Showing papers by "Drexel University published in 1988"

Hyperthermia Protects Against Light Damage in the Rat Retina

Abstract: An increase in the synthesis of heat shock proteins that is induced in cells in vitro by hyperthermia or other types of metabolic stress correlates with enhanced cell survival upon further stress. To determine if a similar increase in stress tolerance could be elicited in vivo, rats were made hyperthermic, and then their retinas were tested for sensitivity to light damage. This treatment resulted in a marked decrease in photoreceptor degeneration after exposure to bright light as compared to normothermic animals. Concomitant with such protection was an increase in retinal synthesis of three heat shock proteins. Thus, a physiological rise in body temperature enhances the stress tolerance of nerve tissue, perhaps by increasing heat shock protein production.

A Broad-Spectrum Probe for Molecular Epidemiology of Bacteria: Ribosomal RNA

Abstract: We investigated the use of ribosomal RNA (rRNA) as a probe for molecular epidemiology of bacterial pathogens. The chromosomal DNA of Escherichia coli, Pseudomonas cepacia, and nontypable Haemophilus influenzae was digested with EcoRI. Agarose gel electrophoresis, Southern blotting, and hybridization by 32P-labeled rRNA revealed eight to 13 bands. The P. cepacia and H. influenzae banding patterns, observed by using an E. coli rRNA probe, were identical to those produced with homologous rRNA probes. Polymorphism of several hybridization bands distinguished all E. coli isolates, nine of 10 H. influenzae isolates, and seven of eight P. cepacia isolates. Two to four bands were common to all P. cepacia and E. coli isolates. The banding patterns of H. influenzae isolates cultured from the trachea and blood of an infant and from the mother's cervix were identical. These data demonstrate that this method is a widely applicable system for determining the molecular epidemiology of genetically diverse gram-negative organisms.

Singular-Value Decomposition and the Grassberger-Procaccia Algorithm

Abstract: A singular-value decomposition leads to a set of statistically independent variables which are used in the Grassberger-Procaccia algorithm to calculate the correlation dimension of an attractor from a scalar time series. This combination alleviates some of the difficulties associated with each technique when used alone, and can significantly reduce the computational cost of estimating correlation dimensions from a time series.

The mechanical characteristics of the collateral ligaments of the human ankle joint.

Abstract: In the present study, the tensile mechanical properties of all of the collateral ligaments of the human ankle joint were determined, in vitro, from tensile tests conducted on 120 ligaments obtained from 20 fresh lower limbs. The ultimate load of the lateral collateral ligaments increased in an anteroposterior sequence, with the anterior fibulotalar ligament less than the fibulocalcaneal ligament and less than the posterior fibulotalar ligament. For the medial collateral ligaments, the increasing order of ultimate load was found to be tibiocalcaneal ligament, tibionavicular ligament, tibiospring ligament, posterior tibiotalar ligament. The posterior tibiotalar ligament and tibiospring ligament, so frequently neglected in the anatomical and orthopaedic literature, demonstrated the highest yield force and ultimate load of all of the collateral ligaments of the ankle. Additionally, the tibiospring ligament showed high yield and ultimate elongation properties probably related to its distal attachment to the spring ligament. The fibulocalcaneal ligament was found to have high linear elastic modulus suggesting some type of unique material properties or internal fiber organization. Knowledge of the mechanical characteristics of the ligaments of the ankle joint contributes to an understanding of their normal function, pathomechanics of injury, and their optimal surgical reparative procedure and reconstructive material. A knowledge of the normal mechanical properties of the ankle ligaments provides a data base to evaluate which of the multiplicity of present tendon graft materials has mechanical properties similar to those of the ligaments to be replaced. Those tendon grafts will be the most suitable for replacement of specific ligaments. Finally, data on the mechanical properties of these ligaments offer the possibility for evaluating any future biological or prosthetic grafts.

