Age-specific Size Research Articles

Quantifying dysmorphologies of the neurocranium using artificial neural networks.

Craniosynostosis, a congenital condition characterized by the premature fusion of cranial sutures, necessitates objective methods for evaluating cranial morphology to enhance patient treatment. Current subjective assessments often lead to inconsistent outcomes. This study introduces a novel, quantitative approach to classify craniosynostosis and measure its severity. An artificial neural network was trained to classify normocephalic, trigonocephalic, and scaphocephalic head shapes based on a publicly available dataset of synthetic 3D head models. Each 3D model was converted into a low-dimensional shape representation based on the distribution of normal vectors, which served as the input for the neural network, ensuring complete patient anonymity and invariance to geometric size and orientation. Explainable AI methods were utilized to highlight significant features when making predictions. Additionally, the Feature Prominence (FP) score was introduced, a novel metric that captures the prominence of distinct shape characteristics associated with a given class. Its relationship with clinical severity scores was examined using the Spearman Rank Correlation Coefficient. The final model achieved excellent test accuracy in classifying the different cranial shapes from their low-dimensional representation. Attention maps indicated that the network's attention was predominantly directed toward the parietal and temporal regions, as well as toward the region signifying vertex depression in scaphocephaly. In trigonocephaly, features around the temples were most pronounced. The FP score showed a strong positive monotonic relationship with clinical severity scores in both scaphocephalic (ρ = 0.83, p < 0.001) and trigonocephalic (ρ = 0.64, p < 0.001) models. Visual assessments further confirmed that as FP values rose, phenotypic severity became increasingly evident. This study presents an innovative and accessible AI-based method for quantifying cranial shape that mitigates the need for adjustments due to age-specific size variations or differences in the spatial orientation of the 3D images, while ensuring complete patient privacy. The proposed FP score strongly correlates with clinical severity scores and has the potential to aid in clinical decision-making and facilitate multi-center collaborations. Future work will focus on validating the model with larger patient datasets and exploring the potential of the FP score for broader applications. The publicly available source code facilitates easy implementation, aiming to advance craniofacial care and research.

Implications for quantifying early life growth trajectories of term-born infants using INTERGROWTH-21st newborn size standards at birth in conjunction with World Health Organization child growth standards in the postnatal period.

The INTERGROWTH-21st sex and gestational age (GA) specific newborn size standards (IG-NS) are intended to complement the World Health Organization Child Growth Standards (WHO-GS), which are not GA-specific. We examined the implications of using IG-NS at birth and WHO-GS at postnatal ages in longitudinal epidemiologic studies. The aim of this study was to quantify the extent to which standardised measures of newborn size and growth are affected when using WHO-GS versus IG-NS at birth among term-born infants. Data from two prenatal trials in Bangladesh (n=755) and The Gambia (n=522) were used to estimate and compare size at birth and growth from birth to 3months when using WHO-GS only ('WHO-GS') versus IG-NS at birth and WHO-GS postnatally ('IG-NS'). Mean length-for-age (LAZ), weight-for-age (WAZ) and head circumference-for-age (HCAZ), and the prevalence of undernutrition (stunting: LAZ<-2SD; underweight: WAZ<-2SD; and microcephaly: HCAZ<-2SD) were estimated overall and by GA strata [early-term (370/7 -386/7 ), full-term (390/7 -406/7 ) and late-term (410/7 -430/7 )]. We used Bland-Altman plots to compare continuous indices and Kappa statistic to compare categorical indicators. At birth, mean LAZ, WAZ and HCAZ, and the prevalence of undernutrition were most similar among newborns between 39 and 40weeks of GA when using WHO-GS versus IG-NS. However, anthropometric indices were systematically lower among early-term infants and higher among late-term infants when using WHO-GS versus IG-NS. Early-term and late-term infants demonstrated relatively faster and slower growth, respectively, when using WHO-GS versus IG-NS, with the direction and magnitude of differences varying between anthropometric indices. Individual-level differences in attained size and growth, when using WHO-GS versus IG-NS, were greater than 0.2 SD in magnitude for >60% of infants across all anthropometric indices. Using IG-NS at birth with WHO-GS postnatally is acceptable for full-term infants but may give a misleading interpretation of growth trajectories among early- and late-term infants.

