Dichloro Butenediamides as Irreversible Site-Selective Protein Conjugation Reagent

We describe maleic-acid derivatives as robust cysteine-selective reagents for protein labelling with comparable kinetics and superior stability relative to maleimides. Diamide and amido-ester derivatives proved to be efficient protein-labelling species with a common mechanism in which a spontaneous cyclization occurs upon addition to cysteine. Introduction of chlorine atoms in their structures triggers ring hydrolysis or further conjugation with adjacent residues, which results in conjugates that are completely resistant to retro-Michael reactions in the presence of biological thiols and human plasma. By controlling the microenvironment of the reactive site, we can control selectivity towards the hydrolytic pathway, forming homogeneous conjugates. The method is applicable to several scaffolds and enables conjugation of different payloads. The synthetic accessibility of these reagents and the mild conditions required for fast and complete conjugation together with the superior stability of the conjugates make this strategy an important alternative to maleimides in bioconjugation.

Dual Role of Ribosome-Binding Domain of NAC as a Potent Suppressor of Protein Aggregation and Aging-Related Proteinopathies

The nascent polypeptide-associated complex (NAC) is a conserved ribosome-associated protein biogenesis factor. Whether NAC exerts chaperone activity and whether this function is restricted to de novo protein synthesis is unknown. Here, we demonstrate that NAC directly exerts chaperone activity toward structurally diverse model substrates including polyglutamine (PolyQ) proteins, firefly luciferase, and Aβ40. Strikingly, we identified the positively charged ribosome-binding domain in the N terminus of the βNAC subunit (N-βNAC) as a major chaperone entity of NAC. N-βNAC by itself suppressed aggregation of PolyQ-expanded proteins in vitro, and the positive charge of this domain was critical for this activity. Moreover, we found that NAC also exerts a ribosome-independent chaperone function in vivo. Consistently, we found that a substantial fraction of NAC is non-ribosomal bound in higher eukaryotes. In sum, NAC is a potent suppressor of aggregation and proteotoxicity of mutant PolyQ-expanded proteins associated with human diseases like Huntington's disease and spinocerebellar ataxias.

Native electrospray mass spectrometry approaches to probe the interaction between zinc and an anti-angiogenic peptide from histidine-rich glycoprotein

Zinc modulates the biological function of histidine-rich glycoprotein (HRG) through binding to its His-rich region (HRR). The Zn2+-binding properties of a 35 amino-acid biologically-active peptide mimic of the HRR, HRGP330, were investigated using dissociative mass spectrometry approaches in addition to travelling-wave ion mobility mass spectrometry (TWIM-MS). Native mass spectrometry confirmed zinc binding to HRGP330; however, broadening of the 1H NMR resonances upon addition of Zn2+ ions precluded the attainment of structural information. A complementary approach employing TWIM-MS indicated that HRGP330 has a more compact structure in the presence of Zn2+ ions. Top-down MS/MS data supported a metal-binding-induced conformational change, as fewer fragments were observed for Zn2+-bound HRGP330. Zn2+-bound fragments of both N-terminal and C-terminal ends of the peptide were identified from collision-induced dissociation (CID) and electron transfer dissociation/proton transfer reaction (ETD/PTR) experiments, suggesting that multiple binding sites exist within this region of HRG. The combination of mass spectrometry and NMR approaches provides new insight into the highly dynamic interaction between zinc and this His-rich peptide.

Conformational flexibility within the nascent polypeptide-associated complex enables its interactions with structurally diverse client proteins

As newly synthesized polypeptides emerge from the ribosome, it is crucial that they fold correctly. To prevent premature aggregation, nascent chains interact with chaperones that facilitate folding or prevent misfolding until protein synthesis is complete. Nascent polypeptide-associated complex (NAC) is a ribosome-associated chaperone that is important for protein homeostasis. However, how NAC binds its substrates remains unclear. Using native electrospray ionization MS (ESI-MS), limited proteolysis, NMR, and cross-linking, we analyzed the conformational properties of NAC from Caenorhabditis elegans and studied its ability to bind proteins in different conformational states. Our results revealed that NAC adopts an array of compact and expanded conformations and binds weakly to client proteins that are unfolded, folded, or intrinsically disordered, suggestive of broad substrate compatibility. Of note, we found that this weak binding retards aggregation of the intrinsically disordered protein α-synuclein both in vitro and in vivo These findings provide critical insights into the structure and function of NAC. Specifically, they reveal the ability of NAC to exploit its conformational plasticity to bind a repertoire of substrates with unrelated sequences and structures, independently of actively translating ribosomes.

Placental CpG methylation of HPA-axis genes is associated with cognitive impairment at age 10 among children born extremely preterm

A major component of the neuroendocrine system is the hypothalamus-pituitary adrenal (HPA) axis. HPA axis genes are also known to play a role in placental physiology. Thus, disruptions in the signaling of HPA axis-associated genes may adversely impact the placenta as well as fetal development, with adverse consequences for health and development of the child. In support of this, recent studies have shown that placental epigenetic methylation of HPA axis genes has an impact on infant behavior. In this study, we evaluated CpG methylation of 14 placental HPA axis-associated genes from a subcohort (n=228) of the Extremely Low Gestational Age Newborns (ELGAN) cohort in relation to cognitive function in mid-childhood (e.g. 10 yrs). Multivariable logistic regression revealed that placental CpG methylation of 10 HPA-axis associated genes were significantly associated with cognition at age 10. Specifically, placental CpG methylation levels of the glucocorticoid receptor gene, Nuclear Receptor Subfamily Group 3 C Member 1 (NR3C1) and Brain-derived Neurotropic Factor (BDNF) were significantly associated with increased odds in developing moderate/severe adverse cognitive impairment at age 10. Methyl-CpG Binding Protein 2 (MECP2) was the major transcriptional regulator of the ten identified HPA genes. The data suggest that placental CpG methylation is associated with cognitive outcomes in mid-childhood.

Effects of sex and HIV serostatus on spatial navigational learning and memory among cocaine users

Spatial learning and memory are critically dependent on the integrity of hippocampal systems. Functional MRI and neuropathological studies show that hippocampal circuitry is prominently affected among HIV-seropositive individuals, but potential spatial learning and memory deficits have not been studied in detail in this population. We investigated the independent and interactive effects of sex and HIV serostatus on performance of a spatial learning and memory task in a sample of 181 individuals with a history of cocaine dependence. We found that men showed faster times to completion on immediate recall trials compared with women and that delayed recall was significantly poorer among HIV-infected compared with HIV-uninfected participants. Additionally, a sex × serostatus effect was found on the total number of completed learning trials. Specifically, HIV-infected men successfully completed more learning trials compared with HIV-infected women. Results are discussed in the context of recent reports of sex and HIV serostatus effects on episodic memory performance.

