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Biomedical subjects

G McCormack

Publications and source records attributed to G McCormack.

24 records · Page 2Linked to original sources
PubMed1983

Dynamics of cover test eye movements.

The dynamics of unilateral cover test eye movements, never before systematically investigated with an objective recording system, are shown to be more complex than textbook accounts of them. We administered the cover test to nine heterophoric subjects by means of electromechanical occluders. Eye movements were recorded using the infrared photoelectric technique. Saccadic and vergence movements of the fixating eye were observed in almost all records when the occluded eye was uncovered. These movements were found in esophores and exophores and in both large and small phoria cases. Such movements were previously described in other asymmetric vergence tasks and appear to obey Hering's law of equal innervation. Uncovering the dominant eye, in cases of clear dominancy, resulted in shorter latency and larger amplitude saccades than did uncovering the nondominant eye. These large saccades were frequently of unequal amplitude in each eye. Trained subjects appear to use dynamic overshoots to increase this saccadic inequality and thereby attain vergence during saccades. Movements after the application of a cover to one eye, while grossly similar to textbook descriptions of them, are found to contain small vergence drifts and refixation (correcting) saccades in the nonoccluded eye.

Adult↗
PubMed1983

Randomized phase II studies in advanced colorectal carcinoma: a North Central Cancer Treatment Group study.

5-FU, semustine (MeCCNU), triazinate (TZT), and razoxane (ICRF-159) have each shown activity against advanced colorectal cancer in studies by at least two investigative groups. Objective response rates, however, have been low, without evidence of increased patient survival. The hope of this study was that enhanced activity might result from giving these agents in two-drug combinations. There were 167 eligible and evaluable patients randomized among the programs: 5-FU at a dose of 500 mg/m2/day by iv push X 5 (F); 5-FU at a dose of 400 mg/m2/day iv X 5 plus TZT at a dose of 175 mg/m2/day iv X 3 (FT); 5-FU at a dose of 400 mg/m2/day plus ICRF-159 at a dose of 600 mg/m2/day orally X 3 (FI); MeCCNU at a dose of 150 mg/m2/day orally plus TZT at a dose of 200 mg/m2/day iv X 3 (MT); MeCCNU at a dose of 150 mg/m2 orally plus ICRF-159 at a dose of 500 mg/m2/day orally X 3 (MI); and ICRF-159 at a dose of 425 mg/m2/day orally X 3 plus TZT at a dose of 125 mg/m2/day iv X 3 (IT). Patients with limiting conditions (serum creatinine greater than 1.5 mg/dl or elevated bilirubin) were randomized among programs F, FI, and MI. Objective response rates by treatment arm were: F--13% (four of 31 patients); FT--13% (four of 31); FI--15% (four of 27); MT--11% (three of 28); MI--13% (four of 32); and IT--6% (one of 17). Response rates of combination arms were not significantly larger than those of 5-FU alone. With regard to survival, patients initially treated with 5-FU alone had the most favorable experience (median, 10.8 mos). Multivariate analysis showed the following factors to have a significant and independent influence on survival: Eastern Cooperative Oncology Group performance score, grade, site of indicator lesion, and the presence of 5-FU in the treatment regimen. Toxic effects most frequently seen were nausea, vomiting, thrombocytopenia, leukopenia, diarrhea, stomatitis, alopecia, and dermatitis. The incidence and severity of toxicity were roughly comparable among the six treatment arms.

Adult↗
PubMed1982

Measurement of interpupillary distance with chromostereopsis.

Chromostereopsis is a perceived depth difference between coplanar objects of different color and can be used for highly accurate measurement of interocular separation (PD). A survey of PD measurement with chromostereopsis and with the PD rule on 83 subjects shows that these methods on average result in the same PD, indicating that chromostereopsis is a valid technique for PD measurement. Repeated PD measures by these 83 individuals on the authors, using the PD rule and chromostereopsis, shows that the chromostereopsis result is far more repeatable than the PD rule. Suggestions are made for the use of the chromostereopsis technique in optometric practice.

Biometry↗