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Biomedical subjects

J Wu

Publications and source records attributed to J Wu.

At least 1,351 records · Page 75Linked to original sources
PubMed1993

Hepatitis C virus antibodies in patients with chronic liver disease: ELISA and RIBA HCV strip immunoblot assay results.

In a study using the current first generation Ortho ELISA, a second generation Ortho ELISA, and the RIBA HCV strip immunoblot assay, all patients who were strongly positive for antihepatitis C virus (HCV) on ELISAs (OD490 > 3) were reactive to RIBA for multiple bands. While all ELISA false positive samples had low or intermediate OD490 values, RIBA confirmed HCV reactivity in 50% of the patients reactive to ELISA with a low suspicion of HCV infection, thus suggesting that RIBA HCV strip immunoblot assay will be most useful for patients who react weakly positive or intermediate to ELISA.

Chronic Disease↗
PubMed1993

Inhibition of gap junctional conductance by long-chain acylcarnitines and their preferential accumulation in junctional sarcolemma during hypoxia.

Electrophysiological and biochemical sequelae of myocardial ischemia occur within minutes of the onset of myocardial ischemia in vivo. Both conduction delay and conduction block occur rapidly within the same time interval as the accumulation of long-chain acylcarnitines. In the present study, double whole-cell voltage-clamp procedures were used to assess the influence of long-chain acylcarnitines on gap junctional conductance in isolated pairs of canine ventricular myocytes. Long-chain acylcarnitine (5 microM) decreased gap junctional conductance from 153 to 48 nS in a time-dependent and reversible manner. Although the amplitude of junctional current was reduced by 68%, the current continued to demonstrate a linear current-voltage relation. The extent of endogenous accumulation of long-chain acylcarnitines in junctional regions of the sarcolemma was assessed in isolated myocytes in which endogenous free, short-chain, and long-chain acylcarnitine pools had been equilibrated with [3H]carnitine. Under normoxic conditions, long-chain acylcarnitines were not detectable in junctional sarcolemma of myocytes as assessed using electron microscopic autoradiography. Exposure of myocytes to hypoxia (PO2, < 15 mm Hg) for 10 minutes resulted in the preferential accumulation of endogenous long-chain acylcarnitines in junctional sarcolemma (173 +/- 5 x 10(5) molecules/microns 3), a concentration that was sevenfold greater than that found in nonjunctional sarcolemma. Therefore, endogenous long-chain acylcarnitines accumulate preferentially in junctional regions of the sarcolemma during short intervals of hypoxia. Exogenously supplied long-chain acylcarnitines can markedly decrease cellular coupling in a reversible manner, suggesting that this amphiphile may contribute to the marked slowing in conduction velocity in the ischemic heart in vivo, not only by suppressing the rapid Na+ inward current directly, as has been shown previously, but also by decreasing cellular coupling.

Animals↗
PubMed1993

The in utero initiation with DMN alters the complement of cytosolic glutathione S-transferases and the phenobarbital-induced expression of c-jun and c-myc oncogenes in primary neonatal rat hepatocytes.

As revealed by a novel in utero-in vitro hepatocarcinogenesis model, a single exposure to dimethylnitrosamine (DMN) elicited in postnatal (and fetal) primary rat hepatocytes (i) immunocytochemically detectable, widespread increases in their complement of the alpha, mu and especially pi classes of cytosolic glutathione S-transferases (GSTs); and (ii) changed patterns (with respect to controls) of the phenobarbital (PB)-evoked increases in steady state levels of c-jun and c-myc mRNA's. These results indicate that DMN causes both transient cytotoxic effects and a broad, permanent initiation in fetal proliferating hepatocytes.

Animals↗
PubMed1993

Measuring the psychological construct of control. Discriminant, divergent, and incremental validity of the Shapiro Control Inventory and Rotter's and Wallstons' Locus of Control Scales.

