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At least 1,495 records · Page 83Linked to original sources
PubMed2004

Mapping land-cover and mangrove structures with remote sensing techniques: a contribution to a synoptic GIS in support of coastal management in North Brazil.

This article deals with the development and application of a cartographic database for a synoptic Geographic Information System (GIS). Its purpose is the storage and evaluation of the heterogeneous datasets of the interdisciplinary scientific research program MADAM (Mangrove Dynamics and Management), which aims to develop recommendations for a tailored integrated coastal management scheme for the mangrove ecosystem at Braganca (North Brazil). The article describes the integration of remote sensing data, aerial photographs, as well as point data provided by fieldwork from different scientific fields. Using various innovative processing techniques and different scale-resolution levels, an assessment of temporal-spatial changes of the mangrove peninsula and the adjacent rural socioeconomic impact area, the type of mangrove structure, as well as a land-use cover analyses was undertaken. The definition of the spatial level of detail was found to be a major issue in the development of the GIS, as well as during the processing and analysis procedures. A division between strong and weak patterns in the mangrove ecosystem could be made, which implies different management measures and sets of specific interdisciplinary studies and monitoring at hierarchical scales.

Brazil↗
PubMed2001

Changes in ubiquitin conjugates and Hsp72 levels during arm regeneration in echinoderms.

All organisms show a common defensive mechanism that results in the expression of conserved heat shock proteins (Hsps). These proteins function in a wide range of stressful conditions. We have monitored their levels in species of regenerating echinoderms with different mechanisms of regeneration and from different geographical locations. The effect of an artificial higher temperature on expression of Hsps was also studied. Two stress proteins (Hsp72 and ubiquitin) that are important in processes such as development and protein degradation were investigated. Using Western blot analysis and immunocytochemistry, we found significant changes in the level (Hsp72) and pattern of conjugation (ubiquitin) that corresponded with the repair phase (early regenerative stages) and with the later growth and regeneration of new tissues. Animals from the intertidal environment showed a distinctly sustained expression pattern of Hsp72 compared with benthic animals which suggests a functionally adaptative and dynamic stress response program.

Journal Article↗
PubMed1993

Mechanisms of supraspinal correction of locomotor activity generator.

In experiments on immobilized decerebrate cats, data about reorganization of efferent activity parameters of the forelimb and hindlimb locomotor generators evoked by electrical stimulation of descending systems were obtained. The generators controlling both forelimb and hindlimb locomotor movements were found to be characterized by the existence of stable states at which total influence of different descending systems on these generators was extremely limited. These data enable us to conclude that the sense of activity reorganization in locomotor generators of both forelimb and hindlimb under the influence of descending system signals is in bringing the motor program to a dynamic relation with supraspinal inflow, where a sufficient degree of limitation and balancing of the influences of corresponding descending systems on the interneuronal nets, determining time and phase characteristics of these generators, is ensured. Possible mechanisms of realization of this interaction between descending signals and locomotor activity generators are discussed.

Animals↗
PubMed2006

Preconditioning principles for preventing sports injuries in adolescents and children.

Preseason preconditioning can be accomplished well over a 4-week period with a mandatory period of rest as we have discussed. Athletic participation must be guided by a gradual increase of skills performance in the child assessed after a responsible preconditioning program applying physiologic parameters as outlined. Clearly, designing a preconditioning program is a dynamic process when accounting for all the variables in training discussed so far. Despite the physiologic demands of sport and training, we still need to acknowledge the psychologic maturity and welfare of the child so as to ensure that the sport environment is a wholesome and emotionally rewarding experience.

Adolescent↗
PubMed1992

Computer modelling of glycolipids at membrane surfaces.

Interactions of membrane anchored molecules such as glycolipids with a membrane surface are important in determining headgroup conformation. It is therefore essential to represent these membrane surface interactions in molecular modeling studies of glycolipids and other membrane bound molecules. We introduce here an energy term that represents the interaction of molecules with a membrane bilayer. This membrane interaction energy term has been added to the potential energy function of a molecular dynamics and mechanics program and has been parameterized using partition coefficients between an aqueous solution and a vesicular membrane for two model glycolipids.

Biophysical Phenomena↗
PubMed1998

Three-dimensional structure of binase in solution.

