Biomedical subjects

V Covelli

Publications and source records attributed to V Covelli.

At least 19 recordsLinked to original sources

PubMed2006

Two-hit model for progression of medulloblastoma preneoplasia in Patched heterozygous mice.

Inactivation of one Ptc1 allele predisposes humans and mice to spontaneous medulloblastoma development, and irradiation of newborn Ptc1 heterozygous mice results in dramatic increase of medulloblastoma incidence. While a role for loss of wild-type (wt) Ptc1 (LOH) in radiation-induced medulloblastomas from Ptc1(neo67/+) mice is well established, the importance of this event in spontaneous medulloblastomas is still unclear. Here, we demonstrate that biallelic Ptc1 loss plays a crucial role in spontaneous medulloblastomas, as shown by high rate of wt Ptc1 loss in spontaneous tumors. In addition, remarkable differences in chromosomal events involving the Ptc1 locus in spontaneous and radiation-induced medulloblastomas suggest distinct mechanisms for Ptc1 loss. To assess when, during tumorigenesis, Ptc1 loss occurs, we characterized cerebellar abnormalities that precede tumor appearance in Ptc1(neo67/+) mice. We show that inactivation of only one copy of Ptc1 is sufficient to give rise to abnormal cerebellar proliferations with different degree of altered cell morphology, but lacking potential to progress to neoplasia. Furthermore, we identify biallelic Ptc1 loss as the event causally related to the transition from the preneoplastic stage to full blown medulloblastoma. These results underscore the utility of the Ptc1(neo67/+) mouse model for studies on the mechanisms of medulloblastoma and for development of new therapeutic strategies.

Aging↗

PubMed2006

Linking DNA damage to medulloblastoma tumorigenesis in patched heterozygous knockout mice.

Hemizygous Ptc1 mice have many features of Gorlin syndrome, including predisposition to medulloblastoma development. Ionizing radiation synergize with Ptc1 mutation to induce medulloblastoma only in neonatally exposed mice. To explore the mechanisms underlying age-dependent susceptibility, we irradiated Ptc(neo67/+) mice at postnatal day 1 (P1) or 10 (P10). We observed a dramatic difference in medulloblastoma incidence, which ranged from 81% in the cerebellum irradiated at P1 to 3% in the cerebellum irradiated at P10. A striking difference was also detected in the frequency of cerebellar preneoplastic lesions (100 versus 14%). Our data also show significantly lower induction of apoptosis in the cerebellum of medulloblastoma-susceptible (P1) compared to -resistant (P10) mice, strongly suggesting that medulloblastoma formation in Ptc1 mutants may be associated with resistance to radiation-induced cell killing. Furthermore, in marked contrast with P10 mice, cerebellum at P1 displays substantially increased activation of the cell survival-promoting Akt/Pkb protein, and markedly decreased p53 levels in response to radiation-induced genotoxic stress. Overall, these results show that developing cerebellar granule neuron precursors' (CGNPs) radiosensitivity to radiation-induced cell death increases with progressing development and inversely correlates with their ability to neoplastically transform.

Allelic Imbalance↗

PubMed2006

New insights into the biological and clinical significance of fecal calprotectin in inflammatory bowel disease.

Nowadays, calprotectin, a cytoplasmatic protein, released by activated neutrophilic polymorphonuclear cells (PMN) and/or monocytes-macrophages (MØ), is considered a good indicator of inflammation in several diseases. Accordingly, fecal calprotectin represents a good predictor of clinical relapse in ulcerative colitis (UC) patients, whereas conflicting results have been reported in Crohn's disease (CD) patients. In our study, in 76 IBD patients (29 CD and 47 UC) fecal calprotectin has been evaluated by a commercial ELISA kit. Results demonstrate that levels of this protein in the stool are significantly more elevated in active CD and UC patients than in normal volunteers. In quiescent CD and UC a trend to higher levels of calprotectin than in the normal counterpart is, however, evident. These data suggest that a low-grade inflammation of the intestinal wall is always present in CD and UC patients, which may predict a clinical relapse risk. In the same group of patients calprotectin levels also were analyzed according to sex and age. A trend to higher values of calprotectin was present in male patients with active or quiescent CD than in their female counterparts. Only in UC patients in remission a trend to calprotectin increase was more marked in the male group than in the female counterpart. When CD and UC patients were divided up according to age, calprotectin positivity peaked between 30-39 years in active CD patients, while in quiescent CD maximum positivity was between 40 and 49 years. However, in both active and quiescent UC patients, calprotectin positivity increased with age. The more precocious detectability of fecal calprotectin in CD patients, as a marker of intestinal mucosa inflammation, may be related to the different histopathology of the two diseases (CD versus UC). However, reduced PMN and/or MØ trafficking from peripheral blood to intestinal mucosa with age by effects of chronic treatment should not be ignored in CD patients.

