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Biomedical subjects

A De Luca

Publications and source records attributed to A De Luca.

At least 55 records · Page 3Linked to original sources
PubMed2001

RACK1 interacts with E1A and rescues E1A-induced yeast growth inhibition and mammalian cell apoptosis.

The adenoviral E1A proteins are able to promote proliferation and transformation, inhibit differentiation, induce apoptosis, and suppress tumor growth. The extreme N terminus and conserved region one of E1A, which are indispensable for transcriptional regulation and for binding to p300/CBP, TBP, and pCAF, play essential roles in these abilities. These observations strongly suggest an intrinsic link between E1A-mediated transcriptional regulation and other effects. In this report, we show that E1A inhibits the normal growth of Saccharomyces cerevisiae HF7c, and this inhibition also depends on the domains required for transcriptional regulation. We demonstrate that E1A associates with histone acetyltransferase activity and represses the transactivation activity of transcription factor in S. cerevisiae, suggesting that E1A may suppress the expression of genes required for normal growth. Based on yeast growth rescue, we present a genetic screening strategy that identified RACK1 as an E1A antagonizing factor. Expression of human RACK1 efficiently relieves E1A-mediated growth inhibition in HF7c and protects human tumor cells from E1A-induced apoptosis. Finally, we show that RACK1 decreases E1A-associated histone acetyltransferase activity in yeast and mammalian cells, and physically interacts with E1A. Our data demonstrate that RACK1 is a repressor of E1A, possibly by antagonizing the effects of E1A on host gene transcription.

Adenovirus E1A Proteins↗
PubMed2001

Incidence and determinants of bacterial infections in HIV-positive patients receiving anti-Pneumocystis carinii/Toxoplasma gondii primary prophylaxis within a randomized clinical trial.

We assessed the incidence and determinants of bacteremia, pneumonia, and sinusitis/otitis in HIV-positive people receiving cotrimoxazole (CTX) or dapsone-pyrimethamine (DP) for primary prophylaxis of Pneumocystis carinii pneumonia (PCP) and toxoplasmic encephalitis (TE) within a randomized clinical trial. In total, 244 patients were randomized: 122 were assigned to CTX and 122 to DP. In the cohort, 22 bacteremia, 63 pneumonia, and 39 sinusitis/otitis cases were observed. Incidence rates of bacteremia, pneumonia, and sinusitis/otitis as well as the 2-year probability of remaining free from any bacterial infection were not significantly different between the two groups. At multivariate analysis, the risks of developing bacteremia and pneumonia were found to be independently increased by the use of a central venous catheter (hazard ratio [HR], 4.48; p <.05 and HR, 4.13; p <.01, respectively) and by hospitalization (HR, 28.82; p <.05 and HR, 10.15; p <.05, respectively). In conclusion, CTX at the dosage employed for primary PCP/TE prophylaxis does not seem to protect against bacterial infections more than second-line DP.

Adult↗
PubMed2001

The role of EGF-related peptides in tumor growth.

The epidermal growth factor (EGF) family of peptides encodes several proteins that can function as growth factors. The EGF-like peptides, with the exception of proteins of the EGF-CFC subfamily, bind and activate tyrosine kinase receptors that belong to the erbB family. The EGF-like peptides are overexpressed in a majority of human carcinomas as compared with their nontransformed counterpart. By using different approaches, it has been shown that several different EGF-like peptides function as autocrine growth factors in carcinoma cell lines of different histological origin. Direct evidence that the EGF-like growth factors might function as transforming genes has been provided by in vitro and in vivo studies. In particular, the development of different transgenic mouse lines in which EGF-like growth factors have been overexpressed by means of tissue-specific or nonspecific promoters has provided invaluable information relating to their ability to function as dominantly transforming oncogenes. Cooperation of the EGF-like peptides with cellular protooncogenes in determining cell transformation has been demonstrated by using both in vitro and transgenic mice systems. Taken together, these data strongly suggest that the EGF-like peptides are involved in the pathogenesis of human carcinomas, and that they might represent suitable targets for novel therapeutic approaches.

Amphiregulin↗
PubMed2001

Changing clinical presentation and survival in HIV-associated tuberculosis after highly active antiretroviral therapy.

