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Biomedical subjects

R C Johnson

Publications and source records attributed to R C Johnson.

At least 325 records · Page 18Linked to original sources
PubMed1984

Chemical compositions of cell walls and polysaccharide fractions of spirochetes.

Cellular polysaccharide fractions of various representative members of genera of the family Spirochaetaceae were obtained by the ammonium hydroxide extraction method. The sugar composition of the polysaccharide preparations was complex and many kinds of sugars such as rhamnose, fucose, ribose, xylose, mannose, galactose, and glucose were detected in all of the spirochetes tested. Of particular interest was the presence of 4-O-methylmannose as a constituent polysaccharide in members of the genus Leptospira. This sugar was not detected in the polysaccharides of Spirochaeta, Borrelia, and Treponema. The chemical compositions of cell wall fractions were also examined. 4-O-Methylmannose was detected in the cell wall polysaccharides of the genus Leptospira but not in cell walls prepared from the Spirochaeta, Borrelia, and Treponema. The diaminopimelic acid present in cell wall peptidoglycans of the genus Leptospira was meso-diaminopimelic acid (A2pm). The molar ratios of alanine, glutamic acid, A2pm, glycine, muramic acid, and glucosamine in leptospiral cell walls were found to be approximately 2:1:1:1:1:1. In contrast to the Leptospira, the peptidoglycans of genera Spirochaeta, Borrelia, and Treponema contained ornithine (Orn) but not A2pm. Since 4-O-methylmannose and A2pm were found in the cell wall fractions of genus Leptospira but not in Spirochaeta, Borrelia, or Treponema, it was suggested that the chemical compositions of the cell wall might become an important criterion for the chemotaxonomy of Spirochaetales.

Carbohydrates↗
PubMed1984

T-cell-independent elimination of Borrelia turicatae.

Mice deficient or deprived of thymus-derived lymphocytes eliminated blood-borne Borrelia turicatae with efficiency comparable to that observed in normal littermates. When challenged with 10(5) borreliae, nude mice had mean (+/- standard deviation) primary spirochetemias lasting 3.1 +/- 0.2 days and mean (+/- standard deviation) peak bacterial counts of 3.0 X 10(7) +/- 0.5 X 10(7) cells per ml of blood; in comparison, heterozygous littermates and normal mice had respective primary spirochetemias lasting 3.4 +/- 0.6 and 3.2 +/- 0.2 days and respective peak counts of 8.0 X 10(7) +/- 1.5 X 10(7) and 5.5 X 10(7) +/- 0.9 X 10(7) bacterial cells per ml of blood. No increased responsiveness to concanavalin A was observed in infected nude mice, indicating the sustained lack of maturate T cells in these animals. Thymectomized and steroid-treated mice were also found to eliminate circulating borreliae with efficiency comparable to that observed in control animals. Irradiation of mice abrogated responsiveness to borreliae, but reconstitution with T-cell-depleted splenocytes restored antibody production. It is proposed that elimination of B. turicatae is mediated by a T-cell-independent immune response mechanism.

Animals↗
PubMed1984

Human phagocyte interactions with the Lyme disease spirochete.

The interaction between human polymorphonuclear leukocytes and monocytes and the Lyme disease spirochete was investigated by incubating phagocytes with microorganisms adherent to plastic or glass surfaces. Both cell populations readily phagocytized and killed spirochetes, and antibodies facilitated but were not essential for phagocytosis.

Animals↗
PubMed1984

Genetic relationship of lyme disease spirochetes to Borrelia, Treponema, and Leptospira spp.

Genetic studies were performed on the following spirochetes: three Lyme disease spirochetes isolated from Ixodes ticks and from human spinal fluid; three species of North American borreliae; four species of Treponema; and two species of Leptospira. The mol% G+C values for Lyme disease spirochetes were 27.3 to 30.5%, similar to values of 28.0 to 30.5% for Borrelia species but different from the values of Leptospira or Treponema species which ranged from 35.3 to 53%. Lyme disease spirochetes represent a new species of Borrelia, with DNA homologies of 31 to 59% with the three North American strains of Borrelia studied. These studies also showed that Lyme disease spirochetes from three sources constituted a single species, with DNA homologies ranging from 76 to 100%. A high degree of relatedness was also seen between the three North American borreliae, with homology varying from 77 to 95%, indicating that these spirochetes represent a single species. Lyme disease spirochetes and Borrelia species exhibited almost no homology with Leptospira and Treponema species (0 to 2%). Plasmids were detected in the three Lyme disease spirochetes and in the three North American borreliae.

Animals↗
PubMed1984

Infection of Syrian hamsters with Lyme disease spirochetes.

Syrian hamsters were shown to be susceptible to infection by the Lyme disease spirochete Borrelia burgdorferi. Although these spirochetes did not cause any outward signs of illness in these animals, they did cause a generalized infection. Spirochetemia was present during the first 6 days of infection. At 14 days postinfection, spirochetes could be isolated from one or more of the following organs: spleen, eyes, kidneys, liver, testes, and brain. Spirochetes were isolated from the eyes and kidneys of one animal 52 days postinfection, suggesting that these organisms may cause a persistent infection. Virulence of B. burgdorferi is maintained by animal passage but is lost upon prolonged in vitro cultivation.

