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J Petersen

Publications and source records attributed to J Petersen.

At least 145 records · Page 8Linked to original sources
PubMed1993

[Erroneous vision determination and quantitative effects].

UNLABELLED: The experimentally determined psychometric function for Landolt rings (8 orientations, 183 eyes) is used to calculate the statistics of visual acuity results according to DIN 58,220 and their bias due to deviations from DIN 58,220. Test procedure fulfilling DIN 58,220, criterion 3/5: With a second test the first result is reproduced in 33.7%. In 47% the difference is 1 step, in 16.2% 2 steps, and in 2.8% 3 steps. Selecting the highest acuity value out of several tests yields a bias of +0.44 steps (2 tests), +0.66 steps (3), +0.81 steps (4 tests). Deviations from DIN 58,220, criterion 3/5: Linearly instead of log-scaled optotypes: above acuity 0.2 the effect is minimal (< 0.1 steps). For acuity 0.1 the bias is -0.9 steps. Old criterion 3/4: bias -0.55 steps; Repetition of a failed optotype: bias +1.11; Repetition of a failed acuity step: +0.61; Continued test despite fulfilled break condition: bias +0.3 steps; Weakened criterion of 2/5: bias +0.89 steps. CONCLUSIONS: Visual acuity values can contain considerable errors. There is a need for more effective algorithms and an unbiased investigator. The solution is programmed automatic testing on a computer screen.

Algorithms↗
PubMed1992

Capillary electrophoretic determination of the protease Savinase in cultivation broth.

The highly basic washing enzyme Savinase and various analogues were analysed by micellar electrokinetic chromatography (MEKC) and electrophoresis. Broth samples were withdrawn during the cultivation of Savinase by recombinant microorganisms. Savinase peak areas obtained by MEKC-electrophoretic analysis were normalized with respect to migration time and compared with traditional enzyme activity measurements. The electropherograms indicated thermal degradation of the Savinase molecule at high field strengths. Baseline separation of Savinase and two analogues was achieved.

Bacillus↗
PubMed1992

[Pregnant women's knowledge about HIV and AIDS].

This investigation is based upon information from 820 pregnant women who replied to a questionnaire about AIDS during the period 17.4.1989-14.7.1989. The questions included sources of information, knowledge about routes of infection and risk groups and the extent of spread of infection and disease in the population. 95% agreed to participate. Knowledge had been obtained primarily via the electronic media, while the health services had limited significance. The employment of sources of information depended on age and occupation. Apart from knowledge about the risk involved in breast feeding, the women were, in general, well informed about routes of infection. Knowledge about risk groups and the current extent of spread of infection was, on the the other hand, deficient. Defective knowledge was concentrated in groups which may be characterized by age (less than 24 years) and occupation (trained and untrained workers and the group of "other occupations"). Information obtained from health staff was connected with better knowledge about the extent of spread of infection. The majority of women desired routine information about AIDS in connection with antenatal control. Prophylactic measures should be based, among other things, on knowledge about development in the knowledge in the population and its employment of sources of information, so that specific information may be directed to certain groups of the population by using the most frequently employed and most effective routes of information. The knowledge of population groups, the attitudes and behaviour should be followed continuously.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Glutamic acid decarboxylase (GAD) autoantibodies are additional predictive markers of type 1 (insulin-dependent) diabetes mellitus in high risk individuals.

The prevalence of glutamic acid decarboxylase autoantibodies was determined with an immunotrapping enzyme activity assay in newly-diagnosed Type 1 (insulin-dependent) diabetic patients as well as in first-degree relatives using rat brain homogenate as a source of glutamate decarboxylase. Twenty-six out of 86 islet-cell cytoplasmic auto-antibody positive and one out of 24 islet cell autoantibody negative patients of recent onset, had autoantibodies to glutamate decarboxylase above the upper 99% confidence limit obtained from 89 control sera. Among 27 islet cell autoantibody positive relatives including 19 siblings and 8 parents, antibodies to glutamate decarboxylase were found in 8 of 9 (89%) relatives and 7 of 8 (87.5%) siblings with islet cell auto-antibody titres above 20 JDF units, in 1 of 19 (5.2%) relatives with islet cell autoantibody titres between 2 and 5 JDF units, in 2 of 263 (0.7%) siblings and 1 of 139 parents without islet cell autoantibodies. In first-degree relatives, high titre islet cell autoantibodies and autoantibodies to glutamate decarboxylase were tightly associated (X2 = 182, p = 0.0001). None of the relatives with low genetic risk (n = 64), i.e. HLA-different to the diabetic proband, was found to be antibody positive. Antibodies to glutamate decarboxylase were present only in those relatives sharing at least one haplotype with the diabetic proband, including two islet cell autoantibody negative but HLA-identical siblings. Autoantibodies to glutamate decarboxylase were present in 7 of 9 (77%) relatives who developed the disease, including one islet cell autoantibody negative sibling.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Direct and correlated responses to bidirectional selection for dustbathing activity in Japanese quail (Coturnix coturnix japonica).

