Biomedical subjects

P Mastrantonio

Publications and source records attributed to P Mastrantonio.

At least 73 records · Page 4Linked to original sources

PubMed1994

Susceptibility patterns and characterization of beta-lactamases in clinical isolates of Bacteroides fragilis.

Strains of Bacteroides fragilis isolated from clinical specimens are known to be frequently resistant to penicillins or cephalosporins. The production of beta-lactamases is the major mechanism in this resistance. Up to now at least five types of beta-lactamase enzymes have been described in the Bacteroides fragilis group. The purpose of this study was to evaluate the susceptibility to different antibiotics and the prevalence of the beta-lactamase types among 100 Bacteroides fragilis strains isolated from clinical specimens in Italy. MICs of 11 antibiotics were determined by the reference agar dilution method and by the new E test (AB Biodisk, Sweden). Results showed an acceptable correlation between the MICs determined for most strains, although those obtained by the E test tended to be lower. In the beta-lactam resistant strains the enzyme activity and isoelectric points were determined on crude enzyme extract.

Anti-Bacterial Agents↗

PubMed1994

Carboplatin and alpha-2b interferon intraperitoneal combination as first-line treatment of minimal residual ovarian cancer. A pilot study.

21 untreated ovarian cancer patients with stage III and minimal tumour size, were given weekly intraperitoneal (i.p.) carboplatin (150 mg/m2) and alpha-2b interferon (IFN) (30 million U/m2) for a total of 12 courses, from June 1989 to February 1993. To date, a total of 248 courses have been administered. Toxicity was seldom severe, although fever (179 courses), fatigue (141 courses) and other IFN-related side-effects were very frequent. No patient refused to continue treatment, but in 5 patients IFN dose had to be reduced, and in 1 it was discontinued. The IFN mean delivered dose intensity was 19.8 million U/m2 week. Grade 3-4 myelotoxicity occurred in 7 patients (39 courses), but no deaths related to treatment occurred. The actual mean dose intensity of carboplatin was 121.5 mg/m2 week. To date, 20 patients have completed treatment and are evaluable for response. Of 11 patients with tumour size < or = 5 mm, 10 (91%) achieved a pathological complete response (pCR) as did 4/9 (44%) of those with tumour > 5 mm at entry, for a 70% (95% confidence interval 50-90) overall pCR rate. At a median follow-up of 21 months (range 4-46), only one death occurred. The probability of being alive at almost 4 years was 91% in the entire group (100% in those with tumour size less than 5 mm). Only 1 of 14 patients who achieved a pCR relapsed. This i.p. combination seems a feasible approach to previously untreated ovarian cancer patients with minimal tumour burden. IFN dosage should be reduced to improve tolerance. In view of the very high pCR rate achieved in the group of patients with smaller tumours, a randomised trial is warranted to compare this approach to standard treatment in these patients.

Adult↗

PubMed1993

Intraperitoneal (ip) cisplatin-mitoxantrone-interferon-alpha 2b in ovarian cancer patients with minimal residual disease.

Forty-one ovarian cancer patients with less than 2 cm residual disease after systemic cisplatin-based chemotherapy received 4 courses of an ip regimen including cisplatin (75 mg/m2), mitoxantrone (20 mg/m2), and interferon-alpha 2b (30 mil IU/m2). The most important side effects were abdominal pain and fatigue. Overall 15/41 patients (37%) required narcotic analgesia for severe abdominal pain. In 1 case laparotomy was necessary due to bowel obstruction. Grade 3-4 myelotoxicity was observed in 18/41 patients (28 courses). No treatment-related death occurred. Pathological complete response (pCR) was achieved in 23/37 (62%) evaluable patients. Four-year disease-free survival was 50%, and no relapse occurred after 32 months. The estimated 4-year progression-free survival (PFS) and overall survival were 35 and 60%, respectively. Patients who achieved pCR showed significantly better survival than the others (P < 0.000). At multivariate Cox's analysis pCR achievement was the most important predictor of PFS (P < 0.005) and survival (P < 0.02). Age (< or = 60 vs > 60) and CA-125 serum levels at entry (normal vs increased) also showed independent predictive value. On the basis of multivariate analysis results we created a risk model for survival and PFS based on age and CA-125 at entry. We identified three subgroups of patients with significantly different outcomes. With this new ip combination long-term disease-free survival is achieved in a significant part of ovarian cancer patients with small tumor burden. A longer follow-up is needed to see whether it can cure some of these patients, and further comparisons with other ip or systemic regimens are needed to draw definitive conclusions about its role in these patients.

Adult↗

PubMed1993

[Anaerobic bacteria and gynecologic infections].

