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A Caprioli

Publications and source records attributed to A Caprioli.

At least 19 recordsLinked to original sources
PubMed2002

Expression of Notch genes and their ligands during gastrulation in the chicken embryo.

Notch signalling is an important evolutionary conserved mechanism known to control cell fate choices through local interactions. Here, the patterns of expression of Notch-1 and -2 genes and their ligands Delta-1, Serrate-1 and -2, were established in the early blastodisc of the chicken embryo from the pre-streak to the first somite stages. Delta-1 was detected as early as the pre-streak stage in the posterior part of the embryo shortly followed in the same region by Notch-1 at the initial streak stage. Thereafter both were strongly expressed in the posterior part of the primitive streak until HH4. Notch-2 was also found at the level of the streak although at low levels. Notch-1 was homogeneously expressed by the epiblast and by mesodermal cells ingressing at the level of the streak whereas Delta-1 expression formed a 'salt and pepper' pattern. The difference between the two was clearly detected by double in situ hybridisation. From the mid-streak to the first somite stages, Notch-1 and Delta-1 expressions appeared in the anterior part of the embryo. Serrate-1 and -2 were not detected at these stages. Taken together, these results constitute a framework for analysing the role(s) for Notch signalling during gastrulation.

Animals↗
PubMed2001

Hemangioblast commitment in the avian allantois: cellular and molecular aspects.

We recently identified the allantois as a site producing hemopoietic and endothelial cells capable of colonizing the bone marrow of an engrafted host. Here, we report a detailed investigation of some early cytological and molecular processes occurring in the allantoic bud, which are probably involved in the production of angioblasts and hemopoietic cells. We show that the allantois undergoes a program characterized by the prominent expression of several "hemangioblastic" genes in the mesoderm accompanied by other gene patterns in the associated endoderm. VEGF-R2, at least from stage HH17 onward, is expressed and is shortly followed by transcription factors GATA-2, SCL/tal-1, and GATA-1. Blood island-like structures differentiate that contain both CD45(+) cells and cells accumulating hemoglobin; these structures look exactly like blood islands in the yolk sac. This hemopoietic process takes place before the establishment of a vascular network connecting the allantois to the embryo. As far as the endoderm is concerned, GATA-3 mRNA is found in the region where allantois will differentiate before the posterior instestinal portal becomes anatomically distinct. Shortly before the bud grows out, GATA-2 was expressed in the endoderm and, at the same time, the hemangioblastic program became initiated in the mesoderm. GATA-3 is detected at least until E8 and GATA-2 until E3 the latest stage examined for this factor. Using in vitro cultures, we show that allantoic buds, dissected out before the establishment of circulation between the bud and the rest of the embryo, produced erythrocytes of the definitive lineage. Moreover, using heterospecific grafts between chick and quail embryos, we demonstrate that the allantoic vascular network develops from intrinsic progenitors. Taken together, these results extend our earlier findings about the commitment of mesoderm to the endothelial and hemopoietic lineages in the allantois. The detection of a prominent GATA-3 expression restricted to the endoderm of the preallantoic region and allantoic bud, followed by that of GATA-2, is an interesting and novel information, in the context of organ formation and endoderm specification in the emergence of hemopoietic cells.

Allantois↗
PubMed2001

Detection and characterization of Shiga toxin-producing Escherichia coli in feral pigeons.

Escherichia coli strains producing a variant of Shiga toxin 2 (Stx2), designated Stx2f, have been recently described in the stools of feral pigeons. During 1997-1998, 649 pigeons were trapped and examined in three different squares of Rome. Stool samples were collected from each bird and enrichment cultures were examined for the presence of Stx by the vero cell assay. Stx-producing E. coli (STEC) were isolated from the positive cultures and characterized by serotyping and PCR analysis of stx and other virulence-related genes. Stx was detected in 10.8% of the stool enrichment cultures. The percentage of positive birds did not differ significantly for the three flocks considered and the season of sample collection. Conversely, STEC carriage was significantly more frequent in young than in adult birds (17.9 versus 8.2%). None of the birds examined showed signs of disease. STEC strains were isolated from 30 of 42 Stx-positive cultures examined. All the strains produced Stx2f, and most of them possessed genes encoding for intimin and the cytolethal distending toxin (CLDT). Six serogroups were identified, but most of the isolates belonged to O45, O18ab, and O75. Molecular typing indicated that most of the isolates within a flock were clonally-related. This work confirms that pigeons represent a natural reservoir of STEC strains characterized by the production of the toxin variant Stx2f, and by the frequent presence of eae and cldt genes. Further work is needed to clarify whether these STEC may represent a cause of avian disease or even a potential health hazard for humans.

Animals↗
PubMed2001

Faecal carriage of Verocytotoxin-producing Escherichia coli O157 and carcass contamination in cattle at slaughter in northern Italy.

