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Biomedical subjects

J M James

Publications and source records attributed to J M James.

At least 37 records · Page 2Linked to original sources
PubMed1997

Patient referrals to a multispecialty asthma clinic. Asthma Care Center Clinical Consortium.

A total of 656 patients with asthma have been referred to a multispecialty pediatric asthma clinic for evaluation; 52 (7.9%): mild; 406 (61.9%): moderate; 177 (27%): severe; and 21 (3.2%): incomplete data. No significant differences in demographics or payer source were observed across disease severity levels. Only 25% of the patients with primary care providers were referred by these practitioners. Over 20% of the mild asthmatics were using inhaled bronchodilators regularly. Only 40% and 50% of the moderate and severe asthmatics, respectively, were using inhaled bronchodilators regularly, and only 19% and 36%, respectively, were on maintenance inhaled corticosteroids. Pressures to reduce subspecialty services may place some of these asthma patients at increased risk for complications from this chronic lung disease.

Administration, Inhalation↗
PubMed1996

Food-associated gastrointestinal disease.

The ingestion of food is frequently associated with specific adverse gastrointestinal symptoms, including emesis, diarrhea, abdominal cramping, and gastrointestinal bleeding. This brief review discusses a variety of food-induced gastrointestinal diseases and will highlight the recent information pertaining to the pathophysiology, clinical presentation, diagnostic approach, and treatment of these disorders. Reactions resulting from immediate hypersensitivity and cell-mediated processes will be reviewed in detail, as well as other proposed pathophysiologic mechanisms. The clinical presentation and diagnostic approach to several food-induced gastrointestinal diseases will be individually examined. In addition, the treatment, especially the proper use of nutritionally balanced restriction diets and hypoallergenic formulas, will be discussed.

Child↗
PubMed1996

Airway reactivity changes in asthmatic patients undergoing blinded food challenges.

To investigate the possible pathogenic role of food allergy in asthma, airway hyperresponsiveness was measured by methacholine inhalation challenges (MIC) performed before and after double-blind, placebo-controlled food challenges (DBPCFC) in 26 food-allergic, asthmatic patients. Airway hyperresponsiveness was classified as severe in two cases (PD20FEV1 < 2 breath units, BU), moderate in 18 (PD20FEV1: 2-20 BU), and mild in six (PD20FEV1 > 20 BU). Medications included albuterol (81%), inhaled steroids (38%), cromolyn (35%), and theophylline (23%). MICs were performed in the afternoon after DBPCFC. Of the 22 positive DBPCFC, 12 involved chest symptoms (cough, wheezing, or both). Another 10 positive DBPCFCs included laryngeal, gastrointestinal, and/or skin symptoms without any chest symptoms. Significant increases in airway hyperresponsiveness were evident in seven of 12 patients experiencing chest symptoms during DBPCFC. Significant increases in airway hyperresponsiveness were observed in one patient without chest symptoms during a positive DBPCFC and one patient after a negative DBPCFC. However, this last patient had a negative MIC with the same antigen 1 yr later. These studies indicate that food-induced allergic reactions can increase airway reactivity, and may do so without inducing acute asthma.

Adolescent↗
PubMed1996

Noninvasive aortic pressure and flow measurement.

The long-term aim of this project is to noninvasively measure aortic blood pressure and aortic blood flow using a portable ultrasonic device. It is envisioned that a small array of ultrasonic crystals will be placed on the suprasternal notch of the neck. The ultrasound beam will be continually positioned onto the aortic arch by a computer. Wall motion will be used as an index of pressure, and flow will be determined through Doppler techniques. The short-term aim is to adapt an ultrasonic hyperthermia array design and control system to produce a focused ultrasound beam from a linear array for aortic pressure and flow measurement. The linear array consists of eight transmitting/receiving crystals, whose focus is controlled by continually changing the time delays for the excitation of each crystal. The hardware and software necessary to produce the delayed excitation signals is discussed.

