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Biomedical subjects

R C Johnson

Publications and source records attributed to R C Johnson.

At least 397 records · Page 22Linked to original sources
PubMed1978

Benign lymphoid hyperplasia manifesting as a cecal mass: report of a case.

We have presented an unusual case of benign lymphoid hyperplasia, which manifested as a cecal deformity in a 15-year-old boy. The clinical manifestation may have been related to partial occlusion of the appendiceal orifice. In future cases of benign lymphoid hyperplasia, colonoscopy may be diagnostic, and if it is used for continuing observation, may avert unnecessary surgical procedures in children and young adults.

Adolescent↗
PubMed1978

Ethnic variation in use and effects of alcohol.

Americans living in Hawaii were questioned about their use of alcoholic beverages. Although alcohol use was widespread in all ethnic groups included in the study, comparisons among groups showed that (a) a larger proportion of Orientals than Caucasians reported no use of alcohol, (b) Caucasians reported heavier use, and (c) a larger proportion of Oriental users reported facial flushing as a sequel to alcohol consumption. Persons with one Oriental and one Caucasian parent were intermediate with respect to (a) and (b), but were more similar to Orientals on (c). Other symptomology reported appeared to be associated with amount imbibed, not with ethnicity per se. Compared to current users, former users reported a larger number of problems and symptoms associated with alcohol use.

Adult↗
PubMed1978

Distribution of the genus Leptospira in soil and water.

The distribution of the aerobic spirochetes Leptospira in surface waters, soil, and aquatic animals was investigated. Isolates from water and soil exhibited physiological characteristics common to members of the "biflexa complex," none were capable of infecting experimental animals, and leptospires could not be isolated from the eight genera of aquatic animals examined. The isolation frequencies from surface waters were: stream, 100%; lake, 65%; spring, 28%; bog lake, 5%; and marsh, 0%. With the exception of the stream, more isolations were obtained from the soil adjacent to the water than from the water. Leptospires were most frequently associated with soils of high moisture and organic matter content.

Amphibians↗
PubMed1978

Protein-free and low-protein media for the cultivation of Leptospira.

A protein-free medium composed of charcoal-detoxified Tweens (polysorbates), vitamins B12 and B1, inorganic salts, and organic buffer is described that supports the growth and subculture of pathogenic and saprophytic Leptospira. Growth was initiated from small inocula, and cell densities of 10(9) organisms per ml were attained. Antigenicity and immunogenicity of Leptospira cultivated in this medium were similar to those of cells cultivated in serum-containing media. The protein-free medium was converted to a low-protein medium by the addition of 0.1% bovine serum albumin.

Antigens, Bacterial↗
PubMed1978

Lipid metabolism of Borrelia hermsi.

The synthesis of complex lipids by Borrelia hermsi while growing in Kelly medium was investigated by labeling cultures with D-[14C]glucose or [14C]palmitic acid. Labeled glucose was incorporated into phosphatidyl choline, phosphatidyl glycerol, monogalactosyl diglyceride, cholesterol glucoside, and acylated cholesteryl glucoside. The fatty acid composition reflected that of the medium suggesting that this spirochete directly incorporates acyl chains unaltered from its external milieu. Furthermore, the distribution of labeled carbon between acyl groups (lipid-soluble) and water-soluble moieties indicates that there is no metabolic exchange between these two pools. The relationship of B. hermsi to other spirochetes is discussed in terms of lipid metabolism as a generic characteristic.

Borrelia↗
PubMed1978

Mucopolysaccharide material resulting from the interaction of Treponema pallidum (Nichols strain) with cultured mammalian cells.

During incubation of Treponema pallidum (Nichols strain) with cultured mammlian cells derived from normal rabbit testes (NRT), an amorphous material accumulated at the surface of the cultured cells. This material was randomly distributed on all tissue cells within the culture chambers. The amount of amorphous material was dependent on the treponemal inocula. With 3 x 10(8) organisms per ml, this material was readily apparent within 2 days; with 4 x 10(7) organisms per ml, this material was detectable within 4 to 5 days; with lower inocula, the accumulation of amorphous material was far less apparent. Deposition of this surface-associated material required attachment of treponemes to the cultured cells, and the amount deposited was related to the number of treponemes attached per cell. This amorphous material was not detected when NRT cells were incubated with preparations of T. pallidum that were heat or air inactivated. In addition, the accumulaton of amorphous material was not due to a soluble component from host testicular tissue or to a soluble component developing during treponemal infection. This was demonstrated by the inability of membrane filtered preparations of T. pallidum to induce the deposition of amorphous material at the surface of the cultured cells. The nature of this material appeared to be acidic mucopolysaccharide as indicated by its metachromatic staining properties, its stainability with ruthenium red, and its partial degradation by bovine and streptomyces hyaluronidase. This amorphous material that accumulated in vitro at the surface of cultured cells may be similar to the mucoid material that accumulates in vivo during syphilitic infection.

Animals↗
PubMed1978

Reduction of postreplication DNA repair in two Escherichia coli mutants with temperature-sensitive polymerase III activity: implications for the postreplication repair pathway.

Daughter strand gaps are secondary lesions caused by interrupted DNA synthesis in the proximity of UV-induced pyrimidine dimers. The relative roles of DNA recombination and de novo DNA synthesis in filling such gaps have not been clarified, although both are required for complete closure. In this study, the Escherichia coli E486 and E511 dnaE(Ts) mutants, in which DNA polymerase I but not DNA polymerase III is active at 43 degrees C, were examined. Both mutants demonstrated reduced gap closure in comparison with the progenitor strain at the nonpermissive temperature. These results and those of previous studies support the hypothesis that both DNA polymerase I and DNA polymerase III contribute to gap closure, suggesting a cooperative effort in the repair of each gap. Benzoylated, naphthoylated diethylaminoethyl-cellulose chromatography analysis for persistence of single-strand DNA in the absence of DNA polymerase III activity suggested that de novo DNA synthesis initiates the filling of daughter strand gaps.

