Showing papers in "Annals of the New York Academy of Sciences in 1981"

Input, interaction, and second language acquisition

Abstract: It is now well established that, under as yet little understood conditions, native speakers modify their speech when addressing non-native speakers. Discussion of native speaker-non-native speaker (NS-NNS) conversation, however, often conflates two related but distinguishable phenomena, input to and interaction with the NNS. Input refers to the linguistic forms used; by interaction is meant the functions served by those forms, such as expansion, repetition, and clarification. This paper explores the possibility that a distinction between these two facets of NS-NNS conversation is important both theoretically, in order better to understand the second-languageacquisition (SLA) process, and in practice, when considering what is necessary and efficient in SL instruction.

The acceleration of cosmic rays by shock waves

Abstract: The problem of the origin of galactic cosmic rays is a particularly difficult one despite the fact that rather detailed measurements of the properties of cosmic rays can be made, at least in the vicinity of the Sun. The current situation has been well reviewed by Lingenfelter (1) who points out that there are several linked problems to be solved, namely the question of sources and acceleration mechanisms, propagation within the galaxy, escape from the galaxy and of course solar modulation which affects the interpretation of the observations, especially below ~ 1 GeV/nuc. It is usually supposed that these problems can be treated separately, so that the sources (perhaps supernovae, pulsars, black holes, flare stars, etc.) simply provide cosmic rays with given elemental and isotopic abundances and given spectra, which then propagate independently by diffusion through the interstellar medium, producing secondaries and perhaps losing energy as they do so until they eventually leave the galaxy by some means, which is usually described in terms of a “free escape” boundary condition to the diffusion equations.

Background and present status of research on platelet-activating factor (paf-acether)

Abstract: A leukocyte-dependent mechanism capable of releasing histamine from platelets was first reported in 1966, and a soluble principal intermediate between rabbit leukocytes and platelets was detected in 1971.’e2 It was at that time described as “lytic” and was not characterized. One of us described the methodology for obtaining this substance routinely, started its characterization, named it platelet-activating factor (PAF), and showed that it was released from rabbit basophils through an IgE-dependent proces~ .~ Its presence was subsequently demonstrated in human leukocytes, and aggregation and the release reaction were shown for human platelet^.^ Finally, most of its known physicochemical characteristics, including its phospholipid nature, were described (see refs. in 5) . At this stage, we knew that PAF was a glycerophospholipid with a choline polar head group, an ester-linked acyl chain on the carbon 2, and no ester link at the carbon 1 position.6 A new class of phospholipid mediator was therefore proposed. Finally, the structure of the mediator was elucidated (FIG. 1 ) as being 1 -O-alkyl-2-acetyl-glyceryl-3-phosphorylcholine, and its total synthesis was achieved.’-g PAF is therefore now termed PAFacether, since it is an ether-lipid and has an acetate residue. We think it is preferable to keep to the established name, and not to replace it by the initials of the now recognized chemical name, in order to preserve a link with previous accomplishments and reduce literature confusion. For similar reasons prostaglandins or heparin, for instance, were not renamed when structures became available. Given the numerous substances present in biological fluids and cell supernatants that can activate platelets, it was necessary to define PAF-acether strictly. Even before knowing its structure, we used the following criteria to distinguish it from arachidonic acid, thrombin, ADP or prostaglandins:

ADH Action: Evidence for a Membrane Shuttle Mechanism

Abstract: It is now well established that the action of antidiuretic hormone (ADH) is mediated by cAMP and that ADH induces physiological changes in the luminal cell Less certain at this stage are the events that link an elevation of intracellular cAMP to an increase in luminal membrane permeability to water and solutes. In recent years, three observations on the toad bladder have provided important insights into these post-CAMP events: (1) The demonstration that by a variety of maneuvers the changes in water permeability can be dissociated from changes in solute Permeability and therefore that separate pathways are involved.5-7 (2) The observations demonstrating that microtubules and microfilaments are involved in the water permeability response.8-10 (3 ) The finding that intramembrane particle aggregates visualized by freeze-fracture electron microscopy are associated with the modulation of luminal-membrane water pem1eabi1ity.ll-l~ Observations reported by many laboratories clearly demonstrate that these organized membrane structures perform an important role in the action of ADH.ll-la Most workers in the field now strongly suspect that these structures are the site of transmembrane water channels. The evidence that aggregates play a role in the ADH response has been discussed in several review papers.l73 Here we will describe how freeze-fracture observations have led to a new proposal for the mechanism of action of ADH and discuss to what extent this proposal is supported by the available evidence.

