[Evaluation of the Yersinia enterocolitica pathogenicity through some phenotypic and genotypic characters: CRMOX agar positivity and presence of the ail gene]

Sixty-nine strains of Y. enterocolitica isolated from environmental and human matrices (waste water, food and faeces) were studied in order to evidence the presence of ail gene, calcium-dependency and Congo Red absorption for pathogenic strains identification. Out of 24 clinical strains, the ail gene was present in 21 (87%), among which 79% were CRMOX-positive as well. On the contrary, none of the 45 environmental strains showed the ail gene although only one (isolated from cooked vegetables) was CRMOX agar positive. Our results confirmed the importance of molecular methods to evidence the Y. enterocolitica pathogenic strains. However, our study pointed also the utility to consider the approach of classic bacteriology, like the subcoltivation on CRMOX agar to show calcium-dependency and Congo Red absorption. In particular, when dealing with environmental isolates, that medium will be useful as a preliminary screening to identify those isolates which need further research to indicate their pathogenic potential by the use of more complex but also more expensive molecular methods.

In-vitro activity of nisin against clinical isolates of Clostridium difficile

Nisin is a cationic peptide produced by Lactococcus lactis. Its activity against clinical isolates of Clostridium difficile was compared to that of vancomycin and metronidazole by minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and time-kill studies. Nisin was more active than the other agents, with a MIC90 of 0.256 mg/L and strong bactericidal activity. Nisin may be a promising agent for the management of C. difficile associated diarrhea.

Nontuberculous mycobacteria in hospital water systems: application of HPLC for identification of environmental mycobacteria

Nontuberculous mycobacteria (NTM), ubiquitous in water environments, are increasingly recognized as nosocomial pathogens. Our study reports a one-year survey of the water system of two hospitals, A and B, in a small town near Florence, Italy. NTM were found throughout the study period in both settings, but B showed a significantly higher mycobacterial load. Mycobacterium gordonae and Mycobacterium fortuitum were the most frequent species isolated. Identification was carried out by conventional techniques and by high performance liquid chromatography (HPLC) analysis of cell wall mycolic acids. HPLC profiling could be used as a first-choice method for identification of environmental mycobacteria.

Impairment of gastric secretion modulation in duodenal ulcer and in long-term PPI treatment: quantitative morphologic findings and pathophysiologic implications

Helicobacter pylori affects gastric secretion. This functional effect might have a morphometric counterpart. Therefore, the gastric cell secretory compartment was morphometrically assessed in different pathophysiologic conditions related to Helicobacter pylori infection. Nineteen Helicobacter pylori-positive nonduodenal ulcer subjects, 15 omeprazole chronically treated subjects, and 19 duodenal ulcer patients were studied against 19 controls. Somatostatin, gastrin, enterochromaffin-like, and parietal cell density was assessed in gastric biopsies. No differences in any cell type density were found between Helicobacter pylori-positive nonduodenal ulcer subjects and controls. On the contrary, differences were significant when comparing omeprazole and duodenal ulcer patients to controls (higher density of gastrin, enterochromaffin-like, and parietal cells, lower density of somatostatin cells). In duodenal ulcer a reversion to control values followed Helicobacter pylori eradication and ulcer healing. A direct linear correlation between enterochromaffin-like, gastrin, and parietal cell density was demonstrated. An almost complete map of mucosal cells involved in gastric secretion is provided by this study. The cell density pattern, identical to the omeprazole group, points to an impaired feedback control of secretion in duodenal ulcer. The reversion to control values after Helicobacter pylori eradication and ulcer healing demonstrates the pathogenetic role of Helicobacter pylori-host interaction in these changes.

Neuronal and glial advanced glycation end product [Nepsilon-(carboxymethyl)lysine]] in Alzheimer's disease brains

