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Biomedical subjects

A Aljada

Publications and source records attributed to A Aljada.

32 records · Page 2Linked to original sources
PubMed2000

Glucose challenge stimulates reactive oxygen species (ROS) generation by leucocytes.

Diabetes mellitus is associated with increased ROS generation, oxidative injury and obesity. To elucidate the relationship between nutrition and ROS generation, we have investigated the effect of glucose challenge on ROS generation by leucocytes, p47phox protein, a key protein in the enzyme NADPH oxidase and alpha-tocopherol levels. Blood samples were drawn from 14 normal subjects prior to, at 1, 2 and 3 h following ingestion of 75 g glucose. ROS generation by polymorphonuclear leucocytes (PMNL) and mononuclear cells (MNC) increased to a peak of 244 +/- 42% and 233 +/- 34% of the basal respectively at 2h. The levels of p47phox in MNC homogenates increased significantly at 2 h and 3 h after glucose intake. alpha-Tocopherol levels decreased significantly at 1 h, 2 h and 3 h. We conclude that glucose intake stimulates ROS generation and p417phox of NADPH oxidase; increases oxidative load and causes a fall in alpha-tocopherol concentration.

Adult↗
PubMed1999

Heparin inhibits reactive oxygen species generation by polymorphonuclear and mononuclear leucocytes.

To examine the hypothesis that heparin may affect leukocyte function and that it may have anti-inflammatory properties, we investigated the effect of heparin on reactive oxygen species (ROS) generation by leucocytes. Heparin was injected intravenously at a dose of 10000 units into eight normal subjects. Blood samples were collected from the antecubital vein sequentially, prior to and following heparin at 0, 0.5, 1, 2, and 4 hours. ROS generation was inhibited significantly by polymorphonuclear cells (PMNL) at 0.5, 1, and 2 hours and returned to baseline level at 4 hours. Similarly, ROS generation was inhibited markedly by mononuclear cells (MNC) at 0.5 hours, with a peak inhibition at 1 hour; it returned to baseline level by 4 hours. The maximum inhibition of ROS generation by PMNL was 57.3+/-19% of the basal, while that by MNC was 56.4+/-11% of the basal. Since ROS are proinflammatory and cause tissue damage, it is possible that heparin may have an anti-inflammatory effect in vivo, apart from its antithrombotic effect. Since ROS also bind to nitric oxide (NO) and reduce the bioavailability of NO, heparin may indirectly increase the bioavailability of NO and thus act as a vasodilator. This effect of heparin may be of particular relevance to its use in unstable angina and following thrombolysis in acute myocardial infarction in preventing reperfusion injury.

Adult↗
PubMed1999

Effect of dexamethasone on reactive oxygen species generation by leukocytes and plasma interleukin-10 concentrations: a pharmacodynamic study.

After the demonstration that hydrocortisone inhibits reactive oxygen species (ROS) generation by leukocytes in vivo in a highly predictable manner, we investigated the effect of dexamethasone at a dose of 4 mg, which is thought to be roughly equivalent to 100 mg hydrocortisone. We also tested the hypothesis that dexamethasone may increase the plasma concentration of interleukin-10 (IL-10), an immunomodulatory cytokine that inhibits T(H)1 cells. Dexamethasone (4 mg given intravenously) markedly inhibited ROS generation by mononuclear cells and polymorphonuclear leukocytes. The onset of the effect on polymorphonuclear leukocytes occurred at 1 hour (76.3% +/- 9.3% of basal value), and the peak effect occurred at 4 hours (22.9% +/- 6.4% of basal value), with a significant inhibition still persistent at 8 hours (51.3% +/- 14.3% of basal value; F = 66.7; P < .001). ROS generation was restored to baseline at 24 hours (97.6% +/- 9.5%). The inhibitory effect of dexamethasone on mononuclear cells was 78.3% +/- 9.5% of baseline at 1 hour, 11.4% +/- 6.6% at 4 hours, 30.3% +/- 14.1% at 8 hours, and 102.3% +/- 18% at 24 hours (F = 66.5; P < .001). The peak inhibitory effect of dexamethasone on mononuclear cells (11.4% +/- 6.6%) was significantly greater (P < .05) than that on polymorphonuclear leukocytes (22.9% +/- 6.4%). Plasma IL-10 concentrations increased consistently from 4.8 +/- 1.8 pg/mL within 1 hour of dexamethasone injection and peaked at 4 hours (8.8 +/- 2.3 pg/mL), declining to baseline at 8 hours (F = 4.26; P < .004). Dexamethasone (and possibly other glucocorticoids) therefore exerts its immunosuppressive and anti-inflammatory effects by inhibiting ROS generation by leukocytes and by increasing the plasma concentrations of IL-10.

