Genetic heterogeneity of variable number tandem repeats in thymidylate synthase gene in colorectal cancer patients

PURPOSE

To analyze the genetic variability in a variable number of tandem repeats (VNTR) in the thymidylate synthase (TS) enhancer promoter region and assess the influence of functional alterations in mismatch repair genes by analyzing constitutional and tumoral DNA from patients with colorectal adenocarcinoma with a high microsatellite instability (MSI-H) or microsatellite stability (MSS) status.

PATIENTS AND METHODS

Patients who underwent surgery for colorectal adenocarcinoma were selected from the colorectal database of our institute and, on the basis of MSI status, assigned to a study group and a control group: group A, MSI-H; group B, MSS. Microsatellite status was investigated using the Bethesda recommended panel (BAT-26, BAT-25, D2S123, D5S346, D17S250). In MSI-H patients an additional analysis was made of the microsatellite loci D18S61 and D18S58, both mapping in the region containing the TS gene (18p11.2-11.32). Based on the number of altered microsatellites (> or = 2, 1, or 0), tumors were considered as having high (MSI-H) or low (MSI-L) instability or microsatellite stability (MSS), respectively. Genotyping for thymidylate synthase promoter polymorphism was carried out on constitutional and tumor DNA of each patient by PCR amplification of the polymorphic region.

RESULTS

MSI-H was found in 55 patients (group A) and MSS in 50 patients (group B). In none of the MSI-H patients was microsatellite instability found in the additional D18S61 and D18S58 loci. In five group A and ten group B cases the analysis was not performed because constitutional DNA and/or tumoral DNA were not amplifiable. Homozygotes for the triple repeat variant (3R/3R) displayed only the large PCR product, homozygotes for the double repeat variant (2R/2R) displayed only the smaller PCR product, while heterozygotes (2R/3R) displayed both the larger and smaller PCR products. In 3/50 (6%) group A patients and 5/40 (12%) group B patients repeat variations were found in tumoral DNA.

CONCLUSION

Our findings demonstrate that there is genetic homogeneity between constitutional and tumoral DNA but do not support the hypothesis that mismatch repair genes are involved in VNTR recombinant events in TS gene variability.

Subcortical nodular heterotopia: a functional MRI and somatosensory evoked potentials study

Subcortical nodular heterotopia (SNH) associated with refractory epilepsy may be surgically treated, and a positive outcome can be expected following the complete excision of the malformed tissue. Recent functional neuroimaging studies have suggested the possible functional relevance of cerebral malformations, and may make it possible to improve presurgical planning, thus allowing extended resections and minimising post-operative deficits. We here report the case of a 19-year-old man with epilepsy and a giant SNH associated with diffused abnormal gyrations of the right temporal-parietal regions. Cortical functional organisation was investigated by means of functional magnetic resonance imaging (MRI) during sensory and motor tasks, and somatosensory evoked potentials. The results revealed enlarged and displaced motor and sensory cortical areas with heterotopic tissue functional activation. The relevance of these findings is discussed in the light of the possible surgical treatment of drug-refractory epilepsy associated with cerebral malformations: surgical treatment based on conventional MRI studies alone, without taking the functional nature of dysplastic tissues into account, may lead to considerable side effects.

Development of polythene films for food packaging activated with an antilisterial bacteriocin from Lactobacillus curvatus 32Y

AIMS

The aims of this work were to (i) use a bacteriocin produced by Lactobacillus curvatus 32Y active against Listeria monocytogenes to activate polythene films by different methods, (ii) implement a large-scale process for antilisterial polythene films production and (iii) verify the efficacy of the developed films in inhibiting the growth of L. monocytogenes during the storage of meat products.

