Biomedical subjects
Publications and source records attributed to D Harris.
5 subjects matched pairs of auditory and vibrotactile stimuli on intensity, making judgments of suprathreshold magnitudes. Slope values for the 100-Hz cross-modal lingual vibrotactile stimulus-standard frequency condition were steeper than those for 250- or 400-Hz conditions. Slope values became steeper at about 25- to 30-dB SL, so frequency seems an important parameter to control in such research.
Temporal resolution values for the lingual tactile sensory system were obtained from 20 normal adult subjects. Contactor areas of .128 cm2, .32 cm2, and 1.3 cm2 were used to obtain fusion thresholds for all 20 subjects. An analysis of variance indicated no significant differences among fusion thresholds for any of the contactor sizes employed. Results are discussed in comparison to other research concerned with contactor area and in terms of the nature of lingual tactile mechanoreception.
Explore the source record for details and available documents.
The possible relationship between threshold and suprathreshold responses for the lingual tactile system was investigated. Lingual vibrotactile thresholds and suprathreshold magnitude function exponents were correlated for 26 adult subjects. A statistical analysis of the correlations indicated that there was no significant relationship between thresholds and exponents. Vibrotactile threshold and suprathreshold information may be useful in increasing understanding of the complexities of oral somesthesis.
An in vitro assay was used to determine whether mouse complement (C') was able to lyse T cells coated with a monoclonal IgM anti-Thy-1 antibody. Using lymph node cells (LNC) as targets, it was found that antibody-coated mature T cells were efficiently lysed by serum from C57BL/6, but inefficiently lysed by serum from BALB/c mice. Serum from both strains lysed antibody-coated thymocytes, demonstrating that BALB/c serum is not deficient in one of the C' components. The lytic activity of BALB/c serum could be improved by increasing the concentration of monoclonal anti-Thy-1 used to coat the target LNC. In contrast, serum from C5-deficient A/HeJ mice was unable to lyse either of the antibody-coated target cells in vitro. These in vitro results were confirmed in vivo using a model of lethal graft-versus-host disease (GVHD) induced to minor histocompatibility antigens. In this model, GVHD occurs when lethally irradiated mice are transplanted with bone marrow plus spleen cells from H-2-identical donor mice. GVHD is prevented when T cells are removed from the cells by in vitro treatment with anti-Thy-1 antibody plus rabbit C'. As predicted by the in vitro data, C57BL/6 mice were protected from GVHD when transplanted with LP cells treated with a 1:100 dilution of anti-Thy-1 antibody, but without complement, but BALB/c recipients of antibody-coated B10.D2/nSN cells were not. When the concentration of anti-Thy-1 used to coat the donor cells was increased to 1:50, 8 of 9 recipients were protected from GVHD. In contrast, none of the C5-deficient DBA/2 recipients of anti-Thy-1 (1:50 dilution) treated B10.D2 cells were protected from GVHD. Complement-mediated lysis appears to be the primary mechanism by which T cells coated with a monoclonal IgM anti-Thy-1 antibody are functionally inactivated in vivo.
Cricoid pressure may be performed when a sharp object such as an animal bone is lodged in the post-cricoid oesophagus. This study was undertaken to determine what damage, if any, may be caused to the oesophagus. A sharp foreign body was inserted into the post-cricoid region of 15 cadavers. In five cases no other procedure was performed. In the remaining 10 cases, intubation with and without cricoid pressure was also performed. No significant damage was visible to the naked eye when the oesophagus was subsequently examined. Cricoid pressure does not seem to result in significant damage in this situation.
Zinc salts (10(-4) and 10(-5) M) inhibited the number of Chlamydia trachomatis inclusions in McCoy, HeLa, and primary human prostate epithelial cell cultures. Addition of zinc salts 1 h before or 24 h after inoculation with C. trachomatis was found to inhibit growth. Both C. trachomatis serotype D and a lymphogranuloma venereum strain were inhibited by the zinc salts. Although the mechanism of inhibition is not known, the continued presence of the zinc appeared necessary for maximal effect. At the concentrations tested, zinc was not directly toxic to the McCoy cells. These results suggest that the levels of zinc in prostatic secretions may be sufficient to preclude the recovery of chlamydia in the diagnostic laboratory or to inhibit chlamydia from infecting the prostate in vivo.
