On the non-bonding valence band and the electronic properties of poly(triazine imide), a graphitic carbon nitride

Graphitic carbon nitrides are covalently-bonded, layered, and crystalline semiconductors with high thermal and oxidative stability. These properties make graphitic carbon nitrides potentially useful in overcoming the limitations of 0D molecular and 1D polymer semiconductors. In this contribution, we study structural, vibrational, electronic and transport properties of nano-crystals of poly(triazine-imide) (PTI) derivatives with intercalated Li- and Br-ions and without intercalates. Intercalation-free poly(triazine-imide) (PTI-IF) is corrugated or AB stacked and partially exfoliated. We find that the lowest energy electronic transition in PTI is forbidden due to a non-bonding uppermost valence band and that its electroluminescence from the π-π* transition is quenched which severely limits their use as emission layer in electroluminescent devices. THz conductivity in nano-crystalline PTI is up to eight orders of magnitude higher than the macroscopic conductivity of PTI films. We find that the charge carrier density of PTI nano-crystals is among the highest of all known intrinsic semiconductors, however, macroscopic charge transport in films of PTI is limited by disorder at crystal-crystal interfaces. Future device applications of PTI will benefit most from single crystal devices that make use of electron transport in the lowest, π-like conduction band.

Polarization Resolved Optical Excitation of Charge-Transfer Excitons in PEN:PFP Cocrystalline Films: Limits of Nonperiodic Modeling

Charge-transfer excitons (CTXs) at organic donor/acceptor interfaces are considered important intermediates for charge separation in photovoltaic devices. Crystalline model systems provide microscopic insights into the nature of such states as they enable microscopic structure-property investigations. Here, we use angular-resolved UV/vis absorption spectroscopy to characterize the CTXs of crystalline pentacene:perfluoro-pentacene (PEN:PFP) films allowing determination of the polarization of this state. This analysis is complemented by first-principles many-body calculations, performed on the three-dimensional PEN:PFP cocrystal, which confirm that the lowest-energy excitation is a CTX. Analogous simulations performed on bimolecular clusters are unable to reproduce this state. We ascribe this failure to the lack of long-range interactions and wave function periodicity in these cluster calculations, which appear to remain a valid tool for modeling properties of organic materials ruled by local intermolecular couplings.

Optimized Synthesis of Solution-Processable Crystalline Poly(Triazine Imide) with Minimized Defects for OLED Application

Poly(triazine imide) (PTI) is a highly crystalline semiconductor, and though no techniques exist that enable synthesis of macroscopic monolayers of PTI, it is possible to study it in thin layer device applications that are compatible with its polycrystalline, nanoscale morphology. We find that the by‐product of conventional PTI synthesis is a C−C carbon‐rich phase that is detrimental for charge transport and photoluminescence. An optimized synthetic protocol yields a PTI material with an increased quantum yield, enabled photocurrent and electroluminescence. We report that protonation of the PTI structure happens preferentially at the pyridinic N atoms of the triazine rings, is accompanied by exfoliation of PTI layers, and contributes to increases in quantum yield and exciton lifetimes. This study describes structure–property relationships in PTI that link the nature of defects, their formation, and how to avoid them with the optical and electronic performance of PTI. On the basis of our findings, we create an OLED prototype with PTI as the active, metal‐free material.

Ab initio modelling of local interfaces in doped organic semiconductors

Doping in organic semiconductors remains a debated issue from both an experimental and ab initio perspective. Due to the complexity of these systems, which exhibit a low degree of crystallinity and high level of disorder, modelling doped organic semiconductors from first-principles calculations is not a trivial task, as their electronic and optical properties are sensitive to the choice of initial geometries. A crucial aspect to take into account, in view of rationalizing the electronic structure of these materials through ab initio calculations, is the role of local donor/acceptor interfaces. We address this problem in the framework of state-of-the-art density-functional theory and many-body perturbation theory, investigating the structural, electronic, and optical properties of quaterthiophene and sexithiophene oligomers doped by 2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-quinodimethane (F4TCNQ). We consider different model structures ranging from isolated dimers and trimers, to periodic stacks. Our results demonstrate that the choice of the initial geometry critically impacts the resulting electronic structure and the degree of charge transfer in the materials, depending on the amount and on the nature of the local interfaces between donor and acceptor species. The optical spectra appear less sensitive to these parameters at least from a first glance, although a quantitative analysis of the excitations reveals that their Frenkel or charge-transfer character is affected by the characteristics of the donor/acceptor interfaces as well as by the donor length. Our findings represent an important step forward towards an insightful first-principles description of the microscopic properties of doped organic semiconductors complementary to experiments.

