Biomedical subjects
P Urbano
Publications and source records attributed to P Urbano.
Burden of unidentifiable mycobacteria in a reference laboratory.
Modern identification techniques at the genomic level have greatly improved the taxonomic knowledge of mycobacteria. In adjunct to nucleic acid sequences, mycobacterial identification has been endorsed by investigation of the lipidic patterns of unique mycolic acids in such organisms. In the present investigation, the routine use of high-performance liquid chromatography (HPLC) of mycolic acids, followed by the sequencing of the 16S rRNA, allowed us to select 72 mycobacterial strains, out of 1,035 screened, that do not belong to any of the officially recognized mycobacterial species. Most strains (i.e., 47) were isolated from humans, 13 were from the environment, 3 were from animals, and 9 were from unknown sources. The majority of human isolates were grown from the respiratory tract and were therefore most likely not clinically significant. Some, however, were isolated from sterile sites (blood, pleural biopsy, central venous catheter, or pus). Many isolates, including several clusters of two or more strains, mostly slow growers and scotochromogenic, presented unique genetic and lipidic features. We hope the data reported here, including the results of major conventional identification tests, the HPLC profiles of strains isolated several times, and the whole sequences of the 16S rRNA hypervariable regions of all 72 mycobacteria, may encourage reporting of new cases. The taxonomy of the genus Mycobacterium is, in our opinion, still far from being fully elucidated, and the reporting of unusual strains provides the best background for the recognition of new species. Our report also shows the usefulness of the integration of novel technology to routine diagnosis, especially in cases involving slow-growing microorganisms such as mycobacteria.
Tentative evidence of AIDS-associated biotype of Mycobacterium kansasii.
Previous studies revealed heterogeneous behavior within the species Mycobacterium kansasii against commercially available DNA probes (Accuprobe M. kansasii culture identification test; Gen-Probe); several isolates, conventionally identified as M. kansasii, failed in fact to hybridize. Looking for a possible association with phenotypic features, we tested a fully characterized panel of 69 clinical isolates of M. kansasii (19 of which were Accuprobe negative) with a semiquantitative micromethod which tests for 19 enzymatic activities (Api Zym; BioMérieux). The strains were from 25 hospitals in 18 Italian towns; 20 isolates came from human immunodeficiency virus type 1-positive patients who fulfilled the Centers for Disease Control criteria for AIDS diagnosis. On the basis of the whole set of phenotypic traits, our strains clustered in two groups, allowing the differentiation of biotypes within the species. There was a perfect association between biotype 2 and hybridization failures with Accuprobe and a very significant association between this novel biotype 2 and AIDS status, which suggests that it differs in virulence.
Nosocomial diarrhoeas in a surgical division hyperendemic for Clostridium difficile: epidemiologic aspects emerging from an analysis of clinical records.
Having previously shown that Clostridium difficile was responsible for an intense and protracted endemic of nosocomial diarrhoeas in the surgical division of a Tuscan hospital, we started a retrospective analysis on all records from the affected division, to cover a period of 15 months. A statistical description is given of a large series of nosocomial diarrhoeas, as well as direct estimates of their incidence rates in selected high risk subgroups. The situation described is epidemiologically unique, and its study tells how an endemic may reach a steady state of high nosocomial morbidity.
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).
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.
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%.
[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.
Surface glycosaminoglycans and calcium distribution in 3T3 cells.
Resting 3T3 cells have relatively more sulphated glycosaminoglycans and Ca2+ in their cell coat than do growing or SV40-virus-transformed cells. It is suggested that the different Ca2+-binding capacity controls cellular activities by affecting the distribution of Ca2+ between the intra- and ecto-cellular compartments.
A rational code for reporting patterns in bacteriocine and bacteriophage typing.
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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.
[Abortive transformation of rabbit cells infected in vitro with polyoma virus].
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Studies on cell-coat macromolecules in normal and virus-transformed BHK 21-C13 cells.
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Electrophoretic analysis of membrane glycoproteins in normal and polyoma virus transformed BHK 21 cells.
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The inhibition of polyoma antigen synthesis and capsid formation by 5-fluorodoxyuridine.
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The Reoviridae family.
The members of the Reoviridae family are extremely varied in host ranges and have such diverse natural histories that it is compelling to conclude that their structural asset and replication strategy are uniquely successful in evolutionary terms. It follows that their study addresses fundamental aspects of virology, besides the ones which are customary with important pathogens affecting humans, animals and plants. We deal here with the present taxonomy of the family Reoviridae and of its genera, two of which (Orbivirus and Rotavirus) are treated separately in this issue. Along with a cursory presentation of the remaining genera, we give a concise update of recent findings on the genus Orthoreovirus.
[Pyocin typing of 111 strains of Pseudomonas aeruginosa isolated in Tuscany, using the Gillies and Govan method].
Pseudomonas aeruginosa strains from Tuscany have been typed for pyocine production against Govan and Gillies' extended set of indicator strains; results have been expressed following a binary code. Among 111 strains only 6 could not be typed; the remaining 105 strains (94.6%) presented 59 different patterns, 44 of which were represented by one isolate only. The most commonly encountered pattern (n. 8045, corresponding to Govan and Gillies' subtype 1e) was shared by 13 strains. Isolates from outpatients or from the environment tended to a uniform distribution of pyocine patterns; those from two different hospitals tended to group into distinct subtypes.
[Multivariate analysis of aminoacyl-tRNA synthetase activities of liver and hepatomas (author's transl)].
Data on the aminoacyl-tRNA synthetase activities in normal liver and in three transplantable rat hepatomas, viz Yoshida's AH 130 and Morris's 5123C and 7793, were studied by means of factor analysis, a powerful technique of multivariate analysis particularly suitable foridentifying factors which theoretically may account for the pattern of interrelations between several variables. The analysis has been performed on 51 patterns of enzyme activities, covering 17 out of the 20 aminoacyl-tRNA synthetases; 80% on average of the total variability of the 17 enzyme activities may be accounted for by the first 4 factors extracted. The enzymes seem to fall into different groups, depending on their relationship with the factors thus identified. The results suggest that enzymes belonging to the same group share a common control mechanism, and are independent of the enzymes belonging to different groups, both in normal liver and in hepatomas.