Efficient SARS-CoV-2 infection antagonization by rhACE2 ectodomain multimerized onto the Avidin-Nucleic-Acid-NanoASsembly

Nanodecoy systems based on analogues of viral cellular receptors assembled onto fluid lipid-based membranes of nano/extravescicles are potential new tools to complement classic therapeutic or preventive antiviral approaches. The need for lipid-based membranes for transmembrane receptor anchorage may pose technical challenges along industrial translation, calling for alternative geometries for receptor multimerization. Here we developed a semisynthetic self-assembling SARS-CoV-2 nanodecoy by multimerizing the biotin labelled virus cell receptor -ACE2- ectodomain onto a poly-avidin nanoparticle (NP) based on the Avidin-Nucleic-Acid-NanoASsembly-ANANAS. The ability of the assembly to prevent SARS-CoV-2 infection in human lung cells and the affinity of the ACE2:viral receptor-binding domain (RBD) interaction were measured at different ACE2:NP ratios. At ACE2:NP = 30, 90 % SARS-CoV-2 infection inhibition at ACE2 nanomolar concentration was registered on both Wuhan and Omicron variants, with ten-fold higher potency than the monomeric protein. Lower and higher ACE2 densities were less efficient suggesting that functional recognition between multi-ligand NPs and multi-receptor virus surfaces requires optimal geometrical relationships. In vivo studies in mice showed that the biodistribution and safety profiles of the nanodecoy are potentially suitable for preventing viral infection upon nasal instillation. Viral receptor multimerization using ANANAS is a convenient process which, in principle, could be rapidly adapted to counteract also other viral infections.

RAndomized Clinical Trial Of NAfamostat Mesylate, A Potent Transmembrane Protease Serine 2 (TMPRSS2) Inhibitor, in Patients with COVID-19 Pneumonia

Even though SARS-CoV-2 was declared by WHO as constituting no longer a public health emergency, the development of effective treatments against SARS-CoV-2 infection remains a critical issue to prevent complications, particularly in fragile patients. The protease inhibitor nafamostat, currently used in Japan and Korea for pancreatitis, owing to its anticoagulant properties for disseminated intravascular coagulation (DIC), is appealing for the treatment of COVID-19 infection, because it potently inhibits the transmembrane protease serine 2 (TMPRSS2) that, after virus binding to ACE-2, allows virus entry into the cells and replication. Moreover, it could prevent the DIC and pulmonary embolism frequently associated with COVID-19 infection. The goal of the RAndomized Clinical Trial Of NAfamostat (RACONA) study, designed as a prospective randomized, double-blind placebo-controlled clinical trial, was to investigate the efficacy and safety of nafamostat mesylate (0.10 mg/kg/h iv for 7 days), on top of the optimal treatment, in COVID-19 hospitalized patients. We could screen 131 patients, but due to the predefined strict inclusion and exclusion criteria, only 15 could be randomized to group 1 (n = 7) or group 2 (n = 8). The results of an ad interim safety analysis showed similar overall trends for variables evaluating renal function, coagulation, and inflammation. No adverse events, including hyperkalemia, were found to be associated with nafamostat. Thus, the RACONA study showed a good safety profile of nafamostat, suggesting that it could be usefully used in COVID-19 hospitalized patients.

Development of a Nanoparticle-Based Approach for the Blood-Brain Barrier Passage in a Murine Model of Amyotrophic Lateral Sclerosis

The development of nanoparticles (NPs) to enable the passage of drugs across blood-brain barrier (BBB) represents one of the main challenges in neuropharmacology. In recent years, NPs that are able to transport drugs and interact with brain endothelial cells have been tested. Here, we investigated whether the functionalization of avidin-nucleic-acid-nanoassembly (ANANAS) with apolipoprotein E (ApoE) would allow BBB passage in the SOD1^G93A mouse model of amyotrophic lateral sclerosis. Our results demonstrated that ANANAS was able to transiently cross BBB to reach the central nervous system (CNS), and ApoE did not enhance this property. Next, we investigated if ANANAS could improve CNS drug delivery. To this aim, the steroid dexamethasone was covalently linked to ANANAS through an acid-reversible hydrazone bond. Our data showed that the steroid levels in CNS tissues of SOD1^G93A mice treated with nanoformulation were below the detection limit. This result demonstrates that the passage of BBB is not sufficient to guarantee the release of the cargo in CNS and that a different strategy for drug tethering should be devised. The present study furthermore highlights that NPs can be useful in improving the passage through biological barriers but may limit the interaction of the therapeutic compound with the specific target.

Angiotensin II Promotes SARS-CoV-2 Infection via Upregulation of ACE2 in Human Bronchial Cells

Blockers of the renin-angiotensin system (RAS) have been reported to increase the angiotensin converting enzyme (ACE)2, the cellular receptor of SARS-CoV-2, and thus the risk and course of COVID-19. Therefore, we investigated if angiotensin (Ang) II and RAS blockers affected ACE2 expression and SARS-CoV-2 infectivity in human epithelial bronchial Calu-3 cells. By infectivity and spike-mediated cell–cell fusion assays, we showed that Ang II acting on the angiotensin type 1 receptor markedly increased ACE2 at mRNA and protein levels, resulting in enhanced SARS-CoV-2 cell entry. These effects were abolished by irbesartan and not affected by the blockade of ACE-1-mediated Ang II formation with ramipril, and of ACE2- mediated Ang II conversion into Ang 1-7 with MLN-4760. Thus, enhanced Ang II production in patients with an activated RAS might expose to a greater spread of COVID-19 infection in lung cells. The protective action of Angiotensin type 1 receptor antagonists (ARBs) documented in these studies provides a mechanistic explanation for the lack of worse outcomes in high-risk COVID-19 patients on RAS blockers.

The mode of dexamethasone decoration influences avidin-nucleic-acid-nano-assembly organ biodistribution and in vivo drug persistence

Avidin-Nucleic-Acid-NanoASsemblies (ANANAS) possess natural tropism for the liver and, when loaded with dexamethasone, reduce clinical progression in an autoimmune hepatitis murine model. Here, we investigated the linker chemistry (hydrazide-hydrazone, Hz-Hz, or carbamate hydrazide-hydrazone, Cb-Hz bond) and length (long, 5 kDa PEG, or short, 5-6 carbons) in biotin-dexamethasone conjugates used for nanoparticle decoration through in vitro and in vivo studies. All four newly synthesized conjugates released the drug at acidic pH only. In vitro, the Hz-Hz and the PEG derivatives were less stable than the Cb-Hz and the short chain ones, respectively. Once injected in healthy mice, dexamethasone location in the PEGylated ANANAS outer layer favors liver penetration and resident macrophages uptake, while drug Hz-Hz, but not Cb-Hz, short spacing prolongs drug availability. In conclusion, the tight modulation of ANANAS decoration can significantly influence the host interaction, paving the way for the development of steroid nanoformulations suitable for different pharmacokinetic profiles.

