Biomedical subjects

C A Flores

Publications and source records attributed to C A Flores.

At least 19 recordsLinked to original sources

PubMed2006

Modulation of renal kallikrein by a high potassium diet in rats with intense proteinuria.

Injury of the renal tubulointerstitial compartment is recognized to play an important role in hypertension. Its damage may in turn, impair the activity of vasodepressor systems, like the kallikrein-kinin, in blood pressure regulation. The overload proteinuria model induces tubulointerstitial injury with activation of the renin-angiotensin system, but renal kallikrein and the development of hypertension have not received special attention. Sprague-Dawley rats received seven intraperitoneal doses of bovine serum albumin (BSA) 2 g/day under normosodic diet and were hydrated ad libitum. A second group received a high potassium diet to stimulate kallikrein production during the previous four weeks and while under BSA administration. A third one received potassium and BSA in the same schedule, but with the kinin B2 receptor antagonist, HOE140, added during the protein load phase. A control group received seven saline injections. Kallikrein protein was detected by immune labeling on renal sections and enzymatic activity in the urine. The BSA group showed massive proteinuria followed by intense tubulointerstitial damage. Blood pressure increased after the third dose in BSA animals, remaining elevated throughout the experiment, associated with significant reductions in renal expression and urinary activity of kallikrein, compared with controls. An inverse correlation was found between blood pressure and immunohistochemistry and urinary activity of kallikrein. Potassium induced a significant increase in both urinary activity and renal kallikrein expression, associated with significant reduction in blood pressure. The HOE140 antagonist blunted the antihypertensive effect of kallikrein stimulation in proteinuric rats. Loss of renal kallikrein, produced by tubulointerstitial injury, may participate in the pathogenesis of the hypertension observed in this model.

Animals↗

PubMed2005

Valsartan-induced hematocrit changes in renal transplant patients.

BACKGROUND: Angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor type 1 blockers (ARB) are frequently prescribed for renal transplant patients. The main reasons for their use are that their antihypertensive and antifibrogenic effects may prevent chronic renal allograft dysfunction, potentially improving transplant survival. Furthermore, ACE and ARB have been used to reduce the hematocrit in patients with posttransplant erythrocytosis. We evaluated the effects of the ARB valsartan on the evolution of hematocrit in stable renal transplant patients treated with cyclosporine (CsA), azathioprine (Aza), and prednisone. PATIENTS AND METHODS: Twenty-six stable renal transplant patients treated with valsartan 80 mg/d orally were followed for 6 months. Evaluations were performed prior to as well as at 3 and 6 months following the initiation of valsartan. RESULTS: The hematocrit levels decreased significantly at 3 months (46.1 +/- 7.3 vs 39.9 +/- 5.8 ; P < .0001) in patients with a normal hematocrit, namely a level over 38%, with no further reduction at 6 months. In recipients with an hematocrit less than 38%, there was no significant reduction, either at 3 or 6 months follow-up. Valsartan was well tolerated without significant side effects. CONCLUSION: We postulate that inhibition of the proerythropoietic effects of angiotensin II and/or the reduction in hypoxia within the renal tubulointerstitium as well as the vasodilator effects on the efferent arterioles, represent possible mechanisms for the reduction and stabilization of the hematocrit in stable renal transplant patients.

Adult↗

PubMed2005

Correlation Between C2 and AUC(0-4) in Renal Transplant Patients Treated With Diltiazem.

