Biomedical subjects

M W Bentzon

Publications and source records attributed to M W Bentzon.

At least 37 records · Page 2Linked to original sources

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↗

PubMed1989

Resistance to dicloxacillin, methicillin and oxacillin in methicillin-susceptible and methicillin-resistant Staphylococcus aureus detected by dilution and diffusion methods.

A total of 54 Staphylococcus aureus strains of varying methicillin resistance were investigated for their resistance to methicillin, oxacillin and dicloxacillin by different diffusion tests. Inhibition zones were measured around locally prepared paperdiscs with 10 micrograms methicillin, 5 and 10 micrograms oxacillin, 5 and 10 micrograms dicloxacillin, PDM paperdiscs with 10 micrograms methicillin or oxacillin and Neo-sensitabs tablets with methicillin or oxacillin. All diffusion tests were performed both with Mueller-Hinton agar and Danish Blood agar as well as at 37 degrees C and 30 degrees C and read after overnight incubation. Differences in zone diameter under different conditions were found to be independent of the susceptibility level of the strains. Seventeen of the strains were detected as methicillin-resistant (MRSA) by two methods including high inoculum and prolonged incubation at 30 degrees C. The minimum inhibitory concentration (MIC) of the 54 strains was determined by a plate dilution method at 30 degrees C and 37 degrees C. A 10 micrograms locally prepared methicillin disc detected all MRSA strains with no false reactions either at 37 degrees C or 30 degrees C on Mueller-Hinton agar. Investigations with oxacillin discs had to be performed at 30 degrees C or with a 5 microgram disc in order to detect correctly. PDM paperdiscs gave reactions identical to the corresponding locally prepared discs. Methicillin Neo-sensitabs detected all MRSA strains but also included a few susceptible strains among the resistant ones. Addition of blood increased the number of not-detected MRSA strains. All 17 MRSA strains were susceptible to dicloxacillin by the dilution method, and the disc diffusion test showed similar results. Dicloxacillin discs therefore did not detect the presence of MRSA strains. The implications of replacement of the methicillin/oxacillin disc by a dicloxacillin disc are discussed.

Denmark↗

PubMed1988

Colonization priority among Staphylococcus aureus strains--correlation with phage-type.

We have studied the distribution of phage-type patterns among strains of Staphylococcus aureus isolated from patients in a burns unit. From 51 patients the same phage-type was isolated from succeeding swabs during the observation period. In 20 patients new types were introduced, but the original strain remained. In 23 patients the first strain was replaced by one other strain, in eight patients two or more. Strains of type 95 seemed to have a high colonization priority, whereas strains of group III had a low one. In 1986 phage-typing was performed on two or more S. aureus strains from the same patient, in 4561 instances. Recurrence of strains of the same phage-type pattern was demonstrated in 70% of the patients when the first and the fourth sample were compared. The "newer epidemic" strains of phage-type 95 and of the 94,96 complex had the highest percentage of recurrence (more than 80%) when adjacent samples were compared, and 68-69% when the first and the fourth sample were compared. The good colonization capacity of these strains might be one of the explanations why they occur frequently today although they are resistant only to penicillin.

Bacteriophage Typing↗

PubMed1988

Changes in the epidemiological pattern of Mycoplasma pneumoniae infections in Denmark. A 30 years survey.

A seroepidemiological survey has shown a remarkable shift in the previously reported regular cyclic pattern of Mycoplasma pneumoniae epidemics which culminated every 4.5 years during the period 1958-74. The last of four regular epidemics occurred in 1972. It was followed by 'premature' epidemics in 1975 and 1977/8 which inaugurated a change from an epidemic to an endemic pattern of the infection in Denmark. Over the following 9 years (1978-86) there has been an irregular but significant decrease in the annual number of seropositive samples with the usual high incidence during winter seasons. This endemic period terminated in the fourth trimester of 1987 with the development of a new epidemic. The hypothesis is advanced that a sixfold increase of children in day care may have influenced the change from an epidemic to an endemic situation which after 9 years led to a new epidemic of M. pneumoniae infection.

Agglutination Tests↗

PubMed1988

In-vitro activity and beta-lactamase stability of methicillin, isoxazolyl penicillins and cephalothin against coagulase-negative staphylococci.

Forty-nine clinical strains of coagulase-negative staphylococci were investigated for susceptibility to methicillin, oxacillin, cloxacillin, dicloxacillin, flucloxacillin and cephalothin. The highest level of resistance was found to methicillin and the lowest to cephalothin. The resistance-level of the isoxazolyl penicillins showed a high degree of uniformity. However more strains were resistant to cloxacillin and oxacillin than to dicloxacillin and flucloxacillin. Only a weak correlation was found between beta-lactamase production, and resistance to the six antibiotics. Methicillin was the most stable. The inactivation of cephalothin differed from that of the other antibiotics.

Cephalothin↗

PubMed1988

Comparative analysis of two blood culture systems (Isolator and a 12-tube system) by cumulative differences in detection power at different times during incubation.

A lysis-centrifugation blood culture system (Isolator) and a conventional system (4 tubes of nutrient broth, 4 tubes of semisolid agar, and 4 tubes of thioglycollate agar) were compared after different lengths of incubation by cumulative scoring of differences in detection power. After the first half day of incubation, the Isolator system was already significantly faster in detecting isolates of clinical significance (15 vs. 4, P = 0.02). Maximum difference in first or only detection system was seen after two days of incubation and was based on an overall superior detection of Staphylococcus aureus (11 vs. 0, P = 0.001), and an earlier detection of Enterobacteriaceae (30 vs. 13, P = 0.01) in the Isolator system. On the contrary, the detection of Streptococcus pneumoniae was significantly inferior in the Isolator system (0 vs. 10, P = 0.002). The earlier finding of clinically significant microorganisms in the Isolator system certainly contributes to good patient-care. A drawback of the Isolator system was the finding of clinically insignificant coagulase-negative staphylococci in 11%, compared with 1% in the conventional system. This led to a considerable waste of time and materials in the laboratory. The comparison of the two blood culture systems, based on statistical analysis of cumulative differences in detection power, expressed as the earliest or only findings, gives the optimal information, and is in our opinion the clinically most relevant comparison.

Bacteria↗

PubMed1988

Scintimetric assessment of synovitis activity during treatment with disease modifying antirheumatic drugs.

In a double blind trial of 36 patients with rheumatoid arthritis a new scintimetric method was applied to three comparable patient groups before and after eight months' treatment with levamisole, penicillamine, or azathioprine. Technetium-99m pyrophosphate scintigraphy of both hands was performed on a gammacamera with a computer attached, immediately after the administration of the tracer. The uptake ratio of each proximal interphalangeal (PIP) joint and the mid-half of the adjacent proximal phalanx was calculated from the activity counted for one minute. A scintimetric index was expressed as the sum of eight uptake ratios. This index was higher for each of the three patient groups before start of treatment than that for 10 age matched controls. After eight months of treatment the index, the number of PIP joints with clinical signs of synovitis, and the total circumference of the PIP joints decreased in the penicillamine and azathioprine groups. The scintimetric method reliably reflected local synovitis activity and its changes but, like grip strength and PIP circumference, was not a representative measure of the overall activity of the disease.

Adult↗