Dexamethasone Conjugation to Biodegradable Avidin-Nucleic-Acid-Nano-Assemblies Promotes Selective Liver Targeting and Improves Therapeutic Efficacy in an Autoimmune Hepatitis Murine Model

Steroids are the standard therapy for autoimmune hepatitis (AIH) but the long-lasting administration is hampered by severe side effects. Methods to improve the tropism of the drug toward the liver are therefore required. Among them, conjugation to nanoparticles represents one possible strategy. In this study, we exploited the natural liver tropism of Avidin-Nucleic-Acid-Nano-Assemblies (ANANAS) to carry dexamethasone selectively to the liver in an AIH animal model. An acid-labile biotin-hydrazone linker was developed for reversible dexamethasone loading onto ANANAS. The biodistribution, pharmacokinetics and efficacy of free and ANANAS-linked dexamethasone (ANANAS-Hz-Dex) in healthy and AIH mice were investigated upon intraperitoneal administration. In ANANAS-treated animals, the free drug was detected only in the liver. Super-resolution microscopy showed that nanoparticles segregate inside lysosomes of liver immunocompetent cells, mainly involved in AIH progression. In agreement with these observational results, chronic low-dose treatment with ANANAS-Hz-Dex reduced the expression of liver inflammation markers and, in contrast to the free drug, also the levels of circulating AIH-specific autoantibodies. These data suggest that the ANANAS carrier attenuates AIH-related liver damage without drug accumulation in off-site tissues. The safety and biodegradability of the ANANAS carrier make this formulation a promising tool for the treatment of autoimmune liver disorders.

Gold-silver alloy semi-nanoshell arrays for label-free plasmonic biosensors

Nanosphere lithography coupled with reactive ion etching has been used to synthesize hexagonal ordered arrays of Au-Ag bimetallic semi-nanoshells to be used as plasmonic biosensors. The degree of lateral interaction between adjacent semi-nanoshells can be controlled by tailoring the reactive ion etching time in order to boost the global plasmonic properties through the formation of near-field hot-spots, which in turn can improve the sensitivity of the biosensors. To test the efficiency of the proposed system as a biosensor, we used an established protocol for the detection of biomolecules (local sensitivity), based on the receptor-ligand approach and using the biotin-streptavidin model system. We also tested the sensitivity to a homogeneous change in the refractive index of the buffer over the sensor (bulk sensitivity). Comparing the obtained results to those of an array of nanoprisms, chosen as a benchmark, significantly higher performances both in local and bulk sensitivities have been found, in agreement with electrodynamics simulations based on finite-element methods.

Preservation of Thrombolytic Activity of Urokinase Modified with Monomethoxypoly(ethylene glycol

A method is described to modify urokinase by covalent binding of monomethoxypoly(ethylene glycol) (mPEG) without impairing its catalytic ac tivity towards high molecular weight substrates. The urokinase active site is protected by an inhibitor, benzamidine, bound to Sepharose during the mPEG modification in order to avoid binding mPEG chains to the active site or to the surrounding area. The mPEG modified urokinase had increased activity towards small molecular weight substrates (acetyl-Gly-methyl ester) as com pared to the unmodified enzyme, while the activity towards the high molecular weight plasminogen and the insoluble substrate fibrin clot was preserved. This did not occur when the enzyme was modified in the absence of active site pro tection. The polymer modification increased the enzyme's thermostability and the stability in plasma in vitro and prolonged in vivo retention after in travenous injection in rats.

A New ELISA Using the ANANAS Technology Showing High Sensitivity to diagnose the Bovine Rhinotracheitis from Individual Sera to Pooled Milk

Diagnostic tests for veterinary surveillance programs should be efficient, easy to use and, possibly, economical. In this context, classic Enzyme linked ImmunoSorbent Assay (ELISA) remains the most common analytical platform employed for serological analyses. The analysis of pooled samples instead of individual ones is a common procedure that permits to certify, with one single test, entire herds as “disease-free”. However, diagnostic tests for pooled samples need to be particularly sensitive, especially when the levels of disease markers are low, as in the case of anti-BoHV1 antibodies in milk as markers of Infectious Bovine Rhinotracheitis (IBR) disease. The avidin-nucleic-acid-nanoassembly (ANANAS) is a novel kind of signal amplification platform for immunodiagnostics based on colloidal poly-avidin nanoparticles that, using model analytes, was shown to strongly increase ELISA test performance as compared to monomeric avidin. Here, for the first time, we applied the ANANAS reagent integration in a real diagnostic context. The monoclonal 1G10 anti-bovine IgG1 antibody was biotinylated and integrated with the ANANAS reagents for indirect IBR diagnosis from pooled milk mimicking tank samples from herds with IBR prevalence between 1 to 8%. The sensitivity and specificity of the ANANAS integrated method was compared to that of a classic test based on the same 1G10 antibody directly linked to horseradish peroxidase, and a commercial IDEXX kit recently introduced in the market. ANANAS integration increased by 5-fold the sensitivity of the 1G10 mAb-based conventional ELISA without loosing specificity. When compared to the commercial kit, the 1G10-ANANAS integrated method was capable to detect the presence of anti-BHV1 antibodies from bulk milk of gE antibody positive animals with 2-fold higher sensitivity and similar specificity. The results demonstrate the potentials of this new amplification technology, which permits improving current classic ELISA sensitivity limits without the need for new hardware investments.

Mesoporous silica sub-micron spheres as drug dissolution enhancers: Influence of drug and matrix chemistry on functionality and stability

Mesoporous silica particles prepared through a simplified Stöber method and low temperature solvent promoted surfactant removal are evaluated as dissolution enhancers for poorly soluble compounds, using a powerful anticancer agent belonging to pyrroloquinolinones as a model for anticancer oral therapy, and anti-inflammatory ibuprofen as a reference compound. Mesoporous powders composed of either pure silica or silica modified with aminopropyl residues are produced. The influence of material composition and drug chemical properties on drug loading capability and dissolution enhancement are studied. The two types of particles display similar size, surface area, porosity, erodibility, drug loading capability and stability. An up to 50% w/w drug loading is reached, showing correlation between drug concentration in adsorption medium and content in the final powder. Upon immersion in simulating body fluids, immediate drug dissolution occurred, allowing acceptor solutions to reach concentrations equal to or greater than drug saturation limits. The matrix composition influenced drug solution maximal concentration, complementing the dissolution enhancement generated by a mesoporous structure. This effect was found to depend on both matrix and drug chemical properties allowing us to hypothesise general prediction behaviour rules.

