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Biomedical subjects

F De Angelis

Publications and source records attributed to F De Angelis.

At least 19 recordsLinked to original sources
PubMed2006

Efficient green-blue-light-emitting cationic iridium complex for light-emitting electrochemical cells.

A highly luminescent novel cationic iridium complex [iridium bis(2-phenylpyridine)(4,4'-(dimethylamino)-2,2'-bipyridine)]PF6 was synthesized and characterized using NMR, UV-visible absorption, and emission spectroscopy and electrochemical methods. This complex displays intense photoluminescence maxima in the green-blue region of the visible spectrum and exhibits unprecedented phosphorescence quantum yields, 80 +/- 10% with an excited-state lifetime of 2.2 mus in a dichloromethane solution at 298 K. Single-layer light-emitting electrochemical cells with the charged complex as conducting and electroluminescent material sandwiched between indium-tin oxide and Ag electrodes were fabricated, which emit green-blue light with an onset voltage as low as 2.5 V. Density functional theory calculations were performed to provide insight into the electronic structure of the [iridium bis(2-phenylpyridine)(4,4'-(dimethylamino)-2,2'-bipyridine)]PF6 complex, comparing these results with those obtained for [iridium bis(2-phenylpyridine)(4,4'-tert-butyl-2,2'-bipyridine)]PF6.

Journal Article↗
PubMed2004

First-principle molecular dynamics with ultrasoft pseudopotentials: parallel implementation and application to extended bioinorganic systems.

We present a plane-wave ultrasoft pseudopotential implementation of first-principle molecular dynamics, which is well suited to model large molecular systems containing transition metal centers. We describe an efficient strategy for parallelization that includes special features to deal with the augmented charge in the contest of Vanderbilt's ultrasoft pseudopotentials. We also discuss a simple approach to model molecular systems with a net charge and/or large dipole/quadrupole moments. We present test applications to manganese and iron porphyrins representative of a large class of biologically relevant metalorganic systems. Our results show that accurate density-functional theory calculations on systems with several hundred atoms are feasible with access to moderate computational resources.

Binding Sites↗
PubMed2001

Reversible carnitine palmitoyltransferase inhibitors with broad chemical diversity as potential antidiabetic agents.

A series of carnitine related compounds of general formula XCH(2)CHZRCH(2)Y were evaluated as CPT I inhibitors in intact rat liver (L-CPT I) and heart mitochondria (M-CPT I). Derivative 27 (ZR = -HNSO(2)R, R = C(12), X = trimethylammonium, Y = carboxylate, (R) form) showed the highest activity (IC(50) = 0.7 microM) along with a good selectivity (M-CPT I/L-CPTI IC(50) ratio = 4.86). Diabetic db/db mice treated orally with 27 showed a significant reduction of serum glucose levels.

3-Hydroxybutyric Acid↗
PubMed2000

Effects of lithium carbonate (Li2CO3) on in-vitro-cultured normal human skin explants.

The early morphological changes induced by lithium carbonate, a well-known psoriasis-provoking drug, were studied on cultured skin. Normal human skin from patients undergoing mastectomy was cultured in the presence of 3 mM, 6 mM and 10 mM of Li2CO3 for 4 days. The morphological changes were then evaluated by three observers in a blind manner and their reports were matched and collated. The cultured skin in the presence of Li2CO3 showed cell crowding of keratinocytes in the lower part of the epidermis, indicating epidermal hyperplasia. Another striking finding was intercellular oedema and vacuolar alteration with formation of small cavities in the upper dermis. There was no evidence of parakeratosis or any other histological characteristic of psoriasis, except hyperproliferation of the epidermis. Based on our knowledge of mechanisms of lithium action, we proposed two competitive explanations for its action on the epidermis: i) that lithium acts directly on dividing cells of the epidermis; and ii) that it acts indirectly by altering epidermal barrier function. Although we lack definite proof, we suggest that the observed morphological changes, in particular the non-specific stimulus to epidermal proliferation, are the primary events which initiate the process that will ultimately lead to the development of psoriasis in a predisposed patient.

