639 research outputs found
Dendritic structure and receptive-field organization of optic flow processing interneurons in the fly
No full textKrapp HG, Hengstenberg B, Hengstenberg R. Dendritic structure and receptive-field organization of optic flow processing interneurons in the fly. Journal of neurophysiology. 1998;79(4):1902-1917.The third visual neuropil (lobula plate) of the blowfly Calliphora erythrocephala is a center for processing motion information. It contains, among others, 10 individually identifiable "vertical system" (VS) neurons responding to visual wide-field motions of arbitrary patterns. We demonstrate that each VS neuron is tuned to sense a particular aspect of optic flow that is generated during self-motion. Thus the VS neurons in the fly supply visual information for the control of head orientation, body posture, and flight steering. To reveal the functional organization of the receptive fields of the 10 VS neurons, we determined with a new method the distributions of local motion sensitivities and local preferred directions at 52 positions in the fly's visual field. Each neuron was identified by intracellular staining with Lucifer yellow and three-dimensional reconstructions from 10-µm serial sections. Thereby the receptive-field organization of each recorded neuron could be correlated with the location and extent of its dendritic arborization in the retinotopically organized neuropil of the lobula plate. The response fields of the VS neurons, i.e., the distributions of local preferred directions and local motion sensitivities, are not uniform but resemble rotatory optic flow fields that would be induced by the fly during rotations around various horizontal axes. Theoretical considerations and quantitative analyses of the data, which will be presented in a subsequent paper, show that VS neurons are highly specialized neural filters for optic flow processing and thus for the visual sensation of self-motions in the fly
Binocular contributions to optic flow processing in the fly visual system
No full textKrapp HG, Hengstenberg R, Egelhaaf M. Binocular contributions to optic flow processing in the fly visual system. Journal of neurophysiology. 2001;85(2):724-734.Integrating binocular motion information tunes wide-field direction-selective neurons in the fly optic lobe to respond preferentially to specific optic flow fields. This is shown by measuring the local preferred directions (LPDs) and local motion sensitivities (LMSs) at many positions within the receptive fields of three types of anatomically identifiable lobula plate tangential neurons: the three horizontal system (HS) neurons, the two centrifugal horizontal (CH) neurons, and three heterolateral connecting elements. The latter impart to two of the HS and to both CH neurons a sensitivity to motion from the contralateral visual field. Thus in two HS neurons and both CH neurons, the response field comprises part of the ipsi- and contralateral visual hemispheres. The distributions of LPDs within the binocular response fields of each neuron show marked similarities to the optic flow fields created by particular types of self-movements of the fly. Based on the characteristic distributions of local preferred directions and motion sensitivities within the response fields, the functional role of the respective neurons in the context of behaviorally relevant processing of visual wide-field motion is discussed
Localised Visualisation of Chemical Cross-talk in Microsensor Arrays Using Scanning Electrochemical Microscopy
No full textKCNJ11 polymorphisms and sudden cardiac death in patients with acute myocardial infarction
No full textPurpose. Patients with an acute myocardial infarction (AMI) are of high risk to develop ischemia-induced ventricular arrhythmias, leading to sudden cardiac death (SCD) in about one third of all AMI patients. The individual susceptibility to ischemia-induced arrhythmias may be modified by polymorphisms in genes encoding ion channels. The cardiac ATP-dependent potassium channel (K-ATP) current is generated by ion channels encoded by the KCNJ11 gene and the SUR2a gene. Opening of the K-ATP channel during ischemia results in action potential shortening in various studies and may therefore influence the outcome of AMI patients
Localized direction selective responses in the dendrites of visual interneurons of the fly
No full textSpalthoff C, Egelhaaf M, Tinnefeld P, Kurtz R. Localized direction selective responses in the dendrites of visual interneurons of the fly. BMC Biology. 2010;8(1): 36.Background:
The various tasks of visual systems, including course control, collision avoidance and the detection of small objects, require at the neuronal level the dendritic integration and subsequent processing of many spatially distributed visual motion inputs. While much is known about the pooled output in these systems, as in the medial superior temporal cortex of monkeys or in the lobula plate of the insect visual system, the motion tuning of the elements that provide the input has yet received little attention. In order to visualize the motion tuning of these inputs we examined the dendritic activation patterns of neurons that are selective for the characteristic patterns of wide-field motion, the lobula-plate tangential cells (LPTCs) of the blowfly. These neurons are known to sample direction-selective motion information from large parts of the visual field and combine these signals into axonal and dendro-dendritic outputs.
