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Results for “computational morphology”

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At least 343 records · Page 19Linked to original sources

PubMed2000

Regional distribution of gas and tissue in acute respiratory distress syndrome. III. Consequences for the effects of positive end-expiratory pressure. CT Scan ARDS Study Group. Adult Respiratory Distress Syndrome.

OBJECTIVE: To determine whether differences in lung morphology assessed by computed tomography (CT) affect the response to positive end-expiratory pressure (PEEP). DESIGN: Prospective study over a 53-month period. SETTING: Fourteen-bed surgical intensive care unit of a university hospital. PATIENTS AND PARTICIPANTS: Seventy-one consecutive patients with early adult respiratory distress syndrome (ARDS). MEASUREMENTS AND RESULTS: Fast spiral thoracic CT was performed at zero end-expiratory pressure (ZEEP) and after implementation of PEEP 10 cmH2O. Hemodynamic and respiratory parameters were measured in both conditions. PEEP-induced overdistension and alveolar recruitment were quantified by specifically designed software (Lungview). Overdistension occurred only in the upper lobes and was significantly correlated with the volume of lung, characterized by a CT attenuation ranging between -900 and -800 HU in ZEEP conditions. Cardiorespiratory effects of PEEP were similar in patients with primary and secondary ARDS. PEEP-induced alveolar recruitment of the lower lobes was significantly correlated with their lung volume (gas + tissue) at functional residual capacity. PEEP-induced alveolar recruitment was greater in the lower lobes with "inflammatory atelectasis" than in the lower lobes with "mechanical atelectasis." Lung morphology as assessed by CT markedly influenced the effects of PEEP: in patients with diffuse CT attenuations PEEP induced a marked alveolar recruitment without overdistension, whereas in patients with lobar CT attenuations PEEP induced a mild alveolar recruitment associated with overdistension of previously aerated lung areas. These results can be explained by the uneven distribution of regional compliance characterizing patients with lobar CT attenuations (compliant upper lobes and stiff lower lobes) contrasting with a more even distribution of regional compliances observed in patients with diffuse CT attenuations. CONCLUSIONS: In patients with ARDS, the cardiorespiratory effects of PEEP are affected by lung morphology rather than by the cause of the lung injury (primary versus secondary ARDS). The regional distribution of the loss of aeration and the type of atelectasis -- "mechanical" with a massive loss of lung volume, or "inflammatory" with a preservation of lung volume-- characterizing the lower lobes are the main determinants of the cardiorespiratory effects of PEEP.

Analysis of Variance↗

PubMed1998

SPECT bone scanning of the spine.

Radionuclide bone scanning is a well accepted method for uncovering a variety of bony lesions including abnormalities of vertebral bodies that may be causing spinal pain. Single photon emission computed tomography (SPECT) is especially useful in such an evaluation because it allows for precise localization of a lesion to the vertebral body, disc space, or vertebral arch. This anatomic distinction is necessary in order to accurately diagnose the underlying condition detected by the bone scan. Most bony abnormalities result in focal areas of abnormal tracer activity but do not affect all components of a vertebra with equal frequency nor have a random pattern of involvement. Vertebral diseases tend to conform to predictable patterns that can be more readily identified by SPECT than planar imaging. Metastatic tumors commonly involve the posterior portion of the vertebral body, often in combination with a pedicle. Extensive abnormalities involving the vertebral body and vertebral arch, but sparing the pedicles, are usually benign as are lesions isolated to articular facets and lamina or disc space. Postoperative patients have additional potential problems including pseudarthrosis and complications following use of internal fixation devices including pedicle screws. Nuclear medicine physicians must speak the language of their referring physicians who are anatomically oriented and used to the exquisite morphologic detail of computed tomography (CT) and magnetic resonance imaging (MRI). SPECT allows for greater anatomic information compared with planar imaging as well as straightforward comparison with other tomographic-based studies such as CT and MRI.

Humans↗

PubMed2006

Creation and reduction of a morphologically detailed model of a leech heart interneuron.

