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Biomedical subjects

A De Luca

Publications and source records attributed to A De Luca.

At least 145 records · Page 8Linked to original sources
PubMed1998

Cloning of murine CDK9/PITALRE and its tissue-specific expression in development.

The cdc2-family of serine/threonine kinases and their binding partners recently were implicated in developmental roles. We previously cloned a cdc2-related kinase, cdk9/PITALRE, that is able to phosphorylate the retinoblastoma protein in vitro. We describe here the cloning and the characterization of the mouse homolog of cdk9/PITALRE. The murine cDNA is 98% identical with humans and is expressed at high levels in brain and kidney tissues. The kinase activity and protein expression of cdk9/PITALRE were highest in terminally differentiated tissues such as the muscle and brain. In situ immunohistology and immunofluorescence detected cdk9/PITALRE protein not only within terminally differentiated cells such as muscle and neuronal cells, but also in proliferating cells. C2C12 and P19 cells induced to differentiate along muscle and neural lineages peaked in cdk9/PITALRE kinase activity at the end of differentiation. These results suggest that, among other roles, cdk9/PITALRE plays a role not unlike cdk5 in the differentiation of certain cell types.

Amino Acid Sequence↗
PubMed1998

Helicobacter pylori eradication ameliorates primary Raynaud's phenomenon.

Raynaud's phenomenon is defined by an intermittent vasospasm of the arterioles of the distal limbs. Helicobacter pylori infection has been recently associated with Raynaud's phenomenon. The aim of this study was to assess the effects of H. pylori eradication on Raynaud's attacks. Forty-six patients affected by primary Raynaud's phenomenon were evaluated. H. pylori infection was assessed by [13C]urea breath test. Eradication therapy was given to infected patients for seven days. Discomfort and the duration and frequency of attacks of Raynaud's phenomenon per week were assessed. Thirty-six subjects were infected with H. pylori; the bacterium was eradicated in 83% of these after therapy. Attacks of Raynaud's phenomenon completely disappeared in 17% of the patients with H. pylori eradication. Discomfort and the duration and frequency of attacks of Raynaud's phenomenon were significantly reduced in 72% of the remaining patients. Conversely, attacks of Raynaud's disease did not change significantly during the 12-week follow-up period either in the H. pylori-negative patients or in the infected subjects in whom the bacterium was not eradicated by therapy. The study shows that H. pylori eradication causes a significant decrease in clinical attacks of Raynaud's disease. The reduction of vasoactive substances determined by the eradication of the bacterium may be the pathogenetic mechanism underlying the phenomenon.

Adult↗
PubMed1998

Phosphorylation and IGF-1-mediated dephosphorylation pathways control the activity and the pharmacological properties of skeletal muscle chloride channels.

1. In the present study we tested the hypothesis that insulin-like growth factor-1 (IGF-1) modulates resting chloride conductance (G(Cl)) of rat skeletal muscle by activating a phosphatase and that the chloride channel, based on the activity of phosphorylating-dephosphorylating pathways, has different sensitivity to specific ligands, such as the enantiomers of 2-(p-chlorophenoxy) propionic acid (CPP). 2. For this purpose G(Cl) in EDL muscle isolated from adult rat was first lowered by treatment with 5 nM 4-beta-phorbol 12,13 dibutyrate (4-beta-PDB), presumably activating protein kinase C (PKC). The effects of IGF-1 and of the enantiomers of CPP on G(Cl) were then tested. 3. IGF-1 (3.3 nM) had no effect of G(Cl) on EDL muscle fibres in normal physiological solution, whereas it completely counteracted the 30% decrease of G(Cl) induced by 4-beta-PDB. No effects of IGF-1 were observed on G(Cl) lowered by the phosphatase inhibitor okadaic acid (0.25 microM). 4. Ceramide, reported to activate on okadaic acid-sensitive phosphatase, mimicked the effects of IGF-1. In fact, N-acetyl-sphingosine (2.5-5 microM), not very effective in control conditions, increased the G(Cl) lowered by the phorbol ester, but not the G(Cl) lowered by okadaic acid. 5. In the presence of 4-beta-PDB, G(Cl) was differently affected by the enantiomers of CPP. The S(-)-CPP was remarkably less potent in producing the concentration-dependent reduction of G(Cl), whereas the R(+)-CPP caused an increase of G(Cl) at all the concentrations tested. 6. In conclusion, the PKC-induced lowering of G(Cl) is counteracted by IGF-1 through an okadaic acid sensitive phosphatase, and this effect can have therapeutic relevance in situations characterized by excessive channel phosphorylation. In turn the phosphorylation state of the channel can modulate the effects and the therapeutic potential of direct channel ligands.

