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Biomedical subjects

D Bani

Publications and source records attributed to D Bani.

At least 19 recordsLinked to original sources
PubMed2005

Protection from cardiac injury by induction of heme oxygenase-1 and nitric oxide synthase in a focal ischaemia-reperfusion model.

The enzymes heme oxygenase (HO) generate carbon monoxide (CO) in living organisms during heme degradation. Carbon monoxide has recently been shown to dilate blood vessels and to possess anti-inflammatory properties. It is also known that nitric oxide (NO) donors ameliorate cardiac ischaemia-reperfusion injury in experimental models of global or focal ischaemia-reperfusion (FIR). The two gaseous mediators share the same mechanism of action via the stimulation of soluble guanylyl cyclase and the increase in cellular levels of cyclic GMP. We studied the effects of manipulating the HO system and the possible interaction between CO and NO in an experimental in vivo model of FIR in the rat heart. FIR-subjected rats had necrotic area in the left ventricle, ventricular arrhythmias and a shortening of survival time in comparison to sham-operated animals. Resident mast cells underwent a heavy degranulation, malonyldialdehyde was produced by myocardial cell membranes, and tissue calcium levels were increased. High levels of myeloperoxidase were also detected, suggesting a FIR-related inflammatory process. In animals pre-treated with the HO-1 inducer, hemin, all the biochemical and morphometric markers of FIR were minimized or fully abated. Consistently, the biochemical and morphometric markers of FIR were reversed in rats treated with the HO-1 blocker, ZnPP-IX, prior to hemin administration. Pre-treatment with hemin significantly increases the expression and activity of both cardiac HO-1 and iNOS, suggesting that CO and NO cooperate in the cardioprotective effect against FIR-induced damage, and that there is a therapeutic synergism between NO-donors and CO-releasing molecules, via the common stimulation of increase in cGMP levels and decrease in calcium overload.

Animals↗
PubMed2005

Atomic force microscopy of histological sections using a chemical etching method.

Physiology and pathology have a big deal on tissue morphology, and the intrinsic spatial resolution of an atomic force microscope (AFM) is able to observe ultrastructural details. In order to investigate cellular and subcellular structures in histological sections with the AFM, we used a new simple method for sample preparation, i.e. chemical etching of semithin sections from epoxy resin-embedded specimens: such treatment appears to melt the upper layers of the embedding resin; thus, removing the superficial roughness caused by the edge of the microtome knife and bringing into high relief the biological structures hidden in the bulk. Consecutive ultrathin sections embedded in epoxy resin were observed with a transmission electron microscope (TEM) to compare the different imaging properties on the same specimen sample. In this paper we report, as an example, our AFM and TEM images of two different tissue specimens, rat pancreas and skeletal muscle fibres, showing that most of the inner details are visible with the AFM. These results suggest that chemical etching of histological sections may be a simple, fast and cost-effective method for AFM imaging with ultrastructural resolution.

Animals↗
PubMed2004

Relaxin potentiates the expression of inducible nitric oxide synthase by endothelial cells from human umbilical vein in in vitro culture.

The hormone relaxin (RLX), which can be detected in human venous cord blood, has been shown to be a potent vasodilator, acting through increased expression of inducible nitric oxide synthase (NOS II) and nitric oxide (NO) generation. This study aims at clarifying whether RLX, at concentrations of 100 and 1000 ng/ml for 6 or 12 h of exposure, can influence the expression of NOS isoforms in human umbilical vein endothelial cells (HUVEC) cultured in vitro. NOS mRNA expression was studied by quantitative real-time RT-PCR, NOS protein expression and activity was studied by Western blot and nitrite assay, and immunoreactive NOS localization was performed by confocal microscopy. Untreated HUVEC expressed all the NOS isoforms, especially the constitutive, endothelial-type NOS III and, to a lesser extent, NOS II and NOS I. RLX-treated cells showed an increased expression of NOS II, attaining a maximum with 1000 ng/ml RLX, which gave rise to increased NO generation, as shown by nitrite assay. This effect of RLX appears to be mediated by activation of NOS II transcription factor NF-kappaB, since it was abolished by the NF-kappaB inhibitors curcumin-95 and dexamethasone. These findings suggest that RLX in the umbilical vein might contribute to the NO-dependent regulation of vascular tone.

