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Biomedical subjects

R F Haines

Publications and source records attributed to R F Haines.

At least 19 recordsLinked to original sources
PubMed1996

Telesurgery. Acceptability of compressed video for remote surgical proctoring.

OBJECTIVE: To determine the clinical acceptability of various levels of video compression for remote proctoring of laparoscopic surgical procedures. DESIGN: Observational, controlled study. SETTING: Community-based teaching hospital. PARTICIPANTS: Physician and nurse observers. INTERVENTIONS: Controlled surgical video scenes were subjected to various levels of data compression for digital transmission and display and shown to participant observers. MAIN OUTCOME MEASURES: Clinical acceptability of video scenes after application of video compression. RESULTS: Clinically acceptable video compression was achieved with a 1.25-megabit/second data rate, with the use of odd-screen 43.3:1 Joint Photographic Expert Group compression and a small screen for remote viewing. CONCLUSION: With proper video compression, remote proctoring of laparoscopic procedures may be performed with standard 1.5-megabit/second telecommunication data lines and services.

Adult↗
PubMed1993

Schizophrenia, narcolepsy, and HLA-DR15, DQ6.

A strong association between HLA-DR2, DQ1 and narcolepsy-cataplexy has been known since 1986. In 1990 a subdivision (HLA-DR15, DQ6) was shown to be equally associated. Narcolepsy symptoms include rapid eye movement (REM)-sleep intrusion hallucinations during the day. Some narcoleptics may be so hallucinated that they become delusional and receive a diagnosis of schizophrenia. Fifty-six inpatient schizophrenics and 56 normal controls were compared to see if there was an excess of the narcolepsy-associated antigens (NAA) among schizophrenics. Patients had frequency of the NAA 3.89 times higher than controls. After a subset was studied by night (n = 9) and day (n = 7) polysomnography, two patients were found to be true narcoleptics. Their psychosis improved with treatment for narcolepsy. When NAA(+) and NAA(-) schizophrenics were compared, the NAA(+) subgroup had significantly higher Brief Psychiatric Rating Scale (BPRS) scores and more hospitalizations. There were no effects attributable only to gender or race. We conclude that narcolepsy can simulate schizophrenia in some cases, and that even in nonnarcoleptic patients, the HLA-DR15,DQ6 antigens mark a group of severe schizophrenics that merits further study.

Adult↗
PubMed1989

The effects of window shape and reticle presence on performance in a vertical alignment task.

This study was conducted to evaluate the effect of selected interior work-station orientational cuing upon the ability to align a target image with local vertical in the frontal plane. Angular error from gravitational vertical in an alignment task was measured for 20 observers viewing through two window shapes (square, round), two initial orientations of a computer-generated space shuttle image, and the presence or absence of a stabilized optical alignment reticle. In terms of overall accuracy, it was found that observer error was significantly smaller for the square window and reticle-present conditions than for the round window and reticle-absent conditions. Response bias data reflected an overall tendency to undershoot and greater variability of response in the round window/no reticle condition. These results suggest that environmental cuing information, such as that provided by square window frames and alignment reticles, may aid in subjective orientation and increase accuracy of response in a space station proximity operations alignment task.

Cues↗
PubMed1989

Space vehicle approach velocity judgments under simulated visual space conditions.

There were 35 volunteers who responded when they first perceived an increase in apparent size of a collimated, two-dimensional perspective image of an Orbiter vehicle. The variables of interest included the presence (or absence) of a fixed reticle within the field of view (FOV), background starfield velocity, initial range to the vehicle and vehicle closure velocity. It was found that: 1) increasing vehicle approach velocity yielded a very small (but significant) effect of faster detection of vehicle movement, nevertheless, response variability was relatively large; 2) including the fixed reticle in the FOV produced significantly slower detection of vehicle radial movement, however this occurred only at the largest range and the magnitude of the effect was only about 15% of the one sigma value; and 3) increasing background star velocity during this judgment led to slower detection of vehicle movement. While statistically significant, this effect was small and occurred primarily at the largest range. A possible explanation for the last two findings is that other static and dynamic objects within the visual field may compete for available attention which otherwise would be available for judging image expansion; thus, the target's retinal image has to expand more than otherwise for its movement to be detected. This study also showed that the Proximity Operations Research Mockup at NASA/Ames can be used effectively to investigate a variety of visual judgment questions related to future space operations. These findings are discussed in relation to previous research and possible underlying mechanisms.

Adult↗
PubMed1988

Vertical displacement threshold sensitivity along the horizontal meridian as a function of stimulus rate, duration, and length.

