The dissociation of color from form and function knowledge.

We report on two brain-damaged subjects who exhibit the uncommon pattern of loss of object color knowledge, but spared color perception and naming. The subject P.C.O., as in previously reported patients, is also impaired in processing other perceptual and functional properties of objects. I.O.C., in contrast, is the first subject on record to have impaired object color knowledge, but spared knowledge of object form, size and function. This pattern of performance is consistent with the view that semantic information about color and other perceptual properties of objects is grounded in modality-specific systems. Lesion analysis suggests that such grounding requires the integrity of the mesial temporal regions of the left hemisphere.

Serial order effects in spelling errors: evidence from two dysgraphic patients.

This study reports data from two dysgraphic patients, TH and PB, whose errors in spelling most often occurred in the final part of words. The probability of making an error increased monotonically towards the end of words. Long words were affected more than short words, and performance was similar across different output modalities (writing, typing and oral spelling). This error performance was found despite the fact that both patients showed normal ability to repeat the same words orally and to access their full spelling in tasks that minimized the involvement of working memory. This pattern of performance locates their deficit to the mechanism that keeps graphemic representations active for further processing, and shows that the functioning of this mechanism is not controlled or "refreshed" by phonological (or articulatory) processes. Although the overall performance pattern is most consistent with a deficit to the graphemic buffer, the strong tendency for errors to occur at the ends of words is unlike many classic "graphemic buffer patients" whose errors predominantly occur at word-medial positions. The contrasting patterns are discussed in terms of different types of impairment to the graphemic buffer.

Deficits in lexical and semantic processing: implications for models of normal language.

The investigation of language processing following brain damage may be used to constrain models of normal language processing. We review the literature on semantic and lexical processing deficits, focusing on issues of representation of semantic knowledge and the mechanisms of lexical access. The results broadly support a componential organization of lexical knowledge-the semantic component is independent of phonological and orthographic form knowledge, and the latter are independent of each other. Furthermore, the results do not support the hypothesis that word meaning is organized into modality-specific subcomponents. We also discuss converging evidence from functional imaging studies in relation to neuropsychological results.

Domain-specific knowledge systems in the brain the animate-inanimate distinction.

We claim that the animate and inanimate conceptual categories represent evolutionarily adapted domain-specific knowledge systems that are subserved by distinct neural mechanisms, thereby allowing for their selective impairment in conditions of brain damage. On this view, (some of) the category-specific deficits that have recently been reported in the cognitive neuropsychological literature - for example, the selective damage or sparing of knowledge about animals - are truly categorical effects. Here, we articulate and defend this thesis against the dominant, reductionist theory of category-specific deficits, which holds that the categorical nature of the deficits is the result of selective damage to noncategorically organized visual or functional semantic subsystems. On the latter view, the sensory/functional dimension provides the fundamental organizing principle of the semantic system. Since, according to the latter theory, sensory and functional properties are differentially important in determining the meaning of the members of different semantic categories, selective damage to the visual or the functional semantic subsystem will result in a category-like deficit. A review of the literature and the results of a new case of category-specific deficit will show that the domain-specific knowledge framework provides a better account of category-specific deficits than the sensory/functional dichotomy theory.

Remediating production of tense morphology improves verb retrieval in chronic aphasia.

Production of tense markers in C-VIC, a computerized visual communication system, was utilized as a treatment for three patients with severe expressive aphasia. Patients practiced constructing C-VIC tense marked sentences and then producing English equivalents. After training, all patients demonstrated significant improvements in English verb retrieval and production of correct tense morphology. Generalization of morphological rules for past tense production was seen for regular, but not irregular verbs. These results support the LaPointe and Dell (1989) extension of the Garrett (1975, 1992) model specifying a search through so-called verb phrase notion stores as a process mediating transition from functional to positional levels, but also suggest an additional constraint on the output of the verb notion store search.

Generalization from single sentence to multisentence production in severely aphasic patients.

