Evidence against a role of nitric oxide in the indirect negative inotropic-effect of M-cholinoceptor stimulation in human ventricular myocardium

Nitric oxide (NO) has been reported to mediate several effects in response to muscarinic cholinergic stimulation in cardiovascular tissues. Recently, an attenuation of guinea pig cardiac myocyte contraction by NO has been described. The aim of the present study was to determine whether the indirect negative inotropic effect of M-cholinoceptor stimulation in human myocardium is in part due to an effect of endogenous NO. Therefore, the effect of carbachol was studied under control conditions and during inhibition of NO-synthase by pretreatment with N^G-monomethyl-l-arginine (NMMA). Functional experiments were performed in isolated, electrically driven (1 Hz, 37°C) left ventricular papillary muscle strips of human myocardium. Since cytokines have been reported to be increased in the serum of patients with heart failure and could induce NO-synthase activity in failing myocardium, we compared samples from nonfailing and terminally failing (classified as NYHA IV) hearts. The indirect negative inotropic effect of carbachol (10 mol/l) was studied in the presence of the \-adrenoceptor agonist isoprenaline (0.03 mol/l).After stimulation with isoprenaline, carbachol significantly (P < 0.05) reduced force of contraction. This effect was diminished in failing myocardium compared to nonfailing, probably due to the diminished inotropic response most likely due to the lower cAMP levels in response to \-adrenoceptor stimulation in the former condition. Pretreatment with NMMA (100 mol/l) altered the antiadrenergic effect of carbachol neither in nonfailing nor in failing preparations. Furthermore, inhibition of guanylyl cyclase, the target enzyme of NO, by preincubation with methylene blue (10 mol/l) for 30 min had no effect on the carbachol-induced decrease in force of contraction. Basal force of contraction, as well as the positive inotropic effect of isoprenaline remained unaffected by NMMA or methylene blue.The present study provides evidence that the indirect negative inotropic effect of M-cholinoceptor agonists is not due to an effect of NO in the human myocardium. Furthermore, the well known enhancement of cGMP in response to M-cholinoceptor stimulation appears not to be involved in this antiadrenergic effect.     

Nitric oxide and l-arginine cause an accumulation of utrophin at the sarcolemma: a possible compensation for dystrophin loss in Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD), a severe X-linked recessive disorder which results in progressive muscle degeneration, is due to a lack of dystrophin, a membrane cytoskeletal protein. An approach to treatment is to compensate for dystrophin loss with utrophin, another cytoskeletal protein with over 80% homology with dystrophin. Utrophin is expressed, at the neuromuscular junction, in normal and DMD muscles and there is evidence that it may perform the same cellular functions as dystrophin. So, the identification of molecules or drugs that could up-regulate utrophin is a very important goal for therapy. We show that in adult normal and mdx mice (an animal model of Duchenne myopathy) treated with l-arginine, the substrate of nitric oxide synthase (NOS), a pool of utrophin localized at the membrane appeared and increased, respectively. In normal and mdx myotubes in culture, l-arginine, nitric oxide (NO), or hydroxyurea increased utrophin levels and enhanced its membrane localization. This effect did not occur with d-arginine, showing the involvement of NOS in this process. The NO-induced increase in utrophin was prevented by oxadiazolo-quinoxalin-1-one, an inhibitor of a soluble guanylate cyclase implicated in NO effects. These results open the way to a potential treatment for Duchenne and Becker dystrophies.     

Nitric Oxide and -Arginine Cause an Accumulation of Utrophin at the Sarcolemma: A Possible Compensation for Dystrophin Loss in Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD), a severe X-linked recessive disorder which results in progressive muscle degeneration, is due to a lack of dystrophin, a membrane cytoskeletal protein. An approach to treatment is to compensate for dystrophin loss with utrophin, another cytoskeletal protein with over 80% homology with dystrophin. Utrophin is expressed, at the neuromuscular junction, in normal and DMD muscles and there is evidence that it may perform the same cellular functions as dystrophin. So, the identification of molecules or drugs that could up-regulate utrophin is a very important goal for therapy. We show that in adult normal and mdx mice (an animal model of Duchenne myopathy) treated with -arginine, the substrate of nitric oxide synthase (NOS), a pool of utrophin localized at the membrane appeared and increased, respectively. In normal and mdx myotubes in culture, -arginine, nitric oxide (NO), or hydroxyurea increased utrophin levels and enhanced its membrane localization. This effect did not occur with -arginine, showing the involvement of NOS in this process. The NO-induced increase in utrophin was prevented by oxadiazolo-quinoxalin-1-one, an inhibitor of a soluble guanylate cyclase implicated in NO effects. These results open the way to a potential treatment for Duchenne and Becker dystrophies.     

P300 and respiratory findings in myotonic muscular dystrophy

Ten patients with myotonic muscular dystrophy (MD) were examined by auditory event-related potentials (P300 ERPs), spirometric and blood gas analyses: arterial oxygen tension (PaO2), arterial carbon dioxide tension (PaCO2) and arterial oxygen saturation (SaO2). The aim of the study was to analyse the frequency of ERP abnormalities in this disease and to determine whether the neurophysiological evidence of cognitive impairment might be related to the ventilatory function abnormalities frequently described in MD. The mean P300 latency was significantly altered in MD patients compared with controls; P300 latencies did not correlate with spirometric parameters, blood gas values or with age, age at onset, duration or clinical status of the disease. This study provides neurophysiological evidence of cognitive impairment in MD patients. The cognitive deficits are not related to alveolar hypoventilation and appear to be a non progressive feature of the disease.     