Quantifying the Plasmonic Character of Optical Excitations in a Molecular J-Aggregate

The definition of plasmon at the microscopic scale is far from being understood. Yet, it is very important to recognize plasmonic features in optical excitations, as they can inspire new applications and trigger new discoveries by analogy with the rich phenomenology of metal nanoparticle plasmons. Recently, the concepts of plasmonicity index and the generalized plasmonicity index (GPI) have been devised as computational tools to quantify the plasmonic nature of optical excitations. The question may arise whether any strong absorption band, possibly with some sort of collective character in its microscopic origin, shares the status of plasmon. Here we demonstrate that this is not always the case, by considering a well-known class of systems represented by J-aggregates molecular crystals, characterized by the intense J band of absorption. By means of first-principles simulations, based on a many-body perturbation theory formalism, we investigate the optical properties of a J-aggregate made of push–pull organic dyes. We show that the effect of aggregation is to lower the GPI associated with the J-band with respect to the isolated dye one, which corresponds to a nonplasmonic character of the electronic excitations. In order to rationalize our finding, we then propose a simplified one-dimensional theoretical model of the J-aggregate. A useful microscopic picture of what discriminates a collective molecular crystal excitation from a plasmon is eventually obtained.

Interplay between Intra- and Intermolecular Charge Transfer in the Optical Excitations of J-Aggregates

In a first-principles study based on density functional theory and many-body perturbation theory, we address the interplay between intra- and intermolecular interactions in a J-aggregate formed by push-pull organic dyes by investigating its electronic and optical properties. We find that the most intense excitation dominating the spectral onset of the aggregate, i.e., the J-band, exhibits a combination of intramolecular charge transfer, coming from the push-pull character of the constituting dyes, and intermolecular charge transfer, due to the dense molecular packing. We also show the presence of a pure intermolecular charge-transfer excitation within the J-band, which is expected to play a relevant role in the emission properties of the J-aggregate. Our results shed light on the microscopic character of optical excitations of J-aggregates and offer new perspectives to further understand the nature of collective excitations in organic semiconductors.

Solid-State Effects on the Optical Excitation of Push-Pull Molecular J-Aggregates by First-Principles Simulations

J-aggregates are a class of low-dimensional molecular crystals which display enhanced interaction with light. These systems show interesting optical properties as an intense and narrow red-shifted absorption peak (J-band) with respect to the spectrum of the corresponding monomer. The need to theoretically investigate optical excitations in J-aggregates is twofold: a thorough first-principles description is still missing and a renewed interest is rising recently in understanding the nature of the J-band, in particular regarding the collective mechanisms involved in its formation. In this work, we investigate the electronic and optical properties of a J-aggregate molecular crystal made of ordered arrangements of organic push-pull chromophores. By using a time-dependent density functional theory approach, we assess the role of the molecular packing in the enhancement and red shift of the J-band along with the effects of confinement in the optical absorption, when moving from bulk to low-dimensional crystal structures. We simulate the optical absorption of different configurations (i.e., monomer, dimers, a polymer chain, and a monolayer sheet) extracted from the bulk crystal. By analyzing the induced charge density associated with the J-band, we conclude that it is a longitudinal excitation, delocalized along parallel linear chains and that its overall red shift results from competing coupling mechanisms, some giving red shift and others giving blue shift, which derive from both coupling between transition densities and renormalization of the single-particle energy levels.

Studies of the Clinical Pharmacology and Therapeutic Efficacy of Pentoxifylline in Peripheral Obstructive Arterial Disease

Studies were carried out to investigate the effects of pentoxifylline on various hemorheological (whole blood, plasma and serum viscosity, erythrocyte filtrability, hematocrit), hemostasiological (blood coagulation and fibrinolysis: euglobulin lysis time, fibrinogen, plasminogen, alpha-2-macroglobulin, alpha-1-antitrypsin, antiplasmin; platelet function: β-thromboglobulin), and hemodynamic factors (limb perfusion: rest and peak flow, time to peak flow; systemic blood pressure, heart rate). In addition, clinical efficacy was monitored in claudicants by assessing walking capacity under placebo controlled double blind cross over conditions. The investigations disclosed the positive influence of acute and chronic pentoxifylline administration on hemorheological, hemostasiological and perfusion parameters, most of the changes recorded being statistically significant. The clinical benefit of pentoxifylline (Trental 400) treatment was demonstrated by the significantly superior increase in walking capacity in comparison to placebo in the controlled study.

Site-specific interactions of copper(II) ions with heparin revealed with complementary (SRCD, NMR, FTIR and EPR) spectroscopic techniques

The interactions between Cu(II) ions and heparin were investigated using several complementary spectroscopic techniques. NMR indicated an initial binding phase involving specific coordination to four points in the structure that recur in slightly different environments throughout the heparin chain; the carboxylic acid group and the ring oxygen of iduronate-2-O-sulfate, the glycosidic oxygen between this residue and the adjacent (towards the reducing end) glucosamine and the 6-O-sulfate group. In contrast, the later binding phase showed little structural specificity. One- and two-dimensional correlated FTIR revealed that complex out of phase (asynchronous) conformational changes also occurred during the titration of Cu(II) ions into heparin, involving the CO and N-H stretches. EPR demonstrated that the environments of the Cu(II) ions in the initial binding phase were tetragonal (with slightly varied geometry), while the later non-specific phases exhibited conventional coordination. Visible spectroscopy confirmed a shift of the absorbance maximum. Titration of Cu(II) ions into a solution of heparin indicated (both by analysis of FTIR and EPR spectra) that the initial binding phase was complete by 15-20 Cu(II) ions per chain; thereafter the ions bound in the non-specific mode. Hetero-correlation spectroscopy (FTIR-CD) improved resolution and assisted assignment of the broad CD features from the FTIR spectra and indicated both in-phase and more complex out of phase (synchronous and asynchronous, respectively) changes in interactions within the heparin molecule during the titration of Cu(II) ions.