The cellular distribution of an advanced glycation end product [Nepsilon-(carboxymethyl)lysine (CML)] in aged and Alzheimer's disease (AD) brains was assessed immunohistochemically. CML was localized in the cytoplasm of neurons, astrocytes, and microglia in both aged and AD brains. Glial deposition was far more marked in AD brains than in aged brains, and neuronal deposition was also increased. On electron microscopic immunohistochemistry, neuronal CML formed granular or linear deposits associated with lipofuscin, and glial deposits formed lines around the vacuoles. Neuronal and glial deposits were prominent throughout the cerebral cortex and hippocampus, but were sparse in the putamen, globus pallidus, substantia nigra, and cerebellum, with glial deposits being far more prominent in AD brains. The distribution of neuronal and glial deposits did not correspond with the distribution of AD pathology. The extent of CML deposits was inversely correlated with neurofibrillary tangle formation, particularly in the hippocampus. Most hippocampal pyramidal neurons with neurofibrillary tangles did not have CML, and most of the neurons with heavy CML deposits did not have neurofibrillary tangles. In the hippocampus, neuronal CML was prominent in the region where neuronal loss was mild. These observations suggest that CML deposition does not directly cause neurofibrillary tangle formation or neuronal loss in AD.

HPLC does not differentiate Mycobacterium paratuberculosis from Mycobacterium avium

HPLC, which is gaining its place as identification tool in mycobacteriology laboratories, has been proposed to distinguish Mycobacterium paratuberculosis from Mycobacterium avium. We had reported no significant difference between M. avium and M. paratuberculosis reference strain ATCC 19698. Because of the advantages offered by such a method, we enlarged our observations to include more isolates of M. paratuberculosis. Within the double cluster of peaks obtained by both M. avium and M. paratuberculosis, we could not find a consistent difference typical of M. paratuberculosis. Therefore, the present study confirmed that M. avium and M. paratuberculosis could not be distinguished by HPLC, raising doubts of a straightforward use of HPLC to identify M. paratuberculosis.

[Ipsilateral central-type facial palsy and contralateral hemiparesis associated with unilateral medial medullary infarction: a case report]

Clinical pictures of medial medullary syndrome are variable, depending upon the extent of the lesion. Facial palsy has rarely been observed even in medullary infarction. However, central-type facial palsy is usually found contralaterally to the infarct area at the level of the rostral medulla. In the present report, we discuss the pathogenesis of the neurological manifestations in a 57-year-old man with hypertension. The patient presented with mild left facial palsy of central type, right hemiparesis, paresthesia, with deep sensory disturbance of the right extremities. An MRI of the brain showed an infarction localized in the medial region of the left upper medulla. Although the exact course of the supranuclear facial pathways remains controversial, the ipsilateral central facial palsy in this patient is considered to have two possible causes: the interruption of aberrant fibers of the corticobulbar tract, which branch off and swing back at the level of the upper-middle medulla, or the disruption of recurrent ascending fibers from the contralateral pyramidal tract, through decussation.

Helicobacter pylori and duodenal ulcer: evidence for a histamine pathways-involving link

OBJECTIVES

A "gastrin link" has been suggested to explain the statistically relevant association between Helicobacter pylori and duodenal ulcer. Given the well known, although not entirely clarified, relationships between gastrin and histamine, the purpose of this study was to assess whether gastric mucosal histamine pathways and, more specifically, histamine-storing cells are involved in the Helicobacter pylori-duodenal ulcer route.

METHODS

Fasting serum gastrin, gastric mucosal histamine content, and mucosal density of both enterochromaffin-like cells and mast cells were compared in 11 H. pylori-positive, non-duodenal ulcer subjects, in 16 duodenal ulcer patients (all H. pylori positive), and in 11 H. pylori-negative control subjects.

RESULTS

Fasting serum gastrin concentration and mucosal histamine content were significantly higher in the duodenal ulcer group than in controls, whereas H. pylori-positive, non-ulcer subjects had values that were intermediate between those of the other two groups. Enterochromaffin-like cell density was significantly greater in duodenal ulcer patients than in the other groups.

CONCLUSIONS

These results demonstrate the involvement of histamine pathways in H. pylori infection and duodenal ulcer. The most original finding in this study was that enterochromaffin-like cell density is three times greater in duodenal ulcer patients than in H. pylori-positive, non-ulcer subjects. This could explain the previous report of an exaggerated acid response to gastrin in duodenal ulcer patients when compared with H. pylori-positive, non-ulcer subjects and thus provide further insight into the pathogenesis of ulcers.

Helicobacter pylori and cell proliferation of the gastric mucosa: possible implications for gastric carcinogenesis

OBJECTIVES

Helicobacter pylori infection is recognized as a risk factor for gastric adenocarcinoma. "Mitogenesis increases mutagenesis," so the effects of H. pylori infection on the gastric mucosal proliferative compartment have been investigated.