Specific sequences in the N-terminal domain of human small heat-shock protein HSPB6 dictate preferential hetero-oligomerization with the orthologue HSPB1

Small heat-shock proteins (sHSPs) are a conserved group of molecular chaperones with important roles in cellular proteostasis. Although sHSPs are characterized by their small monomeric weight, they typically assemble into large polydisperse oligomers that vary in both size and shape but are principally composed of dimeric building blocks. These assemblies can include different sHSP orthologues, creating additional complexity that may affect chaperone activity. However, the structural and functional properties of such hetero-oligomers are poorly understood. We became interested in hetero-oligomer formation between human heat-shock protein family B (small) member 1 (HSPB1) and HSPB6, which are both highly expressed in skeletal muscle. When mixed in vitro, these two sHSPs form a polydisperse oligomer array composed solely of heterodimers, suggesting preferential association that is determined at the monomer level. Previously, we have shown that the sHSP N-terminal domains (NTDs), which have a high degree of intrinsic disorder, are essential for the biased formation. Here we employed iterative deletion mapping to elucidate how the NTD of HSPB6 influences its preferential association with HSPB1 and show that this region has multiple roles in this process. First, the highly conserved motif RLFDQXFG is necessary for subunit exchange among oligomers. Second, a site ∼20 residues downstream of this motif determines the size of the resultant hetero-oligomers. Third, a region unique to HSPB6 dictates the preferential formation of heterodimers. In conclusion, the disordered NTD of HSPB6 helps regulate the size and stability of hetero-oligomeric complexes, indicating that terminal sHSP regions define the assembly properties of these proteins.

The preferential heterodimerization of human small heat shock proteins HSPB1 and HSPB6 is dictated by the N-terminal domain

Small heat shock proteins are ATP-independent molecular chaperones. Their function is to bind partially unfolded proteins under stress conditions. In vivo, members of this chaperone family are known to preferentially assemble together forming large, polydisperse heterooligomers. The exact molecular mechanisms that drive specific heteroassociation are currently unknown. Here we study the oligomers formed between human HSPB1 and HSPB6. Using small-angle X-ray scattering we could characterize two distinct heterooligomeric species present in solution. By employing native mass spectrometry we show that such assemblies are formed purely from heterodimeric building blocks, in line with earlier cross-linking studies. Crucially, a detailed analysis of truncation variants reveals that the preferential association between these two sHSPs is solely mediated by their disordered N-terminal domains.

Extensive Charge Reduction and Dissociation of Intact Protein Complexes Following Electron Transfer on a Quadrupole-Ion Mobility-Time-of-Flight MS

Non-dissociative charge reduction, typically considered to be an unwanted side reaction in electron transfer dissociation (ETD) experiments, can be enhanced significantly in order to reduce the charge state of intact protein complexes to as low as 1+ on a commercially available Q-IM-TOF instrument. This allows for the detection of large complexes beyond 100,000 m/z, while at the same time generating top-down ETD fragments, which provide sequence information from surface-exposed parts of the folded structure. Optimization of the supplemental activation has proven to be crucial in these experiments and the charge-reduced species are most likely the product of both proton transfer (PTR) and non-dissociative electron transfer (ETnoD) reactions that occur prior to the ion mobility cell. Applications of this approach range from deconvolution of complex spectra to the manipulation of charge states of gas-phase ions.

Biophysical studies on interactions and assembly of full-size E3 ubiquitin ligase: suppressor of cytokine signaling 2 (SOCS2)-elongin BC-cullin 5-ring box protein 2 (RBX2)

The multisubunit cullin RING E3 ubiquitin ligases (CRLs) target post-translationally modified substrates for ubiquitination and proteasomal degradation. The suppressors of cytokine signaling (SOCS) proteins play important roles in inflammatory processes, diabetes, and cancer and therefore represent attractive targets for therapeutic intervention. The SOCS proteins, among their other functions, serve as substrate receptors of CRL5 complexes. A member of the CRL family, SOCS2-EloBC-Cul5-Rbx2 (CRL5(SOCS2)), binds phosphorylated growth hormone receptor as its main substrate. Here, we demonstrate that the components of CRL5(SOCS2) can be specifically pulled from K562 human cell lysates using beads decorated with phosphorylated growth hormone receptor peptides. Subsequently, SOCS2-EloBC and full-length Cul5-Rbx2, recombinantly expressed in Escherichia coli and in Sf21 insect cells, respectively, were used to reconstitute neddylated and unneddylated CRL5(SOCS2) complexes in vitro. Finally, diverse biophysical methods were employed to study the assembly and interactions within the complexes. Unlike other E3 ligases, CRL5(SOCS2) was found to exist in a monomeric state as confirmed by size exclusion chromatography with inline multiangle static light scattering and native MS. Affinities of the protein-protein interactions within the multisubunit complex were measured by isothermal titration calorimetry. A structural model for full-size neddylated and unneddylated CRL5(SOCS2) complexes is supported by traveling wave ion mobility mass spectrometry data.

Allosteric modulation of zinc speciation by fatty acids

BACKGROUND

Serum albumin is the major protein component of blood plasma and is responsible for the circulatory transport of a range of small molecules that include fatty acids, hormones, metal ions and drugs. Studies examining the ligand-binding properties of albumin make up a large proportion of the literature. However, many of these studies do not address the fact that albumin carries multiple ligands (including metal ions) simultaneously in vivo. Thus the binding of a particular ligand may influence both the affinity and dynamics of albumin interactions with another.

SCOPE OF REVIEW

Here we review the Zn(2+) and fatty acid transport properties of albumin and highlight an important interplay that exists between them. Also the impact of this dynamic interaction upon the distribution of plasma Zn(2+), its effect upon cellular Zn(2+) uptake and its importance in the diagnosis of myocardial ischemia are considered.

MAJOR CONCLUSIONS

We previously identified the major binding site for Zn(2+) on albumin. Furthermore, we revealed that Zn(2+)-binding at this site and fatty acid-binding at the FA2 site are interdependent. This suggests that the binding of fatty acids to albumin may serve as an allosteric switch to modulate Zn(2+)-binding to albumin in blood plasma.

