Biomedical subjects

C C Wood

Publications and source records attributed to C C Wood.

At least 19 recordsLinked to original sources

PubMed1999

Bayesian inference applied to the electromagnetic inverse problem.

We present a new approach to the electromagnetic inverse problem that explicitly addresses the ambiguity associated with its ill-posed character. Rather than calculating a single "best" solution according to some criterion, our approach produces a large number of likely solutions that both fit the data and any prior information that is used. Whereas the range of the different likely results is representative of the ambiguity in the inverse problem even with prior information present, features that are common across a large number of the different solutions can be identified and are associated with a high degree of probability. This approach is implemented and quantified within the formalism of Bayesian inference, which combines prior information with that of measurement in a common framework using a single measure. To demonstrate this approach, a general neural activation model is constructed that includes a variable number of extended regions of activation and can incorporate a great deal of prior information on neural current such as information on location, orientation, strength, and spatial smoothness. Taken together, this activation model and the Bayesian inferential approach yield estimates of the probability distributions for the number, location, and extent of active regions. Both simulated MEG data and data from a visual evoked response experiment are used to demonstrate the capabilities of this approach.

Bayes Theorem↗

PubMed1997

Ipratropium nasal spray in children with perennial rhinitis.

OBJECTIVE: To compare the efficacy and safety of ipratropium nasal spray and placebo administered twice each day for 4 weeks in pediatric patients with perennial rhinitis who had rhinorrhea as a major complaint. METHODS: This was a multicenter, double-blind, parallel group study. Patients aged 6 to 18 years with symptoms of perennial nonallergic (PNAR) or perennial allergic rhinitis (PAR) were randomized to receive ipratropium (42 micrograms per nostril) or placebo nasal spray, double-blind, twice each day for 4 weeks. Efficacy was evaluated by nasal symptoms, especially anterior rhinorrhea, and quality of life. Previous caregivers for rhinitis and medications used in the past were also evaluated. RESULTS: A total of 202 patients were empanelled, 162 with PAR, 40 with PNAR; of these 151 with mild-severe rhinorrhea were evaluated for efficacy. Treatment with ipratropium reduced symptoms of rhinorrhea primarily in patients with PNAR. In patients with PAR this response was less pronounced, and was seen as a modest decrease in the severity of rhinorrhea noted in the first 2 weeks of treatment. Quality of life assessments confirmed that rhinorrhea was bothersome to these pediatric patients, and suggested that treatment with ipratropium nasal spray was associated with an improvement, especially in the patients with PNAR. There were few adverse events; these were similar in the two treatment groups. CONCLUSIONS: Ipratropium nasal spray 0.03% administered at a dose of 42 micrograms/nostril bid is a safe and effective new therapy for control of anterior rhinorrhea in pediatric patients with PNAR. Twice daily administration is adequate for patients with PNAR, but patients with PAR might benefit from more frequent administration (e.g., tid).

Administration, Inhalation↗

PubMed1995

Product characteristics and pharmacokinetics of intranasal ipratropium bromide.

The in vivo absorption potential of ipratropium bromide nasal spray was evaluated in studies involving healthy volunteers (0.03%, 0.06%, and 0.12% dosage strengths) and patients with perennial rhinitis (0.03% and 0.06%) and the common cold (0.06%). The dose used was two sprays per nostril, corresponding to a total dose of 84 micrograms, 168 micrograms, and 336 micrograms for the three dosage strengths. These studies indicate that 10% or less of active drug is absorbed systemically after nasal administration based on the amount of unchanged drug excreted in urine in a 24-hour interval. In most instances, the plasma drug concentrations were undetectable. In none of these studies did plasma ipratropium concentrations reach a level where systemic anticholinergic effects are known to occur.

Absorption↗

PubMed1995

A clinical trial of ipratropium bromide nasal spray in patients with perennial nonallergic rhinitis.

