Epiglotitis aguda en el adulto. Presentación de varios casos clínicos / Acute epiglottitis in adult. Presentation of several clinical cases

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Antinuclear antibodies: a marker associated with steroid dependence in patients with ulcerative colitis.

BACKGROUND: The autoimmune phenomena and the autoantibody profile have acquired great importance in ulcerative colitis (UC). Few studies have explored antinuclear antibodies (ANAs) prevalence, but not its association with steroid dependence. We hypothesized that ANAs could be a factor associated to steroid dependence. METHODS: Ninety-seven consecutive patients with UC were included. ANA titers and staining patterns were determined by indirect immunofluorescence. Gender, age, follow-up time, C-reactive protein (CRP), disease extent, Mayo Score Activity Index, extraintestinal manifestations, and steroid dependence were analyzed in univariate and multivariate models. RESULTS: Ninety-seven patients were included and 49 (50.5%) were females; mean age was 41.7 +/- 22.2 years. Positivity for ANAs was encountered in 52 (53.5%) patients, and none for anti-dsDNA. The prevalence of ANAs was higher in steroid-dependent than in nonsteroid-dependent patients (77.8% versus 48.1%, P = 0.020; odds ratio [OR] = 3.8, 95% confidence interval [CI] 1.1-12.5), and in those with uveitis (100% versus 51.1%; P = 0.040) or pyoderma gangrenosum (100% versus 51.6%; P = 0.078). No association was observed with gender, age, CRP, disease extent, and Mayo Score Activity Index. The multiple regression analysis model showed an association between steroid dependence and ANAs (P = 0.033, OR = 3.9, 95% CI 1.4-14.9). CONCLUSIONS: ANAs are associated with steroid dependence in UC patients. Further studies are required to determine the role of ANAs as serological markers for prediction of steroid dependence in order to perform early therapeutic interventions with biological agents.

Overexpression of UCP3 in cultured human muscle lowers mitochondrial membrane potential, raises ATP/ADP ratio, and favors fatty acid vs. glucose oxidation.

The skeletal muscle mitochondrial uncoupling protein-3 (UCP3) promotes substrate oxidation, but direct evidence for its metabolic role is lacking. Here, we show that UCP3 overexpression in cultured human muscle cells decreased mitochondrial membrane potential (DYm). Despite this, the ATP content was not significantly decreased compared with control cells, whereas ADP content was reduced and thus the ATP/ADP ratio raised. This finding was contrasts with the effect caused by the chemical protonophoric uncoupler, CCCP, which lowered DYm, ATP, and the ATP/ADP ratio. UCP3-overexpression enhanced oxidation of oleate, regardless of the presence of glucose, whereas etomoxir, which blocks fatty acid entry to mitochondria, suppressed the UCP3 effect. Glucose oxidation was stimulated in UCP3-overexpressing cells, but this effect was inhibited by oleate. UCP3 caused weak increase of both 2-Deoxyglucose uptake and glycolytic rate, which differed from the marked stimulation by CCCP. We concluded that UCP3 promoted nutrient oxidation by lowering DYm and enhanced fatty acid-dependent inhibition of glucose oxidation. Unlike the uncoupler CCCP, however, UCP3 raised the ATP/ADP ratio and modestly increased glucose uptake and glycolysis. We propose that this differential effect provides a biological significance to UCP3, which is up-regulated in metabolic stress situations where it could be involved in nutrient partitioning.

Crystal structure and preferred conformation of beta-lactams derived from (S)-1-arylethyl isocyanates and vinyl ethers.

The configurational analysis of beta-lactams prepared from [2 + 2] cycloaddition of vinyl ethers to pure enantiomers of 1-arylethyl isocyanates was carried out by high resolution 1H NMR. The addition of a chiral shift reagent revealed that the most important conformation of the studied beta-lactams in solution is that in which the methine proton, of the exocyclic stereogenic carbon, points towards the carbonyl oxygen atom. Since the configuration of the stereogenic exocyclic carbon is known, the orientation of the aromatic ring allows the correlation of the chemical shifts with the absolute configuration of the new stereogenic centers. This method is particularly useful to establish the stereochemistry of oily beta-lactams having the N-(1-arylethyl) group. The X-ray crystallographic analysis carried out with (1R,5S)-7-[(1S)-1-(1-naphthyl) ethyl]-2-oxa-7-azabicyclo[3.2.0]heptan-6-one, is consistent with the proposed model for beta-lactams in solution.