GENERAL SIGNIFICANCE

Fatty acid levels in the blood are dynamic and chronic elevation of plasma fatty acid levels is associated with some metabolic disorders such as cardiovascular disease and diabetes. Since the binding of Zn(2+) to albumin is important for the control of circulatory/cellular Zn(2+) dynamics, this relationship is likely to have important physiological and pathological implications. This article is part of a Special Issue entitled Serum Albumin.

Cleaning and decontamination efficacy of wiping cloths and silver dihydrogen citrate on food contact surfaces

AIMS

  To test the efficacy of four wipe cloth types (cotton bar towel, nonwoven, microfibre and blended cellulose/cotton) with either quaternary ammonia cleaning solution or silver dihydrogen citrate (SDC) in cleaning food contact surfaces.

METHODS

  Swab samples collected from untreated, cloth-treated and cloth disinfectant-treated surfaces were subjected to hygiene monitoring using adenosine triphosphate (ATP) bioluminescence and aerobic total plate counting (TPC) assays.

RESULTS

  Adenosine triphosphate measurements taken after wiping the surfaces showed poor cleaning by nonwoven cloths (2·89 RLU 100 cm(-2) ) than the microfibre (2·30 RLU 100 cm(-2) ), cotton terry bar (2·26 RLU 100 cm(-2) ) and blended cellulose/cotton cloth types (2·20 RLU 100 cm(-2) ). The cellulose/cotton cloth showed highest log reduction in ATP-B RLU values (95%) and CFU values (98·03%) when used in combination with SDC disinfectant.

CONCLUSIONS

  Cleaning effect of wiping cloths on food contact surfaces can be enhanced by dipping them in SDC disinfectant. ATP-B measurements can be used for real-time hygiene monitoring in public sector, and testing microbial contamination provides more reliable measure of cleanliness.

SIGNIFICANCE AND IMPACT OF THE STUDY

  Contaminated food contact surfaces need regular hygiene monitoring. This study could help to estimate and establish contamination thresholds for surfaces at public sector facilities and to base the effectiveness of cleaning methods.

Antimicrobial effect and mode of action of terpeneless cold-pressed Valencia orange essential oil on methicillin-resistant Staphylococcus aureus

AIMS

The objectives of this study were to evaluate the antistaphylococcal effect and elucidate the mechanism of action of orange essential oil against antibiotic-resistant Staphylococcus aureus strains.

METHODS AND RESULTS

The inhibitory effect of commercial orange essential oil (EO) against six Staph. aureus strains was tested using disc diffusion and agar dilution methods. The mechanism of EO action on MRSA was analysed by transcriptional profiling. Morphological changes of EO-treated Staph. aureus were examined using transmission electron microscopy. Results showed that 0·1% of terpeneless cold-pressed Valencia orange oil (CPV) induced the cell wall stress stimulon consistent with the inhibition of cell wall synthesis. Transmission electron microscopic observation revealed cell lysis and suggested a cell wall lysis-related mechanism of CPV.

CONCLUSIONS

CPV inhibits the growth of Staph. aureus, causes gene expression changes consistent with the inhibition of cell wall synthesis, and triggers cell lysis.

SIGNIFICANCE AND IMPACT OF THE STUDY

Multiple antibiotics resistance is becoming a serious problem in the management of Staph. aureus infections. In this study, the altered expression of cell wall-associated genes and subsequent cell lysis in MRSA caused by CPV suggest that it may be a potential antimicrobial agent to control antibiotic-resistant Staph. aureus.

Molecular and neuroanatomical characterization of single neurons in the mouse medullary gigantocellular reticular nucleus

Medullary gigantocellular reticular nucleus (mGi) neurons have been ascribed a variety of behaviors, many of which may fall under the concepts of either arousal or motivation. Despite this, many details of the connectivity of mGi neurons, particularly in reference to those neurons with ascending axons, remain unknown. To provide a neuroanatomical and molecular characterization of these cells, with reference to arousal and level-setting systems, large medullary reticular neurons were characterized with retrograde dye techniques and with real-time reverse transcriptase PCR (RT-PCR) analyses of single-neuron mRNA expression in the mouse. We have shown that receptors consistent with participation in generalized arousal are expressed by single mGi neurons and that receptors from different families of arousal-related neurotransmitters are rarely coexpressed. Through retrograde labeling, we have shown that neurons with ascending axons and neurons with descending axons tend to form like-with-like clusters, a finding that is consistent across age and gender. In comparing the two groups of retrogradely labeled neurons in neonatal animals, those neurons with axons that ascend to the midbrain show markers for GABAergic or coincident GABAergic and glutamatergic function; in contrast, approximately 60% of the neurons with axons that descend to the spinal cord are glutamatergic. We discuss the mGi's relationship to the voluntary and emotional motor systems and speculate that neurons in the mGi may represent a mammalian analogue to Mauthner cells, with a separation of function for neurons with ascending and descending axons.

Development of the antiviral state in response to interferon

The development of resistance in response to interferon depends on cellular RNA synthesis and probably also on cellular protein synthesis. The evidence for these requirements is reviewed, as well as the proposal that this evidence indicates the existence of a specific response of the cell to interferon, involving the induced synthesis of an antiviral protein. Direct evidence for such an interpretation has not been obtained, and alternative explanations are discussed which do not require quantitative or qualitative differences in the RNA and protein made in cells exposed to interferon. The possible role of the ribosome in the antiviral action of interferon is also discussed.

Implementation of a multidisciplinary guideline-driven approach to the care of the extremely premature infant improved hospital outcomes

AIM

To test the hypothesis that implementing guidelines for the standardized care of the extremely premature infant (<27 weeks) in the first week of life would improve patient outcomes in an all referral NICU.

METHODS

Data were collected on all infants <27 weeks gestational age and <7 days of age on admission cared for using these small baby guidelines (SBG), as well as on all age-matched infants admitted the year prior (comparison).

RESULTS

Thirty-seven patients were cared for utilizing the SBG and 40 patients were in the comparison group. There were no differences between the groups in gestational age, birthweight or age on admission. There was no difference in survival to discharge (73% SBG, 70% comparison). The mean length of stay for survivors was 112 +/- 38 days SBG and 145 +/- 76 days (p < 0.05) comparison group. Survival without BPD was greater in the SBG group (24%) than in the comparison group (9%; p < 0.05), and survival without severe IVH was greater in the SBG group (65%) than in the comparison group (38%; p < 0.01).

CONCLUSIONS

These data demonstrate that applying a unified approach to the care of the extremely premature infant in the first week of life resulted in a decrease in the length of hospitalization and improved patient outcomes.

