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Biomedical subjects

S E Johnson

Publications and source records attributed to S E Johnson.

At least 73 records · Page 4Linked to original sources
PubMed1989

Esophageal acid clearance test in healthy dogs.

Esophageal acid clearance in healthy dogs was evaluated by placing a pH probe in the distal esophagus and determining the number of swallows and time required for esophageal pH to reach 4.0 after injection of a 10 mL bolus of 0.1 N hydrochloric acid. The increase in pH occurred in a stepwise fashion and was associated with esophageal peristalsis as determined by esophageal manometry. The number of swallows required for acid clearance varied from four to 12 with a mean of 8 +/- 1.8. The time required for acid clearance varied from 150 to 480 s with a mean of 285 +/- 75. No significant difference was noted after 0.16 mg/kg of lenperone hydrochloride was given intramuscularly. The esophageal acid clearance test in dogs appears similar to that reported in humans.

Animals↗
PubMed1989

Strange bedfellows: duodenal ulcer and cancer of the stomach.

We have found only 308 cases of gastric cancer in patients with unoperated duodenal ulcer. We present seven men whose duodenal ulcer disease obscured the diagnosis of gastric cancer. We review the theoretical reasons that those with duodenal ulcer may be protected from gastric cancer, along with the current literature.

Adenocarcinoma↗
PubMed1988

Visceral leishmaniasis in an English foxhound from an Ohio research colony.

Visceral leishmaniasis was diagnosed in a 5-year-old English Foxhound born and housed in an Ohio research colony. Physical examination revealed pyrexia, hematochezia, panuveitis, splenomegaly, and lymphadenopathy. Hematologic and serum biochemical abnormalities consisted of anemia, thrombocytopenia, hypoalbuminemia, hyperglobulinemia, azotemia, and proteinuria. Postmortem examination revealed widely disseminated (spleen, bone marrow, lymph node, liver, kidney, lungs) Leishmania amastigotes within macrophages.

Animals↗
PubMed1988

Tumor necrosis factor receptors and cytocidal activity are down-regulated by activators of protein kinase C.

Human HeLa cells and murine L(S) cells are highly sensitive to the cytocidal activity of tumor necrosis factor (TNF) when simultaneously treated with the inhibitor of protein synthesis cycloheximide. This cytocidal activity of TNF was inhibited up to 90% in both cell lines after a 15-60-min pretreatment with 3-10 ng/ml of phorbol 12-myristate 13-acetate (PMA). This inhibition was long lasting for HeLa cells but transient for L(S) cells. The protection afforded by PMA was most effective when the cells were pretreated with this phorbol ester, but it decreased when PMA was added together with TNF or after TNF addition. This finding suggested that PMA interfered with one of the early steps in the mechanism of action of TNF. A pretreatment with the calcium ionophore A23187 also reduced the cytocidal activity of TNF in both HeLa and L(S) cells to about the same extent. Treatment of these cells with either PMA or A23187 significantly decreased the binding of 125I-TNF to cell surface receptors. This decrease paralleled the time course and dose-response of the inhibition of cytocidal activity. In addition, treatment of HeLa cells with 1-oleyl-2-acetyl-glycerol (OAG) also induced a rapid loss of TNF binding capacity. Since OAG, PMA, and A23187 are all activators of protein kinase C (Ca2+/phospholipid-dependent enzyme), these results suggest that this kinase is involved in modulation of TNF sensitivity. Furthermore, depletion or inhibition of protein kinase C antagonized PMA-induced effects on TNF cytotoxicity and binding to receptors. Internalization of bound TNF was not significantly affected by PMA treatment, and Scatchard analysis of binding data indicated that PMA decreased TNF receptor binding affinity rather than the number of TNF-binding sites. These findings suggest that protein kinase C may have a physiological role in mediating TNF sensitivity.

Animals↗
PubMed1988

Serum bile acid analysis in dogs with experimentally induced cholestatic jaundice.