Lack of genetic structure of Cypriot Alectoris chukar (Aves, Galliformes) populations as inferred from mtDNA sequencing data

The Chukar (Alectoris chukar cypriotes) is the most common game bird in Cyprus. Since 1990 the Cypriot Government has established a restocking program with captive-reared birds. However, this program has not been guaranteed by checking the genetic nature of wild and farmed samples, either in the areas controlled by the Cypriot Government or in northern Cyprus. The sequencing of both Cytochrome-b and Control Region of the mitochondrial DNA was carried out for 61 Cypriot representatives and 14 specimens of the same subspecies from Crete and Israel. Only the A. chukar maternal lineage was found. A partitioning of Cypriot specimens among different clades was not reliably supported, whereas robust bootstrap values weighted for an evolutionary divergence between Cypriot and Cretan Chukars. An overall genetic homogeny of the Cypriot populations was disclosed, whatever their status (captive vs. wild stocks) and origin (Government controlled vs. occupied areas) would be, a higher nucleotide diversity of the wild vs. captive representatives notwithstanding.

[Laparoscopic hysterectomy in the management of endometrial cancer]

Endometrial carcinoma is the most commonly reported gynaecologic malignancy in industrialized countries. Traditionally the surgical treatment of endometrial cancer is total abdominal hysterectomy, bilateral salpingo-oophorectomy, and peritoneal washing cytology. Alternative surgical procedures have been proposed compared to abdominal hysterectomy: increased number of issues about laparoscopy shows the common trend to use this technique. Literature largely described advantages of the laparoscopic procedure compared to abdominal and vaginal surgery. Long-term follow-up series are not available; further investigation into survival and recurrence rates is indicated.

In vitro and in vivo synergy of levofloxacin or amikacin both in combination with ceftazidime against clinical isolates of Pseudomonas aeruginosa

The aim of the present study was to explore the antibacterial activity of the levofloxacin (LVX) and ceftazidime (CAZ) combination compared with the amikacin (AMK)/CAZ combination against Pseudomonas aeruginosa. Minimum inhibitory concentrations (MICs) were determined according to NCCLS. FIC indices (Fl) were calculated by the checkerboard technique. CAZ combined with LVX or AMK yielded Fls indicating synergism (Fl < or = 0.5) for 71/102 (69.6%) and 81/102 (79.4%) (p = 0.108), indifference (FI > 0.5-4) for 24/102 (23.5%) and 12/102 (11.7%) (p = 0.027), and antagonism (Fl > 4) for 7/102 (6.8%) and 9/102 (8.8%) (p = 0.602) strains, respectively. In vivo, CAZ/LVX was as bactericidal as CAZ/AMK combination. Our results support the potential role of LVX as an alternative to AMK in the combination therapy with CAZ in the treatment of P. aeruginosa severe infections. Anyway, further investigations and clinical trials are awaited until any definitive conclusions can be drawn.

GnRH Agonist Treatment before Total Laparoscopic Hysterectomy for Large Uteri

STUDY OBJECTIVE

To evaluate whether uterine shrinkage induced by gonadotropin-releasing hormone (GnRH) agonists in women with a large uterus (>14 wks) may facilitate total laparoscopic hysterectomy.

DESIGN

Randomized, prospective study (Canadian Task Force classification I).

SETTING

University-affiliated hospital.

PATIENTS

Sixty-two women with symptomatic uterine myomas (size 16-20 wks).

INTERVENTIONS

Total laparoscopic hysterectomy for benign pathology.

MEASUREMENTS AND MAIN RESULTS

Before surgery, women were assigned, at a ratio of 1:1 by random selection, to receive injections of triptorelin depot 11.25 mg 3 months before surgery (group A) or no treatment (group B). Uterine volume, mean operating time, uterine weight, drop in hemoglobin, intraoperative complications, conversions to laparotomy, and hospital stay were recorded. Triptorelin decreased uterine volume, calculated by ultrasonography, by 26.5% in group A, whereas the volume remained unchanged in group B. Statistical differences were found between groups concerning uterine weight, operating time, and drop in hemoglobin level. Three patients in group B were converted to laparotomy because of uterine size.

CONCLUSION

In women with a large uterus, a 3-month preoperative course of GnRH may facilitate laparoscopic hysterectomy, decreasing uterine size, operating time, and blood loss.

