Search PubMed⌕ Search

Biomedical subjects

R Patterson

Publications and source records attributed to R Patterson.

At least 19 recordsLinked to original sources
PubMed2004

Interaction between the neuromagnetic responses to sound energy onset and pitch onset suggests common generators.

The pitch-onset response (POR) is a negative component of the auditory evoked field which is elicited when the temporal fine structure of a continuous noise is regularized to produce a pitch perception without altering the gross spectral characteristics of the sound. Previously, we showed that the latency of the POR is inversely related to the pitch value and its amplitude is correlated with the salience of the pitch, suggesting that the underlying generators are part of a pitch-processing network [Krumbholz, K., Patterson, R.D., Seither-Preisler, A., Lammertmann, C. & Lütkenhöner, B. (2003) Cereb. Cortex,13, 765-772]. The source of the POR was located near the medial part of Heschl's gyrus. The present study was designed to determine whether the POR originates from the same generators as the energy-onset response (EOR) represented by the N100m/P200m complex. The EOR to the onset of a noise, and the POR to a subsequent transition from noise to pitch, were recorded as the time interval between the noise onset and the transition varied from 500 to 4000 ms. The mean amplitude of the POR increased by approximately 5.9 nA.m with each doubling of the time between noise onset and transition. This suggests an interaction between the POR and the EOR, which may be based on common neural generators.

Acoustic Stimulation↗
PubMed2001

Differential effects of trivalent and pentavalent arsenicals on cell proliferation and cytokine secretion in normal human epidermal keratinocytes.

There is strong evidence from epidemiologic studies of an association between chronic exposure to inorganic arsenic (iAs) and hyperpigmentation, hyperkeratosis, and neoplasia in the skin. Although it is generally accepted that methylation is a mechanism of arsenic detoxification, recent studies have suggested that methylated arsenicals also have deleterious biological effects. In these studies we compare the effects of inorganic arsenicals (arsenite (iAs(III)) and arsenate (iAs(V))) and trivalent and pentavalent methylated arsenicals (methylarsine oxide (MAs(III)O), complex of dimethylarsinous acid with glutathione (DMAs(III)GS), methylarsonic acid (MAs(V)), and dimethylarsinic acid (DMAs(V))) in human keratinocyte cultures. Viability testing showed that the relative toxicities of the arsenicals were as follows: iAs(III) > MAs(III)O > DMAs(III)GS > DMAs(V) > MAs(V) > iAs(V). Trivalent arsenicals induced an increase in cell proliferation at concentrations in the 0.001 to 0.01 microM range, while at high concentrations (>0.5 microM) cell proliferation was inhibited. Pentavalent arsenicals did not stimulate cell proliferation. As seen in the viability studies, the methylated forms of As(V) were more cytotoxic than iAs(V). Exposure to low doses of trivalent arsenicals stimulated secretion of the growth-promoting cytokines, granulocyte macrophage colony stimulating factor and tumor necrosis factor-alpha. DMAs(V) reduced cytokine secretion at concentrations at which proliferation and viability were not affected. These data suggest that methylated arsenicals, products of the metabolic conversion of inorganic arsenic, can significantly affect viability and proliferation of human keratinocytes and modify their secretion of inflammatory and growth-promoting cytokines.

Adult↗
PubMed2001

The stereoscopic (cyclopean) motion aftereffect is dependent upon the temporal frequency of adapting motion.

This study investigated whether the stereoscopic (cyclopean) motion aftereffect (induced by adaptation to moving binocular disparity information) is dependent upon the temporal frequency or speed of adapting motion. The stereoscopic stimuli were gratings created from disparity embedded in a dynamic random-dot stereogram. Across different combinations of stereoscopic spatial frequency, temporal frequency and speed of adapting motion, the duration of the aftereffect was dependent upon temporal frequency (maximal aftereffect=1-2 cyc s(-1)). These results support the idea that stereoscopic motion is processed by a cortical mechanism that computes cyclopean motion energy.

Adaptation, Physiological↗
PubMed2001

Severe serum sickness-like reaction to oral penicillin drugs: three case reports.