METHODS AND RESULTS

The film was made active by using the antilisterial bacteriocin 32Y by Lact. curvatus with three different procedures: soaking, spraying and coating. The antimicrobial activity of the activated films was tested in plate assays against the indicator strain L. monocytogenes V7. All the used procedures yielded active polythene films although the quality of the inhibition was different. The coating was therefore employed to develop active polythene films in an industrial plant. The antimicrobial activity of the industrially produced films was tested in experiments of food packaging involving pork steak and ground beef contaminated by L. monocytogenes V7 at roughly 10(3) CFU cm(-2) and gram respectively. The results of the challenge tests showed the highest antimicrobial activity after 24 h at 4 degrees C, with a decrease of about 1 log of the L. monocytogenes population.

CONCLUSIONS

Antimicrobial packaging can play an important role in reducing the risk of pathogen development, as well as extending the shelf life of foods.

SIGNIFICANCE AND IMPACT OF THE STUDY

Studies of new food-grade bacteriocins as preservatives and development of suitable systems of bacteriocin treatment of plastic films for food packaging are important issues in applied microbiology and biotechnology, both for implementing and improving effective hurdle technologies for a better preservation of food products.

Genetic variation in carbon isotope discrimination in six European populations of Castanea sativa Mill. originating from contrasting localities

The objective of this study was to evaluate the variability of physiological performances of Castanea sativa Mill. in relation to drought tolerance, among and within European populations coming from contrasting environmental conditions. Forty-eight open-pollinated families from a stratified sample (temperature/precipitation) of six naturalized populations from Spain, Italy and Greece were grown for one growth period under two temperature regimes (25 and 32 degrees C), in combination with two watering regimes in growth chambers. Complementary to growth traits analysed in a previous study, carbon isotope discrimination (Delta), a complex physiological trait involved in acclimation and adaptive processes, was studied. anova indicated significant Delta variability for C. sativa populations across Europe and, thereby, variation in adaptedness to drought. The European pattern of Delta variability matches the previously reported one for the centre of origin of C. sativa (Ponto-Caucasian region). This suggests that common mechanisms of drought adaptedness, involving both genetic and physiological determinants, give C. sativa the capacity to colonize a wide range of site conditions. The highest Delta values, indicating the lowest water-use efficiency (WUE), were found within each treatment for populations originating from Mediterranean drought-prone sites. These populations also had the highest phenotypic plasticity of Delta. Significant among-family genetic variation in Delta was found. The heritability based on the joint anova was estimated at 0.31 +/- 0.07. The estimates of the coefficients for the additive variance varied in the range 2.6-4.0%, suggesting possibilities for selection on WUE and adaptedness to drought. The genetic correlations between Delta and growth traits were generally strong and negative, especially in the two high temperature treatments.

PCR detection of staphylococcal enterotoxin genes in Staphylococcus spp. strains isolated from meat and dairy products. Evidence for new variants of seG and seI in S. aureus AB-8802

AIMS

Evaluation of the occurrence of most known staphylococcal enterotoxin (SE) genes, egc (enterotoxin gene cluster) and TSST1 (toxic shock syndrome toxin 1) gene in both coagulase-positive (CPS) and coagulase-negative (CNS) staphylococcal strains isolated from meat and dairy products.

METHODS AND RESULTS

Specificity and reliability of the PCR detection methods used were ascertained by using nine reference strains of Staphylococcus (S. aureus) harbouring SE genes (seA to seE; seG, seH, seI, seM, seJ, seN and seO) and egc (containing the following sequence of genes: seO, seM, seI, phient1, phient2, seN and seG). Of 109 wild Staphylococcus spp. strains analysed, only 11 S. aureus strains were SE and/or TSST1 PCR-positive. The last 11 strains also appeared to harbour the egc. Restriction endonuclease analysis of part of the egc of both reference and wild strains showed that different variants of the egc exist. Moreover, nucleotide sequences of seG and seI indicate that the egc of the strain AB-8802 is characterized by the presence of variants of these enterotoxins (seGv and seIv).

CONCLUSIONS

The occurrence of SE genes in CNS and other non-S. aureus species isolated from Napoli-type salami, raw water buffalo milk and natural whey cultures used for mozzarella cheese manufacturing is very rare.

