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Biomedical subjects

G Bertoni

Publications and source records attributed to G Bertoni.

At least 55 records · Page 3Linked to original sources
PubMed1998

Analysis of the gene cluster encoding toluene/o-xylene monooxygenase from Pseudomonas stutzeri OX1.

The toluene/o-xylene monooxygenase cloned from Pseudomonas stutzeri OX1 displays a very broad range of substrates and a very peculiar regioselectivity, because it is able to hydroxylate more than one position on the aromatic ring of several hydrocarbons and phenols. The nucleotide sequence of the gene cluster coding for this enzymatic system has been determined. The sequence analysis revealed the presence of six open reading frames (ORFs) homologous to other genes clustered in operons coding for multicomponent monooxygenases found in benzene- and toluene-degradative pathways cloned from Pseudomonas strains. Significant similarities were also found with multicomponent monooxygenase systems for phenol, methane, alkene, and dimethyl sulfide cloned from different bacterial strains. The knockout of each ORF and complementation with the wild-type allele indicated that all six ORFs are essential for the full activity of the toluene/o-xylene monooxygenase in Escherichia coli. This analysis also shows that despite its activity on both hydrocarbons and phenols, toluene/ o-xylene monooxygenase belongs to a toluene multicomponent monooxygenase subfamily rather than to the monooxygenases active on phenols.

Cloning, Molecular↗
PubMed1998

Priming with tat-deleted caprine arthritis encephalitis virus (CAEV) proviral DNA or live virus protects goats from challenge with pathogenic CAEV.

We previously reported that infection of goats with caprine arthritis encephalitis virus (CAEV) tat- proviral DNA or virus results in persistent infection, since the animals seroconverted and direct virus isolation from cultures of blood-derived macrophages was positive. In this study we wanted to determine whether goats injected with CAEV tat- proviral DNA or virus were protected against challenge with the pathogenic homologous virus and to investigate whether CAEV tat- was still pathogenic. All animals injected with CAEV tat- became infected as indicated by seroconversion and virus isolation. Challenge at 8 or 9 months postinfection demonstrated protection in four of four animals injected with CAEV tat- but did not in three of three mock-inoculated challenged goats. Challenge virus was undetectable in the blood macrophages of protected animals during a period of 6 or 10 months postchallenge. In two of four protected animals, however, we were able to detect the challenge wild-type virus by reverse transcriptase PCR on RNA directly extracted from synovial membrane cells surrounding the inoculation site. This result suggests that protection was achieved without complete sterilizing immunity. Animals injected with CAEV tat- and mock challenged developed inflammatory lesions in the joints, although these lesions were not as severe as those in CAEV wild-type-injected goats. These results confirm the dispensable role of Tat in CAEV replication in vivo for the establishment of infection and pathogenesis and demonstrate in another lentivirus infection model the efficacy of live attenuated viruses to induce resistance to superinfection.

Animals↗
PubMed1997

Genetic evidence of separate repressor and activator activities of the XylR regulator of the TOL plasmid, pWW0, of Pseudomonas putida.

The XylR protein encoded by pWW0, the TOL (toluene biodegradation) plasmid of Pseudomonas putida, activates at a distance the transcription of Pu and Ps, which are the two sigma(54)-dependent promoters of the plasmid, but it also downregulates its own sigma(70)-promoter, Pr, which divergently overlaps the upstream activating sites of Ps. All regulatory elements that control Pr activity have been faithfully reproduced in Escherichia coli, and the basis of the autoregulation of XylR transcription has been examined by monitoring the activity in vivo of different combinations of mutant proteins and promoters in rpoN+ and rpoN-genetic backgrounds. By using Ps/Pr regions bearing deleted or offset binding sites for XylR and the sigma(54)-containing RNA polymerase, we could show that formation of a nucleoprotein complex involving the polymerase bound to the divergent promoter Ps is not required for downregulation of Pr. Mutant XylR proteins, G268N and A311V (mutated within the NTP-binding region of XylR) or R453H (affected in multimerization), which are unable to activate sigma(54)-dependent transcription from Ps, were indistinguishable from the wild-type XylR in their ability to repress a reporter Pr-lacZ fusion. Autoregulation of XylR is therefore due exclusively to the binding of the protein to its target sites at the Pr promoter. This allows one to define sensu stricto XylR as a transcriptional repressor, independently of its activator role in other promoters.

