Search PubMed⌕ Search

Biomedical subjects

S E Johnson

Publications and source records attributed to S E Johnson.

At least 55 records · Page 3Linked to original sources
PubMed1993

Systemic mycosis caused by Acremonium sp in a dog.

A 4-year-old female German Shepherd Dog was examined to determine the cause of ataxia, progressive head tilt, anorexia, lethargy, and weight loss of 3 weeks' duration. A vestibular syndrome, generalized lymphadenopathy, bilateral uveitis, and chorioretinitis with complete detachment of the left retina were detected. Abnormal clinicopathologic findings were isosthenuria and hyperglobulinemia. The non-functional left eye was enucleated and fungal organisms resembling Aspergillus spp were identified on histologic examination. Microbial culture of a urine sample yielded Acremonium sp, which was initially considered a contaminant. The dog was considered to have systemic aspergillosis and was treated with itraconazole for 7 months, until it was euthanatized because of persistent vomiting and anorexia. Postmortem examination revealed multisystemic pyogranulomatous and necrotizing inflammation of the myocardium, pericardium, liver, and kidneys; and granulomatous splenitis, lymphadenitis, retinitis, endometritis, and meningoencephalitis. Fungal culture of affected organs yielded Acremonium sp. These findings indicated that Acremonium spp can be pathogenic and should not be ignored when cultured.

Acremonium↗
PubMed1993

Proliferating cell nuclear antigen (PCNA) is expressed in activated rat skeletal muscle satellite cells.

Skeletal muscle satellite cells from uninjured muscle of adult animals are generally found to be in a quiescent state, and when cultured, they remain quiescent in vitro for a period of time which is directly related to the age of the donor animal. A technique for studying the activation of satellite cells in primary cultures has been developed and employs proliferating cell nuclear antigen (PCNA) as a marker for entrance into the S phase of the cell cycle. PCNA is a protein involved in DNA replication and is maximally expressed in S phase of the cell cycle. We monitored PCNA expression in satellite cells isolated from young (3 week) and adult (9 month) rats, and our results indicate that satellite cells begin to accumulate PCNA prior to changes in cell number in both age groups. Using ELISA techniques, we demonstrated that addition of an extract of crushed muscle (CME) activated satellite cells and significantly reduced the length of the lag phase in cells from both age groups. Addition of bFGF shortened the lag phase of PCNA synthesis in satellite cells from 3-week-old rats but had no effect on the kinetics of PCNA expression in cells from 9-month-old rats. Based on our experiments, PCNA expression can be used as a marker to follow the entry of satellite cells into the cell cycle in primary mass cultures.

Animals↗
PubMed1993

The gamma fibrinogen gene (FGG) maps to chromosome 17 in both cattle and sheep.

The gamma fibrinogen gene (FGG) was localised in both cattle and sheep using in situ hybridisation. The probe employed was a 1-kb bovine cDNA fragment. Based on observations of QFQ-banded chromosome preparations, this locus is on bovine chromosome 17q12-->q13 and on the homologous sheep chromosome 17. This localisation is, to our knowledge, the first assignment to chromosome 17 in either the bovine or ovine genome. In addition to localising FGG to this chromosome, the assignment provisionally maps the previously unassigned syntenic group U23, containing (besides FGG) the genes for mitochondrial aldehyde dehydrogenase 2 (ALDH2), interleukin 2 (IL2), immunoglobulin lambda (IGL), and beta fibrinogen (FGB), to chromosome 17 in cattle and probably to the same chromosome in sheep.

Animals↗
PubMed1992

Serum lipoprotein concentrations and hepatic lesions in obese cats undergoing weight loss.

