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PubMed1997

Variation among rheumatologists in clinical outcomes and frequency of office visits for rheumatoid arthritis.

OBJECTIVE: To estimate the variation among rheumatologists in clinical outcomes and frequency of office visits for patients with rheumatoid arthritis (RA), after accounting for patient demographic and clinical characteristics and treatments prescribed. METHODS: Multiple regression analysis using random effects for rheumatologists and adjustments for patient characteristics and treatments received, based on data derived from a panel study of persons with RA. RESULTS: During the years 1984-1993, rheumatologists accounted for a moderate amount of the total variation in clinical outcomes and nearly one-third of the total variation in frequency of office visits. For example, in 1993 rheumatologist associated variation in 4 clinical outcomes ranged from 16 to 25%, while the variation in office visit frequency attributable to rheumatologists stood at 46% of the total variation. However, rheumatologist associated variation in clinical outcomes was not statistically significant in any year, while variation in office visits was highly significant in all years (p < or = 0.0001). Although there was an increase in the percentage of variation attributable to rheumatologists for all outcomes examined across the years of this study, the time trend reached statistical significance only for frequency of office visits (2.4% per year; p = 0.0135) and functional status (1.6% per year; p = 0.0034). CONCLUSION: The magnitude and strength of rheumatologist associated variation in frequency of office visits, without comparable strength in the variation in clinical outcomes, may suggest inefficiencies in the use of resources for the care of persons with RA. Further work is needed to directly examine the relationship between health outcomes and resource utilization.

Adult↗

PubMed1997

Computerised analysis of foetal heart rate variation: prediction of adverse perinatal outcome in patients undergoing prostaglandin induction of labour at term.

The aim of this study was to determine the value of antenatal numerical assessment of foetal heart rate variation in the prediction of adverse perinatal outcome in patients undergoing prostaglandin induction of labour at term. Two hundred and seven patients who underwent prostaglandin cervical ripening after 37 weeks gestation for the indications of pregnancy-induced hypertension, foetal growth retardation or post-dates pregnancy were included in this study. Prior to commencement of cervical ripening, a 30-minute cardiotocography tracing was recorded on the System 8000 machine and the long-term and short-term variations were calculated. Forty-three patients (20.8%) had a long-term variation of less than 30 ms; 9 (4.3%) had a short-term variation of less than 3 ms. The sensitivity and positive predictive values of long-term variation in the prediction of admission to neonatal special care unit were 25.6% and 23.2%, respectively. Corresponding values for short-term variation were 2.6% and 11.1%, respectively. The sensitivity and positive predictive values of long-term variation in the prediction of caesarean section for foetal distress were 33.3% and 9.3%, respectively. Corresponding values for short-term variation were 8.3% and 11.1%, respectively. Long-term and short-term variations appeared to be both poor predictors of adverse perinatal outcome. However, of 4 foetuses with both reduced antenatal heart rate variation and who were subsequently delivered by caesarean section for foetal distress in labour, all 4 were admitted to neonatal special care unit (NSCU). Foetuses with intrapartum evidence of foetal distress were more likely to be admitted to NSCU when antenatal foetal heart rate variation was reduced.

Adult↗

PubMed2006

Molecular genetics of berry colour variation in table grape.

The genetics and biochemistry of anthocyanins and flavonol biosynthesis and their role in plant organ pigmentation is well established in model species. However, the genetic basis of colour variation is species specific and understanding this variation is very relevant in many fruit and flower crop species. Among grape cultivars, there is a wide genetic variation for berry colour ranging from yellow-green ("white" cultivars) to dark blue berries. Berry colour results from the synthesis and accumulation of anthocyanins in the berry skin, which in plants is commonly regulated by transcription factors belonging to the MYB and bHLH families. In this work, we aimed to identify the major genetic determinants of berry colour variation in a large collection of table grape cultivars and somatic variants. The genetic analyses of berry colour in a few grape segregating progenies had previously identified a single locus on linkage group 2 responsible for colour variation. Furthermore, somatic variation for berry skin colour in cultivar Italia had been associated with the presence of a Gret1 retrotransposon in the promoter region of VvmybA1, a Myb gene whose expression is associated to skin colouration. The results show that VvmybA1 is the gene underlying the mapped locus controlling berry colour in grape. Additionally, the molecular analyses indicate that genetic and somatic berry colour variation can be associated to molecular variation at VvmybA1 in more than 95% of the analyzed cultivars. Thus, VvmybA1 is a major determinant of berry colour variation in table grape and its instability is the major cause of somatic variation for this trait.

