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Biomedical subjects

A R Johnson

Publications and source records attributed to A R Johnson.

At least 109 records · Page 6Linked to original sources
PubMed1983

Microbiological analysis of rock cod (Sebastes spp.) stored under elevated carbon dioxide atmospheres.

The numbers and types of microorganisms on fresh rock cod fillets and fillets stored in air or in a modified atmosphere (MA; 80% CO(2), 20% air) at 4 degrees C were compared. Samples were analyzed after 0, 7, 14, and 21 days of storage. The isolation plates were incubated aerobically, anaerobically, or under MA at 4, 20, or 35 degrees C. After 7 days of storage in air, the fillets were obviously spoiled and had a 3- to 4-log cycle increase in microbial counts. Plate counts increased more slowly on MA-stored fillets. After 21 days, the counts on the latter had increased only 2 log cycles, and the fillets did not seem spoiled. The microbial flora changed greatly during MA storage. Only Lactobacillus spp. (70%) and an Aeromonas sp.-like isolate (30%) were found on plates incubated aerobically at 4 and 20 degrees C, and only Lactobacillus spp. was found on plates incubated aerobically and anaerobically at 35 and at 20 degrees C under MA. Isolation plates incubated at 20 degrees C in air gave the highest counts in the shortest incubation time and the greatest diversity of bacterial types recovered. No Vibrio parahaemolyticus, Staphylococcus aureus, or Clostridium botulinum type E were isolated from the fresh or MA-stored fillets.

Aerobiosis↗
PubMed1983

Metabolism of dehydroisoandrosterone and androstenedione in human pulmonary endothelial cells in culture.

The capacity of endothelial cells from pulmonary arteries and veins to convert dehydroisoandrosterone (3 beta-hydroxy-5-androsten-17-one) and androstenedione to potent, biologically active steroids was investigated. The metabolites of [3H]dehydroisoandrosterone produced in pulmonary artery endothelial cells were androstenedione and 5-androstene-3 beta, 17 beta-diol. The metabolites isolated from incubation of pulmonary arterial cells with [3H]androstenedione were testosterone, 5 alpha-androstane-3,17-dione, 5 alpha-dihydrotestosterone (17 beta-hydroxy-5 alpha-androstan-3-one), isoandrosterone (3 beta-hydroxy-5 alpha-androstan-17-one), and androsterone. The products of [3H]androstenedione metabolism in human pulmonary venous cells were the same as those formed in arterial cells, and in addition, 5 alpha-androstane-3 alpha,17 beta-diol and 5 alpha-androstane-3 beta, 17 beta-diol were formed. The rates of metabolite formation from [3H]androstenedione in pulmonary arterial and venous endothelial cells were linear with incubation time up to 3 h. These findings suggest that the pulmonary endothelium is an important site for the metabolism of dehydroisoandrosterone and androstenedione in the human lung. Endothelial cells produce the same metabolites as human lung tissue, with the exception of hydroxylated steroids.

Androstenediol↗
PubMed1983

Steroid sulfatase activity in human lung tissue and in endothelial pulmonary cells in culture.

The conversion of tritium-labeled estrone sulfate to [3H]estrone was evaluated in human lung tissue in vitro. Under standardized conditions, the rate of hydrolysis of [3H] estrone sulfate to [3H]estrone was linear with time of incubation up to 4 h and with wet tissue weight up to 400 mg/ml. The apparent Km of sulfatase for estrone sulfate was 9 microM, and the maximum velocity was 1.4 nmol substrate hydrolyzed/100 mg lung . h. The lung tissue also metabolized the primary metabolite of [3H]estrone sulfate, [3H]estrone, to 17 beta-[3H]estradiol. The hydrolysis of [3H]dehydroisoandrosterone sulfate to [3H]dehydroisoandrosterone by human lung tissue was also measured. Sulfatase activity with this substrate was linear as a function of wet tissue weight up to 800 mg/ml. The apparent Km of sulfatase for dehydroisoandrosterone sulfate was 7 microM, and the maximum velocity was 1.0 nmol substrate hydrolyzed/100 mg lung . h. The highest specific activity of lung sulfatase for [3H]dehydroisoandrosterone sulfate was found in a microsomal fraction of lung homogenate. The primary metabolite, [3H]dehydroisoandrosterone, was metabolized further by lung tissue to [3H]androstenedione and [3H]5-androstene-3 beta, 17 beta-diol. Although isolated segments of human pulmonary arteries also metabolized both [3H] estrone sulfate and [3H]dehydroisoandrosterone sulfate, cultures of pulmonary arterial endothelial cells lacked sulfatase activity. The cell(s) source of sulfatase activity in human lung tissue and isolated arteries has not yet been identified. Our findings suggest that the metabolism of sulfated steroids by the lung should be considered in evaluating homeostasis.