The three-dimensional kinematics and flexibility characteristics of the human ankle and subtalar joints--Part I: Kinematics.

Abstract: The in-vitro, three dimensional kinematic characteristics of the human ankle and subtalar joint were investigated in this study. The main goals of this investigation were: 1) To determine the range of motion of the foot-shank complex and the associated range of motion of the ankle and subtalar joints; 2) To determine the kinematic coupling characteristics of the foot-shank complex, and 3) To identify the relationship between movements at the ankle and subtalar joints and the resulting motion produced between the foot and the shank. The tests were conducted on fifteen fresh amputated lower limbs and consisted of incrementally displacing the foot with respect to the shank while the motion of the articulating bones was measured through a three dimensional position data acquisition system. The kinematic analysis was based on the helical axis parameters describing the incremental displacements between any two of the three articulating bones and on a joint coordinate system used to describe the relative position between the bones. From the results of this investigation it was concluded that: 1) The range of motion of the foot-shank complex in any direction (dorsiflexion/plantarflexion, inversion/eversion and internal rotation/external rotation) is larger than that of either the ankle joint or the subtalar joint.; 2) Large kinematic coupling values are present at the foot-shank complex in inversion/eversion and in internal rotation/external rotation. However, only a slight amount of coupling was observed to occur in dorsiflexion/plantarflexion.; 3) Neither the ankle joint nor the subtalar joint are acting as ideal hinge joints with a fixed axis of rotation.; 4) Motion of the foot-shank complex in any direction is the result of rotations at both the ankle and the subtalar joints. However, the contribution of the ankle joint to dorsiflexion/plantarflexion of the foot-shank complex is larger than that of the subtalar joint and the contribution of the subtalar joint to inversion/eversion is larger than that of the ankle joint.; 5) The ankle and the subtalar joints have an approximately equal contribution to internal rotation/external rotation movements of the foot-shank complex.

The psychiatric symptoms of Alzheimer's disease.

Abstract: The authors used a semistructured interview administered to primary family caregivers to assess the prevalence and nature of psychiatric pathology in 175 well-diagnosed community-residing Alzheimer's disease patients. Symptoms that are indicative of depression in the cognitively intact were virtually ubiquitous in this demented population. A variety of psychotic features were also regularly reported. The implications of these findings for the recognition and treatment of reversible psychiatric impairment are discussed.

Post-Traumatic Stress Disorder in Sexually Abused Children

Abstract: Thirty-one sexually abused children were studied using structured interviews and standardized instruments to determine the frequency of post-traumatic stress disorder (PTSD) and associated symptoms. Of these sexually abused children, 48.4% met DSM-III-R PTSD criteria; 75% of children abused by natural fathers, 67% abused by strangers, and 25% of those abused by trusted adults met criteria as opposed to none of the children abused by an older child. Many children not meeting full DSM-III-R criteria exhibited partial PTSD symptoms. No relationship was observed between the time lapsed since last abusive episode and the development of PTSD. Three standardized instruments (CDI, SEI, and STAIC), although useful in identifying non-PTSD related symptoms, were not useful in differentiating PTSD. The CBCL detected group differences, with PTSD children exhibiting significantly more symptoms of externalizing and internalizing behaviors.

Multifocal acquired demyelinating neuropathy masqurading as motor neuron disease

Abstract: We report five patients with pure motor neuropathy characterized by multifocal weakness, muscle atrophy that was sometimes profound, cramps, and fasciculations with relatively preserved reflexes. The clinical picture led to an initial diagnosis of motor neuron disease in all cases, but nerve conduction studies revealed multifocal conduction block confined to motor axons and predominantly involving proximal nerve segments. Routine sensory nerve conduction studies, ascending compound nerve action potentials, and somatosensory evoked potentials were all normal even through nerve segments in which motor conduction was severely blocked. Onset of symptoms was insidious, and progression was indolent. In two cases, after many years of neuropathy, sensory abnormalities developed but remained clinically trivial. These unusual cases probably have the same pathogenesis as previously described patients with persistent multifocal conduction block. Distinction from motor neuron disease is critical, since chronic demyelinating neuropathy may respond to treatment.

