RESUMEN
Apraxia following left hemisphere stroke disrupts pantomimed tool use (PTU), a task that requires the integrity of a number of cognitive and motor processes. Although previous studies have identified that apraxics have deficits in (1) the integrity of/access to stored tool-use gesture representations, (2) deficits in intrinsic (body-based) coordinate control, and (3) abnormal reliance on visual feedback, no study to date has simultaneously tested the relative contribution of these three deficits to poor PTU performance. In this study we assessed 38 chronic left hemisphere stroke survivors on tests of PTU and the 3 component processes. We then attempted to predict PTU with the component scores using hierarchical regression to control for overall stroke severity and the possibility of correlated component scores. Results showed that over half of the variability in PTU was predictable, with the strongest independent predictor being a test of intrinsic coordinate control without visual feedback. A test of the integrity of/access to stored representations also predicted PTU. These results confirm and extend previous claims that conceptual- and production-related factors affect PTU, even after considering that deficits in both factors are commonly observed to varying degrees in apraxic patients.
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Apraxias/complicaciones , Conducta Imitativa/fisiología , Trastornos de la Destreza Motora/etiología , Desempeño Psicomotor/fisiología , Reconocimiento en Psicología/fisiología , Anciano , Femenino , Lateralidad Funcional , Humanos , Masculino , Persona de Mediana Edad , Valor Predictivo de las Pruebas , Radiografía PanorámicaRESUMEN
The protozoan parasite Leishmania mexicana causes chronic cutaneous disease in humans and most mouse strains. We previously showed that STAT4-deficient mice, but not IL-12p40-deficient mice, have more parasites and progressively growing lesions unlike those of wild-type mice, the lesions and parasite burdens of which plateau by 10-12 weeks post-infection. This demonstrates a STAT4-dependent, IL-12/IL-23-independent pathway of parasite control. Type I IFNs are important in viral and other infections and can activate STAT4. We found that IFN-alpha/betaR-deficient mice have a nonpersistent, early IFN-gamma defect, and a persistent, early IL-10 defect, without changes in serum IL-12 or LN-derived nitric oxide. We found less IL-10 per cell in CD25+CD4+ T cells and possibly fewer IL-10-producing cells in the draining LN of IFN-alpha/betaR-deficient vs. wild-type mice. IFN-alpha/betaR-deficient mice have chronic, nonprogressive disease, like wild-type mice, suggesting that IL-10 and IFN-gamma defects may balance each other. Our data indicate that although type I IFNs help promote early Th1 responses, they are not the missing activators of STAT4 responsible for partial control of L. mexicana. Also, the lack of lesion resolution in IFN-alpha/betaR-deficient mice despite lower IL-10 levels indicates that other pathways independent of T cell IL-10 help prevent an IL-12-driven clearance of parasites.
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Interferón Tipo I/inmunología , Interferón gamma/biosíntesis , Interleucina-10/biosíntesis , Leishmania mexicana/inmunología , Leishmaniasis Cutánea/inmunología , Animales , Linfocitos T CD4-Positivos/química , Linfocitos T CD4-Positivos/inmunología , Interleucina-12/sangre , Subunidad alfa del Receptor de Interleucina-2/análisis , Ganglios Linfáticos/inmunología , Ratones , Ratones Noqueados , Receptor de Interferón alfa y beta/deficienciaRESUMEN
Hemispatial neglect has been conceptualized as having dissociable and potentially clinically relevant subtypes. However, the question of whether patient performance on neglect subtype measures is consistent over time remains largely unanswered. We examined changes in performance over time on measures of motor, perceptual, and personal neglect in 21 patients with neglect from acute right hemisphere stroke. Patients were assessed on three occasions, separated by at least one week, using a lateralized target test, lateralized response test, and modified fluff test. Across three testing timepoints, 18 (85.7%) patients changed subtype performance patterns at least once. In 13 (61.9%) of these patients, inconsistency between timepoints was not adequately accounted for by recovery. On initial testing, seven, patients (33.3%) demonstrated more than one neglect subtype symptom; by the third testing timepoint none of the patients demonstrated multiple symptoms. In the setting of acute stroke, performance on three measures of neglect symptoms is inconsistent across time. However, the distribution of neglect subtype symptoms appears to become more discrete over time. These findings complicate our understanding of the pathophysiology and potential prognostic value of neglect subtypes, and suggest that treatment decisions based on subtype performance assessed at a single timepoint, may be of limited utility.