Arousal-related reticular neurons during reduced oxygen tension: resilience and recovery of electrical activity

Whole-cell patch clamp recordings of the electrical activity of large medullary reticular formation neurons, in nucleus gigantocellularis, were performed under control conditions and under conditions of hypoxia or anoxia. Neurons were discovered whose activity was remarkably resilient during and after the reduction or loss of oxygen. Such cells may relate to the ability of the newborn brain to survive hypoxia/anoxia, and also may demonstrate the preservation of neurons involved in generalized CNS arousal, as would be appropriate for activating behavioral responses to the reduction or loss of oxygen.

Thermal inactivation of Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes in breaded pork patties

Decimal reduction times (D-values) and thermal resistance constants (z-values) for 3 foodborne pathogenic bacteria in formulated ready-to-eat breaded pork patties were determined with thermal inactivation studies. Meat samples, inoculated with Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes cultures or uninoculated controls, were packaged in sterile bags, immersed in circulated water bath, and held at 55, 57.5, 60, 62.5, 65, 67.5, and 70 degrees C for different durations of time. The D- and z-values were determined by using a linear regression model. Average calculated D-values for E. coli O157:H7, Salmonella, and L. monocytogenes at a temperature range of 55 to 70 degrees C were 32.11 to 0.08 min, 69.48 to 0.29 min, and 150.46 to 0.43 min, respectively. Calculated z-values for E. coli O157:H7, Salmonella, and L. monocytogenes were 5.4, 6.2, and 5.9 degrees C, respectively. The results of this study will be useful to food processors to validate thermal lethality of the studied foodborne pathogens in ready-to-eat breaded pork patties.

Longitudinally preserved psychomotor performance in long-term asymptomatic HIV-infected individuals

BACKGROUND

Recent case reports have suggested that some asymptomatic HIV-infected individuals can develop CNS disturbances despite intact immunologic functioning and long-term suppression of plasma HIV concentrations to undetectable levels. This possibility has not yet been systematically studied longitudinally.

METHODS

Using longitudinal data from the Multicenter AIDS Cohort Study, we investigated neuropsychological performance in long-term asymptomatic HIV-infected men who have sex with men. Performance over a 5-year period on the Symbol Digit Modalities test and the Trail Making Tests were compared in three HIV-positive asymptomatic groups [defined as 1) highly active antiretroviral therapy (HAART) treated with undetectable viral loads (n = 83), 2) AIDS-free for more than 15 years without HAART (n = 29), and 3) absence of clinical AIDS or CD4(+) lymphocyte count below 200 cells/muL at the beginning and end of the study period (n = 233)] and in HIV-negative controls (n = 237). Data were analyzed using linear mixed models and proportional odds logistic regression modeling with generalized estimating equations.

RESULTS

There was no evidence of performance differences or performance declines over the 5-year period of study in any of the three long-term asymptomatic groups as compared with the HIV-negative group in the Symbol Digit Modalities test or the Trail Making Tests. Performance decrements were, however, observed with increasing age in each of the tests administered, demonstrating that performance declines could be detected by these methods.

CONCLUSIONS

Regardless of how long-term asymptomatic status was defined immunologically or virologically, neuropsychological test performances remained stable. These findings suggest that psychomotor speed is preserved over many years in HIV-infected individuals with controlled HIV viremia.

Thermal inactivation studies of Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes in ready-to-eat chicken-fried beef patties

Thermal inactivation studies were used to determine the D- and z-values of Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes in ready-to-eat chicken-fried beef patties. Inoculated meat was packaged in sterile bags, which were immersed in a circulated water bath and held at 55, 57.5, 60, 62.5, 65, 67.5, and 70 degrees C for different lengths of time. D- and z-values were determined with a linear regression model. Average D-values at temperatures 55 to 70 degrees C were 27.62 to 0.04 min for E. coli 0157:H7, 67.68 to 0.22 min for Salmonella, and 81.37 to 0.31 min for L. monocytogenes. The z-values were 5.2 degrees C for E. coli O157:H7, 6.0 degrees C for Salmonella, and 6.1 degrees C for L. monocytogenes. The results of this study can be used by food processors to validate their processes and help eliminate pathogenic bacteria associated with chicken-fried beef products.

Thermal process validation for Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes in ground turkey and beef products

At 55 to 70 degrees C, thermal inactivation D-values for Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes were 19.05 to 0.038, 43.10 to 0.096, and 33.11 to 0.12 min, respectively, in ground turkey and 21.55 to 0.055, 37.04 to 0.066, and 36.90 to 0.063 min, respectively, in ground beef. The z-values were 5.73, 5.54, and 6.13 degrees C, respectively, in ground turkey and 5.43, 5.74, and 6.01 degrees C, respectively, in ground beef. In both ground turkey and beef, significant (P < 0.05) differences were found in the D-values between E. coli O157:H7 and Salmonella or between E. coli O157:H7 and L. monocytogenes. At 65 to 70 degrees C, D-values for E. coli O157:H7, Salmonella, and L. monocytogenes were also significantly (P < 0.05) different between turkey and beef. The obtained D- and z-values were used in predicting process lethality of the pathogens in ground turkey and beef patties cooked in an air impingement oven and confirmed by inoculation studies for a 7-log (CFU/g) reduction of E. coli O157:H7, Salmonella, and L. monocytogenes.

Novel cytopathological structures induced by mixed infection of unrelated plant viruses

ABSTRACT When two unrelated plant viruses infect a plant simultaneously, synergistic viral interactions often occur resulting in devastating diseases. This study was initiated to examine ultrastructural virus-virus interactions of mixed viral infections. Mixed infections were induced using potyviruses and viruses from other plant virus families. Novel ultrastructural paracrystalline arrays composed of co-infecting viruses, referred to as mixed virus particle aggregates (MVPAs), were noted in the majority of the mixed infections studied. When the flexuous rod-shaped potyvirus particles involved in MVPAs were sectioned transversely, specific geometrical patterns were noted within some doubly infected cells. Although similar geometrical patterns were associated with MVPAs of various virus combinations, unique characteristics within patterns were consistent in each mixed infection virus pair. Centrally located virus particles within some MVPAs appeared swollen (Southern bean mosaic virus mixed with Blackeye cowpea mosaic virus, Cucumber mosaic virus mixed with Blackeye cowpea mosaic virus, and Sunn hemp mosaic virus mixed with Soybean mosaic virus). This ultrastructural study complements molecular studies of mixed infections of plant viruses by adding the additional dimension of visualizing the interactions between the coinfecting viruses.

