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Biomedical subjects

B Bengtsson

Publications and source records attributed to B Bengtsson.

At least 37 records · Page 2Linked to original sources
PubMed2000

Reliability of computerized perimetric threshold tests as assessed by reliability indices and threshold reproducibility in patients with suspect and manifest glaucoma.

BACKGROUND: High reproducibility of test measurements is often considered an indication of high reliability of test results. The aim of the current study was to analyse the role of the traditional perimetric reliability indices, False Negative and False Positive responses, and Fixation Losses, as indicators of test reliability in comparison with threshold reproducibility in patients with suspect or manifest glaucoma. METHODS: Perimetry was performed in one eye in each of 76 patients. Each eye was tested twice within approximately one week using the Humphrey II 30-2 SITA STANDARD program. Frequencies of False Positive and False Negative answers, and rates of Fixation Losses were related to threshold reproducibility and to general field status as expressed by Mean Deviation from age-normal threshold values using stepwise multiple linear regression analysis. RESULTS: Substantial field loss was associated both with low threshold reproducibility (p<0.0001) and with increased frequency of False Negative answers (p=0.047). The traditional reliability indices contributed marginally compared to amount of field loss when predicting threshold reproducibility; the coefficient of determination decreased non-significantly from 0.37 to 0.33 when excluding the three reliability indices as explanatory variables from the regression model. Frequencies of False Positive answers and Fixation Losses showed no association to field status or to threshold reproducibility. CONCLUSION: Reliability of visual field test results in patients with glaucoma expressed as threshold reproducibility, can be predicted by amount of field loss alone, and traditional patient reliability indices contribute surprisingly little in this regard.

Aged↗
PubMed2000

False-negative responses in glaucoma perimetry: indicators of patient performance or test reliability?

PURPOSE: To study whether false-negative answers in computerized glaucoma perimetry indicate the patient's ability to perform perimetry or test result reliability. METHODS: A retrospective evaluation was performed of visual field test results obtained with a perimetry program (Humphrey 30-2 Sita Standard; Humphrey Instruments, San Leandro, CA) in 70 consecutive patients with unilateral glaucomatous field loss. Frequencies of false-negative answers were compared between the two eyes of each patient and related to amount of visual field damage in the glaucomatous eyes using linear regression analysis. RESULTS: Frequencies of false-negative answers were higher in eyes with field loss. The intrapatient intereye difference was 6.6% on average (P < 0.0001). In seven subjects with false-negative frequency of 5% or more in both eyes, the mean difference was 12.7% between eyes. The differences in false-negative answers depended significantly on the amount of field loss in the glaucomatous eyes (P = 0.0003). Larger differences were seen in patients with advanced field loss in the affected eye. CONCLUSIONS: The increased frequencies of false-negative answers in eyes with field loss were strongly associated with field status. The higher false-negative frequencies in eyes with glaucomatous field loss compared with unaffected eyes may be explained by the increased variability in threshold values typically found in such eyes. False-negative answers in patients with glaucoma therefore represent eye rather than patient status.

Adult↗
PubMed1999

Persistent Organochlorines in the Effluents from a Chlorine-Bleached Kraft Integrated Pulp and Paper Mill in Southeast Asia.

A bleached sulfate integrated pulp and paper mill producing printing and writing paper from mixed tropical hardwood and bamboo was studied. The mill uses a "conventional bleaching sequence," C-E-H1-H2, with an average molecular chlorine consumption of 50 kg per ton of air-dried pulp (ADP). The content of polychlorinated dibenzofurans (PCDFs) and dibenzo-p-dioxins (PCDDs) in the bleaching filtrate in terms of the nordic toxicity equivalent (N-TEQ) was 33.5, 1.15, 0.56, and 0.014 pg/L for the E, C, H1, and H2 bleaching stages, respectively. The corresponding PCDFs and PCDDs loads in ng/t ADP were in the same ranking, i.e., 670, 69, 11.2, and 0.28, respectively. The congener and isomeric pattern of PCDFs and PCDDs of the bleaching filtrate and the bleached pulp was found to be typical for the chlorine bleaching plant effluent. The obtained dioxin load formed in the mill is in agreement with Western studies for the given multiple chlorine of 0.21-0.23. The load is, however, lower than reported discharges from Scandinavian mills using 1980s bleaching technologies, but substantially higher than the discharges from mills with modern bleaching technologies. Modifications in the bleaching plant to reduce molecular chlorine use are necessary to reduce dioxin formation.http://link.springer-ny.com/link/service/journals/00244/bibs/37n3p303.html