Conductance-based neuron models aid in understanding the role intrinsic and synaptic currents play in producing neuronal activity. Incorporating morphological detail into a model allows for additional analysis of nonhomogeneous distributions of active and synaptic conductances, as well as spatial segregation of electrical events. We developed a morphologically detailed "Full Model" of a leech heart interneuron that replicates reasonably well intracellular recordings from these interneurons. However, it constitutes hundreds of compartments, each increasing parameter space and simulation time. To reduce the number of compartments of the Full Model, while preserving conductance densities and distributions, its compartments were grouped into functional groups that each share identical conductance densities. Each functional group was sequentially reduced to one or two compartments, preserving surface area, conductance densities, and its contribution to input resistance. As a result, the input resistance and membrane time constant were preserved. The axial resistances of several compartments were rescaled to match the amplitude of synaptic currents and low-threshold calcium currents and the shape of action potentials to those in the Full Model. This reduced model, with intrinsic conductances, matched the activity of the Full Model for a variety of simulated current-clamp and voltage-clamp data. Because surface area and conductance distribution of the functional groups of the Full Model were maintained, parameter changes introduced into the reduced model can be directly translated to the Full Model. Thus our computationally efficient reduced morphology model can be used as a tool for exploring the parameter space of the Full Model and in network simulations.

Action Potentials↗

PubMed1990

Myosin II heavy chain null mutant of Dictyostelium exhibits defective intracellular particle movement.

Both cellular motility and intracellular particle movement are compared between normal Dictyostelium amebae of strain AX4 and amebae of a myosin II heavy chain null mutant, HS2215, using the computer assisted "Dynamic Morphology System." In AX4 cells rapidly translocating in buffer, cytoplasmic expansion is apical and the majority of intracellular particles move anteriorly, towards the site of expansion. When these cells are pulsed with 10(-6) M cAMP, the peak concentration of the natural cAMP wave, cells stop translocating and average particle velocity decreases threefold within 2-4 s after cAMP addition. After 8 s, there is a partial rebound both in cytoplasmic expansion and particle velocity, but in both cases, original apical polarity is lost. In HS2215 cells in buffer, both cellular translocation and average particle velocity are already at the depressed levels observed in normal cells immediately after cAMP addition, and no anterior bias is observed in either the direction of cytoplasmic expansion or the direction of particle movement. The addition of cAMP to myosin-minus cells results in no additional effect. The results demonstrate that myosin II is necessary for (a) the rapid rate of intracellular particle movement, (b) the biased anterior directionality of particle movement, and (c) the rapid inhibition of particle movement by cAMP.

Biological Transport↗

PubMed1991

Cell behavior and actomyosin organization in Dictyostelium during substrate exploration.

The behavior of individual Dictyostelium amebae was quantitatively analyzed with the computer-assisted "Dynamic Morphology System" (Soll, Voss, Varnum-Finney and Wessels, (1988) J. Cell. Biochem., 37: 177-192.). The same amoebae were then fixed and analyzed for filamentous (F-) actin and myosin (myosin-II, or "conventional" myosin) by fluorescence microscopy using the "agar-overlay method" (Yumura, and Fukui (1985) Nature, 314: 194-196.). This procedure provides a novel description of the behavior and morphometric changes preceding the static analysis of cytoskeletal organization in the same cell. It is demonstrated that when translocating cells make contact with an etched-smooth glass interface, 14% cross the interface, 20% either reverse direction or migrate along the interface, and the remaining 45% stay at the site. Cells contacting the interface from the smooth or etched side show equivalent behavioral responses. Upon contact with the interface, they project numerous lamellipodia and pseudopodia. While the lamellipodial projections exhibit cycles of spreading and retraction, the pseudopodia show lateral scanning motion, analogous to "substrate exploration" in fibroblasts (Albrecht-Buehler (1976) J. Cell Biol., 69: 275-286.). F-actin is localized in the lamellipodia and pseudopodia of amoebae contacting the interface. There is also discernable cortical F-actin, while conventional myosin appears to be excluded from the cortex and dispersed throughout the cytoplasm. The myosin displays a transient filamentous lattice at the base of newly forming lamellipodia. The ultrastructural study suggests that the new lamellipodia are formed on the dorsal surface and subsequently make contact with the substrate, indicating the dorsoventral sequence of polarity of the motile/sensory cellular organs. The present study demonstrates substrate exploration in Dictyostelium amoebae, and suggests its coupling to dynamic reorganization of the actomyosin cytoskeleton. The possible role of single-headed small myosin(s) (myosin-I, or mini-myosin) is discussed.