Cells, Cultured↗
PubMed1999

Expression of cripto and amphiregulin in colon mucosa from high risk colon cancer families.

We assessed the expression of the epidermal growth factor (EGF)-related peptides, cripto-I (CR-I) and amphiregulin (AR), in a small panel of human colon adenomas and carcinomas. CR-I immunoreactivity was found in 17/31 (55%) of colon adenomas, and in 33/39 (84%) colon carcinomas. AR immunostaining was observed in 16/26 adenomas (61%) and in 20/26 carcinomas (77%). CR-I and AR staining were also assessed in 29 specimens from 24 individuals that belong to families with high incidence of colorectal carcinoma, and in 5 non-high risk individuals. Expression of CR-I was detected in 18/29 (62%) of high risk colon mucosa specimens, but only in 1/5 (20%) specimens from non-high risk individuals, while AR staining was found in 20/29 (69%) and in 4/5 (80%) of colon mucosa samples from high and low risk individuals, respectively. A majority (21/29; 72%) of the specimens from the high risk individuals had a high proliferative rate, as measured by Ki-67 staining. A statistically significant correlation was found between high proliferative rate, increased expression of CR-I and reduced expression of AR in the mucosa specimens from high risk individuals, suggesting that these might represent early events in colon tumorigenesis.

Adenoma↗
PubMed1998

L-carnitine esters as "soft", broad-spectrum antimicrobial amphiphiles.

A new class of antimicrobial, "soft", quaternary ammonium l-carnitine esters, of the type (CH3)3N+-CH2-CHOCO(R1)-CH2-COO(R2) Cl-, has been designed, with R1 and R2 being in general long-chain alkyl substituents. The series shows good activity against a wide range of bacteria, yeasts, and fungi. Lipophilicity has been measured by RP-HPLC method to give the logarithm of the experimental capacity factor (log k'), and a quantitative relationship has been determined between log k' and the theoretical partition coefficient (CLOGP); also, bond-dipole descriptors have been introduced into calculations by accounting for polar moieties present within the apolar cores of the molecules, giving a more refined calculated capacity factor (log k'calcd). Finally the latter has been related to the antimicrobial activity (MIC values). The proposed models are predictive for the best broad-spectrum antimicrobial compound within the series.

Anti-Bacterial Agents↗
PubMed1997

Patients with deficit, nondeficit, and negative symptom schizophrenia: do they differ during episodes of acute psychotic decompensation?

The aims of this study were (1) to test the hypothesis that the clinical profiles of deficit, nondeficit, and negative symptom patients are difficult to distinguish during episodes of acute psychotic decompensation; and (2) to compare these groups of schizophrenic patients in terms of sociodemographic and anamnestic variables. Patients admitted for acute psychotic decompensation were retrospectively diagnosed as having deficit (N = 18) or nondeficit (N = 40) forms of schizophrenia and their symptom profiles were evaluated cross-sectionally by using various rating scales (SAPS, SANS, and PANSS). As a whole, nondeficit patients were clearly differentiated from deficit patients by lower severity of negative symptoms. However, the subgroup (N = 24) of nondeficit patients with prominent negative symptoms that were secondary and/or nonenduring showed a symptom profile largely overlapping with that of deficit patients. Attentional impairment was the only measure distinguishing deficit and negative symptom patients. As for trait variables, deficit patients had lower education than the other two groups and, among male subjects, there was a higher percentage of left-handers in the deficit group than in the negative symptom subgroup. These results confirm the importance of diagnosing the deficit syndrome during periods of clinical stability in order to avoid the risk of misclassifying negative symptom patients into the deficit group.

Adult↗
PubMed1997

Quantification of S-carboxymethyl-(R)-cysteine in human plasma by high-performance ion-exchange liquid chromatography/atmospheric pressure ionization mass spectrometry.

