Interface potential of calcium phosphate in simulated body fluid

Calcium phosphate ceramics are used in the substitution of injured or damaged bones. Nevertheless, the behaviour of these materials, and in particular, the mechanisms guiding their interface response in physiological environment is still unknown. This work describes the construction of hydroxyapatite and tricalcium phosphate electrodes used to determine the interface potential behaviour of these materials in a simulated body fluid, in a pH range corresponding to the variation observed in human body injuries, at ambient and physiological temperatures. These measurements are associated with the adsorption/desorption of ions from the materials. The results show that hydroxyapatite and tricalcium phosphate have similar behaviour in that they reach an interface potential equilibrium state faster when the solution pH is decreased and the temperature increased. This behaviour may be attributed to their ability to form a calcium-rich layer and is relevant to their quality as implantable materials.     

The production of interleukin-1 alpha immunoreactivity by human oviductal cells in a coculture system

PURPOSE: The aim of this study was to determine the concentration of interleukin-1 alpha in human embryo culture medium with or without oviductal cell coculture and to correlate the interleukin-1 alpha levels with pregnancy. METHODS: Culture media from 32 in vitro fertilization and embryo transfer cycles were assayed for interleukin-1 alpha by immunoassay technique. Human embryos were cultured in Earles' balanced salt solution supplemented with 15% preovulatory serum (sEBSS) in 16 of these cycles, while embryos in the rest of the cycles were cocultured with human oviductal cells in sEBSS. RESULTS: Both sEBSS and spent sEBSS after embryo culture contained low or undetectable levels of interleukin-1 alpha in the pregnant and nonpregnant cycles. On the other hand, oviductal cells significantly increased the amount of interleukin-1 alpha immunoreactivity in the conventional culture medium or coculture medium (P < 0.001, Mann-Whitney rank sum test). The concentrations of interleukin-1 alpha in the spent sEBSS after oviductal cell culture and after coculture with human embryos were 1.5 +/- 1.0 and 1.3 +/- 0.9 pg/ml, respectively. There was no difference in the interleukin-1 alpha concentration between the pregnant and the nonpregnant coculture cycles. CONCLUSIONS: These data showed that human oviductal cells produced interleukin-1 alpha immunoreactivity in a coculture system. However, this production could not be used as a marker for successful embryo implantation.     

Quantitation of intrathecal measles virus IgG antibody synthesis rate: subacute sclerosing panencephalitis and multiple sclerosis

A method for quantitating specific anti-viral antibodies in serum and cerebrospinal fluid (CSF) is established using enzyme-linked immunosorbent assay (ELISA). Quantitated antibody levels are used to determine intrathecal specific IgG synthesis rate for the particular antibody. Measles virus was used as a model for validating this quantitative technique: a mutated form of measles virus is a cause of subacute sclerosing panencephalitis (SSPE) and there is a possibility that measles virus is related to the cause of multiple sclerosis (MS). Matched serum and CSF samples were assayed. Concentration of anti-measles IgG was determined and intrathecal measles-specific IgG synthesis rate was calculated. For the SSPE samples, measles-specific IgG synthesis rate was elevated and comprised > 20% of the total intrathecal IgG synthesis rate; these results are consistent with the literature. The ELISA method can be performed routinely, providing a quick, simple, reproducible means of quantitating specific antibody concentrations, with sensitivity greater than 1 nanogram per milliliter. With this method, quantitation of IgG antibodies to any other viral antigen can be reliably and precisely determined.     

A method for exploring the effects of attrition in randomized experiments with dichotomous outcomes.