Animals↗
PubMed1984

The flushing response to alcohol use among Koreans and Taiwanese.

Alcohol use, the existence of a flushing response to alcohol and the amount of alcohol required to evoke flushing were studied by questionnaire in 87 homeland Korean and 101 Taiwan Chinese families. SFs (slow flushers--flush after two or more drinks) and FFs (fast flushers--flush after one drink or less) were compared. Despite the similarity in the proportions of subjects who reported flushing, Koreans reported very heavy and Taiwanese very light alcohol use. The two groups differed substantially in the proportions of SFs and FFs. Five ethnic groups in Hawaii were compared with the Koreans and Taiwanese. It appears that fast flushing, but not slow flushing, leads to substantial decreases in alcohol use among all seven groups. The association of flushing type with the extent and duration of flushing and with the frequency of other alcohol-related symptoms may be dose-dependent. For both Koreans and Taiwanese, family resemblances in flushing are substantial but not supportive of the belief that flushing is dominant and results from the influence of a single autosomal gene pair. Of the large groups of subjects from whom data were obtained (Caucasians, Chinese, Filipinos, Hawaiians or part Hawaiians, and Japanese in Hawaii; homeland Koreans; and Taiwan Chinese), the Koreans and Taiwanese differ the most from one another in alcohol consumption. In summary, there is substantial diversity among groups frequently lumped together as "Mongoloid."

Adult↗
PubMed1983

Assay of AHF concentrates and standards: failure to eliminate variability with a monographed assay.

Previous calibration studies have shown a high interlaboratory variability in the potency of the proposed Office of Biologics (National Center for Drugs and Biologics, US-FDA) AHF standard relative to the 2nd International Standard for Factor VIII (Factor VIII:C) (WHO 73/552). This led to the formation of an Industry Collaborative Study group whose objective was to reduce the assay variability. The group, in collaboration with the Office of Biologics and the National Institute for Biological Standards and Control (UK), designed a study based on a monographed one-stage assay protocol, which specified all materials, assay methods, equipment, dilution technique, reagents, assay order, and calculation methodology. All participants received common reagents and samples, with the exception of substrate plasma. It was felt that substrate plasma could not be a common reagent in a monographed assay. However, each laboratory prepared substrate plasma according to the protocol. All data were analyzed by an independent statistical staff. Preparations assayed included two 10-donor plasma pools, the 2nd International Standard for Factor VIII (WHO 73/552), the proposed OoB Lot A internal standard, the participants' own house standards, and commercial AHF concentrate material. The results show a statistically insignificant reduction in the interlaboratory variability, but intralaboratory consistency was generally maintained. The study shows that monographing an assay for Factor VIII.

Adolescent↗
PubMed1983

Brain DNA metabolism in myelin deficient mutant jp, jpmsd and qk mice.

We studied metabolism of brain DNA in three myelin deficient mutants qk, jp and jpmsd mice. The DNA content, the in vivo incorporation of [14C]thymidine in DNA and the activity of acid DNase in tissues (cerebellum and cerebrum) from normal littermates and affected mice were compared. The results showed that neither the DNA content, the incorporation of [14C]thymidine in DNA nor the activity of acid DNase in brain were altered in qk affected mice. In jpmsd mice, however, the DNA content as well as the incorporation of thymidine in DNA were reduced in both cerebellum and cerebrum, but the activity of acid DNase was reduced in cerebrum only. In jp mice, although the DNA content was reduced in both cerebellum and cerebrum, the incorporation of thymidine in DNA and the activity of acid DNase were reduced in cerebrum only. The data suggest a) that in qk mutants DNA metabolism and hence cell (glial) proliferation is not affected; b) that in jpmsd mutants DNA synthesis, and thus the cell proliferation is reduced in cerebellum as well as in cerebrum of the affected mice and c) that in jp mutants the synthesis of DNA and the cell proliferation is reduced in cerebrum but not in cerebellum.

Animals↗
PubMed1983

Cholesterol ester content and activities of the ester metabolizing enzymes in jpmsd mouse brain.

The free and esterified cholesterol content, and the activities of cholesterol esterifying and the ester hydrolyzing enzyme in brain tissue from myelin synthesis-deficient mutant jpmsd mice and normal littermates were determined. Results showed that cholesterol ester content was high in the brain of jpmsd-affected mice and that the esterification of cholesterol in vitro, with or without added fatty acids was also high in the brain tissue of the affected mutant mice. The data suggest that the increase in cholesterol ester concentrations in the brain of jpmsd-affected mutant mice occurs as a result of increased synthesis rather than decreased hydrolysis.

Animals↗
PubMed1983

False-positive serum gastrin elevation during secretin stimulation due to Boots secretin.

