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Biomedical subjects

J N Hall

Publications and source records attributed to J N Hall.

At least 19 recordsLinked to original sources
PubMed1999

Response to 45 degrees head-down tilt as measured by organ weight/body weight ratios and spiral computed tomography.

BACKGROUND: Exposure to microgravity or simulated microgravity causes significant shifts in body fluids which may initiate physiological adaptations to the microgravity stressor. It is imperative to understand the physiological adaptations to microgravity in order to develop appropriate countermeasures to the deleterious aspects (i.e., muscle and bone wasting) of long-term spaceflights. HYPOTHESIS: The significant shifts in body fluids by 45 degrees head-down tilt can be measured by changes in organ weight/body weight (OW/BW) ratios and non-invasively by spiral computed tomography. METHODS: In a previous study (14), rats were weighed and exposed to either 45 degrees head-down tilt (45HDT) or a prone control position for one of the following experimental times: 0.5 h, 1 h, 2 h, 4 h, 8 h, or 24 h. A radioactive tracer was injected intramuscularly immediately prior to the start of the experimental time periods. At the end of the experiment, the major organs were harvested, weighed, and measured for gamma radiation levels. We used the organ weights from this previous study to calculate OW/BW ratios for the present study. Additionally, in the present study, rats in the 14-d experimental groups were weighed, lightly anesthetized to facilitate placement in the 45HDT position, and placed in a specially designed 45HDT cage (45HDT group) or left unrestrained in the cages (control group). At the end of the 14-d experimental time period, the rats were anesthetized and their lung densities measured with spiral computed tomography. RESULTS: The OW/BW ratios for the liver, kidneys, and spleen of 24 h 45HDT rats were significantly lower (p<0.05) than control values while at 1 h the 45HDT rats had a higher kidney OW/BW ratio. Lung density from the 14-d 45HDT rats was 24.4% greater than control rats' values. CONCLUSIONS: The physiological change due to the 45HDT position to simulate microgravity begins as early as 1 h, and the kidney appears to be the first organ affected. Spiral computed tomography may offer a viable method of non-invasively measuring organ densities in the 45HDT model. The OW/BW data generated in the present study does not correlate with the changes in radioactive tracer distribution data from our previous study.

Adaptation, Physiological↗
PubMed1997

Changes in radioactive tracer distribution in rats after 24 hours of 45 degrees hind limb unweighting.

INTRODUCTION: Changes in radioactive tracer distribution were examined in rats after exposure to a simulated microgravity model of 45 degrees head down tilt (45HDT) or 45 degrees hind limb unweighting (45HU) for up to 24 h. METHODS: Rats were randomly assigned to either 45HDT (or 45HU) experimental groups or control groups for each time point of 0.5 h, 1 h, 2 h, 4 h, 8 h, or 24 h. The 0.5-h through 8-h experimental rats were anesthetized and placed head-down on a ramp at 45 degrees, while control rats were placed in a prone position. Non-anesthetized rats in the 24-h experimental group were tail-suspended at 45 degrees, while control rats were allowed unrestrained movement. Technetium-labeled diethylenetriamine pentaacetate (99mTcDTPA, physical half-life of 6.02 h, MW = 492 amu) and indium-labeled diethylenetriamine pentaacetate (111In DTPA, physical half-life of 3.5 d, MW = 545 amu) were used to measure body organ distributions of the radioactive tracers at the 0.5-h-8-h and 24-h time points, respectively. Major organs were harvested after each time period and measured for radioactive counts. Light and electron micrographs were examined. RESULTS: Mean 111InDTPA counts for the lungs, kidneys, and brains of the 24 h 45HU groups were significantly higher than control counts. Light and electron microscopy demonstrated the development of pulmonary edema in the alveolar septal areas after 2 h of 45HDT, and a shift in edema to the pulmonary airways and pulmonary arteries after 24 h of 45HU. CONCLUSIONS: Pulmonary edema development, accompanied by a significant increase in 111InDTPA lung, kidney, and brain counts in the 24-h 45HU groups, suggests vascular injury in the microcirculation of these organs.

Animals↗
PubMed1993

Effectiveness of combined triazolam-behavioral therapy for primary insomnia.

The authors examined sleep improvement in subjects with primary insomnia who received triazolam plus behavioral therapy (N = 8) or triazolam plus sleep-related information (N = 7). At follow-up, total sleep and restedness in the morning showed greater improvement with combined triazolam-behavioral therapy and returned toward baseline in the control subjects.

Adult↗
PubMed1991

Effects of intravenous and aerosolized arachidonic acid on alveolar epithelial permeability in rabbits.

To determine whether arachidonic acid (AA) alters alveolar epithelial permeability, we studied the effect of both continuous intravenous and aerosolized AA on clearance of [99m]Tc-DTPA from lung to blood in rabbits. Although intravenous AA increased prostacyclin production and aerosolized AA decreased systemic blood pressure, neither continuous intravenous nor aerosolized AA augmented alveolar epithelial permeability.

Aerosols↗
PubMed1990

Probability modelling of a surgical probe for tumour detection.

Probability functions for the output counts from a radiation detector probe are needed to implement Bayesian detection strategies or to assess performance of the probe. This paper presents methods for simulating a surgical probe designed for tumour detection to obtain statistical information for modelling probability functions of output data. Statistical models of pharmaceutical uptake in normal organs and tumours were estimated from animal and human data, and these models were combined with a digitised human torso phantom to create a large set of simulated patients. With the simulated patients and with a spatial map of the probe response, computer simulations of intraoperative probe measurements provided a large set of simulated probe data. Probability models derived from these data using maximum-likelihood methods helped to formulate the detection strategy and to evaluate the performance of the surgical probe.

Computer Simulation↗
PubMed1990

Towards a psychology of caring.

