PubMed Health⌕ Search

Biomedical subjects

A Messina

Publications and source records attributed to A Messina.

At least 37 records · Page 2Linked to original sources
PubMed2002

Comparing the efficacy of two fluorescent retrograde tracers in labeling the motor and sensory neuron populations of the rat sciatic nerve.

We compared the efficacy with which the fluorescent tracers Fast Blue (FB) and Diamidino Yellow (DY) retrogradely label neutrons. Trace crystals were applied to the sciatic nerve exclusively (single label) or serially (double label). Unbiased cell counts showed that FB and DY label similar numbers of motoneurons (P=1.00, df 5) or DRG neurons (P=0.95, df 5) when applied exclusively. Plotting of motoneurons revealed a similar pattern of distribution of FB and DY labeled neurons. When the tracers were applied serially, 79% of labeled motoneurons and 77% of labeled DRG neurons were double-labeled irrespective of which tracer was applied first. Equal proportions of the remaining labeled neurons were single-labeled with FB or DY. These data show that FB and DY label equal numbers of motor and sensory neurons of the sciatic nerve following exclusive or serial application of tracers. These findings support the use of FB and DY together in serial fluorescent labeling experiments.

Amidines↗
PubMed2002

Antigen-induced airway inflammation in the Brown Norway rat results in airway smooth muscle hyperplasia.

Asthma is characterized by chronic airways inflammation, airway wall remodeling, and airway hyperresponsiveness (AHR). An increase in airway smooth muscle has been proposed to explain a major part of AHR in asthma. We have used unbiased stereological methods to determine whether airway smooth muscle hyperplasia and AHR occurred in sensitized, antigen-challenged Brown Norway (BN) rats. Ovalbumin (OA)-sensitized BN rats chronically exposed to OA aerosol displayed airway inflammation and a modest level of AHR to intravenously administered ACh 24 h after the last antigen challenge. However, these animals did not show an increase in smooth muscle cell (SMC) number in the left main bronchus, suggesting that short-lived inflammatory mechanisms caused the acute AHR. In contrast, 7 days after the last aerosol challenge, there was a modest increase in SMC number, but no AHR to ACh. Addition of FCS to the chronic OA challenge protocol had no effect on the degree of inflammation but resulted in a marked increase in both SMC number and a persistent (7-day) AHR. These results raise the possibility that increases in airway SMC number rather than, or in addition to, chronic inflammation contribute to the persistent AHR detected in this model.

Acetylcholine↗
PubMed2001

Immunosenescence: a review.

Aging involves the morphological and functional integrity of all organs, including the cellular and humoral immunological functions. The main alterations can be listed as follows: (i) Thymic involution resulting in the decreased number of lymphoid precursor T- and B-cells. (ii) Reduced proliferative capacity of T-cells; loss of lymphocyte subgroups as a consequence of the shortening of telomeres. (iii) Qualitative deficiency of B-lymphocytes with a reduced response to exogenous antigens. (iv) Compromised activity of the accessory cells, both directly by depressing the chemotactic and phagocytic responses, and indirectly by increasing the prostaglandin production which inhibit the proliferation of T-cells. (v) Alterations in the production and secretion of various cytokines. (vi) Other factors like the general physiological conditions, the nutritional state, psychological habit and various hormone levels.

Journal Article↗
PubMed2001

Inducible nitric oxide synthase (iNOS) activity promotes ischaemic skin flap survival.

We have examined the role of nitric oxide (NO) in a model of functional angiogenesis in which survival of a skin flap depends entirely on angiogenesis to provide an arterial blood supply to maintain tissue viability. The different effects of nitric oxide synthase (NOS) inhibitors on rat skin flap survival appeared to be explained on the basis of their NOS isoform selectivity. Skin flap survival was decreased by iNOS-selective (inducible NOS) inhibitors, S-methyl-isothiourea, aminoguanidine and aminoethylthiorea; unaffected by the non-selective inhibitor nitro-imino-L-ornithine; and enhanced by the cNOS (constitutive NOS, that is endothelial NOS (eNOS) and neuronal NOS (nNOS)) inhibitor, nitro-L-arginine methyl ester. Skin flap survival was reduced in mice with targeted disruption of the iNOS gene (iNOS knockout mice), and the administration of nitro-L-arginine methyl ester significantly increased flap survival in iNOS knockout mice (P<0.05). iNOS immunoreactivity was identified in mast cells in the angiogenic region. Immunoreactive vascular endothelial growth factor (VEGF) and basic fibroblast growth factor were also localized to mast cells. The combination of interferon-gamma and tumour necrosis factor-alpha induced NO production and increased VEGF levels in mast cells cultured from bone marrow of wild-type, but not iNOS KO mice. The increased tissue survival associated with the capacity for iNOS expression may be related to iNOS-dependent enhancement of VEGF levels and an ensuing angiogenic response. Our results provide both pharmacological and genetic evidence that iNOS activity promotes survival of ischaemic tissue.

