Flexible synthesis of cationic peptide-porphyrin derivatives for light-triggered drug delivery and photodynamic therapy.

Efficient syntheses of cell-penetrating peptide-porphyrin conjugates are described using a variety of bioconjugation chemistries. This provides a flexible means to convert essentially hydrophobic tetrapyrolle photosensitisers into amphiphilic derivatives which are well-suited for use in light-triggered drug delivery by photochemical internalisation (PCI) and targeted photodynamic therapy (PDT).

Conjugatable water-soluble Pt(II) and Pd(II) porphyrin complexes: novel nano- and molecular probes for optical oxygen tension measurement in tissue engineering.

Measurement of oxygen tension in compressed collagen sheets was performed using matrix-embedded optical oxygen sensors based on platinum(II) and palladium(II) porphyrins supported on polyacrylamide nanoparticles. Bespoke, fully water-soluble, mono-functionalised Pt(II) and Pd(II) porphyrin complexes designed for conjugation under mild conditions were obtained using microwave-assisted metallation. The new sensors display a linear response (1/τ vs. O2) to varying oxygen tension over a biologically relevant range (7.0 × 10(-4) to 2.7 × 10(-1) mM) in aqueous solutions; a behaviour that is maintained following conjugation to polyacrylamide nanoparticles, and following embedding of the nanosensors in compressed collagen sheets, paving the way to innovative approaches for real-time resolution of oxygen gradients throughout 3D matrices useful for tissue regeneration.

Orthogonally bifunctionalised polyacrylamide nanoparticles: a support for the assembly of multifunctional nanodevices.

Polyacrylamide nanoparticles bearing two orthogonal reactive functionalities were prepared by reverse microemulsion polymerisation. Water-soluble photosensitisers and peptide or carbohydrate moieties were sequentially attached to the new nanospecies by orthogonal conjugations based on copper-catalysed azide-alkyne cycloaddition and isothiocyanate chemistry.

Protoporphyrin IX enhancement by 5-aminolaevulinic acid peptide derivatives and the effect of RNA silencing on intracellular metabolism.

Intracellular generation of the photosensitiser, protoporphyrin IX, from a series of dipeptide derivatives of the haem precursor, 5-aminolaevulinic acid (ALA), was investigated in transformed PAM212 murine keratinocytes, together with studies of their intracellular metabolism. Porphyrin production was substantially increased compared with equimolar ALA using N-acetyl terminated phenylalanyl, leucinyl and methionyl ALA methyl ester derivatives in the following order: Ac-L-phenylalanyl-ALA-Me, Ac-L-methionyl-ALA-Me and Ac-L-leucinyl-ALA-Me. The enhanced porphyrin production was in good correlation with improved photocytotoxicity, with no intrinsic dark toxicity apparent. However, phenylalanyl derivatives without the acetyl/acyl group at the N terminus induced significantly less porphyrin, and the replacement of the acetyl group by a benzyloxycarbonyl group resulted in no porphyrin production. Porphyrin production was reduced in the presence of class-specific protease inhibitors, namely serine protease inhibitors. Using siRNA knockdown of acylpeptide hydrolase (ACPH) protein expression, we showed the involvement of ACPH, a member of the prolyl oligopeptidase family of serine peptidases, in the hydrolytic cleavage of ALA from the peptide derivatives. In conclusion, ALA peptide derivatives are capable of delivering ALA efficiently to cells and enhancing porphyrin synthesis and photocytotoxicity; however, the N-terminus state, whether free or substituted, plays an important role in determining the biological efficacy of ALA peptide derivatives.

Photosensitizing properties of a boronated phthalocyanine: studies at the molecular and cellular level.

A synthetic procedure has been developed for the preparation of a Zn-phthalocyanine peripherally substituted with a dodecaborane. The absorption spectrum of the derivative is typical of the phthalocyanine chromophore. Moreover, the boronated phthalocyanine exhibits a high photosensitizing efficiency against a model biological substrate, such as N-acetyl-L-tryptophanamide, and a singlet oxygen quantum yield of 0.53 in dimethylformamide. Even though the presence of the dodecaborane moiety appears to decrease the affinity of the phthalocyanine for HT-1080 transformed human fibroblasts, the boronated phthalocyanine causes an essentially complete loss of cell viability upon irradiation with 600-700 nm light under mild conditions (1 microM concentration, 5-min irradiation at 10 mW/cm(2)).

