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Biomedical subjects

B Harrison

Publications and source records attributed to B Harrison.

At least 109 records · Page 6Linked to original sources
PubMed1985

Macromolecular crowding accelerates the cohesion of DNA fragments with complementary termini.

Macromolecular crowding increases the rate of nonenzymatic cohesion of the complementary ends of lambda DNA. Both lambda DNA and DNA fragments bearing the cohesive ends of lambda DNA are similarly affected. High concentrations of plasma albumin or Ficoll 70 increase the rate of cohesion by ca. 100-fold whereas high concentrations of polyethylene glycol 8000 cause greater than 2000-fold stimulation in this rate. These results have implications for the mechanism of polymer-stimulated enzymatic ligation of DNA or RNA. In addition, these crowding effects may help to explain the rapid cohesion of lambda DNA observed in vivo. An improved procedure for the recovery of DNA fragments separated by agarose gel electrophoresis is also described.

Bacteriophage lambda↗
PubMed1985

Mitomycin C and vindesine associated pulmonary toxicity with variable clinical expression.

A patient receiving mitomycin and vindesine chemotherapy for lung cancer developed abrupt onset of shortness of breath following vindesine administration. Pulmonary function tests both before and after rechallenging him with vindesine showed an acute obstructive pattern, which resolved with bronchodilator therapy; persisting lung damage was evident by arterial blood gas analysis. A record review of the 126 patients placed on the same chemotherapy regimen uncovered an additional 6 patients with possible lung toxicity. These seven patients (5.5%) had a variable clinical picture, from acute, reversible shortness of breath temporally related to vindesine administration to a progressive, fatal interstitial infiltrate. Physicians administering the combination of mitomycin and a vinca alkaloid should be aware of potential lung toxicity with variable clinical expression and be prepared to take appropriate action should they encounter it.

Antibiotics, Antineoplastic↗
PubMed1985

Schwann cell and oligodendrocyte remyelination in lysolecithin-induced lesions in irradiated rat spinal cord.

Localised irradiation of adult rat spinal cord was achieved by implanting for 2 weeks a 192Ir pin alongside vertebral segments in the thoraco-lumbar region of the spinal column. Following removal of the implant, lysolecithin (LPC) was injected directly into the dorsal columns in order to induce demyelination in the most intensely irradiated segments of spinal cord. Eight weeks after LPC injection, remyelination was much less extensive in dorsal columns which absorbed more than 40Gy than in LPC lesions in less intensely irradiated spinal cords or in unirradiated animals. No oligodendrocytes, few astrocyte processes and little myelin debris lay among the demyelinated axons. However, capillary vessels were surrounded by astroglial end-feet so that the glial-limiting membrane remained intact in the demyelinated regions. There were some oligodendrocyte remyelinated fibres around the edges of the demyelinated zones but none among the naked axons. Schwann cells, which probably migrated into the lesions from the proximal segments of the dorsal roots, provided some fibres with myelin sheaths. These remyelinated fibres abutted demyelinated axons without an intervening glial limiting membrane or astrocyte process. Oligodendrocytes may fail to migrate into the demyelinated regions because of the scarcity of astrocyte processes. A possible explanation for the limited Schwann cell remyelination may be that the presence of astroglial end-feet around capillaries deprived Schwann cells of ready access to the demyelinated regions.

Animals↗
PubMed1985

Scleroderma and pregnancy. Anaesthetic considerations.

The case of a pregnant patient with diffuse scleroderma who died following Caesarean section under general anaesthesia is presented. The patient's postoperative course was complicated by pulmonary oedema and pulmonary hypertension, sepsis, thrombocytopenia and renal failure. Aspects of the disease which possess anaesthetic implications are reviewed.

Adult↗
PubMed1984

Polymer-stimulated ligation: enhanced ligation of oligo- and polynucleotides by T4 RNA ligase in polymer solutions.

The effects of macromolecular crowding were tested on several reactions catalyzed by T4 RNA ligase. The rate of cyclization of oligoriboadenylates was stimulated up to 10-fold by relatively high concentrations of several polymers (polyethylene glycol (PEG) 8000 or 20,000; bovine plasma albumin; Ficoll 70). In addition, higher concentrations of PEG 8000 or PEG 20,000 allowed the novel formation of large linear products from the oligoriboadenylates. Also stimulated by high concentrations of PEG 8000 were the rate at which T4 RNA ligase joined p(dT)10 to oligoriboadenylates and the rate at which the enzyme activated p(dT)n by transfer of an adenylyl moiety from ATP to the oligonucleotides. These results with T4 RNA ligase are compared to earlier studies on the effects of crowding on DNA ligases.

Chemical Phenomena↗
PubMed1984

The kinetics of granulopoiesis in long-term mouse bone marrow culture. Part I.

The spontaneous stratification in long-term bone marrow cultures was illustrated and quantified. The cultures were separated into three hematopoietic layers: nonadherent cells in the supernatant medium, lightly adherent cells on top of the stromal layer, and remaining cells buried within the stromal layer. The cells of each layer were subcultured for 10 days in plastic tubes that inhibit the formation of a stromal layer. Daily samplings with absolute and differential cell counts were obtained. We identified three families of cell disappearance curves and cell types: CFU-s, hemocytoblasts, myeloblasts, and promyelocytes (G1, 2); myelocytes (G3); and postmitotic granulocytes (G4). Also, the numbers of mitotic and necrotic cells were determined. The longest half-time of CFU-s was 2.5 days. Lacking stromal support, CFU-s disappeared faster than other differentiated cells. Generally, these cells maintained their numbers for the first week of subcultures, which was attributable to a temporarily maintained balance of cell death and fresh cell production. After more than 7 days, there was a rapid decline of all differentiated cell types.