BACKGROUND: Because the use of heterologous sera has diminished, the incidence of serum sickness has declined. However, serum sickness-like reactions to nonprotein drugs continue to occur. METHODS: We report three cases of severe serum sickness-like reactions in adults to oral penicillin drugs. RESULTS: In each patient, significant symptom resolution occurred within 24 hours of starting therapy with oral corticosteroids. CONCLUSIONS: Serum sickness-like reactions to oral penicillin drugs may be more common than reported in the literature and can be very severe. No specific laboratory finding is universally present or definitively diagnostic. As with classic serum sickness, the diagnosis of serum sickness-like reaction is made clinically. In severe cases such as those presented here with debilitating joint symptoms or life-threatening angioedema, a diagnostic-therapeutic trial of prednisone, 40 to 60 mg at least once daily, is warranted.

Administration, Oral↗
PubMed2001

Impact of allergic rhinitis treatment on quality of life.

Allergic rhinitis is a chronic inflammatory disorder of the nasal passages. It affects approximately 20% of the population, is a significant health and economic burden, and severely impairs quality of life. Two main instruments, Medical Outcomes Study 36-Item Short Form health survey (SF-36) and Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ) have been used to assess quality of life in patients with allergic rhinitis. Antihistamines, corticosteroids, anticholinergic agents, decongestants, cromoglycates, and immunotherapy are used to treat patients with allergic rhinitis. Of these, antihistamines and intranasal corticosteroids are the most efficacious and frequently utilised medications. Studies have demonstrated improvements in quality of life with both of these medications in patients with allergic rhinitis.

Adrenal Cortex Hormones↗
PubMed2001

Listening to deaf speech: does experience count?

Listening for intelligibility in disordered speech involves a complex interaction of factors, including listener experience. This study examines intelligibility as perceived by two groups (experienced and inexperienced listeners) in interpreting deaf speech. Speech samples were gathered from a hearing-impaired child over thirteen months, immediately post cochlear implantation. Results indicate that experienced listeners interpret more of disordered speech than inexperienced, but while experience appears to be a factor in intelligibility judgements, it does not alone guarantee higher intelligibility rating.

Deafness↗
PubMed2001

The promised land.

Explore the source record for details and available documents.

Attitude of Health Personnel↗
PubMed2000

Exposure duration affects the perceived direction of cyclopean type II plaids.

This study investigated the effect of exposure duration on the perceived direction of cyclopean Type I and Type II plaids moving in the X/Y plane. The cyclopean plaids were created from grating components defined by binocular disparity embedded in a dynamic random-dot stereogram. The results showed that the cyclopean Type I plaid appeared to move in the intersection-of-constraints (IOC) direction across the range of exposures tested. However, the cyclopean Type II plaids appeared to move in a direction different from the IOC with short exposures but near the IOC with long exposures. This perceived directional shift was also obtained with luminance-defined Type II plaids. A common pattern-motion mechanism that processes cyclopean and luminance motion signals appears responsible for the perceived directional shift of the Type II plaids.

Depth Perception↗
PubMed2000

Cross-domain adaptation reveals that a common mechanism computes stereoscopic (cyclopean) and luminance plaid motion.

Across three experiments, this study investigated the visual processing of moving stereoscopic plaid patterns (plaids created with cyclopean components defined by moving binocular disparity embedded in a dynamic random-dot stereogram). Results showed that adaptation to a moving stereoscopic plaid or its components affected the perceived coherence of a luminance test plaid, and vice versa. Cross-domain adaptation suggests that stereoscopic and luminance motion signals feed into a common pattern-motion mechanism, consistent with the idea that stereoscopic motion signals are computed early in the motion processing stream.

Adaptation, Ocular↗
PubMed2000

Hypersensitivity pneumonitis resulting from community exposure to Canada goose droppings: when an external environmental antigen becomes an indoor environmental antigen.

BACKGROUND: In the past, hypersensitivity pneumonitis has been attributed to occupational, agricultural, or home environmental exposure. OBJECTIVE: This report describes the first case of hypersensitivity pneumonitis due to community exposure to droppings from Canada geese migrating through a suburban environment. METHOD: Clinical and serologic information was used in making the diagnosis of hypersensitivity pneumonitis. RESULTS: Serologic analysis demonstrated precipitating antibodies against goose droppings and against an extract made from washings from a filter taken from the patient's office. These studies also showed that the antigens in the office filter were goose dropping antigens. CONCLUSION: Hypersensitivity pneumonitis can result from exposure to goose dropping antigens in the community that enter buildings through ventilation systems. This represents a new form of an old disease.

