Biomedical subjects

G Hodge

Publications and source records attributed to G Hodge.

At least 19 recordsLinked to original sources

PubMed2002

Dysregulation of angiotensin II synthesis is associated with salt sensitivity in the spontaneous hypertensive rat.

(1) Salt sensitive hypertension, which occurs as a result of treatment with nitric oxide synthase inhibitors, is associated with a loss of the usual down-regulatory effect of dietary sodium on angiotensin II (Ang II) synthesis. In the spontaneous hypertensive rat (SHR), which suffers a relative NO deficiency, the hypertension is in part salt sensitive. We sought to determine therefore whether the salt sensitive component to the hypertension was associated with a loss of the regulatory effect of dietary sodium on Ang II synthesis. (2) Male SHR were placed on low, intermediate or high salt diets for 4 weeks and their blood pressure recorded. After 4 weeks, blood was collected for determination of renin, angiotensinogen, Ang I, Ang II and aldosterone concentrations, as well as ACE activity. (3) The increase in systolic blood pressure in rats on the high salt diet was significantly greater than in those on the low (P < 0.005) and intermediate salt diets (P < 0.0005). Plasma renin and aldosterone concentrations and ACE activity decreased with increasing dietary sodium. However, the concentrations of Ang II and angiotensinogen both increased in the rats on the high salt diet (Ang II: P < 0.05; angiotensinogen: P < 0.05). (4) We conclude that the hypertension in the SHR is in part salt sensitive and that this salt sensitive component is associated with a loss of the normal down-regulatory effect of dietary sodium on Ang II and angiotensinogen synthesis.

Aldosterone↗

PubMed2002

Salt-sensitive hypertension resulting from nitric oxide synthase inhibition is associated with loss of regulation of angiotensin II in the rat.

In the Dahl salt-sensitive hypertensive rat, a diet containing L-arginine, the natural substrate for nitric oxide synthase, abrogates the hypertension. We postulated that nitric oxide synthase inhibition might induce a salt-sensitive form of hypertension and that this salt sensitivity might be linked to a loss of the regulatory effect of sodium ingestion on angiotensin II (Ang II) and angiotensinogen. Male Wistar-Kyoto rats were randomised to a diet containing 0.008 %, 2.2 % or 4.4 % sodium chloride and to treatment with the NO synthase inhibitor L-NAME (10 mg kg(-1) day(-1)) in the drinking water, or drinking water alone (Controls) for 4 weeks. Blood pressure was measured by tail cuff plethysmography twice weekly. After 4 weeks, the rats were anaesthetised and truncal blood collected for determination of angiotensinogen, renin, angiotensin I (Ang I), Ang II and aldosterone concentrations as well as angiotensin-converting enzyme (ACE) activity. Systolic blood pressure increased with increasing dietary sodium intake in the L-NAME-treated rats (P < 0.05). Plasma renin and aldosterone concentrations decreased with increasing dietary sodium intake in both Control and L-NAME-treated rats. Ang I and ACE activity were unchanged by increasing dietary sodium intake. In contrast, the plasma concentration of Ang II and angiotensinogen increased with increasing dietary sodium (P < 0.05 and P < 0.005, respectively). Treatment with the Ang II receptor blocker, losartan, reversed the blood pressure increase. We conclude that treatment with L-NAME induces an increase in blood pressure that is at least in part salt sensitive. Further, the salt-sensitive component appears to be Ang II-dependent, as it was associated with increasing plasma Ang II levels and could be reversed by treatment with an Ang II receptor antagonist.

Aldosterone↗

PubMed2001

Effect of intermediate-purity factor VIII (FVIII) concentrate on lymphocyte proliferation and apoptosis: transforming growth factor-beta is a significant immunomodulatory component of FVIII.