Vertical displacement thresholds (DT) were quantified in 24 observers at the fovea and each of 8 retinal positions out to 80 degrees along the horizontal meridian during binocular viewing. Stimulus length was increased with eccentricity angle in accordance with the cortical magnification factor (21); a 1 degree arc long stimulus served as a control at each position. Three movement durations (from 0.25 to 4 s) and three angular rates (from 0.04 to 0.42 degrees arc.s-1) were also quantified at each position to determine whether peripheral DT is mediated predominantly by an image displacement- or rate-sensitive mechanism. It was found that 1) DT is mediated predominantly by a constant rate-sensitive mechanism at each position when stimulus length is increased in proportion to the cortical magnification factor; 2) mean percent correct displacement judgments decrease significantly into the periphery for both stimulus lengths, however, increasing stimulus length yields significantly higher accuracy; and 3) at 10 and 30 degrees eccentricity, increasing rate and duration significantly improve displacement judgment accuracy, but beyond 40 degrees only lengthening the stimulus improves accuracy. The findings are related to the design optimization of dynamic attitude displays and symbology for aircraft.

Adolescent↗
PubMed1986

Displacement thresholds in central and peripheral vision during tracking.

In this study 26 observers were presented a series of forced choice, paired comparison trials in which a long, thin, collimated, horizontally oriented (horizon) line moved downward through 12 angles ranging from 0.6-60' of arc on one of the two trials. They had to judge which stimulus had moved in each pair. The displacements were produced by combinations of five stimulus displacement durations (0.25, 0.5, 1,2, and 4 s) and four stimulus angular velocities (0.042, 0.083, 0.167, and 0.25 degrees X s-1 for a total of 20 conditions. It was found that increasing stimulus duration produced significantly more correct displacement judgments. These results are consistent with the hypothesis that threshold is based on a constant stimulus velocity over this range of durations and velocities. However, since fixation remained on the stimulus during its smooth displacement, a corollary neural discharge associated with the voluntary rotation of the eyes may have been a major contribution to this judgment.

Adolescent↗
PubMed1981

Major histocompatibility complex antigens, maternal and paternal immune responses, and chronic habitual abortions in humans.

Women with recurrent consecutive spontaneous abortions of unknown etiology compared with those with recurrent spontaneous abortions of known etiology had a significantly increased frequency of sharing HLA antigens at the A, B, and D/DR loci with their spouses. This major histocompatibility complex (MHC) homozygosity was generally associated with female (responder) and male (stimulator) hyporeactivity in mixed lymphocyte culture reactions. The results indicate that MHC homozygosity between spouses is associated with postfertilization pregnancy wastage in humans.

Abortion, Habitual↗
PubMed1981

Orthostatic fluid-electrolyte and endocrine responses in fainters and nonfainters.

A tilt-table test was administered to five young men before (test 1) and after (test 2) 8 days of heat acclimation (2-h daily exercise at 50% VO2max at 40 degrees db, 30 degrees C wb) and to five other young men before and after the same exercise at 24 degrees C to determine fluid-electrolyte and endocrine responses in orthostasis in fainters and nonfainters. Half of the 10 subjects showed improved orthostatic reactions from test 1 to test 2 (disappearance of nausea and dizziness and improved heart rate and blood pressure), and the other 5 subjects showed no improvement. The improvement, especially in the nonfainters, was related to increases in posttilt plasma volume (PV) and plasma concentration of potassium. During test 1, plasma renin activity (PRA) increased five times from supine to orthostatis, with a corresponding increase in plasma vasopressin (ADH) of 50 times. The corresponding increases in test 2 were lower by 50 and 75% compared with those occurring in test 1 for PRA and ADH, respectively. PRA was five times higher in nonfainters than in fainters in test 1, whereas ADH showed an opposite trend. The orthostatic-induced increase in ADH seems to be related to volume control independent of PRA. This increase is reduced with improvement in orthostatic reactions, probably because of an increase in PV.

Adult↗
PubMed1980

Affective illness and HLA frequencies: no compelling association.

114 patients suffering from an endogenomorphic affective illness were typed for HLA antigens at the A and B loci, and the frequencies were compared with those of a control panel numbering 439 individuals. Using new analytical procedures, a large number of tests were conducted, but no convincing evidence for an association of HLA types with affective disorders was obtained. A reanalysis of the same data, where patients are classified according to Danish diagnostic criteria, yields a marginally significant association of the B locus alleles. The sample sizes for this latter analysis were small, the test criteria are undoubtedly inflated, and no compelling case can be made for a useful association.

Alleles↗
PubMed1979

Deconditioning-induced exercise responses as influenced by heat acclimation.

