The effect of detergents on the basement membrane complex of a biologic scaffold material.

The basement membrane complex (BMC) is a critical component of the extracellular matrix (ECM) that supports and facilitates the growth of cells. This study investigates four detergents commonly used in the process of tissue decellularization and their effect upon the BMC. The BMC of porcine urinary bladder was subjected to 3% Triton-X 100, 8mM 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS), 4% sodium deoxycholate or 1% sodium dodecyl sulfate (SDS) for 24h. The BMC structure for each treatment group was assessed by immunolabeling, scanning electron microscopy (SEM) and second harmonic generation (SHG) imaging of the fiber network. The composition was assessed by quantification of dsDNA, glycosaminoglycans (GAG) and collagen content. The results showed that collagen fibers within samples treated with 1% SDS and 8mM CHAPS were denatured, and the ECM contained fewer GAG compared with samples treated with 3% Triton X-100 or 4% sodium deoxycholate. Human microvascular endothelial cells (HMEC) were seeded onto each BMC and cultured for 7 days. Cell-ECM interactions were investigated by immunolabeling for integrin ß-1, SEM imaging and semi-quantitative assessment of cellular infiltration, phenotype and confluence. HMEC cultured on a BMC treated with 3% Triton X-100 were more confluent and had a normal phenotype compared with HMEC cultured on a BMC treated with 4% sodium deoxycholate, 8mM CHAPS and 1% SDS. Both 8mM CHAPS and 1% SDS damaged the BMC to the extent that seeded HMEC were able to infiltrate the damaged sub-basement membrane tissue, showed decreased confluence and an atypical phenotype. The choice of detergents used for tissue decellularization can have a marked effect upon the integrity of the BMC of the resultant bioscaffold.

Strategies for the preflight circadian shifting of Space Shuttle crews.

In June, 1990, a workshop was put together at NASA/Johnson Space Center to address difficulties the astronauts were having in adjusting their wake and sleep schedule, both immediately before and during Space Shuttle missions. The workshop members, prominent investigators in human circadian research, developed a number of strategies by which astronauts could tackle the problem of circadian adaptation within the demanding timetable of a Space Shuttle mission. The strategies included both abrupt and gradual methods, and some approaches used artificial "very bright lights" to reset the physiologic circadian pacemaker. The strategies have since been operationally implemented on Space Shuttle flights, with good success. This is a report of the problems addressed by the workshop and its recommendations.

Results of a structured psychiatric interview to evaluate NASA astronaut candidates.

One hundred six astronaut applicants who had passed initial screening were evaluated for Axis I and Axis II DSM-III-R diagnoses using a structured psychiatric interview. Nine of 106 candidates (8.5%) met diagnostic criteria for six Axis I (including V-code), or Axis II disorders. The use of the NASA structured interview was effective in identifying past and present psychopathology in a group of highly motivated and healthy astronaut applicants. This was the first time that a structured interview had been used in such a setting for this purpose. The methodology described is applicable to any situation where the presence or history of psychopathology requires evaluation for job selection (e.g. pilot selection).

Psychiatric diagnoses in a group of astronaut applicants.

Between 1959 and 1987, the psychiatric evaluation of astronaut candidates evolved from a 30-h intensive examination evaluating applicants for psychopathology, and studying their performance under stress, to a 2-h clinical interview whose structure and contents were determined by the individual examiner. Evaluations done during these years applied both psychiatric (or, "select-out") criteria and psychological (or, "select-in") criteria. In an attempt to more rigorously define the psychiatric, "select-out" component, a standardized, semi-structured clinical interview was developed to identify the presence or history of psychiatric disorders listed in the Diagnostic and Statistical Manual of Mental Disorders, 3rd Ed. ("DSM-III"). A total of 117 astronaut applicants underwent this clinical interview as part of a comprehensive medical evaluation during a recent astronaut selection. Of the 117 applicants, 9 (7.7%) met DSM-III criteria for a variety of Axis I and Axis II diagnoses, including V-code diagnoses.

Effects of phenytoin on N100 augmenting/reducing and the late positive complex of the event-related potential: a topographic analysis.

The effects of 100 mg of phenytoin on the topographic distribution of augmenting/reducing (amplitude response/nonresponse to increases in stimulus intensity) of the visual N100 component of the event-related potential (ERP) were examined. In normal subjects, visual N100 augmenting is associated with impulsivity and attentional distraction. Effects of phenytoin on the topographic distributions of the P300 and slow-wave cognitive ERP components were also examined. Subjects counted the total number of light flashes presented at two highly discriminable but equiprobable intensities. Results indicated that phenytoin had a significant reducing effect on the intensity response of N100 at the vertex and anterior temporal electrode sites, and approached significance at the frontal pole. That is, at these loci N100 showed less of an increase in amplitude (or, in some subjects, more of a decrease) in going from baseline to drug than in going from baseline to placebo. Results also indicated that phenytoin significantly enhanced the amplitude of the frontal, negative portion of slow wave, but not the posterior, positive portion or the P300 component. These findings are consistent with behavioral evidence that phenytoin reduces impulsivity and improves concentration.