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Biomedical subjects

G Lindgren

Publications and source records attributed to G Lindgren.

At least 19 recordsLinked to original sources
PubMed1992

Studies on the individual and combined diuretic effects of four Vietnamese traditional herbal remedies (Zea mays, Imperata cylindrica, Plantago major and Orthosiphon stamineus).

Herbal remedies are widely used in Vietnam alongside modern drugs. We assessed the diuretic effect of four traditional Vietnamese herbal remedies from Zea mays, Imperata cylindrica, Plantago major and Orthosiphon stamineus, all claimed to produce an increase of diuresis. No influence was recorded for the 12- and 24-h urine output or on the sodium excretion for any of the drugs when tested under standardized conditions in a placebo controlled double-blind crossover model. The present study indicates the need for critical review of the present recommendations regarding therapy with plant materials in countries relying on empiric traditions.

Adult↗
PubMed1989

Test-retest variability in glaucomatous visual fields.

We measured test-retest variations in computerized visual fields from glaucomatous eyes. Fifty-one patients were tested four times within a four-week period; the severity of disease varied from incipient to advanced. We determined the dependence of threshold variability on defect depth and test point location. In areas of the visual field initially found to have moderate loss of sensitivity, variation in follow-up measurements ranged from normal sensitivity to absolute defect, with little dependence on distance from fixation. Conversely, large changes were considerably more unusual in locations initially showing normal or near-normal sensitivities, and variability was lowest in the most central portion of the field. Our findings suggest that differentiation between true progression and random variation will be facilitated if these factors are taken into account, as well as if comparisons are based on more than two tests. The complex nature of interest variation in glaucoma makes it natural to approach this problem with the help of computer-assisted analyses.

Adult↗
PubMed1989

The effect of perimetric experience in normal subjects.

Two groups of normal subjects were submitted to repeated automated static threshold perimetry. Perimetric results were strongly affected by the level of experience in some subjects; in the majority, however, the effect of experience was small. Initial field tests often showed high numbers of depressed points. Sensitivity increased with perimetric training, particularly between the first sessions. Those subjects who improved most started low, gradually approaching normal levels with experience. Learning effects were more pronounced peripherally than paracentrally and "untrained" fields characteristically showed concentric contraction with numerous points with low sensitivity peripherally. An important practical conclusion is to allow repeated testing of all inexperienced patients in whom initial fields do not agree with clinical findings. A chart showing a concentrically narrowed field should be viewed with particular suspicion. Furthermore, a single initial field may constitute an inadequate baseline for clinical follow-up.

Adult↗
PubMed1989

Visual field interpretation with empiric probability maps.

Automated visual field charts may be difficult to interpret partly because of the magnitude and complex nature of normal threshold variability. We devised two types of empiric probability maps in which this variability is taken into account and the significances of measured threshold values are displayed. These maps are highly sensitive to nonobvious but significant paracentral field loss but will at the same time deemphasize false-positive patterns commonly found more peripherally. They also frequently show field defects before these are obvious in conventional threshold printouts. In addition, they differentiate between generalized loss of sensitivity and localized field defects.

Cataract↗
PubMed1989

Statistical evaluation of cell kinetic data from DNA flow cytometry (FCM) by the EM algorithm.

Flow cytometric DNA measurements yield the amount of DNA for each of a large number of cells. A DNA histogram normally consists of a mixture of one or more constellations of G0/G1-, S-, G2/M-phase cells, together with internal standards, debris, background noise, and one or more populations of clumped cells. We have modelled typical DNA histograms as a mixed distribution with Gaussian densities for the G0/G1 and G2/M phases, an S-phase density, assumed to be uniform between the G0/G1 and G2/M peaks, observed with a Gaussian error, and with Gaussian densities for standards of chicken and trout red blood cells. The debris is modelled as a truncated exponential distribution, and we also have included a uniform background noise distribution over the whole observation interval. We have explored a new approach for maximum-likelihood analyses of complex DNA histograms by the application of the EM algorithm. This algorithm was used for four observed DNA histograms of varying complexity. Our results show that the algorithm works very well, and it converges to reasonable values for all parameters. In simulations from the estimated models, we have investigated bias, variance, and correlations of the estimates.

Algorithms↗
PubMed1987

Normal variability of static perimetric threshold values across the central visual field.

We assessed the variability of results in normal subjects of computerized static threshold perimetry of the central 30 degrees field. Variability of measured threshold values was highly dependent on eccentricity. This included variability among individuals, test-to-test variability within individuals, and intratest variability. All values were significantly larger in the midperiphery than centrally. We found that the mean sensitivity decrement with age was eccentricity dependent, so that the age-corrected normal visual field became not only depressed but also steeper with age. Distributions of individual pointwise deviations from the age-corrected normal mean thresholds were significantly nongaussian. The dependency of variability on test point location, the nongaussian distributions of deviations from age-corrected means, and the variability of age-induced sensitivity reduction should all be considered in the interpretation of computerized visual fields, and particularly in the design of statistical programs for field analysis. Programs not considering these factors are likely to result in misleading analyses.

Adult↗
PubMed1986

Preeruptive effect of NaF tablets on caries in children from 12 to 17 years of age.