Multisentence production was examined in three nonfluent aphasic patients who had undergone a single sentence production training program using a computerized visual communication system (C-VIC). Patients were required to describe videotaped vignettes in English and using C-VIC. C-VIC allowed for an investigation of production abilities previously impossible to measure in severely aphasic patients, since C-VIC does not require internal generation of appropriate lexical items or phonological and articulatory realization. Results are discussed in the context of language production models in an attempt to determine the breakdown(s) in the production system that result in difficulty in trying to produce multiple sentences.

How semantic is automatic semantic priming?

Priming for semantically related concepts was investigated using a lexical decision task designed to reveal automatic semantic priming. Two experiments provided further evidence that priming in a single presentation lexical decision task (McNamara & Altarriba, 1988) derives from automatic processes. Mediated priming, but no inhibition or backward priming was found in this type of lexical decision task. Experiments 3 and 4 demonstrated that automatic priming was found only for associated word pairs, as determined by word association norms, and not for word pairs that are semantically related but not associated. It is argued that automatic priming in the lexical decision task occurs at a lexical level not at a semantic level.

Effect of intravenous infusion of atriopeptin 3 on immediate renal allograft function.

Thirty-eight recipients of nineteen pairs of cadaveric kidneys were entered into a double-blind randomized study in which one recipient received a 12-hour intravenous infusion of Atriopeptin III (AP-3), a synthetic analogue of atrial natriuretic factor, commencing at release of the vascular clamps, and the other received a placebo infusion. In an initial dose ranging study, successive groups of six kidneys (3 pairs) were randomized to receive each of 0.0125, 0.025, 0.05 micrograms/kg/min AP-3 or placebo. Thereafter 20 kidneys (10 pairs) received 0.1 micrograms/kg/min or placebo. There was no discernable effect of AP-3 on allograft creatinine clearance or sodium excretion either when the highest dose of AP-3 was considered alone or when all doses were considered together. Averaged creatinine clearance over the period 0 to 24 hours after transplantation was 20.1 +/- 14.7 ml/min in patients receiving active treatment and 18.2 +/- 13.7 ml/min in those receiving placebo. Thus, despite the documentation of a protective effect of atrial natriuretic factor in animal models of renal ischemia, it is unlikely that intravenous infusion of AP-3 in this dose range will be of benefit in improving immediate renal allograft graft function.

The temperature dependence of the time course of growth and decay of miniature end-plate currents in carp extraocular muscle following thermal acclimation.

1. The effect of temperature (5-35 degrees C) on the decay and growth phases of miniature end-plate currents (MEPCs) was investigated in extraocular muscle from freshwater carp acclimated to either high (28 degrees C) or low (8 degrees C) temperature. 2. The temperature dependence of the time constant of decay (TD) was found to follow an Arrhenius relationship; the relationship between logTD and reciprocal of absolute temperature (1/K) being linear in both groups. The TD of MEPCs recorded from cold-acclimated carp was not statistically significant from that of the warm group. 3. TD was moderately temperature-dependent. Regression gave a Q10 of 1.78 for the warm-acclimated carp, corresponding to an activation energy, Ea, of 41.15 +/- 2.17 kJ mol-1. For the cold-acclimated carp, the Q10 was 1.79, and Ea was 41.43 +/- 2.46 kJ mol-1. 4. Growth time (TG) was less susceptible than TD to temperature change. The relationship between growth time (taken as the time for MEPCs to rise from 20 to 80% of maximum) and temperature was linear for the cold-acclimated group, with a Q10 of 1.34 and Ea of 20.94 +/- 4.75 kJ mol-1. The data for the warm group, were, in contrast, best fitted by two linear regressions meeting at 15.1 degrees C. At temperatures below 15.1 degrees C Q10 was 3.16 and Ea was 82.20 +/- 15.47 kJ mol-1; above 15 degrees C, Q10 was 1.22 and Ea was 14.15 +/- 12.24 kJ mol-1. 5. The acetylcholinesterase inhibitor neostigmine increased TD by approximately twofold and raised TG to approximately 1.4 times control values. These effects were observed across the temperature range scanned for both groups. 6. The results are discussed with reference to the documented effects of temperature and temperature acclimation on membrane lipids and proteins.

