Biomedical subjects

A Balbi

Publications and source records attributed to A Balbi.

At least 19 recordsLinked to original sources

PubMed2004

Psychiatric emergencies and services availability: a comparison of two hospitals in Rome.

The development of Psychiatric Emergency Services (PES) as an autonomous organization has allowed the registration of urgent request in different urban areas and their correlation with real clinical needs. Our aim was to investigate different patterns of psychiatric emergencies, considering that A) qualitative differences in diagnostic distribution could emerge in relation to the availability of local hospital services; B) gender differences could condition the type of demand. In particular, the availability of services appears to have a modulating effect on the demand: it's possible to deduce that socio-economic factors can influence demand and change over time the epidemiological features of patients availing of PES.

Adult↗

PubMed2002

Estimate of the cosmological bispectrum from the MAXIMA-1 cosmic microwave background map.

We use the measurement of the cosmic microwave background taken during the MAXIMA-1 flight to estimate the bispectrum of cosmological perturbations. We propose an estimator for the bispectrum that is appropriate in the flat sky approximation, apply it to the MAXIMA-1 data, and evaluate errors using bootstrap methods. We compare the estimated value with what would be expected if the sky signal were Gaussian and find that it is indeed consistent, with a chi(2) per degree of freedom of approximately unity. This measurement places constraints on models of inflation.

Journal Article↗

PubMed2001

Tests for Gaussianity of the MAXIMA-1 cosmic microwave background map.

Gaussianity of the cosmological perturbations is one of the key predictions of standard inflation, but it is violated by other models of structure formation such as cosmic defects. We present the first test of the Gaussianity of the cosmic microwave background (CMB) on subdegree angular scales, where deviations from Gaussianity are most likely to occur. We apply the methods of moments, cumulants, the Kolmogorov test, the chi(2) test, and Minkowski functionals in eigen, real, Wiener-filtered, and signal-whitened spaces, to the MAXIMA-1 CMB anisotropy data. We find that the data, which probe angular scales between 10 arcmin and 5 deg, are consistent with Gaussianity. These results show consistency with the standard inflation and place constraints on the existence of cosmic defects.

Journal Article↗

PubMed2001

Cosmology from MAXIMA-1, BOOMERANG, and COBE DMR cosmic microwave background observations.

Recent results from BOOMERANG-98 and MAXIMA-1, taken together with COBE DMR, provide consistent and high signal-to-noise measurements of the cosmic microwave background power spectrum at spherical harmonic multipole bands over 2<l less similar to 800. Analysis of the combined data yields 68% (95%) confidence limits on the total density, Omega(tot) approximately 1.11+/-0.07 (+0.13)(-0.12), the baryon density, Omega(b)h(2) approximately 0.032(+0.005)(-0.004) (+0.009)(-0.008), and the scalar spectral tilt, n(s) approximately 1.01(+0.09)(-0.07) (+0.17)(-0.14). These data are consistent with inflationary initial conditions for structure formation. Taken together with other cosmological observations, they imply the existence of both nonbaryonic dark matter and dark energy in the Universe.

Journal Article↗

PubMed2000

Synthesis of ionones and carvone analogues: olfactory properties and preliminary toxicity assays.

Vilsmeier reagents react with alpha/beta-ionones and carvone to produce aldehydes 7-11 in a one-step procedure. The indene derivative 11, which came from the double iminoalkylation of carvone and ring closure with the elimination of dimethylamine, was practically odourless, while all the others had peculiar odours which were very different from the starting material. The cytotoxicity data of 9 and 10, which are the most promising potential perfume ingredients, are also reported.

Alkenes↗

PubMed1999

Interaction of oligonucleotides conjugated to substituted chromones and coumarins with HIV-1 reverse transcriptase.