Serum lipoprotein concentrations, routine serum biochemical values, and morphologic changes of the liver were evaluated in cats undergoing weight loss. Food was withheld from 6 obese and 6 control cats for 3 days (days 0 to 2), followed by feeding 50% of previous food intake for 26 days (days 3 to 28). Percutaneous liver biopsy specimens were obtained from all cats on days 0, 7, 14, and 28. Blood samples for serum biochemical analysis and lipoprotein profiles were obtained on days 0, 3, 7, 14, and 28. All cats lost weight throughout the study, and none developed signs of clinical illness, including those of idiopathic hepatic lipidosis syndrome. Serum total cholesterol concentrations decreased initially in all cats, but rapidly returned to normal after day 3 in obese cats, suggesting altered cholesterol metabolism during dietary restriction. Low-density lipoprotein concentrations decreased throughout the study in control cats, but were unchanged in obese cats. Examination of liver biopsy specimens from each cat revealed minimal lipid accumulation in all specimens, although some specimens contained hydropic degeneration.

Animal Feed↗
PubMed1991

Desmin is present in proliferating rat muscle satellite cells but not in bovine muscle satellite cells.

The presence of desmin was characterized in cultured rat and bovine satellite cells and its potential usefulness as a marker for identifying satellite cells in vitro was evaluated. In primary cultures, positive immunohistochemical staining for desmin and skeletal muscle myosin was observed in rat and bovine myotubes. A small number of mononucleated cells (20% of rat satellite cells and 5% of bovine satellite cells) were myosin-positive, indicative of post-mitotic differentiated myocytes. In bovine satellite cell cultures 13% of the mononucleated cells were desmin-positive, while 84% of the mononucleated cells in rat satellite cell cultures were desmin-positive. Rat satellite cell mass cultures and bovine satellite cell clonal density cultures were pulsed with 3H-thymidine, and autoradiographic data revealed that greater than 94% of dividing rat cells were desmin-positive, suggesting that desmin is synthesized in proliferating rat satellite cells. However, no desmin was seen in cells that incorporated labeled thymidine in bovine satellite cell clones. Analysis of clonal density cultures revealed that only 14% of the mononucleated cells in bovine satellite cell colonies were desmin-positive, whereas 98% of the cells in rat satellite cell colonies were desmin-positive. Fibroblast colonies from both species were desmin-negative. In order to further examine the relationship between satellite cell differentiation and desmin expression, 5-bromo-2'-deoxyuridine (BrdU) was added to culture medium at the time of plating to inhibit differentiation. Fusion was inhibited in rat and bovine cultures, and cells continued to divide. Very few desmin-positive cells were found in bovine cultures, but greater than 90% of the cells in rat cultures stained positive for desmin. The presence of desmin and sarcomeric myosin was also evaluated in regenerating rat tibialis anterior five days after bupivacaine injection. In regenerating areas of the muscle many desmin-positive cells were present, and only a few cells stained positive for skeletal muscle myosin. Application of desmin staining to rat satellite cell growth assays indicated that rat satellite cells cultured in serum-containing medium were contaminated with fibroblasts at levels that ranged from approximately 5% in 24 hr cultures to 15% in mature cultures. In defined medium 4 day cultures contain approximately 95% to 98% desmin-positive satellite cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1991

Real ear measures of auditory brain stem response click spectra in infants and adults.

This study investigated spectral differences for auditory brain stem response (ABR) clicks measured in infant and adult ear canals. Click stimuli were presented via insert earphones into the ear canals of 15 adults and 11 infants at 30 and 60 dB nHL. An ER-7C probe microphone fed the stimulus to a spectrum analyzer for analysis of spectral content. Infants had spectral peaks at higher frequencies (mean = 2339.77 Hz) than adults (mean = 1618.75 Hz). The infants also exhibited greater variability in their spectral peaks (SD = 669.37) than did adults (SD = 319.0). The total energy of the clicks was the same in infants' and adults' ears. These results indicate that click stimuli such as those used for ABR testing resonate in infant and adult ears differently, and that the resonance in infants is much more variable than the resonance of adults. These findings provide additional evidence for the need to use infant norms when screening infant hearing using the ABR. Similarly, the findings suggest that infant ABRs may be more correlated with higher frequency behavioral thresholds than those assumed for adults.

