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Biomedical subjects

M W Bentzon

Publications and source records attributed to M W Bentzon.

At least 73 records · Page 4Linked to original sources
PubMed1986

A new method for exact measurements of visual acuity. Determination of threshold curves for the resolving power of the eye by computerized curve fitting.

The paper presents a new test method for investigations of threshold curves for the resolving power of the eye and for exact measurements of visual acuity. This method measures static visual acuity within confidence limits of 9% compared to the acuity steps in Snellen notation of 33% to 50%. Furthermore, the method introduces the slope of the threshold curve as a parameter of suggested importance in the judgement of visual capability. The test mathematic is based on a method described by Finney (1952) for calculations on dose-response curves. To calculate the results and the test statistics an iterative curve fitting programme was designed to be run on a micro-computer. By connecting the presentation system and the response panel to the same computer the test could be performed almost automatically. The new test method was used to study visual acuity measured by projected ortotypes compared to acuity when measured by printed ortotypes. Tests using projected ortotypes were found to equal traditional acuity measurements, but the test results stressed the need for perfect and adjusted optics when projecting systems are used in visual acuity test.

Computers↗
PubMed1986

The susceptibility of Plasmodium falciparum to sulfadoxine and pyrimethamine: correlation of in vivo and in vitro results.

In 1982, 2 of 14 Plasmodium falciparum infections acquired in East Africa and diagnosed in Copenhagen were resistant to treatment with sulfadoxine plus pyrimethamine (Fansidar), while in 1983, 6 of 18 were so. The in vivo tests were supplemented by determinations of drug concentrations in serum, and 4 isolates from in vivo-sensitive cases and 6 from in vivo-resistant cases were selected for in vivo tests. These were performed in ordinary RPMI 1640 medium and in a medium with physiological p-aminobenzoic acid and folic acid concentrations. Pharmacokinetic aberrations were found to be of possible importance in only 2 of the in vivo-resistant cases. In vitro susceptibility to sulfadoxine was found to be uniformly low in all isolates. Testing with a combination of sulfadoxine and pyrimethamine in the medium with physiological concentrations of cofactors probably reflects the in vivo situation most accurately, but in all but 1 of the isolates studied in vitro the in vivo susceptibility to Fansidar would be predicted by in vitro susceptibility to pyrimethamine in either medium. The concentration of p-aminobenzoic acid in serum, quantitated by high performance liquid chromatography, was found to be subject to wide variation, and this may have implications for in vitro testing.

Adult↗
PubMed1985

Imipenem/cilastatin treatment of multiresistant Pseudomonas aeruginosa lung infection in cystic fibrosis.

Ten patients with cystic fibrosis and chronic broncho-pulmonary Pseudomonas aeruginosa infection received 45 mg imipenem/cilastatin per kg body weight/day, intravenously for two weeks. The treatment was safe with only minor side effects and clinical parameters improved considerably during therapy. In all patients resistance of Ps. aeruginosa to imipenem developed in the second week of treatment; in seven patients the therapy selected for a resistant strain and in three resistance developed in the original strain. The resistance persisted after cessation of treatment and thus the clinical usefulness of imipenem/cilastatin as monotherapy in CF-patients with Ps. aeruginosa seems to be limited.

Adolescent↗
PubMed1984

Antigen specific in vitro activity of lymphocyte subpopulations from Mantoux positive and negative subjects assessed by lymphocyte proliferation assay.

A micromethod for the lymphocyte proliferative assay and multifactorial analysis of stimulation indices classified according to subjects, lymphocyte combinations and antigens was used to elucidate deficient Mantoux (Mx) reactions in BCG-vaccinated subjects. It was possible to group each of the factors so that interactions between the two latter factors were not present within but only between groups. Comparisons between the subject groups showed a clear association between results of this in vitro test with PPD antigen and the Mx test carried out with 1 TU. The in vitro test had the advantage of being more sensitive and of not introducing the immune reactions occasionally seen with the Mx test. Thymus-processed lymphocytes were the cells responsible with functions both as effector and regulator cells, B lymphocytes had only regulatory properties.

