Proteomic and phosphoproteomic profiling in heart failure with preserved ejection fraction (HFpEF)

Background

The lack of therapies for HFpEF patients is a major unmet need, thus identifying cardiac specific pathways in HFpEF is a priority.

Purpose

Identify molecular features of protein and phosphoprotein in a murine model of HFpEF

Methods

Studies followed the principles of laboratory animal care (NIH Pub no. 85–23 revised 1985). HFpEF (N=4) was induced by NaCl drinking water, unilateral nephrectomy, and chronic aldosterone infusion (SAUNA) or saline (Sham; N=4) for 4 wks. Mice were euthanized and LV tissue was collected. Samples were homogenized, proteins extracted and subjected to digestion followed by phosphopeptide enrichment for proteomics and phosphoproteomics profiling.

Results

HFpEF mice had moderate hypertension (137.8±7.0 vs. Sham; 115.4±6.0mmHg; P<0.05), lung congestion (4.5±0.1 vs. 4.0±0.1; P<0.01), and LVH (3.7±0.1 vs. 3.3±0.1mg/g; P<0.05). ECHO showed normal LVEF with evidence of diastolic dysfunction in HFpEF mice. Mitral E velocity was reduced (1347±154 vs. 1971±284mm/s; P<0.05) and IVRT increased (24.3±2.6 vs. 14.4±1.6ms; P<0.05) vs. Sham. Protein and protein phosphosites from the LV were quantified by mass spectrometry. Analysis of the proteomics datasets revealed marked changes in sarcomere proteins, such as skeletal alpha (α)-actin (ACTA1; P=0.000039), beta (β)-myosin heavy chain (MYH7; P=0.006963) and myosin heavy chain 9 (MYH9; P=0.000408); the mitochondria-related proteins mitofusin 1 (MFN1; P=0.001059), mitochondrial dynamin like GTPase (aka optic atrophy protein 1, OPA1; P=0.046441) and transcription factor A mitochondrial (TFAM; P=0.005837); and the NAD-dependent protein deacetylase sirtuin-3 (SIRT3; P=0.000914). There was also a reduction in proteins involved in the oxidation of free fatty acid, pyruvate, and ketone bodies in the LV from HFpEF vs. Sham. Phosphoproteomics analysis also showed aberrant protein phosphorylation patterns linked to disparate subcellular compartments, ranging from sarcomere proteins (LIM domain-binding protein 3, LDB3; myozenin 2, Myoz2; titin, TTN), to nuclear-localized proteins (BAG family molecular chaperone regulator 3, BAG3; high mobility group protein HMG-I/HMG-Y, HMGA1) with known links to contractile dysfunction, LVH and/or cardiomyopathy. Additional GSEA analysis revealed the most relevant and enriched biological annotations in LV from HFpEF, to be processes involving immune system modulation and muscle contraction. Downregulated pathways were mainly related to multitude of GO terms associated with mitochondrial metabolism.

Conclusion(s)

This study presents the systematic, quantitative proteomics and phosphoproteomic analysis of the LV from the SAUNA HFpEF mice. We observed profound changes in proteins related to mitochondrial metabolism and function and heart contractile dysfunction in HFpEF which may be mediated by Sirtuin 3. Additional studies are warranted to investigate the specific role of Sirtuin 3 in mitochondrial metabolism and heart contractile dysfunction in HFpEF.

Funding Acknowledgement

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): National Institute of Heath (NIH/ NHLBI)

Humanized mice reveal a macrophage-enriched gene signature defining human lung tissue protection during SARS-CoV-2 infection

The human immunological mechanisms defining the clinical outcome of SARS-CoV-2 infection remain elusive. This knowledge gap is mostly driven by the lack of appropriate experimental platforms recapitulating human immune responses in a controlled human lung environment. Here, we report a mouse model (i.e., HNFL mice) co-engrafted with human fetal lung xenografts (fLX) and a myeloid-enhanced human immune system to identify cellular and molecular correlates of lung protection during SARS-CoV-2 infection. Unlike mice solely engrafted with human fLX, HNFL mice are protected against infection, severe inflammation, and histopathological phenotypes. Lung tissue protection from infection and severe histopathology associates with macrophage infiltration and differentiation and the upregulation of a macrophage-enriched signature composed of 11 specific genes mainly associated with the type I interferon signaling pathway. Our work highlights the HNFL model as a transformative platform to investigate, in controlled experimental settings, human myeloid immune mechanisms governing lung tissue protection during SARS-CoV-2 infection.

SARS-CoV-2 Disrupts Proximal Elements in the JAK-STAT Pathway

SARS-CoV-2 can infect multiple organs, including lung, intestine, kidney, heart, liver, and brain. The molecular details of how the virus navigates through diverse cellular environments and establishes replication are poorly defined. Here, we generated a panel of phenotypically diverse, SARS-CoV-2-infectible human cell lines representing different body organs and performed longitudinal survey of cellular proteins and pathways broadly affected by the virus. This revealed universal inhibition of interferon signaling across cell types following SARS-CoV-2 infection. We performed systematic analyses of the JAK-STAT pathway in a broad range of cellular systems, including immortalized cells and primary-like cardiomyocytes, and found that SARS-CoV-2 targeted the proximal pathway components, including Janus kinase 1 (JAK1), tyrosine kinase 2 (Tyk2), and the interferon receptor subunit 1 (IFNAR1), resulting in cellular desensitization to type I IFN. Detailed mechanistic investigation of IFNAR1 showed that the protein underwent ubiquitination upon SARS-CoV-2 infection. Furthermore, chemical inhibition of JAK kinases enhanced infection of stem cell-derived cultures, indicating that the virus benefits from inhibiting the JAK-STAT pathway. These findings suggest that the suppression of interferon signaling is a mechanism widely used by the virus to evade antiviral innate immunity, and that targeting the viral mediators of immune evasion may help block virus replication in patients with COVID-19. IMPORTANCE SARS-CoV-2 can infect various organs in the human body, but the molecular interface between the virus and these organs remains unexplored. In this study, we generated a panel of highly infectible human cell lines originating from various body organs and employed these cells to identify cellular processes commonly or distinctly disrupted by SARS-CoV-2 in different cell types. One among the universally impaired processes was interferon signaling. Systematic analysis of this pathway in diverse culture systems showed that SARS-CoV-2 targets the proximal JAK-STAT pathway components, destabilizes the type I interferon receptor though ubiquitination, and consequently renders the infected cells resistant to type I interferon. These findings illuminate how SARS-CoV-2 can continue to propagate in different tissues even in the presence of a disseminated innate immune response.

