bluuebunny/crossref_metadata_2025 huggingface dataset:
Gas embolism: pathophysiology and treatment
Authors: van Hulst Robert A. , Klein Jan , Lachmann Burkhard
Published: September 2003

Based on a literature search, an overview is presented of the pathophysiology of venous and arterial gas embolism in the experimental and clinical environment, as well as the relevance and aims of diagnostics and treatment of gas embolism. The review starts with a few historical observations and then addresses venous air embolism by discussing pulmonary vascular filtration, entrapment, and the clinical occurrence of venous air emboli. The section on arterial gas embolism deals with the main mechanisms involved, coronary and cerebral air embolism (CAE), and the effects of bubbles on the blood–brain barrier. The diagnosis of CAE uses various techniques including ultrasound, perioperative monitoring, computed tomography, brain magnetic resonance imaging and other modalities. The section on therapy starts by addressing the primary treatment goals and the roles of adequate oxygenation and ventilation. Then the rationale for hyperbaric oxygen as a therapy for CAE based on its physiological mode of action is discussed, as well as some aspects of adjuvant drug therapy. A few animal studies are presented, which emphasize the importance of the timing of therapy, and the outcome of patients with air embolism (including clinical patients, divers and submariners) is described.
University of Cincinnati Dyspnea Questionnaire for Evaluation of Dyspnoea during physical and speech activities in patients with chronic obstructive pulmonary disease: a validation analysis
Authors: Hodgev V. , Kostianev S. , Marinov B.
Published: September 2003

University of Cincinnati Dyspnea Questionnaire (UCDQ) was developed to measure the impact of dyspnoea during (1) physical activity (Phys), (2) speech activity (Speech) and (3) simultaneous speech and physical activity (Comb). The aim of this study was to evaluate the validity of UCDQ in COPD patients, comparing it to a large set of dyspnoeic indices and functional parameters. Fifty COPD patients (age 58·7 ± 9·1 years, FEV1%pred = 39·3 ± 17·0%, Baseline Dyspnoea Index (BDI) = 4·9 ± 2·5, Six Minute Walk Distance (6MWD) = 373 ± 128 m, Symptoms score = 9·4 ± 2·5; mean ± SD) participated in the study. We found the following mean scores for the three sections of the questionnaire: Phys = 3·5 ± 0·9; Speech = 2·4 ± 1·1; Comb = 4·2 ± 1·0, meaning that patients report the most breathlessness during the combination of speaking and physical activity and the least breathlessness during speech activities. All three section of UCDQ had significant strong correlation with dyspnoea indices (BDI, Borg, MRC, OCD), 6MWD and symptoms score, which proves its concurrent and construct validity. Differentiation of patients by speech section (=3<) discriminated them significantly with respect to all dyspnoeic indices, symptoms score and 6MWD. All three dimensions of UCDQ had high test–retest reliability – ICC between 0·76 and 0·93. Factor analysis yielded three interpretable factors, as all dyspnoeic indices, three sections of UCDQ, symptoms score and 6MWD were loaded on the first factor. In conclusion, UCDQ provides valid and reliable information about the effect of dyspnoea on speech and daily activities.
Effects of simultaneous aortocaval occlusion on oxygen consumption in patients
Authors: Hofland Jan , Tenbrinck Robert , Eggermont Alexander M.M. , van Eijck Casper H.J. , Gommers Diederik , Erdmann Wilhelm
Published: September 2003

The effects of simultaneous occlusion of the thoracic aorta and inferior vena cava on oxygen consumption () have not yet been reported in humans. Ten patients (all ASA II) needed such simultaneous occlusion to allow hypoxic abdominal perfusion in the treatment of pancreatic cancer. With the development of the PhysioFlex® anaesthesia machine for closed‐circuit anaesthesia, intra‐operative real‐time curves of became available. Thus, we can continuously measure , and air consumption. By placing a pulmonary artery catheter, we could also intermittently calculate during the several phases of the perfusion procedure. Immediately after the simultaneous aortocaval occlusion started, decreased by 35% (68 ml min−1 m−2) and decreased below the critical value of 330 ml min−1 m−2. At reperfusion, repayment of the oxygen debt was by a two‐stage pattern: a fast repayment stage with an increase of about 65% was followed by a slow repayment stage of 14% increase (values compared to steady state). Oxygen consumption in women was found to be significantly lower than in men (P = 0·02), with significant variation between the sexes during different stages of the procedure. The oxygen debt was not completely repaid by the end of the procedure. We conclude that the significant variation found in oxygen consumption will have consequences while performing low‐flow anaesthesia, that additional oxygen supply during the recovery period because of the initially incomplete repayment of oxygen debt may be useful and that studies on oxygen consumption must present gender‐specific data because of the gender‐dependent variation found in oxygen consumption.
Prolonged acetylcholine‐induced vasodilatation in the peripheral microcirculation of patients with chronic fatigue syndrome
Authors: Khan Faisel , Spence Vance , Kennedy Gwen , Belch Jill J. F.
Published: September 2003