Adolescent↗

PubMed2006

Taking advantage of viral immune evasion: virus-derived proteins represent novel biopharmaceuticals.

In healthy individuals, natural and adaptive immune responses are able to control virus entry into the host. In particular, CD8(+)-mediated cytotoxicity, sustained by the intervention of CD4+ cells, represents the major key event leading to virus eradication. On the other hand, viruses are able to evade from host immune response via several mechanisms, and special emphasis will be placed on hepatitis C virus and chronic Epstein-Barr infections also in view of personal data. Virokines, viroreceptors, and serpins greatly contribute to viral immune escape, and, among virokines, interleukin (IL)-10 has been object of intensive studies. Finally, all these products have been used as biopharmaceuticals, and, for instance, viral IL-10, chemokine-binding proteins, and serpins exhibit in animal models immunosuppressive, anti-inflammatory, and antiatherogenic activities. As far as their use in human trials is concernded, many cautions are required in order to avoid deleterious side effects and, in particular, the purity of the product, its route and frequency of administration, as well as the immune status of the patient should be taken into serious account.

Antiviral Agents↗

PubMed2006

Involvement of the transforming growth factor beta in the pathogenesis of hereditary hemorrhagic telangiectasia.

Hereditary hemorrhagic telangiectasia (HHT) is characterized by vessel alterations such as dilatation of postcapillary venules and arterio-venous communications, which account for the major clinical manifestations of the disease. Two types of HHT have been characterized HHT-1 and HHT-2, respectively, depending the former on endoglin mutations and the latter on activin receptor-like kinase 1 (ALK-1) mutations. Both endoglin and ALK-1 bind to the transforming growth factor (TGF) superfamily which, physiologically, regulates the activities of endothelial cells and also those related to the extracellular matrix. In this review, the salient features of TGF-beta will be outlined with special reference to its activity on the immune system and on tumorigenesis. Furthermore, the involvement of TGF-beta in the pathogenesis of some gastrointestinal diseases will be discussed and, in particular, in the course of liver disease, Helicobacter pylori infection and inflammatory bowel disease. In the light of these data and of animal model of HHT, the potential risk of developing other diseases in HHT patients will be discussed.

Gastrointestinal Diseases↗

PubMed2003

A point of view: The need to identify an antigen in psyconeuroimmunological disorders.

Several lines of evidence support a mutual relationship between the nervous system and the immune system. Therefore, it is not surprising that some neuropsychiatric disorders are also characterized by immune abnormalities. In patients with phobic disorders and in patients with migraine without aura some common immune abnormalities have been detected and, in particular, natural immunity deficits, exaggerated release of proinflammatory cytokines and circulating bacterial endotoxins have been found. In other neurological disease, some etiologic factors have been detected as in the case of Guillain-Barrè syndrome in which molecular mimicry between Campylobacter jejuni endotoxin and GM1 ganglioside may cause an acute inflammatory polyneuropathy. On the other hand, attempts to identify an antigen have been made in patients with Alzheimer's disease and schizophrenia. Finally, the chronic fatigue syndrome, an old illness in search for an antigen, risk factors and precipitating agents have been described but evidence for a specific antigen is still lacking.

Antigens↗

PubMed2003

Nutrition and immunity: laboratory and clinical aspects.