Anthocyanins↗

PubMed2000

Genetic variance in temperature dependent adult size deriving from physiological genetic variation at temperature boundaries.

An increase in genetic variation in body size has often been observed under stress; an increase in dominance variance and interaction variance as well as in additive genetic variance has been reported. The increase in genetic variation must be caused by physiological mechanisms that are specific to adverse environments. A model is proposed to explain the occurrence of an increase in genetic variation in body size in Drosophila at extreme temperatures. The model has parameters specific to the low- and high-temperature regions of the viable range. Additive genetic variation in the boundary temperatures leads to a marked increase in additive genetic variation in development rate and body size at extreme temperatures. Additive genetic variation in the temperature sensitivity in the low- and high-temperature regions adds non-additive genetic variation. Development rate shows patterns in additive genetic variation that differ from the patterns of genetic variation in body size; therefore, the genetic correlation between development rate and body size changes sign repeatedly as a function of temperature. The existence of dominance in the genetic variation in the boundary temperatures or in the low- and high-temperature sensitivities leads to a higher total genetic variance due to higher dominance and interaction variance, for both development rate and body size.

Animals↗

PubMed2006

Neutral and adaptive variation in gene expression.

Variation among populations in gene expression should be related to the accumulation of random-neutral changes and evolution by natural selection. The following evolutionary analysis has general applicability to biological and medical science because it accounts for genetic relatedness and identifies patterns of expression variation that are affected by natural selection. To identify genes evolving by natural selection, we allocate the maximum among-population variation to genetic distance and then examine the remaining variation relative to a hypothesized important ecological parameter (temperature). These analyses measure the expression of metabolic genes in common-gardened populations of the fish Fundulus heteroclitus whose habitat is distributed along a steep thermal gradient. Although much of the variation in gene expression fits a null model of neutral drift, the variation in expression for 22% of the genes that regress with habitat temperature was far greater than could be accounted for by genetic distance alone. The most parsimonious explanation for among-population variation for these genes is evolution by natural selection. In addition, many metabolic genes have patterns of variation incongruent with neutral evolution: They have too much or too little variation. These patterns of biological variation in expression may reflect important physiological or ecological functions.

Animals↗

PubMed1994

Evolutionary inferences from DNA variation at the 6-phosphogluconate dehydrogenase locus in natural populations of drosophila: selection and geographic differentiation.

Several allozyme-coding genes in Drosophila melanogaster show patterns suggesting that polymorphisms at these loci are targets of balancing selection. An important question is whether these genes have similar distributions of underlying DNA sequence variation which would indicate similar evolutionary processes occurring in this class of loci. One such locus, 6-phosphogluconate dehydrogenase (Pgd), has previously been shown to exhibit clinal variation for Fast/Slow electromorph variation in the United States and Australia, unusually large electromorph frequency differences between the United States and Africa, and other patterns indicative of selection. We measured four-cutter DNA restriction site and allozyme variation at Pgd among 142 D. melanogaster X chromosomes collected from several geographic regions including North Carolina, California, and Zimbabwe (Africa). We also sequenced a representative sample of 13 D. melanogaster Pgd genes collected in North Carolina and a single copy of Pgd from the sibling species, Drosophila simulans. While some population genetic models predict excess DNA polymorphism in genes which are targets of balancing selection, the D. melanogaster samples from the United States had significantly reduced levels of DNA polymorphism and extraordinarily high levels of linkage disequilibrium, providing evidence of hitchhiking effects of advantageous mutants at Pgd or at linked sites. Therefore, while selection has probably influenced the distribution of DNA variation at Pgd, the precise nature of these selective events remains obscure. Since the Pgd region appears to have low rates of crossing over, the reduced level of variation at this locus supports the idea that recombination rates are important determinants of levels of DNA polymorphism in natural populations. Furthermore, while patterns of allozyme variation are very similar at Pgd and Adh, the DNA data show that the evolutionary histories of these genes are dramatically different. We observed extensive differences in the amount and distribution of variation in D. melanogaster Pgd samples from the United States and Zimbabwe which cannot be explained by differential selection on the Fast/Slow polymorphism in these two geographic regions. Thus, genetic drift among partially isolated populations has also been an important factor in determining the distribution of variation at Pgd in D. melanogaster. Finally, we assayed four-cutter variation at Pgd in a sample of 19 D. simulans X chromosomes and observed reduced levels of DNA variability and high levels of linkage disequilibrium. These patterns are consistent with predictions of some hitchhiking models.

