A new design concept for an audio dosimeter

A design concept for a new audio dosimeter is presented which can be used to evaluate employee exposure to both continuous and impulsive noise more accurately. Unlike existing dosimeters, the instrument is capable of eliminating the influence of impulsive sounds upon the employee exposure or "dose." The concept relies upon an interpretation of the intent of existing and proposed U.S. Department of Labor regulations with regard to the evaluation of continuous and impulsive sounds. This paper presents the rationale for the design concept, the block diagram of the microprocessor-based instrument, and a summary of its intended operation.

Major tendon repairs with dacron vascular graft suture

Achilles and patellar tendon tears in nine patients were repaired with 5 mm Dacron vascular grafts. There have been no failures with this method of fixation. In the patients we studied this method permitted earlier mobilization of joints.

Satellite DNA in large marker chromosomes of methotrexate-resistant mouse cells

The additional segments of five large marker chromosomes of methotrexate-resistant mouse melanoma PG19T3 cells are shown to consist of C-banding material. In situ hybridization indicates that these additional segments also contain a high proportion of sequences that will cross hybridize with mouse satellite DNA. Analytical density gradient centrifugation suggests that up to 60% of the DNA in the additional segments may be in the form of satellite DNA. Incorporation of bromodeoxyuridine for one complete S phase and staining with the Hoechst 33258 fluorescence plus Giemsa technique reveals complex asymmetries within the additional segments. These asymmetries are interpreted as showing a large repeating unit, which is likely to be involved in the amplification of the dihydrofolate reductase gene.

Errors in a computerized medical records system (CLINICS)

The accuracy of computer-held medical information can be of critical importance in patient care, therefore it is important not only to know the error rate in the stored data but also to know the effectiveness of error checking and correction programs. This paper reports on the errors which were detected by checking the consistency between stored data and incoming data (context checks), in Southampton University Primary Medical Care computer system (CLINICS). The majority of detected errors were traced either to the registration of new patients or to the doctors failing to pay adequate attention to detail in their record keeping (or to their legibility). 7% of incoming data had errors detected by the context checking program and subsequently corrected; we calculate that the stored data contains less than 1% in error.

The development of resistance to methotrexate in a mouse melanoma cell line. I. Characterisation of the dihydrofolate reductases and chromosomes in sensitive and resistant cells

PG19T3 mouse melanoma cells were selected for resistance to methotrexate. Nine sub-lines that are resistant to concentrations of methotrexate ranging from 1.27 x 10(-7) M, to 1 x 10(-4) M methotrexate were selected and characterised in terms of their content of dihydrofolate reductase activity and their chromosomes. The intracellular level of dihydrofolate reductase activity increases with increasing resistance such that at the highest level of resistance PG19T3:MTXR10(-4)M cells contain approximately 1,000 fold more enzyme activity than the parental PG19T3 cells. It is shown that the enhanced activity is due to an increase in the amount of the enzyme rather than any structural change to the enzyme in resistant cells. Comparisons of pH activity profiles, profiles under different activating conditions and titrations with methotrexate suggest that the sensitive and resistant cells contain identical dihydrofolate reductases. Analysis of the chromosomes of resistant cells shows the presence of up to 5 large marker chromosomes which contain homogeneously staining regions after G-banding. These same regions stain intensely after C-banding and fluoresce brightly after staining with Hoechst 33258. The size of homogeneously staining regions increases throughout the process of selection. For one marker chromosome this increase may have been mediated via a ring chromosome.