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Showing papers by "University of Maryland, Baltimore published in 1982"


Journal ArticleDOI
16 Dec 1982-Nature
TL;DR: A highly significant correlation is demonstrated between levels of a plasma inhibitor of (Na+ + K+)ATPase activity and mean arterial blood pressure in normotensive and hypertensive individuals, providing evidence for the involvement of a circulating Na+ pump inhibitor in the genesis of essential hypertension.
Abstract: The aetiology of essential hypertension, a disease prevalent in cultured societies, is unknown. However, much evidence suggests that abnormal sodium metabolism has a critical role—this has led to the hypothesis that an increase in the circulating concentration of an inhibitor of (Na+ + K+) ATPase is responsible for the increased peripheral vascular resistance in essential hypertension1. Evidence for relatively high levels of a Na+ pump inhibitor in essential hypertension has come from bioassay and cytochemical assays of plasma and urine from normotensive and hypertensive individuals2,3. There is also evidence for increased plasma levels of a Na+ pump inhibitor in some animal models (for example, renal and deoxycorticosterone acetate (DOCA) models) of hypertension4. Nevertheless, direct biochemical determination of (Na+ + K+) ATPase inhibition by this substance has not yet been reported. We demonstrate here, with a kinetic (Na+ + K+) ATPase assay, a highly significant correlation between levels of a plasma inhibitor of (Na+ + K+)ATPase activity and mean arterial blood pressure (MAP) in normotensive and hypertensive individuals. These data provide evidence for the involvement of a circulating Na+ pump inhibitor in the genesis of essential hypertension. Moreover, our assay methods may be useful for the isolation and characterization of this inhibitor.

555 citations


Journal ArticleDOI
TL;DR: The relationship of this organism to the environment reveals a close association with other marine organisms especially copepods on which the Vibrios depend for survival in winter months and growth in summer months and a uniquely provocative disparity between human strains of V. parahaemolyticus.
Abstract: Approximately 30 years have elapsed since Dr. Fujino's original discovery that Vibrio parahaemolyticus (then termed Pasteurella parahemolytica) was the cause of "summer diarrhea" in Japan. Since that finding, V. parahaemolyticus has been established as a cause of gastroenteritis in numbers and places approaching global proportions. It has been isolated in marine and estuarine areas almost worldwide and despite its halophilic nature, V. parahaemolyticus has been isolated from saline-free waters. The relationship of this organism to the environment reveals a close association with other marine organisms especially copepods on which the Vibrios depend for survival in winter months and growth in summer months. There is a uniquely provocative disparity between human strains of V. parahaemolyticus which are Kanagawa phenomenon (KP) positive and the environmental strains which to a large extent are KP negative, the significance being that pathogenicity is measured according to the Kanagawa phenomenon (hemolytic activity) reaction. The hemolysin of the pathogenic strains is a thermostable, cardiotoxic protein, which thus far has not been implicated in the mechanism(s) which causes human gastroenteritis. The interest in this organism has been widened in recent years by the finding that similar organisms, V. alginolyticus, lactose positive vibrios and group F vibrios also cause serious disease in humans.

484 citations


Journal ArticleDOI
TL;DR: This study reconfirms the high mortality rate if ICP is 25 mm Hg or greater; however, the data also document that early aggressive treatment based on ICP monitoring significantly lessens the incidence of ICP of 25mm HG or greater and reduces the overall mortality rate of severe head injury.
Abstract: ✓ During 1977–1978, 127 patients with severe head injury were admitted and underwent intracranial pressure (ICP) monitoring. All patients had Glasgow Coma Scale (GCS) scores of 7 or less. All received identical initial treatment according to a standardized protocol. The patients' average age was 29 years; 60% had multiple trauma, and 35% needed emergency intracranial operations. Treatment for elevations of ICP was begun when ICP rose to 20 to 25 mm Hg, and included mannitol therapy and drainage of cerebrospinal fluid (CSF) when possible. Forty-three patients (34%) had ICP greater than or equal to 25 mm Hg; of these, 36 (84%) died. The mortality rate of the entire group was 46%. During 1979–1980, 106 patients with severe head injury were admitted and underwent ICP monitoring. Their average age was 29 years; 51% had multiple trauma, and 31% underwent emergency intracranial surgery. All patients received the same standardized protocol as the previous series, with the exception of the treatment of ICP. In thi...

