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Biomedical subjects

J Reglinski

Publications and source records attributed to J Reglinski.

17 recordsLinked to original sources
PubMed1992

Studies of oxidative stress in cellular systems. The interaction of monocytes and erythrocytes.

1H spin echo NMR spectroscopy is used to follow the interaction of intact and viable erythrocytes and monocytes obtained from different sources in mixed cultures. After a lag time (270 min) erythrocyte glutathione is observed to become more oxidised. This result is believed to occur as a consequence of monocyte activation generating hydrogen peroxide or hypochlorous acid, which is targeted at the erythrocyte. The red cell in turn employs its sulphydryl system as an anti-oxidant defence.

Erythrocytes↗
PubMed1992

Clinical analysis by 1H spin-echo NMR. 2. Oxidation of intracellular glutathione as a consequence of penicillamine therapy in rheumatoid arthritis.

Spin echo NMR analysis is used to monitor the effect of penicillamine on intact erythrocytes obtained from patients suffering from rheumatoid arthritis during a 12-week period of therapy. The results are compared to the previously reported in vitro effects of the compound (McKay, C. N. N.; et al. Biochim. Biophys. Acta 1986, 888, 30-35). At clinical assessment at week 12, the 20 patients were divided into responder and nonresponder groups. The intracellular glutathione in the responder group is more oxidized (P less than 0.01) than in the nonresponder group. A retrospective analysis of the two patient groups at the initial assessment following the commencement of therapy indicated that in the nonresponder group intracellular glutathione was significantly more reduced (P less than 0.02) than in the responder group. It is postulated that penicillamine stimulates cellular defense against the oxidation of the cell membrane at the expense of cytosolic glutathione. This initial study suggests that spin-echo NMR analysis of erythrocyte glutathione can act as an early indicator of a clinical response to penicillamine therapy.

Arthritis, Rheumatoid↗
PubMed1992

Direct spectroscopic determination of functional sulphydryl groups on intact cell surfaces by surface-enhanced resonance Raman scattering.

Semi-quantitative and direct determination of labelled sulphydryl groups on the surface of intact erythrocytes has been accomplished for the first time with surface-enhanced resonance Raman scattering (SERRS). The method, which involves the use of citrate-reduced silver colloids, is sensitive and selective. A 10(-8) M effective concentration of picomole quantities of sulphydryl groups was determined in the presence of the normally overwhelming signal from haemoglobin. This seminal study suggests that SERRS may be applied to other in situ, site-directed labelling experiments.

Cell Membrane↗
PubMed1992

Spin echo nuclear magnetic resonance studies on intact erythrocytes: changes in cellular metabolism as a consequence of carbimazole therapy.

OBJECTIVE: Because the exact mechanism of action of carbimazole is uncertain, nuclear magnetic resonance (NMR) spectroscopy was used to investigate cellular changes in erythrocytes from Graves' patients following a course of carbimazole therapy. DESIGN: NMR spectroscopy was carried out using intact erythrocytes obtained from Graves' patients prior to and at 2 and 12 months after carbimazole treatment. The data were correlated with thyroid hormone and antibody levels. PATIENTS: Twenty patients (four males; 16 females) with newly diagnosed and previously untreated Graves' disease were enrolled into the study. Assessments were made prior to the commencement of therapy and after 2 and 12 months on treatment. Of the 20 patients assessed at 0 and 2 months only 12 completed the study. MEASUREMENTS: The oxidation-reduction balance of erythrocyte glutathione was measured directly using 1H spin echo NMR spectroscopy of intact cells. Thyroid hormone and antibody levels were measured using reported methods. RESULTS: At 2 and 12 months a significant (P < 0.01) oxidation of the erythrocyte glutathione was observed. Of the four thyroid related markers (T3, T4, TRAb and TSH) assessed in this study both T3 (P < 0.001) and TRAb (P < 0.001) were observed to correlate with the NMR observed changes in glutathione. However, in-vitro experiments indicated that carbimazole does not affect red cell glutathione directly. CONCLUSIONS: A model is presented which uses the hydrated iodium cation (I+), the natural product of T4 conversion to T3, as a chemical oxidant which can produce the observed clinical alteration in intracellular glutathione in ex-vivo erythrocytes. It is suggested that a major factor in the action of carbimazole in Graves' disease may be to stimulate the function of the deiodinase enzymes.