Factor concentrates have been shown to have a variety of immunomodulatory effects in vitro. The presence of plasma-derived factor VIII (pdFVIII) has been shown to diminish lymphocyte proliferative response to mitogens. Recently, we have shown the presence of transforming growth factor-beta (TGF-beta) as an immunomodulatory component present in plasma-derived FVIII concentrate. However, the addition of neutralizing antibody to TGF-beta did not abrogate the inhibitory effect of pdFVIII on monocyte cytokine production, suggesting the presence of other, as yet undetermined, immunomodulatory agent/s in pdFVIII. To further characterize the immunomodulatory effects of pdFVIII, the in vitro effect of pdFVIII concentrate on proliferation and apoptosis of mitogen-stimulated T cells was studied using whole blood and purified T cells. The presence of pdFVIII increased the apoptosis of phytohaemagglutinn (PHA) -stimulated CD4 and CD8 T-cell subsets as determined by Annexin V binding and DNA fragmentation. T-cell subsets showed a pdFVIII dose-dependent inhibition of entry into S-phase and G(1) arrest. Addition of neutralizing anti-TGF-beta reduced some of these changes. To determine the physiological relevance of these findings, blood samples from five patients receiving FVIII prophylaxis were similarly studied ex vivo and showed significantly increased apoptosis of T-cell subsets as determined by Annexin V staining. TGF-beta has been reported to be a potent inhibitor of T-cell proliferation, arresting the cell cycle in G(1) phase and causing apoptosis. Together, these findings suggest that TGF-beta is a significant immunomodulatory component of pdFVIII concentrates.

Adult↗

PubMed2001

Factor VIII concentrate inhibits T helper type 2 cytokine production in vitro: relevance to inhibitor antibody formation.

Inhibitor antibody formation in patients with haemophilia receiving factor VIII (FVIII) concentrate is a serious problem. T helper type 2 (Th2) cytokines are necessary for antibody production by B cells and have been shown to be produced predominantly by CD30(+)/CD45RO(+)/CD3(+) cells. We have previously shown that the Th2 cytokine, interleukin (IL)-6, is inhibited but IL-10 is upregulated, in the presence of plasma-derived FVIII (pdFVIII). To clarify further the overall effect of FVIII on Th2 cytokine production, the percentage of T cells expressing the CD30(+)/CD45RO(+)/CD3(+) Th2 phenotype was studied over 72 h and the production of the Th2 cytokines, IL-4 and IL-5, determined at 24 h in the presence of FVIII following whole-blood stimulation using multiparameter flow cytometry. The production of IL-4 and IL-5 by T cells was significantly inhibited in the presence of pdFVIII. The percentage of CD30(+)/CD45RO(+)/CD3(+) increased with stimulation of whole blood cultures over 72 h but was significantly inhibited by the presence of pdFVIII or TGF-beta at 72 h. The combined inhibitory effect of prednisolone (a commonly used immunosuppressive agent used to treat patients with inhibitors) with pdFVIII on T-cell CD30(+)/CD45RO(+) upregulation, was additive. There was no significant alteration in Th2 cytokine production or phenotype noted in the presence of recombinant FVIII (rFVIII) concentrate. Neutralizing antibody to TGF-beta significantly abrogated the inhibitory effects of pdFVIII on Th2 upregulation, indicating TGF-beta to be a major inhibitory component of pdFVIII on Th2 cytokine production. We now provide evidence that pdFVIII, by inhibiting Th2 cytokine production, may result in decreased antibody formation and may be more appropriate than rFVIII at reducing inhibitor formation. A clinical study needs to be undertaken to determine the significance of these in vitro findings.

Cell Culture Techniques↗

PubMed2001

Cord blood leucocyte expression of functionally significant molecules involved in the regulation of cellular immunity.

