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Longitudinal analysis of circulating tumor DNA and CA19-9 dynamics in predicting disease relapse and monitoring treatment response in stage I-III pancreatic ductal adenocarcinoma: An interim analysis of a prospective observational study.

INTRODUCTION: Postoperative recurrence is the leading cause of mortality in resected pancreatic ductal adenocarcinoma (PDAC), yet reliable tools for early relapse detection and treatment response assessment remain lacking. METHODS: In a prospective cohort of 136 patients with resected stage I-III PDAC receiving adjuvant chemotherapy, we evaluated circulating tumor DNA (ctDNA) and CA19-9 as longitudinal biomarkers across multiple postoperative time windows. RESULTS: ctDNA consistently outperformed CA19-9 as an independent prognostic factor; ctDNA positivity at on-treatment and surveillance assessments achieved a positive predictive value of 91.7%, while persistent negativity identified the lowest-risk patients. Integrating CA19-9 with ctDNA resolved the ctDNA-alone gap in distinguishing treatment clearance from conversion, improving discrimination of responders from non-responders (HR 3.72; P = .008). A time-weighted dynamic ctDNA risk score (MinerVa-dynamic) further stratified ctDNA-negative patients into clinically distinct prognostic subgroups, achieving an area under the curve of 0.87 and 0.82 for one- and two-year disease-free survival prediction, respectively. CONCLUSIONS: These findings support a dual-biomarker longitudinal monitoring framework as a practical, individualized approach to postoperative surveillance and early therapeutic decision-making in PDAC.

CA19-9

Longitudinal effects of elexacaftor/tezacaftor/ivacaftor on the oropharyngeal metagenome in adolescents with cystic fibrosis.

BACKGROUND: Triple modulator therapy elexacaftor/tezacaftor/ivacaftor (ETI) improves lung function and impacts upon the respiratory microbiome in people with Cystic fibrosis (pwCF) with advanced lung disease. However, adolescents with cystic fibrosis (CF) are less colonized with bacterial pathogens than adult pwCF but their microbiota already differs from healthy individuals. The aim of this study was to longitudinally analyze the impact of ETI on the respiratory metagenome in adolescents with predominantly mild CF lung disease. METHODS: In this prospective observational study, we included pwCF aged 12-20 years with at least one F508del mutation, who collected oropharyngeal swabs before and after initiation of ETI therapy twice per week to biweekly over three months. We performed whole metagenome shotgun sequencing, followed by host DNA filtering and taxonomic profiling. We used linear and additive mixed effects models adjusted for known confounders and corrected for multiple testing to study longitudinal development of the microbiome. We analyzed bacterial diversity, abundance, and strain-level phylogeny. RESULTS: We analyzed the metagenomic data of 297 swabs of 20 pwCF. Microbiome composition changed after initiation of ETI therapy. We observed a slight diversification of the microbiome over time (Inv Simpson, Coef 0.085, 95 %CI 0.003, 0.17, p = 0.04). Strain-level analysis and clustering showed that strain retention of the most frequent bacterial species is predominant even during ETI therapy. CONCLUSIONS: During three months of ETI therapy, commensal bacteria increased, which may help to prevent overgrowth of bacterial pathogens.

Humans

Autistic-like traits and longitudinal changes in health-related quality of life among individuals with bipolar disorder: A 12-month study.

OBJECTIVE: Autistic-like traits are common in bipolar disorder (BD) and have been linked to poor functional outcomes, yet their longitudinal impact on quality of life (QOL) remains unclear. This study examined whether autistic-like traits are associated with 12-month changes in health-related QOL in BD. METHODS: Seventy-eight outpatients with BD who completed 12-month follow-up assessments were included (mean age = 34.9 years). Autistic-like traits were assessed using the Social Responsiveness Scale for Adults (SRS-A), with participants classified into elevated- and non-elevated-traits groups. Depressive and manic symptoms were evaluated using the 17-item Hamilton Depression Rating Scale (HAMD-17) and the Young Mania Rating Scale (YMRS). QOL was measured using the 36-Item Short-Form Health Survey (SF-36). Linear mixed models were used to examine longitudinal changes. RESULTS: HAMD-17 scores demonstrated significant main effects of time and group, reflecting overall improvement but persistently higher depressive symptoms in the elevated-traits group. YMRS scores indicated a significant group effect only. Physical QOL remained stable, while mental QOL improved over time without group differences. Role/social QOL showed significant main effects of time and group, with consistently lower scores in the elevated-traits group. No group × time interactions emerged, suggesting similar rates of change between groups. CONCLUSIONS: This prospective study suggests that autistic-like traits in BD are associated with persistently poorer role/social functioning over time rather than differences in recovery trajectories. Assessing autistic-like traits may help identify patients at risk of poorer functioning and guide tailored psychosocial interventions.

