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Biomedical subjects

R F Dodson

Publications and source records attributed to R F Dodson.

At least 55 records · Page 3Linked to original sources
PubMed1988

Use of a semi-automatic image analyser in directly determining mean linear intercepts.

A direct method for measuring mean linear intercepts (Lm) was tested. A semi-automatic image analysis system (Zeiss, Videoplan) and an overlay of parallel lines were employed in determining Lm in intravascularly perfused guinea pig lungs. Actual chord lengths were recorded and the data was immediately processed. Spurious intercepts and manual data manipulation were avoided. This direct method of measurement proved to be simple, rapid and very consistent across three trials for each animal. Analysis of variance revealed no significant differences between the three trials (p = 0.22).

Animals↗
PubMed1987

Cerebromicrovascular endothelial permeability. In-vitro studies.

Permeability of cerebromicrovascular endothelium has been investigated in a new model of cultured cells. The endothelial cells are grown on dextran microcarriers and constitute a barrier for trypan blue (TB) binding to the dextran beads. Changes in the permeability of microcarrier-cultured endothelium have been investigated during the exposure of cells to arachidonic acid or substances involved either in arachidonate metabolism or stimulation of cAMP. The results demonstrate enhanced TB passage through the endothelial barrier during exposure to high concentrations of arachidonic acid and indomethacin, but not to ibuprofen. The effect of indomethacin could be prevented by pretreatment with dexamethasone. Dexamethasone alone did not influence the barrier. Forskolin, a drug which stimulates the catalytic unit of adenylate cyclase, did not affect the endothelial permeability to TB. These findings support the contention that substances derived from a disturbed cellular membrane contribute to the altered blood-brain barrier function found under pathological conditions.

Animals↗
PubMed1987

Comparative efficiency of Nuclepore filters of various pore sizes as used in digestion studies of tissue.

Some of the widely used techniques employed in assessing asbestos load in lung tissue include the use of digestion techniques, in which particulates are entrapped on a filter surface. However, the actual filtering efficiency of various pore sizes as applicable to collecting fibrous material has not been tested. The present study evaluates such filtration efficiency by using a series of back-to-back filters of various sizes. It was confirmed that fibers pass through the pores and that with the larger pore sizes an appreciable loss of small fibers can occur. It is suggested that a filter with 0.2-micron pore size offered a reasonable compromise for both filtration efficiency as well as sufficiently rapid filtration rates for most studies.

Asbestos↗
PubMed1986

An ultrastructural study of acute and long-term lung response to commercial diatomaceous earth.

The acute pulmonary effects of intratracheally instilled particles of calcined diatomaceous earth were found to include a pronounced neutrophil invasion of the bronchioles by 4 h after exposure which remained well developed through 1 day post-exposure. The number of macrophages and neutrophils in the alveoli continued to increase through 1 day post-exposure and remained above control values through 7 days post-exposure. The number of macrophages, many of which contained diatomaceous earth, remained elevated for the duration of the experiment. Most phagocytosis of the particles was carried out by macrophages, with minor participation by neutrophils. Many of the reactive macrophages in the groups with post-exposure periods longer than 2 h showed various types of pathological alterations. A few particles were found in type I epithelial cells. Oedematous changes were observed in some type I epithelial cells and proliferation of type II epithelial cells was evident in some alveoli, particularly those near the respiratory bronchioles. Mild diffuse fibrosis was first observed at 6 months and was still present at 15 months but remained confined to the areas containing the diatomaceous earth.

Animals↗
PubMed1986

Solar elastotic bands of the forearm: an unusual clinical presentation of actinic elastosis.

Actinic damage of dermal tissues produces several distinct clinical patterns. Three patients are described as having discrete, soft, cordlike bands on the forearms that extend from dorsal areas of actinic damage and senile purpura to greatest prominence in flexural regions with less solar damage. Histochemical analyses and light and electron microscopy studies of the plaques showed changes consistent with solar elastosis. The clinical variants of actinic elastosis and the possible origins of the abnormal elastic fibrils found in the dermis of chronically sun-damaged skin are discussed. Solar elastotic bands are an unusual form of actinic degeneration.

Aged↗
PubMed1985

Early response of the visceral pleura following asbestos exposure: an ultrastructural study.

The acute in vivo response of the visceral pleura following intracheal instillation of amosite asbestos was examined by light microscopy and by transmission and scanning electron microscopy in the guinea pig model. Asbestos fibers were observed close to the pleura in all time periods but were never found within the pleura or subpleural regions proper. Thus, pleural changes occurred in the absence of direct fiber contact. Morphological changes in the pleural and subpleural areas were seen as early as 2 h after exposure and were associated with pathological alterations of the underlying parenchyma. The normally squamous mesothelial cells became pleomorphic in experimental animals, ranging from slightly cuboidal, to protruding "columnar-like" cells, to more bizarre forms. While many organelles remained unaltered, an increase in vacuolization in portions of the pleura indicated localized and advanced intracellular responses. Beginning at 4 h postexposure, varied numbers of particulate-free macrophages were seen on the pleural surface, and were considered an extension of the inflammatory response occurring in the underlying parenchyma. Early proliferation of the mesothelial cells, in limited areas of the pleura, and cytoplasmic extensions into the pleural space were also observed. Distortions of the basal lamina and smooth-muscle bundles accompanied the morphological changes in the pleural cells. A trend toward normality was observed in the longer time frames, but some areas of pleural change persisted through 3 mo postexposure.