SIGNIFICANCE AND IMPACT OF THE STUDY

During this study it was shown that at least five different egc may exist in S. aureus. A thorough study of egc polymorphism should provide further insight into the phylogenetics of the egc.

Diversity and dynamics of communities of coagulase-negative staphylococci in traditional fermented sausages

AIMS

Evaluation of composition and evolution of the coagulase-negative staphylococci (CNS) communities in two traditionally fermented sausages (salsiccia and soppressata lucana) produced in Basilicata, southern Italy.

METHODS AND RESULTS

A culture-dependent approach based on isolation on selective media and identification with phenotypic and molecular methods was used. Phenotypic data of 471 strains were analysed by multivariate statistical methods by using 28 strains from culture collections and 48 strains identified by molecular methods (such as 16S rDNA sequencing, species-specific PCR assays, intergenic spacer region-PCR and PCR-denaturing gradient gel electrophoresis) as a reference. The CNS microflora of the sausages was found to be dominated by different biotypes of Staphylococcus xylosus (51.2%), followed by S. pulvereri/vitulus, S. equorum and S. saprophyticus (13.4, 10.2 and 10%, respectively). Other species (S. succinus, S. pasteuri, S. epidermidis, S. warneri and Macrococcus caseolyticus) were also present at lower levels. Identification of 25% of the isolates was impossible.

CONCLUSIONS

The composition of CNS communities varied significantly with sausage type, plant and ripening time and clear differences were found among communities of salsiccia and soppressata at the end of ripening.

SIGNIFICANCE AND IMPACT OF THE STUDY

Phenotypic characterization, supported by molecular and statistical analyses, can be considered a useful approach for typing a large number of isolates and for monitoring the evolution of staphylococcal communities during sausage fermentation but does not always provide a satisfactory identification of the isolates.

Comparative mapping between quercus and castanea using simple-sequence repeats (SSRs)

Simple sequence repeat (SSR) markers from Quercus and Castanea were used for comparative mapping between Quercus robur (L.) and Castanea sativa (Mill.). We tested the transferability of SSRs developed in Quercus to Castanea and vice-versa. In total, 47% (25) of the Quercus SSRs and 63% (19) of the Castanea SSRs showed a strong amplification product in the non-source species. From these 44 putative comparative anchor tags, 19 (15 from Quercus and 4 from Castanea) were integrated in two previously established genetic linkage maps for the two genera. SSR loci were sequenced to confirm the orthology of the markers. The combined information from both genetic mapping and sequence analysis were used to determine the homeology between seven linkage groups, aligned on the basis of pairs or triplets of common markers, while two additional groups were matched using a single microsatellite marker. Orthologous loci identified between Q. robur and C. sativa will be useful as anchor loci for comparative mapping studies within the Fagaceae family.

Experience with immunomodulatory treatments in Rasmussen's encephalitis

The authors investigated immunomodulatory treatments in 15 patients with Rasmussen encephalitis (RE) (14 with childhood and one with adolescent onset RE). Positive time-limited responses were obtained in 11 patients using variable combinations of corticosteroids, apheresis, and high-dose IV immunoglobulins. Although surgical exclusion of the affected hemisphere is the only treatment that halts disease progression, immunomodulation can be considered when early surgery is not feasible, in late-onset patients with slower disease progression, and in the few cases of bilateral disease.

Exercise testing as a predictor of surgical risk after pneumonectomy for bronchogenic carcinoma

The aim of the present investigation was to evaluate the predictive value of a symptom-limited exercise test in predicting postoperative morbidity and mortality in patients submitted to pneumonectomy. The study was conducted in 150 patients (mean age, 57.1). Forty-four patients (29.3%) had postoperative complications. Four patients (2.7%) died within one month of the pneumonectomy. Patients with complications had significantly lower VO2max. The incidence of complications in relation to the amount of oxygen consumption showed that with the progressive decrease of oxygen consumption there was a progressive increase in frequency of complications. In particular patients with VO2max < 50% of predicted should be considered at high risk of morbidity and mortality from cardiopulmonary causes. This predictive capacity of VO2max was more evident in patients with a preoperative FEV1 less than 70% of predicted. The present data support the suggestion that exercise testing could be a useful adjunt in the evaluation of postoperative risk for pneumonectomy, especially in patients with obstructive pulmonary disease.