The price of curing cancer

BackgroundHealth care systems around the world struggle with high prices for new cancer drugs. The purpose of this study was to conduct a gedankenexperiment and calculate how much health expenditures would change if a cure for cancer through pharmaceutical treatment were made available. The cancer cure was conceived to eliminate both cancer deaths and the underlying morbidity burden of cancer. Furthermore, the cure was hypothesized to arrive in incremental steps but at infinitesimally small time intervals (resulting, effectively, in an immediate cure).MethodsThe analysis used secondary data and was conducted from the viewpoint of the German social health insurance. As its underlying method, it used a cause-elimination life-table approach. To account for the age distribution of the population, the study weighted age-specific increases in remaining life expectancy by age-specific population sizes. It considered drug acquisition costs as well as savings and life extension costs from eliminating cancer. All cancer drugs that underwent a mandatory early benefit assessment in Germany between 2011 and 2015/16 and were granted an added benefit were included. Data on age- and gender-specific probabilities of survival, population sizes, causes of death, and health expenditures, as well as data on cancer costs were taken from the German Federal Office of Statistics and the German Federal Social Insurance Office.ResultsBased on the cause-elimination life-table approach and accounting for the age structure of the German population, curing cancer in Germany yields an increase in average remaining life expectancy by 2.66 life years. Based on the current incremental cost-effectiveness ratio of new cancer drugs, which is on average €101,493 per life year gained (€39,751/0.39 life years), the German social health insurance would need to pay €280,497 per insuree to eliminate cancer. Dividing this figure by current average remaining lifetime health expenditures yields a ratio of 2.07, which represents a multiplier of current health expenditures.ConclusionsEliminating cancer at current price levels would more than triple total health expenditures in Germany. As the current price of a cure requires a drastic reduction of non-health consumption, it appears that current prices for cancer drugs already on the market (i.e., small steps towards a cure) need careful reconsideration.

Scaling the cricket pitch to fit junior players

ABSTRACT Studies in several sports have shown the benefits of adapting the playing environment to fit junior players. Frequently the changes are pragmatic choices based on space constraints or existing line markings, or the result of simple scaling based on stature. In this study, a method of scaling the cricket pitch length is presented which is based on the age-specific size and performance of the bowlers and batters. The objective was a pitch length which enabled young bowlers to bowl good length deliveries while releasing the ball at a more downward angle, similar to elite bowlers. The steeper release angle has the benefit of reducing the sensitivity of the ball flight distance to the variability of ball release. Based on data from county standard under-10 and under-11 players a pitch length of 16.22 yards (14.83 m) was calculated, 19% shorter than previously recommended for under-11s in England. A shorter pitch also increases the temporal challenge for batters, encouraging a wider variety of shots and improved anticipation skills. Pitch lengths scaled in this way to fit the players’ abilities as they develop will enable a more consistent ball release by bowlers and more consistent temporal demand for batters.

Sex-based trade-offs among growth, mortality, and maturation in Great Lakes yellow perch stocks

Trade-offs among growth, mortality, and reproduction form the basis of life history theory but may vary among populations owing to local ecological conditions. We examined life history trade-offs driving variation in maturation among 13 yellow perch (Perca flavescens) stocks in the Great Lakes using sex-specific age and length at 50% maturity (A50 and L50, respectively) and probabilistic maturation reaction norm midpoints (Lp50,a). Both sexes exhibited positive correlations between growth and mortality, and faster-growing stocks were mature at younger ages but larger sizes. Male and female A50 and L50 were positively correlated among stocks, but Lp50,a estimates were negatively correlated among stocks, indicating stocks that matured at large sizes for a given age in females matured at smaller age-specific sizes in males. Female Lp50,a estimates were negatively related to growth and mortality, while male Lp50,a estimates were positively related to growth. These results suggest that (i) sex-based life history trade-offs sometimes act to differentially structure maturation schedules in males and females and (ii) males may be less responsive to changes in mortality than females.