Although the aetiology of chronic fatigue syndrome (CFS) is unknown, there have been a number of reports of blood flow abnormalities within the cerebral circulation and systemic blood pressure defects manifesting as orthostatic intolerance. Neither of these phenomena has been explained adequately, but recent reports have linked cerebral hypoperfusion to abnormalities in cholinergic metabolism. Our group has previously reported enhanced skin vasodilatation in response to cumulative doses of transdermally applied acetylcholine (ACh), implying an alteration of peripheral cholinergic function. To investigate this further, we studied the time course of ACh‐induced vasodilatation following a single dose of ACh in 30 patients with CFS and 30 age‐ and gender‐matched healthy control subjects. No differences in peak blood flow was seen between patients and controls, but the time taken for the ACh response to recover to baseline was significantly longer in the CFS patients than in control subjects. The time taken to decay to 75% of the peak response in patients and controls was 13·7 ± 11·3 versus 8·9 ± 3·7 min (P = 0·03), respectively, and time taken to decay to 50% of the peak response was 24·5 ± 18·8 versus 15·1 ± 8·9 min (P = 0·03), respectively. Prolongation of ACh‐induced vasodilatation is suggestive of a disturbance to cholinergic pathways, perhaps within the vascular endothelium of patients with CFS, and might be related to some of the unusual vascular symptoms, such as hypotension and orthostatic intolerance, which are characteristic of the condition.
Assessment of adipose tissue metabolism by means of subcutaneous microdialysis in patients with sepsis or circulatory failure
Authors: Martinez Alexandre , Chiolero Rene , Bollman Marc , Revelly Jean‐Pierre , Berger Mette , Cayeux Christine , Tappy Luc
Published: September 2003

To evaluate the role of adipose tissue in the metabolic stress response of critically ill patients, the release of glycerol and lactate by subcutaneous adipose tissue was assessed by means of microdialysis in patients with sepsis or circulatory failure and in healthy subjects. Patients with sepsis had lower plasma free fatty acid concentrations and non‐significant elevations of plasma glycerol concentrations, but higher adipose‐systemic glycerol concentrations gradients than healthy subjects or patients with circulatory failure, indicating a stimulation of subcutaneous adipose lipolysis. They also had a higher lipid oxidation. Lipid metabolism (adipose‐systemic glycerol gradients, lipid oxidation) was not altered in patients with circulatory failure. These observations highlight major differences in lipolysis and lipid utilization between patients with sepsis and circulatory failure. Hyperlactataemia was present in both groups of patients, but the adipose‐systemic lactate concentration gradient was not increased, indicating that lactate production by adipose tissue was not involved. This speaks against a role of adipose tissue in the development of hyperlactataemia in critically ill patients.
State of vigilance, oestrogen replacement therapy, and lipid profile as modifiers of nocturnal movement‐induced heart rate responses
Authors: Virtanen Irina , Ekholm Eeva , Aittokallio Tero , Tähtinen Jarno , Salmi Jussi , Järvi Jaakko , Polo‐Kantola Päivi , Polo Olli
Published: September 2003

Study objectives: To investigate the body movement‐associated heart rate responses during sleep in postmenopausal women and to evaluate the possible effect of transdermal oestrogen replacement therapy and metabolic factors on these responses.

Design: A prospective double‐blind cross‐over placebo‐controlled trial.

Setting: A university sleep research unit.

Patients: Seventy‐one healthy postmenopausal women.

Methods: The subjects underwent a whole‐night polysomnography including an electrocardiogram (ECG) and a sensitive whole‐body movement sensor channel. Body movements of 2–15 s duration with an artefact‐free ECG were identified and heart rate was automatically analysed for 30 s before and 60 s after movement. The movement‐induced reflex tachycardia and the following rebound bradycardia were measured for the awake state, non‐rapid eye movement (REM) sleep and REM sleep. Indices of the heart rate response correlated with age, body mass index (BMI) and high‐density lipoprotein (HDL)/low‐density lipoprotein (LDL) cholesterol ratio.

Results: The tachycardia response to a body movement was stronger during sleep than in the awake state, being strongest in REM sleep. The rebound bradycardia following a tachycardia response was relatively similar in REM and in the awake states, but attenuated in non‐REM sleep. Oestrogen did not influence the heart rate response. Increasing age and BMI attenuated the response, while an increase in the HDL/LDL cholesterol ratio enhanced the rebound bradycardia response.

Conclusions: Sleep powerfully modulates the rapid cardiac autonomic responses to internal stressors. Postmenopausal hormone replacement therapy does not influence these responses, but they are strongly modulated by lipid metabolism and closely correlated with age and BMI.
Age‐related macular degeneration and nutritional supplementation: a review of randomised controlled trials
Authors: Bartlett Hannah , Eperjesi Frank
Published: September 2003

Age‐related macular degeneration (AMD) is the leading cause of severe vision loss in the developed world. The lack of effective treatment modalities, coupled with evidence supporting an oxidative pathogenesis, has increased interest in the potential preventative role of nutritional supplementation.

This article reviews seven randomised controlled trials (RCTs) that have investigated the role of nutritional supplementation in AMD. Three of these trials reported a positive effect of nutritional supplementation on AMD; the Age‐related eye study (AREDS), the Lutein Antioxidant Supplementation Trial (LAST), and the oral zinc trial by Newsome et al. (1988). However, the oral zinc trial by Newsome et al. (1988) was unlikely to detect any difference between treatments smaller than 72%, and the AREDS results were based on a subgroup of their study population. Lutein was considered for the AREDS formulation, but was not commercially available at that time. The findings of the LAST support a possible therapeutic role of lutein in AMD.
Anterior chamber angle measurement with Anterior Eye Segment analysis system Nidek EAS‐1000®: improving the repeatability
Authors: Lee Tsui‐tsui , Lam Andrew K. C. , Chan Ben L. K.
Published: September 2003

Previous studies have reported good intraobserver and interobserver repeatability of anterior chamber angle (ACA) assessment using the Anterior Eye Segment analysis system, EAS‐1000®. This study investigated the influence of fixation pattern, corneal plotting method and camera position on ACA measurements.