Viral and bacterial agents associated with experimental transmission of infectious proventriculitis of broiler chickens

Proventriculitis of broilers can be reproduced by oral inoculation of day-old chicks with a proventricular homogenate from affected 3-wk-old broilers. The objective of the following studies was to isolate from this homogenate viral and bacterial isolates that could produce proventriculitis. A monoclonal antibody to infectious bursal disease virus (IBDV) was used to precipitate virus from the homogenate. A primary chicken digestive tract cell culture system was also used to isolate virus from a 0.2-microm filtrate of the homogenate, and a bacterium was also isolated from the homogenate. In trial 1, day-old birds were orally inoculated with either proventriculus homogenate or monoclonal antibody immunoprecipitated IBDV (MAB-IBDV). At 4, 7, 14, and 21 days postinfection (PI), 12 birds from each treatment group were subjected to necropsy. In trial 2, day-old birds were orally inoculated with either infectious proventriculus homogenate, suspect virus isolated in cell culture and propagated in embryo livers and spleens, or a bacterial isolate. Twelve birds from each treatment were subjected to necropsy at days 7, 14, 21, and 28 PI. In trial 3, treatments were maintained in negative pressure isolation chambers, and an additional treatment included virus plus bacterial isolate. Twenty-four birds from each treatment were subjected to necropsy at day 21 PI. In trial 1, infectious homogenate decreased body weight and relative gizzard weights at 4, 7, 14, and 21 days PI. Proventriculus relative weight was increased at days 7, 14, and 21 PI, and proventriculus lesion scores were increased at days 14 and 21 PI. Bursa/spleen weight ratios were decreased at day 14, and feed conversion was increased at days 4 and 21. The MAB-IBDV treatment decreased proventriculus and gizzard relative weights at day 4 PI, increased proventriculus lesion scores and bursa/spleen weight ratios at day 14, and decreased heterophil/lymphocyte ratios at day 21. In trial 2, all infected birds had significantly higher mean relative proventriculus weights at 21 days PI and had higher 4-wk mean proventriculus scores as compared with both control groups. In trial 3, birds treated with homogenate and birds treated with both suspect virus and the bacterial isolate had significantly higher proventriculus lesion scores; higher relative weights of proventriculus, gizzard, liver, and heart; lower body weights; and lower relative bursa weights compared with the saline control group. These studies suggest that infectious proventriculitis has a complex etiology involving both viral and bacterial infection.

Thought disorder in schizophrenia and mania: impaired context

This research studied hypotheses that positive thought disorder in schizophrenia is influenced by patients' not taking in immediate target contextual material, thereby losing vital cues that guide thought processes. We assessed 164 acute inpatients (including 55 schizophrenia and 31 bipolar disorder patients), using standardized measures of thought disorder. We also used new measures that assessed (1) total ignoring of context, and (2) straying from the context. Results were as follows: (1) only 9 percent of the schizophrenia patients showed strong evidence of completely ignoring the external context; (2) straying from the external context while simultaneously maintaining part of the context was significantly more common than complete absence of context (p < 0.01); (3) patients with thought disorder strayed from the context significantly more than patients without thought disorder (p < 0.001); and (4) straying from the context was involved in the thought disorder of some, but not all, schizophrenia and mania patients. The data suggest that thought disorder in schizophrenia is not typically due to a failure to "hear" or to take in the relevant contextual material necessary for an appropriate response. Loss of context is involved in some, but not all, thought disorder in schizophrenia and mania.

Auditory working memory in HIV-1 infection

We evaluated auditory working memory in 41 HIV-seropositive (HIV+) and 37 HIV-seronegative (HIV-) male drug users, employing a modified version of the Letter-Number Span Task developed by Gold and colleagues. We added a control condition to the standard task in order to evaluate more directly the contribution of the processing component to the working memory deficits with the effects of storage demands minimized. HIV+ subjects performed significantly more poorly compared to controls on an index of working memory processing derived from raw scores obtained under the two testing conditions. These findings are consistent with our previous reports that HIV-related working memory deficits are evident across multiple informational domains; further, the deficit appears to involve multiple-component functions of working memory. Converging findings from recent working memory studies and from primate and neuroimaging investigations suggest that functional abnormalities of prefrontal cortex should receive greater emphasis in models of neurocognitive aspects of HIV-1 infection, which have typically emphasized "subcortical" deficits.

A home program of rehabilitation for moderately severe traumatic brain injury patients. The DVHIP Study Group

We have recently reported the results of a prospective controlled randomized trial comparing home versus inpatient cognitive rehabilitation for patients with moderate to severe head injury. That study showed no overall difference in outcomes between the two groups.(1) In this article, we provide further details of the home program arm of the study. All patients in the home program received medical treatment as needed, a multidisciplinary in-hospital evaluation, and TBI counseling before entering the eight-week home program, which then included guidance on home activities, as well as weekly telephone calls from a psychiatric nurse.

Verbal working memory in HIV-seropositive drug users

Recent evidence suggests that HIV-seropositive drug users are impaired on tasks of visuospatial working memory compared with drug users seronegative for HIV. In the current study we evaluated the performance of 30 HIV-seropositive male drug users and 30 risk-matched seronegative controls on two measures of verbal working memory, the Listening Span and the verbal Self Ordered Pointing Task. Impaired working memory performance was significantly more common among HIV-seropositive persons compared to controls, with the highest incidence of deficit among symptomatic participants. These findings indicate that working memory deficits in persons with HIV are not domain-specific and can be demonstrated reliably in drug users.

Cognitive rehabilitation for traumatic brain injury: A randomized trial. Defense and Veterans Head Injury Program (DVHIP) Study Group

CONTEXT

Traumatic brain injury (TBI) is a principal cause of death and disability in young adults. Rehabilitation for TBI has not received the same level of scientific scrutiny for efficacy and cost-efficiency that is expected in other medical fields.

OBJECTIVE

To evaluate the efficacy of inpatient cognitive rehabilitation for patients with TBI.

DESIGN AND SETTING

Single-center, parallel-group, randomized trial conducted from January 1992 through February 1997 at a US military medical referral center.

PATIENTS

One hundred twenty active-duty military personnel who had sustained a moderate-to-severe closed head injury, manifested by a Glasgow Coma Scale score of 13 or less, or posttraumatic amnesia lasting at least 24 hours, or focal cerebral contusion or hemorrhage on computed tomography or magnetic resonance imaging.

INTERVENTIONS

Patients were randomly assigned to an intensive, standardized, 8-week, in-hospital cognitive rehabilitation program (n=67) or a limited home rehabilitation program with weekly telephone support from a psychiatric nurse (n=53).

MAIN OUTCOME MEASURES

Return to gainful employment and fitness for military duty at 1-year follow-up, compared by intervention group.