Cells, Cultured↗
PubMed2002

Myenteric neurons and interstitial cells of Cajal of mouse colon express several nitric oxide synthase isoforms.

Information on equipment and subcellular distribution of nitric oxide synthase (NOS) isoforms in myenteric neurons and pacemaker cells (ICC) might help to identify nitric oxide (NO) pathway(s) acting on gastrointestinal motility. In sections of mouse colon labelled with neuronal (n)NOS, endothelial (e)NOS and inducible (i)NOS antibodies, all myenteric neurons co-expressed eNOS and iNOS and a subpopulation of them co-expressed nNOS. ICC co-expressed nNOS and eNOS. In the neurons, nNOS-labeling was intracytoplasmatic, in the ICC at cell periphery. In both cell types, eNOS-labeling was on intracytoplasmatic granules, likely mitochondria. In conclusion, myenteric neurons and ICC co-express several NOS isoforms with specific subcellular distribution. Different nNOS splice variants are presumably present: intracytoplasmatic nNOSbeta and nNOSalpha producing neurogenic NO, plasma membrane-bound nNOSalpha producing ICCgenic NO. eNOS might be implicated in mitochondrial respiration and, in ICC, also in pacemaker activity. Neurons express iNOS also in basal condition.

Alternative Splicing↗
PubMed2002

Protective effect of relaxin in cardiac anaphylaxis: involvement of the nitric oxide pathway.

1 Relaxin (RLX) is a multifunctional hormone best known for its role in pregnancy and parturition, that has been also shown to influence coronary perfusion and mast cell activation through the generation of endogenous nitric oxide (NO). In this study we report on the effects of RLX on the biochemical and mechanical changes of ex vivo perfused hearts isolated from ovalbumin-sensitized guinea-pigs induced by challenge with the specific antigen. The possible involvement of NO in the RLX action has been also investigated. 2 A 30-min perfusion with RLX (30 ng ml(-1)) before ovalbumin challenge fully abated the positive chronotropic and inotropic effects evoked by anaphylactic reaction to the antigen. RLX also blunted the short-term coronary constriction following to antigen challenge. Conversely, perfusion with chemically inactivated RLX had no effect. 3 The release of histamine in the perfusate and the accumulation of calcium in heart tissue induced by antigen challenge were significantly decreased by RLX, while the amounts of nitrites in the perfusate were significantly increased, as were NO synthase activity and expression and cGMP levels in heart tissue. 4 These findings indicate that RLX has a protective effect in cardiac anaphylaxis which involves an up-regulation of the NO biosynthetic pathway.

Anaphylaxis↗
PubMed2002

Ultrastructural abnormalities of muscle spindles in the rat masseter muscle with malocclusion-induced damage.

Human temporomandibular disorders due to disturbed occlusal mechanics are characterized by sensory, motor and autonomic symptoms, possibly related to muscle overwork and fatigue. Our previous study in rats with experimentally-induced malocclusion due to unilateral molar cusp amputation showed that the ipsilateral masseter muscles undergo morphological and biochemical changes consistent with muscle hypercontraction and ischemia. In the present study, the masseter muscle spindles of the same malocclusion-bearing rats were examined by electron microscopy. Sham-operated rats were used as controls. In the treated rats, clear-cut alterations of the muscle spindles were observed 26 days after surgery, when the extrafusal muscle showed the more severe damage. The fusal alterations affected predominantly capsular cells, intrafusal muscle fibers and sensory nerve endings. These results suggest that in the malocclusion-bearing rats, an abnormal reflex regulation of the motor activity of the masticatory muscles may take place. They also allow us to hypothesize that muscle spindle alterations might be involved in the pathogenesis of human temporomandibular disorders.

