Chemical and enzymatic treatment of endothelin

Endothelin-1 (ET), the most potent vasoconstrictor yet discovered, is a peptide containirig 21 amino acids with two intrachain disulfide bridges. With the aim of obtaining two-chain derivatives, Et was submitted to chemical and enzymatic treatments. Reaction of ET with CNBr in 70% HCOOH gave, in addition to the expected [Hse⁷ lactone]-7,8-seco-ET and unreacted material, a by-product whose molecular weight was 25 m.u. greater than that of ET. When the reaction mixture, after lyophilisation, was immediately quenched with NH3-saturated dry MeOH, two products could be recovered in a 5:1 ratio, both obtained by nucleophilic attack of the homoserine lactone: the expected [Hse⁷-NH₂]-7,8-seco-ET and [Hse⁷]ET, resulting from competitive intramolecular reaction of the deprotonated α-amino group of the Asp⁸ residue. The Lys⁹-Glu¹⁰ bond turned out to be very resistant to enzymatic attack both by Lys-C-endopeptidase and trypsin. The 9,10-seco-ET derivative could be obtained by treatment with Lys-C-endopeptidase only by using a high enzyme/ET ratio and after a prolonged incubation time. Cleavage of the Lys⁹-Glu¹⁰ bond could not be achieved by treatment with trypsin, even with a high enzyme/substrate ratio. The main product was 13, 14-seco-ET, deriving from the action of chymotripsin (present as an impurity in the trypsin preparation) on Tyr¹³. The structure of these peptides was confirmed by amino-acid sequence analysis and fast atom bombardment mass spectrometry (FAB-MS). Nicking of the ET structure at different positions had different impact on the biological properties of the resulting derivatives. © Munksgaard 1995.     

Lack of Influence of Atrioventricular Delay on Stroke Volume at Rest in Patients with Complete Atrioventricular Block and Dual Chamber Pacing

Dual chamber pacing (DDD) maintains atrioventricular (AV) sequence; AV delay programmability modifies the relationship between atrial and ventricular contraction. To evaluate the hemodynamic effects of such a modification, ten patients with a DDD unit for complete AV block were studied by time-motion (M-mode) and Doppler echocardiography during inhibited ventricular pacing (VVI), atrial-triggered ventricular pacing (VDD) and atrioventricular sequential pacing (DVI) at different AV delay (90, 140, 190, 240 msec). A significant improvement in stroke volume (SV) (15%-20%, P less than 0.05) was seen during DDD versus VVI pacing; no changes, however, were observed in the same patient with different AV delay or during DVI versus VDD pacing. These data suggest that programming of AV delay does not affect systolic performance at rest; longer diastolic filling times recorded during DDD pacing with "short" AV delay (90-140 msec) do not seem to be a hemodynamically relevant epi-phenomenon of PM programming.     

Effect of mesalazine on mucosal immune biomarkers in irritable bowel syndrome: a randomized controlled proof-of-concept study

Background  Intestinal immune infiltration contributes to symptoms in patients with irritable bowel syndrome (IBS).
Aim  To assesses the effect of mesalazine (mesalamine) on mucosal immune cells in patients with IBS, through a pilot study.
Methods  A randomized, double-blind, placebo-controlled trial in 20 patients with IBS in tertiary care setting. Patients were randomized to receive placebo or 800 mg mesalazine three times daily for 8 weeks. The primary endpoint was a significant reduction in total colonic immune cells on biopsies obtained at the end of treatment compared to baseline. Secondary endpoints included effects on subsets of immune cells, inflammatory mediators and symptom severity. Intention-to-treat analysis was performed.
Results  Mesalazine markedly reduced immune cells as compared with placebo ( P  = 0.0082); this effect was ascribed to a marked inhibition of mast cells ( P  = 0.0014). Mesalazine significantly increased general well-being ( P  = 0.038), but had no significant effects on abdominal pain ( P  = 0.084), bloating ( P  = 0.177) or bowel habits. No serious drug-related adverse events were reported during the study.
Conclusions  Mesalazine is an effective and safe approach to reduce mast cell infiltration and may improve general well-being in patients with IBS. These results support the hypothesis that immune mechanisms represent potential therapeutic targets in IBS.     

In vitro interaction of opioid peptides with phospholipids

The binding of tritiated Leu-enkephalin to phosphatidylserine and phosphatidylcholine vesicles, both unmodified and modified by the incorporation of free fatty acid, has been studied by steric exclusion chromatography, ultraviolet difference spectroscopy and fluorescence anisotropy. The results obtained tend to confirm that both ionic and hydrophobic interactions are important in the binding phenomena. On the other hand, it seems likely that steric factors play a very limited role in the recognition of the phospholipid by the opioid peptide. Finally, these results confirm the existence of three complexes of different size, as already demonstrated. But, unlike the previously presented results, they stress the importance of the larger of the three complexes formed through binding.     

45-Hour continuous quintuple-site actimetry: Relations between trunk and limb movements and effects of circadian sleep-wake rhythmicity

Diurnal and nocturnal trunk and limb motor activity of 20 healthy individuals was evaluated by actimetry for 45 consecutive hours. Sleep was assessed by sleep logs. Overall, motor activity significantly (p < .05) decreased in the order wrist, ankle, and trunk. There was significantly more motor activity in the dominant wrist during the diurnal period. Motor activity was significantly affected by the 24-hr sleep-wake cycle, with lower levels and prolonged immobility during the night. Time series analyses revealed different but significant correlations between motor activity at all sites. These data imply that (a) motor activity should be recorded at the dominant wrist when the highest level of motor activity is of importance, (b) recordings at the nondominant wrist are better indicators of trunk movement than are dominant wrist recordings, and (c) sites other than the conventional nondominant wrist recording site should be evaluated to improve the validity of motor activity-based sleep-wake scoring.     

