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Biomedical subjects

R Patterson

Publications and source records attributed to R Patterson.

At least 73 records · Page 4Linked to original sources
PubMed1997

Recurrence of allergic bronchopulmonary aspergillosis in the posttransplant lungs of a cystic fibrosis patient.

Cystic fibrosis (CF) is an autosomal recessive disease of exocrine origin. Allergic bronchopulmonary aspergillosis (ABPA) is an immunologic disorder caused by colonization of the airways with Aspergillus fumigatus. A fumigatus has been cultured from posttransplant lungs in CF patients. Colonization of posttransplant lung with Aspergillus is a recognized phenomenon. In this case report, however, we present a patient who developed ABPA both before and after lung transplant. This patient meets the criteria for ABPA based on serologic results. ABPA may be a complication in post-CF lung transplant patients and serologic analysis should be considered when eosinophilia and pulmonary infiltrates or decline in lung function occurs.

Adult↗
PubMed1997

A bradykinin antagonist inhibits both bradykinin- and the allergen-induced airway response in primates.

Bradykinin is a mediator of bronchoconstriction and may play a role in the development of the asthmatic response after antigen challenge. Our objective was to study the effectiveness of NPC 17731 as a specific bradykinin beta 2-receptor antagonist and as an antagonist of the allergen-induced early phase of asthma. A primate model was used for all studies. Intracutaneous end-point titrations were performed with bradykinin. A shift of the bradykinin end-point titer was seen when NPC 17731 was injected by the intradermal route prior to performing the end-point titration. Using an aerosolized bradykinin or Ascaris suum antigen airway threshold challenge system, inhibition of the bradykinin or Ascaris airway response was evaluated after pretreatment with aerosolized NPC 17731. NPC 17731 proved to be a safe, effective specific bradykinin receptor antagonist in both cutaneous and airway challenges. NPC 17731 was able to inhibit the antigen-induced airway response in the primate. Bradykinin may play a larger role in mediating the early phase of the antigen-induced asthmatic response than previously was appreciated.

Animals↗
PubMed1997

The effects of time and light exposure on contact and pressure measurements using Fuji prescale film.

The search for methods to demonstrate and accurately measure contact area and pressure within human joints has been and remains an active one. Presenssor is a measuring system developed by Fuji Photo Film Co., Ltd. and used in medical applications. The color intensity fades with time and exposure to light. These changes have not been well documented despite the increasing use of Fuji film in biomedical research. These changes in color intensity provide a source of error in the calculated measurements. The known variability of the color density of film exposed to light and air can be measured and predicted. Methods to control and improve the accuracy and reliability of study data are suggested. Film was exposed to three different amounts of pressure and placed into one of four subgroups: exposed to light and taped or not taped, and stored in the dark and taped or not taped. Fading of the color density was seen after only a few hours of exposure to light when the film was left untaped. When the film was taped, a slight darkening was seen. For the best accuracy and reliability, the film should be digitized or analyzed within eight hours of exposure to pressure.

Bias↗
PubMed1996

Idiopathic anaphylaxis: a purely internal reaction.

Episodes are clinically identical to classic anaphylaxis, yet no external allergen or psychological disorder can be identified as the cause of the patient's symptoms and signs. Combinations of a corticosteroid, an H1-histamine receptor blocker, and a sympathomimetic amine are highly effective at inducing control and can often achieve a remission.

Albuterol↗
PubMed1996

Will operate for food.

After spending 15 years in university, Dr. Robert Patterson recently received the right to write FRCSC after his name, and then began to look for gainful employment as a general surgeon. It was a long and frustrating search. He recounts how he finally found work in northern Alberta, and wonders if next year's residents will encounter the same shortage of opportunities that he discovered.

Canada↗
PubMed1996

Disparity tuning of the stereoscopic (cyclopean) motion aftereffect.

Across five experiments this study investigated the disparity tuning of the stereoscopic motion aftereffect (adaptation from moving retinal disparity). Adapting and test stimuli were moving and stationary stereoscopic grating patterns, respectively, created from dynamic random-dot stereograms. Observers adapted to moving stereoscopic grating patterns presented with a given disparity and viewed stationary test patterns presented with the same or differing disparity to examine whether the motion aftereffect is disparity contingent. Across experiments aftereffect duration was greatest when adapting motion and test pattern both were presented with zero disparity and in the plane of fixation. Aftereffect declined as disparity of adapting motion and/or test pattern increased away from fixation, even under conditions in which depth position of adapt and test was equal. This argues against a relative depth separation explanation of the decline, and instead suggests that the amount of adaptable substrate decreases away from fixation.

