Biomedical subjects

M W Bentzon

Publications and source records attributed to M W Bentzon.

At least 19 recordsLinked to original sources

PubMed1992

Rabies vaccine standardization: International Collaborative Study for the Characterization of the fifth International Standard for Rabies Vaccine.

A collaborative study was carried out to establish a replacement for the International Standard for Rabies Vaccine, the stocks of which are exhausted. Three rabies vaccines for human use derived from different rabies virus strains and prepared on different cell culture substrates were compared with the International Standard for Rabies Vaccine using in vivo and in vitro assay methods in a collaborative study involving 14 participants. The proposed fifth International Standard (PISRAV) which was derived from the same virus strain as the present international standard preparation, the Pitman Moore (PM) strain, was found to be approximately twice as potent relative to the International Standard in immunogenicity assays as in antigenicity assays. On the other hand another vaccine, derived from the LEP strain, was considerably more potent in antigenicity assays than in immunogenicity assays. The glycoprotein of the proposed replacement standard measured in antigenicity assays appeared to be stable at +37 degrees C for 245 days, whereas the immunogenicity of the proposed replacement vaccine was sensitive to this heat treatment and the vaccine lost 66% of its immunogenic potency. The results of this study indicate that the NIH protection test should continue to form the primary basis for potency assay of rabies vaccine as glycoprotein content does not appear to correlate with immunogenic potency for different types of vaccine. The vaccine coded PISRAV has been established as the fifth International Standard for Rabies Vaccine and a potency of 16 International Units of Rabies Vaccine (based on the immunogenicity assays) assigned to the contents of each ampoule. Each ampoule has also been assigned a unitage of 10 IU of PM Rabies Virus Glycoprotein and 135 IU of PM Rabies Virus Ribonucleoprotein.

Animals↗

PubMed1992

Enzymuria in neonates receiving continuous intravenous infusion of gentamicin.

Urinary excretion of the tubular enzymes NAG and AAP was investigated during gentamicin treatment of 105 newborn infants. The values found for NAG and AAP show a significant positive correlation. The urinary excretion of NAG was on the average 92% higher during gentamicin treatment as compared with non-treatment periods in the same newborn infant (33 infants). The same tendency applied to AAP. Newborn infants receiving continuous intravenous infusion of gentamicin were not found to be at greater risk of nephrotoxicity than those receiving intermittent gentamicin treatment, using NAG and AAP as an index of nephrotoxicity. The changes in NAg and AAP within treatment periods were studied. During gentamicin treatment an insignificant average increase in the urinary excretion of NAG occurred, whereas a significant decrease was found during non-treatment periods. A significant negative correlation was found between urinary excretion of NAG and birth weight/gestational age. The long-term effect of the higher excretion of NAG and AAP in newborn and adult patients during aminoglycoside treatment is unknown.

Acetylglucosaminidase↗

PubMed1992

Relation between enzyme-linked immunosorbent assay and radioimmunoassay for detection of antibodies to the capsular polysaccharide of Haemophilus influenzae type b.

The measurement of antibodies to the capsular polysaccharide (PRP) of Haemophilus influenzae type b (Hib) is important because vaccines inducing such antibodies are now available. We developed and evaluated an enzyme-linked immunosorbent assay (ELISA) for detection of these antibodies based on direct coating of the plates with tyraminated PRP. The assay fulfilled the requirements for parallel line assays; it was sensitive, specific, and reproducible with a coefficient of variation between days of 19%. Results from the ELISA were compared with results from radioimmunoassay and a correlation coefficient of 0.93 was found. Results obtained by the two methods were proportional and the relation was independent of the antibody level. The relation between them was also unaffected by the contribution of different antibody isotypes, indicating that these were measured to the same extent by both methods. ELISA employing direct coating of the plates with tyraminated PRP represents a useful alternative for detection of antibodies when studying immunogenicity of Hib vaccines.