Results:
Fluorescence imaging of intracellular calcium concentration allowed us to take a direct look at the local dendritic activity and the resulting local preferred directions in LPTC dendrites during activation by wide-field motion in different directions. These 'calcium response fields' resembled a retinotopic dendritic map of local preferred directions in the receptive field, the layout of which is a distinguishing feature of different LPTCs.
Conclusions:
Our study reveals how neurons acquire selectivity for distinct visual motion patterns by dendritic integration of the local inputs with different preferred directions. With their spatial layout of directional responses, the dendrites of the LPTCs we investigated thus served as matched filters for wide-field motion patterns
Angiotensin converting enzyme gene polymorphism and myocardial infarction a large association and linkage study
No full textThe DD genotype of the angiotensin converting enzyme (ACE) polymorphism has been associated with myocardial infarction (MI). However, sample sizes of many case-control studies showing positive association were small and data were inconsistent. Furthermore, no family-based study is available. In a case-control study frequencies of the ACE genotypes were compared in 1319 unrelated patients with previous MI before 60 years of age (616 from the MONICA Augsburg region and 703 from rehabilitation centers in south Germany) and in 2381 population controls from the MONICA Augsburg study region). Furthermore, linkage and association of the ACE I/D polymorphism with MI were tested in 246 informative families using the sib-transmission/disequilibrium test (S-TDT). Overall, no excess of the D allele was found in MI patients (frequency 0.53 versus 0.57 in the general population; P = 0.2). The ACEDD genotype was even slightly less frequent in groups with MI compared to the general population controls (0.26 versus 0.33 in women and 0.28 versus 0.33 in men). Similar results were also obtained in 247 men with low cardiovascular risk. In the family-based study, the frequency of the D allele was not different in siblings with or without previous MI (0.53 versus 0.50, respectively; S-TDT P = 0.15) indicating no linkage or association of the D allele with MI. In a case-control study of MI patients and controls from the general population as well as a family study neither association nor linkage of the ACED allele with MI was detected despite sample sizes that were among the largest samples studied so far. (C) 2003 Elsevier Science Ltd. All rights reserved
Fixed Capital and Joint Reproduction
No full textThis collection includes:
• Shaikh, A. (n.d.). Quantity and value equations in joint production, the value system, and the Morishima example [Handwritten notes]. Manuscript in possession of the author.
• Shaikh, A. (n.d.). Bibliography on replacement costs, depreciation, and inflation [Handwritten bibliography]. Manuscript in possession of the author.
• Shaikh, A. (1978, April). Bibliography on depreciation from the Columbia University Library [Handwritten bibliography]. Manuscript in possession of the author.
• Shaikh, A. (n.d.). Note that this way constant capital is expressed in current reproduction cost [Handwritten notes]. Manuscript in possession of the author.
• Fay, M. A. (1979, March 1). Letter to George Catephores regarding Marx’s labor theory of value and Morishima. Manuscript in possession of the author.
• Fay, M. A., & Hengstenberg, J. (1978, December 15). Letter to Ian Steedman regarding the labor theory of value and joint production. Manuscript in possession of the author.
• Fay, M. A., & Hengstenberg, J. (n.d.). Schematic representation of our and Steedman’s premises and results. Manuscript in possession of the author.
• Fay, M. A. (1979, February 4). Letter to Bertram regarding correspondence with Steedman, Hengstenberg, and Catephores. Manuscript in possession of the author.
• Hengstenberg, J., & Fay, M. A. (1979, March). Critique of Morishima’s arguments on Marx’s labor theory of value [Paper]. Manuscript in possession of the author.
• Hengstenberg, J. (n.d.). Letter in German to B. S. regarding Morishima’s example of negative labor values. Manuscript in possession of the author.