A Nidek EAS‐1000® system was employed for image acquisition and analysis, to obtain measurements of ACA. Twenty‐five young healthy subjects participated.

The ACAs were different in different quadrants and using different corneal plotting methods (Repeated measures 3‐way anova, p < 0.05). However, the difference was <5° and therefore not clinically significant. Alignment along the visual axis or optical axis did not yield any significant difference. Repeatability was improved by asking the subjects to fixate at the flashing light‐emitting diode (LED). Temporal and nasal angles also demonstrated better repeatability than vertical angles. In measuring the vertical angles, the camera can be set at either the temporal or nasal side (Paired t‐test, p > 0.05).

The Anterior Eye Segment analysis system has good clinical repeatability in measuring ACA. It can be further improved with the use of the flashing LED during image acquisition.
The autonomic control of accommodation and implications for human myopia development: a review
Authors: Chen Jennifer C. , Schmid Katrina L. , Brown Brian
Published: September 2003

Prolonged nearwork has long been associated with myopia development, however, there is no well described linking mechanism. One theory suggests that if accommodation accuracy during nearwork is not maintained, the defocused retinal image leads to myopia development. Here we review the findings of research aimed at determining whether the autonomic inputs to the ciliary smooth muscle are involved in this type of environmental myopia. We examine whether an autonomic imbalance could be a precursor to axial elongation and the resulting myopia. Accommodation responses, such as tonic accommodation and nearwork‐induced accommodative adaptation, as a function of refractive error, are described in relation to an autonomic imbalance model. The collective results of this research point to anomalous accommodation responses, possibly as a result of underlying anomalous autonomic input to the ciliary muscle, being involved in myopia development and progression.
Criteria for prescribing optometric interventions: literature review and practitioner survey
Authors: O'Leary Claire I. , Evans Bruce J. W.
Published: September 2003

The core function of optometrists is the prescribing of refractive corrections, yet a literature review revealed a lack of evidence‐based research on criteria for determining when a refractive correction is required. The reported criteria used by practising optometrists were investigated using a questionnaire to survey prescribing habits for borderline hypermetropia, presbyopia, astigmatism, and horizontal and vertical heterophoria. Thirty‐eight questionnaires were returned and the results analysed. We calculated the ‘cut off’ point above which the anomaly would be corrected over 50% of the time that it was encountered. There was a large variation for each category, but it was clear that the presence or absence of symptoms was an important factor for most optometrists when deciding whether to correct a small error. It was found that for symptomatic patients, most optometrists would correct an anomaly if it reached: +1.00 D of hypermetropia, a reading addition of +0.75 D for presbyopia, −0.75 DC of astigmatism, 1.5 prism dioptres (Δ) of horizontal aligning prism, and 1 Δ of vertical dissociated heterophoria. For asymptomatic patients, optometrists would not correct any of the hypermetropic anomalies or heterophorias that were specified in our questionnaire. However most would correct a presbyopic error of +1.50 D or above, or an astigmatic error of −1.50 DC or above, even in the absence of symptoms. These results were compared with previously published guidelines.
A Mueller matrix model of Haidinger's brushes
Authors: Misson Gary P.
Published: September 2003

Stokes vectors and Mueller matrices are used to model the polarisation properties (birefringence, dichroism and depolarisation) of any optical system, in particular the human eye. An explanation of the form and behaviour of the entoptic phenomenon of Haidinger's brushes is derived that complements and expands upon a previous study. The relationship between the appearance of Haidinger's brushes and intrinsic ocular retardation is quantified and the model allows prediction of the effect of any retarder of any orientation placed between a source of polarised light and the eye. The simple relationship of minimum contrast of Haidinger's brushes to the cosine of total retardation is derived.
Computerised calculation scheme for ocular magnification with the Zeiss telecentric fundus camera
Authors: Langenbucher Achim , Seitz Berthold , Viestenz Arne
Published: September 2003

Littmann (1982) described a method to determine the magnification of the eye in order to relate the size of a retinal feature to its measured image size on a telecentric fundus camera film. This required information only about ametropia and corneal curvature. Several other methods have been reported since then which consider other biometric data to enhance the accuracy of this classical method. The purpose of this study is to describe a numerical calculation scheme to determine the magnification q of the eye in two cardinal meridians using paraxial raytracing. Our calculation scheme is based on ametropia, keratometry, as well as biometric data such as axial length, anterior chamber depth and thickness of the crystalline lens. It is described step‐by‐step in order (1) to determine the refractive powers of both surfaces of the crystalline lens, which are not directly measurable in vivo, (2) to derive the retinal image conjugate to a circular object using paraxial raytracing, (3) to fit an ellipse to the retinal image, (4) to determine the secondary principal points (Gaussian length) separately for both cardinal meridians and (5) to calculate the ocular magnification q. The power of the crystalline lens is estimated to compensate for the spherocylindrical refraction at the spectacle plane and the corneal refraction with an astigmatic component thus creating a sharp image focused at the retinal plane. The capabilities of this computing scheme are demonstrated with five clinical examples and are related to the respective values of the classical Littmann formula as well as to enhanced methods described by Bennett (1988), Bennett et al. (1994) and Garway‐Heath et al. (1998).
The relationship between the Stiles–Crawford effect of the first kind (SCE‐I) and myopia
Authors: Choi Stacey S. , Garner Leon F. , Enoch Jay M.
Published: September 2003