Animals↗

PubMed1984

Antigenic variation of bloodstage malaria parasites.

An antigen on the surface of erythrocytes infected with mature asexual malaria parasites has been shown to undergo antigenic variation in two malaria species. Plasmodium falciparum-infected erythrocytes from squirrel monkeys express a new antigen that is identified by reactivity with antibody from infected animals in an indirect immunofluorescence assay. Cloned P. knowlesi parasites in rhesus monkeys undergo antigenic variation of an erythrocyte surface antigen as defined by antibody-mediated cell agglutination (the SICA test) and indirect immunofluorescence. This variant antigen is a malarial protein that changes both in size (Mr 185 000-225 000) and antigenicity in cloned parasites derived by antigenic variation in vivo. Antigenic variation on the erythrocyte surface probably contributes to the capacity of malaria parasites to establish chronic infections with multiple recrudescences and to the finding that individuals can be repeatedly reinfected. The fundamental reasons for expression of these highly immunogenic antigens on the erythrocyte membrane remain obscure. Other major questions remain to be explored: the repertoire of variant antigens; the genetic basis of antigenic variation and the structural basis for the antigenic uniqueness of each variant antigen. Some properties of malarial antigenic variation indicate that control of antigenic variation in plasmodia will be quite different to antigenic variation in the African trypanosomes. The host spleen is required both for variant antigen expression and antigenic variation, and variant-specific antibody appears to induce antigenic variation rather than select pre-existing variants.

Animals↗

PubMed2005

Role of FRIGIDA and FLOWERING LOCUS C in determining variation in flowering time of Arabidopsis.

Arabidopsis (Arabidopsis thaliana) accessions provide an excellent resource to dissect the molecular basis of adaptation. We have selected 192 Arabidopsis accessions collected to represent worldwide and local variation and analyzed two adaptively important traits, flowering time and vernalization response. There was huge variation in the flowering habit of the different accessions, with no simple relationship to latitude of collection site and considerable diversity occurring within local regions. We explored the contribution to this variation from the two genes FRIGIDA (FRI) and FLOWERING LOCUS C (FLC), previously shown to be important determinants in natural variation of flowering time. A correlation of FLC expression with flowering time and vernalization was observed, but it was not as strong as anticipated due to many late-flowering/vernalization-requiring accessions being associated with low FLC expression and early-flowering accessions with high FLC expression. Sequence analysis of FRI revealed which accessions were likely to carry functional alleles, and, from comparison of flowering time with allelic type, we estimate that approximately 70% of flowering time variation can be accounted for by allelic variation of FRI. The maintenance and propagation of 20 independent nonfunctional FRI haplotypes suggest that the loss-of-function mutations can confer a strong selective advantage. Accessions with a common FRI haplotype were, in some cases, associated with very different FLC levels and wide variation in flowering time, suggesting additional variation at FLC itself or other genes regulating FLC. These data reveal how useful these Arabidopsis accessions will be in dissecting the complex molecular variation that has led to the adaptive phenotypic variation in flowering time.

