bluuebunny/crossref_metadata_2025 huggingface dataset:
Baculovirus‐resistant Anticarsia gemmatalis responds differently to dietary rutin
Authors: Piubelli G.C. , Hoffmann‐Campo C.B. , Moscardi F. , Miyakubo S.H. , De Oliveira M.C.N.
Published: March 2006

The velvetbean caterpillar, Anticarsia gemmatalis (Hübner) (Lepidoptera: Noctuidae), the major soybean [Glycine max (L.) Merrill (Fabaceae)] defoliator pest in Brazil can be controlled by a specific and virulent nuclear polyhedrosis virus (AgMNPV). Flavonoids such as rutin (quercetin 3‐O‐rhamnosylglucoside) were identified in soybean; it is known that this compound plays an important role in plant defense against lepidopteran pests. Studies were carried out to evaluate the biological and physiological activity of rutin (0.65 and 1.30%) on populations of A. gemmatalis resistant and susceptible to AgMNPV. Larvae from the resistant population were more negatively influenced by rutin, in comparison to larvae of the susceptible population, even with the addition of the lowest level of the flavonoid (0.65%) to the insect diet. The highest mortality (98%) was observed in the resistant population, when larvae fed on the diet containing 1.30% of rutin. Elongation of the feeding time, smaller initial larval weight, and pupal weight was observed on the virus‐resistant and ‐susceptible populations after adding 0.65 and 1.30% rutin to the diet. Larvae of the resistant population to AgMNPV fed on diet plus rutin 0.65% were also less efficient in the conversion of ingested and digested food into biomass.
Characteristics of 5‐aminolaevulinic acid‐induced protoporphyrin IX fluorescence in human skin in vivo
Authors: Ibbotson S. H. , Jong C. , Lesar A. , Ferguson J. S. , Padgett M. , O'Dwyer M. , Barnetson R. , Ferguson J.
Published: March 2006

Background/Purpose: Topical photodynamic therapy (PDT) is increasingly being used to treat skin cancers. Knowledge of the detailed characteristics of 5‐aminolaevulinic acid (ALA)‐induced protoporphyrin IX (PpIX) fluorescence in diseased and normal skin is incomplete. Understanding the characteristics of PpIX fluorescence in normal skin may facilitate optimization of PDT regimes while minimizing side effects in the surrounding normal skin. We investigated the characteristics of ALA‐induced PpIX fluorescence in normal skin.

Methods: ALA was applied to the arm, back and leg skin of 21 healthy volunteers for 1–6 h, and PpIX fluorescence was measured for up to 24 h after ALA application using a fluorescent spectrometer. The effect of tape stripping on fluorescence was also examined.

Results: Considerable inter‐subject variation was observed in the time to reach peak PpIX fluorescence. Intra‐subject variation in the time to peak fluorescence was dependent on ALA application time. Six hours after ALA application, no significant difference was observed in the degree of fluorescence achieved irrespective of ALA application times ranging between 1 and 6 h. PpIX fluorescence was reduced on the leg and increased by tape stripping.

Conclusions: Marked inter‐ and intra‐subject variation in ALA‐induced PpIX fluorescence occurs in normal human skin. ALA application time, body site and the state of the stratum corneum are all determinants of PpIX fluorescence within subjects and these factors need to be taken into account in optimization of PDT regimes.
Association of HLA subtype DRB1*0407 in Colombian patients with actinic prurigo
Authors: Suárez Alfonso , Valbuena Martha Cecilia , Rey Maritza , de Porras Quintana Luisa
Published: March 2006

Background: Human leukocyte antigen (HLA) DRB1*0407 had been associated with actinic prurigo in different populations. This class II HLA‐DR subtype had not been studied in Colombia.

Objective: The objective of this study was to establish whether there was an association of actinic prurigo with HLA DR in a Colombian population.

Materials and methods: Forty patients with a clinical diagnosis of actinic prurigo and 40 healthy subjects, paired by age, sex and birthplace, were studied. HLA typing for HLA DRB1 and DRB1*04, if necessary, was performed by the PCR‐SSP method using blood samples.

Results: A high frequency of HLA DRB1*0407 was found in the patients (97.5% vs. 30%; P< 0.00001). The allelic frequency of HLA DRB1*0407 was 63.8% in the case group, and 14.5% in the controls (P<0.00001). In the control group, there was a higher frequency of the alleles DRB1*01 (14.5% vs. 1.25%; P=0.0027) and DRB1*13 (23.7% vs. 2.5%; P=0.00013).

Limitations: The small number of controls does not allow us to drive conclusions about other HLA alleles.

Conclusions: HLA subtype DRB1*0407, found in actinic prurigo patients in studies conducted in England, Scotland, Ireland and Mexico, was also associated in Colombian patients. This finding, concordant in patients from different ethnic groups, could be helpful in the diagnosis of this disease and probably important in its pathogenesis. DRB1*01 and DRB1*13 alleles were more frequent in controls than in patients; we do not know whether they play any role in the resistance to the disease.
Compliance and data reliability in sun exposure studies with diaries and personal, electronic UV dosimeters
Authors: Thieden Elisabeth , Philipsen Peter A. , Wulf Hans Christian
Published: March 2006

Background/purpose: Skin cancer risk estimations are based on sun exposure data. However, the reliability of collected data in personal ultraviolet (UV) dosimeters studies has not previously been validated. We aimed at investigating the data reliability and subject compliance in a study of sun exposure behaviour among 407 subjects (age range, 4–68 years) during 54 943 days based on time‐stamped personal UV dosimeter readings and diary records.