The normal vaginal flora consists of a wide variety of bacteria and the composition of this microflora is influenced by hormonal, metabolic and pharmacological factors. An increased concentration of a mixed anaerobic flora (Mobiluncus, Prevotellae, Peptostreptococci and Gardnerella vaginalis) appears to be an early stage in the development of bacterial vaginosis or in the infection of the upper genital tract. Women with bacterial vaginosis are at increased risk of bartholinitis, skenitis, pelvic inflammatory disease, postpartum and postabortal endometritis, chorioamnionitis and infections following gynecologic surgery or diagnostic procedure.

Bacteria, Anaerobic↗

PubMed1992

Purification and characterization of an immunodominant 36 kDa antigen present on the cell surface of Clostridium difficile.

The 36 kDa antigen represents the major EDTA-extracted protein of Clostridium difficile strains belonging to electrophoretic group 2. Antibodies to this antigen are found in sera of patients with C. difficile-associated diarrhoea. The 36 kDa antigen was extracted from C. difficile C253 by EDTA and purified by gel filtration (Sephacryl S300) and ion exchange chromatography (DEAE-Trisacryl M). The molecular weight of the purified protein was 36 kDa as determined by SDS-PAGE, also in non-reducing conditions. By gel filtration, the molecular size appeared to be 72 kDa and was not modified by the presence of EDTA or SDS in the column buffer. Since IEF showed a single isoelectric form of pI 4.6, the protein could be a homodimeric molecule. Immunofluorescence demonstrated that the 36 kDa antigen was located on the surface of the C. difficile cell. Monospecific antiserum raised in rabbits reacted positively with the 36 kDa protein of most group 2 C. difficile strains isolated from antibiotic-associated diarrhoea (AAD) outbreaks in Italy and other European countries.

Antigens, Surface↗

PubMed1992

Clostridium difficile toxin A induces multinucleation in the human leukemic T cell line JURKAT.

Clostridium difficile toxin A is a cytotoxic enterotoxin known to be active on all mammalian cell lines tested up to now. It induces a disruption of the cytoskeleton, particularly the microfilament system, leading to inhibition of cell proliferation. Here, we describe some effects of toxin A on the leukemic T cell line JURKAT. Cells exposed to the toxin did not divide, as cell numbers remained constant for 3 days in the presence of 0.5 to 1.0 micrograms/ml of the toxin. However, these cells were found to become multinucleated, a phenomenon which was time- and dose-dependent. After treatment for 72 h with 0.5 micrograms/ml toxin A, 95% of the cells were multinucleated and had a considerably increased cell diameter. These effects in JURKAT cells were partially reversible upon removal of the toxin within 12 h after the beginning of toxin exposure, but irreversible after 24 h of toxin treatment. These results suggest a continuing nuclear division in the absence of cytoplasmic division, i.e., an effect of toxin A on contractile ring formation. The JURKAT cell is the first cell type reported to respond to toxin A with multinucleation.

Bacterial Toxins↗

PubMed1991

Genetic relationships among strains of Neisseria meningitidis causing disease in Italy, 1984-7.

Since 1984 a change in the epidemiological pattern of meningococcal disease in Italy has occurred with a predominance of Neisseria meningitidis of serogroup C (76%), serotype 2a and a high proportion of strains resistant to sulphonamides (71%). In order to understand better the epidemiology of the group C N. meningitidis strains responsible for the disease over the last years in Italy, we studied the genetic features of phenotypically closely related strains, by enzyme electrophoresis. The results showed that the genetic and the phenotypic characteristics of the 57 strains studied were similar, suggesting that spread of a single clone during recent years in our country. This result is in agreement with the circulation of strains typical of epidemic situations, despite the decreasing incidence of meningococcal disease in Italy.

Electrophoresis, Starch Gel↗

PubMed1991

Capsule-like structures in Clostridium difficile strains.

Fourteen strains of Clostridium difficile, previously characterized by SDS-PAGE, were examined for the presence of surface structures. None of the strains were fimbriated but, when grown in the presence of glucose, all exhibited a thin ruthenium red-positive layer. Two strains, belonging to different electrophoretic groups, were also observed after treatment with homologous and heterologous antisera. The strain belonging to the electrophoretic group 2, usually associated with the disease, showed a 30-80nm thick capsule in ultrathin sections. The strains belonging to group 5, mainly observed in isolates from healthy children, exhibited a thinner polysaccharide layer (10-20 nm). No stabilization was observed when these strains were treated with heterologous antisera. This capsule-like material did not seem to be associated with adhesive properties of C. difficile strains.

Cell Wall↗

PubMed1990

Antibacterial polysaccharide antibody deficiency after allogeneic bone marrow transplantation.