Five patients with hypochlorhydria, chronic gastritis, and high serum gastrin levels and four control subjects underwent secretin stimulation testing. Gastrin determinations were made by a commercially available radioimmunoassay kit. Intravenous Boots secretin gave positive stimulation tests in all patients and controls. Positive Boots secretin stimulation tests in two of the control subjects were confirmed by a different gastrin assay kit. Synthetic secretin stimulation in two of the patients and the four control subjects showed no rise in postsecretin gastrin. Gastrin assay of pure Boots secretin from three different lots gave values ranging from 170,000 to 1,620,000 pg/ml. Gastrin assay of synthetic CCK 8 gave values of 718,600 and 1,300,000 pg/ml. Gastrin-like activity was undetectable in synthetic and GIH secretin and the normal saline used as a diluent. We conclude: 1) Boots secretin contains a contaminating substance or substances exhibiting immunoreactivity with commercially available gastrin assay kits, 2) cholecystokinin or cholecystokinin-like peptides are the leading candidates for contaminating substances in some assays, and 3) Boots secretin can cause false-positive secretin stimulation tests and should not be used in the secretin stimulation test for hypergastrinemia. We have switched exclusively to Kabi (GIH) secretin.

False Positive Reactions↗
PubMed1983

Synthesis and assembly of flagellar components by Caulobacter crescentus motility mutants.

Cultures of wild-type Caulobacter crescentus and strains with fla mutations representing 24 genes were pulse-labeled with 14C-amino acids and analyzed by immunoprecipitation to study the synthesis of flagellar components. Most fla mutants synthesize flagellin proteins at a reduced rate, suggesting the existence of some mechanism to prevent the accumulation of unpolymerized flagellin subunits. Two strains contain deletions that appear to remove a region necessary for this regulation. The hook protein does not seem to be subject to this type of regulation and, in addition, appears to be synthesized as a faster-sedimenting precursor. Mutations in a number of genes result in the appearance of degradation products of either the flagellin or the hook proteins. Mutations in flaA, -X, -Y, or -Z result in the production of filaments (stubs) that contain altered ratios of the flagellin proteins. In some flaA mutants, other flagellin-related proteins were assembled into the stub structures in addition to the flagellins normally present. Taken together, these analyses have begun to provide insight into the roles of individual fla genes in flagellum biogenesis in C. crescentus.

Bacteria↗
PubMed1983

Leptospiral vaccines: immunogenicity of protein-free medium cultivated whole cell bacterins in swine.

Swine serologically negative for anti-Leptospira antibodies were given 2 doses of a pentavalent vaccine (3 weeks between doses) prepared from Leptospira serovars canicola, icterohaemorrhagiae, hardjo, pomona, and grip-potyphosa (0.2 mg/serovar/dose). Leptospires used for vaccinal production were cultivated in a protein-free medium or in a bovine albumin-containing medium. All vaccinated swine had demonstrable antibody titers within 1 week of the initial vaccination. Peak microscopic agglutination titers were between 256 and 1,024 after the 2nd vaccinal dose was given. After challenge exposure with serovar canicola, control swine had titers of at least 13,653 and the vaccinated swine had titers of 3,403 to 8,192, depending on the vaccine. Leptospiremia and kidney infections were not detected in any canicola Moulton immunized swine, but did appear in control swine. The Al(OH)3 adjuvant had no obvious influence of any of the vaccinal titers.

Adjuvants, Immunologic↗
PubMed1983

Reoperative abdominal arterial surgery--a ten-year experience.

The safety and durability of elective reconstructive procedures of the abdominal aorta and its major branches are universally accepted; however, late complications continue to threaten limbs and lives of a minority of patients. The strategy of managing such revascularization failures has received inadequate attention. Between February 1971 and July 1981, 76 patients underwent 83 remedial, transabdominal revascularization procedures because of failed reconstructions. Group I consisted of 34 patients with occlusive complications (0% remedial operative mortality rate); group II, 21 patients with prosthetic sepsis including graft-enteric fistula (14% operative mortality); group III, 11 patients with aneurysmal degeneration (36% operative mortality); and group IV, 10 patients with visceral ischemia (0% operative mortality). The remedial operative mortality rate for the combined groups was 7.9%. Limb preservation was the rule in group I (91%); however, 29% of limbs at risk in group II ultimately required major amputation (15% early, 14% late). All patients in group II without an established graft-enteric fistula were saved; however, three of ten with active hemorrhage died of the sequelae of hypovolemic shock. Progressive arteriosclerotic morbidity and massive intraoperative bleeding accounted for the high mortality rate in group III. Favorable results were obtained in reoperation for recurrent visceral ischemia (renal ischemia in five, mesenteric ischemia in five). On the basis of this experience, an aggressive surgical approach seems justified. First, complete bifemoral revascularization performed at the time of original operation should reduce the need for reoperation. Second, elective, transabdominal remedial arterial surgery can be done with acceptable morbidity and mortality rates. Third, graft-enteric erosions and periprosthetic sepsis must be treated aggressively to avoid life-threatening sepsis and hemorrhage. Finally, anatomic revascularization can be performed successfully after a suitable period following removal of an infected retroperitoneal prosthesis.

Adult↗