Asunto(s)
Lateralidad Funcional/fisiología , Trastornos de la Percepción/clasificación , Trastornos de la Percepción/etiología , Desempeño Psicomotor/fisiología , Accidente Cerebrovascular/complicaciones , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Masculino , Persona de Mediana Edad , Pruebas Neuropsicológicas , Accidente Cerebrovascular/patologíaRESUMEN
OBJECTIVES: The evolutionary pattern of spontaneous recovery from acute neglect was studied by assessing cognitive deficits and motor impairments. Detailed lesion reconstruction was also performed to correlate the presence of and recovery from neglect to neural substrates. METHODS: A consecutive series of right brain-damaged (RBD) patients with and without neglect underwent weekly tests in the acute phase of the illness. The battery assessed neglect deficits, neglect-related deficits, and motor impairment. Age-matched normal subjects were also investigated to ascertain the presence of non lateralised attentional deficits. Some neglect patients were also available for later investigation during the chronic phase of their illness. RESULTS: Partial recovery of neglect deficits was observed at the end of the acute period and during the chronic phase. Spatial attention was impaired in acute neglect patients, while non spatial attentional deficits were present in RBD patients with and without acute neglect. A strong association was found between acute neglect and fronto-parietal lesions. Similar lesions were associated with neglect persistence. In the chronic stage, neglect recovery was paralleled by improved motor control of the contralesional upper limb, thus emphasising that neglect is a negative prognostic factor in motor functional recovery. CONCLUSIONS: These findings show that spatial attention deficits partially improve during the acute phase of the disease in less than half the patients investigated. There was an improvement in left visuospatial neglect at a later, chronic stage of the disease, but this recovery was not complete.
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Lesiones Encefálicas/complicaciones , Lesiones Encefálicas/psicología , Trastornos de la Percepción/etiología , Trastornos de la Percepción/patología , Percepción Espacial , Accidente Cerebrovascular/complicaciones , Accidente Cerebrovascular/psicología , Enfermedad Aguda , Anciano , Anciano de 80 o más Años , Atención , Lesiones Encefálicas/patología , Estudios de Casos y Controles , Femenino , Lateralidad Funcional , Humanos , Estudios Longitudinales , Masculino , Persona de Mediana Edad , Trastornos de la Destreza Motora/etiología , Trastornos de la Destreza Motora/patología , Examen Neurológico , Pronóstico , Remisión EspontáneaRESUMEN
OBJECTIVE: To assess the relative frequency of occurrence of motor, perceptual, peripersonal, and personal neglect subtypes, the association of neglect and other related deficits (e.g., deficient nonlateralized attention, anosognosia), and the neuroanatomic substrates of neglect in patients with right hemisphere stroke in rehabilitation settings. METHODS: The authors assessed 166 rehabilitation inpatients and outpatients with right hemisphere stroke with measures of neglect and neglect subtypes, attention, motor and sensory function, functional disability, and family burden. Detailed lesion analyses were also performed. RESULTS: Neglect was present in 48% of right hemisphere stroke patients. Patients with neglect had more motor impairment, sensory dysfunction, visual extinction, basic (nonlateralized) attention deficit, and anosognosia than did patients without neglect. Personal neglect occurred in 1% and peripersonal neglect in 27%, motor neglect in 17%, and perceptual neglect in 21%. Neglect severity predicted scores on the Functional Independence Measure and Family Burden Questionnaire more accurately than did number of lesioned regions. CONCLUSIONS: The neglect syndrome per se, rather than overall stroke severity, predicts poor outcome in right hemisphere stroke. Dissociations between tasks assessing neglect subtypes support the existence of these subtypes. Finally, neglect results from lesions at various loci within a distributed system mediating several aspects of attention and spatiomotor performance.
