Showing papers by "Duquesne University published in 2001"

Optimizing femoral component rotation in total knee arthroplasty.

Abstract: Femoral component rotation is important in total knee arthroplasty to optimize patellofemoral and tibiofemoral kinematics. More recently, the epicondylar axis has been cited as the definitive landmark for femoral component rotation. However, there are few studies to support the validity of this rotational landmark and its effect on the patellofemoral and tibiofemoral articulations. In the current study, a total knee arthroplasty was done in 11 knees from cadavers. The knees were tested with various femoral component rotations from 5 degrees internal rotation to 5 degrees external rotation referenced to the epicondylar axis and to the posterior femoral condyles. Each knee acted as its own internal control. The knees were actively ranged from 0 degrees to 100 degrees by a force on the quadriceps tendon in an Oxford knee simulator. Three-dimensional kinematics of all three components were measured whereas a multiaxial transducer imbedded in the patella measured patellofemoral forces. Femoral component rotation parallel to the epicondylar axis resulted in the most normal patellar tracking and minimized patellofemoral shear forces early in flexion. This optimal rotation also minimized tibiofemoral wear motions. These beneficial effects of femoral rotation were less reproducibly related to the posterior condyles. Rotating the femoral component either internal or external to the epicondylar axis worsened knee function by increasing tibiofemoral wear motion and significantly worsening patellar tracking with increased shear forces early in flexion. Based on the current study, the femoral component should be rotationally aligned parallel to the epicondylar axis to avoid patellofemoral and tibiofemoral complications.

Microwave-enhanced chemistry

Abstract: Analytical chemists no longer have to accept the technological mismatch between sample preparation and instrumentation.

A randomized trial of exercise programs among older individuals living in two long-term care facilities: the FallsFREE program.

Abstract: OBJECTIVE: To use two different exercise programs over a 2-year period to reduce falls and their sequelae among residents of two long-term care facilities. DESIGN: Randomized, controlled trial. SETTING: The study took place at two long-term care facilities with services ranging from independent living to skilled nursing. PARTICIPANTS: One hundred and ten participants whose average age was 84 and who were capable of ambulating with or without assistive devices and could follow simple directions. INTERVENTION: Participants were randomized to one of two exercise groups (resistance/endurance plus basic enhanced programming or tai chi plus basic enhanced programming) or to a control group (basic enhanced programming only). Exercise classes were held three times per week throughout the study. MEASUREMENTS: Participants were evaluated for cognitive and physical functioning at baseline and 6, 12, and 24 months. Falls were determined from incident reports filed by the nursing staffs at the facilities. RESULTS: Time to first fall, time to death, number of days hospitalized, and incidence of falls did not differ among the treatment and control groups (P> .05). Among all participants, those who fell had significantly lower baseline Folstein Mini-Mental State Examination and instrumental activities of daily living scores and experienced significantly greater declines in these measures over the 2-year program. CONCLUSION: There were no significant differences in falls among the two exercise groups and the control group. Lack of treatment differences and low adherence rates suggest that residents of long-term care facilities may require individualized exercise interventions that can be adapted to their changing needs.

Gender and computers: similarities and differences in Iranian college students' attitudes toward computers

Abstract: This study surveys attitudes about computers among 375 Iranian undergraduate students (155 males and 220 females). We found significant gender differences with respect to confidence about computers and stereotypic views of computer users. Women showed stronger beliefs in equal gender ability and competence in use of computers, but expressed low confidence in their own ability to work with computers. There were no significant gender differences in respondents' liking for computers or their perceptions of the usefulness of computers. Male and female students believed equally in the positive effects of computers on individuals and society. Results also are discussed in terms of parents' perceived beliefs and behaviors, as well as their socioeconomic status (SES.)

Investigating Influences on Managers' Moral Reasoning The Impact of Context and Personal and Organizational Factors

Abstract: Managers often face situations that challenge their ability to reason morally. Avariety of factors, including the issue itself and personal and organizational influences, may affect their responses...