Amino Acid Sequence↗

PubMed1999

Interobserver and intraobserver variations in sonographic measurement of thyroid volume in children.

OBJECTIVE: To determine the interobserver and intraobserver variations in sonographic measurement of thyroid volume in children. DESIGN: Thyroid volumes of 30 healthy children were measured by three separate observers. Additionally each observer measured thyroid volumes of ten separate children three times. METHODS: The data were used to assess intraobserver and interobserver variations in measurement of thyroid volume. Interobserver and intraobserver variations in measuring each diameter of the thyroid gland were also determined. The effect of thyroid size on interobserver and intraobserver variations was analyzed. RESULTS: Intraobserver variation in measurement of thyroid volume was 8.4+/-6.7% (mean+/-s. d.). Interobserver variation was 13.3+/-8.2%. The widest interobserver variation was encountered in determining the craniocaudal diameter of the thyroid gland. No correlation was found between thyroid volume and interobserver variation (r=-0.12, P=0.27), whereas a slight but statistically significant correlation was found between thyroid volume and intraobserver variation (r=-0.26, P=0.012). CONCLUSION: Significant interobserver and intraobserver variation occurs in sonographic measurement of thyroid volume in children.

Adolescent↗

PubMed2000

Observer variation in the diagnosis of thyroid disorders. Criteria for and impact on diagnostic decision-making.

The thesis is concerned with the reliability of thyroid diagnostic modalities. When no "true" diagnosis was available the reliability could not be evaluated by assessing the accuracy; in these cases the reproducibility was evaluated. This was done by evaluating the observer variation: comparison of observers' evaluation in pairs was assessed. The observer variation was expressed by the kappa coefficient, which adjusts to the amount of agreement that can be expected to occur by chance alone. Clinical estimation only of thyroid functional status was subject to considerable observer variation. Likewise clinical estimation the thyroid gland (size and morphology) was subject to considerable observer variation, and the observer variation was greatest concerning the palpation of a solitary thyroid nodule where even experienced doctors had difficulties in reproducing their own evaluations. In contrast high reproducibility was found concerning the interpretation of routine thyroid blood tests. Thyroid scintigram is not suitable for thyroid size estimation. Assessment of thyroid morphology (diffuse, multinodular, solitary hot or cold lesion) based on scintigram alone seldom resulted in acceptable reproducibility: four doctors diagnosed a solitary cold lesion in 100 of 480 scintigrams, however, they only agreed in 30 of the cases. A solitary cold lesion may in a few per cent of the cases imply malignancy and will therefore lead to further investigations. The reproducibility was not improved when the doctors had additional access to patient history and clinical examination as well as the scintigram. Ultrasound is increasingly often regarded as the "true" diagnosis in the morphological description of the thyroid gland. In a study of two specialists in thyroid ultrasound these descriptions were, however, found not to be reproducible. Thus ultrasound should be applied with caution as the golden standard with regard to thyroid type. It has been demonstrated that thyroid imaging is subject to considerable observer variation. This has great implications when thyroid imaging is used as the golden standard, for example when patients are selected for scientific studies. Furthermore, this may influence the comparison of different studies because of inconsistency of the material included. Therefore the observer variation should appear from description of material and methods in scientific studies. Palpation of thyroid size is neither accurate nor reproducible if an exact volume is aimed at. A rough division into small, medium, and large goitres is reproducible and rather accurate and may therefore be applied. In a prospective randomised study it was demonstrated that this division could replace ultrasound estimation of thyroid size in the calculation of 131I dose in the treatment of hyperthyroidism. Evaluation of thyroid functional status cannot be based on patient history and clinical examination alone, it should include thyroid blood tests. Exact estimation of thyroid size should be performed by means of ultrasound. When morphology of the thyroid is assessed the observer variation should be kept in mind. The existence of observer variation implies uncertainty concerning patient material and inclusion criteria in scientific studies. It may complicate comparison of scientific results. In thyroid diagnostic decision-making doctors should keep in mind that even though there is agreement concerning thyroid blood tests there is not agreement concerning thyroid imaging and the clinical evaluation of patients suspected of thyroid disorders. The patients may experience these disagreements even if the same doctor follows them. Doctors are obliged to use the existing modalities and should be aware of not only problems with technology but also variations originating from the observers, the doctors themselves--the human factor.

