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Biomedical subjects

D Harris

Publications and source records attributed to D Harris.

At least 235 records · Page 13Linked to original sources
PubMed1987

Benzodiazepine--induced event amnesia following a stressful surgical procedure.

In a randomised, double-blind, parallel groups study, 40 patients undergoing surgical removal of impacted third molar teeth received either midazolam 15 mg orally followed at 35 min by intravenous saline or oral placebo followed by intravenous diazepam 10 mg (Diazemuls). Episodic (event) memory was assessed by showing patients photographs of dental and neutral objects both before and after sedation and by testing subsequent recognition at 1 week. Recall of actual surgical events was assessed by questionnaire. Both treatments induced significant amnesia for visual stimuli and for surgical events. However, the degree of amnesia was more profound for artificial stimuli and no relationship was found between the extent of amnesia for the two types of event. Drilling of bone was found to provoke the greatest cardiovascular stress response and a significant relationship was found between the degree of cardiovascular activation and subsequent memory for drilling. It is concluded that the extent of benzodiazepine-induced event-amnesia may be modified by cognitive factors and especially by the extent to which the event is cognitively encoded and elaborated.

Adult↗
PubMed1987

Cystine and lysine transport in cultured human renal epithelial cells.

The transport of the amino acids, cystine and lysine, was studied in epithelial cell lines propagated from human kidney cortex. Cystine uptake data were reproducible in different cell lines and did not vary over several cell passages of an individual cell line. The transport of this disulfide amino acid was sodium-dependent with kinetic analysis showing one apparent Kt system of 0.09 mmol/L and Vmax of 0.054 mmol/L cell water/min. Studies of the kinetics of lysine transport, however, revealed two uptake systems with apparent high and low affinities with Kt of 0.14 mmol/L and 5 mmol/L and Vmax of 0.041 and 0.167 mmol/L cell water/min, respectively. Glutamate appeared to be the most potent inhibitor of cystine uptake by these cultured human renal cells and this interaction was competitive. Although cystine did not inhibit lysine uptake, arginine and ornithine were shown to be major inhibitors, thus providing evidence for the presence of a shared dibasic amino acid transport system.

Arginine↗
PubMed1987

Comparison of midazolam by mouth and diazepam i.v. in outpatient oral surgery.

In a randomized double-blind, parallel groups study, 40 patients undergoing surgical removal of impacted 3rd molar teeth received either midazolam 15 mg orally followed at 35 min by i.v. saline, or oral placebo followed at 35 min by i.v. diazepam 10 mg (Diazemuls). Rapid onset of sedation was seen after midazolam, while the pattern and duration of postoperative sedation, as measured by standard psychometric tests, indicated slower recovery after midazolam than after diazepam. Ratings by the surgeon indicated superior anxiolysis following midazolam and significantly more patients expressed a preference for oral midazolam sedation. Significant, comparable anterograde amnesia was seen with both treatments. No significant cardiovascular complications occurred with either treatment. The findings indicate that rapidly acting oral benzodiazepines such as midazolam provide safe, effect alternatives to i.v. diazepam for conscious sedation in outpatients undergoing minor surgical procedures.

Administration, Oral↗
PubMed1987

Nodule activity and allocation of photosynthate of soybean during recovery from water stress.

Nodulated soybean plants (Glycine max [L.] Merr. cv Ransom) in a growth-chamber study were subjected to a leaf water potential (psi w) of -2.0 megapascal during vegetative growth. Changes in nonstructural carbohydrate contents of leaves, stems, roots, and nodules, allocation of dry matter among plant parts, in situ specific nodule activity, and in situ canopy apparent photosynthetic rate were measured in stressed and nonstressed plants during a 7-day period following rewatering. Leaf and nodule psi w also were determined. At the time of maximum stress, concentration of nonstructural carbohydrates had declined in leaves of stressed, relative to nonstressed, plants, and the concentration of nonstructural carbohydrates had increased in stems, roots, and nodules. Sucrose concentrations in roots and nodules of stressed plants were 1.5 and 3 times greater, respectively, than those of nonstressed plants. Within 12 hours after rewatering, leaf and nodule psi w of stressed plants had returned to values of nonstressed plants. Canopy apparent photosynthesis and specific nodule activity of stressed plants recovered to levels for nonstressed plants within 2 days after rewatering. The elevated sucrose concentrations in roots and nodules of stressed plants also declined rapidly upon rehydration. The increase in sucrose concentration in nodules, as well as the increase of carbohydrates in roots and stems, during water stress and the rapid disappearance upon rewatering indicates that inhibition of carbohydrate utilization within the nodule may be associated with loss of nodule activity. Availability of carbohydrates within the nodules and from photosynthetic activity following rehydration of nodules may mediate the rate of recovery of N2-fixation activity.

