amitotically. Surprisingly, macronuclear H1 but not Mic LH contains sequences resembling p34cdc2 kinase phosphorylation sites, while each of the Mic LH-derived proteins contains a typical protein kinase A phosphorylation site in its carboxy terminus.

Amino Acid Sequence↗
PubMed1994

Involvement of nitric oxide and nitrosothiols in relaxation of pulmonary arteries to peroxynitrite.

Peroxynitrite (ONOO-) is an inflammatory cell-derived oxidant, formed by the reaction of superoxide anion (O2-) with nitric oxide (NO), which was recently reported to relax vascular tissues. In the present study, the potential role of NO in the mechanism of relaxation in isolated bovine endothelium-denuded pulmonary arterial smooth muscle rings to ONOO- was evaluated. Potassium-preconstricted pulmonary arterial rings rapidly relaxed for a prolonged period of time on exposure to ONOO- (0.01-0.1 mM). The relaxation after 1 min of exposure to ONOO- (0.1 mM) was reduced 49 and 87%, respectively, by inhibitors of the stimulation of soluble guanylate cyclase, methylene blue, and LY-83583. In contrast, a scavenger of hydroxyl radicals, dimethyl sulfoxide, did not alter this response. Decomposed 0.1 mM ONOO- (which is primarily nitrite) and 0.1 mM nitrite caused a relaxation of pulmonary artery, which slowly developed over 15 min. Small quantities of NO were detected by chemiluminescence quantification methods when ONOO- was added to buffer. Exposure of pulmonary arterial tissue or buffer containing glutathione (GSH) to ONOO- caused a time-dependent increase in the observed generation of NO, whereas decomposed ONOO- produced 10% of the NO generated by ONOO- on incubation with pulmonary arterial tissue. Treatment with diethyl maleate, an agent that depletes tissue GSH, reduced both the relaxation and the formation of NO detected from pulmonary artery on exposure to ONOO-. GSH solutions treated with ONOO- appear to have generated a nitrosothiol-like vascular relaxant compound. Thus ONOO- appears to relax vascular tissue, in part, by nitrosylating tissue GSH (or other thiols), which subsequently releases NO over prolonged time periods.

Aminoquinolines↗
PubMed1994

[Confirmative test of human semen stain and mixed stain by immunohistochemical method using anti-human sperm monoclonal antibodies].

The stain of the human semen, the mixture of the human semen and vaginal secretion as well as the semen of the bull, goat, pig, dog, rabbit, rat and mouse was examined by the immunohistochemical method using anti-human sperm monoclonal antibodies (SMAB). The result revealed that the SMAB E10 could make a distinction between the human semen, the mixture of the human semen and vaginal secretion, and the seven kinds of animal semen. It is concluded that this method can be used for the species identification of the semen and the mixed stain under the general condition.

Animals↗
PubMed1994

[Distribution of ABH substances in normal secretor human tissue cells by avidin-biotin complex method].

The distribution and location of ABH substances in 54 various kinds of normal secretor human tissue cell of known ABO type were studied by Avidin-Biotin complex (ABC) method. It was firstly demonstrated that 18 different kinds of tissue cells contained ABH substances, which were as follows: neuron and nerve fiber, astrocyte, oligodendrocyte, ependyma epithelial cells, epithelial cells of soft meninges, epithelial cells of parotid gland duct, taste bud cells of tongue, acinar and epithelial cells of duct of buccal gland, epithelial cells of rectal mucous membrane gland, regenerated liver cells of hepatocirrhosis, basal cells of stratified aquamous epithelium of epiglottis, spermiogenesis and spermatozoa of seminiferous tubules, epithelial cells of tubuli reti, rete testis and tubuli epididymis, both primary and secondary follicles of ovary and decidua cells of endometrium. Some new phenomena were observed as follows: ABH substances in chief cells more than those in parietal cells of gastric gland, locally distributed ABH positive cells in stratum spinosum of stratified squamous epithelium of skin, segmentally distributed ABH positive cells in pseudostratified ciliated columanal epithelium of epiglottis. The ABH substances were located at the infranuclear and/or supranuclear region and/or brush border of the epithelial cells of submaxillary gland, mosaic distributed ABH substances were found in the epithelia of both sweat and submaxillary glandular ducts. A few controversies about distribution of ABH substances were solved. The relationship between H and A, B substances, origin of ABH substances, source of ABH substances in body fluids. Production of ABH substances and cell differentiation, mosaicism and inconsistency of ABH distribution are discussed and compared with other reports.(ABSTRACT TRUNCATED AT 250 WORDS)

ABO Blood-Group System↗
PubMed1994

[Fast detection of Alu DNA in human tissues by Alu-PCR].

This paper reports a direct PCR method for the detection of Alu DNA in 18 different kinds of human tissue using primers of Alu 9.1 and Alu 9.2 without DNA extraction. The results showed that besides fresh tissues, some formalin fixed paraffin embedded tissues can be correctly analyzed with PCR. Different amounts of PCR products were obtained from different types of tissues. The duration of fixation in formalin is an important factor exerting an influence on the quantity of the high molecular weight DNA and the results of PCR. No obvious influence of the duration of storage of paraffin embedded tissues on the PCR results was observed. This method is quite simple, sensitive and rapid to perform. It can be performed under a condition of avoiding contamination of DNA and DNase as well as the detrimental phenol and chloroform.

Base Sequence↗