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Biomedical subjects

R Patterson

Publications and source records attributed to R Patterson.

At least 55 records · Page 3Linked to original sources
PubMed1998

Malignant cough equivalent asthma: definition and case reports.

BACKGROUND: Cough equivalent asthma is a cause for chronic cough and usually responds to corticosteroid therapy. Oral corticosteroids are employed in a diagnostic-therapeutic trial and inhaled corticosteroids are employed in maintenance therapy. In certain cases the cough may be especially severe and require escalated doses of oral corticosteroids for initial control. This is labeled malignant cough equivalent asthma. OBJECTIVE: To define malignant cough equivalent asthma, provide two case reports, and identify features that should alert physicians to consider the possibility of malignant cough equivalent asthma. CASE REPORTS: We report two patients who presented complaining of chronic cough that was disruptive of sleep and normal activities, and in one patient prompted an emergency room visit and later hospitalization. The patients underwent evaluation with history, physical examination, and laboratory testing as indicated. Other causes for chronic cough were ruled out by appropriate testing, or were treated, and patients did not respond to usual corticosteroid treatment for cough equivalent asthma. These patients were considered to have a more severe form of cough equivalent asthma and did respond to treatment with higher doses of oral corticosteroids. CONCLUSION: Malignant cough equivalent asthma is a cause of chronic cough that is disruptive to sleep or normal activities, may lead to emergency room visits or hospitalization, and requires escalated doses of oral corticosteroids for initial control.

Adrenal Cortex Hormones↗
PubMed1998

The role of the envelope in processing iterated rippled noise.

Iterated rippled noise (IRN) is generated by a cascade of delay and add (the gain after the delay is 1.0) or delay and subtract (the gain is -1.0) operations. The delay and add/subtract operations impart a spectral ripple and a temporal regularity to the noise. The waveform fine structure is different in these two conditions, but the envelope can be extremely similar. Four experiments were used to determine conditions in which the processing of IRN stimuli might be mediated by the waveform fine structure or by the envelope. In experiments 1 and 3 listeners discriminated among three stimuli in a single-interval task: IRN stimuli generated with the delay and add operations (g = 1.0), IRN stimuli generated using the delay and subtract operations (g = -1.0), and a flat-spectrum noise stimulus. In experiment 2 the listeners were presented two IRN stimuli that differed in delay (4 vs 6 ms) and a flat-spectrum noise stimulus that was not an IRN stimulus. In experiments 1 and 2 both the envelope and waveform fine structure contained the spectral ripple and temporal regularity. In experiment 3 only the envelope had this spectral and temporal structure. In all experiments discrimination was determined as a function of high-pass filtering the stimuli, and listeners could discriminate between the two IRN stimuli up to frequency regions as high as 4000-6000 Hz. Listeners could discriminate the IRN stimuli from the flat-spectrum noise stimulus at even higher frequencies (as high as 8000 Hz), but these discriminations did not appear to depend on the pitch of the IRN stimuli. A control experiment (fourth experiment) suggests that IRN discriminations in high-frequency regions are probably not due entirely to low-frequency nonlinear distortion products. The results of the paper imply that pitch processing of IRN stimuli is based on the waveform fine structure.

Attention↗
PubMed1998

Hypersensitivity pneumonitis due to humidifier disease: seek and ye shall find.

STUDY OBJECTIVES: This study reports a classic case of hypersensitivity pneumonitis (HP) with classic histologic changes in lung tissue and the research used to identify the causative antigens. DESIGN: A patient with clinical, radiographic, pulmonary function abnormalities and a lung biopsy consistent with HP had no identifiable antigen exposure. SETTING: Evaluation of the patient's activities provided no suggestion of antigen exposure. Her home was evaluated. It was found that her humidifier ran continually without being cleaned but water was added periodically. MEASUREMENTS: Serologic analysis demonstrated precipitating antibodies against her humidifier water and ten antigens in the hypersensitivity lung disease serologic panel. CONCLUSION: Removal of the humidifier, cleaning of the house, and a course of prednisone resulted in the return of the patient to a normal state.

Aged↗
PubMed1998

A computerized reminder for prophylaxis of deep vein thrombosis in surgical patients.

