Biomedical subjects
J Greenstein
Publications and source records attributed to J Greenstein.
The use of advanced technology for visual inspection training.
In the past, training with traditional methods was shown to improve inspection performance. However, advances in technology have automated training and revolutionized the way training will be delivered in the future. Examples of such technology include computer-based simulators, digital interactive video, computer-based training, and intelligent tutoring systems. Despite the lower cost and increased availability of computer technology, the application of advanced technology to training within the manufacturing industry and specifically for inspection has been limited. In this vein, a case study is presented which shows how advanced technology along with our basic knowledge of training principles, can be used to develop a computer-based training program for a contact lens inspection task. Improvements due to computer-based inspection training were measured in an evaluation study and are reported.
A prospective cohort study of intake of calcium, vitamin D, and other micronutrients in relation to incidence of rectal cancer among postmenopausal women.
To investigate whether high intakes of calcium and other micronutrients (carotene, retinol, and vitamins C, D, and E) are related to reduced risks of rectal cancer, we analyzed data from a large cohort study of postmenopausal Iowa women who responded to a mailed survey in 1986. After 9 years of follow-up, 144 incident rectal cancer cases were ascertained among the 34,702 women at risk. Intake levels of micronutrients at baseline were derived from self-reported data on vitamin supplements and dietary intake of 127 foods included in a semiquantitative food frequency questionnaire. After adjustment for total energy intake and other potential confounding factors, a dose-response inverse association was observed between total calcium intake and the risk of rectal cancer: adjusted relative risks (RRs) were 1.00, 0.90, and 0.59 (trend test, P = 0.02) from the lowest to the highest calcium intake tertiles. High intakes of dietary and supplement calcium were both related to a slightly reduced risk of rectal cancer, but neither of the trend tests was statistically significant. Reduced risks of rectal cancer were also observed for high intake of carotene and vitamins A, C, and D, although none of the associations were statistically significant. For vitamin D, the adjusted RRs were 1.00, 0.71, and 0.76 (trend test, P = 0.20) for increasing intake tertiles. Compared with women who consumed low levels of both total calcium and vitamin D, those in the highest intake group of both nutrients were at a 45% reduced risk of rectal cancer (RR, 0.55; 95% confidence interval, 0.32-0.93). This study supports the hypothesis that high intake of calcium and possibly other micronutrients may be beneficial in the prevention of rectal cancer.
Validation study of self-reported measures of fat distribution.
OBJECTIVE: To determine the validity of self-reported body circumferences and indices of body fatness in comparison with the same variables measure by technicians. DESIGN: Cross-sectional survey. SUBJECTS: 66 women aged 40-81 years. MEASUREMENTS: Self-reported weight and height and waist, hip, chest and bust circumferences, by mail questionnaire. The same measurements taken by a trained technician during a clinic visit. Derived variables of body mass index, waist-to-hip ratio, and conicity index, based on both self-reports and technician measurements. RESULTS: Mean differences between technician measurements and self measurements indicated that, on average, women tended to systematically underestimate their body circumferences. Age-adjusted Pearson correlations between technician measurements and self measurements ranged from 0.93 (95% confidence interval: 0.89, 0.96) for hips to 0.99 (95% Cl: 0.98, 0.99) for weight. For derived variables (quotients of measures), the highest agreement (r = 0.98, 95% Cl: 0.97, 0.99) was observed for body mass index (weight in kg/height in m2). The ratio of circumferences of the waist and hips was correlated less strongly (r = 0.76, 95% Cl: 0.63, 0.85). The correlation for conicity index, a measure of fat distribution that is independent of hip measurement variability, was 0.82 (95% Cl: 0.72, 0.88). Overall, accuracy of self measurements did not appear to vary according to age. There was an indication that with increasing values of weight and waist measurements, there was an increasing tendency for women to underestimate the measurement. This was also reflected in the accuracy of the derived variables body mass index and waist-to-hip ratio, but not the conicity index. CONCLUSIONS: These results indicate that self measurements of these anthropometric variables are highly accurate even when used to formulate derived variables, and are therefore appropriate for epidemiologic studies.
Comparison of 1.5 Tesla and 0.35 Tesla field strength magnetic resonance imaging scans in the morphometric evaluation of the lumbar intervertebral foramina.
OBJECTIVE: To compare magnetic resonance imaging (MRI) scans obtained from 1.5 Tesla (T) MRI units with scans obtained from 0.35T MRI units in the morphometric evaluation of the lumbar intervertebral foramina (IVF). DESIGN: Three dimensions of lumbar IVFs were measured on a cadaveric lumbar spine by using Vernier calipers. The spine was embedded in gelatin to simulate soft tissue and scanned twice in a 1.5T MRI unit (3-mm and 5-mm slice thicknesses) and once in a 0.35T MRI unit (5-mm slice thickness). Measurements from the scans were made independently by three observers. The results obtained from the two units were compared to the actual IVF size (as measured by calipers) and to one another. RESULTS: The greatest superior-to-inferior distance had the strongest statistically significant correlation to the actual cadaver measurements for both the 0.35T and 1.5T imaging units [r = 0.986 (0.35T); r = 0.985 (1.5T at 3 mm) and r = 0.981 (1.5T at 5 mm); p < .0001 in all cases]. Mean differences and standard errors were minimal between measurements made from MRI scans of both 1.5T and 0.35T units and measurements made directly from the cadaveric spine. CONCLUSION: Both imaging units produced images that accurately depicted the actual size of the IVF. The MRI units of 0.35T field strength produced images of high morphometric accuracy. In addition, the potential for side effects and the operating costs are less with 0.35T units. Therefore, 0.35T MRI units may be a prudent choice as a clinical and research imaging tool in the evaluation of the lumbar IVF.