• Steedman, I. (1978, November 27). Letter to Margaret Fay and Johannes Hengstenberg regarding their paper on joint production. Manuscript in possession of the author.
• Shaikh, A. (n.d.). Commenting Steedman’s letter to us from 27th of November 1978 [Handwritten notes]. Manuscript in possession of the author.
• Steedman, I. (1979, January 11). Letter to Margaret Fay responding to her December 15th letter. Manuscript in possession of the author.
• Fay, M. A., & Hengstenberg, J. (1979, February 4). Letter to Ian Steedman responding to his January 11th letter. Manuscript in possession of the author.
• Shaikh, A. (n.d.). Trying to take Steedman’s objection seriously: “All the algebra is really redundant” [Handwritten notes]. Manuscript in possession of the author.
• Shaikh, A. (n.d.). Schematic representation of Shaikh’s and Steedman’s premises and results [Handwritten notes]. Manuscript in possession of the author.
• Shaikh, A. (n.d.). Notes on Garegnani (1970) and Pasinetti [Handwritten notes]. Manuscript in possession of the author.
• Sraffa, P. (1932, March). Dr. Hayek on money and capital I. The Economic Journal, 42(165), 42–53.
• Shaikh, A. (n.d.). Investment income, depreciation, internal rate of return, and actual revenue [Handwritten notes and examples]. Manuscript in possession of the author.
• Maxfield, M. (1979). Bank illiquidity hits new high [Article with chart]. Manuscript in possession of the author.
• Shaikh, A. (n.d.). The Sraffa method of depreciation allowances [Handwritten notes]. Manuscript in possession of the author.
• Shaikh, A. (1977, July). Different methods of treating deprec. allowances: Comparing Shaikh’s method to Sraffa’s and Marx’s [Handwritten notes]. Manuscript in possession of the author.
• Shaikh, A. (1978, August 9). Internal rate of return, perpetuity rate of return, N-year bonds, and varying yields [Handwritten notes]. Manuscript in possession of the author.
• Shaikh, A. (n.d.). Notes on Jerome’s “Return on operative investment — The Du Pont approach” [Handwritten notes]. Manuscript in possession of the author.
• Shaikh, A. (n.d.). Sraffa’s fixed capital [Handwritten notes]. Manuscript in possession of the author.
• Shaikh, A. (n.d.). Fixed capital chs J. P. (Steedman) [Handwritten notes]. Manuscript in possession of the author.
• Shaikh, A. (1978, May 27). The Sraffa method of depreciation: Example [Handwritten notes]. Manuscript in possession of the author.
• Shaikh, A. (1977, March 21). Joint production: Allocating costs, co-products, and different processes [Handwritten notes]. Manuscript in possession of the author.
• Shaikh, A. (1977, April 14). Notes on joint production: Critiques of conventional formulations and the confusion of fixed capital with joint products [Handwritten notes]. Manuscript in possession of the author.
• Shaikh, A. (n.d.). Subsystem approach, negative values, and the problem of dominated techniques [Handwritten notes]. Manuscript in possession of the author.
• Shaikh, A. (n.d.). Steedman’s problem: Equations and discussion of dual and price implications [Handwritten notes]. Manuscript in possession of the author.
• Shaikh, A. (1978, August). Average rate of return, gross profit stream, and time deposits [Handwritten notes]. Manuscript in possession of the author.
• Shaikh, A. (1978, July 30). Rate of return & opportunity cost [Handwritten notes]. Manuscript in possession of the author.
• Shaikh, A. (1978, July 31). Fixed capital & rate of return: The Sraffa system [Handwritten notes]. Manuscript in possession of the author.
• Shaikh, A. (1978, July 31). Pattern of expenditures and receipts in industrial capital: Table of capital stocks [Handwritten notes]. Manuscript in possession of the author.
• Shaikh, A. (n.d.). Sraffa’s fixed capital with equations [Handwritten notes]. Manuscript in possession of the author.
• Shaikh, A. (1978, August 17). Present value & internal rate of return [Handwritten notes]. Manuscript in possession of the author.
• Shaikh, A. (1987, September 24). Uniform rate of profit, canonical models, and Steedman’s example [Handwritten notes]. Manuscript in possession of the author.
