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Biomedical subjects

A Morelli

Publications and source records attributed to A Morelli.

At least 37 records · Page 2Linked to original sources

Effects of extremely low frequency electromagnetic fields on the adenylate kinase activity of rod outer segment of bovine retina.

Extremely low frequency electromagnetic fields (ELF-EMFs) of 75 Hz with amplitudes above a threshold of about 125 microT have a dramatic effect on the adenylate kinase (AK) activity of the rod outer segment (ROS) membranes. In fact, the ATP production by ROS membranes or by purified disk membranes placed in the field decreased by approximately 54%. The decrease in enzymatic activity was independent of the time of exposure to the field and was completely reversible. When disk membranes were solubilized with Triton or a soluble isoform of AK was used, negligible effects of the field were obtained on the enzymatic activity, suggesting that the membrane has an important role in determining the conditions for the enzyme inactivation.

Adenosine Triphosphate↗

Colonic motility studies in severe chronic constipation: an organic approach to a functional problem.

Chronic constipation is one of the more frequent functional gastrointestinal symptoms. The more severe cases not infrequently undergo a major surgical approach. However, there is still a need for a better diagnostic and therapeutic approach, since the results are still unpredictable, probably due to a poor selection of candidates. This article focuses on the current diagnostic approach to chronic constipation, with an emphasis on the possible role of colonic manometry to help better choose those patients that may benefit from surgery.

Chronic Disease↗

Electromagnetic field of extremely low frequency decreased adenylate kinase activity in retinal rod outer segment membranes.

Adenylate kinase activity in rod outer segment membranes of bovine retina decreased of about 55% when exposed to an extremely low frequency electromagnetic field of 75 Hz and 250 microT. The effect was independent of the time of permanence in the field. Negligible effects of the field were found on the enzymatic activity of a soluble isoform of adenylate kinase or of rod outer segment membranes solubilized with Triton, suggesting the importance of the membrane in determining the conditions of the enzyme inactivation.

Adenosine Triphosphate↗

Symptomatic reversible duodenal compression due to iatrogenic retroperitoneal hematoma.

Selective serotonin reuptake inhibitors are frequently employed to treat depression. However, although rarely, coagulation abnormalities have been described following the use of these compounds, and these effects appear to be enhanced by simultaneous use of nonsteroidal anti-inflammatory drugs. We describe a case of reversible symptomatic duodenal compression caused by a retroperitoneal hematoma after ingestion of sertraline and nimesulide.

Anti-Inflammatory Agents, Non-Steroidal↗

Laparoscopic transduodenal papillosphincteroplasty.

In the past 20 years, the approach to biliary lithiasis has changed tremendously as a result of advances in endoscopic and laparoscopic techniques. The two most important open surgical techniques involve extraction of the stones from the common bile duct combined with choledochoenterostomy and papillotomy followed by transduodenal papillosphinteroplasty. Ideally, the choledochotomy is followed by the insertion of a T-tube in the common bile duct. The transcystic approach has never been considered. The first endoscopic papillotomy was performed in 1973. Subsequently, it became the most widely used method for removal of common bile duct stones. In this report we explore the possibility of performing a laparoscopic transduodenal papillosphincteroplasty, following the strict rules commonly used in surgery. After cholecystectomy, a Fogarty catheter, is introduced through the cystic duct. This is followed by a minimal duodenotomy, then incision of the papillar sphincter. In this surgical proposal, we do not intend to substitute technique, but this method should be considered the ultimate solution in the laparoscopic approach to cholecystic choledocholithiasis.

Ampulla of Vater↗

Nitric oxide and portal hypertension: a nitric oxide-releasing derivative of ursodeoxycholic acid that selectively releases nitric oxide in the liver.