SARS-CoV-2 desensitizes host cells to interferon through inhibition of the JAK-STAT pathway

SARS-CoV-2 can infect multiple organs, including lung, intestine, kidney, heart, liver, and brain. The molecular details of how the virus navigates through diverse cellular environments and establishes replication are poorly defined. Here, we performed global proteomic analysis of the virus-host interface in a newly established panel of phenotypically diverse, SARS-CoV-2-infectable human cell lines representing different body organs. This revealed universal inhibition of interferon signaling across cell types following SARS-CoV-2 infection. We performed systematic analyses of the JAK-STAT pathway in a broad range of cellular systems, including immortalized cell lines and primary-like cardiomyocytes, and found that several pathway components were targeted by SARS-CoV-2 leading to cellular desensitization to interferon. These findings indicate that the suppression of interferon signaling is a mechanism widely used by SARS-CoV-2 in diverse tissues to evade antiviral innate immunity, and that targeting the viral mediators of immune evasion may help block virus replication in patients with COVID-19.

Treatment of chronic migraine with transcutaneous stimulation of the auricular branch of the vagal nerve (auricular t-VNS): a randomized, monocentric clinical trial

Background

Aim of the study was assessment of efficacy and safety of transcutaneous stimulation of the auricular branch of the vagal nerve (t-VNS) in the treatment of chronic migraine.

Methods

A monocentric, randomized, controlled, double-blind study was conducted. After one month of baseline, chronic migraine patients were randomized to receive 25 Hz or 1 Hz stimulation of the sensory vagal area at the left ear by a handhold battery driven stimulator for 4 h/day during 3 months. Headache days per 28 days were compared between baseline and the last month of treatment and the number of days with acute medication was recorded The Headache Impact Test (HIT-6) and the Migraine Disability Assessment (MIDAS) questionnaires were used to assess headache-related disability.

Results

Of 46 randomized patients, 40 finished the study (per protocol). In the per protocol analysis, patients in the 1 Hz group had a significantly larger reduction in headache days per 28 days than patients in the 25 Hz group (−7.0 ± 4.6 vs. −3.3 ± 5.4 days, p = 0.035). 29.4 % of the patients in the 1 Hz group had a ≥50 % reduction in headache days vs. 13.3 % in the 25 Hz group. HIT-6 and MIDAS scores were significantly improved in both groups, without group differences. There were no serious treatment-related adverse events.

Conclusion

Treatment of chronic migraine by t-VNS at 1 Hz was safe and effective. The mean reduction of headache days after 12 weeks of treatment exceeded that reported for other nerve stimulating procedures.

[Consistency and Reliability of MDK Expertise Examining the Encoding in the German DRG System]

INTRODUCTION

Hospital inpatient stays are reimbursed on the basis of German diagnosis-related groups (G-DRG). The G-DRG classification system is based on complex coding guidelines. The Medical Review Board of the Statutory Health Insurance Funds (MDK) examines the encoding by hospitals and delivers individual expertises on behalf of the German statutory health insurance companies in cases in which irregularities are suspected. A study was conducted on the inter-rater reliability of the MDK expertises regarding the scope of the assessment.

METHODS

A representative sample of 212 MDK expertises was taken from a selected pool of 1 392 MDK expertises in May 2013. This representative sample underwent a double-examination by 2 independent MDK experts using a special software based on the 3MTM G-DRG Grouper 2013 of 3M Medica, Germany. The following items encoded by the hospitals were examined: DRG, principal diagnosis, secondary diagnoses, procedures and additional payments. It was analysed whether the results of MDK expertises were consistent, reliable and correct.

RESULTS

202 expertises were eligible for evaluation, containing a total of 254 questions regarding one or more of the 5 items encoded by hospitals. The double-examination by 2 independent MDK experts showed matching results in 187 questions (73.6%) meaning they had been examined consistently and correctly. 59 questions (23.2%) did not show matching results, nevertheless they had been examined correctly regarding the scope of the assessment. None of the principal diagnoses was significantly affected by inconsistent or wrong judgment.

CONCLUSION

A representative sample of MDK expertises examining the DRG encoding by hospitals showed a very high percentage of correct examination by the MDK experts. Identical MDK expertises cannot be achieved in all cases due to the scope of the assessment. Further improvement and simplification of codes and coding guidelines are required to reduce the scope of assessment with regard to correct DRG encoding and its examination.

Headache cessation by an educational intervention in grammar schools: a cluster randomized trial

BACKGROUND AND PURPOSE

Headache is a common health problem in adolescents. There are a number of risk factors for headache in adolescents that are amenable to intervention. The aim of the study was to assess the effectiveness of a low-level headache prevention programme in the classroom setting to prevent these risk factors.

METHODS

In all, 1674 students in 8th-10th grade at 12 grammar schools in greater Munich, Germany, were cluster randomized into intervention and control groups. A standardized 60-min prevention lesson focusing on preventable risk factors for headache (physical inactivity, coffee consumption, alcohol consumption and smoking) and providing instructions on stress management and neck and shoulder muscle relaxation exercises was given in a classroom setting. Seven months later, students were reassessed. The main outcome parameter was headache cessation. Logistic regression models with random effects for cluster and adjustment for baseline risk factors were calculated.

RESULTS

Nine hundred students (intervention group N = 450, control group N = 450) with headache at baseline and complete data for headache and confounders were included in the analysis. Headache cessation was observed in 9.78% of the control group compared with 16.22% in the intervention group (number needed to treat = 16). Accounting for cluster effects and confounders, the probability of headache cessation in the intervention group was 1.77 (95% confidence interval = [1.08; 2.90]) higher than in the control group. The effect was most pronounced in adolescents with tension-type headache: odds ratio = 2.11 (95% confidence interval = [1.15; 3.80]).

CONCLUSION

Our study demonstrates the effectiveness of a one-time, classroom-based headache prevention programme.

Abstract P5-01-07: Select neutrophils inhibit breast cancer metastases in patients via chemokine-mediated mechanisms

Background: In both breast cancer patients and healthy women, we have previously demonstrated that select neutrophils found in breast cancer patients as opposed to healthy women are cytotoxic to breast cancer cell lines. (Granot Z et al. Cancer Cell. 2010) This work stemmed from our prior research in murine breast cancer models indicating that primary breast tumors can mobilize select neutrophils, termed Tumor Entrained Neutrophils (“TENS”); these entrained neutrophils have the unique capacity to inhibit metastatic seeding in the lung through cell-kill mechanisms. (Granot Z et al. Cancer Cell. 2010) In this study, we evaluated the relationship between select chemokines and neutrophil cytotoxicity in breast cancer patients versus healthy volunteers.