Tizanidine treatment of spasticity caused by multiple sclerosis: results of a double-blind, placebo-controlled trial. US Tizanidine Study Group.
This multicenter, stratified, randomized, placebo-controlled, double-blind trial evaluated tizanidine for use in the United States for spasticity secondary to MS. The 15-week trial was divided into baseline (weeks 0 and 1), titration (2 mg to a maximum of 36 mg/d; weeks 2 to 4), and plateau (weeks 5 to 13) phases, followed by dose tapering (week 14) and a final visit (week 15). Primary efficacy parameters were scores on muscle tone (Ashworth Scale) and type and frequency of muscle spasms (patient diaries). All efficacy parameters were evaluated by the physician/assessor, and the physician/prescriber was responsible for all dosage adjustments. The patient, physician/assessor, and physician/prescriber made global evaluations of antispastic efficacy. Tizanidine produced a significantly greater reduction than placebo in spasms and clonus (patient diaries) but no significant differences in Ashworth scores. Patients and physician/prescribers, but not physician/assessors, gave significantly better scores in the overall assessment of efficacy and tolerability. No significant differences in other secondary efficacy parameters were noted. Adverse events were reported for 66 (61%) of the 109 placebo-treated patients and 101 (91%) of the 111 tizanidine-treated patients; 6 (6%) and 14 (13%) discontinued treatment, respectively. Patient and physician perception of improvement demonstrated more consistent differences between groups than did the Ashworth Scale, perhaps because of inexperience with this measure or failure to consider time between drug administration and assessment.
Phase coherence in vibration-induced responses of tactile fibres associated with Pacinian corpuscle receptors in the cat.
1. In pentobarbitone-anaesthetized cats, responses were recorded in peripheral nerves or cervical dorsal columns from sensory fibres associated with Pacinian corpuscle (P.c.) receptors in the forelimb footpads. Factors affecting the phase of response to cutaneous vibration in individual P.c. fibres, and the extent of phase coherence in the responses of different P.c. fibres were examined when sinusoidal vibratory stimuli at 100-400 Hz were delivered using a 1 mm diameter probe. 2. Increases in vibration amplitude from the absolute to the 1:1 threshold for the P.c. fibre led to phase advances in the response, often of about 60 deg, in over 85% of fibres tested at 200 and 300 Hz, but further increases had little effect. 3. Variations in stimulus position within the receptive field led to unpredictable changes in the response phase that ranged from minimal change to shifts of 180 deg. As the response phase was unrelated to the distance from the point of peak sensitivity it is likely that at high vibration frequencies (greater than or equal to 100 Hz) the recruited population of P.c. fibres will respond over the whole range of phase angles. 4. The calculated phase of spike initiation in different pairs of P.c. fibres that shared coincident points of best sensitivity on the skin ranged from near synchrony to maximum asynchrony indicating that there is little phase coherence even in the subpopulation of somatotopically related P.c. fibres recruited by high-frequency cutaneous vibration. 5. Paired recordings from P.c. fibres within the cervical dorsal columns revealed a broad range of phase discrepancies in the responses of P.c. fibres to vibration at 200 and 300 Hz. 6. Several hypotheses are considered to explain the known presence of phase-locked responses to high-frequency (greater than or equal to 100 Hz) vibration in the central neurones of dorsal column nuclei.
Alpha interferon clinical trial for multiple sclerosis: design considerations.
The design and course of a placebo-controlled alpha-2 interferon trial in MS patients are described. No beneficial effect of the interferon on the course of MS could be shown.
Major histocompatibility complex-restricted antigen receptor on T cells. VIII. Role of the LFA-1 molecule.
We show that the LFA-1 molecule on T cells does not play a role in the stimulation of T cell hybridomas by certain targets, namely antigen presented by L cell derivatives or polyvalent anti-receptor antibody. These results suggest that LFA-1 may act by binding to ligands that are not present on all cells. We hope this result will help us and others to establish the true role of LFA-1 in T cell responses.
Family and twin studies in multiple sclerosis.
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Lymphocytapheresis in chronic progressive multiple sclerosis: results of a preliminary trial.
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How do children's eating patterns and food choices change over time? Results from a cohort study.
PURPOSE: The purpose of this study was to investigate the change in eating patterns and food choices in a cohort of students as they moved from the third to the eighth grade. DESIGN: Dietary behaviors and food choices were abstracted from 24-hour recalls and compared across grade levels. SETTING: The setting for the study was elementary and junior high schools. SUBJECTS: The subjects were a cohort of 291 students from Minnesota. MEASURES: Individual 24-hour dietary recalls from a cohort of students were collected in the third, fifth and eighth grades. RESULTS: As students moved from elementary to junior high and middle school, their consumption of breakfast, fruits, vegetables, and milk decreased. Soft drink consumption increased. In the third grade, nearly 99% of the cohort reported eating breakfast; by the eighth grade, 85% reported eating breakfast. Fruit consumption fell by 41% between the third and the eighth grades while vegetable consumption fell by 25%. The proportion of beverage coming from soft drinks more than tripled between the third and the eighth grades with concomitant reductions in milk and fruit juice consumption. CONCLUSIONS: Family, school, and community-wide efforts are needed to promote healthful eating patterns and food choices among adolescents. Our research indicates that nutrition education is needed in the elementary and middle school years. In addition, we need to work on improving teens' social and physical environments to encourage and facilitate their choice of healthy foods.