Biomedical subjects
Publications and source records attributed to D Rae.
The discovery of Org 24598, one of the first potent and selective inhibitors of the glycine transporter is discussed. In vitro structure-activity relationships (SARs) data for interaction of a ligand with this system is discussed.
This study compared gradient gel electrophoresis (GGE) and light-scattering (LS) methods of determining low density lipoprotein (LDL) particle size. LDL was isolated from 27 fasting subjects. Peak particle size was determined by GGE on 3-13% gradient gels (Gradipore, Sydney, Australia) and by LS using a Zetasizer 3000 (Malvern Instruments, Malvern, UK). Repeated measurements on a single specimen indicated a coefficient of variation (CV) of 0.3%. A correlation was noted (P < 0.0001; r = 0.78) when comparing LDL particle size determined by LS methodology and GGE. Particle diameter results obtained by LS were smaller than those obtained by GGE (23.1 +/- 0.1 vs. 26.1 +/- 0.1 nm; P < 0.0001). LDL particle size determined by LS methodology correlated inversely with the log of triglyceride level (P < 0.0001; r = -0.77) and positively with high density lipoprotein (HDL) cholesterol level (P < 0.002; r = 0.57).
Using an assay for measurement of released type 1-prophospholipase A2 (type 1-proPLA2) propeptides (PROP assay), we have shown that human granulocytes, but not lymphocytes or macrophages, abundantly express this 'pancreatic' type 1-proPLA2 zymogen. Stimulation with tumour necrosis factor-alpha (TNF-alpha) and other cytokines results in the immediate release from granulocytes of a mixture of free propeptides and type 1-proPLA2 precursor. We also found that granulocytes contain an approximately 29 kDa trypsin-like endogenous type 1-proPLA2 activator. PROP assay and TAP (trypsinogen activation peptide) assay of plasma samples accurately predicts the segregation of acute pancreatitis into three clearly defined categories of severity--mild, intermediate and severe--at the time of first hospital admission and over the next few hours of observation. Mild and intermediate pancreatitis are associated with a degree of granulocyte stimulation limited to the release of the unactivated type 1-proPLA2 precursor. Progression to severe disease is accompanied by the activation of granulocyte type 1-proPLA2, apparently carried to completion. This identifies the approximately 29 kDa endogenous activator of type 1-proPLA2 in granulocytes as a critical mediator at a threshold stage in acute pancreatitis, which marks the transition from uncomplicated pancreatitis to the potentially lethal disease. Specific inhibitors of this key regulatory enzyme modelled on the P3-P1 domain of the type 1-proPLA2 activation peptide would seem to be promising candidates for a new class of chemotherapeutic agents.
This study examined factors influencing the particle diameter of Lp[a]-, the low density lipoprotein (LDL)-like moiety of Lp[a], in 26 subjects chosen to provide a range of Lp[a] and triglyceride levels. Lp[a] and LDL fractions were isolated by vertical density ultracentrifugation. Lp[a] was further purified using a lysine-Sepharose affinity column and Lp[a]- obtained by incubating Lp[a] with dithiothreitol. Lp[a], LDL, and Lp[a]- fractions were run on 3-13% gradient gels to determine particle diameter. Lp[a] size correlated positively with LDL size (r = 0.62; P < 0.001), but the association between Lp[a]- size and LDL size was stronger (r = 0.82; P < 0.0001). Log triglyceride level correlated inversely with Lp[a]- size (r = -0.72; P < 0.0001) and LDL size (r = 0.69; P < 0.0001). HDL cholesterol level correlated positively with Lp[a]- size (r = 0.67; P < 0.0005) and LDL size (r = 0.64; P < 0.0005). The strong correlation between LDL size and Lp[a]- size may be due to extracellular utilization of circulating LDL in the production of Lp[a] or may reflect the same metabolic processes influencing both these particles once Lp[a] has been formed.
