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Biomedical subjects

R K Jones

Publications and source records attributed to R K Jones.

At least 19 recordsLinked to original sources
PubMed1990

Polysomnography methods and interpretations.

As the field of sleep disorders medicine continues to mature, appropriate diagnostic techniques are becoming properly defined and standardized. This article focuses principally upon diagnostic testing for sleep apnea, although other sleep disorders are discussed briefly. When interpreting a polysomnogram, one must consider a number of complex variables. A critical discussion of the methods for adequately measuring these variables is provided together with guidelines for appropriate interpretation.

Circadian Rhythm↗
PubMed1989

Talc deposition and effects after 20 days of repeated inhalation exposure of rats and mice to talc.

The relationship between the inhalation exposure concentration of talc and the resulting lung burdens and histologic lesions was studied using groups of 20 F344/Crl rats and 20 B6C3F mice (10 male and 10 female) exposed to one of three concentrations of asbestos-free talc for 6 hr/day, 5 days/week for 4 weeks. Controls were exposed to filtered air using the same schedule. The pulmonary retention of talc and the development of pulmonary pathology were evaluated. The mass median aerodynamic diameter (MMAD) of the talc aerosol was 3.0 microns with a geometric standard deviation (sigma g) of 1.9. The mean exposure concentrations for rats were 0, 2.3, 4.3, and 17 mg talc/m3. Lung burdens in rats averaged 0, 0.07, 0.17, and 0.72 mg talc/g lung after the 20-day inhalation exposure; thus, the amount retained in the lung per unit of exposure concentration increased with increasing concentration. Mean exposure concentrations for the mice were 0, 2.2, 5.7, and 20.4 mg of talc/m3, which resulted in lung burdens of 0, 0.10, 0.29, and 1.0 mg talc/g lung; thus, the relationship between exposure concentration and the amount retained in the lung was approximately constant. Lung burdens from this study were used to project lung burdens that would result from longer exposures of rodents and man. No clinical signs were observed in the rats or mice prior to sacrifice 24 hr after the last exposure day. Histologic alterations in lung tissue consisted of only a modest, diffuse increase of talc-containing, free macrophages within alveolar spaces in both rat and mouse groups exposed to the highest level of talc for 20 days. A model simulating chronic talc inhalation exposure of rats and mice predicted lung burdens of 2-3 mg talc/g lung (wet wt) if animals were exposed to 17 mg talc/m3 for 2 years, and deposition and clearance of talc were unchanged by continued exposure. A potential limitation in this modeling is that if clearance of talc is delayed by continued exposure, the accumulated talc lung burdens would be higher than those projected by the simulation model. Humans exposed to aerosols of respirable talc are projected to accumulate much higher lung burdens than would occur in rodents exposed to the same aerosol, because humans have a higher estimated deposition fraction and slower estimated clearance of the deposited talc dust. Equilibrium lung burdens of greater than or equal to 2 mg talc/g lung were predicted for human exposures at or near the TLV for talc.

Aerosols↗
PubMed1989

How is a trumpet known? The "basic object level" concept and perception of musical instruments.

What are the object properties that serve as a basis for the musical instrument classification system, and how do general and specific experience affect knowledge of these properties? In the first study, the multimodal quality of properties underlying children's and adults' perception was investigated. Subjects listened to solos and identified instruments producing the sounds. Even children who did not have experience with all the instruments correctly identified the family of instruments they were listening to. The hypothesis of the second study, that musical instrument families function as a "basic level" in the instrument taxonomy, was confirmed. Variation in the basic level with varying expertise was documented in the third study with musicians. In the fourth study, children and adults identified the source of sounds from unfamiliar objects, Chinese musical instruments. It is suggested that the concept of affordances may be relevant for understanding the importance for behavior of different levels of abstraction of category systems.

Adult↗
PubMed1988

Response of rodents to inhaled diluted diesel exhaust: biochemical and cytological changes in bronchoalveolar lavage fluid and in lung tissue.

