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M Cappello

Publications and source records attributed to M Cappello.

At least 37 records · Page 2Linked to original sources
PubMed1998

Ancylostoma caninum anticoagulant peptide blocks metastasis in vivo and inhibits factor Xa binding to melanoma cells in vitro.

We evaluated the in vivo anti-metastatic activity of recombinant Ancylostoma caninum Anticoagulant Peptide (rAcAP), a potent (Ki = 265 pM) and specific active site inhibitor of human coagulation factor Xa originally isolated from bloodfeeding hookworms. Subcutaneous injection of SCID mice with rAcAP (0.01-0.2 mg/mouse) prior to tail vein injection of LOX human melanoma cells resulted in a dose dependent reduction in pulmonary metastases. In order to elucidate potential mechanisms of rAcAP's anti-metastatic activity, experiments were carried out to identify specific interactions between factor Xa and LOX. Binding of biotinylated factor Xa to LOX monolayers was both specific and saturable (Kd = 15 nM). Competition experiments using antibodies to previously identified factor Xa binding proteins, including factor V/Va, effector cell protease receptor-1, and tissue factor pathway inhibitor failed to implicate any of these molecules as significant binding sites for Factor Xa. Functional prothrombinase activity was also supported by LOX, with a half maximal rate of thrombin generation detected at a factor Xa concentration of 2.4 nM. Additional competition experiments using an excess of either rAcAP or active site blocked factor Xa (EGR-Xa) revealed that most of the total factor Xa binding to LOX is mediated via interaction with the enzyme's active site, predicting that the vast majority of cell-associated factor Xa does not participate directly in thrombin generation. In addition to establishing two distinct mechanisms of factor Xa binding to melanoma, these data raise the possibility that rAcAP's antimetastatic effect in vivo might involve novel non-coagulant pathways, perhaps via inhibition of active-site mediated interactions between factor Xa and tumor cells.

Animals↗
PubMed1997

Experimental analysis of neuronal dynamics in cultured cortical networks and transitions between different patterns of activity.

Experimental investigation of the dynamics of biological networks is a fundamental step towards understanding how the nervous system works. Spontaneous activity in cultured networks of cortical neurons has been investigated by using a multisite recording technique with planar electrode arrays. In these networks, the spatiotemporal firing patterns were studied in the presence of different extracellular solutions. Transitions from asynchronous firing dynamics to synchronous firing dynamics were observed when the extracellular Ca2+ concentration was increased from 0.1 mM to 1 mM. Addition of extracellular Mg2+ reduced the spontaneous activity at any Ca2+ concentration, and an increase in the extracellular K+ concentration enhanced the frequency of periodical synchronous bursts. N-methyl-D-aspartate (NMDA) and non-NMDA glutamate receptor antagonists inhibited synchronous activity. A spatiotemporal analysis of the data has been performed, and the properties of the network such as the synchronization and the periodicity have been quantified in order to clarify how variations of intrinsic parameters of the network can induce structural transitions in the neural dynamics. This experimental study is a possible approach to investigate the computational properties of a neuronal network.

Animals↗
PubMed1997

Actions of the inspiratory intercostal muscles in flail chest.