Actomyosin↗

PubMed1976

The morphological classification of red cells using an image analysing computer.

Image analysis provides a potential method for automation in the examination of blood films. In order to assess the applicability of this technique to red cell morphology, a scheme has been defined for the classification of red cells into six categories, namely, round cells, elongated cells, tear drop poikilocytes, helmet cells, irregular cells and spherocytes. A study was carried out to determine the consistency which observers classified red cells according to this scheme. Measurements of area, perimeter, maximum diameter and integrated optical denisty of fixed, Romanowsky-stained red cells were made using an image analysing computer. A multivariate classifier based on parameters derived from these measurements, namely cell area and the quotients of integrated density over area, area over the square of perimeter and perimeter over maximum diameter was also used to classify red cells into the above categories. It was found that the inherent error of the machine-based classifier was of the same order as the degree of inconsistency encoutered between trained observers. The significance of these findings is discussed.

Computers↗

PubMed1998

[The data-base including digitized morphologies for clinical testing of bone marrow samples using personal computer].

Clinical testing of bone marrow is essential for diagnosis and treatment of hematopoietic disorder. It is sometimes difficult to provide an accurate morphological explanation of bone marrow cells in the reports. Various methods, such as detailed descriptions or sketches of the cells have been attempted to accurately describe the results to clinicians. However, these descriptions and sketches may vary depending on the individual. To resolve this problem, a data-base including digitized microscopic examinations using a personal computer for tested bone marrow samples has been developed. This system enables accurate reporting of cellular morphology by printing out colored figures. Moreover, chronological data may be easily displayed and reviewed on the screen. To assess those functions and the quality of print outs showing cellular morphologies, a questionnaire survey evaluating this system was conducted. As a result, a fairly good assessment was given to the print outs showing various morphologies including leukemic cells, infiltrated tumor cells and some cytochemical staining methods (peroxidase, esterase and periodic acid Schiff reaction). However, a few respondents suggested that expression color in print outs of minute morphologies such as chromatin strands, nucleoli and a few azurophil granules were incomplete. As for data-base functions, responses to the questionnaire were fairly good. In conclusion, this attempt is very useful and practical for clinical testing of bone marrow samples.

Bone Marrow Cells↗

PubMed1997

Effect of retinoic acid on prostatic development.

BACKGROUND AND METHODS: To assess the effect of retinoids on prostatic ductal branching morphogenesis, anterior prostates from newborn rats were cultured under serum-free conditions for 6 days in the presence of testosterone (10(-8) mM) plus 13-cis-retinoic acid (13-cis-RA), all-trans-retinoic acid (at-RA), or N-4-hydroxyphenyl-retinamide (4-HPR). Measures of morphologic complexity were computed and compared between specimens of different treatment groups. RESULTS: Prostatic ductal growth and branching were inhibited in a dose-dependent fashion by both 13-cis-RA and at-RA, but not by 4-HPR. This inhibitory effect of 13-cis-RA was reversible, as the prostatic ducts resumed branching and growth after removal of retinoic acid from the culture medium. Using reverse transcription polymerase chain reaction, we then investigated the expression of nuclear receptor genes for retinoic acid. CONCLUSIONS: This showed the presence of RAR-beta and RAR-gamma in the 0-day prostate, suggesting that the effects of these retinoids on ductal morphogenesis may be via these receptors.

Animals↗

PubMed2001

Two classes of visual motion sensitive interneurons differ in direction and velocity dependency of in vivo calcium dynamics.