Humans↗

PubMed2002

Variation in female mate choice within guppy populations: population divergence, multiple ornaments and the maintenance of polymorphism.

The evolutionary significance of variation in mate choice behaviour is currently a subject of some debate and considerable empirical study. Here, I review recent work on variation within and among guppy (Poecilia reticulata) populations in female mate choice and mating preferences. Empirical results demonstrate that there is substantial variation within and among populations in female responsiveness and choosiness, and much of this variation is genetic. Evidence for variation in preference functions also exists, but this appears to be more equivocal and the relative importance of genetic variation is less clear cut. In the second half of this review I discuss the potential significance of this variation to three important evolutionary issues: the presence of multiple male ornaments, the maintenance of polymorphism and divergence in mate recognition among populations. Studies of genetic variation in mate choice within populations indicate that females have complex, multivariate preferences that are able to evolve independently to some extent. These findings suggest that the presence of multiple male ornaments may be due to multiple female mating preferences. The extreme polymorphism in male guppy colour patterns demands explanation, yet no single satisfactory explanation has yet emerged. I review several old ideas and a few new ones in order to identify the most promising potential explanations for future empirical testing. Among these are negative frequency dependent selection, environmental heterogeneity coupled with gene flow, and genetic constraints. Last, I review the relative extent of within and among-population variation in mate choice and mating preferences in order to assess why guppies have not speciated despite a history of isolation and divergence. I argue that variation within guppy populations in mate choice and enhanced mating success of new immigrants to a pool are major impediments to population divergence of the magnitude that would be required for speciation to occur.

Animals↗

PubMed2005

Assessing the potential for an ongoing arms race within and between the sexes: selection and heritable variation.

In promiscuous species, sexual selection generates two opposing male traits: offense (acquiring new mates and supplanting stored sperm) and defense (enforcing fidelity on one's mates and preventing sperm displacement when this fails). Coevolution between these traits requires both additive genetic variation and associated natural selection. Previous work with Drosophila melanogaster found autosomal genetic variation for these traits among inbred lines from a mixture of populations, but only nonheritable genetic variation was found within a single outbred population. These results do not support ongoing antagonistic coevolution between offense and defense, nor between either of these male traits and female reproductive characters. Here we use a new method (hemiclonal analysis) to study genomewide genetic variation in a large outbred laboratory population of D. melanogaster. Hemiclonal analysis estimates the additive genetic variation among random, genomewide haplotypes taken from a large, outbred, locally adapted laboratory population and determines the direction of the selection gradient on this variation. In contrast to earlier studies, we found low but biologically significant heritable variation for defensive and offensive offspring production as well as all their components (P1, fidelity, P2, and remating). Genetic correlations between these traits were substantially different from those reported for inbred lines. A positive genetic correlation was found between defense and offense, demonstrating that some shared genes influence both traits. In addition to this common variation, evidence for unique genetic variation for each trait was also found, supporting an ongoing coevolutionary arms race between defense and offense. Reproductive conflict between males can strongly influence female fitness. Correspondingly, we found genetic variation in both defense and offense that affected female fitness. No evidence was found for intersexual conflict in the context of male defense, but we found substantial intersexual conflict in the context of male offensive sperm competitive ability. These results indicate that conflict between competing males also promotes an associated arms race between the sexes.

Analysis of Variance↗

PubMed1991

[Observer variation in clinical practice. A review].