Cells, Cultured↗
PubMed1982

Sulfated glycoproteins secreted by human vascular endothelial cells.

Endothelial cells incorporate 35SO4 into a class of glycoproteins which are released from the cell layer into the culture medium. The incorporated 35SO4 was localized on intact oligosaccharide chains which were released from the protein either chemically by hydrazinolysis or enzymatically by a peptide: N-glycosidase activity; thus these 35S-oligosaccharides are presumably N-glycosidically linked to protein. These 35S-oligosaccharides were also isolated and analyzed as labeled glycopeptides and found to contain the terminal trisaccharide sequence sialic acid leads to galactose leads to N-acetylglucosamine. After removal of these carbohydrate residues, the remainder of this 35S-glycopeptide was susceptible to alpha-mannosidase digestion yielding a smaller 35 S-glycopeptide containing GlcNAc35SO4. Monensin (10(-8) M), a monovalent cation ionophore, inhibited the sulfation (greater than 80%) and synthesis (greater than 60%) of endothelial cell-sulfated proteoglycans which were released into the culture medium. However, neither the synthesis nor sulfation of cell-released 35S-glycoproteins was affected at similar monensin concentrations. Higher concentrations of monensin (greater 5 X 10(-8) M) inhibited the incorporation of both [3H]glucosamine and 35SO4 into cell-released glycoproteins.U

Cells, Cultured↗
PubMed1982

Stimulation of prostaglandin formation by vasoactive mediators in cultured human endothelial cells.

Human endothelial cells in culture synthesize prostaglandins and release these products into the culture medium. The major products of arachidonic acid metabolism were identified by high pressure liquid chromatography or thin layer chromatography, and release of prostaglandins was measured by radioimmunoassays. Addition of histamine or bradykinin enhanced release of prostaglandins in both arterial and venous endothelial cells. Other vasoactive compounds including angiotensin II, vasopressin, substance P, epinephrine, norepinephrine, or isoproterenol were ineffective. Release of prostaglandins by histamine was concentration-related, and involved H1 receptors, as determined by addition of histamine antagonists. Incubation of endothelial cells with 14C-arachidonic acid resulted in a time-dependent uptake into cell lipids, where most of the radioactivity was incorporated into phosphatidyl choline and neutral lipids. Endothelial cells released 14C-arachidonic acid as well as 14C-prostaglandins in response to either histamine or bradykinin. The enhanced release of 14C-prostaglandins was inhibited by either indomethacin or mepacrine, but 14C-arachidonic acid release was inhibited only by mepacrine. We conclude that the vasoactive compounds, histamine and bradykinin, stimulate formation of prostaglandins in endothelial cells by the release of arachidonic acid from phospholipids of the cell membrane.

Arachidonic Acid↗
PubMed1982

Uptake and release of 14C-morphine by pulmonary endothelium and cultured pulmonary endothelial cells.

1. Isolated perfused rabbit lungs and cultured pulmonary endothelial cells take up radiolabeled [14C]morphine in proportion to the amount of labeled drug in the medium. 2. The accumulated label is readily released from the isolated lungs by perfusion with unlabeled morphine or naloxone, but not by perfusion with Krebs-Ringer solution, sucrose or thiopental. 3. Thiourea also enhances efflux of radioactivity, suggesting that the release is not related to interaction with specific opiate receptors. 4. Uptake of [14C]morphine by cultured rabbit or human endothelial cells is unaffected by morphine or naloxone, and the release of radioactivity is not enhanced by these agents. 5. None of the drugs used caused pulmonary edema in the isolated lung preparation, and they did not cause the release of lactic dehydrogenase from cultured endothelial cells. 6. It is concluded that morphine can be taken up by pulmonary endothelium, but it is probably not bound to specific receptors, and it does not injure the endothelial cells.

Animals↗
PubMed1982

Chemicals in marine and coastal environments: the need for toxicological information.