Frogs without polliwogs: evolution of anuran direct development.

Abstract: Direct development is the assumption of the adult morphology without progression through an intervening, morphologically distinct, free-living larval phase. We discuss the ecological factors contributing to the evolution of this derived life-history strategy in frogs, and the developmental modifications that facilitate such an unusual mode of embryogenesis. Studies on the Puerto Rican tree frog, Eleutherodactylus coqui, have identified several such modifications, including developmental adaptations for dealing with increased egg size, and loss of tadpole structures. Surprisingly, this direct developer still undergoes a thyroid hormone-dependent metamorphosis, which occurs before hatching. We suggest how the ancestral biphasic developmental pattern may have been rearranged during the evolution of direct development.

A Brownian Dynamics Study of the Initial Stages of Hen Egg-White Lysozyme Adsorption at a Solid Interface

Abstract: We investigate the initial stages of hen egg-white lysozyme (HEWL) adsorption at a charged solid interface using Brownian Dynamics simulation. The protein is modeled at the atomistic level and the adsorption surface is represented by a planar array of positively charged sites. Adsorption reactions are simulated at neutral pH and at low and high salt concentrations. We find that the HEWL, which has a net positive charge, can adsorb onto the positively charged surface. The results are consistent with an electrostatically driven adsorption process. While the orientational distribution of the adsorbed protein is nonuniform, there is no dominant patch composed of two or more oppositely charged residues. The electric field distribution around the protein is the best predictor of the adsorption behavior.

Heme Aggregation inhibitors: antimalarial drugs targeting an essential biomineralization process.

Abstract: Malaria, resulting from the parasites of the genus Plasmodium, places an untold burden on the global population. As recently as 40 years ago, only 10% of the worlds population was at risk from malaria. Today, over 40% of the worlds population is at risk. Due to increased parasite resistance to traditional drugs and vector resistance to insecticides, malaria is once again resurgent. An emergent theme from current strategies for the development of new antimalarials is that metal homeostasis within the parasite represents an important drug target. During the intra-erythrocytic phase of its life cycle, the malaria parasite can degrade up to 75% of an infected cells hemoglobin. While hemoglobin proteolysis yields requisite amino acids, it also releases toxic free heme (Fe(III)PPIX). To balance the metabolic requirements for amino acids against the toxic effects of heme, malaria parasites have evolved a detoxification mechanism which involves the formation of a crystalline heme aggregate known as hemozoin. An overview of the biochemistry of the critical detoxification process will place it in the appropriate context with regards to drug targeting and design. Quinoline-ring antimalarial drugs are effective against the intraerythrocytic stages of pigment-producing parasites. Recent work on the mechanism of these compounds suggests that they prevent the formation of hemozoin. Evidence for such a mechanism is reviewed, especially in the context of the newly reported crystal structure of hemozoin. Additionally, novel drugs, such as the hydroxyxanthones, which have many of the characteristics of the quinolines are currently being investigated. Recent work has also highlighted two classes of inorganic complexes that have interesting antimalarial activity: (1) metal-N4O2 Schiff base complexes and (2) porphyrins. The mechanism of action for these complexes is discussed. The use of these complexes as probes for the elucidation of structure-activity relationships in heme polymerization inhibitor design and the loci of drug resistance is also detailed. As the biochemistry of the complicated interactions between host, parasite, and vector become better understood, the rationale for new antimalarial drug treatments will continue to improve. Clearly, the homeostasis of metal ions is a complicated biochemical process and is not completely understood. For the immediate future, it does, however, provide a clear target for the development of new and improved treatments for malaria.