The p.R1819_C1948delinsS mutation makes von Willebrand factor ADAMTS13-resistant and reduces its collagen-binding capacity

This report concerns abnormal ADAMTS13 (a disintegrin and metalloprotease with a thrombospondin type 1 motif, member 13) and collagen interactions coinciding with the p.R1819_C1948delinsS von Willebrand factor (VWF) mutation associated with the deletion of the C-terminus of the A3 domain (amino acids 1819-1947) in a patient with a history of bleeding. The von Willebrand disease (VWD) phenotype of the patient featured low plasma and platelet VWF, multimers with smears extending over the highest normal oligomers in plasma, but not platelets, and an impaired collagen-binding capacity. In vitro full-length p.R1819_C1948delinsS VWF expression showed impaired VWF release, increased cellular content with normally-multimerized VWF and impaired collagen binding. The recombinant p.R1819_C1948delinsS VWF fragment, extending from domains A2 to B3 (p.R1819_C1948delinsS A2-B3 VWF), was completely resistant to proteolysis by ADAMTS13 in the presence of 1·5 mol/l urea, unlike its normal counterpart. The defect stems from impaired ADAMTS13 binding to p.R1819_C1948delinsS A2-B3, analysed under static conditions. Partial deletion of the C-terminus of the A3 domain thus makes VWF resistant to ADAMTS13, interfering with ADAMTS13 binding to VWF, and impairing the collagen-binding capacity of VWF. The p.R1819_C1948delinsS mutation has both haemorrhagic features (defective collagen binding, reduced VWF levels) and prothrombotic (ADAMTS13 resistance) features, and the latter probably mitigate the patient's bleeding symptoms.

Detection of a fluorescent-labeled avidin-nucleic acid nanoassembly by confocal laser endomicroscopy in the microvasculature of chronically inflamed intestinal mucosa

Inflammatory bowel diseases are chronic gastrointestinal pathologies causing great discomfort in both children and adults. The pathogenesis of inflammatory bowel diseases is not yet fully understood and their diagnosis and treatment are often challenging. Nanoparticle-based strategies have been tested in local drug delivery to the inflamed colon. Here, we have investigated the use of the novel avidin-nucleic acid nanoassembly (ANANAS) platform as a potential diagnostic carrier in an experimental model of inflammatory bowel diseases. Fluorescent- labeled ANANAS nanoparticles were administered to mice with chemically induced chronic inflammation of the large intestine. Localization of mucosal nanoparticles was assessed in vivo by dual-band confocal laser endomicroscopy. This technique enables characterization of the mucosal microvasculature and crypt architecture at subcellular resolution. Intravascular nanoparticle distribution was observed in the inflamed mucosa but not in healthy controls, demonstrating the utility of the combination of ANANAS and confocal laser endomicroscopy for highlighting intestinal inflammatory conditions. The specific localization of ANANAS in inflamed tissues supports the potential of this platform as a targeted carrier for bioactive moieties in the treatment of inflammatory bowel disease.

In vivo fate of avidin-nucleic acid nanoassemblies as multifunctional diagnostic tools

This study describes the formulation optimization and body-cell distribution and clearance in mice of a dually fluorescent biodegradable poly avidin nanoassembly based on the novel Avidin-Nucleic-Acid-Nano-ASsembly (ANANAS) platform as a potential advancement of classic avidin/biotin-based targeted delivery. The nanoformulation circulates freely in the bloodstream; it is slowly captured by filter organs; it is efficiently cleared within 24-48 h, and it is poorly immunogenic. The system displays more favorable properties than its parent monomeric avidin and it is a promising tool for diagnostic purposes for future translational aims, for which free circulation in the bloodstream, safety, multifunctionality and high composition definition are all necessary requirements. In addition, the assembly shows a time-dependent cell penetration capability, suggesting it may also function as a NP-dependent drug delivery tool. The ease of preparation together with the possibility to fine-tune the surface composition makes it also an ideal candidate to understand if and how nanoparticle composition affects its localization.

Integrated architecture for the electrical detection of plasmonic resonances based on high electron mobility photo-transistors

We report the design of an integrated platform for on-chip electrical transduction of the surface plasmon resonance supported by a nanostructured metal grating. The latter is fabricated on the active area of a GaAs/AlGaAs photo-HEMT and simultaneously works as the electronic gate of the device. The gold plasmonic crystal has a V-groove profile and has been designed by numerical optical simulations. By showing that the numerical models accurately reproduce the phototransistors experimental response, we demonstrate that the proposed architecture is suitable for the development of a new class of compact and scalable SPR sensors.

C2362F mutation gives rise to an ADAMTS13-resistant von Willebrand factor

von Willebrand factor (VWF) multimers result from proteolysis by the metalloprotease ADAMTS13. Since C2362F-VWF features abnormally large multimers with their triplet oligomer structure replaced by a diffuse smear, we explored the susceptibility of C2362F-VWF to ADAMTS13. VWF-enriched blood samples, obtained by cryoethanol precipitation of plasma from a patient with von Willebrand disease (VWD) homozygous for the C2362F mutation and a normal subject, were submitted to cleavage by recombinant ADAMTS13 under static conditions in the presence of urea. C2362F-VWF proved completely ADAMTS13-resistant in vitro. At any concentration of recombinant ADAMTS13 (from 0.1 µM to 1 µM), there was no evidence of the abnormally large VWF multimers of C2362F-VWF disappearing, nor any increased representation of triplet multimer bands, unlike the situation seen in normal VWF. This is due partly to a defective ADAMTS13 binding to C2362F-VWF under static conditions, as seen in both the patient's and recombinant mutated VWF proteins. These findings were associated with a significantly shorter than normal survival of C2362F-VWF after DDAVP, demonstrating that proteolysis and VWF survival may be independent phenomena. Our findings clearly demonstrate that the loss of cysteine 2362 makes VWF resistant to proteolysis by ADAMTS13, at least partly due to an impaired ADAMTS13 binding to VWF. This suggests that the B2 domain of VWF is involved in modulating ADAMTS13 binding to VWF and the consequent proteolytic process. The C2362F-VWF mutation also enables a new abnormality to be identified in the VWF-ADAMTS13 relationship, i.e. an ADAMTS13-resistant VWF.