Neurons exploit both membrane biophysics and biochemical pathways of the cytoplasm for dendritic integration of synaptic input. Here we quantify the tuning discrepancy of electrical and chemical response properties in two kinds of neurons using in vivo visual stimulation. Dendritic calcium concentration changes and membrane potential of visual interneurons of the fly were measured in response to visual motion stimuli. Two classes of tangential cells of the lobula plate were compared, HS-cells and CH-cells. Both neuronal classes are known to receive retinotopic input with similar properties, yet they differ in morphology, physiology, and computational context. Velocity tuning and directional selectivity of the electrical and calcium responses were investigated. In both cell classes, motion-induced calcium accumulation did not follow the early transient of the membrane potential. Rather, the amplitude of the calcium signal seemed to be related to the late component of the depolarization, where it was close to a steady state. Electrical and calcium responses differed with respect to their velocity tuning in CH-cells, but not in HS-cells. Furthermore, velocity tuning of the calcium response, but not of the electrical response differed between neuronal classes. While null-direction motion caused hyperpolarization in both classes, this led to a calcium decrement in CH-cells, but had no effect on the calcium signal in HS-cells, not even when calcium levels had been raised by a preceding excitatory motion stimulus. Finally, the voltage-[Ca2+]i-relationship for motion-induced, transient potential changes was steeper and less rectifying in CH-cells than in HS-cells. These results represent an example of dendritic information processing in vivo, where two neuronal classes respond to identical stimuli with a similar electrical response, but differing calcium response. This highlights the capacity of neurons to segregate two response components.

Animals↗

PubMed2002

Contribution of T-type VDCC to TEA-induced long-term synaptic modification in hippocampal CA1 and dentate gyrus.

We have previously reported that exposure to the K+ channel blocker tetraethylammonium (TEA), 25 mM, induces long-term potentiation (LTP) in CA1, but not in the dentate gyrus (DG), of the rat hippocampal slice. During TEA application, stimulation of excitatory afferents results in a strong depolarizing potential after the fast excitatory postsynaptic potential (EPSP) in CA1, but not in DG. We hypothesized that the differential effect of TEA on long-term synaptic modification in CA1 and DG results from different levels of TEA-elicited depolarization in the two cell types. Additional pharmacological studies showed that blockade of T-type voltage-dependent calcium channels (VDCCs) decreased both the magnitude of LTP and the late, depolarizing potential in CA1. Blockade of L-type VDCCs had no such effect. Using computer models of morphologically reconstructed CA1 pyramidal cells and DG granule cells, we tested our hypothesis by simulating the relative intracellular Ca2+ accumulation and membrane potential changes mediated by T-type and L-type VDCCs. Simulation results using pyramidal cell models showed that, with decreased maximum conductance of TEA-sensitive potassium channels, synaptic inputs elicited strong depolarizing potentials similar to those observed with intracellular recording. During this depolarization, VDCCs were opened and resulted in a large intracellular Ca2+ accumulation that presumably caused LTP. When T-type VDCCs were blocked, the magnitudes of both the Ca2+ accumulation and the late depolarizing potential were decreased substantially. Simulated blockade of L-type VDCCs had only a minor effect. Together, our modeling and experimental studies indicate that T-type VDCCs, rather than L-type VDCCs, are primarily responsible for facilitating the depolarizing potential caused by TEA and for the consequent Ca2+ influx. Thus, our findings strongly suggest that the induction of TEA-LTP in CA1 depends primarily on T-type, rather than L-type, VDCCs. Simulation results using modeled granule cells suggests that the failure of TEA to induce LTP in DG is partly due to a low density of T-type VDCCs in granule cell membranes.

Animals↗

PubMed1991

Invasion of Rous sarcoma virus-transformed retinal cells: role of cell motility.

Transformation of retinal neuro-epithelial cells by Rous sarcoma virus (RSV) leads to many alterations in cell phenotype, including changes in cell movement, cell-cell adhesion and protease secretion. To define and quantitate the alterations in cell movement, we analyzed video recordings of cultured cells using the computer-assisted Dynamic Morphology System (DMS). Control neuro-epithelial cells showed very low levels of translocation and membrane activity. After transformation, neuro-epithelial cells exhibited increased membrane activity, although directed cell translocation remained low. Developing retinas also contain a small proportion of Müller glial cells, which were purified by repeated passaging of control cultures. In contrast to neuro-epithelial cells, both control and RSV-transformed glial cells showed high levels of translocation and membrane activity. To analyze how different kinds of cell movement affect invasive behavior, we compared the ability of control and RSV-transformed cells to invade the chorio-allantoic membrane of developing chicken embryos. Control neuro-epithelial cells were not invasive. RSV-transformed neuro-epithelial cells, which showed low levels of translocation as revealed by DMS, were invasive. Similarly, RSV-transformed glial cells were invasive while control glial cells, which translocated, were not invasive. These results suggest that high levels of cell translocation are not necessary for invasion. In addition, the results suggest that elevated membrane activity in neuro-epithelial cells may be important for their invasion.