Intranasal ipratropium bromide has been shown to significantly reduce rhinorrhea. Use of a freon-propelled intranasal preparation has resulted in side effects associated with the drying properties of the propellant. The purpose of the present trial was to study the safety and efficacy of a new isotonic aqueous ipratropium bromide nasal spray pump, specifically in patients with perennial nonallergic rhinitis. Two hundred thirty-three patients participated in an 8-week double-blind parallel comparison of ipratropium bromide nasal spray with its vehicle, a saline solution. Treatment with the ipratropium spray resulted in a 30% reduction in rhinorrhea; this reduction was significantly greater than that seen with the saline vehicle. There was a modest reduction in postnasal drip, sneezing, and congestion with both treatments, which may be attributable to the salutary effects of the saline solution. Patients also perceived a significant reduction in the degree to which rhinorrhea interfered with their daily activities and moods. Treatment was well tolerated, with no drug-related systemic adverse events and no evidence of nasal rebound on discontinuation of treatment. Minor, infrequent episodes of nasal dryness and epistaxis were the only significant adverse events reported; these did not limit treatment.

Adult↗

PubMed1995

Long-term treatment of perennial allergic rhinitis with ipratropium bromide nasal spray 0.06%.

The purpose of this study was to assess the safety and efficacy of ipratropium bromide nasal spray 0.06% (aqueous solution), 84 micrograms per nostril three times a day, in reducing nasal hypersecretion in the long-term treatment of patients with perennial allergic rhinitis (PAR). This was an open-label 1-year trial. In the first 6 months all patients were treated with two puffs ipratropium bromide nasal spray 0.06%, 84 micrograms per nostril three times per day, unless they were unable to tolerate the dose. In the last 6 months the dose could be reduced to the lowest amount required to control rhinorrhea. Ninety-six patients entered the trial, and 47 completed it. Sixty-three patients completed more than 6 months of treatment. Patient and physician global evaluation suggested that ipratropium bromide nasal spray 0.06% is effective in controlling rhinorrhea associated with PAR and can contribute to control of congestion, postnasal drip, and sneezing. There was also a trend toward reduction of mucosal edema and improvement in quality of life. The most common drug-related adverse events were nasal dryness, epistaxis/nose bleed, and increased rhinitis. Most adverse events were mild and resulted in drug discontinuation in less than 10% of patients. Ipratropium bromide nasal spray was well tolerated and not associated with serious drug-related adverse events or clinically significant anticholinergic side effects. Use of ipratropium bromide nasal spray alone or with other standard medications should be considered in treating patients with PAR.

Adolescent↗

PubMed1995

A pharmacologic continuum in the treatment of rhinorrhea: the clinician as economist.

The economics of medications are now of great concern to health-care providers. Pharmacoeconomic issues are by no means simple, and yet, ironically, they assume greater importance in prescribing for modest disorders like rhinorrhea than for life-threatening conditions. The therapeutic continuum of quality and cost becomes foreshortened, and safety is an additional concern. Choosing the appropriate medication for rhinorrhea, then, can pose a challenge to the clinician, just as choosing a vital medication. This paper reviews the usage, quality, and cost of major therapies for the rhinorrhea that occurs secondary to various conditions, including nasal steroids, antihistamines and anticholinergics, and discusses the role of the clinician in factoring costs into therapy.

Cholinergic Antagonists↗

PubMed1995

Mapping function in the human brain with magnetoencephalography, anatomical magnetic resonance imaging, and functional magnetic resonance imaging.

Integrated analyses of human anatomical and functional measurements offer a powerful paradigm for human brain mapping. Magnetoencephalography (MEG) and EEG provide excellent temporal resolution of neural population dynamics as well as capabilities for source localization. Anatomical magnetic resonance imaging (MRI) provides excellent spatial resolution of head and brain anatomy, whereas functional MRI (fMRI) techniques provide an alternative measure of neural activation based on associated hemodynamic changes. These methodologies constrain and complement each other and can thereby improve our interpretation of functional neural organization. We have developed a number of computational tools and techniques for the visualization, comparison, and integrated analysis of multiple neuroimaging techniques. Construction of geometric anatomical models from volumetric MRI data allows improved models of the head volume conductor and can provide powerful constraints for neural electromagnetic source modeling. These approaches, coupled to enhanced algorithmic strategies for the inverse problem, can significantly enhance the accuracy of source-localization procedures. We have begun to apply these techniques for studies of the functional organization of the human visual system. Such studies have demonstrated multiple, functionally distinct visual areas that can be resolved on the basis of their locations, temporal dynamics, and differential sensitivity to stimulus parameters. Our studies have also produced evidence of internal retinotopic organization in both striate and extrastriate visual areas but have disclosed organizational departures from classical models. Comparative studies of MEG and fMRI suggest a reasonable but imperfect correlation between electrophysiological and hemodynamic responses. We have demonstrated a method for the integrated analysis of fMRI and MEG, and we outline strategies for improvement of these methods. By combining multiple measurement techniques, we can exploit the complementary strengths and transcend the limitations of the individual neuro-imaging methods.