OBJECTIVE: To measure the effect of a computerized reminder system on the rate of deep vein thrombosis (DVT) prophylaxis in surgical patients. DESIGN: A prospective trial to measure change in compliance compared to historic controls. MEASUREMENTS: LDS Hospital surgeons developed local consensus as to which procedures should have DVT prophylaxis. The historic rate of prophylaxis for the procedures was measured through a database search of patient records. A computerized reminder system was then implemented which utilized an expert knowledge base and a time drive mechanism to flag surgical cases for DVT prophylaxis. For eligible patients, a DVT reminder appeared on the operating room schedule; surgical staff used this as a guide to apply prophylaxis. During the 3 month trial the rate of DVT prophylaxis was remeasured and compared to the pre-intervention rate. RESULTS: The pre-intervention rate of DVT prophylaxis over a 3 month period was 85.2% (785 of 921 eligible cases). For the 3 months following the introduction of the computerized reminder, compliance with DVT prophylaxis increased to 99.3% (1084 of 1092 eligible cases). The difference between the historic controls and the study subjects was highly significant (p < 0.001). CONCLUSION: A computerized reminder is an effective method of increasing the rate of DVT prophylaxis in surgical patients.

Anticoagulants↗
PubMed1997

Ileal microvillar protein villin is tyrosine-phosphorylated and associates with PLC-gamma1. Role of cytoskeletal rearrangement in the carbachol-induced inhibition of ileal NaCl absorption.

In ileal absorptive cells, carbachol inhibits NaCl absorption and its component brush border Na+/H+ exchanger, acting via basolateral membrane receptors. This carbachol effect involves (i) activation of brush border phosphatidylinositol 4,5-bisphosphate-specific phospholipase C (PLC) activity and brush border but not basolateral membrane translocation of PLC-gamma1 (Khurana, S., Kreydiyyeh, S., Aronzon, A., Hoogerwerf, W. A., Rhee, S. G., Donowitz, M., and Cohen, M. E. (1996) Biochem. J. 313, 509-518); and (ii) brush border tyrosine kinase(s) because mucosal but not serosal addition of the tyrosine kinase inhibitor genistein prevents the carbachol-induced inhibition of NaCl absorption and brush border Na+/H+ exchange. In the present work we identify a pool of villin (a brush border actin-binding protein) in the microvillus membrane fraction of rabbit ileum; this pool of villin is tyrosine-phosphorylated and associates with brush border membrane PLC-gamma1. Villin is present both in the Triton X-100-soluble and -insoluble fractions of the brush border. The Triton X-100-soluble pool is approximately 4-fold smaller than the brush border pool of villin that is present in the Triton X-100-insoluble fraction. Only the villin present in the Triton X-100-soluble fraction of ileal villus brush border associates with PLC-gamma1 and is tyrosine-phosphorylated. Carbachol increases the tyrosine phosphorylation of villin rapidly (as early as 30 s) and transiently. Carbachol also increases the amount of tyrosine-phosphorylated villin that associates with PLC-gamma1. These studies demonstrate that carbachol effects on NaCl absorption are accompanied by an increase in brush border PLC-gamma1 association with villin and an increase in tyrosine phosphorylation of villin. To study the role of cytoskeletal rearrangement in carbachol-induced inhibition of NaCl absorption, we used the F-actin stabilizing drug jasplakinolide. Jasplakinolide prevents the carbachol inhibition of ileal NaCl absorption. This suggests that F-actin severing is necessary for carbachol to inhibit ileal villus NaCl absorption. Since villin is known to sever actin, these studies suggest a role for villin in the signaling cascade that begins at the basolateral membrane with carbachol binding to its receptor and ends at the apical membrane in inhibition of NaCl absorption.

Actins↗
PubMed1997

Airways obstruction in patients with long-term asthma consistent with 'irreversible asthma'.