Influence of molecular packing and phospholipid type on rates of cholesterol exchange

Abstract: The rates of (/sup 14/C)cholesterol transfer from small unilamellar vesicles containing cholesterol dissolved in bilayers of different phospholipids have been determined to examine the influence of phospholipid-cholesterol interactions on the rate of cholesterol desorption from the lipid-water interface. At 37/sup 0/C, for vesicles containing 10 mol % cholesterol, the half-times for exchange are about 1, 13, and 80 h, respectively, for unsaturated PC, saturated PC, and SM. In order to probe how differences in molecular packing in the bilayers cause the rate constants for cholesterol desorption to be in the order unsaturated PC > saturated PC > SM, nuclear magnetic resonance (NMR) and monolayer methods were used to evaluate the cholesterol physical state and interactions with phospholipid. The NMR relaxation parameters for (4-/sup 13/C) cholesterol reveal no differences in molecular dynamics in the above bilayers. The greater van der Waals interaction in the SM monolayer (or bilayer) compared to PC gives rise to a larger condensation by cholesterol. This is a direct demonstration of the greater interaction of cholesterol with SM compared to PC. An estimate of the van der Waals interactions between cholesterol and these phospholipids has been used to derive a relationship between the ratio of the ratemore » constants for cholesterol desorption and the relative molecular areas (lateral packing density) in two bilayers. This analysis suggests that differences in cholesterol-phospholipid van der Waals interaction energy are an important cause of varying rates of cholesterol exchange from different host phospholipid bilayers.« less

Deficits in facial-affect recognition and schizophrenia

Abstract: It has been widely demonstrated that schizophrenic patients show a broad range of deficits in interpersonal skills. Recently, considerable attention has been focused on the ability of these patients to decode affective cues. This article reviews findings about facial-affect recognition in schizophrenia. While the literature on this topic is extensive, many investigations have suffered from significant methodological shortcomings. Strategies to resolve these shortcomings are presented. Possible relationships between problems of affect recognition and other symptoms that characterize schizophrenia are discussed. Neurological mechanisms of facial-affect recognition are reviewed and related to data on lateralized neurological impairment in

A monoclonal antibody specific for the cellular receptor for the group B coxsackieviruses.

Abstract: A 50-kilodalton receptor protein (Rp-a) for the group B coxsackieviruses (CB) was isolated in a virus-receptor complex from detergent-solubilized HeLa cells (J. E. Mapoles, D. L. Krah, and R. L. Crowell, J. Virol. 55:560-566, 1985). It was used as an immunogen for preparation of a mouse monoclonal antibody (RmcB) which protected HeLa cells and Buffalo green monkey kidney cells from infection by all six serotypes of CB. RmcB did not protect HeLa cells from infection by poliovirus, echovirus 6, or coxsackievirus A18. This monoclonal antibody differed in receptor epitope specificity from a previously isolated antibody (RmcA) (R. L. Crowell, A. K. Field, W. A. Schleif, W. L. Long, R. J. Colonno, J. E. Mapoles, and E. A. Emini, J. Virol. 57:438-445, 1986) which blocked receptors only for type 1 CB (CB1), CB3, CB5, and echovirus 6. RmcA and RmcB recognized two distinct saturable receptors on HeLa cells, designated HR2 and HR1, respectively. Human rhabdomyosarcoma (RD) cells have the HR2 receptor for CB3-RD (a variant of CB3), but lack the HR1 receptor for CB3. Therefore, RD cells were resistant to infection by CB3. Although binding of CB3-RD to the HR2 receptor on RD cells can lead to infection, binding of CB3-RD to the HR2 receptor on HeLa cells did not lead to infection. Apparently, both CB3 and CB3-RD use only the HR1 receptor for infection of HeLa cells. Thus, a given virus may use two distinct receptors to bind to cells when only one virus-receptor interaction leads to infection.

