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W Hesse

Publications and source records attributed to W Hesse.

At least 19 recordsLinked to original sources
PubMed2006

Time-variant analysis of fast-fMRI and dynamic contrast agent MRI sequences as examples of 4-dimensional image analysis.

OBJECTIVES: Image sequences with time-varying information content need appropriate analysis strategies. The exploration of directed information transfer (interactions) between neuronal assemblies is one of the most important aims of current functional MRI (fMRI) analysis. Additionally, we examined perfusion maps in dynamic contrast agent MRI sequences of stroke patients. In this investigation, the focus centers on distinguishing between brain areas with normal and reduced perfusion on the basis of the dynamics of contrast agent inflow and washout. METHODS: Fast fMRI sequences were analyzed with time-variant Granger causality (tvGC). The tvGC is based on a time-variant autoregressive model and is used for the quantification of the directed information transfer between activated brain areas. Generalized Dynamic Neural Networks (GDNN) with time-variant weights were applied on dynamic contrast agent MRI sequences as a nonlinear operator in order to enhance differences in the signal courses of pixels of normal and injured tissues. RESULTS: A simple motor task (self-paced finger tapping) is used in an fMRI design to investigate directed interactions between defined brain areas. A significant information transfer can be determined for the direction primary motor cortex to supplementary motor area during a short time period of about five seconds after stimulus. The analysis of dynamic contrast agent MRI sequences demonstrates that the trained GDNN enables a reliable tissue classification. Three classes are of interest: normal tissue, tissue at risk for death, and dead tissue. CONCLUSIONS: The time-variant multivariate analysis of directed information transfer derived from fMRI sequences and the computation of perfusion maps by GDNN demonstrate that dynamic analysis methods are essential tools for 4D image analysis.

Cerebrovascular Circulation↗
PubMed2002

[Personality and personality disorders I. Universality and sensitivity of dimensional personality models as diagnostic systems for personality disorders].

OBJECTIVE: A dimensional diagnostic system for personality disorders (PD) postulates continuous transitions from normal to disordered personalities (continuity hypothesis) and universal validity of basic personality dimensions (universal hypothesis). In the present study three dimensional personality models that claim to provide a systematic representation of the overall domain of personality disorders were compared: the Big-Five model proposed by Costa and McCrae, the psychobiological model proposed by Cloninger and colleagues, and the "Dimensional Assessment of Personal Pathology (DAPP)" model proposed by Livesley and colleagues. METHOD: The "Six Factor Test" (SFT) measuring the Big-Five factors of personality, the "Temperament and Character Inventory (TCI)" measuring 4 temperament and 3 character dimensions, and the DAPP measuring 18 basic traits and 4 second ordered factors were administered to general population subjects (n = 156), and a clinical sample (n = 220) including a subsample of 69 patients with at least one diagnosis of DSM-IV PD. Group comparisons, regression analyses, and facet theoretical analyses were conducted. RESULTS: The nonmetric similarity analyses of the three personality models show a nearly identical radex-representation of the second ordered factors in the non-clinical and clinical sample reflecting an universal validity of 4 basic personality dimensions and confirming the universal hypothesis. In comparison with the BIG-Five concept and the psychobiological model the DAPP model seems to be more sensitive to differentiate PD patients from controls with a reclassification rate of 94.5 %. CONCLUSIONS: The Big-Five model, the DAPP and the TCI represent a substantially similar domain despite their different conceptualization. However, the DAPP was more sensitive to differences between PD patients and controls, offered a more comprehensive account of PD, and could differentiate the two groups more effectively.

Character↗
PubMed2002

[Personality and personality disorders II. The Specificity of the DAPP-model as a diagnostic system for personality disorders].

The 'Dimensional Assessment of Personality Pathology - Basic Questionnaire' (DAPP) measures 18 traits to provide a systematic representation of the overall domain of personality disorders (PD). The present study investigated the relationships between DAPP personality profiles and dimensional assessments of DSM-IV PD in general population subjects (n = 156), and a sample of 220 nonpsychotic psychiatric patients (including n = 67 PD patients). Using nonmetric multidimensional scaling models the similarities between the 18 DAPP-factors and the dimensional scores of the 12 DSM-IV PD (inclusive appendix) were graphically represented in a 2-dimensional similarity-system. Here each DSM-IV PD dimension could be described by a distinct profile of DAPP-factors. Overall results support the assumption that PD can be represented by a dimensional system of personality traits with sufficient sensitivity and specificity.