Animals↗
PubMed2001

Relaxin causes changes of the liver. In vivo studies in rats.

During pregnancy, the liver undergoes metabolic adjustments directed to fulfil the needs of the mother and the growing fetus. This study was designed to verify whether relaxin, a hormone related to pregnancy, may induce histochemical and ultrastructural modifications of hepatocytes which can be related to metabolic changes. Estrogen-primed female rats were treated with relaxin (10 microg in repository vehicle) for 18 h. Additional male rats were treated with relaxin (10 microg/day in PBS) for 4 days. Appropriate vehicle-treated rats were used as controls. After fasting, the rats were killed and liver fragments were processed for light and electron microscopy and for computer-assisted morphometry of PAS-positive glycogen deposits and acid phosphatase-reactive organelles. In both sexes, the relaxin-treated rats underwent a significant decrease in the amount of glycogen in the hepatocytes as compared with the controls. These changes were accompanied by an increase in smooth endoplasmic reticulum, endocytosis vesicles and lysosomes. These findings show that relaxin promotes glycogen depletion and induces morphological changes of hepatocytes which are consistent with functional activation. It is suggested that relaxin might play an important role in hepatic metabolic adjustments occurring during pregnancy.

Animals↗
PubMed2001

Dantrolene counteracts the masseter muscle damage induced by artificial occlusal wear: studies in a rat model.

In previous studies, we showed that the introduction of occlusal alterations to rats results in masseter muscle abnormalities. Here, we investigate whether administration of the muscle relaxant dantrolene to rats with occlusal alteration could counteract the occurrence of such abnormalities. Rats underwent unilateral amputation of molar cusps to cause malocclusion. Some rats received dantrolene (10 mg/kg/day subcutaneously). The masseter muscles ipsilateral to the amputated molars were excised 26 days later. Sham-operated rats were used as controls. The tissue samples were studied by light and electron microscopy and morphometry. Moreover, tissue Ca2+ content, an index of muscle injury, was determined. In the absence of dantrolene, occlusal alteration leads to microvessel constriction, morphologic damage of masseter muscle fibers and blood capillaries, and elevation of tissue Ca2+ content. These changes were nearly abrogated by dantrolene, thus supporting it as a possible new therapeutic tool for the treatment of malocclusion-induced muscle diseases.

Analysis of Variance↗
PubMed2001

The vasorelaxant hormone relaxin induces changes in liver sinusoid microcirculation: a morphologic study in the rat.

This study shows that specialized contractile endothelial cells exist in rat liver sinusoids which may be involved in the local control of hemodynamics and which are sensitive to vasoactive agents, including the vasorelaxant hormone relaxin. Male rats were treated with 10 microg relaxin for 4 days; phosphate-buffered saline (PBS)-treated rats were the controls. For comparison, rats treated with relaxin together with the NO-synthase inhibitor N(omega)-nitro-l -arginine methyl ester (L-NAME), and rats treated with the vasodilator taurodeoxycholic acid or the vasoconstrictor ethanol were investigated. Liver fragments were studied morphologically and morphometrically. In the control rats, peculiar contractile cells were present in the endothelial lining. These cells had abundant myofilaments and formed cytoplasmic blebs projecting into and often occluding the lumen. In the ethanol-treated rats, sinusoids were constricted and filled with cytoplasmic blebs. In the relaxin-treated rats, sinusoids were markedly dilated and the cytoplasmic blebs nearly disappeared. Similar findings were observed in the taurodeoxycholic acid-treated rats. The effects of relaxin were blunted by L-NAME, suggesting that the relaxin action involves an NO-mediated mechanism.

Animals↗
PubMed2000

Mechanical stretch reveals different components of endothelial-mediated vascular tone in rat aortic strips.

