Biomedical subjects

J S Anderson

Publications and source records attributed to J S Anderson.

At least 55 records · Page 3Linked to original sources

PubMed1987

In vitro endothelialization of small-caliber vascular grafts.

To establish the conditions for achieving immediate and complete endothelial cell coverage of the luminal surfaces of small-caliber (internal diameter:4 mm) vascular grafts in vitro, the attachment and spread of endothelial cells cultured from human umbilical veins to expanded polytetrafluoroethylene (PTFE) and knitted Dacron grafts was studied. Cell number was quantified by fluorescent measurements of deoxyribonucleic acid. The completeness of cell coverage and cell junction formation were assessed by means of both scanning and transmission electron microscopy. Cell attachment was compared after expanded PTFE or knitted Dacron grafts were precoated with gelatin, laminin, fibronectin, fibrin, or collagen, singly or in combination. Saturation cell attachment of 3.5 +/- 0.7 X 10(5) cm-2 was completed within 15 minutes when (1) type I collagen was used to form the substrate matrix, (2) human umbilical vein endothelial cells were suspended in phosphate-buffered saline solution supplemented with calcium and magnesium, and (3) the suspended cell number was greater than or equal to 5 X 10(5). In contrast, attachment to untreated or laminin-treated surfaces was 1.3 +/- 0.33 X 10(5) cells cm-2 and attachment to fibrin- or fibronectin-treated surfaces was 2.8 +/- 0.47 and 2.4 +/- 1.1 cells X 10(5) cm-2, respectively. However, to produce a confluent flow surface, the attached cells required several hours in culture medium to spread completely. Maintenance of confluent cell coverage on the graft surface for 3 days in vitro was achieved by means of continuous perfusion with oxygenated tissue culture medium RPMI-1640-HEPES supplemented with 20% fetal bovine serum. We conclude that optimum immediate confluent endothelial coverage of small-caliber vascular grafts requires a high concentration of cells, attachment to collagen-precoated grafts, and several hours of incubation in complete culture medium.

Blood Vessel Prosthesis↗

PubMed1985

Ultrasonographic findings in acute acalculous cholecystitis.

Acute acalculous cholecystitis (AAC) is usually seen as a complication of major surgery or trauma. Although this entity is well-known in the surgical literature, little has been written about it in the radiologic literature. A review of patient records from 1975 through 1982 revealed 16 patients with pathologically confirmed AAC on whom at least 1 sonographic study had been performed. Thickening of the gallbladder wall, a subserosal "halo" of edema, pericholecystic abscess, and marked gallbladder distention were consistent findings in AAC. In the proper clinical setting, these otherwise nonspecific findings allow a prompt and accurate diagnosis.

Acute Disease↗

PubMed1984

Characterization of three intermediates in the biosynthesis of teichuronic acid of Micrococcus luteus.

Teichuronic acid, the Micrococcus luteus cell wall polysaccharide which consists of D-glucose and N-acetyl-D-mannosaminuronic acid, is synthesized in vitro from uridine diphosphate N-acetyl-D-glucosamine, uridine diphosphate N-acetyl-D-mannosaminuronic acid, and uridine diphosphate D-glucose in a series of reactions catalyzed by a particulate enzyme preparation. Several lipid-linked intermediates are formed, of which the first three are called components A, B, and C. The formation of these intermediates is inhibited by tunicamycin. The lipid moiety of the intermediates is approximately 95% undecaprenol and 5% dodecaprenol as determined by mass spectrometry. The oligosaccharide moieties of components B and C are the disaccharide, N-acetyl-D-mannosaminuronyl-(1,3)-N-acetyl-D-glucosamine, and the trisaccharide, N-acetyl-D-mannosaminuronyl-(1,4)-N-acetyl-D-mannosaminuronyl++ +-(1, 3)-N-acetyl-D-glucosamine, respectively, as determined by the complete degradation of the former and partial degradation of the latter by the alkaline beta-elimination reaction. The saccharide and lipid moieties of the intermediates are linked through pyrophosphate. Thus, component A is P1-N-acetyl-alpha-D-glucosaminyl P2-undecaprenyl diphosphate, component B is P1-N-acetyl-D-mannosaminuronyl-(1, 3)-N-acetyl-alpha-D-glucosaminyl P2-undecaprenyl diphosphate, and component C is P1-N-acetyl-D-mannosaminuronyl-(1,4)-N-acetyl-D-mannosaminurony l-(1, 3)-N-acetyl-alpha-D-glucosaminyl P2-undecaprenyl diphosphate.

