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Biomedical subjects

K Wong

Publications and source records attributed to K Wong.

At least 235 records · Page 13Linked to original sources
PubMed1980

Enhanced anti-inflammatory effect and reduced immunogenicity of bovine liver superoxide dismutase by conjugation with homologous albumin.

Bovine liver superoxide dismutase (SOD) can be cross-linked to albumin to form soluble conjugates with up to 70% retention of original enzyme activity. These conjugates have markedly prolonged plasma half-times of enzymatic activity (15 h) compared to native SOD (6 min). The conjugates have potent anti-inflammatory effects in vivo and reduced immunogenicity and antigenicity compared to native SOD. These conjugates provide new possibilities for the study of inflammation and its treatment.

Albumins↗
PubMed1980

The recovery of a random variable from a noisy record with application to the study of fluctuations in synaptic potentials.

Analysis of fluctuations in the amplitude of evoked synaptic potentials can be severely handicapped by the presence of spontaneous synaptic potentials and recording noise. A numerical procedure has been described whereby it is possible to remove some of the masking effects of this noise from the underlying distribution of the fluctuating synaptic potentials. it is not necessary to make an initial assumption about the type of distribution which will best describe the fluctuations. To use this technique, it is necessary to measure the histograms which approximate the probability densities of both the noise, and the noisy evoked potential. It is also necessary to assume that the statistical mechanisms generating the noise are independent of those mechanisms which cause the fluctuation in synaptic transmission, and that the noise and the evoked potentials add linearly. The statistical reliability of the technique depends upon the amount of noise present, and the sample size. Problems of resolution which arise from finite sampling and high noise levels are discussed.

Afferent Pathways↗
PubMed1980

Free radicals and inflammation: superoxide-dependent activation of a neutrophil chemotactic factor in plasma.

The intravenous administration of superoxide dismutase (superoxide:superoxide oxidoreductase, EC 1.15.1.1) to animals with induced inflammation suppresses the inflammatory response and inhibits leukocyte infiltration into the challenged site, suggesting that neutrophil-generated superoxide reacts with an extracellular precursor to generate a substance chemotactic for neutrophils. Plasma exposed to superoxide in vitro becomes potently chemotactic. The appearance of chemotactic activity is inhibited by superoxide dismutase but not by catalase. The chemotactic factor does not stimulate superoxide production or degranulation in neurtrophils. Intradermal injection of superoxide-treated plasma or of a superoxide-generating system causes heavy infiltration of neutrophils to the injection site but does not cause overt signs of inflammation. The chemotactic factor consists of a chloroform-extractable component bound to serum albumin. The superoxide-dependent chemotactic factor appears to play a major role in communication in neutrophil-mediated inflammatory events. Prevention of production of this factor appears to be the major anti-inflammatory action of superoxide dismutase.

Adult↗
PubMed1980

Superoxide and inflammation: a mechanism for the anti-inflammatory activity of superoxide dismutase.

Several models of inflammation induced in laboratory animals were markedly inhibited by intravenous administration of the enzyme superoxide dismutase. In most cases, the enzyme required chemical modification to increase its circulating lifetime. In all cases, histological examination of the sites of the potential lesions revealed that treatment with superoxide dismutase prevented the accumulation of inflammatory cells. Experiments in vitro demonstrated the existence of a plasma factor which reacts with superoxide to become a potent chemotactic factor for neutrophils. The factor apparently serves to call increasing numbers of neutrophils to the inflammatory locus in response to the superoxide produced by the first cells to encounter the stimulus.

Animals↗
PubMed1980

Health outcomes of a community-based therapy program for children with cancer--a shared-management approach.

Critical to providing cancer therapy to children in rural areas is finding dependable sources of therapy near the patients' homes. In this study, comparison was made of 668 visits by 24 patients to nearby private practitioners, who carried out 70% of the therapy, with 712 visits by 22 other patients for whom all care was managed by pediatric hematologist-oncologists. There was no significant difference by Wilcoxon rank sum test between the two groups in the accuracy with which protocol rules were followed, in the incidence of neutropenia, infection, fever, thrombocytopenia, drug toxicity, or the proportion of days hospitalized. The findings indicate that the private practitioners participating in a shared-management system were a dependable resource for providing 70% of the total cancer therapy to these patients.

