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Biomedical subjects

W Shockley

Publications and source records attributed to W Shockley.

8 recordsLinked to original sources
PubMed1996

Proton MR spectroscopy of squamous cell carcinoma of the upper aerodigestive tract: in vitro characteristics.

PURPOSE: To determine the ability of in vitro high-field-strength proton MR spectroscopy to differentiate squamous cell carcinoma of the upper aerodigestive tract from uninvolved muscle. METHODS: Surgical specimens of squamous cell carcinoma arising from the upper aerodigestive tract (n = 18) and from muscle (n = 13) were examined in vitro using high-field (11 T) proton MR spectroscopy. The peak heights of choline and creatine were measured for tumor and muscle at echo times of 136 and 272. The choline/creatine (Cho/Cr) ratio was compared between tumor and normal tissue for each echo time. Student's t test was used to determine whether a significant difference existed between proton MR spectroscopic measurements of the Cho/Cr ratio for tumor and muscle. RESULTS: The mean Cho/Cr ratio was consistently higher in tumor than in muscle at all echo times; however, statistically significant differences between tumor and muscle were identified only at longer echo times (136 and 272). CONCLUSION: The Cho/Cr peak height ratio can be used to differentiate tumor from muscle in vitro (at 11 T).

Carcinoma, Squamous Cell↗
PubMed1995

Nasal implants.

In summary, autogenous tissue remains the authors' preferred method of augmenting the nasal dorsum. Some authors have tried Supramid mesh, which tends to resorb. Mersilene seems to resist resorption and has been used with notable success. Silicone has had variable success but, because of bad publicity and the possibility of autoimmune disease, has fallen out of favor. Medpore never enjoyed widespread use over the dorsum of the nose, because of its rigidity. Gore-Tex seems to be gaining in popularity; animal studies have demonstrated its biocompatibility to be superior to that of other implants. Although the data remain preliminary at this point, they are as good as for any other implant material.

Biocompatible Materials↗
PubMed1995

Nasopharyngeal nonossifying variant of ossifying fibromyxoid tumor: CT and MR findings.

The CT and MR findings of a nasopharyngeal nonossifying variant of an ossifying fibromyxoid tumor are presented. The findings are radiographically indistinguishable from more common malignant neoplasms encountered in this region. The tumor was isointense with muscle on T1-weighted images. On proton density- and T2-weighted images, the mass was mostly isointense with gray matter but contained some areas of lower intensity that might reflect the fibrous tissue component. The tumor eroded through the floor of the middle cranial fossa.

Adult↗
PubMed1989

Perichondrial cutaneous graft. An alternative in composite skin grafting.

The perichondrial cutaneous graft (PCCG) is a composite skin graft that is an alternative to the full-thickness skin graft (FTSG). The PCCG is harvested from the ear and contains epidermis, dermis, scant subcutaneous tissue, and the perichondrial layer. This experiment examined the differences in contraction properties of PCCGs and FTSGs. Twenty FTSGs and 20 PCCGs were harvested from the ears and grafted onto the backs of seven New Zealand white rabbits. The results confirmed that the PCCG provides superior coverage to the FTSGs with regard to thickness, contraction properties, and hair retention. This graft has potential in reconstructive head and neck surgery. When skin grafting is appropriate, the PCCG may provide superior results.

Animals↗
PubMed1988

Adjuvant postoperative external beam radiotherapy in head and neck cancer.

The optimum postoperative dose for local or regional disease control was retrospectively assessed in 70 patients with head and neck cancer given adjuvant external beam radiotherapy. Actuarial 2-year survival rates with no evidence of disease (NED) according to stage were 75%, 59%, and 72% for stages II, III, and IV, respectively. Primary tumor/regional failure and distant metastasis adversely affected prognosis. Patients had an actuarial 2-year NED of 80% when the dose to the primary tumor/upper neck was greater than or equal to 60 Gy but was 53% when the dose was less than 60 Gy. Two-year NED was 85% in those patients given greater than 50 Gy to the lower neck and 62% when less than or equal to 50 Gy was used. Based on these results, a total dose of at least 60 Gy to the primary tumor bed and upper neck and greater than 50 Gy to the lower neck whenever adjuvant postoperative irradiation is administered for subclinical disease is recommended.

Adolescent↗
PubMed1973

Deviations from Hardy-Weinberg frequencies caused by assortative mating in hybrid populations.

The conventional formulas for genotype frequencies in a hybrid population H produced by interbreeding from ancestral populations P(1) and P(2) involve only one hybrid parameter M, equal to the fraction of alleles derived from P(2). For the one-parameter model to be accurate, all individuals of H must have probabilities for alleles determined by one and the same M. When H contains subpopulations that have different values of M, the correct genotype frequencies can be predicted by use of two parameters: (i) M(H), the average of M for all individuals of H and (ii) eta(H), defined like the eta devised by C. A. B. Smith for testing the Hardy-Weinberg Law and computed with a formula like G. R. Price's eta, which involves assortative mating covariance-in this case for the M values of the parents of H. If parents of H have equal average M values for males and females, and mate at random, eta(H) vanishes. For perfect assortative mating, eta(H) is the variance of M for H. As for Smith's eta, eta(H) provides a test of fit of prediction to observed that is sensitive to signs of deviations. Using eta(H) with T. E. Reed's data for Gm in Oakland, California Negroes, his one-parameter fit ("good" by his chi-square test) is significantly rejected (P = 0.04). A simultaneous good fit of Reed's Gm data and his Duffy data results (chi-square, 1 df = 0.88, P > 0.30) from the use of previously published values of 0.23 and 0.047 for M(H) and eta(H). It is concluded that Reed's conclusion that these values were in error is itself in error, as is also his view that differences between M values from different genes and deviations from frequencies expected within genes are not likely to give significant information about variance of M.

Alleles↗
PubMedDate not supplied

MR in squamous cell carcinoma of the lacrimal sac.

A case of squamous cell carcinoma arising from the right lacrimal sac is presented. MR T2-weighted images showed a mass of low signal intensity in the right medial canthus extending into the nasolacrimal duct. This led us to postulate a high-grade malignant neoplasm arising in the lacrimal sac.

Biopsy↗