Selenihalanaerobacter shriftii gen. nov., sp. nov., a halophilic anaerobe from Dead Sea sediments that respires selenate

Abstract: We isolated an obligately anaerobic halophilic bacterium from the Dead Sea that grew by respiration of selenate. The isolate, designated strain DSSe-1, was a gram-negative, non-motile rod. It oxidized glycerol or glucose to acetate+CO2 with concomitant reduction of selenate to selenite plus elemental selenium. Other electron acceptors that supported anaerobic growth on glycerol were nitrate and trimethylamine-N-oxide; nitrite, arsenate, fumarate, dimethylsulfoxide, thiosulfate, elemental sulfur, sulfite or sulfate could not serve as electron acceptors. Growth on glycerol in the presence of nitrate occurred over a salinity range from 100 to 240 g/l, with an optimum at 210 g/l. Analysis of the 16S rRNA gene sequence suggests that strain DSSe-1 belongs to the order Halanaerobiales, an order of halophilic anaerobes with a fermentative or homoacetogenic metabolism, in which anaerobic respiratory metabolism has never been documented. The highest 16S rRNA sequence similarity (90%) was found with Acetohalobium arabaticum (X89077). On the basis of physiological properties as well as the relatively low homology of 16S rRNA from strain DSSe-1 with known genera, classification in a new genus within the order Halanaerobiales, family Halobacteroidaceae is warranted. We propose the name Selenihalanaerobacter shriftii. Type strain is strain DSSe-1 (ATCC accession number BAA-73).

Marketing Rebellion: Insurgent Groups, International Media, and Ngo Support

Abstract: Many scholars view an emergent “global civil society” as an accessible, democratic alternative to the state system–a new political space where social movements frustrated at home can gain support from “principled” transnational advocacy networks. But, only a few movements from the developing world attract transnational backing. This article first proposes a framework clarifying the process, and then identifies structural and strategic factors explaining the variation. The article compares two movements that secured significant international support, Nigeria's Movement for the Survival of the Ogoni People (MOSOP) and Mexico's Zapatista Army of National Liberation (Ejercito Zapatista de Liberacion Nacional, EZLN), against similar groups from the same countries that failed to do so. On this basis, the article argues that “global civil society” requires reconceptualization–as a competitive arena where weak domestic challengers vie for scarce transnational resources, where those groups that gain support have structural or strategic advantages over others, and where transnational supporters act on interest as well as principle.

The Problem of Transfer, and the Sociocultural Critique of Schooling

Abstract: It is often suggested that transfer is central to our system of education. Yet transfer has proven hard to define, difficult to investigate, and perplexingly controversial. This article compares 1 of the earliest critiques of transfer- Dewey's (1916)-with 1 of the most recent-Lave's (1988)-to explore how the debate over transfer is linked to competing views of the goals and aims of schooling. It is proposed that if sociocultural theory is to make good on its critique of schooling, it must be extended in 2 respects: in its ontology of the person, and its conception of the society in which we live. A preliminary sketch is provided of each of these extensions, to develop the sociocultural suggestion that learning and schooling both involve transformation of the person. The debate over transfer rests on but obscures divergent views of the goals and aims of schooling. Both critique of schooling and calls for school reform presuppose conceptions of the kind of person we want children to be, and the kind of soci...

Creating transnational solidarity: the use of narrative in the u.s.-central america peace movement *

Abstract: As social problems become increasingly global, activists are working across state boundaries and forming transnational social movements. However, there is little information that illuminates how groups are able to overcome ethnic, class, ideological and cultural differences that could be obstacles to collaboration. Through an analysis of the story of Salvadoran martyr Archbishop Romero, I demonstrate how this narrative fostered solidarity between the progressive Central American church and U.S. Christians. By symbolically mirroring the social ontology of Christianity and melodramatically presenting the Salvadoran conflict with moral clarity, Romero's life story facilitated the construction of a transnational collective identity and provided a model of action. The moral credibility of the narrators, and the context in which Romero's story was told, influenced many Christians' decision to prioritize this religious identity over their national allegiance.

