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Biomedical subjects

R W Murphy

Publications and source records attributed to R W Murphy.

11 recordsLinked to original sources
PubMed1997

Phylogeny of the side-blotched lizards (Phrynosomatidae:Uta) based on mtDNA sequences: support for midpeninsular seaway in Baja California.

We investigated the phylogenetic relationships of western North American Side-blotched lizards, genus Uta, using mitochondrial DNA partial gene sequences from cytochorme b and ATPase 6. Uta stejnegeri appeared basal in our tree followed by U. palmeri. Uta stansburiana from the islands of Angel de la Guarda, Mejia, and Raza formed the next clade, followed by U. antiqua and other populations of U. stansburiana. These relationships suggest that the populations on the Angel de la Guarda island block should be recognized as a distinct species. Remaining populations of U. stansburiana formed two clades, corresponding to the northern and southern Baja California peninsula. Uta stellata and U. squamata occurred within the northern and southern clades, respectively. The discontinuity requires a long-lasting isolation, the only reasonable explanation being a former midpeninsular seaway. Correlations between our cladogram and magnetic anomalies in the Gulf of California date formation of the seaway at 1 million years ago.

Animals↗
PubMed1993

A comparison of controlled negative pressure and aerosol quantitative respirator fit test systems by using human subjects.

A quantitative respirator fit test system based on controlled negative pressure was evaluated by comparison testing with a computerized aerosol fit test system. Experiments ranged from multiple sequential tests of a single subject wearing a respirator equipped with a series of fixed leaks to sequential fit tests of 125 U.S. Air Force personnel using both systems. Throughout each test phase, measured negative pressure fit factors were consistently more conservative and less variable than aerosol fit factors. Comparison of subject and fixed leak fit factors indicated significant loss of aerosol during subject fit tests. Negative pressure system results did not show any effect from subject-related losses.

Aerosols↗
PubMed1991

A comparison of controlled negative pressure and aerosol quantitative respirator fit test systems by using fixed leaks.

An automated version of a new method for quantitative respirator fit testing by controlled negative pressure was compared with a computerized aerosol fit test system. The controlled negative pressure technique eliminates many of the problems associated with aerosol and pressure decay fit test methods. A series of fixed leaks was used to compare the leak measurement capabilities of the controlled negative pressure system against a standard computerized aerosol fit test system. Negative pressure and aerosol fit factors determined for a series of fixed leaks through hypodermic needles were highly correlated with each other (r = 0.998) and with the cross-sectional areas of the leak needles (r greater than 0.995).

Equipment Design↗
PubMed1980

Use of nicotinamide adenine dinucleotide (NAD)-dependent glucose-6-phosphate dehydrogenase in enzyme staining procedures.

Substitution of nicotinamide adenine dinucleotide dependent glucose-6-phosphate dehydrogenase for the nicotinamide adenine dinucleotide phosphate dependent enzyme has produced identical results in a number of enzyme-linked electrophoretic staining procedures. This substitution significantly reduces the cost of staining for adenylate kinase, creatine kinase, glucosephosphate isomerase, mannosephosphate isomerase, phosphoglucomutase, and pyruvate kinase activity by utilizing NAD rather than the more expensive NADP.

Animals↗
PubMedDate not supplied

Nerve roots and spinal nerves in degenerative disk disease.

After 43 years of investigating the intervertebral disk, the long term results of the management of patients from the standpoint of pain are not significantly different than they were prior to the identification of the herniated disk nor do they seem to be significantly different than no treatment at all. This should at least suggest that the phenomena of low back pain is far more complex than can be accounted for on the basis of a simple mechanical-pressure theory of disk derangement. There is a significant volume of literature that would point to the neural tissues themselves as the most logical structures for future research that attempts to interfere with the natural history of this disease from the standpoint of pain. It seems most appropriate to attack lumbar disk disease from this standpoint because except in uncommon cases, the pathological process is benign and self limiting. It also seems logical that major advancements in the management of "diskogenic" back pain will depend upon an appreciation of the importance of controlling neural inflammation in the early phases of the disease rather than developing new techniques of managing irreversible neural lesions and their iatrogenetic or psychiatric sequelae.

Acute Disease↗
PubMedDate not supplied

The influence of backrest inclination and lumbar support on lumbar lordosis.

The influence of backrest inclination and lumbar support on the shape of the lumbar spine in sitting positions has been studied radiographically on 38 healthy subjects. Four angles of backrest inclination and four different sizes of lumbar support were studied. In addition, the lumbar support was placed at three different lumbar levels. When sitting down from a standing position, the pelvis rotates and the lumbar lordosis decreases. Increases in the backrest-seat angle had only minor effect on the lumbar lordosis. A lumbar support, on the other hand, had a significant influence: the lordosis increased with increasing support. The location of the lumbar support with respect to the level of the spine did not significantly influence the measured angles.

Adult↗
PubMedDate not supplied

Low back pain.

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Back Pain↗