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Biomedical subjects

N Strick

Publications and source records attributed to N Strick.

At least 73 records · Page 4Linked to original sources
PubMed1982

Radioimmunoassay of human beta interferon.

A solid phase radioimmunoassay (RIA) for human fibroblast-derived beta (beta) interferon is described using dinitrophenylated (DNP) IgG from rabbit anti-interferon serum and quantitation of the antigen-bound antibodies by subsequently measuring the attachment of 125I-labeled anti-DNP. The sensitivity limit of the assay is 50 u of interferon corresponding to 0.5 ng of interferon protein. Preparations of alpha leukocyte-derived interferon show only marginal cross-reactivity (less than 0.01%) while the mouse interferons (mixture of alpha and beta)are negative in this assay. The simplicity, reproducibility and the possibility of using 125I-labeled anti-DNP as a universal reagent for different anti-interferon sera may widen the development of RIA tests for interferons both in research and clinical areas.

Animals↗
PubMed1981

Antibodies as immunological probes for studying the denaturation of HBsAg.

Radioimmunoassays were developed for antibodies to denaturated forms of HBsAg (reduced and alkylated in an isotonic buffer (RAHBs) or in 8 M urea-HBs) or reduced in 8M urea but not alkylated). These tests revealed that intact HBsAg and RA-HBs shared common antigenic determinants, termed Re[Imai et al, 1974]. Anti-Re is elicited in the course of immune response to intact HBsAg in humans and experimental animals. Denaturation in 8 M urea and alkylation causes the appearance of additional antigenic determinants, the specificity of which is affected by the reagent used for alkylation. Reduction in 8 M urea followed by treatment with iodoacetate reveals antigenic sites common for HBsAg and some human serum proteins. Antibodies specific for the Le Bouvier determinants of HBsAg are probably not the appropriate probe for detection of primary translational products of the hepatitis B virus genome.

Alkylation↗
PubMed1981

Localization of a hepatitis B surface antigen determinant deduced from results of chemical modifications.

The effect on hepatitis B surface antigen (HBsAg) of reagents considered specific for each of the amino acid residues, lysine, methionine, cysteine, arginine, tyrosine, tryptophan, and glutamic (aspartic) acid, was studied. Based on the observed alterations of HBsAg antigenicity and the known amino acid sequence of the HBsAg polypeptide, a major antigenic determinant was localized within the sequence: Pro-Ser-Cys-Cys-Cys-Thr-Lys-Pro-Thr(Ser)-Asp-Gly-Asn-Cys-Thr-Cys-Ile-Pro-Ile-Pr o-Ser-Ser, corresponding to residues 135-155. The asparagine-linked saccharide chains are not essential for HBsAg antigenicity.

Amino Acid Sequence↗
PubMed1981

Enzyme-linked fluorescence immunoassays using beta-galactosidase and antibodies covalently bound to polystyrene plates.

A solid-phase enzyme-linked immunoassay using a fluorogenic substrate (4-methylumbelliferyl-beta-D-galactopyranoside) was developed. Antibodies were covalently linked to glutaraldehyde-activated 96-well aminopolystyrene plates. Antigens from test samples were adsorbed to the solid phase and detected using antibodies conjugated with E. coli beta-galactosidase. Glutaraldehyde, N-succinimidyl-3-(2-pyridyldithio)-propionate or N-succinimidyl-6-(4-azido-2-nitrophenylamino)-hexanoate were used as linkers between antibodies and the enzyme. The measurement of fluorescence can be automated for rapid screening of many specimens. The sensitivity limit of the test for HBsAg is about 5-10 pg.

Animals↗
PubMed1981

Prevalence of hepatitis B "e" antigen and its antibody in various HBsAg carrier populations.