Bidirectional selection was conducted for dustbathing activity in male Japanese quail over 17 generations. The response to selection was slightly asymmetrical, due mainly to scale effects and a threshold imposing discontinuity on the visible expression of dustbathing in the low line. Correlated responses to selection were found for latency to dustbathe, duration, intensity, and incidence of nonbathers. In general, changes followed linear patterns over time in both lines with the exception of quadratic change in nonbathers in the high line. Under artificial environment, only minor natural selection pressure is assumed to act on the expression of dustbathing behavior.

Animals↗
PubMed1992

Variability among methods to assess patients' well-being and consequent effect on a cost-effectiveness analysis.

Cost-effectiveness analysis is emerging as an approach for determining the relative value of health care programs, technologic innovations, and clinical decisions. Increasingly, patients' stated values for quality of life are applied as adjustment in these analyses; the results may vary depending on how individuals assess their well-being. We interviewed 58 patients with chronic renal failure to determine the level of agreement among six methods for assessing well-being, and to determine the effects of variation in assessed well-being on the results of a cost-effectiveness analysis of in-center hemodialysis. Patients reported well-being using the Sickness Impact Profile, Campbell Index of Well-being, Kaplan-Bush Index of Well-being, categorical scaling, standard gamble, and time trade-off. We found that patient well-being was substantially higher as evaluated by the Sickness Impact Profile compared to the other five methods. The Sickness Impact Profile and the Kaplan-Bush Index of Well-being provided much narrower distributions of assessed values relative to other measures. Correlations among assessment methods were poor (Spearman rank-correlation coefficients range: 0.094-0.519). Discrepancies among indices were particularly vivid when we evaluated data at the individual level; many patients reported a high level of well-being according to one index and a low level of well-being according to a different index. The cost effectiveness of in-center hemodialysis varied from $34,893 to $45,254 per quality-adjusted life-year saved according to the Sickness Impact Profile and standard-gamble technique respectively. The substantial variability in patients' stated quality of life may preclude the use of a single method to analyze the cost effectiveness of a health program.

Cost-Benefit Analysis↗
PubMed1992

An in vivo analysis of reverse ultrafiltration during high-flux and high-efficiency dialysis.

We have developed an in vivo pressure monitoring system to study the phenomenon of reverse ultrafiltration of dialysate during high-flux and high-efficiency dialysis. Under the usual operating conditions of either type of dialysis, driving pressures existed for reverse ultrafiltration of dialysate into the venous end of the blood compartment. Whether or not reverse ultrafiltration could be abolished at higher ultrafiltration rates was dialyzer-dependent, being least with high-efficiency dialysis. In addition, the degree of reverse ultrafiltration was affected by patients hematocrit, dialyzer inlet and outlet oncotic pressures, and the rate and direction of dialysate flow.

Equipment Design↗
PubMed1992

A model of the volumetrically-controlled hemodialysis circuit.

We developed a model that predicts the hemodynamics of the volumetrically-controlled circuit used to administer high flux hemodialysis. The equations simulate the entire blood side of the circuit so that blood and dialysate pressures can be predicted from a knowledge of circuit component and patient characteristics. An alternative method of computation has also been devised which permits measured circuit pressures to be used to predict patient blood access pressure, dialyzer resistance to flow and membrane hydraulic conductivity. Success of the model was evaluated by measuring both circuit pressure and component characteristics. The model successfully predicted circuit pressures when measured component characteristics were employed as model inputs. Conversely, the model accurately predicted circuit component characteristics when measured pressures were employed as inputs (8 patients, 30 dialyses). Specific predictions of the model include the following. Elevations of patient blood access pressure will cause blood and dialysate pressures to rise equivalently without affecting the rate of back-filtration or location of pressure equilibrium along the dialyzer axis. Elevated hematocrit is predicted to increase circuit pressures to a degree that is similar to a poorly functioning blood access, however, high hematocrit markedly augments back-filtration and moves the point of pressure equilibrium toward the dialyzer entrance. We conclude that the model provides a predictive tool that can be used to optimize circuit design. Alternatively, the model can be used to separate the influence of a poorly functioning patient access from other factors which can elevate circuit pressures.