A study on the prevalence of the faecal carriage of Verocytotoxin (VT)-producing Escherichia coli (VTEC) O157 and on the rate of carcass contamination was carried out on feedlot cattle and dairy cows at slaughter in northern Italy. Between April 1998 and January 1999, 12 sampling visits were performed on different days in seven different slaughterhouses. At each visit, 5-12 animals consecutively slaughtered were selected. From each animal, faeces were collected from the rectum immediately after slaughter and surface swabs were taken from the leg region and the diaphragmatic insertion of the carcass. All samples were examined for the presence of VTEC O157 using an immunomagnetic separation technique. A total of 100 animals coming from 60 different farms were examined. In total, VTEC O157 was isolated from the intestinal content of 17, and from the carcasses of 12 of the 100 animals examined. In particular, VTEC O157 was recovered from six (35.3%) out of the 17 carcasses from which the organism had previously been isolated from rectal content and from six (7.3%) of the 82 carcasses of the stool-negative cattle. In seven carcasses, VTEC O157 was isolated from the leg area, in two carcasses from the diaphragmatic area, and in three carcasses from both areas. Major differences in the prevalence of VTEC O157 were observed in the different groups of cattle sampled. In 7 of the 12 sampling visits, all the specimens examined were negative, while 16 of the 17 positive stool samples and 11 of the 12 positive carcass swabs were collected during three of the visits, performed in June in three different abattoirs. In these three visits, the ratios between the percentage of animals carrying VTEC O157 in the stools and the percentage of contaminated carcasses were 0.33, 0.57, and 1.66, respectively; thus, confirming that slaughter practices can largely influence the rate of carcass contamination. Phage typing and PFGE analysis of VTEC O157 isolated from samples collected at the same visit suggested that both auto- and cross-contamination occurred.

Abattoirs↗
PubMed2000

Molecular fingerprinting of strains of Yersinia ruckeri serovar O1 and Photobacterium damsela subsp. piscicida isolated in Italy.

We studied the ribotypes, patterns of pulsed-field gel electrophoresis (PFGE) and interspersed repeated sequences (IRS)-PCR of 30 strains of Yersinia ruckeri O1 and 20 strains of Photobacterium damsela subsp. piscicida isolated from apparently unrelated epizootic outbreaks occurring on Italian fish farms between 1993 and 1999. All of the Y. ruckeri O1 strains had similar profiles, as demonstrated by all three typing methods, thus confirming the clonal structure of this species. The strains of P. damsela subsp. piscicida showed similar profiles when tested with ribotyping and PFGE; however, two slightly different profiles were distinguished by IRS-PCR using the primer ERIC2. The two profiles appeared to be related to the geographic origin of the strains, since each of them was specific to isolates from a certain area (i.e. northern or southern Italy). This result suggests that PCR fingerprinting may be a valuable tool in typing fish bacterial pathogens, which often present a great degree of genetic homogeneity.

Animals↗
PubMed2000

Monitoring of antibiotic resistance in bacteria of animal origin: epidemiological and microbiological methodologies.

The occurrence of antibiotic-resistant bacteria in food animals is a major public health threat. Information on the prevalence of resistance to specific drugs in both bacterial and animal species together with changes occurring over time, are necessary to understand the magnitude of the problem and to establish baselines for taking action. The aim of this paper is to define the minimum epidemiological and microbiological requirements for establishing a surveillance of antimicrobial resistance in bacteria of animal origin. Surveillance should involve different bacterial species, veterinary pathogens, zoonotic bacteria and commensal bacteria used as indicators. The collected data should be periodically updated and the reports distributed among practising veterinarians and regulatory authorities. These reports would be a useful tool for developing guidelines for the prudent use of antimicrobial agents in veterinary medicine and for action strategies.

Animal Diseases↗
PubMed2000

Detection and characterization of vancomycin-resistant enterococci in farm animals and raw meat products in Italy.

The emergence of vancomycin-resistant enterococci (VRE) in Europe has been ascribed to the long-time use of the glycopeptide antibiotic avoparcin as feed additive in food animals, until its ban in 1997 in EU. The pres- ence of VRE in food of animal origin is believed to represent a potential risk for the consumer. We studied the fecal carriage of VRE in broiler chickens and slaughter pigs in Italy before the avoparcin ban and eval- uated the impact of avoparcin withdrawal on the presence of VRE in raw meat products. Broilers and pigs were both found to be frequently colonized by VRE, as 36% and 24.6% of the flocks or the herds, respec- tively, were positive. Molecular typing of VRE strains by PFGE showed that animals housed in different pens within the same farm were colonized by clonally related strains. After the avoparcin ban, a decrease in the rate of VRE contamination in meat products was observed. Such a decrease was statistically significant in poultry (from 18.8% to 9.6%) but not in pork products (from 9.7% to 6.9%). The majority of VRE from all sources carried the vanA resistance gene and included Enterococcus faecium, E. faecalis, E. hirae, E. durans, and E. gallinarum. None of the strains carried the vanB gene, whereas constitutively resistant vanC-positive strains were frequently found. Our results show that avoparcin withdrawal has been successful in reducing VRE contamination in meat products. However, this measure needs to be complemented by a prudent use of glycopeptide antibiotics in human medicine.