Chemical Phenomena↗

PubMed1982

Elongation of teichuronic acid chains by a wall-membrane preparation from Micrococcus luteus.

A wall-plus-membrane preparation from Micrococcus luteus catalyzes the incorporation of [14C]glucose from UDP-[14C]glucose, into two fractions of teichuronic acid, which is the cell wall polysaccharide consisting of alternating residues of glucose and N-acetylmannosaminuronic acid (ManNAcUA). Membrane-associated teichuronic acid was extracted from the wall-membrane fraction of reaction mixtures by sodium dodecyl sulfate. The synthesis of membrane-associated teichuronic acid required UDP-glucose, UDP-ManNAcUA, and UDP-N-acetylglucosamine and was inhibited by tunicamycin. Glucose incorporated into wall-bound teichuronic acid remained in wall fragments after extraction with sodium dodecyl sulfate, and its incorporation required UDP-glucose and UDP-ManNAcUA (but not UDP-N-acetylglucosamine) and was insensitive to tunicamycin. Radioactive material incorporated into wall-bound teichuronic acid could be released by treatment with mild acid or by digestion with lysozyme, indicating that the wall-bound teichuronic acid was covalently linked to peptidoglycan. There were about 600 pmol of wall-bound teichuronic acid acceptor sites for glucose per mg of protein as measured in incorporation reaction mixtures lacking UDP-ManNAcUA. In the presence of both UDP-glucose and UDP-ManNAcUA, elongation of teichuronic acid acceptor sites occurred, with the addition of six to eight disaccharide units to each acceptor site.

Adenosine Triphosphate↗

PubMed1981

Carbon-13 nuclear magnetic resonance spectroscopic study of teichuronic acid from Micrococcus luteus cell walls. Comparison of the polysaccharide isolated from cells with that synthesized in vitro.

Teichuronic acid isolated from the cell walls of Micrococcus luteus has been examined by natural-abundance (13)C NMR spectroscopy. Proton-decoupled and proton-coupled spectra were obtained for native teichuronic acid and also after the teichuronic acid had been oxidized with periodate and reduced with borohydride. The spectra are consistent with the structure [ManNAcUAp-( beta -1,6)-G1cp-( alpha -1,4)]n. Teichuronic acid synthesized in vitro from suitable substrates by the particulate enzyme fraction obtained from M. luteus yielded a (13)C NMR spectrum which is indistinguishable from that of the native teichuronic acid, indicating a structural identity of the teichuronic acid synthesized in vitro with that isolated from cell walls.

Cell Wall↗

PubMed1978

Membrane-bound nucleotidase of Bacillus cereus.

A membrane-bound nucleotidase of Bacillus cereus T was solubilized by digestion with trypsin and subsequently purified more than 300-fold. The purified nucleotidase was most active on ribonucleoside 5'-monophosphates and was slightly less active (40 to 60%) on deoxyribonucleoside 5'-monophosphates and ribonucleoside 3'-monophosphates. In addition to hydrolytic activity, the nucleotidase preparation possessed phosphotransferase activity by which phosphate is transferred from a phosphate donor to the 5' position of nucleosides.

Bacillus cereus↗

PubMed1977

Initial reactions in biosynthesis of teichuronic acid of Micrococcus lysodeikticus cell walls.

The in vitro biosynthesis of teichuronic acid, the cell wall polysaccharide of Micrococcus lysodeikticus, occurs in two stages. In the initial stage, the particulate enzyme fraction utilizes uridine diphosphate N-acetylglucosamine (UDP-GlcNAc) and uridine diphosphate N-acetylmannosaminuronic acid (UDP-ManNAcUA) to form three intermediates. N-Acetylglucosamine is transferred from UDP-GlcNAc to a carrier lipid present in the particulate enzyme fraction to form the first intermediate, GlcNAc carrier lipid. N-Acetylmannosaminuronic acid is then transferred from UDP-ManNAcUA to the GlcNAc carrier lipid to form ManNAcUA-GlcNAc carrier lipid, the second intermediate. Finally, the transfer of an additional N-acetylmannosaminuronic acid residue from UDP-ManNAcUA yields the third intermediate, (ManNAcUA)2-GlcNAc carrier lipid. Reactions involving UDP-ManNAcUA release uridine diphosphate. Concomitant synthesis of peptidoglycan or membrane mannan inhibits the synthesis of the teichuronic acid intermediates, thereby providing indirect evidence that the carrier lipid is undecaprenol monophosphate.

Cell Wall↗

PubMed1977