430 citations


Journal ArticleDOI
TL;DR: This work has followed an arduous and often tortuous route to reach the current understanding of the physiological role of catecholamines (CAs) in the regulation of gonadotropin secretion.
Abstract: I. Introduction We have followed an arduous and often tortuous route to reach our current understanding of the physiological role of catecholamines (CAs) in the regulation of gonadotropin secretion. More often than not, the vast amounts of confusing literature on this subject have bewildered the novice and discouraged the faint of heart and, as such, research into the complexities of this system have waxed and waned over the 32 or more years since CAs first were implicated as regulators of gonadotropin secretion. Much of this confusion was due to: 1) lack of adequate methodology to measure CA secretion; 2) the use of complex and at times unusual experimental animal preparations and paradigms; 3) an inadequate understanding of the neuroanatomy of CA pathways in the brain; and 4) the use of many drugs which lack the specificity required to delineate the interplay that exists between CAs and the secretion of gonadotropic hormones. This is not to say that we now have deciphered the many complex central nervou...

369 citations


Journal ArticleDOI
TL;DR: The beneficial effect of stepped-care treatment on persons with diastolic pressures who had no evidence of end-organ damage and were not receiving antihypertensive medication when they entered the study is supported.
Abstract: In the Hypertension Detection and Follow-up Program, 7825 (71.5 per cent) of the 10,940 participants had diastolic blood pressures averaging between 90 and 104 mm Hg on entry into the study and were designated Stratum 1. Half were referred to their usual source of care in the community (the referred-care group), and half were treated intensively in special clinics (the stepped-care group). Five-year mortality in the Stratum 1 patients given stepped care was 20.3 per cent lower than in those given referred care (P less than 0.01). Particularly noteworthy was the beneficial effect of stepped-care treatment on persons with diastolic pressures of 90 to 104 mm Hg who had no evidence of end-organ damage and were not receiving antihypertensive medication when they entered the study. This subgroup had 28.6 per cent fewer deaths at five years among those treated with stepped care than among those treated with referred care (P less than 0.01). These findings support a recommendation that in patients with mild hypertension, treatment should be considered early, before damage to end organs occurs.

303 citations


Journal ArticleDOI
TL;DR: Improved resin-bonded retainers provide innovative, conservative, and viable alternatives to traditional fixed prosthodontics.
Abstract: Summary A technique was described for a retentive mechanism that etches the inner side of cast fixed partial denture frameworks. The etched metal ceramometal restoration was then bonded to the enamel surface utilizing the technique for acid etching enamel. Improved resin-bonded retainers provide innovative, conservative, and viable alternatives to traditional fixed prosthodontics.

285 citations


Journal ArticleDOI
06 May 1982-Nature
TL;DR: It is shown that passive protection of SV-infected mice from fatal paralytic central nervous system (CNS) disease may be mediated not only by antibodies which neutralize the infectivity of extracellular virus particles but also by those lacking this capacity, which react preferentially with virus- infected cells.
Abstract: Among the heterogeneous population of antibodies specifically induced during many acute viral infections, those having virus-neutralizing activity in vitro are generally considered to be most important for recovery and immunity to reinfection. Similarly, the ability to stimulate production of circulating neutralizing (NT) antibodies is a major criterion for evaluating the immunoprophylactic potential of many antiviral vaccines1. Although there is obviously an association between NT antibody induction and host resistance, we present here data which indicate that other virus-specific antibodies lacking NT function may be equally important in conferring protective immunity to alphaviruses. We used monoclonal antibodies against Sindbis virus (SV) to demonstrate that passive protection of SV-infected mice from fatal paralytic central nervous system (CNS) disease may be mediated not only by antibodies which neutralize the infectivity of extracellular virus particles but also by those lacking this capacity, which react preferentially with virus-infected cells.