Adaptation, Physiological↗
PubMed1996

Direction-selective adaptation and simultaneous contrast induced by stereoscopic (cyclopean) motion.

Across four experiments, this study investigated direction-specific adaptation and simultaneous contrast induced by moving binocular disparity information (stereoscopic motion). The stimuli were moving arrays of stereoscopic dots created from dynamic random-element stereograms. Experiments 1 and 2 examined the effects of adaptation to motion in a given direction on the apparent direction of test motion. Results showed that the direction of test motion appeared repulsed away from the direction of adapting motion (repulsion aftereffect) by as much as 20 deg or more when directions of adapt and test were similar. Experiment 3 investigated transfer of the repulsion aftereffect across the stereoscopic and luminance domains by employing stereoscopic adapting motion and luminance test motion or vice versa. Results showed that the repulsion aftereffect transferred across the two stimulus domains. Experiment 4 investigated direction-specific contrast by measuring the perceived direction of two stereoscopic arrays presented simultaneously and moving in different directions. Results showed that the directions of the arrays appeared repulsed away from one another when their directions were similar. Taken together, these results suggest that the direction of stereoscopic motion is coded in the activity of directionally selective mechanisms, as is the case for luminance-domain motion. Transfer of the repulsion aftereffect between stereoscopic and luminance domains indicates the two kinds of motion perception are mediated by a common substrate.

Adaptation, Ocular↗
PubMed1996

Enduring stereoscopic motion aftereffects induced by prolonged adaptation.

This study investigated the effects of prolonged adaptation on the recovery of the stereoscopic motion aftereffect (adaptation induced by moving binocular disparity information). The adapting and test stimuli were stereoscopic grating patterns created from disparity, embedded in dynamic random-dot stereograms. Motion aftereffects induced by luminance stimuli were included in the study for comparison. Adaptation duration was either 1, 2, 4, 8, 16, 32 or 64 min and the duration of the ensuing aftereffect was the variable of interest. The results showed that aftereffect duration was proportional to the square root of adaptation duration for both stereoscopic and luminance stimuli; on log-log axes, the relation between aftereffect duration and adaptation duration was a power law with the slope near 0.5 in both cases. For both kinds of stimuli, there was no sign of adaptation saturation even at the longest adaptation duration.

Adaptation, Ocular↗
PubMed1996

A fatality from idiopathic anaphylaxis.

BACKGROUND: Idiopathic anaphylaxis by definition is a form of anaphylaxis where no identifiable stimulus can be found. In our series of over 350 patients with idiopathic anaphylaxis there have been no reported deaths. OBJECTIVE: To report the clinical course of the first fatality in our series from idiopathic anaphylaxis. METHODS: A patient was evaluated for idiopathic anaphylaxis and started on our previously published protocol of corticosteroids, sympathomimetics, and antihistamines. RESULTS: Despite following our protocol--which has been effective in decreasing the number of emergency room visits, hospitalizations, and intensive care unit admissions--controlling the disease, and placing a high percentage of patients into remission, the patient with idiopathic anaphylaxis died unexpectedly after experiencing symptoms similar to previous episodes of idiopathic anaphylaxis. CONCLUSION: This is the first reported fatality from idiopathic anaphylaxis in our extensive series.

Adult↗
PubMed1996

An intervention program to reduce the hospitalization cost of asthmatic patients requiring intubation.