Animals↗
PubMed1985

A comparison of the ferruginous body and uncoated fiber content in the lungs of former asbestos workers.

Tissue samples from 12 former asbestos workers were digested and analyzed for ferruginous body and uncoated fiber populations. It was noted that there were large numbers of nonasbestos fibers in each of the samples. In some samples, these fibers constituted over 80% of the total uncoated fibers, and they could greatly influence the data as to asbestos content of the tissue unless differentiated by light and electron microscopic techniques, such as X-ray energy-dispersive analysis. There were great variations in the numbers of uncoated fibers per ferruginous body between the individual workers. The digested samples from lungs of 2 workers yielded no ferruginous bodies by light microscopy, even though these samples by electron microscopy contained respective loads of 780,000 and 1.2 million uncoated amphibole fibers per gram. Light microscopy examination of adjacent tissues confirmed mild fibrosis in both workers. Ferruginous bodies serve as a general marker for asbestos exposure. However, our data suggest that their absence in tissue with interstitial fibrosis from a worker with previous occupational exposure may not be sufficiently conclusive to rule out asbestos-induced disease. Rather, as shown by our data, individual exceptions may require correlated analysis by analytical electron microscopy in order to define particulate load and support the diagnosis of the disease.

Asbestos↗
PubMed1985

A scanning electron microscopic study of the early response of lung tissue to amosite asbestos exposure.

The early response of the lung to a single exposure of amosite asbestos was examined via scanning electron microscopy and correlated light microscopy in the guinea pig model. At 2 h post-exposure, lesions consisted of discrete areas of atelectasis with influx of neutrophils and macrophages. Free asbestos fibres were evident in affected areas. By 4 h post exposure, affected regions were more extensive with phagocytic cell numbers increased both in reactive sites and in adjacent tissue. By 1 day post-exposure, the inflammatory response was well developed and encompassed wide areas of the lung. Activated phagocytes were congregated in atelectatic regions and on blood vessel walls. Numerous macrophages were present even in alveoli distant to reactive loci. The 6 day and 12 day time frames marked a subsiding of the inflammatory response in which macrophages outnumbered PMNs in the comparably fewer reactive areas. There was a notable decrease both in marginated leucocytes and in accumulations of phagocytes in tissue adjacent to affected regions.

Acute Disease↗
PubMed1985

Ferruginous body formation on a nonasbestos mineral.

Tissue from a lung biopsy specimen was submitted for electron microscopy and x-ray energy-dispersive analysis of ferruginous bodies. The presence of these entities had been used as a factor in concluding an asbestos-related tissue response. A 62-year-old man had worked for over 25 years in an iron reclamation and manufacturing facility that had no known sources of asbestos in the work environment. He had no history of recurrent respiratory problems. Combined studies in tissue sections as well as on digested specimens revealed that the core of a majority of the ferruginous bodies was an iron-rich fiber. The source of the fibers was traced to a material used in packing and insulation of the metal during the tempering process. While there is a widespread regional potential for exposure in both environmental and occupational settings, the question as to whether the dust is actually a health hazard or more of a nuisance pollutant remains unanswered. It is evident, however, that the fibrous mineral should be recognized as a stimulus for ferruginous body formation in humans.

Asbestosis↗
PubMed1984

Asbestos content in lungs of occupationally and nonoccupationally exposed individuals.

Previous reports have indicated that a majority of the population has asbestos bodies within their lungs. These studies generally have been carried out using cohorts from urban environments. The present study compares the asbestos body levels from three unique cohorts: (1) a nonoccupationally exposed group from a large urban environment having a relatively low asbestos content, (2) patients with lung cancer from a nonurban setting, and (3) amosite asbestos workers, who worked and lived in a rural setting. The number of asbestos bodies in both the urban nonoccupationally exposed group and the patients with lung cancer was generally found to be low or below limits of detectability, with the exceptions being those persons in whom an occupational exposure was eventually found. The ferruginous body content of the occupationally exposed group varied considerably between individuals as well as between sites within the same individual.

Adult↗
PubMed1984

Morphology and ultrastructure of the distal airway epithelium in the guinea pig.