A perspective on the application of genetic engineering: stability of recombinant plasmid

Abstract: DNA cloning with vector plasmid and/or phage is stimulating not only in the interests of biological science but also in applications such as production of a new medicine, enhancement of yield in a particular metabolite in the fermentation industry, development of a new plant in the agricultural field, etc. Despite the substantial “species barrier” described schematically in FIGURE 1, not a few examples of cloning foreign DNA molecules in host cells have been made available.’.’ For instance, once a specific gene is cloned, metabolites originating from the specific gene might be produced in large quantities due to the gene dosage effect.3 To exaggerate, the contribution of genetic engineering to the biological world is deemed to be revolutionary rather than evolutionary. Although the aspects and/or regions to which genetic engineering is closely related are comprehensive in this context, this paper will pay attention only to a limited area, i.e., the subject of expression and stability of a cloned gene or genes in the cultivation of host cells. Unless cloned genes are kept in situ in vector plasmid during replication in coordination with the growth of host cells, it is not possible to employ the recombinant plasmid as an agent to enhance production of specific materials in industry. Before proceeding to clarify the significance of genetic engineering in this work, a few examples on “stability” and “instability” in plasmid manipulation will be presented.

Applications of Scanning Electron Microscopy to Taphonomic Problems

Abstract: HOSE WHO TRY to reconstruct past environments and hominid T behaviors have only four sources of information: (1) geological evidence; (2) the preserved remains of various hominid and nonhominid species; (3) occasionally, artifacts fashioned and used by our near or distant ancestors; (4) imagination or divine inspiration. Given that the last of these is difficult to use in persuading critics and that the interpretation of artifacts and geological exposures is best discussed by others, I shall focus in this paper on the fossil or osteological evidence of once-living animals and its interpretation. Powerful as such evidence may be in providing glimpses of the past, it is vulnerable to massive distortion. Various agents that act on bones and teeth during the postmortem and predepositional period differentially destroy, preserve, transport, or concentrate skeletal elements until an assemblage may bear little resemblance to the animal community (or bone community) from which it was drawn. As a taphonomist, I must ask of each assemblage how badly i t misrepresents the original collection of bones or species. This question underlies all attempts at paleoecological reconstruction. Answering i t is equally important whether the assemblage has been retrieved from an archeological stie only a few thousand years old or from a paleontological site many millions of years old. In order to answer this question, various studies1-15 of modern processes of death, decay, and dispersal of bones have been carried out.

Directional sensitivity of individual vertebrate hair cells to controlled deflection of their hair bundles

Abstract: Among the most striking and consistent morphological features of vertebrate hair cells is the geometrical arrangement of their mechanosensitive organelles, the hair bundles. These structures each consist of 30-200 microvilluslike stereocilia and a single, eccentrically placed, axonemal kinocilium. Three geometrical features of hair bundles are widespread, if not universal. First, the stereocilia and kinocilium are inserted into the cellular apex in a regular, hexagonal array. Second, the lengths of stereocilia increase monotonically from one edge of the hair bundle to the other, but are approximately equal within a row of stereocilia across the hair bundle. Finally, the kinocilium is located at the edge of the hair bundle at which the longest stereocilia occur. Distortions of these features may occur; for example, the spacing of stereocilia is not absolutely uniform in some hair cells, but varies from one edge of the hair bundle to the other. Hair bundles become progressively distorted and asymmetrical as the apex of the mammalian cochlea is approached. The kinocilium, although present in ontogeny, is lost from some hair cells in mammalian cochleas. Even in these exceptional cases, however, the general pattern of arrangement of the hair bundle is evident.

Velocity storage, nystagmus, and visual‐vestibular interactions in humans*

Abstract: A mechanism that stores activity related to slow-phase eye velocity plays an important role in producing vestibular nystagmus, optokinetic nystagrnus (OKN) and visual-vestibular interactions.'.' This mechanism is present in a wide range of species [see Reference 3 for review] and has been studied extensively in monkeys. Stored activity promotes ocular following during OKN and is responsible for optokinetic after-nystagmus (OKAN).' During vestibular nystagmus, stored activity lengthens the time over which compensatory eye movements are rnaintained.2s4 Modeling of the vestibulo-ocular reflex [VOR) has shown that a single storage element is capable of mediating these responses and can reproduce many phenomena of visual-vestibular interactions.' Manifestations of stored activity also are found in neurons in the vestibular nuclei of the monkey. Canal afferents in the vestibular nerve have a decay time constant of about 5-6 seconds after pulses of a~celeration.~ The decay time constant of neurons in the vestibular nuclei always is longer than that of canal afferents, usually varying between 10 and 30 seconds depending on the state of habit~ation.'.~ These same central neurons also are activated during OKN and OKAN. This demonstrates stored activity in firing rates of vestibular nuclei neurons and supports the theory of a common storage element. While this storage mechanism has been studied in animals, it is not known whether it plays a role in generating or modulating nystagmus in humans. Because the dominant time constant of the cupula-endolymph system and of activity in semicircular canal afferents cannot be determined directly in man, other ways have to be found to demonstrate the presence of stored activity in the oculomotor response. One way is by the presence of OKAN. OKAN represents the steady discharge of activity related to slow-phase velocity stored during exposure to a moving Storage of activity also is manifest in visual-vestibular interactions. Mowrer and Ter Braak were the first to show that postrotatory nystagmus is weaker after rotation in light than in darkness. They inferred that OKAN had summated with the vestibular after-nystagmus to reduce or abolish it. In similar experiments on humans, after-nystagrnus was reduced