1. Since the role of mechanical stretches in vascular tone regulation is poorly understood, we studied how stretch can influence endothelial tone. 2. Isometric contractions of isolated rat aortic helical strips were recorded. The resting tension was set at 0.7 g, 1.2 g or 2.5 g. Endothelium-preserved strips were precontracted with either phenylephrine or prostaglandin F(2 alpha) (PGF(2 alpha)). 3. In control conditions, acetylcholine (ACh) dose-dependently relaxed phenylephrine-precontracted strips independently of resting tension. 4. At 0.7 g resting tension, nitric oxide synthase (NOS) inhibitors did not reduce ACh-induced relaxation, while either a guanylyl cyclase inhibitor or a NO trapping agent prevented it. At 1.2 g and 2.5 g resting tensions, NOS inhibitors shifted the ACh dose-response curve to the right. 5. After preincubation with indomethacin (5 microM) or ibuprofen (10 and 100 microM), at 0.7 g and 1.2 g resting tensions, ACh induced an endothelium-dependent, dose-dependent contraction. ACh (10(-6) M) increased the contraction up to two times greater the phenylephrine-induced one. Lipoxygenase inhibitors prevented it. At high stretch, the ACh vasorelaxant effect was marginally influenced by cyclooxygenase (COX) inhibition. Similar results were obtained when aortic strips were precontracted with PGF(2 alpha). 6. Our data indicate that when resting tension is low, ACh mobilizes a stored NO pool that, synergistically with COX-derived metabolites, can relax precontracted strips. COX inhibition up-regulates the lipoxygenase metabolic pathway, accounting for the ACh contractile effect. At an intermediate resting tension, NO production is present, but COX inhibition reveals a lipoxygenase-dependent, ACh-induced contraction. At high resting tension, NO synthesis predominates and COX metabolites influence ACh-induced relaxation marginally.

Acetylcholine↗
PubMed1999

Relaxin favors the development of activated human T cells into Th1-like effectors.

Differentiation of naive CD4+ helper T (Th) cells into Th1 or Th2 effectors, as characterized by their opposite pattern of cytokine production, can be influenced by several factors, including hormones. In this study, we demonstrate that porcine relaxin, at concentrations ranging from 10(-10) to 10(-6) M, favors the in vitro development of human antigen-specific T cells into Th1-like effectors and enhances both IFN-gamma mRNA expression and IFN-gamma production by established human T cell clones. The promoting effect of relaxin on the development of IFN-gamma-producing cells was not due to a relaxin-induced release of IL-12 and/or IFN-alpha by antigen-presenting cells. These results suggest that relaxin may contribute to the regulation of the immune homeostasis during pregnancy and may also play some role in counteracting Th2-dominated disorders.

Animals↗
PubMed1999

Relaxin promotes differentiation of human breast cancer cells MCF-7 transplanted into nude mice.

Previous studies showed that the hormone relaxin acts on human breast cancer MCF-7 cells in vitro by modulating cell proliferation and promoting cell differentiation toward a duct epithelial phenotype. The present study was designed to investigate whether relaxin retains these properties when acting in vivo on MCF-7 cell tumors developed in athymic nude mice. Mice bearing MCF-7 cell tumors transplanted under the mammary fat pad and estrogenized to sustain tumor growth were treated systemically with relaxin (10 microg/day) for 19 days. Vehicle-treated mice were used as controls. Thirty days later, the mice were sacrificed and tumor fragments were analyzed by light and electron microscopy and immunocytochemistry. Measurements of tumor volume were recorded weekly for the overall experimental period. The results obtained indicate that relaxin treatment promotes differentiation of tumor cells towards both myoepithelial-like and epithelial-like cells, as judged by the ultrastructural features of the cells and by the increased expression of smooth muscle actin and cadherins. Measurements of tumor size and of the number of cycling cells show that relaxin, at the doses and times of exposure used in this study, does not significantly influence tumor growth and cell proliferation.

Actins↗
PubMed1999

Morphologic and biochemical changes of the masseter muscles induced by occlusal wear: studies in a rat model.