Aorta, Thoracic↗
PubMed1996

Anaphylaxis: multiple etiologies-focused therapy.

Anaphylatic reactions are severe, generalized clinical reactions. They can occur with or without warning, progress rapidly from isolated to systemic symptoms, and may in some cases result in death. Estimates in the United States have projected that anaphylaxis can occur in approximately one in every 3000 hospitalized patients, and may be responsible for more than 500 deaths annually. This review will present information related to the epidemiology, pathophysiology, diagnosis and treatment of anaphylactic reactions. In addition, key prevention measures will be discussed.

Anaphylaxis↗
PubMed1995

Safe administration of the measles vaccine to children allergic to eggs.

BACKGROUND: The safety of administering the combined measles-mumps-rubella (MMR) vaccine to patients who are allergic to eggs has been debated for decades because of concern about potential anaphylaxis, since the live attenuated virus used in the vaccine is grown in cultured chick-embryo fibroblasts. METHODS: We recruited 54 children (mean age, 18.5 months) who had not previously been vaccinated and were allergic to eggs. The children's histories of allergy were confirmed with skin tests and double-blind, placebo-controlled food-challenge tests; some children also underwent skin testing with the MMR vaccine. We then routinely administered the vaccine to the children in one subcutaneous (0.5-ml) dose. RESULTS: All 54 children had positive results on skin testing with egg. Allergy to eggs was confirmed in 26 of the children by convincing histories of anaphylaxis after the ingestion of eggs, in 22 children by food-challenge tests, and in 6 patients by convincing histories of recent allergic reactions occurring after the ingestion of eggs. Of the 17 children who underwent skin testing with the MMR vaccine, 3 had positive results. All 54 children received the MMR vaccine as a single subcutaneous injection; none had an immediate or delayed adverse reaction. CONCLUSIONS: The MMR vaccine can be safely administered in a single dose to children with allergy to eggs, even those with severe hypersensitivity.

Anaphylaxis↗
PubMed1995

Technegas and Pertechnegas particle size distribution.

Technegas and Pertechnegas are radioactive aerosols produced in a commercial generator and used for lung scintigraphy. The aerosols are produced by first evaporating to dryness standard technetium-99m generator eluate (99mTcO4 in normal saline) in a graphite crucible (the simmer stage) and then heating this to 2500 degrees C (the "burn" stage). The aim of this work was to measure the particle size distributions of these agents and relate this to regional lung deposition. Factors that may vary during production of the aerosol in routine use were investigated to determine whether they influenced the particle size. Activity size distributions were measured using a serial wire-screen diffusion battery. The Technegas size distribution was approximately log-normal with an activity median diameter of 158 nm and a geometric standard deviation of 1.5. The results for Pertechnegas were similar. The median size increased with the number of simmers and with the time from generation. The increase in size with the number of simmers is thought to be due to the increased salt content in the crucible prior to the "burn". The predicted lung deposition is 37% in the alveolar region and 5% in the bronchial region. Significant changes in deposition are not predicted over the range of particle sizes measured.

Aerosols↗
PubMed1995

Texture analysis of technegas lung ventilation images.

Technegas lung ventilation images sometimes have 'hot spots', particularly in patients with respiratory disease. A novel technique is presented for quantifying this 'spottiness' using morphological texture analysis. A set of 32 images from patients with various respiratory diseases is studied. Images are filtered at a range of scales using morphological opening, and the slopes of image metrics versus structuring element size are used as texture parameters. The results are compared with the opinions of three experienced nuclear medicine physicians who have classified the images into two groups, 'spotty' and 'non-spotty', and have ranked the former. For the spotty images, the computer and observer ranks are compared; the highest correlation is rs = 0.66 (p = 0.01) for a single parameter, and rs = 0.71 (p < 0.01) for a combination of two parameters. Using a pair of parameters, 83% and 90% correct classification rates are obtained for the spotty and non-spotty classes, respectively. It is concluded that these texture parameters provide a useful measure of image spottiness, and it is demonstrated that this technique is superior to previously published methods. The practical value of the technique is illustrated using two applications.