Blood Flow Velocity↗
PubMed1992

A multivariate analysis of mortality and hospital admissions with high-flux dialysis.

The use of high-flux dialysis in clinical practice increased rapidly despite an absence of reports on the clinical effectiveness of the technique. Mortality and hospital admission rates of patients treated with high-flux dialysis were evaluated and compared with those of patients treated with conventional dialysis in a hospital-based renal dialysis unit in northern California. By use of a retrospective, cross-over design, 253 patients enrolled in the dialysis unit from January 1987 to January 1991 were studied. During this period, 107 patients were treated with high-flux dialysis for at least 1 month, and all but 17 of them had received conventional dialysis before switching to high-flux dialysis. The remaining 146 patients were treated with only conventional dialysis. Of the 80 patients who died during the study period, 69 were receiving conventional dialysis and 11 were receiving high-flux dialysis. The multivariate analyses, adjusted for age, gender, ethnic background, type of renal failure, comorbid conditions, and duration of ESRD, showed that annual mortality was substantially less for patients treated with high-flux dialysis compared with that for patients treated with conventional dialysis (7 versus 20%; P < 0.001). The difference in the rate of hospital admissions was not statistically significant. In this nonexperimental study, methods were applied to control for selectivity bias and other factors that might confound the apparent treatment effect. The findings suggest that the potential benefits of high-flux dialysis are sufficient to justify further confirmation in a randomized, controlled trial.

Adult↗
PubMed1992

[The significance of the weaning age of young rabbits for the development of young animals and their food consumption].

The experiment reported compared the influence of weaning at 25, 28, 31 and 35 days of age on the development of liveweight and food consumption during the pre- and post-weaning period hybrid rabbits. Results of 44 does and 949 offspring showed that late weaning exerted a positive influence on live-weight development in comparison with already weaned kits of the same age. In all weaning age groups a depression in growth occurred shortly after weaning which was compensated thereafter. There was no significant difference between treatments with regard to total food consumption of does and offspring. This lack of difference was due to the high food intake of lactating does after weaning that surpassed maintenance requirements.

Age Factors↗
PubMed1992

Effect of methylxanthine derivatives on T cell activation.

In a Phase I-II trial examining the effect of prophylactic administration of pentoxifylline (PTX) on bone marrow transplant-associated morbidity, there was an apparent reduction in the incidence and severity of acute graft-versus-host disease. To determine if PTX might be directly immunosuppressive, its effects on T cell activation and proliferation were examined. PTX and several cogeners were found to directly suppress T cell proliferation in response to phytohemagglutinin, to allogeneic cells in a mixed leukocyte reaction, and to cross-linking the CD3 complex. The effects were dose-related and associated with suppression of secretion of tumor necrosis factor-alpha (TNF alpha). However, the inhibition of proliferation was not solely due to this effect since adding excess recombinant TNF alpha did not restore the proliferative response. These data suggest that PTX may be clinically useful in suppressing allogeneic reactions in bone marrow transplantation.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1992

Erythropoietin therapy in patients with chronic renal failure.

Symptomatic anemia is a common complication of chronic renal failure. Treatment is now possible with the availability of recombinant human erythropoietin (epoetin alfa). Previous experimental studies have suggested that correcting the anemia of chronic renal failure may be harmful in that renal failure may be accelerated. Although experience with this drug has been primarily restricted to its use in patients with end-stage renal disease, several recent trials have been reported in patients with varying degrees of chronic renal failure. We review these studies with particular reference to the progression of renal failure and the drug's reported side effects. We conclude that the use of epoetin is beneficial and well tolerated and that there is no compelling evidence for the acceleration of renal failure associated with its use in patients.

Anemia↗
PubMed1991

[Clinical trial of an ergometry bicycle with automatic blood pressure registration].

Automatic blood-pressure registration on a computerized ergometer cycle was compared with simultaneous manually registered blood-pressure employing a standard mercury sphygmomanometer during performance of maximal ergometer exercise testing on 50 consecutive patients. The difference in blood-pressure registered by the automatic and the manual methods, respectively, was, on an average +0.2 mmHg with a 95% confidence interval of +/- 20 mmHg. By means of linear regression analysis, a correlation coefficient of 0.97 (p less than 0.001) with an uncertainty of approximately 6% with automatic blood-pressure registration was found. Simultaneously, the uncertainty was independent of the degree of work performed. The apparatus was found to be of practical clinical use.

Adult↗