Portal hypertension, a common consequence of chronic liver diseases, is directly responsible for most complications of cirrhosis. In liver microcirculation, nitric oxide is considered a major fine tuner of vascular tone by counterbalancing vasoconstrictors (sympathetic nervous activity, the renin-angiotensin system, and endothelin-1) in normal and cirrhotic livers. The deficiency of endothelial nitric oxide release is a key factor in the hemodynamic abnormalities associated with the dynamic component of portal hypertension. Conventional nitric oxide donors release nitric oxide into the blood stream, causing systemic hypotension and progression of vasodilatory syndrome in cirrhotic patients. NCX1000 is a nitric oxide-releasing derivative of ursodeoxycholic acid-derived compounds, being capable of selectively releasing nitric oxide into the liver circulation. Administration of NCX1000 to portal hypertensive rats decreases intrahepatic resistance providing a novel therapy for the treatment of portal hypertension.

Adipocytes↗

Are colonic regular contractile frequency patterns in slow transit constipation a relevant pathophysiological phenomenon?

BACKGROUND: Pathogenesis of slow transit constipation still remains elusive. Some studies have shown several colonic motor abnormalities; however, it is not easy to understand the relative importance of the single ones. AIMS: Since it has been hypothesized that an excess of periodic distal motor activity may be of pathophysiological importance in patients with slow transit constipation, we evaluated regular colonic contractile frequencies in a homogeneous cohort of these patients. PATIENTS: A total of 26 female patients (age range 34 to 67 years) fulfilling the Rome II criteria for constipation entered the study. No patient had evidence of secondary forms of constipation and distal obstruction. METHODS: Twenty-four hour colonic manometric studies were obtained for each patient. Regular contractile patterns (with frequencies ranging from 2 to 8 cycles/min) were calculated for the entire recording period and in single colonic segments. RESULTS: Overall, regular patterns accounted for about 3% of the total colonic motor activity (average 30 min/day per subject), with the 3 cycles/min being the predominant contractile rhythm. Most of this activity was present in the sigmoid colon, accounting for >50% of the total amount of motility, and it was more prevalent than in the descending and transverse colon; no differences were revealed in the descending with respect to the transverse colon. No daily fluctuations of regular contractile activity, nor a cyclic pattern, nor migration between recording points were observed. CONCLUSIONS: Regular colonic frequency patterns are probably of minor pathophysiological importance in slow transit constipation, even in the light of the scant amount of such phenomena previously documented in healthy subjects.

Adult↗

Parasitological and immunological effects induced by immunization of Mandrillus sphinx against the human filarial Loa loa using infective stage larvae irradiated at 40 Krad.

Six mandrills were immunized with 150 Loa loa infective stage larvae (L3) irradiated with 40 Krad, and challenged with 100 L3, 60 days after initial vaccination. The parasitological outcome of this immunization was compared to results from six mandrills infected with normal L3. No clear association was seen between vaccination and microfilaremia until day 245 when a significant drop in the level of microfilaria occurred in vaccinated compared to infected animals (5 vs 10 mf/ml; p = 0.012). A one-year follow-up of the humoral immune response showed a strong adult, microfilariae (Mf) and L3 specific IgG response, with distinct profiles for each extract. In immunized animal a significant decrease in antibody level was systematically observed between days 90-145 for the anti-L3 and anti-adult IgG. However, in the same group anti-Mf antibody levels that peaked around 160-175 days post-challenge, were inversely correlated with the decrease in Mf density between day 200 and day 386. These results suggest that immunization with irradiated L3 using these specific conditions may affect the appearance of Mf.

Animals↗

Effects of hypoxia on endothelin-1 sensitivity in the corpus cavernosum.

