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Biomedical subjects

J M James

Publications and source records attributed to J M James.

At least 19 recordsLinked to original sources
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↗
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↗
PubMed1992

Early gene interaction during prepupal expression of Drosophila arginine kinase.

Arginine kinase displays a distinctive rise and fall in specific activity and specific protein levels during the prepupal stage of Drosophila development with maximal activity occurring at morphological stage P3. This developmentally regulated peak is under the influence of ecdysone. Altered doses of the major ecdysone-inducible "early" genes at cytological regions 75B and 2B5 alter this pattern of expression while altered doses of another major "early" gene at 74EF have no effect. We hypothesize that a product of the 2B5 locus and a product of the 75B locus interact to effect this developmental pattern of expression of Drosophila arginine kinase.

Animals↗
PubMed1992

Immunologic changes associated with the development of tolerance in children with cow milk allergy.

The purpose of this study was to determine whether cow milk-specific antibody responses correlated with the development of clinical tolerance in cow milk-allergic children. Double-blind, placebo-controlled food challenges were performed annually in 29 patients with cow milk allergy. Clinical reactivity was lost in 11 (38%) of 29 patients. The median age for all patients at the time of diagnosis by these food challenges was 3 years; more than 80% of patients in each group had atopic dermatitis as part of their presenting symptoms. Casein-specific and beta-lactoglobulin-specific IgE, IgG, IgG1, and IgG4 antibody concentrations were analyzed in all patients at regular intervals. In the patients becoming clinically tolerant to cow milk, the IgE-specific antibody concentrations and IgE/IgG-specific ratios for both milk proteins were lower initially and decreased significantly with time, in comparison with those in the group who retained clinical sensitivity. The concentrations of IgG1- and IgG4-specific antibody to casein and the IgE/IgG1 and IgE/IgG4 ratios for both casein and beta-lactoglobulin were significantly less in the patients losing clinical reactivity. No differences in the IgG-specific concentrations were observed in either group at any of the evaluation times noted above. Monitoring similar casein-specific and beta-lactoglobulin-specific IgE concentrations and IgE/IgG ratios may help predict which patients will ultimately lose their clinical reactivity to cow milk.

Adolescent↗
PubMed1992

The incidence and severity of hypoxia associated with 99Tcm Technegas ventilation scintigraphy and 99Tcm MAA perfusion scintigraphy.

Inhalation of the ventilatory radiopharmaceutical 99Tcm Technegas leads, in some patients, to symptoms that may be attributed to temporary lowering of oxygen saturation. In order to evaluate this, oxygen saturation was measured by pulse oximetry in a series of patients undergoing Technegas ventilation scintigraphy. A decrease in oxygen saturation was recorded in 87% of the patient group. The mean change, as a percentage of the initial value, was 8.3% (range 1-24%). Hypoxia arising in association with Technegas administration may be reduced by pre-oxygenation. In patients who were pre-oxygenated, oxygen saturation did not fall below 85% (PaO2: 50 mmHg) but in 39% of those not pre-oxygenated the value fell below this level. Oxygen saturation was also monitored in a series of patients undergoing perfusion scintigraphy. In 17% of patients a decrease was recorded (range 2-11%). In view of the large number of perfusion scans performed annually in this department and elsewhere without untoward effect, such temporary decreases in oxygen saturation presumably present no hazard to the patient.

Adolescent↗
PubMed1992

99Tcm-Technegas and krypton-81m ventilation scintigraphy: a comparison in known respiratory disease.