We present the spatial structure of binase, a small extracellular ribonuclease, derived from 1H-NMR* data in aqueous solution. The total of 20 structures were obtained via torsion angle dynamics using DYANA program with experimental NOE and hydrogen bond distance constraints and phi and chi1 dihedral angle constraints. The final structures were energy minimised with ECEPP/2 potential in FANTOM program. Binase consists of three alpha-helices in N-terminal part (residues 6-16, 26-32 and 41-44), five-stranded antiparallel beta-sheet in C-terminal part (residues 51-55, 70-75, 86-90, 94-99 and 104-108) and two-stranded parallel beta-sheet (residues 22-24 and 49-51). Three loops (residues 36-39, 56-67 and 76-83), which play significant role in biological functioning of binase, are flexible in solution. The differences between binase and barnase spatial structures in solution explain the differences in thermostability of binase, barnase and their hybrids.

Bacillus↗
PubMedDate not supplied

Cellular adaptations of the myocardium to chronic exercise.

The heart responds positively to programs of chronic dynamic exercise. Hallmark adaptations of the heart include a training bradycardia, increases in end-diastolic dimension and maximal stroke volume, and a general improvement in ventricular performance and contractile function. Of considerable clinical significance are the general observations that chronic exercise renders the myocardium less susceptible to the deleterious effects of acute ischemic episodes and can effectively prevent and/or reverse many of the cardiac functional deficits that are known to occur in settings of chronic hypertension, advanced age, and myocardial infarction. In the text that follows, information gathered over the last 25 to 30 years has been reviewed in an attempt to identify cellular myocardial adaptations, both known and hypothetical, that are responsible for the observed effects of chronic dynamic exercise on the function and morphology of the heart in both normal and selected pathophysiologic settings. Finally, a variety of unresolved issues regarding the ability of chronic exercise to elicit adaptive cardiocyte responses has been identified. In so doing, it is hoped that creative thought and future work in the area will be stimulated.

Adaptation, Physiological↗
PubMed1998

Solution structure of murine macrophage inflammatory protein-2.

The solution structure of murine macrophage inflammatory protein-2 (MIP-2), a heparin-binding chemokine that is secreted in response to inflammatory stimuli, has been determined using two-dimensional homonuclear and heteronuclear NMR spectroscopy. Structure calculations were carried out by means of torsion-angle molecular dynamics using the program X-PLOR. The structure is based on a total of 2390 experimental restraints, comprising 2246 NOE-derived distance restraints, 44 distance restraints for 22 hydrogen bonds, and 100 torsion angle restraints. The structure is well-defined, with the backbone (N, Calpha, C) and heavy atom atomic rms distribution about the mean coordinates for residues 9-69 of the dimer being 0.57 +/- 0.16 A and 0.96 +/- 0.12 A, respectively. The N- and C-terminal residues (1-8 and 70-73, respectively) are disordered. The overall structure of the MIP-2 dimer is similar to that reported previously for the NMR structures of MGSA and IL-8 and consists of a six-stranded antiparallel beta-sheet (residue 25-29, 39-44, and 48-52) packed against two C-terminal antiparallel alpha-helices. A best fit superposition of the NMR structure of MIP-2 on the structures of MGSA, NAP-2, and the NMR and X-ray structures of IL-8 are 1.11, 1.02, 1.27, and 1.19 A, respectively, for the monomers, and 1.28, 1.10, 1.55, and 1.36 A, respectively, for the dimers (IL-8 residues 7-14 and 16-67, NAP-2 residues 25-84). At the tertiary level, the main differences between the MIP-2 solution structure and the IL-8, MGSA, and NAP-2 structures involve the N-terminal loop between residues 9-23 and the loops formed by residues 30-38 and residues 53-58. At the quaternary level, the difference between MIP-2 and IL-8, MGSA, or NAP-2 results from differing interhelical angles and separations.

Amino Acid Sequence↗
PubMed1996

[Use of MR-controlled laser-induced thermotherapy in recurrent squamous epithelial carcinoma of the head-neck area].

