Personalized Hydrogels for Engineering Diverse Fully Autologous Tissue Implants

Despite incremental improvements in the field of tissue engineering, no technology is currently available for producing completely autologous implants where both the cells and the scaffolding material are generated from the patient, and thus do not provoke an immune response that may lead to implant rejection. Here, a new approach is introduced to efficiently engineer any tissue type, which its differentiation cues are known, from one small tissue biopsy. Pieces of omental tissues are extracted from patients and, while the cells are reprogrammed to become induced pluripotent stem cells, the extracellular matrix is processed into an immunologically matching, thermoresponsive hydrogel. Efficient cell differentiation within a large 3D hydrogel is reported, and, as a proof of concept, the generation of functional cardiac, cortical, spinal cord, and adipogenic tissue implants is demonstrated. This versatile bioengineering approach may assist to regenerate any tissue and organ with a minimal risk for immune rejection.     

Derandomized Parallel Repetition via Structured PCPs

A PCP is a proof system for NP in which the proof can be checked by a probabilistic verifier. The verifier is only allowed to read a very small portion of the proof and in return is allowed to err with some bounded probability. The probability that the verifier accepts a proof of a false claim is called the soundness error and is an important parameter of a PCP system that one seeks to minimize. Constructing PCPs with subconstant soundness error and, at the same time, a minimal number of queries into the proof (namely two) is especially important due to applications for inapproximability.     

Journey to the Past: Verifying and Modifying the Conceptual Sources of Decimal Fraction Knowledge

Abstract

The present study follows earlier research on fraction unit conception in learning decimals and shows that children with this difficulty also exhibit a similar problem in fractions. Specifically, the focus on the fraction unit observed in decimals (e.g., evaluating 0.4 as larger than 0.68 because tenths are larger than hundredths) is preceded by a similar deficient coordination between the size of the fraction unit and the number of units in determining fraction value. Approximately three quarters of 59 students in seventh and eighth grades identified as having a fraction unit conception in decimals were also identified as having a similar fraction unit focus in fractions. The impact of fraction knowledge was further demonstrated by showing that “changing the past” through meaningful instruction in fractions affected the “present” and transferred to decimals.     

Moving or Improving: Housing Adjustment Choice in Kumasi,Ghana

This paper examines housing adjustment choice of households in Kumasi, Ghana. When a household is dissatisfied with its housing, it can choose to move elsewhere, improve the current dwelling, or neither. Using data from a 596-household survey collected in 1996, logistic regressions are used to examine the determinants of this choice. Results suggest that housing satisfaction and quality, plus some household characteristics, influence the choice of undertaking housing adjustment (including moving and improving). When a household decides to adjust, factors affecting the choice between moving and improving are housing conditions, tenure, household characteristics, and using housing for income generation through informal-sector activities.     

Extracellular Vesicles as Emerging Players in Intercellular Communication: Relevance in Mast Cell-Mediated Pathophysiology

Mast cells are major effector cells in eliciting allergic responses. They also play a significant role in establishing innate and adaptive immune responses, as well as in modulating tumor growth. Mast cells can be activated upon engagement of the high-affinity receptor FcεRI with specific IgE to multivalent antigens or in response to several FcεRI-independent mechanisms. Upon stimulation, mast cells secrete various preformed and newly synthesized mediators. Emerging evidence indicates their ability to be a rich source of secreted extracellular vesicles (EVs), including exosomes and microvesicles, which convey biological functions. Mast cell-derived EVs can interact with and affect other cells located nearby or at distant sites and modulate inflammation, allergic response, and tumor progression. Mast cells are also affected by EVs derived from other cells in the immune system or in the tumor microenvironment, which may activate mast cells to release different mediators. In this review, we summarize the latest data regarding the ability of mast cells to release or respond to EVs and their role in allergic responses, inflammation, and tumor progression. Understanding the release, composition, and uptake of EVs by cells located near to or at sites distant from mast cells in a variety of clinical conditions, such as allergic inflammation, mastocytosis, and lung cancer will contribute to developing novel therapeutic approaches.     