Adult↗
PubMed1992

Action of sodium aurothiomalate on erythrocyte membrane.

The number of sulphydryl groups on the erythrocyte membrane has been assessed as a function of nutritional status for two groups of patients, one receiving non-steroidal anti-inflammatory drugs (NSAIDs) and the other receiving sodium aurothiomalate (Myocrisin). The patients receiving NSAIDs had a significantly higher number of sulphydryl groups in both the glucose depleted and glucose activated states than the patients receiving sodium aurothiomalate. The study focuses on the hexose transport protein where there is a specific binding site for gold using the two sulphydryl residues on helices 11 and 12 of the protein. The data suggest that the strong binding of gold to the erythrocyte membrane occurs via thiol pairs rather than by isolated sulphydryl groups and that there are possibly two further binding sites for gold on the membrane, the identities of which are still unclear.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1991

Clinical analysis in intact erythrocytes using 1H spin echo NMR.

A new method of clinical analysis based on 1H spin echo NMR spectroscopy is presented. It is capable of providing information on six metabolites within viable erythrocytes, directly and without any preparative procedures prior to analysis except for cell separation and washing. Erythrocytes from patients with rheumatoid arthritis and Graves' disease are compared with cells obtained from healthy volunteers. The NMR detectable species in the cytosol of the cells are glutathione, ergothioneine, choline, creatine, glycine, lactate and to a lesser extent alanine and valine. Significant differences are observed between the ergothioneine pools in the rheumatoid group (P less than 0.01) compared to the control group. The glutathione: di-glutathione ratio can be assessed from the ratio, g2 to g4, taken from different signals in the glutathione molecule. The total concentration of glutathione present is easily assessed qualitatively but is more difficult to quantitate.

Adult↗
PubMed1990

The effect of doxorubicin on the glutathione content and viability of cultured human lung cancer cell lines A549 and GLC4 210.

Glutathione was measured in doxorubicin-sensitive cells from small cell carcinoma of lung (GLC4 210), and the levels compared with those of cells with acquired resistance and a line of resistant non-small-cell adenocarcinoma A549 (Alveolar type 2). The effect of different doxorubicin concentrations on glutathione were measured by HPLC. The effect of doxorubicin on the viability of the cell lines was studied using thiazole blue dye reduction. An increase in A549 sensitivity to doxorubicin was produced using buthionine-S,R-sulfoximine at a non-toxic dose.

Adenocarcinoma↗
PubMed1990

An NMR compatible model for solid tumour.

An NMR model for the study of drug interactions with solid tumour is described. It is based on the use of packed cells in a simple medium. The system is capable of dealing with cellular biochemistry at a molecular level through experiments conducted in a homogeneous field by 1H spin-echo NMR spectroscopy. However, through a simple imaging technique, it is also possible to introduce a spatial element into the chemistry of the packed cells. The use of these complementary NMR methods are illustrated by the action of the cytotoxic agent doxorubicin on cellular glycolysis. A pattern of signals observed in a homogeneous field experiment following oxidative stress are duplicated in the imaging experiment to illustrate the toxins' ability to penetrate the model tumour.

Antineoplastic Agents↗
PubMed1988

Cellular response to oxidative stress at sulfhydryl group receptor sites on the erythrocyte membrane.

Ellman's reagent was used to induce an oxidative stimulus on the exofacial membrane sulfhydryl groups of the human erythrocyte. Thiol-disulfide exchange occurring extracellularly was monitored using resonance Raman spectroscopy, and intracellular changes were observed by 1H spin echo nuclear magnetic resonance spectroscopy of the intact cell. The stimulus caused oxidation and depletion of the glutathione pool, which was followed at higher concentrations of Ellman's reagent by a depletion of intracellular ergothioneine levels. Larger changes are induced intracellularly than would be expected from the stoichiometry of the reaction at the exofacial surface. A mechanism is proposed which links exofacial sulfhydryl receptor sites via the transport proteins to spectrin and glutathione. The consequences for the cellular redox balance of an extracellular stimulus of this type are discussed.