Analysis of Variance↗
PubMed1984

In vivo and in vitro boosting effects of tuberculin skin tests in guinea-pigs immunized with living BCG or with killed Mycobacterium tuberculosis.

Eight weeks after the onset of immunization with living BCG vaccine or with heat-killed, dried Mycobacterium tuberculosis in paraffin oil (TB), guinea-pigs were skin tested with small doses of tuberculin PPD. Three weeks later the effect of these tests on skin reactions and on lymphocyte transformation (LT) responses of lymph node lymphocytes (LNL) or peripheral blood lymphocytes (PBL) was estimated by a comparison with non-tested groups. For both immunogens, the skin test after 8 weeks significantly enhanced skin reactions, particularly to low tuberculin doses. In the BCG-vaccinated guinea-pigs the LT responses of both cell types were significantly enhanced by the skin test after 8 weeks, whereas the LT responses from the TB-immunized guinea-pigs were not affected. Therefore, in the planning and interpretation of in vitro tests of cellular immunity, possible effects from previously applied skin tests should be taken into consideration.

Animals↗
PubMed1984

Studies on the development of tuberculin sensitivity in immunized guinea pigs with demonstration of a close relationship between results of skin tests and the lymphocyte transformation technique.

The development of tuberculin sensitivity in groups of guinea pigs immunized with living BCG vaccine or with heat-killed Mycobacterium tuberculosis suspended in oil (TB) was measured by skin tests and lymphocyte transformation (LT) tests with tuberculin PPD. LT tests on lymphocytes from peripheral blood (PBL) and lymph nodes (LNL) and skin tests were carried out on different groups of guinea pigs for 1 year following immunization. Three ways of expressing the LT results were considered, i.e. as stimulation index, delta cpm and uncorrected cpm values. Since neither of the first two methods were equally applicable to all of the data, we decided to express the data as geometric means of cpm values for stimulated and control cultures, respectively. For both immunogens the sensitivity measured by PBL LT and skin tests showed a closely parallel development; LNL reactivity appeared earlier and remained at a higher level than PBL reactivity. Antibody levels in the guinea pigs were measured using a radioimmunoassay technique, were found to be dependent on the immunization period and not correlated to the cellular immunity.

Animals↗
PubMed1984

A prospective study of lung disease caused by Mycobacterium avium/Mycobacterium intracellulare.

This is a prospective study of 36 patients with lung infections caused by M. avium/M. intracellulare. The division of the patients into 2 prognostic groups ("good"/"others"), and the guidelines for their treatment are based on a previous report (3). The criteria for the division were co-existing lung disease and dyspnoea on admittance. The patients in group "good" were treated with isoniazid, rifampicin and ethambutol, in group "others" these were supplemented with one or more drugs. As in the previous study (3), the prognosis was far better for group "good" than for group "others". The patients in group "good" should be treated with isoniazid, rifampicin and ethambutol, unless the course of disease is unsatisfactory. The mortality was high in group "others" and half of the deaths were related to mycobacteriosis. Some patients became culture negative and others showed decreasing numbers of bacteria, but the value of the supplementary drugs could not be proven.

Adult↗
PubMed1983

Effect of 2-mercaptoethanol and mycostatin on guinea pig lymphocyte transformation: interpretation of results depends on the method of calculation.

The stimulating effects of 2-mercaptoethanol (2-ME) reported in murine cell cultures were confirmed for guinea pig lymphocyte transformation (LT). 2-ME was mitogenic for peripheral blood lymphocytes (PBL) and lymph node lymphocytes (LNL) and enhanced PPD-induced LT. The effect on LNL was dependent on the magnitude of the response of non-2-ME treated cultures. The 2-ME effect on PPD-stimulated LNL was reversed when stimulation index (SI) replaced the delta cpm estimate. Mycostatin (MYC) inhibited the blastogenic response of PBL control cultures, whereas its effect on LNL control cultures varied. The interpretation of the effect of MYC on PPD-stimulated cultures was dependent on the use of the delta cpm or SI estimates. The interpretation of LT experiments is therefore highly dependent on whether delta cpm or SI is used for expression of results. Analysis of effects on control and stimulated cultures should precede the addition of 2-ME or MYC to cultures for LT.