Journal Article↗
PubMed1999

Early Manifest Glaucoma Trial: design and baseline data.

OBJECTIVES: The Early Manifest Glaucoma Trial (EMGT) will evaluate the effectiveness of reducing intraocular pressure (IOP) in early, previously untreated open-angle glaucoma. Its secondary aims are to explore factors related to glaucoma progression and to study the natural history of the disease. This article describes the EMGT design and presents baseline data. DESIGN: Randomized, clinical trial. PARTICIPANTS: Newly diagnosed patients 50 to 80 years of age with early glaucomatous visual field defects were mainly identified from a population-based screening of more than 44,000 residents of Malmö and Helsingborg, Sweden. Exclusion criteria were advanced visual field loss; mean IOP greater than 30 mmHg or any IOP greater than 35 mmHg; visual acuity less than 0.5; and inability to complete follow-up protocols. INTERVENTIONS: After informed consent, patients were randomized to treatment or no initial treatment with close follow-up. Treated patients had laser trabeculoplasty and started receiving topical betaxolol twice daily in eligible eyes. Follow-up visits include computerized perimetry and tonometry every 3 months and fundus photography every 6 months. Decisions to change or begin treatment are made jointly with the patient when EMGT progression occurs and also later if clinically needed. MAIN OUTCOME MEASURES: The EMGT progression is defined by sustained increases of visual field loss in three consecutive C30-2 Humphrey tests, as determined from computer-based analyses, or by optic disc changes, as determined from flicker chronoscopy and side-by-side comparisons of fundus photographs performed by masked, independent graders. RESULTS: A total of 255 patients were randomized between 1993 and 1997 and will be followed for at least 4 years. All had generally good health status; mean age was 68.1 years, and 66% were women. At baseline, mean IOP was 20.6 mmHg and 80% of eyes had IOP less than 25 mmHg. CONCLUSIONS: The Early Manifest Glaucoma Trial is the first large randomized, clinical trial to evaluate the role of immediate pressure reduction, as compared to no initial reduction, in patients with early glaucoma and normal or moderately elevated IOP. Its results will have implications for: (1) the clinical management of glaucoma; (2) understanding the role of IOP and the natural history of glaucoma; and (3) evaluating the rationale for glaucoma screening.

Adrenergic beta-Antagonists↗
PubMed1999

Optic nerve head sector analysis recognizes glaucoma most effectively around disc poles.

PURPOSE: To analyze the topography of normal and glaucomatous discs with the goal of developing improved strategies to discriminate between normal and glaucomatous eyes. SUBJECTS AND METHODS: Raster tomography was performed in both eyes of 225 healthy subjects and in 296 eyes of 214 glaucoma patients. Cup area, average cup radius, rim area and minimal rim width were measured in 24 sectors around the optic nerve head at nine different depths from the reference plane. Receiver Operating Curves (ROC) for numerous combinations of parameter, sector and depth were calculated and compared. RESULTS: Discrimination between glaucomatous and normal eyes varied widely between single sectors of the optic disc, and was best at the vertical poles of the disc, intermediate in nasal sectors and worst in temporal sectors. When single sectors or combinations of sectors at the superior pole were combined with their counterparts at the inferior pole of the optic nerve, the gain in sensitivity exceeded the loss in specificity, and discrimination improved. Separation declined dramatically if any of the 8 temporal sectors were involved in such analysis. Depth influenced discrimination only slightly. CONCLUSION: Single sectors located close to the vertical meridian yielded better discrimination than global measurements. When two or more sectors at the superior pole were combined with each other, as well as with their counterparts at the inferior pole, discrimination improved even further. Localized changes concurred frequently, but asymmetrically at both poles of the disc. The depth from reference plane used to define the cup was not critical for separation between normal and glaucomatous eyes.