Animals↗
PubMed1998

Helicobacter pylori infection in patients affected by insulin-dependent diabetes mellitus.

BACKGROUND/AIM: Insulin-dependent diabetes mellitus (IDDM) is the result of an autoimmune destruction of pancreatic Langerhans beta cells. Helicobacter pylori infection, the most common cause of gastritis and peptic ulcer, has been associated with some autoimmune diseases. The aim of this study was to evaluate the prevalence of H. pylori infection and gastrointestinal (GI) symptoms in patients with IDDM. METHODS: 116 patients (50 males and 66 females, mean age: 35 +/- 11 years) affected by IDDM were evaluated; 50 healthy subjects matched for age and sex were utilized as a control group. H. pylori infection was determined by a [13C]urea breath test. IDDM duration, daily dosage of insulin and prevalence of GI symptoms (bloating, pyrosis, epigastric pain, belching, halitosis, nausea) were assessed. RESULTS: The prevalence of H. pylori infection was similar in IDDM patients and in controls (37 vs 34%, respectively). In both groups, the mean age was higher in infected subjects. The mean IDDM duration was significantly greater in infected patients (19 +/- 12 vs 13 +/- 10 years, P < 0.006). Prevalence of infection was directly related to the duration of IDDM (<1 year, 23%; 1-3 years, 32%; >3 years, 40%). The daily dosage of insulin did not differ between infected and non-infected subjects. H. pylori contaminated patients showed a significantly higher prevalence of bloating, pyrosis and epigastric pain when compared with non-infected subjects; conversely, prevalence of belching, halitosis and nausea did not differ between groups. CONCLUSION: The prevalence of H. pylori infection is high in patients affected by IDDM; however, it does not differ from the infection rate observed in a control group. The rate of infection increases with IDDM duration. Bloating, pyrosis and epigastric pain appear to define infection status better.

Adult↗
PubMed1998

Routine use of PCR-reverse cross-blot hybridization assay for rapid identification of Mycobacterium species growing in liquid media.

A PCR-reverse cross-blot hybridization assay procedure that is able to rapidly identify 13 species of clinically relevant mycobacteria was evaluated for routine use in the identification of acid-fast isolates growing in BACTEC 460 TB (12B and 13A) and BACTEC 9000 MB (Myco/F) liquid media. Eight of the probes used were already described by Kox et al. (L. F. F. Kox et al., J. Clin. Microbiol. 33:3225-3233, 1995). In addition, we used six other probes specific for M. chelonae, M. malmoense or M. szulgai, M. genavense, M. gordonae, M. terrae, and M. marinum/M. ulcerans that we designed ourselves. This procedure allowed us to identify 459 mycobacterial species directly from broth cultures of 5,466 clinical samples collected over 1 year and processed with the radiometric or nonradiometric BACTEC system. Our results were in agreement with those obtained by conventional identification methods and also with those obtained by mycolic acid analysis by high-performance liquid chromatography. This assay seems to be a reliable procedure for the routine identification of mycobacteria, providing an accurate identification of mycobacterial isolates more rapidly than conventional tests, with remarkable implications for an efficacious specific antimycobacterial therapy.

Chromatography, High Pressure Liquid↗
PubMed1998

Blockade by cAMP of native sodium channels of adult rat skeletal muscle fibers.

Although the skeletal muscle sodium channel is a good substrate for cAMP-dependent protein kinase (PKA), no functional consequence was observed for this channel expressed in heterologous systems. Therefore, we investigated the effect of 8-(4-chlorophenylthio)adenosine 3',5'-cyclic monophosphate (CPT-cAMP), a membrane-permeable cAMP analog, on the native sodium channels of freshly dissociated rat skeletal muscle fibers by means of the cell-attached patch-clamp technique. Externally applied CPT-cAMP (0.5 mM) reduced peak ensemble average currents by approximately 75% with no change in kinetics. Single-channel conductance and normalized activation curves were unchanged by CPT-cAMP. In contrast, steady-state inactivation curves showed a reduction of the maximal available current and a negative shift of the half-inactivation potential. Similar effects were observed with dibutyryl adenosine 3',5'-cyclic monophosphate but not with cAMP, which does not easily permeate the cell membrane. Incubation of fibers for 1 h with 10 microM H-89, a PKA inhibitor, did not prevent the effect of CPT-cAMP. Finally, the beta-adrenoreceptor agonist isoproterenol mimicked CPT-cAMP when applied at 0.5 mM but had no effect at 0.1 mM. These results indicate that cAMP inhibits native skeletal muscle sodium channels by acting within the fiber, independently of PKA activation.