Krypton-81m gas, by virtue of its imaging characteristics, is often considered the "gold standard" for ventilation scintigraphy but its use is restricted by its high cost and limited availability. The new radiopharmaceutical 99Tcm-Technegas, a suspension of ultrafine technetium-99m labelled carbon particles, produces high-quality images of ventilation and has the advantage of continuous availability. As part of our evaluation of Technegas the two were compared in 40 patients with a variety of established respiratory diseases. Disparities were seen in five patients in five diagnostic groups and may be a consequence of the differing physical properties of the two agents and the different inhalation techniques used. In addition two interesting features were noted on the Technegas images. (1) Hot spots were seen in 50% of patients, particularly in those with a degree of airways obstruction; (2) preferential basal deposition of activity was seen in 30%, particularly in patients with idiopathic pulmonary fibrosis. Both features were significantly associated with parameters of pulmonary function indicating obstructive lung disease in the former case and restrictive lung disease in the latter.

Adult↗
PubMed1991

Anaphylactic reactions to a psyllium-containing cereal.

Historical data were obtained by questionnaire and telephone survey on 20 of 24 women with reported allergic reactions to a psyllium-containing cereal, Heartwise. Protein fractions from this new cereal, as well as from psyllium mucilloid and a psyllium-containing laxative, Metamucil, were extracted, quantitated, and separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Patients' sera were collected, and specific IgE and IgG antibodies to these psyllium antigens were detected by immunoblotting techniques. Of the 20 women evaluated, all but six were nurses. Eighteen (90%) of the women had historical and/or laboratory evidence of atopy. Exposures included ingestion or dispensing of psyllium-containing products. Only three women denied prior exposure to psyllium. Symptoms developed shortly after small amounts of the cereal were ingested and most commonly included moderate to severe wheezing, throat and chest tightness, and urticaria. All the women required medical therapy, 11 (55%) in an emergency room. Specific IgE and IgG antibodies to various psyllium protein fractions were documented in all the subjects. It was concluded that individuals sensitized by occupational exposure to psyllium dust are at high risk for allergic reactions to ingested psyllium-containing products.

Adult↗
PubMed1991

Evaluation of 99Tcm Technegas ventilation scintigraphy in the diagnosis of pulmonary embolism.

In the diagnosis of pulmonary embolism, perfusion lung scintigraphy offers high sensitivity but low specificity. The specificity can be significantly increased by the use of combined ventilation and perfusion studies. Most aspects of perfusion lung scintigraphy are uniformly accepted but the technique of ventilation imaging varies from centre to centre. This study describes a new technique for the performance of ventilation scintigraphy using a suspension of ultrafine carbon particles labelled with 99Tcm ("Technegas"). The technique combines the ready availability of 99Tcm and its optimal imaging properties with an easily administered radiopharmaceutical of particle size sufficiently small to deposit in the alveoli. Of 63 patients studied by conventional perfusion scintigraphy plus Technegas ventilation scintigraphy, images of diagnostic quality were obtained in all. 31 of these patients also had a ventilation study using 81Krm gas and in only one instance did the two methods of ventilation imaging lead to differing interpretations. We conclude that high quality diagnostic images may be obtained using this new technique, which can be made available on both a routine and an emergency basis, thus improving the service provided for patients suspected of having pulmonary embolism.

Adult↗
PubMed1990

A prospective study of genital infections in a family-planning clinic. 1. Microbiological findings and their association with vaginal symptoms.

A prospective study of genital infection was conducted in four inner-city family-planning clinics. Fifteen per cent of routine attenders had symptoms and signs of vaginal infection and many more women attended primarily because of symptoms. Among the women with both signs and symptoms, 70% had positive laboratory findings, Trichomonas vaginalis, Candida albicans and bacterial vaginosis being equally prevalent. Measurement of vaginal pH in the clinic was the single most useful clinical finding for directing empirical therapy. Among patients with a discharge confirmed on examination and an abnormally high pH, 72% had either T. vaginalis or bacterial vaginosis. Neisseria gonorrhoeae was isolated from 4% of women with, and 1% of those without, symptoms. We believe that it is worthwhile to investigate patients presenting to family-planning clinics with vaginal symptoms. No single specimen was found ideal for all pathogens, a cervical swab is better for gonococci and also for T. vaginalis but a vaginal swab is needed for candida and bacterial vaginosis.

Bacterial Infections↗