The cellular immune system of the newborn infant is immature and hypo-responsive when compared with adults. The extent to which immaturity of the leucocyte function underlies hyporesponsiveness in the newborn is incompletely understood. In this study flow cytometric techniques were applied to investigate the concurrent expression of a range of surface and intracellular leucocyte functional molecules and cytokines in resting and stimulated cord and adult blood. Production of interleukin (IL)-2 and expression of the components of its receptor, IL-2R alpha/beta/gamma, were investigated. No differences in the proportion of leucocytes producing IL-2R alpha and IL-2R gamma were observed for newborns and adults. A lower proportion of T cells and natural killer (NK) cells from newborns expressed IL-2R beta and upregulation of expression was slower. We hypothesize that reduced IL-2R beta may curtail early autocrine IL-2 activation of immune responses in the newborn. This hypothesis was supported by the observation that an increased proportion of stimulated T cells from newborns produced IL-2 at 4 h poststimulation, but at 24 h the proportion was lower than for adult T cells. The very low levels of interferon (IFN)-gamma produced by neonatal T cells and NK cells may also be partly explained by a curtailment of early autocrine activation of T cells. Expression and kinetics of upregulation for other functional molecules were studied. CD71, HLA-DR, tissue factor and CD152 levels were not significantly different for adults and newborns, suggesting that cord blood leucocytes, in some respects, may demonstrate functional maturity. IL-6 secretion by stimulated monocytes was also comparable in cord and adult blood. However, IL-1 alpha and IL-1 beta were produced by a lower proportion of monocytes from newborns than adults. Similarly, tumour necrosis factor (TNF)-alpha production for monocytes and T cells was lower in cord blood. The mean fluorescence intensity for IL-1 alpha, IL-1 beta and TNF-alpha was also lower for leucocytes from cord blood. These findings are significant in relation to the inability of newborn infants to mount a febrile response to infection. The findings of lower expression of IL-2R beta and lower production of inflammatory cytokines IL-1 alpha, IL-1 beta and TNF-alpha is a basis for improved understanding of the immunological immaturity of leucocytes in the newborn.

Adult↗

PubMed2001

Interleukin-4 and tumour necrosis factor-alpha inhibit transforming growth factor-beta production in a human bronchial epithelial cell line: possible relevance to inflammatory mechanisms in chronic obstructive pulmonary disease.

OBJECTIVE: Human bronchial epithelial cells are known to secrete an array of inflammatory cytokines including tumour necrosis factor-alpha (TNF-alpha) and interleukin (IL)-4, which may play a role in immune responses in lung diseases such as chronic obstructive pulmonary disease (COPD). However, the regulatory mechanisms governing cytokine production in bronchial epithelia in COPD are largely unknown. Transforming growth factor-beta (TGF-beta) is an anti-inflammatory cytokine and is involved in airway repair. The purpose of this study was to study the effect of TNF-alpha and IL-4 (pro-inflammatory cytokines known to be up-regulated in COPD), on the production of TGF-beta (a negative regulator of inflammation) by epithelial cells. METHODOLOGY: A bronchial epithelial cell line was used as an in vitro culture model (16HBE). Cell cultures were stimulated with various combinations of TNF-alpha and IL-4 (20 ng/mL) for 24 h. Transforming growth factor-beta production was measured by flow cytometry, enzyme-linked immunosorbent assay and immunohistochemistry. RESULTS: Exposure to TNF-alpha significantly up-regulated production of IL-4 from cultured epithelial cells. Unstimulated cells spontaneously released TGF-beta. Exposure to TNF-alpha and IL-4 significantly inhibited production of TGF-beta. The inhibitory effects of TNF-alpha and IL-4 on TGF-beta synthesis were summative. CONCLUSIONS: The inhibitory effect of IL-4 and TNF-alpha on production of the regulatory cytokine TGF-beta in a bronchial epithelial cell line suggests that such mechanisms may contribute to the progression of the inflammatory response and compromise repair processes in inflammatory lung diseases such as COPD.

Bronchi↗

PubMed2000

Increased levels of apoptosis of leukocyte subsets in cultured PBMCs compared to whole blood as shown by Annexin V binding: relevance to cytokine production.