BACKGROUND: The management of patients with recurrent carcinomas of the head and neck that had been treated before by surgery, radiation, and/or chemotherapy presents a considerable problem. The value of the MR-controlled laser-induced thermotherapy (LITT) was analysed as a new palliative treatment modality. METHOD: LITT was used in five patients with recurrent head and neck squamous cell carcinomas, who had undergone established methods of treatment. One patient with a primary laryngeal carcinoma, who refused surgery, was treated by LITT in addition to radiation. A Nd:YAG laser was used to deliver laser light via an applicator directly into the tissue and to produce tumor necrosis. Using two special MR thermosequences (Thermo-TurboFLASH-, modified FLASH-2 D-Sequenfe) the laser process was controlled on line. The necroses were measured by a static and dynamic area calculation program based on a pixel evaluation. RESULTS: The induced tumor necroses ranged from 4 cm3 to 28 cm3. In all cases the MR thermosequences showed a loss of the signal up to 15 mm around the top of the applicator. In the post-interventional T1 sequences with intensified contrast, the coagulation necroses were represented as hypovascular areas. No side effects were seen and five of the patients felt an improvement of clinical symptoms. CONCLUSION: LITT as a minimal invasive, MR-controlled method may be a good alternative in palliative therapy of head and neck carcinomas.

Adult↗
PubMed2002

Symmetry breaking, bifurcations, quasiperiodicity, and chaos due to electric fields in a coupled cell model.

A model for the asymmetric coupling of two oscillatory cells is considered. The coupling between the cells is both through diffusional exchange (symmetric) and through the electromigration of ionic reactant species from one cell to the other (asymmetric) in applied electric fields. The kinetics in each cell are the same and based on the Gray-Scott scheme. Without the electric field, only simple, stable dynamics are seen. The effect of the asymmetry (applying electric fields) is to create a wide variety of stable dynamics, multistability, multiperiodic oscillations, quasiperiodicity and chaos being observed, this complexity in response being more prevalent at weaker coupling rates and at weaker field strengths. The results are obtained using a standard dynamical systems continuation program, though asymptotic results are obtained for strong coupling rates and strong electric fields. These are seen to agree well with the numerically determined values in the appropriate parameter regimes. (c) 2002 American Institute of Physics.

Journal Article↗
PubMed2005

The kinetochore protein Ndc10p is required for spindle stability and cytokinesis in yeast.

The budding yeast kinetochore is comprised of >60 proteins and associates with 120 bp of centromeric (CEN) DNA. Kinetochore proteins are highly dynamic and exhibit programmed cell cycle changes in localization. The CEN-specific histone, Cse4p, is one of a few stable kinetochore components and remains associated with CEN DNA throughout mitosis. In contrast, several other kinetochore proteins have been observed along interpolar microtubules and at the midzone during anaphase. The inner kinetochore protein, Ndc10p, is enriched at the spindle midzone in late anaphase. We show that Ndc10p is transported to the plus-ends of interpolar microtubules at the midzone during anaphase, a process that requires survivin (Bir1p), a member of the aurora kinase (Ipl1p) complex, and Cdc14p phosphatase. In addition, Ndc10p is required for essential non-kinetochore processes during mitosis. Cells lacking functional Ndc10p show defects in spindle stability during anaphase and failure to split the septin ring during cytokinesis. This latter phenotype leads to a cell separation defect in ndc10-1 cells. We propose that Ndc10p plays a direct role in maintaining spindle stability during anaphase and coordinates the completion of cell division after chromosome segregation.

Anaphase↗
PubMed2006

The genomic landscape of histone modifications in human T cells.

To understand the molecular basis that supports the dynamic gene expression programs unique to T cells, we investigated the genomic landscape of activating histone modifications, including histone H3 K9/K14 diacetylation (H3K9acK14ac), H3 K4 trimethylation (H3K4me3), and the repressive histone modification H3 K27 trimethylation (H3K27me3) in primary human T cells. We show that H3K9acK14ac and H3K4me3 are associated with active genes required for T cell function and development, whereas H3K27me3 is associated with silent genes that are involved in development in other cell types. Unexpectedly, we find that 3,330 gene promoters are associated with all of these histone modifications. The gene expression levels are correlated with both the absolute and relative levels of the activating H3K4me3 and the repressive H3K27me3 modifications. Our data reveal that rapidly inducible genes are associated with the H3 acetylation and H3K4me3 modifications, suggesting they assume a chromatin structure poised for activation. In addition, we identified a subpopulation of chromatin regions that are associated with high levels of H3K4me3 and H3K27me3 but low levels of H3K9acK14ac. Therefore, these regions have a distinctive chromatin modification pattern and thus may represent a distinct class of chromatin domains.