The purpose of this study was to evaluate the preeruptive effect of NaF tablets on caries in proximal surfaces of permanent molars and premolars. The material consisted of 47 subjects who had consumed fluoride tablets for a minimum of 5 yr between 1/2 and 6 yr of age in accordance with recommendations from the National Swedish Board of Health and Welfare (F+-group) and 69 comparable children who had never consumed such tablets (F(-)-group). All had resided since birth in an area with a water fluoride concentration of 0.2 ppm and had been exposed to fluorides in toothpaste, mouthrinse solution and varnish since at least the age of 6. The children were examined by means of bitewing radiographs at the ages of 12, 13, 14 and 17. Two confounding factors, i.e. salivary counts of Streptococcus mutans and lactobacilli, were estimated and used for correction of crude caries differences. The mean values of these factors were higher in the F(-)-group than in the F+-group. The results showed a statistically significantly higher caries prevalence in the F(-)-group compared to the F+-group when the children were 14-yr-old, 4.4 vs. 2.9 DFS, corresponding to a caries reduction of about 34%. After correction for confounding, this was reduced to 24%, representing a non-significant difference of 1.1 DFS but still indicating a preeruptive effect. At the age of 17, the difference in caries prevalence was statistically not significant, 7.1 vs. 5.6 DFS, corresponding to a reduction of 21%. Based on corrected data, this was reduced to 15%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1985

Model for the study of the preeruptive effect of NaF tablets on caries in permanent teeth.

The purpose of this study was to elaborate a model for estimating the caries-reducing effect of a preventive measure with due consideration of background factors. The material comprised 50 children, who had consumed NaF tablets regularly during preschool age, and 76 comparable children who had never consumed NaF tablets. They were all examined at 12 and 13 yr of age. Information on caries and, as confounding factors, dietary habits, oral hygiene and microbiologic variables, was obtained on both occasions. Correlations between the parameters and caries, their discriminating effects and interaction between them were studied. The results showed that correction for confounding diminished the crude caries-reducing effect of NaF tablets. Streptococcus mutans and lactobacilli turned out to be the strongest confounders to discriminate well as single variables and to behave logically in analyses of interaction. Therefore, these factors are recommended in the first place for inclusion in a correction model. If the material is sufficiently large for a further breakdown, oral hygiene (represented by bleeding on probing) could be added. The model will be used in future studies of the preeruptive effect of NaF tablets on caries in permanent teeth in the same population.

Adolescent↗
PubMed1985

Acetylcholinesterase inhibition by sulphur and selenium heterosubstituted isomers of N,N-diethylcarbamyl choline and carbaryl.

Nine sulphur and selenium heterosubstituted isomers of N,N-diethylcarbamylcholine and carbaryl have been prepared and their inhibiting activity towards electric eel acetylcholinesterase (E.C. 3.1.1.7) have been measured. The N,N-diethylcarbamylcholines acted only as reversible inhibitors, i.e. they could not carbamylate the enzyme. The reversible inhibition was of mixed type. Sulphur and selenium substitution had only marginal effects on Ki(0.2-0.3 mM) but reduced the value of K'i. The heterosubstituted carbaryl analogues were, with one exception, found to be irreversible inhibitors, about 100 times less potent than carbaryl.

Animals↗
PubMed1979

Clinical and arthrographic studies on the valve mechanism in communicating popliteal cysts.

Forty-one knee joints presenting with significant popliteal cysts were examined clinically and arthrographically. The fluid was aspirated from the cysts and replaced by contrast medium of low viscosity. On knee flexion the contrast fluid spontaneously passed over into the joint in 16 cases (no valve mechanism), in 7 small amounts of fluid were forced into the joint when the cysts were manually compressed, and in 18 no fluid passage to the joint was observed on manipulation (valve mechanism). When a valvular action was established, effusion in the joint was rare and the fluid from the cyst was usually viscous. The cysts with a valvular connection were significantly larger than those without a valve mechanism.

Adult↗
PubMed1978

Growth of schoolchildren with early, average and late ages of peak height velocity.

A sample of Swedish urban schoolchildren (357 girls, 373 boys) born in 1954/55 followed from 10 to 18 years were grouped according to peak height velocity age (PHV age) into early, average and late maturers. Mean heights differed between the maturity groups at ages from 10.0 to 14.0 years for girls and 10.5 to 17.0 years for boys. Mean weights differed between the maturity groups at all ages up to 16.0 years for girls and up to 18.0 years for boys. The earlier the maturity process, the heavier for given height. The time differences between peak weight velocity (PWV) and PHV significantly differed between early, average and late maturers amounting to 0.9, 0.5 and 0.2 years respectively for girls and 0.6, 0.3 and -0.1 years respectively for boys. The time difference between menarche and PWV did not differ between the maturity groups and amounted to about 0.6 +/- 0.05 years (SD = 0.9). For boys a similar lack of difference between maturity groups was obtained concerning the time difference between secondary sex characteristics; stage 4 (SSC IV) and PWV. Mean height and weight for girls and boys differed between the maturity groups at PHV but not at PWV, menarche or SCC IV.

Adolescent↗
PubMed1977

A comparison of growth in twins and singleton controls of matched age followed longitudinally from 10 to 18 years.

A sample of 323 pairs of twins (94 MZ pairs, 133 DZ like-sexed pairs and 97 DZ unlike-sexed pairs born in 1954/55) were studied longitudinally from 10 to 18 years for boys and 10 to 16 years for girls. Height, weight, age at menarche and peak height and weight velocities (PHV and PWV) were studied. No significant differences occurred between twin categories in any two of these varieties, so in each sex the total twin group was compared with a group of matched singleton controls (380 boys and 360 girls). There were very small differences between the twin boys and their controls in height, weight and PWV-age. PHV occurred somewhat earlier in twin boys than in the controls. The height and weight peaks were significantly lower for the twin boys. For twin girls, however, a height and weight deficit was found during puberty and they also matured a little later than their controls according to both PHV, PWV and menarche. The height and weight peaks were also somewhat lower for the twin girls. One reason for the observed sex differences could be a proportionally higher mortality for twin boys, thus an effect of selective survival.

Adolescent↗