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Biomedical subjects

C E Reed

Publications and source records attributed to C E Reed.

At least 91 records · Page 5Linked to original sources
PubMed1990

Random coil scission rates determined by time-dependent total intensity light scattering: hyaluronate depolymerization by hyaluronidase.

A recently developed theory of the light scattering by random coils undergoing random scission is applied to the digestion of hyaluronate by hyaluronidase. The time dependence of the scattered light from solutions undergoing digestion was monitored. Working at a high angle with high molecular weight hyaluronate allowed the use of a powerful approximation for determining initial velocities and the Henri-Michaelis-menten coefficients, without explicit knowledge of the hyaluronate molecular weight, radius of gyration, second virial coefficient, or polydispersity. Effects due to a molecular weight dependent second virial coefficient and to non-Gaussian behavior are briefly considered. Assays were performed over nearly two orders of magnitude in substrate concentration. The initial velocities are compared with those obtained by a standard reducing sugar assay, which was performed on identical samples. The main advantages of the light scattering assay procedure over the more traditional assays are that many relatively high-precision data points can be quickly and automatically collected with simple apparatus, and that the technique is most sensitive for the initial period of digestion, where the other assays are least sensitive. The shapes of the scattering curves also provide evidence that hyaluronate in these solutions is not a stable double strand and that the hyaluronidase cleaves bond randomly. The curves also indicate that enzyme deactivation occurs, which accounts for the lower velocities yielded by the slower reductimetric assay, which is measured over longer initial periods.

Hyaluronic Acid↗
PubMed1990

Lack of suppression of IgE production by recombinant interferon gamma: a controlled trial in patients with allergic rhinitis.

Recent evidence suggests that interferon-gamma (IFN-gamma) is a potent inhibitor of IgE synthesis in rodents. We conducted a randomized, placebo-controlled, two-period clinical trial of human recombinant IFN-gamma in the treatment of allergic rhinitis. Forty-five adults with well-documented ragweed-allergic rhinitis were randomized into three groups of 15 adults each and received subcutaneous injections three times weekly. The first treatment period (4 weeks during the off season) began on April 18, 1988; the second treatment period (6 weeks during ragweed pollination) began on August 15, 1988. All subjects received the same treatment in both periods. Group 1 received 0.2 mg per injection of IFN, group 2 received 0.02 mg of IFN, and group 3 received placebo. One subject in group 1 and three subjects in group 2 withdrew because of adverse reactions, and three subjects withdrew for personal reasons. There were no significant differences in mean weekly symptom scores or supplemental medication scores among the three groups in either treatment period. Furthermore, there were no significant differences in the changes of serum IgE antibody to crude ragweed extract or in serum total IgE among the three groups during or before the ragweed-pollination season. These results indicate that this treatment regimen with IFN-gamma does not alter IgE production in patients with ragweed hay fever and indicate the need for further clinical research of lymphokine modulation of IgE production.

Adolescent↗
PubMed1990

Identification and partial characterization of the soybean-dust allergens involved in the Barcelona asthma epidemic.

Asthma epidemics in Barcelona, Spain, have been attributed to dust generated by the unloading of soybeans in the harbor. Sera of four different groups of 10 subjects in each group were studied: (1) patients attending an emergency room in Barcelona for an asthma attack on epidemic days, group A, (2) patients attending an emergency room for an attack on nonepidemic days, group B, (3) patients with asthma from other cities, group C, and (4) patients without asthma from Barcelona matched by age and sex with group A, group D. All subjects in group A had IgE to allergens in extracts of various soybean samples. In contrast, only one of the 10 subjects in each of groups B and C and none of those subjects in group D had IgE to uncleaned bean and hull extracts. Radioimmunoassay demonstrated that in sera from patients with asthma during an asthma outbreak reacted primarily to soybean hull and dust extracts. Sodium dodecyl sulfate-polyacrylamide and gel electrophoresis thin-layer isoelectrofocusing demonstrated protein bands of 97.4 to less than 14.4 kd and isoelectric point between 6 and 3.5. By Western blot and thin layer isoelectrofocusing/blotted radioimmunoisoelectrofocusing, IgE of patients with asthma during an asthma outbreak reacted weakly to two protein bands of molecular weight ranging from 42 to 21 kd, strongly to glycoprotein bands with molecular weight less than 14.4 kd, and isoelectric point less than 6, which appeared to be the major allergens.