The tremendous increase in the number and amount of chemicals produced and transported in past years has resulted in increasing problems with accidental spills and uncontrolled waste sites involving these chemicals. The United States government has accordingly developed a mechanism for responding to such incidents. As part of that mechanism, the Hazardous Materials Response Project serves to coordinate scientific activities and facilitate in the gathering of scientific information needed for response to chemical spill or waste site emergencies involving coastal waters. Inevitably, much information of a toxicological nature is required to adequately evaluate potential hazards and appropriate responses. The Hazardous Materials Response Project is also able to provide a framework for significant progress in scientific understanding because it can bring together and encourage collaboration among experts in the various disciplines which are relevant to the environmental toxicological problems encountered.

Accidents↗
PubMed1981

Sulfated glycoproteins and extracellular matrix of cultured human pulmonary endothelial cells.

Endothelial cells derived from human pulmonary arteries incorporate (3H)-glucosamine and 35SO4 into glycosaminoglycans and into the carbohydrate side chains of glycoproteins. These 3H/35S-carbohydrate chains were isolated from cells and culture medium after Pronase digestion. The 3H/35S-glycosaminoglycans were separated from the 3H/35S glycopeptides by chromatography on Sephadex G-50. The distribution of cellular glycosaminoglycans and glycopeptides indicated that 30-60% of the cellular 35S-glycopeptides may be associated with the matrix components that are synthesized by the cell and attached to a plastic substratum. Human pulmonary arterial endothelial cells were grown on collagen or on a matrix derived from vascular smooth muscle cells in order to investigate how smooth muscle cell extracellular matrix components may regulate the synthesis of endothelial cell glycoconjugates. Endothelial cells grown on plastic release various proportions of the glycoconjugates they synthesize into the culture medium. However, these same cells, when grown on substratum composed of extracellular matrix materials, synthesized altered proportions of cell-associated glycosaminoglycans and reduced the levels of total glycosaminoglycans they released into the culture medium. Thus the growth of endothelial cells on a matrix of smooth muscle cell components indicates that the glycosaminoglycan materials released into the culture medium by cells grown on a plastic substratum may not be an accurate reflection of the levels or composition of extracellular matrix materials made by endothelial cells in vivo.

Cells, Cultured↗
PubMed1981

Prolylcarboxypeptidase (angiotensinase C) in human lung and cultured cells.

The activity of prolylcarboxypeptidase (PCP), or angiotensinase C, was measured in lung tissues, leukocytes, and cultured human cells using Cbz-Pro-[14C]Ala as a substrate. A lysosomal fraction of homogenized rat or human lung contained most of the PCP activity in that tissue. Polymorphonuclear neutrophils, macrophages, and lymphocytes isolated from human blood had PCP activity. Fibroblasts cultured from human tissues had the highest activity (0.56-1.15 mumol/h per 10(6) cells), more than endothelial cells cultured from human pulmonary arteries. PCP of cultured human fibroblasts was similar to the human renal enzyme because it was resistant to moderate heating and was not inhibited by p-chloromercuriphenyl sulfonic acid. These properties and the substrate specificity distinguish PCP from cathepsin A, which is also in fibroblasts. Antibody to human renal PCP reacted with fibroblast PCP in immunofluorescence, indicating common antigenic determinants. Hydrocortisone changed PCP activity in fibroblasts in parallel with changes in beta-glucuronidase activity and cell-protein concentration; the activity was depressed at low concentration of the hormone. PCP activity was also found in synovial fluid from arthritic joints and in fibroblasts from the synovium. That PCP is found in both inflammatory exudates and in cells that appear at sites of inflammation indicates that, in addition to inactivating angiotensins, this enzyme may have a role in inflammation.

Angiotensin II↗
PubMed1981

Human endothelial cell-lymphocyte interaction. Endothelial cells function as accessory cells necessary for mitogen-induced human T lymphocyte activation in vitro.

Mitogen-stimulated human T cell activation is absolutely dependent on the participation of a nonresponding accessory cell. In populations of human peripheral blood mononuclear cells, monocytes function as the requisite accessory cells. The possibility that cultured endothelial cells (EC) might also function as accessory cells was studied by examining the potential of endothelial cells to restore mitogen responsiveness to monocyte-depleted human T cells. Highly purified T cells were prepared by isolating cells rosetting with sheep erythrocytes and removing monocyte contamination by glass adherence and nylon wool column passage. When cultured at low cell density, T cells failed to respond to stimulation with various mitogenic lectins, whereas co-culture with monocytes restored responsiveness. Similarly, EC obtained from umbilical vein, pulmonary artery, and ovarian vein restored the capacity of T cells to respond to mitogens. Mitogen-stimulated T cell activation required viable endothelial cells. Moreover, effective endothelial T cell cooperation appeared to involve the establishment of cell-to-cell contact between EC and responding T cells. Accessory cell function was not a nonspecific property of all tissue culture cells as evidenced by the finding that human foreskin fibroblasts, lung fibroblasts, and HeLa cells were unable to restore responsiveness to monocyte-depleted T cells. These observations indicate that endothelial cells can support the induction of mitogen-induced T cell activation and suggest that cells lining blood vessels may play an active role in the initiation of immune responses in vivo.