Methods: Neutrophils were purified from the blood of 75 randomly selected newly diagnosed pre-operative breast cancer patients without evidence of metastatic disease, and 47 healthy female volunteers with no history of cancer. Cytotoxicity was evaluated by incubating neutrophils with luciferase labeled MDA-MB-231 cells. Luciferase activity was measured as a reflection of% cytotoxicity. Serum was also isolated from breast cancer patients and healthy volunteers. Based on prior experiments, we used the Millipore® Milliplex Human Cytokine Plex Kit to evaluate Il-1Ra, MCP-1 and TNFa in our serum samples in 50/75 of the cancer patients and 25/47 controls. We used multiple linear regression to develop a model to predict cytotoxicity as a function of the chemokines.

Results: In comparison to healthy volunteers whose mean neutrophil cytotoxicity to MDA-MB-231 cells was 6.5%, pre-operative breast cancer patients demonstrated a mean neutrophil cytotoxicity of 12.7%, p<0.0001. We then evaluated the serum chemokine levels of 50 of the breast cancer patients; 31/50 had high neutrophil cytotoxicity (>10%), and 19/50 had low neutrophil cytotoxicity (<10%). We compared the serum chemokine levels in the patients to the levels found in the 25 controls. Using a multiple linear regression model, we found that the levels of these three chemokines are associated with cytotoxicity (R2 = 0.126, p = 0.022). An ANOVA decomposition of the model suggested that Il.1RA was the most predictive (p = 0.018) followed by MCP.1 (p = 0.088) and TNF.alpha (p = 0.245).

Conclusion: Our work demonstrates the cytotoxic role of select neutrophils in the peripheral blood of breast cancer patients as contrasted with neutrophils from healthy women. We further demonstrate that select chemokines appear to be correlated with neutrophil cytotoxicity. We are currently evaluating the prognostic and therapeutic roles of cytotoxic neutrophils and their related chemokines in breast cancer patients.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-01-07.

An intrinsic circadian clock of the pancreas is required for normal insulin release and glucose homeostasis in mice

AIMS/HYPOTHESIS

Loss of circadian clocks from all tissues causes defective glucose homeostasis as well as loss of feeding and activity rhythms. Little is known about peripheral tissue clocks, so we tested the hypothesis that an intrinsic circadian clock of the pancreas is important for glucose homeostasis.

METHODS

We monitored real-time bioluminescence of pancreas explants from circadian reporter mice and examined clock gene expression in beta cells by immunohistochemistry and in situ hybridisation. We generated mice selectively lacking the essential clock gene Bmal1 (also known as Arntl) in the pancreas and tested mutant mice and littermate controls for glucose and insulin tolerance, insulin production and behaviour. We examined islets isolated from mutants and littermate controls for glucose-stimulated insulin secretion and total insulin content.

RESULTS

Pancreas explants exhibited robust circadian rhythms. Clock genes Bmal1 and Per1 were expressed in beta cells. Despite normal activity and feeding behaviour, mutant mice lacking clock function in the pancreas had severe glucose intolerance and defective insulin production; their isolated pancreatic islets had defective glucose-stimulated insulin secretion, but normal total insulin content.

CONCLUSIONS/INTERPRETATION

The mouse pancreas has an autonomous clock function and beta cells are very likely to be one of the pancreatic cell types possessing an intrinsic clock. The Bmal1 circadian clock gene is required in the pancreas, probably in beta cells, for normal insulin secretion and glucose homeostasis. Our results provide evidence for a previously unrecognised molecular regulator of pancreatic glucose-sensing and/or insulin secretion.

Efficient haemodialysis despite complete central venous thrombosis

Two cases with a fully functional haemodialysis access, in spite of complete thrombotic occlusion of the ipsilateral subclavian and/or brachiocephalic vein are reported. The coincidentally detected complete venous occlusions may indicate that occult venous stenosis or thrombosis is more frequent than generally assumed. In order to avoid deterioration of the haemodynamic situation interventions may be withheld unless clinical problems related to a diminished outflow occur.

A Continuation Method for Nash Equilibria in Structured Games

Structured game representations have recently attracted interest as models for multi-agent artificial intelligence scenarios, with rational behavior most commonly characterized by Nash equilibria. This paper presents efficient, exact algorithms for computing Nash equilibria in structured game representations, including both graphical games and multi-agent influence diagrams (MAIDs). The algorithms are derived from a continuation method for normal-form and extensive-form games due to Govindan and Wilson; they follow a trajectory through a space of perturbed games and their equilibria, exploiting game structure through fast computation of the Jacobian of the payoff function. They are theoretically guaranteed to find at least one equilibrium of the game, and may find more. Our approach provides the first efficient algorithm for computing exact equilibria in graphical games with arbitrary topology, and the first algorithm to exploit fine-grained structural properties of MAIDs. Experimental results are presented demonstrating the effectiveness of the algorithms and comparing them to predecessors. The running time of the graphical game algorithm is similar to, and often better than, the running time of previous approximate algorithms. The algorithm for MAIDs can effectively solve games that are much larger than those solvable by previous methods.

Unusual cause of intermittent claudication

Spontaneous dissection of a peripheral artery is a rare event. We report a case of a spontaneous, non-atherosclerotic and non-aneurysmal dissection limited to the external iliac artery in a 60-year-old woman who was admitted with a left calf claudication. Non-invasive examination documented signs of leg ischemia due to a floating wall dissection of the external iliac artery. After medical treatment over eight weeks the dissection membrane had been adapted to the vessel wall. A similar case of a spontaneous dissection limited to the external iliac artery, followed by a spontaneous healing has not been reported in the literature.

Anemia in chronic kidney disease and congestive heart failure

Anemia is seen in chronic kidney insufficiency (CKI), dialysis patients, congestive heart failure (CHF), and renal transplantation. Anemia can lead to progressive cardiac damage as well as progressive renal damage. It is not generally appreciated that CHF itself may be a very common contributor to both the production of anemia as well as to the progression of the renal failure. Correction of the anemia with erythropoietin and, as necessary, intravenous iron, may prevent the deterioration of both the heart and the kidneys. We suggest that there is a triangular relationship, a vicious circle, between CHF, CKI and anemia where each of these three can both cause and be caused by the other. We call this syndrome the cardio-renal anemia (CRA) syndrome. All physicians, especially cardiologists and internists who treat CKI and CHF, should be made aware of the dangers of anemia in CKI and CHF and should work with nephrologists to correct it.