BACKGROUND: The area-under-the-curve (AUC) of cyclosporine (CsA) reflects exposure to the drug, but this monitoring strategy is time-consuming and not cost-effective. Recently, it has been suggested that the concentration at 2 hours after dosing (C2) shows the best correlation with AUC. The C2 has been replacing the trough measurement (C0) to monitor CsA therapy, but in patients receiving diltiazem there is not much information about this issue. We investigated the correlations between C2 and C0 with absorption AUC over the first 4 hours (AUC(0-4)) in renal stable transplant patients receiving CsA therapy with or without diltiazem. PATIENTS AND METHODS: Ten patients (five men) of ages 23 to 68 years and 6 to 84 months after transplantation, were randomly assigned to an 8-week initial period of either diltiazem washout or controlled treatment with diltiazem. Time-concentration curves of cyclosporine were performed at the end of this period using a specific RIA measurement of blood samples. Thereafter, a crossover of the groups was performed and after another 8 weeks, a second curve was obtained. Drugs that change the pharmacokinetics of cyclosporine or diltiazem were not allowed. RESULTS: The cyclosporine daily dose was lower with diltiazem (173 +/- 4 mg vs 213 +/- 4 mg, P = .002), but despite a dose reduction of only 19% +/- 1.5%, there was a trend to a larger AUC/dose (28 +/- 5 ng x h/mL x mg vs 17 +/- 2 ng x h/mL x mg, P = .1) and a trend to an increased C2 when treatment included diltiazem (1035 +/- 156 ng/mL vs 652 +/- 126 ng/mL, P = NS). Moreover, we confirmed that C2 showed the best correlation with AUC(0-4), (r = 0.7, P = .04), a correlation that improved with diltiazem (r = 0.9, P < .002). CONCLUSION: C2 is the point that correlates best with AUC(0-4) with or without diltiazem. C2 in the presence of diltiazem was associated with a stronger, more significant correlation with AUC(0-4).

Adult↗

PubMed2005

No gender-associated differences of cyclosporine pharmacokinetics in stable renal transplant patients treated with diltiazem.

Cytochrome-P450 enzymes metabolize cyclosporine both in the liver and in the intestinal wall. Diltiazem, by competitive inhibition of these enzymes, may increase the absorption and the bioavailability of cyclosporine. Some evidence points to a higher activity of some specific enzymes in women, such as CYP3A, that may influence differences in cyclosporine pharmacokinetics. We examined possible gender-associated differences in pharmacokinetic profiles of cyclosporine in 19 stable renal transplant recipients cotreated with diltiazem. Ten women and nine men, chronically using diltiazem associated with cyclosporine, azathioprine, and prednisone were randomly assigned to an 8-week period of continued controlled treatment with diltiazem (10 patients) or a wash-out period discontinuing diltiazem (nine patients). At the end of this period, the time-concentration curves of cyclosporine in the first 4 hours were performed after a single dose of cyclosporine. Thereafter, a cross-over between groups was performed, and time-concentration curves repeated. A specific RIA was used to measure cyclosporine concentrations. Comparisons between male and female patients in doses of cyclosporine and other pharmacokinetics parameters (C(0), C(2), AUC(0-4)), with or without diltiazem, did not show any difference related to gender. The association of diltiazem allowed a similar degree of reduction in Neoral dosage in male and female patients (21%). No changes in serum creatinine, blood urea nitrogen, potassium, uric acid, or blood pressure, or other adverse event were observed during the study. In these groups of patients, gender was not an important factor to be considered when diltiazem is added to cyclosporine therapy.

Area Under Curve↗

PubMed2003

Sex-related differences in the distribution of opioid receptor-like 1 receptor mRNA and colocalization with estrogen receptor mRNA in neurons of the spinal trigeminal nucleus caudalis in the rat.

We recently reported that exogenously applied orphanin FQ, the endogenous ligand for opioid receptor-like 1 (ORL(1)) receptor, produces sex-specific modulation of trigeminal nociception, and that estrogen contributes to these sex-related differences. Estrogen could produce these sex-related differences by altering the expression of the ORL(1)-receptor gene in the trigeminal nucleus caudalis. Utilizing in situ hybridization, we compared levels of ORL(1) receptor mRNA and investigated its colocalization with estrogen receptor mRNA in trigeminal neurons. Our results showed that in male rats, ORL(1) receptor mRNA is abundantly expressed in the rostral part of the trigeminal nucleus caudalis, and at the junction of caudalis and interpolaris (Vc/Vi). In comparison with males, levels of ORL(1) receptor mRNA were not significantly different in proestrus females, but were significantly higher in the rostral trigeminal nucleus caudalis and at the junction of Vc/Vi of diestrus females. In addition, ovariectomy raised the levels in the rostral trigeminal nucleus caudalis, and at the junction of Vc/Vi. Levels were reduced to proestrus levels in these regions following estradiol replacement. Our results also showed that ORL(1) receptor mRNA is present in majority of estrogen receptor (alpha and/or beta) mRNA-containing neurons. We conclude that there are sex-related differences in the ORL(1)-receptor gene expression in the trigeminal nucleus caudalis, which appear to be determined in part by estrogen levels.