Cells, Cultured↗
PubMed1980

Biotin and the sudden infant death syndrome.

A diet which is marginally deficient in the vitamin biotin may cause sudden unexpected death of young broiler chickens when they are exposed to stress. Chickens affected with this disorder have low levels of biotin in their livers. In conditions of biotin insufficiency, we postulate that a similar disorder, triggered by mild stress, may occur in the human infant. We have now used a radiochemical technique to measure the biotin content of 204 livers obtained from infants at autopsy. The levels of biotin in the livers of infants who had died of sudden infant death syndrom (SIDS; cot death) were significantly lower than those in livers of infants of similar age, who had died of explicable causes. These findings support an association of biotin with SIDS.

Animals↗
PubMed1980

Dietary polyunsaturated fats and malignant melanoma.

The consumption of polyunsaturated fat of a group of patients with malignant melanoma was compared to that of various groups of control subjects to determine whether such dietary fats predispose to the development of malignant melanoma. The results are tabulated with reference to various associated factors, and a statistical assessment of their significance is presented. The writers were unable to agree on the interpretation of the results, and present two opposing views on whether the ingestion of polyunsaturated fat is associated with the incidence of malignant melanoma.

Adipose Tissue↗
PubMed1980

Human pulmonary endothelial cells in culture. Activities of cells from arteries and cells from veins.

Endothelial cells were cultured from various different human vessels, including aortas, pulmonary, ovarian, and umbilical arteries, and pulmonary, ovarian, and umbilical veins. The cultured cells were identified as endothelial cells by the presence of Factor VIII antigen and antiotensin I converting enzyme (kininase II). They retained these markers for at least five passages in culture, and some cells had them for seven passages or more. Endothelial cells from the various vessels were compared with respect to their ability to metabolize angiotensins I and II and bradykinin. Cells from arteries had three to five times the angiotensin I converting enzyme activity as cells from veins. The activity of angiotensinase A (aspartyl aminopeptidase) had a similar distribution, and cells from arteries were consistently more active than cells from veins. Cultures of endothelial cells from pulmonary and umbilical vessels formed prostacyclin in response to mechanical stimulation. Media from cell monolayers that were subjected to a change of medium and gentle agitation inhibited aggregation of human platelets. This inhibitory activity was generated within 2-5 min, and it was not formed by cells that were treated with indomethacin or tranylcypromine. Addition of prostaglandin (PG)H(2) to indomethacin-treated cells restored the ability to form the inhibitor, but cells treated with tranylcypromine were not responsive to PGH(2). In experiments where [(14)C]arachidonic acid was added to the cells before stimulation, the major metabolite identified by thin-layer chromatography was 6-keto PGF(1alpha). Thus, it appears that pulmonary endothelial cells, as well as umbilical cord cells, can form prostacyclin. In experiments comparing the ability of arterial and venous cells to form prostacyclin, arterial cells were more active than venous cells. These studies of cells from various human vessels suggest that the vascular origin of cultured endothelial cells determines how they metabolize vasoactive peptides and form prostacyclin.

Adult↗
PubMed1980

Kinins and angiotensins. Angiotensin I converting enzyme (kininase II) in endothelial cells cultured from human pulmonary arteries and veins.

Human pulmonary endothelial cells were used to study the metabolism of angiotensin I and bradykinin by angiotensin I converting enzyme (kininase II; ACE). The endothelial cells cultured from pulmonary arteries and veins differed with respect to their enzyme activity and their surface structure, as viewed with scanning electron microscopy. Cells from adult pulmonary arteries had greater ACE activity than cells from either adult pulmonary veins or fetal pulmonary arteries. In addition, cells from adult pulmonary arteries exhibited more prominent surface projections than cells from veins or fetal pulmonary arteries. A brief exposure to trypsin decreased the ACE activity in cells from arteries but not in cells from veins. Possible the differences in ACE activity between these cells are related to their surface structures.

Adult↗