Committee thinks rabies postexposure protocol raises public health concerns.
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Animals↗
Biomedical subjects
R H Johnson
Publications and source records attributed to R H Johnson.
Compendium of animal rabies, prevention and control, 2001.
Explore the source record for details and available documents.
Animals↗
The role of the radiation safety specialist as witness: risk communication with attorneys, judges, and jurors.
As nuclear workers and members of the public continue to fear radiation in this litigious society, specialists in radiation safety will often be called upon as experts to explain the significance of radiation exposures or as fact witnesses to explain radiation safety practices. Radiation risk communication with attorneys, judges, and jurors presents special challenges to the communication skills of health physicists. Your role as the radiation specialist is to present testimony, either in the form of a deposition or as a trial witness, in a way that a judge or jury can understand. As a specialist in radiation safety, you will also need to educate the attorney that you work with so that he or she can ask the right questions and defend challenges in the case. The way that you communicate to attorneys, judges, and jurors could have a great impact on the case's outcome. As a radiation specialist, your testimony is not only to present the scientific basis for radiation health risks, but also to persuade the judge or jurors in the direction of the desired outcome of the case. Insights from the Myers-Briggs Type Indicator show that judges and jurors are most likely persuaded by "Sensing" language that is specific, detailed, measurable, and verifiable with their five senses. Thus, the conceptual, abstract, and theoretical "Intuitive" language often favored by radiation experts may not be understood or appreciated by a judge or jurors. They may also prefer the more personal, empathetic, and caring "Feeling" language rather than the impersonal, logical, and analytical "Thinking" language favored by health physicists. People's feelings about radiation risks are a big factor in radiation cases and providing testimony to address feeling-based conclusions requires a very different communication approach than normally used by health physicists. An understanding of language preferences can be crucial for effective communication with attorneys, judges, and jurors. These insights are derived from the author's experience as a communication specialist and as a radiation expert for the plaintiffs in two radon cases. This paper also provides insights into the qualifications for serving as an expert or fact witness, preparation for a trial, presenting testimony, the courtroom as drama, and the best language modes for persuasive communications with judges and jurors.
Communication↗
Microfocal X-ray CT imaging and pulmonary arterial distensibility in excised rat lungs.
The objective of this study was to develop an X-ray computed tomographic method for measuring pulmonary arterial dimensions and locations within the intact rat lung. Lungs were removed from rats and their pulmonary arterial trees were filled with perfluorooctyl bromide to enhance X-ray absorbance. The lungs were rotated within the cone of the X-ray beam projected from a microfocal X-ray source onto an image intensifier, and 360 images were obtained at 1 degrees increments. The three-dimensional image volumes were reconstructed with isotropic resolution using a cone beam reconstruction algorithm. The vessel diameters were obtained by fitting a functional form to the image of the vessel circular cross section. The functional form was chosen to take into account the point spread function of the image acquisition and reconstruction system. The diameter measurements obtained over a range of vascular pressures were used to characterize the distensibility of the rat pulmonary arteries. The distensibility coefficient alpha [defined by D(P) = D(0)(1 + alphaP), where D(P) is the diameter at intravascular pressure (P)] was approximately 2.8% mmHg and independent of vessel diameter in the diameter range (about 100 to 2,000 mm) studied.
Anatomy, Cross-Sectional↗
Pulmonary arterial morphometry from microfocal X-ray computed tomography.
The objective of this study was to develop an X-ray computed tomographic method for pulmonary arterial morphometry. The lungs were removed from a rat, and the pulmonary arterial tree was filled with perfluorooctyl bromide to enhance X-ray absorbance. At each of four pulmonary arterial pressures (30, 21, 12, and 5.4 mmHg), the lungs were rotated within the cone of the X-ray beam that was projected from a microfocal X-ray source onto an image intensifier, and 360 images were obtained at 1 degrees increments. The three-dimensional image volumes were reconstructed with isotropic resolution with the use of a cone beam reconstruction algorithm. The luminal diameter and distance from the inlet artery were measured for the main trunk, its immediate branches, and several minor trunks. These data revealed a self-consistent tree structure wherein the portion of the tree downstream from any vessel of a given diameter has a similar structure. Self-consistency allows the entire tree structure to be characterized by measuring the dimensions of only the vessels comprising the main trunk of the tree and its immediate branches. An approach for taking advantage of this property to parameterize the morphometry and distensibility of the pulmonary arterial tree is developed.
