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Biomedical subjects

F L Bookstein

Publications and source records attributed to F L Bookstein.

At least 91 records · Page 5Linked to original sources
PubMed1982

Do horizontal growers grow horizontally?

It is common to analyse the growth direction of the facial skeleton by registering serial lateral cephalograms on Sella and orienting along Sella-Nasion. The present paper reports an exercise in cephalometric growth analysis by an alternate method the study of mean growth tensors. The authors conclude that conventional cephalometric techniques are inadequate for precise analysis and practical prediction of craniofacial change and that cephalometrics should proceed independently of any orientation or registration at all, with analyses following from the phenomenon, not preceding it.

Adolescent↗
PubMed1981

Bandeiraea simplicifolia I isolectins reveal a development sequential relationship.

We have analyzed the distribution of the five tetrameric Bandeiraea simplicifolia I isolectins (A4, A3b, A2B2, AB3, B4) isolated by melibionate Bio-Gel affinity chromatography from 168 single seeds gathered in Ghana from known trees and pods. Alkaline, nondenaturing polyacrylamide gel electrophoresis was employed to analyze the distribution of the five isolectins. The polyacrylamide gels were scanned at 625 nm and the peak height corresponding to each isolectin was measured and expressed as a percentage of the total of peak height. Principal components analysis of the correlations among the percentages indicated a sequential relationship among the five isolectins with the concentrations of B4 and A4 inversely related. Further statistical analyses indicated that although the distribution of isolectins in each seed was unique, seeds gathered from the same tree were more similar than seeds gathered from different trees. Several causes of this sequential relationship are discussed.

Electrophoresis, Polyacrylamide Gel↗
PubMed1980

Differential diagnosis of class II malocclusions. Part 1. Facial types associated with class II malocclusions.

By means of computer-based statistical methods, several types of Class II malocclusion have been discovered with defining horizontal and vertical characteristics. Of the six horizontal types, four are severe syndromes, one is a loose, ill-defined grouping of cases with mild skeletal features, and one has only the dental features of Class II. Five vertical types associates with Class II were also revealed, although each vertical is not associated with all horizontal types. A simplified simulation of the computerized procedures has been developed for routine use in clinical practice.

Child↗
PubMed1979

The inappropriateness of conventional cephalometrics.

1. Cephalometric conventions today may have little basis in either biology or biometrics. 2. There is no theory of cephalometrics, only conventions which involve landmarks and straight lines only. These fail to capture the curving of form and its changes, exclude proper measures of size for bent structures, and misrepresent growth, portraying it as vector displacement rather than a generalized distortion. 3. Conventional cephalometric procedures misinform by fabrication of misleading geometric quantities, by camouflage, particularly of remodeling, by confusion about what is happening (analysis of rotations, treating shape separately from size, and registering angles on landmarks as vertices), and by subtraction as a representation of growth. 4. We suggest that the present systems offer little real hope of improvement sufficient to meet our needs in craniofacial growth research. We call attention to three possible techniques to be included in future cephalometric conventions: (1) tangents and curvatures, (2) Blum's medial axis ("skeleton"), and (3) biorthogonal grids.

Biometry↗
PubMed1979

The concept of pattern in craniofacial growth.

1. There are semantic and associated problems with the word pattern in biology, particularly in orthodontics and facial growth. 2. Pattern, as we use the term, is invariance of relationships--"a set of constraints operating to preserve the integration of parts under varying conditions and through time." 3. Craniofacial pattern can be described and quantified by the identification of craniofacial constants, measures that are relatively invariant. 4. Growth is change and is best identified by studying those measures of size and shape that vary most sensitively through time over development stages. 5. The many traditional cephalometric measures that represent well neither pattern nor growth (mixed) are of less clinical utility than either pure pattern indices or growth indices. 6. The analytical and conceptual separation of pattern and growth seems useful in analysis of morphology, analysis of growth, prediction of growth, and clinical treatment planning.

Adolescent↗
PubMed1977

Orthogenesis of the hominids: an exploration using biorthogonal grids.

In 1917, D'Arch Thompson suggested that one should study the change from one biological form to another by examining the unique mathematical object that maps between them in accord with biological homologies. Biorthogonal grids provide a particular coordinate system for visualizing such a map and lead to a quantitative syntax in which a change in shape is reduced to differential changes in size. Application of the method to hominid skull phylogeny has demonstrated three principal axes of evolutionary change anatomically homologous over a fossil sequence.

Animals↗
PubMed1977

A potential model for the interaction of enamel fluoride and plaque in the development of dental caries.

A model relating caries to surface enamel fluoride and plaque has been derived by exploratory data analyses. Since the model was obtained a posteriori, it is best viewed in qualitative terms as a hypothesis for future testing. The model prompts a re-evaluation of expectations relative to the effects of surface enamel apatitic fluoride, and a consideration that the effectiveness of a given measure of fluoride may vary as a function of inherent challenge. Thus, further studies are needed, aimed at quantifying the parameters of resistance and challenge, and characterizing the relationship between them.