Humans↗
PubMed1995

The use of 99Tcm-Technegas in the investigation of patients with pulmonary thromboembolism.

Pulmonary embolism remains a major cause of morbidity and mortality, being responsible for an estimated 200,000 deaths per annum in the USA and 21,000 per annum in the UK. Lung scintigraphy is in many instances the investigation of choice in suspected pulmonary thromboembolism. A normal perfusion lung scan excludes pulmonary embolism. An abnormal perfusion scan, while being sensitive, is of low specificity for the diagnosis of pulmonary embolism and needs to be complemented with a ventilation study. Lung ventilation has been studied using inert gases of radiolabelled aerosols. The new radiopharmaceutical 99Tcm-Technegas is a suspension of 99Tcm-labelled, ultrafine, carbon particles produced in an atmosphere of high-purity argon. The size of the particles is of the order of 0.005-0.2 microns, which assures good peripheral penetration and alveolar deposition. After inhalation, static images in multiple projections may be acquired. The resultant images are of excellent technical quality and several publications have shown the value of Technegas images as an adjunct to perfusion imaging in suspected pulmonary thromboembolism. Studies comparing Technegas images with other ventilatory radiopharmaceuticals have in the majority of instances reported comparable diagnostic qualities.

Administration, Inhalation↗
PubMed1994

The influence of inhalation technique on Technegas particle deposition and image appearance in normal volunteers.

The aim of this work was to investigate the influence of inhalation technique on Technegas image quality and on fractional particle deposition. This was investigated in six normal volunteers using three different types of breathing pattern. Fractional deposition was determined by analysis of dynamic gamma camera images acquired during Technegas administration. Static lung images were subsequently acquired and assessed independently by three experienced observers. High-quality images were obtained in all cases although slight differences were noted. The images produced using a slow deep inspiration with a breath hold (i.e. the standard method) were of more uniform texture and also had the least gradient in activity from apex to base. The converse was true for a rapid inhalation technique. The average fractional deposition per breath was 55%, but this varied between individuals and with breathing pattern, being most influenced by the total duration of a breath. We conclude that for patient studies the standard inhalation technique is best, although variation to suit individual patients would be acceptable. These results contrast with similar studies using conventional radio-aerosols, which tend to show a greater sensitivity of image appearance to changes in breathing pattern and lower fractional depositions.

Adult↗
PubMed1994

Contamination levels and doses to staff arising from the use of Technegas.

The aim of this work was to assess the levels of airborne activity and contamination arising from Technegas ventilation scintigraphy and to estimate doses to staff. The maximum air concentration was below the 99Tcm-derived air concentration limit and considerably lower than reported levels for conventional radioaerosols. The level of contamination on staff gloves and aprons exceeded the body surface contamination limit in 63 and 9% of cases, respectively. Levels of contamination and air concentration were generally higher if the patient had difficulty with the administration procedure. Room surface contamination was very low. In 24% of cases activity was detectable on staff (either in the hair or nose) using gamma camera imaging. Annual skin doses from these sources are calculated to be below the limit for deterministic effects. Whole body effective doses are calculated to be similar to those received by staff performing other nuclear medicine studies. However, care should be exercised to keep exposure from both airborne and fixed sources to a minimum and a regular review of contamination levels is recommended. We recommend the wearing of gloves for all Technegas administrations and disposable hats and masks may be considered in certain cases.

Air Pollutants, Occupational↗
PubMed1994

Food hypersensitivity in children.

A variety of investigations of food hypersensitivity have been published over the past 18 months. These studies have focused on specific immunopathogenic, clinical, diagnostic, and prophylactic issues directly related to this allergic disorder. Whereas several of the reports have confirmed previous findings, significant pieces of new information have emerged. This review provides a practical summary of these scientific publications specifically related to food allergy.

Child↗
PubMed1994

Imaging techniques in the diagnosis of urinary tract infection.