The psychological construct of control is increasingly thought to be an important variable in psychosomatic medicine, but there are limitations with how it has been measured by previous instruments. The current study details four limitations of previous instruments as a rationale for developing a new multi-faceted, multi-dimensional instrument to measure control, the Shapiro Control Inventory (SCI). Discriminant, divergent, and incremental validity of the SCI is compared with the Rotter's Internal/External Locus of Control Scale and Wallstons' Multidimensional Health Locus of Control Scales on five groups, one normal and four clinical groups (depression, generalized anxiety disorder, borderline personality, and panic disorder). Analysis of variance showed significant differences among populations on each of the nine SCI scales. The majority of these results were highly significant, whereas for Rotter's scale the results were barely significant, and for Wallstons' three scales, not at all significant. Correlations of the SCI scales with Rotter's and Wallstons' scales were small to moderate, but in no case explained more than 15% of the variance. The SCI also provided incremental validity over Rotter's and Wallstons' scales both for sensitivity (clinical versus normal) and specificity (between clinical groups). The discussion section provides suggestions for future research.

Adolescent↗
PubMed1993

[Cytotoxicity to hepatoma BEL-7402 cells of an antitumor monoclonal antibody-streptonigrin conjugate].

Streptonigrin, a highly active antitumor antibiotic, was covalently conjugated to anti-human hepatoma monoclonal antibody 3A5 via the active ester method. The conjugate showed biological activities and UV spectra characteristics of streptonigrin and McAb 3A5. The molar ratio of streptonigrin to 3A5 was 2-6:1, with protein recovery of 76%. The conjugate retained 12.5% of drug activity and nearly full antibody activity, though as the number of streptonigrin molecules in the conjugate increased, the antibody activity of the conjugate decreased. As determined by clonogenic assay with human hepatoma BEL-7402 cells in vitro, the inhibitory potency of the conjugate was 63-fold stronger than that of free streptonigrin. For KB cells (which react weakly with 3A5) the cytotoxicity was 11-fold weaker. The results indicate that the McAb 3A5-streptonigrin conjugate is selective for target cells.

Antibodies, Monoclonal↗
PubMed1993

Phagocytosis of platelet in coronary heart disease patients with blood-stasis syndrome.

Phagocytosis of platelets was studied under electronmicroscope in 36 healthy persons and 64 coronary heart disease (CHD) patients with blood-stasis syndrome (BSS). The result showed that both the number of latex particles phagocytized by platelet and platelets which phagocytized latex particles were decreased in CHD with BSS. It was also found in this group that most of the platelets having active-phagocytosis were of medium size. The proportion of large platelets containing plentiful glycogen granules was much more in CHD patients with BSS and the shapes of platelets were changed readily with active exocytosis and aggregations. Therefore the present findings of disability of platelet phagocytosis might be considered the basic change in CHD with BSS.

Adult↗
PubMed1993

Conformation changes of p53 proteins in regulation of murine T lymphocyte proliferation.

This report shows that p53 gene expression is required for proliferation of Concanavalin A (ConA)-stimulated murine T lymphocytes. p53 gene-specific antisense oligodeoxynucleotides strongly inhibited expression of p53 gene in T lymphocytes, causing suppression of ConA-induced cell proliferation. In contrast, the complementary-sense oligomers had no inhibitory effects. Northern and immunoprecipitation-blotting assay data, however, showed no change in p53 mRNA and proteins synthesized in T lymphocytes before and after ConA stimulation. p53 proteins in the resting and ConA-stimulated T cells had different immunoreactivity with specific monoclonal antibodies. p53 from resting T cells only reacted with "wild-type form" p53-specific monoclonal antibody (PAb246); whereas, p53 from ConA-stimulated T cells was recognized by "mutant-form" p53-specific monoclonal antibody (PAb421). These results suggest that the conformation of p53 proteins in resting and ConA-stimulated T cells are different. The p53 conformation changes may be related to the regulation of murine T lymphocyte proliferation.