The Stiles–Crawford effect of the first kind (SCE‐I) was measured on both emmetropic and myopic subjects at six different retinal locations. The results revealed a number of significant discrepancies in receptor alignment between the groups of different refractive errors. In myopic subjects, the receptors in the nasal retina (i.e. between the fovea and the optic nerve head) were found to be aligned nasally towards the optic nerve head, whereas the receptors in the temporal retina were aligned towards the centre of the exit pupil. In emmetropic subjects, the receptors across the retina were finely tuned towards the centre of the exit pupil. The magnitude of the receptor displacement in myopic subjects was found to be directly associated with the length of the eyeball.
Stiles‐Crawford effect of the first kind (SCE‐I) in post‐photorefractive keratectomy and anisometropic subjects
Authors: Choi Stacey S. , Garner Leon F. , Enoch Jay M.
Published: September 2003

The Stiles‐Crawford effect of the first kind (SCE‐I) was measured on both post‐photorefractive keratectomy (PRK) and anisometropic subjects at six different locations of retina. The eye that underwent the PRK procedure showed results that were typical of myopic eyes, although the vision in that eye has been maintained at 6/5 (or 20/15) since the operation. The anisometropic subject had one eye that was emmetropic and the other eye was myopic with a refractive error of −3.00 DS. The emmetropic eye showed the normal well‐centered SCE‐I functions across the retina, whereas the myopic eye of the same subject showed the nasal tilting of receptors in the nasal retina, which has been the typical finding among myopic subjects.
Predicting the continued use of overlays in school children – a comparison of the Developmental Eye Movement test and the Rate of Reading test
Authors: Northway Nadia
Published: September 2003

Coloured overlays have been advocated to enhance reading speed and ability in children with reading difficulty or dyslexia. Assessing the efficacy of overlays has to date been largely subjective. Objective assessment is presently carried out with the Rate of Reading test (RRT), where an increase in reading speed of more than 5% is considered to indicate a positive prognosis for continued use of the overlay. The Developmental Eye Movement (DEM) test is used to assess horizontal scanning behaviour in a number naming task. In this study both tests were utilised to determine whether coloured overlays could enhance reading performance or scanning. This article shows that for some children rate of reading is not improved with coloured overlays although performance on the DEM test does improve. Improvements to the DEM scores occurred in 88% of children who continued to use overlays for more than 3 months. This compared with 60% sensitivity in the RRT. The possible reasons for this phenomenon and the clinical implications are discussed.
Effect of normal aging on functional connectivity of the brain: an EEG study
Authors: SHINOSAKI Kazuhiro , ISHII Ryouhei , UKAI Satoshi , MIZUNO‐MATSUMOTO Yuko , INOUYE Tsuyoshi , TUTIYAMA Masato , KAKU Tetsuji , TAKEDA Masatoshi
Published: September 2003

Background:  Cognitive decline associated with normal aging, mild cognitive impairment (MCI) and Alzheimer's disease (AD) are, in theory, reflected in the disturbance of selective neural networks.

Methods:  The effect of aging on the functional connectivity of multiple areas of the brain was investigated by using relative power contribution (RPC) analysis of alpha activity. Electroencephalograms were recorded from eight channels in 38 healthy elderly subjects aged 50–89 years and in 22 control subjects aged 20–29 years.

Results:  Entropy of the RPC of alpha activity, indicating the amount of dependence in each area, showed a significant decrease in the left temporo‐occipital area in 50–80‐year‐old subjects and in the right inferior frontal area in 70–80‐year‐old subjects.

Conclusions:  A metabolic decrease in these areas is also reported in patients with AD or MCI. The results from this study suggest that the normal aging process and pathological processes may exhibit a partially common pattern of neural degeneration. However, further studies are required using a larger sample size and strict discrimination between normal aging and MCI.
Desynchronization in the right auditory cortex during musical hallucinations: A MEG study
Authors: SHINOSAKI Kazuhiro , YAMAMOTO Masakiyo , UKAI Satoshi , KAWAGUCHI Shunsuke , OGAWA Asao , ISHII Ryouhei , MIZUNO‐MATSUMOTO Yuko , INOUYE Tsuyoshi , HIRABUKI Norio , YOSHIMINE Toshiki , KAKU Tetsuji , ROBINSON Stephen E. , TAKEDA Masatoshi
Published: September 2003

Desynchronization in the right auditory cortices, including the transverse gyrus of Heschl, planum temporale and supramarginal cortex, occurred during musical hallucinations in a 78‐year‐old woman with hearing impairment and depression. This phenomenon was assessed using a novel, spatially filtered magnetoencephalography (MEG) analysis, termed synthetic aperture magnetometry (SAM). In general, the affected areas are consistent with neuroimaging studies of normal musical perception and imagery, suggesting that musical hallucinations involve abnormal spontaneous activity in the neural substrate dedicated to musical perception and imagery in which false imagery occurs.
Cognitive Assessment and Reference Diagnosis System: development of a neuropsychological and clinical examination for clinic and population use
Authors: SUH Guk‐Hee , LEE Mi Ho
Published: September 2003

Background:  Recent therapeutic advances to delay the progression of dementia have renewed calls to improve the early detection and management of individuals with dementia. A new computerized neuropsychological interview and clinical examination, the Cognitive Assessment and Reference Diagnosis System (CARDS) was developed to incorporate in a single instrument all the information required to make an accurate clinical diagnosis of dementia (its subtype, depression and delirium), to present reference diagnoses following the completion of tests and to detect early dementia. This study aims to verify the validity and reliability of CARDS.