Autistic-like traits

Lineage dynamics of invasive Escherichia coli isolates in the Netherlands from 1975 to 2021: a retrospective longitudinal genomic analysis.

BACKGROUND: Escherichia coli is a common cause of invasive infections such as bloodstream and cerebrospinal fluid infections in neonates. Strains positive for the K1 capsule are considered the most common cause of such neonatal invasive infections. This assumption of K1 dominance, and indeed the population genomics of E coli causing invasive infections in general is largely unstudied. We aimed to provide a comprehensive characterisation of this pathogen population using a longitudinal isolate collection. METHODS: In this analysis we report the findings of the SENTINEL study, a longitudinal genomic analysis of 1790 invasive E coli isolates collected mainly from newborns in the Netherlands between 1975 and 2021 by the Netherlands Reference Laboratory for Bacterial Meningitis, Amsterdam University Medical Centre, Amsterdam, Netherlands. The dataset included all bacterial strains cultured from cerebrospinal fluid or blood in cases of (clinical) bacterial meningitis (1976 to 1980). In 1981 the criteria were expanded to include neonates (aged ≤4 weeks) with E coli sepsis, and from July, 2016 all infants younger than 1 year with E coli sepsis were included. All isolates were sequenced using either the HiSeq 2500 or HiSeq 4000 platforms (Illumina, San Diego, CA, USA). We confirmed species and identified sequence types (STs), detected antimicrobial resistance genes, virulence genes, and the presence of K1 capsule, and characterised the dynamics of these factors over time. FINDINGS: Our data show a highly dynamic bacterial population that is entirely unaffected by antimicrobial resistance determinants. Key pathogen population fluctuations include the complete disappearance of the dominant lineage ST567 and the swapping of dominant ST95 clones from a single serotype O18:H7 clone to two distinct serotype O1:H7 clones, with changes in virulence factors including major fimbrial adhesins. These findings, combined with only 58·8% (1053 of 1790) prevalence in K1-expressing isolates in the entire study population, point to host-pathogen interaction and immune selection pressures as key drivers of bacterial population dynamics in this largely antimicrobial-naive population. INTERPRETATION: Our data show the vital need for ongoing genomic surveillance of microbial pathogen populations to guide appropriate intervention strategies. Additionally, genomic insights of a pathogen population from one specific disease syndrome or patient population cannot always be generalised across other cohorts. FUNDING: Wellcome Antimicrobial and Antimicrobial Resistance Doctoral Training Programme and the National Institute for Health and Care Research Birmingham Biomedical Research Centre.

Netherlands

Multidimensional GWAS analyses on longitudinal phenotypes reveal candidate genes regulating multi-stage egg production traits in Wannan yellow chicken.

Egg production performance directly determines the economic viability of indigenous chicken breeding. However, the genetic regulation of multi-stage egg production traits remains difficult to characterize due to their complex and dynamic nature. Here, we integrated a multidimensional GWAS framework, including single-trait GWAS, multi-trait GWAS (MTAG), and longitudinal trajectory-based GWAS (TrajGWAS), to identify stage-specific and shared genetic effects underlying egg production traits in Wannan yellow chickens (WNY). Whole-genome sequencing of 354 WNY hens (10× depth) and quality control yielded 14,253,816 SNPs for analysis. Selective sweep analyses comparing red jungle fowl, commercial layers, and WNY identified a genomic region containing IGF1 under significant selection pressure. Single-trait GWAS identified SNPs 4_57990480 (BMPR1B) and 17_370912 (LOC112531479) associated with egg production across three laying stages (21-30, 31-40, and 21-40 weeks). MTAG further identified loci 8_4336468 (FASLG) and 21_654726 (CHD5) with shared effects across the laying period, whereas TrajGWAS revealed longitudinal associations involving PRKG1 and identified dynamic loci associated with clutch traits, including GRID1. For clutch traits, stage-specific loci were detected for average clutch size (ACS) and maximum clutch size (MCS), including SNP 8_8542036 at 21-30 weeks, PROK1 at 31-40 weeks, and CUL5, ALKBH8 across the entire laying period. These results demonstrate that integrating complementary GWAS strategies improves the resolution of genetic architecture underlying egg production traits by capturing trait-specific, shared, and stage-dependent genetic effects. The identified GWAS loci and selective-sweep candidate regions provide insights into the genetic architecture of egg production traits and breed differentiation.