Brain↗

PubMed1994

Onset and duration of inhibition of ipratropium bromide nasal spray on methacholine-induced nasal secretions.

We performed a randomized, double-blind, placebo-controlled cross-over study with two different concentrations of ipratropium bromide (Atrovent) nasal spray to evaluate its onset and duration of inhibition. Twenty-four subjects with perennial rhinitis participated in the trial. Fifteen minutes to 12 hours after administration of ipratropium bromide (42 or 168 micrograms/nostril) or placebo nasal spray, methacholine challenges were performed and nasal secretion weights measured. After placebo administration the effect of methacholine remained unchanged over the 12-h-period. Both the 42 and 168 micrograms/nostril doses significantly inhibited the nasal hypersecretions induced by methacholine challenge within 15 min of treatment (P < 0.05). The 168 micrograms dose of ipratropium bromide continued to significantly reduce secretion weights through 6 hours, but the effectiveness of the 42 micrograms dose disappeared within 3 h. In addition to having a longer duration, the 168 micrograms/nostril dose produced approximately twice the inhibitory effect of the 42 micrograms dose.

Adult↗

PubMed1992

Tactile interference differentiates sub-components of N20, P20 and P29 in the human cortical surface somatosensory evoked potential.

Somatosensory evoked potentials (SEPs) to median nerve stimulation were recorded from up to 64 locations on the exposed cortical surface in 19 patients undergoing intracranial surgery for epilepsy and/or tumour removal. In view of previously described 'interference' effects on scalp SEPs, a continuous light tactile stimulus was applied to the palm and the first 3 digits of the stimulated hand in order to try to differentiate components due to input from cutaneous and other sensory receptors. The first cortically generated potentials, N20 at postcentral locations and P20 precentrally, could each be resolved into 2 subcomponents separated by about 2.5 msec. The later subcomponent was consistently the more attenuated by the interfering stimulus and is postulated to be due to input from rapidly adapting cutaneous mechanoreceptors. The earlier subcomponent could be due to input from muscle afferents or from slowly adapting cutaneous receptors which the interfering stimulus would have activated to a lesser degree. In 2 cases the P29 potentials recorded from regions of the postcentral gyrus were dissociated. In one case the potentials recorded at adjacent electrodes were attenuated to differing degrees, and in the other the effect was maximal at different locations when the thumb, index and middle fingers were stimulated separately. The method therefore appears capable of distinguishing regions of the postcentral gyrus concerned with cutaneous input from different parts of the hand.

Adolescent↗

PubMed1992

Ipratropium bromide aqueous nasal spray for patients with perennial allergic rhinitis: a study of its effect on their symptoms, quality of life, and nasal cytology.

Ipratropium bromide is an anticholinergic agent with topical activity that has been studied as a freon-propelled aerosol spray for therapy of nonallergic rhinitis. This is the first report of its use both as an aqueous nasal spray and in perennial allergic rhinitis. In this study 123 patients who had symptoms of perennial allergic rhinitis were randomized to receive ipratropium bromide 21 micrograms or 42 micrograms or placebo, one spray per nostril three times a day for 4 weeks. Patients maintained daily diaries of duration and severity of nasal symptoms and were evaluated weekly. Mean duration and severity of rhinorrhea was decreased in both ipratropium bromide treatment groups by comparison with placebo, with consistently greatest improvement in the group treated with ipratropium bromide 42 micrograms per nostril three times a day. No statistically significant differences occurred among treatment groups in duration or severity of postnasal drip, congestion, or sneezing. Seventy percent of patients treated with 42 micrograms of ipratropium bromide thought it had good or excellent effect on rhinorrhea (p less than 0.05 vs placebo); significantly more patients thought that it had improved the quality of life (p = 0.02). No changes occurred in nasal cytology, and no significant local or systemic adverse events occurred. These data indicate that ipratropium bromide significantly decreases the rhinorrhea of perennial allergic rhinitis.

