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PubMed1999

Trait compensation and cospecialization in a freshwater snail: size, shape and antipredator behaviour.

We examined relationships between individual differences in antipredator behaviour and prey morphological characters (size, shape) that influence prey vulnerability. Behavioural responses of Physa gyrina to chemical cues associated with predation by crayfish Orconectes rusticus, were assayed in the laboratory for 6 days over a 13-day period. Snails displayed consistent, individually repeatable responses to the predation cues, including hiding (refuge use) and substratum avoidance (crawling to the water surface or out of the water). We assessed shell morphology using morphometric techniques that isolate geometrically independent components of size and shape variation corresponding to aperture width and apertural obstruction. Previous studies indicate that large size, narrow apertures and obstructed apertures reduce morphological vulnerability to the shell-entry predation tactics used by crayfish. In the present study, small, and thus more vulnerable, prey tended to show stronger antipredator behaviour than large prey (i.e. behavioural compensation for morphological vulnerability). In contrast, behavioural and shape-based defences were positively correlated; snails with narrow apertures showed strong antipredator responses. We refer to this 'double defence' against predators as cospecialization. With either compensation or cospecialization, suites of correlated behavioural or morphological traits must be studied in tandem to understand the adaptive value of prey responses to predators. Copyright 1999 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1996

Placenta morphology and absent or reversed end diastolic flow velocities in the umbilical artery: a clinical and morphometrical study.

The aim of the study was to investigate if a relation exists between absent or reversed end diastolic (ARED) flow in the umbilical artery and morphometric characteristics of the placenta. Geometric parameters were measured in the terminal villi of nine placentae, collected after a pregnancy complicated by ARED flow. Placentae from pregnancies with normal Doppler velocimetry in the umbilical artery were matched for gestational age and formed the control group. Mean placental weight in the ARED group was significantly lower than in the control group. Morphometric characteristics of the terminal placental villi did not differ substantially between the two groups before 30 weeks gestation. After 30 weeks mean villous profile cross sectional area and diameter were significantly smaller in the ARED group than in the control group. The mean profile cross sectional villous diameter in the ARED group did not differ substantially before and after 30 weeks of gestation (2287 microns2 and 2303 microns2, respectively). Accelerated maturation of terminal villi occurs in placentae delivered after a pregnancy with ARED flow in the umbilical artery. Morphometric characteristics are significantly different between placentae expelled after ARED velocities or after normal Doppler recordings in the umbilical artery. In ARED placentae, a significantly more uniform pattern of small villi is found compared with control placentae.

Blood Flow Velocity↗
PubMed1996

Three-dimensional statistical analysis of sulcal variability in the human brain.

Morphometric variance of the human brain is qualitatively observable in surface features of the cortex. Statistical analysis of sulcal geometry will facilitate multisubject atlasing, neurosurgical studies, and multimodality brain mapping applications. This investigation describes the variability in location and geometry of five sulci surveyed in each hemisphere of six postmortem human brains placed within the Talairach stereotaxic grid. The sulci were modeled as complex internal surfaces in the brain. Heterogeneous profiles of three-dimensional (3D) variation were quantified locally within individual sulci. Whole human heads, sectioned at 50 micrometer, were digitally photographed and high-resolution 3D data volumes were reconstructed. The parieto-occipital sulcus, the anterior and posterior rami of the calcarine sulcus, the cingulate and marginal sulci, and the supracallosal sulcus were delineated manually on sagittally resampled sections. Sulcal outlines were reparameterized for surface comparisons. Statistics of 3D variation for arbitrary points on each surface were calculated locally from the standardized individual data. Additional measures of surface area, extent in three dimensions, surface curvature, and fractal dimension were used to characterize variations in sulcal geometry. Paralimbic sulci exhibited a greater degree of anterior-posterior variability than vertical variability. Occipital sulci displayed the reverse trend. Both trends were consistent with developmental growth patterns. Points on the occipital sulci displayed a profile of variability highly correlated with their 3D distance from the posterior commissure. Surface curvature was greater for the arched paralimbic sulci than for those bounding occipital gyri in each hemisphere. On the other hand, fractal dimension measures were remarkably similar for all sulci examined, and no significant hemispheric asymmetries were found for any of the selected spatial and geometric parameters. Implications of cortical morphometric variability for multisubject comparisons and brain mapping applications are discussed.

Aged↗
PubMed1989

A morphometrical method to estimate isoproterenol-induced infarct size in the rat.