A total of 749 persistent carriers of hepatitis B surface antigen (HBsAg) were tested for hepatitis B e antigen/antibody to e antigen (HBeAg/anti-HBe) by a radioimmunoassay method. The prevalence of HBeAg was found to be: 9.1% in carrier-blood donors, 10.3% in mentally retarded patients without Down's syndrome, 23.6% in Chinese-Americans, 35.3% in drug addicts, 39.2% in mentally retarded patients with Down's syndrome, 61.4% in homosexual men, and 71.2% in dialysis patients. The prevalence of HBeAg appears to be independent of sex, race, and HBsAg antigenic subtype. Younger carries tend to be more frequently HBeAg positive than older ones. All individuals acutely infected with hepatitis B virus become at least transiently positive for HBeAg. Appearance or clearance of HBsAg, HBeAg and their corresponding antibodies seem to be interrelated.

Adult↗
PubMed1980

Confirmatory evidence for the association of hepatitis B surface antigen with antigenic determinants reactive with antibodies present in some anti-HBe-positive sera.

Spherical 20 nm diam. particles of hepatitis B surface antigen (HBsAg), purified from some sera positive for hepatitis B e-antigen (HBeAg), are associated with antigenic determinants reacting with antibodies frequently present in sera containing anti-HBe. Treatment of HBsAg with the detergent Sarcosyl increased the exposure of these determinants which could be differentiated from HBeAg on the basis of immunological specificity and sensitivity to reduction and alkylation. The presence of these determinants appeared to be restricted to a subpopulation of HBsAg associated with IgG and albumin.

Antibodies, Viral↗
PubMed1980

An antigen detected frequently in human sera with elevated levels of alanine aminotransferase: a potential marker for non-A, non-B hepatitis.

In a search for additional antigens associated with virus-induced human liver disease a radioimmunoassay (RIA) was developed using IgG from sera of a multiply transfused person. Polystyrene beads coated with IgG F(ab)'2 fragments, dinitrophenylated F(ab)'2 fragments and 125I-labelled anti-2,4-dinitrophenyl antibodies (Neurath & Strick, 1979) were used in the RIA. An apparently new antigen or the corresponding antibodies were detected in 155 serum specimens from 35/37 (94%)individuals who developed non-A, non-B hepatitis. The antigen was also present in hepatitis B surface antigen-negative sera of blood donors with normal (13.2%) and elevated levels of alanine aminotransferase (34%). The antigen has an approximate mol. wt. of 45,000, a buoyant density of 1.23 g/ml and an isoelectric point of 7.

Alanine Transaminase↗
PubMed1979

Radioimmunoassay of hepatitis B e-antigen (HBeAg): identification of HBeAg not associated with immunoglobulins.

A radioimmunoassay for hepatitis B e-antigen (HBeAg) is described. Polystyrene beads coated with IgG prepared from a human serum containing antibodies to HBeAg (anti-HBe) and anti-HBe IgG labelled with 125I-p-hydroxyphenylpropionic acid N-hydroxysuccinimide ester were used in the test. The radioimmunoassay was approximately 1,000-fold more sensitive than immunodiffusion. At least a transient presence of HBeAg in serum appears to be a common feature of infections by hepatitis B virus. The radioimmunoassay was instrumental in establishing conditions for identification of apparently free monomeric HBeAg. The HBeAg has an approximate mol. wt.of 35,000 and was recovered after isoelectric focusing in fractions with a pH between 4.25 and 4.8. Polyacrylamide gel electrophoresis revealed the presence in HBeAg of a polypeptide with an apparent mol. wt. of 17,000.

Hepatitis B Antigens↗
PubMed1979

Association of hepatitis B e-antigen (HBeAg) determinants with the core of Dane particles.

Immunoprecipitates obtained by reacting Dane particle cores with human antibodies to hepatitis B core antigen (HBcAg) were chromatographed on columns of Sepharose 4B CL using 3 M-NaSCN as eluant. An antigen having the size and immunological specificity of monomeric e-antigen (HBeAg) was separated from HBcAg by this method. Antisera from animals immunized with HBcAg or HBeAg reacted not only with the antigen used for immunization but also with HBeAg and HBcAg, respectively. This indicates that HBeAg determinants are associated with the core of Dane particles.

Animals↗
PubMed1979

Radioimmunoassay for albumin-binding sites associated with HBsAg: correlation of results with the presence of e-antigen in serum.