OBJECTIVE: To assess changes in clinical presentation and outcome of HIV-associated tuberculosis (TB) before and after widespread implementation of highly active antiretroviral therapy (HAART). METHODS: We reviewed clinical charts of HIV-infected patients with culture-confirmed pulmonary TB in two referral clinical centers in Rome, Italy. The 67 patients diagnosed in 1995 to 1996 were compared with 51 patients diagnosed in 1997 to 1998. To analyze factors associated with survival we used a Cox model including antiretroviral therapy as a time-dependent covariate. RESULTS: Patients diagnosed in 1997 to 1998 were more likely to have TB as the first AIDS-defining illness (78% versus 58%, p <.05), to have HIV diagnosed <2 months before TB (33% vs. 7%, p <.005) and to have typical chest radiograph pattern (45% vs. 25%, p <.05), and had a higher CD4(+) count (median 105 vs. 43, p <.005). Survival at 1 year was 80% for patients diagnosed in 1997 to 1998 vs. 65% for those diagnosed in 1995 to 1996 (p by log-rank =.02). After adjusting at multivariate analysis, time period of diagnosis was not confirmed as associated with survival (hazard ratio, 1.05; 95% confidence interval, 0.39--2.81). Age, CD4+ cell count <25/mm(3), and AIDS-defining illnesses before TB diagnosis were all associated with an higher risk of death, whereas a decreased risk of death was observed in patients starting a triple combination antiretroviral therapy after TB diagnosis (hazard ratio, 0.14; 95% confidence interval, 0.03--0.57). CONCLUSIONS: Cases of HIV-associated TB occurring in patients with advanced immunosuppression and presenting with atypical radiologic appearance tend to be relatively less common in the HAART era. HAART is a major factor in prolonging survival in these patients.

Adult↗
PubMed2001

Plasma levels of interleukin-6 and interleukin-10 in preterm neonates evaluated for sepsis.

UNLABELLED: In a prospective study, plasma interleukin-6 (IL-6) and interleukin-10 (IL-10) levels were measured by enzyme-linked immunosorbent assay in 45 premature neonates (25-34 weeks gestational age) with signs and symptoms of suspected sepsis at 0, 12 and 24 h; C-reactive protein (CRP) was measured at 0-24 h after enrolment. Six subjects were excluded due to insufficient blood sampling. The remaining 39 neonates were assigned to one of three groups: 25 newborns with sepsis (blood culture positive), seven with pneumonia (positive results on broncho-alveolar lavage fluid culture and characteristic chest radiography) and seven with necrotising enterocolitis (NEC) (characteristic intestinal and radiological signs according to the criteria of Bell et al.). A group of 20 healthy preterm neonates represented control subjects. On admission, higher levels of IL-6, IL-10 and CRP were observed in neonates with sepsis: IL-6 (median 1500 pg/ml, range 487-10000 pg/ml), IL-10 (median 113 pg/ml, range 70-196 pg/ml), CRP (median 22 mg/l, range 4-80 mg/l); pneumonia: IL-6 (median 1500 pg/ml, range 747-8000 pg/ml, IL-10 (median 84 pg/ml, range 76-92 pg/ml), CRP (median 10 mg/l, range 8-33 mg/l) and NEC: IL-6 (median 6650 pg/ml, range 1595-7950 pg/ml), IL-10 (median 80 pg/ml, range 61-147 pg/ml), CRP (median 3 mg/l, range 2.8-8 mg/l) as compared to controls (IL-6 median 208 pg/ml, range 198-349 pg/ml; IL-10 median 36 pg/ml, range 19-50 pg/ml; CRP median < 2 mg/l) (P < 0.05). In neonates with sepsis, IL-6 levels were significantly correlated with IL-10 levels (r = 0.65; P = 0.04) at the time of the second sample. The highest IL-6 levels were observed at onset, while IL-10 was predominant 12 h later. On admission, IL-10 and CRP levels were significantly higher in non-survivors (IL-10 median 507 pg/ml, range 422-753 pg/ml; CRP median 123 mg/l, range 20-219 mg/l) than in survivors (IL-10 median 76 pg/ml, range 61-143 pg/ml; CRP median 8 mg/l range 3-46 mg/l), while IL-10 levels were significantly higher (P < 0.05) also 12 h after admission (non-survivors: IL-10 median 600 pg/ml, range 538-800 pg/ml; survivors: IL-10 median 74 pg/ml, range 53-161 pg/ml). IL-6 and IL-10 levels were significantly correlated with CRP levels on admission (r = 0.45; P = 0.05). CONCLUSION: Preterm neonates with sepsis, pneumonia or necrotising enterocolitis showed increased interleukin-6, interleukin-10 and C-reactive protein levels. High interleukin-10 concentration was associated with mortality and could be an early indicator of prognosis.