Biomechanical Evaluation of the Extensor Musculature of the Cervical Spine

Abstract: Dissection of the musculature in the cervical spines of four cadavers indicated that the semispinalis cervicis and capitis muscles appeared to be the muscles primarily responsible for extension of the cervical spine and head. The minimum force needed to balance a biomechanical model of the cervical

The Vertical Stability of the Cervical Spine

Abstract: The concept of the three-column cervical spine and load transmission through each column was experimentally tested. Material consisted of five cervical columns removed from cadavers. The experiment was conducted on an Instron load testing machine. Load was applied on superior articular surfaces of the axis vertebra and was recorded below from each column separately at the level of the sixth cervical vertebra. It was found that 36% of the total load applied on the top of the specimen is transmitted through the anterior column formed by bodies and intervertebral discs and 32% each through the two posterior cervical columns formed by the articular processes. The experiment very strongly supported the role of neural arch in transmission of vertebral compressive forces.

Solution to the inverse kinematics problem in robotics by neural networks

Abstract: The authors use a neural-network model in the solution of the inverse kinematics problem in robotics. It is found that the neural network can be trained to generate a fairly accurate solution which, when augmented with local differential inverse kinematic methods, results in minimal burden on processing load of each control cycle and thus allows real-time robot control. Further benefits are expected from the natural fault tolerance of the neural network and the elimination of the costly derivation and programming of the inverse kinematic algorithm. >

Problem Solving: A Statistician's Guide

Abstract: PART ONE: The general principles involved in tackling real-life statistical problems Introduction The stages of a statistical investigation Formulating the problem Collecting the data Analyzing the data - 1: General strategy Analyzing the data - 2: The initial examination of data Analyzing the data - 3: The 'definitive' analysis Using resources - 1: The computer Using resources - 2: The library Communication - 1: Effective statistical consulting Communication - 2: Effective report writing Numeracy Summary: How to be an effective statistician PART TWO: Exercises Descriptive statistics Exploring data Correlation and regression Analyzing complex large-scale data sets Analyzing more structured data Time-series analysis Miscellaneous Collecting data PART THREE: Appendices Appendix A: A digest of statistical techniques Appendix B: MINITAB and GLIM Appendix C: Some useful addresses Appendix D: Statistical tables References Author Index Subject Index

A transverse‐wave ultrasonic oblique‐incidence technique for interfacial weakness detection in adhesive bonds

Abstract: The possibility of using an ultrasonic oblique‐incidence technique for improved sensitivity in interfacial weakness detection in adhesive bonds was considered. The analysis of the sensitivity of transverse waves to interface imperfections on an interface between two semi‐infinite half‐spaces with bond rigidities of various finite values was carried out. Excellent sensitivity is obtained for discriminating bond weaknesses from a perfect or welded situation to a poor or smooth situation compared to longitudinal wave impingement and reflection. The optimal angle of incidence for the inspection of an aluminum‐to‐aluminum adhesively bonded structure in an immersion technique is presented. Additionally, a signal feature in frequency domain for adhesive and cohesive weakness distinction is proposed.

Trauma Systems: Current Status—Future Challenges

Abstract: The national status of regional trauma system development was evaluated by a survey sent to all state emergency medical services directors and state chairpersons of the American College of Surgeons Committee on Trauma. Eight essential components of a regional trauma system based on criteria set forth by the American College of Surgeons were listed. Only two states were found to have all components and statewide coverage. Nineteen states and the District of Columbia lacked one or more components of a regional trauma system. The remaining 29 states had yet to initiate the process of trauma center designation. In response to these shortcomings, an attempt was made to define the barriers to trauma system implementation and a step-by-step process was outlined for the development, management, and analysis of a comprehensive system of trauma care. ( JAMA 1988;259:3597-3600)