Effect of proteolytic starter cultures as leavening agents of pizza dough

Lactic acid bacteria (LAB) and yeasts were selected on the basis of in vitro proteolytic activity against wheat gluten protein and then assayed as leavening agents for pizza dough. Trials were carried out to compare a proteolytic starter (Prt(+)), consisting of Lactobacillus sakei T56, Weissella paramesenteroides A51 and Candida krusei G271, and a non-proteolytic starter (Prt(-)), consisting of Lb. sakei T58, W. paramesenteroides A58 and Saccharomyces cerevisiae T22. The proteolytic activity of the starter cultures was monitored immediately after mixing of the dough and throughout the fermentation process. The proteolytic activity was assessed by analysing the salt-soluble protein (SSP) and the dioxane-soluble protein (DSP) fractions of the pizza dough by discontinuous SDS-PAGE. Only the Prt(+) starter exhibited considerable qualitative and quantitative changes in the electrophoretic patterns of the protein fractions extracted. After the fermentation, the Prt(+) and Prt(-) doughs were tested to evaluate the influence of the proteolytic activity on the mechanical properties of the dough before and after baking. Indications emerged suggesting an influence of the proteolytic activity on the viscoelasticity of pizza dough. The pizza dough with Prt(+) strains showed an increase in viscous properties during the fermentation as compared with the Prt(-) dough. Moreover, an increase in the firmness of the crumb was observed in Prt(+) baked pizza dough.

Effect of an intensive chemotherapy followed by mediastinal irradiation on pulmonary and cardiac function in advanced Hodgkin's disease

Mediastinal irradiation combined with chemotherapy in patients with Hodgkin's disease have been associated with cardiopulmonary toxic effects that can last over the years. In this study we monitored pulmonary and cardiac function in 39 patients affected by advanced Hodgkin's disease (stage II B-III and IV) with mediastinal involvement and submitted to an intensive chemotherapy regimen (epirubicin, vincristine, ciclophosphamide, and etoposide) followed by involved field irradiation. Pulmonary function was verified with chest x-ray, spirometric parameters, arterial blood gas analysis, single breath CO transfer factor (DLCO), and its components Dm and Vc. Cardiac function was verified with electrocardiogram (EKG) and left ventricular ejection fraction (LVEF) by means of radionuclide angiocardiography. The median follow-up was 40 months. Spirometric parameters did no show modifications at the end of treatment, on the contrary they improved during the follow-up. Chest x-ray showed radiographic parenchimal damage in 51% of patients. DLCO remained constantly decreased. sEKG did not show significant modification, whereas LVEF significantly decreased at the end of treatment and remained persistently decreased during follow-up. None of the patients with reduction of DLCO or LVEF showed clinical symptoms of heart and pulmonary dysfunctions. One patient, 49 years old, suffered from myocardial infarction 25 months after the completion of radio-chemotherapy. These data indicate that this combined regimen can induce persistent pulmonary and cardiac damages at subclinical level.

Proteolytic activity of Staphylococcus xylosus strains on pork myofibrillar and sarcoplasmic proteins and use of selected strains in the production of "Naples type" salami

AIMS

The aim of this study was to determine the proteolytic activities of Staphylococcus xylosus strains on sarcoplasmic and myofibrillar proteins in order to evaluate the suitability of selected strains as starter cultures in the processing of a dry fermented pork sausage.