Acoustic Stimulation↗
PubMed1991

Localization of the beta-subunit of follicle stimulating hormone in cattle and sheep by in situ hybridization.

The locus for the beta-subunit of the follicle stimulating hormone gene (FSHB) has been determined in both cattle and sheep by in situ hybridization of a bovine and an ovine cDNA probe, respectively, to metaphase chromosomes. Our results show that the FSHB locus is on cattle chromosome 15 in the region of bands q24-qter and in sheep on the cytogenetically homologous chromosome 15, also in the region q24-qter. The mapping of the FSHB gene in cattle together with the location of other genes (CAT, HBB and PTH) previously found to be syntenic in cattle and on human chromosome 11p, defines an evolutionarily conserved synteny. The localization of the FSHB gene to a cytogenetically homologous region in cattle and sheep is consistent with the hypothesis of extensively conserved chromosome structure in these two species.

Animals↗
PubMed1991

Safety and immunogenicity of subcutaneous H. influenzae vaccines in 15-17 month-old children.

To evaluate the safety and immunogenicity of subcutaneously administered PRP and PRP-D, one hundred and one healthy 15 to 17 month-old children were randomly assigned to receive two subcutaneous doses, 2 months apart, of either vaccine. The incidence of local and systemic reactions did not differ significantly between the two groups. PRP antibody levels in the pre-immunization sera of 95% of subjects were below the level associated with immediate protection from Hib disease (less than 0.15 microgram/ml). After the first dose, 32% of PRP and 70% of PRP-D (p less than 0.001) recipients achieved antibody levels of greater than or equal to 0.15 microgram/ml, and 8% and 26% (p = 0.003) respectively achieved levels greater than or equal to 1 microgram/ml, a level believed to predict long-term protection. After the second dose, antibody levels greater than or equal to 0.15 microgram/ml were reached in 38% of PRP and 88% of PRP-D (p less than 0.001) recipients and levels of greater than or equal to 1 microgram/ml were reached in 22% and 78% respectively (p less than 0.001). The geometric mean levels of PRP antibody after immunization were significantly higher in the PRP-D group after both the first and second doses (p less than 0.001). These results suggest that subcutaneous administration of both vaccines is safe, but PRP-D results in significantly higher antibody levels compared to PRP. The levels were lower than what has been reported following intramuscular administration.

Antibodies, Bacterial↗
PubMed1990

Positive and negative regulation of a tumor necrosis factor response in melanoma cells.

Tumor necrosis factor (TNF) elicits a wide variety of responses in target cells by binding to cell surface receptors, but the signal transduced from these receptors in unclear. We examined the role of two different second messenger systems in the regulation of plasminogen activator inhibitor, type 2 (PAI-2) induction by TNF in SK-MEL-109 melanoma cells. Synthesis of PAI-2 and transcription of its mRNA could be induced by a protein kinase C (PKC) activator, phorbol myristate acetate. In addition, induction of PAI-2 synthesis by TNF was blocked by two PKC inhibitors, staurosporine and 1-(5-isoquinolinesulfonyl)-2-methylpiperazine dihydrochloride. The inhibitor of cyclic nucleotide-dependent protein kinases, N-[2-(methylamino)-ethyl]-5-isoquinoline sulfonamide dihydrochloride, was much less effective in decreasing PAI-2 synthesis. Staurosporine and 1-(5-isoquinolinesulfonyl)-2-methylpiperazine dihydrochloride also inhibited both TNF- and phorbol myristate acetate-induced PAI-2 mRNA accumulation. We measured the binding of 3H-labeled phorbol dibutyrate to membrane and cytosol fractions of TNF-treated SK-MEL-109 cells and found a transient redistribution of 3H-labeled phorbol dibutyrate binding from cytosol to membrane fractions in response to TNF. In contrast to the positive regulation by PKC in promoting TNF-induced PAI-2 synthesis cAMP inhibited this response. Pretreatment of cells with agents that raise intracellular cAMP levels completely abolished TNF-induced PAI-2 synthesis. Addition of cAMP-elevating agents during TNF induction could also block PAI-2 synthesis. PAI-2 mRNA accumulation in response to TNF was inhibited, but not completely abolished, by cAMP-elevating agents, suggesting that cAMP also exerted its inhibitory effect at the translation level. The positive regulation of a TNF response by PKC and its negative modulation by cAMP may provide a means for intracellular coordination of signals from interacting extracellular factors in regulating TNF responses in different target cells.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1990

