Biomedical subjects

C J Jackson

Publications and source records attributed to C J Jackson.

54 records · Page 3Linked to original sources

PubMed1991

Isolation and purification of microvascular endothelium from human decidual tissue in the late phase of pregnancy.

Normal pregnancy demands significant structural and physiologic adaptations of the uterine microvasculature, to facilitate adequate placentation. In pregnancies complicated by pregnancy-associated hypertension (preeclampsia), this process is defective, resulting in a high incidence of intrauterine growth retardation. The microvascular endothelium, a focal point for both initiation and inhibition of coagulation and control of vascular tone, may well contribute to development and aggravation of these abnormalities. We describe a method for isolation, purification, and culture of human decidual endothelial cells from biopsies performed at the time of cesarean section. The separation procedure is technically simple, requires only a small piece of tissue, and takes approximately 2 hours to perform. Some of the unique features of these cells in culture are outlined. This technique will permit the close examination of various aspects of the function of these cells in normal pregnancy, and their comparison with cells from pregnancies complicated by hypertension.

Cell Division↗

PubMed1991

Type I collagen fibrils promote rapid vascular tube formation upon contact with the apical side of cultured endothelium.

Extracellular matrix (ECM) components phenotypically modulate cultured endothelium. This paper examined the ability of ECM components to promote tube formation in vitro. When collagen type I was added to the culture medium of confluent neonatal foreskin or human umbilical vein endothelium at 10-100 micrograms/ml tube-like structures formed rapidly. Tube formation did not occur with the addition of other ECM components at similar concentrations. Electron microscopy revealed that the lumen of the tubes consisted of collagen fibrils, with the surrounding cells having typical endothelial junctional complexes. These findings demonstrate that when collagen fibrils make contact with the apical side of endothelium they act as a stimulus and provide a template for vascular tube formation.

Collagen↗

PubMed1991

Biosynthesis and characterization of glucuronide metabolites of fluphenazine: 7-hydroxyfluphenazine glucuronide and fluphenazine glucuronide.

1. To expedite direct studies on phase II metabolites of fluphenazine, pure fluphenazine or 7-hydroxyfluphenazine were incubated with a rabbit hepatic microsomal immobilized enzyme system. After purification and recrystallization a high yield (60%) of 7-hydroxy-beta-D-O-glucuronyl-fluphenazine was obtained. 2. The structure of this glucuronide was proven unambiguously by mass spectrometry (fast atom bombardment, daughter ion analysis, electron impact, chemical ionization) and 1H-n.m.r. and 13C-n.m.r. spectroscopy. The phenolic ether glucuronide was the sole product of the reaction. 3. There was no evidence of conjugation at the primary alcohol group of the side-chain of fluphenazine, or of the formation of quaternary ammonium-linked glucuronides with either of tertiary aliphatic nitrogen atoms of the side-chain. 4. Incubation of fluphenazine with the immobilized enzyme system gave a poor yield (less than 1%) of the aliphatic ether glucuronide as reaction product, consistent with a low susceptibility of the side-chain primary alcohol function of fluphenazine to glucuronidation.

Animals↗

PubMed1990

Binding of human endothelium to Ulex europaeus I-coated Dynabeads: application to the isolation of microvascular endothelium.

A major problem encountered when isolating human microvascular endothelium is the presence of contaminating cells such as fibroblasts that rapidly over-grow the endothelial cells. We describe here a simple, rapid technique for purifying endothelial cells derived from the microvasculature of neonatal foreskin and osteoarthritic and rheumatoid arthritic synovium. This technique is based on the selective binding of the lectin Ulex europaeus I (UEA I) to the endothelial cell surface via fucose residues. Initially UEA I was covalently bound to tosyl-activated super-paramagnetic polystyrene beads (Dynabeads) by incubation for 24 h at room temperature. Cells were isolated by extracting microvascular segments from enzyme-treated (trypsin and Pronase) cubes of tissue. The mixed population of cells obtained were purified by incubating them at 4 degrees C for 10 min with the UEA I-coated Dynabeads. Endothelium bound to the beads whilst contaminating cells were removed by five washes with HBSS using a magnetic particle concentrator. The endothelial cells thus obtained grew to confluence as a cobblestone-like monolayer and expressed von Willebrand factor antigen. The cells were released from the Dynabeads by the competitive binding of fucose (10 min at 4 degrees C). This new method is simple and reproducible and allows pure human microvascular endothelial cells to be cultured within 2 h of obtaining a specimen.

