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Biomedical subjects

B Bengtsson

Publications and source records attributed to B Bengtsson.

At least 55 records · Page 3Linked to original sources
PubMed1997

Pharmacokinetics of penicillin-G in ewes and cows in late pregnancy and in early lactation.

Concentrations of penicillin-G in serum were determined after single intravenous doses of potassium penicillin-G (10 mg/kg body wt) to ewes and cows in late pregnancy and in early lactation. Penicillin-G in serum was analysed by a microbiological method and pharmacokinetic parameters were calculated by model-independent methods. Serum concentrations were lower in early lactation than in late pregnancy in both ewes and cows. The differences were statistically significant at most sampling times in ewes but only during the first hour in cows. Weight corrected values of clearance and volume of distribution were significantly higher in early lactation than in late pregnancy in both ewes and cows. Mean residence time and elimination-half life were shorter in lactating than in pregnant ewes, however for the latter parameter the difference was not statistically significant. Neither of these parameters changed in cows. It is concluded that in both ewes and cows pharmacokinetic parameters of penicillin-G are altered from late pregnancy to early lactation but that these changes have little practical impact and do not call for a revised dosage regime of the studied drug.

Animals↗
PubMed1997

An improved method to estimate frequency of false positive answers in computerized perimetry.

Reliability of patient performance in static computerized perimetry is important for evaluation of results. False positive answers tend to falsely increase measured threshold sensitivity. The frequency of false positive responses is traditionally measured by adding extra questions, catch trials, to the test. Catch trials are few and limited because of time constraints, leading to inexact estimates. We developed an improved method for estimation of false positive answers by using information already available in current ordinary computerized visual field testing, without increasing test time. We here describe the method and evaluate it in a prospectively collected material of 49 glaucoma eyes of 49 patients. The results show that the new method reduces measurement errors considerably and significantly as compared with the traditional catch trials method. Test-retest change was only half with the new method as compared to the traditional method of catch trials. Furthermore, it can reduce test time by eliminating the need to use catch trials to estimate the frequency of false positive responses.

Adult↗
PubMed1997

Perimetric probability maps to separate change caused by glaucoma from that caused by cataract.

We describe a new method for analysis of change in glaucomatous visual fields with the object to differentiate between changes caused by glaucoma from those caused by cataract. New pattern deviation change probability maps were developed from a prospectively collected glaucoma material and designed to be sensitive to changes in localized field loss, but to be unaffected by media-induced perimetric change. We compared the new change probability maps with the commercially available total deviation change probability maps in series of Humphrey perimetric tests in a glaucoma material of 43 eyes of 35 patients, who had undergone cataract surgery. When using the total deviation maps, considerable differences were seen between fields obtained before and after cataract surgery. Much smaller differences were seen when using the new change probability maps, that almost eliminated the common and disturbing effect of increasing cataract. This new tool could be of considerable help in differentiation between progressive glaucomatous visual field loss and deterioration caused by increasing media opacities.

Aged↗
PubMed1997

A new generation of algorithms for computerized threshold perimetry, SITA.

PURPOSE: The purpose of this work was to develop a new family of test algorithms for computerized static threshold perimetry which significantly reduces test time without any reduction of data quality. METHODS: A comprehensive visual field model constructed from available knowledge of normal and glaucomatous visual fields is continuously updated during testing. The model produces threshold estimates and also estimates of the certainty to which the threshold is known at each point. Testing is interrupted at each test location at predetermined levels of threshold certainty. New time-saving methods are employed for estimation of false answers, and test pacing is optimized. After completion of the test, all threshold estimates are re-computed, taking into account the complete body of patient responses. Computer simulations were used to optimize the different parameters of the new algorithms, to evaluate the relative importance of those parameters, and to evaluate the performance of the algorithm as a whole in comparison with a standard algorithm. RESULTS: Simulated test results obtained with this algorithm were slightly more accurate than those of the Humphrey Full Threshold test algorithm. The number of simulated stimuli presented was reduced by an average of 29% in normal fields and 26% in glaucomatous fields. Actual clinical test time should be further reduced, since the influence of the improved timing algorithm was not included in the simulations. CONCLUSIONS: We applied new methods which take available knowledge of visual field physiology and pathophysiology into account, and employ modern computer-intensive mathematical methods for real time estimates of threshold values and threshold error estimates. In this way it was possible to design a family of testing algorithms which significantly reduced perimetric test time without any loss of quality in results.

