Search PubMed⌕ Search

Biomedical subjects

A Calzolari

Publications and source records attributed to A Calzolari.

At least 55 records · Page 3Linked to original sources
PubMed1996

Phenotypic characterization and virulence of a sae- agr- mutant of Staphylococcus aureus.

A sae::Tn551 agr::tetM double mutant was constructed and characterized. The production of several exoproteins (e.g., beta-hemolysin, DNase, and proteases) by this mutant was determined and found to be lower than the already diminished production of either isogenic single mutant sae- or agr-. The double mutant also showed, like the agr- mutant, null production of alpha- and delta-hemolysins and diminished levels of lipase. The reduced levels of many exoproteins in the double mutant as compared with their already diminished levels in either single mutant suggest that there is an additive or synergistic interaction between the two mutations involved, sae- and agr-. However, inactivation of both loci, sae and agr, had a different effect on the two exoproteins that are up regulated in the agr- mutant; thus, coagulase dropped to levels close to the null levels of the sae- parental strain, while extracellular protein A displayed the high levels characteristic of the agr- single mutant. The virulence of the sae- agr- double mutant, determined by intraperitoneal injection in mice, was found to be significantly diminished as compared with that of the sae+ agr+ parental strain or the sae- agr+ single mutant.

Animals↗
PubMed1996

Abnormal hypertensive response during exercise test in normotensive transplanted children and adolescents.

We investigated the cardiovascular and respiratory conditions, at rest and in response to stress testing, in 10 children and adolescents with successful renal transplantation, to release certifications for participation in sports. Our patients were aged more than 6 years, transplanted 6 months or more before the study, with creatinine clearance > 40 ml/min/1.73 m2, without hypertension at rest. All but 1 were on cyclosporine A, prednisone and azathioprine. Two control study groups with the same chronological age and body surface area were paired with our patients. They underwent a graded exercise tread-mill test, during which maximal blood pressure and heart rate were recorded. Resting electrocardiogram, dynamic 24-hour electrocardiogram Holter monitoring and mono- and bidimensional echocardiograms were obtained before the test. Spirometry was performed to study lung flow and volume. A questionnaire collected information about physical activity patterns. Four categories, according to practice, frequency and duration of exercise, were identified: nonactive, starters, experienced and very experienced. Most children and adolescents were sedentary or mildly interested in sports and during treadmill test we observed reduced exercise capacity and systolic hypertensive response to increasing exercise testing.

Adolescent↗
PubMed1996

In vivo expression of exoprotein synthesis with a Sae mutant of Staphylococcus aureus.

The expression of exoprotein synthesis of Staphylococcus aureus Sae mutant RC121 and its parental strain was studied under in vivo growth conditions. Cultures of both strains were inoculated into dialysis sacs implanted in sheep peritoneum. Results indicated that similar to in vitro grown mutant cells, Sae mutant RC121 shows diminished synthesis of alpha- and beta-hemolysin, coagulase, DNase and protein A. However, in vitro and in vivo grown mutant cultures showed different exoprotein profiles in SDS-PAGE; some bands from in vivo mutant cultures were diminished or missing and others appeared as more concentrated, when compared with the pattern of the in vivo grown parental strain, while all the exoprotein bands from the in vitro cultures of the mutant were diminished or missing as compared to the in vitro grown parental strain. The virulence of the Sae mutant, assayed by intraperitoneal injection in mice, was lower than that of the parental strain after both in vivo and in vitro growth conditions.

Animals↗
PubMed1996

[Functional evaluation by treadmill in children and adolescent following correction of Tetralogy of Fallot].

AIM OF THE STUDY: The Authors have examined 22 children (16m and 6f), mean age 9.64 +/- 2.63 years, range 5-15, after total correction for Tetralogy of Fallot, to evaluate the response of their cardiovascular apparatus during an exercise testing on treadmill (Bruce protocol). METHODS: Parameters examined: exercise duration, maximal heart rate (HR), maximal systolic blood pressure (max BP), non invasive cardiac output at rest and at the peak of exercise (CO), arterial oxygen saturation; lung function test at rest, echocardiogram and 24 hours Holter monitoring. CONTROL GROUP: 22 healthy peers, same gender, height and weight, not practising competitive sports. RESULTS: The exercise duration was significantly lower in the first group (77.8 +/- 11.8%; 86.5 +/- 8.2%; P = 0.006). Also max HR and max BP were significantly lower (max HR: 162 +/- 12 b/m'; 187 +/- 8 b/m'; P = 0.000), (max BP: 119 +/- 9 mm Hg; 126 +/- 12 mm Hg; P = 0.042). There were no differences for CO at rest (3.70 +/- 1.09 l/m'; 3.95 +/- 1.07 l/m'). In the first group, CO at peak of exercise was lower but not significantly (6.51 +/- 2.56 l/m'; 7.95 +/- 2.77 l/m'; NS). CONCLUSIONS: These results make more complete the not invasive functional evaluation for a better follow-up of these patients and a better choice for their physical activity.