C-Reactive Protein↗
PubMed2001

Dopamine D4 receptor (DRD4) polymorphism and adaptability trait during infancy: a longitudinal study in 1- to 5-month-old neonates.

We have examined the relationship between the common dopamine D4 receptor (DRD4) exon III repeat polymorphism and infants' behavior measured with the Italian version of the Early and Revised Infancy Temperament Questionnaires (EITQ/RITQ) in 122 Italian neonates at 1 and 5 months of life, when the genetic contribution to the behavior can be more clearly assessed. Two-way (genotype x age) analysis of variance revealed a significant correlation with the temperamental subscale of adaptability [F(1, 120) = 5.26, P < 0.02]. At 1 month of life (early assessment), infants with long (L) DRD4 alleles presented significantly low scores (L 2.61 +/- 0.073; S 2.84 + 0.79; Newman-Keuls P = 0.03) in comparison with the high scores of infants with short (S) alleles (L 2.4 +/- 0.059; S 2.25 +/- 0.57). These differences were not detected at 5 months of life (late assessment), denoting a strong environmental effect at this age on the genetic background. These results confirm and extend the genetic influence of the DRD4 gene in human temperament at birth.

Adaptation, Psychological↗
PubMed2001

Carboxylic acids and skeletal muscle chloride channel conductance: effects on the biological activity induced by the introduction of an aryloxyalkyl group alpha to the carboxylic function of 4-chloro-phenoxyacetic acid.

2-(4-Chloro-phenoxy)propanoic and 2-(4-chloro-phenoxy)butanoic acids are compounds known to block chloride membrane conductance in rat striated muscle by interaction with a specific receptor. In the present study, a series of chiral analogues has been prepared and tested to evaluate the influence of a second aryloxy moiety introduced in the side-chain at a variable distance from the stereogenic centre. The results show that this chemical modification is detrimental for biological activity which, however, is increased by lengthening the alkyl chain up to three methylenic groups, then decreases to remain constant in the next analogues of the series. A possible explanation for this is proposed on the basis of steric effects and/or different approach of the molecules to the receptor.

2,4-Dichlorophenoxyacetic Acid↗
PubMed2001

Three novel mutations causing a truncated protein within the RP2 gene in Italian families with X-linked retinitis pigmentosa.

X-linked retinitis pigmentosa (XLRP) results from mutations in a number of loci, including RP2 at Xp11.3, and RP3 at Xp21.1. RP2 and RP3 genes have been identified by positional cloning. RP2 mutations are found in about 10% of XLRP patients. We performed a mutational screening of RP2 gene inpatients belonging to seven unrelated families in linkage with the RP2 locus. SSCP analysis detected three conformation variants, within exon 2 and 3. Direct sequencing of exon 2, disclosed a G-->A transition at nucleotide 449 (W150X), and a G-->T transversion in position 547 (E183X). Sequence analysis of exon 3 variant revealed an insertion (853/854insG), leading to a frameshift. In this patient, we detected an additional sequence alteration (A-->G at nucleotide 848, E283G). Each mutation was co-segregating with the disease in the affected family members available for the study. These mutations are expected to introduce a stop codon within the RP2 coding sequence probably resulting in a truncated or unstable protein.

Codon, Terminator↗
PubMed2001

Proximal stomach function in systemic sclerosis: relationship with autonomic nerve function.

