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Biomedical subjects

M Lynn

Publications and source records attributed to M Lynn.

At least 19 recordsLinked to original sources
PubMed1992

Effects of cocaine and alcohol, alone and in combination, on human learning and performance.

The acute effects of cocaine hydrochloride (4 to 96 mg/70 kg) and alcohol (0 to 1.0 g/kg), administered alone and in combination, were assessed in two experiments with human volunteers responding under a multiple schedule of repeated acquisition and performance of response chains. Subjects were intermittent users of cocaine and regular drinkers who were not cocaine or alcohol dependent. Alcohol was mixed with orange juice and ingested in six drinks within 30 min; cocaine was administered intranasally 45 min after completion of drinking. In each component of the multiple schedule, subjects completed response sequences using three keys of a numeric keypad. In the acquisition component, a new sequence was learned each session. In the performance component, the response sequence always remained the same. Results were consistent in both experiments, despite variations in the order in which the drugs were tested alone and in combination. Alcohol administered alone increased overall percentage of errors and decreased rates of responding in the acquisition component, whereas responding in the performance component generally was unaffected. Cocaine administered alone decreased rates of responding but did not affect accuracy of responding in the acquisition component, and enhanced accuracy of responding without affecting rates of responding in the performance component. The combined doses of cocaine and alcohol attenuated the effects observed with alcohol and cocaine alone. These results suggest that, under the conditions investigated in this study, (a) alcohol produces greater behavioral disruption than cocaine or cocaine-alcohol combinations, (b) cocaine and alcohol each attenuate effects of the other, and (c) such attenuation is most pronounced for cocaine attenuating the disruptive effects of alcohol.

Adult↗
PubMed1990

Effects of intranasal cocaine on human learning, performance and physiology.

The behavioral and physiological effects of intranasally administered cocaine (placebo, 48, 96 mg/70 kg) were examined in eight recreational cocaine users under controlled laboratory conditions. The 48 and 96 mg doses of cocaine significantly improved subjects' performance on the Digit Symbol Substitution Test above levels observed either prior to drug administration or when placebo was administered. These effects were discernible for up to 120 min after cocaine administration. Cocaine had no statistically significant effects on learning and performance of ten-response sequences. The 48 and 96 mg doses increased heart rate and blood pressure for up to 180 min, and increased subject ratings of drug effects and decreased skin temperature for 60-90 min after drug administration. Cocaine produced no significant effects on the electrocardiogram. To our knowledge, this is the first experimental demonstration that acutely administered cocaine can improve behavioral performance in rested subjects. In addition, the duration of cardiac effects in this study was longer than previously reported with intranasal cocaine, perhaps due to the concurrent behavioral testing.

Administration, Intranasal↗
PubMed1989

Accuracy and reproducibility of KeraScanner analysis in PERK corneal topography. PERK Study Group.

The measurement of the corneal radius of curvature centrally and in the corneal periphery is exceedingly difficult because of variables in photography and data acquisition. We present a technique of Automated image scanning of corneal photographs which provides a more accurate and reproducible analysis of the paracentral corneal contour. We analyzed the sources of error of corneal topography measurement. CorneaScope photographs of calibration balls were generated by each Prospective Evaluation of Radial Keratotomy (PERK) Surgical Center. The 90% confidence intervals for individual ring-radial positions on the 8.00 and 10.00 mm balls were 7.91 to 8.09 mm and 9.89 to 10.11 mm respectively. Our isopter method of analysis for clinical comparison averages all eight radii of curvature for each CorneaScopef ring. This isopter technique reduces the corresponding 90% confidence intervals to 7.96 to 8.03 and 9.95 to 10.06 mm. The measurement variability of a 10 mm calibration ball decreased in the following order: calibration ball positioning, scanner personnel, photograph movement between scans, and nonrepositioned scanning. Photographs of calibration balls demonstrate +/- 4 microns of measurement resolution and patient corneal photographs may be evaluated to +/- 40 microns. This automated scanning system provides consistent data when digitizing keratographs.

Biometry↗
PubMed1988

Relationship of glare to uncorrected visual acuity and cycloplegic refraction 1 year after radial keratotomy in the prospective evaluation of radial keratotomy (PERK) study.

This study examines the relationship of subjective glare to refraction and visual acuity, respectively, 1 year after surgery in 435 patients who underwent radial keratotomy for nearsightedness in the Prospective Evaluation of Radial Keratotomy (PERK) study. Patients were asked if they experienced glare in bright light. Of the 425 responding, 200 patients responded "no" and 225 patients responded "yes." We found no statistically significant difference in the mean value of the cycloplegic refraction 1 year after surgery in these two patient groups. (Mean cycloplegic refraction: no = -.48, yes = -.52, p = .73). We also found no difference between these groups with respect to the percent of patients with uncorrected visual acuity of 20/40 or better 1 year after surgery (no = 79%, yes = 76%, p = .46).

