PubMed Health⌕ Search

Biomedical subjects

G Petrone

Publications and source records attributed to G Petrone.

At least 19 recordsLinked to original sources
PubMed2003

Detection of Listeria monocytogenes in Italian-style soft cheeses.

AIMS: A rapid detection system specific for Listeria monocytogenes and based on the polymerase chain reaction (PCR) was developed. METHODS AND RESULTS: Primers annealing to the coding region of the actA gene, critically involved in virulence and capable of discrimination between two different alleles naturally occurring in L. monocytogenes, have been utilized. The procedure was applied to recover L. monocytogenes cells in artificially contaminated fresh Italian soft cheeses (mozzarella, crescenza and ricotta). Low levels of L. monocytogenes were detected in mozzarella and crescenza homogenates (0.04-0.4 and 4 CFU g(-1), respectively) whereas in ricotta the detection limit was higher (40 CFU g(-1)). CONCLUSIONS: This PCR-based assay is highly specific as primers used recognize the DNA from different L. monocytogenes strains of clinical and food origin, while no amplification products result with any other Listeria spp. strains. SIGNIFICANCE AND IMPACT OF THE STUDY: This study highlighted a low-cost and rapid procedure that can be appropriated for the detection in real time of low L. monocytogenes levels in soft cheese.

Bacterial Proteins↗
PubMed2001

Localized ridge augmentation using titanium micromesh.

Guided bone regeneration (GBR) has been used recently for the regeneration of bone in conjunction with the placement of dental implants, for augmentation of resorbed alveolar crests, and to treat localized ridge deformities. Twenty-two patients with alveolar crest defects or peri-implant dehiscences participated in this study. Titanium implants were inserted, and the defects were covered with a titanium micromesh, above which was positioned an e-PTFE membrane. After healing, the 2 membranes were removed and a small specimen of the underlying tissues was retrieved with a small trephine. The postoperative healing was mostly uneventful, and only a few dehiscences with membrane exposure were observed. The space under the membranes was, in all patients, filled by a tissue with the macroscopic features of newly formed bone. No residual bone defects were observed and an increase of the alveolar width or height was observed. No untoward effects on bone regeneration were observed in the cases with membrane exposure. Histology showed that the underlying regenerated tissues were composed, in all cases, by newly formed bone. In conclusion, our results show that very satisfactory results concerning GBR techniques can be obtained even without the use of grafts under barrier membranes.

Adult↗
PubMed2000

Acid tolerance in Listeria monocytogenes influences invasiveness of enterocyte-like cells and macrophage-like cells.

Clinical and food Listeria monocytogenes isolates, pre-exposed to mild acidic conditions, were able to readily develop acid tolerance, irrespective of their origin. We attempted to investigate the influence of acid tolerance mechanisms, either constitutive or induced, on the invasive behaviour of this facultative food-borne pathogen. Entry efficiency and intracellular growth of acid-tolerant strains were evaluated in in vitro cell models capable to mimic in vivo target cells, such as enterocytes and macrophages. An acid-adapted L. monocytogenes wild-type strain and a constitutively acid-tolerant mutant were able to enter enterocyte-like (Caco-2) cells as well as to survive and proliferate intracellularly in lipopolysaccharide-treated macrophage-like (J774.A1) cells, at a significant increased extent by respect of the non acid-adapted wild-type strain. These findings add new information about the influence of the acid tolerance response on L. monocytogenes virulence, suggesting that in acid-adapted bacteria the early events of pathogenesis which allow the colonization and the spread of bacteria in the host may be highly promoted.

Bacterial Adhesion↗
PubMed2000

Infection of human enterocyte-like cells with rotavirus enhances invasiveness of Yersinia enterocolitica and Y. pseudotuberculosis.

Mixed infection with rotavirus and either Yersinia enterocolitica or Y. pseudotuberculosis was analysed in Caco-2 cells, an enterocyte-like cell line highly susceptible to these pathogens. Results showed an increase of bacterial adhesion and internalisation in rotavirus-infected cells. Increased internalisation was also seen with Escherichia coli strain HB101 (pRI203), harbouring the inv gene from Y. pseudotuberculosis, which is involved in the invasion process of host cells. In contrast, the superinfection with bacteria of Caco-2 cells pre-infected with rotavirus resulted in decreased viral antigen synthesis. Transmission electron microscopy confirmed the dual infection of enterocytes. These data suggest that rotavirus infection enhances the early interaction between host cell surfaces and enteroinvasive Yersinia spp.

