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Biomedical subjects

F J Miller

Publications and source records attributed to F J Miller.

At least 127 records · Page 7Linked to original sources
PubMed1984

Identification system for airways in lung models: a note.

A lobar notational system for the identification of airways in the mammalian lung is presented. This system was developed to identify uniquely the location of morphometric and deposition data within a lobe as well as within the lung, and to provide for easy and efficient data reduction. In addition, this notational system can be used to identify main stems like those found in the monopodial lung, and incorporates identification of terminal bronchioles in the airway identifier. The lobar notational system is composed of a two-character lobe code, followed by a third character identifying the branching structure as monopodial or symmetric. The fourth digit identifies the relative position of a branch within the lobe. Subsequent digits identify the airway's relative location within the branching.

Animals↗
PubMed1984

Effects of ammonium sulfate aerosol exposure on lung structure of normal and elastase-impaired rats and guinea pigs.

Rats and guinea pigs, pretreated with intratracheally administered elastase or saline, were exposed to 1.03 mg/m3 (NH4)2SO4; MMAD, 0.42 micron. Identically treated controls were sham exposed. Measurements and evaluation of structural changes were conducted using morphometric techniques on SEM photographs and by applying subjective ratings. Pathology studies were conducted by light and electron microscopy. All examination methods confirmed elastase-induced emphysema, which was aggravated by (NH4)2SO4 exposure in the rat. Ammonium sulfate exposure of saline-treated animals produced measurable degrees of enlargement of alveoli, and alveolar ducts and sacs. Electron microscopy revealed increased interstitial collagen in affected lung areas of elastase-treated, (NH4)2SO4-exposed animals. Alveolar-pore size was significantly increased in elastase-treated animals (control and exposed) but not in saline-treated, exposed animals. The data suggest a possible difference between elastase and (NH4)2SO4 in the mechanisms responsible for the increased diameter of alveolar structures. Hypertrophy and hyperplasia of nonciliated epithelial cells of the small airways and of the Type II alveolar cells were observed in otherwise untreated guinea pigs exposed to (NH4)2SO4 but not in elastase-treated guinea pigs, nor in any of the rats.

Aerosols↗
PubMed1983

Transcatheter arterial embolization--major complications and their prevention.

A thorough account is given of the complications of embolization techniques in nonneurovascular areas, including hepatic infarction, renal and splenic abscess formation. Infarction of the urinary bladder, gallbladder, stomach, and bowel are discussed. Suggestions are offered to prevent complications from embolization where possible. Specific agents for embolization are detailed and their relative merits are compared; ethyl alcohol has recently gained popularity for treating esophageal varices and infarcting renal tumors. Care is advocated when using alcohol in the renal arteries; employing this agent is currently contraindicated in the celiac and mesenteric arteries. Coils and balloon systems are also described along with their potential complications.

Abscess↗
PubMed1983

Pulmonary function in normal and elastase-treated hamsters exposed to a complex mixture of olefin-ozone-sulfur dioxide reaction products.

An elastase-induced emphysema model was utilized to determine if hamsters with preexisting lung disease were more susceptible to lung damage from air pollutant exposure. Male golden hamsters, divided into two treatment groups, were given a single intratracheal injection of either 6 units of porcine pancreatic elastase (EMP) or buffer (CNT). After a 4-week recovery period, equal numbers of each group were exposed 23 hr/day X 28 day to filtered air (AIR) or to the complex by-products from a dark phase reaction mixture of trans-2-butene, ozone, and sulfur dioxide (MIX). Lung function measurements on the elastase-treated groups showed changes consistent with mild emphysema. There were no significant differences in lung volumes or lung compliance between the AIR- and MIX-exposed animals. However, the nitrogen washout slope decreased (P less than 0.05), and the diffusing capacity for carbon monoxide increased (P less than 0.05) in both the CNT and EMP hamsters exposed to the MIX. The change in diffusing capacity was greater (P less than 0.05) in normal hamsters than in hamsters with emphysema, and it is hypothesized that animals with impaired lung function had a decreased ability to respond to a pulmonary insult from the mix.

Air Pollutants↗
PubMed1983

Effects of subchronic exposure to a mixture of O3, SO2, and (NH4)2SO4 on host defenses of mice.