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OBJECTIVE: To establish a ELISA assay to measure release of type 1-phospholipase A2 propeptide from activated granulocytes. Human type 1-prophospholipase A2 (1-proPLA2) is biosynthesized and stored as inactive zymogen. Activation involves tryptic-like cleavage at the N-terminus, with equimolar release of the heptapeptide DSGISPR. METHODS: Using antibodies directed to the carboxyterminus of synthetic DSGISPR we developed a sensitive solid-phase ELISA specific for the released propeptide that accurately reports the activation of 1-proPLA2. The presence of the 1-proPLA2 precursor itself can be determined by trypsinization of the sample and subsequent assay for free DSGISPR. RESULTS: Using this ELISA, we demonstrated the presence of immunoreactive DSGISPR and its 14 kDa 1-proPLA2-like precursor in human granulocytes, but their absence in human macrophages and lymphocytes. Stimulation of cultured granulocytes with 1 pM of TNF alpha or GM-CSF caused rapid release of DSGISPR and precursor into the surrounding medium. The immunoreactive signal coeluted with standard synthetic DSGISPR on G50 Sephadex chromatography. CONCLUSION: Release of DSGISPR immunoreactivity appears to be a specific consequence of granulocyte activation of potential relevance to the clinical pathophysiology of conditions like acute lung injury.
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Neutrophil sequestration and activation in the pulmonary vasculature and interstitium are important in acute lung injury. Phospholipase A2 plays an important part in the production of potent inflammatory mediators in this syndrome. We used our ELISA for type 1 prophospholipase A2 activation peptides, which have the aminoacid sequence Asp-Ser-Gly-Ile-Ser-Pro-Arg (DSGISPR), to show that DSGISPR concentrations in plasma and urine are a sensitive and specific marker of acute lung injury in patients admitted to intensive care. The detection of DSGISPR in the plasma of 11 of 50 unselected patients had a sensitivity of 100% and a specificity of 93% for the presence or future development of acute lung injury.
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The appearance of crisis forms or degenerate, intraerythrocytic parasites in the peripheral blood of C57BL/6 hosts during the course of Plasmodium chabaudi AS infection was analysed. Following intraperitoneal injection with 10(6) parasitized erythrocytes, C57BL/6 hosts, which are resistant to this species of rodent Plasmodium, eliminate the parasite from the peripheral blood by 4 weeks and recover from acute infection. Elimination of the parasite coincides with the appearance in the peripheral blood of almost all the parasites as crisis forms. A role for cell-mediated immunity in the induction of crisis forms of Plasmodium species has previously been suggested. To define the role of cell-mediated immunity in the appearance of intraerythrocytic crisis forms in the peripheral blood during acute malaria, the outcome of P. chabaudi AS infection, the course of parasitemia and the appearance of crisis forms in mice with either genetically determined or experimentally induced immunodeficiencies on the resistant C57BL-derived background were examined. The mice used were either B-cell deficient (mu-suppressed from birth). T-cell deficient (nu/nu mice), C5 deficient or splenectomized prior to infection. The appearance of intraerythrocytic crisis forms in the peripheral blood during the course of P. chabaudi AS infection is shown to be dependent on cell-mediated mechanisms which require the presence of T cells as well as an intact spleen for the most efficient elimination of this parasite.
The purpose of this study was to determine if increased knowledge changes nursing students' attitudes toward individuals with AIDS. A pretest/post-test design was used to administer a questionnaire, developed and validated in the United States, and adapted for use in this study. Subjects were total population of first to fourth year baccalaureate undergraduate nursing students attending a 1-day AIDS workshop. Questions dealt with knowledge and fears concerning AIDS and caring for AIDS patients, and attitudes toward homosexuality and toward the terminally ill. With the level of significance set at (p less than .05), post-test results indicated that all groups of students displayed a knowledge gain (p = .000) and a more positive attitude toward caring for AIDS patients (p = .001), particularly by e, first and third year students (p = .001). Although positive, younger students and students who had cared for AIDS patients were less positive. In this study, AIDS education had a positive influence on attitudes of nursing students. This finding supports the use of education to foster positive attitudes toward AIDS and individuals with AIDS.
