Circular dichroism studies on sequential polypeptides (Arg-X-Gly) when X = L-Ala,Val, Leu,Ile, Nva,Nle in amphiphilic environments

A series of (L-Arg-X-Gly)_n sequential polypeptides, where X represents the amino acid residues L-Ala, Val, Leu, Ile, Nva, and Nle, have been prepared and their conformational properties as well as their association with nucleic acids in various water fluoroalcohol mixtures have already been reported. In order to gain further insight into the conformational behavior of these polypeptides in amphiphilic environments, we now report their secondary structure, in the presence of increasing amounts of sodium dodecylsulfate and dodecylphosphorylcholine using CD spectroscopy. The CD spectral pattern of all the polypeptides studied is indicative of an equilibrium between α-helix, β-turn, and random coil. They are analyzed in relation to the nature of the X side-chain (length, branching, linearity). The results are explained on the basis of Lundahl's model for polypeptide-micelle interactions.     

Health maximization rejected: The view of Swedish politicians

The meaning of the equity target in Swedish public health policyand its relationship to efficiency is investigated. Three interpretationsof the relationship are analysed and the support given to eachof them by 449 Swedish politicians is investigated in a postalquestionnaire. The common health economics interpretation thatequity is embodied in the health maximization principle, whichimplies that distribution is unimportant, is rejected by approximately70%. The results also refute the lexicograhpical interpretation,since support for the equity target depends upon the magnitudeof the efficiency sacrificed. The third interpretation couldbe labelled plural targets or trade-off, implying that achievementsin respect of 1 target must be weighed against losses in respectof some other target. Approximately 70% of the respondents wereprepared to sacrifice health benefits in exchange for equityof health. However, support for the different interpretationsof equity are strongly associated with sex and political affiliation.Men and representatives of the Conservative Party have muchgreater sympathy for the health maximization principle.     

Conformational study of vasoactive intestinal peptide by computational methods

The conformational profile of vasoactive intestinal peptide (VIP) was characterized using computational methods. The strategy devised included a close examination of the conformational profile of the first 11 residues fragment followed by a study that considered the compatibility of the different conformations found with a continuation of the polypeptide chain in a-helical conformation. Accordingly, a detailed analysis of the conformational preferences of the N-terminal fragment of VIP(1–11) was carried out within the framework of the molecular mechanics approach, using simulated annealing in an iterative fashion as the sampling technique. In a second step, low-energy structures of the fragment were fused to the remainder of the VIP chain in the form of two noninteracting α-helices, according to a model of the structure of the peptide proposed from NMR studies. After investigation for compatibility of each of the low-energy structures of VIP(1–11) with the two helical regions by energy minimization, only 5 of 35 structures were discarded. Analysis of the structures characterized indicates that most of the conformations of VIP(1–11), including the global minimum, can be described as bent conformations. Conformations exhibiting α-turns and ß-turns, previously proposed by NMR studies were also characterized. The conformational analysis also suggests that the common structural features found in VIP(1–11) should also be present in VIP. Finally, because of the sequence homology between VIP and Peptide T, and the fact that both are ligands of the CD4 receptor, both sets of low-energy conformations were compared for similarity. The relevance of these results as guidance of the design of new peptide analogs targeted to the CD4 receptor is also discussed.     

Conformational investigation of α, β-dehydropeptides. VIII.*N-Acetyl-α, β-dehydroamino acid N'-methylamides: conformation and electron density perturbation from infrared and theoretical studies

The Fourier transform infrared spectra are analyzed in the regions of v_s(N-H), amide I, amide II and v_s(C^α=C^β) bands for a series of Ac-ΔXaa-NHMe, where ΔXaa =ΔAla, (Z)-ΔAbu, (Z)-ΔLeu, (Z)-ΔPhe and AVal, to determine the predominant solution conformation of these α, β-dehydropeptide-related molecules and the electron distribution perturbation in their amide bonds. The measurements were performed in dichloromethane (DCM). To confirm and rationalize the assignments, the spectra of the respective series of saturated Ac-Xaa-NHMe, recorded in DCM, and the spectra of these two series of unsaturated and saturated compounds, recorded in acetonitrile, were examined. To help interpret the spectroscopic results, the equilibrium geometrical parameters for some selected amides were used. These were optimized with ab initio methods in the 6-31G** basis set. Each of the dehydroamides studied adopted a C₅ structure, which in Ac-ΔAla-NHMe is fully extended and accompanied by the strong C₅ hydrogen bond. Interaction with the C^α=C^β bond lessened the amidic resonance within each of the flanking amide groups. The N-terminal C=O bond was noticeably shorter, both amide bonds were longer than the corresponding bonds in the saturated entities and the N-terminal amide system was distorted. Ac-ΔAla-NHMe constituted an exception. Its C-terminal amide bond was shorter than the standard one and both amide systems were prototypically planar.     