Clinical Trials as Topic↗
PubMed1987

An endoscopic comparison of the effects of etodolac, indomethacin, ibuprofen, naproxen, and placebo on the gastrointestinal mucosa.

To assess the effects of various nonsteroidal antiinflammatory drugs on gastroduodenal mucosa, 72 normal men were administered either etodolac, indomethacin, ibuprofen, naproxen, or placebo for 7 days. Gastric and duodenal mucosa were scored before and after treatment by direct endoscopy and evaluation of photographs taken during endoscopy. Subjects treated with indomethacin, ibuprofen, and naproxen had significantly worse direct gastric scores, and those treated with indomethacin and naproxen also had significantly worse direct duodenal scores, when compared with pre-treatment and placebo scores. Subjects given either of 2 doses of etodolac had gastric and duodenal scores comparable to pretreatment and placebo scores. The direct gastric scores of the etodolac groups were significantly better than the scores of subjects receiving indomethacin, ibuprofen and naproxen. Similar results were obtained when endoscopy photographs were scored.

Acetates↗
PubMed1987

Laboratory test results as predictors of recurrent coronary artery stenosis following angioplasty.

A retrospective study has been conducted to examine the potential value of a battery of selected clinical laboratory tests as predictors of recurrent coronary artery stenosis following angioplasty. Data from 443 patients (including 325 men and 118 women) who had undergone coronary angioplasty were analyzed. Total men, total women, aspirin-treated men, and aspirin-treated women received separate statistical treatment. The only statistically significant difference in mean laboratory values between success (no recurrent stenosis) and recurrence groups was for serum cholesterol in aspirin-treated women, where the recurrence group showed a higher value than the success group. Multiple logistic regression showed a statistically significant association between elevated mean cholesterol and low mean hemoglobin concentration and recurrence in the female aspirin-treated group. Although only a small number of the laboratory test results fell outside normal laboratory reference ranges, we noted that for some tests, patients with extreme values predominantly developed recurrent stenosis while for certain other tests they were mainly successful. For example, seven of eight male diabetics with plasma glucose concentrations above 9.4 mmol/L (170 mg/dL) developed recurrence, while recurrent stenosis did not occur in any of six men with a bleeding time greater than twice normal. The results of these studies do not support the hypothesis that lipoprotein, coagulation, and platelet factors influence the development of recurrent stenosis in the majority of patients, although abnormalities in certain of these parameters may contribute to the process in specific cases.

Aged↗
PubMed1986

Reported satisfaction, fluctuation of vision, and glare among patients one year after surgery in the Prospective Evaluation of Radial Keratotomy (PERK) Study.

We studied satisfaction with the results of radial keratotomy one year after surgery on one eye as reported by 354 patients in the Prospective Evaluation of Radial Keratotomy (PERK) Study. We measured satisfaction using an index based on ten questions that were part of a longer psychometric questionnaire. Patients were generally satisfied with the results of radial keratotomy-48% were very satisfied, 42% were moderately satisfied, and 10% were dissatisfied. A lot of trouble with fluctuating vision was reported by 12% of patients before surgery and by 34% one year after surgery; 17% reported a lot of trouble with glare both before surgery and one year after surgery. The three major factors that influenced satisfaction were uncorrected visual acuity, residual refractive error, and subjective daily fluctuation in vision. A multiple regression equation that incorporated these three variables, glare, and patient sex was able to predict only 46% of the variance in patient satisfaction.

Adult↗
PubMed1986

Comparison of ultrasonic corneal thickness measurements before and during surgery in the prospective evaluation of Radial Keratotomy (PERK) Study.

Central corneal thickness, determined by an ultrasonic pachymeter, was studied in one eye each of 395 patients enrolled in the Prospective Evaluation of Radial Keratotomy (PERK) Study, to determine the changes in central corneal thickness between preoperative and intraoperative measurements. There was no statistical difference between the preoperative and the intraoperative measurement. However, 9.4% of the corneas were 0.03 to 0.08 mm thinner intraoperatively and 3.3% were 0.03 to 0.06 mm thicker intraoperatively, indicating that clinically meaningful changes in corneal thickness occurred between the preoperative and intraoperative measurements in some eyes. We conclude that the most reliable way to use ultrasonic pachymetry readings to set the length of the knife blade for radial keratotomy surgery is to measure the corneal thickness intraoperatively.

Cornea↗
PubMed1986

Diurnal change in refraction, corneal curvature, visual acuity, and intraocular pressure after radial keratotomy in the PERK Study.