Algorithms↗
PubMed1997

The genetics of primary nocturnal enuresis: inheritance and suggestion of a second major gene on chromosome 12q.

Primary nocturnal enuresis (PNE), or bedwetting at night, affects approximately 10% of 6 year old children. Genetic components contribute to the pathogenesis and recently one locus was assigned to chromosome 13q. We evaluated the genetic factors and the pattern of inheritance for PNE in 392 families. Dominant transmission was observed in 43% and an apparent recessive mode of inheritance was observed in 9% of the families. Among the 392 probands the ratio of males to females was 3:1 indicating sex linked or sex influenced factors. Linkage to candidate regions was tested in 16 larger families segregating for autosomal dominant PNE. A gene for PNE was excluded from chromosome 13q in 11 families, whereas linkage to the interval D13S263-D13S291 was suggested (Zmax = 2.1) in three families. Further linkage analyses excluded about 1/3 of the genome at a 10 cM resolution except the region around D12S80 on chromosome 12q that showed a positive two point lod score in six of the families (Zmax = 4.2). This locus remains suggestive because the material was not sufficiently large to give evidence for heterogeneity. Our pedigree analysis indicates that major genes are involved in a large proportion of PNE families and the linkage results suggest that such a gene is located on chromosome 12q.

Child↗
PubMed1997

Out-patient rehabilitation improves activities of daily living, quality of life and exercise tolerance in chronic obstructive pulmonary disease.

The purpose of this study was to investigate the effects on activities of daily living, quality of life, and exercise tolerance of a comprehensive out-patient rehabilitation programme for patients with moderate-to-severe chronic obstructive pulmonary disease. In this randomized and controlled trial, the main outcome measures were Activities of Daily Living (ADL) score, York Quality of Life Questionnaire (YQLQ) score, Chronic Respiratory Disease Questionnaire (CRDQ) score, 6 min walking distance (6MWD), forced expiratory volume in one second (FEV1), and forced vital capacity (FVC). The rehabilitation programme included physical training, occupational therapy, education, and smoking cessation therapy, and lasted for 12 weeks. The patients were evaluated at entry, halfway through, and at the end of the programme. Follow-up was at 24 weeks. Forty seven patients were recruited, and 16 in each group completed the trial. There were significant differences in the improvements in ADL and CRDQ between the control and the treatment groups at 12 and 24 weeks, and at 24 weeks, respectively. At 6, 12 and 24 weeks, improvements in the 6MWD were 21.6 versus 79.8, 36.1 versus 113.1 and 21.4 versus 96.2 for control and treatment groups, respectively (p<0.004). A correlation matrix showed only ADL and 6MWD to be significantly correlated; the matrix was also used to validate the translated questionnaires. The programme required 124 staff-hours in total. An inexpensive, comprehensive out-patient rehabilitation programme can produce long-term improvement in activities of daily living, quality of life, and exercise tolerance in patients with moderate-to-severe chronic obstructive pulmonary disease.

Activities of Daily Living↗
PubMed1996

[Bacteremia in the county of Ribe].

The Department of Microbiology at the Central Hospital of Esbjerg, established in 1987, serves the five hospitals in Ribe county, Denmark. From early on, the department has endeavoured to guide the hospital's antimicrobial policy. In order to investigate whether this involvement had any measurable impact on the antimicrobial resistance pattern in our region, we compared the resistance patterns of 212 strains isolated from the blood of bacteraemic patients in 1988 to those of 317 strains isolated in 1992. No increase in antibiotic resistance was revealed. This is noteworthy since new specialties have been established at the Central Hospital during this period, with an increased number of patients requiring antimicrobial therapy. It is important to survey the antibiotic resistance pattern closely, and that this is done locally.

Anti-Bacterial Agents↗
PubMed1996

The effect of perimetric experience in patients with glaucoma.