Antibodies, Bacterial↗

PubMed1991

Sensitivity to sensitins and tuberculin in Swedish children. III. Sequential versus simultaneous skin testing.

The aim of this study was to determine whether simultaneous and sequential skin testing with tuberculin and sensitins give consistent results. A total of 475 8- or 9-year-old schoolchildren were skin tested sequentially, at an interval of 3 days, with PPD tuberculin and with either Mycobacterium scrofulaceum or M. avium sensitin. The results were compared with those of 470 simultaneously tested children chosen from the same living area. There were no statistically significant differences between the frequencies of the reactions of sequentially and simultaneously tested children. When the sequential testing procedure was employed, 3.1% reacted to tuberculin, 19% to M. avium sensitin and 30% to M. scrofulaceum sensitin, taking a 6 mm cut-off. The corresponding figures for the simultaneously tested children were 4.7, 21 and 36%, respectively. Thus, there was no indication that the simultaneous testing procedure in itself influenced the results, neither was there any sign of a booster effect when testing in sequence with an interval of 3 days in non-BCG-vaccinated children.

Antigens↗

PubMed1991

Sensitivity to sensitins and tuberculin in Swedish children. I. A study of schoolchildren in an urban area.

Non-BCG-vaccinated schoolchildren (8 or 9 years of age) were simultaneously tested on separate arms with 2 IU PPD RT23 and 0.1 microgram Mycobacterium avium sensitin RS10 or 0.1 microgram Mycobacterium scrofulaceum sensitin RS95. None of the 2819 analysed children had any known exposure to tuberculosis. A total of 3.4% reacted with an induration greater than or equal to 6 mm to PPD RT23. Half the number of children were tested with M. avium sensitin and 25.4% reacted while the remaining were tested with M. scrofulaceum sensitin and 32.4% reacted when the cut-off was 6 mm. For about 90% of the children the sensitin reaction was larger than or equal to the tuberculin (PPD RT23) reaction. Correlation analyses showed that moderate and high PPD RT23 values were combined with still higher sensitin values, indicating that the tuberculin reactions were mainly cross-reactions due to the antigenic similarity between tuberculin and sensitins. The presence of birds, dogs and cats in the homes was combined with an increased frequency of children reacting to the sensitins used. The children with reactions to PPD RT23 greater than or equal to 6 mm were examined and chest X-rays were performed. None of them showed any signs or symptoms of mycobacterial disease. In non-BCG-vaccinated Swedish schoolchildren without clinical signs of tuberculosis and without known contact with a contagious tuberculous person, indurations less than 12 to 14 mm on tuberculin testing are probably caused by atypical mycobacteria. In such cases sensitin tests should be performed to verify the suspicion.

Animals↗

PubMed1991

Sensitivity to sensitins and tuberculin in Swedish children. II. A study of preschool children.

Non-BCG-vaccinated preschool children (4 or 5 years of age) were simultaneously tested on separate arms with a 2 IU PPD RT23 and 0.1 microgram Mycobacterium avium sensitin RS10 or 0.1 microgram Mycobacterium scrofulaceum sensitin RS95. None of the 762 children had any known exposure to tuberculosis. A total of 8.8% reacted with an induration (greater than or equal to 3 mm to PPD RT23 while 2% reacted with greater than or equal to 6 mm. Half the children were tested with M. avium sensitin: 18.9 and 7.8% reacted when 3 and 6 mm cut-off points, respectively, were taken. The remaining children were tested with M. scrofulaceum sensitin: 18.4 and 6.3%, respectively, reacted. In a previous study of schoolchildren aged 8 or 9 years, reactions to sensitins were considerably more frequent. Thus, sensitisation by atypical mycobacteria seems to increase from the preschool to the early school age. This finding probably reflects a continuous exposure of the children to atypical mycobacteria from various sources. The preschool children with a reaction to PPD RT23 greater than or equal to 6 mm were examined and chest X-rays were performed. All children were healthy but one child had enlarged lymph nodes in the mediastinum and abdomen. It cannot be excluded that these pathological findings were caused by atypical mycobacteria.