The functional relationship of monkey infra parietal cortex (IPL) to behavior in the extrapersonal space

Lesions of the posterior parietal system in humans and of the presumably homologous area 7 of the monkey cause impairment in high-order manipulative behavior. A specific "misreaching" observed prompted the outlook of dysfunction constrained to the perceptual, the comand/motor aspects excluded. To clarify the nature of normal functioning in this domain, a study was done by microelectrode recording from area 7 of the monkey of neural firing in relation to hand reaching to targets. The data obtained show that an area 7 neuron fires in relation to simple stimuli, such as a square of white light, and to composite stimuli, such as hand reaching by the monkey or by the trainer in the monkey's extrapersonal space, the response to complex stimuli characteristically multiduty. The firing patterns were presumably relatable to encoding of stimulus components with superposed situation variance. Selectivity of the stimulus was maintained along specific invariance, such as to hand used, to direction of outgoing reaching, to direction from which the rewarding hand of the trainer reached. It is proposed that functional linkage of cognate features, a consequent modular category encoding and "packaging" of information relevant for praxis schema, is thus achieved by area 7 cells specialized for integrating information in the time and space domains visual, tactile, proprioceptive/kinaesthetic, and other for the sake of behavior in extrapersonal space. Generalization without jeopardizing of differentiating is presumably enabled through the multiduty cell entity.

Coherence in localized visual evoked potentials (VEPs) to spatial stimulus attributes (orientation and displacement) in man

The purpose of this study was to compare visual evoked potentials (VEPs) of striate-peristriate and Cz to posterior parietal, especially IPL's supramarginal (Su) and angular (Ang, Ano, and Ant) leads in response to human face spatial attributes attend-task, to assess the concern of the former with basic features versus the latter's spatial attributes "rotated" rightwards, leftwards, or oblique (unusual angle of sight) or nodal one (eye)- and two-item, eye/mouth displacement. Monopolar cranially derived VEPs were recorded bihemispherically from six adults using 12 electrode arrays 1.5 to 2 cm apart. Subjects were instructed to fixate a marking on the monitor at a nodal eyebrow region, while attending the stimulus that was computer displayed for 200 or 300 ms, and followed by mask. Analysis was made on the first 240 ms of the records after stimulus onset; the test was compared to "full face," the hypothesized control. Localized VEP changes were observed task-bound and bihemispherically coherent in parietal leads, especially Ang, Ano, and Su. The early negativity of the "full face" control was replaced by an early positive wave with onset latencies of 70 +/- 15 ms, significantly shorter (p < 0.01) than the striate's 90 +/- 20 ms. The changes were observed for both rotation and displacement. The changes in the angular leads (Ano and Ang) are consistent with the encoding of spatial attributes of orientation and nodal face items displacement. Differentiation of direction and degree of rotation, "seen from above" versus "seen from below," largely encoded by the right Su. The composite double-item eye and displaced or obliquely rotated induced extended coherent activity in parietal leads. Oz, peristriate, and Cz showed no such changes. No attempt is made to imply source localization; we claim parietal localized and coherency of the VEP changes suggest high-order early processing of human face attributes. This occurs by a relatively fast pathway. The "triggers" for the changes are direction and degree of rotation or of displacement rather than actual geometry of the stimulus.

Antimycin A resistance in a mutant Leishmania tarentolae strain is correlated to a point mutation in the mitochondrial apocytochrome b gene

In this paper we report the first case of antimycin A resistance in a protozoan parasite that is attributable to a mutation in the mitochondrial apocytochrome b (CYb) gene. We selected for, and isolated, a mutant Leishmania tarentolae strain that is resistant to antimycin A. This resistance was evident at the levels of the in vitro growth and enzymatic activity of the cytochrome bc1 complex. Molecular characterisation of the mutant revealed a Ser35Ile mutation in the expected region of the CYb gene. In kinetoplastids, CYb and other structural genes of the mitochondrial genome are located on the maxicircle component of the mitochondrial DNA, which is present in 20-50 copies. Primer-extension analysis confirmed the presence of the mutation at the mRNA level. The phenotypic manifestation of the mutation implies that the CYb mRNA is edited and translated within the mitochondrion. Thus, this finding provides direct evidence that edited RNAs are translated in kinetoplastid mitochondria. Furthermore, a defined mutation conferring drug resistance to a mitochondrial gene product can be exploited for the development of mitochondrial transfection systems for trypanosomatids.

The use of transgenic Trypanosoma brucei to identify compounds inducing the differentiation of bloodstream forms to procyclic forms

The expression of procyclins is the earliest known marker of differentiation of bloodstream forms of Trypanosoma brucei to procyclic forms. We have generated transgenic bloodstream and procyclic forms in which the coding region of one procyclin gene was replaced by E. coli beta-glucuronidase (GUS). GUS activity can be monitored in a simple one-step colour reaction in microtitre plates; this assay is potentially suitable for large-scale screening for compounds that influence differentiation. GUS was stage-specifically expressed in procyclic forms and its synthesis occurred in parallel with that of procyclin when bloodstream forms were triggered to differentiate by the addition of cis-aconitate. GUS could also be induced by brief treatment with the proteases trypsin, pronase or thermolysin, but not with pepsin or thrombin. Interestingly, a combination of one of the active proteases with cis-aconitate resulted in increased GUS activity relative to either trigger alone. In contrast to cis-aconitate, protease treatment resulted in considerable cell death. Experiments with the pleomorphic strain AnTat 1.1 showed that long slender bloodstream forms were rapidly killed by proteases, whereas stumpy forms were largely resistant. Stumpy forms treated with trypsin differentiated synchronously and expressed procyclin with faster kinetics than when they were triggered by cis-aconitate. As predicted by the GUS assay, differentiation was even more rapid when both inducers were used simultaneously, with all cells expressing maximal levels of procyclin within 3 h.

Evaluation of laser doppler flowmetry for the study of benign and malignant gastric blood flow in vivo

BACKGROUND

Tumour vascularisation is a determinant of the development of metastases.

AIMS

To measure blood flow in normal stomach and gastric adenocarcinomas by laser Doppler flowmetry and correlate blood flow with vascularisation after immunohistochemical staining of resected specimens for CD31 and von Willebrand factor.

PATIENTS

Twenty two undergoing resection for gastric adenocarcinoma and 10 undergoing cholecystectomy.