Aggravating Process Induced by Indomethacin on Chronic Gastric Lesion in Rat. Role of Polymorphonuclear Leucocytes

The present study examines the indomethacin-provoked aggravation of chronic ulceration induced by acetic acid in rats. The drug was administered in a single dose, 7 and 14 days after provocation of ulceration. The changes induced by indomethacin in other groups of animals that had been treated for 7 and 14 days with hydroxyurea (which provokes a marked leucopenia) were also studied. The results obtained demonstrate that indomethacin does not significantly modify the macroscopic index of ulceration nor vascular permeability in the majority of the groups tested. Only in the group that received hydroxyurea for 14 days was there an increase in both parameters. Myeloperoxidase activity was assayed and used as an index of leucocyte infiltration in an attempt to relate the increase in this activity with a gastrolesive effect. Application of acetic acid produced a significant increase in this activity 7 days after induction of chronic injury. Administration of hydroxyurea intraperitoneally was associated with a decrease in the severity of chronic ulceration and neutrophil infiltration into the gastric mucosa. This effect was detectable enzymatically and microscopically. The groups that received indomethacin showed an increase in myeloperoxidase activity, although this increase was only significant in the animals treated with hydroxyurea for 7 and 14 days. The results suggest that the aggravation provoked by indomethacin is greater when the ulcer curing process is more advanced.     

Review article The use of botulinum toxin in the alimentary tract

New and future indications for the treatment of disorders of the alimentary tract using local injections of botulinum toxin are reviewed. Clinical experience shows that overactive smooth muscle sphincters may be weakened to treat disorders such as achalasia or chronic anal fissure. By contrast, injections placed into the sphincter of Oddi have proven less effective for post-cholecystectomy pain syndrome. Experimental evidence suggests that food intake may be reduced by weakening the distal stomach with botulinum toxin. This approach may possibly lead to the treatment of obesity. There are some new possible indications for the use of botulinum toxin on the alimentary tract, and infantile hypertrophic pyloric stenosis seems to be the most promising new development.     

Improvement of survival in Duchenne Muscular Dystrophy: retrospective analysis of 835 patients

Duchenne Muscular Dystrophy (DMD) is the most common muscle disease in children. Historically, DMD results in loss of ambulation between ages 7 and 13 years and death in the teens or 20s. In order to determine whether survival has improved over the decades and whether the impact of nocturnal ventilation combined with a better management of cardiac involvement has been able to modify the pattern of survival, we reviewed the notes of 835 DMD patients followed at the Naples Centre of Cardiomyology and Medical Genetics from 1961 to 2006. Patients were divided, by decade of birth, into 3 groups: 1) DMD born between 1961 and 1970; 2) DMD born between 1971 and 1980; 3) DMD born between 1981 and 1990; each group was in turn subdivided into 15 two-year classes, from 14 to 40 years of age. Age and causes of death, type of cardiac treatment and use of a mechanical ventilator were carefully analyzed.The percentage of survivors in the different decades was statistically compared by chi-square test and Kaplan-Meier survival curves analyses. A significant decade on decade improvement in survival rate was observed at both the age of 20, where it passed from 23.3% of patients in group 1 to 54% of patients in group 2 and to 59,8% in patients in group 3 (p < 0.001) and at the age of 25 where the survival rate passed from 13.5% of patients in group 1 to 31.6% of patients in group 2 and to 49.2% in patients in group 3 (p < 0.001).The causes of death were both cardiac and respiratory, with a prevalence of the respiratory ones till 1980s. The overall mean age for cardiac deaths was 19.6 years (range 13.4-27.5), with an increasing age in the last 15 years. The overall mean age for respiratory deaths was 17.7 years (range 11.6-27.5) in patients without a ventilator support while increased to 27.9 years (range 23-38.6) in patients who could benefit of mechanical ventilation.This report documents that DMD should be now considered an adulthood disease as well, and as a consequence more public health interventions are needed to support these patients and their families as they pass from childhood into adult age.Key words: Duchenne, survival, cardiomyopathy