Adolescent↗
PubMed1996

bcl-2 protein expression correlates with recurrence and survival in early stage head and neck cancer treated by radiotherapy.

Inherent cellular radioresistance plays a critical role in the failure of radiation therapy (RT). The proto-oncogene bcl-2 encodes a protein that inhibits apoptosis, a common mechanism of cell death induced by several genotoxic agents, including gamma-radiation. Thus, it is likely that bcl-2 gene expression could be involved in the complex mechanisms of radioresistance in human tumors with some prognostic implications. In this study, we analyzed the predictive relevance of bcl-2 expression on 5-year disease-free and overall survival in patients with early stage squamous cell carcinoma of the head and neck (SCCHN) primary treated with RT. The expression of bcl-2 was analyzed by immunohistochemistry on paraffin-embedded sections from 71 consecutive stage I-II SCCHN patients treated with curative RT. We detected bcl-2 protein in 21% of SCCHN studied. A suggestive association was observed between tobacco exposure and bcl-2 protein expression (P < 0.1); this association was stronger in those patients who failed primary RT (P = 0.03). Moreover, we documented a higher rate of bcl-2 immunoreactive tumors in postirradiated biopsies from relapsed patients than in preirradiated ones (P = 0.03). In both univariate and multivariate analyses, bcl-2 expression was the most important indicator for disease-free survival (P = 0.08 and P = 0.01, respectively) and overall survival (P = 0.004 and P = 0.05) within 5 years of RT. The present study indicates that the proto-oncogene bcl-2 is abnormally expressed in some SCCHN, and its expression may prove to be a useful tool in selecting patients for conventional RT with clear prognostic implications.

Adult↗
PubMed1996

Loss of p53 gene mutation after irradiation is associated with increased aggressiveness in recurring head and neck cancer.

The p53 gene plays a pivotal role in the control of a checkpoint during G1 and in the apoptotic program. It has been postulated that alterations of p53 may influence radio-sensitivity and prognosis in several malignancies. We studied the p53 gene status of 35 consecutive head and neck cancer patients who failed primary radiotherapy (RT) in preirradiated and postirradiated tumor samples using DNA single-strand conformational polymorphism analysis. Sixteen of 35 (46%) preirradiated samples presented with band shifts suggestive of point mutations in one or two exons. Eleven of these tumors (69%) showed the same shift even in the postirradiated samples. Exons 5 and 8 were prevalently affected in this group. Five tumors (31%) lost the mutation following RT. The missed mutations clustered in exon 7. All mutations were confirmed by sequencing. Actuarial analysis demonstrated increased survival in patients with tumors bearing a p53 gene mutation in both preirradiated and postirradiated samples (P = 0.05 and P = 0.01, respectively). We also found that loss of p53 gene mutation in postirradiated cancers is associated with a significantly shorter disease-free interval (P < 0.02) and a worse prognosis (P < 0.05). A possible explanation in such cases is clonal selection by RT of more aggressive and radioresistant cell subpopulations, which are wild-type for the p53 gene. Taken together, our data suggest that not only p53 gene status but also the pattern of mutations could modulate the response of tumor cell to RT in vivo.

DNA Mutational Analysis↗
PubMed1995

Physical fitness testing in children operated on for tracheoesophageal fistula.

