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Biometrical studies on buffalo, bovine and canine strains of Trypanosoma evansi isolated from species in Madras, India, were carried out. The buffalo, bovine and canine trypanosomes varied significantly in total length and width. The buffalo strain had a greater free flagellum, total length and width compared with the canine strain.
PURPOSE: To assess the long-term refractive and biometric outcomes of diode laser-treated eyes in threshold retinopathy of prematurity (ROP). METHODS: Cycloplegic autorefraction and biometry (Zeiss IOLMaster) were performed, at a mean follow-up of 11 years, on 16 laser-treated eyes with threshold ROP and 9 comparison eyes with subthreshold untreated ROP. RESULTS: The laser-treated eyes had a mean spherical equivalent of -2.33 D with a mean astigmatic error of 1.38 D. The comparison eyes had a mean spherical equivalent of +1.07 D with a mean astigmatic error of 0.42 D. This trend toward increased myopia in treated eyes did not achieve statistical significance (p=0.08). The myopia in the laser group appeared to be slowly progressive in nature when compared with earlier refractive data for these patients. The laser-treated eyes had reduced anterior chamber depth (ACD) compared with the subthreshold eyes (p=0.02). When physiologic accommodation was inhibited by cycloplegic drops, the anterior chamber deepened by 0.13 mm in the laser-treated eyes and by 0.06 mm in the comparison eyes. This effect of accommodation on ACD did not differ significantly between the two groups (p=0.23). The laser-treated eyes and the comparison eyes did not differ significantly in terms of axial length, corneal power, corneal diameter, or lens power. However, both groups had steeper corneas, shallower anterior chambers, and shorter axial lengths when compared with historical full-term controls. CONCLUSIONS: Myopia in premature infants requiring laser treatment for ROP is associated with a shallowing of the anterior chamber and a steepening of the cornea. Physiological accommodation is not impaired by laser therapy or by severe ROP.
We performed a biometric study that used A-mode ultrasonography on 106 subjects during ocular accommodation. The subjects were divided into two groups; group 1 included 76 subjects and group 2 included 30 subjects. In group 1, we measured the anterior chamber depth, lens thickness, and axial length in the right eye while the left eye, wearing corrective spectacles, focused at distances of 6 m, 33 cm, and 33 cm with an additional correction of +3.0 diopters to offset any accommodative effect. In group 2, we measured the anterior chamber depth, lens thickness, and axial length in the right eye while the left eye focused at distances of 6 m, 33 cm, and 12.5 cm. Similar to the left eyes in group 1, the left eyes in group 2 wore corrective spectacles during all procedures. During accommodation, decreased anterior chamber depth and thickening of the lens were noted in all cases. In group 1, axial length significantly increased an average of 0.06 +/- 0.01 mm (P < .0005) while the left eye focused at a distance of 33 cm. There were no significant changes with the additional +3.0 diopters (P < .05). In group 2, axial length significantly increased an average of 0.05 +/- 0.01 mm (P < .0005) when the left eye focused at a distance of 33 cm, and there was further significant elongation of 0.05 +/- 0.01 mm when the left eye focused at a distance of 12.5 cm. Collectively, these results suggest that axial length increases along with changes in the lens and anterior chamber depth during ocular accommodation.
The biometric, optical and physical properties of 19 pairs of isolated human eye-bank lenses ranging in age from 5 to 96 years were compared. Lens focal length and spherical aberration were measured using a scanning laser apparatus, lens thickness and the lens surface curvatures were measured by digitizing the lens profiles and equivalent refractive indices were calculated for each lens using this data. The second lens from each donor was used to measure resistance to physical deformation by providing a compressive force to the lens. The lens capsule was then removed from each lens and each measurement was repeated to ascertain what role the capsule plays in determining these optical and physical characteristics. Age dependent changes in lens focal length, lens surface curvatures and lens resistance to physical deformation are described. Isolated lens focal length was found to be significantly linearly correlated with both the anterior and posterior surface curvatures. No age dependent change in equivalent refractive index of the isolated lens was found. Although decapsulating human lenses causes similar changes in focal length to that which we have shown to occur when human lenses are mechanically stretched into an unaccommodated state, the effects are due to nonsystematic changes in lens curvatures. These studies reinforce the conclusion that lens hardening must be considered as an important factor in the development of presbyopia, that age changes in the human lens are not limited to the loss of accommodation that characterizes presbyopia but that the lens optical and physical properties change substantially with age in a complex manner.