Age Factors↗

PubMed1991

Ten and a half years seroepidemiology of Mycoplasma pneumoniae infection in Denmark.

The study was based on a computerized card index of 9161 patients who had at least one positive blood specimen in the Mycoplasma pneumoniae complement fixation test. A total of 12,562 specimens from these patients had been sent to Statens Seruminstitut from hospitals and general practitioners during a 10.5-year period. The period encompassed a previously described endemic period in a 30-year study of the epidemiological pattern of M. pneumoniae infection in Denmark. The serological data presented support the hypothesis advanced here that a more than sixfold increase of children in day care might have contributed to a change in the epidemiological pattern. The correlation between age and level of specific antibodies, as well as persistence of seropositivity, were also investigated.

Adolescent↗

PubMed1991

MPB 64 possesses 'tuberculosis-complex'-specific B- and T-cell epitopes.

We have developed monoclonal antibodies (MoAb) reactive with a protein from Mycobacterium tuberculosis of apparent molecular mass 24 kDa. This protein was shown to be identical with MPB 64 (Harboe et al.,) MoAb bound to four different epitopes of which two were restricted to the 'tuberculosis complex' and two were also found in mycobacteria not belonging to the 'tuberculosis complex'. The cross-reactive MoAb demonstrate that MPB 64 is present in more mycobacterial species than previously assumed. MPB 64 was shown to induce strong delayed type hypersensitivity (Dth) reactions in outbred guinea pigs immunized with M. tuberculosis and M. bovis bacille Calmette-Guérin (BCG). No reaction was observed in animals immunized with mycobacteria not belonging to the 'tuberculosis complex'. The Dth-inducing capacity of MPB64 was compared with that of another 24 kDa protein purified from M. tuberculosis and of the previously described 38 kDa protein. The Dth responses to these three antigens were further analysed in four inbred guinea pig strains. A genetic restriction of the ability of the animals to respond to MPB 64 as well as to the 38 kDa protein was observed.

Animals↗

PubMed1991

The cell mediated and humoral immune response to vaccination with acellular and whole cell pertussis vaccine in adult humans.

The cell mediated immune response (CMI) against pertussis antigens following vaccination with the traditional Danish whole cell pertussis vaccine (WC-P) and the Japanese acellular pertussis vaccine (A-PV) JNIH-3 was studied in four adult human volunteers. Vaccination with the A-PV induced an in vitro proliferative response of peripheral blood lymphocytes to pertussis toxin (PT) subunits S2-S4, S3-S4 and S5 and the filamentous hemagglutinin (FHA), and a better serological response to native PT, detoxified PT (dPT) and FHA than the WC-PV. The induced CMI and serological response were followed over a period of 17 weeks, and were not seen to decline during this period. Further, an in vitro proliferative response to Bordetella pertussis agglutinogen 2 and 3 were demonstrated using lymphocytes from recently and not-so-recently pertussis-vaccinated adults.

Adhesins, Bacterial↗

PubMed1991

T-cell proliferative response to antigens secreted by Mycobacterium tuberculosis.

An infection model of human tuberculosis was established with C57BL/6J mice. The lymphocyte proliferative responses to antigens from Mycobacterium tuberculosis were investigated during the course of infection and compared with results obtained with a group of mice immunized with large amounts of killed bacteria. The two groups responded similarly to a number of mycobacterial antigens, but marked differences in responses against secreted antigens were found; only infected mice responded vigorously to these. The responding lymphocyte subpopulation was made up of L3T4+ T lymphocytes under restriction of the Ia molecule.

Animals↗

PubMed1991

The epidemiology of Neisseria gonorrhoeae isolates in Dakar, Sénégal 1982-1986: antimicrobial resistance, auxotypes and plasmid profiles.

