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Biomedical subjects

S De Flora

Publications and source records attributed to S De Flora.

At least 163 records · Page 9Linked to original sources
PubMed1977

Hepatitis B in subjects treated with a drug containing immunoglobulins.

In late 1974 and early 1975, several cases of viral hepatitis were reported in Italy among subjects who had received subcutaneous injections of a drug containing human immunoglobulins that was prescribed for the treatment of allergies. Epidemiologic and laboratory investigations provided evidence that the original immunoglobulins, the series of the drug containing these immunoglobulins, and sera from a number of patients were all positive for hepatitis B surface antigen (HBs Ag) of the adw subtype, which is relatively rare in Italy. Some sera from patients and healthy subjects treated with the HBs Ag-positive drug were also found to be positive for antibody to HBs Ag of the adw subtype. The clinical course of the disease was consistent with typical forms of icteric hepatitis in all patients examined. The average length of the possible incubation period was 111-143 days, and an inverse relation was observed between the number of doses administered and the length of the incubation period. The possibility that immunoglobulins can be responsible for the transmission of viral hepatitis raises a number of theoretical and practical problems concerning control and use of these blood products.

Adolescent↗
PubMed1977

Toxicity and mutagenicity of hexavalent chromium on Salmonella typhimurium.

Four hexavalent and two trivalent chromium compounds were tested for toxicity and mutagenicity by means of the Salmonella typhimurium/mammalian-microsome test. All hexavalent compounds yielded a complete inhibition of bacterial growth at doses of 400 to 800 mug/plate, a significant increase of his(+) revertant colonies at doses ranging from 10 to 200 mug, and no effect at doses of less than 10 mug. The distinctive sensitivity of the four Salmonella strains tested (TA1535, TA1537, TA98, and TA100) suggested that hexavalent chromium directly interacts with bacterial deoxyribonucleic acid by causing both frameshift mutations and basepair substitutions. The latter mutations, which are prevalent, are amplified by an error-prone recombinational repair of the damaged deoxyribonucleic acid. On the average, 1 mumol of hexavalent chromium yielded approximately 500 revertants of the TA100 strain, irrespective of the compound tested (sodium dichromate, calcium chromate, potassium chromate, or chromic acid). The mutagenic potency of the hexavalent metal was not enhanced by adding the microsomal fraction of rat hepatocytes, induced either with sodium barbital or with Aroclor 1254. The two trivalent compounds (chromium potassium sulfate and chromic chloride), with or without the microsomal fraction, were neither toxic nor mutagenic for the bacterial tester strains.

Chromates↗
PubMed1976

Hepatitis B infections in renal transplantied patients.

Multiple serum samples collected from ten renal transplanted patients were examined by means of radioimmunoassay procedures in order to check and quantitate both hepatitis B surface antigen (HBs Ag) and antibody to it (anti-HBs). The anticomplementary activity of serum, levels of serum immunoglobulins and other laboratory parameters were also tested and related to the clinical followup of patients in the pre- and post-operative period, during which they underwent immunosuppressive treatment with azathioprine, methyl-prednisolone and antilymphocyte globulin. The results obtained provided evdence that all subjects under examination either were currently infected or had been previously exposed to hepatitis B virus. Five basic situations could be detected: state of persistent HBs Ag carrier (I) or of persistent positivity for anti-HBs (II) or reinfections (IV) and presence of HBs Ag/anti-HBs immunocomplexes (V). All HBs Ag and anti-HBs-positive sera were ayw subtype, which is typical for hepatitis B virus circulating in Italy.

Acute Disease↗
PubMed1975

Spread of hepatitis-B infections. A seroepidemiologic study.

A solid-phase radioimmunoassay (R.I.A.), allowing simultaneous detection and quantitation either of HB, Ag or of anti-HBs, was applied to check the spread of hepatitis-B virus (H.B.V.) infections in various groups of population. R.I.A. procedures were also used to validate positive reactions and to determine the subtype specificity of sera. The overall prevalence of neutralizing anti-HBs in tested sera was almost 4-fold higher, although generally at rather low titres, than prevalence of HBs Ag. Frequency of HBs Ag and anti-HBs was rather high among healthy individuals from the normal Italian population and was extremely high among individuals from East Africa (Tanzania), as well as among healthy or sub-normal institutionalized subjects, among dialyzed renal patients and unselected blood-donors from 5 Italian towns. 80.2% of HBs Ag and anti-HBs detected in Italy were ay subtype, while most of positive sera from Tanzania (72.3%) were ad, which extends the map of H.B.V. subtypes in Africa. All tested ad antigens, either from Italy and from Tanzania, carried the w secondary determinant. Low-titre neutralizing anti-HBs, predominantly bearing a and d specificity, were also found in almost all examined preparations of standard immunoglobulins, which were imported from U.S.A.

Adult↗
PubMed1975

Radioimmunoassay for the simultaneous detection and quantitation of hepatitis B surface antigen and of the homologous antibody.