Egg production

A longitudinal single-cell and spatial multiomic atlas of pediatric high-grade glioma.

Pediatric high-grade glioma (pHGG) is an incurable central nervous system malignancy that is a leading cause of pediatric cancer death. While pHGG shares many similarities with adult glioma, it comprises distinct disease entities. In this study, we longitudinally profile a molecularly diverse cohort of 16 pHGG patients through single-nucleus RNA and ATAC sequencing, whole-genome sequencing, and CODEX spatial proteomics to capture the evolution of neoplastic and microenvironmental features during disease progression and treatment. We define a set of core pHGG neoplastic cell states and observe differential tumor-myeloid interactions between malignant cell phenotypes. We find that essential neuromodulators and the interferon response are upregulated post-therapy, implicating them as malignant cell-intrinsic targets. We observe an increase in oligodendrocytes upon progression and that they coordinate spatial motifs with proneural tumor cells. This multiomic atlas of longitudinal pHGG captures features of therapy response and provides a scalable reference for the study of pediatric brain tumors.

Humans

The Chatham Blood Pressure Study. An application of Bayesian growth curve models to a longitudinal study of blood pressure in children.

Recent developments in statistics have produced powerful methods that facilitate the analysis of longitudinal studies. These methods are illustrated by an analysis of a longitudinal study of blood pressure in children. The results of the study show a clear tendency for blood pressure to increase with age, and Asian children tend to have lower blood pressures than their Caucasian counterparts of the same age. There is evidence to support the hypothesis that blood pressures track.

Age Factors

Osteoarthritis of the hand: longitudinal studies.

Evaluation of the osteoarthritic grades of the hands of 478 participants of the ongoing Baltimore Longitudinal Study suggests that: 1) Joint degeneration due to osteoarthritis is a relatively slow process. The maximum rate of degeneration is seen in the distal interphalangeal joints where the average increase is about 1 grade per individual in an interval of 12 to 16 years between visits in each age group. The rate of degeneration in the proximal interphalangeal joints is much lower than that of the distal interphalangeal joints. 2) The progress of the degeneration in the distal interphalangeal joints of an individual (longitudinally evaluated) follows closely that which is observed at the population level (cross-sectional joint-digit study). That is, it is directly related to the age and the interval between visits. This is not always seen in the proximal interphalangeal joint data. 3) The rate of change in the osteoarthritic grade of individual hands agrees closely with that of their distal interphalangeal joints. This further supports the conclusions reached in a first report that what has been referred to as osteoarthritic grade of the hand of an individual may actually be the higher grade among the distal interphalangeal joints.

Adult

A new method for investigating the relation between change and initial value in longitudinal blood pressure data. I. Description and application of the method.

The relation between change and initial value is of great interest in longitudinal studies. With variables containing random errors (short-term intra-individual variations and measurement errors) the directly computed relation is however, biased by the regression towards the mean phenomenon. Earlier proposed solutions of the problem are unsatisfactory. In this paper the regression towards the mean phenomenon is described and a new method is proposed by which the error caused by the regression towards the mean is avoided. The method is applied to a set of longitudinal blood pressure data. It is shown that the observed, biased relation in this case is significantly negative, while the correct relation obtained with this method is significantly positive. Since random errors are present in most biological variables, similar erroneous conclusions may easily be drawn also in other cases if the regression towards the mean phenomenon is not corrected for. In this analysis, random errors constitute 65--80% of the observed blood pressure change. To reduce this dominance, recommendations about study design for future studies of change/initial value relationships are given.

Blood Pressure

Longitudinal variability of lipoprotein(a) in youth-onset type 1 diabetes: implications for cardiovascular risk stratification.