Methods: By comparing diary records and UV dosimeter readings on a daily basis, we investigated subject compliance, total sun exposure record, reasons for non‐responding along with rates of diary completing errors. Efforts to improve compliance were described.

Results: The subject compliance rate was median 93.5% (percent days where the diary was completed and the UV dosimeter was worn). The total sun exposure record rate was median 84.1% (percent of participation days with both UV dosimeter and diary records and where the UV dosimeter was worn). Children, adolescents and golfers had lower sun exposure record rates than the rest of the groups (P<0.05). No significant difference was found between males and females (P=0.15). The 17 non‐responders were 10 children, three adolescents, one sun worshipper, two golfers and one gardener. Correctable diary completing mistakes were found in 3.1% of the days. Children made more completing mistakes than adults (P=0.001). The average estimated error rate was 3.3% and was higher for children (6.3%) and adolescents (3.6%) than the adult groups (2.4%).

Conclusion: High subject compliance rate and data reliability were obtained because the investigators were service minded but persistent, offering dosimeter maintenance service within 24 h and scrutinized data for errors and mistakes.
Extracellular ATP Stimulates Exocytosis via Localized Ca2+ Release from Acidic Stores in Rat Pancreatic β Cells
Authors: Xie Li , Zhang Ming , Zhou Wei , Wu Zhengxing , Ding Jiuping , Chen Liangyi , Xu Tao
Published: March 2006

Three different methods, membrane capacitance (Cm) measurement, amperometry and FM dye labeling were used to investigate the role of extracellular ATP in insulin secretion from rat pancreatic β cells. We found that extracellular application of ATP mobilized intracellular Ca2+ stores and synchronously triggered vigorous exocytosis. No influence of ATP on the readily releasable pool of vesicles was observed, which argues against a direct modulation of the secretory machinery at a level downstream of Ca2+ elevation. The stimulatory effects of ATP were greatly reduced by intracellular perfusion of BAPTA but not EGTA, suggesting a close spatial association of fusion sites with intracellular Ca2+ releasing sites. ATP‐induced Ca2+ transients and exocytosis were not blocked by thapsigargin (TG), by a ryanodine receptor antagonist or by dissipation of pH in acidic stores by monensin alone, but they were greatly attenuated by IP3 receptor inhibition as well as ionomycin plus monensin, suggesting involvement of IP3‐sensitive acidic Ca2+ stores. Taken together, our data suggest that extracellular ATP triggers exocytosis by mobilizing spatially limited acidic Ca2+ stores through IP3 receptors. This mechanism may explain how insulin secretion from the pancreas is coordinated through diffusible ATP that is co‐released with insulin.
The development and delivery of a practice‐based breastfeeding education package for general practitioners in the UK
Authors: Burt Sue , Whitmore Mary , Vearncombe Deana , Dykes Fiona
Published: March 2006

Growing acceptance that measurable improvements in public health, particularly in lower‐income groups, could be achieved by increasing the incidence of breastfeeding has focused attention on the current lack of educational provision in breastfeeding issues for many health professionals. An audit of general practitioners in one area of northern England revealed an interest in receiving breastfeeding training. Department of Health funding was obtained by the breastfeeding subgroup of the local Maternity Services Liaison Committee to develop, deliver and evaluate a practice‐based educational session supplemented by a resource pack. Over a 12‐month period, 22 practices received the session and the project was evaluated using an illuminative evaluation model. Response rates to two evaluation questionnaires of 81% (133/164) and 62.5% (65/104) were achieved and findings indicated high levels of satisfaction with the session and its accompanying resource pack. Qualitative data related to perceived influence on future practice were subjected to thematic network analysis and revealed four main (organizing) themes: the acquisition of greater knowledge, improved access to resources, a proactive approach to breastfeeding support and the creation of a breastfeeding‐friendly environment. The illuminative evaluation also identified recurring issues that could impact on any attempt to replicate or adapt this project; these were the influence of personal breastfeeding experiences, the desire for greater interaction during the training session and the wider implications for practice education of multidisciplinary attendance.
The quality of the diet in Malawian children with kwashiorkor and marasmus
Authors: Sullivan Jesse , Ndekha MacDonald , Maker Dawn , Hotz Christine , Manary Mark J.
Published: March 2006

Nutritionists have suggested that kwashiorkor is related to low dietary protein and/or antioxidant intake. This study explored the hypothesis that among Malawian children with severe malnutrition, those with kwashiorkor consume a diet with less micronutrient‐ and antioxidant‐rich foods, such as fish, eggs, tomatoes and orange fruits (mango, pumpkin and papaya), than those with marasmus. A case–control method with a food frequency questionnaire was used to assess the habitual diet. Children with severe childhood malnutrition presenting to the central hospital in Blantyre, Malawi during a 3‐month period in 2001 were eligible to participate. The food frequency questionnaire collected data about foods consumed by siblings <60 months of age in the home. It was assumed that the habitual diet of all siblings 1–5 years old in the same home was similar. Dietary diversity was assessed using a validated method, with scores that ranged from 0 to 7. Regression modelling was used to control for demographic and disease covariates. A total of 145 children with kwashiorkor and 46 with marasmus were enrolled. Children with kwashiorkor consumed less egg and tomato than those with marasmus: 17 (15) vs. 24 (31) servings per month for egg, mean (SD), P < 0.01 and 27 (17) vs. 32 (19) servings per month for tomato, P < 0.05. Children with kwashiorkor had a similar dietary diversity score as those with marasmus, 5.06 (0.99) vs. 5.02 (1.10), mean (SD). Further research is needed to determine what role consumption of egg and tomato may play in the development of kwashiorkor.
Science Studies and English Renaissance Literature
Authors: Marchitello Howard
Published: March 2006