The effects of bFGF, IGF-I, and TGF-beta on RMo skeletal muscle cell proliferation and differentiation.

A new skeletal muscle cell line, rat myoblast omega or RMo, has been characterized with regard to the effects of three growth factors: basic fibroblast growth factor (bFGF), insulin-like growth factor I (IGF-I), and transforming growth factor beta (TGF-beta). Results indicate a differential response of these factors on both cell proliferation and differentiation. Exposure to bFGF and IGF-I stimulate proliferation, while TGF-beta has no effect on cell number. RMo cell differentiation, as indicated by skeletal myosin synthesis, is enhanced by IGF-I, whereas both bFGF and TGF-beta suppress differentiation. These responses are in agreement with the effects of bFGF, IGF-I, and TGF-beta on myogenic cells cultured from fetal and postnatal muscle, thereby suggesting that RMo cells can serve as a model system for the study of growth factor effects on skeletal muscle cells.

Animals↗
PubMed1990

Assignment of the growth hormone gene locus to 19q26-qter in cattle and to 11q25-qter in sheep by in situ hybridization.

The growth hormone gene locus (GH) of cattle and sheep was mapped to a chromosomal region in each species by using in situ hybridization. The probe employed was an 830-bp cDNA sequence from the ovine growth hormone gene. Based on QFQ chromosome preparations, our results show that the GH locus is on cattle chromosome 19 in the region of bands q26-qter and in sheep on chromosome region 11q25-qter. The GH assignments together with previous localizations of type I cytokeratin genes (KRTA) and one homeobox (HOX2) gene in cattle and one type I cytokeratin gene (KRTA) in sheep identify a strongly conserved chromosomal segment on human chromosome 17, bovine chromosome 19, and sheep chromosome 11.

Animals↗
PubMed1990

Borrelia burgdorferi: survival in experimentally infected human blood processed for transfusion.

The isolation of Borrelia burgdorferi from blood raises the possibility of bloodborne transmission of Lyme borreliosis through transfusions. To assess this possibility, the ability of B. burgdorferi to survive in human blood processed for transfusion was studied. Human blood was inoculated with B. burgdorferi type strain B-31 (ATCC 35210) at 0.2, 20, or 2000 viable cells/ml, processed by conventional blood banking procedures, stored at 4 degrees C, and cultured for B. burgdorferi at 12, 23, 36, and 48 days of storage. After processing, most B. burgdorferi were found in the packed cell fraction. At inoculum levels of 20 or 2000 viable cells/ml, B. burgdorferi survived in processed blood through 48 days of storage at 4 degrees C. B. burgdorferi was isolated from packed cells after 36 days of storage at 4 degrees C even when the initial inoculum level was as low as 0.2 cells/ml. The data demonstrate that B. burgdorferi can survive the blood processing procedures normally applied to transfused blood in the USA. Since hematogenous spread of the spirochete seems to occur early in the illness, primarily in symptomatic patients, the risk of transfusion-associated Lyme disease may be small. However, the possibility of survival of B. burgdorferi under blood banking conditions warrants a heightened awareness of this potential problem.

Blood Transfusion↗
PubMed1989

Muscle protein metabolism in finishing pigs fed ractopamine.