It is well known that inappropriate nutrient intake accounts for the maintenance of the immunological equilibrium, in humans and animals. Vitamins, elements, lipids, proteins and nucleic acids play an important role in the regulation of cellular and humoral immune responses since single or multiple deficits of these food components have been shown to cause immune abnormalities. For instance, in the course of protein-calorie malnutrition bacterial and/or viral infections represent the major cause of death. Ageing is characterized by a decline of many immune functions, and this process is called immunosenescence. Here, we report novel findings on the inability of superantigens to activate old CD8+, natural killer and B cells, as an expression of cell amnesia. In the elderly, this lack of activation could lead to lethal effects in the case of severe staphylococcal infections. Quite interestingly, recent findings outlined some similarities between human immune deficiency virus (HIV)-1 infection and ageing in terms of immune changes. The model of HIV-infection may be useful for the interpretation of ageing mechanisms and possible therapeutical interventions. Finally, the role of nutrition in different pathological conditions and the use of medical foods for correcting of immune deficits will be described.

Aging↗

PubMed2001

Analysis of c-Ha-ras gene mutations in skin tumors induced in carcinogenesis-susceptible and carcinogenesis-resistant mice by different two-stage protocols or tumor promoter alone.

In the present study we describe the molecular analysis of c-Ha-ras gene mutations in 47 papillomas and 17 carcinomas developed in two lines of mice, carcinogenesis-susceptible (Car-S) and carcinogenesis-resistant (Car-R), selectively bred for extreme susceptibility or resistance to chemical skin carcinogenesis initiated and promoted with different doses of 7,12-dimethylbenz[a]anthracene (DMBA) and 12-O-tetradecanoylphorbol-13-acetate (TPA). This study also presents the analysis of c-Ha-ras gene mutations in 22 papillomas and 22 carcinomas in Car-S mice initiated with DMBA and promoted with benzoyl peroxide (BzPo) and in seven papillomas and one carcinoma from a group of uniniated Car-S mice that received only BzPo treatment. The data showed that a A(182)-->T transversion in the c-Ha-ras gene was present in 100% and 81% of the skin tumors developed in Car-S and Car-R mice, respectively, after DMBA initiation and TPA promotion, suggesting that differences in genetic susceptibility can influence the frequency of c-Ha-ras mutations in the skin tumors produced. The same A(182)-->T mutation with an incidence of 68% was found in papillomas from DMBA-initiated and BzPo-promoted Car-S mice. The difference in the mutation frequency between DMBA/BzPo and DMBA/TPA papillomas suggested that the promotion step contributes to the final mutation pattern. The tumor induction experiment with BzPo alone showed that this compound can induce tumor development in 26% of Car-S mice, and the molecular analysis of the tumors showed a broad mutation spectrum, including mutations in codons 12, 13, and 61 of the c-Ha-ras gene. Mol. Carcinog. 30:111-118, 2001.

Animals↗

PubMed2001

Use of intercross outbred mice and single nucleotide polymorphisms to map skin cancer modifier loci.

Car-R and Car-S outbred mouse lines, phenotypically selected for resistance and susceptibility to skin carcinogenesis respectively, show significant linkage disequilibrium (LD) at genetic markers mapping on chromosomal regions where skin cancer modifier loci (Skts3, Skts1, and Psl1 on Chrs 5, 7, and 9 respectively) have been mapped in standard crosses. Analysis of these regions for genetic linkage with skin cancer phenotypes in 245 (Car-R x Car-S)F2 intercross mice, by using single nucleotide polymorphisms (SNPs), revealed significant linkage at a possible allelic form of the Skts1 locus, whose mapping region was shortened to a <5.5-cM interval near the Tyr locus. The Car-derived Skts1 locus was linked with papilloma multiplicity and latency by a recessive inheritance of the susceptibility allele. Putative loci on Chr 5 (Skts3) and 9 (Psl1) showed no significant linkage. These results point to the important role of the Stks1 locus in mouse skin tumorigenesis in independent crosses. The shortened Skts1 mapping region should facilitate the identification of candidate genes.