Bacterial Proteins↗
PubMed1997

Endoscopic snare papillectomy in patients with familial adenomatous polyposis and ampullary adenoma.

The optimal treatment of adenomas of the papilla of Vater has still not been definitively established, and the endoscopic excision of such lesions has received little attention in the literature. We report here the cases of two patients with familial adenomatous polyposis, in whom ampullary adenomas measuring 8 and 20 mm, respectively, were treated using one-piece snare excision of the lesion together with the papilla (snare papillectomy), followed by temporary biliopancreatic drainage. Procedure-related complications were an oozing-type hemorrhage and a mild pancreatitis, easily controlled by conservative measures. During the 18-month follow-up, one patient had a small recurrence that was successfully retreated. Further endoscopic and biopsy controls were negative. Although limited, our experience and the data in the literature indicate that snare papillectomy is a viable alternative to surgery for benign ampullary adenomas. Excising both the lesion and the papilla offers good oncological debridement and, unlike laser or thermal ablation, allows a complete histological evaluation of the pathological tissue. However, snare papillectomy should always be associated with temporary biliopancreatic drainage before or after the procedure in order to prevent ductal obstruction and serious pancreatitis. This maneuver should therefore preferably be performed by experienced endoscopists trained in therapeutic endoscopic retrograde cholangiopancreatography and hemostatic techniques.

Adenoma, Villous↗
PubMed1997

AFLP markers for DNA fingerprinting in cattle.

This work reports on use of the recently described amplified fragment length polymorphism (AFLP) technology for DNA fingerprinting in cattle. The AFLP technology produces molecular markers through the high-stringency polymerase chain reaction (PCR)-amplification of restriction fragments that are ligated to synthetic adapters and amplified using primers, complementary to the adapters, which carry selective nucleotides at their 3' ends. While, for plants, the double digestion of genomic DNA with EcoRI and MseI is suggested, in mammals the enzyme combination EcoRI/TaqI produces clearer and more polymorphic AFLP patterns. In a sample of 47 Italian Holstein genotypes, 16 EcoRI/TaqI primer combinations identified 248 polymorphic bands in a species known for its low level of restriction polymorphism. In spite of the low information content carried by each AFLP polymorphism (average polymorphism information content = 0.31), the number of fragments revealed by each primer combination increased significantly the level of genetic information gained in each experiment. AFLP patterns are reproducible in independent experiments and polymorphic fragments segregate in cattle families according to Mendelian rules.

Animals↗
PubMed1997

Anatomo-radiographic study of prenatal development of bovine fetal teeth.

The aim of this study was to improve the knowledge of the time of appearance of dental germs and their morphological development until birth in bovine fetuses. Skulls and isolated mandibles of 35 Simmenthal bovine fetuses, of both sexes and ages from 97 to 280 days old were examined. The radiographic examination was performed with high definition and mamofilms. The exposure values ranged from 36 kV-6 mAs to 55 kV-12 mAs according to skull dimensions. In this study, the first dental germ was observed at 97 days, identified as the third maxillar premolar tooth. Through the morphological study and accurate description of the lingual and vestibular aspect of the occlusive surface of the teeth, three roots for the third and fourth maxillar premolar teeth and two for the second maxillar premolar tooth were observed. Two roots for the second and third mandibular premolar teeth and three for the fourth mandibular premolar tooth were also observed. The germ of the first mandibular molar tooth was seen at 140 days and the first of the maxillar arch at 280 days.