Animals↗
PubMed2001

Stimulating effect of an arteriovenous shunt on the in vivo growth of isografted fibroblasts: a preliminary report.

Isogenous fibroblasts derived from the skin of inbred Sprague-Dawley rats were cultured in vitro, labeled with bisbenzamide (BB) or carboxyfluorescein diacetate (CFDA), and seeded into polycarbonate growth chambers. After 24 h incubation in vitro, the chambers, either empty or containing an arteriovenous (AV) shunt, were implanted subcutaneously into the inguinal region of Sprague-Dawley rats and examined by fluorescence microscopy 2 or 7 days later. The AV shunt remained patent in all experiments. The density of labeled cells on the chamber surface in all chambers decreased in the first 2 days after insertion. At 7 days, the cell density in the empty chambers had not altered from the 2-day level, but the density in the AV shunt containing chambers had increased to almost three times the day 2 level (p = 0.013). It appears that an AV shunt can induce a significant proliferation of fibroblasts implanted adjacent to it. For at least 7 days after labeling, BB and CFDA provide a simple and effective method of quantitative detection of implanted fibroblasts. It is concluded that nutrients from the AV shunt implanted in a growth chamber result in a significant increase in the number of viable, matrix-synthesizing cells, compared with AV shunt-free controls.

Animals↗
PubMed2001

The influence of extracellular matrix on the generation of vascularized, engineered, transplantable tissue.

In a recently described model for tissue engineering, an arteriovenous loop comprising the femoral artery and vein with interposed vein graft is fabricated in the groin of an adult male rat, placed inside a polycarbonate chamber, and incubated subcutaneously. New vascularized granulation tissue will generate on this loop for up to 12 weeks. In the study described in this paper three different extracellular matrices were investigated for their ability to accelerate the amount of tissue generated compared with a no-matrix control. Poly-D,L-lactic-co-glycolic acid (PLGA) produced the maximal weight of new tissue and vascularization and this peaked at two weeks, but regressed by four weeks. Matrigel was next best. It peaked at four weeks but by eight weeks it also had regressed. Fibrin (20 and 80 mg/ml), by contrast, did not integrate with the generating vascularized tissue and produced less weight and volume of tissue than controls without matrix. The limiting factors to growth appear to be the chamber size and the capacity of the neotissue to integrate with the matrix. Once the sides of the chamber are reached or tissue fails to integrate, encapsulation and regression follow. The intrinsic position of the blood supply within the neotissue has many advantages for tissue and organ engineering, such as ability to seed the construct with stem cells and microsurgically transfer new tissue to another site within the individual. In conclusion, this study has found that PLGA and Matrigel are the best matrices for the rapid growth of new vascularized tissue suitable for replantation or transplantation.

Animals↗
PubMed2000

Characterization of the human porin isoform 1 (HVDAC1) gene by amplification on the whole human genome: A tool for porin deficiency analysis.

The deficiency of porin isoform 1 (HVDAC1) in human skeletal muscle has been associated with a pathological phenotype related to defects in the bioenergetic metabolism. In the best studied case, porin deficiency was not apparent in cultured fibroblasts: this observation raised the conclusion that no molecular defect was in the cDNA sequence coding for the protein. To get more insight in the pathogenetic mechanism that is involved in porin isoform 1 deficiency, we have determined the whole structure of the corresponding human gene. On the basis of the corresponding mouse gene structure and the human cDNA sequence, we designed long extension PCR amplifications using the whole genomic DNA as a template. Exonic/intronic regions were isolated and the exons and surrounding introns sequenced. The 5' and 3' extremities of the gene were determined by genome walking. The porin isoform 1 human gene is made up of 9 exons and spans about 33 kbp. A whole panel of PCR parameters was set and is now ready to be used for specific amplification upon patients' genomic DNA. The analysis of the putative promoter sequence was performed. It revealed the presence of a sterol Repressor element (SRE), an SRY, the testis-determining factor, and a nuclear respiratory factor 2 (NRF-2) binding site. These sites, according to results from literature, could be involved in the functional modulation of the gene expression.

