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Biomedical subjects

L J Phillips

Publications and source records attributed to L J Phillips.

At least 19 recordsLinked to original sources
PubMed1993

Replacement and care compliance in a planned replacement contact lens program.

Three-hundred and seven contact lens wearers in a planned replacement program were evaluated to determine compliance with scheduled replacement, yearly evaluation, and lens care. Patients studied were wearing soft lenses and replaced them every 6 months or less but were not using disposable lenses. Those involved were in this program for more than 24 months. The results show a 97.1 percent compliance with lens replacement and a 94.7 percent compliance with scheduled annual visits. The 32.4 percent lens care compliance rate for a single solution system was lower than expected.

Adolescent↗
PubMed1992

A comparison of human toxics exposure and environmental contamination by census division.

National Human Adipose Tissue Survey (NHATS) data and U.S. Environmental Protection Agency (U.S. EPA) STORET data were used to test for relationships between human exposure and environmental contamination according to census division. Regions were ranked according to the mean concentration of 43 toxic substances (pesticides, polychlorinated biphenyls, semi-volatiles, and volatiles) in human adipose tissue and environmental media (sediment, fish tissue, and groundwater). Correlation analyses between regional human and environmental ranks indicated that fish tissue data were good predictors of regional pesticide exposure, sediment data were good predictors of PCB exposure, and groundwater data were good predictors of exposure to semi-volatile compounds. None of the environmental data used were good predictors of exposure to volatile chemical compounds. Groundwater appeared to be a better predictor of overall regional toxics exposure than other types of environmental data.

Animals↗
PubMed1991

Regional variations in human toxics exposure in the USA: an analysis based on the National Human Adipose Tissue Survey.

Regional human exposure was evaluated by examining human tissue chemical concentrations. National Human Adipose Tissue Survey data for 54 toxic substances [pesticides, polychlorinated biphenyls (PCBs), semivolatiles, volatiles, and polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs)], were sorted by United States census divisions. Regional differences in human toxics exposure were found. Based on the data analyzed, it appears that individuals residing in the South Atlantic, East South Central, West South Central, and East North Central regions may be exposed to greater amounts of toxic substances than those of other regions of the country. Higher concentrations of organochlorine pesticides, PCBs, and PCDDs in older individuals indicate that these toxics bioaccumulate in human adipose tissue.

Adipose Tissue↗
PubMed1990

Evaluation of criteria for the acceptance of bioanalytical data.

Results from bioanalytical analyses for registration of a new drug entity are used to define its pharmacokinetics and bioavailability/bioequivalence. Whilst analytical data may be derived from the application of a validated method, it is essential to apply mathematical criteria to its acceptance, in order that the analyst can be assured that the assay is performing within defined limits and to its validated specification. Parameters evaluated for acceptability are the batch calibration curve, the minimum quantifiable concentration and the quality control (QC) sample acceptability. Specifically, six QC samples per analytical batch are used, two samples at each of three concentrations. The rationale for the definition of these criteria is evaluated together with a consideration of their applications and limitations. The relevance and use of Shewhart and Cusum plots to monitor assay performance is illustrated.

Biological Availability↗
PubMed1989

In vitro collagen fibril assembly: thermodynamic studies.

The in vitro fibril assembly of calf skin collagen was examined as a function of ionic strength and temperature. In a 0.03 M NaPi, pH 7.0, buffer, fibril assembly required a minimum critical concentration of collagen. At nearly physiological ionic strengths and temperatures, the critical concentration was less than 1 microgram/mL and required a very sensitive method for measurement. Raising the ionic strength of the buffer resulted first in higher and then lower critical concentrations. Raising the temperature led to lower critical concentrations. A van't Hoff plot of the fibril growth constant calculated from the critical concentration gave positive enthalpy changes and positive heat capacity changes which indicate that the fibril growth is driven by both hydrophobic and ionic inter-collagen interactions. Sedimentation equilibrium studies showed the collagen to be monomeric at subcritical concentrations. Differential scanning microcalorimetric studies showed only one very sharp heat absorption peak for the fibril assembly which coincided with the appearance of solution turbidity. Within experimental error, the enthalpy changes of the fibril assembly measured with the microcalorimeter were of the same magnitude as the van't Hoff enthalpy changes. These results are discussed in light of a cooperative nucleation-growth mechanism of collagen fibril assembly proposed earlier.