Allantois↗

PubMed1993

The value of magnetic stimulation in the diagnosis of radiculopathies.

We studied 42 patients with cervical and lumbar radiculopathies using magnetic stimulation. Prolonged latencies following magnetic stimulation of the brain, the paravertebral spinal nerve, or both, showed a highly significant correlation with muscle weakness in clinical testing (24 of 26 patients with weakness had pathological motor evoked potentials) as well as with spontaneous activity of the target muscles in needle electromyography (24 of 25 subjects). The determination of both the central and the peripheral motor conduction time was found to be essential in patients with radiculopathies, because different patterns of latency changes correlated with different morphological results in computed tomography: in patients diagnosed as having a lateral compression of the nerve root the peripheral nerve latency was delayed; whereas, in patients with more medially localized herniations, a prolonged central motor latency was the most frequent finding. This study posits that combined magnetic stimulation of the brain and nerve root is an effective and painless technique for the noninvasive evaluation of nerve root function.

Adult↗

PubMed2004

ROC analysis of an erythroblast morphologic scoring system to improve identification of fetal cells in maternal blood.

OBJECTIVES: Nucleated red blood cells are used in research settings as a target cell type for investigations of noninvasive prenatal diagnosis, and these cells have a characteristic nuclear morphology and hemoglobin staining pattern that makes them distinguishable from maternal cells. Recently, we developed an erythroblast scoring system based on these characteristics. Here, we employ statistical analyses to further characterize the utility of this scoring system. METHODS: A total of 170 nucleated red blood cells isolated from peripheral blood of four women undergoing elective termination of a trisomy 21 male fetus were analyzed. Each of the four scoring system parameters, whose values range from 0 to 3 points, served as an independent variable to determine its significance for the correct identification of a cell as fetal or maternal. A logistic regression was used as a multivariable statistical tool. RESULTS: Forty-four patterns of the four parameters were found in the overall series. Some patterns were exclusively associated with maternal cells (e.g. 1-1-1-1 and 1-1-2-2), and others were exclusively associated with fetal cells (e.g. 3-2-2-2 and 3-2-3-2). A detection rate of 73.9% at a false-positive rate of 5% resulted from a random simulation model performed with a 1:5 case:control matched set. The variables most predictive of a cell being fetal were gamma hemoglobin staining intensity of cytoplasm and nuclear roundness. CONCLUSIONS: The modified scoring system presented here improves upon the previously reported, unmodified erythroblast scoring system. These statistical analyses suggest that the scoring system is a promising method that aids in distinguishing fetal and maternal NRBCs for prenatal diagnostic applications and that it may be amenable to automated microscopy by applying the discrete morphological parameters as computational classifiers.

Cell Nucleus↗

PubMed1985

Outcome in children with severe head injuries.

We present a series of 56 children who suffered severe head injuries, with a Glasgow Coma Score (GCS) of less than 8. The cases were classified according to the type of morphologic lesion on computed tomography (CT) scan. Intracranial pressure (ICP) was monitored in all children in this series. A protocol that included artificial ventilation and other measures of treatment for intracranial hypertension was applied. Results were analyzed according to age, type of lesion, and ICP. The usefulness of the ICP recording and of obtaining a correct classification of lesions using the CT scan is emphasized.

Adolescent↗

PubMed2005

Right intrahepatic pseudocyst following acute pancreatitis: an unusual location after acute pancreatitis.

The location of a pseudocyst (PC) in the liver is an exceptional event, and intrahepatic PCs are mainly located in the left lobe. We report here a case of right intrahepatic PC following acute pancreatitis associated with cystic (aberrant pancreatic) dystrophy of the duodenal wall (CDDW) and chronic pancreatitis. Morphological assessment (ultrasound, computed tomography [CT] scan, and cholangio-magnetic resonance imaging [MRI]) revealed a 10-cm right intrahepatic collection and rupture of the main pancreatic duct. Percutaneous puncture permitted us to detect a high level of amylase in the collection, confirming the diagnosis of intrahepatic PC. Surgical drainage concomitant with pancreatico-duodenectomy for the treatment of CDDW resulted in disappearance of the collection. The mechanism involved in this patient was rupture of the pancreatic duct in the retroperitoneal cavity and erosion reaching the right hepatic parenchyma. Although intrahepatic PCs are rare, the diagnosis of intrahepatic PC complicating acute pancreatitis can be confirmed by a high level of amylase in the collection. Asymptomatic intrahepatic PCs can be treated conservatively, and symptomatic intrahepatic PCs can be managed either transcutaneously or surgically.