Animals↗

PubMed2001

Orphanin FQ produces gender-specific modulation of trigeminal nociception: behavioral and electrophysiological observations.

The present study aimed to determine if orphanin FQ, an endogenous ligand for the opioid receptor like-1 receptor, produces gender-specific effects in the modulation of N-methyl-D-aspartate (NMDA)-evoked responses of trigeminal nociceptive neurons, and in the NMDA-induced nociceptive behavior. Single-unit extracellular recordings were made from nociceptive-specific and wide dynamic range neurons in the superficial and deeper dorsal horn of the medulla (trigeminal nucleus caudalis) in anesthetized (1.5 g/kg urethane) rats. In the proestrous female, orphanin FQ applied microiontophoretically produced facilitation of the NMDA-evoked responses in 50% (16/32) of nociceptive neurons, inhibition in 31% (10/32), and biphasic effects in 19% (6/32). In contrast, in the male, it inhibited the responses in 86% (18/21), and facilitated the responses in 14% (4/21). In ovariectomized animals, orphanin FQ inhibited the responses in 75% (9/12) of nociceptive neurons, facilitated the responses in 17% (2/12) and produced biphasic effects in 8% (1/12). In contrast, in estradiol-treated ovariectomized rats, it facilitated the responses in 46% (5/11), inhibited the responses in 36% (4/11) and produced biphasic effects in 18% (2/11). For behavioral studies, NMDA-induced scratching behavior was used to assess the effects of orphanin FQ. Twenty-eight male, ovariectomized and estradiol-treated ovariectomized rats were microinjected with NMDA (2 nmol in 10 microl) alone through a cannula implanted in the medullary region, while another 27 rats were microinjected with orphanin FQ (10 nmol in 10 microl) 10 min prior to giving NMDA. Orphanin FQ reduced the NMDA-induced nociceptive scratching behavior by 92% in the male, and by 96% in ovariectomized rats. In contrast, in estradiol-treated ovariectomized animals, orphanin FQ facilitated the NMDA-induced scratching behavior by 210%. We conclude from these studies that orphanin FQ is primarily pronociceptive in the female and primarily antinociceptive in the male. Furthermore, we suggest that estrogen is involved in generating the gender-specific effects of orphanin FQ.

Action Potentials↗

PubMed2000

Bothrops lanceolatus (Fer de lance) venom induces oedema formation and increases vascular permeability in the mouse hind paw.

The ability of snake venoms to increase vascular permeability and to induce oedema through the release of pharmacologically active substances is well known. We have studied the oedema and vascular permeability induced by Bothrops lanceolatus venom in male Swiss white mice. Paw oedema was induced by the subplantar injection of B. lanceolatus venom (125-1000 ng/paw) and was quantified as the increase in paw weight. Changes in vascular permeability were assessed by measuring the amount of Evans blue dye extravasation. The oedema and the increase in vascular permeability were maximal within 2 h and had resolved after 24 h. The administration of the vasodilator iloprost (20 ng/paw) immediately after B. lanceolatus venom potentiated the oedema and the increase in vascular permeability by approximately four-fold. Pretreating the mice with indomethacin, dexamethasone, NDGA or BW A4C inhibited the venom-induced oedema and the increase in vascular permeability. In contrast, histamine, serotonin and PAF-acether antagonists (mepyramine, cyproheptadine and WEB 2086, respectively) were ineffective. Histological examination showed that B. lanceolatus venom (250 ng and 500 ng/paw) caused thickening of the inner dermal layers which was accompanied by extensive intercellular spaces indicative of oedema. In addition, there was a marked infiltration of inflammatory cells, particularly neutrophils, into the underlying muscle layer. The latter, however, remained morphologically unaffected during the 3 h of observation. Venom doses larger than 500 ng/paw produced intense haemorrhage. These results indicate that B. lanceolatus venom induces oedema and increases vascular permeability in the mouse hind paw. The principal mediators of this inflammatory response are cyclooxygenase and lipoxygenase products.

Animals↗

PubMed2000

Endomorphin-1 and endomorphin-2 modulate responses of trigeminal neurons evoked by N-methyl-D-aspartic acid and somatosensory stimuli.