A morphometrical method to quantify the geometrical distribution of ventricular necrosis induced in rat following the s.c. injection of isoproterenol was developed and tested. Each ventricle was divided into two portions, apical and basal, and then 10 microns thick sections of both portions were cut. Necrotic areas were detected with nitro blue tetrazolium. Total and necrotic areas were measured for each section. Thereafter, the total and necrotic volume were calculated assuming that the ventricles form a cone-like structure composed of successive frustum of a cone crowned by an apical cone. The study of volumes, necrotic and whole cardiac could be relevant for a more actual experimental comparison of the anti-ischemic drugs activity. Our results indicated that necrotic volume is unevenly distributed, especially at lower doses of isoproterenol treatment, being greater at the apical than at the basal portions of the ventricles. The importance of careful study of the ventricular apex is stressed. Potential sources of error in determining necrotic volume are discussed.

Animals↗
PubMed1989

A new method of grading malignancy of prostate carcinoma using quantitative microscopic nuclear features.

A morphometrical assessment of nuclear features and a DNA study were performed on prostate tissue specimens from 33 patients with prostate carcinoma using an image analysing computer. Six nuclear geometric variables were measured and their mean, standard deviation (SD) and standard error (SE) were calculated for each case. The data on nuclear DNA content obtained by static cytometry were processed using an algorithm which provided a DNA grade of malignancy (DNA MG). Using the stepwise multiple regression, we found a significant correlation (p less than 0.01) between the DNA MG, chosen as the dependent variable in the statistical model, and the following nuclear features in decreasing order of importance: area SD, convex perimeter SE, and the mean of maximum diameter. From the correlation coefficients of the variables an equation was built up which provided a geometric nuclear grade of malignancy (GNMG) on a morphometrical basis more closely related to the clinical stage of the tumour (r = 0.75) than the visually assessed histological grade (r = 0.68) based on the Gleason score. This new method of grading malignancy allows an objective and quantitative evaluation to be made of the biological behaviour of the tumour, as measured by the patient's clinical stage.

Cell Nucleus↗
PubMed2000

Cirripede phylogeny using a novel approach: molecular morphometrics.

We present a new method using nucleic acid secondary structure to assess phylogenetic relationships among species. In this method, which we term "molecular morphometrics," the measurable structural parameters of the molecules (geometrical features, bond energies, base composition, etc.) are used as specific characters to construct a phylogenetic tree. This method relies both on traditional morphological comparison and on molecular sequence comparison. Applied to the phylogenetic analysis of Cirripedia, molecular morphometrics supports the most recent morphological analyses arguing for the monophyly of Cirripedia sensu stricto (Thoracica + Rhizocephala + Acrothoracica). As a proof, a classical multiple alignment was also performed, either using or not using the structural information to realign the sequence segments considered in the molecular morphometrics analysis. These methods yielded the same tree topology as the direct use of structural characters as a phylogenetic signal. By taking into account the secondary structure of nucleic acids, the new method allows investigators to use the regions in which multiple alignments are barely reliable because of a large number of insertions and deletions. It thus appears to be complementary to classical primary sequence analysis in phylogenetic studies.

Animals↗
PubMed1992

[The role of the nucleus in the mechanism of transformation of muscle after infection by Trichinella spiralis larvae. III. Morphometric analysis of the functional transformation of the muscle cell nucleus after infection].

Morphometric investigations (using the convergence analysis method) of geometric parameters of nuclei and nucleoli of transformed muscle cells were carried in mice 15 days, 30 days and 6 month after infection with T. spiralis larvae. The analysis showed the largest increase of investigated the parameters of 15th day after the infection. The results of morphometric analysis are in agreement with the morphologic, ultrastructural and histochemical observations (published in I and II part) as for as functional changes of muscle cells in various stages of trichinellosis are concerned.

Animals↗
PubMed1996

Biometrics, biomathematics and the morphometric synthesis.