The role of mononuclear phagocytes in acquired immunity resulting in the intraerythrocytic destruction and elimination of malarial parasites was investigated in the murine model of infection with Plasmodium chabaudi AS. Mice were treated 1 day before or 6 days after infection with agents which either result in augmentation or activation of the non-specific, microbicidal effector function of mononuclear phagocytes or in depletion of cells of this lineage. To examine the effect of agents which activate mononuclear phagocytes. A/J mice, which are susceptible to P. chabaudi AS and exhibit fulminant parasitaemia and death within 10 days of intraperitoneal infection with 10(6) P-RBC, were treated intravenously with muramyl dipeptide (MDP) or liposome-encapsulated MDP-glycerol dipalmitate (MDP-GDP). Treatment administered 1 day before infection was ineffective. Treatment on day 6 post-infection with liposome-encapsulated MDP-GDP (1 microgram) resulted in a significant decrease in parasitaemia on day 8 and survival, while treatment with free MDP (100 micrograms) resulted only in a significant decrease in parasitaemia. To examine the effect of depletion of mononuclear phagocytes, C57BL/6 mice, which are resistant to P. chabaudi AS infection and eliminate the parasite by 4 weeks, were treated intravenously with 3 mg silica. Silica administered 1 day before or 6 days post-infection abrogated resistance resulting in a delay in elimination of the parasite and host mortality. Treatment on day 6 was more effective, with death by day 13 post-infection of 70% of the normally resistant C57BL/6 mice which exhibited fulminant parasitaemia levels. These results thus provide in-vivo evidence that mononuclear phagocytes play a critical role in the elimination of infection with the murine malaria species P. chabaudi AS. Furthermore, these results suggest that the time of administration of agents which alter mononuclear phagocyte function may be important in determining their effect on host antimalarial defences.
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(dl)-(5 alpha,8 alpha,9 alpha)-5,8,9,10-Tetrahydro-5,9- methanobenzocycloocten-8-amine hydrochloride (Org 6906) is a potential new antidepressant agent, with a neurochemical profile quite different from that of the classical tricyclic antidepressant drugs. The compound was found active in behavioural tests which are considered to be predictive for antidepressant activity, such as the muricidal test in the rat and the acquired immobility model. Neurochemical studies showed that Org 6906 was an inhibitor of the reuptake of monoamines both in vitro and ex-vivo without having appreciable anticholinergic, antihistaminergic or alpha 1-adrenolytic activity. The facilitatory effect on monoaminergic neurotransmission was confirmed by the reversal of hypothermia induced by reserpine. The drug Org 6906 appeared to have selective alpha 2-adrenolytic properties. It facilitated potassium-stimulated release of noradrenaline from slices of cortex, displaced [3H]rauwolscine and [3H]dihydroergocryptine from their binding sites but only weakly blocked alpha 1-adrenoceptors. The alpha 2-adrenolytic properties were also apparent in behavioural interaction models. The compound antagonized the sleep-inducing effects of clonidine in chicks and mice and it antagonized the mydriasis induced by clonidine in the rat. Finally, it was shown that the two enantiomers of Org 6906 contributed almost equally to the relevant neurochemical and behavioural properties.
Renal papillary necrosis is a frequent complication of unsuccessful renal transplantation in rats, occurring in both isografts and allografts. Papillary necrosis does not occur alone, but only and inevitably in association with severe cortical damage. The pattern of the lesion is different from other forms of papillary necrosis in that the least severe lesions occur in the outer medulla and the more severe lesions involve both medulla and papilla. The incidence of papillary necrosis is increased in isografts, but not in allografts, by longer preservation times. It is suggested that the principal underlying cause may be damage to medullary capillaries, occurring either during preservation or as a consequence of rejection and leading to medullary ischemia.
Visceral glomerular epithelial cell lesions--microvillus formation, loss of foot processes, osmiophilic inclusion droplets, balloon-like malformation of cell processes, degeneration, necrosis, and loss of cell processes from capillary basement membranes--are found in rat renal isografts 1 mth after transplantation. The lesions, which are most readily recognized in perfusion-fixed material, are essentially focal, affecting neither all glomeruli, nor all cells in any glomerulus, bear no relation to the degree of interstitial nephritis in the graft, and are associated with albuminuria and with focal capillary sclerosis in some glomeruli. They are not restricted to renal isografts but are found in aging rats, in different experimental models of glomerular disease and in clinical glomerular disorders, again in association with proteinuria and glomerulosclerosis. It is therefore proposed that glomerular epithelial cell damage increases capillary permeability and impairs maintenance of the integrity of the capillary wall, leading to proteinuria and focal glomerulosclerosis.
The effects of cyclosporine (CsA) on renal function and morphology have been studied in the rat after unilateral nephrectomy and warm renal ischemia. There is evidence of an enhanced CsA nephrotoxic effect after unilateral nephrectomy alone and of an additive or synergistic effect of CsA and renal ischemia upon renal function and morphology. These enhanced effects are most evident after longer periods of ischemia (60 min) and with higher doses of CsA (25 mg/kg/day). The findings may be relevant to clinical practice and suggest that the nephrotoxic effects of CsA upon the donor kidney may be greatest when there is coincident renal damage from other causes.