Animals↗

PubMed2001

In vitro effects of naloxone on T-lymphocyte-dependent antibacterial activity in hepatitis C virus (HCV) infected patients and in inflammatory bowel disease (IBD) patients.

Naloxone acts as an opioid antagonist, displacing opioid drugs from cellular receptors. Among opioid substances, beta-endorphins are able to bind to several cell receptors, even including those expressed by immune cells. In this respect, evidence has been provided that in the course of viral infections, as well as in patients with ulcerative colitis high levels of beta-endorphins are detectable. Here, peripheral blood lymphocytes (PBL) from 21 HCV infected patients and 14 patients with IBD, respectively, were incubated with Naloxone and Naloxone + Ca2+ in order to evaluate a putative modulation of PBL-mediated antibacterial activity. In fact, previous studies have demonstrated a reduction of this T-cell activity in HCV and IBD patients. In general terms, the above treatment led to a recovery of the depressed antibacterial activity. In some cases, increase in T lymphocyte function was obtained with Naloxone alone, while in other cases the combination Naloxone + Ca2+ gave rise to a restorative effect. Of note, in some instances, lymphocytes were unresponsive to pharmacological modulation. The overall results suggest that beta-endorphins may down modulate T-cell antibacterial response in HCV and in IBD patients by saturating peripheral receptors on immune cells. Therefore, it is likely that Naloxone and/or Naloxone + Ca2+ may displace opioid drugs, thus antagonizing their effects.

Adolescent↗

PubMed2000

A cancer modifier role for parathyroid hormone-related protein.

The parathyroid hormone-related protein (PTHrP) gene (Pthlh) maps in the distal region of mouse chromosome 6 that contains a quantitative trait locus associated with genetic predisposition to skin tumorigenesis. Here, we report a genetic polymorphism located in the osteostatin encoding region of the Pthlh gene and that produces Thr/ Pro PTHrP variants. PthlhThr and PthlhPro alleles were significantly linked with resistance and susceptibility to skin carcinogenesis in phenotypically selected Car-R and Car-S outbred mice. Transfection of human NCI-H520 squamous cell carcinoma cells with the PthlhPro allele resulted in cells growing in clusters, tending to pile up, and growing at a significantly faster rate in nude mice than non-transfected and PthlhThr-transfected cells. These results point to the role of the Pthlh gene as a cancer modifier gene in skin tumorigenesis.

Animals↗

PubMed2000

Genetics of chemical carcinogenesis: analysis of bidirectional selective breeding inducing maximal resistance or maximal susceptibility to 2-stage skin tumorigenesis in the mouse.

We report on bidirectional selective breeding, initiated from a genetically defined foundation population and carried out to selection limit, for producing lines of mice endowed with maximal resistance (Car-R) or maximal susceptibility (Car-S) to 2-stage skin tumorigenesis. The initial population resulted from a balanced intercrossing of 8 inbred strains of mice. The tumors, induced by a single application of DMBA (initiation) and twice weekly applications of TPA (promotion), were benign papillomas; their number at the end of the promotion period was the phenotype chosen for assortative mating. Afterward, the majority of them regressed while others progressed to malignant carcinomas. The Car-R line was selected through a strong challenge, while the Car-S line selection was based on responses to decreasing concentrations of DMBA and TPA. The selection limit was reached after 14 or 15 generations showing progressive interline divergence, which strongly suggests the interaction of several quantitative trait loci (QTL). The phenotypic difference was extremely large: the tumor response was 73 times higher in Car-S than in Car-R mice, though the applied concentrations of DMBA and TPA were 100 and 40 times lower, respectively. The mean heritability realized during the selective breeding was 0.20 in Car-R and 0.49 in Car-S. Our results are compatible with a minimal QTL estimate of 8 in the Car-R line and of 9 or 10 in the Car-S line. The Car-S line is also much more susceptible to carcinoma induction. An association of coat color with tumorigenesis was observed in interline F2 segregants. The Car-R and Car-S lines, obtained through a long-lasting breeding program, are a unique model for identifying the QTL involved in chemical tumorigenesis and will be provided to interested investigators.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed2000

Linkage disequilibrium and haplotype mapping of a skin cancer susceptibility locus in outbred mice.