METHODS AND RESULTS

The proteolytic activity of 27 strains of Staphylococcus xylosus on sarcoplasmic and myofibrillar proteins was determined by agar plate method, o-phtaldialdehyde (OPA) spectrophotometric assay and sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Four strains were selected for the formulation of six starter cultures to use in the production of "Naples type" salami. The proteolytic contribution of starters was determined by SDS-PAGE, comparing the protein profile of inoculated sausages with that of uninoculated sausages after 0, 15 and 33 days of ripening. The results showed that the proteolytic activity of some strains, determined by the agar plate method, were not confirmed by electrophoretic and spectrophotometric assays. In fact, of 24 strains of Staphylococcus xylosus able to hydrolyse muscle protein extracts on agar plate, only 12 strains were shown to change SDS-PAGE profile of pork proteins. The SDS-PAGE profile of sarcoplasmic proteins extracted from all sausages showed that the major changes were produced with starters S3, S4 and S5 after 15 days of ripening. Also myofibrillar proteins undergo major changes after 15 days of ripening and the protein profiles showed the same pattern in all samples, except for the sausages produced with starter S4.

CONCLUSIONS

The results of this work showed that the muscle protein extracts hydrolysis test is suitable for preliminary screening of Staphylococcus xylosus strains on the basis of their proteolytic activity. However, evaluation of muscle protein hydrolysis in a food model system could then be more appropriate for selecting micro-organisms for use as starter cultures for fermented sausages.

SIGNIFICANCE AND IMPACT OF THE STUDY

The potential of the findings is discussed with reference to the formulation of starter cultures for the dry fermented sausages production.

Comparison of ISSR and RAPD markers to characterize three Chilean Nothofagus species

The present study is the first report of fingerprinting on three Chilean Nothofagus species using ISSR and RAPD markers; 61 Nothofagus nervosa, 32 Nothofagus obliqua and 32 Nothafagus dombeyi individual trees, sampled from collection and natural sites, were analyzed. Among 45 primers tested, the 6 ISSR and 6 RAPD primers selected for the analysis generated a total of 63 ISSR and 42 RAPD fragments. A high proportion of polymorphic bands, ranging from 97% and 80%, was found using both markers. A similar number of private and marker bands was generated by both markers in all the species examined and one discriminant ISSR fragment was obtained for N. dombeyi. Jaccard and Dice similarity indices were used to evaluate pairwise genetic divergence; cluster analysis of the similarity matrices was performed to estimate the intra- and inter-specific genetic diversity, and PCA analysis was employed to evaluate the resolving power of the markers to differentiate between the species. These analyses, carried out for both markers, allowed us to identify three main groups corresponding to the three Nothofagus species. The results of the present study can be seen as a starting point for future researches on the population and evolutionary genetics of these species.

The use of immunoglobulins in the treatment of human epilepsy

The use of immunoglobulin (IVIg) in intractable epilepsy is one of its oldest applications in medicine, starting from the empirical observation of its beneficial effect on seizures. Immune system dysfunction may play a role in epilepsy by triggering, maintaining or, unexpectedly, improving intractable seizures. Several laboratory and clinical investigations are in favor of an immunological basis for different forms of experimental and human epilepsies. A wide range of immune abnormalities have been reported, suggesting the existence of different subtypes of epileptic syndromes with different abnormalities of the immune system. In this view, IVIg with its broad immunomodulatory mechanism of action could be effective in different forms of immune-dysregulated intractable epilepsies. Non-immunological mechanisms of action have been also suggested, based either on human epilepsy data or on animal experimental data. The possible anticonvulsant properties and the ability of IVIg to interfere with the final common pathway of seizures at a cellular level, with a significant increase in seizure threshold, have been demonstrated in different experimental epilepsy model. Although IVIg may represent a valuable resource in some drug-refractory epilepsies and its effectiveness has important pathogenetic implications, controlled studies with the systematic monitoring of immunological markers are needed to define more precise indications and to optimize the administration protocols.

Epileptic phenotypes associated with mitochondrial disorders

OBJECTIVE

To define the clinical and EEG features of the epileptic syndromes occurring in adult and infantile mitochondrial encephalopathies (ME).

METHODS

Thirty-one patients with recurrent and apparently unprovoked seizures associated with primary ME were included in the study. Diagnosis of ME was based on the recognition of a morphologic, biochemical, or molecular defect.