Body-size and growth-rate divergence among populations of threespine stickleback (Gasterosteus aculeatus) in Cook Inlet, Alaska, USA

Body size is one of the most perceptible traits of organisms and is an important fitness proxy in evolutionary studies. Oceanic threespine stickleback (Gasterosteus aculeatus L., 1758) have colonized and adapted to numerous freshwater habitats throughout the Holarctic since the most recent glacial retreat, giving us natural “replicates” of both convergent and divergent evolution. I observed considerable body-size variation among 22 threespine stickleback populations within a small region surrounding Cook Inlet, Alaska, USA. Larger bodied populations tended to have bimodal size-frequency distributions, whereas most smaller bodied populations had unimodal distributions. Bimodal distributions suggested the presence of at least two age classes within large-bodied populations. I used a Bayesian approach to infer mean size of presumed age-1 and age-2+ fish from bimodal size-frequency distributions; I found significant differences in size among populations within ages and sexes, suggesting significant divergence in growth rate among populations. I did not find significant correlations between growth rates (age-specific size) and geographic distances among populations, drainage affiliation, or distance to the sea. Thus, historical processes like isolation by distance, gene flow, or recent common ancestry did not explain differences in growth among populations, suggesting a role for local adaptation or phenotypic plasticity in size divergence.

Variation in growth of Damaraland mole-rats is explained by competition rather than by functional specialization for different tasks.

In some eusocial insect societies, adaptation to the division of labour results in multimodal size variation among workers. It has been suggested that variation in size and growth among non-breeders in naked and Damaraland mole-rats may similarly reflect functional divergence associated with different cooperative tasks. However, it is unclear whether individual growth rates are multimodally distributed (as would be expected if variation in growth is associated with specialization for different tasks) or whether variation in growth is unimodally distributed, and is related to differences in the social and physical environment (as would be predicted if there are individual differences in growth but no discrete differences in developmental pathways). Here, we show that growth trajectories of non-breeding Damaraland mole-rats vary widely, and that their distribution is unimodal, contrary to the suggestion that variation in growth is the result of differentiation into discrete castes. Though there is no evidence of discrete variation in growth, social factors appear to exert important effects on growth rates and age-specific size, which are both reduced in large social groups.

Non-random sampling for reproductive status induces bias in probabilistic maturation reaction norm midpoints

The midpoint of the probabilistic maturation reaction norm (PMRN), which is the age-specific size at which the probability of maturing is 50%, has been used as an index of age and size at maturation of fish populations. The most important data requirement for the PMRN method is random sampling for reproductive status (mature or immature) at each age or size class. When age at first maturation varies between sexes, randomness of sampling for reproductive status can be evaluated by the sex ratio at the age of first maturity of the precocious sex (i.e., if the sex ratio at the age of first maturity of the precocious sex [sex of which age at first maturation is younger than the other] is biased, the randomness of sampling for reproductive status is not ensured). We examined the effect of the randomness of sampling for reproductive status on PMRN midpoints of precocious males in 10 tributaries containing two salmonid species. The sex ratio (the proportion of males) of fish at the age of first maturity varied among tributaries. The PMRN midpoints for males decreased with an increase in the sex ratio in both species. The biased sex ratio was thought to be caused by different movement patterns of precocious mature males and immature males/females. Our results emphasize that non-random sampling for reproductive status greatly affects estimated PMRN midpoint values.