Car-R (carcinogenesis-resistant) and Car-S (carcinogenesis-susceptible) outbred mice, obtained by phenotypic selection from an initial intercross of eight inbred strains, show a >100-fold difference in their susceptibility to two-stage skin tumorigenesis. We found that the lines carry a high degree of genetic polymorphism. with an average heterozygosity of 0.39. This polymorphism allowed the use of linkage disequilibrium (LD) and haplotype analysis for the mapping of a skin cancer modifier locus on Chr 7, in a short region of 6 cM, around the Tyr gene. Car-S mice inherited the susceptibility allele at this locus from the A/J, BALB/c, SJL/J, and SWR/J strains. Our results demonstrate the feasibility and usefulness of mapping disease genes by LD in phenotypically selected, genetically heterogeneous animals.

Animals↗

PubMed2000

Somatic cell hybrids for high-density mapping of chromosome 2 breakpoints in radiation-induced myeloid leukemia cell lines from inbred mice.

Chromosome 2 (chr 2) deletions are recurrent abnormalities in acute myeloid leukemia (AML) induced by ionizing radiation in the mouse. The localization of deletion sites has proven extremely useful in providing information on the molecular mechanisms of leukemogenesis. The models available for the study of AML are mostly represented by inbred mouse strains, in which the molecular resolution of breakpoints is problematic. In this study, we have examined five leukemic cell lines exhibiting hemizygous chr 2 loss, derived from CBA, C3H, or (C57BLxCBA/H) F1 mice in which AML had been induced by a whole-body dose of radiation. By application of a somatic cell hybridization technique, we have generated interspecific cell hybrids retaining the deleted murine chr 2 homologue. This strategy permitted a very detailed genetic analysis allowing the utilization of any genetic marker on chr 2 without a requirement for polymorphism. Somatic cell hybrid clones were subjected to a high-density polymerase chain reaction-based microsatellite screening using 62-106 informative markers for each cell line. Detailed maps accurately defining chr 2 breakpoints were obtained. The identification of critical breakpoint markers allowed the construction of partial yeast artificial chromosome contigs across chr 2 breakpoints. These maps represent an essential resource for cloning of the breakpoint regions.

Animals↗

PubMed1999

Skin tumorigenesis by initiators and promoters of different chemical structures in lines of mice selectively bred for resistance (Car-r) or susceptibility (Car-s) to two-stage skin carcinogenesis.

Carcinogenesis-resistant (Car-R) and carcinogenesis-susceptible (Car-S) mice were obtained applying a bi-directional selective breeding approach to a two-stage skin carcinogenesis protocol, using 9,10-dimethyl-1,2-benzanthracene (DMBA) as initiator and 12-O-tetradecanoylphorbol-13-acetate (TPA) as promoter. Sixteen generations of selection produced a remarkable interline difference in responsiveness to two-stage skin carcinogenesis between Car-R and Car-S: identical DMBA (25 microgram) and TPA (5 microgram) doses induced papillomas in 100% of Car-S compared with 3.3% of Car-R mice and maximal responses of 14.3 or 0.03 papillomas/mouse, respectively, despite the shorter promotion applied to Car-S (49 vs. 208 days). To define the factors determining this great difference, Car-R and Car-S mice were challenged by initiators/promoters chemically unrelated to those used for selection. Both lines were subjected to either initiation by N-methyl-N-nitrosourea (MNU) followed by TPA promotion, or promotion by benzoyl peroxide, or 1,8-dihydroxy-3-methyl-9-anthrone (chrysarobin) following DMBA initiation. Initiation with MNU induced a 10-fold tumour incidence in Car-S compared with Car-R mice, and a 32-fold difference in tumour induction rate. The 2 lines also differed markedly in susceptibility to benzoyl peroxide promotion: Car-S mice initiated with 25 microgram DMBA and promoted with 7.5 mg benzoyl peroxide showed a 12-fold tumour incidence and a 103-fold tumour induction rate compared with the corresponding Car-R group. Both lines, however, were refractory to chrysarobin promotion. The progression of papillomas to carcinomas was examined in all Car-S groups. The incidence of mice that developed carcinomas was 57% in MNU-initiated mice. Benzoyl peroxide was also able to promote carcinoma development in Car-S mice, though with a lower incidence (30.4%) than TPA.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1999

Headache and cardiovascular risk factors: positive association with hypertension.