Adolescent↗
PubMedDate not supplied

Neurobehavioral effects of prenatal alcohol: Part I. Research strategy.

This paper, Part I of a three-part series, reviews the literature on the neurobehavioral effects of prenatal alcohol exposure and describes a large group of tests assembled to assess neurobehavioral outcomes of alcohol teratogenesis in 7-year-old children. This paper presents the distribution of these test scores for our sample and discusses their relationships with an alcohol binge score and with full-scale IQ. This group of tests is suitable for children with a wide range of abilities and provides a broad assessment of neurobehavioral deficits. Part II of this series describes a new method of statistical analysis, Partial Least Squares (PLS), which is particularly well suited to complex multivariate data sets such as these, and with its aid, examines the effects of prenatal alcohol exposure on IQ, achievement, vigilance and classroom behavior, a total of 43 outcome scores. Part III examines prenatal alcohol effects on outcomes from the broad group of 164 scores deriving from 17 neuropsychologic tests, using the Partial Least Squares methodology, and summarizes the implications of our findings for the behavioral teratology of alcohol.

Child↗
PubMedDate not supplied

Neurobehavioral effects of prenatal alcohol: Part II. Partial least squares analysis.

This paper, the second in a series of three, introduces Partial Least Squares (PLS) methods for assessing the effects of moderate levels of prenatal alcohol exposure on performance and behavior in young school-age children. Studies of human behavioral teratology pose statistical problems for which standard multiple regression methods are inadequate. Prenatal alcohol exposure, the teratogenic "dose," can be assessed only indirectly through a variety of measures of alcohol consumption. Similarly, the behavioral outcomes we examine--IQ, achievement, classroom behavior, and vigilance--are each measured indirectly in terms of multiple items or indicators. We find that a single latent variable, estimated as a linear combination of the measures of alcohol consumption, provides an appropriate measure of "dose" for summarizing the relationships between alcohol exposure and each of the four blocks of outcome variables. A pattern of alcohol consumption emphasizing binge behavior (i.e., reporting average consumption of multiple drinks per drinking occasion, or at least five drinks on any single occasion) in the period prior to recognition of pregnancy is significantly correlated with latent variables computed from each of the four outcome blocks: IQ, academic achievement, classroom behavior and attention/vigilance.

Arousal↗
PubMedDate not supplied

Neurobehavioral effects of prenatal alcohol: Part III. PLS analyses of neuropsychologic tests.

This paper is the third in a three-part series describing an investigation of the effects of prenatal alcohol exposure on the neurobehavioral functioning of 384 children about 7 1/2 years old. Here we describe the use of Partial Least Squares for data reduction and analysis of 158 neurobehavioral measures as they relate to 13 aspects of prenatal alcohol exposure. A general alcohol latent variable, emphasizing both binge and regular drinking patterns in the period prior to pregnancy recognition as well as during pregnancy, predicts a pattern of neurobehavioral deficit that includes attentional and memory deficits across both verbal and visual modalities; a variety of "process" variables reflecting poor integration and quality of responses; behavior patterns involving distractibility and poor organization; and an inflexible approach to problem-solving. The prominence of poorer spatial organization and arithmetic as primary outcomes of alcohol teratogenesis suggests a possible "nonverbal learning disability" pattern of deficit associated with prenatal alcohol exposure at the level of social drinking.

Behavior↗
PubMedDate not supplied

Plasminogen-enriched pulse-spray thrombolysis with tPA: further developments.

PURPOSE: To further improve methods for pulsed plasminogen-enriched thrombolysis and to compare results with the best obtainable with use of tissue plasminogen activator (tPA) alone. MATERIALS AND METHODS: Parameters of plasminogen-enriched pulse-spray thrombolysis were manipulated in groups of rabbits with inferior vena cava thrombosis, and weights of 1-hour residual thrombus were compared. Variables evaluated were (i) tPA pulse frequency, (ii) amount of plasminogen used for enrichment, (iii) tPA concentration and amount, (iv) pulsed versus infused tPA, and (v) admixture versus separation of plasminogen and tPA. RESULTS: With use of 3 mg of tPA and approximately 0.9 mg plasminogen enrichment, efficacy varied directly with pulse frequency over a pulse range of every 15 minutes to every 30 seconds. With use of 30-second pulses of tPA at a concentration 0.125 mg/mL, efficacy also correlated directly with increasing plasminogen enrichment up to, but not beyond, approximately 1.8 mg per 1.24 g of clot. Optimized methodology yielded 89% lysis in 1 hour, as compared to 74% lysis previously reported with use of optimized low-concentration (0.01 mg/ mL) tPA alone. Plasminogen enrichment in conjunction with low concentrations of tPA, admixture of tPA and plasminogen, and fractionation of the plasminogen enrichment all proved to be nonproductive or counterproductive. CONCLUSION: Optimized in vivo postthrombotic plasminogen enrichment significantly accelerated thrombolysis of experimental clots compared to use of optimized tPA alone.