At the core of contemporary morphometrics--the quantitative study of biological shape variation--is a synthesis of two originally divergent methodological styles. One contributory tradition is the multivariate analysis of covariance matrices originally developed as biometrics and now dominant across a broad expanse of applied statistics. This approach, couched solely in the linear geometry of covariance structures, ignores biomathematical aspects of the original measurements. The other tributary emphasizes the direct visualization of changes in biological form. However, making objective the biological meaning of the features seen in those diagrams was always problematical; also, the representation of variation, as distinct from pairwise difference, proved infeasible. To combine these two variants of biomathematical modeling into a valid praxis for quantitative studies of biological shape was a goal earnestly sought though most of this century. That goal was finally achieved in the 1980s when techniques from mathematical statistics, multivariate biometrics, non-Euclidean geometry and computer graphics were combined in a coherent new system of tools for the complete regionalized quantitative analysis of landmark points together with the biomedical images in which they are seen. In this morphometric synthesis, correspondence of landmarks (biologically labeled geometric points, like "bridge of the nose") across specimens is taken as a biomathematical primitive. The shapes of configurations of landmarks are defined as equivalence classes with respect to the Euclidean similarity group and then represented as single points in David Kendall's shape space, a Riemannian manifold with Procrustes distance as metric. All conventional multivariate strategies carry over to the study of shape variation and covariation when shapes are interpreted in the tangent space to the shape manifold at an average shape. For biomathematical interpretation of such analyses, one needs a basis for the tangent space compatible with the reality of local biotheoretical processes and explanations at many different geometric scales, and one needs graphics for visualizing average shape differences and other statistical contrasts there. Both of these needs are managed by the thin-plate spline, a deformation function that has an unusually helpful linear algebra. The spline also links the biometrics of landmarks to deformation analysis of the images from which the landmarks originally arose. This article reviews the history and principal tools of this synthesis in their biomathematical and biometrical context and demonstrates their usefulness in a study of focal neuroanatomical anomalies in schizophrenia.

Anatomy↗
PubMed1994

Physical determinants of bronchial mucosal folding.

It has recently been proposed, on the basis of a theoretical analysis, that the folding of the mucosa provides a significant component of airway stiffness. The model predicted that the stiffness of an airway was directly related to the number of epithelial folds that developed. In this study we examine the possibility that the folding pattern is determined by the physical requirements that the folding membrane must stay within the boundary of the smooth muscle wall, that the submucosal mass is constant, and that the strain energy of the folding membrane is the minimum possible within the geometric constraints. Model predictions are compared with morphometric data from the noncartilaginous airways of 17 sheep lungs. The data are in agreement with our predictions, which are based on the assumption that the folding membrane thickness is proportional to the submucosal thickness (in a fully dilated airway). The outcome of this analysis is that the increase in intrinsic stiffness of the folding membrane resulting from the increased thickness outweighs the decrease in stiffness conferred by the fewer folds required by the thicker submucosa. It is suggested that the increase in folding membrane thickness observed in asthma could be viewed as a protective mechanism that tends to reduce hyperresponsiveness.

Animals↗
PubMed1999

Biomechanics of the columnar cactus Pachycereus pringlei.

We report the longitudinal variations in stiffness and bulk density of tissue samples drawn from along the length of two Pachycereus pringlei plants measuring 3.69 and 5.9 m in height to determine how different tissues contribute to the mechanical stability of these massive vertical organs. Each of the two stems was cut into segments of uniform length and subsequently dissected to obtain and mechanically test portions of xylem strands, stem ribs, and a limited number of pith and cortex samples. In each case, morphometric measurements were taken to determine the geometric contribution each tissue likely made to the ability of whole stems to resist bending forces. The stiffness of each xylem strand increased basipetally toward the base of each plant where stiffness sharply decreased, reaching a magnitude comparable to that of strands 1 m beneath the stem apex. The xylem was anisotropic in behavior, i.e., its stiffness measured in the radial and in the tangential directions differed significantly. Despite the abrupt decrease in xylem strand stiffness at the stem base, the contribution made by this tissue to resist bending forces increased exponentially from the tip to the base of each plant due to the accumulation of wood. A basipetal increase in the stiffness of the pith (and, to limited extent, that of the cortex) was also observed. In contrast, the stiffness of stem rib tissues varied little as a function of stem length. These tissues were stiffer than the xylem in the corresponding portions of the stem along the upper two-fifths of the length of either plant. Tissue stiffness and bulk density were not significantly correlated within or across tissue types. However, a weak inverse relationship was observed for these properties in the case of the xylem and stem rib tissues. We present a simple formula that predicts when stem ribs rather than the xylem strands serve as the principal stiffening agents in stems. This formula successfully predicted the observed aspect ratio of the stem ribs (the average quotient of the radial and tangential dimensions of rib transections), and thus provided circumstantial evidence that the ribs are important for mechanical stability for the distal and younger regions of the stems examined.

Journal Article↗
PubMed1993

Activity-dependent plastic changes in the motor nerve terminals of the adult rat.