Most of the investigatory studies of cytokine production by cells have been performed on purified cells or cell lines by measuring the secreted cytokine levels in the bulk culture supernatant. However, results of cytokine production from isolated peripheral blood mononuclear cells (PBMCs) cultivated in synthetic media, have been reported to be inaccurate and of low reproducibility. Isolation procedures have been shown to be toxic to certain cells. We hypothesised that purified cell culture techniques may result in increased levels of apoptosis of cells compared with whole blood culture techniques. To compare the effects on cell viability between PBMCs and whole blood techniques, an Annexin V binding assay was utilised. The effect of different cell concentration and serum/plasma concentrations on apoptosis levels in the various leukocyte subsets in PBMC and whole blood cultures following stimulation was investigated. There were significantly increased levels of apoptosis of cells in PBMC compared to whole culture at similar plasma concentrations, suggesting that cell viability was plasma concentration-dependent. There were significantly increased levels of apoptosis in PBMC cultures at the same cell concentration to whole blood techniques, suggesting that interaction between all cellular elements (as in whole blood techniques) is important in maintaining cell viability. These results suggest that whole blood culture techniques provide the best conditions for study of leukocyte cytokine production. If PBMC culture is performed, similar plasma and cell concentration to whole blood will best preserve cell viability.

Adult↗

PubMed2000

Effect of factor VIII concentrate on antigen-presenting cell (APC)/T-cell interactions in vitro: relevance to inhibitor formation and tolerance induction.

Inhibitor formation in patients with haemophilia receiving factor VIII (FVIII) concentrate is a common problem requiring tolerance induction therapy. Immune tolerance is dependent on defective T cell/antigen-presenting cell (APC) interactions and inhibitor antibody formation is associated with effective T-cell/B-cell interaction. We studied the expression of the cell-surface molecules involved with these interactions using multiparameter flow cytometry and a whole blood stimulation assay-phytohaemaglutinin (PHA) to activate T cells and Escherichia coli lipopolysaccharide (LPS) to activate monocytes and B cells. Up-regulation of T-cell co-stimulatory receptors CD11a, CD40 ligand (CD40L) and CTLA4 were inhibited in a dose-dependent manner by plasma-derived (pd)FVIII, but CD28 was unchanged. Up-regulation of monocyte and B-cell co-stimulatory ligands CD4O, B7-1 (CD80) and B7-2 (CD86) were also inhibited in a dose-dependent manner by pdFVIII, but LFA-3 (CD58) was unchanged. The combined inhibitory effect of prednisolone, an immunosuppressive agent used in several tolerance induction protocols, with pdFVIII on co-stimulatory molecules, was additive. There was no significant alteration in T-cell/APC adhesion or co-stimulatory molecules noted in the presence of recombinant (rh)FVIII concentrate. The inhibitory effect of pdFVIII on molecules involved in interaction between T cells and APCs may result in immune tolerance in recipients of pdFVIII concentrate. The inhibitory effect of pdFVIII on CD40/CD40L up-regulation may result in defective antibody formation. We now provide evidence that the use of pdFVIII, through interfering with APC/T-cell interactions, may be more appropriate than rhFVIII for tolerance induction.

Antigen-Presenting Cells↗

PubMed2000

Surface and intracellular interleukin-2 receptor expression on various resting and activated populations involved in cell-mediated immunity in human peripheral blood.