Selected patients who complained of fluctuating visual acuity in the Prospective Evaluation of Radial Keratotomy (PERK) Study were examined before 8:00 a.m. and after 7:00 p.m. on the same day to determine diurnal change in uncorrected visual acuity, best corrected visual acuity, manifest refractive error, average central keratometric power, and intraocular pressure. Sixty-three operated eyes were examined at three months, while 46 operated and 40 unoperated contralateral eyes were examined at one year after radial keratotomy. One year after surgery, 42% of the operated eyes had an increase in minus power of the manifest refraction of 0.50 to 1.25 diopters, 26% of the eyes changed their uncorrected visual acuity by 2 to 4 Snellen lines, and 35% of the operated eyes showed central steepening of the cornea by 0.50 to 1.25 diopters. These changes in the operated eyes at one year were similar to the changes at three months. Minimal diurnal changes occurred in the unoperated eyes at one year. Only 11% of the unoperated eyes changed their manifest refraction by 0.50 to 1.00 diopters, none changed their uncorrected visual acuity by 2 to 4 Snellen lines, and only one of the unoperated eyes changed its central keratometric power by 0.50 diopters. This study documents that many patients who experience diurnal fluctuation of vision have steepening of the cornea and an increase in the minus power of their refraction during the day.

Biomechanical Phenomena↗
PubMed1985

Enhancement of immunogenic activity of ribosomal preparations from Haemophilus influenzae by various adjuvants.

Ribosomes from Haemophilus influenzae type b have been reported to have immunoprotective activity in animals that can be enhanced by adjuvants. In this report we evaluated the adjuvant activity of several compounds in conjunction with ribosomes from the b and c serotypes of H. influenzae. Alhydrogel, saponin, and DPT were found to significantly enhance the immunoprotective response in mice, equalling or exceeding the activity of Freund's incomplete adjuvant. All of these adjuvants also enhanced significantly the IgM response of mice to sheep red blood cells. Ribosomes were also found to enhance this response. Among the compounds failing to provide adjuvant activity for ribosomes were poly(A:U), muramyl dipeptide, mycobacterial extract, dimethylglycine, methylated bovine serum albumin, sodium diethylthiocarbamate, and cetyltrimethylammonium bromide.

Adjuvants, Immunologic↗
PubMed1985

Effects of pictures on the organization and recall of social information.

The role of visual stimuli in the organization and recall of social information was investigated in a study that presented photographs of stimulus persons along with verbal trait descriptors. Paired with four trait descriptors of each stimulus person, subjects saw either no picture, one trait-unrelated picture, four trait-unrelated pictures, or four trait-related pictures. These conditions permitted a test of several competing explanations for the previously obtained improvement in memory for semantic information when accompanied by pictorial information. Results indicated that pictures incremented recall of trait information in two distinct stages--once with the addition of pictorial information and again when the pictures became relevant to the traits. Clustering in free recall on the basis of person categories was unaffected by the experimental conditions. These findings were consistent with the hypothesis that pictures enhance person memory by fostering elaboration on stimulus information at encoding.

Adult↗
PubMed1984

Biochemical alterations in the mouse induced by Pseudomonas aeruginosa and its slime glycolipoprotein.

Mice, injected with either live cells of Pseudomonas aeruginosa, or its slime glycolipoprotein (GLP), developed similar lethal syndromes. Within 14 h, biochemical changes in the sera, such as increased urea, aspartate aminotransferase, alanine aminotransferase, and creatinine, as well as decreased glucose, albumin, total protein, uric acid, and alkaline phosphatase, indicated liver and renal dysfunction. These marked alterations were in contrast with the minimal histopathological changes that occurred in these organs. Either live cell or GLP challenge also induced haemolysis in vivo. Immunization with GLP protected mice against most biochemical changes when challenged with live cells but did not protect GLP-challenged mice against the biochemical alterations assayed in the sera.

Animals↗
PubMed1979

The superiority of combination chemotherapy over single agent chemotherapy in small cell lung carcinoma.

From June 1974 to October 1976, 288 patients with small cell undifferentiated lung carcinoma were entered into a randomized, controlled study comparing the two noncycle-active induction regimens of cyclophosphamide vs. the combination of cyclophosphamide, doxorubicin and imidazole carboximide (DTIC). Patients were stratified by extent of disease, previous radiotherapy and performance status. Responding patients and those who did not progress were then randomized to receive their initial regimen alone, or their initial regimen with added cycle-active therapy (vincristine, hydroxyurea and methotrexate). While only 4/34 (12%) evaluable patients treated with cyclophosphamide achieved a response (greater than 50% regression), a final total of 119/217 (57%) evaluable patients on the three drugs have responded (p = 0.005). The survival curve for all the combination-treated patients was significantly better than for those treated with cyclophosphamide alone (p = 0.012). There was no demonstrable statistical superiority in length of remission or survival for patients on the combination who received in addition cycle-active consolidation therapy. In the combination chemotherapy group, survival duration was longer for patients with limited disease than extensive disease (p = 0.035). There was a strong correlation between quality of remission produced by the combination and survival.

Adult↗