Adult↗
PubMed1999

Refractive changes in the elderly.

PURPOSE: Cross-sectional studies have consistently shown younger people to be less hyperopic than older people, but it is not known if this reflects a myopic shift from one generation to the next or a true age-related shift. METHODS: We used data from three population surveys to study cohort phenomena and true age-related changes in refraction of elderly people in southern Sweden. Differences concerning the use of cycloplegics made us restrict comparisons between refractions in separate studies to persons aged 65 to 74 years, in whom our measurements were considered unlikely to have been affected by accommodation. RESULTS: An apparent increase in mean spherical equivalent as rapid as 0.6 D in 10 years was observed in our latest (and largest) cross-sectional survey. The myopic shift, from one generation to the next, was limited to 0.25 D in 25 years. This discrepancy was explained by a true age-related hyperopic shift between 55 and 70, which was confirmed in a longitudinal study of over 1000 persons followed for more than 8 years. CONCLUSION: A true age-related hyperopic shift between 55 and 70 does indeed exist, and should not be disregarded by anyone who is prescribing spectacles or performing surgery for refractive errors. In the long run, however, a persisting secular trend towards myopia could prove even more important.

Aged↗
PubMed1999

Inter-subject variability and normal limits of the SITA Standard, SITA Fast, and the Humphrey Full Threshold computerized perimetry strategies, SITA STATPAC.

PURPOSE: To establish and evaluate inter-subject variability and normal threshold limits for the new SITA strategies and to compare them with those obtained with the traditional Humphrey Full Threshold algorithm. METHODS: Data from 330 eyes of 330 normal subjects were collected at 10 centres in order to establish limits of normality for the new SITA strategies and thus, to make it possible to subject SITA fields to computer-assisted visual field analysis. Two visual field tests were obtained with each of the SITA Standard, SITA Fast, and the Full Threshold algorithms. RESULTS: Inter-subject variance was 31% smaller with SITA Standard and 41% smaller with SITA Fast than with Full Threshold (p<0.0001). Age-dependent decrease of differential light sensitivity was also significantly smaller with both SITA algorithms than with Full Threshold (p<0.0001), 23% and 25% respectively. Mean sensitivity was somewhat higher with both SITA Standard (29.5 dB) and SITA Fast (29.9 dB) as compared to Full Threshold (28.3 dB) (p<0.0001). Normal limits were tightened between 9 to 29% at different significance levels with SITA. CONCLUSION: SITA test results from eyes with normal visual fields will on average be more even from centre to mid-periphery as compared with Full Threshold fields. They will also appear slightly lighter in grey-scale representations. Because of smaller inter-subject variance, shallower depressions are needed in SITA fields for statistical and clinical significance.

Adult↗
PubMed1999

Comparing significance and magnitude of glaucomatous visual field defects using the SITA and Full Threshold strategies.

PURPOSE: To evaluate and compare visual field test results as presented by the Statpac interpretation tools in tests obtained with the new short SITA Standard and the even shorter SITA Fast strategies to the traditional Humphrey Full Threshold strategy. SUBJECTS AND METHODS: One eye of each of 44 glaucoma patients was examined four times with each of the Humphrey SITA Standard, SITA Fast, and Full Threshold strategies. Another 21 eyes of 21 normal subjects had one eye examined once with each of the three strategies. RESULTS: Average light sensitivity was highest with the shortest SITA Fast strategy and lowest with the longest Full Threshold strategy. Magnitude of field loss as defined by the Statpac Mean Deviation (MD) did not differ between the three strategies. In the glaucoma patients, both SITA strategies showed larger number of significantly depressed points in Statpac probability maps than the Full Threshold strategy. In the normal subjects SITA Standard showed more significantly depressed points, close to the statistically expected number, at the lowest probability level (p<5%) than both Full Threshold and SITA Fast. At higher probability levels (p<1%) SITA Standard and Full Threshold showed similar numbers of significantly depressed points. CONCLUSION: Both SITA Standard and SITA Fast identified at least as much significant glaucomatous field loss as the Full Threshold using the Statpac interpretation tools.