Blood Glucose↗
PubMed1988

Doxorubicin-induced altered glycolytic patterns in the leukemic cell studied by proton spin echo NMR.

1H spin echo NMR of the leukemic cell line J-lll is reported. Phosphorylcholine, phosphorylcreatine, lactate and mobile triglyceride are identified as constituents of the cytosolic pool in the intact and viable cells. The concentration of cells in the NMR tube is high (approx. 10(9) in 0.4 ml) and as a result the available oxygen is restricted, making the NMR experiment a plausible in vitro tumour model in which kinetics in the living cell can be probed in a non-invasive manner. Treatment with pharmacological concentrations of the drug doxorubicin produced immediate enhanced anaerobic glycolysis and eventual cell death.

Doxorubicin↗
PubMed1988

Spin-echo 1H NMR detected response of ergothioneine to oxidative stress in the intact human erythrocyte.

Human erythrocytes were subjected to oxidative stress using arsenicals. The study is a model for thiol-related redox processes observed in the etiology of diseases such as rheumatoid arthritis. Spin-echo NMR spectroscopy of the living cell was used to monitor the cellular biochemistry. Oxidation of glutathione and the first demonstrated response of ergothioneine to a chemical stimulus in a cell were observed. The reversible nature of the ergothioneine response is interpreted as an environmental rather than a chemical change.

Arthritis, Rheumatoid↗
PubMed1988

The use of 1H spin echo NMR and HPLC to confirm doxorubicin induced depletion of glutathione in the intact HeLa cell.

The effects of doxorubicin on the cellular biochemistry of the HeLa cell using 1H spin echo nuclear magnetic resonance spectroscopy (NMR) of the intact and viable cell in conjunction with dual wavelength HPLC of cell lysates is reported. Directly dose-related changes were observed in lactate and reduced glutathione concentration. Doxorubicin induces a time-dependent depletion of the cytosolic pool of glutathione and a change in the glycolytic pattern of the cell. The glutathione depletion could be partially reversed by controlled pre-treatment of the cells with N-acetylcysteine and cysteine, the protection being linked to the intracellular concentration of the thiol.

Acetylcysteine↗
PubMed1987

A 1H spin echo NMR study of the HeLa tumour cell.

Phosphorylcholine, phosphorylcreatine, lactate, glutathione, glycine and leucine were identified in living HeLa cells in the first study of this cell type by 1H spin echo NMR spectroscopy. The technique has the advantage that it is non-invasive, providing detailed structural information on individual species present in the cell matrix. It has been used in this case to study the rate of energy consumption following the activation of the glycolytic pathway with glucose.

Energy Metabolism↗
PubMed1986

Changes in glutathione in intact erythrocytes during incubation with penicillamine as detected by 1H spin-echo NMR spectroscopy.

1H spin-echo NMR spectroscopy was used to study changes in glutathione status in intact erythrocytes. The concentration of glutathione in suspensions of erythrocytes in 2H2O saline is significantly different in cells from patients with rheumatoid arthritis than in controls from normal healthy volunteers. It is observed that the methods of separation and suspension affect lactate metabolism in red cells. Incubation of erythrocytes with solutions of the therapeutic agent D-penicillamine in 2H2O saline produced a change in glutathione resonances which is indicative of an increase in diglutathione concentration. Signals from the methyl groups of penicillamine decreased at a commensurate rate. Incubation of normal cells with plasma from patients with rheumatoid arthritis who had the same blood group as the normal volunteer indicated a much larger fall in glutathione signal with plasma from a patient treated with penicillamine than from a patient on non-steroidal anti-inflammatories.

Anti-Inflammatory Agents↗