Animals↗
PubMed1997

Caprine arthritis encephalitis virus dysregulates the expression of cytokines in macrophages.

Caprine arthritis encephalitis virus (CAEV) is a lentivirus of goats that leads to chronic mononuclear infiltration of various tissues, in particular, the radiocarpal joints. Cells of the monocyte/macrophage lineage are the major host cells of CAEV in vivo. We have shown that infection of cultured goat macrophages with CAEV results in an alteration of cytokine expression in vitro. Constitutive expression of interleukin 8 (IL-8) and monocyte chemoattractant protein 1 (MCP-1) was increased in infected macrophages, whereas transforming growth factor beta1 (TGF-beta1) mRNA was down-regulated. When macrophages were infected with a CAEV clone lacking the trans-acting nuclear regulatory gene tat, IL-8 and MCP-1 were also increased. No significant differences from cells infected with the wild-type clone were observed, suggesting that Tat is not required for the increased expression of IL-8 and MCP-1 in infected macrophages. Furthermore, infection with CAEV led to an altered pattern of cytokine expression in response to lipopolysaccharide (LPS), heat-killed Listeria monocytogenes plus gamma interferon, or fixed cells of Staphylococcus aureus Cowan I. In infected macrophages, tumor necrosis factor alpha, IL-1beta, IL-6, and IL-12 p40 mRNA expression was reduced in response to all stimuli tested whereas changes in expression of granulocyte-macrophage colony-stimulating factor depended on the stimulating agent. Electrophoretic mobility shift assays demonstrated that, in contrast to effects of human immunodeficiency virus infection of macrophages, CAEV infection had no effect on the level of constitutive nuclear factor-kappaB (NF-kappaB) activity or on the level of LPS-stimulated NF-kappaB activity, suggesting that NF-kappaB is not involved in altered regulation of cytokine expression in CAEV-infected cells. In contrast, activator protein 1 (AP-1) binding activity was decreased in infected macrophages. These data show that CAEV infection may result in a dysregulation of expression of cytokines in macrophages. This finding suggests that CAEV may modulate the accessory functions of infected macrophages and the antiviral immune response in vivo.

Animals↗
PubMed1997

Expression of cytokine mRNA in lentivirus-induced arthritis.

Infection of goats with the lentivirus caprine arthritis encephalitis virus (CAEV) leads to persistent infection and development of chronic arthritis. We analyzed the expression of cytokines and viral RNA in the joints of goats at early time points after experimental infection with CAEV and in those of animals suffering from chronic arthritis as a result of natural infection. In situ hybridization experiments showed that the pattern of cytokine expression in caprine arthritis was similar to that found in rheumatoid arthritis (RA), with a few cells expressing the lymphocyte-derived cytokines interferon (IFN)-gamma and interleukin (IL)-2 and rather more cells expressing monocyte chemoattractant protein (MCP)-1, IL-6, and tumor necrosis factor (TNF)-alpha. IFN-gamma mRNA expression in experimentally infected joints peaked at day 12 and was mostly detected in areas containing viral RNA. At later time points, no IFN-gamma- or virus-expressing cells were found in inflamed joints but both were again detected in goats with severe arthritis. Interestingly, at the clinical stage of arthritis reflecting the chronic stage of infection, the inflammatory lesion was found to be immunologically compartmentalized. Humoral immune responses and cell-mediated immune responses appeared to concurrently occur in distinct areas of the synovial membrane.

Animals↗
PubMed1996

Organisation of the tmb catabolic operons of Pseudomonas putida TMB and evolutionary relationship with the xyl operons of the TOL plasmid pWW0.