The study of early modern science has been a topic of serious interest to literary scholars since at least the 1920s. This essay examines the history of this interest and the critical work it has engendered. In its first wave, this criticism was especially devoted to the study of the ways in which early modern science influenced – and was thereby reflected in – imaginative writing of the period. This understanding was itself underwritten by prevailing notions of science as both an autonomous and a privileged discourse governed by an irresistible and ever‐evolving rationalism that staked exclusive claims to truth. Recent work in the expanding fields of science studies over the past twenty years, however, has served to dislodge this scientific exceptionalism and radically to recast both the history of science and our understanding of the nature of science. As a result, in second wave criticism of early modern science and literature, literary culture is no longer believed to exist in a merely reflective relation to the disciplines of science; instead, science and literature are set in a creative dialectic with each other that denies priority and scientism and helps to offer a more powerful understanding of the dynamic between these two complexly related cultural practices.
A metal‐binding site is present in the amino terminal region of the bioactive iron regulator hepcidin‐25
Authors: Melino S. , Garlando L. , Patamia M. , Paci M. , Petruzzelli R.
Published: March 2006

Abstract:  Hepcidin is a new peptide hormone secreted by the liver and widely distributed among animals, from fish to human. It acts as a signal molecule in iron metabolism and plays an important role in iron overload diseases. Recently, it has been reported that hepcidin is able to regulate the iron efflux by binding to the ferroportin protein and inducing its internalization. This activity is specific only for bioactive hepcidin‐25 and not for the truncated hepcidin‐20, lacking the five amino terminal residues. We have characterized the N‐terminal region of the hepcidin‐25 as a metal‐binding site by several spectroscopic techniques and chemical studies. This region, specific for the coordination of Cu(II) and Ni(II), is known as ‘ATCUN motif’. Moreover, we have demonstrated that the metal binding inhibits the aggregation propensity of both whole hepcidin‐25 and its N‐terminal fragments, probably inducing a conformational change leading to the stabilization of the N‐terminal region. The identification of a metal‐binding site at the N‐terminus of hepcidin‐25, which is necessary for its biological activity as iron‐regulatory hormone, will help us to cast light both on the role of the divalent metals and of the hepcidin‐25 in the iron homeostatis, and to better understand structure–function relationships of this hormone‐peptide.
Interactions of an acidic cyclooctapeptide with metal ions: microcalorimetric and fluorescence analyses
Authors: Ngu‐Schwemlein M. , Butko P. , Cook B. , Whigham T.
Published: March 2006

Abstract:  The metal‐ion binding preferences of an acidic amphipathic cyclopeptide, cyclo[d‐Leu‐Leu‐d‐Leu‐Trp‐(d‐Glu‐Glu)2] (CP), was studied by isothermal titration calorimetry and steady‐state fluorescence spectroscopy. CP adopted a partial beta structure, and variable temperature circular dichroism showed small secondary structural changes over the temperature range from 5 °C to 95 °C. The peptide did not bind alkali or alkaline earth metal ions but exhibited selectivity for some divalent transition metal ions (with association constants KCu2+ 4.5 × 104 m−1, KZn2+ 1.6 × 105 m−1, KCd2+ 1.3 × 104 m−1, KHg2+ (1) 2.2 × 106 m−1, and KHg2+ (2) 6.5 × 103 m−1), for Pb2+ (2.0 × 105 m−1), and a trivalent Group III metal, Al3+ (1.6 × 105 m−1). The thermodynamic data show that the interaction between CP and these metal ions are spontaneous and entropically driven. A large range of binding enthalpies coupled with a smaller range of binding free energies of CP for these metal ions indicate an entropy–enthalpy compensation dependent on the ionic size of participating metal ions. The interaction of Pb2+, Hg2+, and Cu2+ with CP in aqueous solution specifically modulates the fluorescence emission properties of CP. The results of this study show that CP exhibits selectivity in metal‐ion binding, which is reflected in its fluorescence spectra. The observed trends can be useful for the design of heavy‐metal sensors based on fluorophore‐tagged acidic cyclopeptides.
Biotransformation of maximakinin, a bradykinin‐related nonadecapeptide from toad venom, by mammalian kallikrein and salivary proteases
Authors: Chen T. , O'Rourke M. , McKenna J. , Hirst D.G. , Shaw C.
Published: March 2006