Adult↗
PubMed1999

Liquid ventilation attenuates pulmonary oxidative damage.

PURPOSE: Liquid perfluorochemicals reduce the production of reaction oxygen species by alveolar macrophages. We sought to determine whether the use of liquid perfluorochemicals in vivo during liquid ventilation would attenuate oxidative damage to the lung. MATERIALS AND METHODS: Healthy infant piglets (n = 16) were instrumented for mechanical ventilation and received intravenous oleic acid to create an acute lung injury. The animals were assigned to a nontreatment group receiving conventional mechanical ventilation or a treatment group receiving partial liquid ventilation with a liquid perfluorochemical. Following sacrifice, the bronchoalveolar lavage and lung parenchyma were analyzed for evidence of oxidative damage to lipids and proteins by determination of TBARS and carbonylated protein residues, respectively. RESULTS: Mortality in the control group was 50% at the completion of the study compared with no deaths in the partial liquid ventilation group (P = .025). The alveolar-arterial oxygen difference was more favorable following injury in the partial liquid ventilation group. The liquid ventilation group demonstrated a 32% reduction in TBARS (P = .043) and a 14% reduction in carbonylated protein residues (P = .061). CONCLUSION: These data suggest that partial liquid ventilation supports gas exchange and reduces mortality in association with a reduction in the production of reactive oxygen species and the concomitant attenuation of tissue damage during the early phase of acute lung injury.

Animals↗
PubMed1999

Hydrocortisone-induced inhibition of reactive oxygen species by polymorphonuclear neutrophils.

OBJECTIVE: To determine whether hydrocortisone given intravenously inhibits reactive oxygen species (ROS) generation by polymorphonuclear neutrophils (PMNLs) in vivo and, if so, to describe the pharmacodynamics of this effect. DESIGN: A prospective, open label study in normal subjects. SETTING: A clinical research unit of a tertiary referral center for diabetes and endocrinology. PATIENTS: Eight normal subjects (age range, 2450 yrs). INTERVENTION: An indwelling cannula was inserted into the antecubital vein. Sequential blood samples were obtained from the cannula just before, and after, the intravenous injection of hydrocortisone (100 mg) at 1, 2, 4, 8, and 24 hrs. MEASUREMENTS AND MAIN RESULTS: ROS generation by PMNLs and mononuclear cells (MNCs) was assayed as previously observed in a chemiluminometer. ROS generation by PMNLs and MNCs was inhibited by hydrocortisone at 1 hr; this effect peaked at 2 hrs and began to recover by 4 hrs; ROS generation had recovered to the baseline by 24 hrs. Although the pharmacodynamic effect of hydrocortisone on PMNLs and MNCs was similar, the peak inhibition was significantly greater for PMNLs (26% of basal vs. 43% of basal, p<.02) than MNCs. CONCLUSIONS: There is a marked, consistent, inhibition of ROS generation by PMNLs, which parallels that of MNCs after intravenous hydrocortisone. The pharmacodynamics of this effect are consistent with our current clinical practices.

Adult↗
PubMed1999

Increase in plasma interleukin-10 following hydrocortisone injection.