The effect of long-term (24 months) inhalation of diesel exhaust on the bronchoalveolar region of the respiratory tract of rodents was assessed by serial (every 6 months) analysis of bronchoalveolar lavage fluid (BALF) and of lung tissue from F344/Crl rats and CD-1 mice (both sexes) exposed to diesel exhaust diluted to contain 0, 0.35, 3.5, or 7.0 mg soot/m3. The purpose of the study was twofold. One was to assess the potential health effects of inhaling diluted exhaust from light-duty diesel engines. The second was to determine the usefulness of BALF analysis in detecting the early stages in the development of nononcogenic lung disease and differentiating them from the normal repair processes. No biochemical or cytological changes in BALF or in lung tissue were noted in either species exposed to the lowest, and most environmentally relevant, concentration of diesel exhaust. In the two higher levels of exposure, a chronic inflammatory response was measured in both species by dose-dependent increases in inflammatory cells, cytoplasmic and lysosomal enzymes, and protein in BALF. Histologically, after 1 year of exposure, the rats had developed focal areas of fibrosis associated with the deposits of soot, while the mice, despite a higher lung burden of soot than the rats, had only a fine fibrillar thickening of an occasional alveolar septa in the high-level exposure group. Higher increases in BALF beta-glucuronidase activity and in hydroxyproline content accompanied the greater degree of fibrosis in the rat. BALF levels of glutathione (GSH) and glutathione reductase activity increased in a dose-dependent fashion and were higher in mice than in rats. Lung tissue GSH was depleted in a dose-dependent fashion in rats but was slightly increased in mice. This depletion may have played a role in the greater fibrogenic response observed in rats. Other tissue changes in enzymatic activity were small compared to changes observed in BALF. The exposure did not increase the cytochrome P-450 content of the lung in either species. The results suggest that, for the noncarcinogenic health effects reported in this paper, there is a threshold of exposure below which adverse effects were not observed. This threshold was well above environmentally relevant levels of diesel exhaust but may be in the range of some occupational exposures. The analysis of BALF proved a useful adjunct to the chronic toxicity study to quantitate the inflammatory changes accompanying the development of pulmonary disease.

Animals↗
PubMed1987

Diesel exhaust is a pulmonary carcinogen in rats exposed chronically by inhalation.

Male and female F344 rats were exposed 7 hr/day, 5 day/week for up to 30 months to automotive diesel engine exhaust at soot concentrations of 0.35, 3.5, or 7.0 mg/m3 or were sham-exposed to clean air. Rats were terminated at 6-month intervals to measure lung burdens of diesel soot and for histopathology. Other rats either died or were terminated after 30 months of exposure. Lungs were fixed, sectioned into 3-mm slices, and examined by a dissecting microscope to detect tumors. Lesions were stained and examined by light microscopy. Survival and body weight were unaffected by exposure. Focal fibrotic and proliferative lung disease accompanied a progressive accumulation of soot in the lung. The prevalence of lung tumors was significantly increased at the high (13%) and medium (4%) dose levels above the control prevalence (1%). Four tumor types, all of epithelial origin, were observed: adenoma, adenocarcinoma, squamous cyst, and squamous cell carcinoma. Logistic regression modeling demonstrated a significant relationship between tumor prevalence and both exposure concentration and soot lung burden. These results demonstrate that diesel exhaust, inhaled chronically at a high concentration, is a pulmonary carcinogen in the rat.

Adenocarcinoma↗
PubMed1986

Deposition, metabolism, and excretion of 1-[14C]nitropyrene and 1-[14C]nitropyrene coated on diesel exhaust particles as influenced by exposure concentration.

Nitrated polycyclic aromatic hydrocarbons (nitro-PAH) have been detected in the environment, originating from sources such as diesel exhaust emissions and coal combustion fly ash. 1-Nitropyrene (NP) is a predominant mutagenic and carcinogenic nitro-PAH found in diesel exhaust emissions. Since inhalation of NP is a likely route of exposure in humans, it is important to determine the biological fate of inhaled NP both in its pure form and associated with particles. The purpose of this study was to determine the disposition of NP aerosols inhaled by rats. The studies described in this paper were designed to determine the deposition of [14C]NP over a range of exposure concentrations, identify the pathways and half-times for excretion of absorbed NP, and determine the distribution of inhaled NP and metabolites in tissues. Male F344 rats were exposed nose only to various concentrations of NP and NP coated on diesel exhaust particles (50-1100 ng/liter). The results indicate that, over the range of concentrations tested, pathways for excretion of [14C]NP equivalents in urine and feces were independent of the exposure concentration of NP, whether in its pure form or associated with diesel exhaust particles. In all cases, fecal excretion was the major route of elimination of [14C]NP equivalents, with about 2 times more excreted by this route than by urine. The fractional deposition of [14C]NP in the respiratory tract did not appear to be dependent on exposure concentration. Half-times for elimination of 14C in urine and feces were about 15 to 20 hr. In all exposures, 14C was widely distributed in the tissues examined. Analysis of the tissues for NP and its metabolites indicated that within 1 hr after exposure, greater than 90% of the 14C was NP metabolites. Lungs of rats exposed to [14C]NP coated on diesel exhaust particles contained nearly 5 times more 14C than lungs from rats exposed to pure aerosols of [14C]NP (148 vs 29 pmol/g lung) within 1 hr after exposure. This difference was increased to 80-fold at 94 hr after exposure (80 vs 1 pmol/g lung). Long-term clearance half-times of 14C from various tissues were similar. The results demonstrate that particle association of NP significantly alters the biological fate of inhaled NP.

Aerosols↗
PubMed1985

Health effects of diesel exhaust. A contemporary air pollution issue.