METHODS

In 25 H. pylori-positive and 19 H. pylori-negative subjects, epithelial cell proliferative activity and the pattern of the proliferative compartment were separately evaluated in relation to both the different type of mucosa (antrum and corpus) and the H. pylori positivity/negativity after 3H-thymidine labeling.

RESULTS

Both mucosal cell kinetics and the pattern of the proliferative compartment in the antrum appeared different from those of the corpus. Comparing H. pylori-positive and H. pylori-negative subjects, differences were detected only in the total number of cells in the antrum, whereas all of the cell kinetics parameters, except the labeling index, were greater in the corpus of the former group. A superficialization of the proliferative compartment was shown in H. pylori-positive subjects. Changes were more evident in subjects with more severe gastritis but were also present in H. pylori-positive subjects without corpus gastritis.

CONCLUSIONS

These results show that H. pylori infection is associated with modifications in the proliferative compartment of the gastric mucosa. Both infection per se and chronic gastritis seem to be relevant for such changes.

Gastric mucosal histamine storing cells. Evidence for different roles of mast cells and enterochromaffin-like cells in humans

Gastric mucosal histamine content, enterochromaffin-like cell density, and mast cell density were studied in 13 subjects under omeprazole therapy, 13 partially gastrectomized subjects with a Billroth II reconstruction, 10 partially gastrectomized subjects with a Roux-en-Y reconstruction, and 9 control subjects. Histamine content was significantly greater both in the subjects with higher gastrinemic levels (omeprazole-treated subjects) and those with more abundant enterogastric reflux (Billroth II subjects) than in controls. Enterochromaffin-like cell density was significantly greater in the omeprazole subjects than in each of the other groups. Mast cell density was significantly greater in Billroth II subjects than in controls. Serum gastrin levels, mucosal histamine content, and enterochromaffin-like cell density were positively correlated. Gastrin was not correlated to mast cell density. These results support the existence of different control pathways for enterochromaffin-like and mast cells. Moreover, they suggest that enterochromaffin-like cells and mast cells are involved in the regulation of gastric secretion and in gastric mucosal injury-repair mechanisms, respectively, due to histamine release.

Betalactam therapy and intestinal flora

Betalactams, mainly when orally administered, may lead to intestinal flora modifications related to their spectrum of activity, rate of absorption and degradation. therefore it is important to investigate the possible influence of recently developed oral cephem derivatives on normal human microflora. We have investigated the impact on normal human intestinal flora in a 10-day course with cefetamet-pivoxil (CET, 500 mg BID) in comparison to cefixime (CFX, 400 mg qD) or cefuroxime axetil (CA, 250 mg BID) in 24 patients suffering from acute exacerbation of chronic bronchitis. Stool specimens were taken before (day 0), at the end (day 10) and 14 days after treatment (day 24) and quali-quantitative microflora composition was determined with a detection limit of 10 CFU/g dry weight. Treatment with CET caused slight and non-significant modifications of normal intestinal flora. On the contrary CFX and CA significantly affect Enterobacteriaceae and clostridia with a concomitant increase in enterococci for CFX. With both CFX and CA there was a new appearance of Salmonella spp. as well as Clostridium difficile in 4 and 2 cases, respectively. Therefore CET seems to affect normal bowel flora minimally in comparison to other oral cephalosporins. This aspect might contribute to the low incidence of GI related side effects in patients treated with CEt for longer than 1 week.

[Pseudomonas aeruginosa antibodies in patients with cystic fibrosis: clinical implications]

Patients chronically colonised by P. aeruginosa develop a pronounced antibody response against P. aeruginosa that can be used to discriminate between superficial colonization and chronic infection. Anti-P. aeruginosa antibodies fail to afford protection against this pathogen; moreover high levels of antibodies are correlated with a poor prognosis. We investigated the significance of anti-P. aeruginosa antibodies (precipitins) by crossed immunoelectrophoresis (CIE) in 94 patients attending the Cystic Fibrosis Center of Florence. The highest numbers of precipitins were found in serum from patients chronically colonized in comparison to those patients who were transiently or not colonized. A negative correlation was found between the number of precipitin peaks and clinical conditions, evaluated with Schwachman score, and the number of precipitins and pulmonary functions. In summary, anti-P. aeruginosa antibodies fail to protect against P. aeruginosa bronchopulmonary infections, and are correlated to a more severe disease. Based on our experience, P. aeruginosa antibodies can be considered a reliable index of lung damage.