OBJECTIVE: To study prospectively the effects of perimetric learning in glaucoma patients. PATIENTS AND METHODS: Twenty-five patients with newly detected glaucoma underwent repeated perimetric testing using the 30-2 full threshold program with the Humphrey perimeter. Each patient was tested five times at about 1-week intervals. No patient had undergone perimetry before entering the study. RESULTS: In most patients, visual field results improved with repeated testing. Improvements were obvious in 21 of the 37 glaucomatous eyes. Means of mean deviation values improved significantly, by 2.81 dB (P < .001, analysis of variance), between the first and the second test session, and no significant differences were shown between tests 2 and 5. Fields with moderate field loss improved more than fields with milder or more severe loss. Learning effects were more pronounced peripherally than centrally, and better points improved more than more disturbed ones. CONCLUSIONS: The effects of perimetric learning were large and common, and are clinically important. Baselines for perimetric follow-up of patients with glaucoma should consist of more than one test. To avoid misleading conclusions, studies using perimetry to assess the effects of glaucoma treatment should take learning effects into consideration.

Adult↗
PubMed1996

Sensitivity and specificity of structural optic disc parameters in chronic glaucoma.

We studied different structural optic disc parameters and their ability to discriminate between normal and glaucoma eyes using computerized raster tomography. Two hundred and seventy-six eyes of 138 normal subjects and 146 eyes of 102 glaucoma patients were examined with a raster tomographic imaging system (The Glaucoma-ScopeTM, Ophthalmic Imaging Systems, Sacramento, CA). Glaucoma eyes were classified into four groups according to their perimetric mean deviation values. Minimum rim width within the 60 degrees and 90 degrees sectors across the vertical meridian, vertical and horizontal cup-disc ratio, rim and cup area were calculated for each optic disc. Receiver operating characteristics curves were set up for comparisons of the different parameters. Representing localised changes of the optic disc, minimum rim width 60 degrees and 90 degrees showed the best separating characteristics with sensitivity values of 91% at a fixed specificity of 90%, followed by vertical cup-disc ratio. Global indices like cup and rim area and horizontal cup-disc ratio showed the poorest separation. These differences were particularly obvious in the group with mild to moderate glaucomatous visual field defects. Thus, global parameters were less likely to detect early focal glaucomatous optic nerve head changes, than parameters representing localised changes.

Aged↗
PubMed1995

Glycosylated peptide hormones: pharmacological properties and conformational studies of analogues of [1-desamino,8-D-arginine]vasopressin.

Two analogues of the antidiuretic drug [1-desamino,8-D-arginine]vasopressin (DDAVP), which have a glycosylated serine at position 4, have been prepared by Fmoc solid phase peptide synthesis. The glycosylated analogues had significantly higher bioavailabilities than the nonglycosylated [D-Tyr2,Ser4]DDAVP and DDAVP on intraintestinal administration in rat. The improved bioavailability resulted from an increased absorption from the small intestine and most likely from an increased stability toward enzymatic degradation, whereas plasma clearance was either unaffected or slightly increased by the glycosylation. The glycosylated analogues displayed only very low agonistic and antagonistic activities at the vasopressin V2-receptor. Conformational studies performed by 1H NMR spectroscopy did not reveal any major influence from glycosylation on the conformation of the peptide backbone. The lack of receptor binding displayed by the analogues is therefore most likely explained by steric repulsion between the carbohydrate moiety and the vasopressin receptor which prevents receptor binding.

Amino Acid Sequence↗
PubMed1994

Uptake and distribution of calcium and phosphorus in beech (Fagus sylvatica) as influenced by aluminum and nitrogen.

We studied the effects of excess nitrogen added as nitrate (NO(3) (-)) or ammonium (NH(4) (+)), or both, on mineral nutrition and growth of beech (Fagus sylvatica L.) plants grown at pH 4.2 in Al-free nutrient solution or in solutions containing 0.1 or 1.0 mM AlCl(3). A high external concentration of NH(4) (+) increased the concentration of nitrogen in roots, stems and leaves. The root/shoot dry weight ratio was less in plants grown in the presence of NH(4) (+) than in plants grown in the presence of NO(3) (-). The concentration of phosphorus in the roots was increased and the concentration of potassium in all parts of the plant was decreased by NH(4) (+). A high external concentration of NO(3) (-) caused a decrease in phosphorus concentrations of the root, stem and leaf. Uptake of (45)Ca(2+) by roots was reduced in the presence of high concentrations of NH(4) (+) or NO(3) (-), and a combination of high concentrations of nitrogen and aluminum further reduced the uptake of (45)Ca(2+). Uptake of phosphate ((32)P) and concentrations of phosphorus in root and shoot were increased when plants were grown in the presence of 0.1 mM Al. Exposure to 1.0 mM Al, however, reduced the concentration of phosphorus in roots and shoots and the reduction was greater when plants were grown in the presence of a high external NO(3) (-) concentration. Aluminum binds to roots, and plants grown in the presence of 1.0 mM Al had a slightly higher concentration of aluminum in roots than plants grown in the presence of 0.1 mM Al, whereas the concentration of Al in the shoot was increased 2 to 3 times in plants exposed to 1.0 mm Al. Furthermore, the effects of 1.0 mM Al on uptake of other macronutrients were quite different from the effects of 0.1 mM Al. We conclude that 0.1 mM Al facilitates uptake and transport of phosphorus in beech and that between 0.1 and 1.0 mM Al there is a dramatic change in the effects of Al on uptake and transport of divalent cations and phosphorus.

