Biomedical subjects

C C Wood

Publications and source records attributed to C C Wood.

At least 19 recordsLinked to original sources

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↗

PubMed1989

Task-dependent field potentials in human hippocampal formation.

Task-dependent field potentials were recorded from implanted electrodes located in the hippocampus and other medial temporal lobe (MTL) structures of epileptic patients undergoing evaluation for possible surgery. In 2-alternative categorization tasks, low-probability auditory, somatic, and visual stimuli elicited potentials with large amplitudes and sharp spatial gradients having the following characteristic spatial distribution: positive posterior to the hippocampus, negative within the hippocampus, and positive anterior to the hippocampus. The sharp spatial gradients within the MTL suggest that these potentials were locally generated, probably by hippocampal pyramidal cells. The MTL potentials were also reliably elicited by exemplars of semantic categories and by stimulus omissions and were sensitive to the sequence of preceding stimuli. However, they were not elicited by the same stimulus sequences when the patient's attention was directed elsewhere and categorization was not required. These results indicate that the MTL potentials reflect endogenous as opposed to obligatory processes. The time course and task dependence of the MTL potentials suggest that MTL structures could contribute to P300 and related event-related potentials on the scalp.

Acoustic Stimulation↗

PubMed1988

ERPs predictive of subsequent recall and recognition performance.

By exploiting measures of information processing complementary to those obtained from behavioral studies, electrophysiological studies of human memory may provide insights into the cognitive processes associated with encoding. In the present experiment, subjects viewed words under incidental learning conditions in which each word required a two-choice decision based on semantic criteria (interesting/uninteresting or edible/inedible). Memory for those words was subsequently assessed by a free recall test and then a recognition test. Event-related brain potentials elicited in response to the original presentation of each word were found to differ as a function of later memory performance. Over the 400-800 ms latency range, responses to remembered words were positive relative to responses to forgotten words, especially for recall. These electrophysiological differences are interpreted as reflections of processes that correlated with encoding.

Adult↗

PubMed1988

Localization of human sensorimotor cortex during surgery by cortical surface recording of somatosensory evoked potentials.

The traditional means of localizing sensorimotor cortex during surgery is Penfield's procedure of mapping sensory and motor responses elicited by electrical stimulation of the cortical surface. This procedure can accurately localize sensorimotor cortex but is time-consuming and best carried out in awake, cooperative patients. An alternative localization procedure is presented that involves cortical surface recordings of somatosensory evoked potentials (SEP's), providing accurate and rapid localization in patients under either local or general anesthesia. The morphology and amplitude of median nerve SEP's recorded from the cortical surface varied systematically as a function of spatial location relative to the sensorimotor hand representation area. These results were validated in 18 patients operated on under local anesthesia in whom the sensorimotor cortex was independently localized by electrical stimulation mapping; the two procedures were in agreement in all cases. Similar SEP results were demonstrated in an additional 27 patients operated on under general anesthesia without electrical stimulation mapping. The following three spatial relationships between SEP's and the anatomy of the sensorimotor cortex permit rapid and accurate localization of the sensorimotor hand area: 1) SEP's with approximately mirror-image waveforms are recorded at electrode sites in the hand area on opposite sides of the central sulcus (P20-N30 precentrally and N20-P30 postcentrally); 2) the P25-N35 is recorded from the postcentral gyrus as well as a small region of the precentral gyrus in the immediate vicinity of the central sulcus: this waveform is largest on the postcentral gyrus about 1 cm medial to the focus of the 20- and 30-msec potentials; and 3) regardless of component identification, maximum SEP amplitudes are recorded from the hand representation area on the precentral and postcentral gyri.

Anesthesia, General↗

PubMed1987

Prevention of pneumococcal bacteremia in a child with acquired immunodeficiency syndrome-related complex.

Explore the source record for details and available documents.

AIDS-Related Complex↗

PubMed1987

Intracranial recordings of endogenous ERPs in humans.