Cell Line↗

PubMed1989

Down-regulation of secondary in vitro antibody responses by suppressor T cells of mice treated with a tolerogenic conjugate of ovalbumin and monomethoxypolyethylene glycol, OVA(mPEG)13.

In previous studies from this laboratory it was shown that OVA(mPEG)n conjugates induced: (i) tolerance in mice with respect to IgG and IgE antibody responses to dinitrophenylated OVA (DNP-OVA); and (ii) OVA-specific suppressor T (Ts) cells which could down-regulate a primary immune response in vivo. For the present study, we have developed an in vitro culture system for assessing the activity of Ts cells of mice tolerized by an OVA(mPEG)13 conjugate. Spleen cells from mice which had been primed with DNP4-OVA in Al(OH)3 gel were cultured with DNP4-OVA to induce a secondary antibody response in vitro. After 6 days, cells secreting anti-DNP antibodies of the IgG1 class were enumerated by an immunoenzymatic plaque-forming cell assay. Addition to the culture of T cells from mice treated with 3 i.p. injections of 500 micrograms of OVA(mPEG)13 resulted in a 29-61% reduction in the number of IgG1 anti-DNP antibody-forming cells, in comparison with the effect of T cells from mice treated with PBS. It was concluded that this tolerogenic conjugate induced splenic Ts cells which were capable of suppressing secondary in vitro anti-DNP responses.

Animals↗

PubMed1989

Isolation and propagation of endothelial cells derived from rheumatoid synovial microvasculature.

Synovial angiogenesis may play an important part in the destruction of articular cartilage in patients with rheumatoid arthritis (RA). As an important first step towards developing in vitro models of synovial angiogenesis, microvascular endothelial cells have been isolated, purified, and cultured from operative synovial specimens obtained from adult patients with RA.

Arthritis, Rheumatoid↗

PubMed1989

A new comprehensive anaesthetic record.

Eternal vigilance and strict attention to detail are the 'sine qua non' of safe anaesthesia with the contemporaneous anaesthetic record being the documentation. As an alternative to the manifold and often inadequate forms currently in use, a new rapidly completed anaesthetic record incorporating a comprehensive checklist is presented. Guidelines of the Faculty of Anaesthetists, Royal Australasian College of Surgeons are met. It is argued that the chart improves safety not only by its direction to attention during the peroperative visit and equipment check, but also by its demand for the ongoing attention of the anaesthetist. Reservations are expressed about 'black box' recording by trend printout and a perspective for computerised and automated anaesthetic records is also discussed.

Anesthesia Recovery Period↗

PubMed1987

Synthesis, isolation, and characterization of conjugates of ovalbumin with monomethoxypolyethylene glycol using cyanuric chloride as the coupling agent.

The experimental conditions for the preparation of conjugates of ovalbumin (OA) and monomethoxypolyethylene glycol (mPEG) of a preselected average degree of conjugation, n, using cyanuric chloride as the coupling agent, have been investigated with emphasis on purification and characterization of the products. These conjugates served as prototypes of tolerogenic mPEG derivatives of antigenic proteins which were capable of suppressing in mammals the immunological response to the corresponding unmodified antigens. In other studies in this laboratory, the tolerogenicity of OA(mPEG)n conjugates was found to be a function of n. The reproducibility of the reaction leading to the production of OA(mPEG)n conjugates was shown to depend primarily on the reactivity of the mPEG-cyanuric chloride intermediate, which--for best results--had to be synthesized under completely anhydrous conditions. Isolation of the OA(mPEG)n conjugates was optimized by the use of ion-exchange chromatography whereby rapid removal of large amounts of uncoupled intermediate from the conjugate was achieved; the conditions of fractionation were affected by the degree of conjugation. This method of purification was superior to dialysis, ultrafiltration, and gel filtration. Furthermore, by the application of analytical hydrophobic interaction HPLC it was possible to differentiate among conjugates of different degrees of conjugation and to establish the absence of any detectable free OA in any of the preparations. The quantity of mPEG in the conjugates was determined directly by NMR.

Chemical Phenomena↗

PubMed1987

Tolerance induction in mice by conjugates of monoclonal immunoglobulins and monomethoxypolyethylene glycol. Transfer of tolerance by T cells and by T cell extracts.