Adult↗
PubMed1999

Clinical and experimental effects of growth hormone secretagogues on various organ systems.

A new class of growth hormone (GH) secretagogues (GHS) has been developed. In rats, the GHS hexarelin exerts cardioprotective effects. In humans, GHS increase growth velocity in children with short stature/GH deficiency. In adults, a combined infusion of GH releasing peptide-2 and thyrotropin releasing hormone increases circulating concentrations of GH as well as that of insulin-like growth factor-I. In healthy volunteers, oral GHS administration reverses diet-induced catabolism, and in healthy obese men, oral GHS treatment increases fat-free mass. However, little is known about the possible direct effects of GHS and there are few long-term studies. Therefore, it is not yet possible to fully evaluate the use of GHS.

Animals↗
PubMed1998

[Vulvar complaints in young girls need instant professional evaluation].

As vulvovaginal disease are nog very common in prepubescent girls, it may seem reasonable to suspect sexual abuse when a small girl presents with complaints in the genital area. However, the very fact that there are visible changes suggests that it is no a case of sexual abuse, the signs of which are usually more subtle. To arrive at a correct diagnosis, and avoid unnecessary, traumatic investigation into the possibility of sexual abuse, it is essential that such patients be examined from the outset by physicians experienced in this field.

Child↗
PubMed1998

Evaluation of a new threshold visual field strategy, SITA, in normal subjects. Swedish Interactive Thresholding Algorithm.

PURPOSE: We developed a new family of test algorithms. This is an evaluation in normal subjects. METHODS: One eye in each of twenty normal subjects, with a mean age of 37 years (range 26 to 59), was tested twice with each of the SITA, Full Threshold and Fastpac strategies of the Humphrey perimeter at 3 separate visits. Actual test times and number of stimulus exposures were compared. Test-retest variability and levels of threshold estimates were also calculated and compared between strategies. RESULTS: In all subjects test times were shortest with SITA, 6.14 minutes in average, which was 50% as compared to Full Threshold (p<0.001) with an average of 12.27 minutes, and a reduction of 16% as compared to Fastpac (mean 7.28 minutes, p<0.0001). SITA required 287 stimulus exposures on the average, significantly fewer (p<0.0001) than corresponding numbers with Full Threshold (mean of 404), and significantly more (p<0.0001) than with Fastpac (average 240). SITA results showed significantly lower test-retest variability than results obtained with Fastpac (p=0.0002), and just as low as those of the Full Threshold strategy (p=0.0979). Threshold values obtained with SITA were slightly higher than those produced by the other two strategies. CONCLUSIONS: The results confirm those of previously reported simulated tests, that improved test algorithms using advanced visual field models and mathematical analyses performed in real time may effectively shorten computerized perimetry tests, while achieving the same or better test quality than today's standard methods.

Adult↗
PubMed1998

Age, gender, IOP, refraction and optic disc topography in normal eyes. A cross-sectional study using raster and scanning laser tomography.

PURPOSE: To study the influence of age, gender, intraocular pressure and refraction on optic disc topography in normal subjects. METHODS: We studied both eyes of 225 healthy subjects between 20 and 80 years of age using raster tomography (Glaucoma-Scope, Ophthalmic Imaging Systems, Sacramento CA, USA) and scanning laser tomography (Heidelberg Engineering, Heidelberg, Germany). We chose to study cup area and maximum cup depth, two variables that are minimally influenced by the operator. RESULTS: Raster and scanning laser tomography results were strongly correlated. Cup area was independent of age, gender and refraction. It was weakly associated with IOP, but this association was significant only when the cup area was measured with scanning laser tomography. Maximum cup depth was independent of age, gender and IOP. It was larger in hypermetropic eyes, although this trend was significant only when maximum cup depth was measured with raster tomography. CONCLUSION: Our results indicate that optic nerve head topography does not change significantly with age in normal subjects. This information has important implications for follow-up of pathological changes in optic nerve head topography.