Gastrointestinal involvement is frequent in patients with systemic sclerosis (SSc); however, studies on the proximal stomach and its regulation are lacking. It has been hypothesized that the primary event in the pathogenesis of gastrointestinal involvement in SSc is an early neural lesion. This study investigates proximal stomach function and its relation to autonomic nerve function in SSc. Twenty SSc patients classified in to clinical subsets, underwent measurement of proximal stomach function with and without glucagon by electronic barostat and an assessment of autonomic nerve function. SSc patients were not significantly different from 11 controls for gastric compliance (59.5+/-5.0 vs 47.7+/-4.2 ml/mm Hg, P = 0.1). The pressure-volume curves in each participant with and without glucagon were significantly different (P < 0.001). A significant positive association was found between gastric compliance and autonomic nerve function (P < 0.05). The change in gastric compliance during glucagon administration was significant-associated with autonomic function (P < 0.05). The perception cumulative scores did not differ between SSc patients and control subjects (P = 0.2). In conclusion, proximal stomach function is associated with autonomic nerve function in SSc patients. This confirms the frequent association of motility disorders with autonomic dysfunction in SSc.

Adult↗
PubMed2001

Alteration of the Bcl-2:Bax ratio in the placenta as pregnancy proceeds.

The placenta is the primary site of nutrient and gas exchange between mother and foetus. During human placental development, proliferation, differentiation and apoptosis occur at different stages. In order to clarify some of the molecular mechanisms underlying these events, we investigated the pattern of expression of two members of the Bcl-2 family in human placenta samples and compared them to the level of apoptosis detected by the TUNEL method. In particular, we evaluated the expression of Bcl-2 and Bax and their ratio during the first and third trimester. We found that Bcl-2 was generally expressed at low levels during the entire gestational period. On the other hand, Bax was low during the first trimester but increased towards the end of gestation. In accordance with the change of ratio of these two molecules, the increase of apoptotic cells was observable in the third trimester. These data indicate that Bcl-2 and Bax are spatio-temporally regulated during placental development and that the different expression of the above mentioned genes is at least in part responsible for the delicate balance between cell proliferation and programmed cell death in the human placenta during pregnancy.

Adult↗
PubMed2001

Alteration of excitation-contraction coupling mechanism in extensor digitorum longus muscle fibres of dystrophic mdx mouse and potential efficacy of taurine.

No clear data is available about functional alterations in the calcium-dependent excitation-contraction (e-c) coupling mechanism of dystrophin-deficient muscle of mdx mice. By means of the intracellular microelectrode "point" voltage clamp method, we measured the voltage threshold for contraction (mechanical threshold; MT) in intact extensor digitorum longus (EDL) muscle fibres of dystrophic mdx mouse of two different ages: 8 - 12 weeks, during the active regeneration of hind limb muscles, and 6 - 8 months, when regeneration is complete. The EDL muscle fibres of 8 - 12-week-old wildtype animals had a more negative rheobase voltage (potential of equilibrium for contraction- and relaxation-related calcium movements) with respect to control mice of 6 - 8 months. However, at both ages, the EDL muscle fibres of mdx mice contracted at more negative potentials with respect to age-matched controls and had markedly slower time constants to reach the rheobase. The in vitro application of 60 mM taurine, whose normally high intracellular muscle levels play a role in e-c coupling, was without effect on 6 - 8-month-old wildtype EDL muscle, while it significantly ameliorated the MT of mdx mouse. HPLC determination of taurine content at 6 - 8 months showed a significant 140% rise of plasma taurine levels and a clear trend toward a decrease in amino acid levels in hind limb muscles, brain and heart, suggesting a tissue difficulty in retaining appropriate levels of the amino acid. The data is consistent with a permanent alteration of e-c coupling in mdx EDL muscle fibres. The alteration could be related to the proposed increase in intracellular calcium, and can be ameliorated by taurine, suggesting a potential therapeutic role of the amino acid.

Animals↗
PubMed2001

Increased rigidity of the chiral centre of tocainide favours stereoselectivity and use-dependent block of skeletal muscle Na(+) channels enhancing the antimyotonic activity in vivo.