OBJECTIVE: To describe a series of eight patients with long-term asthma and pulmonary function consistent with "end-stage," irreversible obstruction. DESIGN: Retrospective descriptive analysis of patients with severe asthma. SETTING: A university-based allergy-immunology service with a large population of corticosteroid-dependent patients with asthma. PATIENTS: Eight patients with long-standing asthma and apparently irreversible airways obstruction despite long-term oral and inhaled corticosteroid therapy. MEASUREMENTS: Pulmonary function data, radiographic studies including chest radiograph and high-resolution CT of the chest, and serologic analysis to rule out allergic bronchopulmonary aspergillosis and alpha1-antitrypsin deficiency had been performed as indicated, and these results were obtained through chart review. RESULTS: The age of the patients ranged from 41 to 58 years, with a mean duration of asthma of 39 years (SD = 12.4 years). No patient had evidence of any other pulmonary disease process. The mean duration of daily or alternate-day oral corticosteroid treatment was 15.8 years (SD=11.8 years). Despite intensive pharmacotherapy, all patients had an FEV1 57% (42+/-12%) with marked small airways disease as reflected in the forced expiratory flow between 25% and 75% of the FVC. Three of the eight patients demonstrated an accelerated decline in FEV1 despite continuous systemic corticosteroids. CONCLUSIONS: We have described a series of eight patients with long-standing asthma who demonstrate irreversible airways obstruction despite long-term systemic and inhaled corticosteroids. The term "end-stage asthma" or irreversible asthma might be applied to these patients in whom fixed obstruction has occurred in the absence of other pulmonary diseases.

Adult↗
PubMed1997

Speed discrimination of stereoscopic (cyclopean) motion.

This study investigated the degree to which speed of stereoscopic translational motion (i.e. moving binocular disparity information) can be discriminated in a display that minimizes position information. Observers viewed dynamic random-element stereograms depicting arrays of randomly positioned stereoscopic dots that moved bidirectionally. Two tasks were performed: a speed discrimination task and a displacement discrimination task. Across a range of conditions, speed could be discriminated under conditions in which displacement could not. Thus, speed of stereoscopic motion can be discriminated when position information is minimal. This result indicates that stereoscopic motion is sensed in a way that cannot be explained by feature tracking or by inferring the motion from memory of position and time.

Depth Perception↗
PubMed1997

Direction-selective coding of stereoscopic (cyclopean) motion.

This study employed a selective adaptation paradigm and investigated thresholds for direction discrimination of translational stereoscopic motion (moving binocular disparity information). The stimuli were moving arrays of randomly positioned stereoscopic discs created from disparity embedded in dynamic random-element stereograms. When discrimination thresholds were measured across a range of base directions following adaptation in a fixed direction, discrimination thresholds were maximally elevated 20-30 deg away from adaptation and reduced in the same direction as adaptation. These results are consistent with a distributed-channel model of direction coding and indicate that the direction of stereoscopic motion is encoded by adaptable direction-selective mechanisms similar to those proposed for luminance-defined motion.

Adaptation, Ocular↗
PubMed1997

Direction discrimination of cyclopean (stereoscopic) and luminance motion.

This study compared direction discrimination of cyclopean (stereoscopic) and luminance motion involving stimuli equated for effective strength. The stimuli were random-walk cinematogram (RWC) displays whose signal and noise discs were created from binocular disparity differences embedded in a dynamic random-dot stereogram or from luminance differences. Experiment 1 measured global motion detection thresholds for cyclopean and luminance stimuli by manipulating the proportion of signal to noise discs. Detection thresholds for cyclopean motion were about 25% whereas detection thresholds for luminance motion were 5%, thus five times more cyclopean motion events than luminance events were necessary to elicit threshold responding. Experiment 2 measured thresholds for discriminating the direction of cyclopean and luminance motion under conditions of equal stimulus strength by presenting the motion displays at equal multiples of detection threshold. Direction discrimination thresholds (ranging from about 5-30 deg, depending upon conditions) were similar for cyclopean and luminance motion, thus the precision with which the pooling of local motion events in one direction can be discriminated from the pooling of events in a slightly different direction is the same for cyclopean and luminance stimuli. The finding that cyclopean motion information is pooled is consistent with the idea that the direction of cyclopean motion is coded in the responses of a population of directionally selective mechanisms.

Depth Perception↗
PubMed1997

Pediatric idiopathic anaphylaxis: experience with 22 patients.