Adrenergic beta-Agonists↗
PubMed1998

p21waf1/cip1mda-6 expression in non-small-cell lung cancer: relationship to survival.

In order to clarify critical events during bronchial carcinogenesis, and to evaluate a possible prognostic role for p21 immunohistochemical detection, we assessed the immunohistochemical expression of p21 protein in 60 surgically resected non-small-cell lung cancers (NSCLCs) that had been investigated previously for their p53 protein status. We found that p21 protein was expressed in both normal and neoplastic tissue. In normal tissue, p21 immunoreactivity was detectable in a low percentage of well-differentiated cells. We found immunostaining for p21 in 80% of the investigated neoplasms. In 73.3% of the neoplasms, p21 was considered to be overexpressed. No relationship was found between p21 overexpression and tumor stage or tumor-nodal-metastatic (TNM) status. The histologic grading was slightly correlated with the p21 status (P = -0.51), with no significant differences noted between squamous carcinomas and adenocarcinomas. Survival percentage curves for our lung-cancer patients, based on a comparison of different p21 expression levels and constructed through a Kaplan-Meier analysis, showed significant differences in mean (P < 0.001) and overall (P < 0.001) survival time between patients of different p21 status, suggesting a favorable prognostic value of p21 immunostaining for NSCLC patients.

Adenocarcinoma↗
PubMed1998

Apolipoprotein A-I reverse transcriptase-polymerase chain reaction analysis for detection of hematogenous colon cancer dissemination.

Detection of systemic tumor dissemination in colon carcinoma patients might be important for selection of appropriate treatment modalities. It has been previously shown that Apolipoprotein A-I (Apo A-I) is expressed in human intestinal epithelial cells, and in some human colon carcinoma cell lines. We examined the expression of Apo A-I mRNA in 14 human primary colon carcinomas by Northern blot and/or reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. An Apo A-I specific transcript was found in up to 70% of the colon carcinomas. We developed an RT-PCR assay for Apo A-I transcripts, to identify circulating carcinoma cells in the peripheral blood of colon cancer patients. The Apo A-I RT-PCR assay was optimized using limiting dilution of an Apo A-I positive cancer cell line mixed with peripheral blood from healthy donor. In this system, up to 10 colon carcinoma cells were detected in 5 ml of peripheral blood. We examined Apo A-I mRNA expression in peripheral blood samples from 4 healthy donors, 20 colon carcinoma patients, and 11 individuals with tumor disease other than colon cancer. No Apo A-I mRNA was detected in the healthy donors and in the patients without colon cancer. Two out of 10 patients with metastatic colon carcinoma were positive by this assay, whereas Apo A-I mRNA was not found in any of the blood samples from the 10 radically resected colon carcinoma patients. These data suggest that Apo A-I RT-PCR assay is a highly specific and sensitive assay, although a low number of advanced colon carcinoma patients was found to be positive.

Apolipoprotein A-I↗
PubMed1998

Nucleotide fractional incorporation: a simple metabolic feature potentially related to clinical outcome in colorectal cancer patients.

Among the different investigated biomarkers, cell proliferation has provided valuable information on the clinical outcome of patients with malignant tumors. In the present study, we analyzed the potential relevance of fractional incorporation (FI) of a nucleotide precursor (3H-thymidine, 3H-dT) into DNA of tumor cells, determined on the primary tumor, on long-term clinical outcome of a series of patients with colorectal cancer. Determination of 3H-dT FI was carried out on fresh tumor material obtained at surgery as part of the clinical management of the primary tumor in 28 patients with colorectal cancer. Analysis of the relation between the FI and clinico-pathological characteristics of the tumor showed a trend of an inverse relation between the biomarker and Dukes' stage and no relation with tumor site. At 6 year follow-up, alive patients had a statistically significant higher median FI value (2.4%; range: 1.1-6.5%) than dead patients (1%; range: 0.3-4.5%) (p=0.02). Owing to the simplicity of this inexpensive methodology, the preliminary results of our study would indicate the potential of FI, a metabolic-kinetic parameter, to give prognostic information in colorectal cancer patients.

