Account In Statistical Analysis Research Articles

An individual based, multidimensional approach to identify emotional reactivity profiles in inbred mice

BackgroundDespite extensive environmental standardization and the use of genetically and microbiologically defined mice of similar age and sex, individuals of the same mouse inbred strain commonly differ in quantitative traits. This is a major issue as it affects the quality of experimental results. Standard analysis practices summarize numerical data by means and associated measures of dispersion, while individual values are ignored. Perhaps taking individual values into account in statistical analysis may improve the quality of results. New methodThe present study re-inspected existing data on emotional reactivity profiles in 125 BALB/cJ and 129 mice, which displayed contrasting patterns of habituation and sensitization when repeatedly exposed to a novel environment (modified Hole Board). Behaviors were re-analyzed on an individual level, using a multivariate approach, in order to explore whether this yielded new information regarding subtypes of response, and their expression between and within strains. ResultsClustering individual mice across multiple behavioral dimensions identified two response profiles: a habituation and a sensitization cluster. Comparison with existing method(s)These retrospect analyses identified habituation and sensitization profiles that were similar to those observed in the original data but also yielded new information such as a more pronounced sensitization response. Also, it allowed for the identification of individuals that deviated from the predominant response profile within a strain. ConclusionsThe present approach allows for the behavioral characterization of experimental animals on an individual level and as such provides a valuable contribution to existing approaches that take individual variation into account in statistical analysis.

Association between dietary inflammatory index and bone density in lactating women at 6\u2009months postpartum: a longitudinal study

BackgroundChronic inflammation contributes to the risk of osteoporosis and fracture. Dietary Inflammatory Index (DII), a novel method appraising the inflammatory potential of diet, has been utilized to examine the association between diet and bone health among postmenopausal women or the elderly. However, its relationship with bone density (BD) in lactating women has not been studied.MethodsThe prospective study was conducted to assess the possible association between DII and maternal BD during lactation. We enrolled 150 lactating women in the cohort. Participants were measured ultrasonic BD as baseline values at 1 month postpartum. After five-month follow up, the participants’ BD were measured again. DII scores were calculated from semi-quantitative food frequency questionnaires (FFQ) and divided into tertiles. We compared the differences in the changes of BD at 6 months postpartum without or with adjustment for potential covariates across the tertiles.ResultsThe women in Q1 of DII scores had less bone mass loss than those in Q2 and Q3 without adjustment for any covariates (p < 0.01); after adjusting demographic characteristics such as BMI (kg/m2) at 6 months postpartum, educational level, metabolic equivalent (MET), daily energy intake (kcal/d), we found that participants in the highest tertile of DII scores had much more bone loss than those in the lowest tertile (p = 0.038). However, in the test for trend, no significant association between DII and the changes of maternal BD at 6 months postpartum was observed.ConclusionsChinese lactating women with higher DII scores have more bone mass loss; however significant differences and trends are attenuated and/or disappear depending on covariates and confounders that are taken into account in statistical analysis. The further study should be conducted in larger population to explore whether the significant association between DII and BD exists in Chinese lactating women.

Effect of heart rate on shooting performance in elite archers

AimThe aim of the present study was to examine the effect of heart rate on shooting performance in elite archers. MethodsRegularly trained 13 (7 female, 6 male) international level elite archers performed a (specific) protocol twice with 3 days interval in an indoor area. In order to raise the heart rate (HR) and related physiological stress the archers performed 4 sets of steady pace shuttle runs (males 10 km h-1; females 8 km h-1) for 3 minutes in a 20 m course following with 1 minute stop during which they performed 3 shots to 18 meter distance indoor target, and followed by 1 minute rest, where blood sample was collected from ear lobe for blood lactate (BL) analysis. Heart rate monitors were used for heart rate (HR) recordings with 5 seconds intervals for resting, running, shooting, and recovery periods. The score of the shots were recorded as in the normal archery indoor competition. Average (overall) results were taken into account for statistical analysis. ResultsMean HR and BL during resting shoot in 1st and 2nd tests were 119.0 and 112.2 bpm (range 1st test: 101–142 bpm, 2nd test: 96–135 bpm) and 1.72 and 1.65 mmol.L−1 (range 1st test: 0.9–2.6 mmol.L−1, 2nd test: 0.8–2.3 mmol.L−1) respectively. Mean HR and BL during post exercise shooting in 1st and 2nd tests were 168 and 166 bpm (range 1st test: 152–191 bpm, 2nd test: 147–188 bpm) and 4.21 and 3.44 mmol.L−1 (range 1st test: 1.3–7.0 mmol.L−1, 2nd test: 1.3–5.7 mmol.L−1) respectively. There was not any statistically difference between shooting scores (27.50–27.23 points) after running exercise and resting (p > 0.05). ConclusionIt was concluded that, under simulated indoor competition environment, high HR values do not influence short distance shooting scores.