Small and short-lasting physiologic variations in the locomotor activity of normal adult rats can induce remodelling in the motor nerve endings of the fast extensor digitorum longus muscle. The specificity and relative importance of the different plastic adaptations occurring in the presynaptic axonal tree have been studied, in silver impregnated nerve endings, by using an automatic image analysis treatment of the nerve terminals' geometric properties and a discriminant analysis of the morphometric parameters. Changes observed, like selective length variations in certain terminal segments and positional rearrangements, agree with a mechanism of neural connectivity regulation in the adult that arises as a consequence of normal neuromuscular activity.

Adaptation, Physiological↗
PubMed1998

Clinical evaluation of spine morphometric X-ray absorptiometry.

A new method for vertebral height measurements, morphometric X-ray absorptiometry (MXA) based on dual-energy X-ray absorptiometry, has been proposed. This technique overcomes some limitations of morphometric radiography (MRX): the effective radiation dose is low, some sources of geometric distortion are eliminated, such as dependence on patient position, magnification gradient, and the effect of scoliosis is minimized. The purpose of this study was to compare morphometric parameters obtained by both methods (MXA and MRX), and to evaluate the agreement between morphometric evaluations and qualitative reading for vertebral fracture diagnosis. The evaluation was performed with an Hologic QDR 2000 device in 67 women without vertebral fractures and 31 women with vertebral fractures (according to a qualitative assessment). The reproducibility of the image analysis was <4% and comparable to MRX. The estimated bias between the two methods was on average 10 mm, and was a function of the vertebral height, according to the Bland and Altman method. The agreement between MXA and other methods for vertebral fracture diagnosis was poor for the thoracic level above T7, due to a lack of resolution and rib interposition. Agreement was also low for T10, due to the motion of the diaphragm muscle. MXA cannot currently be used for the diagnosis of thoracic vertebral fracture in clinical practice. Technological improvements are necessary to make this promising method useful as a screening tool to evaluate the presence of thoracic vertebral fractures.

Absorptiometry, Photon↗
PubMed2006

Morphometric approach to the solvation free energy of complex molecules.

We show that the solvation free energy of a complex molecule such as a protein can be calculated using only four geometrical measures of the molecular structure and corresponding thermodynamical coefficients. We compare results from this morphometric approach to those obtained by an elaborate statistical-mechanical theory in liquid state physics for a large variety of different structures of protein G and find excellent agreement. Since the computational time is drastically reduced, the new approach provides a practical and efficient way for calculating the solvation free energy which can be employed when this quantity has to be calculated for a large number of structures, as in a simulation study of protein folding.

Models, Chemical↗
PubMed1994

Role of the microtubular system in morphological organization of normal and oncogene-transfected epithelial cells.

To understand better the role of the microtubular system in the development and maintenance of morphological organization of nonpolarized and polarized cells of the same origin we examined the effects of two microtubule-specific drugs, colcemid and taxol, on discoid cultured epithelial rat cells of the IAR-2 line and on polarized cells obtained from this line by transfection of mutated N-ras oncogene; morphometric, immunomorphologic, and videomicroscopic methods were used. Depolymerization of microtubules by colcemid did not cause major changes in the discoid shape of IAR cells but altered organization of actin cortex; in particular, it led to disappearance of circumferential bundle of actin microfilaments. Taxol reorganized the normal network of microtubules radiating from the perinuclear centers into numerous arrays of short microtubules not associated with any centers. Taxol-treated cells had wider circumferential bundles of microfilaments than control cells and morphometric analysis showed that their contours were closer to geometric circle than those of control or of colcemid-treated cells. These data show that function of the microtubular system is essential for maintenance of the characteristic morphological organization of discoid cells; we propose to name this function "contra-polarization." Contra-polarization is not prevented and is even promoted by taxol; this result suggests that a decentralized system of microtubules is sufficient for this function. In contrast, maintenance of polarized morphology of IAR-2 cells transfected by the N-ras oncogene is inhibited not only by colcemid but also by taxol and thus requires the presence of a normal centralized microtubular system.

Animals↗
PubMed1999

Geometric measurements of the lumbar spine in Chinese men during trunk flexion.