A solid-phase radioimmunoassay procedure is presented, which allows the simultaneous detection and quantitation of HB, Ag and of anti-HBs. This procedure involves short preliminary incubation of test sera and of negative controls with a standard HB, Ag. The standard HBs Ag is diluted, according to preliminary assays, in order to yield a count ratio to negative controls of 10 to 1. Therefore, a value of 10 is ascribed to the counts of positive controls (standard HBs, Ag + HBs-negative serum) and counts of all test sera are proportionally related. The values obtained are denominated HBs Units. Test sera are considered to be positive for HBs Ag or anti-HBs when the corresponding HBs Units are significantly higher or lower, respectively, than the average value of standard antigen controls. Including the reference standard HBs Ag controls in each set of assays ensures the quantitative reproducibility of results among different assays and among different laboratories. Titres of serum HBs Ag and anti-HBs can be expressed as end-point dilutions, simply by plotting the corresponding HBs Units on a nomography. This was drawn according to the indications emerging from analysis of the radioimmunoassay kinetics. Laboratory assays and the practical application of the combined procedure over several thousands determinations showed that the binding capacity of the solid-phase substrate used (small antibody-coated polystyrene tubes) is extremely homogeneous. Such homogeneity accounts for a very high accuracy and reproducibility of quantitative results.

Antibodies↗
PubMed1975

Detection of animal viruses in coastal seawater and sediments.

Animal viruses, predominantly enteroviruses, were detected in shallow water at bottom depths and in clastic marine sediments. Viruses accumulated in sandy and slimy deposits of the sea bottom near the shore and could be easily released into water by means of simple mechanical shaking.

Enterovirus↗
PubMed1975

Quantitative detection and typing of HBs Ag and anti-HBs by radioimmunoassay techniques.

Small polystyrene tubes coated with purified anti-HBs were used as solid-phase substrate for the detection of HBsAg and anti-HBs by RIA procedures. This substrate yields highly sensitive, reproducible and homogeneous results. The sensitivity and the kinetics of various solid-phase RIA procedures for anti-HBs detection were explored. The preliminary heating of sera at 56 degrees C for 30 min is needed, in order to remove a thermolabile aspecific inhibitor, which is not identifiable with complement. In particular, an RIA procedure is suggested, based upon preincubation of serum to be tested with a serum containing low amounts of HBsAg (count ratio to negative sera = 10:1) and suitable for the combined detection and quantitation of HBsAg and of anti-HBs. The results are expressed as HBs Units, which provide a simple and standardizable unit allowing estimation of HBsAg and anti-HBs amounts over a range of as much as one million values. A number of RIA procedures were also studied for typing HBsAg and anti-HBs, which are also suitable to evaluate 'in vitro' the degree of cross immunity among the various subtypes.

Animals↗
PubMed1975

Epidemiological distribution and significance of anti-HBs.

HBsAg and anti-HBs neutralizing antibodies were quantitatively detected and typed by solid-phase RIA procedures in various random populations and in commercial lots of standard immunoglobulins. The prevalence of anti-HBs was considerably higher than prevalence of HBsAg, and the specificities of HBsAg and anti-HBs overlapped within the single groups of population. The results obtained provided evidence that hepatitis B virus infections are wide-spread, particularly in communities, and that the distribution of subtypes varies according to geographical patterns. The degree of cross neutralization between homotypic and heterotypic subtypes was not quantitatively constant, implying that the amounts of the single reacting determinants probably vary among HBsAg particles. It is also stressed that a number of sera containing both HBsAg and anti-HBs escape identification, since a fairly long interval can elapse during which the decreasing levels of HBsAg and the increasing levels of anti-HBs equalize in the blood.

Adolescent↗
PubMed1975

[Sensitivity and various radioimmunologic procedures for the research and typization of the antigen and antibody of hepatitis B].

The kinetics of solid-phase radioimmunoassay (SPRIA) procedures for HBsAg detection were explored. Most HBsAg-positive sera showed an evident prozone phenomenon and the optimal reaction zone occurred at considerable dilution rates. Subsequent dilutions (in negative serum) resulted in a linear decrease of counts, plotted on log-logit graphs, to the lowest level of positivity (cpm positive serum/cpm negative sera=2.1/1). As compared with commercial solid-phase substrates, the sensitivity of HBsAg detection was enhanced when the SPRIA procedure was carried out in small polystyrene tubes, previously coated with purified antibody by simple contact. Various SPRIA procedures were described for HBsAg typing and suggested also as confirmatory tests for suspect positive sera. The sensitivity and the kinetics of three methods for the detection of anti-HBsAg antibody (anti-HBs) were investigated. These methods are based upon the neutralization of a standard dose of HBsAg (methods A and B) or upon the competitive inhibition of labeled antibody (method C). One of these methods fits the combined detection of HBsAg and anti-HBs. Finally, some SPRIA procedures were suggested for anti-HBs typing and some applications were shown.

Animals↗