Axial length measurements in 200 patients were performed with the Digital Biometric Ruler (DBR) and the Echo-oculometer with (Echo-osc) and without an oscilloscope (Echo). Measurements taken with the DBR and Echo-osc correlated better with each other than either did with the Echo measurements. In 32% of cases, the DBR and Echo-osc measurements differed by 0.4 mm or more, corresponding to a difference in predicted implant power of 1 diopter (D) or more. In 8% of cases, the measurements differed by 0.8 mm or more, corresponding to a difference in predicted implant power of 2D or more. In spite of these differences in axial length measurement in individual patients, intraocular lens implant power using the SRKTM formula, could be accurately predicted to within 1D of spectacle correction in 75% to 82% of cases, and to within 2D of spectacle correction in 94% to 98% of cases using either the DBR or Echo-osc measurements. Based on the poor correlation of the Echo axial length measurements to the other two, and the poorer implant power prediction accuracy, we do not recommend the use of the Echo-oculometer without an oscilloscope.
OBJECTIVES: Biometrical comparison procedures for cardiac imaging methods with continuous outcome are reviewed mainly concentrating on assessment and design adequate comparison of accuracy and precision. Univariate graphical and numerical representation of corresponding deviations is outlined to derive a 'check list' of minimum information necessary to compare the measurement methods. DATA: The methods reviewed here are illustrated by the comparison of standard 2DE bidimensional cardial volumetry versus assessment using TDE colour imaging in 28 normal probands. SOURCES: The paired t-test and the corresponding confidence interval approach are used to assess deviations in location of two imaging methods; the test procedures of Maloney and Rastogi Hahn and Nelson and Grubbs are surveyed as proposals for the comparison of precisions in paired data. The Krippendorff coefficient and the Bradley/Blackwood test are illustrated as surrogate measures for method concordance. CONCLUSIONS: Since these methods can be performed by simple modification of standard options available in most statistics software packages, this review intends to enable cardiologists to choose appropriate methods for statistical data analysis and representation on their own.
Biometrical alterations in a horse Trypanosoma evansi isolate were observed when passaged in laboratory rodents. The major parasite transformation observed was the increase in the total length as a consequence of an increase in some parasite measurements. These transformations probably occurred as a consequence of a host change from horse to rodents. No kinetoplastic forms were observed.
PURPOSE: The aim of this study was to investigate the changes in biometric measurements and corresponding refractive errors during a three-year period among university students exposed to high educational demands. METHODS: A three-year longitudinal cohort study was performed among 149 Norwegian engineering students (79 females and 70 males, mean age 20.6+/-1.2 years) measuring their refraction and ocular dimensions at the beginning and at the end of the period. The examinations included refraction, keratometry, and A-scan ultrasonographic measurements of the ocular components, all made in cycloplegia. RESULTS: After three years the mean refractive change was -0.52+/-0.45 D (p<0.05), which was accompanied by a change in lens thickness of 0.07+/-0.10 mm (p<0.05), and a vitreous chamber elongation of 0.27+/-0.30 mm (p<0.05). The results refer to the right eye. Stratification of the sample based on their initial refraction (myopes, emmetropes, and hyperopes) showed refractive change towards myopia for all subgroups as well as a significant increase in lens thickness and vitreous chamber depth. No significant three-year change in anterior chamber depth or corneal curvature was found in any of the groups. For all groups, vitreous chamber elongation gave a notable dioptric change in myopic direction. CONCLUSIONS: A shift in refraction towards myopia after puberty is accompanied by vitreous chamber elongation which can explain the dioptric change in myopic direction.