Haemorheological and endothelial-dependent alterations in heart failure after ACE inhibitor, calcium antagonist and beta blocker

The aim of our study was to evaluate endothelium-dependent dilatation induced by an ACE-inhibitor, calcium antagonist and beta blocker in patients suffering from heart failure (NYHA class II and III). We studied 34 patients (19M, 15F, mean age 76.96+/-8.82) in pharmacological wash-out for at least one week, divided into 3 groups: Group A (15 patients, 9M and 6F) taking ramipril (5 mg/die); Group B (10 patients, 6M and 4F) taking amlodipine (10 mg/die), Group C: (9 patients, 4M and 5F) taking carvedilole (25 mg/die). The groups were homologous for NYHA class and instrumental echographic parameters (mean EF=22.5+/-6.7 and mean sAPP 38.4+/-8.7). At the beginning and after 3 weeks of therapy, we performed a clinical and instrumental assessment; we studied endothelial function by determination of L-arginine and L-citrulline (amino acids of the nitric oxide metabolic pathway), the L-citrulline/L-arginine ratio (an index of NOS activity) and VCAM-1 (endothelial dysfunction index); haemorheological parameters (blood viscosity, plasma fibrinogen and erythrocyte morphology); coagulative/fibrinolytic parameters (PT, aPTT, fibrinogen and PAI-1). The results show that L-citrulline and L-arginine increase, while VCAM-1 decreases. The L-citrulline/L-arginine ratio increases in a statistically significant way. This trend is maintained in each group. These results demonstrate that the drugs used induce an improvement of endothelium-dependent dilatation. In addition, there is progressive haemorheological and fibrinolytic improvement, with a reduction of PAI-1 and blood viscosity.

Spontaneous echo-contrast as an in vivo indicator of rheological imbalance in dilatative cardiomyopathy

The aim of this study was to evaluate coagulative and hemorheologic assessment in patients with dilatative cardiomyopathy with or without spontaneous echo contrast (SEC). We studied 45 patients, 35 males and 10 females (mean age 72.1 +/- 9.2). We measured whole blood viscosity, plasmatic fibrinogen, prothrombin time (PT), activated partial thromboplastin time (aPTT), D-dimer and red cell morphology with Zipursky-Forconi method. Transthoracic and transesophageal echocardiography was performed in all patients to evaluate the presence of SEC in left atrium. We divided all the patients into two groups: the 1st group of 20 patients with SEC and Atrial Fibrillation (AF) in 80% of cases, and the 2nd group of 25 patients without SEC and AF in 31%. Our results show that in patients with SEC there is a statistically significant increase of whole blood viscosity and plasma fibrinogen in comparison with patients without SEC. Red cell morphology in all patients demonstrates a reversed EMI. D-Dimer, was out of the normal range in about 1/3 of the patients in both groups. An analysis of our results points out that in patients with SEC and AF, with a major risk factor for cardioembolic stroke, we have alterations of hemorheologic assessment with an increase of whole blood viscosity and fibrinogen that seems to be caused by an increase of red cells aggregability favoured by fibrinogen. Our conclusions are that SEC in patients with dilatative cardiomyopathy and AF is an important in vivo indicator of hemorheologic imbalance and an important marker for cardioembolic risk stroke evaluation.

Cycloartane saponins from Astragalus peregrinus as modulators of lymphocyte proliferation

From Astragalus peregrinus, four cycloartane-type saponins have been isolated and their structures elucidated by spectral means as 20(R),24(S)-epoxy-9 beta,19-cyclolanostane-3 beta,6 alpha,16 beta,25-tetrol 3-O-beta-D-glucopyranoside (1), 20(R),24(S)-epoxy-9 beta,19-cyclolanostane-3 beta,6 alpha,16 beta,25-tetrol 3-O-alpha-L-rhamnopyranosyl-(1-->4)-beta-D-glucopyranoside (2), 20(R),24(S)-epoxy-9 beta,19-cyclolanostane-3 beta,6 alpha,16 beta,25-tetrol 3-O-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-glucopyranoside (3) and 20(R),25-epoxy-9 beta,19-cyclolanostane-3 beta,6 alpha,16 beta,24(S)-tetrol (24-O-acetyl)- 3-O-alpha-L-rhamnopyranosyl-(1-->2)-(6'-O-acetyl)-beta-D-glucopyranoside (4). Compounds 2 and 3 showed to stimulate the proliferation of mouse splenocytes and were not significantly cytotoxic.

Conformation of heparin pentasaccharide bound to antithrombin III

The interaction, in aqueous solution, of the synthetic pentasaccharide AGA*IA(M) (GlcN,6-SO(3)alpha 1-4GlcA beta 1-4GlcN,3,6-SO(3)alpha 1-4IdoA,2-SO(3)alpha 1-4GlcN,6-SO(3)alpha OMe; where GlcN,6-SO(3) is 2-deoxy-2-sulphamino-alpha-D-glucopyranosyl 6-sulphate, IdoA is l-iduronic acid and IdoA2-SO(3) is L-iduronic acid 2-sulphate), which exactly reproduces the structure of the specific binding sequence of heparin and heparan sulphate for antithrombin III, has been studied by NMR. In the presence of antithrombin there were marked changes in the chemical shifts and nuclear Overhauser effects (NOEs), compared with the free state. On the basis of the optimized geometry of the pentasaccharide the transferred NOEs were interpreted with full relaxation and conformational exchange matrix analysis. An analysis of the three-dimensional structures of the pentasaccharide in the free state, and in the complex, revealed the binding to be accompanied by dihedral angle variation at the A-G and I-A(M) (where G, I, A and A(M) are beta-d-glucuronic acid, 2-O-sulphated alpha-L-iduronic acid, N,6-O-sulphated alpha-D-glucosamine and the alpha-methyl-glycoside of A respectively) glycosidic linkages. Evidence is also provided that the protein drives the conformation of the 2-O-sulphated iduronic acid residue towards the skewed (2)S(0) form.