Humans↗
PubMed2002

[Brief causal relations in EEG based on adaptive Granger causality].

Commonly, coherence and correlation are used to describe interrelations between EEG signals. But, on this basis, the investigation of causality or direction of interrelations is not possible. The general idea of causality between two signals may be expressed in terms of upgrading the predictability of one signal bye the knowledge of the past of the other signal. The best established approach in this context is the so-called Granger causality. The study present an adaptive estimation of Granger causality, which allows to detect dynamic causal relations within time intervals of less 100 ms. The time-variant Granger causality is applied to EEG data of the Stroop task. It could be shown, that conflict situation generates a dense web of directed interactions from posterior to anterior cortical areas.

Adult↗
PubMed2001

[Motivation, volition, and ambivalence: A contribution to understanding of long-term impairments among schizophrenic patients].

Traditional concepts of avolition (Kraepelin) and ambivalence (Bleuler) among schizophrenic patients can be interpreted in the light of present ideas of motivation and volition. Accordingly schizophrenic patients are marked both by oppositional high hope and fear components of implicit motives and by the impairment of volitional selfregulation, which both are vulnerability factors. In an environment lacking stimuli the patients cannot surpass their ambivalence through volitional selfregulation and remain passive. In this study 61 schizophrenic patients are compared with a control group of 69 non-patients. As expected, the schizophrenic patients show significant higher fear components of the implicit affiliation, achievement, and power motives, as well as an increased hope component of the affiliation motive. The comparison of subgroups of schizophrenic patients with distinguishing symptoms reveals no differences, which supports the assumption of stable traits.

Chronic Disease↗
PubMed1990

[Morphologic changes in the early stages of arthrosis].

"Joint failure" may be the result of different pathological conditions. While in some arthropathies initial changes prior to secondary cartilage destruction may be observed morphologically, the early changes in "mechanically induced" osteoarthrosis are not well known. In the present paper the ultrastructural events, eventually leading to osteoarthrotic cartilage destruction are presented. From the morphological changes it is assumed that the primary lesion leading to cartilage destruction may be seen in the loss of the granular surface microstructures of cartilage that may be followed by an increased hydration and thereafter chondrocytic death with destruction of cartilaginous matrix.

Cartilage, Articular↗
PubMed1989

The neural structures involved in cross-modal recognition and tactile discrimination performance: an investigation using 2-DG.

Given the failure of the ablation method to identify the neural structures/systems that are crucial for cross-modal recognition (CMR) and for tactile discrimination performance (TDP), we injected radioactive 2-deoxy-[14C]glucose (2-DG) into monkeys trained to a high level of CMR or TDP. Nine monkeys were trained to recognize in one sense-modality, to a level greater than 80% correct, the objects experienced in the alternate modality on only a single prior trial. After injection, CMR was continued (Expt. 1a) exactly as before, except that all CMR problems were now in only one direction; or (Expt. 1b) the second--the CMR--trial of each problem was not realized (i.e. no objects were available in the second modality) so that the monkey merely 'expected' the cross-modal trial. Nine other monkeys were trained on a graded roughness discrimination task with conventional 'titration' procedures to a stable level of performance, either (Expt. 2a) without having undergone any cortical removal, or (Expt. 2b) after unilateral removal--contralateral or ipsilateral to the preferred hand--of the posterior insula or of the second somatosensory projection cortex (SII). Exactly the same training procedures were continued in Expt. 2 after injection of 2-DG. Coronal radiographs were made at 490 microns for all 18 monkeys (and also for a 19th, which served as a control in Expt. 1b). The optical densities of the autoradiographs were measured quantitatively in respect of 50 structures or part-structures (e.g. sulci, thalamic nuclei, subcortical structures); they were rated either with the aid of 'pseudo-colours' produced by the computer, or directly by judging the black/white optical densities, in respect of 29 other structures. These 79 structures were then the dependent variables in MANOVAs or ANOVAs, to determine differences between groups; or within groups with respect to the left/right and ipsilateral/contralateral hemispheres; or interaction effects. It was found that certain structures (e.g. the ventral portion of the claustrum, the insula with its extension ventrally into the fundus, nucleus Medialis dorsalis and nucleus Pulvinar oralis) repeatedly, whereas others (e.g. the amygdala) never gave rise to significant outcomes. Structures in the left cerebral hemisphere were frequently found to be more strongly labelled than those in the right hemisphere.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1987