Acetylation↗
PubMed2004

An exploratory study of changing occupational injury risk during the closure of industrial operations.

Companies go out of business on a regular basis, and industrial plants close as a result. Various social, economic and interpersonal dynamics accompany such events. Environmental health and safety (EH&S) aspects are not exempt from those dynamics during a programmed closing of a manufacturing operation. How does this condition fit the industrial hygiene paradigm of anticipation, recognition, evaluation and control? This paper describes an exploratory enquiry into the nature of risk to human health and safety associated with the planned closure of a manufacturing operation. As a starting point, the recognition of risk was explored using a qualitative opinion survey of a group of independent EH&S professionals. The survey, reflecting what is often referred to as the 'art' of industrial hygiene, gathered professional impressions of change in potential risk of injury during a hypothetical plant-closing. The results suggested that a plant-closing might be considered a real issue by most EH&S professionals, and pointed specifically to management of personnel behavior, employee satisfaction and outside influences as primary potential sources of increased risk of injury during this final phase of a plant's life. Next, a specific real-world example was considered to evaluate actual change in injury statistics. For this, compensation claim records were examined for a malt beverage manufacturer before and after an official announcement of closure for four geographically distinct North American plants. Risk was evaluated first in terms of the one-monthly and three-monthly rates of injury incidence and then in terms of severity (expressed as cost), based on data derived from compensation claim records as of the month of plant closing. The rate of injury incidence appeared to have increased during plant-closing for one of the plants, but the results were equivocal for the other three plants. On the other hand, when the results were transformed so that the injury incidences were weighted with respect to the cost, the effective impact on the injury rate appeared to increase for three of the plants. Most importantly overall, this paper identifies-for the first time-that there is the potential for increased injury risk during a plant closure phase, and so poses an alert for EH&S professionals and management to implement possible preventative control options in such situations.

Accidents, Occupational↗
PubMed1997

Fundamentals for establishing a risk communication program.

This paper provides a suggested outline for developing a risk communication organizational plan that could be used by a variety of federal, state, or private agencies. Drawing on various techniques presented in the literature and on the authors' insights, suggestions are provided as to how to formulate and convey risk messages. First, the paper provides a few risk communication fundamentals including definitions, the goal of informing vs. influencing, the importance of public participation in risk management, building trust and credibility, the consideration of outrage, and the importance of oral and visual communications. Second, a stepwise approach synthesized by the authors is presented that can be applied in developing a risk communication program. The approach is a 13-step method based on the premise that the risk communication program should be dynamic, flexible, and involve interaction with the public at every possible step.

Communication↗
PubMed1989

Nonunion of acetabular fractures: evaluation with interactive multiplanar CT.

Nonunions involving fractures of the acetabulum are reportedly rare, with few citings and little discussion in the literature. It is possible that acetabular nonunions go undetected because imaging of the acetabulum is difficult by conventional radiography. We report two cases of fracture nonunion involving the weight-bearing surface of the acetabulum diagnosed with the aid of computed tomography (CT) and a newly developed interactive 2D/3D orthotool (copyright and trademark of the Body CT Imaging Laboratory, Department of Radiology, The Johns Hopkins Medical Institutions) that uniquely processes and reformats routine CT data. The interactive 2D/3D orthotool is a sophisticated computer program that allows dynamic viewing of standard multiplanar reconstructions in the axial, coronal, and sagittal planes as well as multiple oblique projections. The 2D/3D orthotool provides on screen correlation of two-dimensional multiplanar images with three-dimensional reconstructions of the pelvis. The authors found this capability ideally suited for studying fractures with off-axis orientation such as those through the acetabular dome, greatly facilitating the diagnosis of nonunion.

Acetabulum↗
PubMed2003

Correlates of continued risky sex among pregnant African American teens: implications for STD prevention.

