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Biomedical subjects

J H Thompson

Publications and source records attributed to J H Thompson.

At least 19 recordsLinked to original sources
PubMed1995

Potential role of nitric oxide in a model of chronic colitis in rhesus macaques.

BACKGROUND/AIMS: Excess nitric oxide formation, via the inducible NO synthase isoform, has been implicated in the pathogenesis of experimental and clinical inflammatory bowel disease. The aim of this study was to assess the site, enzyme source, and magnitude of NO production in juvenile rhesus macaques with idiopathic colitis. METHODS: NO production was assessed systemically from plasma and urine levels of reactive nitrogen intermediates and locally by the formation of [3H]citrulline from [3H]arginine and reduced nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase histochemistry. Inducible NO synthase gene expression was assessed by reverse-transcription polymerase chain reaction. RESULTS: Plasma and urine levels of reactive nitrogen intermediates were greater in colitic animals than in control monkeys by 13- and 5-fold, respectively. NADPH diaphorase activity in normal animals was confined to the myenteric plexus. In colitis, staining was also apparent in crypt abscesses and superficial epithelial and mucosal bands. Gene expression for inducible NO synthase was only found in colitic specimens. Colonic [3H]citrulline formation was markedly elevated in colitic specimens, and the inducible isoform accounted for 58% of total activity. CONCLUSIONS: It is proposed that excess NO, formed via the inducible form of NO synthase, contributes to the mucosal inflammation and symptoms of this idiopathic colitis model.

Amino Acid Oxidoreductases↗
PubMed1995

Role of inducible nitric oxide synthase expression and peroxynitrite formation in guinea pig ileitis.

BACKGROUND & AIMS: Inflammatory bowel disease is characterized by increased synthesis of nitric oxide. The aim of this study was to determine if inducible NO synthase (iNOS) was responsible for tissue injury, potentially via peroxynitrite formation, in the guinea pig model of gut inflammation. METHODS: Inflammation was induced in guinea pig ileum by intraluminal administration of the hapten trinitrobenzene sulfonic acid in 50% ethanol. iNOS gene expression was assessed by reverse-transcriptase polymerase chain reaction and Western blotting, immunohistochemistry was determined by its localization, and activity was inhibited with the specific inhibitor aminoguanidine administered via the drinking water for 7 days. Nitration of tyrosines was assessed by immunohistochemistry. RESULTS: In control animals, iNOS gene expression was minimal to absent, whereas, in hapten, inflammation-marked iNOS gene expression was evident from day 1 to 7. Nitrotyrosine and iNOS immunohistochemistry were colocalized, and positive staining was most intense in epithelia and neurons. Inhibition of NO formation prevented nitrotyrosine formation. Aminoguanidine inhibited the inflammatory response and restored morphology. CONCLUSIONS: The colocalization of tyrosine nitration with iNOS immunoreactivity suggests that iNOS may be responsible for tissue injury and the formation of NO-dependent nitrating species, potentially peroxynitrite. Inhibition of iNOS may afford a new therapeutic approach to the treatment of inflammatory bowel disease.

Amino Acid Sequence↗
PubMed1985

Entamoeba polecki infection in Southeast Asian refugees: multiple cases of a rarely reported parasite.

Recently, Entamoeba polecki was identified for the first time in our parasitology laboratory in stool specimens from eight Southeast Asian refugees. This ameba has been reported infrequently in the Western world; most reported cases have been from the New Guinea region. In most previously described patients and in our patients, no definite gastrointestinal symptoms could be directly attributed to E. polecki infection. Morphologically, E. polecki may mimic the pathogen E. histolytica and also nonpathogens such as E. coli. These species are most readily distinguished by studying encysted forms. In contrast to E. histolytica and E. coli, E. polecki characteristically has uninucleate cysts. Both pigs and monkeys naturally harbor E. polecki, but four of the patients in this series had no apparent contact with these animals. Other modes of infection may be human-to-human transmission or acquisition from other domestic animals. Six of our eight patients were treated successfully with one course of metronidazole in a regimen similar to that used for E. histolytica infection. In the two other patients, repeated courses of therapy eradicated the infection. Because of the recent increase in number of Southeast Asian immigrants to the United States, E. polecki may be identified more frequently than in the past. Physicians and laboratory personnel should be familiar with this organism, because it may be confused with E. histolytica or may act as a pathogen.