In Pseudomonas putida (Pp) TMB the genes involved in the catabolism of methyl-substituted aromatic hydrocarbons 1,2,4-trimethylbenzene, m- and p-xylene (tmb operon), are functionally and genetically homologous to the xyl genes of the plasmid pWW0, but are chromosomally encoded. We have analysed by cloning. Southern blotting and sequencing of selected regions the organisation of the tmb cluster. This analysis shows that the structural and regulatory genes of the tmb and xyl systems exhibit a high degree of homology and are similarly organised in operons. However the operons are differently arranged on the Pp TMB chromosome and on the pWW0 plasmid. Comparison of the two systems suggests that the operon arrangement found in pWW0 may have originated from that found in Pp TMB via cointegration mediated by replicative transposition or by intermolecular recombination between two copies of the insertion element IS1246.

Base Sequence↗
PubMed1996

Expression of TNF alpha in arthritis caused by caprine arthritis encephalitis virus.

Goats infected with caprine arthritis encephalitis virus (CAEV) develop chronic arthritis sharing many features with human rheumatoid arthritis (RA). TNF is thought to be a key mediator contributing to the formation of the arthritic lesion in RA. We studied this cytokine in goats suffering from chronic arthritis. TNF alpha expressing cells were detected by in situ hybridization in synovial membranes of arthritic carpal joints. Expression of TNF alpha did not correlate with the degree of viral replication as assessed by in situ hybridization for viral RNA. In line with the lack of correlation between the degree of viral replication and TNF expression in vivo, we failed to detect increased cytokine RNA in goat macrophages infected with CAE virus in vitro and no TNF protein was found in culture supernatants. In addition, virus infection failed to prime goat macrophages for enhanced TNF expression in response to lipopolysaccharide. Taken together, these findings argue against a direct role of CAE virus in increasing the expression of TNF alpha in caprine arthritis.

Animals↗
PubMed1996

High prevalence of adenomas and microadenomas of the duodenal papilla and periampullary region in patients with familial adenomatous polyposis.

BACKGROUND: Patients with familial adenomatous polyposis (FAP) are traditionally considered to be at high risk for duodenal-papillary and periampullary adenomas and cancer. AIM: To evaluate prospectively the prevalence, histology and clinical significance of ampullary and periampullary macroscopic and microscopic lesions in our population of affected patients. SETTING: Three gastroenterological departments of northern Italian hospitals. PATIENT AND METHODS: Twenty-five affected patients were carefully investigated over a 24-month period by end-viewing and side-viewing upper panendoscopy. Biopsies were performed on representative macroscopic lesions and randomly on normal-appearing papillary and periampullary mucosa. RESULTS: Seven patients had macroscopic adenomas of the duodenal papilla, three of the periampullary region and five at both sites (cumulative prevalence 40%). An additional six patients had macroadenomas in the rest of the duodenum (overall prevalence 64%). Microscopic adenomas were identified in nine and two patients in the papilla and periampullary region, respectively, and in three at both sites (overall prevalence 44%). Thus, a total of 17 (68%) patients presented macro- or microadenomas at these locations. The prevalence rose to 72%, when a further patient with macroadenomas in the rest of the duodenum only was included. Malignancy was not encountered and severe dysplasia was observed only in a macroadenoma of the second duodenal portion. A higher frequency of macroadenomas in the papilla and periampullary region was significantly correlated with the presence and number of such lesions in the rest of the duodenum (P = 0.04). No other significant association was detected either between micro- or macroadenomas at different sites or with the demographic, clinical and pathological features. CONCLUSION: This study confirms that the duodenal papilla and periampullary region are sites with high prevalence of macro- and microscopic adenomas in patients with FAP. However, our data do not seem to support a higher frequency and malignancy potential of such lesions as compared to polyps in the rest of the duodenum. Nevertheless, these findings warrant a periodic, careful examination of the duodenum with either end-viewing or side-viewing endoscopy, the need for random biopsies of the papilla and periampullary region and the removal of any larger or rapidly growing lesions detected.

Adenoma↗
PubMed1996

Osteogenesis of the fetal bovine skull.