We have previously shown in dogs that the ribs in flail chest move paradoxically inward during inspiration but continue to move cranially. We have also shown that flail elicits, probably via an increased activation of the muscle spindles, a threefold to fourfold increase in external intercostal inspiratory EMG activity without inducing any changes in parasternal intercostal activity. Therefore, the present studies were undertaken to test the hypothesis that the persistent cranial motion of the fractured ribs resulted primarily from the action of the external intercostals. A flail was induced in seven supine anesthetized animals by fracturing both dorsally and ventrally ribs 3 to 6 on the right side of the chest, after which the external intercostal muscles in interspaces 1 to 7 were severed. Severing the external intercostals caused a small increase in the inspiratory inward displacement of the fractured ribs, from 2.76 +/- 0.31 to 3.25 +/- 0.38 mm (p < 0.05), but it did not affect the parasternal intercostal EMG activity or the cranial rib displacement (before, 3.61 +/- 1.03 mm; after, 3.22 +/- 1.43 mm; NS). However, when the parasternal intercostals in interspaces 1 to 7 were also denervated, the inspiratory inward displacement of the ribs increased markedly to 5.95 +/- 0.48 mm (p < 0.01), and their inspiratory cranial displacement was reversed into a 1.05 +/- 0.58 mm inspiratory caudal displacement (p < 0.01). We conclude, therefore, that in dogs with flail chest the respiratory displacements of the ribs are still primarily determined, besides pleural pressure, by the action of the parasternal intercostals. These observations also suggest that in anesthetized dogs, spindle-induced excitation of the external intercostals has little impact on the mechanical behavior of the ribs.

Animals↗
PubMed1996

Anticoagulant repertoire of the hookworm Ancylostoma caninum.

Hookworms are hematophagous nematodes that infect a wide range of mammalian hosts, including humans. There has been speculation for nearly a century as to the identity of the anticoagulant substances) used by these organisms to subvert host hemostasis. Using molecular cloning, we describe a family of potent small protein (75-84 amino acids) anticoagulants from the hookworm Ancylostoma caninum termed AcAP (A. caninum anticoagulant protein). Two recombinant AcAP members (AcAP5 and AcAP6) directly inhibited the catalytic activity of blood coagulation factor Xa (fXa), while a third form (AcAPc2) predominantly inhibited the catalytic activity of a complex composed of blood coagulation factor VIIa and tissue factor (fVIIa/TF). The inhibition of fVIIa/TF was by a unique mechanism that required the initial formation of a binary complex of the inhibitor with fXa at a site on the enzyme that is distinct from the catalytic center (exo-site). The sequence of AcAPc2 as well as the utilization of an exo-site on fXa distinguishes this inhibitor from the mammalian anticoagulant TFPI (tissue factor pathway inhibitor), which is functionally equivalent with respect to fXa-dependent inhibition of fIIa/TF. The relative sequence positions of the reactive site residues determined for AcAP5 with the homologous regions in AcAP6 and AcAPc2 as well as the pattern of 10 cysteine residues present in each of the inhibitors suggest that the AcAPs are distantly related to the family of small protein serine protease inhibitors found in the nonhematophagous nematode Ascaris lumbricoides var. suum.

Amino Acid Sequence↗
PubMed1996

Ancylostoma caninum anticoagulant peptide: cloning by PCR and expression of soluble, active protein in E. coli.

Ancylostoma caninum Anticoagulant Peptide (AcAP) is the major anticoagulant activity present in extracts of adult Ancylostoma caninum hookworms. This 8.7 kDa protein is a potent and specific inhibitor of human coagulation factor Xa. Using PCR, we have isolated a cDNA encoding for AcAP from an adult A. caninum cDNA library. The 5' end of the AcAP cDNA was identified by reverse transcription PCR (RT-PCR) using A. caninum cDNA and a 5' primer corresponding to a nematode spliced leader sequence. The AcAP cDNA was expressed in E. coli using a prokaryotic expression vector, and the recombinant fusion protein (rAcAP) was purified to homogeneity using nickel resin affinity chromatography and reverse phase HPLC. Purified rAcAP is comparable to the native protein in inhibitor activity, with an apparent equilibrium inhibitory dissociation constant (Ki*) for the inhibition of factor Xa of 265 +/- 71 pM. The purified protein also prolongs the prothrombin and partial thromboplastic times of human plasma in a dose dependent manner.

Amino Acid Sequence↗
PubMed1996

On the mechanism of the mediolateral gradient of parasternal activation.