Mice exposed 5 h/d, 5 d/wk up to 103 d, to 0.2 mg O3/m3 or to a mixture of O3, 13.2 mg SO2/m3, and 1.04 mg (NH4)2SO4 aerosol/m3 showed significantly greater susceptibility to group C streptococcal aerosol infection relative to filtered air controls. Pulmonary bactericidal activity by alveolar macrophages was significantly enhanced in the lungs of mice exposed to the mixture relative to those inhaling filtered air or O3 alone. The total number and distribution of the free cells lavaged from the lungs, as well as cellular ATP levels, did not change due to the pollutant exposures. In vitro cytostasis in tumor target cells cocultured with peritoneal macrophages from the exposed mice was significantly enhanced in the O3-exposed and in the mixture-exposed treatment groups relative to controls and also in the mixture-exposed relative to the O3-exposed group when a target-to-effector-cell ratio of 1:10 was used; no such effects were observed when this ratio was 1:20. Splenic T-lymphocyte function, as measured by blastogenesis to mitogens and alloantigens, was affected by exposure to O3 and/or the mixture, although the patterns of effects were qualitatively different. Splenic B-cell function and macrophage antigen processing, as measured by the generation of antibody plaque-forming cells, was unaffected by exposure.

Aerosols↗
PubMed1983

Dynamic tomographic digital subtraction angiography using temporal filtration.

A variation of temporal recursive filtering for intravenous and intra-arterial digital subtraction angiography (DSA) is described. It results in a dynamic tomographic DSA display that may improve intravenous DSA performance by removing the confusion introduced by vessel overlap and reducing the severity of motion artifacts. A conventional circular tomographic apparatus was modified by the addition of a 23-cm image intensifier-television chain and made to run continuously at one revolution each 1.5 seconds. The video output was processed by the recursive filter in a two-step process resulting in a dynamic tomographic display of arterial opacification. Theory and results of initial animal studies are presented.

Angiography↗
PubMed1983

Clinical intra-arterial digital subtraction imaging. Use of small volumes of iodinated contrast material or carbon dioxide.

Forty patients were examined with intra-arterial digital subtraction angiography (DSA) using meglumine iothalamate (202 mg iodine/ml) or CO2 as a contrast medium. Diagnostic studies were obtained in all patients. The use of CO2 resulted in diagnostic examinations of the common femoral artery to the level of the trifurcation. The use of CO2 and low-iodine-content contrast material reduced the iodine dosage, and temporal bandpass filtration DSA permitted a lower entrance exposure than pulsed systems. It is concluded that intra-arterial DSA, using the techniques described in this paper, will become a more important and widely used procedure than it currently is.

Angiography↗
PubMed1983

The changing role of animal toxicology in support of regulatory decisions.

The Clean Air Act is the basic U.S. Federal law for controlling air pollution. Under Sections 108 and 109, primary (health) national ambient air quality standards (NAAQS) can be set for pollutants which are ubiquitous in the ambient air. The standard-setting process includes a comprehensive summary of scientific information on effects and controls in criteria and control techniques, and the selection of an appropriate standard which, in the judgment of the Administrator, protects the health of normal and susceptible subpopulations with an adequate margin of safety. Determining the adequacy of existing NAAQS or establishing new standards requires that the scientific information base be evaluated to assess pollutant effects on public health. Improvements in this process can be accomplished not only through new health effects research, but also through improved use of currently available data. The commonality joining these two efforts is in the area of extrapolation modeling, which is the topic of this paper. Extrapolation modeling involves determining the effective dose delivered to the target organ of several species and the sensitivity of the target organ to that dose so that effective pollutant concentrations can be estimated across species. This in turn allows greater utilization of the results from animals in making judgments about the effects in man from exposure to a given pollutant.

Air Pollutants↗
PubMed1982

Pulmonary host defense responses to inhalation of sulfuric acid and ozone.