STUDY DESIGN: An analysis of the geometric data of the lumbar spine in Chinese men. Lateral radiographs were obtained of 16 men in the upright position to a trunk flexion of 90 degrees in 30 degrees increments. OBJECTIVES: To establish reference data concerning the geometry of the lumbar spine for various degrees of trunk flexion. SUMMARY OF BACKGROUND DATA: In previous studies, the morphometry and alignment of the lumbar spine have been investigated. Reports of systematic analyses of the lumbar spine in trunk flexion have lacked adequate radiographic data. Moreover, few studies have focused on measuring lumbar spine geometric data in Chinese individuals. METHODS: A total of 67 landmarks on each radiograph were identified. They were marked by investigators and digitized using a HyperSpace digitizing system (V.17: Mira Imaging Inc., Salt Lake City, UT). The geometric configuration of the vertebrae and discs then was derived from the digitized points. RESULTS: The dimensions of the vertebrae and disc on the lumbar spine obtained in this study were similar to those of previous studies. The motion of the lumbosacral spine had the greatest contribution in trunk flexion, approximately 90% (i.e., rotating at the rate of 9 degrees for each 10 degrees of trunk flexion) when the trunk was flexed from 30 degrees to 60 degrees. After that, the hips were dominant in accomplishing the trunk flexion from 60 degrees to horizontal. This motion patterns may be useful for making clinical diagnoses of lumbar function in Chinese men. CONCLUSIONS: No obvious interracial differences were found in the geometric data found in this study, which suggests that morphometric data obtained from Caucasian individuals may be applied to Chinese patients for clinical purposes.

Adult↗
PubMed1988

Morphometric analysis of the thoracolumbar and lumbar pedicles, anatomo-radiologic study.

The geometric properties of 380 vertebral pedicles, ranging from T6 to L5, were analysed. Measurement were made directly from the specimens as well as from roentgenograms. The parameters considered were the horizontal and vertical pedicle diameters, pedicle angles in the transverse and sagittal planes, and the transverse and anteroposterior widths of the spinal canal and vertebral body. In addition, the length of the pedicle and the length of the pedicle including the vertebral body to the anterior cortex were measured along the pedicle axis and in a line parallel to the midline of the vertebral body. The smallest horizontal and vertical pedicle diameters were found at vertebral levels from T6 to T10. The correlation between pedicle widths and screw dimensions is obvious. In the transverse plane, the pedicle angle diverged from the vertebral body at all levels, except at T12. In the sagittal plane, the pedicles were angled cephalad from T6 to L3 and slightly caudally at L5. Knowledge of the length of the pedicle to the anterior vertebral body cortex is very important for safe screw purchase. At all levels, with the exception of T12, this length was found to be significantly greater along the pedicle axis than along a line parallel to the midline of the vertebral body.

Adult↗
PubMedDate not supplied

Morphometric analysis of the anastomosing arteriolar network in cat sartorius muscle.

Topological and geometrical characteristics of the anastomotic arteriolar network in cat sartorius muscle were studied. The vessels were dilated and filled with gelatin-ink solution and the muscle cleared with methylsalicylate. The analysis was done on 11 muscles and included 2297 vascular segments and 772 vascular loops classified according to their position within the network. On average, each muscle had 644 transverse arterioles arising from the anastomotic vessels. The length of vascular segments close to feeding arteries was greater than those located in the central region, while the number of transverse arterioles per unit length of arcade vessel showed an opposite tendency. Most vessel orders had similar diameters, except for the segments at the periphery of the muscle, which were significantly larger. No correlation was found between vessel length and diameter. Vascular loops located in the central part of the network were smaller, as assessed by area, perimeter, number of segments, segment length and number of branches. The variability of the parameters between muscles was smaller than variability within each muscle. We concluded that, in addition to the parameters previously reported, quantitative descriptions of anastomotic networks may be enhanced by considering certain topological aspects of microvessels. The separation of segments and loops according to the position in the network may reveal differences between muscles of different sizes and functions which would not be detected if the vessels were considered as a single group.

Animals↗
PubMed2001

Cardiac function, microvascular structure, and capillary hematocrit in hearts of polycythemic rats.

The effect of polycythemia on the coronary microcirculation was studied in young male rats. Two experimental models of polycythemia were employed: cobalt-induced polycythemia, which mimics hypoxia-induced changes, and erythropoietin-induced polycythemia, which circumvents these changes. In both models, baseline left ventricular function was normal, whereas maximal systolic and developed pressures were decreased. In cobalt-treated rats the left ventricular functional reserve was also compromised. Morphometric analysis of the left ventricle confirmed previously described improved geometric conditions for oxygen supply at the distal portions of capillaries (smaller domain areas and shorter capillary segments). In cobalt-treated but not in erythropoietin-treated rats, increased capillary angiogenesis was also detected. In the hearts from rats with both types of polycythemia, a small but significant increase in the formation of arterioles was found. Capillary linear hematocrit was within the normal range in both types of polycythemia despite sizeable increases in systemic hematocrit. Significant differences in red blood cell distribution within capillaries were found between proximal and distal portions in all experimental groups.

Animals↗