Structural studies on a biologically active hexasaccharide obtained from heparin.

Abstract: The isolation from heparin of oligosaccharides active in some specific coagulation assays should allow the study of the minimal critical saccharidic sequences responsible for the various biological effects of this anticoagulant drug. For this purpose, a decasaccharide' as well as two octasaccharides2p3 were recently isolated and characterized. These products have a high anti-factor Xa activity (evaluated by the assay of Yin et a1.J which is related to the ability to bind antithrombin-111 (AT-111). The structural studies carried out on the octasaccharide that we have isolated have led us to propose for this compound the following sequencezv5: 4, 5unsaturated-2-0-sulfate uronic acid, N-sulfate-D-glucosamine, L-iduronic acid, N-acetyl-D-glucosamine, D-glucuronic acid, N-sulfate-3-0-sulfate D-ghcosamine, 2-0-sulfate-iduronic acid, N-sulfate-D-glucosamine (FIG. 1, A-H) . Nuclear magnetic resonance (nmr) studies, originally carried out on the decasaccharide and then on the octasaccharide A-H,6 revealed the presence in these products of an extra-signal at 57-59 ppm never reported before in heparin. This signal was then related to the presence of an 0-sulfate group at C-3 of a glucosamine

Patterns of narcotic drug use in a cancer pain clinic

Abstract: The treatment of pain caused by chronic disease presents several serious problems. Relief of moderate to severe pain often requires narcotic analgesics, yet physicians are often reluctant to use them because of their abuse This reluctance is further encouraged by the fact that these drugs are carefully monitored by federal and state governments and physicians in prescribing such drugs, and pharmacists in dispensing such prescriptions must follow strict regulations. In addition, the pharmacology of narcotic analgesics is poorly understood by many physicians and their patients, who believe that physical dependence and addiction are interchangeable terms. As a result, physicians generally tend to underuse narcotics in medically ill patients with severe pain 4, and this issue has recently received much public attention.6. This article reviews the limited available data on the use of narcotics in patients with chronic medical illness and our own experience in treating patients with pain due to cancer, to determine the patterns of narcotic drug usage.

Glass transition in the hard-sphere model and kauzmann's paradox*

Abstract: The transformation from a metastable supercooled liquid to an amorphous solid is one of the more common and technologically interesting amongst experimental phase transitions, but its classical, irreversible, and statistical thermodynamic descriptions are poorly developed. Since Kauzmann,’ in 1947, pointed out the paradoxical observation of the impending entropy “catastrophe” at the onset of glass formation, the question of the termination of the liquid state a t low temperatures has, to cite Anderson from a recent publication of lecture notes,’ remained problematical. In those lectures, emphasis was placed upon spin glasses, but the most promising approach for simple continuous phase systems, more akin to supercooled liquids, is that of molecular dynamics (MD) simulation. These computations have now been reported for a variety of models, and reviewed recently by Angel1 et al.3 Some of the sytems studied are sufficiently simple to be amenable to theoretical development and, a t the same time, yield valuable information on the role of the intermolecular potential i n glass formation phenomenology. This viewpoint is endorsed in a broader review of the relevant literature by Frenkel and M c T a g ~ e . ~ The simplest model that might reasonably be expected to exhibit glass formation reminiscent of laboratory liquids is that of classical hard spheres, first investigated using MD methods by Alder and Wainwright.’ Considerations of their self-diffusion data: together with virial series equations of state,’.’ and a preliminary MD computation, in which 500 hard spheres were rapidly compressed, indicated an underlying thermodynamic anomaly associated with the disappearance of translational diffusion in the process of glass formation. Gordon et al.” analyzed the early Alder-Wainwright data for 32 ~ p h e r e s , ~ however, reaching contrary conclusions: that there should be no glass transition of a thermodynamic nature in the hard-sphere model and that the thermodynamic properties and diffusivity s.hould, appart from operational retardation effects, be continuous up to amorphous close packing in a metastable phase space. A further series of densification “experiments” were carried out for small (32 and 100) hard-sphere systems.” The results were largely inconclusive because of the fluctuations exhibited by small systems, periodic-boundary-induced crystallization, and an operational glass transition range which, as a consequence of the fast and variable quench rate, was very broad compared to the usually rather sharp transition