Antineoplastic Agents↗
PubMed1978

Retropharyngeal abscess after endoscopic retrograde cholangiopancreatography: an uncommon but potentially fatal complication.

Diagnostic cholangiopancreatography is a useful procedure which is attended by a relatively low incidence of immediate or delayed complications. Perforation of the esophagus or gut, myocardial infarction, hemorrhage, cholangitis, and pancreatitis are the most commonly reported morbid or fatal events. This paper reported a case of retropharyngeal abscess which led to tracheal compression requiring an emergency tracheostomy and antibiotic therapy after a routine ERCP procedure. This dramatic case pointed out an unusual but potentially fatal complication of diagnostic ERCP.

Abscess↗
PubMed1978

Proximal tibiofibular synostosis.

The occurrence of a proximal tibiofibular synostosis is indeed a rare condition with only 2 cases unassociated with other diseases reported to our knowledge to date. Two skeletally immature patients presented with a synostosis of the proximal tibiofibular region associated with shortening of the limb in the affected segments. Although the shortening and the synostosis seem interrelated no explanation of their relationship is evident from these 2 cases.

Child↗
PubMed1976

Dopamine receptors in human and calf brains, using [3H]apomorphine and an antipsychotic drug.

In order to develop a better dopamine receptor radioligand, [3H[apomorphine was prepared and tested for dopamine-like binding properties in both calf and human brain tissues. Specific binding of [3H]apomorphine was defined as that binding which occurred in the presence of 1 muM (-)-butaclamol (an inactive neuroleptic) minus that occurring in the presence of 1 muM (+)-butaclamol (active neuroleptic). The specific binding was saturable, the number of sites being double that of specific [3H]dopamine binding, and occurred primarily in dopamine-rich regions of postmortem human brains. The binding had a dissociation constant of 0.9 nM for human caudate (2 nM for calf caudate) and was blocked by dopamine and norepinephrine, but not by isoproterenol or (-)-propranolol, distinguishing it from a beta-adrenergic receptor. Since there was little desorption of [3H]apomorphine, the ligand permits extensive washing during routine assays for dopamine receptors, and facilitates biochemical purification of the receptor.

Affinity Labels↗
PubMed1976

The effect of ribonuclease on the penetration of R17 phage A-protein and RNA.

In an attempt to throw further light on the relationship of R17 phage RNA and A-protein during the early stages of infection, studies were carried out to determine the effect of ribonuclease (ribonuclease I, EC 3.1.4.22) on the ability of these two phage components to penetrate into host bacteria. It was found that the penetration of phage RNA is affected by ribonuclease concentrations as low as 0.1 mug/ml, while the penetration of phage A-protein was unaffected by ribonuclease concentrations as high as 20 mug/ml. In addition, it was found that a significant fraction of the phage RNA is resistant to the ribonuclease effect. This RNase-resistant portion of the phage population increased with increasing phage concentrations, and gave rise to the penetration of intact, 28S RNA molecules that produced the expected number of infectious centers. These findings are discussed in terms of a model for phage RNA injection in which the A-protein functions both as an attachment organelle and a pilot protein that guides the RNA from the capsid to the exterior surface of the F pilus, and thence into the host bacterium.

Coliphages↗
PubMed1975

Brain receptors for antipsychotic drugs and dopamine: direct binding assays.

In order to test the suggestion that antipsychotic drugs act by blocking dopamine receptors in the brain, the direct effects of such neuroleptic drugs were tested on the stereospecific binding of [3H]dopamine and of [3H]haloperidol to rat brain striata and their subfractions. The stereospecific component of binding was defined as that amount of [3h]dopamine or [3H]haloperidol bound in the presence of (-)-butaclamol (an inactive drug) minus that bound in the presence of (+)-butaclamol (a potent neuroleptic drug); 100 nM butaclamol was used for the [3H]haloperidol assay, while 1 muM butaclamol was used for the [3H]dopamine assay. Various antipsychotic drugs inhibited this stereospecific component in both the dopamine and haloperidol assays. These inhibitory potencies correlated with the clinical doses used for controlling schizophrenia.

Animals↗