RESULTS

Mean (SD) gastric blood flow was 208 (35) perfusion units (PU) in patients undergoing cholecystectomy and 190 (75) PU in the undiseased part of the stomach in patients with gastric adenocarcinoma. Gastric blood flow was higher in the border of gastric adenocarcinomas (322 (120) PU, p<0.01 v normal stomach) but lower in the centre (74 (27) PU, p<0.01 v normal stomach and tumour border). Blood flow was higher in tumours staged T>/=3 than in those staged T<3. Blood vessel density in normal stomach was 41 (8) stained cells/field viewed and was 1. 9-3.4 times higher in gastric adenocarcinomas.

CONCLUSION

Laser Doppler flowmetry is a valuable tool for studying the pathophysiological alterations of malignant blood flow in the human stomach in vivo.

In vivo import of unspliced tRNATyr containing synthetic introns of variable length into mitochondria of Leishmania tarentolae

The mitochondrial genomes of trypanosomatids lack tRNA genes. Instead, mitochondrial tRNAs are encoded and synthesized in the nucleus and are then imported into mitochondria. This also applies for tRNATyr, which in trypanosomatids contains an 11 nt intron. Previous work has defined an exon mutation which leads to accumulation of unspliced precursor tRNATyr. In this study we have used the splicing-deficient tRNATyr as a vehicle to introduce foreign sequences into the mitochondrion of Leishmania tarentolae. The naturally occurring intron was replaced by synthetic sequences of increasing length and the resulting tRNATyr precursors were expressed in transgenic cell lines. Whereas stable expression of precursor tRNAsTyr was obtained for introns up to a length of 76 nt, only precursors having introns up to 38 nt were imported into mitochondria. These results demonstrate that splicing-deficient tRNATyr can be used to introduce short synthetic sequences into mitochondria in vivo. In addition, our results show that one factor which limits the efficiency of import is the length of the molecule.

Suicide by cop

STUDY OBJECTIVE

"Suicide by cop" is a term used by law enforcement officers to describe an incident in which a suicidal individual intentionally engages in life-threatening and criminal behavior with a lethal weapon or what appears to be a lethal weapon toward law enforcement officers or civilians to specifically provoke officers to shoot the suicidal individual in self-defense or to protect civilians. The objective of this study was to investigate the phenomenon that some individuals attempt or commit suicide by intentionally provoking law enforcement officers to shoot them.

METHODS

We reviewed all files of officer-involved shootings investigated by the Los Angeles County Sheriff's Department from 1987 to 1997. Cases met the following criteria: (1) evidence of the individual's suicidal intent, (2) evidence they specifically wanted officers to shoot them, (3) evidence they possessed a lethal weapon or what appeared to be a lethal weapon, and (4) evidence they intentionally escalated the encounter and provoked officers to shoot them.

RESULTS

Suicide by cop accounted for 11% (n=46) of all officer-involved shootings and 13% of all officer-involved justifiable homicides. Ages of suicidal individuals ranged from 18 to 54 years; 98% were male. Forty-eight percent of weapons possessed by suicidal individuals were firearms, 17% replica firearms. The median time from arrival of officers at the scene to the time of the shooting was 15 minutes with 70% of shootings occurring within 30 minutes of arrival of officers. Thirty-nine percent of cases involved domestic violence. Fifty-four percent of suicidal individuals sustained fatal gunshot wounds. All deaths were classified by the coroner as homicides, as opposed to suicides.

CONCLUSION

Suicide by cop is an actual form of suicide. The most appropriate term for this phenomenon is law enforcement-forced-assisted suicide. Law enforcement agencies may be able to develop strategies for early recognition and handling of law enforcement-forced-assisted suicide (suicide by cop). Health care providers involved in the evaluation of potentially suicidal individuals and in the resuscitation of officer-involved shootings should be aware of law enforcement-forced-assisted suicide as a form of suicide.

PET with 18fluorodeoxyglucose and hexamethylpropylene amine oxime SPECT in late whiplash syndrome

BACKGROUND

Many patients have cognitive abnormalities and psychological problems after whiplash injury to the cervical spine. To our knowledge, neuroradiologic imaging has not depicted brain damage that explains the symptoms. Parietotemporo-occipital perfusion deficits on hexamethylpropylene amine oxime (HMPAO) SPECT studies have been described among patients who have sustained whiplash injury.

METHODS

We examined 13 patients with typical late whiplash syndrome (study group) using HMPAO SPECT, 18fluorodeoxyglucose (FDG) PET, and MRI of the brain and compared the findings with those for 16 control subjects who underwent FDG PET.

RESULTS

In the study group, statistical parametric mapping revealed significantly decreased FDG uptake in the frontopolar and lateral temporal cortex and in the putamen. The frontopolar hypometabolism correlated significantly with scores of the Beck Depression Inventory. However, in individual cases, reliability in the depiction of hypometabolic areas was relatively low. No alterations were found in the parietotemporo-occipital area. In these areas, decreased uptake of HMPAO and FDG correlated with cortical mass.

CONCLUSION

FDG PET did not allow reliable diagnosis of metabolic disturbances for individual patients. Therefore, we do not recommend FDG PET or HMPAO SPECT as a diagnostic tool in routine examinations of patients with late whiplash syndrome.

Theophylline and warfarin interaction studies with grepafloxacin

Two phase I trials, each involving 16 healthy adult volunteers, were performed to investigate possible interactions between grepafloxacin and theophylline or warfarin. In the theophylline study, grepafloxacin 600 mg was administered once daily for 10 days to 12 volunteers who were receiving a maintenance dose of theophylline. This dose of theophylline was designed to produce mean serum theophylline concentrations of 7.5 mg/L; 4 volunteers received theophylline plus placebo. Pharmacokinetic parameters of theophylline were determined before grepafloxacin treatment and on day 10 of grepafloxacin or placebo administration. Peak theophylline concentrations and the area under the concentration-time curve increased significantly during grepafloxacin treatment, and apparent total clearance of theophylline was reduced by approximately 50%. No changes were observed in the placebo group and theophylline appeared to have no effect on the pharmacokinetics of grepafloxacin. In the warfarin study, grepafloxacin 600 mg was given once daily for 14 days to volunteers receiving a maintenance dose of warfarin. Warfarin was discontinued during the last 4 days of grepafloxacin administration. The pharmacodynamics of warfarin did not change after administration of grepafloxacin. Similarly, warfarin had no significant effect on the pharmacokinetics of grepafloxacin. We conclude that during treatment with grepafloxacin maintenance, doses of theophylline should be reduced by 50%, and we recommend that serum concentrations of theophylline be monitored during treatment with grepafloxacin. However, no dose adjustment is necessary for grepafloxacin when it is coadministered with theophylline, and dose adjustment does not seem to be required in concomitant treatment with grepafloxacin and warfarin.