Recent studies have shown that in spontaneously breathing dogs the parasternal intercostals are activated according to a mediolateral gradient. To assess the mechanism of this regionalization of activity, we assessed the pattern of activation of these muscles after section of the dorsal roots and examined the topographic distribution of the muscle fiber types from the sternum to the chondrocostal junctions. The pattern of parasternal activity after dorsal rhizotomy was similar in all respects to that previously observed in intact animals. Thus activity in the medial parasternal bundles at the onset of inspiration frequently preceded activity in the middle bundles, and no activity was recorded from the lateral bundles. The amount of medial activity, when expressed as a percentage of the activity recorded during supramaximal tetanic stimulation of the internal intercostal nerve (maximal activity), was also consistently greater than the amount of middle activity (52.6 +/- 4.6 vs. 23.1 +/- 2.6% maximal activity; P < 0.001). Furthermore, the medial, middle, and lateral parasternal bundles had a higher proportion of slow-twitch oxidative fibers than of fast-twitch oxidative-glycolytic fibers; no topographic difference in fiber type distribution was observed. We conclude, therefore, that the mediolateral gradient of parasternal activity is probably due to the unequal distribution of central inputs throughout the pool of alpha-motoneurons.

Animals↗
PubMed1996

Respiratory muscle response to flail chest.

We have previously shown that flail chest in the dog causes an inspiratory inward displacement of the ribs and an increased inspiratory activity in the external intercostal muscles, and we have speculated that this increased activity is due to an increased spindle afferent activity. The present studies were designed to test this hypothesis. Twenty-nine supine anesthetized dogs were studied, and flail was produced surgically by fracturing ventrally and dorsally two to four contiguous ribs on the right side of the chest. Although flail elicited an increased inspiratory activity in the external intercostal and levator costae muscles in the disconnected segment of the rib cage, it did not alter the inspiratory activity in the diaphragm and parasternal intercostals. Expiratory activity in the triangularis sterni, internal intercostals, and transversus abdominis remained unchanged also, as did the inspiratory activity in the external intercostals on the left side of the chest. After flail, the normal inspiratory shortening of the external intercostal muscles in the disconnected segment was also reversed into an inspiratory muscle lengthening. However, when the fractured ribs were connected to the adjacent ribs so that the external intercostals were prevented from lengthening during inspiration, external intercostal and levator costae inspiratory activity was unaltered. These observations support the hypothesis that the increased external intercostal muscle activity seen in flail chest results primarily from an increased activation of the muscle spindles.

Animals↗
PubMed1996

Molecular approaches to vaccinating against hookworm disease.

Anthelminthic drug chemotherapy has failed as an acceptable approach to hookworm control in the less developed countries of the tropics. The development of a genetically engineered vaccine against hookworm infection would be a major advance in our efforts to control this parasitic disease. We have produced several lead recombinant hookworm vaccine antigens. Their development is based on scientific principles that were generated almost 70 years ago when investigators first began to attenuate living infective hookworm larvae. Those early studies on attenuated live vaccines highlighted the importance of secreted larval antigens for eliciting protective immunity in dogs challenged with Ancylostoma caninum. The two major secreted larval antigens have been recently identified as Ancylostoma secreted protein-1 (ASP-1) and ASP-2. The predicted amino acid sequences of the ASP cDNAs together with experimental immunogenicty data using the expressed recombinant protein suggest that the ASPs are promising vaccine antigens. Preliminary hookworm challenge data in mice immunized with recombinant ASP-1 helps to validate this assumption. Alternative vaccines based on either genetic immunization (DNA vaccines) or immunization with recombinant molecules expressed from adult hookworm cDNAs are also under evaluation. Optimization of vaccine route, delivery system, and adjuvant formulations will be required before future planned phase I testing in humans. Vaccine development for a target population living in rural areas of less developed countries will require innovative solutions to financing and manufacture.

Amino Acid Sequence↗
PubMed1996

Intrinsic positive end-expiratory pressure during one-lung ventilation for thoracic surgery. The influence of preoperative pulmonary function.