An increasing awareness of the chronicity of many conditions, and reservations about the appropriateness of 'treatment' models of intervention, together encourage a positive and careful psychological examination of caring. A psychology of caring must be relevant to care by families in domestic settings as well as to more specialized and professionally staffed settings. The relationship between explicit and implicit philosophies of caring, the goals and objectives of caring, the care practices themselves, and the emotions and feeling associated with care, need to be carefully examined. As applied psychologists, there are many detailed aspects of care we could examine, including the nature of need, vigilance, risk taking, the elicitation of care, identifying the motivation of potential carers, and care evaluation. Much of the literature on caring is derived from organizational and sociological perspectives: there is room for, and a need for, a specifically psychological perspective as well.

Affect↗
PubMed1989

A comparison of practices, attitudes and interactions in two established units for people with a psychiatric disability.

This study evaluates and compares aspects of residential care in a community hostel setting and a hospital setting for people with a psychiatric disability. The clients were assessed to establish their level of general functioning, the comparison indicating there was no significant difference between the two groups on the measure used. A previously published protocol was used as a method of comparing the units. The findings indicated that the hospital unit was more individually orientated both in practices and staff attitudes, and had staff who were more optimistic about clients' potential accomplishments. No differences were found between perceived involvement of staff in decision making, or staff resident interactions. These findings have implications for the 'Care in the Community' movement, as they indicate that the nature of a service is as important as its location. They suggest that the relocation of services to the community in itself will not automatically overcome some of the difficulties associated with institutional care.

Adult↗
PubMed1989

Whole-body lymphangioscintigraphy: preferred method for initial assessment of the peripheral lymphatic system.

In 20 patients with congenital and acquired lymphedema in either upper or lower extremities and in four patients without extremity edema, human serum albumin labeled with technetium-99m was injected intradermally into a digital web space of the hand or foot. With a digital gamma camera that permitted a "sweep" of the torso, serial extremity and whole-body lymphagioscintigraphy (LAS) of the peripheral lymphatic system was performed. In 11 patients with acquired lymphedema, a well-defined obstructive pattern was seen, characterized by discrete peripheral lymphatic trunks, delayed or absent depiction of regional nodes, and delayed but extensive soft-tissue tracer extravasation. Five of nine patients with congenital lymphedema showed hypoplasia characterized by poorly defined lymphatic trunks, delayed depiction of regional nodes, and early and extensive extravasation of tracer. The other four patients showed aplasia, with absence of trunks, no depiction of nodes, and little or no tracer extravasation. LAS is technically simple to perform and requires no special training. Radiation exposure is minuscule, and the procedure is safe and without apparent side effects. For these reasons, whole-body LAS should be the preferred method for the initial assessment of congenital or acquired lymphedema.

Adolescent↗
PubMed1988

Splenic salvage quantified by uptake of heat-damaged radiolabeled red blood cells. Experimental and clinical studies.

We evaluated a noninvasive radionuclide technique to quantify splenic trapping function, which is a key step in the disposition of blood-borne particulates such as poorly opsonized encapsulated microorganisms implicated in hyposplenic fulminant sepsis. Using computerized external gamma imaging, the percentage of splenic uptake of heat-damaged radiolabeled red blood cells was determined in adult Sprague-Dawley rats with eutopic (partial splenectomy) or ectopic (single or multiple autotransplantation) remnants or whole spleens, and in 14 patients with either an intact spleen or splenic remnants after treatment for trauma or hypersplenism. The masses of both eutopic and ectopic remnants correlated directly with the percentage of heat-damaged red blood cell uptake, but the percentage of uptake per gram was higher in eutopic remnants, paralleling more vigorous compensatory growth. In patients, the percentage of heat-damaged red blood cell uptake by remnant spleens was similar to that seen in the rats and, in addition, was supernormal in those with congestive splenomegaly. This noninvasive technique both provides a vivid biplanar image and quantifies blood-borne particle trapping, which is a key splenic function. A heat-damaged red blood cell uptake of less than 15 percent after splenic salvage suggests marginal splenic performance and continued vulnerability to overwhelming sepsis.

Animals↗
PubMed1988

REHAB: a new assessment instrument for chronic psychiatric patients.

The renewed interest in the care and treatment of chronic psychiatric patients has led to an awareness of the need for improved assessment methods for this group. This article describes the development of REHAB, a behavior rating scale for use with people with chronic psychiatric disability, which has been carefully designed with respect to content, format, and ease of use. The article also draws together the various factor-analytic, reliability, validity, and sensitivity-to-change studies that provide the basic psychometric evidence for the scale's value. REHAB is presented as an integrated package of materials with special attention paid to training of raters and simplicity of interpretation. It has been used for a variety of different assessment purposes, in both research and clinical settings.

Deinstitutionalization↗
PubMed1980

Ward rating scales for long-stay patients: a review.

Twenty-nine published ward rating scales for long-stay psychiatric patients are reviewed according to a standard set of criteria. Attention is paid to details of the rating setting, the rating procedure, and scale construction and evaluation, and some detailed recommendations are made. Only 4 scales meet a subset of 5 minimal criteria.

Humans↗
PubMed1979

Cobalt-57 bleomycin for imaging head and neck tumors.

Cobalt-57 bleomycin imaging was performed in 11 patients with a history of head and neck cancer. Clinical and scan findings concurred on the presence and extent of tumor in 9 patients (82%); tumor was present in 7 and absent in 2 of the 9. In 2 patients (18%) the scan demonstrated tumor in the neck but failed to show metastatic sites. Cobalt-57 bleomycin images were of good technical quality, with remarkably low background activity at 24 hours after administration. Cobalt-57 bleomycin imaging appears to be a promising technique for evaluating patients with head and neck tumors.

Adult↗