Synthesis and chromatography-free purification of PNA-PEO conjugates for the functionalisation of gold sensors

Peptide Nucleic Acids (PNAs) linked to high molecular weight (MW) poly(ethylene oxide) (PEO) derivatives could be useful conjugates for the direct functionalisation of gold surfaces dedicated to Surface Plasmon Resonance (SPR)-based DNA sensing. However their use is hampered by the difficulty to obtain them through a convenient and economical route. In this work we compared three synthetic strategies to obtain PNA-high MW PEO conjugates composed of (a) a 15-mer PNA sequence as the probe complementary to genomic DNA of Mycobacterium tuberculosis, (b) a PEO moiety (2 or 5 KDa MW) and (c) a terminal trityl-protected thiol necessary (after acidic deprotection) for grafting to gold surfaces. The 15-mer PNA was obtained by solid-phase synthesis. Its amino terminal group was later condensed to bi-functional PEO derivatives (2 and 5 KDa MW) carrying a Trt-cysteine at one end and a carboxyl group at the other end. The reaction was carried out either in solution, using HATU or PyOxim as coupling agents, or through the solid-phase approach, with 49.6%, 100% and 5.2% yield, respectively. A differential solvent extraction strategy for product purification without the need for chromatography is described. The ability of the 5 KDa PEO conjugate to function as a probe for complementary DNA detection was demonstrated using a Grating-Coupling Surface Plasmon Resonance (GC-SPR) system. The optimized PEO conjugation and purification protocols are economical and simple enough to be reproduced also within laboratories that are not highly equipped for chemical synthesis.

Characterization of multifunctional nanosystems based on the avidin-nucleic acid interaction as signal enhancers in immuno-detection

The Avidin-Nucleic-Acids-Nano-Assembly (ANANAS) is a kind of soft poly avidin nanoparticle originating from the high affinity interaction between avidin and the nucleic acids. In this work we investigated the possibility of transforming ANANAS cores into stoichiometrically controlled multifunctional nanoparticles through a "one-pot" procedure, and we measured in a quantitative way their ability to work as reagents for enhanced immunodiagnostic detection. Initially, we measured the ANANAS loading capability for biotinylated proteins of different nature. About 200 molecules of biotin-horseradish-peroxidase (40KDa b-HRP) and 60 molecules of biotin-immunoglobulin-G (150KDa b-IgG) could be accommodated onto each nanoparticle, showing that steric limitations dictate the number of loadable entities. Stoichiometrically controlled functional assemblies were generated by mixing core particles with subsaturating amounts of b-HRP and b-IgG. When applied as detection reagents in an Enzyme-Linked-ImmunoSorbed-Assay (ELISA), these assemblies were up to two-orders of magnitude more sensitive than commercial HRP-based reagents. Assemblies of different composition displayed different efficacy, indicating that the system functionality can be fine-tuned. Within-assay variability (CV%), measured to assess if the assembly procedure is reproducible, was within 10%. Stability experiments demonstrated that the functionalyzed assemblies are stable in solution for more than one week. In principle, any biotinylated function can be loaded onto the core particle, whose high loading capacity and tunability may open the way toward further application in biomedicine.

Optimized avidin nucleic acid nanoassemblies by a tailored PEGylation strategy and their application as molecular amplifiers in detection

Avidin was recently found to display the ability to interact with high affinity with nucleic acids. In this work, we investigated how this property is affected by the protein modification with poly(ethylene glycol) (PEG). More precisely, we studied the influence of the size and geometry of the polymer and of the mode of anchorage to the protein surface. To this end, we synthesized five PEG derivatives capable of PEGylating avidin either through covalent attachment to its lysine primary amines or by exploiting its biotin binding pockets. Several differently PEGylated avidin derivatives were then obtained, which were later tested for their affinity for plasmid DNA by means of the electrophoretic mobility assay. The results show that covalent PEGylation reduces the affinity for DNA in a dose-dependent manner, whereas PEG anchoring through the biotin binding sites does not, even when bulky and high MW biotin-PEG derivatives are used. We then investigated how the size and molecular weight of the biotin-PEG affects the solubility and stability of avidin-nucleic acid nanoassemblies in physiological buffer. Among the biotin-PEG derivatives synthesized in this work, the branched forms were more efficient in protecting particle surface and preventing their aggregation. Full nanoparticle solubility was achieved by saturating 30% of the biotin binding sites with a 2 x 5 kDa branched derivative. the optimized avidin nucleic acid nanoassemblies (ANANAS) were employed in a model analytical test where they showed at least 40-fold higher efficiency than monomeric avidin in recognizing biotinylated surface immobilized IgGs. The results pave the way toward the application of this novel nanosystem in biomedicine.

The effect of Na(2)CO(3), NaF and NH(4)OH on the stability and release behavior of sol-gel derived silica xerogels embedded with bioactive compounds

Stability, defined as the reproducible behavior of a device upon its storage, is an important issue in pharmaceutical formulation. Silica xerogels obtained through the sol-gel route are relatively new as matrices for the controlled release of drugs. In some cases, it was observed that their behavior changes upon storage, so that they cannot always be defined as "stable". This occurs especially when gel processing is performed at mild temperatures, a procedure that may have to be used to prevent degradation of the embedded drug. This work investigated the use of inorganic catalysts as potential xerogel stability inducers when gel curing by heating is not applicable. Three compounds known to accelerate sol-gel polymerization, namely ammonia, sodium fluoride and sodium carbonate, were introduced during the polymerization of low-temperature processed inorganic and organically modified gels, and the effect of each compound on xerogel stability and drug release was monitored. The use of carbonate leads to formulations with good retention properties, as opposed to ammonia and NaF, which lead to poorly retentive xerogels in accordance with their known ability to increase porosity. Ammonia was shown to be a poor stability promoter independently of gel composition, as opposed to fluoride and carbonate, which both displayed stabilizing properties in a dose-dependent manner. No correlation was found between xerogel stability and drug release properties. An attempt was also made to correlate stability data with polymerization rates and wet gel syneresis time evolution with the purpose of identifying one or more synthesis parameters that could act as stability predictors for pre-formulation studies. No correlation was found between stability and syneresis data. A similar trend in the curve of gel time vs. catalyst concentration was observed for the two stabilizing catalysts, which was different for the non-stabilizing ammonia. It was concluded that the trend of this curve could potentially provide an indicator of catalyst stabilizing efficacy.