Adhesins, Bacterial↗
PubMed2000

Modulation of actA gene expression in Listeria monocytogenes by iron.

This study analysed the invasiveness of Listeria monocytogenes into enterocyte-like Caco-2 cells in which iron depletion was achieved by picolinic acid treatment. Both entry and intracellular multiplication varied depending on the endogenous iron content of bacterial and eukaryotic cells. The behaviour within enterocytes was correlated with a 10-fold increased transcription of the actA gene observed in bacterial cells grown under conditions of iron stress.

Bacterial Proteins↗
PubMed2000

Implant periapical lesion: a clinical and histologic case report.

A new pathologic entity called implant periapical lesion has been recently described. This lesion could be produced by contamination of the implant surface, overheating of bone, overloading of the implant, presence of a pre-existing bone pathology, presence of residual root fragments and foreign bodies in bone, implant placement in an infected maxillary sinus, implant placement in a poor bone quality site, or lack of biocompatibility. A 49-year-old female patient underwent the placement of a screw-shaped titanium dental implant in the premolar region of the right mandible Six months after implant insertion, the patient presented with a persistent pain resistant to analgesics. No fistula was present at a clinical intraoral examination. A periapical x-ray showed the presence of a radiolucency at the apical portion of the implant; this image was confirmed by a CT Scan. The implant was removed. After implant removal, the pain disappeared completely. The specimen was processed to obtain thin ground sections. The histologic examination showed the presence of necrotic bone in the external and apical portion of the antirotational hole of the implant. The etiology of the implant failure in this instance could be related, probably, to an implant contamination of the apical portion of the implant.

Dental Implantation, Endosseous↗
PubMed2000

Immediate postextraction implants: a histologic and histometric analysis in monkeys.

The aim of this study was to evaluate the reaction of peri-implant tissues to immediately placed titanium plasma-sprayed implants into extraction sockets. Six macaca fascicularis monkeys were used in the study. A total of 36 titanium plasma-sprayed implants (PHI, Legnano, Italy) were inserted in both arches (18 in the posterior maxilla and 18 in the posterior mandible). The two premolars and the first molars of the maxilla and the mandible of all animals were extracted, and immediate postextraction implants were placed. After a releasing periosteal incision, the flap was coronally repositioned and sutured. No barrier membranes were used, and the only graft material used was autogenous bone chips. The implants were loaded after 2 months. Six months after implant loading, a block section was carried out, the remaining defects were filled with nonresorbable hydroxyapatite, and all 36 implants were retrieved. The implants were treated with the Precise System (Assing, Rome, Italy), to obtain thin ground sections. A total of three slides were cut for each implant and were examined under normal and polarized light. A histomorphometrical analysis was done. All implants were covered by compact, mature bone under examination in light microscopy. A very high bone-implant contact percentage (65-70%) was observed. No bone loss was present after the loading period. These results indicate that implants placed into fresh extraction sites grafted with autogenous bone chips will heal in a predictable way.

Animals↗
PubMed1998

Natural milk fatty acids affect survival and invasiveness of Listeria monocytogenes.

The effects of 12 fatty acids, naturally occurring in milk from several mammalian species, on the survival and invasion ability of Listeria monocytogenes, a food-borne pathogen, were determined. The survival was tested in the presence of 200 micrograms ml-1 fatty acids suspended in brain hearth infusion broth or in storage conditioning solution (NaCl 1%) of Mozzarella cheese, an Italian soft unripened cheese, at pH 7.0 or 5.0. Lauric (C12:0), linoleic (C18:2) and linolenic (C18:3) acids exerted the strongest bactericidal activity. The invasive efficiency of L. monocytogenes, determined in the Caco-2 enterocyte-like cell line, was strongly decreased in the presence of the fatty acids tested (from about 20 to 500-fold). This research suggests that naturally occurring fatty acids of milk, supplemented in milk derivatives, could affect both bacterial growth and invasiveness and consequently, could serve as barriers towards L. monocytogenes infection.

