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Biomedical subjects

R Epstein

Publications and source records attributed to R Epstein.

At least 73 records · Page 4Linked to original sources
PubMed1992

Is the establishing of tolerance to self obligatorily MHC restricted?

The prevailing paradigm used to interpret how T cells recognize antigen treats antigen processing as obligatory because the T cell antigen receptor complex can only detect antigen located in a "groove" found on MHC-encoded restricting elements. The vast majority of experimental systems used to analyze how T cells recognize antigen depend on induced T cells executing their effector functions, and it is agreed without exception that this event is MHC restricted. However, to date, the extrapolation of the obligatory MHC restriction of effector function to the level of the antigen-responsive T cell that makes the tolerance induction decision, depends not on experiment, but on theoretical constructs. The few experiments designed to test whether tolerance is MHC restricted are open to several interpretations, only one of which is consistent with the view that all antigen recognition events must be MHC restricted. If it can be shown that tolerance is not obligatorily MHC restricted, then the pillar of the prevailing paradigm will have fallen. The experiments described here throw into serious doubt the evidence that has been used to conclude that tolerance is obligatorily MHC restricted.

Animals↗
PubMed1992

A method for estimating the uncertainty of future bone mass.

The development of statistical models for estimating fracture probability is a promising method for quantitating and optimizing the clinical utility of bone mass measurements. Earlier models have assumed that future bone mass could be predicted exactly and were, therefore, limited to analyses that assume the loss rate is known in advance. Since bone loss rates may vary over time and cannot be predicted accurately, we have developed a new model, based on empirical data, that estimates the degree of uncertainty associated with predicted bone mass. Without a bone mass measurement, the population mean must be assumed for an individual. For the calcaneus, the standard deviation of the population distribution is about 60 mg/cm2. By measuring bone mass, one can determine how close or far from the mean an individual's true bone mass is, with a standard deviation (SD) of about 3 mg/cm2. Without a subsequent bone mass measurement, our model predicts that the uncertainty (standard deviation) in calcaneal bone mass will increase approximately sixfold (relative to the reproducibility at the initial measurement) over a period of five years for women under age 60, from 3 mg/cm2 to 19 mg/cm2. The five-year increase in uncertainty is approximately fourfold for women over age 60, from 3 to 13 mg/cm2. However, the uncertainty in bone mass for an individual five years after the initial measurement is still only one third to one fifth that of the entire population, and can be reduced to the initial level by obtaining another measurement. Furthermore, the predicted (or measured) values are usually much better estimates of an individual's true bone mass than simply assuming the population average.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

Toddlers' sleep and temperament: reporting bias or a valid link? A research note.

Objective sleep measures derived from a computerized movement detector attached to the child's leg, were obtained for a group of 31 toddlers (mean age: 18.5 months). The monitored sleep parameters were compared with maternal assessment of the child's sleep and her perception of his temperament. The validity of maternal diaries as a measure of the child's sleep was not supported. Nevertheless, a link between both subjective and objective sleep measures with temperament dimensions was indicated. The modest association between sleep and temperament may suggest either a continuity between some aspects of day- and night-time functioning or, alternatively, the influence of the child's sleep behavior in shaping the mother's perceptions of her toddler's temperament.

Child, Preschool↗
PubMed1992

The importance of timing in melatonin administration in a blind man.

An 18-year-old blind man suffered from chronic sleep disturbances associated with daytime fatigue and excessive daytime somnolence. After two unsuccessful treatment regimens with 5 mg and 10 mg melatonin administered at bedtime (2200-2230), a third regimen of 5 mg melatonin administered at 2000 for 3 weeks resulted in a successful resolution of his sleep disturbances. We suggest that the efficacy of melatonin in ameliorating sleep disturbances because of alterations in circadian rhythmicity may be dependent on the time of administration.

Adolescent↗
PubMed1992

Specific reading impairments--are they to be associated with emotional difficulties?