1. Searching for the structural requirements improving the potency and the stereoselectivity of Na(+) channel blockers as antimyotonic agents, new derivatives of tocainide, in which the chiral carbon atom is constrained in a rigid alpha-proline or pyrrolo-imidazolic cycle, were synthesized as pure enantiomers. 2. Their ability to block Na(+) currents, elicited from -100 to -20 mV at 0.3 Hz (tonic block) and 2-10 Hz (use-dependent block) frequencies, was investigated in vitro on single fibres of frog semitendinosus muscle using the vaseline-gap voltage-clamp method. 3. The alpha-proline derivative, To5, was 5 and 21 fold more potent than tocainide in producing tonic and 10 Hz-use-dependent block, respectively. Compared to To5, the presence of one methyl group on the aminic (To6) or amidic (To7) nitrogen atom decreased use-dependence by 2- and 6-times, respectively. When methylene moieties were present on both nitrogen atoms (To8), both tonic and use-dependent block were reduced. 4. Contrarily to tocainide, all proline derivatives were stereoselective in relation to an increased rigidity. A further increase in the molecular rigidity as in pyrrolo-imidazolic derivatives markedly decreased the drug potency with respect to tocainide. 5. Antimyotonic activity, evaluated as the shortening of the time of righting reflexes of myotonic adr/adr mice upon acute drug in vivo administration was 3 fold more effective for R-To5 than for R-Tocainide. 6. Thus, constraining the chiral centre of tocainide in alpha-proline cycle leads to more potent and stereoselective use-dependent Na(+) channel blockers with improved therapeutic potential.

Animals↗
PubMed2001

Epidemiology and prognosis of AIDS-associated progressive multifocal leukoencephalopathy in the HAART era.

Whereas most AIDS-related neurologic disorders have reduced incidence since HAART therapy was introduced, we find that the incidence of progressive multifocal leukoencephalopathy (PML) did not significantly differ between the pre-HAART and the HAART period (OR 0.78; 95% CI 0.41-1.50). These findings were confirmed by the preliminary results of the Italian Register Investigative Neuro AIDS (IRINA) Study, a prospective multicenter study started in January 2000, which showed that PML was the second most frequently diagnosed neurologic disorder after TE. A similar proportion of cases were found in HAART-naïve and HAART-experienced patients in our experience. PML was more common in the presence of HIV RNA > 500 copies/ml. Most of the cases occurring in HAART-exposed patients developed within the first 6 months of therapy. As others have reported, we find a prolonged survival in PML subjects prescribed HAART (245 days in the group treated with HAART versus 66 days in the group not treated with HAART; P at log rank = 0.001). However despite the survival benefit, AIDS-associated PML still has a serious prognosis. In fact, PML had the lowest 1-year survival probability of any cerebral disorder in our study (P = 0.0005). Our findings also confirm that CSF JCV DNA burden at baseline is a useful prognostic indicator with a threshold of 4.7 log(10) JCV copies/ml (P at log rank = 0.01) in our experience. CSF JCV DNA load at 4 weeks of follow-up and clearance of JCV-DNA from CSF are associated with a better neurologic outcome and a longer survival.

AIDS-Related Opportunistic Infections↗
PubMed2001

Potent anti-retroviral therapy with or without cidofovir for AIDS-associated progressive multifocal leukoencephalopathy: extended follow-up of an observational study.

To analyze the clinical efficacy of cidofovir combined with highly active anti-retroviral therapy (HAART) in AIDS-related progressive multifocal leukoencepalopathy (PML), a multicenter observational study was performed. Consecutive HIV-positive patients with histologically or virologically proven PML and at least 4 weeks of treatment after diagnosis were examined: 27 patients were treated with HAART, whereas 16 patients were treated with HAART plus cidofovir 5 mg/kg intravenously per week for the first 2 weeks and every other week thereafter. JC virus DNA was quantified in cerebrospinal fluid (CSF) by PCR. Baseline virologic, immunologic, and clinical characteristics as well as HIV RNA and CD4 responses to HAART were homogeneous between the groups. The median follow-up was 132 weeks. In one case (6%), cidofovir was permanently discontinued because of severe proteinuria. One-year cumulative probability of survival was 0.61 with cidofovir and 0.29 without (log rank test P = 0.02). After adjusting for baseline CD4 counts, JC viral load in CSF, Karnofsky, and use of HAART prior to the onset of PML, the use of cidofovir was independently associated with a reduced risk of death (hazard ratio, 0.21, 95% confidence interval, 0.07-0.65; P = 0.005). A randomized study will definitively establish whether cidofovir confers significant advantage over HAART alone in AIDS-related PML.

AIDS-Related Opportunistic Infections↗
PubMed2001

Designs for clinical trials to test the efficacy of therapeutics in progressive multifocal leukoencephalopathy.