Journal Article↗
PubMed1993

[Septicemia caused by Malassezia furfur].

A case of septicaemia caused by Malassezia furfur in a newborn patient receiving intravenous nutrition is presented. M. furfur, the well known cause of pityriasis versicolor, is a strict lipophilic yeast, with predilection for indwelling catheters conducting lipid solutions. Since the diagnosis of M. furfur is hampered by the slow growth and the requirement of lipid containing growth media, one must keep the organism in mind when signs of septicaemia occur in a patient receiving parenteral nutrition, especially in premature infants.

Catheterization, Central Venous↗
PubMed1993

Efficacy, safety, and dosing of desmopressin for nocturnal enuresis in Europe.

Desmopressin is a potent antidiuretic for nocturnal enuresis with few and mostly insignificant adverse reactions. Almost 80 years ago, the antidiuretic effects of extracts of the posterior pituitary were first reported. The molecular structure of the peptide vasopressin arginine vasopressin (AVP) became known in 1956, and by 1967, a synthesized modification of AVP, known as DDAVP, or desmopressin, was introduced. Toxicity studies performed on experimental animals support the conclusion that desmopressin is considerably more potent as an antidiuretic than AVP and has an exceptional safety margin. Further, clinical experience reveals that from 1974 to June 1992 only 21 patients using desmopressin had serious adverse reactions (water intoxication), and no fatalities occurred. Seven of 10 children with nocturnal enuresis who receive desmopressin stop their bedwetting completely or reduce it significantly, with best results noted in children over 10 years of age. Given these results, the preferred treatment in Europe for children with nocturnal enuresis is the sequential combination of desmopressin and the enuresis alarm.

Adolescent↗
PubMed1992

Correction of optic disc measurements on fundus photographs.

If defined as diameter of image/diameter of object, the magnification M of the eye-camera system is kB, where k is a camera constant and B represents the vergence of the internal axis of the eye. The magnification may be assessed (1) from the length l of the eye, using the formula 1.336 k/(l-0.0016); (2) from the glass refraction G, using the formula kD/(1-G/D), in which D is the "normal" refractive power of the eye; or (3) from the principal point refraction A and the deviation delta D1 from the "normal" refractive power of the cornea, using the formula kD.(1 + delta B/D), where delta B = A + 0.84 delta D1. If k is 0.042 m, as in the Zeiss camera, and D is about 60 dpt, the formulas may be written as (1) M = 0.056/(l-0.0016); (2) M = 2.5/(1-0.017 G); and (3) M = 2.5.(1 + 0.017 delta B).

Fundus Oculi↗
PubMed1992

Mathematical description of the concentration of oxytetracycline and penicillin-G in tissue cages in calves as related to the serum concentration.

A mathematical model based on Fick's laws of diffusion describing the concentration of drug in tissue cage models was elaborated. The model takes into account differences in protein binding, tissue cage geometry and serum pharmacokinetics. The validity of the model was tested against experimental data obtained from a tissue cage model in calves by simultaneous fitting to serum and tissue cage fluid (TCF) data in a non-linear least-squares regression computer program. Concentrations of penicillin-G (pen-G) in serum and TCF following intravenous (i.v.) administration of potassium pen-G were adequately described by the mathematical model. Concentrations in TCF after intramuscular (i.m.) administration of the same drug and of procaine pen-G could be predicted by the mathematical model. Concentrations of oxytetracycline (OTC) in serum and TCF following i.v. administration and continuous i.v. infusions were also adequately described by the model, and TCF concentrations after i.m. administration of the same drug could be roughly predicted. The results indicate that pen-G and OTC have the same permeability coefficient for transport from serum to TCF.

Animals↗