Methods:  The CARDS was administered to 70 dementia patients (51 Alzheimer's disease, 19 vascular dementia) and 34 healthy (control) subjects. Three aspects of reliability (internal consistency reliability, inter‐rater and test–retest reliability) were tested. Correlations with the Alzheimer's Disease Assessment Scale, Korean version (ADAS‐K), the Cambridge Cognitive Examination, Korean version (CAMCOG‐K) and the Mini‐Mental State Examination, Korean version (MMSE‐K) were used to estimate the concurrent validity of CARDS. To evaluate the sensitivity of CARDS, mean scores from CARDS, ADAS‐K, CAMCOG‐K and MMSE‐K were compared between dementia patients and control subjects.

Results:  The CARDS demonstrated high levels of reliability. Mean CARDS scores for dementia patients were significantly different from the control group (P < 0.001). Furthermore, CARDS was significantly correlated with other tests and scales (P < 0.01).

Conclusion:  We demonstrated that CARDS is a reliable and valid instrument not only for dementia diagnosis, but also for the evaluation of impaired cognitive domains. A regression equation, derived from nationwide population surveys for norm data from CARDS, will be applied for individualized cutoff scores of five domains of dementia to eliminate the influence of age, sex and educational attainment on test scores.
Proliferation of peripheral blood mononuclear cells is suppressed by the indoleamine 2,3‐dioxygenase expression of interferon‐γ–treated skin cells in a co‐culture system
Authors: Sarkhosh Kourosh , Tredget Edward E. , Li Yunyuan , Kilani Ruhangiz T. , Uludag Hasan , Ghahary Aziz
Published: August 2003

Indoleamine 2,3‐dioxygenase (IDO) is an intracellular tryptophan‐oxidizing enzyme possessing various immunosuppressive characteristics. In this study, we report the possible use of this enzyme in an allogenic skin substitute to suppress the proliferation of immune cells. Human fetal skin fibroblasts and keratinocytes were treated with the cytokine interferon‐γ to induce expression of IDO mRNA and protein. IDO enzyme activity was evaluated by measurement of kynurenine levels in the interferon‐γ–treated and –untreated cells. Results of Northern analysis showed a dose‐dependent response in expression of IDO mRNA to the various concentrations of interferon‐γ used. Northern blot analysis also showed a time‐dependent expression of IDO in response to different durations of interferon‐γ treatment. The level of kynurenine measured, as the bioactivity of IDO enzyme, was significantly higher in the interferon‐γ–treated fibroblasts and keratinocytes compared to those of controls (p < 0.001). To illustrate the immunosuppressive effects of IDO on immune cell proliferation, IDO‐expressing fibroblasts were cocultured with human peripheral blood mononuclear cells for a period of 5 days. Results of 3H‐thymidine incorporation assays showed a significant reduction in proliferation of the mononuclear cells cocultured with IDO‐expressing skin cells compared to monocytes cocultured with control (non‐IDO‐expressing) skin cells (p < 0.001). Furthermore, addition of the IDO‐inhibitor (1‐methyl‐D‐tryptophan) significantly reversed the immunosuppressive effects of IDO on monocyte proliferation (p < 0.001). In conclusion, suppression of peripheral blood mononuclear cell proliferation due to interferon‐γ–induced IDO‐expression in allogenic human skin cells might shed new light on developing a nonrejectable allogenic skin substitute. (WOUND REP REG 2003;11:337–345)
Developmental integration in a complex morphological structure: how distinct are the modules in the mouse mandible?
Authors: Klingenberg Christian Peter , Mebus Katharina , Auffray Jean‐Christophe
Published: August 2003

SummaryThe mouse mandible has long served as a model system for studying the development and evolution of complex morphological structures. We used the methods of geometric morphometrics to reassess the hypothesis that the mandible consists of two separate modules: an anterior part bearing the teeth and a posterior part with muscle attachment surfaces and articulating with the skull. The analyses particularly focused on covariation of fluctuating asymmetry, because such covariation is due exclusively to direct interactions between the developmental processes that produce the traits of interest, whereas variation of traits among individuals also reflects other factors. The patterns of fluctuating asymmetry and individual variation were only partly consistent, indicating that developmental processes contribute differentially to variation at different levels. The results were in agreement with the hypothesis that the anterior and posterior parts of the mandible are separate develop‐mental modules. Comparison of all alternative partitions of the landmarks into two contiguous subsets confirmed the hypothesis for the location of the boundary between modules but also underscored that the separation between them is not complete. Modularity is therefore manifest as the relative independence of parts within the framework of overall integration of the mandible as a whole—it is a matter of degrees, not all or nothing.
Conserved and divergent functions of Drosophila atonal, amphibian, and mammalian Ath5 genes
Authors: Sun Yan , Kanekar Shami L. , Vetter Monica L. , Gorski Sharon , Jan Yuh‐Nung , Glaser Tom , Brown Nadean L.
Published: August 2003

Summary
Insect and vertebrate eyes differ in their formation, cellular composition, neural connectivity, and visual function. Despite this diversity, Drosophila atonal and its vertebrate Ortholog in the eye, Ath5, each regulate determination of the first retinal neuron class—R8 photo‐receptors and retinal ganglion cells (RGCs)—in their respective organisms. We have performed a cross‐species functional comparison of these genes. In ato1 mutant Drosophila, ectopic Xenopus Ath5 (Xath5) rescues photoreceptor cell development comparably with atonal. In contrast, mouse Ath5 (Math5) induces formation of very few ommatidia, and most of these lack R8 cells. In the developing frog eye, ectopic atonal, like Xath5, promotes the differentiation RGCs. Despite strong conservation of atonal, Xath5, and Math5 structure and shared function, other factors must contribute to the species specificity of retinal neuron determination. These observations suggest that the atonal family may occupy a position in a gene hierarchy where differences in gene regulation or function can be correlated with evolutionary diversity of eye development.
Stellenwert von Biologics in der Psoriasis‐Therapie: Ein Konsensus‐Papier der Arbeitsgruppe Psoriasis, Arbeitsgemeinschaft dermatologische Forschung
Authors: Boehncke Wolf‐Henning , Friedrich Markus , Mrowietz Ulrich , Reich Kristian , Rosenbach Thomas , Sticherling Michael , Thaçi Diamant
Published: September 2003