The assumption that specific learning disabilities are not causally related to emotional disturbances is crucial for the cognitive research approaches that endeavor to isolate specific malfunctioning cognitive-computational processes. Because there are conflicting data regarding the emotional status of subjects with learning difficulties, the purpose of this study was the evaluation of the emotional status of subjects with specific learning difficulties in comparison with that of subjects from several relevant control groups. The HSCL-90 profiles of 38 subjects suffering developmental dyslexia, 28 subjects with subjective complaints regarding general concentration and reading comprehension difficulties, and 23 psychiatric patients were compared with those of 44 skilled readers without any known emotional difficulties. All subjects were adolescents and young adults (age range = 15 to 23). A cluster analysis of subjects' HSCL-90 profiles did not reveal any significant differences between subjects with dyslexia and control subjects. Both groups, on the other hand, were easily differentiated from psychiatric patients. Subjects with severe deficits in their ability to remember details of a text, and with subjective complaints regarding concentration difficulties, tended to generate emotional profiles that testify to a high level of anxiety. Although these subjects, as well as individuals with dyslexia, may be regarded at the functional level as inefficient readers, the two groups seem to clearly differ regarding the failure factors that underlie their phenotypic difficulties.

Achievement↗
PubMed1992

Actigraphic measurements of sleep in rheumatoid arthritis: comparison of patients with low back pain and healthy controls.

Actigraphic recordings during sleep were carried out in patients with rheumatoid arthritis (RA), in patients with chronic low back pain, and in healthy controls for 4 consecutive nights. All derived measures of sleep quality showed that the sleep of patients with RA was significantly poorer than controls, while patients with chronic low back pain had sleep quality not significantly different from either group. Polysomnographically defined periodic movements in sleep were significantly related to sleep efficiency in patients with RA. Clinical status in these patients was significantly related to several actigraphic sleep measures.

Arthritis, Rheumatoid↗
PubMed1991

Analysis of Ly5 chromosome 1 position using allelic differences and recombinant inbred mice.

Differences between the mouse Ly5a and Ly5b alleles can be distinguished on the basis of polymerase chain reaction (PCR)-restriction enzyme analysis and differential monoclonal antibody reactivities. To more precisely map the Ly5 gene on the mouse chromosome 1, analytical DNA and protein tests were performed on recombinant inbred strains of mice prepared from SJL/J (Ly5a) and BALB/cke (Ly5b) progenitor strains. Each recombinant inbred strain was characterized to determine whether it carried the Ly5a or Ly5b allele. Both assays, DNA-PCR and protein-immunofluorescence, yielded identical results for each strain examined. Placement of the Ly5 gene with respect to other characterized markers of mouse chromosome 1 for these recombinant inbred mouse strains shows a gene order of Idh-1:Ity:Pep3:[Ly5, Cfh].

Alleles↗
PubMed1991

Effect of pneumonectomy on the remaining lung in dogs.

To determine the magnitude of functional compensation after pneumonectomy and whether compensation is related to maturity of the animal at the time of resection, we performed left pneumonectomy in either adult or 10-wk-old beagles. Studies were performed in adults 7-9 mo after surgery and in puppies 18-23 mo after surgery when the dogs reached full maturity. Results were compared with those in age- and sex-matched unoperated controls. Measurements included pressure-volume relationships, pulmonary hemodynamics, rebreathing studies of lung volume, diffusing capacity and its components, lung tissue volume, and pulmonary blood flow. Computerized-tomographic scans were performed in the puppy groups to determine changes in thoracic shape and size. Morphometric analysis of the lungs was performed under light microscopy. There was partial compensation for loss of one lung by functional improvement in the remaining lung. Compensation was greater in those pneumonectomized as puppies than as adults. Volume of the remaining lung was larger than predicted for a given transpulmonary pressure in both groups. Diffusing capacity, pulmonary capillary blood volume, and lung tissue volume were larger than expected for the normal right lung. After pneumonectomy, compliance of the rib cage was greater in puppies than in adults. Weight of the costal diaphragm was reduced in pneumonectomized puppies. Pulmonary hypertension at rest did not develop, and pulmonary vascular reactivity to hypoxia was unchanged after pneumonectomy in both groups. Significant correlations were obtained between physiological and morphometric measurements.

Age Factors↗
PubMed1991

Sleep-wake cycles in multi-infarct dementia and dementia of the Alzheimer type.

We monitored by actigraphs minute-by-minute activity of 10 patients with multi-infarct dementia (MID), 15 patients with dementia of the Alzheimer type (DAT), and 11 control volunteers for eight consecutive 24-hour periods to assess sleep-wake cycles and sleep quality. MID patients had disrupted sleep-wake cycles associated with decreased sleep quality. In contrast, ambulatory DAT patients maintained a relatively normal sleep-wake cycle that did not differ significantly from controls. There was no correlation between the severity of intellectual deterioration and the degree of sleep-wake cycle disintegration in either group of dementia patients.