Adolescent↗
PubMed1990

Variability of cat-allergen shedding.

To study the differences in total allergen shed, nine cats were placed individually in a lucite chamber with an air sampler attached for 1 hour. With a RAST-inhibition assay that used specific cat IgE antibodies from cat-sensitive subjects, we ranked the allergen production of each cat. From these nine cats, three high producers and one low producer were studied further. Each cat's allergens were collected for two to four separate 1-hour intervals on 6 different days. The high producers' samples remained high in allergen content, and the low producer's sample remained low. An additional eight cats were selected for similar longitudinal measurements, and allergens from each of these 12 cats were collected during four 1-hour intervals on 2 different days and assayed for total allergy units (AUs) by RAST inhibition and for the major cat allergen, Fel d I, by a two-site assay with a monoclonal antibody. Shedding, particularly by high producers, varied considerably from hour to hour. We found a hundredfold difference in AUs between the mean rate of shedding of the highest and lowest producers and a sixfold difference in Fel d I units. Variation in rate of shedding of Fel d I accounted for about half the variation of shedding of AUs. Allergen shedding varies not only between cats but also in the same cat during the course of a day and between days. Male cats shed more than female cats.

Air Pollutants↗
PubMed1990

Role of ventilation, air filtration, and allergen production rate in determining concentrations of rat allergens in the air of animal quarters.

Concentration of any substance in the air of a room is determined by the ratio between the rates of its production and removal. Thus, high concentrations can result from high production, low removal, or a combination of the two. Air filtration can supplement ventilation in removing allergens from the air. Control of aeroallergen exposure at any particular location would be more rational and effective if the contribution of production, ventilation, and filtration were known. Using immunochemical assays for rat urinary protein allergen, we measured the rate of production by individual rats and the concentration of allergens in the air of rat animal quarters where the ventilation rate was about 15 changes per hour. We introduced two different high-efficiency filtration systems that provided additional clean air changes up to a maximum of 127 changes per hour. Male rats shed about 20 ng/min of allergen. Because of this high rate of production, substantial reduction in rooms that housed large numbers of animals required the very high air-exchange rates that were achieved with laminar flow small animal isolator racks. Measured concentrations agreed well with concentrations calculated from a mass balance equation whose terms included numbers of animals in the room, production rate by individual animals, and rates of ventilation and filtration. We suggest that this principle of considering both production and removal rates applies not only to devising means of reducing levels of rat allergens in rat rooms, but generally to other indoor allergens as well.

Air Pollutants, Occupational↗
PubMed1990

Myasthenia gravis: a review with emphasis on the potential role of thymectomy.

Review of our results with thymectomy for myasthenia gravis supports the role of early surgery for this debilitating and often lethal disease. The data presented here confirm the fact that thymectomy has rare complications and low operative mortality. Approximately 80 percent of patients with myasthenia gravis can expect clinical improvement with surgery, which also offers a chance for complete remission.

Adolescent↗
PubMed1989

The effects of pH on hyaluronate as observed by light scattering.

Hyaluronate was investigated over a wide pH range, and at near zero and intermediate ionic strength, using dynamic and total intensity light scattering. Commercially obtained rooster comb hyaluronate was purified, and solutions were prepared in pure water by low-power bath ultrasonication and subsequent filtering. These solutions were of low polydispersity and appeared to contain single molecules of hyaluronate. Despite the absence of added electrolyte, these solutions yielded well-behaved Zimm plots. Increasing ionic strength and changing pH decreased radii of gyration and increased diffusion constants. Except for what appeared to be slow hydrolysis at either extreme of pH, molecular weights remained constant under all pH and ionic strength conditions. Under all solvent conditions investigated, diffusion coefficients increased with decreasing hyaluronate concentration. Unsonicated, lightly centrifuged solutions without added electrolyte were polydisperse, and their light scattering intensity was dominated by what appeared to be stable hyaluronate aggregates. The results are interpreted in terms of the polyelectrolyte properties of hyaluronate and its tendency to form stable entanglements, especially at low ionic strength. Previous light scattering studies in the literature on hyaluronate have shown widely varying results. The present article briefly reviews this literature and attempts to explain the variation among the previous results, emphasizing the Kuhn statistical segment length as an indicator of whether results are influenced by polydispersity or contaminants causing hyaluronate aggregation.

