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Biomedical subjects

R Patterson

Publications and source records attributed to R Patterson.

At least 163 records · Page 9Linked to original sources
PubMed1989

Viewing distance affects stereoscopic tilt created with spatial frequency disparity.

A controversy exists as to whether stereoscopic tilt created with interocular differences in spatial frequency is based on perception of spatial frequency disparity or positional disparity. To determine which hypothesis is correct, we investigated the influence of viewing distance on perceived tilt. Tilt was induced by having observers view, at three viewing distances, dichoptic spatial frequency grating patterns differing in frequency by 25%. By appropriate physical scaling of the size of the patterns, their spatial frequency and angular width remained unchanged as distance varied. Under such conditions, the spatial frequency disparity hypothesis predicts no effect of distance, whereas the positional disparity hypothesis predicts a significant effect of distance (due to stereoscopic depth constancy) on the magnitude of tilt. The results showed that perceived tilt does covary with distance, a result consistent with only the positional disparity hypothesis.

Adolescent↗
PubMed1989

Effects of combined receptor antagonists of leukotriene D4 (LTD4) and platelet-activating factor (PAF) on rhesus airway responses to LTD4, PAF and antigen.

Rhesus monkeys with IgE-mediated asthmatic-type responses to Ascaris suum antigen were pretreated with a combination of 2 receptor antagonists to leukotriene D4 (LTD4) and platelet-activating factor (PAF). This combination of anti-LTD4 and anti-PAF was shown to inhibit airway responses to either LTD4 or PAF in separate experiments in these Ascaris airway-reactive animals. When the same combination of LTD4 and PAF receptor antagonists was used to pretreat the same animal prior to aerosol challenge with Ascaris antigen we could not demonstrate inhibition of the antigen-induced airway response. Thus, combined receptor blockade for LTD4 and PAF did not alter IgE-mediated acute airway responses to antigen in this species. We review the current status of rhesus asthma and LTD4 and PAF receptor antagonist activity in this model.

Animals↗
PubMed1989

Visual persistence and adult dyslexia.

Visual persistence was investigated in adults with and without dyslexia in order to determine whether the adults with dyslexia demonstrate problems similar to those found in childhood dyslexia. Using a temporal separation threshold measure and procedures derived from signal detection theory, sensitivity to sequentially presented form information was determined for the two types of adults. The results showed that the sensitivity of the adults with dyslexia was impaired relative to that of the nondisabled adults when parts of a test stimulus were presented to adjacent retinal areas. This result suggests that, under certain conditions, visual persistence is longer for adults with dyslexia. The results are discussed within the context of a recent theory of dyslexia (Lovegrove, Martin & Slaghuis, 1986) that incorporates the operation of sustained and transient visual mechanisms.

Adolescent↗
PubMed1989

The impact of prednisone in life-threatening idiopathic anaphylaxis: reduction in acute episodes and medical costs.

Two patients with frequent episodes of well documented life-threatening idiopathic anaphylaxis were studied. Despite prior treatment with antihistamines and self-administered epinephrine, both patients continued to have episodes of anaphylaxis. At the time of presentation to the Northwestern University Allergy Service, prednisone and antihistamines with or without sympathomimetics were started. Described in this report are the substantial reductions in the frequency of hospitalizations, emergency room visits, and anaphylactic episodes after our medical management was instituted.

Acute Disease↗
PubMed1989

Diphenylmethane diisocyanate hypersensitivity pneumonitis: a serologic evaluation.

We describe the clinical and immunologic evaluation of a steel plant maintenance supervisor who had clinical symptoms consistent with hypersensitivity pneumonitis. No antigen was obvious but after a thorough occupational history and review of the industrial hygiene data, the most likely antigen appeared to be diphenylmethane diisocyanate. Precipitating antibodies were not detected in the worker's serum; however, significant antibody levels of IgG specific for diphenylmethane diisocyanate-human serum albumin were detected by other immunoassays. This case highlights the importance of a thorough occupational history and an aggressive laboratory immunologic evaluation in identifying the offending agent in a worker with hypersensitivity pneumonitis. Hypersensitivity pneumonitis due to an inhaled reactive chemical may be present without precipitins demonstrated in vitro due to the nature of the haptenized chemical protein conjugate or the concentration of IgG antibody.

Alveolitis, Extrinsic Allergic↗
PubMed1989

Baker's asthma: report of an unusual case.

Using immunologic techniques recently available, we report the evaluation of baker's asthma due to wheat flour and demonstrate the usefulness of these techniques in occupational asthma. The diagnosis of baker's asthma was very important in this case, as even a trial of avoidance of work exposure was not possible because of the social and economic factors involved. A commercial wheat extract was obtained and the wheat flour actually used at the work site was extracted. Prick skin testing with each of these extracts resulted in positive wheal and flare responses. Enzyme linked immunosorbent assay and inhibition assays were performed to assess the worker's antibody response to wheat flour and wheat extracts. Significant specific IgE and IgG levels to the wheat flour and wheat extracts were detected in the worker's serum. Because of unique psychosocial and educational factors, this worker was unable to change occupations. Even with respiratory protection, she continued to be symptomatic. She is currently controlled on bronchodilators and inhaled steroids.