RESULTS

At 1-year follow-up, there was no significant difference between patients who had received the intensive in-hospital cognitive rehabilitation program vs the limited home rehabilitation program in return to employment (90% vs 94%, respectively; P=.51; difference, 4% [95% confidence interval ¿CI¿, -5% to 14%]) or fitness for duty (73% vs 66%, respectively; P=. 43; difference, 7% [95% CI, -10% to 24%]). There also were no significant differences in cognitive, behavioral, or quality-of-life measures. In a post-hoc subset analysis of patients who were unconscious for more than 1 hour (n = 75) following TBI, the in-hospital group had a greater return-to-duty rate (80% vs 58%; P=. 05).

CONCLUSIONS

In this study, the overall benefit of in-hospital cognitive rehabilitation for patients with moderate-to-severe TBI was similar to that of home rehabilitation. These findings emphasize the importance of conducting randomized trials to evaluate TBI rehabilitation interventions. JAMA. 2000;283:3075-3081

Quantitative computed tomography in the evaluation of spinal osteoporosis following spinal cord injury

Disuse osteoporosis occurs in the lower extremities of patients with spinal cord injury (SCI). However, spinal osteoporosis is not usually observed in these patients. We investigated lumbar spine bone mineral density (BMD) in SCI patients using single energy quantitative computed tomography (QCT) and dual-energy X-ray absorptiometry (DXA). Our study population consisted of 64 patients with long-standing SCI. Spine BMD (g/cm3) was assessed by QCT at four vertebrae ranging from T11 to L4 with single mid-vertebral CT slices 1 cm thick parallel to the vertebral end-plates. Confounding variables affecting normal trabecular bone pattern, such as compression fractures, surgical hardware or fat replacement, were excluded. For a subset of 29 patients, DXA values of the spine and femoral neck were also measured, and QCT and DXA Z-scores were compared On the average, the 64 SCI patients had Z-scores 2.0 +/- 1.2 below those of age-matched controls. In the subset of 29 patients with both QCT and DXA measurements, the QCT and DXA Z-scores were 2.4 +/- 1.1 below and 1.3 +/- 2.3 above the mean, respectively (p < 0.0001). Our results indicate that QCT reveals osteoporosis of the spine after SCI, in contrast to DXA. We postulate that QCT is more valuable for evaluating spinal osteoporosis following SCI than DXA and thus recommend QCT for spinal BMD studies in SCI.

Intracranial deployment of coronary stents for symptomatic atherosclerotic disease

Intracranial percutaneous transluminal balloon angioplasty (PTA) has been used as a technique of last resort in the treatment of intracranial atherosclerotic disease when medical and surgical alternatives have failed or cannot be applied. The major risks associated with PTA include intracranial vessel rupture and abrupt vessel dissection causing occlusion. Angioplasty techniques in the extracranial circulation have been improved by the development of safe stent technology in combination with potent antiplatelet agents. We report three successful cases of symptomatic intracranial atherosclerotic disease in middle-aged adults treated by endovascular PTA followed by deployment of coronary stents.

Reaction times are faster in HIV-seropositive patients on antiretroviral therapy: A preliminary report

We evaluated subclinical mental and motor slowing in 142 HIV-seropositive patients without dementia, using computerized simple and choice reaction time tasks and self-report measures of psychological distress. Patients on antiretroviral therapy at the time of testing (n = 79) had significantly faster choice reaction times (p < 0.05), indicating faster mental processing speed, than untreated patients (n = 63). These faster RTs could not be attributed to differences in age, education, risk factors, degree of immunosuppression, substance abuse history, peripheral neuropathy, or psychological distress. Reaction time tasks should be investigated further as potential outcome measures in clinical trials, particularly for subjects with few or no overt cognitive deficits.

Postural reflexes in patients with HIV-1 infection

OBJECTIVE

We studied whether medium latency (ML) and long latency (LL) postural reflexes, which are abnormal in a number of neurological conditions including basal ganglia disorders, provide an early marker of CNS involvement in HIV-positive patients.

METHODS

Leg reflexes were elicited in 9 neurologically normal HIV-positive patients and 10 healthy controls who were standing upright, using toe-up forceplate rotations of varying amplitude (4 degrees and 10 degrees) and predictability (serial and random).

RESULTS

For predictable amplitude perturbations, posturally destabilizing ML and stabilizing LL responses in HIV-seropositives did not differ from controls. However, for unpredictable amplitude perturbations, HIV-positive patients inappropriately manifested a mid-size default LL response, in contrast to healthy subjects who showed a maximum size default response.

CONCLUSIONS

These results suggest that impaired modulation of LL reflex processing occurs in early stages of HIV infection, prior to the onset of clinical postural instability, and this dysregulation may be influenced by cognitive factors.

Influence of heterotopic ossification of the hip on bone densitometry: a study in spinal cord injured patients

OBJECTIVE

To evaluate (1) the magnitude of falsely elevated bone density results caused by heterotopic ossification (HO) around the hip and (2) effect of age of patients when the measurement was taken, age of patients at injury, and age of injury (time since event) to the prevalence of HO.

SUBJECTS AND METHODS

We blindly analyzed plain radiographs of the hip [(obtained within 1 month of dual energy X-ray absorptiometry (DEXA)] in 107 spinal cord injured (SCI) patients for HO and matched the result to the three regions of interest (ROI): the femoral neck, Ward's triangle, and the trochanter. The influence of HO on bone densitometric values was determined by the analysis of variance (ANOVA) and post-hoc analysis.

RESULTS

Nineteen (18%) patients had HO; overlying the femoral neck (79%), trochanter (74%) and Ward's triangle (37%), respectively. Significant elevation of densitometric values (P < 0.05 or less) was observed in a various magnitude at each ROI, with the greatest elevation at Ward's triangle. The prevalence of HO was high when the patients were injured at age range of 20-39 years.

CONCLUSIONS

HO around the hip can cause significantly elevated bone densitometry results at all ROIs, which can obscure underlying osteoporosis, leading to underestimation of fracture risk. Determination of bone density in this region with corresponding plain radiographs would be of help. In SCI patients, prevalence of HO was high when the age of patients at injury was 20-39 years.