Abstract:  Maximakinin is an N‐terminally extended bradykinin (DLPKINRKGPRPPGFSPFR) from the venom of a Chinese toad (Bombina maxima) that displays highly selective activity at mammalian arterial smooth muscle receptors. In this study, we report that incubation of maximakinin with either kallikrein or human saliva generates catabolites with enhanced bioactivity that retain the tissue selective effects of the parent molecule. In addition, we have observed that kallikrein rapidly cleaves the C‐terminal arginyl residue of both maximakinin and bradykinin – a cleavage hitherto considered to be performed by a carboxypeptidase that facilitates selective bradykinin receptor targeting. Maximakinin has thus evolved as a ‘smart’ defensive weapon in the toad with inherent resistance to the signal‐terminating protease hardware in the potential predator. Thus, natural selection of amphibian skin peptides for antipredator defence, through interspecies delivery by an exogenous secretory mode, produces subtle structural stabilization modifications that can potentially provide new insights for the design of orally active and selectively targeted peptide therapeutics.
Hexamer peptide affinity resins that bind the Fc region of human immunoglobulin G
Authors: Yang H. , Gurgel P.V. , Carbonell R.G.
Published: March 2006

Abstract:  A family of linear hexapeptides composed of histidine on the N‐terminus followed by aromatic amino acid(s) and positively charged amino acid(s) has been identified through a three‐step screening of a synthetic solid phase library. These peptides were able to recognize human immunoglobulin G (HIgG) through its Fc region, and their selectivity to Fc is comparable to Protein A. This is the first known report of short peptides that are able to bind HIgG by recognizing its Fc portion. One of the ligands from the identified family, HWRGWV, was examined for its ability to isolate HIgG from complex mixtures. It was found that HWRGWV possessed the potential to purify HIgG from complete mammalian cell culture medium containing 10% fetal calf serum with purity comparable to commercially available resins, but using milder elution conditions. HWRGWV bound all HIgG subclasses and IgGs from bovine, mouse, goat, and rabbit. The broad affinity spectrum as well as its Fc recognition ability may be useful in capturing and detecting both polyclonal and monoclonal antibodies.
Conformational restraints induced by modification of configuration of threonine and oxazoline residues in ascidiacyclamide analogues
Authors: Asano A. , Yamada T. , Katsuya Y. , Taniguchi T. , Sasaki M. , Doi M.
Published: March 2006

Abstract:  After designing the desoxazoline‐ascidiacyclamide diastereomers cyclo(–Ile–Thr–D‐Val–thiazole–)2 (3) and cyclo(–Ile–D‐allo‐Thr–D‐Val–thiazole–)2 (5), the molecules were treated with thionyl chloride treatments to yield the ascidiacyclamide diastereomers cyclo(–Ile–allo‐oxazoline–D‐Val–thiazole–)2 (4) and cyclo(–Ile–D‐oxazoline–D‐Val–thiazole–)2 (6). X‐ray diffraction analyses revealed the folded forms of 3 and 5 and the square form of 4. The structure of 6 was a novel reverse‐square form, and the CD spectra suggested the structures of 4 and 6 differ in solution. Whereas trifluoroethanol titration showed 4 to be conformationally flexible, 6 was comparatively rigid. The cytotoxicity of 4 was similar to that of ascidiacyclamide, but 3, 5 and 6 was not cytotoxic. Together with earlier studies, these results suggest that the conformational flexibility of ascidiacyclamide is important for its cytotoxicity.
Fragments of Nle3‐angiotensin(1–7) accelerate healing in dermal models
Authors: Rodgers K.E. , Ellefson D.D. , Espinoza T. , Maulhardt H. , Roda N. , Maldonado S. , DiZerega G.S.
Published: March 2006

Abstract:  The renin angiotensin system (RAS) has been shown to be present in dermal tissue and exogenous peptides from the RAS accelerates healing and reduces scarring. An analogue of Angiotensin(1–7) [A(1–7)], Norleucine3‐A(1–7) [Nle3‐A(1–7)], is the lead compound under development for treatment of dermal injuries. As proteases are prevalent in wounded tissue and at very high levels in chronic wounds, the ability of fragments of Nle3‐A(1–7) to accelerate healing and the effect of proteases on the peptide were determined. Daily application of fragments of Nle3‐A(1–7) of five or six amino acids accelerated healing in two models of dermal injury. In addition, the peptide was found to be stable (not substantially degraded) after incubation for 4 h in the presence of Cathepsin G, collagenases blend (from clostridium), matrix metalloprotease [MMP] 2, MMP 3, MMP 9, elastase (human leukocytic or porcine pancreatic) or plasmin. Only kallikrein, an enzyme known to cleave peptides of the RAS, cleaved the peptide into two major fragments one of which was identified as NorLeu3‐A(1–4). These data support the activity of Nle3‐A(1–7) on dermal wounds.
Pentamer peptide from Fas antigen ligand inhibits tumor‐growth with solid‐bound form found by peptide array
Authors: Kato R. , Okuno Y. , Kaga C. , Kunimatsu M. , Kobayashi T. , Honda H.
Published: March 2006

Abstract:  Despite their low molecular weight and simple structure, peptides regulate vital reactions of various cells. With higher standards of safety and purity required in clinical researches, chemically synthesized peptides are considered as an ideal alternative material for animal‐derived materials in the regulation of cellular events. However, effective high‐throughput assay for studying peptide‐cell interactions has not been established to design peptide with objective function. Here, we report the effectiveness of the utilization of peptide array combined with cell assay for the design of cell‐interactive peptides. As a model case, peptide that regulates tumor cell viability with support‐bound form was explored. By culturing cells on peptide array, we found a novel 5‐mer sequence CNNLP (Cys‐Asp‐Asp‐Leu‐Pro) that strongly inhibits viability of tumor cells (leukemia and adenocarcinoma) from human Fas antigen ligand. We here indicate the advantageous features of peptide array, which are ‘feasibility in examining combinatorial amino acid substitutions’ and ‘indicative data consist of effective and ineffective substitutions from an assay’, contributes greatly for studying peptide‐cell interaction. These features differentiate peptide array from other peptide library screening strategy. As a result, we succeeded in obtaining 29 novel tumor‐growth inhibitory peptides with it solid‐bound form, and structural rules that suggest ideal peptide design for acquiring objective peptide function.
A novel fibronectin‐related structural motif that modulates cell migration
Authors: Szaniawska B. , Kleczkowska P. , Trembacz H. , Janik P. , Lipkowski A. W.
Published: March 2006