Administration, Intranasal↗

PubMed1992

Ipratropium bromide (Atrovent nasal spray) reduces the nasal response to methacholine.

We investigated the efficacy of local ipratropium bromide on methacholine-induced nasal secretions in a double-blind, placebo-controlled experiment. Twenty subjects with perennial rhinitis received a total intranasal dose of 21, 42, 84, and 168 micrograms of ipratropium bromide or placebo in each nostril. One hour later, filter paper disks were used to deliver increasing doses of methacholine and to collect secretions from the left septum. Concomitantly, symptoms of rhinorrhea and nasal congestion were scored. Compared with doses of placebo, all doses of ipratropium bromide significantly reduced the methacholine-induced increase in nasal secretion weights and symptoms of rhinorrhea (p less than 0.01). The highest dose was significantly more effective than the lower doses in reducing secretion weights (p = 0.01). We speculate that ipratropium bromide may prove beneficial for the treatment of rhinorrhea in perennial rhinitis. Furthermore, increasing the delivered dose to 168 micrograms may increase efficacy without augmenting side effects.

Adult↗

PubMed1992

Event-related potentials elicited by deviant endings to melodies.

Event-related potentials were recorded from scalp electrodes while subjects listened to well-known melodies. The melodies ended either with the expected note or with a different note. This design was a nonlinguistic analogue of the design used by Kutas and Hillyard (1980b), who first reported that anomalous terminal words in sentences elicited N400 potentials. However, Besson and Macar (1987) reported that deviant terminal notes in melodies did not elicit N400 potentials. In the present study, additional time was allowed for expectations to develop for the terminal note. Deviant terminal notes did not elicit N400s. In both studies, however, the deviant notes elicited P300-like waves. This outcome raised the possibility that N400 might have been masked by the positive potential. In a second condition in which P300 amplitude was minimized, N400s were again not evident. These results thus illustrate two additional situations in which nonlinguistic stimuli that deviated from a sequential pattern failed to elicit N400 potentials.

Adult↗

PubMed1992

Double-blind study of intranasal ipratropium bromide in nonallergic perennial rhinitis.

We undertook this trial to determine whether ipratropium bromide nasal spray 0.03% (IB) reduced the nasal hypersecretion associated with nonallergic perennial rhinitis (NAPR) without causing excessive dryness or irritation of the nasal mucosa. We compared two drug doses of IB (21 micrograms and 42 micrograms per nostril) to a placebo, administered as two sprays to each nostril twice daily. The study design consisted of a 1-week screening period without treatment, a 1-week single-blind placebo period, a 4-week double-blind treatment comparison period, and a 1-week follow-up period without medication to evaluate nasal rebound. One hundred fifty-two patients were entered and 140 completed the trial. Both doses of IB reduced the severity and duration of rhinorrhea compared with placebo (P = .05 and .03, respectively). Treatment differences were noticeable during the first week of therapy, continued to widen during the second week, and then remained stable throughout the next 2 weeks. There was no evidence of nasal rebound observed during the week after treatment. The drug was well tolerated with side effects limited to infrequent nasal adverse events of nasal dryness, blood-tinged mucus, and epistaxis occurring in 2% to 6% of patients. We conclude that IB is a safe and effective therapy for control of rhinorrhea associated with NAPR.

Administration, Intranasal↗

PubMed1991

Potentials evoked in human and monkey cerebral cortex by stimulation of the median nerve. A review of scalp and intracranial recordings.