Combined quantitative (1)H and (13)C nuclear magnetic resonance spectroscopy for characterization of heparin preparations

The sulfation patterns of pig and bovine mucosal commercial heparin preparations can be characterized and distinguished from each other easily by analysis of their monodimensional proton and carbon nuclear magnetic resonance ((1)H and (13)C-NMR) spectra. NMR spectroscopy can detect and quantify signals associated with major sequences as well as with minor residues such as the typical ones associated with the antithrombin (AT) binding sequence and the "linkage region." Contaminants arising from industrial preparation processes are also detectable.

Preserving the original heparin structure of a novel low molecular weight heparin by gamma-irradiation

Several preparations of low molecular weight heparins (LMWHs) obtained by physical depolymerisation (irradiation with gamma-rays) of pig mucosal heparin have been characterised by mono- and two-dimensional NMR spectroscopy. Integration of typical 1H- and 13C-NMR signals provided a useful quantification of their sulfation pattern. The availability of the corresponding parent heparins showed that the original structure (including that of the active site for antithrombin, as also confirmed by affinity chromatography) had not been significantly modified by the depolymerisation procedure. This process involves only a slight decrease of undersulfated sequences. A peculiarity of gamma-LMWH is the absence of the 'linkage region', commonly present in unmodified heparins and most LMWHs.

In vitro antiplasmodial activity of extracts of Tristaniopsis species and identification of the active constituents: ellagic acid and 3,4,5-trimethoxyphenyl-(6'-O-galloyl)-O-beta-D-glucopyranoside

Screening of plants from New Caledonia for antiplasmodial activity against Plasmodium falciparum revealed that methanolic extracts of the leaves and bark of Tristaniopsis calobuxus, T. yateensis, and T.glauca inhibited the growth of chloroquine-sensitive and -resistant clones. Ellagic acid and the new compound 3,4,5-trimethoxyphenyl-(6'-O-galloyl)-O-beta-D-glucopyranoside were identified as the active constituents (IC50 0.5 and 3.2 microM, respectively). The growth inhibition of both clones was comparable. The compounds showed negligible or very low cytotoxicity to human skin fibroblasts and Hep G2 cells when tested at concentrations ranging from 0.5 to 100 microM.

Blood viscosity and red cell morphology in subjects suffering from cirrhosis before and after treatment with S-adenosyl-L-methionine (SAM)

Alterations of fluidity of the hepatocytic membrane and of the transport related systems are the basis of the cholesteatic syndrome and favour the tissue accumulation of cytotoxic metabolites. S-Adenosyl-L-Methionine (SAM) is a natural molecule which acts as a giver of methylic groups and as an enzymatic activator in several enzymatic actions of transmethylase and of transulphuration and plays a key role in biochemical processes of hepatic cell. The aim of our study was to evaluate the effects of SAM on the restoration of the membrane fluidity and on the hepatic function in general. In studying the fluidity of the cell membrane we evaluated some hemorheological parameters (total blood viscosity and red cell morphology). Fluidity of the red cell membrane is one of the most important elements of red cell rheology. We studied 15 patients (Group A) suffering from micro- and macro-nodular cirrhosis verified through hepatic biopsy, with alcoholic or post-viral causes. We evaluated the values of: blood viscosity (with a cone-plate rheometer by Carri-med), haematocrit, plasma fibrinogen and the erythrocytic morphology at the optical microscope with the Zipursky-Forconi method before and after 7 days of therapy with SAM i.v.. Data were compared with those of a similar group (Group B) treated with traditional therapy only (hyposodic and hypoprotein diet supplemented with multivitamin preparations, vitamin K in particular, if necessary, and potassium sparing diuretics). We also measured biliary salts, alkaline phosphatase, transaminase and gamma-GT. In the first group we observed a statistically significant reduction of blood viscosity, haematocrit didn't change significantly; biliary salts reduced in a statistically significant way. Evaluation of red cell morphology showed in all cases a pathological percentage (>15%) of echinocytes and knizocytes which reduced to a mean of 5% after SAM therapy. We observed no further modifications of the other hemorheological parameters. Results demonstrate that SAM has a positive action on the fluidity of the membrane, as indicated by the improvement of haemorheological parameters and by the significant decrease of biliary salts, indicating the presence of cholesteasis.

Effect of substitution pattern on 1H, 13C NMR chemical shifts and 1J(CH) coupling constants in heparin derivatives

1H, 13C NMR chemical shifts and 1J(CH) coupling constants were measured for derivatives of heparin containing various sulfation patterns. 1H and 13C chemical shifts varied considerably after introducing electronegative sulfate groups. Chemical shifts of protons linked to carbons changed by up to 1 ppm on substitution with O- and N-sulfate or acetyl groups. Differences up to 10 ppm were detected for 13C chemical shifts in substituted glucosamine, but a less clear dependence was found in iduronate. 1J(CH) values formed two groups, corresponding to either sulfation or non-sulfation at positions 2 and 3 of glucosamine. O-sulfation caused increases up to 6 Hz in 1J(CH) and N-sulfation decreases up to 4 Hz. N-acetylation gave similar 1J(CH) values to N-sulfation. At positions 2 and 3 of iduronate the trend was less marked; 1J(CH) for O-sulfated positions usually increasing. Introduction of sulfate groups influences chemical shift and 1J(CH) values at the position of substitution, but also at more remote positions. 1J(CH) at the glycosidic linkage positions varied between free-amino and N-sulfated compounds, by up to 9 Hz. These results and changes in chemical shift values suggest that iduronate residues and the glycosidic linkages are affected, indicating overall conformational change. This may have important implications for biological activities.