OBJECTIVE: To detect and to quantify intrinsic positive end-expiratory pressure (PEEPi) during thoracic surgery in the dependent lung of patients intubated with a double-lumen endotracheal tube (DLT) in the lateral position. METHODS: Twenty consecutive patients undergoing elective pulmonary resection were anesthetized, paralyzed, and intubated with a DLT. Their lungs were ventilated (Siemens Servo 900 C ventilator; Siemens Elevna; Solna, Sweden) with constant inspiratory flow. Fraction of inspired oxygen, tidal volume (10 mL/kg), frequency (10/min), and inspiratory time/total time (0.33) were kept constant during the study. PEEPi and ventilatory data were measured in the dependent lung in the supine then in the lateral position with a closed hemithorax. The obtained data were analyzed according to the presence (group PH) or absence (group N) of pulmonary hyperinflation determined from the preoperative pulmonary function data as higher than 120% of predicted value of functional residual capacity (FRC) and residual volume (RV). DATA ANALYSIS: In the dependent lung of patients in group PH (n = 11), PEEPi was present in the supine (n = 8) and in the lateral (n = 11) positions in the range of 1 to 10 cm H2O. In group N (n = 9), PEEPi was detected in one patient and only in the supine position. In the whole group of 20 patients, the preoperative value of FRC (% predicted) and RV (% predicted) was statistically significantly correlated to the presence of PEEPi, whereas the preoperative FEV1 (% predicted) was poorly related to PEEPi in both positions. There was no significant correlation between the value of PaCO2 and PEEPi during one-lung ventilation (OLV) but patients in group PH had a significantly higher PaCO2 during OLV than group N (p = 0.012). CONCLUSIONS: In patients with chronic obstructive lung disease and pulmonary hyperinflation, PEEPi occurs commonly during the period of OLV and only occasionally in patients with normal lungs. As the ventilatory pattern, the size of DLT, and the side of surgery were similar in the two groups of patients, we conclude that the occurrence of PEEPi in our patients was influenced mainly by the preexisting pulmonary hyperinflation and airflow obstruction.

Forced Expiratory Volume↗
PubMed1996

Isolation and characterization of the tsetse thrombin inhibitor: a potent antithrombotic peptide from the saliva of Glossina morsitans morsitans.

A potent and specific inhibitor of the human coagulation protease thrombin was identified in salivary gland extracts of the tsetse fly, Glossina morsitans morsitans, an important vector of African trypanosomiasis. This low molecular weight peptide (MW = 3,530 Da as determined by laser desorption mass spectrometry) was purified using a combination of size-exclusion chromatography and reverse-phase, high-performance liquid chromatography, respectively. Amino terminal sequencing of the purified protein reveals no homology to any previously identified serine protease inhibitor or naturally occurring anticoagulant. The tsetse thrombin inhibitor (TTI) is a stoichiometric inhibitor of thrombin, with an apparent equilibrium dissociation inhibitory constant (Ki*) [corrected] of 584 x 10(-15)M. In addition, it is also a potent inhibitor of thrombin-induced platelet aggregation. Like other hematophagous arthropods, tsetse flies appear to have evolved a novel protease inhibitor capable of antagonizing host hemostasis and facilitating blood feeding.

Amino Acid Sequence↗
PubMed1995

Ancylostoma caninum anticoagulant peptide: a hookworm-derived inhibitor of human coagulation factor Xa.