3' Untranslated Regions↗
PubMed2000

Requirements for obtaining unbiased estimates of neuronal numbers in frozen sections.

The use of frozen sectioning is a convenient and rapid means of observing the results obtained using fluorescent retrograde tracers. Quantitation of these results using the biased stereological methods currently available can be associated with large errors. A recently developed stereological tool, the optical dissector, provides unbiased and efficient results, however, the requirements for its use in frozen sections has not previously been established. In this study, a comparison was made of neuron numbers, estimated using the optical dissector method, in the motoneuron pool retrogradely labelled from the rat sciatic nerve with either Fast Blue or Tetramethylrhodamine dextran (fluoro-ruby) in methacrylate embedded and frozen spinal cord specimens. Despite over 50% shrinkage in the frozen sections, compared with virtually no shrinkage in the methacrylate sections, no significant difference in labelled motoneuron numbers was observed, provided this shrinkage was taken into account. Correction for section shrinkage is therefore essential in order to use the optical dissector with confidence to count fluorescent labelled neurons in frozen tissue.

Amidines↗
PubMed2000

The interferon regulatory factors 1 and 2 bind to a segment of the human c-myb first intron: possible role in the regulation of c-myb expression.

The preferential expression of the protooncogene c-myb in hematopoietic cells is in part regulated by a mechanism of transcriptional block in the first intron. By electrophoresis mobility shift assays using probes corresponding to different segments of the putative human c-myb intron 1 transcription pause region and nuclear extracts from myeloid leukemia HL 60 and fibroblast WI 38 cells, we detected a HL-60-specific DNA-protein complex with a 123-bp fragment containing binding sites for the interferon regulatory factors (IRFs) nuclear proteins. Formation of the DNA-protein complex was abrogated by competition with an oligomer containing the wild-type, but not the mutated, IRF binding site and the complex was specifically supershifted by the anti-IRF-1 or the anti-IRF-2 antibody. Moreover, in vitro translated IRF-1 or IRF-2 protein did interact with the 123-bp c-myb intron 1 fragment. Upon TPA-induced differentiation, c-myb expression was readily down-modulated in parental HL 60 cells, but not in cells transfected with an antisense IRF-1 plasmid. Moreover, chloramphenicol acetyltransferase activity driven by a c-myb promoter containing the entire intron 1 was suppressed upon IRF-1, but not IRF-2 expression. Together, these results are consistent with the existence of a functional relationship between IRF-1 and c-myb in which IRF-1 negatively regulates c-myb expression at the transcriptional level by a mechanism that may depend on the interaction of IRF-1 with a segment of the c-myb gene implicated in transcription pausing.

Animals↗
PubMed2000

The role of mast cells in ischaemia-reperfusion injury in murine skeletal muscle.

To determine the role of mast cells in ischaemia-reperfusion (IR) injury to skeletal muscle, W(f)/W(f) mast cell-deficient and their corresponding wild-type mice were subjected to 70 min tourniquet ischaemia and 24 h reperfusion. As measured by nitroblue tetrazolium (NBT) staining, muscle viability was 9% in wild-type and 94% in mast cell-deficient animals (p<0.001). Assay of residual lactate dehydrogenase activity within the injured muscle (p<0.05) and histological examination confirmed the greater muscle necrosis in treated wild-type than in treated mast cell-deficient mice. There was no significant difference in the degree of neutrophil infiltration, tissue myeloperoxidase content or water content of IR-injured muscle in the two mouse phenotypes. To determine further the role of mast cells in IR injury, wild-type mice were treated 30 min prior to reperfusion with an intraperitoneal dose of either saline or the mast cell-stabilizing agent lodoxamide trometamol (2.5, 7.5, 25 or 75 mg/kg). Twenty-four hours after removal of the tourniquet, saline-treated gastrocnemius muscle had a mean viability of 14% compared with 28% (p<0.05) and 48% (p<0.01) after 25 mg/kg and 75 mg/kg of lodoxamide treatment, respectively. The ability of lodoxamide to stabilize mast cells was confirmed by histological examination. Ischaemic muscle reperfused for 1 h showed much less degranulation of mast cells in mice pretreated with lodoxamide (50 mg/kg) than in saline-treated controls. These findings suggest that mast cells are a major source of mediators of necrosis in IR injury to skeletal muscle.