Asunto(s)
Trastornos de la Percepción/etiología , Accidente Cerebrovascular/complicaciones , Actividades Cotidianas , Adulto , Anciano , Anciano de 80 o más Años , Encéfalo/patología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Trastornos de la Percepción/clasificación , Rehabilitación de Accidente CerebrovascularRESUMEN
Sarcoidosis is a systemic disease that may affect the musculoskeletal system. An association between carpal tunnel syndrome (CTS) and sarcoidosis has not been demonstrated. Consecutive patients from the sarcoidosis clinic at our institution were questioned about history and symptoms of carpal tunnel syndrome: hand numbness and nocturnal paresthesias with relief of symptoms by shaking of the hands (flick sign). A physical exam was performed to evaluate for Tinel's and Phalen's signs. A comparison of the presence of arthritis, prednisone treatment, spirometry, and number of organs involved with sarcoidosis was made in patients with a history or clinical findings of CTS versus those without. Eighty-nine patients were evaluated. Thirty-five patients (39%) had nocturnal paresthesias with a positive flick sign. Fourteen patients (16%) had physical findings of CTS. A history of CTS was present in 14 (16%) of the patients, four of which were documented by EMG. There was no significant difference between the frequency of prednisone treatment in patients with or without CTS history, nocturnal paresthesias, or Phalen's sign. There were significantly fewer patients with a positive Tinel's sign who were receiving prednisone. There was a trend toward an increased frequency of wrist arthritis in patients with a history or clinical findings of CTS. There was no significant difference in disease severity, assessed by spirometry or organ involvement, when comparing sarcoidosis patients with or without a history or clinical findings of CTS. Thirty-nine (44%) had symptoms and/or signs of CTS. Even when we adjusted our sarcoidosis population for other factors associated with CTS, the prevalence of symptoms and signs of CTS was much higher in our patient population than in studies of the general population. Our findings suggest that CTS is common in sarcoidosis.
Asunto(s)
Síndrome del Túnel Carpiano/complicaciones , Sarcoidosis/complicaciones , Adulto , Síndrome del Túnel Carpiano/fisiopatología , Femenino , Humanos , Hipoestesia/etiología , Masculino , Nervio Mediano/fisiopatología , Persona de Mediana Edad , Parestesia/etiología , Sarcoidosis/fisiopatologíaRESUMEN
On several accounts of "selection for action", acting on a target object among distractors requires that irrelevant inputs and responses to these inputs are inhibited, and relevant inputs and responses selected. In unilateral neglect associated with right-hemisphere lesions, selection processes may be biased toward stimuli on the right, as right is usually defined by head and body hemispace. In normal subjects performing reaching-to-target tasks, selection may be "hand-centered" (Tipper S., Lortie C., Baylis G.C., Journal of Experimental Psychology: Human Perception and Performance 18(4) (1992) 891-905) in that distractor stimuli close to the hand compete strongly with the target for the control of action, causing greater interference than distractors far from the hand. We reasoned that in the context of a reaching task, a left-right asymmetry in unilateral neglect may be defined with respect to the position of the hand. This predicts that target and distractor stimuli to the left of hand (i.e. requiring leftward movements for contact) should compete less strongly for the control of action than stimuli to the right of the hand. We tested this hypothesis by asking eight patients with unilateral neglect (and 12 healthy controls) to reach to central targets presented alone and with surrounding distractors from left or right start positions. Patients with neglect, but not controls, were slower to initiate reaches from right start as compared to left start positions. In this context, patients showed interference from distractors to the right of the hand and facilitation from distractors to the left of the hand. This indicates that a left-right selection asymmetry in neglect may be hand-centered. These data can be explained on a model of damage to the portion of a distributed neuronal population coding movement vectors to stimuli in relatively leftward locations.
Asunto(s)
Destreza Motora/fisiología , Trastornos de la Percepción/fisiopatología , Adulto , Anciano , Anciano de 80 o más Años , Atención , Estudios de Casos y Controles , Femenino , Lóbulo Frontal/fisiología , Lateralidad Funcional , Mano , Humanos , Masculino , Persona de Mediana Edad , Lóbulo Parietal/fisiología , Percepción VisualRESUMEN
Previous accounts of autotopagnosia (e.g., Ogden, 1985; Pick, 1908; Semenza, 1988) propose that the disorder is attributable to deficits in "mental images," visual body schema, or semantic representations. A recent account (Sirigu, Grafman, Bressler, & Sunderland, 1991b) posits deficits in visual structural descriptions of the human body and its parts, in the context of spared semantic and proprioceptivespatio-motor body representations, but provides no evidence bearing on the nature or format of the putatively damaged representation. We report data from a man with autotopagnosia consequent to lefthemisphere brain damage which bear directly on the nature of the representation impaired in the disorder. The subject, GL, is unable to localise body parts on himself or others, whether cued by verbal or visual input. In contrast, he uses body parts precisely in reaching and grasping tasks, correctly matches items of clothing to body parts, and localises the parts of animals and man-made objects without error. We also demonstrate that GL is unable to match pictured or real human body parts across shifts in orientation or changes in visual appearance, but can perform analogous matching tasks with animal body parts and man-made object parts. The data extend the account of Sirigu et al. (1991b) in suggesting that human body part localisation depends upon structural descriptions of human (but not animal) bodies that enable viewpoint-independent body part recognition and participate in the calculation of equivalence between the body parts of self and others across transformations in orientation.