Five young men were tested on a bicycle ergometer before (Test 1) and after (Test 2) 8 d of heat acclimation (exercise at 50% of Vo2max at 39.8 degrees C DB, 30.0 degrees C WB) and after 8 h of water immersion (Test 3). A control group of five subjects underwent a similar procedure in a temperate environment of 23.8 degrees C. Heat acclimation resulted in the usual decreases in exercise heart rate (30 beats/min) and rectal temperature (0.6 degrees C) and an increase in sweat rate (19%). The control group showed effects of moderate training by decreases in exercise heart rate (11 beats/min), rectal temperature (0.3 degrees C), and sweat rate (24%). Water immersion resulted in substantial diuresis in both groups, despite 1800 ml of water consumed by each subject. In the acclimation group, exercise responses in Test 2 were better than in Test 1, with little improvement shown by the control group. The acclimation group maintained exercise responses in Test 3 as in Test 1, with more adverse responses shown by the control group. The results show that heat acclimation provides an effective method to prevent the adverse effects of water-immersion deconditioning on exercise tolerance.

Acclimatization↗
PubMed1977

Visual response time to colored stimuli in peripheral retina: evidence for binocular summation.

Simple onset response time (RT) experiments, previously shown to exhibit binocular summation effects for white stimuli along the horizontal meridian, were performed for red and green stimuli along 5 oblique meridians. Binocular RT was significantly shorter than monocular RT for a 45-min-diameter spot of red, green, or white light within eccentricites of about 50 deg from the fovea. Relatively large meridian differences were noted that appear to be due to the degree which the images fall on corresponding retinal areas.

Adolescent↗
PubMed1976

Sequential renal transplants: some surgical and immunological implications on management of the first homograft.

Experience with 35 second grafts included in a total number of 310 renal transplants was analyzed to identify factors associated with success. The 2 year life-table renal survival rate of sequential cadaveric grafts is 42 percent compared in 54 percent for primary cadaveric grafts. The 2 year life-table patient survival rate for the same group is 68 percent compared to 72 percent for single cadaveric homotransplants. Twenty-one of 30 patients tested in the interval between grafts developed cytotoxic antibodies to greater than 5 percent of a random panel of cells; 43 percent of these kidneys functioned at least one year; 65 percent functioned for one year or more if the cytotoxicity was 5 percent or less. If the first graft functioned greater than 3 months, the second had a 67 percent chance of functioning for one year; if less than 3 months, the second had a 45 percent one year function rate. Removal of the first transplant at time of second transplantation resulted in an 88 percent one year life-table survival rate of the second kidney in nine patients. Removal prior to second transplantation resulted in a 25 percent one year survival rate in 23 patients. To further evaluate this significant finding, data was obtained through the American College of Surgeons/National Institutes of Health (ACS/NIH) Organ Transplant Registry from five major transplant centers. Thirty-two patients had their first graft removed at time of second transplantation with a 52 percent one year life-table kidney survival rate vs. 29 percent if the first were removed more than 90 days prior to second grafting. Statistical analysis shows this to be significant at the 95 percent confidence level.

Antibody Formation↗
PubMed1975

Peripheral visual response time and retinal luminance-area relations.

Button pressing response time was measured in five trained subjects to the onset of small visual stimuli imaged across the horizontal retinal meridian at 10 degrees arc intervals from 90 degrees arc right to 90 degrees arc left of the line of sight. Four stimulus luminance conditions were presented at each peripheral retinal location, a low luminance condition (approx. 2.6 ft-L), a high luminance condition (arox. 22.2 ft-L), and two conditions in which luminance was varied systematically from low to moderately intense levels from one side of the visual field to the other. The two variable luminance conditions were included to see if it is possible to compensate for the progressive decrease in retinal stimulus image area caused by the apparent pupil. The results indicated that response time to stimuli imaged within approximately 70 degrees arc from the fovea does not differ significantly when all possess about the same luminance. Mean response time is significantly faster to stimuli imaged beyond about 70 degrees arc from the fovea when their luminance is increased by an amount equal to the foveal stimulus luminance multiplied by the cosine of the angle between the peripheral stimuli and the line of sight. These data are discussed in relation to previous psychophysical data and to possible response mechanisms.

Adult↗
PubMed1975

Binocular summation and peripheral visual response time.

Six males were administered a peripheral visual response time test to the onset of brief, small stimuli imaged in 10 degrees arc separation intervals across the dark adapted horizontal retinal meridian under binocular and both monocular viewing conditions. This was done in an attempt to verify the existence of peripheral binocular summation using a response time measure. The results indicated that from 50 degrees arc right to 50 degrees arc left of the line of sight binocular summation is a reasonable explanation for the significantly faster binocular data. The stimulus position by viewing eye interaction was also significant. A discussion of these and other analyses is presented along with a review of related literature.

Adolescent↗