Abstract:  Fibronectins are extracellular proteins that play important roles in normal and pathological cell functions. These proteins exert concerted effects upon various active elements, of which probably only a fraction have been well characterized. Our previous studies suggested of existence of cell membrane binding sites that interact with fibronectin, modulate cell migration without influence on intracellular biochemistry. To search for element(s) responsible for recognition of these binding sites, we synthesized several model peptides and evaluated their influence on ovarian cancer OVP 10 cells migration, phosphorylation of ERK 1/2 and FAK expression. From our results we propose the existence of specific ‘leucine membrane binding site’ (LMBS). Inhibition of ovarian cancer cells migration by neutral leucine containing peptides is a result of formation of ligand‐membrane binding site complexes that in turn alter the physicochemical properties of the membrane, and/or competitively inhibit the binding of natural activators present in the extracellular fluid. Cationic peptides, containing basic arginine or lysine residues as well as lipophilic leucine, form complexes that change membrane charge and hydrophilicity, and activate migration. Lack of specific peptide sequence requirements suggests that a range of endogenous and exogenous molecules may competitively interact with the LMBS so as to modulate the physicochemical properties of cell membranes.
Control of Platoons of Nonholonomic Vehicles Using Redundant Manipulator Analogs
Authors: Bishop Bradley E.
Published: March 2006

In this work, we consider the control of platoons of cooperating nonholonomic vehicles. Using techniques based on redundant manipulator control, the platoon is treated as a single entity with a set of platoon-level objectives. The class of tricyclelike robots, with limits on steering and speed, is chosen because it represents a vast class of real, nonholonomic vehicles beyond the basic differential drive. The method presented uses platoon redundancy to limit the impact of vehicle constraints on the platoon-level objectives. A simulation study is presented to show the efficacy of the method.
Stable Forbidden-Region Virtual Fixtures for Bilateral Telemanipulation
Authors: Abbott Jake J. , Okamura Allison M.
Published: March 2006

There has been recent interest in novel human-machine collaborative control laws, called “virtual fixtures,” which provide operator assistance for telemanipulation tasks. A forbidden-region virtual fixture is a constraint, implemented in software, that seeks to prevent the slave manipulator of a master/slave telemanipulation system from entering into a forbidden region of the workspace. In this paper, we consider the problem of unstable vibrations of the slave and/or master against forbidden-region virtual fixtures for a general class of telemanipulator control architectures, including those with haptic feedback. To the best of the authors’ knowledge, there has been no rigorous study of the stability of forbidden-region virtual fixtures in previous work. The system is evaluated around the master and slave equilibrium position resulting from a constant desired human input force, using a discrete state-space model. We present a method to analytically determine if instability is possible in the system. We thoroughly evaluate this method, experimentally, applying malicious user strategies that attempt to drive the system unstable. Our approach agrees with experimental results and can be used to design and analyze the stability and transient properties of a telemanipulator interacting with virtual fixtures. We show that the user can affect both slave- and master-side virtual fixture stability by modifying his or her impedance characteristics. However, the upper bound on stable slave-side virtual fixture stiffness does not depend on the particular user.
The Berkeley Lower Extremity Exoskeleton
Authors: Kazerooni H. , Steger R.
Published: March 2006

The first functional load-carrying and energetically autonomous exoskeleton was demonstrated at the University of California, Berkeley, walking at the average speed of 1.3m∕s(2.9mph) while carrying a 34kg(75lb) payload. Four fundamental technologies associated with the Berkeley lower extremity exoskeleton were tackled during the course of this project. These four core technologies include the design of the exoskeleton architecture, control schemes, a body local area network to host the control algorithm, and a series of on-board power units to power the actuators, sensors, and the computers. This paper gives an overview of one of the control schemes. The analysis here is an extension of the classical definition of the sensitivity function of a system: the ability of a system to reject disturbances or the measure of system robustness. The control algorithm developed here increases the closed-loop system sensitivity to its wearer’s forces and torques without any measurement from the wearer (such as force, position, or electromyogram signal). The control method has little robustness to parameter variations and therefore requires a relatively good dynamic model of the system. The trade-offs between having sensors to measure human variables and the lack of robustness to parameter variation are described.
Controlling the Apparent Inertia of Passive Human-Interactive Robots
Authors: Worsnopp Tom , Peshkin Michael , Lynch Kevin , Colgate J. Edward
Published: March 2006