Psychophysiological Basis for Errors in Identification of Degraded Geometric Forms under Conditions of High Information Uncertainty

Identification of ambiguous geometric forms by human subjects with brief experience or pre-knowledge of the stimulus may call upon Bayesian specialised mechanisms. Subjects were presented with a 2-alternative forced choice between a pair of incomplete geometric figures in conditions with common and varying components. Stimuli of 1, 3, 5, and 6 pixel acuity grades were displayed in iterative order in randomised blocks at 100, 200, 260, and 360 ms exposure times, rotated or upright, under local or global viewing. Analysis of probability of correct identification against stimulus intensity, acuity demand, and stimulus duration revealed: (i) sigmoid or dipper-shaped nonmonotonic psychometric functions; (ii) Poisson-like skewed binomial distributions of errors; and (iii) category-based dependence on the stimulus and its ambiguity. This is attributable to the high uncertainty constraints imposed on tasks sharing and also varying in their stimulus parameters and dimensions. Nonlinearities shown reflect category-based strategies and attention allocation, interactions as a drive for performance stability manifested in equalisation across sub-categories and invariances of errors, with acuity demand accounted for perhaps by mechanisms of differential attention allocation. Two sources of error are apparent: (i) possibly ‘bottleneck of attention’-related and individually varying ‘blink of attention’, with small falls distributed across stimulus intensities, and (ii) ‘lapse of attention’ with large falls on easier tasks, and rightward-skewed deviations from normal Poisson-like binomial distributions ( p<0.001), the high correlation to performance effort suggesting an active process of pay-off.

The Pseudomonas aeruginosa outer membrane protein I vaccine: immunogenicity and safe administration in man

After expression in Escherichia coli and purification by Ni++ chelate-affinity chromatography, the outer membrane protein I (OprI) of Pseudomonas aeruginosa was tested in experimental animals for its safety and pyrogenicity. Four groups of 7 adult human volunteers were then vaccinated 3 times at four-weekly intervals with either 500 micrograms, 200 micrograms, 50 micrograms or 20 micrograms of OprI adsorbed onto aluminum hydroxide. The vaccinations were well tolerated and without systemic side effects, but a significant rise of antibody titers against OprI was measured in the serum of those who had received the 500 micrograms, 200 micrograms or 50 micrograms doses. Raised antibody titers against OprI were still present 30 weeks after the final vaccination. It was possible to demonstrate binding of the complement component C1q to the elicited antibodies, and this confirms their ability to promote antibody-mediated complement-dependent opsonization.

Safety and immunogenicity of a Pseudomonas aeruginosa outer membrane protein I vaccine in human volunteers

The outer membrane protein I (OprI) of Pseudomonas aeruginosa was expressed in Escherichia coli and purified by Ni2+ chelate-affinity chromatography. After safety and pyrogenicity evaluation in animals, four groups of seven adult human volunteers were vaccinated three times at four week intervals with either 500 micrograms, 200 micrograms, 50 micrograms or 20 micrograms of OprI adsorbed onto Al(OH)3. All vaccinations were well tolerated and no systemic side effects were detected. A significant rise of antibody titers against OprI could be measured in the serum of all volunteers who had received the 500 micrograms, 200 micrograms or 50 micrograms doses. Elevated antibody titers against OprI could still be measured 30 weeks after the final vaccination. Binding of the complement component C1q to the elicited antibodies could be demonstrated, showing the ability of the latter to promote antibody-mediated complement-dependent opsonization.

Are Special Mechanisms Chosen in Short Experience-Based Identification of Degraded Geometric Forms?

Perceptual performance schema are consistently prepared by human beings. Minimal ‘experience’ with pertinent stimulus attributes seem necessary. We presume that with new stimuli, a ‘linkage’ is formed with inner representations on the basis of commonly shared stimulus components. To investigate this hypothesis, we used ‘confusion stimuli’, ie degradations of five-corner and six-corner stars. These were presented within each of four paradigms: upright (u), rotated (10°; r), foveal/local viewing (A) or eccentric/global viewing (B), that is uA, uB, rA, and rB paradigms. Random presentation of stimuli prototypes preceded the stimulus so that in comparing the presented stimulus to one and the other prototype, the subject faced a 2AFC task. Series (4 to 6) each of 32 randomised paradigms were run on each of six subjects. The subjects keyed 5 or 6 on identifying one or the other stimulus. On the assumption that exposure time and/or acuity grades impose stimulus intensities, psychometric curves were derived by plotting probability of correct choice against either parameter. The results indicate that in hybrid paradigms such as the present uA and uB, or rA and rB subjects may use shared component strategy: ‘u strategy’ with uA and uB, ‘r strategy’ with rA and rB, shared A and B in generating viewpoint invariance. Similar log-linear psychometric curves and slopes for pairs of paradigms were obtained, and ‘transfer’ of learning presumably also based on shared stimulus properties was observed.

TH1 cells trigger tumor necrosis factor alpha-mediated hypersensitivity to Pseudomonas aeruginosa after adoptive transfer into SCID mice

Recent experiments have shown that gamma interferon (IFN-gamma), either administered or induced in vivo, e.g., by certain bacteria, is a key mediator in inducing hypersensitivity to bacterial lipopolysaccharides. The source of endogenous IFN-gamma in this context (natural killer versus TH1 cells) has not been investigated yet. In order to investigate the role of antigen-specific, IFN-gamma-producing TH1 cells in murine Pseudomonas aeruginosa infection, a murine TH1 cell line was propagated in vitro by using recombinant P. aeruginosa outer membrane protein I. Adoptive transfer experiments were performed by intravenous injection of various amounts of TH1 cells into P. aeruginosa-challenged SCID mice. Adoptive transfer of 5 x 10(6) T cells into SCID mice followed by an intraperitoneal challenge with 1.4 x 10(6) CFU of live P. aeruginosa resulted in the rapid death of the animals within 12 h postchallenge, whereas transfer of lower T-cell doses and saline as a control did not cause any detrimental effects. After challenge with 2.8 x 10(6) CFU of P. aeruginosa, similar results were obtained 18 h postchallenge; however, at the end of the 72-h observation period, no significant differences in survival rates were obtained between the groups treated with different amounts of T cells. The rapid death of mice treated with 5 x 10(6) T cells was reflected by 860-fold-elevated levels of tumor necrosis factor alpha (TNF-alpha) present in serum 2 h postchallenge, whereas no significant differences in TNF-alpha serum levels were detectable in mice treated with lower doses of T cells or with saline. Pretreatment of T-cell-reconstituted SCID mice with neutralizing anti-IFN-gamma monoclonal antibodies completely protected mice from bacterial challenge and reduced TNF-alpha levels in serum. We conclude that under the experimental conditions described here, IFN-gamma- and interleukin-2-producing TH1 cells represent an important trigger mechanism inducing TNF-alpha-mediated hypersensitivity to bacterial endotoxin.

