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Biomedical subjects

J Wu

Publications and source records attributed to J Wu.

At least 1,585 records · Page 88Linked to original sources
PubMed1978

Modified micro-scale enzymatic method for plasma ammonia in newborn and pediatric patients; comparison with a modified cation-exchange procedure.

We modified two "kit" procedures for plasma ammonia to make them suitable for use with newborn and pediatric patients. Available methods either require too large a specimen, are insufficiently sensitive in the normal range, or are too cumbersome. One was an enzymatic (Sigma Chemical Co., St. Louis, Mo. 63178), the other a cation-exchange (Hyland, Costa Mesa, Calif. 92626) method. The modified micro-scale enzymatic method requires 100 microliter of plasma (CV at 38 micronmol/liter, 8%). Reagent costs per patient assay, including controls and standards, are currently $0.53. An assay run can be completed in 30 min. The modified cation-exchange method requires 200 microliter of plasma; the within-run CV is 12% for a concentration of 34.2 micronmol/liter. Reagents currently cost $0.74 per assay and each run requires less than 2 h to complete. The correlation coefficient for the two methods was 0.98.

Ammonia↗
PubMed1977

Morphology and pathogenesis of desquamative interstitial pneumonitis.

Thirty human lung biopsy specimens have been diagnoses as desquamative interstitial pneumonitis. Six cases had intraalveolar lesions, believed to be early, while 20 had advanced disease characterised by intraalveolar cellular clumps, alveolar wall fibrosis, distortion, and loss of pulmonary parenchyma. Electron microscopy, high resolution light microscopy, and cytological examination have shown that the characteristic clumps in the alveolar air spaces are formed predominantly by enlarged and aggregated macrophages. Lymphocytes and eosinophils are also present in the intraalveolar clumps and in alveolar walls. Inflammation and immunological mechanisms are suggested as causes of the cellular clumping. Interstitial pneumonitis, alveolar wall fibrosis, changes in the alveolar epithelium, and loss of lung parenchyma are believed to be secondary events.

Adult↗
PubMed1974

Immunohistochemical localization of glutamate decarboxylase in rat cerebellum.

Glutamate decarboxylase (L-glutamate l-carboxylase; EC 4.1.1.15), the enzyme in brain that forms gamma-aminobutyric acid, was made visible on sections of rat cerebellum by use of rabbit antiserum to purified mouse-brain glutamate decarboxylase. Cerebellar sections obtained from rats that were perfused with 4% paraformaldehyde were treated with antiserum against the enzyme or with serum from unimmunized rabbits, washed, and then incubated with peroxidase-labeled goat antibody against rabbit immunoglobulin. The glutamate decarboxylase was made visible on sections by means of the product formed by the action of peroxidase on 3,3'-diaminobenzidine and H(2)O(2). A weak and diffuse reaction was observed in Purkinje cell bodies, suggesting the occurrence of the enzyme within these cells. In addition, an intense, punctate deposition of reaction product was located around the Purkinje cells and around the neurons of the deep cerebellar nuclei, suggesting the impingement of many nerve terminals containing the enzyme upon these neuronal surfaces. No specific reaction product was observed in sections treated with serum from unimmunized rabbits. The distribution of glutamate decarboxylase observed in our preparations is consistent with a large body of indirect biochemical, physiological, and morphological data dealing with the synaptic role of gamma-aminobutyric acid neurons in the cerebellum.

Animals↗
PubMedDate not supplied

Time-resolved fluorescence resonance energy transfer studies of DNA bending in double-stranded oligonucleotides and in DNA-protein complexes.