Acetylene↗
PubMed1987

Assessment of gastric emptying using gamma scintigraphy.

Gamma scintigraphy was used to measure the gastric emptying rates of three test meals in human volunteers. Emptying rates were determined for solid and liquid materials alone, and for liquid in the presence of solid material. It was shown that the emptying of solids from the stomach was significantly slower than that of liquid, whether liquid alone or liquid in the presence of solid material. It was concluded from these results that, in the case of a solid test meal from which radio-label could be eluted, the free label would empty considerably faster than the remaining solid material. The emptying rate observed scintigraphically would not, therefore, be a true estimate of the solid emptying rate.

Contrast Media↗
PubMed1987

Removal of benign intraoral masses using the CO2 laser.

Benign soft tissue lesions of the mouth can be removed using the CO2 laser. This type of laser surgery is faster and offers less postoperative complication as compared with conventional surgery and electrosurgery. Presently, the CO2 laser can be used for intraoral biopsy of benign masses, gingivectomies, and frenectomies.

Adult↗
PubMed1987

Magnitude estimation and magnitude production: stimulus frequency effects on magnitudes of lingual vibrotactile sensation.

The methods of magnitude estimation and magnitude production were employed to investigate the effects of stimulus frequency on supra-threshold lingual-vibrotactile sensation-magnitude functions. The method of magnitude estimation was used to obtain numerical judgments of sensation magnitudes for nine stimulus intensities presented to the anterior dorsum of the tongue. The vibrotactile stimulus frequencies employed for 10 subjects (M age = 21.1 yr.) were 100, 250, and 400 Hz. The numerical responses obtained during the magnitude-estimation task were in turn used as stimuli to obtain magnitude-production values for the same three vibrotactile stimulus frequencies. The results appeared to present two suggestions. First, the effects of stimulus frequency on lingual vibrotactile-sensation magnitudes may be dependent on the psychophysical method used in any particular experiment. Second, lingual-vibrotactile magnitude-estimation scales may demonstrate asymptotic growth functions above about 25 dB sensation level. The limitation in the growth of sensation magnitude occurred for all three vibrotactile stimulus frequencies employed.

Adult↗
PubMed1987

Effects of aging on responses to suprathreshold lingual vibrotactile stimulation.

Lingual vibrotactile suprathreshold sensation magnitudes were investigated across four age groups (M ages = 7.8 yr., 19.3 yr., 45.2 yr., and 57.0 yr.; age range = 5 to 64 yr.) by employing the psychophysical methods of magnitude estimation and cross-modal matching. Lingual vibrotactile stimuli were presented in combination with auditory stimuli for the cross-modal matching task. For lingual vibrotactile magnitude estimation, both the upper and lower power functions were steeper for the oldest age group. The power functions for cross-modal matching in which the vibratory stimulus was the standard showed asymptotic growth at about 25-dB sensation level for the three older age groups, but not for the youngest age group. Straight-line power functions were obtained for all age groups on the cross-modal matching task when the auditory stimulus was the standard, with the older aged subjects making larger lingual vibrotactile magnitude adjustments to the lower level auditory stimuli than the younger aged subjects. These results are discussed in relation to neurophysiological and behavioral changes which occur during development and aging.

Adolescent↗
PubMed1987

Midline and off-midline tongue and right- and left-hand vibrotactile thresholds of stutterers and normal-speaking individuals.