Responses to colour of neurones in area 7a of the inferior parietal lobule of the rhesus monkey

A single-unit study on area 7a of alert, fixating rhesus monkeys revealed responsiveness to primary colours comparable to white light responsiveness shown in other cells. Mostly decremented, some biphasic, and a small portion with incremented neuronal firing response were observed, following stimulation of cells by parafoveal receptive field, rectangular, approximately 20 degrees x 20 degrees red, green or blue-violet light stimuli. The same cell showed no response to white light. Receptive fields of these colour-sensitive cells, like those of white-sensitive cells, were mostly contralateral, some ipsilateral and a few in both hemifields. Augmentation of responses following preconditioning electrical stimulation of lateroposterior-pulvinar targets was observed as with the white-light sensitive cells. It is noteworthy that this monkey area 7a colour sensitivity is complementary to previously demonstrated white light sensitivity. The specific properties revealed by these cells suggest separate channels within area 7a for colour and for achromatic light, the colour sensitivity possibly relevant when chromaticity is of generalized import, and these may subserve the animal's orienting response to colour appearance in the near-periphery visual field.

Outer membrane proteins of Pseudomonas aeruginosa as vaccine candidates

We tested the ability of recombinant outer membrane proteins of Pseudomonas aeruginosa to serve as a protective vaccine against this gram negative pathogen under two main pathophysiological events leading to P. aeruginosa sepsis. i) systemic infection during immunosuppression, and ii) bacterial translocation. A hybrid vaccine was cloned combining protective epitopes of outer membrane protein F (OprF) and outer membrane protein I (OprI). This vaccine proved to be highly protective against an intraperitoneal challenge with P. aeruginosa in immunosuppressed mice. Oral immunization of mice, with recombinant Salmonella dublin expressing OprI induced s-IgA antibodies in the gut mucosa against OprI and provided protection against translocation of P. aeruginosa in an immunosuppressed mouse model. To test whether OprI is safe for use in humans, recombinant OprI was purified and used for immunization of volunteers. Vaccination was well tolerated and no major side effects were observed. The induction of serum antibodies against OprI was found to be dose-dependent and was observed in total in 65% of the volunteers.

Protection of immunosuppressed mice against translocation of Pseudomonas aeruginosa from the gut by oral immunization with recombinant Pseudomonas aeruginosa outer membrane protein I expressing Salmonella dublin

AroA Salmonella dublin was used as recipient for a plasmid coding for the outer membrane protein I (OprI) of Pseudomonas aeruginosa. Oral immunization of Balb/c mice with recombinant S. dublin induced serum IgG and IgA antibodies against P. aeruginosa. In spleen and Peyer's patches anti-P. aeruginosa IgG- and IgA-secreting cells could be measured by the ELISPOT technique. In an oral challenge of immunosuppressed mice with P. aeruginosa the orally immunized animals had a 58-fold higher LD50 than control animals.

Organ-localized hypothalamic-stimulated vasculature changes in the cat

Stimulation of specific lateral hypothalamic targets in a cat model induces vascular and/or cardiac changes. Evidence is presented that these may consist of discretely localized sympathetically mediated changes taking place in just one or two organs. Moreover, following stimulation of either one of two adjacent lateral hypothalamus sites, pressor effects are induced that superficially look similar, but prove to be mediated by different pathways. To investigate possible synapsing at sympathetic ganglia, e.g. in superior cervical or stellate ganglia, 50 micrograms atropine methyl nitrate, a ganglionic blocker, was applied directly to the ganglia. This was shown to potentiate the pressor effects, in some cases when applied to the superior cervical ganglia, in others to stellate ganglia, presumably by blockade of a ganglionic attenuating mechanism. The contributions made by different sympathetic nerves to the lateral hypothalamus-induced pressor effect were analysed. Stimulation of one of the lateral hypothalamus sites (TAR.I) in eight cats induced a pressor effect that was abolished by severing a nerve branch, from the superior cervical ganglia laterally, shown to innervate neck muscle vasculature. In another group of nine cats stimulation of TAR.II induced a pressor effect abolished by cutting a branch from the superior cervical ganglia medially, shown to be destined to the vasculature of pharyngeal muscles and possibly lower respiratory tract. The hypothesis that central control via the sympathetic nervous system is responsible for differential organ specific regulation of blood flow to individual organs is discussed.

A motor-driven miniature multiple microelectrode manipulator for recording from the cortical neuropile of the awake monkey in operant behavior paradigms

An improved version of the Blum and Feldman multiple microelectrode manipulator is described. The main innovation is a design based on miniaturization and light weight (75 g), which allows head mounting with minimal disturbance to the animal in awake monkey operant behavior studies. The major features of the previously described model are preserved: simultaneous independent manipulation of four microelectrodes, in order to record from at least four single units, that may be crosscorrelated. With the new design better adjustment of intermicroelectrode distances for studies of interneural distances of 300 microns to 7 mm, and an easier automatic, computer-controlled monitoring of distances transversed into the brain are possible.

Formation of guide RNA/messenger RNA chimeric molecules in vitro, the initial step of RNA editing, is dependent on an anchor sequence

Synthetic pre-edited messenger RNA (mRNA) and guide RNA (gRNA) for the 5'-edited maxicircle-encoded ND7 cryptogene from Leishmania tarentolae formed chimeric molecules upon incubation in the presence of a mitochondrial extract. These chimeric molecules consisted of the gRNAs covalently linked to the mRNAs by short oligo(U) tails at normal editing sites in most cases. Unlike the previously reported chimeras present in steady-state kinetoplast RNA, the in vitro-synthesized chimeras showed no editing of downstream editing sites. The synthesis of chimeric RNAs required ATP and was dependent on the formation of a gRNA/mRNA anchor duplex 3' of the pre-edited region, as shown by in vitro mutagenesis of the mRNA and the gRNA. mRNA sequences 3' and 5' of the pre-edited region also affected the efficiency of the chimera-forming activity. This in vitro system may accurately represent the initial step in RNA editing.