In vitro and in vivo evaluation of acellular diaphragmatic matrices seeded with muscle precursors cells and coated with VEGF silica gels to repair muscle defect of the diaphragm

In this work, a bioartificial system consisting of VEGF-loaded porous silica gel and myoblasts cultured on acellular diaphragmatic matrix (ADM) has been implanted to repair a surgically created diaphragmatic defect in Lewis rats. ADMs exerted a strong angiogenic response on chorio-allantoic membrane. Cytotoxicity, VEGF release and matrix erodibility in vitro tests demonstrated that the silica support was nontoxic and that the VEGF bioactivity was maintained after matrix entrapment and it was released within a timeframe that can be modulated by synthesis parameters. Different grafts composed by ADMs with and without autologous male myoblasts or/and VEGF-loaded porous silica gel have been implanted to repair previously created diaphragmatic defects in female Lewis rats. Patches composed of ADMs and myoblasts appeared well preserved until 8 weeks, and contained multinucleated cells and cholinergic fibers. At 8 weeks, the implanted cells were still present inside the patches. The disappointing results obtained when VEGF was delivered by porous silica gel were probably due to an abnormal angiogenic response following an excess of local growth factor concentration. Taken together, these results confirmed that our matrices contained biologically active angiogenic factors which were per se sufficient to induce neo-vessels formation, thus allowing the survival of implanted myoblasts.

Effects of surfactant characteristics on drug availability from suppositories

The addition of surfactants to suppository formulations is referred to in the scientific literature, but their effects on drug availability remain uncertain. Surfactants are reported to improve drug dispersion into hard fatty excipients, to increase the spreading of the melted suppository on the rectal mucosa leading to a greater contact surface, to reduce the viscosity of the molten mass and to reduce the pathway of drug particles to the interface. In the present study a systematic investigation based on tensiometric and rheological methods was carried out to evaluate the effects of nonionic surfactants with different HLBs (hydrophilic-lipophilic-balance) on drug availability and to clarify the possible mechanisms involved in the release process. The relationship between the melted suppositories and a membrane simulating the rectal barrier were investigated in the course of the in vitro release test by measuring their energy characteristics. At the same time, the potential influences of such interactions on drug release were investigated in suppositories formulated with different kinds and concentrations of surfactant additives. Drug availability was influenced not only by the interaction between the suppository and the rectal membrane but also by the interaction between surfactant, lipophilic excipient and suspended drug particles. Such interactions appear to greatly influence drug release from suppositories, which, in turn, is the main parameter determining drug availability.

A single-step photolithographic interface for cell-free gene expression and active biochips

We have developed a biochip platform technology suitable for controlled cell-free gene expression at the micrometer scale. A new hybrid molecule, "Daisy", was designed and synthesized to form in a single step a biocompatible lithographic interface on silicon dioxide. A protocol is described for the immobilization of linear DNA molecules thousands of base pairs long on Daisy-coated surfaces with submicrometer spatial resolution and up to high densities. On-chip protein synthesis can be obtained with a dynamic range of up to four orders of magnitude and minimal nonspecific activity. En route to on-chip artificial gene circuits, a simple two-stage gene cascade was built, in which the protein synthesized at the first location diffuses to regulate the synthesis of another protein at a second location. We demonstrate the capture of proteins from crude extract onto micrometer-scale designated traps, an important step for the formation of miniaturized self-assembled protein chips. Our biochip platform can be combined with elastomeric microfluidic devices, thereby opening possibilities for isolated and confined reaction chambers and artificial cells in which the transport of products and reagents is done by diffusion and flow. The Daisy molecule and described approach enables groups not proficient in surface chemistry to construct active biochips based on cell-free gene expression.

Bisphosphonate complexation and calcium doping in silica xerogels as a combined strategy for local and controlled release of active platinum antitumor compounds

The production of bone substitute biomimetic materials which could also act as antitumoral drug release agents is of enormous interest. We report in this paper the synthesis and characterization of a novel platinum dinuclear complex containing a geminal bisphosphonate and its embodiment into xerogels prepared by the sol-gel method. Our goal was to obtain a hybrid inorganic matrix that could release a platinum species active against bone tumors or metastases, upon local implant. Two silica xerogels were considered: one was composed of pure silica, while the other contained also some calcium as potential release-modulating agent thanks to its high affinity for bisphophonates. The platinum-complex loading capacity of the inorganic matrices, the release kinetics in buffer simulating physiological conditions, and the stability upon storage were investigated as a function of Pt-complex concentration and calcium addition. We found that the presence of calcium in the composites deeply influences not only the stability of the formulations but also the nature of the platinum complex liberated in solution.

fac-{Ru(CO)3}2+-Core Complexes and Design of Metal-Based Drugs. Synthesis, Structure, and Reactivity of Ru−Thiazole Derivative with Serum Proteins and Absorption−Release Studies with Acryloyl and Silica Hydrogels as Carriers in Physiological Media

The reaction of [Ru2(CO)6Cl4], 1, with excess THZ (1,3-thiazole) in absolute ethanol at 55 degrees C produces fac-[Ru(CO)3Cl2(THZ)], 2, in high yield. [Ru(CO)2Cl2(THZ)2], 3, is formed at higher temperature (ca 70 degrees C) and higher concentration of THZ. The X-ray structures of the new compounds have been determined, and density functional studies performed at the hybrid B3LYP/(Lanl2DZ, Ru; 6-311+G**, CHClNOS) level allowed the estimation of the structures of several conformers as well as that of their relative total electronic energies. Compound 2 is soluble (slowly) in aqueous media, where it reacts with the transport proteins bovine serum albumin (BSA) and human apotransferrin (HTF), and at a lower extent with calf thymus DNA (CT-DNA) and with guanosine-5'-monophosphate (GMP). The complex molecule is adsorbed by certain synthetic acryloyl polymers that have terminal carboxylate functions and is embedded in silica gels when these latter are prepared in the presence of a solution of 2. Ruthenium species are slowly released from the loaded gels into physiological solutions at pH 7.4. The reactivity of 2 with biomolecules and synthetic hydrogels makes it a compound of interest for anticancer and antimetastases tests.

Evaluation of Silicon Dioxide–Based Coating Enriched with Bioactive Peptides Mapped on Human Vitronectin and Fibronectin:In VitroandIn VivoAssays

A wide range of biochemical signals promoting cell functions (adhesion, migration, proliferation, and differentiation) and thereby improving the osseointegration process are currently investigated. Unfortunately, their application for the production of bioactive implantable devices is often hampered by their insolubility; instability; and limited availability of a large amount of inexpensive, high-purity samples. An attractive alternative is the use of short peptides carrying the minimum active sequence of the natural factors. Synthetic peptides mapped on fibronectin and vitronectin have been demonstrated to enhance cell adhesion both to polystyrene and acellular bone matrix; in particular, a nonapeptide sequence from human vitronectin works via an osteoblast-specific adhesion mechanism. In this study, we incorporated these peptides into a sol-gel silica dressing applied to coat sand-blasted and acid-attacked titanium samples; measured the kinetic of peptide release; and used titanium disks, coated with a peptide-enriched film, as substrates to determine the peptide concentration that maximizes cell adhesion in vitro. We also evaluated in vivo the capacity of the vitronectin-derived peptide to improve osteogenic activity: histologic analysis revealed markedly improved osteogenic activity around peptide-enriched samples. This article also discusses the role of surface characteristics and the importance of bioactive peptides.

