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Biomedical subjects

R C Johnson

Publications and source records attributed to R C Johnson.

At least 253 records · Page 14Linked to original sources
PubMed1989

Characteristics of emigrants from Hawaii.

As part of an ongoing study on young adult psychological and social development, data were obtained through parental reports on the present residences and educational and occupational attainments of 718 present or former residents of Hawaii (average age 31 years). These subjects, as well as their parents, had been tested between 1972 and 1976 on measures of cognitive abilities and personality. The extent of emigration to the mainland in this middle to upper-middle class sample was over 40%. On average, former Hawaii residents now living on the US mainland were of higher intelligence and educational background than their counterparts still living in Hawaii. Differences were also found for number of children, cross-ethnic marriages, and occupational attainment (males only). In addition, parents of US mainland residents scored significantly higher on measures of cognitive abilities and education than parents of current Hawaii residents.

Adult↗
PubMed1989

Fasting plasma amino acids in elderly men.

The fasting amino acid profile in 22 healthy young men aged 25-35 y (group A) was compared with the fasting profile in 21 healthy independent men aged 65-85 y (group B), in 23 orally-fed nursing home men with dementia aged 65-92 y (group C), and in 17 tube-fed nursing home men with dementia aged 65-88 y (group D). Groups B, C, and D had significantly (p less than 0.05) lower levels of methionine and branched-chain amino acids than group A. Methionine was significantly lower in groups C and D than in group B. The ratio of essential to nonessential amino acids was significantly lower in groups B, C, and D than in group A. The data suggest that the intake of essential amino acids may often be suboptimal in both independent and institutionalized elderly men.

Aged↗
PubMed1989

Competitive effects of long-chain-triglyceride emulsion on the metabolism of medium-chain-triglyceride emulsions.

This study was conducted to assess the potential metabolic competitive interactions of intravenous medium-chain-triglyceride (MCT) and long-chain-triglyceride (LCT) lipid emulsions. To assess this competition increasing concentrations of LCT emulsion were added to an intravenous dose of MCT emulsion of 3.0 g/kg body wt up to a maximum dose of 3.0 g LCTs/kg body wt. Blood samples were assessed for competitive interactions by analyzing the following metabolites: glucose, insulin, lactate, pyruvate, ketones (acetoacetate, beta-hydroxybutyrate), elimination of triglycerides, and free fatty acids. Evaluation of the data showed a strong competitive interaction between the MCT and LCT emulsions. This competition was evident as soon as LCTs were added to the MCT infusions and appeared to favor LCTs for removal and metabolism over MCTs. This appears to indicate that there is a peripheral, strong affinity site for LCT removal and metabolism and a shared peripheral site and specific visceral site for MCT removal and metabolism.

Animals↗
PubMed1989

Human necrotizing splenitis caused by Borrelia burgdorferi.

A 25-year-old Hispanic male presented to the emergency room with complaints of severe left upper quadrant pain. Physicians determined that the patient had an acute inflammatory process with a possible diagnosis of splenic abscess. A splenectomy was performed. Histologic examination of the tissue sections revealed extensive necrosis and inflammation, but no etiologic agent was discernible. Microbiologic cultures of the tissue had negative results. A Dieterle silver stain revealed an overwhelming number of spirochetal bacteria most closely resembling Borrelia spp. The patient's serum was tested for serologic evidence of antibody to Borrelia burgdorferi with the following results; by indirect fluorescent antibody 1:32; by enzyme-linked immunosorbent assay for IgM, 1:320; and Western blotting had positive results for the presence of B. burgdorferi outer-surface protein antibodies. This is the first human case report of an acute necrotizing splenitis resulting from B. burgdorferi.

Adult↗
PubMed1989

Lyme disease and migrating birds in the Saint Croix River Valley.

During a study of migrating land birds in 1987, we examined over 9,200 individual birds representing 99 species from the Saint Croix River Valley, a Lyme disease-endemic area of east central Minnesota and northwestern Wisconsin. We found that 250 deer tick (Ixodes dammini) larvae and nymphs infested 58 birds from 15 migrant species; 56 ticks (22.4%) were positive for the Lyme disease spirochete Borrelia burgdorferi. Five ground-foraging migrant bird species favoring mesic habitats, veery (Catharus fuscescens), ovenbird (Seiurus aurocapillus), northern waterthrush (S. novaboracensis), common yellowthroat (Geothlypis trichas), and swamp sparrow (Melospiza georgiana), accounted for nearly three-quarters of parasitized individuals. Nearly half of the spirochete-positive ticks were removed from migrating birds taken in a riparian floodplain forest. Recaptured migrants with infected ticks indicate that they transmit B. burgdorferi to hexapod larvae. We suggest that birds may be both an important local reservoir in the upper Mississippi Valley and long-distance dispersal agents for B. burgdorferi-infected ticks to other regions of the continent.