The present study investigated the modulation of N-methyl-D-aspartate (NMDA)-evoked and peripheral cutaneous stimulus-evoked responses of trigeminal neurons by endomorphins, endogenous ligands for the mu-opioid receptor. Effects of endomorphins, administered microiontophoretically, were tested on the responses of nociceptive neurons recorded in the superficial and deeper dorsal horn of the medulla (trigeminal nucleus caudalis) in anesthetized rats. Endomorphin-1 and endomorphin-2 predominantly reduced the NMDA-evoked responses, producing an inhibitory effect of 54.1 +/- 2.96% (mean +/- SE; n = 34, P < 0.001) in 92% (34/37) of neurons and 63.6 +/- 3.61% (n = 32, P < 0.001) in 91% (32/35) of neurons, respectively. The inhibitory effect of endomorphins was modality specific; noxious stimulus-evoked responses were reduced more than nonnoxious stimulus-evoked responses. Naloxone applied at iontophoretic current that blocked the inhibitory effect of [D-Ala(2), N-Me-Phe(4), Gly(5)-ol]-enkephalin, reduced the peak inhibitory effect of endomorphins on the NMDA- and natural stimulus-evoked responses. We suggest that endomorphins by acting at micro-opioid receptor selectively modulate noxious stimulus-evoked responses in the medullary dorsal horn.

Analgesics, Opioid↗

PubMed1999

Leguminous lectins as tools for studying the role of sugar residues in leukocyte recruitment.

The natural physiological ligands for selectins are oligosaccharides found in glycoprotein or glycolipid molecules in cell membranes. In order to study the role of sugar residues in the in vivo lectin anti-inflammatory effect, we tested three leguminous lectins with different carbohydrate binding affinities in the peritonitis and paw oedema models induced by carrageenin in rats. L. sericeus lectin was more anti-inflammatory than D. virgata lectin, the effects being reversed by their specific binding sugars (N-acetylglucosamine and alpha-methylmannoside, respectively). However, V. macrocarpa, a galactose-specific lectin, was not anti-inflammatory. The proposed anti-inflammatory activity of lectins could be due to a blockage of neutrophil-selectin carbohydrate ligands. Thus, according to the present data, we suggest an important role for N-acetylglucosamine residue as the major ligand for selectins on rat neutrophil membranes.

Acetylglucosamine↗

PubMed1999

Prevention of cyclophosphamide-induced hemorrhagic cystitis by glucose-mannose binding plant lectins.

PURPOSE: Neutrophils are implicated in the physiopathologic alterations of hemorrhagic cystitis (HC). Thus, we decided to test the antiinflammatory activity of glucose-mannose binding lectins extracted from D. violacea and D. guianensis seeds, which showed an inhibitory effect upon neutrophil migration in a model of rat peritonitis based on HC experimentally induced by cyclophosphamide (CYP). MATERIALS AND METHODS: Mice were treated with mesna (40 mg./kg., i.p.), lectins (1 and 10 mg./kg., i.v.) and 0.1 M of alpha-D-methyl-mannoside (alpha-CH3) or alpha-D-galactose (alpha-D-gal). The HC was induced by CYP (200 mg./kg., i.p.). The results were evaluated 12 hours after HC induction, based on the following parameters: vesical edema measurements, macroscopic and microscopic analysis of the bladders (Gray's analysis). The vesical edema was quantified either by the increase in bladder wet weight or by the determination of vesical vascular permeability (Evans' blue leakage). RESULTS: CYP-induced vesical edema was prevented by mesna and lectin treatment. The lectin effects were dose-dependent, and at the highest dose were similar to that achieved by mesna treatment. alpha-CH3 selectively reversed the lectin inhibitory effect. Histopathological analysis corroborated these findings and showed an intense reduction of leukocyte infiltration and tissue damage by lectin treatment. The bladders from the mesna-treated group showed a nearly normal histological pattern. However, differently from this group, none of the lectins abolished CYP-induced hemorrhage. CONCLUSIONS: The glucose-mannose binding lectins showed strong antiinflammatory activity in the mouse model of HC induced by CYP. As lectins mainly affected leukocyte vesical infiltration, we suggest a competitive blockage of glucosylated (mannose-glucose) selectin binding sites by lectins.

