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Biomedical subjects

G Petrone

Publications and source records attributed to G Petrone.

51 records · Page 3Linked to original sources
PubMedDate not supplied

Listeria monocytogenes infection of Caco-2 cells: role of growth temperature.

The aim of the present study was to evaluate the role of temperature in the virulence of Listeria monocytogenes, a Gram-positive facultative intracellular food-borne pathogen. The capacity of bacteria grown at 37, 25 and 4 degrees C to develop haemolytic activity, to enter the Caco-2 enterocyte-like cell line and to multiply intracellularly was investigated. We demonstrated that L. monocytogenes penetration was not significantly influenced by the growth temperature of cultures and that bacteria grown at low temperature were capable of synthesizing internalin and, during the infection process, of restoring the haemolytic phenotype which is normally lacking in the extracellular environment at 4 and 25 degrees C. It can be concluded that L. monocytogenes, frequently present in numerous environmental sources and also in refrigerated food products, produces at low temperature, the virulence factors necessary to invade intestinal cells.

Colonic Neoplasms↗
PubMedDate not supplied

Tissue reactions, fluids, and bacterial infiltration in implants retrieved at autopsy: a case report.

A 72-year-old patient underwent the placement of 2 screw-type implants. After 5 months the patient died of a massive stroke, and a block section of the portion of the mandible containing the implants was done. The specimen was treated to obtain thin ground sections. A 1- to 5-micron gap was present between the implant and the healing cover screw, and this space was filled by bacteria and calculus; bacteria were also present in the most apical portion of the hollow part of the implant. An inflammatory infiltrate was present in the connective peri-implant tissues. The spaces between all implant components (implant, abutment, and healing screw) can act as conduits and reservoirs for bacteria, which could cause inflammation of the peri-implant soft tissues. In conclusion, the histologic data from this autopsy case may help to confirm the penetration by fluids and bacteria into the internal portion of the implants, obtained from previous in vitro and in vivo studies.

Aged↗
PubMedDate not supplied

Immediate one-stage postextraction implant: a human clinical and histologic case report.

The placement of an implant immediately after tooth extraction may have the following advantages: reduction in morbidity, treatment time, and treatment costs; preservation of the residual ridge width and height; optimal esthetic result; and easier definition of implant position. The aim of the present study was the presentation of a human clinical and histologic report involving a nonsubmerged implant placed in a mandibular postextraction site and removed because of persistent pain. At low-power magnification, it was possible to see that newly formed bone with wide osteocyte lacunae was present around the implant. A 1.5-mm sulcular epithelium was visible on one side of the implant, with a 0.5-mm epithelial attachment. The thickness of the supracrestal connective tissue was 3.2 mm. This connective tissue was dense, had few cells, was well vascularized, and showed no evidence of an inflammatory infiltrate. Under polarized light, it was possible to observe that the connective fibers were arranged perpendicular to the implant surface and that these fibers became parallel near the implant. These results show that human immediate postextraction implants can have a high percentage of bone-implant contact.

Alveolar Process↗
PubMedDate not supplied

Tetraplegia from trauma of the cervical spine in the absence of fractures and luxations.

Spinal cord lesions are not infrequent in cervical traumas in absence of fractures and/or luxations. In hyperextension traumas conservative treatment is normally sufficient. In hyperflexion and unknowm mechanism traumas neurosurgical treatment is often necessary due to the frequency of a discal herniation. Myelography is indispensable for correct and complete diagnosis and for this reason its use is strongly recommended.

Cervical Vertebrae↗
PubMedDate not supplied

Invasion of human cultured cells by Prevotella nigrescens.

Invasion of gingival and junctional epithelial cells has been recently proposed as a potentially relevant mechanism in the pathogenesis and recurrence of periodontal disease. The gram negative anaerobe Prevotella nigrescens was shown to be involved in the development of periodontal lesions in man, suggesting a possible involvement of invasivity as a mean to circumvent the host immune surveillance and other hostile factors. Appropriately designed invasion assays demonstrated that P. nigrescens efficiently invades human epithelial cells, through a mechanism whose efficiency is influenced by the phase of growth, by the multiplicity of infection, and by the cell line used, and that requires microfilament integrity, but is not affected by an impairment of microtubule organization. Intracellular replication assays suggested that P. nigrescens probably multiplies within Kb epithelial cells, causing extensive cell alterations. Invasion of gingival epithelial cells could consequently be a basic step in the virulence mechanism of the species.