Serum bile acid (SBA) concentration was determined weekly for 4 weeks in dogs with experimentally induced hyperbilirubinemic liver disease. Obstructive jaundice was created in 6 dogs by surgical ligation of the common bile duct, and hepatocellular jaundice was created in 6 sham-operated dogs by administration of dimethylnitrosamine; 6 other sham-operated dogs served as controls. Serum bile acid concentration increased rapidly after bile duct ligation (from 0.6 +/- 0.1 to 69.2 +/- 15.3 mumol/L at 3 days), peaked at 14 days (247.8 +/- 54.1 mumol/L), and then gradually decreased (179.9 +/- 27.1 mumol/L at 28 days). Serum bile acid concentration in dimethylnitrosamine-treated dogs increased more gradually to 38.9 +/- 10.7 mumol/L at 28 days, at which time the serum bilirubin concentration was comparable with that of bile duct-ligated dogs. Mean total SBA values in bile duct-ligated dogs were significantly (P less than 0.01) higher than those in control and dimethylnitrosamine-treated dogs at days 3 through 28, with no overlap of individual values. Serum bile acid concentration at day 28 correlated positively (P less than 0.01) with cholestasis and bile duct proliferation observed in liver biopsy specimens, but did not correlate with necrosis or inflammation. Serum bile acid concentration also correlated positively (P less than 0.01) with serum bilirubin and cholesterol concentrations and with serum alkaline phosphatase and alanine transaminase activities. Results of the study reported here indicated a relationship between SBA concentration and cholestasis in dogs; extrahepatic bile duct obstruction resulted in the highest SBA values.(ABSTRACT TRUNCATED AT 250 WORDS)

Alanine Transaminase↗
PubMed1987

Cytocidal activity of tumour necrosis factor: protection by protease inhibitors.

The mechanism of the cytostatic and cytocidal activities of TNF was studied in human tumour cells. BT-20 breast and ME-180 cervical cancer cells were significantly growth-inhibited by TNF, but other cells were not. When protein synthesis was inhibited by cycloheximide, however, TNF was cytotoxic for all cells except BT-20 cells. This suggests that different mechanisms are responsible for the cytostatic and cytocidal activities of TNF. The sensitivity of different cell lines could not be correlated with the number or affinity of TNF receptors. Some protease inhibitors completely protected human and murine cells from TNF cytotoxicity. Inhibitors of chymotrypsin-like proteases were more effective than inhibitors of trypsin-like proteases. Reversible and irreversible inhibitors (such as alkylating compounds) were both protective. The cells were best protected when pretreated with inhibitors before the addition of TNF. When the protease inhibitors were removed the cells gradually lost their resistance to TNF cytotoxicity. The inhibitors did not interfere with the functioning of TNF-receptor complexes, since SK-MEL-109 melanoma cells treated with a protease inhibitor synthesized TNF-induced proteins. These findings suggest that a protease is involved in the cytocidal activity of TNF.

Humans↗
PubMed1987

Protection from tumor necrosis factor cytotoxicity by protease inhibitors.

Tumor necrosis factor (TNF) is cytocidal for human and murine cells when protein synthesis is inhibited by cycloheximide, but some protease inhibitors completely protect these cells from TNF cytotoxicity. Inhibitors of chymotrypsin-like proteases are active at lower concentrations than inhibitors of trypsin-like proteases. Both irreversible inhibitors, such as alkylating compounds, and reversible inhibitors, such as substrates of proteases, protect cells from the cytocidal activity of TNF. This protection is most effective when the cells are pretreated with these inhibitors before addition of TNF. When the protease inhibitors are removed, the cells gradually lose resistance to TNF cytotoxicity. The inhibitors do not interfere with the functioning of TNF-receptor complexes, since SK-MEL-109 melanoma cells treated with a protease inhibitor synthesize a TNF-induced protein. These findings suggest that a protease in involved in the cytocidal action of TNF.

Animals↗
PubMed1986

A method for one-step freezing of mouse embryos.

A simple one-step method of freezing mouse embryos directly in liquid nitrogen is described. The main objective of this study was to assess post-thaw survival following predehydration in various mixtures of glycerol and sucrose. Also investigated was pretreatment with glycerol prior to dehydration and effects of embryo stage. When sucrose was held constant (0.25 M) and glycerol concentration varied (1.0-4.0 M), post-thaw survival was best (67%) in 2.0 M glycerol. Pretreatment in glycerol provided no advantage over no pretreatment. When glycerol was held constant (2.0 M) and sucrose concentration varied (0-1.0 M), optimum post-thaw survival (81%) was found in 0.5 M sucrose. Morulae survived better than blastocysts (86% vs 72%, respectively). Transfer of thawed embryos frozen by the optimum treatment (2.0 M glycerol + 0.5 M sucrose) resulted in a birthrate of 41%, compared to 54% for fresh controls. This technique could find application in freezing and thawing of livestock embryos on the farm.