DNA Polymerase II↗
PubMed1978

The inflammatory esophagogastric polyp and fold.

A radiographic finding, previously undescribed to our knowledge of a polypoid defect and prominent fold in the region of the esophagogastric junction was seen in 9 patients. We believe this represents a stage in the evolution of chronic esophagitis.

Adult↗
PubMed1978

Humoral immune responses of cattle vaccinated with leptospiral pentavalent outer envelope and whole culture vaccines.

The humoral immune response of cattle vaccinated with leptospiral pentavalent outer envelope and whole culture vaccines was monitored with the microscopic agglutination (MA) test and the leptospiricidal activity (LA) test for a 2.5-year period. The serovars present in the vaccines were canicola, icterohaemorrhagiae, grippotyphosa, pomona, and hardjo. The LA test had greater sensitivity than the MA test for detecting antibodies to the hardjo, canicola, and icterohaemorrhagiae components of the pentavalent vaccine and was approximately equal in sensitivity to the MA test for detecting antibodies to the grippotyphosa and pomona components of the leptospiral vaccine. Both IgM and IgG were produced in similar amounts in the immunized cattle, and both classes were reactive in the MA and the LA tests. The IgM class of antibodies was more reactive in the MA test, whereas the IgG class of antibodies was more reactive in the LA test. Using the MA test as the criterion of evaluating, the immunogenic potency of the individual vaccine components was found to be canicola more than icterohaemorrhagiae more than grippotyphosa more than pomona more than hardjo. A direct correlation between protective antibodies, as determined by the hamster passive protection test, and antibodies reactive in the MA and the LA tests was observed.

Agglutination Tests↗
PubMed1978

Humoral immune response of dogs vaccinated with leptospiral pentavalent outer envelope and whole culture vaccines.

The humoral immune response of dogs vaccinated with leptospiral pentavalent outer envelope and whole culture vaccines was monitored with the microscopic agglutination (MA) test and leptospiricidal activity (LA) test for a 2-year period. The leptospiral serovars in the vaccines was canicola, icterohaemorrhagiae, grippotyphosa, pomona, and hardjo. The LA test was markedly more sensitive than the MA test for detecting anti-Leptospira antibodies and was least noticeable with anti-pomona antibodies. Both Igm and IgG were produced in similar amounts in the vaccinated dogs, and both classes of immunoglobulins were reactive in the MA and LA tests. The IgM class of antibodies was slightly more reactive in the MA test, whereas IgG antibodies were somewhat more reactive in the LA test. A direct correlation between protective antibodies, as determined by the hamster passive-protection test, and antibodies reactive in the MA and LA tests was observed.

Agglutination Tests↗
PubMed1977

Metabolic regulation of aminoacyl-tRNA synthetase biosynthesis in bakers' yeast.

The specific activities of 15 aminoacyl-tRNA synthetases in Saccharomyces cerevisiae were measured after growth under a variety of conditions that produced a range of cell-doubling times. The specific activity of each synthetase increased as cell-doubling time decreased. Control experiments eliminate the possibility that these results are due to preferential recovery of synthetases, or to the presence of activators in the faster growing cultures or inhibitors in the slower growing ones. These observations run counter to the expectation that synthetases in bacteria and yeast are negatively regulated by free amino acids, or, more likely, by aminoacyl-tRNA. In fact, as the growth medium was enriched, generation times decreased, and synthetase and aminoacyl-tRNA levels increased. It is suggested that cytoplasmic aminoacyl-tRNA synthetases may be more or less coordinately controlled such that their response to growth follows the pattern observed for ribosome production and RNA synthesis. This suggests the possibility of coordinated response of genes for components of the protein synthetic apparatus.

Alcohol Oxidoreductases↗
PubMed1977

Fatty acid composition of lipids in cerebral myelin and synaptosomes in phenylketonuria and Down syndrome.

Lipid and fatty acid composition of myelin and synaptosomes isolated from brains of phenylketonuric (PKU) and Down syndrome (DS) patients and patients with neither of these disorders was determined. No differences were observed in the proportions of cholesterol to phospholipids in synaptosomes and cholesterol to galactolipids to phospholipids in myelin or in the fatty acid composition of phospholipids in synaptosomes. However, the myelin from PKU brains contained reduced proportions of unsaturated and long-chain fatty acids. We conclude that genetic PKU and its experimental model have in common a defect in cerebral fatty acid metabolism, and that cerebral lipid abnormalities in this condition, rather than being generalized, may be confined to the glial cell population that synthesizes myelin. We further conclude that DS is not associated with an abnormality of cerebral lipid metabolism.

Adolescent↗
PubMed1977

Ability to transcribe music and ear superiority for tone sequences.

Trained musicians able to transcribe music make fewer erros in recognition of conventional melodies when the melodies are presented in the right ear, but show more right ear than left ear errors in the recognition of random note sequences. Other subjects, even though able to read music and play instruments, make more errors across all types of stimuli when stimuli are presented in the right ear. The ability to transcribe music, but not the ability to read music or to play instruments is associated with a sharp reduction in errors for stimuli presented in either ear.

Auditory Perception↗