Animals↗

PubMed1999

American Academy of Pediatrics. Committee on Nutrition. Calcium requirements of infants, children, and adolescents.

This statement is intended to provide pediatric caregivers with advice about the nutritional needs of calcium of infants, children, and adolescents. It will review the physiology of calcium metabolism and provide a review of the data about the relationship between calcium intake and bone growth and metabolism. In particular, it will focus on the large number of recent studies that have identified a relationship between childhood calcium intake and bone mineralization and the potential relationship of these data to fractures in adolescents and the development of osteoporosis in adulthood. The specific needs of children and adolescents with eating disorders are not considered.

Adolescent↗

PubMed1998

Intestinal secretory factor released by macrophages stimulated with Clostridium difficile toxin A: role of interleukin 1beta.

Clostridium difficile toxin A is associated with enterocolitis in animals and humans. However, the mechanisms of its secretory and damaging effects are not totally understood. In this work, we examined the intestinal secretion of electrolytes and water caused by supernatants from macrophages stimulated with toxin A in rabbit ileal mucosa mounted in Ussing chambers. We also investigated the mechanism by which the intestinal secretory factor (ISF) is released from stimulated macrophages. Supernatants from macrophages stimulated with toxin A caused potent intestinal secretion (change in short-circuit current [DeltaIsc], 76 microA x cm-2; P < 0.01). The release of the ISF was pertussis toxin sensitive (reduction, 61%; P < 0.01) and was also reduced (P < 0.05) by a protein synthesis inhibitor (67%), protease inhibitors (57%), a phospholipase A2 inhibitor (54%), a cyclo-oxygenase inhibitor (62%), a dual cyclo- and lipoxygenase inhibitor (48%), a platelet-activating factor (PAF) receptor antagonist (55%), and tumor necrosis factor alpha (TNF-alpha) synthesis inhibitors (48%). However, this release was not inhibited by a lipo-oxygenase inhibitor. Monoclonal anti-interleukin 1beta (IL-1beta) but not anti-IL-1alpha antibody blocked (72%; P < 0.01) the secretory action of the ISF, as did recombinant human IL-1 receptor antagonist (80%; P < 0.01). High levels of IL-1beta (3,476 pg/ml) were detected by an enzyme-linked immunosorbent assay in the above supernatants. Furthermore, the addition of IL-1beta to the serosal side caused a potent secretory effect (DeltaIsc, 80 microA x cm-2; P < 0.01). These results show that macrophages stimulated with toxin A release an ISF capable of provoking intestinal secretion. The regulation of this factor is dependent upon the activation of the G protein. In addition, prostaglandins, PAF, and TNF-alpha are involved in the release of the ISF. We conclude that IL-1beta is probably the ISF released by macrophages in response to toxin A.

Animals↗

PubMed1998

Histopathological analysis of rat mesentery as a method for evaluating neutrophil migration: differential effects of dexamethasone and pertussis toxin.

In the present study, histopathological analysis of rat mesentery was used to quantify the effect of two anti-inflammatory agents, dexamethasone (Dex) and pertussis toxin (Ptx), on leukocyte migration. The intravenous injection of Dex (1 mg/kg) and Ptx (1,200 ng) 1 h prior to the intraperitoneal injection of the inflammatory stimuli lipopolysaccharide (LPS) or formyl-methionyl-leucyl-phenylalanine (fMLP) significantly reduced the neutrophil diapedesis (LPS: Ptx = 0.86 +/- 0.19 and Dex = 0.35 +/- 0.13 vs saline (S) = 2.85 +/- 0.59; fMLP: Ptx = 0.43 +/- 0.09 and Dex 0.01 +/- 0.01 vs S = 1.08 +/- 0.15 neutrophil diapedesis/field) and infiltration (LPS: Ptx = 6.29 +/- 1.4 and Dex = 3.06 +/- 0.76 vs S = 15.94 +/- 3.97; fMLP: Ptx = 3.85 +/- 0.56 and Dex = 0.40 +/- 0.16 vs S = 7.15 +/- 1.17 neutrophils/field) induced by the two agonists in the rat mesentery. The inhibitory effect of Dex and Ptx was clearly visible in the fields nearest the venule (up to 200 microns), demonstrating that these anti-inflammatory agents act preferentially in the transmigration of neutrophils from the vascular lumen into the interstitial space, but not in cell movement in response to a haptotactic gradient. The mesentery of rats pretreated with Dex showed a decreased number of neutrophils within the venules (LPS: Dex = 1.50 +/- 0.38 vs S = 4.20 +/- 1.01; fMLP: Dex = 0.25 +/- 0.11 vs S = 2.20 +/- 0.34 neutrophils in the lumen/field), suggesting that this inhibitor may be acting at a step that precedes neutrophil arrival in the inflamed tissue. In contrast to that observed with Dex treatment, the number of neutrophils found in mesenteric venules was significantly elevated in animals pretreated with Ptx (LPS: Ptx = 9.85 +/- 2.25 vs S = 4.20 +/- 1.01; fMLP: Ptx = 4.66 +/- 1.24 vs S = 2.20 +/- 0.34 neutrophils in the lumen/field). This discrepancy shows that Ptx and Dex act via different mechanisms and suggests that Ptx prevents locomotion of neutrophils from the vascular lumen to the interstitial space. In conclusion, the method described here is useful for quantifying the inflammatory and anti-inflammatory effect of different substances. The advantage of this histopathological approach is that it provides additional information about the steps involved in leucocyte migration.