The maximal physical activity capacity of children operated on for tracheoesophageal fistula (TEF) has not been clearly defined. Eight patients (average age, 12 years) successfully operated on for TEF at birth underwent maximal exercise stress testing on a treadmill, according to the Bruce protocol, to test physical work capacity. Heart rate (HR), oxygen consumption (VO2), and pulmonary ventilation (VE) were measured by a portable lightweight telemetric device. Nine healthy children served as controls. Exercise duration was significantly lower for TEF subjects than for controls (11.6 +/- 1.7 minutes v 15.1 +/- 2.3 minutes; P < .01). Mean HR at rest and during exercise did not differ between the groups. All children reached the maximum HR according to their age; however, for the majority of TEF patients, this occurred at an earlier stage than in the controls. No differences were seen in mean VO2 at rest and on exertion between TEF and control children. However, maximal VO2, as measured at the end of exercise, was significantly different when normalized per kilogram of body weight (VO2/kg = 52.3 +/- 5.8 v 33.3 +/- 6.6; P < .005). The physical rehabilitation of TEF children usually takes into account only respiratory and nutritional factors. However, complete assessment of their cardiac and respiratory function, at rest and on exertion, also should be performed, because this may show that some patients have reduced motor performance; evidence is now accumulating that these children can safely participate in the same physical activities of their healthy peers.

Adolescent↗
PubMed1995

[Transesophageal atrial stimulation in the oral treatment of supraventricular reciprocal paroxysmal tachycardia in infants].

INTRODUCTION: The aim of the study was the evaluation of the usefulness of transesophageal atrial pacing in predicting chronic oral treatment efficacy of symptomatic reciprocating supraventricular tachycardia in infants and in avoiding the risk of very dangerous recurrences at home. METHODS: We studied 13 infants (11 males, 2 females, mean age 43 +/- 31 days) with symptomatic reciprocating supraventricular tachycardia and no structural heart disease. All patients had chronic oral therapy, using the drug effective in acute i.v. somministration. Each patient was discharged when supraventricular tachycardia was not inducible with transesophageal atrial pacing after 5 half-lives of the drug used in chronic oral treatment. All patients, every 6 months, were retested with transesophageal atrial pacing alternatively during chronic oral therapy and after complete wash out. Oral therapy was stopped in each patient when supraventricular tachycardia was not inducible after the wash out. RESULTS: The number of oral treatments tested for each patient were 2 +/- 1 (range 1-5). The number of transesophageal studies performed for each patient were 4 +/- 2 (range 3-7). No patient had symptomatic episodes of supraventricular tachycardia or needed to change therapy during the follow-up. The oral treatment was stopped after the twelfth month of life in 8 patients and after the twenty-fourth in 2 others without recurrences. CONCLUSION: Transesophageal atrial pacing seems to be useful in predicting accurately and rapidly the oral treatment efficacy of supraventricular tachycardia in infants. Our protocol seems to be effective to avoid dangerous recurrences of tachycardia and to decide when we can stop therapy without risk.

Administration, Oral↗
PubMed1994

Pathogenicity in mice of Staphylococcus aureus mutants deficient in exoprotein synthesis.

Twelve mutants were isolated from a Staphylococcus aureus strain derived from bovine mastitis after mutagenesis by ultraviolet light. These mutants were found to be deficient for several characteristics such as production of most exoproteins and had altered phage type and/or colonial morphology in serum-soft agar medium. They also differed in virulence when assayed in mice by intraperitoneal administration; the ratio of the LD50 of the mutants vs. that of the parental strain ranged from 1 to 123. The different virulence of the mutants could not be associated with lack of production of exoproteins or altered colonial morphology. On the other hand, a clear correlation was evidenced between lowered virulence and slower growth rate at 37 degrees C. Three mutants were assayed in the mouse mastitis model. One of them, which was about 40 times less virulent when assayed by intraperitoneal administration, induced a histopathological lesion similar to that produced by the parent strain; the other two mutants, which were about 70 to 120 times less virulent by intraperitoneal administration, induced only a very slight lesion. Mice were vaccinated by the intraperitoneal route with two of the less virulent mutants; the LD50 in the vaccinated mice that were challenged with the parental strain increased 11 to 14 times compared with that for the unvaccinated mice.

Animals↗
PubMed1994

Characterization of a Tn925-induced mutant of Staphylococcus aureus altered in exoprotein production.

An insertional mutant was isolated from a bovine Staphylococcus aureus strain after membrane-mating with a Streptococcus faecalis strain carrying conjugative plasmid pCF10::Tn925. This mutant, designated RC128, showed enhanced production of alpha-hemolysin and proteases and decreased production of coagulase, extracellular protein A, DNase, lipase and delta-hemolysin. No difference was found in the production of beta-hemolysin. Both, Southern blot analysis and transfer of the pleiotropic mutant phenotype by transduction, indicated that the mutation was originated from a single insertion of transposon Tn925. The LD50 determined by intraperitoneal administration in mice showed that mutant RC128 was slightly less virulent than its parental strain.