The kinetics of assembly of the high-affinity interleukin-2 receptor (IL-2R)alpha/beta/gamma were investigated by studying intracellular and surface expression of IL-2Ralpha, beta and gamma by T cells, monocytes and natural killer (NK) cells. IL-2Ralpha and IL-2Rgamma were expressed by small numbers of resting T cells. These numbers increased following stimulation, to maximal expression at 48 h and 72 h, respectively. This observation was consistent with de novo synthesis of the receptor protein in response to the stimulus. The proportion of T cells producing IL-2Rbeta was smaller and up-regulated later than the proportion of cells producing IL-2Ralpha or IL-2Rgamma. IL-2Rbeta may therefore slow the assembly of the high-affinity IL-2R on T cells. A small number of resting NK cells expressed IL-2Ralpha, both on the cell surface and intracellularly, but this increased over 72 h on stimulated NK cells. IL-2Rbeta was constitutively expressed, both on the cell surface and intracellularly, by monocytes and NK cells. An increased proportion of NK cells and monocytes produced IL-2Rbeta, 24 h and 4 h post-stimulation, respectively. Maximal or plateau expression occurred at 72 h and 24 h post-stimulation, for NK cells and monocytes, respectively. The early up-regulation of intracellular IL-2Rbeta for monocytes may facilitate the up-regulation of surface IL-2Rbeta, and early assembly of the high-affinity IL-2R, accelerating monocyte activation and function. High constitutive intracellular IL-2Rgamma expression (> 80%) in all types of leucocyte investigated, decreased over the 72 h following stimulation with a concurrent increase in surface expression. IL-2Rgamma was expressed by increased proportions of T cells, monocytes and NK cells, 4 h following stimulation. The intracellular storage of IL-2Rgamma may accelerate translocation to the cell surface after stimulation. The early translocation of IL-2Rgamma may reflect its usage as a signal transduction molecule by other cytokine receptors - IL-4, IL-7, IL-9 and IL-15. This study delineated the potential expression of the high-affinity IL-2Ralpha/beta/gamma on various stimulated leucocytes. The differential kinetics of assembly of the high-affinity IL-2Ralpha/beta/gamma on different leucocyte subsets suggests that IL-2 may regulate the inflammatory cellular responses in a sequential manner, paralleling the timed expression of IL-2Ralpha/beta/gamma on the monocytes, NK cells and T cells.

Adult↗

PubMed1999

Functional lymphocyte immunophenotypes observed in thalassaemia and haemophilia patients receiving current blood product preparations.

Immune abnormalities have been reported in recipients of cellular and plasma blood products. To document the effect of current transfusion practices, we performed ex vivo lymphocyte immunophenotypic studies on patients with thalassaemia major who had received multiple (leucocyte-depleted) transfusions and patients with haemophilia A and B who had received heat viral-inactivated factor concentrates. Patients with thalassaemia major showed a significant lymphocytosis, with mainly B-cell changes consistent with ongoing B-cell stimulation associated with chronic exposure to red cell antigens. Reduced T-cell IL-2Ralpha expression would be consistent with inhibition by desferrioxamine chelation therapy. In contrast, patients with haemophilia showed predominantly T-cell changes. Patients with haemophilia A showed significantly elevated activated CD8+ cytotoxic T lymphocytes whereas those with haemophilia B showed an increase in CD8+CD11adim and CD4+CD45RA+ suppressor T cells. Several of the immune abnormalities found may be due to the presence of cytokines not removed by leucocyte filtration or destroyed by factor concentrate production (e.g. TGF-beta) causing a T-helper-2-like response. The extensive lymphocyte characterization in this study has not previously been performed and has enabled a closer examination of the functional lymphocyte immunophenotypes seen in patients treated according to current transfusion practices.

Adolescent↗

PubMed1999

Effect of factor VIII concentrate on leucocyte cytokine production: characterization of TGF-beta as an immunomodulatory component in plasma-derived factor VIII concentrate.

Clinical and subclinical immunological abnormalities have been reported in HIV-seronegative haemophiliacs. The mechanisms by which these abnormalities arise remain unclear. As cytokines are important biological response modifiers, the effect of a FVIII concentrate on production of a range of cytokines, by a variety of cells, was investigated. A whole blood technique was used and the in vitro modulation of cytokine synthesis by an intermediate-purity plasma-derived factor VIII (pdFVIII) concentrate was analysed using multiparameter flow cytometry. In cell cultures exposed to pdFVIII, T cells showed reduced production of TNF-alpha, IL-2 and IFN-gamma; monocytes showed reduced production of TNF-alpha, IL-1alpha, IL-1beta, IL-6, IL-8 and IL-12 but an increase in IL-10 synthesis; IFN-gamma synthesis by NK cells was reduced. All changes in cytokine synthesis and the reduction in cell surface expression of CD69, a signal transduction molecule contributing to both cytokine and cytokine receptor synthesis, were in a dose-dependent manner in cultures exposed to FVIII concentrate. These changes were characteristic of TGF-beta. Addition of anti-TGF-beta to FVIII reduced these changes in T-cell cytokine production, suggesting TGF-beta may be an important immunomodulatory agent in the pdFVIII concentrate. The Th2 cytokine bias shown in the presence of pdFVIII concentrate, in vitro, may explain the increase in rates of certain types of infections reported in these patients, which require Th1 cytokine production for an effective response.