Helicobacter pylori potentiates histamine release from rat serosal mast cells induced by bile acids

In the present study we have experimentally addressed the effects of Helicobacter pylori on the bile acid capability of histamine release. Bile acids alone were confirmed to be able to induce in vitro histamine release from rat serosal and mucosal mast cells. On the contrary, no significant histamine release was obtained when incubating any Helicobacter pylori preparations alone with mast cells. However, histamine release induced by bile acids was significantly enhanced, without any significant increase in lactate dehydrogenase activity, when whole washed or formalin-killed bacterial cells or crude cell walls were incubated with mast cells in the presence of cholic (0.3 mM), deoxycholic (0.3 mM), or lithocholic (0.3 mM) acids, chenodeoxycholylglycine (0.3 mM), and deoxycholyltaurine (3 mM). The electron microscopic features of mast cells incubated with Helicobacter pylori were consistent with an exocytotic secretion. The release of histamine induced by 0.3 mM deoxycholic acid in the presence of Helicobacter pylori was inhibited by the preincubation of the cells with dimaprit (an H2 agonist) and potentiated by the H2 antagonist, ranitidine. The current results suggest a link between human Helicobacter pylori infection and histamine release and a possible involvement of gastric mucosal mast cells in the pathogenesis of Helicobacter pylori-associated gastritis.

Helicobacter pylori potentiates histamine release from serosal rat mast cells in vitro

Helicobacter pylori seems to be involved in the etiology of peptic ulcer and chronic gastritis. Histamine is fundamental in gastric secretion modulation, and some features of H. pylori-associated gastritis (edema, vasodilatation, inflammatory cell infiltration) are typical of the histamine-mediated response. This in vitro study has been undertaken as a preliminary step, in order to find a possible link between H. pylori and histamine release. H. pylori isolated from gastric biopsies has been tested as whole washed bacterium, whole formalin-killed bacterium, and crude cell wall preparation with serosal mast cells obtained by density gradient centrifugation or elutriation from peritoneal and pleural washings of male Wistar albino rats. Histamine release was assayed fluorimetrically. No significant histamine release was obtained by testing the various bacterial preparations alone with mast cells. On the contrary, whole washed cells, whole formalin-killed cells and crude cell walls from H. pylori have been found to potentiate compound 48/80 or calcium ionophore A23187-induced histamine release. Crude cell walls showed the highest activity, whereas filtered supernatants from broth cultures constantly appeared inactive. The enhancement in histamine release differed between the different strains. The present in vitro study, which shows the potentiating effect of H. pylori on histamine release, may prove interesting; however, at present, clinical implications cannot be inferred and further studies as well as in vivo demonstrations are needed.

Reflux-related gastric mucosal injury is associated with increased mucosal histamine content in humans

BACKGROUND

Experimental studies in the dog and the rat have shown histamine involvement in reflux-related gastric mucosal injury. However, no definite demonstrations of a link between reflux-related gastric mucosal injury and mast cell mediators exist in humans.

METHODS

The relationships between reflux, gastric mucosal histamine content, and gastric histology were assessed in partially gastrectomized subjects presumptively with high (11 Billroth II subjects) and low reflux levels (9 total biliary diversion subjects), respectively. Findings were compared with those in a control group consisting of 8 endoscopically and histologically proven normal subjects.

RESULTS

Bile acid quantity and concentration in the gastric aspirates were significantly greater in Billroth II subjects than in total biliary diversion subjects. Significantly higher cumulative scores for foveolar hyperplasia, mucosal edema, capillary dilatation and congestion, and smooth muscle fibers in the lamina propria were found in Billroth II subjects than in total biliary diversion subjects. Mucosal histamine content as well as mast cell density and degranulation differed significantly between Billroth II and the other two groups.

CONCLUSIONS

These results represent the first demonstration in humans of an association between mast cell mediators and chemical gastric mucosal injury.