Animals↗
PubMedDate not supplied

Tensor biometrics for changes in cranial shape.

D'Arcy Thompson's method of Cartesian transformations can be adapted to the biometric study of group differences and trends in shape. The key to this extension is the symmetric tensor, a mathematical representation of the linear deformation taking one triangle onto another. These tensors may easily be computed from data that come in the form of Cartesian coordinates of homologous landmarks, such as are customary in roentgenographic cephalometrics. This article shows how the tensors make possible the rigorous statistical analysis of populations of shapes without requiring the specification of particular shape measures in advance. Instead, the findings of a study include the extraction of particular shape measures most clearly manifesting the group difference or treatment effect under study. Only conventional multivariate statistical techniques, such as Hotelling's T2, are involved. Configurations of many landmarks can be analysed via the display of their mean difference as a biorthogonal grid pair, perusal of which leads to the selection of triangles of landmarks for more rigorous analysis. The techniques are exemplified in two cephalometric studies: the description and prediction of normal craniofacial growth, and a comparison of the craniofacial deformities associated with Apert's and Crouzon's syndromes.

Biometry↗
PubMedDate not supplied

Convergence of neural systems processing stimulus associations and coordinating motor responses.

A sensory-sensory learning paradigm was used to measure neural changes in humans during acquisition of an association between an auditory and visual stimulus. Three multivariate partial least-squares (PLS) analyses of positron emission tomography data identified distributed neural systems related to (i) processing the significance of the auditory stimulus, (ii) mediating the acquisition of the behavioral response, and (iii) the spatial overlap between these two systems. The system that processed the significance of the tone engaged primarily right hemisphere regions and included dorsolateral prefrontal cortex, putamen, and inferior parietal and temporal cortices. Activity changes in left occipital cortex were also identified, most likely reflecting the learned expectancy of the upcoming visual event. The system related to behavior was similar to that which coded the significance of the tone, including dorsal occipital cortex. The PLS analysis of the concordance between these two systems showed substantial regional overlap, and included occipital, dorsolateral prefrontal, and limbic cortices. However, activity in dorsomedial prefrontal cortex was strictly related to processing the auditory stimulus and not to behavior. Taken together, the PLS analyses identified a system that contained a sensory-motor component (comprised of occipital, temporal association and sensorimotor cortices) and a medial prefrontallimbic component, that as a group simultaneously embodied the learning-related response to the stimuli and the subsequent change in behavior.

Acoustic Stimulation↗
PubMedDate not supplied

The composition of the radiologic report.

In order to understand and evaluate fully the composition of the radiologic report, an experiment was performed in which eight readers each read the same 100 chest radiographs. The reports were dissected into individual statements, each of which was analyzed for accuracy, statement type (descriptive or etiologic), confidence, and specificity. In addition, each report was evaluated for stylistic factors of succinctness, orderliness, and the use of supplemental comments. Detailed analysis showed the radiologic report to be a series of largely descriptive statements in which confidence level, specificity, and orderliness were associated with the presence of errors in film interpretation. These factors can serve as important markers for identifying error-laden films. The use of specific, etiologic diagnoses in these film readings was limited. The composition of the report was not related to the length of radiologic training beyond the first year of residency. The implications of these findings concerning report composition in light of present day radiologic practice and new, automated radiologic reporting systems were discussed.

Diagnostic Errors↗
PubMedDate not supplied

Multiple pulmonary nodules detected by computed tomography: diagnostic implications.

Prior to the advent of CT, the radiographic demonstration of multiple nonmiliary lung nodules usually indicated the presence of metastases or, less likely, granulomas. The increased sensitivity of CT at detecting small parenchymal pulmonary densities is accompanied by loss of specificity, creating uncertainty as to the significance of nodules detected at CT in any individual patient. During a 1 year period we reviewed all CT scans in our institution demonstrating three or more focal lung densities, noting these parameters: number of densities, maximum lesion size, presence of calcification as determined visually, and lesion morphology (linear or nodular). Of 137 patients with three or more focal lung densities at CT, nodule diagnosis was established on pathologic or clinical grounds in 114. Metastases accounted for 73%, with primary colon and lung malignancies and lymphoma the most common causes. Malignant nodules were statistically significantly larger, more numerous, and more rounded, whereas calcification was significantly associated with benign disease. However, no single criterion or combination of criteria was foolproof. Based on our results, we offer recommendations for further evaluation of nodules in several common clinical settings.

Adenocarcinoma↗