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Biomedical subjects

M Schwartz

Publications and source records attributed to M Schwartz.

At least 793 records · Page 44Linked to original sources
PubMed1977

Prevalence of vitiligo. Epidemiological survey on the Isle of Bornholm, Denmark.

The prevalence of vitiligo was 0.38% in 47,033 people in a representative region in Denmark. Both sexes were equally affected. No significant difference was found in the distribution of 179 patients with vitiligo among five municipalities or between urban and rural districts. The age-specific prevalence increased from 0.09% under the age of 10 years to 0.90% in the age group 60 to 69 years. After the age of 70, the prevalence declined. This fall might reflect an increased incidence of vitiligo during the past few decades. The number of new cases of vitiligo increased steadily with advancing age, its onset being most often between the ages of 40 and 60 years. It is assumed that the prevalence of vitiligo in Denmark applies also to the northwestern part of Europe.

Adolescent↗
PubMed1977

Use of gene fusions to study outer membrane protein localization in Escherichia coli.

Escherichia coli strains have been isolated that produce hybrid proteins comprised of an NH2-terminal sequence from the lamB gene product (an outer membrane protein) and a major portion of the COOH-terminal sequence of beta-galactosidase (beta-D-galactoside galactohydrolase, EC 3.2.1.23; a cytoplasmic protein). These proteins exhibit beta-galactosidase activity. One such strain, pop 3105, produces a hybrid protein containing very little of the lamB gene protein; the protein is found in the cytoplasm. The protein found in a second strain, pop 3186, contains much more of the lamB gene protein; a substantial fraction of the beta-galactosidase activity is found in the outer membrane, probably facing outward. These results indicate that information necessary to direct the lamB gene product to its outer membrane location is located within the lamB gene itself. The properties of such fusion strains open up the prospect of a precise genetic analysis of the genetic components involved in protein transport.

Bacterial Proteins↗
PubMed1977

Distubed neuromuscular transmission in viral infections.

14 subjects with influenza or echovirus infection, all suffering myalgia, and 9 subjects with mumps, in whom this symptom was lacking, were investigated with single fibre electromyography (EMG) in the acute phase and during convalescence to reveal a possible disturbance in neuromuscular transmission. In both groups about the same percentage of the potential pairs studied showed abnormal transmission characteristics in the acute phase. Two weeks after the acute infection, this percentage had decreased significantly in the group with myalgia, whilst in the non-myalgia group it was still at the same level. However, on both occasions of investigation and in both groups the percentages were substantially greater than those recorded in healthy individuals. This study demonstrates that acute febrile infections may adversely affect neuromuscular transmission in previously healthy human subjects. The effects observed might offer an explanation to the accentuated muscular weakness in association with infections in patients with an already low safety margion of neuromuscular transmission, e.g. in myasthenia gravis.

Adolescent↗
PubMed1977

A system of cancer-related urinary glycoproteins: biochemical properties and clinical applications.

UNLABELLED: Gel-filtration and immunodiffusion reveal most patients with disseminated cancer excrete 100 to 1000 mg/day of urine proteins, mol wt 10,000-60,000, which are distinct from known plasma proteins and cancer-related antigens. By gel-filtration and ion-exchange chromatography, 5 novel urinary glycoproteins have been isolated which are responsible for about 1/2 the mass of the "low molecular weight proteinuria" of patients with advanced cancer: BJC1 and BJC2 (patient B.J., chronic myelocytic leukemia); JBB5 (J.B., metastatic pancreatic carcinoma); EDC1 (E.D., acute myelocytic leukemia); HNC1beta (H.N., acute monocytic leukemia). Mol wts respectively are 29,000, 22,000, 55,000, 27,000 and 33,000, and carbohydrate contents respectively 61%, 23%, 23%, 27% and 40%. Attention to date has focussed on EDC1 and HNC1beta, because their urinary excretion directly reflects the course of the neoplastic disease. EDC1 and HNC1beta possess the same protein but different carbohydrate moieties. They are antigenically related to inter-alpha trypsin inhibitor, mol wt 160,000, which is one of the 6 antiproteolytic proteins in normal human plasma. EDC1 and HNC1beta both possess antitryptic activity. Specific radioimmunoassays (RIA) to these 2 glycoproteins were developed. Normal individuals (n = 210) excreted 0.3 +/- .02 (ave. +/- SE) mg EDC1 per g creatinine. In 18 non-neoplastic diseases (n = 75), urinary EDC1 was .5 +/- .06 mg/g creatinine. In disseminated cancer of 7 types (n = 81) (breast, ovary, colon, squamous of head-neck and lung; melanoma; acute myelocytic leukemia), ave. EDC1 excretion ranged from 10 to 190 mg/g creatinine. A significant increase (P less than .05) was found in the localized stage of squamous cancer of head-neck-lung, but only after regional or distant spread in the other types. Similar results were found with HNC1beta, urinary excretion of which averaged 1/10 that of EDC1. Effective chemotherapy in 5 patients with leukemia or solid tumors caused prompt disappearance of urinary EDC1; the glyco-protein reappeared in the urine several weeks before clinical relapse. CONCLUSIONS: (i) EDC1- and HNC1beta-proteinuria is a useful indicator of some types of localized and most types of disseminated cancer; (ii) the degree of this proteinuria reflects the effectiveness of chemotherapy; (iii) the antiproteolytic property of EDC1 and HNC1beta suggests a relation between proteolysis and tumorigenesis.