Journal Article↗
PubMed1985

Clinicopathologic findings resembling hypoadrenocorticism in dogs with primary gastrointestinal disease.

Nine dogs with primary gastrointestinal disease had clinical and laboratory findings resembling hypoadrenocorticism. The dogs had histories of anorexia, weakness or lethargy, diarrhea, vomiting, and weight loss. Hypothermia, dehydration, and emaciation also were detected on physical examination. Hyponatremia, hyperkalemia, and abnormally low Na/K ratios were found on laboratory evaluation, but results of ACTH-response tests were not compatible with hypoadrenocorticism. The primary diagnoses were trichuriasis and salmonellosis in 2 dogs, trichuriasis in 5 dogs, and perforated duodenal ulcer in 2 dogs. Most dogs responded to medical or surgical treatment of their primary gastrointestinal disease, and the original electrolyte abnormalities resolved. These findings emphasize the importance of the ACTH-response test in the diagnostic evaluation of dogs with clinicopathologic findings similar to those of hypoadrenocorticism.

Adrenal Insufficiency↗
PubMed1985

Continence following ileo-anal anastomosis with an antiperistaltic terminal ileal segment.

The procedure of total colectomy, excision of the rectal mucosa and ileo-anal anastomosis with or without a proximal small intestinal reservoir has been described as a method of treating patients with ulcerative colitis and familial polyposis coli. The purpose of constructing a terminal ileal reservoir is to reduce the severe diarrhoea which often occurs following ileo-anal anastomosis. It is suggested that the use of a single antiperistaltic segment for this purpose would reduce the diarrhoea, and provide continence. This has been tested in the dog and the results are reported in this publication.

Anal Canal↗
PubMed1985

Utilization of galactose by human platelets in vitro.

The extent to which platelets can metabolize galactose has been unknown. We have studied this question by incubating platelets with radiolabeled galactose for periods of time and analyzing the cells for radioactive metabolites. The sugar was observed to accumulate quickly in cells isolated by filtration. Within seconds at room temperature, galactose metabolites were detectable by thin-layer chromatography, and within 20 minutes at 37 degrees C, radioactivity appeared in trichloroacetic acid (TCA) precipitates of the suspensions. The TCA-precipitable radioactivity was degraded by alpha-amylase as well as by protease. However, the TCA-soluble material released by protease digestion had an elution volume on Sepharose CL-4B too small for glycopeptides and in addition was degraded by alpha-amylase. The majority of the galactose metabolized by platelets, therefore, becomes incorporated into glycogen, rather than glycoprotein. The reversibility of the galactose metabolic pathway was demonstrated by the addition of an excess of the unlabeled sugar to the labeled platelets and by the effect of thrombin and collagen on the TCA-precipitable radioactivity.

Blood Platelets↗
PubMed1985

Determination of serum bile acids in fasting dogs with hepatobiliary disease.

The diagnostic value of determining total conjugated serum bile acid (SBA) concentrations was evaluated in fasting dogs with spontaneous liver disease. Conjugated primary SBA values were determined by radioimmunoassay in 12 healthy dogs, 64 dogs with hepatobiliary disease, and 9 dogs with intestinal disorders unassociated with clinical or biochemical evidence of liver disease. Reference values for SBA concentrations ranged from 0 to 5 mumol/L and were not significantly different from those determined in dogs with intestinal disease (P less than 0.05). Mean SBA concentrations determined in dogs with portosystemic shunts, glucocorticoid-induced hepatopathy, hepatic neoplasia, hepatitis, cholestasis, and cirrhosis were significantly greater than reference values (P less than 0.05). The mean SBA concentration in dogs with glucocorticoid-induced hepatopathy was significantly (P less than 0.05) lower than that in all other clinical groups of dogs with liver disease, except in dogs with cholestasis. Although these 2 groups were statistically indistinguishable, dogs with glucocorticoid-induced hepatopathy generally had lower SBA values (2 to 37 mumol/L) than did the group with cholestasis (2 to 562 mumol/L). The SBA concentrations in fasting dogs were weakly correlated with histologic evidence of hepatic damage, as determined by a total biopsy score (r = 0.28, P less than 0.02). Because total SBA concentrations were increased in 89% of all dogs with hepatobiliary disease, the determination of SBA appears to be a sensitive test of hepatic dysfunction.