Idiopathic anaphylaxis in the pediatric population is being increasingly recognized, with symptoms (and therefore classifications) the same as those described in adults. We present a series of 22 patients with special attention to considerations relatively unique to the pediatric population. Prednisone, hydroxyzine, and albuterol were used to control symptoms and induce remission. No deaths occurred during treatment. One adolescent who presented with corticosteroid-dependent idiopathic anaphylaxis was diagnosed with undifferentiated somatoform-idiopathic anaphylaxis. Local physician reluctance to participate in management complicated care for some patients.

Adolescent↗
PubMed1997

A case of idiopathic anaphylaxis associated with respiratory infections.

BACKGROUND: Anaphylaxis is associated with IgE-mediated reactions to foods, drugs, and other allergens. Exercise-induced anaphylaxis and food plus exercise-induced anaphylaxis have been reported. Anaphylactoid reactions with no mechanisms determined have been described with radiographic contrast media. Idiopathic anaphylaxis by definition is anaphylaxis with no identifiable external allergen or stimulus. In our series of more than 350 patients with idiopathic anaphylaxis, extensive evaluation has failed to identify a cause for the anaphylaxis. OBJECTIVE: To report a first case of idiopathic anaphylaxis associated with coryzal symptoms. METHODS: A patient was evaluated for idiopathic anaphylaxis. Appropriate therapy was initiated. RESULTS: The patient's anaphylactic episodes are related to the occurrence of coryzal symptoms but no clear IgE-mediated mechanism was identified. CONCLUSION: This is the first reported association of anaphylaxis with an inciting factor of infection.

Anaphylaxis↗
PubMed1997

Malignant and corticosteroid-dependent idiopathic anaphylaxis: successful responses to ketotifen.

BACKGROUND: Malignant idiopathic anaphylaxis refers to the most severe form of idiopathic anaphylaxis where defined episodes of idiopathic anaphylaxis are not controlled when the prednisone is reduced below at least 60 mg every other day or 20 mg daily. Corticosteroid-dependent idiopathic anaphylaxis refers to patients with idiopathic anaphylaxis who require continuous daily or alternate day prednisone at threshold doses for control of idiopathic anaphylaxis. Ketotifen has been reported to help induce remission in some patients with idiopathic anaphylaxis and has steroid sparing effects in other patients with idiopathic anaphylaxis. METHODS: We present five patients, two with malignant idiopathic anaphylaxis and three with corticosteroid-dependent idiopathic anaphylaxis, who responded to the administration of ketotifen. RESULTS: All five patients, while receiving ketotifen, had a reduction or resolution of their episodes of idiopathic anaphylaxis and prednisone was tapered and discontinued. CONCLUSION: Ketotifen is shown to be successful in inducing remission in two patients with malignant idiopathic anaphylaxis and in three additional patients with corticosteroid-dependent idiopathic anaphylaxis. An additional patient with malignant idiopathic anaphylaxis had prednisone stopped after elective hip surgery.

Adrenal Cortex Hormones↗
PubMed1997

Heart rate change as a function of age, tidal volume and body position when breathing using voluntary cardiorespiratory synchronization.

Voluntary cardiorespiratory synchronization (VCRS), where inspiration and expiration follows a fixed number of heart beats, was used to investigate heart rate change (HRC) in 16 subjects (grouped as 20-30 and 46-57 years of age) as a function of age, body position, and respiratory tidal volumes of 500 and 1000 ml. In phase I, the subjects, following a tone, inspired for two heart beats and expired for three beats. In phase II, the older group's breathing pattern was 2/2, 2/3, 3/3, 4/4, 5/5, and 6/6 inspiratory and expiratory heart beats, respectively, per respiratory cycle. Comparing the younger and older groups, we found a statistically significant (p < 0.05) decrease in HRC for beat 1, 2, and 4 of the respiratory cycle in the supine position, and also for beat 2 in the sitting position, but no significant change with tidal volume. The ratio of the younger to older group's beat 2 HRC was 2.54 sitting and 3.54 supine. Increasing the number of beats per respiratory cycle from four to 12 resulted in the HRC growing from 1.8 to 7.5 beats over the respiratory cycle, showing the importance of respiratory rate in measuring HRC. VCRS can easily observe the influence of each phase of the respiratory cycle on the HRC and show the unique phase dependent changes that occur.

Adult↗