Biomedical subjects

D Jungkind

Publications and source records attributed to D Jungkind.

23 records · Page 2Linked to original sources

PubMed1975

Evidence for the synthesis of soluble peptidoglycan fragments by protoplasts of Streptococcus faecalis.

Growing protoplasts of Streptococcus faecalis 9790 were found to synthesize and excrete soluble peptidoglycan fragments. The presence of soluble peptidoglycan derivatives in culture supernatants was determined by (i) incorporation of three different radioactively labeled precursors (L-lysine, D-alanine, and acetate) into products which, after hen egg-white lysozyme hydrolysis, had the same KD values on gel filtration as muramidase hydrolysis products of isolated walls; (ii) inhibition of net synthesis of these products by cycloserine and vancomycin; and (iii) identification of disaccharide-peptide monomer using the beta-elimination reaction, gel filtration, and high-voltage paper electrophoresis. Under the conditions of these experiments the presence of newly synthesized, acid-precipitable (macromolecular) peptidoglycan was not detected. The predominance of monomer (70 to 80%) in lysozyme digests of peptidoglycan synthesized by protoplasts was in sharp contrast to digest of walls from intact streptococci which contain mostly peptide cross-linked products. Biosynthesis and release of relatively uncross-linked, soluble peptidoglycan fragments by protoplasts was related to the absence of suitable, preexisting acceptor wall.

Acetates↗

PubMed1969

Characterization of ribosomes from the myxomycete Physarum rigidum grown in pure culture.

The plasmodial phase of the myxomycete Physarum rigidum, analyzed during the period of rapid growth, attained a ribonucleic acid (RNA) and protein content of 9.8 and 60.0%, respectively, on a dry weight basis. It possessed ribosomes of the 80S class which, especially in the absence of magnesium ions, partially dissociated to 60S and 40S subunit classes. Electron micrographs of ribosomes treated with uranyl acetate-lead citrate revealed a number of surface features. Nucleotide analyses of both ribosomal and total RNA disclosed that they were composed of 51.0 and 52.5% guanylic and cytidylic acids, respectively. Consistent with most reports on other organisms, guanylic acid was the most abundant nucleotide found in the various types of RNA and cytidylic acid was the least abundant. The S(0) (20,w) values of the total RNA classes, in 0.01 sodium acetate (pH 4.6) containing 0.10 m NaCl, were 5.2, 18.1, and 27.3 in S units. Changing the ionic environment of the RNA (0.017 molal potassium phosphate, pH 7.0, containing 0.01 m disodium ethylenediaminetetraacetate) resulted in a reduction of the S(0) (20,w) values to 4.2, 16.6, and 22.6 in S units, which is indicative of molecular conformational transitions. In general, the amino acid composition of the ribosomal proteins was similar to the data available on ribosomal proteins from other biological sources.

Amino Acids↗

PubMedDate not supplied

Confirmation of the Syva MicroTrak enzyme immunoassay for chlamydia trachomatis by Syva Direct Fluorescent Antibody Test.

BACKGROUND AND OBJECTIVES: The Syva Micro Trak enzyme immunoassay (EIA) is used widely for screening women infected with Chlamydia trachomatis. Confirmatory tests used in conjunction with EIA screening have shown that false-positive results are common. GOALS: To evaluate the specificity of the Syva MicroTrak EIA by confirmation of positive specimens with the Syva Direct Fluorescent Specimen Test. STUDY DESIGN: Of 6,039 endocervical specimens collected from women attending Colorado family planning clinics, 328 positive EIA results (5.4%) were obtained by Syva MicroTrak EIA. A random subset of 136 positive specimens was tested by Syva Direct Specimen Test. Twenty of 136 specimens (14.7%) negative by Syva Direct Specimen testing were also tested by Syva blocking antibody tests (9 of 20 positive, 45%) and Roche Amplicor polymerase chain reaction (PCR; 6 of 20 positive, 30%). Of 20 specimens positive by Syva MicroTrak EIA and negative by Syva Direct Specimen Test, 11 (55%) were also negative by blocking antibody and PCR, including three specimens with initial EIA sample-to-cutoff ratios greater than 2. CONCLUSIONS: Confirmatory testing of Syva MicroTrak EIA positive specimens with Syva Direct Specimen Test showed that 14.7% were false positive. Coupling the Syva Direct Specimen test with either blocking antibody or PCR reduces the rate of false-positive results to 8%.

Chlamydia Infections↗

PubMedDate not supplied

A phage-linked immunoabsorbant system for the detection of pathologically relevant antigens.

This report describes a novel system for the immunological detection of immobilized antigen. The detection of herpes simplex virus (HSV) antigen was used as an example. Bacteriophage M13, containing the E. coli lac Z gene, was used as the "reporter" molecule in an immunoassay which is otherwise analogous to the enzyme-linked immunoabsorbant assay (ELISA). Briefly, HSV infected cells were incubated with a mouse monoclonal antibody specific for HSV antigen, followed by rabbit anti-mouse serum and mouse anti-M13 serum. Immune complexes were incubated with viable M13 phage. M13 binding was due to the presence of M13 antibodies, whose presence ultimately depended on the binding of monoclonal antibody to HSV. Phage was recovered by elution in pH = 11. Recovered phage was used to infect E. coli. M13 was quantitated by either plaque assay or by an assay for phage-induced beta-galactosidase activity in appropriate E. coli strains. The amount of M13 recovered was proportional to the number of HSV infected cells probed. Therefore, M13 served as a "bio-amplifiable tag" to antibody, as enzymes do in the ELISA. Since M13 is viable, its signal can be amplified by infection of susceptible bacteria, and the promise for an enormously sensitive immunoassay exists. The sensitivity of the assay described here is compared to the ELISA in the detection of HSV infection cells, as an example of the novel assay's potential. Significantly, the novel assay was more sensitive than the ELISA when samples were tested under identical circumstances. This technique is called the phage-linked immunoabsorbant assay (PHALISA), by analogy to the ELISA.

Antigens, Viral↗

PubMedDate not supplied

Formaldehyde, sodium hypochlorite, and metabisulphite are equally effective as sterilants for central delivery systems.

Sterilants are used to disinfect reverse osmosis (RO) thin film composite membranes or peripheral loop water delivery systems. Formaldehyde (4.0% weight/volume) and metabisulphite (1.0%) were used to sterilize the RO and peripheral loop, and sodium hypochlorite (0.5%) was used to sterilize the peripheral loop with only acid/alkaline treatment of the RO; each sterilant was evaluated for 4 months. Sanitization at the machine was with sodium hypochlorite or glutaraldehyde. Quantitative RO processed water (weekly) and dialysate (4-6 from each station during the period of each sterilant) cultures were obtained. AAMI standards were used (< 200 CFU/ml RO water; < 2,000 CFU/ml dialysate). Bacterial growth exceeded Association for the Advancement of Medical Instrumentation (AAMI) limits in 16% of RO water and 4.7% of dialysate samples, but repeat cultures invariably failed to confirm initial abnormal results. Chi-square analysis showed no differences among sterilants. No difference among sterilants was noted in arithmetic or log10 mean colony counts. Sporadic low level gram positive and gram negative organism growth occurred with all sterilants. Continued "sterility" that met AAMI standards was obtained for 1 year, first with metabisulphite and then with acid/alkaline RO and sodium hypochlorite loop treatment. It is concluded that all three sterilants are effective for disinfection of hemodialysis delivery systems. Sodium hypochlorite is recommended because of its safety advantages and readily available test of adequate removal.

Colony Count, Microbial↗