The discriminant validity of the interpersonal-affective and social deviance traits of psychopathy has been well documented. However, few studies have explored whether these traits follow distinct or comparable developmental paths. The present study used the Multidimensional Personality Questionnaire (A. Tellegen, in press) to examine the development of the psychopathic traits of Fearless Dominance (i.e., interpersonal-affective) and Impulsive Antisociality (i.e., social deviance) from late adolescence to early adulthood in a longitudinal-epidemiological sample of male and female twins. Results from mean- and individual-level analyses revealed stability in Fearless Dominance from late adolescence to early adulthood, whereas Impulsive Antisociality declined over this developmental period. In addition, biometric findings indicated greater genetic contributions to stability in these traits and greater nonshared environmental contributions to their change over time. Collectively, these findings suggest distinct developmental trends for psychopathic traits from late adolescence to early adulthood.
A model is described for the biometrical analysis of interaction behavioural characteristics. The model is illustrated by analysis of the mating speed of Drosophila pseudoobscura derived from crosses of fast and of slow mating strains generated through artificial selection.
Lines of Drosophila melanogaster, bidirectionally selected for extreme and opposite expression of central excitatory state (CES), were subjected first to biometrical and then to chromosome analysis. The analyses revealed that low CES expression is partially dominant to high, at least two chromosomes (II and III) are correlated with CES expression, for the low line, both chromosomes, II and III, are necessary for low expression, cytoplasmic factors are involved with CES expression, and loci of minor effect on the X and Y chromosomes are correlated with CES expression.
Despite the importance of competition as an evolutionary determinant in natural populations there have been few studies of the genetical control of competitive ability. Here, we report the results of a biometrical analysis of four continuously varying traits which, between them, describe the competitive interactions in mixed cultures of Drosophila melanogaster. The analysis involved the parental, F1, F2 and backcross generations (including all reciprocals) derived from crosses between two highly inbred lines isolated from the Texas population of D. melanogaster. The competitive performance of each genotype in monoculture and in duoculture with a phenotypically distinct tester were assessed using a yield-density regression analysis. Appropriate genetic models were fitted using a variance weighted least squares procedure and the resulting genetic components of the generation means used to define the genetical architecture of competition. Of the four competitive parameters investigated here the e-value, which describes the competitive performance of the indicator genotype at a fixed reference density, was found to be determined by simple additive genetic effects with no evidence of significant dominance. Conversely, competitive performance in monoculture (intra-genotypic competition) did display a significant net dominance component and the observed values in the F1 and parental generations indicated some degree of heterosis. Of the two competitive parameters determining performance in duoculture (inter-genotypic sensitivity and inter-genotypic pressure) the former was found to have a complex genetic determination involving not only additive and dominance components of the progeny's own genotype but also dominance components of the F1 maternal genotypes. There were also additive-dominance and dominance-dominance non-allelic interactions. Heterosis was evident, determined both by the progeny's own genotype and by one of the F1 maternal genotypes.(ABSTRACT TRUNCATED AT 250 WORDS)
The aphid Schizaphis graminum is an important vector of the viruses that cause barley yellow dwarf disease. We studied the genetic architecture of virus transmission by crossing a vector and a non-vector genotype of S. graminum. F1 and F2 hybrids were generated, and a modified line-cross biometrical analysis was performed on transmission phenotype of two of the viruses that cause barley yellow dwarf: Cereal yellow dwarf virus (CYDV)-RPV and Barley yellow dwarf virus (BYDV)-SGV. Our aims were to (1) determine to what extent differences in transmission ability between vectors and non-vectors is due to net additive or non-additive gene action, (2) estimate the number of loci that determine transmission ability and (3) examine the nature of genetic correlations between transmission of CYDV-RPV and BYDV-SGV. Only additive effects contributed significantly to divergence in transmission of both CYDV-RPV and BYDV-SGV. For each luteovirus, Castle-Wright's estimator for the number of effective factors segregating for transmission phenotype was less than one. Transmission of CYDV-RPV and BYDV-SGV was significantly correlated in the F2 generation, suggesting that there is a partial genetic overlap for transmission of these luteoviruses. Yet, 63% of the F2 genotypes transmitted CYDV-RPV and BYDV-SGV at significantly different rates. Our data suggest that in S. graminum, the transmission efficiency of both CYDV-RPV and BYDV-SGV is regulated by a major gene or set of tightly linked genes, and the transmission efficiency of each virus is influenced by a unique set of minor genes.
