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Biomedical subjects

D I Smith

Publications and source records attributed to D I Smith.

At least 145 records · Page 8Linked to original sources
PubMed1987

Rate and filter effects on the developing middle-latency response.

Auditory middle-latency responses (MLRs) were obtained from 71 unanesthetized gerbils ranging in age from 10 to greater than 90 days. Effects of age, stimulation rate, high- and lowpass filter settings and filter slope were examined. MLR amplitude decreased significantly with increased stimulation rate at all ages, at rates up to 40/s. The detection of MLR waves (presence or absence) varied inversely with the rate of stimulation only in immature subjects. The amplitude of waves B (15 ms) and C (25 ms) was significantly larger with a highpass filter setting of 3 Hz as compared to 10 and 30 Hz. This effect was significantly more pronounced in developing animals as compared to adults. MLR amplitude was greater with a filter slope of 6 dB/octave as compared to 48 dB/octave, (10-2,000 Hz) and this effect was also significantly greater in developing animals than in adults. There was no interaction between lowpass filter setting and age (100 vs. 2,000 Hz). A prominent positive wave occurring at approximately 50 ms was present in the 48 dB/octave condition although it was not observed with 6 dB/octave filtering. The clinical use of the MLR requires a better understanding of the effects of stimulus and recording procedures on the response, and how they vary as a function of subject age.

Aging↗
PubMed1986

Evaluation of a residential AA program.

The purpose of the study was to evaluate the effectiveness of the Serenity Lodge alcohol rehabilitation program by comparing a group of 137 men who entered the program with the same number of similar men who did not enter the program after an admission to a detoxification hospital. The residential program, for which people must pay board, is based on the AA philosophy and reality therapy. Follow-up interviews were conducted with three-quarters of the men in each group. Even after allowing for spontaneous remission as measured by the improvement in the control group, it was apparent that for a wide range of outcome criteria, and not just the obtaining of abstinence, the program was having a beneficial effect for the men who stayed at Serenity Lodge.

Adult↗
PubMed1986

Comparison of patrons of hotels with early opening and standard hours.

A comparison was made of 72 men who were patrons in hotels with 6 A.M. or 7 A.M. opening, with a control group of 87 men interviewed in nearby hotels with 10 A.M. opening. The two groups were very similar on biographical characteristics, yet the men in the early-opening group consumed significantly more alcohol, had more drinking sessions, spent longer in drinking, and had significantly higher SMAST scores. The early opening was apparently facilitating problem drinking.

Adult↗
PubMed1985

Cortical mapping of the auditory middle latency response in the unanesthetized guinea pig.

Auditory middle latency responses (MLRs) were mapped on the cortical surface of the unanesthetized guinea pig. The MLR consists of two positive peaks, designated A and C, with latencies of approximately 11 and 29 msec respectively, and a negative trough B, at 18 msec. Results suggest that each MLR component appears to have different generator sites and specific stimulus-response characteristics. The present work suggests that positive MLR components A and C have different generator sources because each component was maximally recorded from a different location over the contralateral temporal lobe. Little MLR activity was evident outside an area roughly 4 mm X 4 mm for each component.

Acoustic Stimulation↗
PubMed1985

Auditory middle latency responses in children: effects of age and diagnostic category.

The nature of auditory middle latency responses (MLRs) in children has been the subject of considerable debate. In order to study MLRs as a function of age, MLRs were obtained in 217 subjects ranging in age from 6 days to 20 years, all with normal auditory brain-stem responses (ABRs). Subjects were classified into several diagnostic categories: normal; communicative disorders (language delay, learning disability); mentally retarded, multiply handicapped; and post-meningitic. Age effects, the effects of diagnostic category, and possible differences in MLRs of males vs. females and right vs. left ears were examined. The detectability of both Na and Pa was found to increase significantly as a function of age. Detection of these MLR components became similar to adult values (approaching 100% detectability) at approximately 10 years of age. No significant differences were found among diagnostic categories. There were also no significant differences in the detectability of MLRs in males as compared to females, and there were no right vs. left ear differences. The strong age effect which appears to exist in the MLR influences their clinical use. When responses are present, they may be useful indicators of hearing sensitivity, but the absence of MLRs in children cannot be taken as an indication of hearing loss. Similarly, absent or abnormal MLRs cannot be interpreted as a manifestation of auditory pathway dysfunction, since there appears to be little difference in MLRs in normal subjects and MLRs in patients with a wide range of neurologic, cognitive, and speech and language disorders.

Adolescent↗
PubMed1985

Epidemiology of liver cirrhosis morbidity and mortality in Western Australia, 1971-82: some preliminary findings.

Liver cirrhosis mortality and morbidity (primary and secondary diagnosis) data for Western Australian men and women over the age of 30 years for the period 1971-82 are presented. Correlations between the morbidity and mortality data and adult consumption of beer, wine, spirits and absolute alcohol are also reported. Possible reasons for the various significant correlations are discussed, and in particular, with respect to the increasing wine consumption of adults (greater than or equal to 15 years).

Alcohol Drinking↗
PubMed1985

Auditory brainstem and middle latency responses in non-human primates.

Auditory brainstem (ABR) and middle latency responses (MLR) were obtained from each ear in 8 crab-eating macaques, 4 white-handed gibbons, 4 siamangs and 2 orangutans. Macaques ranged in age from 5 days to 15 years with the 6 older animals in age-matched, male-female pairs. From each animal, latency-intensity functions were obtained and multiple MLR recordings were measured at 60 and 70 dB. Latency-intensity functions, interwave intervals, thresholds and percent detectability were calculated for ABR waveforms. Waves II and IV were largest in amplitude and were most consistently detected at low stimulus intensities in all species tested. Waves I and II had adult latencies in the youngest animal tested (5-day-old macaque), while waves III and IV were prolonged in comparison to the 15-month-old macaque, in whom latencies had reached adult values. There were no apparent sex differences in evoked potentials in the age-matched, male-female pairs. A broad, negative MLR at 7-13 ms was observed in all animals. Longer latency MLRs varied among animals of the same species, but were replicable in some individuals, including the youngest macaque (5 days) and orangutan (7 months). These data were compared to responses obtained in humans, other primates and other vertebrates.