Animals↗
Comparison of oral fluconazole and itraconazole for progressive, nonmeningeal coccidioidomycosis. A randomized, double-blind trial. Mycoses Study Group.
BACKGROUND: In previous open-label noncomparative clinical trials, both fluconazole and itraconazole were effective therapy for progressive forms of coccidioidomycosis. OBJECTIVE: To determine whether fluconazole or itraconazole is superior for treatment of nonmeningeal progressive coccidioidal infections. DESIGN: Randomized, double-blind, placebo-controlled trial. SETTING: 7 treatment centers in California, Arizona, and Texas. PATIENTS: 198 patients with chronic pulmonary, soft tissue, or skeletal coccidioidal infections. INTERVENTION: Oral fluconazole, 400 mg/d, or itraconazole, 200 mg twice daily. MEASUREMENTS: After 4, 8, and 12 months, a predefined scoring system was used to assess severity of infection. Findings were compared with those at baseline. RESULTS: Overall, 50% of patients (47 of 94) and 63% of patients (61 of 97) responded to 8 months of treatment with fluconazole and itraconazole, respectively (difference, 13 percentage points [95% CI, -2 to 28 percentage points]; P = 0.08). Patients with skeletal infections responded twice as frequently to itraconazole as to fluconazole. By 12 months, 57% of patients had responded to fluconazole and 72% had responded to itraconazole (difference, 15 percentage points [CI, 0.003 to 30 percentage points]; P = 0.05). Soft tissue disease was associated with increased likelihood of response, as in previous studies. Azole drug was detected in serum specimens from all but 3 patients; however, drug concentrations were not helpful in predicting outcome. Relapse rates after discontinuation of therapy did not differ significantly between groups (28% after fluconazole treatment and 18% after itraconazole treatment). Both drugs were well tolerated. CONCLUSIONS: Neither fluconazole nor itraconazole showed statistically superior efficacy in nonmeningeal coccidioidomycosis, although there is a trend toward slightly greater efficacy with itraconazole at the doses studied.
Administration, Oral↗
Practice guideline for the treatment of coccidioidomycosis. Infectious Diseases Society of America.
Management of patients diagnosed with coccidioidomycosis involves defining the extent of infection and assessing host factors that predispose to disease severity. Patients with relatively localized acute pulmonary infections and no risk factors for complications often require only periodic reassessment to demonstrate resolution of their self-limited process. On the other hand, patients with extensive spread of infection or at high risk of complications because of immunosuppression or other preexisting factors require a variety of treatment strategies that may include antifungal therapy, surgical debridement, or both. Amphotericin B is often selected for treatment of patients with respiratory failure due to Coccidioides immitis or rapidly progressive coccidioidal infections. With other more chronic manifestations of coccidioidomycosis, treatment with fluconazole, itraconazole, or ketoconazole is common. Duration of therapy often ranges from many months to years, and, for some patients, chronic suppressive therapy is needed to prevent relapses.
Antifungal Agents↗
Coccidioidomycosis in pregnancy during an epidemic in California.
OBJECTIVE: To determine presentation, clinical course, and outcome of a cohort of pregnant women with coccidioidomycosis and compare findings with common observations reported in the literature. METHODS: Thirty-two women who delivered live infants or aborted fetuses in 1993 and had confirmed diagnoses of coccidioidomycosis were included in the study. Medical records were evaluated retrospectively for clinical characteristics, laboratory results, and disease course. RESULTS: Dissemination occurred in three of 32 cases. The most common management was supportive and symptomatic care. At 1 year, 26 of 32 had recovered. There were no maternal deaths. CONCLUSION: The common depiction of coccidioidomycosis in pregnancy has overstated morbidity and mortality likely because of reporting bias. Many women will have favorable outcomes without drug treatment, and the practice of abortions or early delivery in subjects with active infection should be rare.
Adult↗
Steady-state pharmacokinetics of indinavir in cerebrospinal fluid and plasma among adults with human immunodeficiency virus type 1 infection.