Animals↗
PubMed1984

The morphology of hematopoietic layers in long-term cultures of mouse bone marrow.

Mouse bone marrow cells in long-term culture were examined with scanning electron microscopy during the first 10 days of growth and with phase contrast microscopy during the first 4 weeks. The development of stroma and hematopoiesis was studied, and phase microscopic observation was used in order to achieve positive cell identifications with scanning EM. We analyzed those cell populations that could not be washed away from the adherent culture layer. These adherent cells in 24-hour cultures contain the full potential of hematopoietic long-term production. Stromal cells started to spread almost immediately and by 5 days had established several layers. Although in early cultures hematopoietic cells were found resting on the surfaces of stromal cells, they were later packed between stromal layers. The blast cells, especially, were usually buried under and between thin sheets of reticulum cells. The study confirms the three-dimensional nature of bone marrow in culture and points to close correspondence with bone marrow structure as studied by others in vivo.

Animals↗
PubMed1981

Serum-induced demyelination: an electrophysiological and histological study.

Serum from rabbits with EAN in the acute phase of the disease has been injected into rat sciatic nerve, and compared to control rabbit serum and serum from patients with demyelinating neuropathy and to normal human control serum. Electrophysiological studies were performed on all rat sciatic nerves so injected, and the nerve was then removed and examined histologically. Control rabbit and human serum and neuropathic human serum, when injected in a 20 microL quantity through a 30 gauge needle, did not produce significant electrophysiological abnormalities. EAN serum, however, produced significant dispersion of the muscle action potential and conduction block. All serum produced some histological evidence of demyelination but that seen with EAN serum was quite profound compared to all other sera. It is concluded that humoral factors are present within animals with EAN which has potent demyelinating potential. We were not able to demonstrate the same effect from patients with demyelinating neuropathy in this test system.

Animals↗
PubMed1980

Association of the herpes simplex-1 viral gene for thymidine kinase with the human gene for adenylate kinase-1 in biochemically transformed cells.

The herpes simplex type 1 biochemically transformed human cell line, HB-1, was fused with thymidine kinase deficient rodent cells, and 18 hybrids were isolated using the HAT-ouabain selection system. The selected enzyme, viral thymidine kinase, was present in all 18 hybrids. In 16 of 18 hybrids the viral gene for thymidine kinase cosegregated with the human gene for adenylate kinase-1 (AK-1). Thirty-six bromodeoxyuridine (BrdUrd) resistant sublines were isolated from the 16 human AK-1 positive hybrids. Each BrdUrd-resistant subline was examined for the presence of the viral TK gene by back-selection in HAT medium, and for human AK-1. In all 36 BrdUrd-resistant sublines the viral TK gene cosegregated with the human AK-1 gene. These results indicate that the transforming viral DNA fragment was associated with a specific human chromosomal region in HB-1 cells.

Adenylate Kinase↗
PubMed1980

Association of herpes simplex thymidine kinase gene with chromosome No. 18 in transformed human cells.

The herpes simplex virus type-2 (HSV-2)-transformed human cell line HB-2-3 was fused with thymidine kinase (TK)-deficient mouse cells [LM(TK-)], and 12 independent hybrids were isolated with the use of the HAT (hypoxanthine, amethopterin, and thymidine)-ouabain selection system. Discontinuous polyacrylamide gel electrophoresis studies demonstrated that the HSV-2-specific TK was the selected enzyme in the hybrids. Isoenzyme analysis and karyotyping were used in the analysis of the hybrids for the presence of human chromosomes. All 12 hybrids contained human chromosome No. 18 and the enzyme peptidase A, which is encoded by a gene on this chromosome. Hybrids were exposed to bromodeoxyuridine (BrdUrd) as a means of selection for cells that had lost HSV-2 TK activity. Isoenzyme and karyotyping data obtained from 33 BrdUrd-resistant sublines were consistent with the hypothesis that the HSV-2 TK gene is associated with chromosome No. 18 in the HB-2-3 cell line.

Animals↗
PubMed1980

Neuroticism, practice, and sex differences in a digit-symbol task.

136 university students participated in a digit-symbol coding task. An analysis of variance of sex, practice (distributed, massed), trial (1 to 10), and neuroticism (3 levels) yielded significant main effects due to trials, i.e., a learning effect, and sex (females performed better). Interactions of anxiety by trial and of anxiety by practice by trial were generally indicative of an inverse U-shaped function relating anxiety to performance under massed practice; subjects high and low in anxiety tended to perform worse than those of medium anxiety on some trials.

Anxiety↗
PubMed1979

Electron microscopy of the morphogenesis of Bacillus subtilis bacteriophage SP3.

The capsid of Bacillus subtilis bacteriophage SP3 is assembled via a prohead intermediate which subsequently encapsulates DNA and attaches a tail. The prohead contains a ring-like core structure. The spokes which extend from the core to the inner prohead surface are thought to form a scaffold for the polymerization of the prohead. Ninety percent of the proheads are assembled prior to the onset of DNA encapsulation. The first mature phage particles are observed at 45 min after infection; titres of intracellular phage demonstrate their infectivity. The core is visible in phage ghosts.

Bacillus subtilis↗