BACKGROUND: Asthma is the single disease that accounts for the largest proportion of total health care cost in the US. OBJECTIVE: To analyze whether an asthma management program affected the cost of subsequent asthma care for patients in whom intubation had been necessary. METHODS: We evaluated patients with asthma who (1) had required intubation for treatment of status asthmaticus; (2) were 45 years old or younger; (3) had regular follow-up visits in our clinic for 1 year after initial evaluation; and (4) had complete medical records 1 year before and 1 year after the intervention for our evaluation. Medical costs of asthma treatment for each patient were determined for 1 year before and 1 year after intervention. The program included patient education, regular outpatient visits, specialist care, and access to the Allergy Immunology emergency call service. The outcome measures were the total cost of care, inpatient hospitalizations, outpatient services, emergency services, and medicine costs. RESULTS: Nine patients [mean age 19.6 years (SD = 9.9)] fulfilled the criteria (six women and three men). The mean duration of asthma was 14.0 years (SD = 9.7). The mean total cost of care decreased from $43,066 to $4,914 (t = -4.53, P < .001) and inpatient hospitalization costs decreased from $40,253 to $1,926 (t = -4.50, P <.001). There was, however, no significant difference in the mean pre-intervention versus post-intervention cost of emergency services, outpatient services, or medicine costs. CONCLUSIONS: The intervention--which included education, specialist care, regular outpatient visits, and access to an emergency call service--significantly reduced the cost of asthma care in our population of patients intubated for asthma.

Adolescent↗
PubMed1996

Idiopathic anaphylaxis: a series of 335 cases.

BACKGROUND: Idiopathic anaphylaxis is anaphylaxis with no definable etiology and no trigger by exogenous allergens. Initially described in 1978, idiopathic anaphylaxis has been subsequently characterized and treatment protocols have been established. OBJECTIVE: The demographics and course of 335 patients (225 previously reported) treated with prednisone, hydroxyzine, and albuterol are now reported. RESULTS: Ages ranged from 5 to 83 years. There were nine new pediatric patients in this series totaling 14 (4.2%). Atopy was common (48%) with 34 new patients with asthma. The duration of symptoms prior to presentation ranged from three days to 27 years. One hundred thirty-two patients with idiopathic anaphylaxis were available for follow-up. Twenty of these are currently receiving prednisone for control of idiopathic anaphylaxis, seven of them as part of their initial therapy, and ten for control of recurrence of symptoms. Three patients required continuous alternate day prednisone for control of symptoms (corticosteroid-dependent idiopathic anaphylaxis). Of the 335 patients, there were no longer any patients with the diagnosis of malignant idiopathic anaphylaxis defined as requiring prednisone, 20 mg daily, or 60 mg every other day, for control of idiopathic anaphylaxis. Of the six patients previously diagnosed with malignant idiopathic anaphylaxis, five no longer required prednisone and one has a decreased prednisone requirement of 20 mg on alternate days. Hospital visits were significantly reduced by the management regimens. There were no fatalities from idiopathic anaphylaxis in this series. CONCLUSIONS: The incidence of idiopathic anaphylaxis is increasing in our practice with more patients being evaluated each year. During 1104 patient years of observation (the longest period of single patient observation being 24 years), no inciting agent has been found responsible for the anaphylactic symptoms. Prognosis continues to remain good with the majority of patients achieving remission with pharmacotherapy.

Adolescent↗
PubMed1996

A time domain description for the pitch strength of iterated rippled noise.

Two versions of a cascaded add, attenuate, and delay circuit were used to generate iterated rippled noise (IRN) stimuli. IRN stimuli produce a repetition pitch whose strength relative to the noise can be varied by changing the type of circuit, the attenuation, or the number of iterations in the circuit. Listeners were asked to discriminate between various pairs of IRN stimuli which differed in the type of network used to generate the sounds or the number of iterations (n = 1, 2, 3, 4, 7, and 9). Performance was determined for IRN stimuli generated with delays of 2, 4, and 8 ms and for four bandpass filter conditions (0-2000, 250-2000, 500-2000, and 750-2000 Hz). Some IRN stimuli were extremely difficult to discriminate despite relatively large spectral differences, while other IRN stimuli produced readily discriminable changes in perception, despite small spectral differences. these contrasting results are inconsistent with simple spectral explanations for the perception of IRN stimuli. An explanation based on the first peak of the autocorrelation function of IRN stimuli is consistent with the results. Simulations of the processing performed by the peripheral auditory system (i.e., interval histograms and correlograms) produce results which are consistent with the involvement of these temporal processes in the perception of IRN stimuli.

Humans↗
PubMed1996

Management of asthma in the geriatric population.

Asthma remains an important cause of morbidity and mortality for patients of all ages, but it may be of particular concern in geriatric patients as the aging population increases. Asthma may vary in severity from mild to such severity that ventilatory support is required. However, with proper medical management, asthma of most patients can be adequately controlled. Although there are similarities in managing younger patients with asthma, special problems occur in the geriatric population.

Administration, Inhalation↗