Effect of cultured autologous chondrocytes on repair of chondral defects in a canine model

Articular cartilage has a limited capacity for repair. In recent clinical and animal experiments, investigators have attempted to elicit the repair of defects of articular cartilage by injecting cultured autologous chondrocytes under a periosteal flap (a layer of periosteum). The objective of the present study was to determine the effect of cultured autologous chondrocytes on healing in an adult canine model with use of histomorphometric methods to assess the degree of repair. A total of forty-four four-millimeter-diameter circular defects were created down to the zone of calcified cartilage in the articular cartilage of the trochlear groove of the distal part of the femur in fourteen dogs. The morphology and characteristics of the original defects were defined in an additional six freshly created defects in three other dogs. Some residual noncalcified articular cartilage, occupying approximately 2 per cent of the total cross-sectional area of the defect, was sometimes left in the defect. The procedure sometimes damaged the calcified cartilage, resulting in occasional microfractures or larger fractures, thinning of the zone of calcified cartilage, or, rarely, small localized penetrations into subchondral bone. The forty-four defects were divided into three treatment groups. In one group, cultured autologous chondrocytes were implanted under a periosteal flap. In the second group, the defect was covered with a periosteal flap but no autologous chondrocytes were implanted. In the third group (the control group), the defects were left empty. The defects were analyzed after twelve or eighteen months of healing. Histomorphometric measurements were made of the percentage of the total area of the defect that became filled with repair tissue, the types of tissue that filled the defect, and the integration of the repair tissue with the adjacent cartilage at the sides of the defects and with the calcified cartilage at the base of the defect. In histological sections made through the center of the defects in the three groups, the area of the defect that filled with new repair tissue ranged from a mean total value of 36 to 76 per cent, with 10 to 23 per cent of the total area consisting of hyaline cartilage. Integration of the repair tissue with the adjacent cartilage at the edges of the defect ranged from 16 to 32 per cent in the three groups. Bonding between the repair tissue and the calcified cartilage at the base of the defect ranged from 41 to 89 per cent. With the numbers available, we could detect no significant difference among the three groups with regard to any of the parameters used to assess the quality of the repair. In the two groups in which a periosteal flap was sutured to the articular cartilage surrounding the defect, the articular cartilage showed degenerative changes that appeared to be related to that suturing.     

Scattering of screened excitons by free carriers in semiconductingquantum well structures

The theoretical treatment of the scattering of excitons by free electrons and holes in a two-dimensional semiconducting quantum-well system is extended to take into account screening by the free carriers. The scattering cross sections are calculated using the Born approximation for elastic scattering of the excitons by the free carriers. For the heavy-hole exciton, the screening by the free carriers reduces the cross section for free-carrier exciton scattering for all values of the energy of relative motion of the free carriers and the excitors. For the light-hole exciton, however, screening can actually lead to an enhancement of the scattering cross section for low values of the energy of relative motion when the density of free carriers is high. This is because screening not only reduces the interaction between the free carriers and the exciton, but also decreases the binding of the exciton, leading to a larger effective radius of the exciton. The results for the scattering cross sections are then applied to calculate the contribution of the exciton linewidth due to elastic scattering of the excitons by free carriers. It is found that this contribution to the exciton linewidth is decreased below its value in the absence of screening for both the heavy- and light-hole excitons     

Rehabilitation psychology: Exploring issues.

Rehabilitation Psychology has several goals. One of its primary functions is to disseminate information that promotes the effective use of knowledge. While really new and current developments in rehabilitation interventions having psychological components may be known to the reader long before discussion of them appears in Rehabilitation Psychology, few "new findings" are dealt with to everyone's complete satisfaction. Many opinions exist about the efficacy of most innovative strategies; these conflicting views often are diverse, if not controversial. Therefore, it is helpful to provide professionals a forum in which they can discuss a problem and offer different viewpoints and perspectives that promote its resolution. I hope to make the journal such a forum within which these varying viewpoints can be heard. As Editor, I view Rehabilitation Psychology as being the single most significant organ through which the field can acquire additional clarity and identity. I view the role of Editor as being similar to that of a gatekeeper. The role entails major responsibility for ensuring that clinicians and academicians have an opportunity to present their findings and their opinions about critical issues facing the field. It is a role I hope to fulfill with competence and sensitivity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

High power non-linear magnetophotoconductivity in n-GaAs using the UCSB free electron laser