Effects of gravity on rotatory nystagmus in monkeys

Abstract: The vestibulo-ocular reflex (VORJ stabilizes gaze in response to head rotation. If a step of angular velocity is given about a vertical axis, horizontal nystagmus is induced. Initially, its slow-phase velocity is compensatory; but as rotation continues with the subject in darkness, slow-phase velocity decays to zero. Deceleration induces postrotatory nystagmus. It is essentially anticompensatory since it occurs when the subject is stationary. There are several conditions under which the compensatory response of the VOR is improved. If rotation occurs in light, optokinetic nystagmus (OKN) is induced that helps hold the velocity of the slow phases of nystagmus close to that of the stimulus. During and after deceleration, activity stored during OKN summates with the vestibularly induced postrotatory nystagmus to reduce or abolish it.'-5 Compensatory eye velocities also can be enhanced by the introduction of a rotating gravity vector relative to the head. If subjects are rotated about an axis tilted from the vertical (off-vertical axis rotation), nystagmus is induced that lasts as long as rotation At the end of rotation, the after-nystagmus is weaker and shorter than that after rotation about a vertical axis. While the steady-state characteristics of the nystagmus induced by off-vertical axis rotation have been examined,6\" its dynamic characteristics are unknown. Moreover, there is little information about the relationship between perrotatory and postrotatory nystagmus induced by this type of stimulus. The purpose of this study was to characterize the dynamic aspects of the slow-phase velocity of nystagmus induced by off-vertical axis rotation. We wished to determine whether the velocity storage mechanism that is important for visual-vestibular interaction5 also plays a role in mediating nystagmus induced by rotation about an off-vertical axis.

The natural course of myasthenia gravis and effect of therapeutic measures

Abstract: Prior to the introduction in 1934 of anticholinesterase compounds for diagnosis and management of myasthenia gravis,’ the few patients recognized with the disease were mainly those with severe illness and high mortality.2* For example, the records of the Johns Hopkins and Maimonides Hospitals from 1900 to 1934 show a yearly average of two new patients, most of whom died within a year after onset. After 1934, the disease was much more frequently recognized (50 patients per year in these hospitals), but since almost all patients received anticholinesterase medication, and many had thymectomy and assisted ventilation after 1939,4 pressure or volume controlled respiration after 1960,5 and corticosteroids after 1966,6 it has not been possible to delineate the “natural” course of the disease. In 300 patients with generalized myasthenia gravis who were followed between 1940 and 1958, 30% died, 26% improved, 21 % remained unchanged, 13% went into remission, and 10% became w ~ r s e . ~ ~ Patients who had thymectomy did somewhat better (by about 7%) than those who did not. In reports from 1958 to 1971, death occurred in 31% and improvement in 52% of 726 patients who did not have thymectomy, death in 14% and improvement in 68% of 744 patients who had a nonthymomatous thymus removed (p < 0.001), and death in 43% and improvement in 31% of 169 patients who had a thymoma removed.1°-15 During the past 20 years, there has been a reduction in mortality and morbidity of the disease,lG attributed to improvement in management, but specific factors have been difficult to isolate. The present study describes the course of the disease during the past 40 years and factors affecting its’ outcome.

A hypothetical explanation for periodic alternating nystagmus: instability in the optokinetic-vestibular system.

Abstract: Spontaneous nystagmus that periodically reverses direction has been reported in a variety of circumstances: as a variant of congenital nystagmus; in association with acquired neurological lesions, especially in the region of the craniocervical junction; and as a transient manifestation of anticonvulsant intoxication.'-6 Periods of oscillation ranging from a few seconds to minutes have been r e p ~ r t e d . ~ . ~ Sometimes this nystagmus is present only in darkness.' It has been reported in blind patients with no other evidence of neurological disease? Within the subjects of these reports exists a group of patients who show an indefatigable nystagmus, in light or darkness, which regularly reverses direction with a period often of 3-4 minutes, and in whom acquired disease of the nervous system seems most likely to be the cause.' It is this form of periodic alternating nystagmus (PAN) that we address here, using clinical studies and control-systems analysis to develop a hypothetical explanation, or model, of the phenomenon. We propose that PAN arises from (1) an instability in the brain-stem neural networks that generate slow phases of vestibular and optokinetic nystagmus, (2) the action of an adaptive network that normally acts to null prolonged, inappropriate nystagmus, and (3) an inability to use retinal-error-velocity information.