Somatosensory evoked potentials (SEPs) are generated in afferent pathways, subcortical structures and various regions of cerebellar and cerebral cortex by stimulation of somatic receptors or electrical stimulation of peripheral nerves. This review summarizes current knowledge of SEPs generated in cerebral cortex by stimulation of the median nerve, the most common form of stimulation for human research and clinical investigations. Major sources of data for the review are intracranial recordings obtained from patients during diagnostic or neurosurgical procedures, and similar recordings in monkeys. Short-latency cortical SEPs in the 20-40 ms latency range consist of P20 and N30, recorded from motor cortex and frontal scalp; P25 and N35, recorded from cortex near the central sulcus and central scalp; and N20 and P30, recorded from somatosensory cortex and parietal scalp. Several lines of evidence including cortical surface and intracerebral recordings, neuromagnetic recordings and lesion studies in humans and monkeys, strongly support the conclusion that these potentials are generated in contralateral somatosensory cortex in areas 3b and 1, in contrast to the conclusion of many previous studies that SEPs recorded from the frontal scalp are generated in motor cortex and other frontal lobe areas. These potentials are primarily mediated by cutaneous afferents of the dorsal column-medial lemniscal system; the contribution of muscle afferents has not been completely resolved but appears to be small. There is currently no evidence that short-latency SEPs are generated in cortex other than primary somatosensory cortex. Recordings from the vicinity of the second somatosensory area, from the supplementary motor and sensory areas and from surface cortex other than sensorimotor cortex have not detected reliable short-latency activity, although some of these regions generate long-latency potentials. Consequently, short-latency SEPs recorded from the scalp are similar to those recorded from the surface of sensorimotor cortex. Old World monkeys such as Macaca mulatta and M. fascicularis provide an excellent model for human short-latency SEPs. All the potentials described above in humans have corresponding monkey analogues, with similar distributions over the cortical surface. The squirrel monkey, a New World species, exhibits the same potentials, but due to the different morphology of sensorimotor cortex, the surface distribution of SEPs is quite different.

Afferent Pathways↗

PubMed1991

Cortical somatosensory evoked potentials. I. Recordings in the monkey Macaca fascicularis.

1. The anatomic generators of somatosensory evoked potentials (SEPs) to median nerve stimulation in the 10- to 30-ms latency range were investigated in monkeys (Macaca fascicularis) by means of cortical-surface and laminar recordings. 2. Three groups of SEPs evoked by stimulation of the contralateral median nerve were recorded from the hand representation area of sensorimotor cortex: P10-N20, recorded anterior to the central sulcus (CS); N10-P20, recorded posterior to the CS; and P12-N25, recorded near the CS. These potentials were similar in morphology and surface distribution whether the animal was awake or anesthetized. 3. P10-N20 exhibited a polarity inversion to N10-P20 across the CS, both in cortical-surface recordings and in laminar recordings within cortex and white matter of motor and somatosensory cortex. In contrast, P10-N20 and N10-P20 did not exhibit polarity inversion in recordings from the surface and white matter of the crowns of motor and somatosensory cortex, respectively. These results strongly suggest that these potentials are produced by a tangential generator located in the posterior wall of the CS, primarily in area 3b of somatosensory cortex. 4. P12-N25 was largest over the hand area of somatosensory cortex and showed polarity inversion across the crown of somatosensory cortex but not across the crown of motor cortex or across the walls of the CS, suggesting that P12-N25 is due to a radially oriented generator located in areas 1 and 2 of somatosensory cortex. 5. P10-N20 and P12-N25 are thought to be equivalent to the "primary evoked response" recorded from somatosensory cortex of other mammals. 6. These results are very similar to those obtained in human cortical-surface recordings and demonstrate that the monkey P10-N20, N10-P20, and P12-N25 potentials correspond to the human P20-N30, N20-P30, and P25-N35 potentials, respectively. The only appreciable difference in human and monkey SEPs is that the monkey P12-N25 appears to be generated in areas 1 and 2, whereas the human P25-N35 appears to be generated only in area 1. 7. There was no evidence of locally generated activity in areas 3a and 4.

Animals↗

PubMed1991

Cortical somatosensory evoked potentials. II. Effects of excision of somatosensory or motor cortex in humans and monkeys.