Information processing and antiretroviral therapy in HIV-1 infection

Computerized reaction time (RT) tasks are sensitive measures of subclinical HIV-related mental slowing. We previously reported that nondemented HIV-seropositive patients on antiretroviral therapy at the time of testing had faster choice RTs compared to matched untreated seropositive participants. In the present study, we evaluated the performance of 163 nondemented HIV-seropositive participants on a reaction time version of the Stroop task as a function of antiretroviral status. Persons on antiretroviral therapy at the time of testing had significantly faster reaction times than untreated individuals, although treated asymptomatic participants showed significantly less Stroop interference than treated symptomatic participants. These effects could not be attributed to differences in demographic variables, disease status, substance abuse, or psychological distress. These data indicate that central information processing is faster for patients treated with antiretroviral compounds compared to untreated patients, and suggest that reaction time tasks may have significant potential utility in clinical trials of neuroprotective compounds.

Prolonged response of multicentric reticulohistiocytosis to low dose methotrexate

We describe a case of multicentric reticulohistiocytosis complicated by central retinal vein thrombosis and trigeminal neuropathy. A variety of treatment modalities were tried in this patient. Both skin disease and arthritis responded to low dose methotrexate over 8 years of followup. Graduated compression gloves produced an excellent cosmetic improvement in the disfiguring skin lesions.

Neurobehavioral functioning in asymptomatic HIV-1 infected women

Numerous reports have assessed the neuropsychological functioning of medically asymptomatic HIV-1 infected men. However, to date there have been no published studies of the neuropsychological functioning of asymptomatic HIV-1 infected women, even though women represent the fastest-growing demographic group of HIV-1 infected individuals. In this investigation, 31 women (17 asymptomatic HIV-1 seropositive, 14 seronegative) were administered a battery of neurocognitive and neuropsychiatric instruments. Participants in both groups were matched for age, education, months since injection drug use, and substance use. Group comparisons revealed no significant differences in any of the neurocognitive or neuropsychiatric measures. The results of this preliminary study suggest that clinically significant differences in neurobehavioral function are unlikely in medically asymptomatic HIV-1 infected women compared to seronegative controls. However, additional studies are needed with larger sample sizes and with careful attention to possible confounding or masking variables.

Bone mineral density and indexes of bone metabolism in spinal cord injury

We evaluated the pattern of osteoporosis after spinal cord injury, determined the time-frame of the changes, and elucidated the relationship among parathyroid hormone levels, biochemical markers of bone formation, and the pattern of bone mass loss. We included 176 subjects with spinal cord injury and 62 subjects without spinal cord injury as controls in the study. Bone mineral density of the spine and the proximal femur was measured. The participants' age, level of injury, and length of time since injury were compared with the nonspinal cord-injured controls and with each other. Serum levels of calcium, calcitonin, biochemical markers of bone formation, and parathyroid hormone were determined. Our results revealed that bone mineral density of the proximal femur declined and reached fracture threshold at one to five years after injury. The decline was detected at 12 months after injury in all age groups. Spinal bone mineral density neither declined significantly nor reached fracture threshold. Parathyroid hormone levels declined before the end of the first year postinjury and increased at one to nine years postinjury in the 20- to 39-year age group. The increase correlated with the initial decline of bone mineral density of the proximal femur. Our studies in spinal cord-injured subjects revealed a pattern of osteoporosis similar to age and parathyroid dysfunction-related osteoporosis. No other correlation was detected between indexes of bone metabolism and bone mineral density measurements.

Working memory deficits in HIV-seropositive drug users

We studied the integrity of working memory operations in 38 HIV-seropositive and 20 seronegative drug users, using a modified version of the Tower of London task. This new task, the Tower of London-Working Memory version (TOL-WM), includes a delayed-response component in addition to the planning required for successful performance of the standard TOL. Symptomatic HIV-seropositive participants solved significantly fewer TOL-WM problems compared to matched seronegative controls. However, seropositive and seronegative subjects showed similar overall levels of planning efficiency, suggesting that the TOL-WM deficit may be associated primarily with failure to encode or maintain an adequate online memory representation. The results of this study confirm our previous report of a possible working memory deficit in HIV-1 infection and suggest that measures of working memory have particular utility in the evaluation of HIV-related cognitive deficits.

Densitometric patterns of spinal cord injury associated bone loss

The purpose of the study was to use dual energy X-ray absorptiometry to measure bone mineral density (BMD) in the lumbar spine, the femoral neck, Ward's triangle, and the greater trochanter in 204 men (69 able-bodies controls and 135 spinal cord injured patients) stratified according to age (20-39, 40-59, and 60+ years old) in order to determine whether changes in BMD were age related, and to determine when these changes began to appear. The BMDs of the lumbar spine of both the 40-59 year old and the 60+ year old patients were significantly higher (P < or = 0.012) than the 40-59 year old and 60+ year old controls, respectively. The femoral region BMDs of the 20-39 year old and the 40-59 year old patients were all significantly lower (P < or = 0.027) than the 20-39 year old and 40-59 year old controls, respectively. When patients were grouped according to the time since their injury (0-1, 1-5, 6-9, 10-19, 20-29, 30-39, 40-49, and 50-59 years post injury) within the various age categories different results were obtained. In all the age categories, BMD loss occurred starting one year after spinal cord injury in the hip region. This bone loss took place gradually, reaching a significant plateau (P < or = 0.017) at 19 years post injury and then started improving. The spine BMD in our patient population never significantly decreased, and started improving as the age of the injury increased. Findings presented for the femoral regions were similar to other investigators' findings; however, the steady bone mass maintained in the lumbar area, which increased with age regardless of the age of the injury, with the bone mass loss in the hip area, were the most notable new findings.

Influence of spondylopathy on bone densitometry using dual energy X-ray absorptiometry

Spinal cord injury (SCI), as well as other neuromuscular disorders, not only results in osteopenia but also induces various patterns of osseous, articular, and soft tissue alterations. In the spinal column, a variety of abnormalities occur. To evaluate the magnitude of discrepancy of bone densitometry results caused by spondylopathy in SCI patients, we analyzed anteroposterior (AP) radiographs of the lumbar spine [obtained within 1 month of dual energy X-ray absorptiometry (DXA)] in 116 SCI patients for various manifestations of spondylopathy, and matched the result to each vertebral level (L1, 2, 3, 4). The dataset was stratified by individual vertebra (totally 463 vertebrae) as valid (no demonstrable other abnormal density on plain radiograph except osteopenia), abnormal without, and abnormal with hardware. The influence of spondylopathy on bone densitometry results was determined by the analysis of variance (ANOVA) and post hoc analysis. Our results showed that 227 (49%) vertebrae were abnormal. Significant elevation (15%, 15%, 18%, 20%; P < 0.001-P < 0.05) of bone mineral density (BMD; g/cm2) was observed at all levels (L1, 2, 3, 4, respectively), particularly at those abnormal vertebrae without hardware compared with valid (no other abnormal density on radiograph except osteopenia (Table 1). The L4 level was most severely affected. We concluded that in SCI patients, owing to various secondary progressive skeletal abnormalities, particularly neuropathic spondylopathy, can have strongly and significantly elevated vertebral bone densitometry results, which can obscure underlying osteoporosis, leading to misinterpretation and underestimation of fracture risk. DXA, although characterized by improving spatial resolution, cannot replace radiography in establishing the magnitude of this skeletal pathology. Therefore, determination of bone density in this region with corresponding plain radiographs is highly recommended.