BACKGROUND: Lipoprotein(a) [Lp(a)] is a genetically determined and independent cardiovascular risk factor, traditionally considered stable across the lifespan, supporting a single lifetime measurement strategy. However, its longitudinal behaviour during childhood and adolescence remains poorly characterised, particularly in individuals with type 1 diabetes who face a markedly increased lifetime risk of coronary artery disease. We therefore aimed to characterise intra- and inter-individual trajectories of Lp(a) in a paediatric type 1 diabetes cohort and to assess the implications of Lp(a) variability for cardiovascular risk classification. METHODS: We conducted a retrospective single-centre cohort study of children and adolescents with type 1 diabetes attending Geneva University Hospitals between 2012 and 2023. Annual fasting Lp(a) concentrations were analysed longitudinally. Variability was assessed in participants with&#x2009;&#x2265;&#x2009;2 measurements. Clinically relevant thresholds were used to evaluate cardiovascular risk reclassification. Paired Wilcoxon tests, Pearson and Kendall correlations, and Holm-adjusted p-values (P&#x2009;<&#x2009;0.05) were applied. Analyses were conducted in R. RESULTS: A total of 286 participants contributed 1403 Lp(a) measurements, with observation periods varying across individuals (median 6.2&#xa0;years, IQR 2.9-9.6) and between 1 and 13 measurements per participant. At baseline, 26% had elevated Lp(a) (&#x2265;&#x2009;300&#xa0;mg/l). Among participants with serial measurements, 32% showed intraindividual fluctuations exceeding 50% of their individual maximum value. Reclassification across the 300&#xa0;mg/l cardiovascular risk threshold occurred in 11.9% of participants. Lp(a) concentrations peaked between ages 10 and 13&#xa0;years and declined thereafter. Modest seasonal variation was observed, with higher concentrations in autumn and winter (P&#x2009;<&#x2009;0.05). CONCLUSIONS: In youth with type 1 diabetes, Lp(a) is not as stable as previously assumed, exhibiting clinically relevant variability over time. These findings challenge the current paradigm of a single lifetime Lp(a) measurement and suggest that repeated assessment, particularly during adolescence, may improve early cardiovascular risk stratification.

Humans

Comprehensive cross-sectional and longitudinal comparisons of plasma glial fibrillary acidic protein and neurofilament light across FTD spectrum disorders.

BACKGROUND: Therapeutic development for frontotemporal dementia (FTD) is hindered by the lack of biomarkers that inform susceptibility/risk, prognosis, and the underlying causative pathology. Blood glial fibrillary acidic protein (GFAP) has garnered attention as a FTD biomarker. However, investigations of GFAP in FTD have been hampered by symptomatic and histopathologic heterogeneity and small cohort sizes contributing to inconsistent findings. Therefore, we evaluated plasma GFAP as a FTD biomarker and compared its performance to that of neurofilament light (NfL) protein, a leading FTD biomarker. METHODS: We availed ARTFL LEFFTDS Longitudinal Frontotemporal Lobar Degeneration (ALLFTD) study resources to conduct a comprehensive cross-sectional and longitudinal examination of the susceptibility/risk, prognostic, and predictive performance of GFAP and NfL in the largest series of well-characterized presymptomatic FTD mutation carriers and participants with sporadic or familial FTD syndromes. Utilizing single molecule array technology, we measured GFAP and NfL in plasma from 161 controls, 127 presymptomatic mutation carriers, 702 participants with a FTD syndrome, and 67 participants with mild behavioral and/or cognitive changes. We used multivariable linear regression and Cox proportional hazard models adjusted for co-variates to examine the biomarker utility of baseline GFAP and NfL concentrations or their rates of change. RESULTS: Compared to controls, GFAP and NfL were elevated in each FTD syndrome but GFAP, unlike NfL, poorly discriminated controls from participants with mild symptoms. Similarly, both baseline GFAP and NfL were higher in presymptomatic mutation carriers who later phenoconverted, but NfL better distinguished non-converters from phenoconverters. We additionally observed that GFAP and NfL were associated with disease severity indicators and survival, but NfL far outperformed GFAP. Nevertheless, we validated findings that the GFAP/NfL ratio may discriminate frontotemporal lobar degeneration with tau versus TDP-43 pathology. CONCLUSIONS: Our head-to-head comparison of plasma GFAP and NfL as biomarkers for FTD indicate that NfL consistently outmatched GFAP as a prognostic and predictive biomarker for participants with a FTD syndrome, and as a susceptibility/risk biomarker for people at genetic risk of FTD. Our findings underscore the need to include leading biomarkers in investigations evaluating new biomarkers if the field is to fully ascertain their performance and clinical value.

Humans

Temporal associations between leukocytes DNA methylation and blood lipids: a longitudinal study.

