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Biomedical subjects

J L Fu

Publications and source records attributed to J L Fu.

29 records · Page 2Linked to original sources
PubMed1984

Antigenic difference between viral strains causing classical and mild types of epidemic hemorrhagic fever with renal syndrome in China.

The antigenic relationship between viral isolates from Apodemus and Rattus that appear to cause the classical and mild types of epidemic hemorrhagic fever (EHF) in China was studied by cross-immunofluorescence, cross-neutralization, immunofluorescence blocking tests, and cross-enzyme-linked immunosorbent assay (ELISA). Obvious antigenic diversity between the isolates was demonstrated by cross-neutralization, immunofluorescence blocking tests, and cross-ELISA. Antisera from patients with classical EHF neutralized viruses of both types to a similar degree, but antisera from patients with mild EHF showed little neutralization of apodemus virus. Similarly, antisera from classical EHF blocked immunofluorescence by monoclonal antibody (25-1 McAb) derived from apodemus virus to both viral antigens, but antisera from mild EHF gave only low-grade blocking against apodemus viral antigen. Direct antigenic titrations of both viral strains by cross-ELISA yielded similar results. That distinct antigenic differences exist between viral strains causing these two types of EHF might be of great importance to the serological differentiation of the viruses and the study of EHF vaccine.

Animals↗
PubMed1977

Allosteric interactions between the membrane-bound acetylcholine receptor and chemical mediators: equilibrium measurements.

An approach to equilibrium dialysis measurements has been developed which enables one to study the interaction of chemical mediators with the membrane-bound acetylcholine receptor and to gain information of a type previously obtainable only with soluble proteins. Equilibrium dialysis experiments conducted at pH 7.0,4 degrees C, and mu = 0.18 M, with electroplax membrane preparations from Electrophorus electricus revealed apparently homogeneous binding isotherms for decamethonium with dissociation constants in the range of 0.2-0.4 muM. The following new information has been obtained. (1) The activators of neural transmission, decamethonium and carbamylcholine, occupy overlapping binding sites. (2) These activators and the inhibitors, alpha-bungarotoxin and d-tubocurarine, compete for only one-half of the sites available to them even through the stoichiometry of these is 1:1 as measured with decamethonium (a reversibly binding activator) and alpha-bungarotoxin (an irreversible specific inhibitor). Different receptor molecules, preexisting nonequivalent binding sites, or an allosteric mechanism involving ligand-induced conformational changes are often considered to account for such observations.

Acetylcholine↗
PubMed1977

Allosteric interactions between the membrane-bound acetylcholine receptor and chemical mediators. Kinetic studies.

The kinetics of the specific irreversible reaction of a snake neurotoxin, alpha-bungarotoxin, with the acetylcholine receptor of electroplax membrane preparations have been investigated. The effects of activators (decamethonium, carbamylcholine) and inhibitors (alpha-bungarotoxin, d-tubocurarine) of neural transmission on this reaction have been measured and the following new information obtained. (1) The irreversible reaction is preceded by the reversible formation of toxin-receptor complexes. (2) Two types of receptor binding site exist. d-Tubocurarine directly competes with the toxin for one type of binding site. Decamethonium and carbamylcholine are noncompetitive inhibitors of the toxin reaction. (3) The data are inconsistent with binding sites on separate and distinct molecules or with preexisting nonequivalent binding sites. A simple model is proposed to explain both the kinetic data and equilibrium measurements which indicated that activators and inhibitors of neural transmission compete for only one-half of the receptor sites available to them. The model proposes that for the compounds investigated the binding sites of activators do not overlap with those of inhibitors and the ligand-induced conformational changes of the receptor result in changes in the affinities of the binding sites. The model is simple and is based on mechanisms which have been found to be valid for many well-characterized regulatory enzymes.

Acetylcholine↗
PubMedDate not supplied

Eczema herpeticum in children with atopic dermatitis.

Eczema herpeticum (EH), a form of disseminated cutaneous herpes simplex virus (HSV) infection, is a potentially life-threatening disease. It usually occurs in individuals with atopic dermatitis (AD) or other preexisting dermatosis. The resulting disruption of the skin barrier decreases the ability of such individuals to localize an HSV infection. We report eight AD cases with eczema herpeticum, seen from February 1989 to January 1996. Their ages ranged from 5 months to 6 years (mean age 2.5 years), There were 5 boys and 3 girls. Their laboratory data showed: IgE: 39 to 474, mean 197 IU/ml; eosinophil count 139 to 560, mean 314/mm3; Tzanck smear positive in 6 out of 6 patients; vesicle fluid culture positive for Herpes simplex type I in 4 out of 4 patients. All patients were treated with acyclovir and recovered.