RESUMEN
We report a patient with autotopagnosia (JD) who was unable to code the position of body parts relative to each other and who failed to update the position of body parts after passive movements. JD's performance in Studies 1-4 suggest that her ability to code the dynamic location of body parts with respect to each other ("intrinsic egocentric" spatial coding) was impaired, and that she employed a compensatory strategy by means of which the location of body parts was computed with respect to objects in the environment ("extrinsic egocentric" spatial coding). Studies 5-8 suggest that JD's ability to update hand position information was impaired after passive relative to active movements of her arm. For example, she was impaired in reaching to a target after passive but not active movements of her hand. Taken together, these findings extend previously reported functions of extrinsic egocentric coding to the localisation of body parts and demonstrate a possible dissociation between body part localisation dependent upon proprioceptive and efference copy information.
RESUMEN
Although ideomotor apraxia (IM) has been a topic of investigation since the early 20th century, progress in studying the disorder has been hindered by important (and sometimes unarticulated) differences in the underlying theoretical models of various investigative groups. As a result, it is difficult to draw conclusions about the expected performance of IM patients on various tests of praxis (e.g. pantomime, single object use, gesture imitation, and naturalistic action); the relationship of IM to ideational apraxia (IA); the degree to which specific error types are diagnostic of one or the other disorder; the relationship of semantic knowledge to gesture representations; and the role of spatiomotor systems external to the stored gesture representation system. Here an updated model of IM is presented, informed by recent physiological and functional neuroimaging literature, as a step towards resolving some of these concerns. The model is intended to lay the groundwork for future investigations of specific performance patterns in different subtypes of IM.
Asunto(s)
Apraxia Ideomotora/diagnóstico , Apraxia Ideomotora/fisiopatología , Apraxia Ideomotora/psicología , Mapeo Encefálico , Cuerpo Calloso/fisiopatología , Dominancia Cerebral/fisiología , Humanos , Red Nerviosa/fisiopatología , Examen Neurológico , Pruebas Neuropsicológicas , Lóbulo Parietal/fisiopatologíaRESUMEN
When a parent dies from cancer, each surviving child faces unique grief and loss issues. Nurses play a major role in caring for the child whose parent has died or is expected to die from cancer. The nurse's responsibility begins with assessing the child's coping strategies, family environment, and community resources. All three components affect the child's ability to progress through the grief process. Early assessment may identify problematic grief reactions and facilitate a positive outcome. Interventions that facilitate the grieving process include involving the child and family in grief groups, providing individual counseling, providing adequate information, assisting the child in the creation of memory keepsakes, and encouraging normalcy within the family.
Asunto(s)
Adaptación Psicológica , Actitud Frente a la Muerte , Pesar , Neoplasias/psicología , Padres/psicología , Psicología Infantil , Adolescente , Factores de Edad , Niño , Preescolar , Consejo , Mecanismos de Defensa , Educación en Salud , Humanos , Lactante , Rol de la Enfermera , Evaluación en Enfermería , Enfermería Oncológica/métodos , Derivación y Consulta , Grupos de Autoayuda , Apoyo SocialRESUMEN
PURPOSE: The purpose of this study is to assess the patterns of geographic variation of the following pulmonary diseases: tuberculosis (TB), lung cancer (LC), berylliosis (BR), sarcoidosis (SR), and asthma (AS).METHODS: Hospitalization rates for the five diseases were calculated for the 46 South Carolina (SC) counties from 1985-1995. Variation in rates was assessed by county, region, and urban/rural status using analysis of variance. SC was divided into 4 regions, according to proximity to the coastline and to physiographic characteristics. Region 1 comprised counties in the western-most part of the state, and region 4 comprised the counties closest to the coastline. SC was also divided into 5 population density settings: extreme rural (<15,000), rural (15,000-30,000), middle-size (30,000-50,000), middle-urban (50,000-100,000) and urban (>100,000). Statistical analyses were performed with SAS Version 8.RESULTS:Table 1The rates of SR, TB, and BR were significantly higher in the coastal region. In contrast, no coastal pattern was detected by population density.CONCLUSIONS: The consistent association of SR, TB, and BR with geographical region, as opposed to the inconsistent association with population density, suggests that environmental factors may be involved in these pulmonary diseases. These results demonstrate the need for further analysis of the relationship between socio-economic, behavioral, and environmental factors and the development of these diseases.