Animals↗
PubMed1994

Efficacy and safety of ventricular rate responsive pacing in children with complete atrioventricular block.

Single chamber rate responsive pacing offers many potential advantages over the more complex dual chamber atrial tracking pacing mode in children, and the preservation of atrioventricular synchrony could be unnecessary in selected groups of pediatric patients. Twenty-two pediatric patients (age range 9 months to 12 years; mean 6.5 years) had implantation of ventricular rate responsive (VVIR) pacemakers over a 2-year period. All patients had chronic third-degree atrioventricular block, and a normal ventricular function at rest. During the follow-up each patient underwent a 24-hour Holter monitoring, and ten performed a graded treadmill test in both ventricular fixed rate (VVI) and rate responsive (VVIR) pacing mode. Paced ventricular rates were found to be normal for age in all 22 patients; maximum rate did not reach the higher programmed rate during daily activities in any patient. Comparing the mean paced ventricular rate to the mean rates of blocked P waves, six patients showed a difference of more than 20 beats/min, which induced the pacemaker parameters to be reprogrammed. In all patients a significant correlation was found between variations of paced ventricular rate and variations of spontaneous blocked atrial rhythm (P < 0.05); this correlation persisted in the subsequent Holter controls in the ten patients with longer follow-up. Exercise tolerance resulted normal in the ten patients who performed a treadmill test either in VVIR or VVI mode, with increased maximal heart rates and maximal systolic blood pressure in VVIR mode (P < 0.0013). Rate responsive ventricular pacemakers seem to adequately respond to the physiological needs of daily life of this selected group of children requiring permanent pacing.

Atrial Function↗
PubMed1994

Characterization of a Tn551-mutant of Staphylococcus aureus defective in the production of several exoproteins.

A Tn551 insertional pleiotropic mutant defective in the production of several exoproteins was isolated from Staphylococcus aureus 196E and characterized. The pleiotropism of the mutant was due to a single insertion of the transposon as evidenced by Southern blot hybridization and by the transfer of its phenotype by transduction to S. aureus ISP479. The mutants showed diminished or null levels of alpha- and beta-hemolysis, DNase, coagulase, and protein A in the supernatants of broth cultures. Production of proteases, lipase, staphylokinase, or enterotoxin A was not modified. The mutants did synthesize the cell-bound form of protein A and also the extracellular form of this protein coded by pRIT11, which lacks the COOH-terminal segment of the molecule. These observations suggest that the sae locus does not involve a positive regulatory gene acting at the transcriptional level. The phenotype of the mutant was different from that of other insertional mutants affecting exoprotein synthesis, such as agr, xpr, or sar. This new mutation has been designated sae (for S. aureus exoprotein expression).

Bacterial Proteins↗
PubMed1994

Lack of detection of human papillomavirus (HPV) in transformed laryngeal keratoses by in situ hybridization (ISH) technique.

Laryngeal keratosis (LK) is a precancerous mucosal change with a variable possibility of malignant transformation. Recent studies evidencing HPV-DNA genomes in a large series of non-malignant and malignant laryngeal lesions suggest a role of HPV in the transformation of laryngeal lesions possibly in synergistic interaction with other carcinogens. In this study, we analyzed 115 biopsy specimens from benign laryngeal lesions to evaluate the risk of malignant transformation and its relationship to degree of dysplasia and to histological features of virus cell infection. The rate of transformation of LK was 8% (9/115). Our results indicate that the risk of transformation in laryngeal keratoses without dysplasia (LKWOD) is lower than that in laryngeal keratoses with dysplasia (2.2% vs 25%, respectively) (p < 0.05). An increased risk of malignant evolution in laryngeal keratoses with dysplasia (LKWD) was also related to the degree of dysplasia (rate of transformation of 12.5, 22.2 and 36% in mild, moderate and severe dysplasia, respectively). Histological features suggesting HPV infection (koilocytic-like atypia and epithelial papillary hyperplasia) were found in 6 LK only, no case subsequently developing cancer. In both benign and transformed LK, analyzed by ISH, we failed to detect HPV genomes, suggesting a major role of others carcinogens, such as tobacco and/or alcohol, in the transformation of LK.