Colorectal Neoplasms↗
PubMed1998

Potential targets for skeletal muscle impairment by hypogravity: basic characterization of resting ionic conductances and mechanical threshold of rat fast- and slow-twitch muscle fibers.

Prolonged hypogravity such as during space flights affects skeletal muscle function by inducing postural changes as well as reduced muscle strength and locomotion capacity. Also in rats, space flight as well as useful models of groundbased hypogravity induce marked atrophy in the slow-twitch soleus (SOL) muscle as opposed to slight or none in the fast-twitch ones such as extensor digitorum longus (EDL). Biochemical and histological studies on hindlimb suspended animals, showed a hypogravity-induced impairment of muscle function involving the transition of slow-twitch muscle type, responsible for postural control, toward the fast-twitch phenotype by modification of excitation-contraction pattern. In slow muscles of rats, hindlimb suspension induced upregulation of the fast isoform of myosin heavy-chain and increased expression of fast Ca2+ pump mRNA and protein, which is consistent with the increased Ca(2+)-dependent ATPase activity and the speeding of muscle relaxation, typical of fast muscles. Little is known about the modifications induced by hypogravity in the sarcolemmal ion channels function, which controls the pattern of muscle excitability and contractility. The normally high resting chloride conductance, which is required for the electrical stabilization of mammalian muscle fibers, may be a target of hypogravity modifications since a pharmacological block of this parameter determines, though an increase of excitability, the transition of the fast-twitch muscle phenotype toward the slow one either in adult or in developing rats. Hypogravity also induced increased expression of dihydropyridine receptors in soleus muscle, that are normally lower than that found in the fast ones. In this study, we characterized the electrical and contractile properties of rat extensor digitorum longus (EDL) and slow-twitch soleus SOL muscles fibers at the aim to better understand the molecular mechanisms leading to fiber transition.

Animals↗
PubMed1998

Comparison of excitability parameters and sodium channel behavior of fast- and slow-twitch rat skeletal muscles for the study of the effects of hindlimb suspension, a model of hypogravity.

When mammals are constrained to hypogravity, their neuromuscular apparatus undergoes modifications which rend difficult postural maintenance and muscular activity upon the return to normal gravitational conditions. Muscle atrophy and differetial gene expression are particularly evident in slow-twitch antigravity muscles such as the soleus. During hypogravity, most of the metabolic and contractile properties characteristic of slow-twitch muscles shift toward to those of fast-twitch muscles. For example, the expression of the fast isoforms of both the myosin heavy-chain and the sarcoplasmic reticulum calcium pump increases in slow-twitch muscle during hypogravity. Thus, modifications of the contractile machinery and calcium handling are likely to be involved in the hypogravity-induced slow-twitch muscle impariment. Fast- and slow-twitch muscles differ also in their electrical properties. Resting membrane potential (RMP) is more negative by about 10 mV in fast muscles compared to slow ones. Differences in action potential (AP) shape as well as in the number of elicitable APs have been also observed between both muscle types, which may reslut from the reported differences in chloride conductance and sodium current. Little is known about the potential modification fo muscle electrical properties during hypogravity, apart a negative shift of the RMP in soleus muscle. Thus this study was performed at the aim to compare the excitability parameters and sodium channel behavior of rat fast-twitch and slow-twitch muscle fibers. The characterization of these properties specific for each muscle-type will give us the basis for the study of the effect of hypogravity.

Action Potentials↗
PubMed1998

Epidermal growth factor-related peptides as targets for experimental therapy of human colon carcinoma.

Colorectal carcinomas generally show a poor sensitivity to conventional chemotherapeutics. Therefore, novel therapeutic approaches are required to improve the prognosis of colon cancer patients in advanced stage. Several growth factors are involved in the control of colon carcinoma cell proliferation. In particular, the epidermal growth factor (EGF)-related peptides transforming growth factor-alpha (TGF-alpha), amphi-regulin (AR), and CRIPTO (CR) are frequently overexpressed in human colon carcinomas. It has also been recently demonstrated that they can function as autocrine growth factors in human colon carcinoma cells. In fact, antisense (AS) retroviral expression vectors or AS oligonucleotides directed against TGF-alpha, AR, or CR are able to inhibit growth and transformation of several human colon carcinoma cell lines. These data suggest that the EGF-like growth factors and their receptors offer potential as targets for experimental therapy of human colon carcinoma. This article reviews the most recent findings in this field.

Animals↗
PubMed1998

Partial recovery of skeletal muscle sodium channel properties in aged rats chronically treated with growth hormone or the GH-secretagogue hexarelin.