Allogeneic bone marrow-engrafted adults immunized with meningococcal types A and C and pneumococcal type 14 polysaccharide antigens showed only low antibody titers of the IgM class, no antibody titers of the IgG or IgA classes, and no bactericidal activity in vitro. The analytical isoelectrofocusing showed the appearance of a restricted pattern of clonotypes in a minority of subjects. These observations are consistent with the hypothesis that B cells in bone marrow transplant patients express some characteristics of neonatal B cells and suggest that polysaccharide-protein conjugates, rather than isolated polysaccharide, might be utilized in the setting of bone marrow transplantation.

Adult↗

PubMed1990

Surface blebbing and cytoskeletal changes induced in vitro by toxin B from Clostridium difficile: an immunochemical and ultrastructural study.

Clostridium difficile toxin B is a powerful cytopathic agent without enterotoxic activity which is believed to be involved in the pathogenesis of pseudomembranous colitis. Up until today, the mechanisms of toxin B cytotoxicity have not been elucidated. The results of in vitro studies performed on different cell lines by means of immunocytochemical and ultrastructural methods are reported here. Low doses (0.15 ng/ml) of toxin B cause cell rounding and arborization. Higher doses (up to 15 micrograms/ml) induce cell rounding and appearance of numerous surface protrusions with blister or bulb-like features. These "blebs" belong to the potocytotic type, the bleb matrix being devoid of cytoplasmic organelles and filled with ribosomes only. Furthermore, a peculiar role of cytoskeletal apparatus in this phenomenon has been detected. In fact, morphological rearrangement occurs in cytoskeletal elements, mainly represented by the presence, in the blebs, of tubulin and of the actin-binding proteins alpha-actinin, filamin, and calmodulin, while actin and intermediate filaments, keratin and vimentin, appear to be absent. Moreover, beta 2-microglobulin, considered as a surface protein marker, seems to undergo changes in its expression, being absent over the blebbing surface. The results of this study may support the view that C. difficile toxin B affects one or more subcellular components that regulate the structure and function of the actin cytoskeleton.

Bacterial Proteins↗

PubMed1990

Trends in meningococcal disease in Italy in 1988.

Meningococcal disease in Italy decreased 15% in 1988 from the previous year (290 vs. 342 cases). The decline was particularly evident in military cases (1.7/100,000 in 1988 vs. 5/100,000 in 1987) reflecting the full coverage of bivalent serogroup (A + C) meningococcal polysaccaride vaccine in army recruits, achieved since January 1988. The highest proportion of cases was seen in people older than 25 years of age (25%). Serogroup C constituted 60% of the isolates, while 19% belonged to serogroup B. The proportion of strains resistant to sulphonamides was 45%, while 15% were resistant to Minocycline and none to Rifampin. Out of the five military cases, only one (due to serogroup C) was attributable to the vaccine failure. A single coprimary case, but no secondary cases occurred among civilians. These findings are consistent with the trends reported in Italy in the previous years.

Adolescent↗

PubMed1990

Interaction of Clostridium difficile toxin A with cultured cells: cytoskeletal changes and nuclear polarization.

Experiments done on in vitro-cultured cells exposed to toxin A from C. difficile showed a series of cytopathologic changes leading to cell retraction and rounding accompanied by the marginalization of the nucleus, which localized at one pole of the cell. Cytoskeleton appeared to be strongly involved in such modifications. In particular, the microfilament system seemed to be involved in cell retraction, while microtubule network integrity and function seemed to be necessary for the nuclear displacement. The carboxylic ionophore monensin completely blocked the cytopathic effect when added with the toxin. The serine protease inhibitor chymostatin appeared to be protective also upon addition long after the end of the binding step. The Ca2(+)-dependent cytosolic protease inhibitors antipain and leupeptin were uneffective in protecting cells. Thus, our results suggest the involvement of an acidic compartment and the action of a serine protease in toxin A-induced cytopathic effect.

Animals↗

PubMed1990

Genomic fingerprints and phenotypic characteristics of strains of Neisseria meningitidis causing disease in Italy.

Since 1984 a change in the epidemiological pattern of meningococcal disease in Italy has occurred with a predominance of Neisseria meningitidis of serogroup C (76%), serotype 2a and a high proportion of strains resistant to sulfonamides (71%). To better understand the epidemiology of the group C N. meningitidis strains responsible for the disease over the last five years in Italy, we studied the DNA fingerprinting of 62 strains in combination with serotyping and sulfonamide susceptibility testing. The results show that the phenotypical features as well as the fingerprints of the strains studied were similar, suggesting the spread of a single clone in the patients studied. This is in agreement with the circulation of strains typical of epidemic situations, despite the decreasing incidence of the disease in Italy during the examined period.

DNA, Bacterial↗

PubMed1990

The effect of meningococcal group A and C polysaccharide vaccine on nasopharyngeal carrier state.