Identification of an aspartic residue in the P-loop of the vanilloid receptor that modulates pore properties.

Vanilloid receptor subunit 1 (VR1) is a nonselective cation channel that integrates multiple pain-producing stimuli. VR1 channels are blocked with high efficacy by the well established noncompetitive antagonist ruthenium red and exhibit high permeability to divalent cations. The molecular determinants that define these functional properties remain elusive. We have addressed this question and evaluated by site-specific neutralization the contribution on pore properties of acidic residues located in the putative VR1 pore region. Mutant receptors expressed in Xenopus oocytes exhibited capsaicin-operated ionic currents akin to those of wild type channels. Incorporation of glutamine residues at Glu(648) and Glu(651) rendered minor effects on VR1 pore attributes, while Glu(636) slightly modulated pore blockade. In contrast, replacement of Asp(646) by asparagine decreased 10-fold ruthenium red blockade efficacy and reduced 4-fold the relative permeability of the divalent cation Mg(2+) with respect to Na(+) without changing the selectivity of monovalent cations. At variance with wild type channels and E636Q, E648Q, and E651Q mutant receptors, ruthenium red blockade of D646N mutants was weakly sensitive to extracellular pH acidification. Collectively, our results suggest that Asp(646) is a molecular determinant of VR1 pore properties and imply that this residue may form a ring of negative charges that structures a high affinity binding site for cationic molecules at the extracellular entryway.

Calpain-3 gene expression is decreased during experimental cancer cachexia.

The Yoshida AH-130 rat ascites hepatoma is a model system for studying the mechanisms involved in the protein hypercatabolism associated with cancer cachexia. The present study was aimed at investigating if the calpain-3 gene expression in skeletal muscle was affected by tumor growth. The results presented clearly show that calpain-3 gene expression is considerably reduced in experimental cancer cachexia, while there is a reciprocal change in the expression of the ubiquitin-dependent proteolytic system and in the ubiquitous m-calpain. The results, observed during cancer cachexia, suggest a potential counterregulatory role of calpain-3 in muscle proteolysis.

Angiogenesis induced in muscle by a recombinant adenovirus expressing functional isoforms of basic fibroblast growth factor.

The present work studies the effects of a replication-deficient adenovirus (Ad), Ad-RSVbFGF, bearing the human basic fibroblast growth factor (bFGF) cDNA, as a potential vector for therapeutic angiogenesis of ischemic diseases. The different isoforms of the protein were expressed from the viral vector in various cell types and, although the cytoplasmic isoform does not possess a signal peptide, we observed its release from a muscle cell line. The proteins were fully functional when tested in a long-term survival assay of quiescent fibroblasts. After endothelial cell infection with Ad-RSVbFGF, we observed an 80&percnt increase in the mean length of the capillary-like tubes that differentiated in a three-dimensional model of angiogenesis. We evaluated angiogenesis directly in mice 14 days after subcutaneous injection of Matrigel plugs containing Ad-RSVbFGF. A marked neovascularization was observed in the Matrigel plugs and in the surrounding tissues. Finally, the recombinant virus was injected into the hindlimb muscles of mdx mice. A 2.5-fold increase in bFGF content of the muscle was observed 6 days after injection, without any significant variations detected in the animal sera. Immunohistological detection showed an increased number of large-caliber vessels in the treated muscles as compared with control muscles. These results demonstrate that Ad-mediated transfer of the human bFGF gene can induce angiogenesis in muscle, making this tissue a potential target for the treatment of ischemic diseases.

Ubiquitin gene expression is increased in human muscle undergoing neurogenic involvement.

Histological features of neurogenic muscle involvement included type grouping, muscle fiber atrophy, and target fibers. In muscles with myofiber atrophy and target fibers, we found an increased expression of the genes encoding for the ubiquitin-ATP-dependent proteolytic system. Thus, in patients with target fibers, a 5.2- and a 3.9-fold increase were observed for the 2.4 and 1.2 kb transcripts, respectively, while in those with atrophic angulated hyperoxidative fibers, a 3.9- and a 4.4-fold increase were observed for the 2.4 and 1.2 kb transcripts, respectively. It is suggested that the activation of this proteolytic system may be responsible for the skeletal muscle alterations that often accompany human muscle neurogenic involvement.

beta-D-glucuronidase gene from Escherichia coli is a functional reporter in the methylotrophic yeast Pichia pastoris.