BACKGROUND: The associations between blood lipids and DNA methylation have been investigated in epigenome-wide association studies mainly among European ancestry populations. Several studies have explored the direction of the association using cross-sectional data, while evidence of longitudinal data is still lacking. RESULTS: We tested the associations between peripheral blood leukocytes DNA methylation and four lipid measures from Illumina 450&#xa0;K or EPIC arrays in 1084 participants from the Chinese National Twin Registry and replicated the result in 988 participants from the China Kadoorie Biobank. A total of 23 associations of 19 CpG sites were identified, with 4 CpG sites located in or adjacent to 3 genes (TMEM49, SNX5/SNORD17 and CCDC7) being novel. Among the validated associations, we conducted a cross-lagged analysis to explore the temporal sequence and found temporal associations of methylation levels of 2 CpG sites with triglyceride and 2 CpG sites with high-density lipoprotein-cholesterol (HDL-C) in all twins. In addition, methylation levels of cg11024682 located in SREBF1 at baseline were temporally associated with triglyceride at follow-up in only monozygotic twins. We then performed a mediation analysis with the longitudinal data and the result showed that the association between body mass index and HDL-C was partially mediated by the methylation level of cg06500161 (ABCG1), with a mediation proportion of 10.1%. CONCLUSIONS: Our study indicated that the DNA methylation levels of ABCG1, AKAP1 and SREBF1 may be involved in lipid metabolism and provided evidence for elucidating the regulatory mechanism of lipid homeostasis.

Humans

An integrative network approach for longitudinal stratification in Parkinson's disease.

Parkinson's disease (PD) is a neurodegenerative disorder characterized by motor symptoms resulting from the loss of dopamine-producing neurons in the brain. Currently, there is no cure for the disease which is in part due to the heterogeneity in patient symptoms, trajectories and manifestations. There is a known genetic component of PD and genomic datasets have helped to uncover some aspects of the disease. Understanding the longitudinal variability of PD is essential as it has been theorised that there are different triggers and underlying disease mechanisms at different points during disease progression. In this paper, we perform longitudinal and cross-sectional experiments to identify which data modalities or combinations of modalities are informative at different time points. We use clinical, genomic, and proteomic data from the Parkinson's Progression Markers Initiative. We validate the importance of flexible data integration by highlighting the varying combinations of data modalities for optimal stratification at different disease stages in idiopathic PD. We show there is a shared signal in the DNAm signatures of participants with a mutation in a causal gene of PD and participants with idiopathic PD. We also show that integration of SNPs and DNAm data modalities has potential for use as an early diagnostic tool for individuals with a genetic cause of PD.

Parkinson Disease

Timing and sequence of eruption of permanent teeth in a longitudinal sample of children from Oregon.

A longitudinal sample of children was examined for timing and sequence of eruption of permanent teeth. Separate consideration was given to 124 boys and 163 girls from the Child Study Clinic longitudinal growth study. Girls show more variability in age at eruption than boys, and eruption is generally earlier in girls. The degree of variation in sequences of eruption of the first seven permanent teeth is distinct. The most common sequence in girls' maxillas occurred in only 11.4% of subjects; in boys, the most common sequence appeared in 13.4% of subjects. Predictability efficiency of eruption of the first three permanent teeth is not higher than 0.74.

Adolescent

Digital Remote Assessment of Motor and Speech Changes in Amyotrophic Lateral Sclerosis: Longitudinal Observational Study.

BACKGROUND: Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease with an active trial landscape that relies on the sensitivity of selected clinical trial endpoints. Traditional clinical outcome assessments perform well in trials but lack strong psychometric properties and may not detect small but clinically meaningful disease progression. Digital health technologies offer a promising alternative for tracking ALS disease progression. OBJECTIVE: This study assessed the feasibility of remote digital monitoring in ALS using a comprehensive battery of prescribed home-based assessments via a smartphone, a wearable device, and a computer-based mouse-clicking task. METHODS: Participants completed weekly remote assessments, including motor and speech tasks via a smartphone app and a computer mouse-clicking task for 24 weeks. They also participated in 3 remote telephone visits in weeks 1, 13, and 25. Reliability, minimal detectable change, and correlations with self-reported ALS Functional Rating Scale-Revised subdomain scores were calculated for 8 features across the speech, fine motor, and gross motor smartphone app tasks and for all 32 features from the computer mouse-clicking task. Sensitivity to longitudinal change was assessed for the 8 smartphone-derived features and for a representative subset of 8 computer mouse-clicking features. RESULTS: Forty-two participants (19 with ALS and 23 controls) completed 10,237 smartphone assessments and 459 computer mouse-clicking sessions. Baseline discriminative models differentiated ALS from controls with AUC values of 0.75-0.92. Digital measures correlated strongly with self-reported ALS Functional Rating Scale-Revised subdomain scores. Both participants with ALS and controls demonstrated improvement in fine motor and speech measures, with the exception of nondominant-hand pegboard performance, which declined in the ALS group. Improvements were smaller in participants with ALS, leading to increasing group differences over time, although only one feature showed a statistically significant separation over the 24 weeks. Gait and balance performance declined in both groups, with greater but nonsignificant separation observed for balance measures. CONCLUSIONS: These findings support the feasibility of digital remote assessments in ALS, demonstrate the ability to discriminate between ALS and controls based on certain features collected from speech, fine, and gross motor tasks, and in some cases, quantify functional decline over time. Further research is necessary to explore the natural history of these features longitudinally in larger cohorts of participants with ALS over extended periods to enable their potential integration into clinical trials.