Detection of Helicobacter pylori-like organisms in the stomach of some food-source animals using a monoclonal antibody

To investigate a possible animal reservoir of Helicobacter pylori, 15 pigs, 15 rabbits and 5 cows slaughtered for consumption were studied. Raised serum IgG levels were found in 93% of the pigs and 87% of the rabbits, but levels were normal in the cattle. In the controlled testings three of 22 humans had elevated IgG to H pylori and in all three H pylori was detected by the use of monoclonal antibody. Helicobacter pylori were identified in gastric brushings by a monoclonal antibody in 8 out of 10 pigs and 7 out of 10 rabbits. This study suggests an animal reservoir of Helicobacter pylori which may be of importance in human infection.

Helicobacter pylori and luminal gastric pH. Relationships in nonulcer dyspepsia

The relationships between gastric pH and Helicobacter pylori infection were studied in 37 consecutive subjects affected with nonulcer dyspepsia. Each underwent esophagogastroduodenoscopy with multiple gastric biopsies for both H. pylori and histologic assessment, and 24-hr antral pH monitoring. H. pylori was harbored by 59.5% of the subjects with whole gastric spread of infection in all but one patient. Histologic gastritis was shown in 70.3% of the subjects. H. pylori was strongly associated with gastritis, both antral nonatrophic and multifocal atrophic. The ranges of 24-hr pH values were 1.3-6.9 in the H. pylori-positive and 1.2-6.8 in the H. pylori-negative group. Differences in pH values between the two groups were not significant. Moreover, the mean percent time duration of pH above 2, 4, and 6 did not significantly differ between the two groups. Therefore, this study has shown that chronic H. pylori infection is not related to luminal gastric pH.

[Proteins bound to satellite DNA, are present in human nuclear matrix cell preparations]

The presence of protein or complex of proteins that specifically bind to human satellite 3 (HS3) was shown during investigations of the nuclear matrix. The specificity of binding of HS3 was shown by using nuclear matrix immobilized on nitrocellulose. The activity disappeared after extractions of the nuclear matrix. The presence of specific activity in low salt extract was shown by gel retardation assay with whole HS3 fragment. All the subfragments of HS3 after Sau3A restriction (1 kb, 0.36 kb, 0.41 kb) also retarded in the mixture with this protein extract. DNA-protein complexes were stable even in the presence of a 1000-fold excess of competitive DNA. These data are discussed in the frame of hypotheses about the three dimensional organization of interphase chromatin.

In-vitro activity of vancomycin, teicoplanin, daptomycin, ramoplanin, MDL 62873 and other agents against staphylococci, enterococci and Clostridium difficile

The minimum inhibitory concentrations (MICs) of different antibiotics were determined by a broth microdilution method for staphylococci, enterococci and Clostridium difficile. The antimicrobial agents tested were vancomycin, teicoplanin, daptomycin, ramoplanin, MDL 62873, rifampicin and piperacillin, the latter limited to enterococci. In terms of MIC90S, daptomycin (0.89 mg/l). MDL 62873 (0.99 mg/l), and teicoplanin (1.50 mg/l) were found to be highly active against methicillin-resistant Staphylococcus aureus (MRSA). Daptomycin (MIC90 0.48 mg/l), MDL 62873 (0.95 mg/l) and ramoplanin (1.45 mg/l) were the most active drugs against methicillin-resistant S. epidermidis (MRSE). Teicoplanin (MIC90 0.45 mg/l) was the most active agent against enterococci, followed by MDL 62873 (0.65 mg/l) and daptomycin (1.60 mg/l). MDL 62873 gave the lowest MIC90 (0.17 mg/l) for C. difficile. Teicoplanin (MIC90 0.42 mg/l), daptomycin (0.87 mg/l) and ramoplanin (0.98 mg/l) were also very active. Our results indicate that teicoplanin, daptomycin, ramoplanin and MDL 62873, a teicoplanin derivative, are potentially effective alternative antibiotics for treatment of infections caused by staphylococci, enterococci and C. difficile.

Observations on phage-typing of Clostridium difficile: preliminary evaluation of a phage panel

Of the various methods now employed to type Clostridium difficile, the performance of the phage-typing, as proposed by Sell et al., was investigated on a large collection of isolates from various local epidemiological settings. Because those isolates appeared in preliminary trials mostly resistant to the reference phages, the panel was enlarged by including newly isolated phages. The new set was redundant but better suited to the purpose: out of 287 phage sensitivity patterns 8.4% only were resistant in comparison to the 67.6% resistant to the reference one.