Passive robotic devices may exhibit a spatially varying apparent inertia perceptible to a human user. The apparent inertia is the projection of the inertia matrix onto the instantaneous direction of motion. The spatial variation is due to the configuration dependence of the inertia matrix and relevant to many passive mechanisms, including programmable constraint machines or “cobots,” which use low-power steering actuators to choose the direction of motion. We develop two techniques for controlling the apparent inertia in cobots to emulate the desired inertial properties of a virtual object or mechanism. The first is a path-limiting method, which constraints the cobot to steer along certain paths where the apparent inertia and desired inertia are equivalent. The second uses a low-power actuator to control the apparent inertia by driving the device along its direction of motion. We illustrate these ideas for a two-link cobot we have built for experiments in human motor control and rehabilitation. For the actuated control method, we show that the power actuator can be relatively low power compared to the actuators of a traditional robot performing similar tasks.
Kinetostatic Design Considerations for an Articulated Leg-Wheel Locomotion Subsystem
Authors: Jun Seung Kook , White Glenn D. , Krovi Venkat N.
Published: March 2006

Our long-term goal is one of designing land-based vehicles to provide enhanced uneven-terrain locomotion capabilities. In this paper, we examine and evaluate candidate articulated leg-wheel subsystem designs for use in such vehicle systems. The leg-wheel subsystem designs under consideration consist of disk wheels attached to the chassis through an articulated linkage containing multiple lower-pair joints. Our emphasis is on creating a design that permits the greatest motion flexibility between the chassis and wheel while maintaining the smallest degree-of-freedom (DOF) within the articulated chain. We focus our attention on achieving two goals: (i) obtaining adequate ground clearance by designing the desired/feasible motions of the wheel axle, relative to the chassis, using methods from kinematic synthesis; and (ii) reducing overall actuation requirements by a judicious mix of structural equilibration design and spring assist. This process is examined in detail in the context of two candidate single-degree-of-freedom designs for the articulated-leg-wheel subsystems—a coupled-serial-chain configuration and a four-bar configuration. We considered the design synthesis of planar variants of the two candidate designs surmounting a representative obstacle profile while supporting a set of end-effector loads and highlight the key benefits in the presented results.
Control of Closed Kinematic Chains Using A Singularly Perturbed Dynamics Model
Authors: Wang Zhiyong , Ghorbel Fathi H.
Published: March 2006

In this paper, we propose a novel approach to the control of closed kinematic chains (CKCs). This method is based on a recently developed singularly perturbed model for CKCs. Conventionally, the dynamics of CKCs are described by differential-algebraic equations (DAEs). Our approach transfers the control of the original DAE system to the control of an artificially created singularly perturbed system in which the slow dynamics corresponds to the original DAE when the perturbation parameter tends to zero. Compared to control schemes that rely on solving nonlinear algebraic constraint equations, the proposed method uses an ordinary differential equation (ODE) solver to obtain the dependent coordinates, hence, eliminates the need for Newton-type iterations and is amenable to real-time implementation. The composite Lyapunov function method is used to show that the closed-loop system, when controlled by typical open kinematic chain schemes, achieves asymptotic trajectory tracking. Simulations and experimental results on a parallel robot, the Rice planar Delta robot, are also presented to illustrate the efficacy of our method.
Mice Transgenic for a Human Porcine Endogenous Retrovirus Receptor Are Susceptible to Productive Viral Infection
Authors: Martina Y. , Marcucci K. T. , Cherqui S. , Szabo A. , Drysdale T. , Srinivisan U. , Wilson C. A. , Patience C. , Salomon D. R.
Published: March 2006

Porcine endogenous retrovirus (PERV) is considered one of the major risks in xenotransplantation. No valid animal model has been established to evaluate the risks associated with PERV transmission to human patients by pig tissue xenotransplantation or to study the potential pathogenesis associated with PERV infection. In previous work we isolated two genes encoding functional human PERV receptors and proved that introduction of these into mouse fibroblasts allowed the normally nonpermissive mouse cells to become productively infected (T. A. Ericsson, Y. Takeuchi, C. Templin, G. Quinn, S. F. Farhadian, J. C. Wood, B. A. Oldmixon, K. M. Suling, J. K. Ishii, Y. Kitagawa, T. Miyazawa, D. R. Salomon, R. A. Weiss, and C. Patience, Proc. Natl. Acad. Sci. USA 100:6759-6764, 2003). In the present study we created mice transgenic for human PERV-A receptor 2 (HuPAR-2). After inoculation of transgenic animals with infectious PERV supernatants, viral DNA and RNA were detected at multiple time points, indicating productive replication. This establishes the role of HuPAR-2 in PERV infection in vivo; in addition, these transgenic mice represent a new model for determining the risk of PERV transmission and potential pathogenesis. These mice also create a unique opportunity to study the immune response to PERV infection and test potential therapeutic or preventative modalities.
Action of Inhibitors on Accumulation of Processed Hepatitis Delta Virus RNAs
Authors: Chang Jinhong , Nie Xingcao , Gudima Severin , Taylor John
Published: March 2006