Antigens, CD↗

PubMed1999

Intracellular cytokine production and cytokine receptor interaction of cord mononuclear cells: relevance to cord blood transplantation.

A 'cytokine storm' consisting of IL-1, IL-2, IL-12, IFNgamma and TNFalpha is considered important in the development of graft-versus-host disease (GvHD). These cytokines activate effector cells or damage host tissues. Cord blood transplantation has been associated with a low incidence of GvHD. We hypothesized that the low incidence of GvHD relates to the cord mononuclear cells being poor producers of pro-inflammatory cytokines. The cytokine profile (IL-1alpha/beta, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12, IFNgamma and TNFalpha) of cord blood cells induced by immune stimuli was determined in heparinized whole blood. Compared to adult, cord blood CD3+ and NK cells produced less IFNgamma, less cord blood CD3+ cells and monocytes produced TNFalpha and less monocytes produced IL-1alpha/beta. Although more cord T cells produced IL-2 compared to adult T cells at 4 h, adult T cells produced more at 24 h. Cord blood had similar proportions of monocytes to adult producing IL-6, IL-10 and IL-12. Both adult and cord mononuclear cells constitutively expressed receptors for IFNgamma and TNFalpha but not IL-12. In contrast to the adult cells, cord CD3+ and NK cells did not express IL-12 receptor but did up-regulate IL-10 receptor after mitogenic stimulation. The findings of this study indicate that the cord blood cytokine-receptor network is biased towards anti-inflammatory activity compared to adult and helps to explain the decreased incidence of GVHD in cord blood transplantation.

Adult↗

PubMed1999

Methyl-prednisolone up-regulates monocyte interleukin-10 production in stimulated whole blood.

Glucocorticosteroids (GCS) have been used successfully in the treatment of inflammatory conditions such as asthma and acute graft-vs-host disease, but their mode of action remains unclear. There have been numerous reports of the in-vitro suppression of cytokine production by GCS based on quantitation of cytokines by ELISA on bulk supernatants from isolated cell culture systems. We report the use of a whole-blood intracellular cytokine assay which is more representative of an in-vivo environment. We examined the effects of GCS, prednisolone and dexamethasone, on cytokine production by individual cells (monocytes, T lymphocytes and natural killer or NK cells) in heterogenous cell populations. Cells in whole blood were activated with various stimuli: phorbol ester and calcium ionophore for T cells, Escherichia coli lipopolysaccharide (LPS) for monocytes, and phytohaemagglutinin (PHA) plus interleukin (IL)-12 for NK cells. Brefeldin A was used as an intracellular transport inhibitor to enhance the detection of intracellular cytokine production. The effects of various concentrations (10-5, 10-7, 10-9 and 10-11 m) of GCS on cytokine production were studied using multiparameter flow cytometry. After surface staining with fluorescently-conjugated monoclonal antibodies (MoAbs) to identify cell type, cells were fixed and permeabilised. Intracellular cytokines interferon (IFN)-gamma, IL-10, IL-1alpha and beta, IL-2, tumour necrosis factor (TNF)-alpha, and IL-12 were stained with their respective conjugated MoAbs. The GCS both caused a dose-dependent modulation of cytokine production by T cells, monocytes and NK cells. After 4 h, a decrease in the MFI (amount of cytokine produced per cell) was noted for all cell types. After 24 h a decrease in both MFI and the percentage of cells producing cytokine was observed for all cell types. The exception was monocyte production of IL-10 which was enhanced at low concentrations of GCS (10-9 and 10-11 m). Our findings thus suggest that one anti-inflammatory mechanism of GCS action may be through inhibition of the release of pro-inflammatory cytokines IL-1alpha and beta, IL-2, IFN-gamma and TNF-alpha, and up-regulation of the anti-inflammatory cytokine IL-10.

