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Biomedical subjects

T Rich

Publications and source records attributed to T Rich.

45 records · Page 3Linked to original sources
PubMed1979

Micro-light guides: a new method for measuring tissue fluorescence and reflectance.

Three-way light guides containing one or more strands of 25-micron or 80-micron diameter optical fibers in each channel have been constructed and used to measure the NADH fluorescence and UV reflectance from mitochondrial suspensions, the perfused, hemoglobin-free rat liver, and the perfused beating interventricular septum of the rabbit. The optical changes measured with these so-called micro-light guides, which have channels containing one or several strands of optical fibers less than 100 micron, are comparable in magnitude with those measured using much larger conventional light guides. The effect of light scattering on the fluorescence channel has been determined and an empirical equation for correcting the fluorescence channel for light scattering has been obtained for mitochondrial suspensions. A mathematical equation characterizing the optical behavior of a two-way micro-light guide has been derived and has been shown to account satisfactorily for reflectance and fluorescence measurements of a mat surface in air.

Animals↗
PubMedDate not supplied

PQBP-1 (Np/PQ): a polyglutamine tract-binding and nuclear inclusion-forming protein.

Polyglutamine(Q) tract binding protein-1 (PQBP-1) was isolated on the basis of its interaction with polyglutamine tracts and localizes predominantly to the nucleus where it suppresses transcriptional activation by a neuron-specific transcription factor, Brn-2. Its C-terminal domain is highly conserved and binds to a component of the spliceosome. PQBP-1 possesses unique repetitive sequences that may fold as polar zippers. Interestingly, PQBP-1 also forms nuclear inclusion bodies, which are similar to those nucleated by the protein products of polyglutamine disease genes. Furthermore, because PQBP-1 is highly conserved in simple animal metazoans and plants (Caenorhabditis elegans and Arabidopsis), it may perform a basic function in cells. By the same token, disruption of the basic function could be critical to the disease process. Collectively, PQBP-1 might be a candidate molecule involved in the pathology of polyglutamine diseases. In this review, we discuss the structure and function of the PQBP-1 protein, the relevance of its aggregation and possible roles in normal and disease processes.

Animals↗
PubMedDate not supplied

A validation and comparison study of two metabolic monitors.

Two portable metabolic cart systems of indirect calorimetry (Deltatrac Metabolic Monitor, 2900 MMC System) were validated. CO2 and N2 were delivered at precise rates into a constructed lung model to simulate CO2 production (VCO2) and O2 consumption (VO2). VCO2 (200-400 ml/min) and VO2 (250-750 ml/min) were measured at varying combinations of minute ventilation (VE) (6, 10, 20 liter/min) and FiO2 (0.21, 0.30, 0.60, 0.80). VCO2 was measured with overall errors of 1.5% and 2.4% for the Deltatrac and 2900 monitors, respectively. VO2 was measured with overall errors of 1.9% and 3.2% by the Deltatrac and 2900 monitors, respectively. Both monitors performed equally well for measurement of VO2 at FiO2 up to 0.6, but the Deltatrac had less error for measurements of VO2 at FiO2 of 0.8.

Calorimetry↗
PubMedDate not supplied

Revision of diagnostic logic using a clinical database.

Statistical pattern-recognition techniques have been frequently applied to the problem of medical diagnosis. Sequential Bayesian approaches are appealing because of the possibility of generating the underlying sensitivities, specificities, and prevalence statistics from the estimates of medical experts. The accuracy of these estimates and the consequences of inaccuracies carry implications for the future development of this type of system. In an effort to explore these subjects, the authors used statistics derived from a clinical database to revise the diagnostic logic in a Bayesian system for generating a differential diagnostic list. Substantial changes in estimated a priori probabilities, sensitivities, and specificities were made to correct for significant under- and overestimations of these values by a group of medical experts. The system based on the derived values appears to perform better than the original system. It is concluded that the statistics used in a Bayesian diagnostic system should be derived from a database representative of the patient population for which the system is designed.

Bayes Theorem↗