Generation of unexpected editing patterns in Leishmania tarentolae mitochondrial mRNAs: misediting produced by misguiding

We have analyzed the generation of unexpected patterns of RNA editing, i.e., those not following a strict 3' to 5' progression, which occur in junction regions between fully edited and preedited sequences. Evidence is presented that these patterns are generated by misediting due to specific events of misguiding. Misediting can occur through the interaction of inappropriate gRNAs with mRNAs or appropriate gRNAs in an incorrect fashion. Four possible mechanisms for the generation of misedited sequences are presented. Chimeric molecules have been detected in steady-state mitochondrial RNAs that are composed of misguiding gRNAs covalently linked to mRNAs at misediting sites by the 3' oligo(U) tail. We propose that misediting within junction regions can be corrected by appropriately acting gRNAs.

Characterization of the [3H]-desipramine binding site of the bovine adrenomedullary plasma membrane

The specific (i.e. nisoxetine-sensitive) binding of [3H]desipramine was studied in membranes prepared from bovine adrenal medullae. (1) [3H]desipramine bound reversibly and with high affinity (KD = 2.8 nmol/l) to a single class of non-interacting binding sites (Hill coefficient = 0.96); the maximal number of binding sites (Bmax) was 2.1 pmol/mg protein. (2) Binding of [3H]desipramine was dependent on [Na+] and [Cl-]. Increasing the concentrations of these ions increased binding. (3) Substrates and inhibitors of the neuronal noradrenaline transport system (uptake1) inhibited binding of [3H]desipramine with a rank order of potency typical for an interaction with the uptake1 carrier. The characteristics of [3H]desipramine binding remained essentially unchanged after solubilization of adrenomedullary membranes with the non-ionic detergent digitonin. The results indicate that the plasma membrane of bovine adreno-medullary cells is endowed with the neuronal uptake1 transporter.

Antibody Production in Silkworm Cells and Silkworm Larvae Infected with a Dual Recombinant Bombyx Mori Nuclear Polyhedrosis Virus

We have examined the efficiency of coexpression of two heterologous genes from a recombinant Bombyx mori nuclear polyhedrosis virus for the production of antibodies in silkworm larvae. The cDNAs encoding the light and the heavy chains of a murine immunoglobulin, directed against lipoprotein I of Pseudomonas aeruginosa, were brought under the control of two separate copies of the viral polyhedrin promotor. Infection of silkworm cells with the recombinant baculovirus yielded a maximum of 6.4 micrograms/ml IgG2A in the culture supernatant 72 hours post infection, while 800 micrograms/ml IgG2A was found in the hemolymph of infected fifth instar silkworm larvae seven days after infection with the same construct. The recombinant antibody exhibited a similar antigen specificity and avidity to that of the monoclonal antibody derived from ascites fluid.

Computer methods for locating kinetoplastid cryptogenes

RNA editing in the mitochondria of kinetoplastid protoza involves the insertion and/or deletion of precise numbers of uridine residues at precise locations in the numbers of uridine residues at precise locations in the transcribed RNA of certain genes. These genes are known as cryptogenes. In this paper we study computational algorithms to search for unknown cryptogenes and for the associated templates for insertion of uridines, gRNA sequences. The pairwise similarity search algorithm of Smith and Waterman (1) is modified to study this problem. The algorithm searches for unknown gRNAs given the cryptogene sequence. The method is tested on 4 known cryptogenes from L.tarentolae which are known to have 7 associated gRNAs. The statistical distribution of the longest gRNA when comparing random sequences is derived. Finally we develop an algorithm to search for cryptogenes using amino acid sequences from related proteins.

Hypothalamic etiology in sympathetically induced pathogenic cardiovascular changes in the cat

Transient cardiovascular changes, including angina-like electrographic signs, are inducible by electrical stimulation of discrete sites in the prefornical region of the lateral hypothalamus (LH) of cats. Repeated stimulation may result in neurogenic cardiac infarction and myocardial bleeding. Thirty Swiss breed locally grown cats were studied under alpha-chloralose anesthesia in pairs, one as control and one experimental, with only the latter receiving multiple stimulations. ECG in lead II and arterial blood pressure were recorded on a Grass polygraph (USA). Electrical stimulation was delivered to a LH target at Fr 9.0, L2.5, D-1 to -2, by means of stainless steel wire electrodes. Stimulation consisted of 15-sec trains of square wave pulses at 100 Hz, 0.2-0.5 msec duration, and threshold currents of 0.05-0.1 mAmp. Stimulation at these LH sites induced small blood pressure changes, often with a small increase or no change in heart rate, presumably a manifestation of baroreceptor dysfunction. Repeating this stimulation greater than 6 times was shown to be pathogenic: on gross examination a darkened area was seen, mostly on the upper ventricular surface of the heart. Microscopic examination of such sites revealed subendocardial bleeding and sometimes also microinfarcts. Scanning electron microscopy revealed an unusually large number of contractures of the myofilaments. Biochemical analysis showed diffusion of catecholamines from nerves. Total myocardial blood flow increased following such stimulation, proportional to the stimulus intensity. It is pointed out that this is not contradictory to the sharply localized ischemic changes assumed to be responsible for the cardiopathy.

Visual responses to reward-related cues in inferior parietal lobule

A sample of 263 neurones was recorded in area 7a of the parietal lobe, in a monkey performing a reach task to visual targets displayed on a touch-sensitive videomonitor. The task had been operantly conditioned on food or juice rewards, and 78 (30%) of the units showed activity changes linked in some way to the reward. For most of these cells, the response was to the approach of the trainer's hand with the food reward. This specific visual response was similar irrespective of the direction of approach. Six cells increased discharge as soon as the task was completed in apparent anticipation of the reward. Another two neurones responded to missing a reward: they fired vigorously if the videoscreen was blanked in mid-trial because a target was not correctly touched. In many cases (40/78) the same cells responding to some aspect of the reward also responded to visual cues given during the task, especially the presentation of the target location. Reward-related activity in area 7a probably results from an integration of the visual and limbic inputs to this region, such that visual information which foretells behaviourally important events is emphasized.

Facilitation of pattern recognition by cuing foveation with the luminance centroid as origin of the frame of reference

The strategy for visual information processing must vary with the specific situation. We assume that in recognition of pre-learnt letter-like patterns under time-pressure conditions, mechanisms of selective attention are involved. We propose that, with simple stimuli, foveation is to the luminance centroids of such patterns, and if normally the latter has to be computed by the brain, cuing such information should improve performance. This assumption was tested on three subjects with five stimuli. In confirmation of the working hypothesis, we found significant improvements in performance (P = 0.01 or better) for each of the stimuli, with cuing to 'relevant' as compared with 'irrelevant' sites, and also when the point of foveation was nearer to the 'nodal' site. It is concluded that in pattern recognition processes, nodal regions are computed, the luminance centroid for example, for simple pattern stimuli.