On the stability, storage capacity, and design of nonlinear continuous neural networks

Abstract: The stability, capacity, and design of a nonlinear continuous neural network are analyzed. Sufficient conditions for existence and asymptotic stability of the network's equilibria are reduced to a set of piecewise-linear inequality relations that can be solved by a feedforward binary network, or by methods such as Fourier elimination. The stability and capacity of the network is characterized by the postsynaptic firing rate function. An N-neuron network with sigmoidal firing function is shown to have up to 3/sup N/ equilibrium points. This offers a higher capacity than the (0.1-0.2)N obtained in the binary Hopfield network. It is shown that by a proper selection of the postsynaptic firing rate function, one can significantly extend the capacity storage of the network. >

Cooperative frequency locking and stationary spatial structures in lasers

Abstract: We investigate the spontaneous emergence of transverse patterns in lasers by using both the standard two-level model and the so-called cubic approximation, which is generally valid in the threshold regions. The stationary intensity configurations fall into two distinct classes. The first includes solutions of the single-mode type with the frequency and spatial structure of one of the transverse resonances. The solutions of the second group involve the simultaneous oscillation of several cavity modes, operating in such a way as to produce a stationary intensity profile. The stationary character of these multimode configurations emerges from the fact that the transverse modes of the resonator lock onto a common frequency during the nonlinear transient. We call this phenomenon cooperative frequency locking.

Neural network architecture for control

Abstract: Two important computational features of neural networks are associative storage and retrieval of knowledge, and uniform rate of convergence of network dynamics independent of network dimension. It is indicated how these properties can be used for adaptive control through the use of neural network computation algorithms, and resulting computational advantages are outlined. The neuromorphic control approach is compared to model reference adaptive control on a specific example. It is shown that the utilization of neural networks for adaptive control offers definite speed advantages over traditional approaches for very-large-scale systems. >

Velocity measurements in a plane turbulent air jet at moderate Reynolds numbers

Abstract: An experimental investigation of the moderate Reynolds number plane air jets was undertaken and the effect of the jet Reynolds number on the turbulent flow structure was determined. The Reynolds number, which was defined by the jet exit conditions, was varied between 1000 and 7000. Other initial conditions, such as the initial turbulence intensity, were kept constant throughout the experiments. Both hot-wire and laser Doppler anemometry were used for the velocity measurements. In the moderate Reynolds number regime, the turbulent flow structure is in transition. The average size and the number of the large scale of turbulence (per unit length of jet) was unaffected by the Reynolds number. A broadening of the turbulent spectra with increasing Reynolds number was observed. This indicated that there is a decrease in the strength of the large eddies resulting from a reduction of the relative energy available to them. This diminished the jet mixing with the ambient as the Reynolds number increased. Higher Reynolds numbers led to lower jet dilution and spread rates. On the other hand, at higher Reynolds numbers the dependence of jet mixing on Reynolds number became less significant as the turbulent flow structure developed into a self-preserving state.

Paramyosin and actin in schistosomal teguments

Abstract: Schistosomes are blood-dwelling trematode parasites that infect 200 million people in developing countries. The critical role served by the tegument in immune evasion and parasite homeostasis suggests that a detailed knowledge of tegumental components would be helpful in the design of new drugs and the production of vaccines. We demonstrate here, by immunoelectron microscopy, that the cytoskeletal proteins actin and paramyosin are organized into major tegumental structures of Schistosoma mansoni. The surface spines are composed of paracrystalline arrays of actin filaments. Actin is also present in areas recovering from damage, implying an important role for this structural protein in tegumental repair. Paramyosin exists predominantly in the tegument in a non-filamentous form, the membrane-bounded elongate bodies. The localization of this protein to the tegument of the parasite is the likely basis for resistance to S. mansoni observed in mice immunized with paramyosin (refs 1, 2 and T. P. Flanigen et al., in preparation).