Search PubMed⌕ Search

Biomedical subjects

W C White

Publications and source records attributed to W C White.

At least 19 recordsLinked to original sources
PubMed1995

Gadolinium-enhanced magnetic resonance imaging assessment of hydroxyapatite orbital implants.

PURPOSE: Successful prosthesis attachment depends on complete vascularization of porous coralline hydroxyapatite when it is used as an orbital implant. We retrospectively assessed the utility of gadolinium-enhanced magnetic resonance imaging to evaluate and characterize the temporal progression of this fibrovascular process, which has been histologically documented elsewhere. METHODS: Serial T1-weighted gadolinium-enhanced orbital magnetic resonance examinations were performed in five patients receiving hydroxyapatite orbital implants. Retrospective evaluation of the enhancement patterns was performed. Magnetic resonance imaging enhancement patterns guided timing of final drilling for prosthesis fixation. RESULTS: Serial gadolinium-enhanced T1-weighted sequences consistently demonstrated centrally advancing, peripheral enhancement centered on the drilled access channels. Progression over time varied, with the following two patterns demonstrated: (1) rapid peripheral enhancement, which led to diffuse enhancement (three patients); and (2) enhancement limited to the periphery, which failed to advance centrally. CONCLUSIONS: The temporal enhancement seen on magnetic resonance imaging is identical to the histologically proven fibrovascular ingrowth pattern and most likely reflects this process. Magnetic resonance imaging can identify progression of fibrovascular ingrowth into the hydroxyapatite orbital implants and guide surgical planning. It may also identify implants that fail to vascularize, thereby preventing the morbidity encountered by drilling into an avascular hydroxyapatite implant.

Adolescent↗
PubMed1982

Dog bites. A neglected problem in accident prevention.

Dog bites are a common but neglected pediatric problem. To clarify the epidemiology of dog bites and to learn if parents would welcome counseling aimed at preventing bites, 455 families (960 children) in a Denver pediatric practice were surveyed. One hundred ninety-four children (20.2%) had been bitten at least once, with the majority of bites occurring before the child was aged 5 years. Forty-three percent of the bites prompted a visit to a physician and 16.5% received sutures. German shepherds were responsible for 17% of the incidents, more than expected relative to their popularity as pets. The dogs usually were owned by a neighbor (40.2%) or the victim's family (31%). Approximately half of the bites were believed to be unprovoked. Seventy-seven percent of the parents believed that dog bite prevention warranted discussion with their physician. Dog bites are an important pediatric problem, and parents should be counseled accordingly during well-child visits.

Adolescent↗
PubMed1981

Methotrexate-resistant Chinese hamster ovary cells have amplified a 135-kilobase-pair region that includes the dihydrofolate reductase gene.

For the eventual purpose of isolating and studying a single animal cell replicon, we have developed a methotrexate-resistant Chinese hamster ovary cell line that has amplified an early-replicating DNA sequence approximately 500 times; this sequence includes the gene coding for dihydrofolate reductase (DHFR; tetrahydrofolate dehydrogenase; 5,6,7,8-tetrahydrofolate:NADP+ oxidoreductase, EC 1.5.1.3). DHFR composes 30% of the cytoplasmic protein in this cell line, and DHFR mRNA represents 25% of the message translatable in vitro. After digestion of genomic DNA from resistant cells with restriction enzymes, a unique set of highly repetitive restriction fragments can be visualized on agarose gels by ethidium bromide staining. These bands are not present in digests of parental DNA. We estimate the total length of the unit repeated sequence to be 135 +/- 15 kilobase pairs. Regardless of the restriction enzyme utilized, a subset of these repetitive fragments hybridizes to radioactive DHFR cDNA. The homogeneously staining regions on mitotic chromosomes in which these amplified sequences are located are shown to be early-replicating, as are the highly repeated restriction fragments themselves. These data suggest that an early replicon can be isolated from this region, and that this entire, normally unique, genomic segment can be cloned and mapped with respect to origins of DNA synthesis and promoters for transcription, as well as other genetic features of interest.

Animals↗
PubMed1976

Attributional change and the importance of baseline recording a case illustration.

This single case study illustrates how attention to baseline measures prevented premature conclusions regarding the impact of a conditioning procedure upon aggressive, acting-out behavior. Five disruptive behaviors were initially delineated so that frequency distributions could be obtained. During the course of this 15-day observational period, a significant reduction in the number of these aggressive responses was noted. The proposed conditioning procedure was therefore never required. Explanations as well as implications regarding the observed alteration in behavior were discussed.

Acting Out↗
PubMed1975

Validity of the Overcontrolled-Hostility (O-H) Scale: a brief report.

In order to further assess the validity of the MMPI O-H (overcontrolled hostility) Scale, high and low O-H youthful offenders were administered the Rosenzweig Picture-Frustration Study and their responses classified as extrapunitive, impunitive or intropunitive. Results indicated that high O-H subjects were significantly more impunitive than low O-H subjects and conversely, that low O-H subjects were more extrapunitive than high O-H subjects. Such findings are consistent with the O-H personality typology and lend further support to the construct validity of the Scale.

Adult↗