In view of the fact that glucocorticoids have an immunosuppressive effect and the fact that interleukin-10 (IL-10) is inhibitory to T helper cell function, we have now investigated the effect of hydrocortisone on plasma IL-10 concentrations. Seven normal subjects were injected with 100 mg hydrocortisone intravenously between 8 and 9:00 a.m. Sequential blood samples were obtained prior to and 1, 2, 4, 8 and 24 h after the injection. Plasma IL-10 concentrations increased significantly and consistently following the injection in all subjects. The peak increase of IL-10 occurred at 4 h and the restoration to baseline by 8 h. The sequential values were (mean+/-SD): 3.0+/-1.3 pg/ml at 2 h, 9+/-4.2 pg/ml at 4 h, 3.7+/-1.8 pg/ml at 8 h and 3.7+/-1.4 pg/ml at 24 h. The magnitude of increase was 436% of the basal at peak effect. This effect of hydrocortisone (and possibly other glucocorticoids) may contribute to the immunosuppressive effect of this drug. IL-10 may also be potentially useful in the assessment of Cushing's Syndrome as a marker of end organ effect of glucocorticoids.

Adult↗
PubMed1999

Increased IkappaB expression and diminished nuclear NF-kappaB in human mononuclear cells following hydrocortisone injection.

We have recently demonstrated that hydrocortisone and other glucocorticoids inhibit reactive oxygen species (ROS) generation by mononuclear (MNC) and polymorphonuclear leucocytes (PMNL). Since NF-kappaB/IkappaB system regulates the transcription of proinflammatory genes, including those responsible for ROS generation, we tested the hypothesis that hydrocortisone may stimulate IkappaB production thus inhibiting NF-kappaB translocation from the cytosol into the nucleus in MNC, in vivo. One hundred milligram of hydrocortisone was injected intravenously into 4 normal subjects. Blood samples were obtained prior to the injection and at 1, 2, 4, 8 and 24 hr after the injection. Nuclear extracts and total cell lysates were prepared from MNC by standard techniques. IkappaB levels in MNC homogenates increased at 1 hr, peaked at 2-4 hr, started to decrease at 8 hr, and returned to baseline levels at 24 hr. NF-kappaB in MNC nuclear extracts decreased at 1 hr, reached a nadir at 4 hr, gradually increased at 8 hr and returned back to baseline levels at 24 hr. The total protein content of NF-kappaB subunit (P65) in MNC lysates also showed a decrease following hydrocortisone injection. This decrease was observed at 2 hr, reached a nadir at 4 hr, and returned to baseline levels at 24 hr. ROS generation inhibition paralleled NF-kappaB levels in the nucleus. It was inhibited at 1 hr, reached a nadir at 2-4 hr, started to increase at 8 hr, and returned to basal levels at 24 hr. Our data demonstrate that hydrocortisone induces IkappaB and suppresses NF-kappaB expression in MNC in parallel. IkappaB further reduces the translocation of NF-kappaB into the nucleus thus preventing the expression of proinflammatory genes.

Adult↗
PubMed1998

Premature peripheral vascular disease: clinical profile and abnormal lipid peroxidation.

The aim of this study was to determine any biochemical differences between early-onset peripheral vascular disease and typical onset atherosclerosis, and age-matched controls. A subset of patients present at a young age ( < 50 years) with peripheral vascular disease which pursues an aggressive course. As lipid oxidation seems important in atherosclerosis, total lipid peroxides, oxidized subfractions, and Trolox equivalent antioxidant capacity (TEAC) were studied in patients with premature peripheral vascular disease. Charts were reviewed of patients operated on for vascular occlusive disease over a 5-year period. Patients with early-onset peripheral vascular disease (group I) were evaluated for biochemical abnormalities and compared with typical onset atherosclerotics (group II) and age-matched controls (group III). Sixteen patients with early-onset peripheral vascular disease underwent biochemical evaluation. Conventional lipid profiles did not differ statistically from those of age-matched controls, except for mild elevations in LDL and VLDL in patients with vascular occlusive disease (207 and 195 mg/dl in groups I and 11 versus 157 mg/dl in group III). Total oxidative potential was significantly elevated (P = 0.006) 3.04, 2.15 and 2.04 nmol/ml in groups I, II and III, respectively. Levels of oxidized LDL and VLDL were even more significantly elevated (P = 0.0009) for premature peripheral vascular disease, (1.2, 0.58 and 0.47 nmol/ml in groups I-II). TEAC values did not differ significantly between groups (0.83, 0.82, 0.82 nmol/ml) and did not correlate with total lipid peroxide values for individual patients. In conclusion, lipid peroxides were significantly elevated in patients with premature peripheral vascular disease, the most marked changes being seen in oxidized LDL and VLDL subfractions. Lipid peroxides were elevated when standard lipid profiles were only mildly abnormal. The poor long-term prognosis in these patients suggests the need for aggressive evaluation and treatment of lipid abnormalities.