Outbreak of Clostridium difficile diarrhoea in an orthopaedic unit: evidence by phage-typing for cross-infection

In a three-week period five patients had diarrhoea in an orthopaedic unit. The first case was clinically diagnosed as pseudomembranous colitis but the causative agent was not sought. Of the remaining cases, two were Clostridium difficile positive. The outbreak then apparently ceased, but during the following several days two of seven stool samples taken at random from asymptomatic patients yielded C. difficile. Phage-typing of the isolates showed that all apparently belonged to the same strain.

Epidemiological studies of Pseudomonas aeruginosa infections in leg ulcers

A 6-month prospective study was carried out in an angiology ward on patients with leg ulcers. Pseudomonas aeruginosa was isolated from about half of the samples from the patients. Of the isolates, 85 were serotyped, fingerprinted as to passive pyocin sensitivity and characterized for antibiotic susceptibility pattern. According to all criteria, the isolates belonged to six strains, two of which were clearly epidemic: one infected 11 patients yielding 52 identical isolates, the other infected 4 patients (19 isolates).

Age-related changes in the prevalence of precipitating antibodies to BK virus in infants and children

Nearly 1000 sera from children were tested by immunoelectro-osmophoresis against BK virus, and age-specific prevalence rates were estimated from birth until the age of 12 years. Declining rates during the first 12 months showed the waning of passive immunity, which at birth reflects the mother's immune status. The changes of prevalence suggested that the peak incidence of primary infections occurred at about 2 years, with an estimated peak annual rate of 24.6%.

[Role of viruses in acute gastroenteritis]

In a two years screening carried out on Florentine children we confirmed that Rotaviruses are the most important ethiological agents of acute gastroenteritis in infants less than two years old, irrespective of sex. We had evidence that Rotavirus diarrhea does not occur with the same incidence every year. Rotavirus gastroenteritis is characterized by profuse diarrhea, vomiting, fever and often by respiratory symptoms. Severe complications have not been observed.

Immunoelectroosmophoresis for the human papovavirus BK

The reaction between BK virus and its antibodies may well be visualized with immunoelectroosmophoresis (IEOP). Serum antibody levels may be compared or graded by reacting them against a continuous antigen front. In seroepidemiologic surveys IEOP compares favourably with hemagglutination inhibition in terms of sensitivity, practicability and reproducibility. Technical conditions are described which are suitable for antigen detection, quantification and identification.

[Serodiagnosis of rotavirus infections in gastroenteritis of infants]

We report the use of the line immunoelectroosmophoresis (LIEOP), a modification of the immunoelectroosmophoresis (IEOP), for the serodiagnosis of rotavirus infection, in comparison with the complement fixation test. We tested 17 paired and 29 single sera from hospitalized children affected by acute gastroenteritis; rotavirus had been searched in the stools both by electron microscopy and IEOP. The LIEOP showed seroconversion in all the 11 cases with positive stools and also in 5 out of 5 patients whose stool sample had been negative. Either we had not been able to detect the virus, or there was an intervening (nosocomial) rotavirus infection. All sera which were reactive by complement fixation with bovine rotavirus were also reactive by LIEOP. Some of the sera which reacted by LIEOP, both with the homologous and the heterologous antigen, were negative by complement fixation.

Biometrical implications of factorial experiments for the study of lymphocyte mitogenic response

Lymphocyte responsiveness to mitogens is affected by a number of experimental variables; the latter may be conveniently studied several at a time, following a factorial design that allows the complete evaluation of the effects of each variable and of their interplays. Statistical inferences may be drawn through an analysis of variance, provided that the data conform to the underlying model, i.e. that the effects are additive and that the errors are normally distributed and homoscedastic. Thymidine incorporation data should first be transformed to log cpm; the effects on the metameter may then be assumed to be additive, and their errors approach normality; the error variances may be affected by the experimental variables involved, so that the homogeneity of the error must be checked before relying on the pooled estimate of the error for parametric tests of significance. The above considerations have been illustrated with factorial experiments on [3H]TdR incorporation by rabbit spleen cells stimulated with varying amounts of PHA-P or PHA-M, under a variety of culture conditions.