Duration of gestation, size at birth and later childhood behaviour

Although many previous studies have reported an association between preterm birth or small size at birth and later behaviour, multiple methodological limitations threaten the validity of causal inferences from reported associations. The authors have examined the association between gestational age and gestational age-specific size at birth (weight, length and head circumference) and behaviour in a large sample of children born healthy at term. The data were from the 6.5-year follow-up of 13,889 Belarusian children who participated in the Promotion of Breastfeeding Intervention Trial, a cluster-randomised trial of a breast-feeding promotion intervention. Child behaviour was measured using the parent and teacher versions of the Strengths and Difficulties Questionnaire (SDQ). Differences in SDQ scores by gestational age and by birthweight, birth length and birth head circumference standardised for gestational age and sex (z-scores) were analysed after controlling for potentially confounding maternal and family factors. There was no association between gestational age and child behaviour after adjusting for potential confounding factors. Lower birthweight-for-gestational age was associated with higher scores in problem behaviours including total difficulties, conduct problems, hyperactivity, emotional symptoms and peer problems. Similar but smaller differences were observed with birth length and birth head circumference, but those differences were attenuated with adjustment for birthweight. The patterns of association were consistent in both parent and teacher assessments. Among school-age children born at term within normal range of birthweight, fetal growth, but not gestational age, was associated with behavioural problem scores.

Age-Specific Size of the Upper Airway Structures in Children during Development

The purpose of this study was to establish the largest magnetic resonance imaging study so far, by including 292 cases in a prospective fashion, to investigate the normative values of the upper airway and surrounding tissues during development. We enrolled in the study 448 children who underwent cranial magnetic resonance imaging. We included 292 patients who had no sleep disorders or any associated symptom that could be related to breathing disorders. Using midsagittal and axial images, we evaluated the variations in size of the upper airway tissues. On images from the midsagittal plane, the normative values of the length and the thickness of the soft palate, the length and height of the tongue, the distance between the mental spine and the clivus, the thickness of the adenoid pad and the nasopharyngeal area, the adenoid pad oblique width, the soft palate oblique width, and the tongue oblique width were obtained for several age groups. Using images from the axial plane at the level of maximal tonsillar cross-sectional area, we measured the normative values of the mean tonsillar width and intertonsillar space. Magnetic resonance imaging is an excellent method of assessing upper airway structures. Knowledge of variations in size of the upper airway and surrounding tissues is essential in determining the significance of incidental findings in this area.

Age, Body Size, and Sexual Dimorphism in Size and Shape in Salamandrella keyserlingii (Caudata: Hynobiidae)

In organisms with determinate growth, sexual size dimorphism (SSD) occurs before maturity during the developmental process of growing apart, an ontogenetic perspective on the evolution of SSD. If the direction of SSD (female-larger SSD) is known, patterns of growth can be tested with one-tailed statistical distributions. In indeterminate growing organisms as well, does SSD occur before maturity? If it occurs, whether is females’ larger mean body size caused by a difference in age at maturity, age-specific size, divergent growth prior to maturity, or selection on post-maturational growth? How important is biphasic, sexual shape dimorphism (BSSD) for determinants of SSD? Biphasic characteristics are those that differ between adult aquatic- and terrestrial-phase morphs, and shape is size of a characteristic relative to body size. To address those questions, I determined age and body size based on a careful description of a growth trajectory for each sex in Salamandrella keyserlingii, using 555 independent data points from skeletochronological studies. Females reached maturity at 3–4 years of age, a year later than males that reached maturity at 2–3 years of age (mean body size: males = 57.63 mm, females = 61.70 mm; delayed sexual maturity resulted in SSD). However, SSD was highly detected before maturity (SSD index = 0.097), and females after maturity continued to grow and resulted in larger asymptotic size than males. Traits of BSSD were greater in males than in females. These results suggest that when determining SSD the difference in mean adult-body size results from the difference in age-specific size and the female-larger SSD develops to resolve intersexual ontogenetic conflict by allowing small-sized males to swell their whole body during the aquatic phase as much as large-sized females.

CT Scan Enumeration of Altered Spleen Status and Pulmonary Artery Size in Patients with Autoimmune Lymphoproliferative Syndrome (ALPS).

