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Biomedical subjects

R Holmes

Publications and source records attributed to R Holmes.

170 records · Page 10Linked to original sources
PubMedDate not supplied

Optical fibre-based goniometer for sensing patient position and movement within a magnetic resonance scanner using chromatic modulation.

An optical fibre-based goniometer is described. This instrument was designed to measure the angular position of patients' limbs within the core of a magnetic resonance body scanner, via a 40 m remote fibre-optic link. The sensor exploits the advantages of optical fibre-based sensing, which include immunity to electromagnetic interference, intrinsic safety and chemical immunity. The detection electronics and signal processing are based on the principles of chromatic modulation, an inexpensive, intensity-independent technique in which a change in the spectral power distribution is measured over a broad bandwidth, by photodetectors with differing spectral responses. The optical fibre goniometer has an angular range of 90 degrees, with an average resolution of 2'. The long-term accuracy is within +/- 1 degree, the specified accuracy for the physiological application.

Artifacts↗
PubMedDate not supplied

Congenital choanal atresia -- a technique for surgical correction.

A technique for transnasal correction of unilateral and bilateral congenital atresia in both infants and older children has been used repeadedly with no difficulty encountered in creating an adequate passage in patients with either unilateral or bilateral atresia. In no instances was there any deviation from the intended path of the boring tool causing injury to the palatine vessels, roof of the nasopharynx, or posterior pharyngeal wall.

Airway Obstruction↗
PubMedDate not supplied

Clinical pharmacology of polyethylene glycol-L-asparaginase.

Polyethylene glycol (PEG)-L-asparaginase, at doses ranging from 500 to 8000 units/m2, was infused iv over 60 min in 31 patients of whom 27 were evaluable pharmacokinetically. The plasma disappearance of PEG-L-asparaginase is described by a monophasic curve with a mean half-life of 357 +/- 243 hr which is much longer than that of the unconjugated enzyme (half-life of approximately 20 hr). The rate of total clearance (128 +/- 74 ml/m2 X day) is much slower than that of L-asparaginase (2196 +/- 1098 ml/m2 X day). The volume of distribution is 2093 +/- 643 ml/m2, which is similar to that of L-asparaginase, indicating that PEG-L-asparaginase is mainly localized in the plasma. No enzyme could be measured in urine samples taken from nine patients for a period of up to 4 days. Additionally, no enzyme was measurable in one patient's pleural fluid obtained at the end of infusion and 6 days after infusion of a 1000-unit/m2 dose; the corresponding concentrations in plasma were 0.64 and 0.62 units/ml, respectively. In general, the plasma enzyme concentrations at the end of the 1-hr infusion and at 14 days after drug administration were proportional to the dose given. However, in two patients, a sudden disappearance of enzyme levels occurred which preceded anaphylactic reactions during subsequent treatment. A third patient developed severe bronchospasm 30 min after the first dose, but his enzyme levels were within the normal range.

Adult↗
PubMedDate not supplied

Relapsing pseudomembranous colitis.

Pseudomembranous colitis secondary to C. difficile and its toxin(s) is a well-recognized disease in children and usually responds to treatment with oral vancomycin. There are well-documented reports of relapse in adults after initial successful treatment with vancomycin. This report documents relapse in a child who developed diarrhea following treatment of pseudomembranous colitis. Stool cultures were negative for C. difficile at the end of the initial course of treatment, but the organism was isolated from the stool when the diarrhea recurred. The symptoms improved following a second course of treatment with vancomycin and have not recurred during 8 months of follow-up monitoring.

Child, Preschool↗
PubMedDate not supplied

Effects of synovial fluid on fibroblasts in tissue culture.

The ability of the torn anterior cruciate ligament of the knee to heal is unpredictable, despite early surgical repair. A popular explanation has been that synovial fluid inhibits ligament healing. Other variables of ligament healing could reside with the fibroblasts, themselves, from different ligaments. With the use of tissue culture techniques, populations of fibroblasts were cultured from human anterior cruciate ligaments, deep and superficial medial collateral ligaments of the knee. Growth of fibroblasts from the anterior cruciate ligament was always diminished when exposed to synovial fluid and, on the average, plating efficiency was reduced by 46% when the culture medium contained synovial fluid. Growth rates demonstrated that fibroblasts from the superficial medial collateral ligament grew an average of 35% more than the others. Information gained from this study provides some data to explain the clinical frustration of the torn anterior cruciate ligament. The combination of synovial fluid inhibition of cell proliferation and the variable growth rates of fibroblasts, may explain the unsatisfactory healing of cruciate ligaments.

Cell Count↗
PubMedDate not supplied

Human ocular aldehyde dehydrogenase isozymes: distribution and properties as major soluble proteins in cornea and lens.

Human aldehyde dehydrogenase isozymes (ALDHs; EC 1.2.1.3) exhibit very high levels of activity in anterior eye tissues. Human corneal ALDH1 and ALDH3 isozymes are present as major soluble proteins (3% and 5%, respectively, of corneal soluble protein) and may play major roles in protecting the cornea against ultraviolet radiation (UVR)-induced tissue damage, as well as contributing directly to ultraviolet B (UV-B) photoreception. The human lens exhibits high levels of ALDH1 activity (1-2% of lens-soluble protein) and lower levels of ALDH3 activity. Kinetic analyses support a role for these enzymes in the metabolism of peroxidic aldehydes, which have been reported in ocular tissues.

Aldehyde Dehydrogenase↗