Search PubMed⌕ Search

Biomedical subjects

D B Johnson

Publications and source records attributed to D B Johnson.

88 records · Page 5Linked to original sources
PubMed1971

Statistical approach to planning an integrated haemodialysis-transplantation programme.

A mathematical model has been constructed to assist in planning the future requirements of a combined haemodialysis and transplantation centre. It has been used to predict the number of patients in the dialysis unit, the general wards, and at home on dialysis, as well as providing further information on transplantation rates and overall costs. The model can be adapted for units with different facilities from our own.It can be primed with data from an individual unit or with pooled data from the whole country. The purpose of this paper is to demonstrate the methodology of a particular statistical approach.

Economics, Medical↗
PubMed1966

Observations on the biosynthesis of thiamine in yeast.

1. Methods are described for the isolation of radioactively pure thiamine from yeast and its degradation on a small scale to its cyclic components. 2. A degradation of the pyrimidine ring and a thin-layer method for the separation of thiamine, its derivatives and pyrimidine and thiazole residues are described. 3. [(14)C]Formate is more effectively incorporated into the pyrimidine residue than into the thiazole residue, whereas the reverse is true with l-[Me-(14)C]methionine. 4. Experiments with [Me-(14)C,(35)S]methionine demonstrate that methionine provides an intact unit for the biosynthesis of the thiazole ring. 5. [6-(14)C]Orotic acid is insignificantly incorporated into the pyrimidine residue of thiamine. 6. Experiments with [1-(14)C]- and [2-(14)C]-acetate indicate that it is incorporated as a unit into the thiazole residue, but that only C-2 is incorporated into the pyrimidine residue. 7. l-[U-(14)C]Alanine is also effectively incorporated into the thiazole residue. 8. These results are discussed in relation to possible pathways of biosynthesis of the two ring components of the thiamine molecule.

Acetates↗
PubMedDate not supplied

Hyperad: augmenting and visualizing free text radiology reports.

Hyperad is an automated computer system designed to extract key concepts from thoracic radiology reports and give physicians access to a large database containing the reports and key concepts. The concepts are extracted from textual documents with natural language processing techniques, then stored with the original documents in the database, which can be queried in terms of findings or associated attributes from an intuitive and easily accessible interface. The extracted concepts are represented both textually in a coded hypertext format and graphically on a coronal cross-sectional anatomy atlas, an idealized graphical model of human anatomy. To facilitate implementation, the communication protocols and standards of the World Wide Web (Web) were adopted. The reports and associated forms are encoded in standard hypertext markup language, which makes it possible to use hypermedia links to navigate the Hyperad database with any graphical Web browser. In the future, Hyperad may prove useful for other applications.

Computer Systems↗
PubMedDate not supplied

Teleradiology as a foundation for an enterprise-wide health care delivery system.

An effective, integrated telemedicine system has been developed that allows (a) teleconsultation between local primary health care providers (primary care physicians and general radiologists) and remote imaging subspecialists and (b) active patient participation related to his or her medical condition and patient education. The initial stage of system development was a traditional teleradiology consultation service between general radiologists and specialists; this established system was expanded to include primary care physicians and patients. The system was developed by using a well-defined process model, resulting in three integrated modules: a patient module, a primary health care provider module, and a specialist module. A middle agent layer enables tailoring and customization of the modules for each specific user type. Implementation by using Java and the Common Object Request Broker Architecture standard facilitates platform independence and interoperability. The system supports (a) teleconsultation between a local primary health care provider and an imaging subspecialist regardless of geographic location and (b) patient education and online scheduling. The developed system can potentially form a foundation for an enterprise-wide health care delivery system. In such a system, the role of radiologist specialists is enhanced from that of a diagnostician to the management of a patient's process of care.

Appointments and Schedules↗
PubMedDate not supplied

Comparative metabolism of four allylic barbiturates and hexobarbital by the rat and guinea pig.

A method for the extraction and identification of urinary metabolites of allylic barbiturates by gas chromatography and mass spectrometry is described. The metabolites from rat and guinea pig urine were extracted and separated into two fractions (an acidic and a nonacidic fraction) by chromatography on DEAE-Sephadex before converted into suitable derivatives for gas phase analysis. N,N'-dimethyl derivatives were used except in cases where metabolic N-demethylation was possible, in which case N-ethylation yielded more information. Hydroxyl, keto, and epoxy groups were converted into trimethylsilyl (TMS), alkyloxime, and chloro-TMS derivatives, respectively. This procedure was used to identify metabolites present in urine at concentrations as low as 0.1 microgram/ml. The allyl sidechains of secobarbital, alphenal, allobarbital, and aprobarbital were metabolized to epoxides, diols, and, in the case of secobarbital, to a ketol. Other sidechains were usually hydroxylated. Secobarbital was metabolized to compounds containing hydroxyl groups in both chains. Hexobarbital was metabolized by allylic hydroxylation, and no evidence of the epoxide-diol pathway was observed. The significance of the detection of epoxides of the four allylic barbiturates is discussed.

Animals↗