Animals↗
PubMed1993

c-Myb and v-Myb are differentially phosphorylated by p42mapk in vitro.

The product of the c-myb proto-oncogene is a highly conserved transcription factor that has been shown to function as both a transactivator and repressor. The v-myb oncogenes of E26 leukemia virus and avian myeloblastosis virus (AMV) encode proteins truncated at both the amino and carboxy termini, deleting portions of the DNA-binding and negative regulatory domains present in c-Myb. Similar truncations of c-Myb alter its function, suggesting that the viral proteins lack important regulatory sequences. Interestingly, eight potential sites of phosphorylation by proline-directed protein kinases conserved between the avian, murine and human Myb proteins are clustered in or near the negative regulatory domain of c-Myb. The majority of these sites are deleted in both the E26 and AMV viral proteins. In this paper we show that one proline-directed protein kinase, p42mapk, phosphorylates bacterially synthesized avian and murine c-Myb but not AMV v-Myb in vitro. We find that p42mapk phosphorylates c-Myb on serine and threonine, but not on tyrosine. Furthermore, deletion analysis indicates that the sites of phosphorylation map to the C-terminal negative regulatory domain. We speculate that the inability of v-Myb to be phosphorylated by p42mapk may contribute to its oncogenic properties.

Animals↗
PubMed1993

[A comparative study of six different staining methods on neurofibrillary tangles and senile plaques].

Six different staining methods were evaluated for demonstrating SPs and NFTs by using serial sections of brain tissue collected from aged patients with or without senile dementia. The methods used were as follows: the Bodian, Modified Beilschowsky, Periodic acid methenamine silver (PAMS), New methenamine silver (MS), PAS and Congo Red. SPs and NFTs were demonstrated in the cerebral cortex of aged patients with or without dementia. Among these 6 methods Bodian gives a more reliable result in demonstrating tangles and plaques of the classic and primitive types but not the diffuse type. The MS method clearly demonstrated all the 3 types of SPs particularly the diffuse plaque, but could not show the NFTs. The result indicates that combination of Bodian and MS methods seemed to be the most reliable method for routine neuropathological investigation.

Aged↗
PubMed1992

Site-directed mutagenesis of tyrosine hydroxylase. Role of serine 40 in catalysis.

We have investigated the role of serine 40 (Ser-40) in tyrosine hydroxylase (TH) catalysis of basal and activated enzymes by protein kinase A (PKA)-mediated phosphorylation. Wild type and mutant TH were transiently and stably expressed in AtT-20 cells, and the enzymatic activities of the recombinant enzymes were analyzed. The specific enzymatic activity of transiently expressed TH mutants Ser-40-->leucine or-->tyrosine (Leu-40m or Tyr-40m) was higher than that of the wild type enzyme or of other mutants in which Ser-8, -19, and -31 were replaced by leucine. The kinetic studies carried out with the stably expressed TH show that the Km for the cofactor 6-methyltetrahydropterine is lower and the Ki for dopamine is higher when the enzymatic hydroxylation is catalyzed by the Leu-40m or Tyr-40m than by the wild type enzyme. The kinetic parameters and the pH profile of the enzymatic hydroxylation catalyzed by the Leu-40m or Tyr-40m are similar to the enzyme activated by PKA-mediated phosphorylation. We suggest that Ser-40 in TH exerts an inhibitory influence on the enzymatic activity, and its replacement with another amino acid by site-directed mutagenesis or its modification by phosphorylation leads to a change in conformation with an increased enzymatic activity. The importance of Ser-40 in the activation of TH by PKA-mediated phosphorylation was investigated by comparing the activation of the wild type enzyme with that of Leu-40m or Tyr-40m. The findings that the enzymatic activity is increased by PKA-mediated phosphorylation of the wild type enzyme, but not of the Leu-40m or Tyr-40m, demonstrate that phosphorylation at Ser-40 is essential for activation of TH by PKA. The findings that addition of ATP plus cAMP to homogenates from transfected AtT-20 cells stimulates the recombinant wild type TH activity indicate that these cells contain endogenous cAMP-dependent protein kinase.