The penis remains in a hypo-oxygenated, flaccid state for a large majority of the time. In this study, we investigated the effect of changing oxygen tension on the expression and functional activity of endothelin-1 (ET-1) receptors in the penis. Experiments were performed in rabbit and human corpora cavernosa (CC) as well as in human fetal penile tissue and cell cultures [human fetal penile endothelial cells (hfPECs) and human fetal smooth muscle cells (hfPSMCs)]. Endothelin A (ETA) receptors are expressed by both endothelial and muscular cells in all tissues investigated. Only penile endothelial cells express endothelin B (ETB) receptors, which are further turned on during experimental hypoxia. In addition, hypoxia also allows ETB expression in the muscular compartment without affecting ETA expression. This hypoxia-induced over-expression of ETB decreased the contractile activity of ET-1 and increased ETB-mediated relaxation. The latter was essentially related to increased ETB-mediated nitric oxide formation in hfPEC and even in hfPSMC. Hypoxia also induced a time-dependent down-regulation of RhoA and Rho kinase (ROK) expression which, in turn, participated in the decreased contractile activity of ET-1 in the hypoxic penile tissue. Accordingly, during hypoxia, an ROK inhibitor, Y27632, was less effective in relaxing ET-1-precontracted strips. In conclusion, prolonged (24 h) hypoxia stimulated several counter-regulatory mechanisms in penile tissue, including up-regulation of ETB and down-regulation of RhoA/ROK pathways, which may help to preserve CC hypo-oxygenation, allowing smooth muscle relaxation and, most probably, penile erection.

Animals↗

Equation of state data for iron at pressures beyond 10 Mbar.

We present equation of state points for iron, in the pressure range 10-45 Mbar, the first obtained with laser-driven shock waves. The experiment has been performed with the high energy laser Phebus, optically smoothed with Kinoform phase plates. Our results double the set of existing experimental data at very high pressures showing good agreement with the predictions of the quotidian equation of state model and with previous results.

Journal Article↗

ATP synthesis in the disk membranes of rod outer segments of bovine retina.

ATP is synthesized on the disk membrane isolated from rod outer segments of the bovine retina. Together with a slow component which accounted for a constant rate of about 22 nmol ATP/min/mg of protein and which was due to the adenylate kinase activity, a fast component with a maximal activity of about 58 nmol ATP/min/mg of protein was measured at physiological calcium concentrations. This fast activity disappeared in the presence of the Ca(2+) ionophore A23187, was inhibited by vanadate or thapsigargin but not by oligomycin, suggesting that this ATP synthesis is due to the reversal functioning of the Ca(2+)-ATPase previously found on the disk membranes.

Adenosine Diphosphate↗

Effect of acute and chronic levosulpiride administration on gastric tone and perception in functional dyspepsia.

BACKGROUND: Altered visceral perception is common in functional dyspepsia (FD). Dopaminergic pathways control gastrointestinal motility, but whether they modulate visceral sensitivity is unknown. AIM: To investigate whether levosulpiride, a D2 antagonist, modulates gastric sensitivity and compliance in dyspeptic patients. METHODS: Eight healthy subjects and 16 dyspeptic patients underwent graded gastric distensions using a tensostat. In dyspeptic patients the same isotonic distensions were repeated during either levosulpiride or saline administration. Eight FD patients were evaluated after 4-week treatment with oral levosulpiride. Gastrointestinal symptoms were evaluated using a 100 mm visual analogue score. Perception was scored on a scale of 0 to 6. RESULTS: Although healthy subjects and FD patients had similar gastric compliance, FD patients tolerated lower tension levels. At the same distending tension levels, levosulpiride decreased gastric compliance and perception score (14 +/- 6% and 38 +/- 10% change, respectively; P < 0.05 vs. saline) only in FD patients. Isotonic distensions exhibited very reproducible perception. Chronic levosulpiride administration significantly reduced dyspeptic symptoms and increased discomfort threshold. CONCLUSIONS: Compared with healthy subjects, FD patients show marked gastric hypersensitivity. In FD patients levosulpiride decreased the perception of gastric distension with an action unrelated to change of gastric tone. Chronic levosulpiride administration significantly ameliorates gastrointestinal symptoms and increases the discomfort threshold.

Adult↗

[Neurinoma of the brachial plexus: 2 case reports].