Target detection and stimulus omission tasks of the type used to elicit scalp P300 and related potentials were studied in a group of 40 patients in whom intracranial electrodes had been implanted during evaluation for epilepsy surgery. Two distinct task-related intracranial ERP patterns have been identified, one in the medial temporal lobe and the other in the frontal lobe. These patterns overlap in time with each other and with scalp P300. The temporal lobe pattern consists of positive potentials dorsal and posterior to the hippocampus, sharp negative potentials within and medial to the hippocampus, and positive potentials in the vicinity of the amygdala. This 3-part pattern has been observed for counted targets in auditory, somatic, and visual modalities and for counted stimulus omissions with latencies that covary with scalp P300. This pattern is absent or greatly attenuated in ignore tasks when targets were not counted. The frontal pattern consists of a widespread negative-positive-negative sequence at deep sites which in some patients inverts in polarity at superficial sites and on the scalp. This pattern is consistent with a source or sources within the frontal lobe. Differences in shape and onset latency between the frontal and medial temporal lobe ERP patterns indicate that the former are not simply a distant recording of the latter. These data strongly suggest multiple contributions to scalp P300.

Acoustic Stimulation↗

PubMed1987

Transplantation of thymic tissue into patients with AIDS. An attempt to reconstitute the immune system.

Thymic epithelial fragments were transplanted into 15 patients in an advanced stage of the acquired immunodeficiency syndrome (AIDS). One patient was given interleukin 2 in addition to thymic tissue. We demonstrated the following: Thymic epithelial fragments cultured before transplantation to remove T cells survived for months after transplantation in eight of 15 patients and seemed to be responsible for a partial, selective, but transient repopulation of the circulating T-cell pool. The absolute number of T8 cells, but not T4 cells, increased three to four weeks after the procedure in eight of the 15 subjects. This increase in T8 cells was associated with clinical improvement in some cases and increased T-cell responsiveness in vitro. Thymic tissue transplantation as a single therapeutic maneuver is unlikely to reconstitute the immune system of patients with AIDS, but the potential of the approach, used in combination with agents that block replication of human T-cell lymphotropic virus type III, deserves further study.

Acquired Immunodeficiency Syndrome↗

PubMed1986

Microcystic adnexal carcinoma. Immunohistologic observations suggesting dual (pilar and eccrine) differentiation.

Microcystic adnexal carcinoma (MAC) is a locally aggressive neoplasm that has recently been recognized as a clinicopathologic entity. Its histologic appearance includes both pilar and eccrine differentiation. We initially treated two patients with MAC of the cheek and of the nasolabial fold, respectively; by microscopically controlled excision because of the contiguous growth of the tumors. Despite the benign histologic appearance, there was deep and extensive infiltration of the subcutaneous tissue. Both patients responded favorably to initial treatment with microscopically controlled excision. In addition, immunoperoxidase staining for carcinoembryonic antigen supported the dual differentiation of this unusual neoplasm. We speculate that previous radiotherapy may be an important predisposing factor in the pathogenesis of MAC.

Biopsy↗

PubMed1986

Antibody against the human immunodeficiency virus in commercial intravenous gammaglobulin preparations.

In a 6-month study, antibody levels against the human immunodeficiency virus (HIV) were determined in intravenous gammaglobulin preparations and 45 serum samples from 20 patients on gammaglobulin therapy. All 10 lots of a reduced and alkylated preparation and 4 of 8 lots of a pH4/pepsin-treated preparation were seropositive by enzyme-linked immunosorbent assay (ELISA). By Western blot analysis, 8 of 10 lots of the reduced and alkylated preparation and 3 of 8 lots of the pH4/pepsin-treated preparation were positive. Before gammaglobulin infusion, 2 of 45 preinfusion samples were seropositive by ELISA but seronegative by Western blot. After infusion, 15 of 45 samples were seropositive by ELISA, and 8 had antibody against p24 by Western blot. Seropositivity persisted for less than 1 month. Cultures of HIV-positive intravenous gammaglobulin lots were negative for reverse transcriptase activity or viral antigen expression. These results suggest that current methods of preparation either exclude or inactivate HIV.

Antibodies, Viral↗