A total of 460 Neisseria gonorrhoeae isolates from patients seen at three clinics in Dakar, Sénégal, 1982-1986, have been investigated. In this period a significant change in antimicrobial susceptibility was observed: the percentage of strains susceptible to penicillin (MIC less than or equal to 0.08 micrograms/ml) fell from 61 to 18 (p less than 0.0001) and the percentage of resistant strains (MIC greater than or equal to 1.2 micrograms/ml) increased from 18 to 46. Among penicillin-resistant strains the proportion of penicillinase-producing strains (PPNG) was fairly constant (range 35-55%). The determination of susceptibility to anti-microbial agents performed locally allowed detection of approximately all PPNG strains whereas the increase in the occurrence of strains with chromosomally determined resistance was not revealed. The study comprised 70 PPNG strains of which 19% (13/70) carried the 7.4 kb Asian plasmid and 81% (57/70) the 5.3 kb African plasmid. None of these strains possessed the 38 kb conjugative plasmid, whereas it was found in 4.5% of the 376 non-PPNG strains available for plasmid analysis; 92% (410/446) of all strains had the small 4.2 kb plasmid and 5.4% (24/446) did not contain any plasmid. Overall, auxotype zero and proline-requiring strains were predominant, accounting for 53% (244/460) and 28% (131/460), respectively. In general, PPNG strains carrying the 5.3 kb plasmid were auxotype zero (49/57 = 86%) and those carrying the 7.4 kb plasmid were proline-requiring (9/13 = 69%).

Female↗

PubMed1991

Proliferative response to seven affinity purified mycobacterial antigens in eight strains of inbred mice.

This study compares the T-cell-stimulating ability of different mycobacterial antigens. The responses to crude culture filtrates and seven affinity-purified antigens were investigated in eight strains of inbred mice. Large differences in the stimulating abilities of the antigens were observed, and four antigens were found to give a powerful T-cell stimulation. Some antigens divided the strains into high and low responders, while a 17-kDa antigen was found to be exceedingly T-cell stimulatory in mice of all tested haplotypes. The responses of the eight strains were analyzed by comparing the response patterns of the strains. Using a statistical model based on antigen ranking, five strains were found to have a similar response pattern; three strains were found to differ. These results demonstrate the significance of the choice of mouse strain in studies of mycobacterial immunology and, furthermore, indicate that when research is conducted to develop new mycobacterial vaccines, it is important to include panels of antigens.

Animals↗

PubMed1990

A subdivision of strains of Staphylococcus aureus in the 94,96 complex by means of experimental phages.

In order to facilitate epidemiological investigations a subdivision of Staphylococcus aureus strains belonging to the 94,96 complex by means of two experimental phages, 16 and 47A, was performed. These phages were selected from the nine experimental phages initially examined because they gave the greatest discrimination. On the basis of reactions with these two phages, 2199 isolates which reacted with phages 94 and 96, and 773 isolates which reacted with phage 96 alone, were each subdivided into two major and two minor groups. Strains with different phage patterns were in a few cases (2/64) isolated from the same deep body site in a patient, and lysogenisation experiments suggested that differences in phage patterns were determined by the presence of prophages. Strains with the phage patterns 94/96 and 96 were found to be unevenly distributed throughout Denmark. This regional distribution suggested that particular strains might predominate in some areas. The extended phage patterns with the experimental phages did not give any retrospectively useful epidemiological information. It is proposed that in future phages 16 and 47A be used for specific investigations into the sources and relatedness of strains involved in small incidents.

Bacteriophage Typing↗

PubMed1989

[Treatment of gonorrhea at the Venereal Disease Clinic in Copenhagen in 1985. A study of the efficacy of standardized treatment compared with the sensitivity of Gonococcus to penicillin in vitro].