Animals↗
PubMed1989

Antigenically variable Borrelia burgdorferi isolated from cottontail rabbits and Ixodes dentatus in rural and urban areas.

Spirochetes were isolated from 71 subadult Ixodes dentatus removed from cottontail rabbits captured in Millbrook, N.Y., and in New York, N.Y. Spirochetes were also cultured from kidney tissues of six rabbits. While all isolates reacted with monoclonal antibody H9724, which identifies the spirochetes as borreliae, more than half did not bind with antibody H5332 and even fewer reacted with H3TS, both of which were produced to outer surface protein A of Borrelia burgdorferi. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis protein profiles of three isolates differed from one another and from all previously characterized B. burgdorferi strains from humans, ticks, and wildlife in North America. The 12 periplasmic flagella that originated subterminally from each pointed end of a rabbit Borellia isolate contrasted with the 11 or fewer flagella for B. burgdorferi reported previously from North America. Although DNA homology and restriction endonuclease analysis also revealed differences among a rabbit kidney isolate, an I. dentatus isolate, and B. burgdorferi B31, similarities were sufficient to lead us to conclude that the borreliae in rabbits and I. dentatus are B. burgdorferi. Enzyme-linked immunosorbent assay titers of sera from humans with diagnosed Lyme disease to rabbit tick B. burgdorferi were often similar to one another and to those recorded for a reference B. burgdorferi strain.

Animals↗
PubMed1989

Detection of antigens in urine of mice and humans infected with Borrelia burgdorferi, etiologic agent of Lyme disease.

Lyme disease is a seasonal tick-borne malady which has worldwide distribution. Early and accurate diagnosis of Lyme disease is essential for successful antibiotic therapy. Symptoms are too vague to make an early diagnosis based on conventional criteria. We report the detection of antigens of Borrelia burgdorferi, causative agent of Lyme disease, in the urine of infected mice and humans. This technique may eventually provide a rapid diagnostic test for the early and accurate detection of this illness.

Animals↗
PubMed1989

Characterization of Borrelia burgdorferi isolates by restriction endonuclease analysis and DNA hybridization.

Genomes of several Borrelia burgdorferi isolates from North America and Europe were characterized by restriction endonuclease analysis and DNA hybridization using labeled B. burgdorferi whole-cell DNA (strain ATCC 35210). Several different restriction and homology patterns were observed among these isolates, indicating genotypic heterogeneity within this genus and species. It was concluded from this study that restriction endonuclease analysis of B. burgdorferi whole-cell DNA may be a reliable and accurate method for identifying strains or genotypes of the Lyme disease agent.

Animals↗
PubMed1988

Phosphatidylcholine synthesis by peritoneal mesothelium: its implications for peritoneal dialysis.

This study investigated the possibility that the peritoneum is capable of synthesizing phosphatidylcholine (PC), a lubricant surfactant, in an amount similar to that produced by pulmonary alveoli. The synthesis of PC by rat lung (positive control), liver (negative control), and transparent mesentery (test tissue) was determined by in vitro incubation of these tissues in the presence of (methyl-14C) choline chloride for three hours at 37 degrees C in Warburg flasks. All lipid material present in tissue and incubation media was extracted by the Folch technique. Carrier egg PC was added to each sample and total PC was isolated using high performance thin-layer chromatography. The PC fractions were counted for total radioactivity. No statistically significant difference was observed between the mean radioactive value for mesenteric tissue compared with lung tissue. The mean radioactive value for liver when compared with mesenteric and lung tissue was significantly lower (P less than 0.001). Thus, under the conditions of the experiment, we have demonstrated for the first time that peritoneal tissue is capable of synthesizing PC in amounts similar to that produced by the lung. Electron microscopy of transparent mesentery (test tissue) showed that mesothelium constituted the bulk of the cell population. Therefore, it is most likely that the PC that has been detected in peritoneal fluid is produced by the mesothelial cell. These findings are of significant relevance to developing concepts on the role of surfactant phospholipids in the physiology of peritoneal dialysis.

Animals↗
PubMed1988

Isolation of the gene encoding the Hin recombinational enhancer binding protein.

