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Biomedical subjects

A Angeretti

Publications and source records attributed to A Angeretti.

At least 37 records · Page 2Linked to original sources
PubMed1985

Staphylococcus aureus: characters associated with its pathogenicity and sensitivity to antibiotics.

A hundred staphylococcus strains recently isolated from hospital specimens of various kinds were first divided into two groups: mannitol-positive (90 strains) and mannitol-negative (10 strains). Their ability to produce protein A was then correlated with the presence of other metabolic and enzymatic characters typical of S.aureus. The results showed that satisfactory identification of S. aureus in clinical practice requires assessment of other more species-specific characters in addition to the mannitol fermentation, though this is useful as a preliminary screening measure. Evaluation of protein A production would seem as good or even better than evaluation of coagulase for this purpose. It was also found that the strains examined displayed an increased resistance to methicillin, particularly the part of non-aureus (mainly S.epidermidis) strains. Nearly all strains displayed resistance to the penicillins through the production of penicillinase.

Coagulase↗
PubMed1983

Pseudomonas aeruginosa beta-lactamases.

Forty recently isolated hospital strains of Pseudomonas aeruginosa were assayed to determine the part played by the production of beta-lactamase in their resistance to beta-lactamic antibiotics, together with the relative importance of constitutive and inducible enzymes in such resistance in the case of carbenicillin (CB). 62.5% were CB-resistant. In 56% of cases, this resistance was due to the production of a class Vd constitutive enzyme, whereas it was ascribable to intrinsic resistance in the other 44%.

Anti-Bacterial Agents↗
PubMed1983

Separation of IgM for diagnostic purposes by exclusion chromatography: a comparison between six gels.

Sera from rubella patients were fractionated with six different gels on a 0.9 X 30 cm column. Fractionation efficiency was evaluated by determining the IgM, IgA and IgG concentrations in each fraction and titring the rubella virus hemagglutination-inhibiting antibodies before and after treatment with 2-mercaptoethanol. All six gels were able to separate IgM from the other Ig, but the distance between their elution peaks varied considerably. Assessment of the usefulness of a gel for diagnostic purposes requires evaluation of its ability to separate IgM from the oligometric IgA often present in sera and a possible source of diagnostic error. Ultrogel AcA 22 and Bio-Gel A5m gave the best results. In addition to displaying good peak separation, they eluted IgM within their linear fractionation range.

Adult↗
PubMed1983

Comparison between five methods for the separation of IgM.

Five serum fractionation methods were examined with regard to their suitability for use in the demonstration of specific IgM antibodies. It was found that Protein A - Sepharose CL - 4B chromatography leads to higher IgM recovery than absorption with whole Staphylococcus aureus (58% as opposed to 40%). It is also cheaper, since this absorbent can be reused. Contamination with 2-5% IgG and about 70% IgA is encountered with both methods. Quaternary aminoethyl (QAE) - Sephadex chromatography gives excellent IgM recovery (97%) and its cost and execution time are the lowest. IgG and IgA residues are 2% and 53% respectively. Ultrafiltration results in poorer recovery of IgM (31%). However, the sample volume can be brought back to its initial value, or concentrated still further. IgG and IgA residues are 2% and 14%. The cost of the method and the time needed for its execution are relatively high. Gel chromatography is the only method to give a completely IgG- and IgA-free IgM fraction. The percentage of IgM recovered varies in accordance with the ratio between the volume of the sample and that of the column. Very high values may be obtained, but at the expense of heavy dilution. The cost is low, but the method requires a considerable amount of time. In short, none of the five methods is clearly superior to the others. Whether or not a given method is chosen will thus depend on the relative importance attached to the percentage of IgM recovered, the presence or otherwise of IgA, sample dilution, cost, and rapidity of execution.

Chromatography, Affinity↗
PubMed1979

[Antibiotic resistance transmissible in "minor" Salmonella strains recently isolated in the Piedmont region].

The presence of R factors in one hundred (100 strains of Salmonella, recently isolated in Piedmont Region, has been investigated. The resistance to 9 antibiotics has been determined for these strains. 83 proved resistant to one or more antibiotics and in particular 57 of these proved to be multiresistant. Only 18 R factors were put in evidence, 13 of these belonging to Salmonella wien. The majority of the R factors found were present in strains of Salmonella isolated from healthy carriers.

Ampicillin↗
PubMed1979

[Influence of composition of the culture media on the in vitro determination of the bacterial sensitivity to sulfonamides, trimethoprim and cotrimoxazole].

The difficulties concerning the interpretation of results of susceptibility tests to sulphonamides, trimethoprim, co-trimoxazole have been investigated. The zones of inhibition produced by discs containing these drugs are peculiar since frequently they contain a light bacterial growth and small colonies. Therefore the real sensitivity or resistance of the microorganism is questionable. Susceptibility tests performed on media of different composition, have shown that the phenomenon is chiefly due to the presence in the medium of thymidine and methionine. Both the substances are end-products of the metabolic pathway on which act sulphonamides, trimethoprim, co-trimoxazole. When they are in the medium, they can be available for the bacteria in spite of the inhibition caused by the mentioned drugs.