Abstract 4034Poster Board III-970 BackgroundALPS is a disorder of apoptosis resulting in elevated DNT (CD3+, TCRab+, CD4-, CD8-, B220+ double negative T lymphocyte) cells associated with childhood onset nonmalignant lymphadenopathy, splenomegaly and multilineage cytopenias due to splenic sequestration and autoimmune destruction. Patients with ALPS frequently have altered spleen status: splenomegaly or splenectomy, the latter often-related to refractory chronic AIHA and ITP. This altered spleen status has been associated with pulmonary arterial hypertension (PAH) in two patients with ALPS. Though traditionally diagnosed as elevated tricuspid regurgitant jet velocity > 2.6 m/sec, PAH can also be predicted using PA diameter, most commonly measured as the Main PA (MPA) diameter. Similar to Sickle Cell Disease patients who are evaluated for presence of PAH due to functional asplenia here we attempted to further elucidate the relationship between dilated pulmonary arteries (PA) and spleen status in ALPS patients. MethodsCT scans of 162 patients with ALPS were studied; their age range at the time of the study was 1-63yrs, median age 16yrs. The CT scans were obtained as part of the routine monitoring of their LPD. Patients' most recent complete chest, abdomen and pelvis CT scans were evaluated. In 97 patients spleen sizes in two scans done 1-12 years apart were also measured. Each scan was evaluated using Kodak Carestream PACS Version 10.1.sp1 software. Point of maximal distension was visually identified in the Main, Left, and Right PA. Artery diameters were measured perpendicular to the vessel wall. Measurement of spleen length consisted of summing the distance between the axial slice in which the spleen first appears to the slice where it appears last. Digital Image Processing (IP) measurements are also underway to compute spleen and liver volumes in these patients. Evaluation CriteriaSplenomegaly was defined as a CT estimated spleen length of > 9.76 cm. PA diameter was considered above the upper limits of normal if adults if MPA measured > 28.6 mm LPA > 22.1 mm; RPA> 19.8 mm. For children age specific sizes were adapted from published reports. Results and conclusionIn our cohort of 162 ALPS patients, 51% had splenomegaly, 42% had undergone splenectomy due to hypersplenism prior to CT scan evaluations and 7% had normal size spleens. 26% of them demonstrated dilated MPA. However, contingency table analysis yielded a P value = 0.436 (P < 0.05) evaluating an association between splenic abnormalities and dilated MPA. ANOVA analysis of an association between MPA diameter and broad patient classifications of normal spleen, splenectomy, and splenomegaly yielded P = .02 (α < 0.05) and non-significant Tukey HSD statistical tests, the odds ratio = 0.93 for an association between spleen length and MPA diameter. Correlation R2 = 0 between age, spleen length and MPA diameter, though this was only evaluated in 42 patients 17 years and older. Serial measurements of enlarged spleens in the 97 children and adults with at least 2 CT scans done at a median time of 4 yrs apart (range 1-12yrs) showed no further significant increase in spleen size with age. For most patients, their ALPS associated lymphoproliferative burden appears to be worse during early childhood and as they grow older it may become self-limited and stable. Further work is in progress to correlate changes in PA diameter with changes in spleen length, spleen volumes and age. There was no statistical correlation between MPA diameter and altered spleen status, though a quarter of these patients demonstrated dilated pulmonary arteries. Active surveillance for PAH by periodic echocardiograms is underway in these patients. Disclosures:No relevant conflicts of interest to declare.

Evolutionary genetics of ageing in the wild: empirical patterns and future perspectives

Summary 1 Classical evolutionary theory states that senescence should arise as a consequence of the declining force of selection late in life. Although the quantitative genetic predictions of hypotheses derived from this theory have been extensively tested in laboratory studies of invertebrate systems, relatively little is known about the genetics of ageing in the wild. 2 Data from long-term ecological studies is increasingly allowing quantitative genetic approaches to be used in studies of senescence in free-living populations of vertebrates. We review work to date and argue that the patterns are broadly consistent with theoretical predictions, although there is also a clear need for more empirical work. 3 We argue that further advances in this field of research might be facilitated by increased use of reaction norm models, and a decreased emphasis on attempting to discriminate between mutation accumulation and antagonistic pleiotropy models of senescence. We also suggest a framework for the better integration of environmental and genetic effects on ageing. 4 Finally, we discuss some of the difficulties in applying quantitative genetic models to studies of senescence outside the laboratory. In particular we highlight the problems that viability selection can cause for an accurate estimation of parameters used in the prediction of age-trajectory evolution.