Forty crossbred barrows (average initial weight, 66.4 kg) were utilized to determine the effects of ractopamine (a phenethanolamine/beta adrenergic agonist) on protein accretion and synthesis, activities of cathepsins B, H, L and calcium-dependent proteinase and nucleic acid content of semitendinosus muscle (ST). All pigs were offered a 16% protein, mineral and vitamin fortified corn-soybean meal diet supplemented with either 0 or 20 ppm ractopamine for 14, 21, 28, 35 or 42 d. Protein synthesis (fractional rates) was studied in pigs at d 21 and 35; ST protease activities, protein and nucleic acid content were measured on d 14, 28 and 42. Ractopamine increased (P less than .01) ST total protein content and maintained RNA muscle concentration and total ST muscle RNA content. DNA content (mg/g ST) declined (P less than .05) upon ractopamine feeding, but total DNA per muscle remained unchanged except for d 42, when the ST muscles were largest. Fractional accretion rates (FAR) were 1.0 and 1.2% for control and ractopamine-fed pigs, respectively. Fractional protein synthesis rate (FSR) was higher (P less than .06) in ractopamine-fed pigs (6.1%/d) than in control pigs (4.4%/d). Fractional protein synthesis rate could account for the observed muscle hypertrophy and increased FAR. Estimated fractional breakdown rates (FBR = FSR - FAR) were 3.4%/d and 4.9%/d for control and ractopamine-fed pigs, respectively. The activities of the catheptic proteases and calcium-dependent proteinase were not affected by the treatments.

Adrenergic beta-Agonists↗
PubMed1989

Effects of cocaine and related drugs in nonhuman primates. III. Self-administration by squirrel monkeys.

The self-administration of cocaine was compared with that of bupropion, 1-(2-[bis(4-fluorophenyl)methoxy]ethyl]-4-(3-phenylpropyl)piperazine, mazindol, methylphenidate and nomifensine, drugs that displace [3H]cocaine from its binding sites and have monoamine uptake inhibiting effects in common with those of cocaine. Squirrel monkeys responded under a second-order fixed-interval schedule of consequent i.v. drug injection, and dose-effect curves were established by determining stable rates of responding maintained by saline and a range of doses of each drug. Cocaine (0.01-0.56 mg/kg/injection), bupropion (0.1-3.0 mg/kg/injection), 1-(2-[bis(4-fluorophenyl)methoxy]ethyl)-4-(3- phenylpropyl)piperazine-(0.03-1.0 mg/kg/injection), methylphenidate (0.01-0.3 mg/kg/injection) and nomifensine (0.01-0.3 mg/kg) maintained comparable rates and patterns of responding in all subjects, whereas mazindol (0.03-0.3 mg/kg) maintained self-administration behavior in only half the monkeys studied. The present results in conjunction with those of previous studies in squirrel monkeys reveal a close correspondence between the relative potencies of cocaine and related drugs for maintaining i.v. self-administration and for increasing rates of schedule-controlled responding, suggesting that the reinforcing and psychomotor-stimulant effects of the drugs are mediated similarly. The potency relations observed in the present study also agree generally with those observed for displacement of specifically bound [3H]cocaine in monkey caudate-putamen suggesting that the reinforcing effects of cocaine involve its actions at specific recognition sites in brain.

Animals↗
PubMed1989

Effect of lenperone hydrochloride on gastroesophageal sphincter pressure in healthy dogs.

Treatment of healthy dogs with the butyrophenone derivative, lenperone hydrochloride, at two different doses significantly decreased gastroesophageal sphincter pressure (GESP). No dose-related effect was identified. Individual variation in the response to lenperone hydrochloride was noted which was consistent on a day-to-day basis. Lenperone hydrochloride is unsuitable for chemical restraint of dogs undergoing esophageal manometry because it decreases GESP and because the magnitude of the decrease varies considerably between dogs.

Animals↗