Time-resolved Förster resonance energy transfer (trFRET) has been used to obtain interdye distance distributions. These distributions give the most probable distance as well as a parameter, sigma, that characterize the width of the distribution. This latter parameter contains information not only on the flexibility of the dyes tethered to macromolecules, but on the flexibility of the macromolecules. Both the most probable interdye distance as well as sigma provide insight into DNA static bending and DNA flexibility. Time-resolved fluorescence anisotropy and static anisotropy measurements can be combined to provide a measure of the cone angle within which the tethered dyes appear to wobble. When this motion is an order of magnitude faster than the average lifetime that characterizes transfer, an average value of the dipolar orientational parameter kappa2 can be calculated for various mutual dye orientations. The resulting kappa2 distribution is very much narrower than the limiting values of 0 and 4, allowing more precise distances and distance changes to be determined. Static and time-resolved fluorescence data can be combined to constrain the analyses of DNA-protein kinetics to provide thermodynamic parameters for binding and for conformational changes along a reaction coordinate. The parameter sigma can be used to model multiple DNA-protein complexes with varying DNA bend angles in a global fitting of trFRET data. Such a global fitting approach has shown how the range of bends in single base DNA variants, when bound by the TATA binding protein (TBP), can be understood in terms of two limiting forms. Time-resolved FRET, combined with steady-state FRET, can be used to show not only how osmolytes affect the binding of DNA to proteins, but also how DNA bending depends on osmolyte concentration in the DNA-protein complexes.

DNA↗
PubMedDate not supplied

Fast analysis of proteins by isoelectric focusing performed in capillary array detected with concentration gradient imaging system.

Isoelectric focusing of several protein samples is performed simultaneously in an array of 2-4 short capillaries (4-10 cm long). The separated proteins are detected by either an on-line concentration gradient imaging detection system, or a single point concentration gradient detector which requires a mobilization step following the focusing process. The application of the capillary array increases the throughput of the capillary isoelectric focusing (CIEF) technique, and makes the technique comparable in sample throughput to the gel slab isoelectric focusing technique, but with much faster speed of separation and quantitation. The analysis is completed in 2-3 min with the imaging detection system, which is about 100 times faster than the conventional gel slab isoelectric focusing and 10 times faster compared to conventional CIEF. The resolution of the separation is 0.02 pH units or better. All separated proteins in the capillary array are detected by the universal concentration gradient detector, which eliminates the need for sample derivatization. The concentration limit of detection for the inexpensive instrument described in this work is about 30 micrograms/mL and can be reduced by using higher quality components in the system, such as a more stable laser, higher optical quality capillaries and a faster computer A/D board. The sample consumption is 400 nL for the 4 cm long, 100 microns ID square capillary. The isoelectric point (pI) values of the samples can be directly determined without internal pI markers from their positions inside the capillary after focusing when the imaging detection system is used.

Costs and Cost Analysis↗
PubMedDate not supplied

Distinct involvement of NF-kappaB and p38 mitogen-activated protein kinase pathways in serum deprivation-mediated stimulation of inducible nitric oxide synthase and its inhibition by 4-hydroxynonenal.

Cytokine-induced expression of inducible nitric oxide synthase (iNOS) and concomitant production of nitric oxide (NO) involve activation of mitogen-activated protein (MAP) kinases and are in most cases mediated by the transcription factor NF-kappaB. We investigated the role of p38 MAP kinase activation and IkappaB phosphorylation in iNOS expression in a novel iNOS-inducing model in mouse macrophages. Deprivation of serum from the culture medium of RAW 264.7 cells up-regulated iNOS and NO production, which were inhibited by 4-hydroxy-2-nonenal (HNE), a component of oxidatively modified low-density lipoprotein (oxLDL). Serum withdrawal induced phosphorylation of Akt, IkappaB, and p38 MAP kinase. Pretreatment with the potent PI3 kinase inhibitor wortmannin, the NF-kappaB inhibitor PDTC or the specific p38 MAP kinase inhibitor SB203580 each partially attenuated the induction of iNOS and NO production, demonstrating that both p38 activation and IkappaB phosphorylation are required for iNOS expression. SB203580, however, did not prevent the phosphorylation of Akt and IkappaB, suggesting that the p38 MAP kinase signal contributes to iNOS gene expression through an IkappaB-phosphorylation-independent pathway. HNE, which markedly inhibited iNOS expression and NO production, prevented the serum withdrawal-triggered IkappaB phosphorylation but not that of Akt or p38 MAP kinase. A high concentration of HNE stimulated dephosphorylation of IkappaB but promoted activation of p38 MAP kinase. Taken together, these results suggest that NF-kappaB and p38 MAP kinase lie in separate signal pathways for serum deprivation-stimulated iNOS expression and NO production. HNE selectively suppresses the former pathway, targeting a site downstream of Akt.