PURPOSE: To determine patient demographics and the ocular biometric parameters in patients presenting for cataract surgery within the public hospital system, in a defined New Zealand population. METHOD: Prospective study of 502 eyes of 488 consecutive patients undergoing cataract surgery. A clinical assessment, including refraction, keratometry (K), A-scan ultrasound and Orbscan II computerized topography was performed on each eye. RESULTS: The mean age of the group was 74.9 +/- 9.8 years (mean +/- SD) with a female predominance (62%). Ethnic origin included 72% European, 8% Maori, 10% Pacific Islander, 4% Asian, 3% Indian and 3% other ethnic origins. The mean Log MAR visual acuity of eyes prior to cataract surgery was 0.88 +/- 0.57 (approximately 6/48(-1)). Corneal topographic (keratometric) maps were classified into five groups: 34% round, 10% oval, 31% symmetrical bow tie, 12% asymmetrical bow tie and 13% irregular. The mean steepest K measurement was 44.1 +/- 1.7 D, the median keratometric astigmatism 0.89 D (range 0.0-6.5 D) and the steepest corneal meridian was horizontal in 50% and vertical in 43%. Seven per cent of corneas were spherical. Refraction revealed a mean sphere of 0.0 +/- 3.1 D and a mean cylinder of -1.2 (range 0.0-7.5 D). Refractive astigmatism was with-the-rule in 15%, against-the-rule in 50% and oblique in 15%, with 20% spherical. Axial length was a mean of 23.14 +/- 1.03 mm. CONCLUSION: Patients presenting for cataract surgery in this study were predominantly elderly, female, of European Caucasian ethnicity and exhibited relatively poor corrected visual acuity in the affected eye. Interestingly, 41% of eyes demonstrated bow-tie topographic patterns, largely exhibiting with-the-rule astigmatism. However, assessment by keratometry or refraction highlighted against-the-rule more frequently; this may have implications for combined cataract and astigmatic surgery. The mean axial length was slightly shorter than expected for a group of predominantly European ethnic origin, although the mean refractive error was emmetropic.
Sonographic fetal biometric measurements on 6082 low-risk patients were compared in the second and third trimesters of pregnancy with respect to fetal race and gender. Ultrasonic measurements were obtained from fetuses of women participating in the Routine Antenatal Diagnostic Imaging with Ultrasound Study (RADIUS), who underwent both an early sonographic evaluation between 15 and 22 weeks' gestation and a later scan between 31 and 35 weeks' gestation. In the 16-21-week scans, male fetuses had significantly larger biparietal diameter measurements compared to female fetuses (estimated difference 0.852 mm, 95% CI 0.737-0.967). There was only minimal difference in biparietal diameter between Black and White fetuses. Femur length was similar in both female and male fetuses, but longer in Black compared to White fetuses (estimated difference 0.808 mm, 95% CI 0.539-1.078). During the 31-35-week scans, male fetuses continued to have larger biparietal diameter measurements compared to female fetuses (estimated difference 1.22 mm, 95% CI 1.04-1.40), and femur lengths were persistently longer in Black compared to White fetuses (estimated difference 0.563 mm, 95% CI 0.234-0.893). Further investigation is necessary to evaluate the effect of these slight differences in morphometric fetal measurements between races and genders, so that we can determine how best to use them for optimizing prenatal care.