222 citations


Journal ArticleDOI
TL;DR: In this paper, the histogenesis of epidermoid metaplasia and restoration of normal mucociliary epithelium following mechanical injury was studied in hamster tracheal epithelial cells with single pulse or continuous infusion of tritiated thymidine (3HTdR) combined with colchicine blockade of metaphase mitoses.
Abstract: In companion papers we described in detail the morphologic changes that occur during tracheal regeneration following focal mechanical injury (Keenan et al. 1982a), and the proliferative events that occur following multifocal injury, particularly the dominant role played by the secretory cell population in the regenerative process. In this paper the histogenesis of epidermoid metaplasia and restoration of normal mucociliary epithelium following mechanical injury was studied in hamster tracheal epithelium with single pulse or continuous infusion of tritiated thymidine (3HTdR) combined with colchicine blockade of metaphase mitoses. Both small and large wounds were produced in the same animal, in the dorsal and ventral tracheal semicircles respectively. At 12 h following injury, 14.2% of the dorsal epithelial cells and 34.6% of the ventral epithelial cells were lost. Viable cells migrated into the denuded wound sites, covering the small wounds by 12 h and the larger wounds by 48 h. By 27 h a peak mitotic rate (MR) was reached in the dorsal epithelium (MR = 18.1%), but mitotic activity in the ventral epithelium did not peak until 33 h (MR = 13.3%). In both tracheal semicircles, secretory cells accounted for over 76% of the labeled mitotic cells. Ciliated cells did not label or divide. Epidermoid metaplasia was first observed at 33 h in both semicircles. It was transient in the small wounds, but persisted through 168 h in the large wounds. Almost all the epidermoid cells were labeled by continuous3HTdR infusion. A very few pre-ciliated cells appeared first at 33 h but they peaked in numbers at 72 h in both the dorsal (8.0%) and ventral (5.5%) semicircles. These large, pale staining cells were not labeled by single pulse3HTdR but were labeled by continuous3HTdR infusion. Later, large, pale staining cells morphologically similar to pre-ciliated cells, and with identical labeling patterns, were observed budding cilia. Ciliated cell numbers were restored to control level in the dorsal semicircle by 168 h, but only to 84% of control values in the ventral semicircle, where epidermoid metaplasia persisted. These data suggest that secretory cells have a greater proliferative potential than basal cells in regenerating tracheal epithelium, and that they contribute to the development of both transient and persistent epidermoid metaplasia and the production of new secretory cells. Moreover, these proliferating secretory cells produce ciliated cells via a transient pre-ciliated cell which develops cilia and matures in the regenerating epithelium.

217 citations


Journal ArticleDOI
TL;DR: The proportion of a child's food samples that contained E. coli was significantly related to the child's annual incidence of diarrhoea associated with enterotoxigenic E. Escherichia coli, highlighting the importance of seeking locally available foods that are hygienic as well as nutritious to supplement the diets of breastfeeding children in developing countries.
Abstract: In longitudinal studies of infectious diseases and nutrition in Bangladesh, we determined the degree of bacterial contamination of traditional weaning foods and evaluated the role of these foods in the transmission of diarrhoeal diseases. 41% of samples of food items fed to weaning aged children contained Escherichia coli; these organisms were used as indicators of faecal contamination. Milk and foods prepared particularly for infants were more frequently and heavily contaminated with E. coli than was boiled rice, and E. coli levels were found to be related to the storage of cooked foods at high environmental temperatures. 50% of drinking water specimens also contained E. coli, but colony counts were approximately 10-fold lower than in food specimens. The proportion of a child's food samples that contained E. coli was significantly related to the child's annual incidence of diarrhoea associated with enterotoxigenic E. coli. This observation underscores the importance of seeking locally available foods that are hygienic as well as nutritious to supplement the diets of breastfeeding children in developing countries.

207 citations


Journal ArticleDOI
TL;DR: It is recommended that a typhoid control program include the identification of carriers followed by health education and therapeutic interventions.
Abstract: As part of a program to control endemic typhoid fever in Santiago, Chile, an assessment was made of the magnitude of the reservoir of chronic carriers of Salmonella typhi. The availability of an accurate census and reliable data on the prevalence of biliary disease and of S. typhi carriage among persons with cholecystitis allowed an unusually precise estimate of the number of carriers. In 1980 there existed 25,019 female and 4,575 male carries in a population of 4,264,514, yielding a crude prevalence of 694 carriers per 10(5) population. Because of the magnitude of this human reservoir, which includes many females of greater than 40 years of age, it is recommended that a typhoid control program include the identification of carriers followed by health education and therapeutic interventions.

200 citations


Journal ArticleDOI
TL;DR: Hair cadmium and lead content were related to intelligence tests, motor impairment assessments, and school achievement scores from 149 children aged 5 to 16 yr enrolled in rural Maryland public school systems and Hierarchical regression analyses suggest that Cadmium has a significantly stronger effect on verbal I.Q. than does lead.
Abstract: Hair cadmium and lead content were related to intelligence tests, motor impairment assessments, and school achievement scores from 149 children aged 5 to 16 yr enrolled in rural Maryland public school systems. Hair cadmium and lead were significantly correlated with both intelligence scores and school achievement scores, but not motor impairment scores. Significant relations with I.Q. were obtained after regressing out demographic factors and were observed, even in children within a normal I.Q. range. Evidence of different effects of cadmium and lead on cognitive development was obtained. Hierarchical regression analyses suggest that cadmium has a significantly stronger effect on verbal I.Q. than does lead and that lead has a stronger effect on performance I.Q. than does cadmium.