Animals↗
PubMed2000

Effects of LIF dose and laminin plus fibronectin on axotomized sciatic nerves.

Leukemia inhibitory factor (LIF), a cytokine which has neurotrophic and myotrophic activities, has been shown to enhance nerve regeneration and consequent return of muscle function in the entubulation model of sciatic nerve repair. Fibronectin (FN) and laminin (LN) are two extracellular matrix (ECM) components that, when combined, promote axon growth in the entubulation model. The aim of this study was to determine the optimal LIF dose and the efficacy of FN plus LN administered either alone or simultaneously with the optimal LIF dose. We found that at 12 weeks following nerve repair, a single 10 ng LIF dose produced the largest medial gastrocnemius (MG) muscle mass (P < 0.0001) and maximum force contraction (P < 0.001). The diameter of the axons in the FN plus LN group were significantly greater than for saline (P < 0.001) and the LIF dose groups (P < 0.01). When 10 ng LIF was combined with FN plus LN, the MG muscle mass was significantly greater than the optimal LIF dose (P < 0.05), suggesting an additive effect. Our findings support the view that combinations of factors, which perhaps act on complementary mechanisms for nerve regeneration, will be required to maximally potentiate nerve regeneration and return of muscle function after nerve injury.

Animals↗
PubMed2000

[Vascularized surgical rotation of a bi-articular trapezoid-trapeziometacarpal complex for the treatment of severe rhizarthrosis of the thumb].

UNLABELLED: A new surgical procedure has been conceived to avoid persistent pain and to restore the functionality and pinch strength of the basal joint of the thumb destroyed by degenerative osteoarthritis. Since January 1998 a double total joint transposition was performed on eight patients, switching the trapezoid-metacarpal joint and the trapezio-metacarpal joint. A 180 degrees rotation of the bi-articular complex (trapezoid-trapezio-metacarpal joints) in its entirety was achieved, while preserving the intrinsic ligaments and vascular supply insured by the dorsal branch of the radial artery; the Cardan conformation in Physics of the trapezoid-metacarpal joint provided complete thumb motion. TECHNIQUE: skin dorso-radial approach of the wrist; arteriolysis of the dorsal branch of the radial artery at the anatomic snuff box and at its entrance into the first intermetacarpal space; metaphyseal osteotomy of the first and second metacarpal; capsulotomy all around the bi-articular complex; transfer and rotation of the trapezoid-trapezio-metacarpal bi-articular complex together with the dorsal branch of radial artery; osteotomy stabilisation by Kirschner wires; capsulo-ligamentous reconstruction; plaster slab immobilisation. Four weeks later the thumb moves actively; hand therapy starts six weeks post-operatively. Clinical and radiological controls were performed at two, four and six weeks, tomography at three months post-operation. Clinical assessment for three patients showed three good results and for the other five showed excellent outcomes, resulting in complete motion, stability of the first metacarpal and restored painless pinch strength of the thumb. Today the trapezoid-metacarpal joint seems to ensure pain relief, mobility and to solve the instability due to the collapse of the thumb column by restoring the bone chain of the first metacarpal ray.

Bone Wires↗
PubMed2000

Extramitochondrial porin: facts and hypotheses.

Mitochondrial porin, or VDAC, is a pore-forming protein abundant in the outer mitochondrial membrane. Several publications have reported extramitochondrial localizations as well, but the evidence was considered insufficient by many, and the presence of porin in nonmitochondrial cellular compartments has remained in doubt for a long time. We have now obtained new data indicating that the plasma membrane of hematopoietic cells contains porin, probably located mostly in caveolae or caveolae-like domains. Porin was purified from the plasma membrane of intact cells by a procedure utilizing the membrane-impermeable labeling reagent NH-SS-biotin and streptavidin affinity chromatography, and shown to have the same properties as mitochondrial porin. A channel with properties similar to that of isolated VDAC was observed by patch-clamping intact cells. This review discusses the evidence supporting extramitochondrial localization, the putative identification of the plasma membrane porin with the "maxi" chloride channel, the hypothetical mechanisms of sorting porin to various cellular membrane structures, and its possible functions.