Aufgrund der Schwere ihres Krankheitsbildes benötigen etwa 20 % aller Psoriasis‐Patienten eine Photo‐ und/oder eine systemische Therapie. Probleme der entsprechenden etablierten Therapieformen bezüglich unerwünschter Wirkungen, Kontraindikationen, Therapieresistenz und fehlende Langzeitwirkung i. S. einer „remittive therapy” unterstreichen die Notwendigkeit der Entwicklung verbesserter Therapeutika zur Behandlung der Psoriasis. In den letzten Jahren wurden die technischen Voraussetzungen geschaffen, um therapeutische Moleküle aus lebenden Zellen zu gewinnen, die gezielt krankheitsrelevante Mediatoren oder Zell‐Zell‐Interaktionen inhibieren können. Mehrere dieser sog. Biologics haben das Potential, die Therapiemöglichkeiten bei mittelschwerer bis schwerer Psoriasis entscheidend zu verbessern. Hier stellt die Arbeitsgruppe Psoriasis der Arbeitsgemeinschaft Dermatologische Forschung (ADF) den aktuellen Stand der Psoriasistherapie dar. Vor diesem Hintergrund werden die Eigenschaften diesbezüglich aktuell relevanter Biologics diskutiert. Der Fokus liegt auf deren potentiellem medizinischen Nutzen sowie für die praktische Anwendung wichtigen Sicherheitsaspekten. Daneben wird auf juristische und gesundheitsökonomische Aspekte eingegangen, die ebenfalls Einfluß auf den Einsatz der Biologics haben.
Pathomechanismen der Auslösephase der allergischen Kontaktdermatitis
Authors: Riemann Helge , Schwarz Thomas , Grabbe Stephan
Published: September 2003

Die allergische Kontaktdermatitis (ACD) ist eine spezifische durch T‐Zellen vermittelte entzündliche Reaktion auf wiederholte Exposition mit Allergenen. Für die Manifestation der ACD sind zwei immunologisch unterschiedliche und aufeinanderfolgende Schritte notwendig: In der Sensibilisierungsphase werden naive T‐Zellen aktiviert und differenzieren in Antigen‐/Allergen‐spezifische Gedächtnis‐ bzw. Effektor‐Zellen. In der Auslösephase führt der erneute Kontakt mit dem selben Allergen zur örtlichen Aktivierung dieser spezifischen T‐Zellen, die zytotoxisch wirken, Zytokine freisetzen und somit weitere Entzündungszellen rekrutieren. Diese Vorgänge führen schließlich zu einer klinisch erkennbaren Entzündungsreaktion, die durch Ödem, Erythem, Schuppung und Vesikulation gekennzeichnet ist. Für den Kliniker ist vor allem die Auslösephase von großer Bedeutung, weil die Sensibilisierungsphase im allgemeinen asymptomatisch verläuft, die Auslösephase aber zur klinischen Manifestation der ACD führt. Genaue Kenntnisse über die Mechanismen der Auslösephase sind daher Voraussetzung für die Entwicklung neuer therapeutischer Strategien.
Efficacy of superficial and deep regional hyperthermia combined with systemic chemotherapy and radiotherapy in metastatic melanoma
Authors: Richtig E. , Hoff M. , Rehak P. , Kapp K. , Hofmann‐Wellenhof R. , Zalaudek I. , Poschauko J. , Uggowitzer M. , Kohek P. , Smolle J.
Published: September 2003

Background and Objective: Response rates of cutaneous‐subcutaneous or lymph node metastases of melanoma to systemic chemotherapy are rather low. We report our clinical experience with superficial and deep regional hyperthermia in combination with radiotherapy and/or chemotherapy with carboplatin.

Patients/Methods: We treated 15 patients with metastatic melanoma (6 men, 9 women; age 39 – 84 years, mean age 60 years) by using superficial or deep regional hyperthermia produced by electromagnetic energy. Superficial hyperthermia was delivered to skin or lymph node metastases in combination with radiochemotherapy in 12 patients, while deep regional hyperthermia was administered with an annular array applicator to lymph node metastases either in combination with radiochemotherapy (1 patient) or with carboplatin alone (2 patients). The clinical response was assessed by clinical evaluation and/or computer tomography and/or ultrasonography at monthly intervals.

Results. Both superficial and deep regional hyperthermia was well tolerated. We observed 5 complete local remissions (34 %), 6 partial local remissions (40 %) and 2 patients with stable disease (13 %). The best results were obtained in cutaneous or retroperitoneal metastases.