RESULTS

Epileptic seizures were the first recognized symptom in 53% of the patients. Many adults (43%) and most infants (70%) had nontypical ME phenotypes. Partial seizures, mainly with elementary motor symptoms, and focal or multifocal EEG epileptiform activities characterized the epileptic presentation in 71% of the patients. Generalized myoclonic seizures were an early and consistent symptom only in the five patients with an A8344G mitochondrial DNA point mutation with classic myoclonus epilepsy with ragged red fibers (MERRF) syndrome or "overlapping" characteristics. Photoparoxysmal EEG responses were observed not only in patients with typical MERRF, but also in adult patients with ME with lactic acidosis and strokelike episodes (MELAS), or overlapping phenotypes, and in one child with Leigh syndrome.

CONCLUSIONS

Epilepsy is an important sign in the early presentation of ME and may be the most apparent neurologic sign of nontypical ME, often leading to the diagnostic workup. Except for those with an A8344G mitochondrial DNA point mutation, most of our patients had partial seizures or EEG signs indicating a focal origin.

Comparison of statistical methods for identification of Streptococcus thermophilus, Enterococcus faecalis, and Enterococcus faecium from randomly amplified polymorphic DNA patterns

Thermophilic streptococci play an important role in the manufacture of many European cheeses, and a rapid and reliable method for their identification is needed. Randomly amplified polymorphic DNA (RAPD) PCR (RAPD-PCR) with two different primers coupled to hierarchical cluster analysis has proven to be a powerful tool for the classification and typing of Streptococcus thermophilus, Enterococcus faecium, and Enterococcus faecalis (G. Moschetti, G. Blaiotta, M. Aponte, P. Catzeddu, F. Villani, P. Deiana, and S. Coppola, J. Appl. Microbiol. 85:25-36, 1998). In order to develop a fast and inexpensive method for the identification of thermophilic streptococci, RAPD-PCR patterns were generated with a single primer (XD9), and the results were analyzed using artificial neural networks (Multilayer Perceptron, Radial Basis Function network, and Bayesian network) and multivariate statistical techniques (cluster analysis, linear discriminant analysis, and classification trees). Cluster analysis allowed the identification of S. thermophilus but not of enterococci. A Bayesian network proved to be more effective than a Multilayer Perceptron or a Radial Basis Function network for the identification of S. thermophilus, E. faecium, and E. faecalis using simplified RAPD-PCR patterns (obtained by summing the bands in selected areas of the patterns). The Bayesian network also significantly outperformed two multivariate statistical techniques (linear discriminant analysis and classification trees) and proved to be less sensitive to the size of the training set and more robust in the response to patterns belonging to unknown species.

Detection and characterization of a bacteriocin, garviecin L1-5, produced by Lactococcus garvieae isolated from raw cow's milk

AIMS

The identification of a bacteriocin-producing lactococcal strain isolated from raw cow's milk is reported, along with production conditions, physical and chemical properties, and mode of action of the bacteriocin.

METHODS AND RESULTS

On the basis of resistance to clindamycin, species-specific PCR and amplification of the 16S-23S rDNA spacer region, the strain was identified as Lactococcus garvieae. Its bacteriocin, designated garviecin L1-5, was bactericidal against closely related species and strains of species from different genera, including Listeria monocytogenes and Clostridium spp. Garviecin L1-5 was shown to be proteinaceous by protease inactivation and was unaffected by heat treatments, also at low pH values. When amplifying known lactococcal bacteriocin genes using DNA from strain L1-5 as template, no amplification products were observed on the agarose gel. The molecular weight of garviecin L1-5 was about 2.5 kDa. As far as is known, no bacteriocins have been detected from Lactococcus garvieae.

CONCLUSION

The general properties of garviecin L1-5 are characteristic of the low-molecular-weight bactericidal peptide group.

SIGNIFICANCE AND IMPACT OF THE STUDY

The survey of micro-organisms for novel antimicrobial substances provided valuable information on their physiology, ecology and practical application.