Pulmonary embolism in the elderly: clinical, instrumental and laboratory aspects

OBJECTIVE

To focus on diagnostic and therapeutic problems of pulmonary embolism in the elderly.

METHODS

Retrospective analysis of 5 years of clinical, instrumental, and laboratory data (collected at the time of hospital admission) for patients 65 years and older with pulmonary embolism proven by a high-probability scintigraphic lung scan or necropsy. Sixty-eight patients, 46 females and 22 males, 78.61 +/- (SD) 7.71 years old, were enrolled in the study.

RESULTS

Dyspnea, chest pain, tachycardia, and tachypnea were the most common symptoms and signs; they were present alone or in combination in all patients. Bed rest over 4 days was found in 65% of the patients and deep vein thrombosis in the leg in 35%. Only 7 patients were on anticoagulant therapy which was likely to reduce the incidence of pulmonary embolism. The mortality was 29.5%. Major bleeding due to anticoagulant therapy was observed in 4.4% of the patients; 1 case was fatal. Sinus tachycardia, ST segment and T wave abnormalities in anterior leads, and incomplete bundle branch block were the most frequent electrocardiographic findings. Chest X-ray was normal in 19.5% of the patients and compatible with pulmonary embolism in 10%. A transthoracic two-dimensional echocardiogram was abnormal in 74% of the cases, with involvement of the right ventricle in the majority of them. Many patients had laboratory parameters within the normal range. The value of the latex agglutination D-dimer assay was less than the cutoff value of 500 microg/l in 16% of the patients. Hypoxemia and a high alveolar-arterial oxygen gradient were the most frequent aspects of the arterial blood gas analysis. Respiratory alkalosis was observed in only one third of the patients.

CONCLUSIONS

Pulmonary embolism is often underdiagnosed in the elderly. Clinical, instrumental, and laboratory findings are nonspecific. Only acute suspicion can increase the number of diagnoses, reduce the time to diagnosis, and improve the prognosis.

A novel heparan sulphate with high degree of N-sulphation and high heparin cofactor-II activity from the brine shrimp Artemia franciscana

With the aid of heparinase and heparitinases from Flavobacterium heparinum and 13C and IH NMR spectroscopy it was shown that the heparan sulphate isolated from the brine shrimp Artemia franciscana exhibits structural features intermediate between those of mammalian heparins and heparan sulphates. These include an unusually high degree of N-sulphation (with corresponding very low degree of N-acetylation), a relatively high content of iduronic acid residues (both unsulphated and 2-O-sulphated) and a relatively low degree of 6-O-sulphation of the glucosamine residues. The major sequences (glucuronic acid-->N-sulphated glucosamine and glucuronic acid-->N, 6-disulphated glucosamine) are most probably arranged in blocks. Although exhibiting negligible anticlotting activity in the APTT and anti-factor Xa assays the A. franciscana heparan sulphate has a high heparin cofactor-II activity (about 1/3 that of heparin).

Evaluation of hemorheological parameters and red cell morphology in hypertension

The aim of our study was to evaluate hemorheological parameters in two groups of patients both suffering from essential hypertension compared with an homologous group of subjects not suffering from hypertension; the 1st group was composed of 16 patients (8 females and 8 males, mean age 65.6 +/- 16.5) suffering from essential hypertension; the 2nd one of 26 patients (8 females and 18 males, mean age 74.3 +/- 11.7) suffering from essential hypertension and cerebral or cardiac ischemia in a chronic phase. The group of controls was composed of 20 subjects (mean age 50.5 +/- 11.5). In all these subjects we evaluated: blood viscosity, hematocrit, plasmatic fibrinogen, red cell morphology according to Zipursky-Forconi method and blood pressure. Our results show that blood viscosity and fibrinogen were statistically increased relative to controls. Comparison between these groups leads us to observe that blood viscosity and fibrinogen are slightly higher in the first group in a statistically significant way (7.5 +/- 1.1 cPs 10 s(-1) 1st group, 7.9 +/- 1.05 cPs 10 s(-1) 2nd group; 362.2 +/- 167.3 mg% 1st group, 384.6 +/- 106.9 mg% 2nd group). Blood pressure was higher in the second group. The study of red cell morphology in all the patients showed a prevalence in the percentage of discocytes, cells which have less deformability compared to bowls. The study demonstrated EMI (Erythrocyte Morphology Index) decreased in a statistically significant way compared to controls (0.70 +/- 0.03 1st group; 0.65 +/- 0.02 2nd group; 1.2 +/- 0.09 control group). In subjects suffering from essential hypertension with end-organ damage EMI further decreases. So we observed that hypertension is also delineated by the increase in the discocytes percentage which results in reduction of the red cell deformability. In conclusion, when hypertension causes end-organ damage, the hemorheological alterations, which implicate a worsening in microcirculation, are more evident.