1. To clarify the generators of human short-latency somatosensory evoked potentials (SEPs) thought to arise in sensorimotor cortex, we studied the effects on SEPs of surgical excision of somatosensory or motor cortex in humans and monkeys. 2. Normal median nerve SEPs (P20-N30, N20-P30, and P25-N35) were recorded from the cortical surface of a patient (G13) undergoing a cortical excision for relief of focal seizures. All SEPs were abolished both acutely and chronically after excision of the hand area of somatosensory cortex. Similarly, excision of the hand area of somatosensory cortex abolished corresponding SEPs (P10-N20, N10-P20, and P12-N25) in monkeys. Excision of the crown of monkey somatosensory cortex abolished P12-N25 while leaving P10-N20 and N10-P20 relatively unaffected. 3. After excision of the hand area of motor cortex, all SEPs were present when recorded from the cortical surface of a patient (W1) undergoing a cortical excision for relief of focal seizures. Similarly, all SEPs were present in monkeys after excision of the hand area of motor cortex. 4. Although all SEPs were present after excision of motor cortex in monkeys, variable changes were observed in SEPs after the excisions. However, these changes were not larger than the changes observed after excision of parietal cortex posterior to somatosensory cortex. We concluded that the changes were not specific to motor cortex excision. 5. These results support two major conclusions. 1) Median nerve SEPs recorded from sensorimotor cortex are produced by generators in two adjacent regions of somatosensory cortex: a tangentially oriented generator in area 3b, which produces P20-N30 (human) and P10-N20 (monkey) [recorded anterior to the central sulcus (CS)] and N20-P30 (human) and N10-P20 (monkey) posterior to the CS; and a radially oriented generator in area 1, which produces P25-N35 (human) and P12-N25 (monkey) recorded from the postcentral gyrus near the CS. 2) Motor cortex makes little or no contribution to these potentials.

Adolescent↗

PubMed1989

Human cortical potentials evoked by stimulation of the median nerve. I. Cytoarchitectonic areas generating short-latency activity.

1. The anatomic generators of human median nerve somatosensory evoked potentials (SEPs) in the 40 to 250-ms latency range were investigated in 54 patients by means of cortical-surface and transcortical recordings obtained during neurosurgery. 2. Contralateral stimulation evoked three groups of SEPs recorded from the hand representation area of sensorimotor cortex: P45-N80-P180, recorded anterior to the central sulcus (CS) and maximal on the precentral gyrus; N45-P80-N180, recorded posterior to the CS and maximal on the postcentral gyrus; and P50-N90-P190, recorded near and on either side of the CS. 3. P45-N80-P180 inverted in polarity to N45-P80-N180 across the CS but was similar in polarity from the cortical surface and white matter in transcortical recordings. These spatial distributions were similar to those of the short-latency P20-N30 and N20-P30 potentials described in the preceding paper, suggesting that these long-latency potentials are generated in area 3b of somatosensory cortex. 4. P50-N90-P190 was largest over the anterior one-half of somatosensory cortex and did not show polarity inversion across the CS. This spatial distribution was similar to that of the short-latency P25-N35 potentials described in the preceding paper and, together with our and Goldring et al. 1970; Stohr and Goldring 1969 transcortical recordings, suggest that these long-latency potentials are generated in area 1 of somatosensory cortex. 5. SEPs of apparently local origin were recorded from several regions of sensorimotor cortex to stimulation of the ipsilateral median nerve. Surface and transcortical recordings suggest that the ipsilateral potentials are generated not in area 3b, but rather in other regions of sensorimotor cortex perhaps including areas 4, 1, 2, and 7. This spatial distribution suggests that the ipsilateral potentials are generated by transcallosal input from the contralateral hemisphere. 6. Recordings from the periSylvian region were characterized by P100 and N100, recorded above and below the Sylvian sulcus (SS) respectively. This distribution suggests a tangential generator located in the upper wall of the SS in the second somatosensory area (SII). In addition, N125 and P200, recorded near and on either side of the SS, suggest a radial generator in a portion of SII located in surface cortex above the SS. 7. In comparison with the short-latency SEPs described in the preceding paper, the long-latency potentials were more variable and were more affected by intraoperative conditions.(ABSTRACT TRUNCATED AT 400 WORDS)

Brain↗

PubMed1989

Human cortical potentials evoked by stimulation of the median nerve. II. Cytoarchitectonic areas generating long-latency activity.

Cerebral Cortex↗