Electrochemistry↗
PubMed1989

Surgical resection for complications of pulmonary tuberculosis.

From 1975 through 1984, 24 patients at the Medical University of South Carolina underwent surgical resection for complications of pulmonary tuberculosis. The complications fell into three major categories: persistent or drug-resistant disease, bronchiectasis, and hemoptysis. The major indications for surgical intervention included hemoptysis (14 patients), drug resistance (5), possible neoplasm (3), and bronchiectasis (2). Impaired pulmonary function was common. Surgical therapy generally necessitated lobectomy, sometimes resulted in substantial blood loss, and had a total major and minor complication rate of 46%. Despite these problems, the long-term prognosis after successful resection is good.

Adult↗
PubMed1989

Correlations between levels of mite and cat allergens in settled and airborne dust.

Thirty homes in Rochester, Minn., 20 of which housed cats, were studied to compare cat and mite allergen concentrations in airborne and settled dust. With Air Sentinels in the bedroom and living room for airborne collections, and a Sample Vac for collections from living room carpet and bedroom mattress, immunochemical quantifications of each were made with various radiometric assays with polyclonal and monoclonal antibodies. The most significant correlations were found between airborne mite in the bedroom and living room (p less than 0.001) and airborne mite in the bedroom and dust from the bedroom mattress (p less than 0.001). Most houses had specific epitopes of both Dermatophagoides pteronyssinus and D. farinae, but D. farinae was present in greater amounts. In seven houses we found greater than 10 micrograms of group I mite allergen per gram of settled dust, indicating that some houses in Minnesota have concentrations of mite allergens high enough to cause allergic disease, even in the winter. Clinical interpretation of these data on air levels is hampered by uncertainty as to whether symptoms are more closely related to average steady-state exposure, which we measured, or to brief heavy concentrations. Further epidemiologic studies are needed to define the concentration of mite and cat allergens in the air that are risk factors for allergic disease. The concentration of cat allergen correlated with mite allergen in the air, but not in settled dust, presumably reflecting the fact that both are influenced by ventilation rate.

Air↗
PubMed1989

Guidelines for the clinical evaluation of hypersensitivity pneumonitis. Report of the Subcommittee on Hypersensitivity Pneumonitis.

In general, a history of exposure to "moldy" hay, birds, or other incriminated occupational or environmental inhalants in a patient with clinical and radiologic features consistent with HSP should lead to the demonstration of serum precipitins to the suspected antigen and an established diagnosis, confirmed by avoidance of the agent involved. Occasionally, other diagnostic procedures are required. The diagnosis is often difficult in domestic exposures, such as humidification and air conditioning systems. A careful environmental history is essential, and at times the physician must inspect the patient's environment personally. In most cases, the diagnosis is established if (1) the history and physical findings and pulmonary function tests indicate an interstitial lung disease, (2) the x-ray film is consistent, (3) there is exposure to a recognized cause, and (4) there is antibody to that antigen. In other exceptional circumstances, bronchoalveolar lavage may help. Biopsy is rarely needed. Special environmental studies and identification of new antigens require research facilities. Provocation tests are research procedures, not necessary for the diagnosis, and not needed in contested workmen's compensation adjudications.

Alveolitis, Extrinsic Allergic↗
PubMed1989

Proper use of aerosol corticosteroids to control asthma.

Aerosol glucocorticoids are highly effective in the treatment of bronchial asthma. Clinically apparent systemic hypercortisolism is virtually nonexistent in patients who receive such therapy, although local effects of candidiasis or dysphonia may occur. Treatment failures can often be attributed to poor patient compliance or incorrect use of the pressurized aerosol inhaler. The addition of a spacer device to the inhaler improves the technique and the results in many patients. Furthermore, many patients with asthma require 2 or 3 times the conventional dose of aerosol corticosteroids for optimal control of pulmonary function. Careful coaching is essential for the successful use of aerosol corticosteroids.

Administration, Inhalation↗