The study analyzes the prevalence of cardiovascular risk factors in 1343 patients with severe headache (399 men and 944 women), aged 15 to 64 years; analyses were controlled for sex, age, and type and frequency of headache. Prevalence of various forms of headache was different between men and women. Age and days per year with headache were significantly different among various forms of headache. For men and women with headache, age directly related to prevalence of hypertension, hypercholesterolemia, and obesity. Due to low prevalence, analyses by age were not done for diabetes mellitus. For cigarette smoking, prevalence was not related to age in men, but was inversely related to age in women. With control for age, prevalence of cardiovascular risk factors was not significantly different among patients with different forms of headache, except for cluster headache. Among men with cluster headache, prevalence was high for cigarette smoking, but low for hypercholesterolemia. With control for age, days per year with headache did not relate to prevalence of cardiovascular risk factors except for cigarette smoking in men. Compared to data for a population sample used as control, patients with headache had higher prevalence of hypertension in both sexes, independent of age (odds ratio 1.51, 95% confidence interval 1.28 to 1.80); the difference between patients with headache and the control population was lower with increasing age. The high prevalence of hypertension among patients with headache was not due to overweight. The data indicate that headache is significantly associated with hypertension, but not with other cardiovascular risk factors.

Adolescent↗

PubMed1998

Inversion of genetic predisposition to carcinogenesis in liver of two lines of mice selected for resistance (Car-R) or susceptibility (Car-S) to skin carcinogenesis.

Two lines of mice, one resistant (Car-R) and one susceptible (Car-S) to skin carcinogenesis, were produced by bi-directional selective breeding. To see whether the characteristics of susceptibility or resistance to tumorigenesis were also expressed in the liver and lung, the two lines were submitted comparatively to treatment with 5,9-dimethyl dibenzo[c,g]carbazole (DiMeDBC), a potent hepatocarcinogenic derivative of the ubiquitous heterocyclic carcinogenic pollutant, 7H-dibenzo[c,g]-carbazole (DBC). An inversion of genetic predisposition to carcinogenesis in liver was observed. Car-R animals displayed rapid tumorigenesis in 100% of cases while Car-S mice were remarkably less sensitive, showing a 4-fold lower mean tumor multiplicity and a 4-month longer latency time. In parallel adduct formation by DiMeDBC and DBC in liver DNA was analyzed by the 32P-postlabeling method, showing a remarkably higher level in Car-R mice than in Car-S animals. These data indicate that tissue-specific sensibility in carcinogenesis may involve gene expression at various levels.

Animals↗

PubMed1998

Dopamine receptors in the striatum of rats exposed to repeated restraint stress and alprazolam treatment.

Stress-related behaviors are accompanied by modification of a large number of neurotransmitters in the brain. Moreover, the binding to GABA(A) receptors does not account for all the effects of benzodiazepines. In this study we investigated the effect of repeated restraint stress and alprazolam treatment (1 mg/day os) on dopamine receptors (Bmax and Kd) in the striatum of adult rats by means of quantitative receptor autoradiography. After chronic restraint stress dopamine D1 receptors (Bmax value) decreased in the accumbens nucleus, whereas dopamine D2 receptors were not modified in any investigated area. After alprazolam treatment, a considerable increase in both dopamine D1 and D2 receptors in the striatum was observed. Chronic immobilization stress together with alprazolam treatment re-established dopamine D1 receptor density to control values in the accumbens nucleus and olfactory tubercle, whereas it resulted in an increase in dopamine D2 receptors comparable to that elicited by alprazolam treatment alone.

Alprazolam↗