Animals↗
PubMed1983

Kinetics and dose calculations of ampicillin and gentamicin given as continuous intravenous infusion during parenteral nutrition in 88 newborn infants.

Ampicillin and gentamicin were administered continuously intravenously to 88 newborn infants using individually calculated dosages. For infants with a mean value of plasma clearance of the antibiotics, it was calculated that the serum ampicillin and gentamicin concentrations would be between 35-55 and 3-5 micrograms/ml, respectively, using the dosages for intermittent treatment. These dosages are therefore recommended as fixed dosages for continuous intravenous infusion initiated by a bolus dosage. Serum gentamicin concentration should be assayed about three half-lives after start of infusion and the dosage adjusted for values outside 3-5 micrograms/ml.

Ampicillin↗
PubMed1983

Frequency, phage types and antibiotic resistance of Staphylococcus aureus isolated from blood cultures in Denmark 1975-1981.

In the period 1975-1981, 4060 cases of Staphylococcus aureus bacteremia were recorded in Denmark, and the corresponding strains were examined. The percentage of strains, resistant to penicillin only, rose to 82, and the percentage of multiply-resistant strains fell to five. Newer phage types (94, 96 and 95) increased from 10% to 27% of the material. These strains were usually resistant only to penicillin, but produced large amounts of penicillinase. The ample penicillinase production has also been characteristic for previous epidemic strains, and it is furthermore correlated to mortality. The overall mortality of 34.6% was lower than that of the preceding period. Mortality rates were highest in elderly patients, nosocomial cases, patients with serious primary diseases and endocarditis cases.

Adult↗
PubMed1982

A study of bacteremias in Denmark from 1977-1978.

The results of blood cultures from a large number of Danish hospitals examined at Statens Seruminstitut in 1977 and 1978 have been analysed. Out of a total of 17, 518 cultures in 1977 and 17,820 in 1978, 1,626 from 830 patients and 1,544 from 832 patients yielded growth of pathogenic microorganisms. Cases of bacteremia with Enterobacteriaceae constituted approximately 50% of cases both in 1977 and 1978. Polymicrobial bacteremia occurred in 8.1% of bacteremic cases in 1977 and 7.5% of those in 1978. The microorganisms isolated and their frequencies were surprisingly similar to those found in 1965 and 1971 in an earlier investigation from this department. No change in antibiotic susceptibility was observed between 1977 and 1978. Retesting of 50 E. coli strains from 1965, 1971 and 1978 for susceptibility towards ampicillin, cephalotin, streptomycin and tetracycline indicated that no significant changes had occurred, contrary to the results of the earlier investigation. This fact stresses the importance of exploring the possibility of unnoticed methodological changes having occurred in the sensitivity testing systems before any conclusions can be drawn concerning apparent differences in antibiotic susceptibilities.

Adolescent↗
PubMed1982

Predicting recurrence in patients with breast cancer from cumulative laboratory results: a new technique for the application of time series analysis.

We followed the cases of 26 consecutive postmenopausal patients operated on for primary breast cancer. Serum specimens were obtained each month for 1.5 years and stored at -80 degrees C until assayed for carcinoembryonic antigen (CEA) and other quantities. Ten patients developed recurrence, while 16 qualified as controls (no clinical recurrence for at least 1.7 years after the last venipuncture). Using the homeostatic autoregressive time series model, modified by us to be particularly sensitive to sustained deviations from the mean, we detected four recurrences by CEA without having any falsely positive alarms. Group-based reference limits and application of the unmodified homeostatic model were less effective (fewer detected and shorter lead time). Simulation studies, involving use of a mathematical model relating CEA concentration to tumor growth and using parameters estimated from patient data, verified this and indicated that at least five stable baseline values are needed to detect 100% of recurrences before they are detected by the group-based limit.

Aged↗