The Escherichia coli gene gusA was expressed in the methylotrophic yeast Pichia pastoris in a transcriptional fusion to the homologous methanol-inducible AOX1 promoter. Four recombinant clones were selected for expression studies in shake flask conditions and beta-D-glucuronidase (beta-GUS) activity was assayed each 24 h during the induction period. Regardless of the genomic integration patterns and the gene dosage, beta-GUS was functionally expressed and easily detected in all studied clones. The results obtained demonstrate the feasibility of using this bacterial enzyme as a reporter in Pichia pastoris.

Ubiquitin and proteasome gene expression is increased in skeletal muscle of slim AIDS patients.

Human biopsies obtained from skeletal muscle of cachectic AIDS patients clearly showed an increased expression (in relation to that of healthy subjects) of the genes encoding for the ubiquitin-ATP-dependent proteolytic system. Increases of 120% and 42% were observed for the 2.4 and 1.2 kb ubiquitin transcripts, respectively. The expression of the C8 proteasome subunit was also increased by 60% in the cachectic AIDS patients in relation to the healthy control subjects. It is suggested that the activation of this proteolytic system (possibly via changes in circulating cytokines, such as TNF) may be responsible for the skeletal muscle waste that often accompanies AIDS.

Role of TNF receptor 1 in protein turnover during cancer cachexia using gene knockout mice.

The implantation of the Lewis lung carcinoma (a fast-growing mouse tumour that induces cachexia) to both wild-type and gene-deficient mice for the TNF-alpha receptor type I protein (Tnfr1 degree/Tnfr1 degree), resulted in a considerable loss of carcass weight in both groups. However, while in the wild-type mice there was a loss of both fat and muscle, in the gene-knockout mice muscle wastage was not affected to the same extent. In both groups, tumour burden resulted in significant increases in circulating TNF-alpha, a cytokine which, as we have previously demonstrated, can induce protein breakdown in skeletal muscle. Muscle wastage in wild-type mice was accompanied by an increase in the fractional rate of protein degradation, while no changes were observed in protein synthesis. The result is a decreased rate of protein accumulation that accounts for the muscle weight loss observed as a result of tumour burden. In contrast, gene knockout mice did not have significantly lower rates of protein accumulation as a result of tumour implantation. The increase in protein degradation in the tumour-bearing wild mice was accompanied by an enhanced expression of both ubiquitin and proteasome subunit genes, all of them related to the activation of the ATP-dependent proteolytic system in skeletal muscle. Tumour-bearing gene-deficient mice did not show any increase in gene expression. It is concluded that TNF-alpha (alone or in combination with other cytokines) is responsible for the activation of protein breakdown in skeletal muscle of tumour-bearing mice.

Protein turnover in skeletal muscle of tumour-bearing transgenic mice overexpressing the soluble TNF receptor-1.

The implantation of the Lewis lung carcinoma (a fast-growing mouse tumour that induces cachexia) to both wild-type and transgenic mice for the soluble TNF receptor type I protein (sTNF-R1) resulted in a considerable loss of carcass weight in both groups. However, while in the wild-type mice there was a loss of both fat and muscle, in the transgenic mice muscle waste was not affected to the same extent as in the wild-type group. Muscle waste in wild-type mice was accompanied by an increase in the fractional rate of protein degradation, while no changes were observed in protein synthesis. The result was a decreased rate of protein accumulation which accounted for the muscle weight loss observed as a result of the tumour burden. In contrast, transgenic mice did not have such low rates of protein accumulation after tumour implantation. The increase in protein degradation in the tumour-bearing transgenic mice was accompanied by a similar increase in protein synthesis which compensated for the loss of muscle protein by degradation. Both tumour-bearing groups showed an enhanced expression of ubiquitin and proteasome C8 subunit genes, all of them related to the activation of the ATP-dependent proteolytic system in skeletal muscle. It is suggested that TNF may, in part, be responsible for the loss of protein in skeletal muscle of tumour-bearing mice.

Different cytokines modulate ubiquitin gene expression in rat skeletal muscle.