Observations of the natural history of myasthenia gravis and the effect of thymectomy

Abstract: The natural course of myasthenia gravis (MG) is rarely observed nowadays. After the diagnosis, nearly all patients receive anticholinesterases. Most young patients and nearly all patients with thymomas are subjected to thymectomy and older patients are primarily treated with prednisone and or azathioprine if anticholinesterases are not of “enough benefit.” The boundaries between young and old are unclear, as is the criterion of enough benefit. Some clinicians advocate thymectomy in older age groups even if no thymoma can be demonstrated. As Rowlandl has pointed out, the treatment of myasthenia is full of controversies, which are unlikely to be resolved unless controlled trials are carried out. The following report concerns a large group of personally observed patients, about half of whom have been treated with anticholinesterases alone. Part of them are included in previous reports?,

Hormone-sensitive ion transport systems in erythrocytes as models for epithelial ion pathways.

Abstract: 216. Sci. USA. 78: 1057-1061. 1980. Nature 284: 281-283. Palfrey & Greengard : Hormone-Sensitive Transport 307

Morphological similarities between the dog kidney cell line mdck and the mammalian cortical collecting tubule

Abstract: In the last five years, the cell line MDCK has received considerable attention because it has retained many morphologic, physiologic, and biochemical properties exhibited by transporting epithelia in vivo.l-” MDCK cells were derived by Madin and Darby in 1958 from the normal, adult male Cocker Spaniel kidney. Although several cultured kidney cell lines have attracted the attention of renal physiologists in the last few years,]? many investigators remain skeptical of this approach to kidney physiology for two reasons. First, it is said that the nephron site of origin of any epithelial cell line is unknown, so direct physiological comparisons between cultured cells and intact kidney tubules cannot be made. Secondly, it is widely believed that once put into culture the functional properties of any differentiated cell are not stable and are lost due to an illdefined process called “dedifferentiation”. In this paper, I present morphologic evidence that low-passage MDCK cultures contain two cell types that are identical by an array of interconnected criteria to the principal and intercalated cells of the mammalian cortical collecting tubule. These observations substantiate and extend biochemical results indicating that the MDCK adenyl cyclase is sensitive to vasopressin but not parathyroid hormone,6* l 3 a relationship also found in the collecting t~bu1e . l~

On Self‐Deception

Abstract: T H E P O I N T OF DEPARTURE for this conference is the Clever Hans story. Because the story was written as a scientific treatise, the horse’s trainer, Herr von Osten, appears primarily as a stimulus object. Scientists observed and recorded Herr von Osten’s postural movements and concluded that such movements were signals to the horse to tap his hoof. Although not entirely neglected in the scientific write-up, Herr von Osten’s unshakable belief in the horse’s human-like rationality received only brief notice. Both Stumpfl and Pfungst2 declared that von Osten was not a trickster nor a swindler; rather they settled on a diagnosis of self-deception. Although in its naked form, the term “self-deception” contains a contradiction, it continues to be widely used to denote states of affairs similar to that of Herr von Osten in the Clever Hans story. Herr von Osten held to his anthropomorphic belief in the horse’s rationality in the face of adverse evidence presented by respectable and responsible scientists. Parenthetically, one should note that anthropomorphism is a rather common human belief, and Herr von Osten’s apparent espousal of anthropomorphic doctrine was not taken by his contemporaries as a sign of senile dementia (nor should it have been). My aim in this paper is to illuminate the conduct frequently labeled self-deception. Von Osten is an appropriate example. To show that the phenomenon is not unique, I will identify several additional examples taken from experimental and field studies. These examples, taken together, serve both as a working definition of self-deception and a framework for a sketch of previous attempts to come to grips with the problem. At the end of my paper, I offer a theoretical statement about self-deception based on the narrative as the root-metaphor for knowing.

Postural imbalance with head extension: improvement by training as a model for ataxia therapy*

Abstract: Head extension may cause a physiological vertigo and postural imbalance separate and distinct from basilar insufficiency. This physiological imbalance mainly is due to a vestibular sensory deficiency when the utricular otoliths are beyond their working range because of the change in head position. Since the intact visual and somatosensory control hope widely compensate for the vestibular deficiency, head-extension vertigo is of particular concern only in certain stimulus situations or diseases in which the stabilizing input from the eyes or joint receptors is reduced. Balance training on foam rubber with head extension and closed eyes improved postural-sway activity up to 50% within five days. A daily short-term training effect and a long-term training effect together form a typical exponential sawtooth curve of postural stability over time. After termination of training, learned balance skill exponentially returns to the pretraining values within weeks. The percentage of improvement through training depends on the amount of initial instability. Clinicians should treat ataxia by exposing patients to stimulus situations producing increasing body instability in order to activate sensorimotor rearrangement.