The determination of S-carboxymethyl-(R)-cysteine (SCMC) in human plasma during extended bioequivalence studies demands a rapid, accurate and selective assay technique. A liquid chromatographic/mass spectrometric method was developed which involves rough protein precipitation followed by high-performance liquid chromatographic separation with an ion-exchange column and atmospheric pressure ionization (API) mass spectrometric detection, with the instrument operating with electrospray ionization (ESI) and in the selected-ion monitoring mode. The drug and the internal standard S-[(R)-1-carboxyethyl]-(R)-cysteine (SCEC) are detected by focusing the first quadrupole of the triple stage system on MH+ ions, thus permitting elimination of endogenous interfering substances and allowing a detection limit of 0.05 microgram ml-1. The chromatographic run time is 16 min and the method has sufficient sensitivity, precision, accuracy and selectivity for routine analyses of clinical plasma samples containing SCMC at concentrations in the range 0.2-20 micrograms ml-1. In summary, this LC/MS-based assay of SCMC demonstrates advantages of easy sample preparation, low limit of quantification (200 ng per ml of human plasma) without any derivatization step, high specificity and rapid sample analysis with an overall throughput of more than 60 analyses per day.

Calibration↗
PubMed1995

Spectrin Anastasia (alpha I/78): a new spectrin variant (alpha 45 Arg-->Thr) with moderate elliptocytogenic potential.

We describe a white Italian kindred in which hereditary elliptocytosis (HE) is associated with abnormal level of alpha I/78 peptide in spectrin digest. Clinical phenotype varied among the family members ranging from asymptomatic to mild haemolytic HE. The original mutation responsible is a G-C substitution of the spectrin alpha-gene: alpha 45 Arg-->Thr (AGG-->ACG). The corresponding spectrin is designated spectrin Anastasia. Utilizing a secondary structure predictive method we suggest that this mutation has a poor capability to induce conformational changes of the tetramerization site and thus shows a moderate elliptocytogenic potential.

Adult↗
PubMed1994

Analysis of a bioactive synthetic analogue of tuftsin by tandem mass spectrometry: anomalous fast atom bombardment activated processes.

Fast atom bombardment (FAB) tandem mass spectrometry has been used to analyse the biologically potent, partially modified retro-inverso (PMRI) synthetic isomer of tuftsin: this compound represents the active peptide of the fraction of gamma-globulin (leukokinin) which binds specifically to blood neutrophilic leukocytes and monocytes. Protonated molecules and fragment ions were collisionally dissociated at low energies in a triple-quadrupole mass spectrometer to yield a complete picture of the reactions that occur in the condensed and in the gas phase. The study shows that, when retro-inversion is within the N-terminal amino acid, charge localization at the basic sites (possibly at the N-terminus) induces a marked decomposition of the molecule, the loss of ammonia being the most favourable fragmentation process. Also, artifacts are formed in the liquid phase via bimolecular reactions promoted by the high-energy beam. The findings indicate that despite the fact that PMRI isomers of this type are stable against exo-peptidases and also stable under acidic conditions, they appear to be labile under conditions where the energy deposition, due to FAB is necessarily high.

Amino Acid Sequence↗
PubMed1989

Fast atom bombardment mass spectrometry and selective acid hydrolysis for the analysis of partially modified retro-inverso peptide analogues.

Fast atom bombardment (FAB) mass spectrometry has been successfully applied to the analysis of partially modified retro-inverso peptide isomers. The spectra are characterized by abundant protonated molecular ions and also by sequence ions due to fragmentation of the inverted bonds. Unambiguous information, as to the nature and the position in the backbone of the amino acids involved in the partial modification of the structure, are given by using a combination of FAB mass spectrometry and partial, selective acid hydrolysis, without separation of the resulting peptide mixtures.

Hydrolysis↗
PubMed1986

Peptide sequencing by using a combination of partial acid hydrolysis and fast-atom-bombardment mass spectrometry.

To overcome the limit of the intensity of ions carrying sequence information in structural determinations of peptides by fast-atom-bombardment m.s., we have developed a method that consists in taking spectra of the peptide acid hydrolysates at different hydrolysis times. Peaks correspond to the oligomers arising from the peptide partial hydrolysis. The sequence can then be identified from the structurally overlapping fragments.

Amino Acid Sequence↗