Bacteria↗
PubMedDate not supplied

[Serotyping of Salmonella isolated in the Piedmont region in the years 1975-1976].

Ninehundredtwentysix bacteria of genus Salmonella, collected from hospitals, provincial laboratories and university centers of Piedmont (Italy) have been serologically tested. The serotypical frequencies were compared with those reported in literature. Our findings shown that the appearance of new and unusual serotypes is dominant in comparison to traditional ones.

Humans↗
PubMedDate not supplied

CMV-specific polymeric and monomeric IgA antibodies in serum of renal transplant patients.

CMV-specific IgA, IgM and IgG antibodies were detected by ELISA in sera from 81 renal transplant patients. Twenty-seven patients were followed from transplantation; 6 patients who underwent on transplantation before the beginning of the study were followed during admissions for graft failure or acute illness; 48 outpatients were periodically monitored. One of the patient followed from transplantation experienced a primary CMV infection, serologically demonstrated by the appearance of specific IgM and IgG. Specific IgA appeared at the same time as IgM and lasted for about six months. A specific IgA response was observed in all but five recurrent CMV infections too, even when specific IgM were not present. In all outpatients periodically monitored for CMV serology specific IgA were not found. About specific IgA polimerization, a transient marked polymeric IgA (p-IgA) response was observed in only the primary infection whereas in all the other IgA positive patients, specific IgA were represented by monomers (m-IgA).

Adult↗
PubMedDate not supplied

Anti-HBc polymeric IgA antibodies in serum from acute hepatitis B patients.

Serum anti-HBc IgA antibodies can be demonstrated in acute hepatitis B patients. At first, they are mainly polymeric (p-IgA), whereas monomeric IgA (m-IgA) become detectable 3 months later. In most cases, anti-HBc IgA cannot be demonstrated after 6-12 months. From a diagnostic point of view, specific p-IgA can be regarded as a marker of active infection but, compared to IgM, their demonstration is more difficult.

Acute Disease↗
PubMedDate not supplied

[Specific IgA in the serological diagnosis of viral infections].

In acute viral infections, specific IgM antibodies appear early and persist for a short period of time; by contrast IgG antibodies persist longer. The diagnostic significance of specific serum IgA is still discussed. We observed that in acute systemic infections, serum IgA appear early and are mainly polymeric (p-IgA) whereas monomers (m-IgA) appear in late convalescence. On the other hand, in secondary infections or in reinfections these immunoglobulins are mainly represented by monomers. In mucosa confined infections, serum IgA are almost absent suggesting that their synthesis is not related to mucosal stimulation.

Antibodies, Viral↗
PubMedDate not supplied

Anti-HIV and anti-HBc antibodies and HBsAg in postmortem blood of drug addicts: the picture for 1988.

Serological markers of HIV and HBV infections were studied in 90 drug addicts who died in 1988 and were medicolegally autopsied at the Institute of Forensic Sciences, University of Turin. Nineteen (21.1%) displayed evidence of HIV infection, demonstrated by the presence of anti-HIV antibodies; fifty-nine (65.5%) HBV infection, demonstrated by the presence of anti-HBc antibodies and/or HBsAg; nine (10%) had HBsAg, indicating potential infectiousness for HBV infection.

Adolescent↗
PubMedDate not supplied

[Specific IgG for viral capsid antigen (VCA) of Epstein-Barr virus: evaluation of several commercial kits].

Four methods to detect IgG antibodies to Epstein-Barr virus in serum samples of aspirate in renal transplant patients were evaluated. Further to technical characteristics, the assays were compared as to sensitivity, specificity and positive and negative predictive value. 100% of specificity was found for all methods whereas sensibility and negative predictive value were different among the different methods.

Antigens, Viral↗
PubMedDate not supplied

[Stability of specific antibodies in blood collected on filter paper disks].

Immunoglobulin G (IgG) and M (IgM) stability in serum samples collected on filter paper disks and stored at different temperatures was evaluated. IgG and IgM concentration measured by immunonephelometry was fairly stable for 4 weeks at 4 degrees C, whereas it decreased to about 50% of total at room temperature and at 37 degrees C. By ELISA, no significative loss in antibody activity of IgG was observed after 6 months at 4 degrees C. At 37 degrees C the loss was greater but still acceptable. Antibody activity of IgM decreased more rapidly than that of IgG: IgM were stable at -20 degrees C, whereas had a significative loss of activity after 5 weeks both at 4 degrees C and 37 degrees C. Finally, it is to note that a storage in saturated water vapour seems not to interfere with immunoglobulins stability.

Blood Specimen Collection↗
PubMedDate not supplied

[A fractionation method for human blood for the separation of subclasses of IgG].

A serum fractionation method which permits a good separation among IgG subclasses is proposed. By loading serum on a Protein A-sepharose column, IgG3 are readily recovered as they do not bind to the Protein A. IgG of the other subclasses are eluted, equilibrated at pH 6 and loaded either on a chromatofocusing column, or on an anion exchanger gel. In these conditions IgG4 are retained, and then recovered by lowering the pH, whereas IgG1 and IgG2 pass through the column and can be recovered separately by absorption on a Protein A column and elution with a decreasing pH gradient.

Blood Specimen Collection↗