The kinetics of electrons bound to shallow donor impurities in n-GaAs was investigated by saturation spectroscopy using the University of California at Santa Barbara free electron laser. The resonant photothermal conductivity from 1s–2p⁺ transitions was measured at intensities greatly exceeding previous studies. Saturation of bound-to-free photoionization transitions was measured from 0 to 4 Tesla. The 1s–2p⁺ resonant photoconductive signal shows a distinct intensity dependence caused by the competing bound-to-free transitions which saturate differently. Evaluation of the electron recombination kinetics allows us to calculate the transition time of electrons from the 2p⁺ level to the ground state, the recombination time of free electrons, and the thermal ionization probability of the 2p⁺ state.     

On the intermolecular potential in solid N2

An anisotropic intermolecular potential for solid N₂ is proposed in terms of a sum of multipole-like interactions. The potential is shown to lead to an - transition. Furthermore, the hexadecapolar terms in the hard-core potential reduce the libronic frequencies atT=0K to approximately those calculated with the electric quadrupole potential alone. It is suggested that the smallness of the hexadecapolar terms in the 6–12 atom—atom potential accounts for its inability to explain the properties of solid N₂ Research supported by the USAF-Aerospace Research Laboratory under contract no. F-3-3615-71-C-1820.     

Using the Job-Related Affective Well-Being Scale (JAWS) to investigate affective responses to work stressors.

Prior research linking job stressors to psychological strains has been limited to a small number of emotional reactions. This article describes research linking job stressors to a wide range of affective states at work. In Study 1, a multidimensional scaling procedure was used on a matrix of similarity judgments by 51 employees of 56 job-related affective statements to support a 2-dimensional view of affective well-being. In Study 2, ratings of the affect statements by 100 employees further supported the contention that the dimensions were pleasure–displeasure and degree of arousal. In Study 3, 114 full-time university employees responded to the Job-Related Affective Well-Being Scale, which was found to be related to measures of job stressors as well as job satisfaction and physical symptoms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sexual Versus Nonsexual Workplace Aggression and Victims' Overall Job Satisfaction: A Meta-Analysis.

A meta-analytic approach was used to examine whether sexual and nonsexual forms of nonviolent workplace aggression (both verbal and nonverbal) share equivalent or differential relationships with victims' overall job satisfaction. When the meta-analytic comparison was restricted to all-female samples to hold victims' gender constant, nonsexual aggression was found to share a significantly stronger negative relationship with victims' overall job satisfaction than was sexual aggression. In addition, nonsexual aggression was found to share a stronger negative link with women's level of job satisfaction than with men's. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Recent Advances in Light-Controlled Activation of Pt(IV) Prodrugs

Pt(IV) prodrugs remain one of the most promising alternatives to conventional Pt(II) therapy due to their versatility in axial ligand choice and delayed mode of action. Selective activation from an external source is especially attractive due to the opportunity to control the activity of an antitumor drug in space and time and avoid damage to normal tissues. In this review, we discuss recent advances in photoabsorber-mediated photocontrollable activation of Pt(IV) prodrugs. Two main approaches developed are the focus of the review. The first one is the photocatalytic strategy based on the flavin derivatives that are not covalently bound to the Pt(IV) substrate. The second one is the conjugation of photoactive molecules with the Pt(II) drug via axial position, yielding dual-action Pt(IV) molecules capable of the controllable release of Pt(II) cytotoxic agents. Thus, Pt(IV) prodrugs with a light-controlled mode of activation are non-toxic in the absence of light, but show high antiproliferative activity when irradiated. The susceptibility of Pt(IV) prodrugs to photoreduction, photoactivation mechanisms, and biological activity is considered in this review.     

Robonaut: a robot designed to work with humans in space

The Robotics Technology Branch at the NASA Johnson Space Center is developing robotic systems to assist astronauts in space. One such system, Robonaut, is a humanoid robot with the dexterity approaching that of a suited astronaut. Robonaut currently has two dexterous arms and hands, a three degree-of-freedom articulating waist, and a two degree-of-freedom neck used as a camera and sensor platform. In contrast to other space manipulator systems, Robonaut is designed to work within existing corridors and use the same tools as space walking astronauts. Robonaut is envisioned as working with astronauts, both autonomously and by teleoperation, performing a variety of tasks including, routine maintenance, setting up and breaking down worksites, assisting crew members while outside of spacecraft, and serving in a rapid response capacity.