Length of hospitalization in elderly patients with community-acquired pneumonia

Community-acquired pneumonia (CAP) is a serious social and medical problem in the elderly. Mortality, hospitalization and length of stay increase with age. The aim of this study was to determine the risk factors associated with prolonged hospital stay in elderly patients with CAP. Clinical and laboratory data were collected for 115 community-living patients, 65 years old and over, admitted to the geriatric ward of a University Hospital from 1995 to 1998 because of symptoms and signs of pneumonia confirmed by a pulmonary infiltrate on chest x-ray. We divided the patients into two groups, with length of stay more than 13 days (70 patients, cases), and length of stay less than 13 days (45 patients, controls) according to Diagnosis Related Groups criteria for complicated and uncomplicated pneumonia, respectively. A prolonged hospital stay was associated with a higher fever peak and a higher number of days with fever (p<0.005), greater comorbidity (p<0.001), urinary catheterization and secondary urinary infections (p<0.001), higher erythrocyte sedimentation rate (p<0.001), dehydration (p<0.005), and caloric-proteic malnutrition (p=0.01). In conclusion, knowledge of the risk factors for prolonged hospital stay in elderly patients with CAP may be used to identify high-risk patients, prevent the risks with prophylactic measures, and contain the costs of hospitalization.

"Linkage region" sequences of heparins and heparan sulfates: detection and quantification by nuclear magnetic resonance spectroscopy

The (13)C NMR spectra of most heparin and heparan sulfate preparations display minor signals not attributable to the glycosaminoglycan chains of these polysaccharides. These signals have been "concentrated" in oligosaccharides isolated from an acid hydrolyzate of heparin and shown to arise from the sequence GlcA-Gal-Gal-Xyl of the "linkage region" (LR) connecting the carbohydrate chains to the peptide chains in the original proteoglycans. Mono- and two-dimensional (1)H and (13)C NMR analysis of the major oligosaccharide (LR-OLIGO) indicated the prevalent structure GlcA-GlcNAc-GlcA-Gal-Gal-Xyl, where GlcNAc is partially 6-O-sulfated. (13)C NMR signals at 84.6 and 85.0 ppm, arising from C-3 of the two Gal residues, lend themselves to easy detection and quantification of the linkage region in heparins and heparan sulfates and can be used to assess the importance of the LR in the modulation of various biological activities of these glycosaminoglycans.

Structure of heparin-derived tetrasaccharide complexed to the plasma protein antithrombin derived from NOEs, J-couplings and chemical shifts

A complex of the synthetic tetrasaccharide AGA*IM [GlcN, 6-SO3-alpha(1-4)-GlcA-beta(1-4)-GlcN,3, 6-SO3-alpha(1-4)-IdoA-alphaOMe] and the plasma protein antithrombin has been studied by NMR spectroscopy. 1H and 13C chemical shifts, three-bond proton-proton (3JH-H) and one-bond proton-carbon coupling constants (1JC-H) as well as transferred NOEs and rotating frame Overhauser effects (ROEs) were monitored as a function of the protein : ligand molar ratio and temperature. Considerable changes were observed at both 20 : 1 and 10 : 1 ratios (AGA*IM : antithrombin) in 1H as well as 13C chemical shifts. The largest changes in 1H chemical shifts, and the linewidths, were found for proton resonances (A1, A2, A6, A6', A1*, A2*, A3*, A4*) in GlcN, 6-SO3 and GlcN,3,6-SO3 units, indicating that both glucosamine residues are strongly involved in the binding process. The changes in the linewidths in the IdoA residue were considerably smaller than those in other residues, suggesting that the IdoA unit experienced different internal dynamics during the binding process. This observation was supported by measurements of 3JH-H and 1JC-H. The magnitude of the three-bond proton-proton couplings (3JH1-H2 = 2.51 Hz and 3JH4-H5 = 2.23 Hz) indicate that in the free state an equilibrium exists between 1C4 and 2S0 conformers in the ratio of approximately 75 : 25. The chair form appears the more favourable in the presence of antithrombin, as inferred from the magnitude of the coupling constants. In addition, two-dimensional NOESY and ROESY experiments in the free ligand, as well as transferred NOESY and ROESY spectra of the complex, were measured and interpreted using full relaxation and conformational exchange matrix analysis. The theoretical NOEs were computed using the geometry of the tetrasaccharide found in a Monte Carlo conformational search, and the three-dimensional structures of AGA*IM in both free and bound forms were derived. All monitored NMR variables, 1H and 13C chemical shifts, 1JC-H couplings and transferred NOEs, indicated that the changes in conformation at the glycosidic linkage GlcN, 6-SO3-alpha(1-4)-GlcA were induced by the presence of antithrombin and suggested that the receptor selected a conformer different from that in the free state. Such changes are compatible with the two-step model [Desai, U.R., Petitou, M., Bjork, I. & Olson, S. (1998) J. Biol. Chem. 273, 7478-7487] for the interaction of heparin-derived oligosaccharides with antithrombin, but with a minor extension: in the first step a low-affinity recognition complex between ligand and receptor is formed, accompanied by a conformational change in the tetrasaccharide, possibly creating a complementary three-dimensional structure to fit the protein-binding site. During the second step, as observed in a structurally similar pentasaccharide [Skinner, R., Abrahams, J.-P., Whisstock, J.C., Lesk, A.M., Carrell, R.W. & Wardell, M.R. (1997) J. Mol. Biol. 266, 601-609; Jin, L., Abrahams, J.-P., Skinner, R., Petitou, M., Pike, R. N. & Carrell, R.W. (1997) Proc. Natl Acad. Sci. USA 94, 14683-14688], conformational changes in the binding site of the protein result in a latent conformation.