Animals↗
PubMed1985

Evaluation of a residential AA programme for women.

Follow-up interviews were conducted with 43 women who participated in a residential programme based on the work of Alcoholics Anonymous; the treatment outcome was compared to that of 35 similar women in a control group formed by a retrospective matching procedure. The control group received inpatient detoxification. For a wide range of outcome variables and, not just for abstinence, the treatment group had a significantly better outcome.

Adult↗
PubMed1984

.05% or 0.08%?

Explore the source record for details and available documents.

Adolescent↗
PubMed1984

Demonstration of insulin in the pancreas of the Didelphis albiventris (opossum) by immunocytochemical techniques.

The exocrine secretion of insulin by the suckling opossum was demonstrated by indirect immunofluorescence and immunoperoxidase techniques. In weanling and adult marsupial insulin is present in the pancreatic islets and in scattered cells located in the exocrine secretory units. Positive reaction was also observed in the brush border and in some isolated cells of the proximal segment of the suckling opossum small intestine.

Animals↗
PubMed1983

Evaluation of an inpatient alcohol rehabilitation programme.

A retrospective matching procedure was used to form a control group of 145 men who underwent detoxification, but unlike the treatment group did not enter the Quo Vadis Hospital rehabilitation programme. On a wide range of variables for which data was obtained at follow-up interview, respondents in the two groups were very similar. By contrast, official records data showed that the treatment group had significantly more readmissions to the detoxification hospital during the follow-up period than the control group. A number of methodological issues are briefly discussed.

Adult↗
PubMed1983

Anesthesia and surgical trauma: their influence on the guinea pig compound action potential.

A chronic implant consisting of a fine thermocouple placed on the round window permitted measurement of temperature and of the compound action potential (CAP) of the cochlear nerve in guinea pigs. Thresholds and latencies of the CAP, in response to tone bursts (2-40 kHz), were measured when the animal was awake and unrestrained, and again after several hours of anesthesia. The CAP remained unchanged with a variety of common anesthetics when precise control of round window temperature was maintained. However, when anesthesia was accompanied by several hours of slight cochlear cooling, thresholds were elevated for CAPs evoked by frequencies above 24 kHz and latencies were increased for CAPs evoked by all frequencies tested. The effects of surgery on CAP threshold and latency were also examined. Guinea pigs were tested while still anesthetized at the conclusion of the implantation procedure, and then again several days later while awake. Thresholds and latencies were unchanged. In two anesthetized guinea pigs already implanted with thermocouples, ventral and post-auricular surgery to expose the middle ear had no effect on the CAP, when low-speed drilling was used to open the auditory bulla. However, when small portions of the bulla were broken away with forceps, the CAP in response to high-frequency tone bursts immediately showed elevated thresholds. This alteration of the CAP was clearly different from that produced by lowered temperature, since the latencies at threshold were significantly decreased.

Action Potentials↗
PubMed1983

The temperature dependency of neural and hair cell responses evoked by high frequencies.

A fine thermocouple, placed on the round window of the guinea pig cochlea, was used to measure temperature and electrical potentials. In acute experiments, rectal temperature was held constant at 38 degrees C while cochlear temperature was varied between 38 degrees C and 31.5 degrees C. Cochlear cooling to 36 degrees C caused elevated thresholds for the compound action potential (CAP) in response to tone bursts with frequencies above 24 kHz. CAP latencies increased for all frequencies tested (2 to 40 kHz). Cooling to lower temperatures produced larger latency increases and greater threshold shifts which extended to CAPs evoked by frequencies as low as 16 kHz. These CAP changes were fully reversible after a cochlear temperature of 38 degrees C was restored. In an attempt to create more uniform cooling of the cochlea, experiments were also conducted with round window thermo-couples chronically implanted in guinea pigs. After cooling the entire anesthetized animal to 36 degrees C, CAP thresholds were again elevated only for frequencies above 24 kHz. In other acute experiments, extracellular dc receptor potentials were recorded from the organ of Corti with micropipettes. Cooling caused a decreased sensitivity to tones at the characteristic frequency of the recording location (20 kHz) and had less effect on responses to lower frequencies. The receptor potential usually recovered after rewarming the cochlea. These data emphasize that temperature is an important parameter when electrophysiological measurements are being made. They also suggest an explanation for the reported discrepancy between behavioral and electrophysiological thresholds at high frequencies.

Action Potentials↗
PubMed1983

Predicting success in limb salvage.

While success in revascularization procedures for severe arterial insufficiency--limb salvage--demands a technically correct operation, the adequacy of the outflow system is equally important. An outflow index (phi), the percentage drop in femoral artery pressure following an intra-arterial injection of papaverine, was developed. The predictive value of this index was demonstrated in a prospective study of 44 limbs in which an aortoiliac procedure with profundoplasty was done for multilevel disease. In the operations considered completely successful (n = 27), the mean value of phi was 37 +/- 8 per cent; this was significantly greater (P less than 0.001) than the mean value of 16 +/- 9 per cent found for those operations (n = 17) deemed to have been unsuccessful on the basis of rigorous postoperative criteria. This finding not only proves the efficacy of the index, but emphasizes the importance of an outflow system with the ability to accept more blood.

Arterial Occlusive Diseases↗