Application of a Frailty Modeling Approach to Correlated Breastfeeding Duration Data.

Correlated breastfeeding duration data are very common in infant feeding research using cohort designs. Intracluster correlation within the same clustering group is expected and needs to be taken into account in statistical analysis; otherwise, the corresponding statistical inferences may be subject to an increased Type I error. The aims of this study were to illustrate the necessity of adjusting for the intracluster correlation in correlated breastfeeding duration data analysis and to demonstrate different frailty modeling approaches. An introduction to shared frailty models was presented under the assumption of proportional hazards (PH). Then, two different approaches-the Cox frailty model (semiparametric approach) and the parametric frailty model (parametric approach)-were used to fit the data from a maternal cohort in Nepal as an illustrative example. For the semiparametric approach, random effects denoting the variations in the hazard of breastfeeding cessation shared by mothers living in the 27 distinct communities were estimated and graphically presented. Compared with the conventional Cox model, Cox frailty model reduced the chance of Type I error occurring, providing a better model fit in the presence of correlated survival data. Among candidate parametric approaches, a Weibull PH model with a gamma frailty term was selected as an appropriate model fitting the breastfeeding data. Shared frailty models can be used in other research areas in the presence of correlated time-to-event data. Model selection depends on the assumption of PH, the specification of the baseline hazard function, and also the study purpose.

Intracranial Pressure Changes During Intrahospital Transports of Neurocritically Ill Patients.

Intrahospital transport is associated with a high rate of complications. Investigations of this problem using neuromonitoring remain scarce. This is a monocentric, prospective observational study. Patients with severe brain diseases and intracranial pressure (ICP) monitoring were included. Continuous monitoring of ICP, cerebral perfusion pressure (CPP), oxygen saturation (SpO2), heart rate, and mean arterial pressure was measured during seven different periods of intrahospital transport (baseline for 30min, I=preparation, II=transport I, III=CT scan, IV=transport II, V=postprocessing, and follow-up for another 30min). All complications were documented. Between July 2013 and December 2013, a total number of 56 intrahospital transports of 43 patients were performed from ICU to CT. Data recording was incomplete in six cases. Fifty transports have been taken into account for statistical analysis. Forty-two percent were emergency transports. Mean duration of the procedure was 17' (preparation), 6' (transport I), 9' (CT scan), 6' (transport II), and 15' (postprocessing), respectively. Mean ICP at baseline was 8.53mmHg. Comparing all periods of intrahospital transport and the follow-up period to the baseline showed a significant increase of ICP only during CT scan (15.83mmHg, p<0.01), not during the transport to and from the radiology department. An overall complication rate of 36% (n=18) was observed. In 26% (n=13), additional ICP therapy was necessary due to an elevation of ICP above 20mmHg. There is a considerable rate of complications during intrahospital transport of critically ill patients with severe brain diseases, with a significant increase of ICP during transport and CT scan. In one-fifth of all patients, additional therapy was necessary. From our point of view, transport of critically ill patients should only be performed by trained staff and under monitoring of ICP and CPP.

High Prevalence of Giardia duodenalis Assemblage B Infection and Association with Underweight in Rwandan Children