Adult↗
PubMed1998

Lipid hydroperoxide stimulates retinal neovascularization in rabbit retina through expression of tumor necrosis factor-alpha, vascular endothelial growth factor and platelet-derived growth factor.

To test the hypothesis that oxidative damage associated with tissue hypoxia plays a role in neovascularization, a lipid hydroperoxide (LHP) was injected into the vitreous of rabbits. Single injections of LHP (50-600 microg) caused a sustained retinal neovascularization visualized clinically by ophthalmoscopy and confirmed by microscopy. Vasodilators, i.e. histamine and nitric oxide, peaked at 6h and 7 days, respectively. The levels of both tumor necrosis factor-alpha and interleukin-1alpha peaked at 12h and dropped to basal levels by 24h. Expression of vascular endothelial growth factor (VEGF) and transforming growth factor-beta peaked at 24h and were sustained throughout the following 3 weeks, and platelet-derived growth factor was also elevated throughout the same period. Upregulation of these five angiogenic cytokines, but not basic fibroblast growth factor, occurred prior to the appearance of neovascularization. Leakage of fluorescein at the tips of new vessels was demonstrated by fluorescein angiography. Linoleic hydroperoxide induced neovascularization, but saturated or unsaturated native C-18 fatty acids had no effect. The cascade of multiple, angiogenic cytokines induced by LHP may interact to promote sustained neovascularization.

Journal Article↗
PubMed1998

Tumor necrosis factor-alpha in sera of obese patients: fall with weight loss.

In view of the recent demonstration that obesity in animals and humans is associated with an increase in tumor necrosis factor-alpha (TNFalpha) expression, that this expression falls with weight loss, and that TNFalpha may specifically inhibit insulin action, the possibility that TNFalpha may be a mediator of insulin resistance has been raised. We have undertaken this study to investigate whether serum TNFalpha concentrations are elevated in obese subjects, whether they fall after weight loss, and whether this fall parallels the fall in insulin release after glucose challenge. Obese patients (age range: 25-54, weight mean +/- SD: 96.4 +/- 13.8 kg, body mass index: 35.7 +/- 5.6 kg/m2) were started on a diet program. The mean weight fell to 84.5 +/- 11.3 (P < 0.0001) and body mass index to 31.3 +/- 4.9 (P < 0.0001). Plasma TNFalpha concentrations were markedly elevated in the obese (3.45 +/- 0.16 pg/mL), when compared with controls (0.72 +/- 0.28 pg/mL), and fell significantly (2.63 +/- 1.40 pg/mL) after weight loss (P < 0.02). The magnitude of insulin release after glucose (75 g) challenge (area under the curve) also fell significantly (P < 0.01) after weight loss. The magnitude of weight loss and fall in TNFalpha were related to basal body weight (r = 0.57, P < 0.001) and basal TNFalpha (r = 0.55, P < 0.001) concentrations, respectively, but not to each other or to the glucose-induced insulin release (area under the curve). We conclude that obesity is associated with increased plasma TNFalpha concentrations, which fall with weight loss. Because circulating TNFalpha may mediate insulin resistance in the obese, a fall in TNFalpha concentrations may contribute to the restoration of insulin resistance after weight loss, Thus, TNFalpha may be an important circulating cytokine, which may provide a potentially reversible mechanism for mediating insulin resistance.

Adult↗
PubMed1997

Oxidative stress in diabetic macrovascular disease: does homocysteine play a role?

