Genetic markers to discriminate benign and malignant thyroid nodules with undetermined cytology in an area of borderline iodine deficiency.

BACKGROUND: Fine needle aspiration (FNA) with cytologic evaluation is the most reliable tool for malignancy prediction in thyroid nodules, but cytologic diagnosis remains undetermined for 20% of nodules. AIM: We investigated the diagnostic potential of a set of 6 marker genes to distinguish benign and malignant thyroid nodules. SUBJECTS AND METHODS: The prospective study included 153 thyroid samples obtained by FNA of thyroid nodules from 151 patients (56 benign, 43 malignant, and 54 nodules with undetermined cytology). Gene expression was evaluated by quantitative realtime PCR and statistical analysis of data was performed. All samples were analyzed for V600E BRAF mutation. RESULTS: A decrease in TTF3 and HGD1 expression was observed in malignant nodules with respect to benign ones, while an increase in PLAB expression was demonstrated in these nodules. The decision model was valid for 88 of 99 cases of benign and malignant nodules, with a total of 11 false positive or negative predictions. The obtained malignant/benign phenotype prediction was also valid for 37 of 54 cases of nodules with undetermined cytology with a total of 8 false positive and 9 false negative predictions. V600E BRAF gene mutation was demonstrated in 19/43 malignant nodules, in 0/56 benign nodules, and in 1/54 undetermined nodules. CONCLUSIONS: The expression profiles of genes (TFF3, HGD1, and PLAB) allowed a good prediction for the differentiation of benign thyroid lesions and thyroid cancer starting from cells of FNA; however, this assay showed limitations when applied to discriminate thyroid nodules with undetermined cytology.

Unusual species of campylobacters isolated in the Siena Tuscany area, Italy.

From January 1989 to December 1990, stool samples from 288 children with enteritis were examined for the presence of unusual campylobacters which represented about 20% of all campylobacteria isolated when the filtration technique was used. The isolation percentage was the following: C. jejuni ss. jejuni 6.9%; C. coli 2%; C. jejuni ss. doylei, C. upsaliensis and C. concisus each 0.7%. The atypical Campylobacter isolates were examined for their virulence characteristics. Toxin profiles based on cytotonic, cytotoxic and cytolethal distending factors were determined after analysis responses in Vero, CHO and HeLa cells. Adhesivity and invasivity tests were performed on Intestine 407 cells. No strain was cytotoxic. C. jejuni ss. doylei and C. concisus induced an elongation of CHO cells (a cytotonic-like effect). C. upsaliensis strains provoked a cytolethal distending effect. No strain adhered to cells in vitro. Our results suggest that the filtration technique is excellent for the isolation of atypical campylobacters and indicate that the unusual Campylobacter isolates could be potentially virulent.

Species, biotype and serogroup of Campylobacter spp. isolated from children with diarrhoea over a ten-year period.

From 1981 to 1990, stool samples from 6403 gastroenteritis cases were examined for the presence of campylobacters as well as Salmonella, Shigella, Aeromonas species and Yersinia enterocolitica. The percentages of isolation were the following: campylobacters 10.8 (86.1% of isolates were C. jejuni and 13.9% were C. coli), Salmonella spp. 8.4, Aeromonas spp 1.4, Yersinia enterocolitica 0.3. Shigella spp. were isolated only occasionally. Predominant biotypes of campylobacters were C. jejuni I (69.5%), C. jejuni II (29.5%) and C. coli I (92.7%). The six most common LIO serogroups-36; 4; 1; 28.53; 11; 2-accounted for 50% ca. of typable strains. Campylobacters are the most common etiological agent of bacterial enteritis in children living in this area of Tuscany. The species and serogroup determination can be useful from an epidemiological point of view.

In vitro virulence factors of Arcobacter butzleri strains isolated from superficial water samples.

Eighteen isolates of A. butzleri from river water samples were examined for their biotype, serogroup and putative virulence characteristics. Toxin profiles based on cytotonic, cytotoxic and cytolethal distending factors were determined after analysis responses in Vero and CHO cells Adhesivity and invasivity tests were performed on HeLa and Intestine 407 cells. Six biotypes and five serogroups were determined in our isolates. All strains but one induced cytotoxic effects on cells in culture. The cytotoxic negative strain caused elongation of CHO cells (a cytotonic-like effect). This strain was the only one which adhered to cells in vitro. Invasiveness was never observed. Our results show a phenotypic heterogeneity of arcobacters isolated from environmental sources, and indicate that some strains could be potentially virulent.

Occurrence of killer yeasts in spontaneous wine fermentations from the tuscany region of Italy.

The occurrence of killer yeasts in an area of Tuscany (central Italy) was studied. Killer yeasts were found in 88% of spontaneous wine fermentations from 18 wineries. The incidence of killers varied with respect to fermentation stage and vintage period, increasing from the first vintage to successive ones and from the commencement to the end of fermentation. At the end of fermentation, the proportion of killer strains relative to total yeast population was below 25% in 15 cases, above 75% in 6 cases, from 25 to 50% in 5 cases, and from 50 to 75% in 3 cases. Karyotype analysis also showed a mixed killer population in the fermentations in which the killers dominated.

Comparisons between degree of histological gastritis and DNA fingerprints, cytotoxicity and adhesivity of Helicobacter pylori from different gastric sites.