Animals↗

PubMed1997

Fecal lactoferrin, interleukin-1beta, and interleukin-8 are elevated in patients with severe Clostridium difficile colitis.

Twenty-two patients with Clostridium difficile colitis as determined by positive enzyme immunoassay for toxin A were evaluated for fecal inflammatory markers and their relationship to the severity of illness. Fourteen of 22 specimens were positive for fecal lactoferrin (FLF), with titers from 1:50 to 1:800. Nine of 10 stools tested had ratios of interleukin-1beta (IL-1beta) to IL-1 receptor antagonist (IL-1ra) of >0.01. Seventeen of 22 specimens also had elevated IL-8 concentrations, and 12 of 14 had elevated IL-1beta concentrations. A review of the 18 available patient records revealed that fecal IL-8 concentrations, IL-1beta/IL-1ra ratios, and FLF titers were significantly higher in patients with moderate to severe disease than in patients with mild disease. These findings suggest that the proinflammatory effects of C. difficile may directly influence clinical characteristics of human disease.

Adult↗

PubMed1997

Role of pertussis toxin A subunit in neutrophil migration and vascular permeability.

The anti-inflammatory activity of pertussis toxin (Ptx) was compared to that of a noncatalytic mutant of pertussis toxin (9K/129G; Ptxm), which contains two amino acid substitutions in the A protomer, by using a rat model of inflammation. The toxins were administered intravenously 1 h prior to the injection of inflammatory stimuli. Ptx, but not Ptxm, inhibited neutrophil migration into peritoneal cavities in response to formyl-methionyl-leucyl-phenylalanine and lipopolysaccharide. The inhibitory effect of Ptx on neutrophil migration could not be explained by the ability of the toxin to induce leukopenia or neutropenia. The increase in skin vascular permeability induced by leukotriene B4, a powerful neutrophil chemotactic agent, was also inhibited only by Ptx. On the other hand, the increase in skin vascular permeability induced by histamine was potentiated by both toxins. These data show that Ptx inhibits neutrophil-mediated inflammation in vivo and that this effect is dependent on the ADP-ribosyltransferase activity of the A protomer.

Animals↗

PubMed1996

Inhibition of eosinophil chemotaxis by chronic blockade of nitric oxide biosynthesis.