Background Giardia duodenalis is highly endemic in East Africa but its effects on child health, particularly of submicroscopic infections, i.e., those below the threshold of microscopy, and of genetic subgroups (assemblages), are not well understood. We aimed at addressing these questions and at examining epidemiological characteristics of G. duodenalis in southern highland Rwanda.Methodology/Principal FindingsIn 583 children <5 years of age from communities and health facilities, intestinal parasites were assessed by triplicate light microscopy and by PCR assays, and G. duodenalis assemblages were genotyped. Cluster effects of villages were taken into account in statistical analysis. The prevalence of G. duodenalis as detected by microscopy was 19.8% but 60.1% including PCR results. Prevalence differed with residence, increased with age, and was reduced by breastfeeding. In 492 community children without, with submicroscopic and with microscopic infection, underweight (weight-for-age z-score <−2 standard deviations) was observed in 19.7%, 22.1%, and 33.1%, respectively, and clinically assessed severe malnutrition in 4.5%, 9.5%, and 16.7%. Multivariate analysis identified microscopically detectable G. duodenalis infection as an independent predictor of underweight and clinically assessed severe malnutrition. Submicroscopic infection showed respective trends. Overall, G. duodenalis was not associated with gastrointestinal symptoms but assemblages A parasites (proportion, 13%) were increased among children with vomiting and abdominal pain.Conclusions/SignificanceThe prevalence of G. duodenalis in high-endemicity areas may be greatly underestimated by light microscopy, particularly when only single stool samples are analysed. Children with submicroscopic infections show limited overt manifestation, but constitute unrecognized reservoirs of transmission. The predominance of assemblage B in Rwanda may be involved in the seemingly unimposing manifestation of G. duodenalis infection. However, the association with impaired child growth points to its actual relevance. Longitudinal studies considering abundant submicroscopic infections are needed to clarify the actual contribution of G. duodenalis to morbidity in areas of high endemicity.

Rozwój ślimaka u niemowląt ze zmianami w obrębie ośrodkowego układu nerwowego powstałymi w następstwie asfiksji okołoporodowej

Asphyxia in neonates with inadequate blood-inner ear barrier function causes damage to the inner ear included the degeneration of outer hair cells of the organ of Corti and oedematous changes in stria vascularis. The major consequences in the central nervous system (CNS) are found to be hypoxic-ischemic encephalopathy (HIE) in term newborns, peri- (PVH) or intraventricular hemorrhages (IVH) and periventricular leucomalacia (PVL) in preterm neonates. was to carry out the objective assessment of the cochlea development using CEOAEs in infants with CNS impairment occurring as an effect of perinatal asphyxia, imaged during trans-fontanel ultrasonography. To the investigation 36 infants with HIE, IVH or PVL were included, the control group encompassed 32 born at term, health children. In all children three times otoscopic examination and CEOAEs recordings were performed: after birth, in 3rd and in 6th month of life using Otodynamics Otoacoustic Analyser ILO-88 in Quick Screen version. Perinatal anamnesis, general pediatric status, results of trans-fontanel ultrasonography and biochemical test results were taken into account in statistical analyses. The mean amplitudes of CEOAEs in the first days of life were significantly reduced in InvG comparing to control babies. In half-octave frequency bandwidth analysis significant reduction of S/N Ratio at 1,5–4 kHz in InvG was observed. 3 and 6 months later the recorded responses significantly increased, they didn’t reach values of CG but no statistical differences between groups were observed. In conclusion, the outer hair cells activity in first days of life is reduced in newborns with CNS impairment and perinatal asphyxia in anamnesis comparing to health children. The maturation of the cochlea is intensive during first 3 months of life, later only subtle changes in CEOAEs are observed.

Assessment of hearing organ activity in a group of neonates with central nervous system impairment

ObjectiveHypoxic-ischemic encephalopathy, primary subarachnoid hemorrhage in term newborns as well as periventricular leukomalacia and intraventricular hemorrhage in premature newborns are the major consequences of perinatal asphyxia. Intrauterine hypoxia and labor prolongation can also affect the hearing organ in newborns causing reversible or irreversible changes in the cochlea, brainstem or cortex.The aim of the study was to carry out the objective assessment of the cochlea and hearing pathway activity using CEOAEs and ABR; to find relationships between hearing status and parameters effecting on nervous system in neonates with central nervous system impairment occurring following perinatal asphyxia. MethodsTo the investigation 36 newborns with hypoxic-ischemic encephalopathy, periventricular leukomalacia or intraventricular hemorrhage were included. The control group encompassed 32 health newborns matched as to the age. In all newborns otoscopic examination, CEOAEs after birth and CEOAEs with ABR 3months later were performed. Perinatal anamnesis, general pediatric status, results of trans-fontanel ultrasonography and biochemical test results were taken into account in statistical analyses. ResultsThe mean amplitudes of CEOAEs in the first days of life were significantly reduced in investigation group comparing to control babies. 3months later the recorded responses significantly increased but did not reach values of control group. No differences were found between latencies of waves I and II. ABR latencies of waves III, IV, V and interpeak latencies I–III, III–V, I–V were delayed in investigation group when compared to control patients. Also morphology of ABR recordings in investigation group has slightly changed. Perinatal aspyxia leading to hypercapnia, low gestational age, prolonged artificial ventilation and meningitis were the main risk factors related to disturbances in ABR recordings. ConclusionsThe combined use of CEOAEs and ABR in neonates with central nervous system impairment involvement revealed the existence of abnormalities in cochlear micromechanics and retrocochlear auditory pathway. Etiology seems to be multifactoral.