In vitro DNA inversion mediated by the protein Hin requires the presence of a recombinational enhancer sequence located in cis relative to the recombination sites and a protein, Fis, which binds to the enhancer. We have cloned and determined the primary sequence of the gene encoding Fis. The deduced amino acid sequence of Fis indicates that the protein is 98 amino acids long and contains a potential helix-turn-helix DNA binding motif at its carboxyl terminus. The gene encoding Fis maps at 72 min on the Escherichia coli chromosome. The construction of mutant strains of E. coli that lack a functional fis gene demonstrates that Fis is not essential for cell growth under laboratory conditions but is required for high rates of Hin-mediated site-specific inversion in vivo.

Amino Acid Sequence↗
PubMed1988

Renal artery reconstruction: extended indications.

Renal artery reconstruction has traditionally been limited to cases of documented renal artery hypertension. We report our experience with renal artery reconstruction on 32 arteries in 23 patients over a three-year period. These procedures were done for renovascular hypertension in nine patients, for renal preservation in seven patients, and concomitantly with aortic reconstruction in seven patients. Aortorenal bypass was the primary method of reconstruction, with thromboendarterectomy, primary reanastomosis, and splenorenal bypass being used less frequently. Significant improvement in hypertension was seen in virtually all patients, with improvement in renal function seen in all patients operated on for threatened renal function. In no case did renal function deteriorate postoperatively, and there have been no operative deaths. Major complications included postoperative hemorrhage (four patients), myocardial infarction (one patient), and restenosis of an artery after previous thromboendarterectomy (one patient). Renal artery revascularization procedures are safe and useful in selected patients with hypertension and ischemic nephropathy.

Aorta, Abdominal↗
PubMed1988

Effect of serum lipoproteins on growth and sterol synthesis in cultured rat brain glial cells.

Cells dissociated from brains of 1-day-old rats were cultured in medium containing either lipoprotein-deficient serum (LPDS) or LPDS plus various lipoprotein fractions. Increases in number of cells and in DNA content served as a measure of cell growth. Cholesterol synthesis was measured from the incorporation of [14C]acetate into total nonsaponifiable lipids and digitonin-precipitable sterols, and from the activity of the enzyme 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase. The data indicated that cholesterol biosynthesis from acetate was reduced in cells cultured in medium containing either LPDS plus low-density lipoproteins (LDL), high-density lipoproteins (HDL), or total lipoproteins (LP) and that this reduction was accompanied by a reduction in the activity of the HMG CoA reductase and an increase in the esterified sterol content. The reduction in cholesterol synthesis from acetate was maximal in cells cultured in the presence of HDL, whereas the maximal reduction in the activity of HMG CoA reductase occurred in cells cultured in the presence of LP. The presence of LDL or LP in the culture medium enhanced the cell growth but the presence of HDL did not. Esterified sterol content was highest in cells cultured in the medium containing LPDS plus LP and was not detected in cells cultured in LPDS medium. It is inferred from these data that rat brain glial cells in culture are able to utilize cholesterol in lipoproteins, that the presence of LDL in the medium enhances cell growth, and that reduced cholesterol synthesis in the presence of lipoproteins may occur at the HMG CoA reductase step as well as at some other step(s).

Acetates↗
PubMed1988

Judgments of "normal" and "problem" alcohol use as related to reported alcohol consumption.

We obtained alcohol use data and judgments of individual ("What do you think?") and cultural ("What do people in general think?") norms for normal and problem quantity and frequency of alcohol use, as well as ratings of whether particular alcohol-related behaviors indicated a drinking problem, from 928 adult respondents who were members of Hawaii's five major racial/ethnic groups [Chinese, European (Caucasian), Filipino, Hawaiian/Part-Hawaiian, and Japanese ancestry]. As compared with older survey data (but consonant with recent survey data), Hawaiians have substantially increased in alcohol use, as have Filipinos (if they drink at all; a high proportion are abstainers), and to a lesser extent, Japanese. Chinese remain very low in alcohol use, while Caucasians have relatively decreased in use. Alcohol use norms (especially of own judged normal use) vary across sexes and ethnic groups and are predictors of consumption both within and across groups. Family resemblances are substantial with regard to alcohol use category (present users, former drinkers, abstainers). Among present users, family resemblances are often significant with regard to amount used; resemblances are more substantial between mothers and offspring than between spouses or between fathers and offspring. There were small but significant ethnic group differences in the number of specific behaviors judged to be indicative of a drinking problem, with the groups reporting the highest mean alcohol consumption (Caucasians and Hawaiians/Part Hawaiians) also indicating more behaviors, particularly pathological as opposed to celebratory behaviors, as being problematic.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