To characterize steady-state indinavir pharmacokinetics in cerebrospinal fluid and plasma, 8 adults infected with human immunodeficiency virus underwent intensive cerebrospinal fluid sampling while receiving indinavir (800 mg every 8 hours) plus nucleoside reverse transcriptase inhibitors. Nine and 11 serial cerebrospinal fluid and plasma samples, respectively, were obtained from each subject. Free indinavir accounted for 94.3% of the drug in cerebrospinal fluid and 41.7% in plasma. Mean values of cerebrospinal fluid peak concentration, concentration at 8 hours, and area under the concentration-time profile calculated over the interval 0 to 8 hours [AUC(0-8)] for free indinavir were 294 nmol/L, 122 nmol/L, and 1616 nmol/L x h, respectively. The cerebrospinal fluid-to-plasma AUC(0-8) ratio for free indinavir was 14.7% +/- 2.6% and did not correlate with indexes of blood-brain barrier integrity or intrathecal immune activation. Indinavir achieves levels in cerebrospinal fluid that should contribute to control of human immunodeficiency virus type 1 replication in this compartment. The cerebrospinal fluid-to-plasma AUC(0-8) ratio suggests clearance mechanisms in addition to passive diffusion across the blood-cerebrospinal fluid barrier, perhaps by P-glycoprotein-mediated efflux.
Acquired Immunodeficiency Syndrome↗
An iterative approach to the beam hardening correction in cone beam CT.
In computed tomography (CT), the beam hardening effect has been known to be one of the major sources of deterministic error that leads to inaccuracy and artifact in the reconstructed images. Because of the polychromatic nature of the x-ray source used in CT and the energy-dependent attenuation of most materials, Beer's law no longer holds. As a result, errors are present in the acquired line integrals or measurements of the attenuation coefficients of the scanned object. In the past, many studies have been conducted to combat image artifacts induced by beam hardening. In this paper, we present an iterative beam hardening correction approach for cone beam CT. An algorithm that utilizes a tilted parallel beam geometry is developed and subsequently employed to estimate the projection error and obtain an error estimation image, which is then subtracted from the initial reconstruction. A theoretical analysis is performed to investigate the accuracy of our methods. Phantom and animal experiments are conducted to demonstrate the effectiveness of our approach.
Algorithms↗
Effective presentation of radiation safety training--risk communication: an important function of radiation safety training.
Implementing an effective radiation safety program requires good communication with workers. The process begins with radiation safety. Before workers take a position involving radiation exposures, they should understand the possible health risks and what to do to keep their risks ALARA. The goal is for workers to achieve a balanced perspective on radiation health risks in order to avoid either undue fear or undue complacency about radiation. Workers should have enough understanding of radiation risks to decide to acceptor not accept-or not accept the risk of radiation as a condition of employment. Furthermore, the decision to accept radiation risk for the benefits of employment should be based on informed consent. Workers with a good understanding of radiation health risks will strive to minimize not only their own radiation exposure but also those of their work group. Normally radiation safety training to achieve worker understanding is focused primarily on the technology of radiation. However, understanding is more than a matter of good technical information. What one chooses to understand is also impacted by perceptions of radiation risks.
Adult↗
Clinical and economic evaluation of subsequent infection following intravenous ciprofloxacin or imipenem therapy in hospitalized patients with severe pneumonia.
A recent multicentre clinical study evaluated the safety and efficacy of i.v. ciprofloxacin therapy compared with imipenem-cilastatin in hospitalized patients with severe pneumonia. Monotherapy with i.v. ciprofloxacin was at least equivalent to imipenem in terms of bacteriological eradication and clinical response. In a single-centre, retrospective, post-therapy evaluation of persistent and subsequent infection, the incidence of gram-negative infections and associated costs were compared. The main elements of the economic analysis included costs of additional antimicrobial therapy and hospitalization. Thirty-two patients were randomized into the study, of whom 27 were efficacy-valid. The 13 patients randomized into the ciprofloxacin group were not significantly different from the 14 patients in the imipenem group in terms of clinical parameters. Clinical cure occurred in ten of 13 patients (77%) in the ciprofloxacin group and in seven of 14 (50%) in the imipenem group. Bacteriological eradication was achieved in 11 of 13 (85%) ciprofloxacin-treated and eight of 14 (57%) imipenem-treated patients. Five of 13 (38%) patients in the ciprofloxacin group and nine of 14 (64%) in the imipenem group experienced persistent or subsequent infection requiring post-treatment antimicrobials. In these five ciprofloxacin patients, three had cultures with gram-positive organisms only and two had cultures with both gram-positive and gram-negative organisms. In the nine imipenem-treated patients requiring post-study antimicrobials, all had gram-negative bacteria and three also had gram-positive organisms. The incidence of subsequent gram-negative infection in the two groups (15% vs 64%) was significantly different (P < 0.05). Pseudomonas aeruginosa was isolated from seven patients in the imipenem group but only one in the ciprofloxacin group (P < 0.05). Subsequent costs for post-therapy antimicrobials and hospital stay while receiving study and post-study drug therapy were evaluated; the cost per patient cure was US$29,000 for ciprofloxacin and US$76,000 for imipenem. Initial treatment of severe pneumonia with ciprofloxacin resulted in significantly less subsequent gram-negative infection and was associated with substantially lower curative costs.