Nonparametric Rank Regression for Analyzing Water Quality Concentration Data with Multiple Detection Limits

Environmental data usually include measurements, such as water quality data, which fall below detection limits, because of limitations of the instruments or of certain analytical methods used. The fact that some responses are not detected needs to be properly taken into account in statistical analysis of such data. However, it is well-known that it is challenging to analyze a data set with detection limits, and we often have to rely on the traditional parametric methods or simple imputation methods. Distributional assumptions can lead to biased inference and justification of distributions is often not possible when the data are correlated and there is a large proportion of data below detection limits. The extent of bias is usually unknown. To draw valid conclusions and hence provide useful advice for environmental management authorities, it is essential to develop and apply an appropriate statistical methodology. This paper proposes rank-based procedures for analyzing non-normally distributed data collected at different sites over a period of time in the presence of multiple detection limits. To take account of temporal correlations within each site, we propose an optimal linear combination of estimating functions and apply the induced smoothing method to reduce the computational burden. Finally, we apply the proposed method to the water quality data collected at Susquehanna River Basin in United States of America, which clearly demonstrates the advantages of the rank regression models.

Simulated Cataract and Low Contrast Stimuli Impair Cognitive Performance in Older Adults: Implications for Neuropsychological Assessment and Everyday Function

ABSTRACT Objective: To investigate how age-related declines in vision (particularly contrast sensitivity), simulated using cataract-goggles and low-contrast stimuli, influence the accuracy and speed of cognitive test performance in older adults. An additional aim was to investigate whether declines in vision differentially affect secondary more than primary memory. Method: Using a fully within-subjects design, 50 older drivers aged 66–87 years completed two tests of cognitive performance – letter matching (perceptual speed) and symbol recall (short-term memory) – under different viewing conditions that degraded visual input (low-contrast stimuli, cataract-goggles, and low-contrast stimuli combined with cataract-goggles, compared with normal viewing). However, presentation time was also manipulated for letter matching. Visual function, as measured using standard charts, was taken into account in statistical analyses. Results: Accuracy and speed for cognitive tasks were significantly impaired when visual input was degraded. Furthermore, cognitive performance was positively associated with contrast sensitivity. Presentation time did not influence cognitive performance, and visual gradation did not differentially influence primary and secondary memory. Conclusion: Age-related declines in visual function can impact on the accuracy and speed of cognitive performance, and therefore the cognitive abilities of older adults may be underestimated in neuropsychological testing. It is thus critical that visual function be assessed prior to testing, and that stimuli be adapted to older adults' sensory capabilities (e.g., by maximising stimuli contrast).

Enns: The French Nutrition &amp; Health Survey-Blood Lead Levels in the French Adult Population

ISEE-0374 Background and Objectives: The French Nutrition & Health Survey (ENNS) was carried out by the French Institute for Public Health Surveillance in 2006-2007. The main objectives were to explore food consumption and levels of various biomarkers in the general population. The aim of the present study was to assess blood lead levels (BLL) in the French adult population. Methods: ENNS is a cross-sectional study in the general population. Participants (18 to 74 years of age) were sampled using a three-stage probability design stratified by geographical areas and degrees of urbanization. Data on individual characteristics, eating habits, occupational and environmental exposure were collected through interviews and self-administered questionnaires. Blood samples were collected and analysed using standardized procedures. Sample weights and complex sample design were taken into account in statistical analyses to produce unbiased and representative estimates. Results: The blood lead geometric mean in the French population was 25.7 μg/L [CI95: 24.9-26.5]. The overall prevalence of elevated BLL (>100 μg/L) was 1.6% [CI95: 1.1%-2.1%]. The median was 25 μg/L and the 95th percentile was 73 μg/L. Comparison with results from previous studies show that the geometric mean of BLL (in male young adults) dropped by 50% in 10 years. In 2006, levels were significantly higher (P < 0.0001) for males than for females, and increased (P < 0.0001) with age, tobacco or alcohol consumption. Others factors associated with BLL were identified including leisure activities, socio-professional status, age of housing, birth country and shellfish consumption. Conclusion: The findings from the ENNS-lead study demonstrate that BLL in the French population has declined during recent years, and is still influenced by age, sex, smoking habits, and alcohol consumption. The distribution of BLL in France was quite similar to that observed in other European countries (Germany and Czech Republic).