Acute Disease↗

PubMed1988

Cell motility and chemotaxis in Dictyostelium amebae lacking myosin heavy chain.

Dictyostelium amebae have been engineered by homologous recombination of a truncated copy of the myosin heavy chain gene (heavy meromyosin (HMM) cells) and by transformation with a vector encoding an antisense RNA to myosin heavy chain mRNA (mhcA cells) so that they lack native myosin heavy chain protein. In the former case, cells synthesize only the heavy meromyosin portion of the protein and in the latter case they synthesize negligible amounts of the protein. Surprisingly, it was demonstrated that both cell lines are viable and motile. In order to compare the motility of these cells with normal cells, the newly developed computer-assisted Dynamic Morphology System (DMS) was employed. The results demonstrate that the average HMM or mhcA ameba moves at a rate of translocation less than half that of normal cells. It is rounder and less polar than a normal cell, and exhibits a rate of cytoplasmic expansion and contraction roughly half that of normal cells. In a spatial gradient of cAMP, the average ameba of HMM or mhcA exhibits a chemotactic index of +0.10 or less, compared to the chemotactic index of +0.50 exhibited by normal cells. Finally, the initial area, rate of expansion, and final area of pseudopods are roughly half that of normal cells. The five fastest HMM amebae (out of 35 analyzed in detail) moved at an average rate of translocation equal to that of normal amebae, and exhibited an average chemotactic index of +0.34. In addition, the average rate of cytoplasmic flow in fast HMM cells was equal to that of the average normal ameba. However, fast HMM amebae still exhibited the same defects in pseudopod formation that were exhibited by the entire HMM cell population. These results suggest that myosin heavy chain is involved in the "fine tuning" and efficiency of pseudopod formation, but is not essential for the basic behavior of pseudopod expansion.

Actins↗

PubMed1984

Nuclear magnetic resonance in schizophrenia: a preliminary study.

Nuclear magnetic resonance (NMR) scans were performed in nine patients with schizophrenia and five control subjects. NMR scans allowed multiple-plane views of the brains of schizophrenic patients and demonstrated much greater detail of morphological structure than computed tomographic (CT) scans. This small sample of subjects, however, showed no significant differences in several quantitative measurements between schizophrenic patients and control subjects. Problems in the interpretation of image intensity measures of NMR scans are discussed.

Adult↗

PubMed1985

Inhibition and acceleration of erythrocyte aggregation induced by small macromolecules.

The aggregation (especially the 'rouleau' formation) of human erythrocytes induced by polysaccharide and polyglutamic acid was quantitatively examined by using a low-shear rheoscope combined with a television image analyzer and a computer. (1) The morphological characteristics of rouleaux induced by these macromolecules are presented. (2) Polysaccharides with high molecular weights of 70 400 and 494 000 and poly(glutamic acids) with weights of 50 000 and 66 000 formed the rouleaux (then the three-dimensional aggregates). But polysaccharides with the low molecular weights of 10 300 and 42 500 and poly(glutamic acids) with weights of 8000 and 20 000 did not. The dependences of the velocity of rouleau formation on the macromolecule concentration and on the shear rate are shown. (3) The erythrocyte aggregation induced by high-molecular-weight polysaccharides was inhibited by low-molecular-weight polysaccharides and glucose, but was not affected by low-molecular-weight poly(glutamic acids). (4) The aggregation induced by high-molecular-weight poly(glutamic acids) was inhibited by poly(glutamic acid) with a molecular weight of 8000, but was accelerated by that of 20 000. The poly(glutamic acid)-induced aggregation was not affected by low-molecular-weight polysaccharides. (5) The stereochemical structure-dependent interaction (or the mode of bridging) of macromolecules with erythrocytes was stressed for the mechanism of erythrocyte aggregation.

Adult↗