The effect of chronic N omega-nitro-L-arginine methyl ester (L-NAME) treatment on the in vivo eosinophil migration induced by bradykinin, platelet-activating factor (PAF), lipopolysaccharide and carrageenin has been investigated in the rat using the pleurisy model. The in vitro (microchemotaxis chamber) eosinophil migration induced by N-formyl-methionyl-leucyl-phenylalanine (fMLP), PAF and zymosan-activated serum was also evaluated in the rat. The eosinophils were obtained from the peritoneal cavity of male Wistar rats and isolated on a discontinuous metrizamide gradient. Chronic inhibition of nitric oxide biosynthesis was achieved by adding L-NAME to the drinking water to give an intake of approximately 75 mumol/rat/day for 4 weeks. Rats treated chronically with L-NAME developed a significant level of hypertension (163 +/- 4.8 mmHg; P < 0.01) compared with animals which received either the same dose of the inactive enantiomer D-NAME (124 +/- 3.2 mmHg) or tap water alone (119 +/- 1.6 mmHg). The intrapleural injection of bradykinin (50 micrograms), PAF (1 microgram), lipopolysaccharide (0.25 microgram) and carrageenin (125 micrograms) into untreated rats in vivo induced a significant level of eosinophil migration by 24 h post-injection. This migration was markedly reduced in L-NAME-treated rats. Eosinophils obtained from untreated rats showed a significant level of migration in vitro in response to fMLP (5 X 10(-8) M), PAF (10(-8) M) and zymosan-activated serum (27 microliters). In contrast, the migration induced by these chemotactic agents was markedly reduced in cells isolated from animals treated chronically with L-NAME. L-Arginine (5.5 mM), but not D-arginine (5.5 mM), restored the ability of eosinophils from L-NAME-treated animals to migrate in response to fMLP. Our results indicate that nitric oxide plays a major role in the in vivo and ex vivo migration of eosinophils.

Animals↗

PubMed1996

Milk carnitine affects organ carnitine concentration in newborn rats.

Previous studies suggest that exogenous milk carnitine may be necessary during the suckling period to maintain normal fat metabolism. To characterize the relationship between milk carnitine and carnitine in body organs, newborn rats were fed from birth a rat milk substitute with or without 300 micromol/L L-carnitine, corresponding to the concentration present in rat milk, for either 2 or 4 d. Carnitine concentrations in heart, skeletal muscle, liver and small intestine were compared with levels in rat pups that were never fed (d 0) and those that were nursed by their mothers for 4 d. Carnitine supplementation resulted in significantly higher concentrations of carnitine in all organs studied after 4 d compared with nursed controls. Relative intestinal carnitine pool size was 38.1 +/- 3.0, 22.6 +/- 1.0, 7.9 +/- 0.5 and 2.3 +/- 0.7 micromol/g body wt in supplemented, nursed, unsupplemented and never fed pups, respectively (P < 0.05, compared with one another). These results indicate that carnitine organ concentrations are related to dietary intake during the early suckling period and that the small intestine is a considerable and previously unrecognized proportion of the carnitine pool of suckling animals.

Animals↗

PubMed1995

Partial characterization of the RNA from LPS-stimulated macrophages that induces the release of chemotactic cytokines by resident macrophages.

It is well established that exogenous RNA is incorporated into eukaryotic cells and is able to exert various biological responses. Little, however, is known about the effects of such RNA on macrophages. In this study, we demonstrate that RNA extracted from macrophages stimulated with Escherichia coli lipopolysaccharide (LPS), referred to as L-RNA, in contrast to RNA from non-stimulated macrophages (N-RNA), induces the release of a macrophage-derived neutrophil chemotactic factor (MNCF) and interleukin-8 (IL-8) from macrophage monolayers. The effect of L-RNA was dependent of the integrity of the polynucleotide chain and was not due to LPS contamination since its ability to induce MNCF and IL-8 release was strongly reduced by RNase but was not affected by DNase or polymyxin B. The poly A(+)L-RNA and poly A(-)L-RNA fractions were able to induce the release of MNCF and IL-8, indicating that the L-RNA could be acting at transcriptional and translational levels. The demonstration that actinomycin-D and cycloheximide inhibited the release of MNCF and IL-8 by L-RNA-stimulated macrophages confirms this assumption. Fractionation of the total L-RNA by centrifugation on a 5-20% sucrose gradient showed that the L-RNA which sediments in the 4-5S region of the gradient is the only fraction capable of inducing the release of MNCF from naive macrophages. We have previously shown that macrophage monolayers stimulated with interleukin-1 beta or LPS release a low molecular RNA which also sediments in the same 4-5S region. Taken together, these results support our proposal that resident macrophages, when activated by injurious stimuli, in addition to secreting cytokines, also release a low molecular weight (4-5S) RNA which may act on the surrounding macrophages to further stimulate the release of cytokines. This process would amplify the inflammatory response and would increase the mechanisms involved in the defense response or tissue injury.

Animals↗