Vibrotactile thresholds for 7 male stutterers and 7 normal-speaking men (age range for both groups = 19 to 32 yr.) were obtained from the right, midline, and left sides of the lingual dorsum, and the thenar eminences of both hands. The stutterers showed slightly higher (less sensitive) mean thresholds than the normal speakers for all three lingual test sites. This was not the case for the thresholds obtained from both hands. The preliminary data suggest that oral peripheral sensory integrity might be somewhat different for stutterers than for normal-speaking individuals.

Adult↗
PubMed1987

Defective monocyte chemotaxis in active lepromatous leprosy.

This study of monocyte chemotaxis in leprosy patients showed a significant inverse correlation (p less than 0.05) of chemotaxis and the bacterial index (BI) (N = 22). In addition, there was a significant inverse correlation (p less than 0.05) between chemotaxis and the serum levels of anti-phenolic glycolipid-I IgM antibodies (N = 20). Patients taking thalidomide who had a BI greater than or equal to 1 had a significantly greater (p less than 0.001) chemotaxis response than that of patients with the same BI who were not taking thalidomide. No significant decrease in chemotaxis of monocytes from healthy donors was observed when the cells were pre-incubated with serum from 18 leprosy patients. We conclude that monocytes from patients with active lepromatous leprosy not receiving thalidomide have an intrinsic abnormality when assessed by chemotaxis.

Antibodies, Bacterial↗
PubMed1986

Signal transducing mechanisms involved in human T cell activation via surface T44 molecules. Comparison with signals transduced via the T cell receptor complex.

Antibodies against the T44 surface molecule have been shown to activate human T cells to produce interleukin 2. The role of Ca2+ in the triggering of the interleukin 2-producing Jurkat T cell line by anti-T44 monoclonal antibody has been investigated. We show that activation is initiated by an increase in the concentration of free cytoplasmic calcium ions [Ca2+]i. Subsequently, we have investigated the mechanism by which perturbation of T44 molecules induces increases of [Ca2+]i in Jurkat cells. We show that the anti-T44-mediated increase in [Ca2+]i can occur only in presence of extracellular Ca2+, since no increment is detectable when extracellular Ca2+ is depleted by EGTA. Thus, it appears that perturbation of T44 molecules, unlike that of T3-Ti antigen receptor complex, fails to mobilize Ca2+ from intracellular stores. As inositol triphosphate is considered the putative mobilizer of Ca2+ from internal stores, we measured the levels of inositol triphosphate and of the other inositol phosphate compounds in Jurkat cells after stimulation with anti-T44 antibodies. In contrast to the stimulation via the T3-Ti antigen receptor complex, stimulation via T44 molecule does not induce increments of all three inositol phosphates. Taken together, these data indicate that stimulation mediated by the T44 molecule proceeds via a mechanism independent from the typical inositol lipid metabolism which does not involve mobilization of Ca2+ from internal stores.

Antibodies, Monoclonal↗
PubMed1986

Differential effect of benzodiazepine sedation in high and low anxious patients in a "real life" stress setting.

In a randomised, double-blind, parallel groups study, 40 patients referred for surgical removal of impacted third molars received either (a) temazepam 40 mg orally followed at 35 min by IV saline or (b) oral placebo followed by IV diazepam 10 mg (Diazemuls). Patients were divided into High-Anxious and Low-Anxious groups by median split of their anxiety scores on the Speilberger State Anxiety Scale at the time of oral medication. Compared with placebo, temazepam significantly attenuated anticipatory anxiety in the High-Anxious group while in the Low-Anxious group no difference was found between the treatments. Preoperative but not intraoperative heart-rate distinguished between the High-Anxious and Low-Anxious groups and neither oral temazepam nor IV diazepam abolished the heart-rate response to the traumatic stages of the surgical procedure. The results are interpreted as providing support in a "real life" human stress setting for Gray's neuropsychological model of anxiety.

Adult↗
PubMed1986

Sedation in outpatient oral surgery. Comparison of temazepam by mouth and diazepam i.v.