Journal ArticleDOI
15 Jul 1982-Nature
TL;DR: It is found that ICa could be decreased or cancelled with the calcium-blocking agent diltiazem (Herbesser), but that the same concentration of the drug potentiated the twitch, tetanus and contractures.
Abstract: It has been proposed1 that an influx of calcium ions into twitch muscle fibres during an action potential might initiate contraction. However, when external Ca2+ is lowered to 10−8 M with EGTA, the fibres can produce normal twitches for many minutes2,3. Nevertheless, a clear Ca2+ influx during contraction has been demonstrated4,5, and it has been found that phasic skeletal muscle has an inward calcium current (ICa)6,7 which can give rise to calcium spikes8. In certain conditions, a reduction in external Ca2+ with 80–90 mM EGTA results in reversible blockade of excitation–contraction (e–c) coupling9, leading some authors to suggest7,9–11 that extracellular Ca2+ moved into the myoplasm due to ICa may be involved in the e–c coupling mechanism that triggers contraction. This proposition was further supported by the localization of ICa in the T-system, which circumvented the problem of the delay due to calcium diffusion from the surface membrane. We have now investigated whether ICa has a clear role in initiating or sustaining contractions in twitch muscle fibres. Our approach was to decrease or eliminate ICa with the calcium-blocking agent diltiazem (Herbesser) and to see how the twitch, tetanic and potassium-contracture tensions were affected. We found that ICa could be decreased or cancelled with the calcium-blocking agent, but that the same concentration of the drug potentiated the twitch, tetanus and contractures. We conclude, therefore, that ICa has no role in e–c coupling. A preliminary report of these results has been presented elsewhere12.

Book ChapterDOI
TL;DR: The role of nonsteroidal regulators in control of oocyte and follicular maturation is discussed, which interact to serve to control its maturation, responsiveness to gonadotropins, as well as to lead to control of the maturation of its oocyte.
Abstract: Publisher Summary This chapter discusses the role of nonsteroidal regulators in control of oocyte and follicular maturation. The ovarian follicle is bathed in a fluid rich in steroid hormones as well as nonsteroidal regulators which interact to serve to control its maturation, responsiveness to gonadotropins, as well as to lead to control of the maturation of its oocyte. The orderly maturation of an ovarian follicle and its oocyte is controlled by pituitary LH and FSH in concert with local intrafollicular regulators. The principal nonsteroidal follicular regulators are an oocyte maturation inhibitor, a luteinization inhibitor, a luteinization stimulator, FSH receptor binding inhibitor, and inhibin-F. OMI is a polypeptide

Journal ArticleDOI
TL;DR: Data indicate that alterations in the proestrous gonadotropin and prolactin surges occur early during the aging process in the female rat, which may be important in the age-related transition to estrous acyclicity.
Abstract: Plasma LH, FSH, and prolactin were measured in middle-aged (7- to 9-month-old) breeder and young (3-4 month old) female rats on proestrus. Sixty-eight percent of the middle-aged rats exhibited regular 4-day estrous cycles; the remainder showed irregular cycles 4-7 days in length. All young rats exhibited at least two consecutive 4-day cycles prior to use. The right atria of all rats were cannulated under ether anesthesia between 0700 and 0800 hr (14:10 light-dark cycle, lights on at 0400 hr). Blood was drawn at 0900 hr and at hourly intervals from 1200 to 2200 hr; each rat was bled a maximum of nine times. Plasma LH and FSH rose significantly later and peak concentrations were significantly lower in middle-aged rats. Baseline prolactin concentrations at 0900 and 2000-2200 hr were significantly higher in middle-aged female rats. These data indicate that alterations in the proestrous gonadotropin and prolactin surges occur early during the aging process in the female rat. Such changes may be importa...