Adult↗
PubMed1998

Evaluation of a new perimetric threshold strategy, SITA, in patients with manifest and suspect glaucoma.

PURPOSE: To evaluate the performance of the new perimetric threshold strategy SITA relative to older methods. METHOD: Thirty-two patients with either glaucoma or ocular hypertension performed two threshold visual field tests with each of three threshold strategies, SITA, Humphrey Full Threshold, and Fastpac. Testing was distributed over three visits, and testing order was balanced between strategies to control for order effects. RESULTS: SITA tests consumed 54% of the time taken by Full Threshold tests on average, and 85% of Fastpac tests; SITA's test times were significantly shorter than those of Full Threshold (p<0.0001) and Fastpac (p=0.0008). Test-retest threshold variability did not differ significantly between strategies. Intertest variability of the pattern deviation analysis was lowest in SITA (p<0.01) relative to both Full Threshold and Fastpac. Both SITA and Fastpac showed higher than expected average sensitivities relative to Full Threshold. SITA and Fastpac showed approximately the same amount of visual field loss. There was a significant relationship between Mean Deviation and the SITA function used to shorten stimulus sequences at points where measurement errors are small (p<0.0001). CONCLUSION: Our results suggest that SITA matches the precision of older thresholding methods, consuming considerably and significantly less test time. This indicates that SITA could replace Full Threshold as the standard clinical test used in glaucoma management, without decreasing the quality of test results.

Aged↗
PubMed1998

SITA Fast, a new rapid perimetric threshold test. Description of methods and evaluation in patients with manifest and suspect glaucoma.

PURPOSE: To describe and evaluate the new rapid SITA Fast computerized perimetric threshold strategy. METHOD: Computer simulations of visual fields were used to develop a new rapid threshold strategy, SITA Fast. In a clinical evaluation 30 patients were examined twice with each of the Full Threshold, Fastpac and SITA Fast strategies. RESULTS: SITA Fast had significantly shorter test time using on average 34% of the test time when compared to the Full Threshold strategy (p<0.0001) and 53% compared to Fastpac (p<0.0001). Reproducibility, calculated as the average Root Mean Square Error, was 1.84 dB in SITA tests, and 1.99 dB and 2.02 dB with Full Threshold and Fastpac, respectively. Both SITA Fast and Fastpac showed slightly higher sensitivities on average than theoretically expected. Sensitivity differences were larger in eyes with large differences in test time. Defects detected by SITA Fast were often deep and more localised than those detected by the Full Threshold and the Fastpac strategies. CONCLUSION: SITA Fast tests were considerably shorter than Fastpac tests. The low test-retest variability found in the SITA Fast tests implies that it may be a sensitive test for detection of field progression.

Aged↗
PubMed1998

Detection of extended-spectrum beta-lactamases. The reliability of methods for susceptibility testing as used in Denmark.

The susceptibility testing methods used in Denmark were evaluated with respect to their ability to detect cephalosporin resistance with cefuroxime as indicator, especially resistance caused by extended-spectrum beta-lactamases (ESBLs). Two methods for determination of minimal inhibitory concentration (MIC), three agar diffusion methods, a disc approximation test and the ESBL-Etest were used against a panel of strains producing well-known beta-lactamases. The tablet diffusion test (Rosco Neo Sensitabs) as the most used in Denmark had the lowest detection rate of cefuroxime resistance among ESBL-producing strains. The prediffusion method, which is only used at one laboratory, was the most reliable method for such detection. The MIC methods were in good agreement, but the detection rate for resistance due to ESBLs was low and depended on the antibiotics used. The disc approximation test and the ESBL-Etest both resulted in an acceptable ESBL detection rate. The latter tests discriminated between isolates producing the frequent chromosome-mediated and the in Denmark probably very rare ESBL-mediated cephalosporin resistance. For the evaluation of susceptibility tests such strains require special attention.

Alcaligenes↗