Effect of immunosuppressive drugs (azathioprine)

Abstract: For more than 18 years, we have been treating myasthenic patients with cytostatic drugs. We began with 6-mercaptopurin, actinomycin and ametopterin but we were forced to discontinue routine usage when serious side effects became evident. For the last 1 1 years, we have been using azathioprine at a dosage of 150-200 mg daily and have published our experiences with the drug at various times, mainly in German journals.l, * In 1978 we were able to report our results with azathioprine at the Plasmapheresis Conference in San Francisco; 5 , since then, many myasthenia clinics have accepted azathioprine usage; however, mostly in connection with plasmaphere~is.~-T Little new data have been uncovered during the last years concerning azathioprine treatment. First impressions about cytostatic drugs in myasthenia were published originally by Mertens in 1969; the experiences of other European authors O-I2 and our own multicenter-study results in 1976 2, have been mainly affirmed.

Second‐language acquisition from a functionalist perspective: pragmatic, semantic, and perceptual strategies*

Abstract: In her 1977 keynote address to the Stanford Child Language Forum, Susan Ervin-Tripp offered some reflections on all the research that has accumulated in the last decade on semantics, pragmatics, discourse structure, and so~iolinguistics.~~ As a pioneer in all of these areas, Dr. ErvinTripp offered us the following reminder: we never did solve the problem of how grammar is acquired. Although studies of meaning and function are valuable in their own right, they need to be taken one step further, to an understanding of how semantic and pragmatic factors influence the discovery and use of grammatical forms. One way to meet this goal is through the construction of a performance grammar-a unified theory of the pragmatic, semantic, and perceptual processing strategies that adults and children use to comprehend and produce sentences, inside and outside of a discourse context. Such a grammar would focus not only on the “possession” of a rule by a language or by an individual, but on the way grammatical information is handled in real time. In monolinguals, we have evidence suggesting that grammatical processing takes place with incredible speed, integrating many different levels of discourse simultaneously. For example, linguistic research on the relationship between discourse and grammar has shown that many different communicative functions are conveyed with every single grammatical d e c i s i ~ n . ’ ~ ~ ~ ~ Psycholinguistic research has shown that listeners integrate information from every level of discourse (phonology, lexical relations, word order, and prior discourse context) rapidly and in parallel, from the very first word presented in on-line sentence-comprehension experiment^.^^ Given these constraints, the accomplishments of an adult bilingual seem nothing short of miraculous. First of all, the bilingual is in the unique position of mapping the same underlying meanings and intentions onto two

Eye-muscle geometry and compensatory eye movements in lateral-eyed and frontal-eyed animals.

Abstract: Our question here has a long history and arises from the following type of observation: when a rabbit is oscillated about the naso-occipital (roll) axis, the compensatory eye movements are vertical, but when a human is oscillated about the same axis, the compensatory eye movements are torsional. What is the basis of such differences in compensatory eye movements among vertebrates with differing interocular angles? While the existence of these appropriate behavioral differences is commonly known, the origin of these differences is, currently, commonly unknown, as a search of the contemporary literature a t t e ~ t ~ . ~ * ’ ~ , ~ ~ * ~ ~ . ~ ~ This is regrettable; subsequent to arriving at our answer to the question posed above, we found that Ohm, in a rarely referenced 1919 paper, had arrived at the same answer.35 The results reported here confirm and extend Ohm’s lucid and accurate study, which had been ‘‘lost’’ to modern investigators of the vestibuloocular reflexes. To answer the question of what underlies the differences in compensatory eye movements among animals with different interocular angles, one must consider the physiological relations between the vestibular labyrinth and the extraocular muscles and also the peripheral anatomy of the labyrinth and of the extraocular muscles. Hogyes was the first to delve into these matters; he deduced a specific set of primary relations and pathways between the labyrinth of one side and the ipsilateral and contralateral eye muscles.22 Indeed, he came quite close to determining the actual arrangement, clarified much later by Szenthgothai.44-46 In the course of his studies, Hogyes also recognized the different requirements for appropriate compensatory eye movements in lateraland frontal-eyed animals, but he did not clearly resolve the question of how the requirements are met. (Hogyes’ achievements in vestibular research were fully appreciated only after his main publication, originally published in Hungarian in the 188Os, appeared in German translation in 1912.jZ3 BBr5ny accurately observed the eye movements elicited in rabbit by natural vestibular ~ t imul i .~ However, he claimed that the actions of rabbit and human extraocular muscles were identical, and thus his description of the relations of individual vertical semicircular canals to specific eye muscles was erroneous. Why BBriny believed the actions of rabbit and human extraocular muscles to be identical is mysterious because the anatomical information about the periphery necessary to arrive at the contrary conclusion was available from his associate Rothfeld and also from W e s ~ e l y ? ~ . ~ ~ BBrAny’s viewpoint was contradicted by Ohm, who demonstrated anatomically