Attrition from conditions in randomized experiments is common. Yet it is difficult to assess the possible effects of attrition because the outcome status of the dropouts is usually unknown. This article develops methods to assess those effects in studies with dichotomous outcomes, illustrating the methods with randomized experiments in drug abuse treatment, smoking cessation treatment, and alcoholism treatment. The methods include computing the lowest and highest possible effect sizes that could have been observed, enumerating the percent of possible study outcomes below a given threshold, estimating the probability that an outcome beyond any given threshold would be observed if all participants were measured, and constructing attrition analysis plots showing the effects of attrition under varied assumptions. For the kind of study to which they apply, these methods should replace the treatment of missing participants as failures in an "intent-to-treat" analysis. A user-friendly personal computer program is available to implement all of these analyses. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Analysis of a human cDNA containing a tissue-specific alternatively spliced LIM domain

A unique clone, isolated from a human pancreatic cDNA library, was sequenced and characterized. Northern blot analysis showed that the gene is active in a number of fetal and adult tissues, and immunoblots showed expression in nuclear and cytosolic cell fractions. The gene corresponding to the clone was localized to chromosome 13 by human/rodent somatic cell hybrid panels. The largest open reading frame contains a LIM domain, and the deduced peptide from the open reading frame appears to have the characteristics of a LIM-only protein, designated LMO7. RT-PCR and genomic sequence analyses indicate that expression of this gene product is subject to tissue-specific modulation by elimination of the LIM domain by alternative splicing in neural tissues.     

Spatially resolved X-ray diffraction phase mapping and α → β → α transformation kinetics in the heat-affected zone of commercially pure titanium arc welds

Spatially resolved X-ray diffraction (SRXRD) is used to map the α → β → α phase transformation in the heat-affected zone (HAZ) of commercially pure titanium gas tungsten arc welds. In situ SRXRD experiments were conducted using a 180-μm-diameter X-ray beam at the Stanford Synchrotron Radiation Laboratory (SSRL) (Stanford, CA) to probe the phases present in the HAZ of a 1.9 kW weld moving at 1.1 mm/s. Results of sequential linear X-ray diffraction scans made perpendicular to the weld direction were combined to construct a phase transformation map around the liquid weld pool. This map identifies six HAZ microstructural regions between the liquid weld pool and the base metal: (1) α-Ti that is undergoing annealing and recrystallization; (2) completely recrystallized α-Ti; (3) partially transformed α-Ti, where α-Ti and β-Ti coexist; (4) single-phase β-Ti; (5) back-transformed α-Ti; and (6) recrystallized α-Ti plus back-transformed α-Ti. Although the microstructure consisted predominantly of α-Ti, both prior to and after the weld, the crystallographically textured starting material was altered during welding to produce different α-Ti textures within the resulting HAZ. Based on the travel speed of the weld, the α → β transformation was measured to take 1.83 seconds during heating, while the β → α transformation was measured to take 0.91 seconds during cooling. The α → β transformation was characterized to be dominated by long-range diffusional growth on the leading (heating) side of the weld, while the β → α transformation was characterized to be predominantly massive on the trailing (cooling) side of the weld, with a massive growth rate on the order of 100 μm/s.     

Wavelet decomposition of harmonizable random processes

The discrete wavelet decomposition of second-order harmonizable random processes is considered. The deterministic wavelet decomposition of a complex exponential function is examined, where its pointwise and bounded convergence to the function is proved. This result is then used for establishing the stochastic wavelet decomposition of harmonizable processes. The similarities and differences between the wavelet decompositions of general harmonizable processes and a subclass of processes having no spectral mass at zero frequency, e.g., those that are wide-sense stationary and have continuous power spectral densities, are also investigated. The relationships between the harmonization of a process and that of its wavelet decomposition are examined. Finally, certain linear operations such as addition, differentiation, and linear filtering on stochastic wavelet decompositions are considered. It is shown that certain linear operations can be performed term by term with the decomposition     

Supporting collaborative engineering design

The complexity of current engineering design demands the collaboration of specialists. Collaboration involves both communication between and coordination among members of a design team. Currently, design collaboration is carried out through the use of schedules, specifications and drawings which only capture the end results of the design process. They fail to record important design information such as the reasoning behind design decisions. In this paper, we describe a tool CADS, that supports collaboration in engineering design. CADS is based on an extension to the Axiomatic Design methodology which not only captures the design elements but also the rationale used to conceive them. CADS serves as a shared database of design information with facilities that support communication and coordination in engineering design.Currently at the Media Laboratory, MIT.