In 1985, a total of 1,140 patients (907 men and 503 women) were treated for gonorrhoea at the Copenhagen County Outpatients Clinic at Rudolph Berghs Hospital. Failure of the standard treatment regimen (pivampicillin plus probenecid; patients stating penicillin allergy received a Sulfotrim-regimen) occurred in 79 (5.6%). A significant association between the in vitro susceptibility to penicillin and the efficacy of the standard treatment regimen was found; among 1,139 patients with uncomplicated urogenital gonorrhoea caused by penicillin susceptible gonococci, the failure rate was low (0.4-1.9%); the failure rate was high in patients infected with penicillin resistant gonococci. Continued surveillance of the in vitro antimicrobial susceptibility of gonococci is recommended as a basis for the choice of standard treatment regimen.

Drug Resistance, Microbial↗

PubMed1989

Estimation of guinea pig antigen-specific and non-specific suppressor cell activity.

A functional assay for the quantitative estimation of suppressor cell (SC) activity in guinea pigs has been developed. Cultures of antigen-stimulated peripheral blood lymphocytes (PBL) from sensitized guinea pigs develop SC activity. The suppression of proliferation can be demonstrated in antigen-stimulated autologous co-cultures of precultured and freshly isolated PBL. The extent of suppression is dependent on the preculture antigen concentration but not the preculture period and it consists, as demonstrated with PBL from doubly sensitized guinea pigs, of an antigen-specific and a non-specific component. The observed SC activities were not due to an alteration of the kinetics of the co-cultures. The estimates of suppression are highly dependent on corrections for the values of the control cultures. The present method may prove useful in immunological studies of mycobacterial infections in guinea pigs.

Animals↗

PubMed1989

Importance of blood volume cultured in the detection of bacteremia.

The influence of the volume of blood cultured on the rate of detection of bacteremia was evaluated in a routine 12-tube blood culture system using 1693 samples from 1502 patients. Blood samples were drawn simultaneously into two transport tubes. The blood volume cultured was the only varying parameter. Generally, 17% more cultures with clinically significant microorganisms (both Enterobacteriaceae and gram-positive cocci) were found when blood from two instead of one tube was used (in most cases comparing 13-16 ml of blood with 6.5-8 ml). Of the most prevalent species, the maximum average extra yield was observed for Staphylococcus aureus (26%) followed by Escherichia coli (16%) and Streptococcus pneumoniae (12%). In adults most cases of bacteremia are low-grade. The grade of bacteremia in our patient population was on average as low as 0.25 CFU/ml blood. Therefore, all patients suspected of having bacteremia should have the benefit of a sufficient volume of blood cultured. Since the volume of blood cultured seems to be the single most important factor in the detection of bacteremia, it is imperative that the volume is the same in comparative studies of different blood culture systems.

Bacteria↗

PubMed1989

Potency assay of antibodies against rabies. A report on a collaborative study.

The relative potencies of a number of rabies immunoglobulin preparations were estimated in an international collaborative study comprising eight laboratories in five countries. Two assay methods were used: a virus neutralization test in mice (MNT) and a virus neutralization test in cell culture (RFFIT). Differences between the results obtained by the two methods, which have been reported, could not be generally corroborated. The results indicate that in some laboratories the MNT cause difficulties and give results different from those obtained by RFFIT. In other laboratories such difficulties are not encountered. The results seem to indicate that the RFFIT is a more reliable method than the MNT.

Analysis of Variance↗

PubMed1989

Coronary risk factors, development of myocardial infarction, and plasma oestrogens: a prospective case-control study in men.

A number of studies have reported hyperoestrogenaemia in men surviving an acute myocardial infarction (AMI). This has led to speculations that hyperoestrogenaemia might be a coronary risk factor. It is not clear why plasma levels of oestrogens should be elevated in coronary heart disease. To ascertain whether hyperoestrogenaemia might be present before the onset of a myocardial infarction, we performed a prospective study in 252 men above the age of forty who within the following 5 years suffered an AMI and, as controls, 526 men matched for age and coronary risk factors and 329 randomly selected men. Mean plasma concentrations of oestradiol and oestrone did not differ significantly between the groups. This suggests that hyperoestrogenaemia is not a coronary risk factor and thus, if present after the AMI, is more likely develop concurrently with the myocardial infarction.

Adult↗