Aged↗
PubMed1991

Circadian rhythms in 6-sulphatoxymelatonin and nocturnal sleep in blind children.

This article describes the relationship between melatonin secretion and sleep quality and subjective complaints about sleep in totally blind children. Eleven boarding-school children (mean age 15.2 years) participated. The major urinary melatonin metabolite 6-sulphatoxymelatonin (aMT6s) was measured five times a day for 48 h. Sleep-wake cycles were recorded by continuous actigraphic recordings during the same time period. Results showed that delayed secretory peaks in aMT6s were significantly associated with disturbed nocturnal sleep and with complaints about morning fatigue.

Adolescent↗
PubMed1991

Patient attitudes and knowledge about HIV infection and AIDS.

BACKGROUND: Family physicians are caring for an increasing number of those with human immunodeficiency virus (HIV) infection, those at risk, and those concerned about HIV disease. METHODS: A questionnaire survey of attitudes and knowledge about HIV infection was conducted in 430 patients in three family practices in Monroe County, NY. RESULTS: The majority of those surveyed had worried about catching HIV and had spoken with friends or relatives about HIV. Approximately 7.5% had had the HIV test. Approximately half of all the respondents expressed a desire to discuss HIV-related issues with their family doctor; however, less than 8% had actually done so. The majority of the respondents believed their family doctor was competent to answer questions about HIV disease. Furthermore, the majority were well informed about the modes of transmission of HIV. Many of the respondents were unsure of the lack of risk from casual contact, however, and whether acquired immune deficiency syndrome (AIDS) is incurable at the present time. CONCLUSIONS: Family physicians need to take a more active role in educating and counseling patients about HIV disease.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Actigraphic home-monitoring sleep-disturbed and control infants and young children: a new method for pediatric assessment of sleep-wake patterns.

Two studies were conducted to evaluate actigraphic home-monitoring for the assessment of infants' and children's sleep patterns. In the first study, 11 children (aged 12 to 48 months) were monitored in the laboratory by traditional polysomnography and by actigraphy for one night. Actigraphic automatic sleep-wake scorings were compared with those of the polysomnograph; total agreement rate was 85.3%. In the second study, sleep patterns of 63 sleep-disturbed and 34 control healthy children (aged 9 to 27 months) were compared. These children were home-monitored by actigraph for a mean of 4.45 nights (total 482 nights). Actigraphic data were analyzed by an automated scoring procedure. Sleep quality of the sleep-disturbed children, measured by actigraphically derived sleep percent and number of longer-than-5-minute wakings, was significantly lower than that of the control subjects (P less than .0001). Sleep measures showed significant night-to-night stability in both groups. The stability of specific measures and their age trends were different between the groups. Actigraphic sleep measures alone could discriminate between sleep-disturbed and control children with a highly correct assignment rate of 79.4% and 91.2%, respectively.

Age Factors↗
PubMed1990

Evaluation of selective liver denervation methods.

This study compares four methods of hepatic denervation and defines the rate and physiological significance of reinnervation. Five groups of rats were prepared: 10 underwent orthotopic liver transplantation. In nine rats a 90% aqueous phenol solution was applied circumferentially to the portal vein. Thirteen rats underwent microsurgical denervation; 28 received different doses of 6-hydroxydopamine (6-HODA) administered as a single intraportal injection [50 (n = 10), 75 (n = 6), and 100 mg/kg (n = 6)]. Twelve rats were studied as controls. Rats were killed 1, 4, and 8 wk after surgery to determine liver tissue content of norepinephrine (NE). Changes in mean arterial pressure (MAP) in response to hepatic nerve stimulation, which was supramaximum in intensity and frequency, were measured before rats were killed. NE content in controls ranged from 121 to 204 ng/g and MAP increased by 30-38 mmHg after electrical stimulation. At 1, 4, and 8 wk after treatment the liver NE content was less than 1, 2.3, and 20.2 ng/g in the transplant group; less than 1, 2.7, 4.1 ng/g in the phenol group; and 17.2, less than 1, and 3 ng/g in the surgically denervated group. In the 6-HODA group, values were 18.9, 47, and 61.5 ng/g (50 mg/kg); 5.7, 20.2, and 15 ng/g (75 mg/kg); and 7.7, 2.5, and 17.5 ng/g (100 mg/kg). When the level of NE was undetectable, MAP increase after stimulation was 0-18% that of controls. When NE content was 15-23% of normal, MAP increased 49-62% regardless of the denervation technique.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