Journal ArticleDOI
TL;DR: The results suggest that the arsenate efflux system is coupled to cellular ATP rather than an electrochemical proton gradient, possibly by an arsenate-translocating ATPase.
Abstract: Plasmid R773, which codes for resistances to arsenate, arsenite, and antimony, was introduced into Escherichia coli strain AN120, a mutant deficient in the H+-translocating ATPase of oxidative phosphorylation. Cultures depleted of endogenous energy reserves were loaded with 74AsO3-4, and arsenate efflux was measured after dilution into medium containing various energy sources and inhibitors. Rapid extrusion of arsenate occurred when glucose was added. Arsenate was extruded both against and down a concentration gradient. In this strain glucose allows formation of both ATP via substrate-level phosphorylation and an electrochemical proton gradient (or protonmotive force) via oxidation of the products of glycolysis. When oxidation was inhibited by cyanide, glucose metabolism still produced arsenate efflux. Energy sources such as succinate, which supplies a protonmotive force but not ATP, did not result in efflux. Measurement of intracellular ATP concentration under each set of conditions demonstrated a direct correlation between the rate of efflux and ATP levels. Osmotically shocked cells lost the ability to extrude arsenate; however, no arsenate-binding activity was detected in osmotic shock fluid from induced cells. These results suggest that the arsenate efflux system is coupled to cellular ATP rather than an electrochemical proton gradient, possibly by an arsenate-translocating ATPase.


Journal ArticleDOI
TL;DR: Serum antibodies to Norwalk virus and to rotavirus were measured during longitudinal studies of infectious diseases and nutrition in rural Bangladesh to find children with the lowest levels of antibody to rotvirus had the greatest risk of rotav virus diarrhea.
Abstract: Serum antibodies to Norwalk virus and to rotavirus were measured during longitudinal studies of infectious diseases and nutrition in rural Bangladesh. Initially, the prevalence of antibody to Norwalk virus was 7% in children younger than six months and increased to 80% in children two to five years of age. The incidence of titer increases was highest in one- and two-year-olds and in children who had low or undetectable levels of antibody. Some Norwalk virus infections appeared to result in diarrhea. Nearly all children had serum antibodies to rotavirus at the beginning of the study; however, children with the lowest levels of antibody to rotavirus had the greatest risk of rotavirus diarrhea. Over half of the children had a fourfold increase in titer of antibody to rotavirus during the year, and 7% had increases in two of the three study periods during the year. Most increases in titer of antibody to rotavirus appeared to result from subclinical infections.

Journal ArticleDOI
TL;DR: A new procedure for neovascular glaucoma that has reduced intraocular pressure (IOP) significantly and has caused relatively few postoperative complications is introduced.

Journal ArticleDOI
TL;DR: Results are consistent with the general hypothesis that prolonged apnea or airway obstruction is part of the pathophysiologic process resulting in SIDS and those hypotheses implicating unstable respiratory activity during sleep as well as apnea and pharyngeal/laryngeals dysfunction induced by liquid stimulation of the upper airway.
Abstract: Respiratory observations made during nutritive feeding and a complete daytime nap within the first week of life on ten newborns who subsequently were victims of sudden infant death syndrome (SIDS) were compared with normative data based on 1,301 infants of comparable ages. Measurements were obtained of all apneic pauses and/or transient respiratory obstructive events at least two seconds in duration. A statistically significant increased number of future SIDS victims were found to have an unusual amount of apnea/obstruction episodes during nutritive feeding when compared with the normative group. Future SIDS victims, as a group, also had an increased frequency of apneic pauses during sleep. Furthermore, all SIDS victims demonstrated either an unusual amount of apnea/obstruction during nutritive feeding or apneic pauses during sleep. None of the airway obstruction measures during sleep differentiated the SIDS infants from the normative group. These results are consistent with the general hypothesis that prolonged apnea or airway obstruction is part of the pathophysiologic process resulting in SIDS and those hypotheses implicating unstable respiratory activity during sleep as well as apnea and pharyngeal/laryngeal dysfunction induced by liquid stimulation of the upper airway. They are also compatible with the growing body of evidence indicating that factors that predispose an infant to SIDS originate in the perinatal period.

Journal ArticleDOI
TL;DR: The data demonstrate that during long-term spastic hemiplegia in man some motor units develop increased fatigability and prolonged-twitch contraction times, reflecting the dynamic properties of muscle.

Journal ArticleDOI
TL;DR: CP-induced ARF in the maintenance phase has a multifactorial pathogenesis and tubular fluid "backleak" and a primary decrease in glomerular filtration contribute to the decrease in GFR, and the possible role of intratubular obstruction cannot be excluded.

Journal ArticleDOI
TL;DR: Phase and modulation measurements can distinguish between time-dependent processes and spectral heterogeneity by observation of any feature described above and under favorable conditions, a two-state excited-state process can be distinguished from a continuous multiple- state process.