Adult↗

PubMed1999

The forgotten stakeholders: seniors' values concerning their health care.

Within the context of health care reform and its evaluation, a major gap exists in relation to our understanding of the values which seniors hold regarding their health care. This paper reports on a modified participatory, ethnographic study of such values, using transcribed interviews with ten seniors from across Canada. Members of the National Advisory Council of Canada, most of whom are themselves seniors, participated in designing the study, carrying out the interviews and interpreting the results. Clusters of values were identified concerning health care services, service providers and the overall health care system. While the numbers involved in this study preclude generalizing to the population, a number of recommendations emerged from the study which could impact on future research and begin to influence health policy at local and national levels.

Aged↗

PubMed1998

Aerosolized albuterol improves airway reactivity in infants with acute respiratory failure from respiratory syncytial virus.

The objective of this investigation was to measure the bronchodilator effect of aerosolized albuterol on infants with respiratory syncytial virus (RSV)-induced respiratory failure. Infants who required intubation and mechanical ventilator support for RSV disease were eligible for this prospective, nonrandomized study. Pulmonary function tests, including respiratory mechanics by least mean square analysis, small airway function by rapid thoraco-abdominal compression, and functional residual capacity by nitrogen washout were performed before and 20 min after inhalation of 20-40 breaths of undiluted (0.5%) albuterol solution via a small-volume nebulizer. Analysis of maximum expiratory flow at functional residual capacity (V'maxFRC) before and after albuterol administration was performed using a t-test for paired comparisons. A two-tailed P-value of less than 0.05 was considered statistically significant. Twenty-five infants (mean +/-SD postconceptional age = 45 +/- 5 weeks) were enrolled. Thirteen of the 25 infants had a prior history of prematurity and/or cardiorespiratory disease. After aerosolized albuterol, mean V'maxFRC increased significantly from 48 +/- 46 ml/sec to 65 +/- 59 ml/sec (P = 0.03); however, only three patients had an increase into the normal range. Three patients had a substantial (40-50%) decrease in V'maxFRC. These findings suggest that during the acute phase of severe RSV respiratory infection some of this group of very young infants had airway reactivity that improved in response to inhaled albuterol.

Acute Disease↗

PubMed1998

Renoprotective differences between perindopril and enalapril in the diabetic hypertensive rat do not reflect glomerular angiotensin-converting enzyme activity.

1. The various angiotensin-converting enzyme inhibitors have structural differences which affect their affinities for the catalytic sites on converting enzyme. We postulated that such differences might result in differences in renoprotective efficacy. We investigated this in the diabetic spontaneous hypertensive rat. We also investigated whether these differences might reflect variations in glomerular or plasma angiotensin-converting enzyme activity. 2. One week after induction of diabetes, rats were started on antihypertensive therapy: enalapril, 10 mg.day-1.kg-1, or perindopril, 4 mg.day-1.kg-1, in the drinking water. After 3 months, the rats were killed, blood samples were taken and tissues were harvested. Angiotensin-converting enzyme activity in isolated glomeruli and plasma was measured by fluorimetric assay. Glomerular protein content was also determined. 3. Urinary protein excretion was significantly lower in perindopril-treated rats than in either controls (P < 0.0005) or enalapril-treated rats (P < 0.05). Glomerular protein content was also lower in perindopril-treated rats (P < 0.05 versus enalapril; P < 0.005 versus control). There was no difference in glomerular angiotensin-converting enzyme activity between the two inhibitors although both were lower than control values (enalapril P < 0.025; perindopril P < 0.025). Plasma angiotensin-converting enzyme activity was significantly lower in the perindopril group than in either control (P < 0.005) or the enalapril group (P < 0.01). 4. We conclude that in the spontaneous hypertensive rat with streptozotocin-induced diabetes, perindopril is more effective than enalapril in reducing proteinuria and glomerular protein accumulation. This difference does not result from differences in glomerular-converting enzyme activity.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed1998

Surface activation markers of T lymphocytes: role in the detection of infection in neonates.