Quantitative genetics of growth and cryptic evolution of body size in an island population

While evolution occurs when selection acts on a heritable trait, empirical studies of natural systems have frequently reported phenotypic stasis under these conditions. We performed quantitative genetic analyses of weight and hindleg length in a free-living population of Soay sheep (Ovis aries) to test whether genetic constraints can explain previously reported stasis in body size despite evidence for strong positive directional selection. Genetic, maternal and environmental covariance structures were estimated across ontogeny using random regression animal models. Heritability increased with age for weight and hindleg length, though both measures of size were highly heritable across ontogeny. Genetic correlations among ages were generally strong and uniformly positive, and the covariance structures were also highly integrated across ontogeny. Consequently, we found no constraint to the evolution of larger size itself. Rather we expect size at all ages to increase in response to positive selection acting at any age. Consistent with expectation, predicted breeding values for age-specific size traits have increased over a twenty-year period, while maternal performance for offspring size has declined. Re-examination of the phenotypic data confirmed that sheep are not getting larger, but also showed that there are significant negative trends in size at all ages. The genetic evolution is therefore cryptic, with the response to selection presumably being masked at the phenotypic level by a plastic response to changing environmental conditions. Density-dependence, coupled with systematically increasing population size, may contribute to declining body size but is insufficient to completely explain it. Our results demonstrate that an increased understanding of the genetic basis of quantitative traits, and of how plasticity and microevolution can occur simultaneously, is necessary for developing predictive models of phenotypic change in nature.

Parameters of Household Composition as Demographic Measures

Cross-sectional data, such as Census statistics, enable the re-enactment of household lifecourse through the construction of the household composition matrix, a tabulation of persons in households by their age and bythe age of their corresponding household-heads. Household lifecourse is represented in the household composition matrix somewhat analogously to survivorship in a life-table in demography. A measure of household lifecourse is the average household size, specific to age of household-head. Associated with the age-specific household size is the age-interval 0–4, which yields average number of children present in households, also by age of head. Trajectories of re-enacted household lifecourses for Phoenix and for the State ofArizona are depicted here to track the gamma probability density function. Through this relationship also the association between household size, children per household, and fertility emerges. To the extent that housing conditions or tenure impact average household size, or other aspects of household composition, fertility in particular is discerned as a housing- related demographic attribute of households. Household size and headship ratio, both specific to age of head, are here shown to be analytically related to the household composition matrix, their product yielding the age-specific headship coefficient. As a measure incorporating parameters of households and dwellers, thus also characterizingoccupied dwellingunits, the headshipcoefficient emerges as a demographic indicator of housing in a community.

Age-Specific Household Size as a Demographic Aspect of Regional Disparity: Czech Republic, 1991

The post-communist transition to market economy in Central Europe over the last decade of the twentieth century had a significant impact on the demographic profile of the former Soviet bloc countries. Largely due to government policy and market conditions related to housing, this observation is particularly true for the Czech Republic. The present study shows housing as a facet of regional demographic differences within the Czech Republic. The household composition matrix is applied here as a demographic gauge to the behavioral response of households to Czech housing markets and policy. The matrix provides here a glance at households’ demographic behavior in the capital city of Prague and in the country’s other regions, during the early transition period, based on observations from the 1991 census. A summary feature of household composition is the age-specific household size shown for the various regions of the Czech Republic to trace the reduced standard Gamma function. Anomalies detected in the trajectory of age-specific household size for Prague confirm the unique housing market conditions in the capital city, and point to a commensurate demographic response in Prague as opposed to the rest of the country.