Carcinoma↗
PubMed1976

Maltose transport in Escherichia coli K12. A comparison of transport kinetics in wild-type and lambda-resistant mutants as measured by fluorescence quenching.

The kinetic parameters for the maltose transport system in Escherichia coli K12 were determined with maltose and maltotriose as substrates. The system exhibits an apparent Km of 1 muM for maltose and 2 muM for maltotriose. The V of entry was determined as 2.0 and 1.1 nmol substrate/min per 10(8) cells. Mutations in lamB, the structural gene for the receptor protein of phage lambda, increased the Km for maltose transport by a factor of 100-500 without influencing the maximal rate of transport. Maltotriose is no longer transported in these lamB mutants. The maltose-binding protein, an essential component of the maltose transport system, was found to exhibit substrate-dependent fluorescence quenching. This phenomenon was used to determine dissociation constants and to estimate the rate of ligand dissociation. A Kd of 1 muM for maltose and of 0.16 muM for maltotroise was found. From the comparison of the kinetic parameters of transport of maltose and maltotriose in wild-type and lambda-resistant mutants with the binding constants for both sugars to purified maltose-binding protein, we conclude that the lambda receptor facilitates the diffusion of maltose and maltodextrins through the outer membrane.

Bacterial Proteins↗
PubMed1976

Reconstitution of genetically regulated responses against random and ordered synthetic polypeptides by methylated bovine serum albumin as analyzed by isoelectric focusing.

In previous publications it was shown by avidity measurements, cross-reactivity patterns and genetic analyses, that the tetrapeptide T-T-G-G is the immuno-dominant epitope of the synthetic polypeptide (T, G)-A--L. In the present study this close immunological relationship between the random multichain copolymer (T, G)-A--L and the ordered analogue (T-T-G-G)-A--L is extended by two additional criteria. First, the immune response against (T-T-G-G)-A--L in H-2k nonresponder mouse strains can be reconstituted to high antibody levels by complexing this antigen to methylated bovine serum albumin, as was tested earlier for (T,G)-A--L. The antibodies elicited upon reconstitution in both antigenic systems are directed mainly against the same determinant, T-T-G-G. Second, isoelectric focusing analysis of specific antisera developed with radiolabeled antigen revealed restricted 7 S IgG antibody populations in high responder and reconstituted high and low responder mice. The spectra were found to be of similar complexity in the (T,G)-A--L and in the (T-T-G-G)-A--L system. From these data it was concluded that the repertoires of specific B cells to T-T-G-G are very similar in high and low responder strains, and the defect in the H-2k low responder systems should be located at the level of T-B cell cooperation.

Alanine↗
PubMed1976

Role of antigenic structure in cell to cell cooperation.

Two synthetic polypeptides which differ only in the order of amino acids in their NH2-terminal side chains, namely, (Tyr-Tyr-Glu-Glu)-poly(DLAla)- -poly(LLys) and (Tyr-Glu-Try-Glu)-poly(DLAla)- -poly(LLys), were found to be under different genetic control. By three different in vivo systems for thymus-derived cell depletion, it was demonstrated that (Tyr-Tyr-Glu-Glu)-poly(DLAla)- -poly(LLys), which represents the random poly(Tyr,Glu)-poly(DLAla)- -poly(Lys) in the pattern of immune responses and in the quality of antibodies they elicit, is thymus-dependent whereas (Tyr-Glu-Tyr-Glu)-poly(DLAla)-poly(LLys) does not require thymus-derived cell help for efficient antibody production. Therefore, the two ordered polypeptides which are similar chemically differ in parameters, not yet determined, which affect their capability to trigger bone marrow-derived cells.

Amino Acid Sequence↗
PubMed1976

Determinants of antigenic molecules responsible for genetically controlled regulation of immune responses.

The ability of mice bearing the H-2S haplotype to develop helper responses to the random copolymer of Glu,Ala while they developed suppressor responses to the terpolymer of Glu,Ala,Tyr suggested the crucial role of tyrosine in these peptides. On the basis of various considerations, it was postulated that many of the tyrosine residues in Glu,Ala,Tyr would be localized at the NH2-terminal end of the molecule. To verify this hypothesis, a block terpolymer composed of a short sequence of homopolymer tyrosine covalently bound to the random copolymer of Glu,Ala was synthesized. The present studies, using this block terpolymer, demonstrated that the chemical determinants stimulating helper and suppressor responses are distinct and can be present simultaneously in the same molecule. Thus, addition of COOH-terminal tyrosine residues to the Glu,Ala polypeptide converted this immunogenic molecule to an immunosuppressive molecule in mice bearing the H-2S haplotype. The mechanism by which these short sequences of tyrosine influence H-2-linked immune responses remains to be determined.

Alanine↗