Carcass conformation and cut composition of Creole goat from Guadeloupe

Carcass data base of 164 Creole male goats was used in order to provide factual data on the carcass conformation. Standardised procedures of carcass measuring and cutting were followed. The European official grid of light lamb is implemented for meat goat in the French West Indies and included five levels. Weights of carcass, cuts and tissues, quality scores and linear measurements were analysed. Feeding system, age at slaughter and weight were taken into account for statistical analysis. There were significant differences among carcass conformation classes (CC) for many traits except for the fat score, leg length and compactness ratio (carcass width on length): 2.2, 34.5 cm and 0.30 on average, respectively. The values of chilled carcass weight and yield and the carcass linear measurements steadily increased until conformation class 4 or 5: 6.7 to 11.2 kg, 49% to 55% and 52.4 to 58.0 cm carcass length. For the weights of carcass cuts, significant differences appeared between two groups: classes 1 and 2 vs. classes 3, 4 and 5. Regardless of the carcass weight, the distribution of prime cuts remained similar. The indices calculated on a weight basis (kg/cm), either for the carcass or the leg, increased significantly (P<0.01): with 54% and 63% difference between the two extreme classes, respectively. The muscle, bone and fat proportions in the shoulder did not vary between CC with 0.72, 0.22 and 0.06, respectively. Corresponding traits in leg were 0.74, 0.23 and 0.03; the last two were different (P<0.05) from class 1 to class 5. The muscle/bone ratios calculated either in shoulder or in leg ranged from 3.1 to 3.6 (P>0.05).

Propranolol therapy alters estimation of potential cardiovascular risk derived from submaximal postinfarction exercise testing

We studied the effect of propranolol administration on risk assessment based on submaximal exercise testing performed early after myocardial infarction. A total of 70 patients with recent infarction underwent modified Bruce treadmill testing with simultaneous measurement of expired gases in the absence of antianginal agents including β-antagonists. Among these, 31 patients who had at least one of the following abnormalities—ST depression ⩾ 1 mm (22 patients), chest pain (four patients), or treadmill time < 360 seconds (12 patients)—were studied in a randomized double-blind fashion and received either placebo or 240 mg of propranolol/day. A total of 28 patients completed the randomized phase and were able to undergo repeat exercise testing an average of 3.4 ± 1.8 days later. Randomized groups were equivalent at baseline except for a higher peak oxygen consumption and carbon dioxide production ( p < 0.05) in the propranolol compared with the placebo group; these differences were taken into account in statistical analyses of the study data. Resting heart rate (59 ± 1.2 versus 82 ± 4.2 beats/min) and peak heart rate X systolic blood pressure (14,208 ± 496 versus 20,075 ± 1,062) were both significantly less ( p < 0.01) after propranolol than after placebo. Eight of nine patients treated with placebo maintained ST depression ⩾ 1 mm from the initial to the randomized exercise test, compared with only 4 of 13 receiving propranolol ( p < 0.01). In those with continued ST depression, time to positivity was significantly longer in those receiving propranolol compared with those taking placebo (538 ± 73 versus 318 ± 44 seconds, p < 0.05). In contrast, the peak ratio between carbon dioxide production and oxygen consumption was higher in those receiving propranolol compared with those receiving placebo (0.93 ± 0.04 versus 0.81 ± 0.03, p < 0.05). We conclude that propranolol therapy reduces evidence of ischemia and changes traditional estimates of potential cardiac risk derived from submaximal postinfarction exercise testing.