Child↗
PubMedDate not supplied

X-linked agammaglobulinemia presenting as juvenile chronic arthritis: report of one case.

Bruton agammaglobulinemia (X-linked agammaglobulinemia, XLA), transmitted by X-linked recessive inheritance, affects only males. Twenty percent of patients with XLA may have arthritis. Septic arthritis may occur, but there is also a form of arthritis that is similar to rheumatoid arthritis or juvenile chronic arthritis. Here we report one case of XLA in a boy with non-erosive chronic right knee arthritis. There was no evidence of septic arthritis. Regular intravenous gammaglobulin replacement therapy and oral naproxen resulted in dramatic improvement in the arthritis. This case illustrates that XLA should be considered as a possible underlying cause of juvenile chronic arthritis in males.

Agammaglobulinemia↗
PubMedDate not supplied

Whey and casein specific IgE and the cow's milk challenge test for atopic children.

We studied 30 atopic children who suspected of milk allergy by past history (age ranging from 1 yr 4 mo to 9 yr 6 mo, mean age: 5.03 yr.) diagnosed as having asthma, atopic dermatitis and/or allergic rhinitis. These 30 atopic children had been screened from the patients at our outpatient clinic by the Pharmacia CAP system RAST FEIA. All of them showed the presence of at least Class II (greater than 0.7 ku/l) IgE specific to proteins in cow's milk. Further analysis found IgE specific to alpha-lactoalbumin (alpha-LA) elevated in 1 patient (3.3%), 1 patient (3.3%) to beta-lactoglobulin (beta-LG), 4 patients (13.3%) to alpha-LA and beta-LG, 5 patients (16.7%) to casein, 8 patients (26.7%) to casein and alpha-LA, 11 patients (36.7%) to casein, alpha-LA and beta-LG. After 3 weeks' cow-milk-free diet, the patient's milk challenge test was performed at our outpatient clinic. According to the test result, none of these 30 atopic children showed clinical evidence of significant allergic reaction to cow's milk in the skin, the gastrointestinal tract or the respiratory tract either within two hours after the challenge test or within 3 days after they went home. We therefore conclude that: (1) No single major allergen is apparent in cow's milk: casein, alpha-LA and beta-LG all show a high proportion of positive reaction. (2) Many atopic children fully tolerate cow's milk, although they have high titer of IgE antibodies specific to cow's milk. The RAST test is only the first step to screen patients with suspected IgE-mediated allergies. To make sure, any positive reaction must be confirmed by the "golden standard" for diagnosis, i.e., the double-blind placebo-controlled food challenge.

Animals↗
PubMedDate not supplied

Fish induced anaphylactic reaction: report of one case.

In the past 2 years, a 4 year-old boy has had an anaphylactic reaction whenever he contacted food prepared with fish. The symptoms included intense itching in the throat and eyes, which progressed to generalized urticaria and facial angioedema. This was accompanied by cough, wheezing and dyspnea. Many fish preparations caused these episodes including several different kinds of fish (cod, tuna, salmon, trout, eel...), fish soup, chopsticks contaminated with fish preparations and canned fish. Elevated levels of total serum IgE (224 IU/ml) and specific IgE for cod (93.1 IU/ml), tuna (> 100 IU/ml), salmon (> 100 IU/ml), trout (64.4 IU/ml), mackerel (41.2 IU/ml) and eel (28.1 IU/ml) were found by the Pharmacia CAP system RAST FEIA in our allergy clinic. A skin prick test for mixed fish extracts (contain flounder, cod and halibut) was positive. A fish challenge test for cod, tuna, salmon, trout and eel all showed anaphylactic reactions. His allergic symptoms stabilized gradually after strictly avoiding ingestion of fish and using drug treatment. He also had a similar anaphylactic reaction to frogs. The best treatment for fish allergy is avoidance. Avoidance of fish may need to include both ingestion and inhalation of cooking vapors.

Anaphylaxis↗