Extracts of diesel exhaust particles are mutagenic in bacterial and mammalian cell assays; they contain hundreds of identifiable organic compounds, some of which are known mutagens and carcinogens. The particles are readily respired and about 20% to 30% of them are deposited in the pulmonary region, where they are retained for long periods. At low diesel exhaust concentrations, typical of those likely for human exposure, particle deposition and clearance rates are essentially normal and particle concentrations in the pulmonary region are expected to remain quite low. At very high concentrations of diesel exhaust, clearance processes may be overwhelmed and lung burdens of particles may continue to increase over long periods. Evidence from laboratory animals suggests that pulmonary injury and reduced respiratory function would occur in humans at these high concentrations. Epidemiologic data and laboratory studies appear to indicate that the human lung cancer risk from exposure to diesel exhaust would be quite low, even if use of diesel vehicles increased substantially.

Animals↗
PubMed1985

Effects of inhaled diesel exhaust on immune responses after lung immunization.

The inhalation of diesel exhaust particles and the accumulation of these particles in the lung-associated lymph nodes could alter the development of immune responses after lung immunization. To study this possibility, Fischer 344 rats and CD-1 mice were exposed to three levels of diesel exhaust (nominal concentration--7000, 3500, or 350 micrograms particles/m3). Chamber controls and exposed animals were immunized by intratracheal instillation of sheep red blood cells (SRBC) after 6, 12, 18, and 24 months of exposure. The number of anti-SRBC IgM antibody-forming cells (AFC) in the lung-associated lymph nodes and spleen was evaluated after immunization. The lung-associated lymph nodes from rats and mice exposed to the high levels of diesel exhaust were black with accumulated diesel particles, and the number of lymphoid cells was significantly elevated at each sacrifice time, while rats exposed to the medium level of diesel exhaust also had elevated numbers of cells in these tissues at 12, 18, and 24 months of exposure. The total number of AFC in the lung-associated lymph nodes was significantly elevated (p less than 0.05) in rats exposed to medium and high levels of diesel exhaust, but no significant effects were observed in exposed mice. Data expressed as AFC/10(6) lymphoid cells in rats and mice, and the level of specific IgM, IgG, or IgA antibody in rat sera were not significantly altered. We conclude that the increased cellularity, and the presence of diesel particles in the lung-associated lymph nodes, had a minimal effect on the immune and antigen filtration functions of these tissues.

Animals↗
PubMed1979

Treatment outcome for alcoholics as a function of therapeutic effort.

The association between therapeutic effort measured in terms of reimbursements for services and several treatment outcome variables was examined. A sample of clients regarded as definitely alcoholic was grouped into five categories according to the amount of money reimbursed for treatment in a fee-for-service arrangement. A systematic positive relationship was found between the amount of treatment measured in dollars and therapeutic outcome measured by remission rate and income. The data suggest that there may be an optimal cutoff for resource investment, above which no further treatment gains are achieved. Such information can provide a basis for program management decisions and suggests important implications for assumptions regarding alcoholism.

Adult↗
PubMed1978

A distinctive characteristic of pictorial perception: the zoom effect.

To investigate the role of flat surface information for the plane of projection in pictorial perception, three studies were designed in which varying amounts of such information were made available to adult subjects. The first study tested preferences for true or modified linear perspective under conditions of presence or absence of surface texture cues for the plane of projection. In the second and third studies, the absence of texture cues for the plane was coupled with the addition of motion parallax and binocular information respectively. It was found that adults showed a consistent preference for parallel perspective in pictures when the flat-surface information was provided either by visible texture or by motion parallax; but no consistent preference for either true or modified perspective in the absence of all three sources of flatness information or when the flat surface information was given only by binocular cues in the absence of visible surface texture of visible surface texture or head motion.

Cues↗
PubMed1978

Gasoline vapor exposure during bulk handling operations.

The survey evaluated gasoline vapor concentrations in the employees, breathing zone at five bulk handling facilities. Charcoal tube samples were analyzed by a special GLC/flame ionization/flasher technique which coupled with a computer program identified up to 142 constituents. A time-weighted limit of 240 ppm/10-hour day was only exceeded for five percent of the time at one location.

Air Pollution↗
PubMed1977

Towards a definition of living systems: a theory of ecological support for behavior.

It is proposed that the Darwinian theoretical approach and account of living systems has not yet been clearly given. A first approximation to this is attempted, focussing on behavior in evolving environments. A theoretical terminology is defined emphasizing the mutuality of organism and environment and the existence of biologically theoretical entities.

Animals↗
PubMed1977

Topographic impairment of night vision related to exercise.

We observed impaired night vision in the lower visual fields of long distance runners. We reduplicated our field observations by studying four vigorously exercising men, aged 26 to 52 years, under controlled laboratory conditions. Results of our observations showed impaired night vision did occur in the inferior visual fields of all four subjects.

Adult↗