Conclusions. Local response can be achieved in inoperable metastatic melanoma using superficial or deep regional hyperthermia in combination with radiochemotherapy or chemotherapy.
Sensibilisierung auf Teebaumöl in Deutschland und Österreich – Eine multizentrische Studie der Deutschen Kontaktallergiegruppe
Authors: Pirker C. , Hausen B. M. , Uter W. , Hillen U. , Brasch J. , Bayerl C. , Lippert U. , Fuchs Th. , Aberer W. , Fartasch M. , Tebbe B. , Richter G. , Kinaciyan T. , Frosch P. J.
Published: September 2003

Hintergrund und Fragestellung:Teebaumöl, ein Destillationsprodukt der Blätter des australischen TeebaumesMelaleuca alternifolia, erfreut sich zunehmender Beliebtheit als Alternativheilmittel für die Behandlung diverser Hauterkrankungen. Das Öl ist ein Gemisch aus zahlreichen allergologisch relevanten Substanzen wie Monoterpenen und Sesquiterpenen. In dieser multizentrischen Studie sollte evaluiert werden, ob die Zunahme des Verbrauches von Teebaumöl zu einer Sensibilisierungshäufigkeit in Deutschland und Österreich geführt hat, die die Aufnahme in die Standardreihe rechtfertigen würden.

Patienten und Methode:Für die Epikutantestung wurde ein standardisiertes Teebaumöl, 5 % in Diethylphthalat (DEP), verwendet. Getestet wurden konsekutive Ekzem‐Patienten von 11 Hautkliniken in Deutschland und Österreich. Die Ablesung erfolgte nach zwei und drei Tagen gemäß den Empfehlungen der Deutschen Kontaktallergiegruppe (DKG).

Ergebnisse:Von insgesamt 3 375 getesteten Patienten reagierten 36 (1,1 %) positiv auf Teebaumöl. Die Sensibilisierungshäufigkeit zeigte große geographische Unterschiede von 2,3 % (Dortmund), 1,7 % (Buxtehude), 1,1 % (Essen), 0,7 % (Graz) bis 0 % (Berlin, Wien). 14/36 Patienten (38,9 %) zeigten auch eine positive Reaktion auf Terpentin.

Schlußfolgerung:Für einzelne Testzentren ist Teebaumöl ein wichtiges Allergengemisch. Bei anamnestischen Hinweisen über die Anwendung teebaumölhaltiger Produkte sollte es getestet werden. Angesichts der großen regionalen Unterschiede in der Sensibilisierungshäufigkeit ist die Aufnahme in die Standardreihe noch nicht zu empfehlen.
Chaotic atomic tunneling between two periodically driven Bose–Einstein condensates
Authors: Xie Qiongtao , Hai Wenhua , Chong Guishu
Published: August 2003

The chaotic coherent atomic tunneling between two periodically driven and weakly coupled Bose–Einstein condensates has been investigated. The perturbed correction to the homoclinic orbit is constructed and its boundedness conditions are established that contain the Melnikov criterion for the onset of chaos. We analytically reveal that the chaotic coherent atomic tunneling is deterministic but not predictable. Our numerical calculation shows good agreement with the analytical result and exhibits nonphysically numerical instability. By adjusting the initial conditions, we propose a method to control the unboundedness, which leads the quantum coherent atomic tunneling to predictable periodical oscillation.
Relaxation of finite perturbations: Beyond the fluctuation-response relation
Authors: Boffetta G. , Lacorata G. , Musacchio S. , Vulpiani A.
Published: August 2003

We study the response of dynamical systems to finite amplitude perturbation. A generalized fluctuation-response relation is derived, which links the average relaxation toward equilibrium to the invariant measure of the system and points out the relevance of the amplitude of the initial perturbation. Numerical computations on systems with many characteristic times show the relevance of the above-mentioned relation in realistic cases.
Traveling fronts in an array of coupled symmetric bistable units
Authors: Pazó Diego , Pérez-Muñuzuri Vicente
Published: August 2003

Traveling fronts are shown to occur in an array of nearest-neighbor coupled symmetric bistable units. When the local dynamics is given by the Lorenz equations we observe the route: standing→oscillating→traveling front, as the coupling is increased. A key step in this route is a gluing bifurcation of two cycles in cylindrical coordinates. When this is mediated by a saddle with real leading eigenvalues, the asymptotic behavior of the front velocity is found straightforwardly. If the saddle is focus-type instead, the front’s dynamics may become quite complex, displaying several oscillating and propagating regimes and including (Shil’nikov-type) chaotic front propagation. These results stand as well for other nearest-neighbor coupling schemes and local dynamics.
Efficient simulation of three-dimensional anisotropic cardiac tissue using an adaptive mesh refinement method
Authors: Cherry Elizabeth M. , Greenside Henry S. , Henriquez Craig S.
Published: August 2003

A recently developed space–time adaptive mesh refinement algorithm (AMRA) for simulating isotropic one- and two-dimensional excitable media is generalized to simulate three-dimensional anisotropic media. The accuracy and efficiency of the algorithm is investigated for anisotropic and inhomogeneous 2D and 3D domains using the Luo–Rudy 1 (LR1) and FitzHugh–Nagumo models. For a propagating wave in a 3D slab of tissue with LR1 membrane kinetics and rotational anisotropy comparable to that found in the human heart, factors of 50 and 30 are found, respectively, for the speedup and for the savings in memory compared to an algorithm using a uniform space–time mesh at the finest resolution of the AMRA method. For anisotropic 2D and 3D media, we find no reduction in accuracy compared to a uniform space–time mesh. These results suggest that the AMRA will be able to simulate the 3D electrical dynamics of canine ventricles quantitatively for 1 s using 32 1-GHz Alpha processors in approximately 9 h.
The largest Lyapunov exponent of chaotic dynamical system in scale space and its application
Authors: Liu Hai-Feng , Yang Yong-Zhe , Dai Zheng-Hua , Yu Zun-Hong
Published: August 2003