Animals↗
PubMed1998

Extradural hematomas in children.

BACKGROUND: Extradural hematomas are rate complications of head injures in children often resulting from minor head traumas. Therefore the management of these ordinary traumas remains controversy since in many asymptomatic cases the intracranial bleeding is detected only by CT scan. METHODS: During the study period between January 1991 and September 1995 sixty-one patients ranging in age from 5 months to 12 years were operated on for epidural hematomas. They represent about the 3% of all patients admitted for head injury in the same period in our Division. According to the age, children were divided in three groups (G1, G2, G3). Males predominate over females in each group of age. The mechanism of injury, the clinical findings, the neurological assessment on admission, the site of hematoma and the presence of skull fracture were examined in order to identify clinical and diagnostic parameters predicting developing intracranial complications. RESULTS: The most common cause of head trauma was accidental falls in children under 5 years of age. Otherwise bicycle, pedestrian and car accidents are the main type of injury in older patients. A skull fracture was identified in 49 cases with a homogeneous distribution among the groups of age. Recurrent vomiting was found in about 70% of cases. A loss of consciousness was frequently reported (78%) in older children. Outcome mainly depended on Glasgow or Children Coma Score on admission. In our series the overall mortality rate was 4.9%. CONCLUSIONS: Our data according with the literature suggest that localized skull traumas, suspected fractures, a loss of consciousness after trauma and recurrent vomiting can be recommended as indications for intracranial complications.

Child↗
PubMed1997

Discovery of a novel class of substituted pyrrolooctahydroisoquinolines as potent and selective delta opioid agonists, based on an extension of the message-address concept.

This paper describes the design and synthesis of compounds belonging to a novel class of substituted pyrrolooctahydroisoquinolines which are potent and selective delta opioid agonists. Molecular modeling studies performed on known, selective delta ligands such as (+)-3 and the potent delta agonists SNC 80 led to the identification of the carboxamido moiety of the latter as a putative nonaromatic delta address. Insertion of this moiety onto the octahydroisoquinoline opioid message resulted in (+/-)-5b, a potent and selective delta ligand. The active enantiomer, (-)-5b, displayed nanomolar affinity for the delta receptor (Ki = 0.9 nM) with good mu/delta and kappa/delta binding selectivity ratios (140 and 1480, respectively). In addition, (-)-5b behaved as a full delta agonist in the mouse vas deferens bioassay having an IC50 = 25 nM and being antagonised in the presence of 30 nM naltrindole (NTI). These studies, based on the message-address concept, indicated that the nonaromatic (N,N-diethylamino)carbonyl moiety is a viable alternative to the classical benzene ring as a delta opioid address. Preliminary in vivo studies showed that (+/-)-5b produced a dose-related antinociception in the mouse abdominal constriction test after intracerebroventricular administration (ED50 = 1.6 micrograms/mouse).

Animals↗
PubMed1997

Comparison of the water diuretic activity of kappa receptor agonists and a vasopressin receptor antagonist in dogs.

Strategies for developing selective water diuretic agents have involved development of kappa opioid receptor agonists and vasopressin V2 receptor antagonists; however, these two classes of compounds have not been compared directly. We have investigated the activity of three kappa receptor agonists and one nonpeptide vasopressin receptor antagonist in conscious dogs. SB 215520, SB 215519 and niravoline are selective kappa agonists with variable abilities to cause a water diuresis and ataxia in rats. When administered to conscious hydropenic dogs, the kappa agonists resulted in an increase in free water clearance; however, these effects were associated with an antinatriuresis, an increase in heart rate and, at the higher doses, central nervous system side effects. Conversely, the vasopressin receptor antagonist, OPC 31260, resulted in a significant water diuresis without any accompanying changes in sodium excretion and heart rate, and with no apparent central nervous system effects. These studies suggest that, at least in dogs, a vasopressin receptor antagonist is a more selective water diuretic than a kappa receptor agonist.

Animals↗
PubMed1997

Giant intracavernous carotid aneurysm in a child. Case report.