Differential effects of injections of anti-mu and anti-delta monoclonal antibodies on B-cell populations in adult mice: regulation of xenoreactive natural antibody-producing cells

BACKGROUND: The depletion of differential B cell and xenoreactive natural antibodies (XNA) by anti-delta and anti-mu injections was analyzed in adult mice. Sequential treatment with anti-delta and then anti-mu induces a complete depletion of B cells and XNA and represents a potential approach to induce xenograft tolerance. METHODS: Adult mice were injected with anti-mu, anti-delta, anti-delta then anti-mu, or control isotype monoclonal antibodies from day 0 to day 14. The different B-cell populations were analyzed by FACS and immunohistology. Ig production was tested by ELISA. XNA were analyzed by FACS. RESULTS: Anti-mu injections induced a depletion of IgMhigh, immature B cells, marginal zone B cells, and B1 cells and an increase of IgG-XNA production. Anti-delta injections induced mature conventional IgDhigh B-cell depletion and increased IgM-XNA production. Interestingly, sequential injections of anti-delta then anti-mu induced a depletion of immature B cells, mature B cells (MZ, B2, and B1), and XNA. CONCLUSIONS: These results demonstrate that mature B-cell depletion in adult mice can be obtained by mAb injections and depends on the surface immunoglobulin cross-linking threshold. Indeed, anti-mu mAb depleted IgMhigh B cells (MZ and B1) and anti-delta, IgDhigh B cells (B2). The differential B-cell suppression shows that conventional B cells are responsible in the IgG-XNA production and MZ and B1 cells in the IgM-XNA production. Sequential repeated injections of anti-delta then anti-mu mAb depleted all B-cell populations and suppressed the whole XNA production.     

Kidney and urinary tract injuries. Experience with 113 cases

BACKGROUND: Trauma of the kidney and urinary tract is not rare in emergency surgery and the related treatment needs today high competence and interdisciplinary approach. Aim of the study was to analyze the personal experience in order to find differences in the treatment during the last years especially for trauma of the kidney. METHODS: The authors report 113 cases of kidney or urinary tract trauma out of 16,569 patients admitted in emergency between 1981 and 1995. Fifty patients (44%) underwent surgery. Thirty patients (26%) underwent surgery for kidney trauma but in only 5 (16%) conservative surgery for partial damage was possible. Section of the ureter occurred in one patient. Ten patients had a rupture of the bladder and 9 the rupture of urethra. The cause of trauma was a gunshot wound in 11 patients (22%). Nineteen patients (38%) had also damage to other organs. RESULTS: The results show absence of morbidity or mortality related with urinary tract trauma. CONCLUSIONS: The analysis of these cases shows that the improvement of diagnostic possibilities allowed the reduction of surgical interventions especially for kidney trauma.     

Latex allergy. An not rare intraoperative event

Latex allergy has become a real problem among both surgical staff (paramedics and physicians) and patients especially pediatric patients with urogenital malformations and spina bifida. Latex allergy is produced from both natural molecules which compose the substance produced from Hevea brasiliensis (rubber tree) and industrial additives contents in latex devices. Diagnosis of latex allergy may be carried out through a preoperative Prik-test. A characteristic of latex allergy reaction is the starting of symptoms (more than 15 minutes after allergen contact). Pathophysiology of latex allergy is the same of all allergic reactions; it is an antigen-antibody reaction and type I or II reaction may occur. There are a lot of devices that surgeons and anesthesists use in the operative theatre and that should not be used in presence of a patient with latex allergy. Guaranteed latex-free devices should always be present in store.     

Target controlled infusion (TCI): applications of the "TCI visual" program in anesthesia and sedation with propofol

BACKGROUND: Systems for Target Controlled Infusion accepting not only patient' data, like Diprifusor, but also a pharmacokinetic model have not been available in Italy in the last years. Therefore a program which controls a Pilot Anesthesia Vial pump and accepts any pharmacokinetic model was developed and applied to propofol infusion for anaesthesia and sedation. METHODS: Two versions of the Visual TCI program have been developed. The first, at intervals, supplies the anaesthetist with the values for the pump; the second directly interacts with the pump. The program also supplies the anaesthetist with the current amount of drug in each compartment and with the estimated awakening time. DESIGN: preliminary prospective study. SETTING: operatory theatre and Intensive Care Unit in a University Hospital. Patients: 6 patients undergoing total intravenous anaesthesia with propofol and fentanyl for abdominal surgery; 6 patients undergoing sedation with propofol in an Intensive Care Unit (the first 4-hour period was taken into account). Interventions: propofol infusion was regulated by the Visual TCI program. The first version was employed in three patients of each group and the second one in the others. Hypo- and hypertensive episodes (systolic pressure less than 80 mmHg or higher than basal value plus 25%) were recorded during anaesthesia and sedation. Propofol concentration was measured in plasma three times at defined intervals and per cent differences between measured and computer-calculated values (Predictive error, PE) were calculated. RESULTS: No hypo- or hypertensive episodes were recorded. PE was 27.4 +/- 17.9%. CONCLUSIONS: The program was easily employed, caused no inconvenience, and its use was associated with a remarkable cardiovascular stability. PE distribution was acceptable on the ground of the criteria reported in the literature. The program can be applied to drugs other than propofol, with both two and three compartment pharmacokinetic models and the anaesthetist can choose the most suitable model for the patient.