Beta-cluster haplotypes, alpha-gene status, and hematological data from SS, SC, and S-beta-thalassemia patients in southern California.

The beta-gene-cluster haplotype and alpha-gene status were determined for 221 patients with sickle cell anemia, 41 with SC disease, and 21 with S-beta-thalassemia. Among SS patients, eleven beta S haplotypes were found in 21 combinations. Three haplotypes--the Benin (Ben) [---+-], the Central African Republic (CAR) [+---+], and the Senegal (Sen) [+- ]--comprise 61%, 21%, and 10% of the chromosomes, respectively. Cleavage at the Xmn I site 5' to the G gamma gene was observed only when the Senegalese arrangement was present. The linear correlation which exists between the absolute value of the G gamma chains and the Hb F for each haplotype combination suggests a feed-back mechanism which controls the G gamma to A gamma ratio and thus the Hb F level (or vice versa). The A gamma T chain was present with specific haplotypes [++-++] and [++-+-]. Heterozygous or homozygous alpha-thalassemia-2 was present in 36% of the SS patients and was randomly distributed among beta S-gene-cluster haplotypes. The variable levels of hemoglobin, MCV, Hb F, G gamma chains, and Hb A2 are in response to the heterogeneous genetic mix of the beta S-gene-cluster haplotypes and alpha-thalassemia-2 in American patients with sickle cell anemia. The influence of alpha-thalassemia-2 on the level of Hb F is dependent on the beta S-cluster haplotype. Hb A2 levels increased with decrease in the number of alpha genes. Among SC and S-beta-thalassemia patients the beta-cluster polymorphisms on the beta S chromosome were those commonly associated with the African origins of beta S haplotype. The haplotype [+--+-] was present on the C chromosome in 90% of the cases. Most beta-thalassemia chromosomes had haplotypes that matched the common African polymorphisms. An alpha-gene deletion was found in 29% of the SC and S-beta-thalassemia patients.

Effect of simple short term dietary control on urine electrolyte excretion in normal men.

Normal diet and a simple short term prescribed diet were compared with respect to mean excretion of urine electrolytes and the variability in these responses in 12 healthy male subjects. Urine was collected from 7 to 15 h (overnight) and 15 to 25 h (daytime) after the start of dietary control. Differences in mean responses were slight. For sodium and potassium excretion, however, there were tendencies for responses in subjects with high excretion on normal diet to decrease and for responses in those with low excretion on normal diet to increase towards the overall mean during the prescribed diet. The prescribed diet reduced markedly the variability in electrolyte responses and for log transformed data reductions in variability were statistically significant in the daytime urine collections. The results of this study have confirmed quantitatively the benefit of a short period of simple dietary control. The marked reduction in the variability of sodium and potassium excretion improves considerably the precision and sensitivity of studies of urine electrolyte composition.

A study of the minor peaks in high performance liquid chromatograms of globin chains on reversed phase columns.

The high performance liquid chromatograms of the hemoglobins in a hemolysate show minor peaks on reversed phase columns in addition to the expected major peaks of the alpha, beta, and gamma chains. One of these had previously been identified as the delta chain. The material in the most prominent minor peak which is termed "pre-beta" is indistinguishable from the normal beta chain in amino acid composition, but the difference has not been identified. An analogous pre-delta peak appears when chromatographically isolated Hb A2 is examined, but pre-alpha and pre-gamma peaks have not been observed. One minor peak contains a non-heme protein(s). Glycosylated hemoglobins do not separate from their non-glycosylated counterparts, but acetylated gamma chains appear to do so.

The estimation of Hb A2 in the presence of Hb C or Hb E by reverse phase high performance liquid chromatography.