Animals↗
PubMed1984

Hb J-Singa (alpha-78 Asn leads to Asp), a newly discovered hemoglobin variant with the same amino acid substitution as one of the two present in Hb J-Singapore (alpha-78 Asn leads to, alpha-79 Ala leads to Gly).

A new fast-moving alpha-chain Hb variant with an Asn leads to Asp substitution at position alpha-78 was found in a French-Acadian family living in Eastern Canada. The identical substitution was reported in Hb J-Singapore, which also had an additional Ala leads to Gly substitution at position alpha-79. The new variant, which did not result in any clinical symptoms, was named accordingly, Hb J-Singa.

Adult↗
PubMed1984

Lyme disease: a selective medium for isolation of the suspected etiological agent, a spirochete.

A simple procedure with a new selective culture medium for the isolation of the suspected etiological agent of Lyme disease from ticks is described. Live ticks (Ixodes dammini) were ground with a mortar and pestle, and the suspensions were inoculated into a selective and nonselective medium. The selective medium, which contained kanamycin and 5-fluorouracil, yielded positive spirochete cultures from 100% of the pooled ticks and from 79% of the single tick specimens. The isolation rate for the nonselective medium was 0% from the tick pools and 58% from the single tick specimens.

Animals↗
PubMed1984

DNA characterization of the spirochete that causes Lyme disease.

Lyme disease, a tick-borne disease long recognized in Europe but only recently recognized in the United States, was shown in 1982-1983 to be caused by a spirochete, the Lyme disease spirochete. Whether one or more species of the spirochete exists is unknown, as is its taxonomic status. To answer these questions, we determined (i) the DNA base (guanidine-plus-cytosine) content for five strains; (ii) the DNA relatedness of 10 strains from Europe or the United States (isolated from ticks, humans, and a mouse) by DNA hybridization (hydroxyapatite assay at 50 and 65 degrees C); and (iii) the DNA relatedness to other pathogenic spirochetes. The guanine-plus-cytosine content of the Lyme disease spirochete strains was 27.5 to 29.0 mol%, most similar to those of Borrelia hermsii (30.6 mol%) and Treponema hyodysenteriae (25.6 mol%) among the other spirochetes tested. DNA hybridization studies with 32P-labeled DNA from Lyme disease spirochete strain TLO-005, a human blood isolate, revealed divergence (unpaired bases) within related nucleotide sequences of only 0.0 to 1.0% for all nine Lyme disease spirochete strains tested for relatedness to TLO-005. Relatedness values of seven strains to TLO-005 were 58 to 98% (mean, 71%) in 50 degrees C reactions and 50 to 93% (mean, 69%) in 65 degrees C reactions. Two other strains, from which very low yields of DNA were obtained, showed less relatedness (36 to 50 degrees C, 38 to 47% at 65 degrees C). These were nonetheless considered to belong to the same species because of the low amount of divergence in the sequences related to TLO-005 and the absence of decreased relatedness in reactions done at 65 degrees Celsius compared with those done at 50 degrees Celsius. DNA from strain TLO-005 showed relatedness of 1% to DNAs of two leptospires and 16% relatedness to DNA from T. hyodysenteriae. B. hermsii DNA was 30 to 40% related to three Lyme disease spirochete strains in 50 degrees Celsius reactions. Divergence in these reactions was 16.5 to 18.5%, and relatedness in 65 degree Celsius reactions was 8 to 10%. On the bases of phenotypic similarity, guanine-plus-cytosine content, and DNA relatedness to B. hermsii, we conclude the Lyme disease spirochete is single previously undescribed species which belongs in the genus Borrelia.

Animals↗
PubMed1984

Hb Wayne, the frameshift variant with extended alpha chains observed in a Caucasian family from Alabama.

The presence of the alpha-globin frameshift mutant, Hb Wayne, in three generations of a second family is described. The data include a hematological evaluation of the four heterozygotes, structural characterization of the variant, the use of HPLC for the separation of tryptic and chymotryptic peptides, functional analyses of the isolated variant showing high affinity for oxygen and the (near) absence of a Bohr effect, and alpha chain gene organization analyses with restriction endonuclease technology suggesting that the Hb Wayne heterozygote has a full complement of four alpha globin genes.

Adult↗