Aldehydes↗
PubMedDate not supplied

Radioimmunoguided surgery in gastric cancer using 131-I labeled monoclonal antibody 3H11.

A clinical trial of radioimmunoguided surgery (RIGS) using 131-I labeled monoclonal antibody (MAb) 3H11 was performed on 25 cases with gastric cancer in this study. The results showed that the route of the administration of radiolabeled MAb is the key point of successful RIGS for gastric cancer. The RIGS in 19 cases in the group of submucosal injection via endoscope was very satisfying. For the detection of metastatic lymph nodes, the sensitivity rate of RIGS was 99.2% (118/119), the specificity, 97.7% (43/44), and the accuracy 98.8% (161/163). The accuracy rate in detecting tumor infiltration of the gastric wall was 95.9% (94/98), the sensitivity 94.6% (35/37), and the specificity 96.7% (59/61). Thus, the use of RIGS may improve the radical resectability rate and possibly the overall survival rate in patients with gastric cancer.

Adult↗
PubMedDate not supplied

Identification of inosine as an endogenous modulator for the benzodiazepine binding site of the GABAA receptors.

Previously we have reported the presence of endogenous ligands that are involved in the regulation of the binding of muscimol to the GABA binding site of the GABAA receptors. Here, we report the presence of multiple forms of endogenous ligands in the brain which modulate the binding of flunitrazepam (FNZP) to the benzodiazepine (BZ) binding site of the GABAA receptor. Furthermore, one of the endogenous ligands for the BZ receptors, referred to as EBZ, has been identified as inosine based on the following observations: (1) standard inosine and the EBZ have identical NMR and UV spectra; (2) the elution profile of inosine and the EBZ from a HPLC column are indistinguishable, and (3) inosine and the EBZ show identical activity in inhibiting [3H]FNZP binding.

Animals↗
PubMedDate not supplied

The effect of anxiety and hostility in silent mentation on localized cerebral glucose metabolism.

Ten normal, wakeful, young (average age, 25.3 +/- 6.6 years) male subjects received positron emission tomographic (PET) scans 45 to 120 minutes after an infusion of D-[18 F]deoxyglucose in order to assess localized cerebral glucose metabolic rates during silent visual and other sensory imagery and cognitive mentation. The typescripts of the verbal reports, limited to 5 minutes, of this type of mentation (including free-associations to all the silent mental events), were blindly content-analyzed to provide objective measures of various kinds of anxiety and hostility. Many significant positive and negative correlations were found in medial cortical, lateral cortical, and subcortical gray matter, and white matter areas between the magnitude of the anxiety and hostility aroused in the silent mental processes and localized cerebral glucose metabolic rates. Clearly, energy consumption in the brain, as judged from localized glucose metabolic rates, is highly influenced by the quality and quantity of emotionally tinged private reveries and mental events occurring spontaneously within human subjects. Brain areas involved with the processing of language, sensation, cognition, memory, and emotional reactions appear to be involved especially in these significant correlations. The implications of such findings in the neurosciences and behavioral sciences are discussed.

Adult↗
PubMedDate not supplied

The effect of head-down tilt on brain potentials related to visual attention.