Thirty-six isolates of H. pylori from up to three gastric biopsy sites (antrum, corpus and fundus) from 13 patients in Italy with different degrees of histological gastritis were investigated. All strains were tested for motility, cytotoxicity and degree of adhesion, and were typed by analysis of ribosomal RNA gene patterns (ribopatterns). Seventeen different DNA types (ribotypes) were identified, with each patient possessing H. pylori of one or more unique types. Only two patients had identical H. pylori at three sites. Most patients had H. pylori with different ribotypes or subtypes, but nine strains were not typable. Five patients had the same strain colonizing two of the three sites and atypical strains were mostly from the antrum. A complex pattern of H. pylori colonization in the stomach of some individuals was evident and suggested multiple sources of infection. No consistent associations were detected between degree of gastritis and adherence, cytotoxicity and motility but a 2.56Kb rRNA gene fragment that had a higher frequency in strains associated with severe gastritis than mild gastritis, may provide a useful molecular marker for future pathogenicity studies.

Method and parameters for genetic transformation of Streptococcus sanguis Challis.

A simple procedure for genetic transformation of Streptococcus sanguis Challis was developed and standardized. During the exponential phase of growth, cells became competent while growing as diplococci in broth containing 10% foetal calf serum. High levels of competence were maintained by the cultures for 60 min. Competent cells could be stored frozen without loss of competence for at least three years. Using total chromosomal DNA as donor, the dose-response curve for transformation of a point mutation (streptomycin resistance) showed one-hit kinetics, as the DNA concentration varied from 0.000001 to 10 micrograms/ml. At 10 micrograms/ml, more than 2.2% of the colony-forming units were transformed to streptomycin resistance, while transforming activity remained detectable with 1 pg of DNA/ml. Optimal time of exposure of competent cells to transforming DNA was 30 min. The transformation reaction was inhibited at 0 and 4 degrees C, whereas it occurred efficiently both at 25 and 37 degrees C.

Cytotoxin production by Campylobacter pylori strains isolated from patients with peptic ulcers and from patients with chronic gastritis only.

A total of 66.6% of Campylobacter pylori strains isolated from patients with peptic ulcers produced a cytotoxin active against mammalian cells in vitro, versus 30.1% of strains isolated from patients with chronic gastritis of various degrees of severity only. This difference was statistically significant and suggests that the toxic substance could be involved in the development of peptic ulcers.

Host-vector system for integration of recombinant DNA into chromosomes of transformable and nontransformable streptococci.

We describe a genetic system in which transformation of Streptococcus pneumoniae and Streptococcus sanguis was used to insert recombinant DNA into the conjugative chromosomal element omega (cat tetM) 6001 (omega 6001). The element containing the recombinant DNA was then transferred by conjugation to the chromosome of transformable and nontransformable streptococci. When Escherichia coli plasmid pDP36 was used as donor in transformation, it was capable of inserting 5.9 kilobases of heterologous DNA into the chromosome of competent streptococcal strains carrying omega 6001; the transformants were scored for erythromycin resistance. Genetic analysis showed that in a fraction of the erythromycin-resistant transformants the integration via flanking homology of the heterologous DNA caused inactivation of the tetM gene of omega 6001. By analyzing the stability of the resistance markers, we found that stable integration of heterologous DNA was achieved only in the erythromycin-resistant, tetracycline-sensitive transformants. It was possible to detect conjugal transfer of the heterologous sequences from stable transformants to strains of S. pneumoniae, S. sanguis, Streptococcus pyogenes, and Streptococcus faecalis. The omega 6001-pDP36 host-vector system opens new possibilities for gene transfer in streptococci. By this method cloned streptococcal DNA (possibly mutagenized in vitro) can be returned to the original host, greatly facilitating complementation tests and fine physiological studies.

Production of serum-opacity factor by Streptococcus pyogenes strains isolated from pharyngitis in children. Prevalence of "rheumatogenic" M types among OF-negative strains.

Two hundred ten S. pyogenes strains isolated in 1979, 1980 and 1984 from children with pharyngitis were here examined for properties which might be relevant to their rheumatogenic potential. Strains were first tested for the production of streptococcal serum-opacity factor and, among those scored as OF-negative, the presence was then verified of M types which have been epidemiologically related to rheumatic fever. Members of "rheumatogenic" M types are present among strains causing pharyngitis in children, which, however, also include a considerable proportion of OF-positive, probably non-rheumatogenic, strains. The results are discussed in the light of the low incidence of rheumatic fever in this country.

Properties of an E. coli O26 mutant with modified cell wall and improved efficiency as recipient in conjugation for an FII plasmid.

Among populations of an E. coli O26 strain two types of mutants have been found to be present which act as better recipients in conjugation for an FII plasmid. Some properties of one of these mutants, O26SMB9, are here described. They indicate that a defect in the cell-wall structure has occurred which corresponds to a smooth----semirough transition.

Two different types of conjugation-prone recipients for an FII plasmid in populations of an E. coli O26 strain.

In populations of an E. coli O26 strain three types of cells can be found which show different degrees of recipient ability in conjugation for an FII plasmid. In this paper the characterization of the plasmid used, pSMB35, is described and the conjugation-proficient mutants, O26SMB9 and O26SMB11, are compared for some of their properties.