Occlusal alterations may result in changes in the functional performance of masticatory muscles. In this study, we set up an experimental model in rats to examine whether masticatory muscle abnormalities occur after a malocclusion is induced. Rats underwent unilateral amputation of the molar cusps to simulate an occlusal wear situation. The masseter muscles ipsilateral and contralateral to the amputated molars were excised at different experimental times. Sham-operated rats were used as controls. The tissue samples were studied by light and electron microscopy and morphometry. Tissue calcium content, a biochemical index of muscle injury, was also determined. The results show that occlusal dysfunction leads to microvessel constriction and clear-cut morphologic damage of muscular fibers and blood capillary endothelium, as well as to elevation of tissue calcium content, in the ipsilateral masseter muscle. These changes are likely related to muscle fatigue and ischemia. The early signs of injury do not involve the entire muscle but are mostly restricted to tissue areas rich in type I (slow) muscle fibers, which are characterized by a predominantly aerobic metabolism. The muscle damage becomes more extended and severe with time. On the other hand, the contralateral muscles show only slight alterations which are reversible with time, possibly due to an adaptive response.

Analysis of Variance↗
PubMed1999

Relaxin up-regulates the nitric oxide biosynthetic pathway in the mouse uterus: involvement in the inhibition of myometrial contractility.

The uterus is a site of nitric oxide (NO) production and expresses NO synthases (NOS), which are up-regulated during pregnancy. NO induces uterine quiescence, which is deemed necessary for the maintenance of pregnancy. Relaxin is known to promote uterine quiescence. Relaxin has also been shown to stimulate NO production in several targets. In this study we investigated the effects of relaxin on the NO biosynthetic pathway of the mouse uterus. Estrogenized mice were treated with relaxin (2 microg) for 18 h, and the uterine horns were used for determination of immunoreactive endothelial-type NOS and inducible NOS. Moreover, uterine strips from estrogenized mice were placed in an organ bath, and the effect of relaxin on K+-induced contracture was evaluated in the presence or absence of the NOS inhibitor nitro-L-arginine. Relaxin increases the expression of endothelial-type NOS in surface epithelium, glands, endometrial stromal cells, and myometrium, leaving inducible NOS expression unaffected. Moreover, relaxin inhibits myometrial contractility, and this effect is blunted by nitro-L-arginine, thus indicating that the L-arginine-NO pathway is involved in the relaxant action of relaxin on the myometrium. Because relaxin is elevated during pregnancy, it is suggested that relaxin has a physiological role in the up-regulation of uterine NO biosynthesis during pregnancy.

Animals↗
PubMed1998

Relaxin activates the L-arginine-nitric oxide pathway in vascular smooth muscle cells in culture.

The peptide hormone relaxin (RLX) has been shown to elicit a powerful vasodilatory response in several target organs. This response is mediated by the stimulation of intrinsic nitric oxide (NO) generation. The present study was designed to clarify whether RLX directly promotes the relaxation of vascular smooth muscle cells through stimulation of NO generation. Vascular smooth muscle cells from bovine aortas were incubated with RLX at concentrations ranging from 1 nmol/L to 1 micromol/L. The expression and activity of NO synthase, production of NO, and the intracellular levels of cGMP and Ca2+ were determined. The cell morphology and signal transduction mechanisms of these bovine aortic smooth muscle cells in response to RLX were also studied. RLX stimulated the expression of immunoreactive inducible NO synthase and increased significantly and in a concentration-related fashion inducible NO synthase activity, NO generation, and intracellular cGMP levels. Concurrently, RLX significantly decreased cytosolic Ca2+ concentrations and caused changes in cell shape and the actin cytoskeleton that were consistent with cell relaxation. The signal transduction mechanisms leading to the enhanced expression of inducible NO synthase protein and activity caused by RLX involve the activation of tyrosine kinase, phosphatidylcholine-phospholipase C, and the transcription factor nuclear factor-kappaB, similar to bacterial endotoxins and proinflammatory cytokines. This study suggests that RLX is an endogenous agent capable of regulating vascular tone by activation of the L-arginine-NO pathway in vascular smooth muscle cells.

Analysis of Variance↗