Human hookworm infection is a major cause of gastrointestinal blood loss and iron deficiency anemia, affecting up to one billion people in the developing world. These soil-transmitted helminths cause blood loss during attachment to the intestinal mucosa by lacerating capillaries and ingesting extravasated blood. We have isolated the major anticoagulant used by adult worms to facilitate feeding and exacerbate intestinal blood loss. This 8.7-kDa peptide, named the Ancylostoma caninum anticoagulant peptide (AcAP), was purified by using a combination of ion-exchange chromatography, gel-filtration chromatography, and reverse-phase HPLC. N-terminal sequencing of AcAP reveals no homology to any previously identified anticoagulant or protease inhibitor. Single-stage chromogenic assays reveal that AcAP is a highly potent and specific inhibitor of human coagulation, with an intrinsic K*i for the inhibition of free factor Xa of 323.5 pM. In plasma-based clotting time assays, AcAP was more effective at prolonging the prothrombin time than both recombinant hirudin and tick anticoagulant peptide. These data suggest that AcAP, a specific inhibitor of factor Xa, is one of the most potent naturally occurring anticoagulants described to date.

Amino Acid Sequence↗
PubMed1995

Response of the inspiratory intercostal [correction of intercoastal] muscles to increased inertial loads.

To test the hypothesis that the external intercostals and levator costae constitute an inspiratory reserve system, we have examined the response of these muscles to increased inertial loads. Weights were t hus attached sequentially to the ribs in ten lightly anesthetized, spontaneously breathing dogs. As weights were attached, the ribs were progressively displaced caudally at end-expiration, so that the external intercostal muscles were lengthened. In addition, the cranial motion of the ribs during inspiration was gradually reduced, the inspiratory shortening of external intercostal disappeared, and the external intercostal and levator costae inspiratory EMG activities increased. The parasternal intercostal inspiratory activity, however, remained unchanged. Studies also showed that: (1) the increases in external intercostal activity appeared with the first loaded breath and disappeared as soon as the load was removed; (2) these increases were related to the suppression of the inspiratory muscle shortening, rather than to the increase in precontraction muscle length or to vagal inputs; and (3) denervation of the external intercostal caused inspiratory muscle lengthening but had little effect on the inspiratory motion of the ribs. These observations thus indicate that increased inertial loads on the ribs trigger reflexes, possibly spindle reflexes, which cause selective increases in external intercostal and levator costae inspiratory EMG activities. In that sense, the present findings are consistent with the idea that these two muscles constitute an inspiratory reserve system. However, it appears that the major effect of these increased activities is simply to prevent the muscles from lengthening during inspiration.

Animals↗
PubMed1995

Dizziness and vertigo in a department of emergency medicine.

Dizziness is a common and vexing diagnostic problem in emergency departments. The term is rather undefinite and often misused, but can in practice be classified into four categories: fainting, disequilibrium, vertigo and miscellaneous syndromes. Vertigo is the most common category of dizziness. Classification of vertigo can be based either on chronological criteria (acute, recurrent or chronic vertigo) or on topographical criteria (peripheral or central vertigo). Physicians working in emergency departments must be able to rapidly identify patients with potentially serious forms of vertigo, which could cause death or disability, and patients with mild conditions, that can be effectively treated. Previous studies and the experience of the authors have shown that reliable diagnostic hypotheses can be generated by taking a proper clinical history (focused on the onset and duration of the disease, the circumstances causing the vertigo and associated otological or neurological symptoms) and performing an accurate physical examination (evaluation of neurological defects and spontaneous or provoked nystagmus), supplemented by few laboratory tests and diagnostic procedures. Therapy of vertigo in emergency settings is mainly symptomatic and based on sedation and use of vestibulosuppressant drugs (antihistamines, phenothiazines).

Algorithms↗
PubMed1995

Rib cage distortion in a canine model of flail chest.