The distal airways, defined anatomically as the region of the respiratory system including the terminal bronchioles through alveoli, were characterized in the guinea pig by means of light microscopy and by both scanning and transmission electron microscopy. The epithelium of the terminal bronchioles was comprised of two cell types. Ciliated cells were cuboidal and contained long thin microvili, ellipsoid mitochondria, and both rough and smooth endoplasmic reticulum. Nonciliated (Clara) cells were dome-shaped and usually protruded into the bronchiolar lumen. Numerous large mitochondria, granules of varying density, and crystalloid inclusions were notable in nonciliated cells. Respiratory bronchioles were characterized by a smooth-surfaced, low cuboidal epithelium. The cells in this region contained the crystalloid material found in terminal bronchioles, numerous large mitochondria, lysosomelike inclusions, and unusual tubular structures arranged in a matrix. The epithelium became progressively squamous toward the alveolar duct, where transition from bronchiolar cells to pneumocytes occurred. Transitional zones consisted of cells which, in addition to the above-mentioned structures, contained inclusions with internal laminations. These inclusions were structurally similar to the lamellar bodies observed in typical type II pneumocytes of the alveoli. The epithelium of both the alveolar ducts and alveoli was composed of type I and type II pneumocytes. Classical type I pneumocytes were squamous and very similar in cytoplasmic characteristics to the endothelial cells of the adjacent capillaries. Type II pneumocytes were characterized by the presence of lamellar bodies and numerous mitochondria.

Animals↗
PubMed1984

The influence of amosite asbestos exposure on lung permeability.

The effect of amosite asbestos on permeability of the blood/air barrier in the lung was studied using an acute animal model. The ultrastructural tracer selected for the study was horseradish peroxidase which was given intravenously in animals that had been exposed intratracheally to asbestos. The acute period of study was either 1/2, 1, 2, 3, or 4 hr, or 1-7 or 14 days postexposure. The barrier in the normal lung was at the level of the alveolar epithelial lining. Leakage of exudate and tracer occurred through the altered barriers following asbestos exposure and the extent of leakage related directly to the degree of alveolitis and the asbestos present in the area. A trend toward recovery of the barrier occurred with the reestablishment of a more normal-appearing epithelial lining during the second week postexposure.

Animals↗
PubMed1984

An ultrastructural study of the blood/air barrier in the guinea-pig.

Horseradish peroxidase (HRP) was intravenously injected into guinea-pigs to ultrastructurally examine the permeability of the blood/air barrier. Adults were given 300 mg/kg of the tracer in a small volume of saline, anesthetized and sacrificed at intervals by either intratracheal filling or right ventricular perfusion with 3% glutaraldehyde. The reaction product had passed through endothelial clefts and accumulated in the interstitium as early as 1.5 min after injection. This same degree of penetration occurred with either fixation method used. Tight junctions between pneumocytes prevented passage of the reaction product into alveoli. Pinocytotic vesicles were numerous in both endothelial and epithelial cells, but did not significantly contribute to tracer transport. Ten minutes post-injection was selected as optimal for this model since the highest concentration of tracer was found in the tissues at this time.

Animals↗
PubMed1983

Cerebrovascular muscle cultures. I. Isolation, growth and morphological characterization.

This study describes the development and establishment of pure cerebrovascular smooth muscle cells derived from dissociated cells of microvessels obtained from brains of rats. The cultured and propagated vascular smooth muscle cells display histochemical and ultrastructural characteristics of smooth muscle cells consistent with those reported in cultures of peripheral vessels. Thus, the cerebrovascular smooth muscle cultures provide a new model system for the investigation of their function, particularly in relation to the regulation of cerebral blood flow and blood pressure.

Animals↗
PubMed1983

Acute lung response to amosite asbestos: a morphological study.

The acute morphological response to amosite asbestos in the guinea pig was studied by light microscopy and by transmission, scanning, and scanning transmission electron microscopy. Fiber identification was carried out by energy dispersive X-ray analysis. Animals were studied at postinjection intervals of 2, 4, and 12 hr and 1-7 days. Three groups of test animals were studied for each time interval. These consisted of a vascularly perfused parenchymal group and a free cell lavaged group. The information obtained was compared with saline-injected and normal control animals. The acute tissue response was characterized by intraalveolar, not interstitial, events. The early phagocytic response was shared between polymorphs and macrophages, while in the longer intervals, the macrophages were the phagocytic cell type. Packaging differences within the two types of phagocytes were seen. Endothelial stability was noted, while some edematous type I pneumocytes were observed. Fibrotic involvement was limited to some intraalveolar fibrin deposits. It is suggested that the term "free asbestos fibers" refers to an extracellular event, while intracellular fibers are coated with either a membranous sheath, a siderosome, or a classical ferruginous coating.

Acute Disease↗
PubMed1983

The influence of inflation levels of the lung on the morphology of the visceral pleura.

The visceral pleura was shown ultrastructurally to be a tightly adhering covering which follows closely the contour of the underlying lung parenchyma. The outer mesothelial layer was comprised of flattened cells when the lung was inflated and transformed into regions of more cuboidal cells after lung collapse. The only distinguishing factors between the visceral pleura of the younger and older animals were the increased connective tissue in the submesothelial areas of the latter and the increased numbers of vesicles found in their basal lamina. The varying degrees of lung inflation can result in marked alterations in the characteristics of the mesothelial layer of the visceral pleura.

Aging↗