RESUMEN
On an influential model of limb praxis, ideomotor apraxia results from damage to stored gesture representations or disconnection of representations from sensory input or motor output (Heilman & Gonzalez Rothi, 1993; Gonzalez Rothi et al., 1991). We report data from a patient with progressive ideomotor limb apraxia which cannot be readily accommodated by this model. The patient, BG, is profoundly impaired in gesturing to command, to sight of object, and to imitation, but gestures nearly normally with tool in hand and recognizes gestures relatively well. In addition, performance is profoundly impaired on imitation of meaningless gestures and on tasks requiring spatiomotor transformations of body-position information. We provide evidence that BG's apraxia is largely attributable to impairments external to the stored gesture system in procedures coding the dynamic positions of the body parts of self and others; that is, the body schema. We propose a model of a dynamic, interactive praxis system subserved by posterior parietal cortex in which stored representational elements, when present, provide "top-down" support to spatiomotor procedures computed on-line. In addition to accounting for BG's performance, this model accommodates a common pattern of ideomotor apraxia more readily than competing accounts.
Asunto(s)
Apraxia Ideomotora/diagnóstico , Imagen Corporal , Anciano , Apraxia Ideomotora/etiología , Atrofia/complicaciones , Atrofia/patología , Progresión de la Enfermedad , Femenino , Lóbulo Frontal/patología , Humanos , Imagen por Resonancia Magnética , Pruebas Neuropsicológicas , Lóbulo Parietal/patología , Índice de Severidad de la Enfermedad , Conducta Espacial/fisiologíaRESUMEN
Leishmania amazonensis induces a nonhealing infection in C3H mice, whereas infection with Leishmania major is self-healing. We found that C3H mice infected with L. amazonensis exhibited decreased IL-12 production, which could account for the susceptibility to this organism. However, exogenous IL-12 administration failed to induce a healing immune response. The failure of L. amazonensis-infected C3H mice to respond to IL-12 was associated with a specific defect in IL-12 receptor beta2 (IL-12Rbeta2) mRNA expression by CD4+ T cells. Furthermore, decreased IL-12Rbeta2 mRNA expression correlated with a decrease in the IL-12-signaling capacity of the lymph node (LN) cells. IL-4 did not contribute to susceptibility or down-regulation of the IL-12Rbeta2 subunit, because IL-4-/- mice remained susceptible to L. amazonensis infection, even after IL-12 administration, and CD4+ cells from infected IL-4-/- mice also had reduced expression of IL-12Rbeta2 mRNA. These results demonstrate that regulation of the IL-12 receptor, independent of IL-4, is a point of control for the immune response to leishmaniasis. In contrast to experimental L. major infections, where host genetics control susceptibility, these studies demonstrate that the lack of IL-12 responsiveness may be dictated by the pathogen, rather than the host.