OBJECTIVES: The aim of this study was to establish the biometric threshold of biparietal diameter (BPD), assumed to be an independent variable of gestational age, at which 100% accuracy in the assessment of fetal sex by ultrasonography is achievable. METHODS: Transvaginal and/or transabdominal sonography was used for detecting the 'sagittal sign' as a marker of fetal sex in 385 fetuses with BPD between 18 and 29 mm. The results of ultrasound examination were compared with sex at birth or with karyotype obtained from amniotic fluid cells or chorionic villus sampling. RESULTS: Fetal sex assignment was feasible in 337 of 385 cases (87.5%). Of the 312 fetuses with known fetal sex outcome, 164 were males and 148 were females. An accuracy rate of 100% was achieved when a BPD of > or = 23 mm was obtained. CONCLUSION: This study provides important information about the earliest stage of fetal development, expressed in terms of BPD, at which a diagnosis of fetal sex can be made with 100% accuracy.
During surgical exposure of the carpal tunnel it is possible to injure the neurovascular structures closely related to the flexor retinaculum, such as the superficial palmar arch and the communicating branch between the ulnar and median nerves. Because of the importance of these structures and with the purpose of increasing knowledge of anatomical details concerning to their location, a biometric study was performed on the retinaculum and the communicating branch, and between the communicating branch and the distal wrist crease, as well as between the retinaculum and the superficial palmar arch. We dissected 56 hands from 28 Brazilian formalin-preserved cadavers of both sexes (24 male) at the Federal University of São Paulo-Escola Paulista de Medicina, Brazil. The communicating branch was observed in 96.4% of cases and the superficial palmar arch in 78.6%. The communicating branch was found between the common palmar digital nerve of the 4th interosseous space (from the ulnar nerve) to the homonymous nerve of the 3rd interosseous space (from the median nerve). In males, the distance between the distal wrist crease and the site where the communicating branch originates from the ulnar component had an average of 33.9 +/- 5.5 mm on the right side and 30.2 +/- 8.2 mm on the left. The distance between the distal wrist crease and the junction of the communicating branch with the common palmar digital nerve of the 3rd interosseous space was 43.6 +/- 6.9 mm on the right and 40.2 +/- 6.2 mm on the left side. Conversely, in 14.8% of cases (1 female), the communicating branch was observed to emerge from the common palmar digital nerve of the 3rd interosseous space. The distance between the retinaculum and the superficial palmar arch in the axial line of the 4th metacarpal bone was on average 7.3 +/- 4.3 mm on the right and 8.3 +/- 3.5 mm on the left side. At the same level, the distance between the retinaculum and the communicating branch was 6.2 +/- 3.7 mm on the right side and 5.1 +/- 2.8 mm on the left. These results can be used as a reference during surgical procedures in the palmar region.
Methodology of clinical studies is highly sophisticated in drug research. But clinical trials are also necessary to demonstrate efficacy and safety of rehabilitation treatment. The call for evidence based medicine has also reached rehabilitation. However, in rehabilitation medicine it is much more difficult to design and conduct clinical trials with a high methodological standard. Among the reasons are: A comparable control group is necessary because spontaneous healing and unspecific measures contribute to therapeutic success, too. But what could "placebo rehabilitation" look like? The masking of therapies (blinded studies) will hardly ever be possible. Therefore, it is more difficult to achieve the same treatment and observation for the treatment and control group. Treatments in rehabilitation take longer to become effective than a drug and maybe the success will disappear after some time. Therefore, long-term trials and follow-ups are necessary. Such studies are expensive, need a strong organisation, and drop-outs are unavoidable. An appropriate outcome variable does not always exist. "Return to work" is an important, reliable and valid variable, but it delivers only one bit of information per patient. As a consequence, smaller progress in rehabilitation can only be demonstrated with large sample sizes. Outcome variables based on time enable studies with reasonable sample sizes. Sometimes it is more difficult to obtain acceptance of randomisation in rehabilitation patients than in acute patients. Some rehabilitation hospitals have only recently begun to take an interest in controlled clinical trials, hence are not so experienced. Nevertheless, controlled clinical trials delivering convincing results are possible in rehabilitation medicine as well. But biometrical consultation is necessary e.g. for study design, study conduction and evaluation. Most important points are the methodology of the study design and its practicability. Especially in these topics rehabilitation physicians and biometrician have to cooperate.