Demineralization in tetraplegic and paraplegic man over time

The aim of the present study was to compare bone mineral density (BMD in g/cm2) in the lumbar spine and three hip regions of male spinal cord injured subjects at various times post injury to age-matched able-bodied controls and to correlate their BMDs to their age and level of their spinal cord lesion. Patients and controls were stratified into three 20 years age groups (20-39, 40-59, and 60+ years of age). BMD measurements were obtained using dual energy X-ray absorptiometry (DEXA, Lunar Model DPX). BMD levels taken within the first year of injury were not significantly lower than the age-matched able-bodies controls. The 20-39 year old patients injured longer than 1 year had significantly lower (P < or = 0.01) BMDs in their femoral region than both their age matched controls and the 20-39 year old acutely injured (injured for less than 1 year) patients. Although femoral BMDs of both paraplegic and quadriplegic patients 40-59 and 60+ years of age decreased over time, none showed significant bone loss in this regions until 10 years after their injury. These results indicate that spinal cord injury associated bone loss occurs most dramatically in the femoral region of young men. These results also indicate that initial bone mass loss does not occur prior to 1 year post-injury to the extent that it is detectable by densitometry, or at least it did not occur in our patients.

Topography of the maximum of the amplitude of EEG frequency bands in dementia of the Alzheimer type

The localization of the maxima of activity of 36 patients with dementia of the Alzheimer type and 36 age-matched controls was calculated after Fourier transformation of EEG data in six frequency bands (4 Hz steps between 1 and 24 Hz). Patients were divided into three groups of severity (BCRS mean < 3,9, 4.0-4.9, and > 4.9). Significant differences were found in the beta frequency band. In the distribution of the maxima of the activity, the maxima of patients were located more frontally than the maxima of controls. The alterations were staged dependent. The beta activity in EEG is said to be correlated with cognitive processes; the correlation between cognitive decline and decreasing beta activity in dementia of the Alzheimer type might support this assumption. Differences in the location of the maxima between patients and controls might allow for differentiation between both groups.

Delayed recognition memory span in HIV-1 infection

We administered a spatial version of the Delayed Recognition Span Test (DRST), a working memory task performed abnormally by patients with basal ganglia disease, to a group of 96 HIV-seropositive and 83 seronegative subjects with a high prevalence of substance abuse. For comparison purposes, we also administered the Symbol-Digit Modalities Test (SDMT) and the Trail Making Test (TMT), measures which detect HIV-related mental slowing efficiently in gay men but are nonspecifically impaired in subjects with a history of substance abuse. As predicted, scores on the TMT and the SDMT did not discriminate the groups, but HIV-seropositive subjects had significantly shorter spatial spans (p < .007) and DRST total scores (p < .005). These effects could not be attributed to differences in age, education, estimated intelligence, or psychological distress, because the groups were well matched on these variables. The DRST is a promising measure of HIV-related cognitive dysfunction in substance abusers, who are often nonspecifically impaired on psychomotor tasks. These preliminary data also indicate that working memory function should be studied further in HIV-seropositive subjects.

Selective deficit of one language in a bilingual patient following surgery in the left perisylvian area

We report on a right-handed bilingual patient with a left perisylvian arteriovenous malformation that caused a mild naming deficit evident only on formal language testing in both languages. Sodium amytal injected in the left carotid artery (Wada test) before surgery resulted in speech arrest for both languages. Following surgery for removal of the lesion she developed additional deficits in her native language without alteration in her second language. Selective impairment in one language after surgery demonstrates that each language has different anatomical representation within the perisylvian dominant area.

Postoperative cognitive and single photon emission computed tomography assessment of patients with resection of perioperative high-risk arteriovenous malformations

We studied the outcome of 10 patients who had undergone high-risk surgery for an arteriovenous malformation at our institution between November 1991 and November 1993. All of the lesions were located in the dominant (left) hemisphere. Perioperative risk was assessed by the location of the lesion in functionally eloquent cortex (seven patients) or deep structures (two patients) or the lesion's large volume (two patients). Our patients included six women and four men, and their ages ranged from 22 to 53 years (mean, 35.8). Our follow-up study included the evaluation of neurological sequelae but mainly emphasized the study of cognitive deficits (seven major functional clusters), the incidence of depression and behavioral changes, and the assessment of regional cerebral blood flow with single photon emission computed tomography. Six patients returned to a seemingly "normal" daily life with some minor deficits postoperatively, three developed contralateral hemiparesis, and one had disabling cognitive deficits. Our comprehensive cognitive assessment, in particular, showed that although patients might appear "normal" on a routine neurological examination, most patients showed a mild deficit in at least one cognitive function and three were severely impaired. In addition, the single photon emission computed tomographic studies pointed out hypoperfusion in more extensive regions than the surgical defects shown by magnetic resonance imaging or computed tomographic studies. These single photon emission computed tomography images helped to explain some of the cognitive and behavioral changes better than the anatomic studies. This information will make it possible for the physician to offer continuing supportive care for the patient in postoperative transition to normal life activities.

Successful methylphenidate treatment of apathy after subcortical infarcts

A patient with prominent apathy secondary to multiple subcortical infarcts was treated successfully with methylphenidate. SPECT and reaction time testing showed selective improvement of frontal system function, consistent with a recent model of frontal-subcortical circuits and behavior.

Language-activated single-photon emission tomography imaging in the evaluation of language lateralization--evidence from a case of crossed aphasia: case report

We report a right-handed patient who developed a nonfluent aphasia after surgery for a right parietal arteriovenous malformation. Resting brain single-photon emission tomography displayed decreased regional cerebral blood flow only in the right hemisphere, with spared regional cerebral blood flow in the left hemisphere. Single-photon emission tomography performed after a language activation task (Boston Naming Task) showed a consistent area of increased regional cerebral blood flow in the right inferior and posterior frontal lobe, supporting a right hemisphere dominance for language. These results suggest a potential role for this noninvasive study in the evaluation of language lateralization.