Asunto(s)
Interleucina-12/antagonistas & inhibidores , Interleucina-12/biosíntesis , Interleucina-4/fisiología , Leishmania mexicana/inmunología , Leishmaniasis Cutánea/inmunología , Animales , Antígenos de Protozoos/inmunología , Linfocitos T CD4-Positivos/inmunología , Linfocitos T CD4-Positivos/metabolismo , Linfocitos T CD4-Positivos/parasitología , Linfocitos T CD4-Positivos/patología , Regulación hacia Abajo/genética , Regulación hacia Abajo/inmunología , Femenino , Predisposición Genética a la Enfermedad , Inyecciones Subcutáneas , Interferón gamma/biosíntesis , Interleucina-12/administración & dosificación , Interleucina-12/fisiología , Interleucina-4/deficiencia , Interleucina-4/genética , Leishmania major/inmunología , Leishmaniasis Cutánea/etiología , Leishmaniasis Cutánea/genética , Leishmaniasis Cutánea/metabolismo , Ganglios Linfáticos/inmunología , Ganglios Linfáticos/parasitología , Ganglios Linfáticos/patología , Activación de Linfocitos , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C3H , Ratones Endogámicos C57BL , Ratones Noqueados , ARN Mensajero/biosíntesis , Receptores de Interleucina/antagonistas & inhibidores , Receptores de Interleucina/biosíntesis , Receptores de Interleucina/deficiencia , Receptores de Interleucina/genética , Receptores de Interleucina-12 , Transducción de Señal/inmunología , Células TH1/efectos de los fármacos , Células TH1/inmunología , Células TH1/metabolismoRESUMEN
Glycosyl phosphatidylinositol (GPI) anchors in the bloodstream form of Trypanosoma brucei are unusual in that their two fatty acids are myristate. The myristates are added in the final stages of GPI biosynthesis in a remodeling reaction. Remodeling occurs first at the sn-2 position of glycerol, involving removal of a longer fatty acid and subsequent attachment of myristate. The second myristate is then incorporated into the sn-1 position, but the mechanism has been unclear due to the unavailability of a reliable cell-free system supporting complete remodeling. Here, we first refined the cell-free system (by removing Mn(2+) ions), thereby allowing efficient production of the dimyristoylated GPI precursor. Using this improved system, we made three new discoveries concerning the pathway for fatty acid remodeling. First, we discovered a monomyristoylated GPI (known as glycolipid theta') as an intermediate involved in remodeling at the sn-1 position. Second, we found an alternative pathway for production of glycolipid theta, the first lyso intermediate in remodeling. The alternative pathway involves an inositol-acylated GPI known as glycolipid lyso-C'. Finally, we found that there is significant breakdown of GPIs during remodeling in the cell-free system, and we speculate that this breakdown has a regulatory role in GPI biosynthesis.
Asunto(s)
Ácidos Grasos/metabolismo , Glicosilfosfatidilinositoles/metabolismo , Ácido Mirístico/metabolismo , Trypanosoma brucei brucei/metabolismo , Animales , Glicosilfosfatidilinositoles/biosíntesis , CinéticaRESUMEN
A leading account of high-level visual recognition proposes that the recognition of faces, objects, and words is mediated by two processing capacities. Words are assumed to require the capacity to represent numerous parts, whereas faces are processed wholistically. and hence require the representation of complex units. Object recognition requires the capacity to represent both numerous and complex parts. As object recognition depends upon the same processing capacities underlying face and word recognition, this account predicts that patients with severe alexia and prosopagnosia should be deficient in tests of object recognition. We report a patient who is unable to recognize words or faces, yet performs relatively well on tests of object recognition. The two-capacity theory cannot accommodate this pattern of performance without additional assumptions.
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Agnosia/psicología , Percepción Visual/fisiología , Cara , Humanos , Pruebas del Lenguaje , Masculino , Persona de Mediana Edad , Pruebas Neuropsicológicas , LecturaRESUMEN
An unselected group of right hemisphere, semi-acute stroke patients (n = 30) was run on a laboratory test of naturalistic action production and was found to commit errors of action at a higher rate than what was previously reported for recovering head injury patients [Schwartz et al., Naturalistic action impairment in closed head injury. Neuropsychology, 1997, 8, 59-72]. There were strong similarities in how these two patient groups responded to variations in task demands and in the pattern of errors they produced. Hemispatial biases were evident in the errors of right hemisphere patients with neglect but not those without neglect; and neglect patients also many errors that were unrelated to the spatial layout. We argue that a non-specific resource limitation--which might translate as reduced arousal or effort--is central to the breakdown of naturalistic action production after brain damage, and right hemisphere patients are especially vulnerable to this resource limitation and its behavioral consequences.
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Trastornos Cerebrovasculares/psicología , Trastornos del Conocimiento/psicología , Desempeño Psicomotor/fisiología , Adulto , Anciano , Femenino , Lateralidad Funcional/fisiología , Traumatismos Cerrados de la Cabeza/psicología , Humanos , Masculino , Persona de Mediana Edad , Pruebas NeuropsicológicasRESUMEN
The authors sought to determine whether errors of action committed by patients with closed head injury (CHI) would conform to predictions derived from frontal lobe theories. In Study 1, 30 CHI patients and 18 normal controls performed routine activities, such as wrapping a present, under conditions of graded complexity. CHI patients committed more errors even on the simplest condition; but, except for a higher proportion of omitted actions, their error profile was very similar to that of controls. Study 2 involved a subset of patients whose performance in Study 1 was within normal limits. When these high functioning patients were asked to perform the routine tasks under still more taxing conditions, they, too, committed errors in excess of the control group. Accounts based on frontal mechanisms have a difficult time explaining the overall pattern of findings. An alternative based on limited-capacity resources is suggested.