Observer variation denotes the discrepancy between two consecutive observations of the same indicant. Principles and results of observer variation studies are outlined. Observer variation seems to be present wherever it is searched for, in history taking as well as in physical examination. It has been found unanimously to be smaller for intra- than for inter- observer variation while it is still controversial whether clinical experience lessens observer variation. Even fundamental clinical observations and particularly evaluations of borderline cases between normal and abnormal exhibit observer variation. The possibilities of reducing observer variation, and the importance of observer variation to clinicians and patients, and also the influence on research and society are referred to briefly. The future role of observer variation studies is discussed. Observer variation often is evaluated by the Kappa statistics whose statistical advantages and clinical disadvantages are outlined.

Observer Variation↗

PubMed1997

Age, genetic, and nongenetic factors influencing variation in serum sex steroids and zonal volumes of the prostate and benign prostatic hyperplasia in twins.

BACKGROUND: We have observed that hereditary and environmental factors have a substantial influence on the plasma content of sex steroids in normal male twins and in men of families with prostatic disease. METHODS: The contribution of genetic and nongenetic familial factors on the variation of plasma sex steroid concentrations and of the volume of zones of the prostate measured by transrectal ultrasound (TRUS) has now been investigated in pairs of male monozygotic (MZ) and dizygotic (DZ) twin pairs between age 25-75 years. Bioelectric impedance permitted quantitation of body fat, lean body mass, and water. Morphometrics and testicular volume were also determined. RESULTS: The intraclass correlation (rI) was > 0.40 for the variation of the total volume (TV), the transition zone (TZ), the peripheral zone (PZ), and the ratio of TZ/PZ in both MZ and DZ twins, and heredity affected 22% of the variation of the PZ and TZ and 30% of the ratio of TZ/PZ. None of the TV and environmental factors influenced the remainder of the variation. Heredity accounted for 25% or more of the variation of dihydrotestosterone (DHT), and the ratios of DHT/testosterone (T), estradiol (E2)/T, androstanediol glucuronide, sex hormone-binding globulin (SHBG)-bound T, T/SHBG, luteinizing hormone (LH), follicle-stimulating hormone (FSH), and dehydroepiandrosterone sulfate (DHEA-S). In MZ twin pairs the variation of the volumes of the prostate became greater with age. In contrast, the variation of the sex hormone concentrations did not show greater variation with age. Heredity also affected > 30% of the variation for waist measurement, weight, body fat, body mass, water and lean body mass, body mass/fat, and testicular size. CONCLUSIONS: Our results indicated that both MZ and DZ twin pairs had zonal prostate volumes more like their twin pair than like unrelated twins. However, nongenetic factors exerted stronger influences than genetic factors on zonal volumes of the prostate. In contrast, hereditary factors had stronger influences on determining the variation of many sex hormones and morphometric characteristics than did nongenetic factors.

Adult↗

PubMed2004

Patterns of tooth crown size and shape variation in great apes and humans and species recognition in the hominid fossil record.

It has been suggested that patterns of craniodental variation in living hominids (Gorilla, Homo, Pan, and Pongo) may be useful for evaluating variation in fossil hominid assemblages. Using this approach, a fossil sample exhibiting a pattern of variation that deviates from one shared among living taxa would be regarded as taxonomically heterogeneous. Here we examine patterns of tooth crown size and shape variation in great apes and humans to determine 1) if these taxa share a pattern of dental variation, and 2) if such a pattern can reliably discriminate between samples that contain single species and those that contain multiple species. We use parametric and nonparametric correlation methods to establish the degree of pattern similarity among taxa, and randomization tests to assess their statistical significance. The results of this study show that extant hominids do not share a pattern of dental size variation, and thus these taxa cannot be used to generate expectations for patterns of size variation in fossil hominid species. The hominines (Gorilla, Homo, and Pan) do share a pattern of shape variation in the mandibular dentition; however, Pongo is distinct, and thus it is unclear which, if either, pattern should be expected in fossil hominids. Moreover, in this case, most combined-species samples exhibit patterns of shape variation that are similar to those for single hominine species samples. Thus, although a common pattern of shape variation is present in the mandibular dentition, it is not useful for recognizing taxonomically mixed paleontological samples.

Animals↗

PubMed2002

Variation within and between birds in corticosterone responses of great tits (Parus major).