Adult↗
Feldkamp and circle-and-line cone-beam reconstruction for 3D micro-CT of vascular networks.
Detailed morphometric knowledge of the microvascular network is needed for studies relating structure to haemodynamic function in organs like the lung. Clinical volumetric CT is limited to millimetre-order spatial resolution. Since evidence suggests that small arterioles (50 to 300 micrometres) dominate pulmonary haemodynamics, we built a micro-CT scanner, capable of imaging excised lungs in 3D with 100 microm resolution, for basic physiology research. The scanner incorporates a micro-focal (3 microm) x-ray source, an xyz theta stage and a CCD-coupled image intensifier detector. We imaged phantoms and contrast-enhanced rat lungs, reconstructing the data with either the Feldkamp or the circle-and-line cone-beam reconstruction algorithm. We present reconstructions using 180 views over 360 degrees for the circular trajectory, augmented with views from a linear scan for the circle-and-line algorithm. Especially for platelike features perpendicular to the rotation axis and remote from the midplane, the circle-and-line algorithm produces superior reconstructions compared with Feldkamp's algorithm. We conclude that the use of nonplanar source trajectories to perform micro-CT on contrast-enhanced, excised lungs can provide data useful for morphometric analysis of vascular trees, currently down to the 130 microm level.
Algorithms↗
Automated detection of BB pixel clusters in digital fluoroscopic images.
Small ball bearings (BBs) are often used to characterize and correct for geometric distortion of x-ray image intensifiers. For quantitative applications the number of BBs required for accurate distortion correction is prohibitively large for manual detection. A method to automatically determine the BB coordinates is described. The technique consists of image segmentation, pixel coalescing and centroid calculation. The dependence of calculated BB coordinates on segmentation threshold was also evaluated and found to be within the uncertainty of measurement.
Algorithms↗
Septic shock in coccidioidomycosis.
OBJECTIVES: To describe the clinical and laboratory parameters of patients with septic shock following infection with Coccidioides immitis, estimate the incidence of septic shock from coccidioidomycosis, and outline clues that may be helpful in early diagnosis of this syndrome. DESIGN: Retrospective, descriptive case series. SETTING: A 250-bed general public hospital in Kern County, CA. PATIENTS: Eight patients diagnosed with septic shock from infection with C. immitis from September 1991 to December 1993. Five were Hispanic, two were Filipino, and one was African-American. The diagnosis of C. immitis was made by microscopic examination and culture of the organism from sputum or other sites. Septic shock was diagnosed using criteria formulated by the American College of Chest Physicians Consensus Conference/Society of Critical Care Medicine. MEASUREMENTS AND MAIN RESULTS: No patient had traditional immunocompromising conditions. All patients had pulmonary symptoms and were symptomatic for a mean duration of 19.4 +/- 19.8 days before admission. One patient presented with septic shock and the remaining seven developed shock during their hospital course. Serology for coccidioidomycosis was positive in six patients. The mean cardiac index was 5.8 +/- 1.9 (SD) L/min/m2, the mean arterial pressure was 71.0 +/- 16.7 mm Hg, the mean pulmonary artery occlusion pressure was 16.9 +/- 3.5 mm Hg, and the mean systemic volume resistance index was 846.6 +/- 224.1 dyne-sec/cm5xm2. All patients developed acute respiratory distress syndrome. Coccidioidomycosis was recognized or considered in only five of eight patients before they developed septic shock. Despite therapy with amphotericin B, all patients died. One patient died of progressive pulmonary disease, two patients suffered an acute arrest, and five patients developed progressive multiple organ system failure and died with additional organ involvement. CONCLUSIONS: Septic shock following infection with C. immitis is an ominous yet underrecognized condition. Hemodynamic parameters and cytokine concentrations were not significantly different from values seen in gram-negative septic shock. Clinical clues to the diagnosis include duration of illness and conspicuous pulmonary involvement. Patient outcome in this series was poor but may improve with increased recognition of septic shock in infections from C. immitis.