Adult↗
PubMed1994

Epstein-Barr virus (EBV) infection and undifferentiated carcinoma of the parotid gland in Caucasian patients.

The Epstein-Barr virus (EBV) has been detected in certain types of lymphoma and some epithelial neoplasms such as nasopharyngeal lymphoepithelioma and occasional undifferentiated carcinomas in several organs including the salivary glands. However, clonal EBV genomes have been detected in undifferentiated carcinomas of the parotid gland exclusively in Alaskan natives and Eskimos, both groups being at the highest risk for nasopharyngeal carcinoma. The authors investigated the possibility that EBV may be present in undifferentiated parotid carcinomas in Caucasian subjects. To test this hypothesis, in situ hybridization (ISH) technique with biotinylated EBV-DNA probes was utilized on routinely processed, paraffin-embedded tissues from 7 cases of undifferentiated carcinomas of the parotid gland. EBV genomes were demonstrated in the cytoplasm of tumor cells from 3 out of 7 specimens tested. Surprisingly, EBV genomes were found in 3 out of 5 (60%) undifferentiated carcinomas that had developed in patients with a history of a long-persisting asymptomatic parotid mass, which had suddenly increased in size. Conversely, none of the undifferentiated carcinomas with continuous and rapid growth studied was found to be positive for EBV-DNA by ISH technique. Taken together, these data might suggest a possible role of EBV in the transformation of benign parotid gland lesions into malignant and aggressive undifferentiated carcinoma of the parotid gland, the so-called carcinoma expleomorphic adenoma.

Adult↗
PubMed1994

[Expression of p53 in the skin in systemic sclerosis. Immunohistochemical study of 8 cases].

P53 gene belongs to the family of "Tumor suppressor gene". It encodes a nuclear phosphoprotein involved in cell proliferation control; mutations of p53 gene are the most common genetic alterations found in human tumors. These mutations may cause the production of an altered protein that usually loses its physiological function. The mutant p53 protein is more stable than the wild type form and it is immunohistochemically detectable. Systemic Sclerosis is characterized by activation of fibroblasts, endotheliocytes and lymphocytes; furthermore, in this disease, a proto-oncogenic activation has already been shown in fibroblasts and lymphocytes. The aim of this study was to verify p53 expression in the skin of SSc patients. Eight patients, all classified in the limited cutaneous subset of SSc, after informed consent, underwent skin biopsies of the affected and apparently unaffected skin. P53 was investigated by immunohistochemistry, using a monoclonal anti-p53 antibody (DO-7), on formalin fixed, paraffin embedded tissue. P53 immunoreactive cells were found in 4 out of 8 biopsies; in all cases the positivity was confined to cells of the basal layer of the epidermis, histologically identified as keratinocytes. A large case series and a molecular biology approach are needed to support these preliminary observations.

Adult↗
PubMed1994

Lack of detection of p53 expression in retinoblastoma tumor cells.

p53 was examined by immunohistochemistry in five cases of retinoblastoma, a neoplasm that is caused by a loss of function of the Retinoblastoma susceptibility gene (Rb), mapped to chromosome 13q14. Object of the study was the identification of eventual further gene mutation in retinoblastoma tumor cells determining the onset of an independent tumoral monoclonal cell subset. We did not observe any positive reaction for p53 protein expression in the five cases we analyzed.

Apoptosis↗
PubMed1994

Detection of human herpesvirus-6 and Epstein-Barr virus genome in childhood Hodgkin's disease.

Two widespread human herpesviruses, the Epstein-Barr virus (EBV) and the Human Herpesvirus 6 (HHV-6), have been frequently associated with Hodgkin's Disease (HD) and, recently, it has been observed an HHV-6 transactivation effect on EBV replicative cycle. We studied the presence and the possible association between EBV and HHV-6 in childhood HD cases, nodular sclerosis subtype. We analyzed formalin-fixed and paraffin-embedded lymph nodes from 15 cases by PCR for HHV-6 genome, and by PCR and in situ hybridization (ISH) for EBV genome. One out 15 samples resulted positive for HHV-6 DNA PCR, while 5 resulted positive for EBV DNA PCR. Only one sample positive for HHV-6 resulted positive for both HHV-6 and EBV genome. All samples were negative in ISH. At the moment, it is not clear the exact role of EBV and HHV-6 in the lymphomagenesis, neither it is possible to establish the rate of their interaction; our data show that it does not exist in vivo an evidence of their association.

Adolescent↗