A radioimmunoassay for albumin-binding sites associated with hepatitis B surface antigen (HBsAg) is described. Polystyrene beads coated with glutaraldehyde-polymerized human serum albumin were incubated with diluted specimens of HBsAg-positive sera which contained either e-antigen (HBeAg) or anti-HBe or were negative for both HBeAg and anti-HBe as determined by rheophoresis. The quantity of HBsAg attached to the beads, determined by measuring the amount of 125I-labeled anti-HBs adsorbed during a subsequent incubation step, was related to the presence of HBeAg in the specimens.

Adsorption↗
PubMed1978

Antigenic sites related to human serum proteins in HBsAg: isolation from normal human serum of a high-molecular-weight glycoprotein reacting with antialbumin.

A novel minor constituent was isolated from normal human serum by affinity chromatography on columns of insolubilized concanavalin A and antibodies to albumin, followed by rate zonal centrifugation. This component has the following properties: a sedimentation coefficient of approximately 31; a diameter of 14--22 nm, and a buoyant density of 1.302 gm/cu cm. It contains about 1% neutral sugars and is electrophoretically heterogeneous, since two populations of particles with isoelectric points of pH 4.95 and 5.75 were separated by isoelectric focusing. It contains a single major glycopeptide with an apparent molecular weight of 72,000 daltons. Its amino acid composition is distinct from that of albumin. It elicited the formation of antibodies that also reacted with HBsAg.

Antibody Specificity↗
PubMed1978

Radioimmunoassay and some properties of human antibodies to hepatitis B core antigen.

A solid-phase radioimmunoassay for antibodies to hepatitis B core antigen (anti-HBc) is described. Polystyrene beads coated with anti-HBc, hepatitis B core antigen prepared from pooled sera of humans infected with hepatitis B virus (HBV) and 125I-labelled anti-HBc were used for the test. Distinct patterns of development and changes of anti-HBc and their immunologic properties are all related to variations of other markers specific for HBV infections. Knowledge concerning the detailed features of the immune response to hepatitis B core antigen may provide deeper insight into the pathogenesis of HBV infections.

Antibodies, Viral↗
PubMed1978

Some properties of hepatitis B core antigen isolated from serum of infected humans.

The nucleocapsid of Dane particles (= hepatitis B core antigen; HBcAg) was isolated from human sera either positive or negative for e-antigen (HBeAg)--an apparent marker for the level of infectious hepatitis B virus in serum. HBcAg from the HBeAg-positive serum pool consisted of two distinct populations of particles, one with a buoyant density (d) of 1.358 g/ml and a sedimentation coefficient (S20, w) of approximately 110, and another with d = 1.25 to 1.30 g/ml and S20, w approximately 70. Only the latter type of particles was isolated from an HBeAg-negative serum pool. HBcAg was labelled with 125I-p-hydroxyphenylpropionic acid N-hydroxysuccinimide ester, dissociated and analysed by polyacrylamide gel electrophoresis. One major and one minor polypeptide with apparent mol. wt. of 16000 +/- 500 and 68000, respectively, were detected. Another component have the properties of a glycolipid with a mol. wt. in the order of 10(3) was observed. After isoelectric focusing, HBcAg was recovered in fractions with a pH between 4.0 and 5.8, suggesting heterogeneity in isoelectric points.

Epitopes↗
PubMed1978

Properties of delipidated hepatitis B surface antigen (HBsAg) and preparation of its proteolytic cleavage fragments carrying HBsAg-specific antigenic determinants.

Treatment of hepatitis B surface antigen (HBsAg) with either chloroform-methanol (2:1, v/v) or 50% 1,1',3,3'-tetramethylurea did not affect the morphological integrity of the particles (about 20 nm in diameter), although the major portion of lipids was released as indicated by their increased buoyant density in CsCl (1.27 g/cm3 as compared with 1.20 g/cm3 for intact HBsAg). The antigenicity and polypeptide composition of HBsAg was not altered by delipidation. The carbohydrate chains of HBsAg contain penultimate beta-D-galactosyl residues. HBsAg was cleaved by chymotrypsin into fragments which were smaller than intact HBsAg by two orders of magnitude and which contained both the a and d determinants.

Chymotrypsin↗