Journal ArticleDOI
TL;DR: Observations suggest that microtubules are involved in the initial establishment of cytoplasmic asymmetry and process development, and glial filaments may play a role in maintaining and stabilizing the overall geometry of the mature astrocyte.


Journal ArticleDOI
TL;DR: Recent infection could be accurately serodiagnosed by levels of vibriocidal antibody and antitoxin (by IgG ELISA in a convalescent-phase serum) by agreeing most closely with those of the ELISA, the most sensitive antitoxin assay, in serologically detecting clinical and subclinical infections.
Abstract: Sera from 147 volunteers were examined for vibriocidal antibody by the tube-dilution method before and after they ingested 10(3)-10(6) Vibrio cholerae organisms. Titers increased significantly after challenge in 97% of 110 persons who excreted V. cholerae. In 12% of the bacteriologically confirmed infections, the titer increased significantly only to the homologous (Inaba or Ogawa) serotype. Levels of vibriocidal antibody decreased substantially between one and six months after challenge, but they usually remained elevated over base-line values. Levels of antitoxin to V. cholerae were measured by IgG enzyme-linked immunosorbent assay (ELISA), rabbit skin permeability tests, and adrenal cell techniques in 73 pairs of prechallenge and postchallenge sera. Results of the vibriocidal assay agreed most closely with those of the ELISA, the most sensitive antitoxin assay, in serologically detecting clinical and subclinical infections. Recent infection could be accurately serodiagnosed by levels of vibriocidal antibody and antitoxin (by IgG ELISA) in a convalescent-phase serum.

Journal ArticleDOI
TL;DR: None of 114 stool-culture isolates yielded cholera enterotoxin, and none of the 20 volunteers had significant increases in serum titers of antitoxin as measured by enzyme-linked immunosorbent assay although six of the volunteers had slightly elevated vibriocidal antibody levels.
Abstract: Nonenterotoxigenic strains no. 1196-78 and no. 1074-78 of Vibrio cholerae serogroup O1 (biotype El Tor, serotype Ogawa) were isolated from sewage water in Brazil and fed to 20 volunteers. Neither strain caused diarrhea. None of the seven volunteers who ingested Ogawa strain no. 1074-78 (10(6) organisms) excreted the organism whereas eight of the 13 volunteers who ingested Ogawa strain no. 1196-78 (10(6) or 10(8) organisms) did excrete the organism in their stools. None of 114 stool-culture isolates yielded cholera enterotoxin, and none of the 20 volunteers had significant increases in serum titers of antitoxin as measured by enzyme-linked immunosorbent assay although six of the volunteers had slightly elevated vibriocidal antibody levels. Six volunteers used as controls and four volunteers who had stool cultures positive for strain no. 1196-78 of V. cholerae were challenged with pathogenic El Tor Ogawa strain no. E7946 (10(6) organisms) to determine if previous ingestion of the Brazilian strain would induce protective immunity. All 10 of the volunteers developed diarrhea, and the severity of the illness was similar in both groups.

Journal ArticleDOI
TL;DR: It is indicated that very low doses of kainic acid directly applied to hippocampal CA3 neurons, can elicit bilateral changes in the electroencephalogram indicative of repetitive limbic seizures which are not necessarily accompanied by neuronal degeneration.


Journal ArticleDOI
TL;DR: No consistently altered sensitivity to monoaminergic stimulation by amphetamine in bipolar affective disorder was demonstrated in this study, one of the first reports of familial (possibly genetic) variation in a psychostimulant drug response in man.

Journal ArticleDOI
TL;DR: This study is concerned with P300 and Slow Wave in an experimental paradigm in which information is transmitted by a combination of two successive events (a ‘message’).
Abstract: This study is concerned with P300 and Slow Wave in an experimental paradigm in which information is transmitted by a combination of two successive events (a ‘message’). Each event delivered essential information for understanding the message, but the meaning of the message could not be determined until occurrence of the second event. The amount of information in each event was varied by varying its perceptual difficulty. Increasing perceptual difficulty causes an information loss, termed equivocation. A positive Slow Wave was elicited by both events. Slow wave was clearly increased in amplitude by equivocation in the eliciting event, and less clearly increased in amplitude by equivocation in the other event. The first event elicited a small P290 component. It could not be determined whether this component corresponded to P300. The second event elicited a large P300. This component was much reduced in amplitude by equivocation in the second event, but was only moderately reduced in amplitude by equivocation in the first event.