Hepatitis delta virus (HDV) replication involves processing and accumulation of three RNA species: the genome, its exact complement (the antigenome), and a polyadenylated mRNA that acts as a template for the small delta antigen (δAg), the only protein of HDV and essential for genome replication. In a recently reported experimental system, addition of tetracycline induced synthesis of a DNA-directed source of δAg, producing within 24 h a significant increase in accumulation of newly transcribed and processed HDV RNAs. This induction was used here to study the action of various inhibitors on accumulation. For example, potent and HDV-specific inhibition, in the absence of detected host toxicity, could be obtained with ribavirin, mycophenolic acid, and viramidine. An interpretation is that these inhibitors reduced the available GTP pool, leading to a specific inhibition of the synthesis and accumulation of HDV RNA-directed RNA species. In contrast, no inhibition was observed with
l
-FMAU (2′-fluoro-5-methyl-β-
l
-arabinofuranosyl-uridine), alpha interferon, or pegylated alpha interferon. After modifications to the experimental system, it was also possible to examine the effects of three known host RNA polymerase inhibitors on HDV genome replication: amanitin, 5,6-dichloro-1-β-
d
-ribofuranosylbenzimidazole (DRB), and actinomycin. Of most interest, amanitin at low doses blocked accumulation of HDV RNA-directed mRNA but had less effect on HDV genomic and antigenomic RNAs. Additional experiments indicated that this apparent resistance to amanitin inhibition of genomic and antigenomic RNA relative to mRNA may not reflect a difference in the transcribing polymerase but rather relative differences in the processing and stabilization of nascent RNA transcripts.
Sequences within thegagGene of Mouse Mammary Tumor Virus Needed for Mammary Gland Cell Transformation
Authors: Swanson Ingrid , Jude Brooke A. , Zhang Annie R. , Pucker Andrew , Smith Zachary E. , Golovkina Tatyana V.
Published: March 2006

Previously, we identified a group of replication-competent exogenous mouse mammary tumor viruses that failed to induce mammary tumors in susceptible mice. Sequence comparison of tumorigenic and tumor-attenuated virus variants has linked the ability of virus to cause high-frequency mammary tumors to thegaggene. To determine the specific sequences within thegaggene that contribute to tumor induction, we constructed five distinct chimeric viruses that have various amino acid coding sequences ofgagderived from a tumor-attenuated virus replaced by those of highly tumorigenic virus and tested these viruses for tumorigenic capacities in virus-susceptible C3H/HeN mice. Comparing the tumorigenic potentials of these viruses has allowed us to map the region responsible for tumorigenesis to a 253-amino-acid region within the CA and NC regions of the Gag protein. Unlike C3H/HeN mice, BALB/cJ mice develop tumors when infected with all viral variants, irrespective of thegaggene sequences. Using genetic crosses between BALB/cJ and C3H/HeN mice, we were able to determine that the mechanism that confers susceptibility to Gag-independent mammary tumors in BALB/cJ mice is inherited as a dominant trait and is controlled by a single gene, called mammary tumor susceptibility (mts), that maps to chromosome 14.
Varicella-Zoster Virus Open Reading Frame 10 Is a Virulence Determinant in Skin Cells but Not in T Cells In Vivo
Authors: Che Xibing , Zerboni Leigh , Sommer Marvin H. , Arvin Ann M.
Published: March 2006

The open reading frame 10 (ORF10) of varicella-zoster virus (VZV) encodes a tegument protein that enhances transactivation of VZV genes and has homology to herpes simplex virus type 1 (HSV-1) VP16. While VP16 is essential for HSV replication, ORF10 is dispensable for vaccine OKA (VOKA) growth in vitro. We used parent OKA (POKA) cosmids to delete ORF10, producing POKAΔ10; point mutations that disrupted the acidic activation domain and the putative motif for binding human cellular factor 1 (HCF-1) in ORF10 protein yielded POKA10-Phe28Ala, POKA10-Phe28Ser, and POKA10-mHCF viruses. Deleting ORF10 or mutating these two functional domains had no effect on VZV replication, immediate-early gene transcription, or virion assembly in vitro. However, deleting ORF10 reduced viral titers and the extent of cutaneous lesions significantly in SCIDhu skin xenografts in vivo compared to POKA. Epidermal cells infected with POKAΔ10 had significantly fewer DNA-containing nucleocapsids and complete virions compared to POKA; extensive aggregates of intracytoplasmic viral particles were also observed. Altering the activation or the putative HCF-1 domains of ORF10 protein had no consequences for VZV replication in vivo. Thus, the decreased pathogenic potential of POKAΔ10 in skin could not be attributed to absence of these ORF10 protein functions. In contrast to skin cells, deleting ORF10 did not impair VZV T-cell tropism in vivo, as assessed by infectious virus yields. We conclude that ORF10 protein is required for efficient VZV virion assembly and is a specific determinant of VZV virulence in epidermal and dermal cells in vivo.
Astrocytes Survive Chronic Infection and Cytopathic Effects of thets1 Mutant of the Retrovirus Moloney Murine Leukemia Virus by Upregulation of Antioxidant Defenses
Authors: Qiang Wenan , Kuang Xianghong , Liu Jinrong , Liu Na , Scofield Virginia L. , Reid Amy J. , Jiang Yuhong , Stoica Gheorghe , Lynn William S. , Wong Paul K. Y.
Published: March 2006