Adult

[Longitudinal studies on the physical development of low birth weight children. Growth dynamics and sexual dimorphism during the first year of life].

Longitudinal studies of physical development in the first year of life were carried out in the group of children born with low body weight. Results were compared with those obtained in the control group. The examined group consisted of 73 children born from single pregnancies in hospitals from families living in Wola district of Warsaw. Out of 73 children, 35 were born t term as small-for-date children (DW). Remaining 38 children were prematurely born (W). The control group (K) consisted of 40 children born in hospital at term, from single pregnancy, with body-weight at birth corresponding to foetal age (25-75 centiles). They came also from families living in Wola district. Analysis of physical development was based on the results of anthropometric measurements carried out at monthly intervals through the first year of life, considering required age tolerance, using standardized measuring methods and instruments. The principles of feeding, nursing, prophylaxis of rickets and iron deficiency as well as preventive vaccinations were the same for all children. Variability with age as well as monthly and yearly gains and the index of sexual dimorphism of the following parameters were analysed: body-weight, body-length, head and chest circumference thorax and head length, shoulders width, hip width. Longitudinal observation of these children through evaluation of growth increments made the analysis of the dynamics of somatic development possible. The analysis showed differences in physical development in the first year of life in children under examination. These differences concerned both the variability of separate traits with age, and the dynamics of development, development of sexual dimorphism index in relation to the control group. The differences ere also observed between the small-to-date and prematurely born children. Developmental differences ere noted among the children born with low body-weight dependent on the achieved foetal age at birth. No tendency in small-for-date infants to decrease the differences as compared to the control group was noted. This tendency was typical of the prematurely born children. The highest developmental rate was observed in prematurely born infants.(ABSTRACT TRUNCATED AT 400 WORDS)

Age Factors

A longitudinal cephalometric study on unilateral cleft lip and palate subjects.

The facial growth of nine male and 9 female subjects with surgically repaired unilateral cleft lips and palates was compared to that of 20 male and 15 female non-cleft individuals. Different cephalometric landmarks were identified on the cranial base and maxillary complex, and eleven different parameters were measured. Univariate longitudinal growth profile and mean vector analyses as well as multivariate and cross-sectional comparisons were performed between male, female, and combined normal and cleft groups. Linear data comparisons indicated statistically significant differences in the growth profile and mean vector analyses of several of the parameters describing the relationship (SNA and SNAns) and dimensions (Ans-Ptm and A-Ptm) of the maxillary complex. Incremental data comparisons on the same parameters (SNA, SNAns, Ans-Ptm and A-Ptm) indicated statistically significant differences in the mean vector longitudinal analysis and the univariate cross-sectional analysis. Most of these significant differences were concentrated in the older age comparisons (7 to 8, 8 to 9, and 9 to 10 years). Where significant differences existed, the normal sample increments were usually greater than the cleft sample increments.

Cephalometry

Cross-sectional and longitudinal evaluations of an endurance training program.

A comparison of the cardiorespiratory responses obtained using both a longitudinal and cross-sectional evaluation of an endurance training program was made in two groups of 60 young male military personnel. Both groups were initially tested (T1) and then retested 6 months later (T2). At T1, Group I was a sample of personnel not participating in a training program while Group II had undergone a 5-month endurance program (2-4 mile run/day). At T2, Groups I and II had been participating in the program for 6 and 11 months, respectively. Testing consisted of sub-maximal and maximal determinations of VO2, VE and heart rate (HR) using an interrupted treadmill test. VO2 max was 11% greater in Group II compared to Group I at T1 and increased 10% in Group I at T2. Similar results were also seen for HR submax, HR max and VE max. These results show that similar values indicative of an improved level of cardiorespiratory fitness can be obtained using either a cross-sectional or longitudinal design when relatively homogeneous groups are studied.

Adolescent