Loss of Transposase-DNA Interaction May Underlie the Divergence of mariner Family Transposable Elements and the Ability of More than One mariner to Occupy the Same Genome

Abstract: Mariners are a large family of eukaryotic DNA-mediated transposable elements that move via a cut-and-paste mechanism. Several features of the evolutionary history of mariners are unusual. First, they appear to undergo horizontal transfer commonly between species on an evolutionary timescale. They can do this because they are able to transpose using only their own self-encoded transposase and not host-specific factors. One consequence of this phenomenon is that more than one kind of mariner can be present in the same genome. We hypothesized that two mariners occupying the same genome would not interact. We tested the limits of mariner interactions using an in vitro transposition system, purified mariner transposases, and DNAse I footprinting. Only mariner elements that were very closely related to each other (ca. 84% identity) cross-mobilized, and then inefficiently. Because of the dramatic suppression of transposition between closely related elements, we propose that to isolate elements functionally, only minor changes might be necessary between elements, in both inverted terminal repeat and amino acid sequence. We further propose a mechanism to explain mariner diversification based on this phenomenon.

Synthesis, antifolate, and antitumor activities of classical and nonclassical 2-amino-4-oxo-5-substituted-pyrrolo[2,3-d]pyrimidines.

Abstract: Classical and nonclassical isosteric C8−N9 bridged analogues of the multitargeted antifolate LY231514 were synthesized as inhibitors of thymidylate synthase (TS), dihydrofolate reductase (DHFR), and as antitumor and antiopportunistic infection agents. The syntheses of the analogues were accomplished by reductive amination of the appropriate anilines with 2-amino-4-oxo-5-cyanopyrrolo[2,3-d]pyrimidine (28) followed by saponification of the ethyl esters, for the classical analogue 6. The N9-methyl analogues were obtained from the N9−H precursors by reductive methylation. In general, the nonclassical compounds 7−17 were similar in potency to TMP against Toxoplasma gondii DHFR, with selectivity ratios greater than 38 and 21 for 11 and 16, respectively. These compounds were poor inhibitors of Pneumocystis carinii DHFR and rat liver DHFR. The nonclassical analogues were also inactive against TS. The classical analogue 6 was a marginal inhibitor of isolated human TS (IC50 = 46 μM) and of human DHFR (IC50 = 10 μM)...

Enhancement of Ibuprofen Dissolution via Wet Granulation with β-Cyclodextrin

Abstract: The purpose was to investigate the effect of wet granulation with beta-cyclodextrin (betaCD) on the enhancement of ibuprofen (IBU) dissolution. The effect of the granulation variables on the physical properties as well as the dissolution of tablets prepared from these granules was also examined. Granulation was performed using three granulating solvents: water, ethanol (95 vol%), and isopropanol. Granules were either oven-dried for 2 h or air-dried for 3 days. The granules or respective physical mixtures were compressed into tablets. Powder X-ray diffraction showed that oven-dried granulation resulted in less amorphous entities thatfacilitated IBU-betaCD complexation in solution and enhanced the dissolution of the corresponding tablets compared to the physical mixture with or without oven drying. In contrast, air-dried granulation did not cause any differences in the X-ray diffraction pattern (crystallinity) or the dissolution compared to the physical mixture without drying. Isopropanol and water, as granulating solvents, enhanced the dissolution of the oven-dried batches more than ethanol. The Differential scanning calorimetry (DSC) and Thermogravimetric analysis (TGA) data showed that tablets prepared from oven-dried granules, but not air-dried granules, had lower AH values and percent loss in weight, respectively, than those prepared from the physical mixture as a result of the expulsion of the water molecules from the betaCD cavity and enhancement of the complexation in solution. These results showed that oven-dried granulation of IBU and betaCD provided faster IBU dissolution than the physical mixture; air-dried granulation did not substantially affect the dissolution of IBU.

Dialogic civility as pragmatic ethical praxis: an interpersonal metaphor for the public domain

Abstract: This essay offers dialogic civility as a guiding interpersonal metaphor in a time of narrative disagreement, an era in which ethical standpoints that traditionally have undergirded discourse are in contrast, dispute, and disruption. Dialogic civility is an interpersonal metaphor grounded in the public domain and in a pragmatic commitment to keeping the conversation going in a time of narrative confusion and virtue fragmentation. This essay frames a pragmatic case for dialogic civility as a key interpersonal metaphor for negotiating difference in the public domain of postmodern communicative interaction.