Thets1 mutant of Moloney murine leukemia virus (MoMuLV) induces a neurodegenerative disease in mice, in which glial cells are infected by the retrovirus but neurons are not.ts1 infection of primary astrocytes, or of the immortalized astrocytic cell line C1, results in accumulation of thets1 gPr80envenvelope protein in the endoplasmic reticulum (ER), with ER and oxidative stress. Notably, only about half of the infected astrocytes die in these cultures, while the other half survive, continue to proliferate, and continue to produce virus. To determine how these astrocytes survivets1 infection in culture, we established a chronically infected subline of the living cells remaining after the death of all acutely infected cells in an infected C1 cell culture (C1-ts1-S). We report here that C1-ts1-S cells proliferate more slowly, produce less virus, show reduced H2O2levels, increase their uptake of cystine, and maintain higher levels of intracellular GSH and cysteine compared to acutely infected or uninfected C1 cells. C1-ts1-S cells also upregulate their thiol antioxidant defenses by activation of the transcription factor NF-E2-related factor 2 (Nrf2) and its target genes. Interestingly, despite maintenance of higher levels of intracellular reduced thiols, C1-ts1-S cells are more sensitive to cystine deprivation than uninfected C1 cells. We conclude that somets1-infected astrocytes survive and adapt to virus-induced oxidative stress by successfully mobilizing their thiol redox defenses.
Selection of Novel Vesicular Stomatitis Virus Glycoprotein Variants from a Peptide Insertion Library for Enhanced Purification of Retroviral and Lentiviral Vectors
Authors: Yu Julie H. , Schaffer David V.
Published: March 2006

The
introduction of new features or functions that are not present in an
original protein is a significant challenge in protein engineering. For
example, modifications to vesicular stomatitis virus glycoprotein
(VSV-G), which is commonly used to pseudotype retroviral and lentiviral
vectors for gene delivery, have been hindered by a lack of structural
knowledge of the protein. We have developed a transposon-based approach
that randomly incorporates designed polypeptides throughout a protein
to generate saturated insertion libraries and a subsequent
high-throughput selection process in mammalian cells that enables the
identification of optimal insertion sites for a novel designed
functionality. This method was applied to VSV-G in order to construct a
comprehensive library of mutants whose combined members have a
His
6
tag inserted at likely every site in the original
protein sequence. Selecting the library via iterative retroviral
infections of mammalian cells led to the identification of several
VSV-G-His
6
variants that were able to package high-titer
viral vectors and could be purified by Ni-nitrilotriacetic acid
affinity chromatography. Column purification of vectors reduced protein
and DNA impurities more than 5,000-fold and 14,000-fold, respectively,
from the viral supernatant. This substantially improved purity elicited
a weaker immune response in the brain, without altering the infectivity
or tropism from wild-type VSV-G-pseudotyped vectors. This work applies
a powerful new tool for protein engineering to construct novel viral
envelope variants that can greatly improve the safety and use of
retroviral and lentiviral vectors for clinical gene therapy.
Furthermore, this approach of library generation and selection can
readily be extended to other challenges in protein
engineering.
Competitive Translation Efficiency at the Picornavirus Type 1 Internal Ribosome Entry Site Facilitated by ViralcisandtransFactors
Authors: Dobrikova Elena Y. , Grisham Rachel N. , Kaiser Constanze , Lin Jennifer , Gromeier Matthias
Published: March 2006

Enteroviruses (EVs) overcome their host cells by usurping the translation machinery to benefit viral gene expression. This is accomplished through alternative translation initiation in a cap-independent manner at the viral internal ribosomal entry site (IRES). We have investigated the role ofcis- andtrans-acting viral factors in EV IRES translation in living cells. We observed that considerable portions of the viral genome, including the 5′-proximal open reading frame and the 3′ untranslated region, contribute to stimulation of IRES-mediated translation. With the IRES in proper context, translation via internal initiation in uninfected cells is as efficient as at capped messages with short, unstructured 5′ untranslated regions. IRES function is enhanced in cells infected with the EV coxsackievirus B3, but the related poliovirus has no significant stimulatory activity. This differential is due to the inherent properties of their 2A protease and is not coupled to 2A-mediated proteolytic degradation of the eukaryotic initiation factor 4G. Our results suggest that the efficiency of alternative translation initiation at EV IRESs depends on a properly configured template rather than on targeted alterations of the host cell translation machinery.
Effect of Hepatitis C Virus (HCV) NS5B-Nucleolin Interaction on HCV Replication with HCV Subgenomic Replicon
Authors: Shimakami Tetsuro , Honda Masao , Kusakawa Takashi , Murata Takayuki , Shimotohno Kunitada , Kaneko Shuichi , Murakami Seishi
Published: March 2006

We previously reported that nucleolin, a representative nucleolar marker, interacts with nonstructural protein 5B (NS5B) of hepatitis C virus (HCV) through two independent regions of NS5B, amino acids 208 to 214 and 500 to 506. We also showed that truncated nucleolin that harbors the NS5B-binding region inhibited the RNA-dependent RNA polymerase activity of NS5B in vitro, suggesting that nucleolin may be involved in HCV replication. To address this question, we focused on NS5B amino acids 208 to 214. We constructed one alanine-substituted clustered mutant (CM) replicon, in which all the amino acids in this region were changed to alanine, as well as seven different point mutant (PM) replicons, each of which harbored an alanine substitution at one of the amino acids in the region. After transfection into Huh7 cells, the CM replicon and the PM replicon containing NS5B W208A could not replicate, whereas the remaining PM replicons were able to replicate. In vivo immunoprecipitation also showed that the W208 residue of NS5B was essential for its interaction with nucleolin, strongly suggesting that this interaction is essential for HCV replication. To gain further insight into the role of nucleolin in HCV replication, we utilized the small interfering RNA (siRNA) technique to investigate the knockdown effect of nucleolin on HCV replication. Cotransfection of replicon RNA and nucleolin siRNA into Huh7 cells moderately inhibited HCV replication, although suppression of nucleolin did not affect cell proliferation. Taken together, our findings strongly suggest that nucleolin is a host component that interacts with HCV NS5B and is indispensable for HCV replication.