Ten different pyranone-related substituents (chromones or coumarins) were covalently linked to the 5' end of various oligonucleotides (ODN). The interaction of these compounds with human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) was analyzed. A different behavior was found to depend on the structure of the oligonucleotide derivatives. Some compounds activated the enzyme at relatively low concentrations (0.1-0.5 microM), followed by an inhibition of the activity at higher concentrations (5-20 microM), whereas others behave just as inhibitors. Because the presence of some coumarin or chromone derivatives conjugated to ODNs enhanced the interaction with the reverse transcriptase, we analyzed the capacity of such ODN derivatives to be used as primers. The introduction of substituent I, a chromone derivative, the 2-[(3-(aminopropyl)amino]-8-isopropyl-5-methyl-4-oxo-4H-1-benzopyran-3-c arbaldehyde], and II, a coumarin derivative, the 1-(3-aminopropoxy)-2-ethyl-3H-naphto[2,1-b]pyran-3-one, into the 5' end of a noncomplementary ODN allowed these compounds to be used as primers. In the case of complementary primers, the presence of conjugated derivatives enhanced the affinity with Km values that were two to three orders of magnitude lower than that of a complementary primer of the same length. After addition of a ddT-unit to the 3'-terminal end of the ODN, some of these primers became very effective inhibitors of RT with Ki values in the nanomolar range.

Chromones↗

PubMed1998

HIV-1 reverse transcriptase is capable of elongating derivatives of sequence specific noncomplementary oligodeoxynucleotides.

We have carried out a comparison of KM and Vmax values for various primers in the polymerization reaction catalyzed by the HIV-1 RT. The affinity of RT for complementary d(pT)6 containing two different 5'-end pyranone derivatives was 2-3 orders of magnitude higher (KM = 3-15 nM) than that of d(pT)6 (KM = 12.6 mM). Oligodeoxynucleotides (ODNs) noncomplementary to poly(A) template were not elongated by RT. However, derivatives of d(CAGGTG) containing the 5'-terminal chromone and coumarin related groups were efficient primers showing KM (30-300 nM) and Vmax (75-93%) values comparable with that for d(pT)10 (800 nM; 100%). The [d(CAGGTG)]ddT ODN derivatives were effective inhibitors of RT. The primer function of derivatives of noncomplementary ODNs appears to be due to the additional interactions of their 5'-terminal groups with the enzyme tRNA-binding site.

Binding Sites↗

PubMed1998

Simultaneous HPLC determination of multiple components in a commercial cosmetic cream.

A high-performance liquid chromatographic method for the simultaneous determination of magnesium ascorbyl phosphate (I), imidazolidinylurea (II), a mixture of methyl-(III), ethyl-(IV), propyl-(V), butyl-(VI) parabens dissolved in phenoxyethanol, and ascorbyl palmitate (VII), was studied by using a cyano-propyl column and a methanol gradient at 220 and 240 nm. Calibration curves were found to be linear in the 0.05-5 mg ml(-1) range (compounds I, II, VII) and 0.9-160 mg ml(-1) (compounds III-VI). Linear regression analysis of the data demonstrates the efficacy of the method in terms of precision and accuracy. An extraction method is developed and validated in order to apply this chromatographic method to a commercial cosmetic cream. The precision of this method, calculated as the relative standard deviation (RSD) of the recoveries (1.57-2.21%) was excellent for all compounds I-VII.

Ascorbic Acid↗

PubMed1997

Synthesis and hybridization properties of the conjugates of oligonucleotides and stabilization agents--II.

New pyranone derivatives having tri- or pentamethylenamine linker functions were synthesized. These derivatives were covalently attached through the 5'-phosphoramide linkage to heptanucleotide pd(CCAAACA). Complementary complexes of the octanucleotide pd(TGTTTGGC) and above oligonucleotide conjugates were tested for their thermodynamic response. The Tm data and thermodynamic parameters for complex formation have demonstrated the ability of chromone (gamma-pyrone) and coumarin (alpha-pyrone) derivatives to stabilize strongly 7-mer/8-mer complementary complex, most likely through the stacking interaction of the pyran aromatic system with the neighboring nucleotide bases. The effect of chromone (or coumarin) derivatives on the stability of the oligonucleotide complexes (delta delta G at 37 degrees C ranged from -1.0 to -1.7 kcal/mol) was shown to be comparable to the effect of one nucleotide base pair and similar to the effect (delta delta G at 37 degrees C ranged from -1.5 to -2.0 kcal/mol) found for acridineoligonucleotide conjugates served in this study as a reference.

Acridines↗

PubMed1996

Characterization and quantitation of the active polynucleotide fraction (PDRN) from human placenta, a tissue repair stimulating agent.