Construct Validity of the WISC-III for White and Black Students from the WISC-III Standardization Sample and for Black Students Referred for Psychological Evaluation.

Abstract: This study used both exploratory (EFA) and confiiatory factor analy- ses (CFA) to examine the factor structure of the WISC-III among White and Black students from the WISC-III standardization sample and a sample of 348 Black students referred for psychological evaluation. Results of the EFA provided evi- dence of a large first principal factor as well as the expected Verbal and Perfor- mance components across all three groups. Empirical support for the Freedom from Distractibility dimension was provided only from the confirmatory factor analyses. Although the four factor confirmatory model exhibited the best overall statistical fit, inspection of specific factor loadings revealed anomalies with the third and fourth factors, especially for the Referred Black sample. Implications for school psychologists are presented and recommendations for future research are provided.

Differential Geometry from Differential Equations

Abstract: We first show how, from the general 3rd order ODE of the form , one can construct a natural Lorentzian conformal metric on the four-dimensional space . When the function satisfies a special differential condition the conformal metric possesses a conformal Killing field, , which in turn, allows the conformal metric to be mapped into a three dimensional Lorentzian metric on the space ) or equivalently, on the space of solutions of the original differential equation. This construction is then generalized to the pair of differential equations, z ss =S(z,z s ,z t ,z st ,s,t) and z tt =T(z,z s ,z t ,z st ,s,t), with z s and z t the derivatives of z with respect to s and t. In this case, from S and T, one can again, in a natural manner, construct a Lorentzian conformal metric on the six dimensional space (z,z s ,z t ,z st ,s,t). When the S and T satisfy differential conditions analogous to those of the 3rd order ode, the 6-space then possesses a pair of conformal Killing fields, and which allows, via the mapping to the four-space of (z,z s ,z t ,z st ) and a choice of conformal factor, the construction of a four-dimensional Lorentzian metric. In fact all four-dimensional Lorentzian metrics can be constructed in this manner. This construction, with further conditions on S and T, thus includes all (local) solutions of the Einstein equations.

Interobserver variability associated with the MIB-1 labeling index: high levels suggest limited prognostic usefulness for patients with primary brain tumors.

Abstract: BACKGROUND The use of the MIB-1 labeling index (LI) as a potential prognostic marker for patients with primary brain tumors is controversial. Many studies advocating its prognostic usefulness have suggested discrete MIB-1 LI cut-off values, above which patients have significantly worse outcomes. However, interobserver variability associated previously with MIB-1 LI calculation has not been reported despite the fact that the degree of interobserver variability impacts the clinical usefulness of such cut-off values. METHODS MIB-1 LIs were calculated independently using a standardized protocol by six pathologist observers for 50 astrocytic gliomas of varying grades. The level of interobserver agreement was determined by calculating kappa statistics for pairwise pathologist comparisons using MIB-1 LI cut-off values of 2.5%, 5.0%, 8.0%, 11.0%, and 15.0%. Spearman rank correlation coefficients were used to assess the pairwise associations between observer MIB-1 LIs. RESULTS Although there was general agreement among pathologists regarding whether an MIB-1 LI for a given astroglial tumor was low, moderate, or high based on the analysis of correlation, a high level of interobserver variability was associated with the determination of specific MIB-1 LIs. The highest level of agreement occurred using a cut-off value of 5.0%, with pairwise kappa statistics for this value ranging from 0.52 to 0.80. CONCLUSIONS The high level of interobserver variability suggests that proposed discrete MIB-1 LI prognostic cut-off values most likely are not useful clinically for predicting outcome for individual patients with primary brain tumors. Further prospective studies are needed investigating the prognostic usefulness of MIB-1 LI ranges that optimize interobserver agreement. Cancer 2001;92:2720–6. © 2001 American Cancer Society.