The research was carried out in order to study the osteogenesis of skull bones in bovine fetuses. A total of 24 fetuses were considered. The age of specimens ranged from 52 to 212 days. After silver-nitrate impregnation of the skulls, the specimens were examined radiologically using latero-lateral, latero-medial, and dorso-ventral projections.

Aging↗
PubMed1996

Cloning of the genes for and characterization of the early stages of toluene and o-xylene catabolism in Pseudomonas stutzeri OX1.

In order to study the toluene and o-xylene catabolic genes of Pseudomonas stutzeri OX1, a genomic library was constructed. A 28-kb EcoRI restriction endonuclease DNA fragment, cloned into the vector plasmid pLAFR1 and designated pFB3401, permitted Pseudomonas putida PaW340 to convert toluene and o-xylene into the corresponding meta-ring fission products. Physical and functional endonuclease restriction maps have been derived from the cloned DNA fragment. Further subcloning into and deletion analysis in the Escherichia coli vector pGEM-3Z allowed the genes for the conversion of toluene or o-xylene into the corresponding catechols to be mapped within a 6-kb region of the pFB3401 insert and their direction of transcription to be determined. Following exposure to toluene, E. coli cells carrying this 6-kb region produce a mixture of o-cresol, m-cresol, and p-cresol, which are further converted to 3-methylcatechol and 4-methylcatechol. Similarly, a mixture of 2,3-dimethylphenol and 3,4-dimethylphenol, further converted into dimethylcatechols, was detected after exposure to o-xylene. The enzyme involved in the first step of toluene and o-xylene degradation exhibited a broad substrate specificity, being able to oxidize also benzene, ethylbenzene, m-xylene, p-xylene, styrene, and naphthalene. Deletions of the 6-kb region which affect the ability to convert toluene or o-xylene into the corresponding methylphenols compromise also their further oxidation to methylcatechols. This suggests that a single enzyme system could be involved in both steps of the early stages of toluene and o-xylene catabolism.

Benzene↗
PubMed1996

Triple therapy with azithromycin, omeprazole, and amoxicillin is highly effective in the eradication of Helicobacter pylori: a controlled trial versus omeprazole plus amoxicillin.

BACKGROUND: Azithromycin is a new-generation, acid-stable macrolide antibiotic that achieves remarkably high concentrations in gastric tissue, persisting above the MIC90 for Helicobacter pylori over a 5-day period after a single 500-mg oral dose. METHODS: We evaluated a new metronidazole-free triple therapy with omeprazole 20 mg b.i.d. plus amoxicillin 1 g b.i.d. (both for 14 days) and azithromycin 500 mg mane (for the first 3 days only) (group I) versus double therapy with omeprazole 20 mg b.i.d. plus amoxicillin 1 g t.i.d., both for 14 days (group II). H. pylori status was determined by urease test and histology before and 6 wk after completion of therapy. RESULTS: Ninety-two patients with peptic ulcer disease or nonulcer dyspepsia completed the study. H. pylori infection was eradicated in 44 (91.6%) of 48 patients randomized to receive triple therapy versus 26 (59.1%) of 44 who received double therapy (p < 0.001). Smoking, but not omeprazole pretreatment, proved to be a risk factor for treatment failure only in the double-therapy group (p = 0.05). All ulcers healed by the time of the 8-wk endoscopic control. Side effects, usually minor, were recorded in 12.5% and 9.1% of patients, respectively (NS), but therapy had to be discontinued in one patient in group I and in three in group II (NS). CONCLUSIONS: Two-week triple therapy with omeprazole, amoxicillin, and (for the first 3 days) low-dose azithromycin is highly effective in eradicating H. pylori. This regimen is safe and well-tolerated, and we recommend that it be used as first-line treatment, as an alternative to less-effective omeprazole-amoxicillin double therapy. Moreover, azithromycin appears to be a new, promising antibiotic for future innovative anti-H. pylori combinations.

Adult↗