BACKGROUND: Non-insulin-dependent diabetes mellitus (NIDDM) and hyperhomocysteinemia are both associated with increased lipid peroxidation (oxidative stress). This may contribute to the accelerated vascular disease associated with these conditions. It is not known whether the coexistence of elevated homocysteine levels will stimulate oxidative stress further than that caused by diabetes alone. METHODS: Plasma concentrations of thiobarbituric acid reactive substances (TBARS), an index of lipid peroxidation, were measured in patients with NIDDM who had previously had a methionine load test; some of the patients had hyperhomocysteinemia. RESULTS: Plasma TBARS concentrations were elevated in diabetics with vascular disease. The additional presence of hyperhomocysteinemia was not associated with a further increase in plasma TBARS concentrations. CONCLUSIONS: Lipid peroxidation is increased in patients with diabetes mellitus and macrovascular disease and is not further elevated by the coexistence of elevated homocysteine levels. It is possible that diabetes maximally stimulates oxidative stress and any further acceleration of vascular disease in patients who have coexistent hyperhomocysteinemia is mediated through mechanisms other than lipid peroxidation.

Adult↗
PubMed1996

Calcium, calmodulin and protein kinase C dependence of platelet shape change.

Platelet shape change (PSC) represents the initial phase of platelet activation and is normally investigated in ethylene diamine tetraacetic acid (EDTA) containing platelet rich plasma (PRP); EDTA is a potent chelator of calcium and therefore reduces ionized calcium to negligible levels. It is therefore assumed that it is a process independent of calcium. To test the hypothesis that PSC may be dependent upon intracellular calcium, we examined the effect of 8-(N,N-Diethylamino) octyl 3,4,5-Trimethoxybenzoate hydrochloride (TMB-8), an inhibitor of intercellular calcium mobilization on PSC. It produced a dose dependent inhibition of PSC. We then examined whether PSC was dependent upon calmodulin and protein kinase C, a calcium dependent enzyme which is cardinal to platelet aggregation. Both calmidazolium, a specific inhibitor of calmodulin, and H-9, a specific inhibitor of protein kinase C, produced dose dependent inhibition of PSC. Finally, we investigated whether GP IIb/IIIa receptor which binds fibrinogen was involved in PSC; DMP 728 [(cyclic [D-2-amino-butyryl-N2-methyl-L-arginyl-glycyl-L-aspartyl-3- (a min o-methyl-benzoic acid], methanesulfonic acid salt] a potent GP IIb/IIIa receptor antagonist was without any effect on PSC. We conclude that PSC is a calcium, calmodulin and protein kinase C dependent process like platelet aggregation but that it does not require extracellular calcium or the participation of platelet GP IIb/IIIa complex.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1994

Procalcitonin increase after endotoxin injection in normal subjects.

As procalcitonin concentrations have been shown to be elevated in patients with septicemia and gram-negative infections in particular, we proceeded to investigate the effect of endotoxin, a product of gram-negative bacteria, on procalcitonin concentrations in normal human volunteers. Endotoxin from Escherichia coli 0113:H10:k, was injected i.v. at a dose of 4 mg/kg BW into these healthy volunteers. Blood samples were obtained before and 1, 2, 4, 6, 8, and 24 h after injection of the endotoxin. Each patient's cardiovascular and overall clinical status was monitored over this period. The patients developed chills and rigors, myalgia, and fever between 1-3 h. Tumor necrosis factor-alpha levels increased sharply at 1 h and peaked at 90 min, reaching the baseline concentration thereafter by 6 h. Interleukin-6 levels increased more gradually, peaking at 3 h and reaching the baseline concentration at 8 h. The procalcitonin concentration, which was undetectable (< 10 pg/mL) at 0, 1, and 2 h, was detectable at 4 h and peaked at 6 h, maintaining a plateau through 8 and 24 h (4 ng/mL). There was no elevation of calcitonin concentrations, which remained below 10 pg/mL, the lowest sensitivity of the assay. Procalcitonin was measured by a two-antibody immunoradiometric assay specific for this peptide, with no cross-reactivity with calcitonin, katacalcin, or calcitonin gene-related peptide. We conclude that endotoxin induces the release of procalcitonin systemically, that this increase is not associated with an increase in calcitonin, and that the increase in procalcitonin associated with septicemia in patients may be mediated through the effect of endotoxin described here. Whether procalcitonin participates in the mechanisms underlying inflammation remains to be investigated.

Adult↗