The polydeoxyribonucleotide (PDRN) fraction is an extract which forms the active component in a new formulation of the drug Placentex (a tissue repair stimulating agent), obtained from human placenta through an original proprietory extraction method. From a comparison of the UV, NMR and IR spectra of this fraction (before and after nuclease treatment) with that of a similar standard (Sigma D1501), it was shown that the active substances in the PDRN fraction mainly consist of a mixture of DNA fragments. By gel electrophoresis, the molecular weights of the DNA fragments were shown to range from 50 to 2000 base pairs. Finally, an HPLC method is described, based on an anion-exchange material capable of determining the amount of PDRN in different batches of the extract, which varied from 80 to 90%.

Chromatography, High Pressure Liquid↗

PubMed1996

Synthesis and antirhinovirus activity of 3-(diethylamino)-5-phenylisoxazole derivatives.

Previous studies showed that some 2'-alkyloxyisoxazoles 2b-d obtained from 3-(diethylamino)-5-(2'hydroxy-4'-methoxyphenyl)isoxazole 2a were endowed with an interesting anti-group B rhinovirus activity (action on HRV-2 serotype). Other isoxazoles (WIN compounds) are well known to have anti-group A rhinovirus activity (action on HRV-14 serotype). To obtain an action similar to that of WIN compounds, starting from 2a, the 2'-acyl (3,4,5) and 2'alkyl (6,8) derivatives were synthesized. Also some Mannich bases (9,10) and bisisoxazoles (7,11,13,14) were studied. Though some of the tested compounds mainly exhibited anti-group B rhinovirus activity, their potency was less intense with respect to the above mentioned compounds 2b-d. The only N-methylpiperazinomethyl derivative 10 was slightly active against both tested serotypes.

Antiviral Agents↗

PubMed1995

Sulphonamides as anti-inflammatory agents: old drugs for new therapeutic strategies in neutrophilic inflammation?

1. It is well known that neutrophils act as mediators of tissue injury in a variety of inflammatory diseases. Their histotoxic activity is presently thought to involve proteinases and oxidants, primarily hypochlorous acid (HOCl). This oxidant is also capable of inactivating the specific inhibitor of neutrophil elastase (alpha 1-antitrypsin), thereby favouring digestion of the connective matrix. 2. In the present work, we found that sulphanilamide and some sulphanilamide-related anti-inflammatory drugs such as dapsone, nimesulide and sulphapyridine reduce the availability of HOCl in the extracellular microenvironment of activated neutrophils and prevent the inactivation of alpha 1-antitrypsin by these cells in a dose-dependent manner. The ability of each drug to prevent alpha 1-antitrypsin from inactivation by neutrophils correlates significantly with its capacity to reduce the recovery of HOCl from neutrophils. Five other non-steroidal anti-inflammatory drugs were completely ineffective. 3. Therefore, sulphanilamide-related drugs, i.e. dapsone, nimesulide and sulphapyridine, have the potential to reduce the bioavailability of neutrophil-derived HOCl and, in turn, to favour the alpha 1-antitrypsin-dependent control of neutrophil elastolytic activity. These drugs appear as a well-defined group of agents which are particularly prone to attenuate neutrophil histotoxicity. They can also be viewed as a previously unrecognized starting point for the development of new compounds in order to plan rational therapeutic strategies for controlling tissue injury during neutrophilic inflammation.

Anti-Inflammatory Agents↗

PubMed1995

Heterocyclizations under Vilsmeier conditions: an old method with interesting possibilities in drug research.

The Vilsmeier reaction is well known and widely used in substituting activated hydrogen with a formyl group into a great variety of molecules. This reaction is also a powerful synthetic tool used to obtain many heterocycle compounds, which may be difficult to reach or at times inaccessible. The more relevant data published in chemical literature in the last ten years and my personal experience are reported in the following with the aim of showing the valuable synthetic potential of this reaction.

Adjuvants, Immunologic↗

PubMed1994

A novel dimeric fluoropyrimidine molecule behaves as a remote precursor of 5-fluoro-2'-deoxyuridine in human erythrocytes.