Adolescent↗
PubMed1980

Visceral leishmaniasis (kala-azar) as a cause of fever of unknown origin.

A patient with a rare cause of fever of unknown origin, visceral leishmaniasis (kala-azar), is reported. The diagnosis was made by exploratory laparotomy and splenectomy after diagnostic studies had failed to reveal the cause of the fever. The patient was cured with a 6-day course of therapy with Pentostam (sodium antimony gluconate). Visceral leishmaniasis should be considered in the differential diagnosis of patients with obscure fever who have traveled in endemic areas.

Adult↗
PubMed1980

Infectious diseases of Indochinese refugees.

The recent Mayo Clinic experience in the diagnosis and treatment of infectious diseases in Indochinese refugees is discussed. One hundred patients from whom stool and blood specimens were submitted for parasitic examination showed a high percentage of parasitic infection, often with multiple agents. An outline for the initial medical examination and treatment of the parasitic agents found is presented.

Adolescent↗
PubMed1976

Plasma renin activity in diabetic autonomic neuropathy.

Postural changes in plasma renin activity were studied in three groups of age and duration-matched male diabetics (potent, impotent and with postural hypotension) and in non-diabetic control subjects. Those diabetic subjects with postural hypotension due to automatic neuropathy had no increase in plasma renin activity to the erect posture whereas both the potent and impotent groups had similar plasma renin activity responses to the control subjects. There was a significant inverse correlation between the rise in plasma renin activity on standing and the postural drop in blood pressure (r = 0.476, P less than 0.01) but no correlation with other tests of autonomic reflex function such as the Valsalva manoeuvre and blood pressure response to sustained handgrip. The results suggested that the lesion responsible for the postural hypotension is in the efferent sympathetic pathway. However, neuropathy per se did not wholly explain the decreased postural plasma renin activity response. Diabetic nephropathy, with involvement of cells of juxtaglomerular apparatus, may also be implicated.

Adult↗
PubMed1976

Hemoccult stool tests: false-negative results due to storage of specimens.

Stoll samples mixed with 0 to 38 mg of hemoglobin per gram of stool were tested for occult blood by the Hemoccult (HO) method when fresh and after storage for 1 to 14 days. The intensity of the HO reaction in fresh stool samples was directly related to the hemoglobin concentration, and approximately 8 mg/g was required for a positive reaction. After samples had been stored on HO cards for 4 days, the intensity of the HO reaction was decidedly less in all. Except at the highest concentrations studied, all became HO-negative or trace within 8 days. In contrast, samples of most concentrations that were stored in tightly capped containers prior to preparation of HO cards maintained a positive reaction intensity for 1 week. Nevertheless, the intensity of the HO reaction decreased significantly (P less than 0.01) with each method of storage. No false-positives were induced by storage during this portion of our study. Samples from 100 stool specimens sent to the clinical laboratory for determination of occult blood were also smeared on separate HO cards for testing immediately and after 4, 7, or 10 days of storage. Only one positive HO reaction was observed on an HO card prepared from a specimen initially classified as HO-negative. In contrast, up to 40% of the stored HO cards prepared from specimens initially classified as HO-positive were HO-negative when analyzed 4 days later.

False Negative Reactions↗
PubMed1973

Lack of effect of chronic nicotine administration on fatty acid distribution in the liver, testis, and adipose tissue of male Fischer-344 rats.

A comparison is made of the percentage compositions of major fatty acids in liver and testis phospholipids, liver and abdominal adipose tissue triglycerides, and liver sterol esters in male Fischer-344 rats administered a physiological saline control or a "smoking" dose of nicotine (1000 micro g base/kg/day, subcutaneously) for 2 or 22 months. Results indicate that there is no major trend, or significant difference, between nicotine- or saline-treated rats with respect to major fatty acid distribution. Some differences in fatty acid distribution in the various lipid fractions were found between young and old rats.

Adipose Tissue↗