The largest Lyapunov exponent is an important invariant of detecting and characterizing chaos produced from a dynamical system. We have found analytically that the largest Lyapunov exponent of the small-scale wavelet transform modulus of a dynamical system is the same as the system’s largest Lyapunov exponent, both discrete map and continuous chaotic attractor with one or two positive Lyapunov exponents. This property has been used to estimate the largest Lyapunov exponent of chaotic time series with several kinds of strong additive noise.
Convective instability of He3–4He superfluid mixtures heated from below
Authors: Zadorozhko A. A. , Kalko T. V. , Rudavskskiı̆ É. Ya. , Chagovets V. K. , Sheshin G. A.
Published: August 2003

The convective thermal instability of He3–4He superfluid mixtures on heating from below is studied in the temperature interval 100–500 mK in mixtures with an initial concentration of 9.8% He3. It is found that at certain critical values of the power of the heat flux in the mixture there is a change in character of the heat transfer, indicating the onset of convective heat transfer. The critical temperature gradients associated with the onset of convection correspond to Rayleigh numbers many orders of magnitude greater than the Rayleigh numbers in the heating of the mixtures from above. The results are analyzed in the framework of the theory of the convective instability of binary mixtures.
Critical current of asymmetric SFIFS tunnel structures
Authors: Koshina E. A. , Krivoruchko V. N.
Published: August 2003

The physics of critical current inversion (π state of the junction) and enhancement in SFIFS tunnel junctions (S and F are superconducting and ferromagnetic metals, and I is an insulator) is discussed on the basis of a microscopic theory of the proximity effect. The ground state and the critical current of an asymmetric (SF)LI(FS)R junction with a strong ferromagnetic field on one of its “banks” are investigated. It is shown that SFINS junctions with strong magnetism of the F layer are found in a ground state with a ±π/2 difference of the superconducting phases on the banks (N is a normal nonmagnetic metal). The dependence of the dc Josephson effect on temperature and on the angle between the magnetic moments of the F layers in SFIFS junctions is investigated.
Changes of the IR spectrum and hydrogen bond enthalpy in thin-film water cryocondensates
Authors: Drobyshev A. , Aldijarov A. , Abdykalykov K. , Panchenko G.
Published: August 2003

Measurements of the IR spectra are made on thin-film water cryovacuum condensates formed on a metal substrate in the temperature range 16–200 K. It is found that the frequency of molecular stretching vibrations are shifted to lower frequencies with increasing temperature; this is explained by a weakening of the hydrogen bond. A calculation of the change in H-bond enthalpy shows that this change is larger for thinner samples. A fine structure of the librational bands of intramolecular protonic transitions in the cryocondensate is revealed. It may be due to the different orientations of the molecules relative to the internal field in samples formed at different temperatures.
Thermodynamics of a one-dimensional generalized Wigner crystal
Authors: Slavin V. V.
Published: August 2003

The thermodynamic characteristics of a one-dimensional generalized Wigner crystal are investigated for arbitrary temperature, particle density, and character of the interparticle repulsive pair potential. A method is proposed which permits calculating the partition function of the system with allowance for the interaction between an arbitrary number of neighboring particles. It is shown that increasing this number leads to the appearance of increasingly fine steps in the low-temperature dependence of the particle density on the chemical potential. These steps are remnants of a dependence of the “devil’s staircase” type that is characteristic for this sort of system at zero temperature.
On the estimate of the stochastic layer width for a model of tracer dynamics
Authors: Trueba José L. , Baltanás José P. , Feudel Fred , Sanjuán Miguel A. F.
Published: August 2003

An analytical estimate of the width of the generated chaotic layer in a time-periodically driven stream function model for the motion of passive tracers is discussed. It is based essentially on the method of the separatrix map and the use of the Melnikov theory. Energy–time variables are used to derive lower bounds for the half width of the layer. In order to perform a comparison with numerical simulations, the results are transformed into space variables. The analytic results of the layer thickness in both parallel and perpendicular directions to the shear flow are compared with numerical computations and some systematic deviations are discussed.
Geometry and topology of escape. II. Homotopic lobe dynamics
Authors: Mitchell K. A. , Handley J. P. , Delos J. B. , Knudson S. K.
Published: August 2003

We continue our study of the fractal structure of escape-time plots for chaotic maps. In the preceding paper, we showed that the escape-time plot contains regular sequences of successive escape segments, called epistrophes, which converge geometrically upon each end point of every escape segment. In the present paper, we use topological techniques to: (1) show that there exists a minimal required set of escape segments within the escape-time plot; (2) develop an algorithm which computes this minimal set; (3) show that the minimal set eventually displays a recursive structure governed by an “Epistrophe Start Rule:” a new epistrophe is spawned Δ=D+1 iterates after the segment to which it converges, where D is the minimum delay time of the complex.
Chaotic bursting as chaotic itinerancy in coupled neural oscillators
Authors: Han Seung Kee , Postnov D. E.
Published: August 2003

We show that chaotic bursting activity observed in coupled neural oscillators is a kind of chaotic itinerancy. In neuronal systems with phase deformation along the trajectory, diffusive coupling induces a dephasing effect. Because of this effect, an antiphase synchronized solution is stable for weak coupling, while an in-phase solution is stable for very strong coupling. For intermediate coupling, a chaotic bursting activity is generated. It is a mixture of three different states: an antiphase firing state, an in-phase firing state, and a nonfiring resting state. As we construct numerically the deformed torus manifold underlying the chaotic bursting state, it is shown that the three unstable states are connected to give rise to a global chaotic itinerancy structure. Thus we claim that chaotic itinerancy provides an alternative route to chaos via torus breakdown.