Diagnosis of perinatal infection in the newborn is difficult; there may be few clinical signs and current tests are slow or non-specific. Detection of organisms, antigen or specific antibody to common pathogens often requires repeat samples and does not give immediate results. Haematological parameters, although relied upon frequently to diagnose infection in the neonate prior to a positive bacterial isolation, are unreliable and insensitive. Indicators such as an increase in neutrophil band cell counts are highly variable between morphologists. Infection induces the expression of a number of T lymphocyte surface markers, including CD45RA/CD45RO and CD45RO. The use of changed expression of surface markers as a laboratory test for detection of infection in neonates was evaluated. We used multiparameter flow cytometry to detect expression of early (CD45RA/CD45RO) and late (CD45RO) activation markers. In the respective groups of 50 full term (including 25 normal vaginal deliveries and 25 caesarean deliveries) and 30 premature, i.e. < 36 weeks gestation (born by either normal vaginal delivery or caesarean delivery) the CD45RA isoform was brightly expressed on newborn 'naive' CD4+ T cells, whereas the CD45RO isoform (including both 'bright' and 'dim' populations) was present on < 19% of CD4+ T cells from these newborn infants. In a group of 37 infants, tested to evaluate possible effects of non-infective parameters such as respiratory distress and iso-immunization, no significant changes in surface marker expression were found and specificity of the test was confirmed. In 14 neonates with documented sepsis, up-regulation of dual staining CD45RA/CD45RO isoforms on CD4+ T cells was detected early in the infection. In addition, we found that CD45RO expression persisted for several weeks after bacterial infection, and up to several months in viral infection. In conclusion, detection of T cell activation by flow cytometry for the early diagnosis of neonatal infection is an easy test to carry out on small volumes of blood, is inexpensive, and may be a specific indicator of infection.

Bacterial Infections↗

PubMed1997

Acute but not chronic angiotensin-converting enzyme inhibition induces enzyme synthesis in the glomerulus of the spontaneously hypertensive rat.

1. Treatment with angiotensin-converting enzyme (ACE) inhibitors slows the rate of progression of nephropathy in the spontaneously hypertensive rat (SHR) with streptozotocin-induced diabetes. Paradoxically, however, chronic ACE inhibitor therapy has been reported to be associated with induction of ACE in the plasma. We sought to determine whether induction also occurred in the glomerulus. 2. Seven days after induction of diabetes rats were randomized to receive perindopril (4 mg/kg per day) in the drinking water or water alone. Blood glucoses were maintained 6-10 mmol/L by daily ultralente insulin. Rats were killed after 1 and 12 weeks of ACE inhibitor therapy and the kidneys were harvested. Angiotensin-converting enzyme activity was determined in isolated glomeruli before and after removal of perindopril and reconstitution with zinc sulphate. 3. After 1 week of ACE inhibitor therapy, glomerular ACE was significantly greater after removal of perindopril than either before its removal (P < 0.025) or in the untreated controls (P < 0.025). After 12 weeks of therapy, ACE activity was significantly lower in the perindopril-treated group than in the untreated controls (P < 0.025). There was no increase in ACE activity following removal of perindopril. 4. These studies suggest that short-term ACE inhibition is associated with induction of ACE in the glomerulus. However, there was no increase in ACE activity after removal of perindopril, suggesting that induction of synthesis of this enzyme in the glomerulus does not occur during chronic ACE inhibition.

Angiotensin-Converting Enzyme Inhibitors↗