Although Hb-C may be separated from Hb A2 by some ion exchange methods, most will not separate Hb E and Hb A2. The delta chain can be readily separated from the beta C, beta E and beta O-Arab chains by reverse phase HPLC. Hence, reverse phase HPLC provides a means of quantitatively determining Hb A2 in the presence of Hb C, Hb E, and Hb O-Arab. The procedure, although not highly accurate, does permit the detection of increased Hb A2, for example, in beta-thal heterozygotes and, therefore, is applicable to other conditions (Hb C, Hb E, Hb O-Arab).

Oxygen binding and stability properties of Hb Santa Ana (beta 88 Leu----Pro).

Hb Santa Ana (beta 88 Leu----Pro) was found at a level of 30% of total hemoglobin in red cells from a patient with congenital hemolytic anemia. Since no detailed functional studies of this hemoglobin have been done previously, we determined oxygen equilibrium curves of red cell suspensions, hemolysates, and isolated Hb Santa Ana. The P50 values obtained were 22.5 mm Hg (37 degrees C, pH 7.4) for red cell suspensions (normal mean = 27.0 mm Hg), 10.0 mm Hg (25 degrees C, pH 7.0) for hemolysate (normal = 13.5 mm Hg), and 1.3 mm Hg (25 degrees C, pH 7.0) for isolated Hb Santa Ana. Measurements of mechanical stability of Hb Santa Ana showed that the oxy-form of this hemoglobin was 10 times more unstable than that of Hb S and 100 times more unstable than that of Hb A. The deoxy-form of Hb Santa Ana was as unstable as its oxy-form, indicating that no stabilization (R----T conversion) takes place upon the deoxygenation of Hb Santa Ana.

Hb Aztec or alpha 2 76 (EF5) Met----Thr beta 2 detection of a silent mutant by high performance liquid chromatography.

High performance liquid chromatography has detected 14 abnormal hematological states in 600 randomly selected samples of blood. Two of these are silent mutations which are not apparent from chromatographic or electrophoretic examination. One of these has the substitution alpha 76 (EF5) Met----Thr and has been named Hb Aztec. The variant was first detected in a 9-day-old baby girl who had inherited it from her mother. This abnormal hemoglobin has no obviously deleterious effect on hematological status or health.

High performance liquid chromatographic separation of the globin chains of non-human hemoglobins.

High performance liquid chromatography has been applied to the separation of the globin chains of 16 non-human species which include common mammalian and avian species. The procedure uses a large-pore C4 column which has been effectively employed for the separation of human globin chains. In many cases, the gradient for human chains with trifluoroacetic acid-water-acetonitrile was satisfactory or required only moderate modification. The separations were excellent for all except dog hemoglobin. Many results substantiate prior published information about heterogeneity, amino acid composition, etc. of the individual hemoglobins. Additional data on some of these hemoglobins have also been obtained, and some previously unstudied hemoglobins have been examined.

Preparation and characterization of pentaammineruthenium-(histidine-83)azurin: thermodynamics of intramolecular electron transfer from ruthenium to copper.

The reaction between a5RuH2O2+ (a is NH3) and Pseudomonas aeruginosa azurin at pH 7, followed by oxidation, yields a5Ru(His-83)3+-azurin(Cu2+) as the major product. Spectroscopic measurements (UV-visible, CD, EPR, and resonance Raman) indicate that the native structure is maintained in the modified protein. The site of ruthenium binding (His-83) was identified by peptide mapping. The a5RuHis/Cu ratio in the modified protein, determined from the EPR spectrum, is 1:1, and the reduction potentials (vs. normal hydrogen electrode, pH 7.0, 25 degrees C) are blue copper (Cu2+/1+), 320 +/- 2 mV; a5Ru(His-83)3+/2+, 50 +/- 10 mV. From measurements of the reduction potentials at several temperatures in the 5-40 degrees C range, delta H degree for intramolecular Ru2+ ----Cu2+ electron transfer was estimated to be -12.4 kcal mol-1 (1 cal = 4.184 J). Analysis of kinetic data in light of the electron transfer exothermicity indicates that the reorganizational enthalpy of the blue copper site can be no larger than 7.1 kcal mol-1.