Wet sol–gel derived silica for controlled release of proteins

The potential of wet sol-gel derived silica gels as new matrices for the entrapment and sustained release of proteins was investigated. Model proteins, BSA, ribonuclease-A and avidin, with differing molecular weights and/or isoelectric points, were entrapped in two silica polymer formulations having different silica contents (4% and 12% wt/v). The conformational stability of the proteins after entrapment and their release after immersion into physiological conditions were measured. Circular dichroism analysis showed that protein conformation is maintained after entrapment and stability is enhanced. Protein-free formulations were injected intramuscularly into BALB/c mice to monitor the in vivo fate of the matrix, and the results showed that the gel is totally reabsorbed, without any apparent surrounding inflammation process. The time required for matrix bioerosion varied between one to three weeks, depending on its SiO(2) content. Erosion was also measured in vitro and the contribution of erosion and diffusion to the release of the embedded proteins was quantified. These data indicate that wet silica polymers obtained by the sol-gel route are promising matrices for the sustained release of protein drugs.

In vitro methods for the evaluation of drug availability from suppositories: comparison between biological and artificial membranes

Drug availability from suppositories is currently evaluated in vitro by means of a model consisting of a dialysis tube (porous membrane) or isolated biological membrane (animal rectum). We propose a new alternative in vitro method to determine drug availability from suppositories consisting of an artificial membrane soaked with n-octanol, coupled with a filter paper sheet soaked with phosphate buffer. This method provides for an integrated hydro-lipophilic simulation of the biological membrane, including the mucus layer adhering to the rectal mucosa. By simply using the porous membrane, the amount of drug released varied directly according to its solubility for formulations with lipophilic excipients. For formulations with hydrophilic excipients, drugs with low/intermediate solubility in water showed increased availability in comparison to lipophilic excipients. The in vitro rat rectum model provided overall results that were similar to those obtained with the porous membrane method, although the percentage values of AUC were lower. The new model of in vitro simulated absorption produced a degree of drug availability that was lower in comparison to both previous methods. However, the simulated model appeared to give a pattern of drug availability closer to that of the model of in vitro rat rectum. The new in vitro artificial model thus appears to be useful in suppositories preformulation studies, allowing for an estimate of drug availability and the choice of the most adequate excipient.

Influence of synthesis and processing conditions on the release behavior and stability of sol–gel derived silica xerogels embedded with bioactive compounds

The influence of processing parameters and synthetic strategies in the properties of sol-gel derived silica matrices intended for the release of bioactive compounds was investigated. The time-evolution of the matrix properties during its aging at room temperature in the dry and wet forms was investigated by measuring some of its physical and drug retaining properties. The results indicate that long term gel aging in the wet form is fundamental for the obtainment of dry matrices that are stable upon storage, a fundamental requirement for any practical application. In the case of hybrid matrices obtained by replacing part of the tetraethoxysilane precursor with mono-methyl trimethoxysilane, the order of addition of the reaction component is also important in determining the properties of the final dry gel, probably by influencing the polymer structural properties. This parameter acts synergistically with the matrix composition in determining the release properties of xerogels embedded with bioactive compounds.

DNA condensation by high-affinity interaction with avidin

Avidin, the basic biotin-binding glycoprotein from chicken egg white, is known to interact with DNA, whereas streptavidin, its neutral non-glycosylated bacterial analog, does not. In the present study we investigated the DNA-binding properties of avidin. Its affinity for DNA in the presence and absence of biotin was compared with that of other positively charged molecules, namely the protein lysozyme, the cationic polymers polylysine and polyarginine and an avidin derivative with higher isoelectric point (pI approximately 11) in which most of the lysine residues were converted to homoarginines. Gel-shift assays, transmission electron microscopy and dynamic light scattering experiments demonstrated an unexpectedly strong interaction between avidin and DNA. The most pronounced gel-shift retardation occurred with the avidin-biotin complex, followed by avidin alone and then guanidylated avidin. Furthermore, ultrastructural and light-scattering studies showed that avidin assembles on the DNA molecule in an organized manner. The assembly leads to the formation of nanoparticles that are about 50-100 nm in size (DNA approximately 5 kb) and have a rod-like or toroidal shape. In these particles the DNA is highly condensed and one avidin is bound to each 18 +/- 4 DNA base pairs. The complexes are very stable even at high dilution ([DNA] =10 pM) and are not disrupted in the presence of buffers or salt (up to 200 mM NaCl). The other positively charged molecules also condense DNA and form particles with a globular shape. However, in this case, these particles disassemble by dilution or in the presence of low salt concentration. The results indicate that the interaction of avidin with DNA may also occur under physiological conditions, further enhanced by the presence of biotin. This DNA-binding property of avidin may thus shed light on a potentially new physiological role for the protein in its natural environment.

Silica xerogels as a delivery system for the controlled release of different molecular weight heparins

In this work, we investigated a sol-gel derived silica matrix as a delivery system for the prolonged release of different molecular weight heparins, which allows the glycosaminoglicons to retain their whole biological activity. Several xerogels were obtained by embedding different molecular weight heparins into matrices prepared by using different amount of NH4OH as a catalyst during gel formation. Gel synthesis parameters, drug release properties, and xerogels surface area were evaluated. Unfractionated, low and oligo-molecular weight heparins were embedded into xerogels and the effect of the molecular weight on the release kinetics and the retained biological activity has been investigated. The results show that the surface area of the matrix is a determinant parameter affecting drug release kinetics. This structural feature can be modified by varying the catalyst tetraethoxysilane molar ratio used during the matrix synthesis. In most cases release kinetics fitted the Higuchi diffusive model and a lower diffusion rate was observed from silica matrices characterized by a smaller surface area. In the case of matrices with lower surface area, loaded with unfractionated heparin, zero order kinetics was observed. In this paper, we have defined a heparin release silica xerogel system and we have pointed out how modulation of its synthesis parameters allows adjusting the release of heparin according to therapeutic needs.

Conjugates of peptides and proteins to polyethylene glycols

This chapter provides a critical overview of the technology presently available in the field of protein PEGylation. The chemistry of the polymer and of its reactive derivatives is discussed and presented together with several protocols used to obtain PEG-protein conjugates. The coupling protocols are critically discussed on the basis of the properties of the protein to be modified and those desired for the final product. Methods for product purification and characterization are also provided. The overall information provided will guide the reader toward all of the critical steps involved in the preparation of PEG-protein adducts.

