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Biomedical subjects

L W Clark

Publications and source records attributed to L W Clark.

8 recordsLinked to original sources
PubMed1983

Nature of spelling errors in transcortical sensory aphasia: a case study.

The nature and extent of spelling errors in a patient with transcortical sensory aphasia were investigated. The two experimental conditions required the patient to spell monosyllabic and polysyllabic words both verbally and in written form. Analysis of the spelling errors revealed partially preserved knowledge of the visual image of a word as a whole, as well as preserved knowledge of temporal order. Our patient's error patterns in both conditions were more similar than dissimilar. These findings in conjunction with results reported in the literature indicate that patients exhibiting different aphasia syndromes use separate spelling strategies.

Aged↗
PubMed1982

Plasma phenylalanine: tyrosine ratios during high-dose methotrexate-citrovorum "rescue".

We have measured phenylalanine and tyrosine in the plasma of patients with osteogenic sarcoma undergoing chemotherapy with high-dose methotrexate (HDMTX) citrovorum factor rescue (CFR). During 14 treatments in six different patients, the phenylalanine to tyrosine ratio (PHE/TYR) at 21 to 38 hours was elevated over pretreatment levels. The observed increase in plasma phenylalanine is attributed to inhibition by MTX of the phenylalanine hydroxylase system of the liver, which is not folate-dependent and thus is not corrected by administration of CV. A post-infusion increase in PHE/TYR of 571% after 22 hours in one patient and of 410% after 30 hours in another were associated with marked MTX toxicity. The greatest increase in PHE/TYR seen in a patient who did not experience toxicity was was 249% in 21 hours. Thus, in this group of patients, there appears to be a correlation between evidence of clinical MTX toxicity and the magnitude of the percentage increase in PHE/TYR in the plasma, which indicates inhibition of a liver enzyme and thus reflects the intracellular concentration of MTX.

Adolescent↗
PubMed1975

The significance of isolating low numbers of mycobacterium tuberculosis in culture of sputum specimens.

Because fewer than five Mycobacterium tuberculosis colonies were isolated from single sputum specimens from several patients with little clinical evidence of pulmonary tuberculosis, we reviewed all of our low colony isolates (LCIs) from an 18-month period. Thirty-one patients had 35 LCIs and were separated easily into groups that either appeared to have tuberculosis by clinical criteria or appeared to be uninfected. Patients in the "tuberculosis likely" group reasons such as concurrent antituberculosis therapy or an interstitial location of their pulmonary lesion to account for their LCIs. In contrast, patients in the "tuberculosis unlikely" group were all culture-negative when reevaluated two to four months after their first culture, and they had no evidence of tuberculosis on chest x-ray film despite having received no antituberculosis therapy. Half had negative tuberculin reactions, without generalized anergy. Epidemiologic study showed that most had been cultured the same day as patients with smear-positive tuberculosis, and the possibility of cross-contamination was investigated.

Humans↗