Amino Acid Sequence↗
PubMed1992

Cardiovascular phase relationships to the cortical event-related potential of schizophrenic, depressed, and normal subjects.

Cardiovascular phase, especially diastole, influences attention and the event-related potential (ERP) of the right hemisphere of the brain. Depression and schizophrenia are characterized by attentional deficits, unique lateralization of brain function, and deviant phase relationships of biological oscillators. In the present study, the ERP was recorded during stimulation triggered by diastole and systole in control (n = 16), depressed (n = 16), and schizophrenic (n = 9) subjects. Fifty tones were presented and subjects were instructed to count them silently. Previous findings were supported of delayed latencies and increased amplitude in depressed patients and decreased amplitudes and delayed latencies in schizophrenics. An exaggerated effect of diastole on the ERP in the right hemisphere was observed in depressed patients, however, no cardiovascular effect on the ERP was apparent in schizophrenic patients. Results suggested that heart/brain networks are tightly coupled in normal controls, perhaps "overdriven" in depressed patients, and uncoupled in schizophrenics.

Arousal↗
PubMed1992

Application of capillary isoelectric focusing with universal concentration gradient detector to the analysis of protein samples.

The design of a new capillary isoelectric focusing (cIEF) instrument, composed of a rugged cartridge holding a short piece of capillary and a universal, inexpensive concentration gradient detector, was optimized and applied to the analysis of various protein samples. High-efficiency cIEF separations with sub-femtomole detection limits for absolute amounts were obtained using 10 microns I.D. capillaries with large O.D.-to-I.D. ratios. An electric field strength of 1 kV/cm applied in the focusing step resulted in a 10(-8) M on-column concentration detection limit, which corresponded to 10(2) amol absolute amount of proteins. The detection volume was estimated to be 2 pl, which is among the smallest values reported to date for any optical or spectroscopic detector. When a 6-cm long capillary was used, proteins with isoelectric points ranging from 4.7 to 8.8 could be analyzed in about 5 min, the shortest analysis time ever reported for cIEF. Compared with commercial cIEF instruments with UV-visible absorbance detectors, the instrument is easier to use and has lower detection limits and better resolution. Several protein mixtures and real samples were separated with this instrument.

Antibodies, Monoclonal↗
PubMed1992

Renaturation and partial peptide sequencing of mitogen-activated protein kinase (MAP kinase) activator from rabbit skeletal muscle.

Mitogen-activated protein kinase (MAP kinase) activator was purified 2000-fold from skeletal muscle, and proteins which co-purified with the activator were analysed after SDS/PAGE by renaturation and partial sequencing. Activity for tyrosine and threonine phosphorylation of MAP kinase was present in two bands of approx. 48 and 46 kDa, which have sequence similarity to small GTP-binding protein p25 GDP dissociation inhibitor and protein kinases (PBS2, SPK1+, STE7, BYR1) respectively.

Amino Acid Sequence↗
PubMed1992

Ordered phosphorylation of p42mapk by MAP kinase kinase.

Preparation of milligram amounts of [32P]p42mapk, phosphorylated at Tyr185 or diphosphorylated at Tyr185/Thr183, for use as specific protein phosphatase substrates is described. Tyr- but not Thr-phosphorylated p42mapk, accumulates when ATP is limiting. Furthermore, Tyr185-phosphorylated p42mapk exhibits an apparent 10-fold decrease in apparent Km (46.6 +/- 6.6 nM) for MAP kinase kinase compared to that for the dephospho form (approximately 476 nM). We conclude that Tyr185 precedes Thr183 phosphorylation, and that this is prerequisite, dramatically increasing the affinity of p42mapk for MAP kinase kinase.

Animals↗