• Shaikh, A. (n.d.). Joint production, single product industries, and feasible combinations [Handwritten notes]. Manuscript in possession of the author.
• Shaikh, A. (1978, June 20). Sale of used machines by single machine and balanced stock enterprises [Table]. Manuscript in possession of the author.
• Shaikh, A. (1978, July 2). Frankfurt comments on fixed capital presentation [Handwritten notes]. Manuscript in possession of the author.
• Shaikh, A. (n.d.). Equations with lambda and omega variables [Handwritten equations]. Manuscript in possession of the author.
• Shaikh, A. (1978, June 30). Notes on fixed capital: Sraffa’s method and orthodox capital theory [Handwritten notes]. Manuscript in possession of the author.
• Shaikh, A. (1977, June 27). Balanced stock: Comparing Shaikh’s method to Sraffa’s and Marx’s [Handwritten notes]. Manuscript in possession of the author.
• Shaikh, A. (n.d.). Comparison of the Shaikh, Sraffa, and Marx methods with numerical example [Handwritten notes]. Manuscript in possession of the author.
• Shaikh, A. (n.d.). The Sraffa system: Discussion of the scrapping margin [Handwritten notes]. Manuscript in possession of the author.
• Shaikh, A. (1978, June 28). Pattern of receipts & method of deprec.: Gross and net profits under efficiency scenarios [Table]. Manuscript in possession of the author.
• Shaikh, A. (n.d.). Notes from Marx’s Capital Volumes II and III, with page references [Handwritten notes]. Manuscript in possession of the author.
• Shaikh, A. (n.d.). Equations on the rate of profit and surplus value [Handwritten notes]. Manuscript in possession of the author.
• Kuruma, Y. (n.d.). The metaphysics of joint production: Steedman values versus Morishima values [Paper]. Manuscript in possession of the author.
• Sekine, T. T. (n.d.). The metaphysics of joint production: Steedman values versus Morishima values [Paper]. Manuscript in possession of the author.
• Shaikh, A. (1978, November 10). Joint production and multiple techniques [Handwritten notes]. Manuscript in possession of the author.
• Schefold, B. (1978, June 7). Letter to John Eatwell with travel directions. Manuscript in possession of the author
Genetic Determinants of Circulating Sphingolipid Concentrations in European Populations
No full textSphingolipids have essential roles as structural components of cell membranes and in cell signalling, and disruption of their metabolism causes several diseases, with diverse neurological, psychiatric, and metabolic consequences. Increasingly, variants within a few of the genes that encode enzymes involved in sphingolipid metabolism are being associated with complex disease phenotypes. Direct experimental evidence supports a role of specific sphingolipid species in several common complex chronic disease processes including atherosclerotic plaque formation, myocardial infarction (MI), cardiomyopathy, pancreatic beta-cell failure, insulin resistance, and type 2 diabetes mellitus. Therefore, sphingolipids represent novel and important intermediate phenotypes for genetic analysis, yet little is known about the major genetic variants that influence their circulating levels in the general population. We performed a genome-wide association study (GWAS) between 318,237 single-nucleotide polymorphisms (SNPs) and levels of circulating sphingomyelin (SM), dihydrosphingomyelin (Dih-SM), ceramide (Cer), and glucosylceramide (GluCer) single lipid species (33 traits); and 43 matched metabolite ratios measured in 4,400 subjects from five diverse European populations. Associated variants (32) in five genomic regions were identified with genome-wide significant corrected p-values ranging down to 9.08 x 10(-66). The strongest associations were observed in or near 7 genes functionally involved in ceramide biosynthesis and trafficking: SPTLC3, LASS4, SGPP1, ATP10D, and FADS1-3. Variants in 3 loci (ATP10D, FADS3, and SPTLC3) associate with MI in a series of three German MI studies. An additional 70 variants across 23 candidate genes involved in sphingolipid-metabolizing pathways also demonstrate association (p = 10(-4) or less). Circulating concentrations of several key components in sphingolipid metabolism are thus under strong genetic control, and variants in these loci can be tested for a role in the development of common cardiovascular, metabolic, neurological, and psychiatric diseases
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