The design of a comparative treatment trial to evaluate the efficacy of therapeutics for progressive multifocal leukoencephalopathy (PML) is outlined. We propose a large simple randomized trial with patient survival as its primary endpoint, completed in a short period of time and involving a cohort with as few enrollment restrictions as possible. We use stratification as the counterweight to the lack of exclusion criteria and suggest that proper stratification will attenuate differences inherent in a heterogeneous subject cohort. Estimation of power, sample size, and study duration, implementation of interim analyses, toxicity management, and validation of secondary clinical measures are also addressed.

Antiviral Agents↗
PubMed2001

Mechanism of block of single protopores of the Torpedo chloride channel ClC-0 by 2-(p-chlorophenoxy)butyric acid (CPB).

We investigated in detail the mechanism of inhibition by the S(-) enantiomer of 2-(p-chlorophenoxy)butyric acid (CPB) of the Torpedo Cl(-)channel, ClC-0. The substance has been previously shown to inhibit the homologous skeletal muscle channel, CLC-1. ClC-0 is a homodimer with probably two independently gated protopores that are conductive only if an additional common gate is open. As a simplification, we used a mutant of ClC-0 (C212S) that has the common gate "locked open" (Lin, Y.W., C.W. Lin, and T.Y. Chen. 1999. J. Gen. Physiol. 114:1-12). CPB inhibits C212S currents only when applied to the cytoplasmic side, and single-channel recordings at voltages (V) between -120 and -80 mV demonstrate that it acts independently on individual protopores by introducing a long-lived nonconductive state with no effect on the conductance and little effect on the lifetime of the open state. Steady-state macroscopic currents at -140 mV are half-inhibited by approximately 0.5 mM CPB, but the inhibition decreases with V and vanishes for V > or = 40 mV. Relaxations of CPB inhibition after voltage steps are seen in the current responses as an additional exponential component that is much slower than the gating of drug-free protopores. For V = 60 mV) with an IC50 of approximately 30-40 mM. Altogether, these findings support a model for the mechanism of CPB inhibition in which the drug competes with Cl(-) for binding to a site of the pore where it blocks permeation. CPB binds preferentially to closed channels, and thereby also strongly alters the gating of the single protopore. Since the affinity of CPB for open WT pores is extremely low, we cannot decide in this case if it acts also as an open pore blocker. However, the experiments with the mutant K519E strongly support this interpretation. CPB block may become a useful tool to study the pore of ClC channels. As a first application, our results provide additional evidence for a double-barreled structure of ClC-0 and ClC-1.

Animals↗
PubMed2001

Skeletal muscle disuse induces fibre type-dependent enhancement of Na(+) channel expression.

Slow-twitch and fast-twitch muscle fibres have specific contractile properties to respond to specific needs. Since sodium current density is higher in fast-twitch than in slow-twitch fibres, sodium channels contribute to the phenotypic feature of myofibres. Phenotype determination is not irreversible: after periods of rat hindlimb unloading (HU), a model of hypogravity, a slow-to-fast transition occurs together with atrophy in the antigravity slow-twitch soleus muscle. Using cell-attached patch-clamp and northern blot analyses, we looked at sodium channel expression in soleus muscles after 1-3 weeks of HU in rats. We found that sodium channels in fast-twitch flexor digitorum brevis muscle fibres, soleus muscle fibres and 1- to 3-week HU soleus muscle fibres showed no difference in unitary conductance, open probability and voltage-dependencies of activation, fast inactivation and slow inactivation. However, muscle disuse increased sodium current density in soleus muscle fibres 2-fold, 2.5-fold and 3-fold after 1, 2 and 3 weeks of HU, respectively. The concentration of mRNA for the skeletal muscle sodium channel alpha subunit increased 2-fold after 1 week of HU but returned to the control level after 3 weeks of HU. In contrast, the concentration of mRNA for the ubiquitous sodium channel beta(1) subunit was unchanged after 1 week and had increased by 30% after 3 weeks of HU. The tetrodotoxin sensitivity of sodium currents in 3-week HU soleus muscles and the lack of mRNA signal for the juvenile skeletal muscle sodium channel alpha subunit excluded denervation in our experiments. The observed increase in sodium current density may reduce the resistance to fatigue of antigravity muscle fibres, an effect that may contribute to muscle impairment in humans after space flight or after long immobilization.

Animals↗