Results of a comprehensive longitudinal study comparing the effects of feeding healthy preterm infants with human milk or a specially adapted formula designed for the preterm infant are reported. 10 healthy infants were given human milk from birth, and 9 similar infants were given a formula which contained 80 kcal, 1.8 g protein, and 4.5 g fat per 100 ml. Anthropometric measurements were made weekly as were routine haematological and biochemical variables together with plasma amino acid and gastrointestinal regulatory peptide levels and metabolic fuel concentrations. Infants receiving the formula demonstrated a significantly greater growth velocity compared with infants receiving human milk. There were no significant differences between the two groups in routine haematological or biochemical variables measured nor in plasma insulin or blood glucose, lactate, pyruvate, or ketone body concentrations. Plasma amino acid profiles, however, did demonstrate some significant differences between the two groups with higher methionine and threonine levels in the formula-fed infants. Plasma motilin, enteroglucagon, neurotensin, cholecystokinin, gastric inhibiting polypeptide, and pancreatic polypeptide levels all demonstrated significant postnatal surges, with significant differences between the two groups in plasma gastric inhibiting polypeptide and pancreatic polypeptide concentrations.
Plasma levels of 17 amino acids were measured in 10 conscious mothers and their minimally stressed fetuses (mean body weight 302 g) at 18-21 wk gestation. Simultaneous blood samples were taken from the maternal antecubital vein, and from the fetal umbilical vein and artery by fetoscopy prior to termination of pregnancy. The mean concentrations of all amino acids were significantly higher in the fetal (2.26 mmol/liter) than in the maternal (0.96 mmol/liter) circulation, the total molar concentration of amino acids was 2.4 times greater in fetal than in maternal plasma. There was a significant positive relationship between maternal and fetal levels for most amino acids; the mean umbilical concentration difference was significantly positive for glycine, alanine, isoleucine, leucine, phenylalanine, and histidine.
The present pilot study was designed to obtain samples of numerical vibrotactile magnitude estimations from two groups of 37 randomly selected subjects (Mage = 22.04 yr.) and to determine if these numbers were statistically equivalent. Analysis showed the numerical responses of the two groups of subjects were statistically equivalent. It was suggested that they might be viewed as a representative sample of magnitude-estimation numbers that could be employed in experimentation on lingual vibrotactile magnitude production.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Kidney renin concentrations were significantly lower in spontaneously hypertensive rats (SHR) than in normotensive Wistar Kyoto (WKY) rats. After treatment of both SHR and WKY rats with captopril (100 mg/kg p.o. for 3 months), kidney renin concentration increased dramatically in SHR and slightly, but significantly, in WKY. After captopril treatment, kidney renin content of SHR was still significantly lower than WKY. Because of the lower content of kidney renin in SHR and the proportionately greater increase in kidney renin content in SHR after captopril treatment than in WKY, it is proposed that a fundamental difference(s) in the control of the renin-angiotensin system exists in SHR, an effect which may or may not be related to SHR hypertension.
Non-abraded rabbit endothelium has been exposed to human blood taken from male non-smoking volunteers before and after the smoking of two medium tar cigarettes, in an in vitro system using a Baumgartner chamber. In each case the blood was allowed to circulate for 10 min at a constant flow rate. Blood from 10 volunteers has been tested in this way. Scanning electron microscopy of the endothelial surfaces demonstrates large numbers of adherent platelets when 'post-smoking blood' is used, but very few and in some cases none with the 'pre-smoking' blood. As a further control to ensure that this phenomenon did not occur as a result from changes in the vessel related to the time during which it had been removed from its normal physiological environment, blood from further non-smoking volunteers was passed over seven of the remaining pieces of vessel at the completion of these runs. Platelets were either absent or very few in number, as with the pre-smoking samples.
Explore the source record for details and available documents.
The stability of oral and nonoral vibrotactile magnitude scales produced by the method of magnitude production was investigated for 11 adult subjects. Each subject was tested over four sessions separated by 1-wk. intervals. Data analyses included correlations across trials of power function slopes as well as individual adjustments of intensity. Analysis showed a lack of stability over time for the slope functions obtained on the thenar eminence but moderate stability for the functions obtained on the tongue. Individual adjustments on intensity showed consistently high correlations across trials and structures. It was concluded that the subjects' responses were guided by the imposed experimental variables and that each individual's scaling was not necessarily reflected by the correlations based on power function slopes established over the four trials.
This study represents the first attempt to generate magnitude-estimation and magnitude-balance functions for the human tongue. Vibrotactile magnitude scales for the tongue and thenar eminence of the hand were investigated for nine adult subjects. The methods of magnitude estimation and magnitude production were used to obtain magnitude-balance functions for both structures. The magnitude-estimation task resulted in magnitude functions for the tongue which were similar in slope value to those found for the thenar eminence. The magnitude-production task also gave magnitude functions which were similar in slope value for the two structures.