Animals↗
PubMed1988

The radiosensitivity of embryos of domestic chickens and black-headed gulls.

Eggs of domestic chickens and black-headed gulls were continuously exposed to gamma-rays during incubation, using dose rates ranging from 0.004 to 0.08 Gy h-1 for 20 days. Acute-dose experiments were also conducted, and eggs were irradiated on day 10 of incubation with doses of between 1.92 and 28.8 Gy. Hatchability and numbers reaching full-term developed were affected only after chronic doses of 9.6 Gy and acute doses of 4.8 Gy or higher. Maximum embryo mortality occurred around days 10-11 of incubation and just before hatching, in all experiments. An increase in foot and limb deformities was observed above acute and chronic doses of 9.6 Gy.

Animals↗
PubMed1983

Counting processes in deaf children's arithmetic.

Ten profoundly deaf children and 10 hearing controls matched for arithmetical achievement were given integer additions to classify as right or wrong. Hearing children perform this task by using covert counting strategies which have been assumed to be subvocal. In view of deaf children's poor spoken language abilities it was expected that the deaf group would make little or no use of such covert counting strategies and would rely more on alternative methods such as recalling learned number facts from long-term memory. The results failed to confirm this expectation and showed that classification times for the deaf were generally consistent with the same counting model as for the hearing. There was no difference between the groups in responses to correct sums involving ties or to incorrect sums, potential indicators of the use of associative retrieval. It is suggested that the covert counting processes of both deaf and hearing children in integer addition do not involve subvocalization. Alternative possibilities and general implications of this result for the education of the deaf are discussed.

Child↗
PubMed1983

Intraocular lenses: an update.

The use of intraocular lenses has been rapidly increasing in recent years. Improved designs and newer surgical techniques have reduced already low complication rates making implantation of an intraocular lens the procedure of choice for both patients and practitioners. Trends in lens design and a review of the most recent literature is offered for the practitioner.

Cataract Extraction↗
PubMed1980

Quality.

Explore the source record for details and available documents.

Delivery of Health Care↗
PubMed1979

Evaluation of the binocularity of 147 unilateral and bilateral pseudophakic patients.

Tests of binocular functions were performed on a group of 147 patients with unilaterally or bilaterally implanted intraocular lenses. The quality of the binocular vision achieved was significantly better than that of unilateral aphakic patients wearing contact lenses. Compared to the normal population, the stereoscopic threshold in the pseudophakic population was found to be slightly poorer. Visual acuity, anisometropia, lens fixation, and vertical deviation were analyzed in relation to stereopsis.

Adult↗
PubMed1979

Intraocular lenses and their follow-up in the optometric office.

A broad overview of intraocular lens implantation is presented for the optometrist. Included in this overview is a review of the most recent literature comparing complication rates for lens implants versus standard cataract surgery. A proportion of the paper addresses itself to the pre and post-operative optometric management of the pseudophakic patient. This paper is presented to give the optometrist a basic understanding of the expanding field of intraocular lens implantation as well as a reference list which will serve as a starting point for further review.

Aphakia↗
PubMed1978

Evaluation of 225 consecutive intraocular-lens implants.

A retrospective study of the first 225 intraocular lens implants (IOL) performed by a single surgeon was conducted for this report. In complication rate and visual acuity assessed 4.5 months postoperatively, these patients (pseudophakes) compared very closely with 2 populations of aphakic patients who had had phacoemulsification surgery without lens implantation by the same surgeon. The majority of pseudophakes were left with moderate to low refractive errors. Patient satisfaction was found to be high. It appears that implantation of iris and capsular fixated intraocular lenses is a comparatively safe and in many cases advantageous procedure.

Adult↗