BACKGROUND: African American adolescent females have been understudied with regard to their continued sexually transmitted disease (STD) risk behavior during pregnancy. Preintervention studies of this population are especially important because the sequelae of STDs during pregnancy can be particularly problematic. OBJECTIVE: This exploratory study identified correlates of engaging in relatively frequent penile-vaginal sex, unprotected by a condom, among inner-city African American adolescents during their first or second trimester of pregnancy. STUDY DESIGN: Baseline data collected as part of an HIV prevention study were used. Adolescents at their first prenatal visit completed a self-administered survey and face-to-face interview. Only adolescents reporting a current boyfriend were included in this exploratory analysis (n = 144). Significant bivariate correlates were assessed for multivariate significance. RESULTS: Significant bivariate correlates of relatively frequent unprotected vaginal sex were older age (P < 0.02), primiparity (P < 0.03), not being enrolled in school (P < 0.02), not residing with at least one parent (P < 0.001), reported infrequent sexual communication (communicating about sex) with the boyfriend (P < 0.01), spending at least 30 hours each week with the boyfriend (P < 0.001), reporting that the age of the current relationship was at least 2 years (P < 0.04), and using marijuana in the past 30 days (P < 0.03). Three correlates retained significance in the multivariate model: not residing with at least one parent (adjusted odds ratio [AOR] = 2.24; P < 0.04), spending at least 30 hours with the boyfriend each week (AOR = 3.70; P < 0.002), and infrequent sexual communication with the boyfriend (AOR = 2.88; P < 0.008). CONCLUSION: Given the potential of STDs to complicate pregnancy outcomes, clinic-based and community-based programs addressing relational dynamics and relational obstacles to safer sex may be warranted, particularly for adolescents not residing with parents.

Adolescent↗
PubMed2007

Risk selection and targeted interventions in community-based control of chlamydia.

PURPOSE OF REVIEW: To describe recent developments in the community-based approach of high-risk groups for Chlamydia trachomatis infection, and to discuss the assessment of impact of selective systematic screening on the transmission of C. trachomatis in the community. RECENT FINDINGS: Two large home-based screening programs in Europe have recently shown that systematic postal screening for C. trachomatis infection is feasible, but certain high-risk groups are poor participators. This underscores the need for risk selection and targeted approaches. A prediction rule has been developed which can assist in identifying high-risk groups and can be used as a tool for (self) selection for screening. The Internet has been shown to be a promising medium to promote chlamydia testing. School-based programs also succeed in including high-risk groups in screening programs. Recently developed dynamic simulation models, which take into account transmission of C. trachomatis, can assist in the development and evaluation of targeted screening strategies. SUMMARY: Chlamydia will not likely be controlled by one standard approach. Risk selection strategies need further development and different systematic approaches at the community level, including postal screening, school-based screening, and the Internet may produce the desired public health effect of decreasing morbidity and reducing the transmission of C. trachomatis in the community.

Chlamydia Infections↗
PubMed2005

Multi-field surface electrode for selective electrical stimulation.

We designed a 24-field array and an on-line control box that selects which and how many of 24 fields will conduct electrical charge during functional electrical stimulation. The array was made using a conductive microfiber textile, silver two-component adhesive, and the conductive ink imprint on the polycarbonate. The control box comprised 24 switches that corresponded one-to-one to the fields on the array. Each field could be made conductive or nonconductive by simple pressing of the corresponding push-button type switch on the control box. We present here representative results of the selectivity of the new electrode measured in three tetraplegic patients during functional electrical stimulation of the forearm. The task was to generate finger flexion and extension with minimal interference of the wrist movement during lateral and palmar grasps. Therapists determined the appropriate pattern that lead to effective grasping, lasting on average 5 min per stimulation channel in the first session. This optimal conductive pattern (size and shape) provided effective finger flexion and extension with minimal wrist flexion/extension and ulnar/radial deviations (<10 degrees). The optimal size and shape of the electrode in all cases had a branched pattern. The selection of the optimal stimulation site was achieved without moving the electrode. The size and shape were reproducible in the same subject from session to session, yet were different from subject to subject. The optimal electrode size and shape changed when subjects pronated and supinated their forearm. The control box includes a program that can dynamically change the number and sites of the conductive fields; hence, it is feasible to use this during functional movements. Subjects learned how to determine the optimal electrode pattern; hence, these electrodes could be effective for home usage.

Electric Stimulation↗