To study the possible effect of simulated weightlessness on brain function state, the brain event-related potentials (ERPs) in a simple visual selective response task were compared between HDT and HUT in 9 normal subjects. The results were: The Target(T) and non-Target(NT) flash signals both induced significant slow positive potentials which were supposed to related to the attention state; the amplitude of the positive potentials in frontal regions decreased significantly especially for NT-ERPs during HDT compared with that during HUT. The data reported provide new evidence indicating that more attention should be paid on the brain function study during space flight.

Adult↗
PubMedDate not supplied

Frontal cortex and basal ganglia metabolic rates assessed by positron emission tomography with [18F]2-deoxyglucose in affective illness.

Twenty affective disorder patients (16 bipolar and 4 unipolar) and 24 normal controls received scans with positron emission tomography (PET) using [18F]2-deoxyglucose (FDG) as a tracer. Subjects received a series of brief electrical stimuli to their right arms during FDG uptake. Patients with bipolar affective illness had significantly lower frontal to occipital glucose metabolic rate ratios (relative hypofrontality) and significantly lower metabolic rates in their basal ganglia in comparison to whole slice metabolism than normal controls. Patients with unipolar illness showed significantly higher frontal to occipital ratios, and also showed relatively decreased metabolism in the basal ganglia. All results in unipolar patients should be considered exploratory due to the small number of patients. Clinical depression ratings correlated negatively with whole slice metabolic rate.

Adult↗
PubMedDate not supplied

Effect of attention on frontal distribution of delta activity and cerebral metabolic rate in schizophrenia.

15 patients with schizophrenia and nine normal volunteers had 32 channel topographic EEG recorded for spectral analysis during the uptake of 18-F-deoxyglucose (FDG) for positron emission tomography (PET). Both patients and controls performed the Continuous Performance Test, a visual vigilance task, during FDG uptake. EEG was also obtained during an initial pre-FDG resting period. Each EEG epoch was individually inspected for eye movement artifacts. Analysis confirmed increased delta activity in the frontal region of patients with schizophrenia in comparison to normal controls, and a significant correlation between increased frontal delta and relative reduction in frontal lobe metabolism among patients with schizophrenia. This finding of increased delta is consistent with PET, blood flow and topographic EEG studies of schizophrenia, suggesting reduced frontal activity.

Adult↗
PubMedDate not supplied

The role of FlbD in regulation of flagellar gene transcription in Caulobacter crescentus.

The flagellar (fla) genes in Caulobacter crescentus are organized into a regulatory hierarchy of four levels (I-IV) in which transcription of the class III and class IV genes late in the cell cycle from sigma 54-dependent promoters depends on expression of the class II genes above them. The periodicity of fla gene expression has been attributed to sequential activation and repression by specific transcription factors. We have been particularly interested in understanding the function and regulation of one such transcription factor, FlbD. FlbD belongs to the NtrC family of bacterial response regulators that catalyse the initiation of transcription by sigma 54 RNA polymerase (E sigma 54) and its function is required for transcription of the class III and IV fla genes. Here we show that purified FlbD binds to ftr elements that are required for transcription from the sigma 54-dependent class III flbG promoter (ftr1) and repression of transcription from the class II fliF promoter (ftr4). Dimethylsulphate footprinting assays demonstrated that FlbD makes base-specific contacts at highly conserved guanine nucleotides in each half site of the ftr sequences. In a reconstituted in vitro transcription system using E. coli E sigma 54, we found that FlbD was clearly capable of driving transcriptional initiation from the flbG promoter and that this activity relied on the ftr1 binding site. Several observations suggest that phosphorylation plays a role in the regulation of FlbD activity. First, we found that a mutant form of FlbD (FlbDS140F) corresponding to the substitution found in a constitutively active NtrC protein (NtrCS160F), displayed a greater potential for activating E sigma 54-dependent transcription that the wildtype protein. We also observed that high energy-phosphate-containing molecules stimulate transcription activation by the wild type FlbD. Together, these results suggest that FlbD is responsible for mediating fla gene transcription initiation by E sigma 54 and that covalent modification is likely to play a role in governing FlbD activity during the cell cycle.

Bacterial Proteins↗