A new dimeric fluoropyrimidine molecule (5-fluoro-2'-deoxyuridilyl-(5'-->3')-5-fluoro-2'-deoxy-5'-uridylic acid, Compound 1) was chemically synthesized from two separately deblocked 5-fluoro-2'-deoxyuridine mononucleotide moieties. Other structurally related nucleotides, 5-fluoro-2'-deoxyuridine-5'-diphosphate (FdUDP), 5-fluoro-2'-deoxyuridine-5'-triphosphate (FdUTP) and 5-fluoro-2'-deoxyuridine-3',5'-bisphosphate were also synthesized. The structures of all synthesized molecules were verified by mass spectrometric analyses and were consistent with expected molecular mass values. The metabolic patterns of conversion of Compound 1 were investigated both in human erythrocyte lysates and in intact erythrocytes previously loaded with this molecule according to a highly conservative encapsulation procedure. In hemolysates, Compound 1 was transformed to 5-fluoro-2'-deoxyuridine (FUdR) and to 5-fluorouracil (FU) through the intermediate formation of 5-fluoro-2'-deoxyuridine-5'-monophosphate (FdUMP). In intact red cells, Compound 1 still generated FUdR (and to a lesser extent FU), that was then released outside. The conversion pathway involves a phosphodiesterase-catalysed hydrolysis of Compound 1 into two FdUMP molecules, followed by further dephosphorylation to FUdR and by partial conversion to FU. Unlike hemolysates, Compound 1-loaded intact erythrocytes featured transient formation of FdUDP and FdUTP, both metabolites representing storage compounds for the final and sustained production of FUdR and FU. Therefore, human erythrocytes can behave as bioreactors ensuring the time-controlled production and delivery of the two powerful antitumor drugs FUdR and FU from encapsulated Compound 1. This new molecule and other compounds as well (e.g. FdUDP and FdUTP) can be viewed as useful pre-prodrugs, exploitable for intraerythrocytic bioconversion reactions.

Erythrocytes↗

PubMed1993

Synthesis in solution of oligodeoxynucleotides and some their 5'- and 3'-linked derivatives.

Antisense oligodeoxynucleotides (ODNs) and their derivatives are highly interesting tools to regulate gene expression and promising drugs for antiviral and anticancer therapy. In view of performing more extensive pharmacological trials requiring relatively great amounts of ODNs, we used a method of ODN synthesis derived from the phosphotriester approach which allow to prepare ODNs covalently linking cholesteryl residue (in 5' or 3') and phenazinium group (in 5'). HPLC purifications are discussed.

Base Sequence↗

PubMed1992

HPLC analysis of theophylline: bioequivalence study of two sustained-release formulations at steady state.

Theophylline is at present one of the standard drugs used for asthma and obstructive respiratory diseases but still presents clinical problems due to its narrow therapeutic range. To provide additional studies in this important field, the in vivo bioavailability of Bronchoretard, a theophylline sustained-release preparation, not available at present in Italy, has been compared with that of Diffumal, formulation of large consumption. An isocratic reverse-phase HPLC method to assess the theophylline in plasma is described. The two formulations present good bioequivalence, though Bronchoretard seems to provide little therapeutic advantage.

Biological Availability↗

PubMed1991

Study of bioequivalence of magnesium and sodium valproates.

The in vivo bioavailability of magnesium valproate (500 and 1000 mg) enteric-coated tablets has been compared with that of sodium valproate (Depakine) (500 and 1000 mg) enteric-coated tablets. The two preparations were found to be bioequivalent; magnesium valproate appeared to be a drug without bioavailability problems and with reduced inter-subject variability, compared with that of sodium valproate. A reversed-phase HPLC method for the determination of valproates is described.

Administration, Oral↗

PubMed1991

Antiplatelet effect of 2-(diethylamino)-7-hydroxychromone.

In this study the in vitro influence of 2-(diethylamino)-7-hydroxychromone (RC39II) on platelet aggregating responses, thromboxane A2 (TxA2) production, release reaction and intraplatelet cyclic AMP (cAMP) content has been investigated. The drug exerts a dose-dependent inhibitory effect on aggregating response to arachidonic acid, U46619, thrombin, collagen and calcium ionophore A23187. Inhibiting concentrations of RC39II also prevent platelet release reaction and TxA2 formation. RC39II potentiates platelet cAMP accumulation by Iloprost. Several studies, carried out on soluble cAMP phosphodiesterase (PDE) have shown that the drug inhibits phosphodiesterase in a dose-dependent manner. No effect was shown on adenylate cyclase activity from platelet membranes.

Blood Platelets↗