Selective alkylation and acylation of alpha and epsilon amino groups with PEG in a somatostatin analogue: tailored chemistry for optimized bioconjugates

The effects of the type and location of polymer grafting on the biological activity of different mono-PEG derivatives of the somatostatin analogue RC160 were evaluated. A chemical strategy to obtain mono-PEG alkylation or acylation of the peptide's alpha-terminal or lysil-epsilon primary amines was devised. Selective BOC protection of the two available primary amines, followed by reaction with two different PEG reagents and removal of the protecting group, was carried out. Chemical characterization, structural studies, and the evaluation of the biological activity of the bioconjugates synthesized allowed the identification of the one having characteristics more suitable for therapeutic application. This corresponds to the mono-epsilon-lysil-pegylated form, obtained by reductive alkylation, where the amine's positive charge is preserved. The results obtained suggest the importance of preliminary studies in the development of new polymer-peptide conjugates with improved pharmacological properties.

An approach to increased polyplex gene delivery by peptides selected from a phage display library

Phage display libraries were screened for peptides to be incorporated in nonviral gene delivery vehicles. Cells in culture were incubated with heptamer random peptide libraries displayed on M13 bacteriophages in three to five copies per phage. Surface-adherent phages were removed or inactivated and the cells were fractionated in a nuclear pellet and supernatant. Bacteriophages from each of the two fractions were amplified and reincubated with the cells. Three successive rounds of selection were performed. Eighteen sequenced clones revealed 14 different sequences. Two sequences were homologous to segments of the HIV gp120 protein. For three sequences, the corresponding synthetic peptides were generated and attached via avidin-biotin to polylysine-condensed plasmid DNA containing a reporter gene. The addition of the peptides led to 8-14 times increase in the expression of the reporter.

Influence of processing conditions in the manufacture of O/W creams: I. Effect on dispersion grade and rheological characteristics

Two series of O/W creams having the same general formulation were prepared in three different mechanical conditions (F with an hand blender; S with a turbomixer; T with a vacuum turbo emulsor) using two types of surfactants, polyoxyethylene-cetostearyl alcohols and polyglyceryl-3-methylglucose-distearate. By means of microscopic image analysis it was possible to point out the dispersion grade of the oil internal phase increasing with the energy applied under the conditions of manufacture (F < S < T). The level of dispersion influenced significantly on the rheological characteristics of the creams. With polyoxyethylene-cetostearyl alcohols, the viscosity of creams increased as the energy applied in manufacturing increased, with polyglyceryl-3-methylglucose-distearate on the contrary decreased. Moreover, indifferently to the manufacturing conditions, even in the same concentration of surfactant, the creams obtained with the last produced a much greater viscosity. At a parity of manufacturing conditions the differences between the batches of productions were not significant.

Influence of processing conditions in the manufacture of O/W creams: II. Effect on drug availability

O/W creams prepared in three mechanical conditions (F with a hand blender; S turbomixer; T vacuum turbo-emulsor) produced different dispersion grades of the internal phase and different rheological characteristics by using surfactants of different chemical nature (polyoxyethylene-cetostearyl alcohols and polyglyceryl-3-methylglucose distearate). Three tests were used (an in vitro release test across a porous membrane; an in vitro simulated absorption test across a porous membrane impregnated with isopropyl myristate; an in vivo absorption test based on the intensity and duration of the erythema produced by methyl nicotinate after application of the cream on the skin) to assess whether the different physical characteristics influence drug availability from the creams. The different physical characteristics due to the mechanical conditions of emulsifying and gelification appeared not to influence drug release and in vivo absorption.

[Pulmonary embolism: the past and . . . the future]

The history of pulmonary embolism cannot be reconstructed reliably beyond the last two centuries, starting with the Napoleon's times by the works of Laennec. We owe the first pathological and clinical descriptions to European scientists, especially French, German and Italian. Interestingly, some ideas regarding pathophysiology and even hemodynamics can be found in papers published as early as the end of the 19th century. Of note, the strong relationship between venous thrombosis and pulmonary embolism, suspected already in the middle of the 19th century, resulted later in a new clinical entity named venous thromboembolic disease. Only just before the second world war "modern" diagnostic tests entered into the clinical arena. Beginning with electrocardiography and X-ray techniques including pulmonary angiography, the progress in the field of imaging continued with lung scan, echocardiography, computed tomography, and finally still largely unexplored ultra-fast magnetic resonance imaging techniques: despite this technological development the correct diagnosis of pulmonary embolism in daily practice remains an important challenge. This is due to the lack of a single test which would combine high diagnostic power, round-the-clock availability and reasonably low cost. Though thrombotic origin of pulmonary embolism was well documented for almost two centuries, anticoagulation as a treatment for venous thromboembolism dates back much less than a century and thrombolysis was initiated only 30 years ago. What is even worse, those 30 years were not enough for us to identify clear-cut criteria in the selection between thrombolysis and anticoagulation in individual patients. Not to speak about the problem regarding optimal duration of secondary prophylaxis after a thromboembolic episode. Still how long shall we be debating about the same problems at the bed of our patients with venous thromboembolism? Or maybe the near future will bring completely new answers to our old questions? What type of case report related to pulmonary embolism will have the chance to be accepted for publication in the Italian Heart Journal in the year ... 2050? Future will show? But only if we help it....

A labeling, detection, and purification system based on 4-hydroxyazobenzene-2-carboxylic acid: an extension of the avidin-biotin system

We introduce a new nonradioactive, chromogenic label based on 4-hydroxyazobenzene-2-carboxylic acid (HABA), which is suitable for bioanalytical application, e.g., detection, localization, isolation, and purification. The HABA label is superior to other systems where it is difficult to separate labeled from unlabeled molecules or to determine the amount of label. HABA is readily detected spectroscopically by its absorption at 350 nm or by its interaction with avidin that results in a red shift to 500 nm. The HABA reagents described can be conjugated to a variety of functional groups on biomolecules and purified thereafter by affinity chromatography on an avidin column. The interaction of the HABAylated biomolecules with their corresponding targets is detected with high-affinity anti-HABA antibodies or with avidin. The nonradioactive, chromogenic HABA-based reagents form a homogeneous system that can complement or replace systems where facile quantification of the label is desired.

[The cardiologist facing pulmonary embolism. The experience of 160 cases of acute cor pulmonale]

BACKGROUND

The results of recent multicenter studies dealing with pulmonary embolism often reveal remarkable discrepancies in terms of diagnosis, prognosis and treatment, partly due to the heterogeneity of study patients and of evaluation criteria. Our prospective study focused exclusively on patients affected by pulmonary embolism with a hemodynamic pattern of acute cor pulmonale, investigated at a single center. Particular attention was paid to in-hospital mortality, embolic recurrences, major bleeding and underlying pathologies.