Journal Article↗
PubMedDate not supplied

The anti-invasive effect of bovine lactoferrin requires an interaction with surface proteins of Listeria Monocytogenes.

The anti-invasive effect of bovine lactoferrin (BLf) and of bovine transferrin (BTf) towards L. monocytogenes, an intracellular facultative food-borne pathogen, was assayed in the enterocyte-like cell line Caco-2. When 0.5 mg/ml BLf were added during the infection time or preincubated with bacteria the number of internalized bacteria was noticeably decreased whereas BLf was ineffective when preincubated with the enterocytes or added post infection. BTf was deprived of any effect. Results from direct binding and Western blotting assays provided evidence that two L. monocytogenes surface proteins, of approximately 80 and 60 kDa, specifically reacted with BLf. These findings strongly support the hypothesis that the antiinvasive mechanism of BLf is due to its interaction with bacterial surfaces, but not to its binding with eukaryotic cells.

Journal Article↗
PubMedDate not supplied

In vivo incorporation of 3H-glycerol and 14C-palmitate into lipids of subcellular fractions of the myocardium hypertrophied during experimental hypoxia.

Incorporation of labelled precursors into neutral lipids and phospholipids of hypertrophied guinea-pig cardiac ventricles during normobaric hypoxia (breathing gas mixture of N2: O2, 9: 91%) was studied. The lipids of the heart were isotopically labelled in vivo with [1-14C] palmitate and [2-3H] glycerol, and, after a period of 2 hours, the incorporation of the two injected precursors into mitochondrial and microsomal fractions was determined. Eighty hours after the onset of the hypoxic treatment, the specific activities of isolated lipids showed a more elevated incorporation into lipid classes of hypoxic right and left ventricles with respect to that of the control. For both precursors, the percent increase of incorporation into microsomal and mitochondrial neutral lipids was higher than into phospholipids. In the microsomal fraction the increase of 14C-radioactivity incorporation was more pronounced than 3H-incorporation. 3H/14C incorporation ratio appeared decreased in hypoxic ventricles. The data in this experiment suggest that the net increase of 3H-glycerol and 14C-palmitate incorporation into myocardial lipid classes was a compensatory response of the heart to the hypoxic stimulus.

Animals↗
PubMedDate not supplied

Arteriovenous aneurisms of the spinal cord. Observations of 8 cases.

After description of the anatomy of spinal circulation, the Authors report some data from the literature concerning the localization, the incidence and the most frequent characteristics of spinal AVM. Afterwards, clinical and neuradiological features of the diagnosis of this type of malformation are reported from their experience on 8 patients directly observed. 6 out of the 8 patients were operated upon: decompressive laminectomy was performed on 4 of them; in 2 cases spinal AVM was completely removed with clear improvement.

Adult↗
PubMedDate not supplied

[24 hours plasma tryptophan levels in patients with endogenous depression (author's transl)].

The variations of total and free tryptophan during 24 hours were measured in patients with endogenous depression. In depressive patients, plasma tryptophan levels are significantly lower than in control subjects. Plasma tryptophan levels in depressive patients are low during the night (when high at the same hours in normal subjects). The physiopathological mechanisms of such alterations and their possible influence on symptomathology are described.

Adult↗
PubMedDate not supplied

Circadian rhythm of plasma tryptophan in clinically healthy subjects and patients with endogenous depression.

Variations of plasma tryptophan along the 24-h scale are studied in clinically healthy subjects and in patients with endogenous depression. In both groups a circadian rhythm in free and total tryptophan has been found. In healthy subjects plasma tryptophan levels were higher during the night in comparison with daytime hours; the opposite was demonstrated in depressed patients. The possible physiopathological mechanisms underlying the different behavior of plasma tryptophan in the 24-h span, in these two groups of subjects, are discussed.

Adult↗
PubMedDate not supplied

Identification of Listeria monocytogenes by colony hybridization test using the virulence-associated hly and inlA genes as probes.

We developed a method of identification of Listeria monocytogenes based on colony hybridization with nonradioactively labeled DNA probes, represented by the hly and inlA virulence-associated genes. The procedure described in this paper results simple, rapid, specific and reproducible. Since it can be performed in a short time, the above technique can be applied to detect L. monocytogenes from different source and constitutes a noteworthy and alternative tool to identify this gram-positive pathogenic bacterium.

Bacterial Typing Techniques↗