Hypoxia modulates phenotype,inflammatory response,and leishmanial infection of human dendritic cells

Bosseto MC, Palma PVB, Covas DT, Giorgio S. Hypoxia modulates phenotype, inflammatory response, and leishmanial infection of human dendritic cells. APMIS 2010; 118: 108–14. Development of hypoxic areas occurs during infectious and inflammatory processes and dendritic cells (DCs) are involved in both innate and adaptive immunity in diseased tissues. Our group previously reported that macrophages exposed to hypoxia were infected with the intracellular parasite Leishmania amazonensis, but showed reduced susceptibility to the parasite. This study shows that although hypoxia did not alter human DC viability, it significantly altered phenotypic and functional characteristics. The expression of CD1a, CD80, and CD86 was significantly reduced in DCs exposed to hypoxia, whereas CD11c, CD14, CD123, CD49 and HLA‐DR expression remained unaltered in DCs cultured in hypoxia or normoxia. DC secretion of IL‐12p70, the bioactive interleukin‐12 (IL‐12), a cytokine produced in response to inflammatory mediators, was enhanced under hypoxia. In addition, phagocytic activity (Leishmania uptake) was not impaired under hypoxia, although this microenviroment induced infected DCs to reduce parasite survival, consequently controlling the infection rate. All these data support the notion that a hypoxic microenvironment promotes selective pressure on DCs to assume a phenotype characterized by pro‐inflammatory and microbial activities in injured or inflamed tissues and contribute to the innate immune response.     

Hypertrophy of mucosa and serosa in the obstructed intestine of rats

After a surgically induced partial obstruction of the small intestine (ileum) in adult rats there is an accumulation of ingesta and a progressive enlargement of the lumen accompanied by wall thickening: over a period of 2–3 wk the circumference of the hypertrophic intestine increases by a factor of 2·7 and the thickness of the musculature increases more than threefold, while the length of the ileum (measured at the mesenteric attachment) remains unchanged. The villi become markedly larger and more elongated in the circumferential direction, and have a greater separation between one another. The number of villi per unit surface is markedly reduced but the number of villi per unit length of ileum, whilst appearing to show a small increase, was not significantly altered. The component epithelial cells (absorptive cells) appear unchanged in morphology and size (height). The microvilli of the epithelial cells have the same appearance, size (height) and packing density in the control and the hypertrophic ileum. Glands of Lieberkühn, Peyer's patches and single lymphatic follicles constituting the Peyer's patches are significantly increased in size in the hypertrophic intestine. The serosal surface of the hypertrophic ileum, in spite of the great expansion, remains regularly covered by mesothelial cells; these are much larger than in the controls and have an altered distribution of their microvilli.     

Right Ventricular Tachycardia with Left Bundle Branch Block and Inferior Axis Morphology: Clinical and Arrhythmological Characteristics in 15 Patients

Fifteen patients (mean age 30) presenting with right ventricular tachycardia (VT) of the outflow tract type (left bundle branch block with inferior axis morphology), in the absence of obvious organic heart disease, were studied. Seven patients had palpitations, one presyncope and seven were asymptomatic. The echo and/or angiographic findings were normal in 11 patients (73%), suggesting arrhythmogenic right ventricular dysplasia (ARVD) in three (20%) and dubious in one (7%). The VT was sustained in three patients (20%), nonsustained (11 +/- 6 beats) in twelve (80%), inducible during exercise in two out of 15 patients (13%) and with ventricular stimulation in one out of eight (12.5%). Four patients were treated with sotalol, three with Class IC drugs and one with amiodarone. At follow-up of 36 +/- 30 months, only three patients had VT recurrences due to drug withdrawal. In conclusion: (1) abnormal echo and/or angiographic findings suggested that ARVD was observed in a minority of the patients (22%); (2) the low inducibility of VT and the good response to sotalol suggested a possible mechanism of abnormal automaticity; and (3) at a 3-year follow-up the prognosis appeared to be good in both patients with or without echo-angiographic signs suggestive of right ventricular dysplasia.     

Clinical Experience with Orthocor II Antitachycardia Pacing System for Recurrent Tachyarrhythmia Termination

Between June 1986 and December 1988, eight patients were treated with an Orthocor II 284 A antitachycardia pacemaker (Cordis Corp., Miami, FL, USA) forsupraventricular tachycardia (SVT) and ventricular tachycardia (VT) termination. Four patients had intra-AV nodal reentrant tachycardias; 1 patient had AV reentrant tachycardia with an atrio-nodal accessory bypass tract; 2 patients had AV reentrant tachycardias with concealed Kent bundle, and 1 patient had ventricular tachycardia. All patients had been treated with three or more drugs and were considered to be drug refractory. The programmed antitachycardia mechanism used for patients with SVT were: automatic overdrive in five patients and burst scanning in two patients. In the patient with VT, a critically timed double extrastimulus with fixed coupling interval was programmed. Follow-up ranged from 2 to 30 months. The pacemaker proved to be effective in terminating tachycardias in all cases with SVT; in the patient with VT, the programmed antitachycardia mechanism was effective for a long time, but after an episode of sustained VT not interrupted by the pacemaker, the patient underwent automatic cardioverter/defibrillator (AICD) implantation. Additional antiarrhythmic therapy was required in 3 patients to control their maximum sinus rate, in 1 patient to reduce tachycardia episodes and to enable termination, and in 2 patients to prevent spontaneous atrial fibrillation. It is concluded that Orthocor II is a flexible and versatile antitachycardia pacemaker providing a safe and effective control of recurrent tachycardia in selected patients.