Animals↗
PubMed2000

A new Shiga toxin 2 variant (Stx2f) from Escherichia coli isolated from pigeons.

We have isolated Shiga toxin (Stx)-producing Escherichia coli (STEC) strains from the feces of feral pigeons which contained a new Stx2 variant gene designated stx(2f). This gene is most similar to sltIIva of patient E. coli O128:B12 isolate H.I.8. Stx2f reacted only weakly with commercial immunoassays. The prevalence of STEC organisms carrying the stx(2f) gene in pigeon droppings was 12.5%. The occurrence of a new Stx2 variant in STEC from pigeons enlarges the pool of Stx2 variants and raises the question whether horizontal gene transfer to E. coli pathogenic to humans may occur.

Alleles↗
PubMed2000

Typing of intimin genes in human and animal enterohemorrhagic and enteropathogenic Escherichia coli: characterization of a new intimin variant.

Enteropathogenic Escherichia coli (EPEC) and enterohemorrhagic E. coli (EHEC) produce the characteristic "attaching and effacing" (A/E) lesion of the brush border. Intimin, an outer membrane protein encoded by eae, is responsible for the tight association of both pathogens with the host cell. Several eae have been cloned from different EPEC and EHEC strains isolated from humans and animals. These sequences are conserved in the N-terminal region but highly variable in the last C-terminal 280 amino acids (aa), where the cell binding activity is localized. Based on these considerations, we developed a panel of specific primers to investigate the eae heterogeneity of the variable 3' region by using PCR amplification. We then investigated the distribution of the known intimin types in a large collection of EPEC and EHEC strains isolated from humans and different animal species. The existence of a yet-unknown family of intimin was suspected because several EHEC strains, isolated from human and cattle, did not react with any of the specific primer pairs, although these strains were eae positive when primers amplifying the conserved 5' end were used. We then cloned and sequenced the eae present in one of these strains (EHEC of serotype O103:H2) and subsequently designed a PCR primer that recognizes in a specific manner the variable 3' region of this new intimin type. This intimin, referred to as "epsilon," was present in human and bovine EHEC strains of serogroups O8, O11, O45, O103, O121, and O165. Intimin epsilon is the largest intimin cloned to date (948 aa) and shares the greatest overall sequence identity with intimin beta, although analysis of the last C-terminal 280 aa suggests a greater similarity with intimins alpha and gamma.

Adhesins, Bacterial↗
PubMed1999

Occurrence of Vibrio and other pathogenic bacteria in Mytilus galloprovincialis (mussels) harvested from Adriatic Sea, Italy.

Sixty-two samples of Mytilus galloprovincialis (mussels) harvested from approved shellfish waters in the Adriatic Sea were examined for the presence of Vibrio, Salmonella, Campylobacter, and verocytotoxin producing Escherichia coli. Vibrio spp. were isolated from 48.4% of samples; the species most frequently found were V. alginolyticus (32.2%) and V. vulnificus (17.7%), followed by V. cincinnatiensis (3.2%), V. parahaemolyticus (1.6%), V. fluvialis (1.6%) and V. cholerae non-O1 (1.6%). V. parahaemolyticus resulted negative to Kanagawa-phenomenon and to PCR amplification of tdh gene. V. cholerae resulted negative to PCR amplification of sto gene. No Salmonella, Campylobacter, or E. coli verocytotoxin-producing strains were isolated. The results of this study suggest the potential risk of ingesting raw or undercooked mussels due to the frequent presence of potentially pathogenic Vibrio species.

Animals↗
PubMed1999

Isolation of Verocytotoxin-producing Escherichia coli O157:H7 from cattle at slaughter in Italy.

Cattle arriving for slaughter at a large abattoir in northern Italy between April 1997 and January 1998 were examined for intestinal carriage of Verocytotoxin-producing Escherichia coli (VTEC) O157 using an immunomagnetic separation technique. Sixty sorbitol non-fermenting VTEC O157 strains were isolated from 59 (13.1%) of the 450 cattle examined. In particular, VTEC O157 was found in 37 (16.6%) of 223 feedlot cattle and in 22 (16.1%) of 137 dairy cull cows, but not in the 90 veal calves sampled. The isolation rate was higher during warm weather (17.5%), falling to an average of 2.9% during the winter months. VT-negative, O157 latex-agglutinating E. coli strains were isolated from 23 (5.1%) of the 450 animals. PCR analysis showed that all 60 VTEC O157 strains carried the VT2 gene and that 25 strains also carried the VT1 gene. In addition, four of the VT-negative, O157 latex-agglutinating E. coli strains carried the VT2 gene. Atypical biochemical features were observed in some VTEC O157: two strains (3.3%) showed beta-glucuronidase activity, and seven (11.7%) produced urease.