Comparison of the results of transsternal imple, transcervical simple, and extended thymectomy

Abstract: Recently, the effectiveness of thymectomy for myasthenia gravis (MG) has been well appreciated.2. ti, * At the start of use of thymectomies for MG, it was performed by median sternotomy, and this approach became wide-spread in most clinics of thoracic surgery. Thereafter, since the latter half of the 1960s a new approach was advocated 12, 22 in some institutes, mainly, Mt. Sinai Hospital and the Massachusetts General Hospital. This approach was the one performed by a collar incision up above the sternal notch, and the advocates of this method asserted merits of lower morbidity, and lesser surgical stress. In 1975, weI6 remarked upon the high incidence of extracapsular thymic tissue in the fat at the anterior mediastinum, and thought that the en bloc resection of fat tissue with the thymus gland was necessary to remove the thymic tissue as much as possible. Thus, in the First Surgical Department of Osaka University, three different procedures have been performed for nonthymomatous MG, i.e., 1 ) transsternal simple thymectomy from 1962 to 1970, 2) transcervical simple thymectomy from 1971 to March 1973, and 3) extended thymectomy from April 1973 up t o date. Herewith, we present a survey comparing the results using those procedures.

Directional plasticity of the vestibulo‐ocular reflex in the cat*

Abstract: As an individual moves, the eyeballs must rotate at the same speed, but in the opposite direction, as head rotation for images to be stabilized on each retina. Such movemenis are made automatically by the vestibulo-ocular reflex (VOR). Its effectiveness may be measured by the gain of the reflex: eye velocity divided by head velocity. Normally the gain is close to 1.0, so that images do not slip on the retina when the head moves. The VOR must have some type of maintenance system that monitors its gain (by vision] and corrects it when it falls out of calibration. In a young animal this system is responsible for maintaining calibration as the organism grows. Growth of the skull-which alters the angular relations between the orbits' and the semicircular canals-and changes in the mechanical parameters of the eyeball and eye muscles must be compensated if the system is to continue working. In the mature animal the task becomes one of preserving the gain of the vestibulo-ocular system in spite of the continual disturbing effects of cell death during aging. The enormous anatomical variations between members of a species suggest that genetic programming alone cannot maintain the VOR.' The mechanism responsible for optimizing the VOR has been described as a motor-learning system capable of making parametric changes by modifying synaptic ~ t r e n g t h s . ~ , ~ The ability of this repair mechanism to change the VOR has been demonstrated by adapting animals and humans to optical devices that change the relationship between the apparent motion of visual objects and head rotation. Melvill Jones and his colleagues have studied the effect of chronic vision through Dove prism^.^-^ These prisms reverse the seen world from left to right and make it appear to move in the same direction as the head when the latter moves. After an adaptation period, the gain was found to be reduced. Miles and his colleagues found that a telescope lens system that magnifies the visual world can be used to raise the VOR gain.',' In each of these and similar situations, the gain always rose or fell in such a way as to lessen or eliminate retinal image slip during head movements. This form of adaptive motor plasticity now has been well established in a variety of species. Not only must the speed of a compensatory eye movement be correct, its direction must be just opposite to that of the head to keep the line of sight stationary in the visual environment. We can think of vestibular eye compensatory movements as occurring in a plane parallel to the plane of head rotation. The wrong orientation of the plane of the eye movement would cause images to slip on the retina. If the planes of action of pairs of extraocular muscles were exactly parallel to those of synergistic pairs of semicircular canals, the arrangement

Fluorophores in polar media: spectral effects of the langevin distribution of electrostatic interactions

Abstract: The models employed for the analysis of the dependence of the fluorescence spectrum upon the dielectric properties of the solvent'-5 consider the latter as a continuum which causes changes in the electronic energy levels through the interaction of the fluorophore with the reaction field that it induces upon its dielectric environment. In models of this kind, the change in energy of the excited state with respect to an unperturbed state is given by an expression of the form:

Role of platelets in tumor cell metastases

Abstract: Platelets may have a role in the development of animal tumor metastases. Ultrastructural studies in vivo have shown arrested tumor emboli surrounded by platelets. Several tumor cell lines induce thrombocytopenia in vivo. Certain tumor cells aggregate platelets in vitro. Correlations exist between the ability of some tumor cells to aggregate platelets in vitro and their metastatic potential in vivo. Antiplatelet agents have impaired or altered the spread of certain tumor metastases. It is suggested that platelets have a role in the sequestration, adherence, and penetration of tumor cells through the blood vessel endothelial cell barrier, thus preventing their rapid clearance from the circulation and allowing extravascular formation of nests of cells. Antiplatelet agents, particularly prostaglandins, may prove useful in preventing experimental animal metastases when administered before the inoculation of tumor cells. Their potential in human malignancy, where the patient presents with an established tumor, remains to be established.

Aspects of the natural history of myasthenia gravis: crisis and death

Abstract: In an analysis of myasthenia crises during the past 20 years, the incidence of crisis remained fairly constant at 12-16%, but the fatality rate of crises declined from 42% to 6%, and the overall mortality of myasthenia declined from 12% to 3.3%. Most crisis episodes were caused by aspiration pneumonia or occurred in patients with severe dysphagia, who were at risk of aspiration. Cholinergic drug therapy clearly was not useful during crisis, and should probably be discontinued while the patient is on a respirator. Fifteen of 28 patients with thymectomy had 21 episodes of crisis months or years after surgery. Ultimately, 42% of crisis survivors achieved a state of improved myasthenia or remission after one or more crises.

From vitamin a to retinoids in experimental and clinical oncology: achievements, failures, and outlook

Abstract: The problems of prevention and therapy of cancer are far from being solved. Regarding therapy, it is beyond doubt that surgery and radiotherapy cure a certain percentage of cancer patients. Cancer chemotherapy with the conventional cytostatic agents is a further means by which oncologists can help patients. Immunotherapy, including the newest methods of treatment with thymosin, and particularly interferon, may bring further progress. In the field of prevention of cancer mortality, early detection of precancerous and cancerous lesions and elimination of carcinogenic agents are up to now the most successful means. The continuing high mortality of cancer, even in the most developed countries, underlines the still unsatisfactory medical methods at our disposal. New approaches to the cancer problem are badly needed. It is the purpose of this conference to acquaint us with the basic research work done in the field of retinoids. The retinoids (vitamin A and analogs) represent a fairly new development in the cancer field, offering a new approach differing markedly in their more physiological mode of action from the hitherto existing approaches in prevention and therapy of cancer.

Monoclonal autoantibodies to acetylcholine receptors: evidence for a dominant idiorpe and requirement of complement for pathogenicity*

Abstract: An antigenic determinant of mammalian muscle acetylcholine receptors (AChR) remote from the ACh-binding site and exposed extracellularly at the neuromuscular junction has been defined by monoclonal autoantibodies (McAb's). The determinant is a dominant antigen in the rat's autoimmune response to AChR. It was defined by four IgG McAb's (from two individual donor rats) which shared a common idiotype (Id) complementary to the AChR determinant. These four McAb's bound to AChR in vivo and induced experimental autoimmune myasthenia gravis (EAMG). They also bound to nonjunctional AChR on living myotubes in culture at 37 degrees and caused loss of alpha-bungarotoxin (alpha-BT) binding sites. The McAb's did not inhibit binding of alpha-BT to solubilized AChR or to nonjunctional AChR in membranes of muscle cells held at 4 degrees C. Impairment of neuromuscular transmission by the McAb's required activation of complement via the classical pathway. In the absence of C3 leads to C9, or in isolated deficiency of C4, binding of McAb's to at least 62% of AChR for 72 hours in vivo did not alter miniature endplate potentials (MEPPs) or EPPs or reduce the muscle's content of AChR. The common Id was detectable in sera of rats immunized with AChR of either Torpedo, eel or syngeneic muscle. Anti-Id antibodies raised against 3 of the McAb's inhibited in vitro binding of each of the 4 McAb's to AChR; absorption of one anti-Id by a second McAb removed inhibitory activity for all McAb's. However, when rats with high titers of anti-Id were challenged by immunization with torpedo AChR, the severity of EAMG was undiminished despite a continuing excess of anti-Id antibodies. Success of the anti-Id approach to therapy of myasthenia gravis may require definition of several antigenic determinants of human muscle AChR with which patients' auto-antibodies interact in vivo.