The occurrence of intracranial aneurysm in the pediatric population is a rare phenomenon. A case of giant aneurysm of the intracavernous carotid artery in a child is reported. Clinicoradiological findings are presented and the surgical procedure is illustrated. Authors stress the value of monitoring the cerebral collateral blood flow before and during the operation.

Adolescent↗
PubMed1996

Spinal intramedullary angiolipoma.

We report the case of a young patient with a thoracolumbar (T11-L3) intramedullary angiolipoma. Total removal of the tumor was possible and after operation the patient's neurological condition greatly improved. Only two previous cases of intramedullary angiolipomas have been reported, and in neither could the lesion be wholly removed. The histopathological and radiological features of these tumors are discussed and the extreme rareness of this case is emphasized.

Angiolipoma↗
PubMed1996

Superinfection by Listeria monocytogenes of cultured human enterocyte-like cells infected with poliovirus or rotavirus.

A mixed infection with either rotavirus or poliovirus and Listeria monocytogenes was analysed in Caco-2 cells, a tumour-derived cell line, highly susceptible to these pathogens. The multiplication of these pathogens, whose usual site of entry and/or replication is the intestine, was also followed by electron microscopy. Results obtained showed an increase of L. monocytogenes internalisation in cells infected with rotavirus, whereas the preinfection with poliovirus had only a slight interfering effect on bacterial entry. Analysis of L. monocytogenes multiplication in virus-infected cells revealed that rotavirus also promoted bacterial replication, which poliovirus hampered replication. Concerning the effect of Caco-2 cell invasion by L. monocytogenes on viral replication, we observed an increase in rotavirus antigen synthesis but no significant effect on poliovirus yield under our experimental conditions.

Caco-2 Cells↗
PubMed1996

The effects of inhibitors of vacuolar acidification on the release of Listeria monocytogenes from phagosomes of Caco-2 cells.

To evaluate the role of the acidic pH of phagosomes on the invasive ability and fate of Listeria monocytogenes within host cells, entry and replication of this gram-positive bacterium in a human enterocyte-like cell line (Caco-2) were investigated by a combination of biochemical and ultrastructural approaches. The effects of inhibitors of vacuolar acidification--the lipophilic weak base ammonium chloride, the carboxylic ionophore monensin and the vacuolar proton ATPase inhibitor bafilomycin A1--on the bacterial invasion pathway were analysed. These agents, which raise the intracellular vesicle acidic pH of living cells by different mechanisms, affected L. monocytogenes replication in Caco-2 cells. Bacteria internalised by bafilomycin-treated cells were unable to escape from phagosomes, as demonstrated by electronmicroscopy. The results provide evidence that low pH is required for efficient intracellular growth of L. monocytogenes.

Ammonium Chloride↗
PubMed1996

Iron availability affects entry of Listeria monocytogenes into the enterocytelike cell line Caco-2.

The influence of iron on the entry of Listeria monocytogenes into Caco-2 cells was studied. Iron availability was found to modify the surface hydrophobicity and protein profile of L. monocytogenes, with the result that cell invasion strongly increased upon bacterial growth in iron-rich medium. The enhanced invasive capability of iron-overloaded L. monocytogenes cells correlates to the higher-level expression of the inlAB virulence genes, which were positively iron regulated at the transcriptional level.

Bacterial Adhesion↗
PubMed1995

Trigonocephaly associated with anterior basal meningocele. Case report.

Pathogenesis of craniosynostosis is poorly understood. Several different factors (primary fusion of a cranial vault suture, abnormal tensile forces acting on the cranial sutures, genetic control, fetal constraint) may be responsible for the malformation. Trigonocephaly is a relatively rare form of cranial malformation ranging from 5 to 20% of all the craniosynostotic syndromes. This form of craniosynostosis may be simple not associated with other cerebral defects or complex, associated with arhinencephaly and hypoplasia of frontal lobes; three gradations of malformation (marked, mild, incomplete) may be considered. A case of trigonocephaly associated with anterior basal meningocele is reported. The operative treatment and radiological findings are described. The pathogenetic role of the basal meningocele to determine the premature sutural fusion through tensile forces transmitted by abnormal dural attachments is evaluated.

Craniosynostoses↗