Asunto(s)
Traumatismos Cerrados de la Cabeza/psicología , Desempeño Psicomotor/fisiología , Actividades Cotidianas , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Atención/fisiología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Pruebas Neuropsicológicas , Valor Predictivo de las PruebasRESUMEN
It is frequently claimed that ideational apraxia, an impairm ent of the performance of complex actions with objects, is a left-hemisphere syndrome. We assessed the consequences of lefthemisphere damage for naturalistic action performance in two studies. In Study 1, we compared the action errors of left-hemisphere stroke patients (LCVA) to previously reported patients with right-hemisphere stroke (RCVA) and closed head injury (CHI), and found that LCVA were no more vulnerable to errors of action than the other patient groups once differences in severity were controlled. In Study 2, we compared the naturalistic action performance of a patient with severe ideational apraxia and left-hemisphere damage to that of two RCVA patients of equal clinical severity. There was considerable quantitative and qualitative similarity in the errors of the three patients. From these and other findings, we argue that deficits in left-hem isphere systems do not compromise com plex action in a unique or transparent manner. We offer an alternative account based on nonspecific resource limitations that accommodates the data from all patient groups.
RESUMEN
The survival of Trypanosoma cruzi, the causative agent of Chagas' disease, depends vitally on proteins and glycoconjugates that mediate the parasite/host interaction. Since most of these molecules are attached to the membrane by glycosylphosphatidylinositol (GPI), alternative means of chemotherapeutic intervention might emerge from GPI biosynthesis studies. The structure of the major 1G7 antigen GPI has been fully characterized by us (Güther, M. L. S., Cardoso de Almeida, M. L., Yoshida, N., and Ferguson, M. A. J.(1992) J. Biol. Chem. 267, 6820-6828; Heise, N., Cardoso de Almeida, M. L., and Ferguson, M. A. J.(1995) Mol. Biochem. Parasitol. 70, 71-84), and based on its properties we now report the complete precursor glycolipids predicted to be transferred to the nascent protein. Migrating closely to Trypanosoma brucei glycolipid A on TLC, such species, named glycolipids A-like 1 and A-like 2, were labeled with tritiated palmitic acid, myo-inositol, glucosamine, and mannose, but surprisingly only the less polar glycolipid A-like 1 incorporated ethanolamine. The predicted products following nitrous acid deamination and digestion with phospholipases A2, C, and D confirmed their GPI nature. Evidence that they may represent the anchor transferred to the 1G7 antigen came from the following analyses: (i) alpha-mannosidase treatments indicated that only one mannose was amenable to removal; (ii) their lipid moiety was identified as sn-1-alkyl-2-acylglycerol due to their sensitivity to phospholipase A2 (PLA2), mild base and by direct high performance TLC analysis of the corresponding benzoylated diradylglycerol components; and (iii) both glycolipids incorporated 3H-fatty acid only in the sn-2- and not in the sn-1-alkyl position as previously found in the GPI of the mature 1G7 antigen. Based on the differential [3H]ethanolamine incorporation pattern and the recent report that an aminoethylphosphonic acid (AEP) replaces ethanolamine phosphate (EtNH2-PO4) in the GPI in epimastigote sialoglycoproteins (Previato, J. O., Jones, C., Xavier, M. T., Wait, R., Travassos, L. R., Parodi, A. J., and Mendonça-Previato, L.(1995) J. Biol. Chem. 270, 7241-7250) it is proposed that glycolipid A-like 2 contains AEP and A-like 1 EtNH2-PO4. In the in vitro cell-free system both glycolipids were synthesized simultaneously and do not seem to bear a precursor/product relationship. Among the various components synthesized in vitro a glycolipid C-like corresponding to a form of glycolipid A-like 1 acylated on the inositol was also characterized. Phenylmethylsulfonyl fluoride, an inhibitor known to block the addition of ethanolamine phosphate in T. brucei but not in mammalian cells, also inhibits the synthesis of glycolipids A-like and C-like in T. cruzi, indicating that the putative trypanosome EtNH2-PO4/AEP transferase(s) might represent a potential target for chemotherapy.