Antibody Specificity↗
PubMed1989

Effect of capsulectomy on the hemodynamics and viability of random-pattern skin flaps raised on expanded skin in the pig.

Skin flaps constructed on expanded skin usually include the underlying capsular tissue. It has been hypothesized that capsulectomy may jeopardize the viability of the expanded skin flap. The experiments reported herein were designed to test this hypothesis. Specifically, we studied the hemodynamics and viability of random-pattern skin flaps (8 X 20 cm) raised on delayed bipedicle flaps (group A) and on expanded skin pockets with capsulectomy at the time of flap elevation (group B) or with intact underlying capsular tissue (group C). Each group was randomly assigned to each flank in 16 pigs. Skin pockets were expanded by inflation of subcutaneous silicone tissue expanders with sterile saline (299 +/- 7 ml; X +/- SEM) over a period of 3 weeks. At the end of this period, the bipedicle flaps were constructed. Eight days later, random-pattern skin flaps were raised on bipedicle flaps and skin pockets. The length and area of skin flap viability, judged by the fluorescein dye test performed 1 day postoperatively, were not significantly different (p greater than 0.05) among groups A, B, and C (n = 31 to 32). There also were no significant differences (p greater than 0.05) in total skin capillary blood flow measured 1 day postoperatively (A = 2.6 +/- 0.4, B = 2.4 +/- 0.4, and C = 2.7 +/- 0.6 ml/min per flap; n = 15 to 16) and in skin viability assessed 7 days postoperatively (A = 74 +/- 2, B = 75 +/- 2, and C = 76 +/- 2 percent; n = 16) among delayed skin flaps and skin flaps raised on expanded skin pockets with or without capsulectomy. The results of this flap viability study were confirmed in 5 minipigs in a separate experiment. We conclude that capsulectomy did not have a detrimental effect on the hemodynamics and viability of random-pattern skin flaps raised on expanded skin. Furthermore, we hypothesize that skin flaps raised on expanded skin are similar to delayed skin flaps in that the skin blood flow is optimally augmented; therefore, the capsular tissue does not add significant blood supply to the overlying skin.

Animals↗
PubMed1989

Outcomes of pregnancy in adolescents with severe asthma.

Asthma in adolescent pregnancies is not rare and may make patient management difficult, especially since mortality from asthma is of particular concern in the adolescent age group. We present a series of 21 pregnant adolescents with severe asthma. During 28 pregnancies, there were 56 exacerbations of asthma, including 22 hospitalizations and 20 emergency room visits. For 18 (64%) of the 28 pregnancies, outpatient systemic corticosteroids were administered, and inhaled corticosteroids were prescribed for 8 (29%). Factors associated with exacerbations included respiratory tract infections (59%) and noncompliance with medical regimens (27%). There were no maternal or fetal deaths or evidence for intrauterine growth retardation. Two infants were premature, with one experiencing acute respiratory distress syndrome. Aggressive treatment of asthma and associated respiratory tract infections, as well as careful ambulatory care, to encourage patient compliance are advisable to achieve a favorable maternal-fetal outcome.

Adolescent↗
PubMed1988

Idiopathic anaphylaxis: classification, evaluation, and treatment of 123 patients.

The manifestations, evaluation, treatment, and course of 123 patients with idiopathic anaphylaxis (IA) are described for a total of 374 patient years of our management. Observation of this group of patients resulted in the description and classification of IA as one or more episodes of generalized IA with multiple systemic manifestations or IA with life-threatening angioedema of the tongue or larynx. Therapy is based on the frequency of episodes. Acute therapy is appropriate for infrequent episodes, but prophylactic therapy is indicated for frequent episodes. In patients with frequent episodes, remissions can be induced and maintained with prednisone. Prolonged remissions may occur after prednisone is stopped. There have been no deaths from IA in patients managed by our service. By definition, there is no identifiable antigen responsible for episodes of IA, and there is no underlying disease in these patients. A mast cell basophil-activation mechanism is suggested. IA may represent the most severe form of a spectrum of diseases that include idiopathic urticaria and angioedema.

Adolescent↗
PubMed1988

Antibody response to trimellityl hemoglobin in trimellitic anhydride-induced lung injury.

Sprague-Dawley rats were exposed to trimellitic anhydride by inhalation, and the antibody response to trimellityl (TM)-conjugated hemoglobin (HB) and TM rat serum albumin (RSA) was compared. Groups of rats were exposed to trimellitic anhydride by inhalation 6 hours per day for 2, 6, or 10 days at 100 micrograms/m3 and compared to a control group exposed to filtered air. The IgG antibody response to TM-HB in both serum and bronchoalveolar lavage (BAL) fluid was measured with ELISA. IgG antibody levels to TM-HB rose significantly throughout the exposure. A positive correlation was found between IgG to TM-HB in serum and BAL fluid. In addition, this response in both serum and BAL fluid correlated with the IgG antibody response to TM-RSA. Cross-inhibition studies indicated the existence of shared antigenic determinants on TM-RSA and TM-HB. The IgG antibody to both antigens was specific for new antigenic determinants and not for the TM hapten.

Animals↗