Adult↗
Association between facial cutaneous coccidioidomycosis and meningitis.
The skin is frequently a site of extrapulmonary dissemination in patients with coccidioidomycosis. Clinical experience in an endemic area suggests an association between facial cutaneous coccidioidomycosis and meningitis. Awareness of this association is important because coccidioidal meningitis is the most ominous site of spread in coccidioidomycosis. In this study, we assess whether cutaneous dissemination involving the face is associated with meningitis to a greater degree than that limited to the body. We retrospectively reviewed the medical records of 201 patients from 1987 to 1996 with disseminated coccidioidomycosis and found 30 patients with cutaneous involvement. Their mean age was 29.5 +/- 11.6 years; 20 patients were male; 14 were African American, 12 were Hispanic, 3 were white, and 1 was Asian. Nineteen patients had facial involvement, and 11 had isolated body involvement. Meningitis developed in 11 patients, 10 with facial involvement and 1 with only body involvement. Patients with facial lesions were more likely to have meningitis (odds ratio, 11.1; 95% confidence interval, 1.1 to 529, P = .023). The identification of a subgroup of patients at significant risk of developing meningitis may allow earlier detection and perhaps improved management of patients with meningeal disease.
Adult↗
Bisphosphonates in the treatment of osteoporosis.
Bisphosphonates are compounds derived from pyrophosphate, a byproduct of cellular cleavage of adenosine triphosphate (ATP), and are resistant to alkaline phosphatase by virtue of replacement of oxygen by carbon. The high affinity of the P-C-P structure for hydroxyapatite accounts for deposition in bone. Modification of the two side chains of carbon alters the potency of the drugs. Of those that have either completed or are undergoing clinical trials, the order of increasing potency for inhibition of bone resorption is etidronate, clodronate, tiludronate, pamidronate, alendronate, residronate and ibandronate (potency range: 1 to 10,000). Less than 5% of bisphosphonates are absorbed and the half life is a few hours. The drugs must be given on an empty stomach because food and beverages interfere with gastrointestinal absorption. Of the absorbed fraction, as much as 60% is taken up by the skeleton and the remainder is excreted unchanged in the urine. Etidronate, tiludronate, residronate, and alendronate are given orally, clodronate intravenously, and pamidronate and ibandronate by either route. At lower concentrations, bisphosphonates inhibit osteoclatic bone resorption, whereas at higher concentrations they may inhibit mineralization and cause osteomalacia. Inhibition of mineralization diminishes with increasing potency. In postmenopausal women, etidronate and alendronate for 3 yr were shown to inhibit bone resorption, increase bone mineral density (BMD) of the lumbar spine and hip, and prevent fractures without producing osteomalacia. Bone formation also is reduced as a consequence of diminished bone resorption but reduction is less than the reduction of bone resorption. In higher doses bisphosphonates may cause upper gastrointestinal disturbances but in recommended doses they generally are well tolerated and have an excellent safety profile.
Diphosphonates↗
Central nervous system abscesses due to Coccidioides species.
Meningitis occurs in one-third to one-half of patients with disseminated coccidioidomycosis, but mass lesions have rarely been described; these lesions are usually found at autopsy. We report six cases of disseminated coccidioidomycosis with central nervous system (CNS) abscesses. Four patients had cerebellar involvement, and two had spinal cord involvement. Four patients were diabetic, and two subsequently died. Review of the literature on CNS coccidioidomycosis indicated that parenchymal brain involvement occurs in 1%-33% of cases, and < 40 cases with mass lesions have been reported since 1905. Almost all patients were male and had other active disseminated foci of coccidioidomycosis. In approximately one-third of all cases, meningitis was absent. Brain lesions may be superficial or deep and multiple or single. In the absence of meningitis, serology of cerebrospinal fluid is negative. Hematogenous origin appears to be more common than direct extension from the meninges. Spinal cord involvement is rare. Diabetes was present in several cases, thus suggesting a vascular predisposition. We hope our experience will increase awareness of this entity, which appears to be more common than previously appreciated, and will facilitate diagnosis.
Abscess↗