The present study investigated inter- and intraindividual variation of the stress response (in terms of plasma levels of corticosterone) to handling in birds. Individual captive great tits (Parus major) were exposed to a standardised capture and handling protocol three times at about 2-week intervals. Mean plasma corticosterone levels were low (<5 ng/ml) when the birds were first sampled and increased in all birds 10 min after handling (mean levels on each sampling occasion 14 to 22 ng/ml). Levels in some birds then continued to increase, whereas in other birds levels remained relatively constant or had declined 30 min after handling began. Corticosterone responses were measured three times in each bird so that variation in plasma corticosterone levels could be defined. The area under the corticosterone response curve was defined as the integrated corticosterone response and was calculated for each response curve. Variation between birds was quantified by comparing mean values of corticosterone levels and integrated corticosterone responses between birds, then calculating a coefficient of variation for the mean of the individual bird means for each corticosterone parameter. Variation within birds was quantified by calculating the mean of the coefficients of variation for each bird for each corticosterone parameter. Variation in corticosterone levels in the first blood samples at 0 min (coefficient of variation (CV) 84.0%) was greater than variation in peak levels at 10 min (CV 35.1%) and in integrated corticosterone responses (CV 31.9%), indicating that corticosterone responses were more consistent between birds than were basal corticosterone levels. This study has demonstrated that corticosterone responses to a stressor tend to be repeatable in individual great tits, and has provided a method for quantifying variation in corticosterone responses for comparison with other birds in the future.

Corticosterone↗

PubMed2002

Anatomic variations of the paranasal sinus area in pediatric patients with chronic sinusitis.

Endoscopic endonasal surgery has been performed in children. Therefore, we need to know the precise anatomy and anatomic variations of the lateral nasal wall. This is important in order to achieve better surgical results and avoid complications. We also need to know the relationship between the anatomic variations and sinonasal disease. For the purpose of this study we assessed the anatomic variations of the lateral nasal wall and the association of these variations with chronic sinusitis in children. Forty-seven children with chronic sinus disease were included in the study. There were 25 female and 22 male patients with ages ranging from 2 to 16 years (mean 10.5+/-3.8 years). On coronal and axial computed tomographic (CT) scans, the anatomic variations of the lateral nasal wall and sinusitis were assessed. A pneumatized middle concha (MC) was the most common anatomic variation, followed by pneumatization of the superior concha (SC), Haller cell and agger nasi cell. Secondary MC, large ethmoidal bulla, maxillary sinus hypoplasia, Onodi cell, and uncinate process pneumatization were relatively rare. Maxillary sinusitis was the most common sinus infection, followed by ethmoidal, sphenoidal and frontal sinusitis in that order. There was no significant relationship between the sinusitis and anatomic variations except for some minor associations. In conclusion, anatomic variations in the lateral nasal wall are common in children. Local, systemic or environmental factors appear to be more important in pediatric sinusitis than the anatomic variations. Due to the absence of a definitive relationship between the anatomic variations and sinus disease, aggressive surgical interventions should be avoided while performing endonasal endoscopic surgery in the children.

Adolescent↗

PubMed1993

Analysis of variation in prostate-specific antigen values.

This retrospective study analyzes variation in prostate-specific antigen (PSA) levels in 129 males who were not diagnosed with prostate cancer or other known malignancies. The extent to which the assay and the biologic variation contributed to the variation in PSA concentration was evaluated from analysis of slopes characterizing PSA concentration as a function of time. The mean coefficient of variation on observations was 58.0 percent. The estimated mean biologic coefficient of variation was 55.3 percent versus a mean assay coefficient of variation of 13.2 percent, indicating that the assay variation contributed negligibly to variation compared with the biologic variation. The concept that a PSA level which rises more than that attributable to assay variation indicates the need for invasive testing for prostate cancer is questionable. A decreasing PSA level was seen as often and of the same magnitude as an increasing level within a relatively narrow window of approximately one year. We are aware of no reason why this variability in PSA values would not be observed in patients with occult prostate cancer.

Aged↗