Detection of bacteria using foreign DNA: the development of a bacteriophage reagent for Salmonella

A phage-based reagent was developed for the detection of Salmonella in food samples. The parental phage was Felix 01, which lyses practically all Salmonella. Using data obtained about the molecular biology of the phage, a recombinant phage that carried the bacterial genes specifying luciferase was produced. The method involved the isolation of amber nonsense mutations and subsequent crosses to render doubly mutant phage with a very low reversion rate on strains lacking an amber suppressor. A plasmid was constructed that contained a segment of Felix 01 DNA with two adjacent genes, one dispensable and the other essential, and their flanking sequences. Recombinant DNA technology was used to remove the two genes and the luxA and luxB genes for luciferase, and a gene specifying a tRNA that recognizes amber codons (supF=tyrT) was put in their stead. This region could be transferred into the genome of the phage by homologous recombination. The recombinant phage cannot grow because it lacks an essential gene. However, it can grow in a host that synthesizes the missing protein. This technique allows the construction of "locked" recombinant phages that carry foreign DNA but which cannot propagate themselves in nature.     

Expression and possible involvement of calpain isoforms in mammalian egg activation

At fertilization in mammals, the spermatozoon triggers a unique signal transduction mechanism within the egg, leading to its activation. It is well accepted that the earliest event observed in all activated eggs is an abrupt rise in intracellular calcium concentrations. However, little is known regarding the downstream proteins that are activated by this rise in calcium. Calpains constitute a family of intracellular calcium-dependent cysteine proteases whose members are expressed widely in a variety of cells. We investigated the expression and possible role of the calpain isoforms mu and m throughout egg activation. Both calpains were expressed in the rat egg and localized at the egg cortex as well as in the meiotic spindle. m Calpain translocated to the membrane and to the spindle area during parthenogenetic egg activation and during in vivo fertilization, upon sperm binding to the egg. The cytoskeletal protein alpha-spectrin (fodrin) was proteolysed by calpain during the egg-activation process, as demonstrated by specific calpain-breakdown products. Following parthenogenetic activation by ionomycin or puromycin, the calpain-selective permeable inhibitor, calpeptin, inhibited the resumption of meiosis and cortical reaction in a dose-dependent manner. Calpeptin was also effective in inhibiting in vitro fertilization. These results may imply a correlation between calpain activation and mammalian egg activation at fertilization and a possible role for calpain in the cascade of cellular events leading to resumption of meiosis.     

Efficient frequency doubling by a phase-compensated crystal in a semimonolithic cavity

In multiple-pass nonlinear frequency conversion devices, interacting waves may accumulate different phases, owing to dispersive elements in the system. Phase compensation is therefore necessary for efficient frequency conversion. We experimentally demonstrate phase compensation in a compact semimonolithic frequency-doubling cavity by using a periodically poled KTP crystal. The conversion efficiency of the crystal was found to decrease at high pump powers, owing to power-dependent thermal lensing. This experimental observation was supported by a theoretical calculation of the conversion efficiency in a cavity, considering the mismatch between the mode's thermally loaded and unloaded cavities. A design procedure was also presented to compensate for the thermal lensing effect. The highest conversion efficiency of 56.5%, corresponding to a second-harmonic power of 117.5 mW at 532 nm, was achieved with a cw Nd:YAG pump power of 208 mW.     

Development of a category system of good moments in Gestalt therapy.

10 nonmutually exclusive categories of good moments (i.e., client behaviors or processes represented as therapeutically valuable or desirable) developed from a review of the Gestalt literature were used to rate 458 verbal behaviors of clients drawn from 4 therapy sessions with well known Gestalt therapists. Agreement levels among judges (2 male clinical psychologists and 2 female senior PhD students in clinical psychology) ranged from acceptable to very high for 8 of the individual categories. Analyses of co-occurrences indicated that most categories included in the computations tapped separate dimensions of client behaviors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)