In a randomized double-blind, parallel groups study, 39 patients undergoing surgical removal of impacted third molar teeth received either temazepam 40 mg by mouth (as soft gelatin capsules) followed at 35 min by i.v. saline, or oral placebo followed at 35 min by i.v. diazepam 10 mg (Diazemuls). Rapid onset of significant anxiolytic activity and psychomotor depression was seen following temazepam, while the pattern and duration of postoperative sedation measured with standard psychometric tests, were similar for both treatments. Ratings by the surgeon and by the patients indicated that sedation following the two treatments was comparable. No significant cardiovascular complications were found with either treatment. The findings indicate that rapidly acting oral benzodiazepines such as temazepam provide safe, effective alternatives to i.v. diazepam for sedation in outpatients undergoing minor surgical procedures.

Administration, Oral↗
PubMed1986

Continuous noninvasive estimation of cardiac output by electrical bioimpedance: an experimental study in dogs.

A new device has been developed to estimate continuously and noninvasively cardiac output from the thoracic electrical bioimpedance (CObi). CObi was compared to cardiac output by thermodilution (COtd) in five anesthetized dogs. Blood pressure, blood volume, and blood flow were manipulated by hemorrhage and infusions of sodium nitroprusside and phenylephrine. These data were used to determine the correlation between CObi and COtd under conditions of hypotensive normal flow and normotensive low flow, as well as during hemorrhagic shock and resuscitation. The CObi device was calibrated in vivo to COtd for each dog at the beginning of each experiment. CObi had a significant positive correlation with COtd throughout the experiments (r = 0.84, slope = 0.91, intercept = 0.55, p less than 0.01), and CObi predicted COtd with a standard error of the estimate of 0.81 L/min. Neither heart rate nor mean arterial pressure was significantly correlated with COtd or CObi. During severe hemorrhagic shock, CObi could not determine cardiac output in two of the dogs when COtd averaged 1.7 L/min. These data indicate that CObi is a blood-flow related variable that can be monitored continuously.

Animals↗
PubMed1986

Effects of exposure to psychophysical scaling on lingual vibrotactile magnitude estimation and magnitude production.

The purpose of the present study was to determine if the results obtained by the scaling methods of magnitude estimation and magnitude production could be influenced by providing subjects with prior exposure to psychophysical scaling in the form of magnitude estimation or magnitude production. Group 1 (n = 10, Mage = 21.1 yr.) performed lingual vibrotactile-magnitude estimation followed by lingual vibrotactile magnitude production. Group 2 (n = 10, Mage = 19.7 yr.) performed lingual vibrotactile-magnitude production (using the magnitude-estimation responses provided by Group 1), followed by lingual vibrotactile-magnitude estimation. For the magnitude estimations there was no over-all statistically significant difference between the two groups, but there was for the magnitude-production values. Magnitude-estimation scaling was apparently not influenced by prior exposure to magnitude production, while magnitude-production scaling was influenced by prior exposure to magnitude estimation. The results are discussed in terms of how subjective scaling behavior in psychophysical experimentation may be influenced by the interaction between an absolute internal scaling mechanism and parameters set by the experimenter, such as scaling method and range of stimulus intensity.

Adolescent↗
PubMed1986

Effect of stimulus pulse duration and interstimulus interval on cross-modal matching of auditory and lingual vibrotactile stimuli.

Cross-modal matching functions for eight intensity levels of a 1000-Hz auditory stimulus and a 250-Hz lingual vibrotactile stimulus were obtained for two groups of subjects. Group 1 adjusted the vibrotactile stimulus to match the auditory stimulus, and Group 2 adjusted the auditory stimulus to match the vibrotactile stimulus. Stimulus-pulse durations and interstimulus intervals were varied over six experimental conditions for both groups. The variations in stimulus-pulse durations and interstimulus intervals had no appreciable effect on mean matching-function exponents for the two groups. A possible regression effect consistent with data from other psychophysical scaling studies was noted for matching functions of the two stimuli.

Adolescent↗