Haemorheological disturbances and possibility of their correction in cerebrovascular diseases

The presence of a hemorheological disturbance must be considered in the pathophysiological and therapeutical approach to vascular diseases, including cerebral diseases. A reduction of blood fluidity, due either to increase of hematocrit (polycythemic hyperviscosity) or of fibrinogen concentration (plasmatic hyperviscosity) or of red cell rigidity (sclerocythemic hyperviscosity) is commonly considered a condition of high risk for acute or chronic brain ischemia. So many attempts have been made for improving blood fluidity with the purpose to prevent stroke and to delay cerebral deterioration in chronic condition. This paper will present a review of the literature on this subject and the personal experience of our research group with the use of hemodilution, plasmapheresis and pharmacological agents. In our opinion the possible correction of hyperviscosity is very helpful in the prevention of acute ischemic attacks and in the reduction of their incidence in chronic cerebral ischemia. During the acute phase of stroke, hemorheological disturbance is only a part of the complex hemodynamic situation: a primary blood hyperviscosity can favor the onset of the disease but, because of its secondary increase after stroke, a vicious circle might be set in motion resulting in a further reduction of blood supply to the brain. Considering this, attempts in improving blood fluidity during stroke could be made, but with the caution that is required in this complicated "circulatory storm".

[Critical ischemia in elderly patients. Evaluation of the effect of two different methods of Iloprost therapy on the efficacy, tolerance, modification of quality of life and self-sufficiency]

BACKGROUND

The use of Iloprost in the treatment of critical leg ischemia in very old patients can lead to tolerability problems, related to the drug used and to the kind of patient treated. The aim of this study was to evaluate the impact of this therapy on the activities of daily living and on the quality of life of the patient together with its efficacy and tolerability.

METHODS

We studied 20 subjects (mean age 74 +/- 6.8) divided in 2 groups homogeneous for age, seriousness of the disease and presence of diabetes mellitus. In the first group Iloprost was administered for 6 hours, for 28 consecutive days, in the second group for 6 hours, two times a day for 14 consecutive days. In each group we observed the following parameters before and after treatment: clinical evaluation of pain and use of analgesics, ADL and SK39 questionnaire, ankle/arm index c.w. Doppler, strain gauge plethismography of lower limbs, TcPO2 at the back-feet level.

RESULTS

Treatment was well tolerated in both groups where we observed a similar reduction of pain, a reduction in the instrumental indexes which express the microcirculatory activity, an improvement in the quality of life and in the capacity to carry out everyday activities. The double daily administration of Iloprost did not cause any significant side effect in the subjects studied, and a better responsiveness to the pain symptomatology was observed.

CONCLUSIONS

Iloprost can be used in the treatment of critical leg ischemia even for very old patients with good tolerability and effectiveness. In the double daily administration no relevant side effect was observed. This approach is to be preferred also in terms of cost-effectiveness.

Evaluation of erythrocyte morphology as deformability index in patients suffering from vascular diseases, with or without diabetes mellitus: correlation with blood viscosity and intra-erythrocytic calcium

The aim of our study was to evaluate the erythrocytic morphology in vascular patients, with or without diabetes, showing cell alterations correlated to blood viscosity and intra-erythrocytic calcium. We studied 108 subjects: 20 normal subjects, 58 vascular patients (25 suffering from CHD, 19 from CVD, 14 from POAD) and 30 non-insulin-dependent diabetes patients with vascular disease in metabolic compensation (13 CHD, 9 CVD, 8 POAD). Erythrocytic morphology, blood viscosity and intra-erythrocytic calcium were evaluated. Our results show that bowls, the most deformable red cells, decreased significantly in vascular patients and in POAD diabetics, while the discocytes, having a stiffer form, greatly increased in subjects suffering from ischemic disease and in POAD diabetics. The altered red cells (echinocytes and knizocytes) reached a statistical significance in CVD and POAD diabetics. Comparing the percentage of discocytes to intraerythrocytic calcium content in vasculopathic subjects, we obtained a significant correlation. No evidence of a relationship between discocytes and blood viscosity was found, even if blood viscosity significantly increased in patients affected by ischemic disease. These results suggest that ischemia decreases the deformability of red cells which is supported by the study of red cells morphology, by the erythrocytic morphology index (EMI), which becomes < 1, and by the evaluation of cytosolic calcium content.