Although blunt chest injuries frequently lead to respiratory failure, the effects of flail chest on the mechanics of breathing have not been evaluated. In the present studies, we have measured the respiratory displacements of the ribs and sternum and the electromyograms (EMG) of the parasternal and external intercostal muscles in eight supine, anesthetized, spontaneously breathing dogs before and after the third to sixth ribs on the right side of the chest were fractured both dorsally and ventrally. After flail, the fractured ribs moved inward, rather than outward, during inspiration, but their inspiratory cranial displacement remained unchanged. The inspiratory outward and caudal displacement of the sternum, the inspiratory EMG activity of the parasternal intercostals, the pattern of breathing, and the arterial blood gases were also unaltered. However, the inspiratory EMG activity recorded from the external intercostals increased consistently to 327 +/- 101% of control (p < 0.05). These observations indicate that with flail chest, the disconnected segment of the rib cage shows paradoxical motion exclusively along the lateral axis; the increased external intercostal activation may account, at least in part, for the persistent inspiratory cranial motion of the ribs. These observations also suggest that the harmful effects of blunt chest injuries are related to pulmonary contusion and pain, rather than to flail chest per se.

Animals↗
PubMed1995

Molecular pathobiology of hookworm infection.

Within the past 2 years, progress has been made in the identification, isolation, and cDNA cloning of several macromolecules from hookworms. While the predicted amino acid sequences of some cDNAs resemble those from other nematodes, such as Caenorhabditis elegans, other cDNAs are unique to hookworms. Studies are under way to evaluate the function of these recombinant hookworm polypeptides with respect to the biology of hookworms in experimental animal models. The recombinant polypeptides are also under evaluation as vaccine targets and as natural products used in the treatment of human cardiovascular and autoimmune diseases.

Ancylostomatoidea↗
PubMed1994

Smoking habits and recurrence in Crohn's disease.

BACKGROUND/AIMS: Smoking may be a risk factor for surgical recurrence of Crohn's disease. However, other variables associated with recurrence could be confounding factors for smoking. The aim of this study was to evaluate the role of smoking as an independent predictor of clinical, surgical, and endoscopic recurrence. METHODS: In a series of 182 patients who underwent surgery for Crohn's disease, a multivariate analysis was performed that included all of the significant variables associated with recurrence: sex, age at diagnosis, time between onset of symptoms and surgery, site of disease, indication for surgery, extent of disease, extraintestinal manifestation, and smoking habit. RESULTS: Independent predictors of clinical recurrence by the Cox proportional hazard model were smoking (hazard ratio, 1.46; 95% confidence interval [CI], 1.1-1.8), extraintestinal manifestations (hazard ratio, 1.61; 95% CI, 1.0-2.5), and extent of disease (hazard ratio, 1.57; 95% CI, 1.0-2.4). Smoking was the only significant predictor of surgical recurrence (hazard ratio, 2.0; 95% CI, 1.2-2.3). For endoscopic recurrence, logistic regression showed that smoking (odds ratio, 2.2; 95% CI, 1.2-3.8) and extent of disease (odds ratio, 2.6; 95% CI, 1.0-6.7) were predictive factors of recurrence. CONCLUSIONS: Smoking is an independent risk factor for clinical, surgical, and endoscopic recurrence in Crohn's disease.

Adult↗
PubMed1994

Hyaluronidases of the gastrointestinal invasive nematodes Ancylostoma caninum and Anisakis simplex: possible functions in the pathogenesis of human zoonoses.

The gastrointestinal invasive stages of two parasitic nematodes, Ancylostoma caninum and Anisakis simplex, were each found to release in vitro a hydrolytic enzyme that degrades the glycosaminoglycan hyaluronic acid. The parasite hyaluronidases were partially purified by ion-exchange chromatography and biochemically characterized. The hyaluronidase from A. caninum adult worms had a molecular weight of 65,000 and a pH optimum of 6 with activity at neutral pH, while the hyaluronidase from A. simplex larvae had a molecular weight of 40,000 and a pH optimum of 4 with no activity at neutral pH. Both parasite hyaluronidases also degraded the glycosaminoglycan chondroitin sulfate A. Cupric sulfate and high concentrations of sodium chloride were inhibitory. The nematode hyaluronidases are postulated to have a role in tissue histolysis and mucosal invasion; their distinct biochemical properties have relevance to the pathogenesis of the zoonoses anisakiasis and eosinophilic enteritis.

Ancylostoma↗