In terms of future morbidity and mortality, one of the most important considerations in urinary tract infection is the age of the patient. In adults, only those with complications or illnesses that fail to respond to treatment require investigation to exclude underlying pathology. In contrast, the young are at risk of future hypertensive and renal disease; imaging techniques are therefore of paramount importance to identify those with renal parenchymal disease at an early stage and permit appropriate and adequate treatment. 99mTc-dimercaptosuccinic acid scintigraphy is emerging as the method of choice for this purpose, because it combines high specificity and sensitivity with convenience, repeatability, and acceptable radiation doses. Voiding cystourethrography will also be required in many cases to exclude bladder pathology. New developments include the use of color Doppler ultrasonography and the nuclear magnetic resonance technique of rapid acquisition recall echo urography, both of which may become of value for the detection of scarring.

Adult↗
PubMed1994

Respiratory reactions provoked by double-blind food challenges in children.

A total of 320 children with atopic dermatitis undergoing double-blind, placebo-controlled food challenges (DBPCFC) for the evaluation of food hypersensitivity were monitored for respiratory reactions. The patients, ages 6 months to 30 yr, were highly atopic (median IgE; 3,400 IU/ml) and had multiple sensitivities to foods and aeroallergens. Fifty-five percent of the patients had asthma; 45% presented with both asthma and allergic rhinitis. Food hypersensitivity was confirmed by DBPCFC in 205 (64%) of the 320 patients evaluated, and 121 (59%) of these 205 patients experienced respiratory reactions, including nasal, laryngeal, and/or pulmonary symptoms in 34 (17%). To assess the degree of pulmonary dysfunction developing during food hypersensitivity reactions, especially those including lower respiratory symptoms, 88 of these patients were monitored with spirometry during positive and negative DBPCFC. Of these patients, 13 (15%) developed lower respiratory symptoms, including wheezing, during DBPCFC; however, only six patients had a > 20% decrease in FEV1. We conclude that respiratory symptoms are commonly provoked in children with atopic dermatitis during DBPCFC, but significant bronchopulmonary obstruction is not frequently observed.

Adolescent↗
PubMed1993

Patients with severe atopic dermatitis have activated circulating basophils.

BACKGROUND: The purpose of this study was to define the potential role of the basophil in the pathogenesis of atopic dermatitis by comparing basophil releasibility in patients with food allergy and either mild or severe atopic dermatitis. METHODS: A clinical scoring system was used to differentiate patients into either a low clinical score (LCS) group, 10 patients, or a high clinical score (HCS) group, 14 patients. Basophil histamine release was measured with a radioenzymatic assay, and leukotriene C4 (LTC4) was determined with a radioimmunoassay. Histamine and LTC4 released from basophils spontaneously or after incubation with deuterium oxide, an IgE-dependent histamine-releasing factor, anti-IgE, and C5a were measured. RESULTS: Basophils from the HCS group released more histamine than those from the LCS group when stimulated with deuterium oxide (median percent total release: 85% vs 68%, p < 0.05), with 10 and 100 ng/ml of anti-IgE (58% vs 26% and 62.5% vs 37%, both p < 0.05) and 5 and 50 ng/ml of C5a (50.5% vs 11.5, p < 0.05; 49% vs 11%, p < 0.01, respectively). The spontaneous release of LTC4 from basophils was greater in the HCS group (median release: 34 vs 3.5 pg/0.1 ml, p < 0.05). Basophils stimulated with deuterium oxide, with 100 ng/ml anti-IgE, and 50 ng/ml C5a released more LTC4 in the HCS group (111.5 vs 39 pg/0.1 ml, p < 0.05; 64.5 vs 10 pg/0.1 ml, p < 0.01; 80 vs 1 pg/0.1 ml, p < 0.05, respectively). CONCLUSIONS: These data indicate that patients with more severe atopic dermatitis have "activated" circulating basophils in vivo and increased basophil releasibility, in particular in response to C5a. These studies may serve as markers for more severe atopic dermatitis.

Adolescent↗