Neurinomas, also referred to as neurilemmomas and schwannomas, are rare benign tumours of the peripheral nerves. A small percentage of these lesions arise from the brachial plexus. The Authors report two cases of schwannoma arising from the brachial plexus. Such lesions, usually asymptomatic, may cause sensitivity alterations or, less frequently, motor deficits in the involved arm. Tumour enucleation, avoiding damage to any of the nervous fascicles, is the treatment of choice.

Brachial Plexus Neuropathies↗

Proteinase-activated receptor 2 is an anti-inflammatory signal for colonic lamina propria lymphocytes in a mouse model of colitis.

The proteinase-activated receptor 2 (PAR-2) is a member of a family of G protein-coupled receptors for proteases. Proteases cleave PARs within the extracellular N-terminal domains to expose tethered ligands that bind to and activate the cleaved receptors. PAR-2 is highly expressed in colon in epithelial and neuronal elements. In this study we show that PAR-2 activation prevents the development and induces healing of T helper cell type 1-mediated experimental colitis induced by intrarectal administration of 2,4,6-trinitrobenzene sulfonic acid (TNBS) in mice. A role for PAR-2 in the protection against colon inflammation was explored by the use of SLIGRL-NH(2), a synthetic peptide that corresponds to the mouse tethered ligand exposed after PAR-2 cleavage. TNBS-induced colitis was dose-dependently reduced by the administration of SLIGRL-NH(2), whereas the scramble control peptide, LSIGRL-NH(2), was uneffective. This beneficial effect was reflected by increased survival rates, improvement of macroscopic and histologic scores, decrease in mucosal content of T helper cell type 1 cytokines, protein, and mRNA, and a diminished myeloperoxidase activity. SLIGRL-NH(2), but not the scramble peptide, directly inhibited IFN-gamma secretion and CD44 expression on lamina propria T lymphocytes. Protection exerted by PAR-2 in TNBS-treated mice was reverted by injecting mice with a truncated form of calcitonin gene-related peptide and by sensory neurons ablation with the neurotoxin capsaicin. Collectively, these studies show that PAR-2 is an anti-inflammatory receptor in the colon and suggest that PAR-2 ligands might be effective in the treatment of inflammatory bowel diseases.

Animals↗

NCX-1000, a NO-releasing derivative of ursodeoxycholic acid, selectively delivers NO to the liver and protects against development of portal hypertension.

Portal hypertension resulting from increased intrahepatic resistance is a common complication of chronic liver diseases and a leading cause of death in patients with liver cirrhosis, a scarring process of the liver that includes components of both increased fibrogenesis and wound contraction. A reduced production of nitric oxide (NO) resulting from an impaired enzymatic function of endothelial NO synthase and an increased contraction of hepatic stellate cells (HSCs) have been demonstrated to contribute to high intrahepatic resistance in the cirrhotic liver. 2-(Acetyloxy) benzoic acid 3-(nitrooxymethyl) phenyl ester (NCX-1000) is a chemical entity obtained by adding an NO-releasing moiety to ursodeoxycholic acid (UDCA), a compound that is selectively metabolized by hepatocytes. In this study we have examined the effect of NCX-1000 and UDCA on liver fibrosis and portal hypertension induced by i.p. injection of carbon tetrachloride in rats. Our results demonstrated that although both treatments reduced liver collagen deposition, NCX-1000, but not UDCA, prevented ascite formation and reduced intrahepatic resistance in carbon tetrachloride-treated rats as measured by assessing portal perfusion pressure. In contrast to UDCA, NCX-1000 inhibited HSC contraction and exerted a relaxing effect similar to the NO donor S-nitroso-N-acetylpenicillamine. HSCs were able to metabolize NCX-1000 and release nitrite/nitrate in cell supernatants. In aggregate these data indicate that NCX-1000, releasing NO into the liver microcirculation, may provide a novel therapy for the treatment of patients with portal hypertension.

Animals↗