The effects of simultaneous exposure to ozone (O3) and sulfuric acid [H2SO4, 0.23 microns volume median diameter (VMD)] and a single exposure to ultrafine (less than 0.1 micron VMD) H2SO4 under various conditions were studied using the infectivity/mortality and the ciliary beating frequency model systems. A 3-h exposure to a combined aerosol of 196 micrograms O3/m3 and 483 or 241 micrograms H2SO4/m3 significantly increased the susceptibility of mice to a laboratory-induced respiratory infection. However, exposure to 543 micrograms ultrafine H2SO4/m3 for 2 h or 365 micrograms/m3 2 h/d for 5 d did not significantly affect this parameter. Upper airway response, as measured by changes in hamster tracheal ciliary beating frequency, was not affected by either a 3-h combined exposure to 196 micrograms O3/m3 and 847 micrograms H2SO4/m3 or a 2-h exposure to 458 micrograms ultrafine H2SO4/m3.

Aerosols↗
PubMed1982

Effects of immunosuppression with cyclophosphamide on acute murine cytomegalovirus infection and virus-augmented natural killer cell activity.

The effects of cyclophosphamide (CY) treatment on acute murine cytomegalovirus (MCMV) infection were studied to explore the potential usefulness of MCMV as a means of detecting immune dysfunction and to identify host defense mechanisms important for protection against MCMV. Conditions found optimal for enhancing MCMV infection with CY included infecting adult mice with 2 X 10(5) PFU or more of virus and administering 80 mg or more of CY per kg 1 to 3 days later. In addition to enhanced mortality, virus titers in lung, liver, and spleen were elevated in CY-treated mice, and wet weights of liver, spleen, and thymus were depressed when compared with those of infected but untreated mice. Treatment with CY before MCMV challenge was not as efficient a means of enhancing mortality as treatment after virus challenge. The effect that the time of CY administration relative to infection had on mortality correlated with the effect of such timing on natural killer cell activity. Animals treated before infection exhibited depressed natural killer cell activity initially. However, they rapidly recovered this response, and by 5 days postinfection they had the same level of virus-augmented activity seen in untreated mice. In contrast, animals treated after infection did not recover natural killer cell activity and were more likely to die. A similar correlation was not obtained when the effects of CY on lymphocyte responses to B and T cell mitogens were examined, nor were there striking differences in pathology between the treatment groups. The data suggest an important role for natural killer cells in host defense against MCMV. Also, increased susceptibility to MCMV may provide a useful indicator of deficits in the natural killer cell response.

Animals↗
PubMed1982

Experimental transcatheter splenectomy using absolute ethanol.

Since ethanol is known to be effective for transcatheter infarction of the kidney, the authors evaluated it as an agent for splenic ablation in swine and dogs. Infarction was successful in 7 of 9 pigs and 4 of 5 dogs. Controlled segmental infarction using flow-directed balloon catheters was attempted and was successful in 3 pigs and 2 dogs. The maximum blood ethanol level was 78 mg/100 ml, and by 15 minutes after injection it was less than or equal to 20 mg/100 ml. There was no evidence of pancreatic or hepatic injury at autopsy. The authors conclude that with careful catheter positioning, controlled total or partial infarction of the spleen can be safely performed with absolute ethanol without risk of abscess formation, pneumonia, or significant damage to other organs.

Animals↗
PubMed1982

Digital subtraction angiography using a temporal bandpass filter: initial clinical results.

A dual digital memory recursive filtering system provides an effective alternative to digital subtraction imaging by using routine fluoroscopic equipment operated with slightly elevated fluoroscopic technical factors. This is accomplished with relatively inexpensive portable electronic equipment that can be connected to the video output of most modern fluoroscopic systems. Initial clinical experimental studies suggest that the system can produce diagnostic images comparable with pulsed fluoroscopic digital systems. The temporal filtering approach offers a real-time vascular imaging technique that requires no postprocessing and can be used either with arterial or intravenous injections of contrast materials.

Adult↗
PubMed1982

Digital subtraction angiography using a temporal bandpass filter: associated patient motion properties.

A system for performing real-time digital angiography both intraarterially and intravenously is described. A filtering process, rather than mask subtraction produces diagnostic-quality angiograms using existing fluoroscopic x-ray systems operated continuously (30 frames/sec) at less than 70 kVp and 20 mA. The image degradation effects of patient motion (breathing, swallowing, sudden movement) are dealt with differently from a subtraction approach. Certain periodic patient motions can be accommodated without the need for postprocessing. An analysis of experimental and clinical results of intravenous angiographic studies is presented, with emphasis on patient motion properties.

Angiography↗