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Biomedical subjects

D C Lewis

Publications and source records attributed to D C Lewis.

At least 73 records · Page 4Linked to original sources

An assessment of the complications of the Brantley Scott artificial sphincter.

A Brantley Scott artificial sphincter has been inserted into 95 patients since 1981; more than half of the patients had lower urinary tract neuropathy and most of the others post-TUR incontinence. The main problem with the device has been cuff failure (12), which should be resolved by the new "dipped" cuffs. The major surgical complication has been erosion (10), usually associated with infection. Twenty-four patients had variable degrees of incontinence but the artificial sphincter remains the cornerstone of continence control when other methods have failed or are inappropriate.

Female↗

The diagnosis and prevalence of subclinical hepatic encephalopathy in apparently healthy, ambulant, non-shunted patients with cirrhosis.

Thirty-seven patients, all with histologic evidence of cirrhosis and with a normal neurological examination and normal mental status were evaluated by psychometric testing for subclinical hepatic encephalopathy. They were all regarded as having well compensated cirrhosis, not requiring any treatment or dietary restrictions and they were working, and many of them driving. A group of 19 patients with a history of alcoholism, or medical disorders, but without clinical or biochemical evidence of cirrhosis, served as controls. They were matched by age, sex, education, and alcohol consumption. Investigations performed were an EEG, fasting arterial ammonia, liver biochemical tests and a series of verbal and performance psychometric tests. The EEG was abnormal in 3 (8.3%) of patients, the ammonia elevated in 17 (45.9%) of patients and 26 patients (70.3%) failed 2 or more psychometric tests, as compared to 2 (10.5%) of the control group. It is concluded that 2 out of 3 patients with stable, well compensated cirrhosis were suffering from subclinical hepatic encephalopathy and that impairment of performance rather than verbal skills occurred. The digital symbol test, trail test (number connection test) and block design tests readily identified the patients with subclinical hepatic encephalopathy. The implication of these observations in patients with cirrhosis, especially those working in mechanical or skilled occupations, needs consideration.

Ammonia↗

Eye movements and the enhancement of edges.

A mathematical examination of retinal photochemistry leads to a hypothesis for Mach band phenomena based on eye movements. This retinal model suggests why minimally distinct borders fade under eye fixation and agrees qualitatively with subjective measures of border contrast as a function of overall field luminance.

Eye Movements↗

Phenotype of adult familial dyslexia: reading of visually transformed texts and nonsense passages.

Oral reading is less disrupted by mirror-image and upside-down text transformations for individuals affected by familial dyslexia than for non-affected readers. An analysis of errors made during oral reading of nonsense passages showed that most readers substituted real words for nonsense words, often of similar visual configurations. These findings were discussed in the context of what is known about cerebral functioning during reading. One interpretation of the present study is that affected readers used a reading strategy apparently mediated more by right than left hemisphere mechanisms, than did nonaffected readers.

Adolescent↗

The discrimination of vowel duration by infants.

Three groups of nine 5-11-month-old infants provided evidence of discrimination of speechlike stimuli differing only in vowel duration. Ease of discrimination was directly related to the magnitude of the ratio of the longer to shorter vowel. Group one infants discriminated three vowel duration contrasts (with ratios of 0.33, 0.67, and 1.0) embedded in a synthetic [mad] syllable; group two discriminated these same duration contrasts within the bisyllable [ samad ], and group three in the trisyllable [ masamad ]. In all cases, the contrasting durations were carried by the last vowel of the synthetic word. These same three infant groups failed to provide evidence of discrimination of a final position released stop consonant contrast ([mat] versus [mad]) cued by voice excitation during closure of the [d] and not the [t]. These results suggest that vowel duration may be a primary cue for infants' perception of the voicing of final position stop consonants.

Adult↗

The life-cycle of Eimeria cernae Levine and Ivens, 1965 in the bank vole, Clethrionomys glareolus.

Eimeria cernae is recorded for the first time in England and the life-cycle is described in experimentally infected bank-voles (Clethrionomys glareolus). The pre-patent period was 6 days and the patent period was 4-6 days. Oocysts were ellipsoidal in shape and measured 20.2 x 15.9 micrometers. Sporocysts, measuring 11.5 micrometers long and 6.8 micrometers wide, possessed a small stieda body and contained a mass of granular sporocyst residuum. The endogenous stages developed in the epithelial cells of the colon and rectum. Three generations of schizonts were found. The 1st-generation schizont seen at 48 h post-infection (p.i.) contained up to 8 merozoites, the 2nd-generation schizont seen at 72 hr p.i. had a mean number of 16 (12-20) merozoites and the 3rd-generation schizont at 96 h p.i. had a mean of 18 (14-21) merozoites. Gamogonic stages were present from 96 to 120 h p.i. in the rectum only.

Animals↗

Methadone effects on brain functioning and type A and B CNV shapes.

Twelve male outpatients participating in a methadone maintenance treatment program were evaluated for the effects of acute administration of methadone on brain functioning (contingent negative variation or CNV), attention performance (reaction time and continuous performance test), and psychophysiological activity (heart rate and eye blink rate). Individual differences in response to methadone were assessed by classifying patients into two groups on the basis of basal CNV shapes: Type A (quick rise time) and type B (slow rise time). Methadone produced a pattern of increased electrical brain activity (CNV) and enhanced attention performance in type B patients and elevated heart rate and lowered eye blink rate in type A subjects. Results are interpreted in terms of the distraction-arousal and the eye blink-hedonia hypotheses.

Adult↗

Narcotic antagonist treatment: clinical experience with naltrexone.

Narcotic antagonist (naltrexone) treatment experience with 22 opioid addicts over a 29-month period shows that the mean duration of receipt of naltrexone was 6.2 weeks, and 12 subjects (55%) continued in treatment after cessation of naltrexone for an average of 5.6 weeks. Analysis of physical and behavioral measured revealed no toxicity, indicating that naltrexone appears to be a safe drug. Clinical evaluation of the patients receiving naltrexone suggests that ingestion of naltrexone provides a degree of external control, reducing the preoccupation with heroin and releasing energy for the pursuit of other goals. Subject follow-up at an average of 45.3 weeks after cessation of naltrexone indicated that 11 (58%) were known to be abstinent, and 9 (47%) subjects were employed compared with 3 (16%) employed at the onset of treatment.

Adolescent↗