Regio- and stereoselective cycloadditions of cyclic nitrones to maleic diamide forced in a peptide: synthesis of potent ligands of human NK-2 receptor.

The regioselectivity and the stereoselectivity induced by relatively small peptidomimetic maleic diamide 1 in cycloaddition reactions with cyclic nitrones 2-5 was studied. The high regio- and stereoselectivity observed, sensibly increased by nonpolar solvents, was the effect of a double-asymmetric induction produced by the nitrone substituent on the pseudopeptidic tether. A new class of potent human tachykinin NK-2 receptor ligands was synthesized.

[Ventricular fibrillation in the initial phase of acute myocardial infarct]. / La fibrillazione ventricolare nella fase iniziale dell'infarto miocardico acuto.

In order to determinate the incidence, predictivity and prognosis of ventricular fibrillation in the early phase of acute myocardial infarction a series of 301 patients with acute myocardial infarction consecutively assisted by the Mobile Coronary Care Unit of Florence was analyzed. 151 patients (50.2%) received intensive care within 2 hours from the onset of the symptoms, 75 patients (24.9%) received intensive care between the second and sixth hour. 38 patients (12.6%) had at least one episode of ventricular fibrillation. 30% of the episodes of ventricular fibrillation happened within 1 hours from the onset of the symptoms, 47.4% within 2 hours, 74% within 6 hours. Serious arrhythmias complicated the early phase of acute myocardial infarction, but only sinus bradycardia seems to have a significant predicativity of ventricular fibrillation (P less than 0.05). We found that hospital survival resuscitated patients is strictly related to the time between early symptoms and the episode of ventricular fibrillation: 91% of the patients with ventricular fibrillation within 1 hour were discharged alive from hospital, 71% of those with ventricular fibrillation within 6 hours, 20% of those with ventricular fibrillation beyond 6 hours (P less than 0.01). The high rate and the favourable prognosis of ventricular fibrillation in the early phase of acute myocardial infarction must lead to a widespread implementation of rapid response emergency care systems away from hospital.

[Mobile coronary unit of Florence: early care of arrhythmias not due to acute coronary insufficiency]. / Unità coronarica mobile di Firenze: intervento precoce per disturbi del ritmo non dipendenti da insufficienza coronarica acuta.

The aim of Mobile Coronary Care Units (M.C.C.U.) is to reduce the delay in delivering intensive care to patients with a heart attack. In the city of Florence a M.C.C.U. has been available since November 1979. During the first year the staff of the M.C.C.U. has treated 158 cases of serious cardiac arrhythmias which occurred among 486 interventions. In 94 patients cardiac arrhythmias followed an acute coronary attack. In 64 patients coronary heart disease could not be demonstrated. This study concerns the latter group of patients. The mean age was 65.2 years and 39 patients (61%) were women. The mean time from the onset of the symptoms to the arrival of the M.C.C.U. team was 3h and 2 min, whereas the mean time from the call to the arrival was 14 min. Sixty patients had atrial arrhythmias (29 atrial fibrillation, 2 atrial flutter, 22 atrial tachycardia, 7 premature atrial contractions) and 4 patients had ventricular arrhythmias (1 ventricular tachycardia, 1 ventricular flutter, 2 premature ventricular contractions). In thirty-nine patients (61%) the cardiac arrhythmia was abolished by the staff of the M.C.C.U.. Of the remaining 28 patients, 10 were brought to the hospital and 18 were left at home. None of these needed later admission to the hospital. So the treatment at home of cardiac arrhythmias has been successful in the majority of patients. Bunaftine was the antiarrhythmic drug more frequently used (23 cases, 34%) with a high percentage of success (87%). In planning medical emergency services to the community, one can envisage the use of the M.C.C.U. facilities to treat at home those arrhythmias that are not associated with an acute coronary attack.