Air Pollution, Indoor↗
PubMed2000

Endotoxin (lipopolysaccharide)-induced nitric oxide production in 2,3,7,8-tetrachlorodibenzo-p-dioxin-treated Fischer rats: detection of nitrosyl hemoproteins by EPR spectroscopy.

Electron paramagnetic resonance (EPR) spectroscopy was used to study the effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on endotoxin (lipopolysaccharide)-induced nitric oxide (NO) production in Fischer rats. We found that rats treated with 50 microg/kg TCDD had increased sensitivity to endotoxin, resulting in an approximately 2-fold increase in the level of NO production detected as nitrosylhemoglobin (HbNO) in venous blood. At lower concentrations (< or = 5 microg/kg), TCDD did not affect the endotoxin-induced NO production. The TNF-alpha serum concentration was found to parallel that of NO. TCDD alone did not induce the production of detectable HbNO or TNF-alpha. We found that TCDD induced a dose-dependent increase in the EPR signal intensity of (Fe(3+)) low-spin methemoprotein complexes found in the liver and kidney. These species with EPR resonance at g = 2.43, 2.26, and 1.92 are attributed to low-spin Fe(3+) in cytochromes P450 and P420. Our data confirm previous studies that have shown that TCDD induces a dose-dependent increase in the production of some cytochrome P450 enzymes. However, in rats that were subsequently challenged with endotoxin, a smaller increase in the EPR intensity of these species was observed. The decrease in the low-spin Fe(3+) cytochrome P450 EPR signal in endotoxin-challenged rats could be due to one or more of the following occurring: (1) cytochrome destruction, (2) reduction of the ferric to the ESR-silent ferrous oxidation state of cytochromes by nitric oxide, and/or (3) formation of ferrous nitrosyl cytochrome complexes that contribute, in part, to the characteristic five-coordinate nitrosyl hemoprotein triplet also observed in these tissues. Since low concentrations of endotoxin can leak from the gut lumen into the systemic circulation, this investigation explores the possibility that endotoxin interaction with TCDD may be, in part, responsible for the effects of TCDD observed in these tissues.

Animals↗
PubMed2000

Multicenter, double-blind, placebo-controlled, multiple-challenge evaluation of reported reactions to monosodium glutamate.

BACKGROUND: The frequency of reactions reported to occur after the consumption of monosodium glutamate (MSG) is the subject of controversy. OBJECTIVE: We conducted a multicenter, multiphase, double-blind, placebo-controlled study with a crossover design to evaluate reactions reportedly caused by MSG. METHODS: In 3 of 4 protocols (A, B, and C), MSG was administered without food. A positive response was scored if the subject reported 2 or more symptoms from a list of 10 symptoms reported to occur after ingestion of MSG-containing foods within 2 hours. In protocol A 130 self-selected reportedly MSG-reactive volunteers were challenged with 5 g of MSG and with placebo on separate days (days 1 and 2). Of the 86 subjects who reacted to MSG, placebo, or both in protocol A, 69 completed protocol B to determine whether the response was consistent and dose dependent. To further examine the consistency and reproducibility of reactions to MSG, 12 of the 19 subjects who responded to 5 g of MSG but not to placebo in both protocols A and B were given, in protocol C, 2 challenges, each consisting of 5 g of MSG versus placebo. RESULTS: Of 130 subjects in protocol A, 50 (38. 5%) responded to MSG only, 17 (13.1%) responded to placebo only (P <. 05), and 19 (14.6%) responded to both. Challenge with increasing doses of MSG in protocol B was associated with increased response rates. Only half (n = 19) of 37 subjects who reacted to 5 g of MSG but not placebo in protocol A reacted similarly in protocol B, suggesting inconsistency in the response. Two of the 19 subjects responded in both challenges to MSG but not placebo in protocol C; however, their symptoms were not reproducible in protocols A through C. These 2 subjects were challenged in protocol D 3 times with placebo and 3 times with 5 g of MSG in the presence of food. Both responded to only one of the MSG challenges in protocol D. CONCLUSION: The results suggest that large doses of MSG given without food may elicit more symptoms than a placebo in individuals who believe that they react adversely to MSG. However, neither persistent nor serious effects from MSG ingestion are observed, and the responses were not consistent on retesting.

Adult↗