Abattoirs↗
PubMed1999

Molecular characterisation of verocytotoxin-producing Escherichia coli of serogroup O111 from different countries.

A collection of epidemiologically unrelated verocytotoxin (VT)-producing Escherichia coli (VTEC) strains of serogroup O111 isolated from human patients and cattle with diarrhoeal disease in five different countries were characterised by determination of their VT genotypes, the presence of other virulence factors such as the intimin-coding eae gene and the enterohaemorrhagic E. coli (EHEC) plasmid, and their antibiotic susceptibility patterns. The genetic relatedness among isolates was evaluated by genomic DNA fingerprinting techniques such as restriction fragment length polymorphism analysis of ribosomal RNA genes (ribotyping) and pulsed-field gel electrophoresis. The results indicated that the VTEC O111 examined belong to two distinct clonal lineages. The first group was constituted mainly of non-motile, eae-positive, EHEC plasmid-positive isolates from both man and cattle. The second lineage was represented by an O111:H2 epidemic strain, isolated during an outbreak of haemolytic uraemic syndrome in France and exhibiting an unusual combination of virulence factors: VT production and aggregative adhesion to HEp-2 cells associated with an enteroaggregative E. coli (EAEC) plasmid.

Adhesins, Bacterial↗
PubMed1999

Direct detection of Clostridium perfringens enterotoxin in patients' stools during an outbreak of food poisoning.

An outbreak of diarrhoea in a hotel affected 25 time keepers attending the 1997 Mediterranean Games. Epidemiological investigation implicated a 'pasta al ragù' consumed at the hotel's restaurant and Clostridium perfringens food poisoning was identified by direct detection of C. perfringens enterotoxin in patients' stools. This report confirms that a careful evaluation of epidemiological features, together with the availability of direct and rapid laboratory methods, may lead to a prompt identification of C. perfringens food poisoning.

Adolescent↗
PubMed1999

Development of a universal intimin antiserum and PCR primers.

Enteropathogenic Escherichia coli (EPEC) and enterohemorrhagic E. coli (EHEC) constitute a significant risk to human health worldwide. A hallmark of both pathogens is their ability to produce characteristic attaching-and-effacing (A/E) lesions in intestinal epithelial cells. Genes encoding A/E lesion formation map to a chromosomal pathogenicity island termed the locus of enterocyte effacement (LEE). Intimin, an LEE-encoded bacterial adhesion molecule, mediates the intimate bacterium-host cell interaction characteristic of A/E lesions. On the basis of characterization of the C-terminal 280-amino-acid cell binding domain of intimin (Int280(661-939)), four distinct Int280 types (types alpha, beta, gamma, and delta) have been identified. Importantly, Int280alpha and Int280beta antisera specifically recognized their respective intimin types. Using a conserved region of the intimin molecule (Int(388-667)) and primers synthesized to generate the recombinant Int(388-667), we have now generated universal intimin antiserum and PCR primers that are reactive with the different intimin types expressed by both human and animal A/E lesion-forming strains. Use of immunogold electron microscopy to visualize intimin on the surfaces of EPEC and EHEC strains revealed, in general, a uniform distribution on the bacterial cell surface. However, a filamentous staining pattern was observed with a few strains expressing intimin gamma. Cloning of the intimin eae gene from one such strain (strain ICC57) into strain CVD206, an EPEC strain which harbors a null deletion in eae, produced a uniform intimin staining pattern indicating that, if the filamentous staining pattern defines a filamentous form of intimin gamma, it is dependent upon the genetic background of the strain and is not a feature of the intimin molecule.

Adhesins, Bacterial↗
PubMed1998

Blood-borne seeding by hematopoietic and endothelial precursors from the allantois.

Until now the allantois has not been considered as a hematopoietic organ. Here we report experimental evidence demonstrating the in situ emergence of both hematopoietic and endothelial precursors in the avian allantoic bud. When the prevascularized allantoic bud from a quail embryo was grafted in the coelom of a chicken host, hematopoietic and endothelial cells later were found in the bone marrow of the host. Because the graft was located at a distance from the limb bud, these cells could reach the bone marrow only by the circulatory pathway. This blood-borne seeding may be accomplished by distinct hematopoietic and endothelial precursors, or by hemangioblasts, the postulated common precursors of these two lineages; we consider the latter interpretation more likely. We also show by reverse transcription-PCR that the allantois region expresses very early the GATA genes involved in hematopoiesis and some beta-globin chain genes.

Allantois↗