The effect of Neisseria meningitidis group A and C polysaccharide vaccine on nasopharyngeal carriage was studied in Italian army recruits. Throat swabs were cultured for N. meningitidis at the time of vaccination (one week after entry to service) and again three weeks later in a follow-up cohort of 98 men. At the first survey the overall carriage rate was 32% with 9% of isolates due to serogroup C, none to serogroup A and 17% to serogroup Y. At the second survey the overall carriage rate reached 52% (P less than 0.01); no isolate belonged to serogroup A or C, while serogroup Y reached 40% (P less than 0.01). The cumulative carriage rate was 65%. Out of the 64 carriers during the whole study period, only 7 (11%) belonged to the same serogroup during the two different surveys. The vaccination appears to influence the carriage rate of meningococcal specific serogroups. The inhibition of serogroups A and C is, however, offset by an increased prevalence of meningococci belonging to serogroup Y.

Bacterial Vaccines↗

PubMed1989

Haemagglutination and surface structures in strains of Clostridium spiroforme.

Five strains of Clostridium spiroforme were examined for their surface properties. All strains were able to agglutinate human erythrocytes. Electron microscopy showed a ruthenium red-positive capsule mediating the attachment of bacteria to erythrocytes. Two strains, showing the lowest degree of haemagglutination, exhibited an additional external layer of filamentous structures, possibly interfering with the agglutinating activity. In spite of their agglutinating ability, the C. spiroforme strains did not show surface hydrophobicity, thus suggesting the possible existence of a new type of clostridial adhesin.

Animals↗

PubMed1989

Effects of Clostridium difficile toxins A and B on cytoskeleton organization in HEp-2 cells: a comparative morphological study.

A comparative study on the effects of toxin A and toxin B from Clostridium difficile on HEp-2 cells was carried out. Both toxins caused cell retraction and rounding and seemed to exert their effect on cell morphology via a rearrangement of actin and alpha-actinin microfilaments. Such a rearrangement occurred at an early stage, when no change in microtubular and cytokeratin systems was detectable. Nevertheless, several structural modifications accompanying the cytopathological process induced by toxins A and B appeared to be quite different. In particular, toxin B-treated cells showed an arborized phenotype as a result of cell retraction and rounding, whereas toxin A caused cell rounding without arborization. Moreover, nuclear polarization following disorganization of the microfilament system was only observed in toxin A-treated cells. The structural features distinguishing intoxication processes induced by the two toxins probably reflect a different mechanism of action and suggest the presence of a distinct subcellular component as a primary target for each toxin.

Bacterial Proteins↗

PubMed1989

Meningococcal disease in Italy.

In 1985, nationwide surveillance of meningococcal disease aimed at establishing appropriate guidelines for prophylaxis started in Italy. The incidence of disease was 1.1/100,000 in 1985 and 0.6/100,000 in 1987. This decreasing trend was particularly evident among military recruits (from 17.3/100,000 in 1985 to 5/100,000 in 1987), reflecting the use of bivalent serogroup (A + C) meningococcal polysaccharide vaccine in all new recruits since January 1987. The age distribution of cases was statistically different from that observed during the 1970s (P less than 0.001), with a shift towards older age groups. Men have been in the majority (516 vs. 358, P less than 0.0000001). Group C has been the most common serogroup encountered (72.2%), while only 18% of the isolates belonged to serogroup B. Among military recruits, serogroup C accounted for 92% (81/88) of the cases. The proportion of strains resistant to sulphonamides was 67%, while only 3% strains were resistant to rifampicin and to minocycline. Reduced susceptibility to ampicillin and to penicillin was observed in 3 and 4% strains respectively. Nine secondary cases were all due to failure in the administration of chemoprophylaxis (sulphonamide given in seven cases, prophylaxis not attempted in two cases). Immunisation of all new military recruits and effective chemoprophylaxis of close contacts of cases are the major guidelines provided by the National Meningitis Surveillance Programme.

Age Factors↗

PubMed1989

Immunoblot analysis of serum immunoglobulin G response to surface proteins of Clostridium difficile in patients with antibiotic-associated diarrhea.

We examined by immunoblot analysis the serum immunoglobulin G antibody response to EDTA-extracted surface proteins of Clostridium difficile in 16 patients with antibiotic-associated diarrhea. For each patient, paired serum samples were tested against proteins of the infecting strain and of a collection strain (C253) known to belong to the electrophoretic group 2 pattern. Eight patients, all harboring group 2 C. difficile strains, exhibited responses to the proteins of the infecting strain; six patients showed increases in the level of antibodies between acute-phase and convalescent-phase sera. A great variability in the antigens recognized was found; however, seven patients possessed antibodies directed against an antigen of about 35 kilodaltons, corresponding to the major protein of group 2 strains. The sera of these seven patients cross-reacted also with the 35-kilodalton and other proteins of strain C253. Our data show that C. difficile proteins other than toxins can elicit an immune response in patients with C. difficile-associated disease; in this group of patients, the major surface protein of the group 2 strains was the antigen most often recognized.

Adolescent↗