METHODS

This study includes 160 cases (103 women with a median age of 71 years and 57 men with a median age of 65 years) in whom the clinical and echocardiographic findings suggestive of acute pulmonary embolism were confirmed by lung perfusion scan, pulmonary angiography, techniques for the detection of deep vein thrombosis and/or autopsy.

RESULTS

The most common clinical manifestations were: dyspnea (92% of cases), tachycardia (80%), syncope (44%), cardiac arrest (22%), and shock (20%). Thoracic pain was present in only 27% of patients. None of the patients showed a normal ECG; a right bundle branch block was found in 47% of cases. T-wave inversion in the precordial leads (32%) was not related to the severity and outcome of pulmonary embolism. Present or previous deep vein thrombosis was found in 53 and 26% of cases, respectively. Only in 2 patients pulmonary embolism was secondary to a deep vein thrombosis of the upper limbs. Intravenous heparin alone was used in 36% of cases, whereas 56% were treated with thrombolytic agents + heparin. Major bleeding occurred in 9% of patients treated with heparin alone, and in 16% of those who received heparin + thrombolytic drugs. Death occurred in 17% of the former, and in 27% of the latter patients. The in-hospital mortality rate was related not only to the presence of cardiac arrest and--to a lower degree--of shock, but also to the recurrence of pulmonary embolism and to the underlying heart disease. No relationship was found between mortality and age, intracardiac thrombi or malignancy. Prognosis was quite different depending on clinical presentation, with a death rate ranging from 11% in the absence of systemic hypertension, and 77% in the presence of cardiac arrest.

CONCLUSIONS

Even the "massive" pulmonary embolism that is observed in a cardiac department represents a true "spectrum" of pathological conditions, a spectrum that should be taken into account not only in order to evaluate prognosis and treatment in a particular case, but also when meta-analyses are performed.

Bioconjugation in pharmaceutical chemistry

Polymer conjugation is of increasing interest in pharmaceutical chemistry for delivering drugs of simple structure or complex compounds such peptides, enzymes and oligonucleotides. For long time drugs, mainly with antitumoral activity, have been coupled to natural or synthetic polymers with the purpose of increasing their blood permanence time, taking advantage of the increased mass that reduces kidney ultrafiltration. However only recently complex constructs were devised that exploit the 'enhanced permeability and retention' (EPR) effect for an efficient tumor targeting, the high molecular weight for adsorption or receptor mediated endocytosis and finally a lysosomotropic targeting, taking advantage of acid labile bonds or cathepsin susceptible polypeptide spacers between polymer and drug. New original, very active conjugates of this type, as those based on poly(hydroxyacrylate) polymers, are already in advanced state of development. Labile oligonucleotides, including antisense drugs, were also successfully coupled to polymers in view of an increased cell penetration and stabilization towards nucleases. However, the most active research activity resides in the field of polypeptides and proteins delivery, mainly for the two following reasons: first of all because a great number of therapeutically interesting compounds are now being produced by genetic engineering in large quantity and, secondly, because these products are difficult to administer to patients for several inherent drawbacks. Proteins are in fact easily digested by many endo- and exo-peptidases present in blood or in other body districts; most of them are immunogenic to some extent and, finally, they are rapidly excreted by kidney ultrafiltration. Covalent polymer conjugation at protein surface was demonstrated to reduce or eliminate these problems, since the bound polymer behaves like a shield hindering the approach of proteolytic enzymes, antibodies, or antigen processing cell. Furthermore, the increase of the molecular weight of the conjugate allows to overcome the kidney elimination threshold. Many successful results were already obtained in peptides and proteins, conjugated mainly to water soluble or amphiphilic polymers like poly(ethylene glycol) (PEG), dextrans, or styrenemaleic acid anhydride. Among the most successful are the conjugates of asparaginase, interleukin-2 or -6 and neocarcinostatin, to remind some antitumor agents, adenosine deaminase employed in a genetic desease treatment, superoxide dismutase as scavenger of toxic radicals, hemoglobin as oxygen carrier and urokinase and streptokinase as proteins with antithrombotic activity. In pharmaceutical chemistry the conjugation with polymers is also of great importance for synthetic applications since many enzymes without loss of catalytic activity become soluble in organic solvents where many drug precursors are. The various and often difficult chemical problems encountered in conjugation of so many different products prompted the development of many synthetic procedures, all characterized by high specificity and mild condition of reaction, now known as 'bioconjugation chemistry'. Bioconjugation developed also the design of new tailor-made polymers with the wanted molecular weight, shape, structure and with the functional groups needed for coupling at the wanted positions in the chain.

N-hydroxysuccinimide carbonates and carbamates are useful reactive reagents for coupling ligands to lysines on proteins

Ligands containing amino or hydroxyl groups were converted to their corresponding activated N-hydroxysuccinimidyl carbamate and carbonate by reaction with disuccinimidyl carbonate (DSC). The latter reagents can be used for the group-specific modification of primary amines as an alternative to the widespread usage of N-hydroxysuccinimide esters. Biotin and 2,4-dinitrophenyl (DNP) derivatives were used as examples to demonstrate the approach. Biotin and DNP were each extended by attaching two different spacer arms, carrying either a hydroxyl group or a primary amine as terminal functions. The latter were then activated via their conversion to N-hydroxysuccinimide carbonates and carbamates, respectively. The usefulness of these reagents for protein modification was investigated. The modified proteins obtained exhibited similar stability and activity characteristics compared to those modified with active N-hydroxysuccinimdyl esters. The activation of hydroxy- or amino-terminating compounds with DSC represents a general method that can be applied to any ligand which contains these functional groups for its covalent coupling to amines.

[The traps of pulmonary embolism]

The clinical diagnosis of pulmonary embolism (PE), even massive, remains difficult and perplexing. In our hospital, the percentage of exact clinical diagnoses has not significantly changed over recent years, with a false-negative rate of 78%, and a false-positive rate of 2%. In approximately 20% of cases, autopsy showed several emboli and pulmonary infarctions of various ages, indicating recurrent embolic episodes. The diseases most frequently associated were cardiac diseases (51%) and tumours (24%). Pneumonia considerably decreases the probability of an exact diagnosis of PE; hospitalisation in the Cardiology department or Intensive Care Unit increased the probability of this diagnosis. While the numerous diagnostic algorithms recently proposed have a limited value, the process integrating clinical and instrumental data in order to establish a prospective clinical probability, should facilitate identification of acute PE in live patients.