This study was aimed at investigating the effects of chronic treatment of aged rats with growth hormone (GH, 8 weeks) or the GH-secretagogue hexarelin (4 weeks) on the biophysical modifications that voltage-gated sodium channels of skeletal muscle undergo during aging, by means of the patch-clamp technique applied to fast-twitch muscle fibers. Two phenotypes of aged-rat fibers could be discriminated on the basis of channel conductance. In the young phenotype, sodium channels present a conductance of 18 pS as in young-adult rats. In the aged phenotype, channels present a conductance of 9 pS while ensemble average currents activate and inactivate more slowly. Nevertheless, in all situations, sodium channels shared a number of biophysical properties, such as open probability, mean open time, steady-state inactivation and use-dependent inhibition. Furthermore, channel density on extrajunctional sarcolemma was higher in aged rats, a result independent of the phenotype. Chronic treatment of aged rats with either GH or hexarelin restored current kinetics but not channel conductance and density. These results confirm the specific age-related changes in sodium channel behavior and show that treatment with either GH or hexarelin has partial restorative effects. Moreover, hexarelin restored the firing capacity of fast-twitch muscle fibers, as did GH in previous studies. These findings support the possible therapeutic value of the synthetic peptide in cases of GH deficiency, as in the elderly.

Aging↗
PubMed1998

Chronic administration of taurine to aged rats improves the electrical and contractile properties of skeletal muscle fibers.

A reduction of resting chloride conductance (GCl) and a decrease of the voltage threshold for contraction are observed during aging in rat skeletal muscle. The above alterations are also observed in muscle of adult rat after taurine depletion. As lower levels of taurine were found by others in aged rats compared to young rats, we tested the hypothesis that a depletion of taurine may contribute to the alteration of the electrical and contractile properties we found in skeletal muscle during aging. This was accomplished by evaluating the potential benefit of a pharmacological treatment with the amino acid. To this aim 25-mo-old Wistar rats were chronically treated (2-3 mo) with taurine (1 g/kg p.o. daily) and the effects of such a treatment were evaluated in vitro on the passive and active membrane electrical properties of extensor digitorum longus muscle fibers by means of current-clamp intracellular microelectrode technique. Excitation-contraction coupling was also evaluated by measuring the voltage threshold for contraction with the intracellular microelectrode "point" voltage clamp method. In parallel muscle and blood taurine contents were determined by high-performance liquid chromatography. Taurine supplementation significantly raised taurine content in muscle toward that found in adult rats. Supplementation also significantly increased GCl vs. the adult value, in parallel the excitability characteristics (threshold current and latency) related to this parameter were ameliorated. The increase of GCl induced by taurine was accompanied by a restoration of the pharmacological sensitivity to the R(+) enantiomer of 2-(p-chlorophenoxy) propionic acid, a specific chloride channel ligand. In parallel also the protein kinase C-mediated modulation of the channel was restored; in fact the potency of 4-beta-phorbol 12, 13-dibutyrate in reducing GCl was lower in taurine-treated muscles vs. untreated aged, being rather similar to that observed in adult. The treatment also improved the mechanical threshold for contraction of striated fibers which in aged rats is shifted toward more negative potentials, moving it toward the adult values. Our results suggest that the reduction of taurine content could play a role in the alteration of electrical and contractile properties observed during aging. These findings may indicate a potential application of taurine in ensuring normal muscle function in the elderly.

Aging↗
PubMed1998

Simian virus 40-like DNA sequences and large-T antigen-retinoblastoma family protein pRb2/p130 interaction in human mesothelioma.

The oncoprotein of the Simian virus 40, SV40 large T-antigen (Tag), is reported to target and inactivate growth-suppressive proteins such as the retinoblastoma (Rb) family and p53 leading to transformation of human cell lines in vitro, to produce tumours in rodents, and to be detected in several human cancers including mesothelioma. In support of the potential role of SV40 Tag in the pathogenesis of certain human cancers, we have found SV40-like sequences in 8/25 bioptic specimens of mesothelioma from patients with exposure to asbestos fibres. We have also demonstrated that the SV40 Tag detected in human mesothelioma binds the retinoblastoma family protein pRb2/p130 in 5/5 specimens studied. We submit that the tumorigenic potential of SV40 Tag in some human mesotheliomas may arise from its ability to interact with and thereby inactivate several tumour and/or growth suppressive proteins in cooperation with asbestos fibres in inducing pleural mesothelioma.

Aged↗