Intravenous administration of different cytokines caused important changes in the expression of ubiquitin genes in skeletal muscle. Tumour necrosis factor-alpha caused a 2.2- and 1.9-fold increase in the expression of the 2.4 and 1.2 kb transcripts, respectively. Administration of interferon-gamma also caused a 2.2- and 1.8-fold increase in the 2.4 and 1.2 kb transcripts, respectively. While administration of leukaemia inhibitory factor and interleukin-6 resulted in no changes in ubiquitin gene expression, interleukin-1 administration also caused an increase in both ubiquitin gene transcripts (2.8- and 1.9-fold for the 2.4 and 1.2 kb transcripts, respectively). The results suggest that some of the cytokine effects on the ubiquitin system gene expression could be related to the enhanced skeletal muscle proteolysis found during cancer cachexia and other pathological states.

Lipid metabolism in tumour-bearing mice: studies with knockout mice for tumour necrosis factor receptor 1 protein.

The implantation of the Lewis lung carcinoma (a fast-growing mouse tumour that induces cachexia) to both wild-type and gene-deficient mice for the tumour necrosis factor (TNF) receptor type I protein (Tnfr1(0)/Tnfr1(0)), resulted in a considerable loss of carcass (26%) and white (77%) and brown adipose (37%) tissue weights in the wild-type mice, while it induced much less marked effects in the gene-deficient mice. Tumour burden also inflicted an important decrease in total lipoprotein lipase (LPL) activity in epididymal white adipose tissue (50%) in the wild-type mice while no changes were observed in the knockout mice. In addition, all tumour-bearing animals were clearly hypertriglyceridaemic (80% increase in circulating triacylglycerols in wild-type and 36% in knockout mice). It is concluded that although TNF seems to be to some extent responsible for adipose waste, LPL changes and hyperlipaemia (via receptor I), the role of other cytokines (alone or in combination with TNF) in promoting changes in lipid metabolism during cancer cachexia cannot be discarded.

Protein architecture of avian reovirus S1133 and identification of the cell attachment protein.

There are a number of discrepancies in the literature regarding the protein composition of the avian reoviruses. The present study demonstrates that avian reovirus S1133 contains at least 10 proteins (lambdaA, lambdaB, lambdaC, muA, muB, muBC, muBN, sigmaA, sigmaB, and sigmaC). Polypeptides muB, muBC, muBN, sigmaB, and sigmaC are components of the outer capsid layer of the virus, while lambdaA, lambdaB, muA, and sigmaA are core polypeptides. Protein lambdaC is a component of both layers, extending from the inner core to the outer capsid. The minor outer-capsid polypeptide sigmaC is shown to be the cell attachment protein, since it is the only viral polypeptide present in extracts of S1133-infected cells that binds specifically to chicken embryo fibroblasts; furthermore, its binding to avian cells was competitively inhibited by S1133 reovirions but not by mammalian reovirions. Our results also show that sigmaC is an oligomeric protein both in the virion and free in the cytoplasm, and preliminary results suggest that the multimer is made up of three monomeric units.

TNF can directly induce the expression of ubiquitin-dependent proteolytic system in rat soleus muscles.

Incubation of isolated rat soleus muscles in the presence of human recombinant TNF-alpha (10,000 U/ml) resulted in an important increase in ubiquitin gene expression (over 50%). Although previous studies involving cytokine administration in vivo (1) have demonstrated an action on ubiquitin-dependent proteolysis, this is the first report demonstrating a direct action of the cytokine on protein breakdown in incubated rat skeletal muscle.

Is TNF really involved in cachexia?

A review on the possible involvement of tumor necrosis factor-alpha (TNF) in cachexia is presented. While this cytokine is definitely linked to sepsis and tumor-associated weight loss in some experimental models, other cytokines, such as interleukin-6 (IL-6) or interferon-gamma (IFN-gamma), alone or in combination with TNF, may also play an important role in the development of cachexia.

Anti-TNF treatment reverts increased muscle ubiquitin gene expression in tumour-bearing rats.

Implantation of the ascitic tumour Yoshida AH-130 hepatoma (a cachectic tumour) resulted in important increases in muscle ubiquitin gene expression. Administration of daily injections of 25 mg/kg b.w. polyclonal goat anti-murine TNF IgG preparation to tumour-bearing rats abolished the increase in muscle ubiquitin gene expression observed in the control (non-anti-TNF-treated) tumour-bearing rats. It is concluded that TNF can have an important role in the activation of the ubiquitin-dependent proteolytic system during tumour growth.