Testing hypotheses of aging in long-lived painted turtles ( Chrysemys picta)

For 38 of the past 50 years, Painted Turtles were studied on the University of Michigan's E.S. George Reserve in southeastern Michigan. We compared age specific body sizes, reproductive traits and survival of Painted Turtles ranging from 9 to 61 years of age to test contrasting predictions of the Relative Reproductive Rate and Senescence Hypotheses of aging. Indeterminate growth (i.e. continued body growth of adults) was important in increasing reproductive output of older turtles; however, growth rate of the oldest age-group was reduced compared to that of younger adults. Although clutch size and among year reproductive frequency did not increase with age, within year reproductive frequency (production of second clutches), egg size, and hatchling size did. Nest predation rates and the proportion of surviving nests that produced hatchlings were similar among age groups, and embryo mortality in nests was not related to age. Survivorship of males was less than that of females, and survivorship of the oldest group of females was not statistically different from that of a younger group of females. No decline in reproductive output or survivorship was detected in the oldest females as predicted by the Senescence Hypothesis. Thus, the majority of data on reproductive traits and survivorship support the Relative Reproductive Rate Hypothesis. We also compared Painted Turtles to Blanding's Turtles, another species studied on the E.S. George Reserve. That Painted Turtles exhibit indeterminate growth whereas Blanding's Turtles do not, appears to be a primary mechanism for some differences between species in the relationships between reproductive traits and age. An important mechanism for increasing reproductive output in both species was increased reproductive frequency in older females. Painted Turtles also increased offspring quality (egg and hatchling size) with age, whereas Blanding's Turtles did not. Compared to younger individuals, there was no reduction in survivorship in the oldest Painted Turtles and survivorship increased in the oldest Blanding's Turtles.

Commentary

Commentary

Age-specific size of the normal adenoid pad on magnetic resonance imaging.

Conclusions regarding the significance and appearance of the adenoids incidentally noted on magnetic resonance (MR) scans of the brain largely rely on observations of previously published plain film data. In order to determine the age specific appearance of normal adenoid tissue as measured on sagittal T1-weighted midline MR images, we evaluated 189 patients without a history or clinical evidence of adenoid disease, who were sequentially referred for an MR scan of the brain. The thickness of the adenoid pad was measured to the nearest 1 mm along a line through the pharyngeal tubercle constructed perpendicular to the anterior clival surface. Patients were grouped according to age. Normal subjects demonstrated an age specific variation in the size of the pad with the maximal size being attained in early childhood and then steadily decreasing in later childhood and adulthood (P = 0.0001). The adenoids were largest in the 7-10 years age group (mean, 14.59 mm) and steadily declined to 4.83 mm by 60 years of age. Previous surgery had no effect on adenoid measurement (P = 0.582). Magnetic resonance scans provide an excellent method for assessing the adenoid pad.

Origin of the large burbot (Lota lota (L.)) caught in an Arctic ice-fishing competition: a case study

Recreational ice-fishing and ice-fishing competitions are popular in Finland. In recent years the prizes have become increasingly valuable. One such competition is held yearly at Lake Kilpisjarvi. During the 1998 ice-fishing competition, two participants brought two large burbot (Lota lota (L.)) to the officials for weighing. These two burbot were much larger than the rest of the fish caught. The origin of these two burbot was questioned and subsequently studied by comparing their age-specific size, stomach contents and parasite fauna with those of the smaller burbot caught during the competition. Both the age-specific lengths and weights of the suspected burbot were higher than those of the smaller burbot, and the stomach analysis revealed that the large burbot had eaten roach (Rutilus rutilus (L.)), which are not found in Lake Kilpisjarvi. Moreover, the parasite fauna in these two burbot was not typical of the lake. It was therefore concluded that the suspect burbot could not have been caught in Lake Kilpisjarvi, and the contestants were disqualified.