The specific tolerance induced in mice by conjugates of human monoclonal IgG (HIgG) with monomethoxypolyethylene glycol (mPEG) was transferred to normal mice by spleen cells or a surface immunoglobulin negative (sIg-) Lyt-2+ subpopulation of these cells. Although transferable tolerance was demonstrable 6 to 14 days after treatment of the cell donors with tolerogen, the state of tolerance persisted in the treated mice for at least 43 days. Moreover, an extract prepared by freezing and thawing of the sIg- spleen cells obtained from mice 6 days after treatment with HIgG(mPEG)20 was capable of reducing (greater than 85%) the immune response of normal mice to heat aggregated HIgG. On the basis of these results, it is suggested that similar tolerogenic mPEG derivatives of xenogeneic monoclonal immunoglobulins (XIg) may prove to be useful therapeutic agents in man when administered before treatment with the unmodified XIg.

Animals↗

PubMed1987

Induction of in vivo helper activity for murine antibody responses by macrophages pulsed with ovalbumin-monomethoxypolyethylene glycol (OA-mPEG) conjugates.

Conjugates of protein antigens with an optimal number of monomethoxypolyethylene glycol (mPEG) chains of an appropriate molecular weight had been shown to suppress murine IgE responses to the unmodified antigen. To investigate the possibility that the tolerogenic capacity of these mPEG conjugates is attributable to a defect in macrophage (M phi) presentation of their antigenic determinants, the activity of ovalbumin (OA)-mPEG conjugates when pulsed onto mouse peritoneal adherent cells (M phi) was compared in this study with their activity in solution. Surprisingly, in contrast to the suppressogenic capacity of mPEG conjugates in solution, the OA-mPEG pulsed M phi appeared to exert a helper effect when injected intraperitoneally (ip), i.e., after subsequent immunization with dinitrophenylated OA (DNP3-OA) in Al(OH)3, the mice showed accelerated IgE and IgG1 antibody responses to OA and DNP. However, when M phi were exposed to limiting concentrations of OA or OA-mPEG, markedly higher concentrations of OA-mPEG were required to yield pulsed M phi, exerting a significant helper effect. It was concluded that although M phi were capable of presenting the OA determinants of OA-mPEG conjugates to helper T (Th) cells, the preparations of modified antigen were presented less effectively than native OA.

Animals↗

PubMed1987

Tolerogenic polyethylene glycol derivatives of xenogeneic monoclonal immunoglobulins.

It is becoming apparent that the effectiveness of xenogeneic monoclonal antibodies (XIg), which are increasingly used for diverse therapeutic purposes in man, may be counteracted by their inherent immunogenicity. Since conjugates of proteins with monomethoxypolyethylene glycol (mPEG) have proved to be effective tolerogens in other systems, we have used an experimental model in mice to explore the tolerogenicity of mPEG conjugates of a human monoclonal IgG (HIgG), i.e. a myeloma protein. Administration of these conjugates prior to immunization with heat aggregated HIgG (ha-HIgG) resulted in specific tolerance, as manifested by a marked reduction in the level of antibodies to HIgG, which was related to the degree of conjugation and the dose of conjugate administered. Thus, administration of HIgG(mPEG)20 6 to 43 days prior to immunization with ha-HIgG resulted in an inhibition of anti-HIgG antibody formation of the order of 85-90%, in relation to the titres of mice receiving PBS in lieu of HIgG(mPEG)20; these results hold the promise that mPEG conjugates of XIg may prove therapeutically useful in man in relation to organ transplantation, localization of tumours by immuno-imaging and tumour destruction by immunotoxins.

Animals↗

PubMed1987

A canine model for the study of hapten-specific suppression of IgE-mediated bronchoconstriction and anaphylaxis.

Newborn mongrel dogs were sensitized with conjugates of ovalbumin (OA) and 2,4-dinitrophenol (OA-DNP3) in the presence of Al(OH)3 to produce high levels of anti-OA and anti-DNP IgE antibody. At 4-6 months of age, when anti-DNP and anti-OA antibody levels reached titers of 64 by passive cutaneous anaphylaxis, the dogs underwent separate inhalation and intravenous challenges with conjugates of DNP and bovine gamma globulin (DNP15-BGG) and OA. Inhalation challenge with DNP15-BGG and OA resulted in 5- and 10-fold increases in airflow resistance, respectively. Intravenous challenge with either DNP15-BGG or OA produced profound anaphylaxis with 60-80% decreases in blood pressure, cardiac output and regional blood flows in the carotid, superior mesenteric and renal arteries, and the distal aorta. Treatment of sensitized dogs with 5 doses of 20 mg of conjugates of DNP and polyvinyl alcohol (DNP2-PVA) on alternate days resulted in suppression of anti-DNP IgE antibody production; abrogation of established airway and vascular anaphylactic sensitivities; no change in regional blood flows, and no effect on sensitivities to challenge with OA.

2,4-Dinitrophenol↗

PubMed1982