[Eye injuries in childhood].

A retrospective study was performed of eye injuries sustained by children up to 15 years old who had to be hospitalized for treatment. The period under review covered five years. The authors reviewed 241 cases with regard to cause of injury, type of injury, treatment, duration of hospitalization and consequences, if any. Most of the injuries were caused by other children, while playing. By far the most common injury was contusion of the bulb, seen in 107 cases. The results of the study published here contain a further breakdown of the criteria mentioned above.

Child↗
PubMed1986

[Fibrin gluing in ophthalmic surgery].

A new fibrin adhesive "Beriplast" of the Behringwerke AG Marburg was implemented for conjunctival glueing in 42 patients after intracapsular cataract extraction. The tissue adhesive was also examined in palpebral tumour surgery as to its compatibility and usefulness. Good functional and cosmetic results were obtained with regard to the conjunctiva and the eyelids, respectively. No cases of incompatibility were registered.

Adult↗
PubMed1986

[Limbus-based flap versus fornix-based flap in goniotrepanation].

In a prospective, randomized study 61 eyes in which goniotrepanation had been performed using fornix-based or limbus-based conjunctival flaps were followed up for 4 to 18 months. No differences were found in the results of filtration, nor in the form and frequency of filtering blebs or the frequency of complications. In view of the easier technique and better visualization, the present authors prefer the fornix-based flap.

Adult↗
PubMed1986

[Visual fixation tonometry as an aid in the early diagnosis of endocrine ophthalmopathy].

In some cases of autoimmunogenic hyperthyroidism an endocrine ophthalmopathy is found, but it is difficult to diagnose Graves' disease in early stages. Even before the occurrence of measurable morphological changes (measured by sonography and computed tomography of the orbit and eye muscles) short positional intraocular pressure changes are found in 64.5% of cases with autoimmunogenic dysthyreosis. These pressure changes are detected by positional applanation tonometry. These findings admit the conclusion that with the method described not only early detection of ocular signs associated with thyroid disease is possible, but also early differentiation between autoimmunogenic and nonimmunogenic thyroid disorders.

Eye Movements↗
PubMed1986

[Early diagnosis of endocrine ophthalmopathy using eye movement tonometry].

In a certain number of cases (about 30%) of autoimmune hyperthyroidism the pattern of an endocrine ophthalmopathy was observed which is difficult to determine especially in early stages of Graves disease. Already prior to measurable morphological changes, being determined by sonography and computertomography (41.6%), functional discrepancies could be assessed by means of temporary increases of intraocular pressure due to eye movement in 64.5% of cases. Such changes in ocular pressure were established on the basis of eye movement tonometry. Results obtained suggest that by means of the method described an early detection of eye signs associated with thyroid diseases is possible and thus enabling an early differentiation between autoimmune and non-immunogenic thyroid disorders.

Adenoma↗
PubMed1982

[A follow-up study of combined cataract/trabeculectomy operation].

In the past 12 years 69 combined trabeculectomy/cataract operations have been performed at Graz University Eye Clinic. Of these, 33 were examined after an average interval of three years. In 23 cases intraocular pressure was regulated without therapy, and four eyes were regulated with additional therapy. In five eyes no satisfactory pressure could be reached and one eye was lost due to late infection. In ten cases a hyphema appeared; in seven cases registered a rise in intraocular pressure was recorded and in two cases a flat chamber. In view of the great variety of indications this method seems to be especially suitable for elderly patients.

Aged↗