Animals↗
PubMed2000

Characterization of channel-forming activity in muscle biopsy from a porin-deficient human patient.

A bioptic specimen from the muscles of a patient suffering from severe myopathy was inspected for the presence of human porin 31HL. Western blotting suggested that the specimen was free of the most abundant eukaryotic porin 31HL (HVDAC1). The specimen was treated with detergent and the soluble protein fraction was passed through a dry hydroxyapatite column. The passthrough of this column was inspected for channel formation in artificial lipid-bilayer membranes. The channel observed under these conditions had a single-channel conductance of about 2.5 nS in 1 M KCl, was cation selective, and was found to be virtually voltage independent. Experiments with a control specimen from a healthy human being, without any indication for muscle myopathy, revealed the presence of the voltage-dependent porin 31HL in the sample. It is discussed whether the patient's bioptic specimen contained another human porin, which has not been studied to date in its natural environment.

Biopsy↗
PubMed2000

Localization of inducible nitric oxide synthase to mast cells during ischemia/reperfusion injury of skeletal muscle.

Nitric oxide contributes to tissue necrosis after ischemia-reperfusion (IR). A biochemical and immunohistochemical study was made of the amounts and localization of both Ca++-independent nitric oxide synthase (NOS) II and Ca++-dependent (NOS I and NOS III) in rat skeletal muscle after ischemia and 0.5, 2, 8, 16, and 24 hours reperfusion. NOS II was not detectable in control muscle or during ischemia, was first detected after 2 hours reperfusion, increased further by 8 hours, and remained elevated at 24 hours. Both NOS II and nitrotyrosine, a marker of peroxynitrite formation, were localized exclusively to mast cells except after 24 hours reperfusion when some macrophages and neutrophils also showed positive immunoreactivity. Mast cells underwent extensive degranulation during reperfusion. NOS I was not detected in injured or control muscle. The level of NOS III, which was localized to the endothelium of blood vessels of all sizes in control muscle, decreased progressively during ischemia and reperfusion to reach undetectable levels after 16 hours reperfusion. These findings indicate that most of the nitric oxide formed during IR injury is generated by NOS II located almost exclusively in mast cells.

Animals↗
PubMed2000

A Lost Realm in the Internal Domains of the Betic-Rif Orogen (Spain and Morocco): Evidence from Conglomerates and Consequences for Alpine Geodynamic Evolution.

The Malaguide-Ghomaride Complex is capped by Upper Oligocene-Aquitanian clastic deposits postdating early Alpine orogenesis but predating the main tectonic-metamorphic evolution, end of nappe emplacement, unroofing, and exhumation of the metamorphic units of the Betic-Rif Orogen. Two conglomerate intervals within these deposits are characterized by clasts of sedimentary, epimetamorphic, and mafic volcanic rocks derived from Malaguide-Ghomaride units and by clasts of acidic magmatic and orthogneissic rocks of unknown provenance, here studied. Magmatic rocks originated from late-Variscan two-mica cordierite-bearing granitoids and, subordinately, from aplitic dikes. Orthogneisses derive from similar plutonic rocks but are affected by an Alpine metamorphic overprint evolving from greenschist (T=510&j0;-530 degrees C and P=5-6 kbar) to low-temperature amphibolite facies (T>550&j0;C and P<3 kbar). Such a plutonic rock suite is unknown in any Betic-Rif unit or in the basement of the Alboran Sea, and the metamorphic evolution in the orthogneisses is different from (and older than) that of Alpujarride-Sebtide rocks to which they were formerly ascribed. Magmatic and metamorphic rocks very similar to those studied characterize the basements of some Kabylia and Calabria-Peloritani units. Therefore, the source area is a currently lost continental-crust realm of Calabria-Peloritani-Kabylia type, located to the ESE of the Malaguide-Ghomaride Domain and affected by a pre-latest Oligocene Alpine metamorphism. Increasingly active tectonics transformed this realm into rising areas from which erosion fed small subsiding synorogenic basins formed on the Malaguide-Ghomaride Complex. This provenance analysis demonstrates that all these domains constituted a single continental-crust block until Aquitanian-Burdigalian times, before its dispersal around nascent western Mediterranean basins.

Journal Article↗