julilili42/papers huggingface dataset:
Limit theorems for isotropic random walks on triangle buildings
2002-12-01

Abstract The spherical functions of triangle buildings can be described in terms of certain two-dimensional orthogonal polynomials on Steiner's hypocycloid which are closely related to Hall-Littlewood polynomials. They lead to a one-parameter family of two-dimensional polynimial hypergroups. In this paper we investigate isotropic random walks on the vertex sets of triangle buildings in terms of their projections to these hypergroups. We present strong laws of large numbers, a central limit theorem, and a local limit theorem; all these results are well-known for homogeneous trees. Proofs are based on moment functions on hypergroups and on explicit expansions of the hypergroup characters in terms of certain two-dimensional Tchebychev polynimials.
Reorganization of Speech Production at the Motor Cortex and Cerebellum following Capsular Infarction: a Follow-up Functional Magnetic Resonance Imaging Study
2002-12-01

Based on clinical data, Geschwind assumed left hemisphere dominance of speech production to extend to the cortical representation of articulatory and phonatory functions at the motor cortex. This author suggested, furthermore, that the clinical observation of rapid recovery from articulatory impairments after damage to the left-sided corticobulbar tracts reflects compensatory activation of an alternative pathway involving the contralateral pre-central gyrus and its efferent projections. In order to test this hypothesis, functional magnetic resonance imaging (fMRI) was performed 4 and 35 days after stroke in a 38-year-old man who had experienced sudden speech deterioration ('dysarthric speech') concomitant with weakness of the right upper limb and the right side of the face. Computerized tomography demonstrated an ischaemic infarction within the left internal capsule. The patient fully recovered from dysarthria within 9 days. Activation of the right hemisphere analogues of Broca and Wernicke areas has been assumed to contribute to recovery from aphasia. As a further aspect of the reorganization of speech function, the present case study demonstrates for the first time by means of fMRI a selective 'shift' of the cortical representation of speech motor control to the right Rolandic cortex and the left cerebellum during restitution of articulation in a case of transient dysarthria following infarction of the left internal capsule.
Cell Microarrays: An Emerging Technology for the Characterization of Antibodies
2002-12-01

The possibility to miniaturize and parallelize biological assays has a great impact on the development of biomedical technologies. Here, we describe a simple, miniaturized, and parallelized method employing entire cells from different cell lines displaying a protein of interest on their surface, which were immobilized on a microarray slide. Antibodies were added to these cellular microarrays, and their specific binding to the cell surface proteins was monitored using appropriate fluorescently labeled detection molecules. This new method is applicable for rapidly screening cell surface-specific antibodies with respect to selectivity and cross-reactivity.
Effect of Glimepiride on Insulin-Stimulated Glycogen Synthesis in Cultured Human Skeletal Muscle Cells
2002-12-01

OBJECTIVE—To examine the effect of glimepiride on insulin-stimulated glycogen synthesis in cultured human skeletal muscle cells in comparison with glibenclamide. RESEARCH DESIGN AND METHODS—Myotubes derived from glucose-tolerant subjects were incubated with glimepiride or glibenclamide (0–100 μmol/l) for 4 h and with or without insulin (100 nmol/l) for 2 h, and subsequently glycogen synthesis was determined. RESULTS—Glimepiride had no significant effect on basal glycogen synthesis; in contrast, glimepiride caused a dose-dependent increase of insulin-stimulated glycogen synthesis, with a maximal effect of 39.97 ± 8.4% (mean ± SEM, n = 4, P &amp;lt; 0,02). The time course of this glimepiride effect on insulin-stimulated glycogen synthesis showed a peak after 12 h incubation with a half maximal effect after 4 h. Preincubation of the myotubes with wortmannin (100 nmol/l), an inhibitor of phosphatidylinositol (PI)- 3 kinase, caused an inhibition of this glimepiride effect on insulin-stimulated glycogen synthesis. In contrast to glimepiride, incubation of myotubes with glibenclamide (0–100nmol/l), a second generation sulfonylurea, had no significant effect on basal or insulin-stimulated glycogen synthesis. CONCLUSIONS—Incubation of cultured human skeletal muscle cells derived from glucose-tolerant subjects with glimepiride caused a dose-dependent increase of insulin-stimulated glycogen synthesis using therapeutic glimepiride concentrations. This glimepiride effect seems to be mediated via the PI3 kinase pathway. In contrast to glimepiride, glibenclamide had no significant effect on basal or insulin-stimulated glycogen synthesis. These results suggest that glimepiride, beside its well-known effect to stimulate insulin secretion, possess an insulin-sensitizing action in cultured human skeletal muscle cells in support of the concept of an extrapancreatic action of glimepiride.
Pharmacokinetic modelling of morphine, morphine‐3‐glucuronide and morphine‐6‐glucuronide in plasma and cerebrospinal fluid of neurosurgical patients after short‐term infusion of morphine
2002-12-01

Aims Concentrations in the cerebrospinal fluid (CSF) are a useful approximation to the effect site for drugs like morphine. However, CSF samples, are available only in rare circumstances. If they can be obtained they may provide important insights into the pharmacokinetics/pharmacodynamics of opioids. Methods Nine neurological and neurosurgical patients (age 19–69 years) received 0.5 mg kg −1 morphine sulphate pentahydrate as an intravenous infusion over 30 min. Plasma and CSF were collected for up to 48 h. Concentration time‐course and interindividual variability of morphine (M), morphine‐3‐glucuronide (M3G) and morphine‐6 glucuronide (M6G) were analysed using population pharmacokinetic modelling. Results While morphine was rapidly cleared from plasma (total clearance = 1838 ml min −1 (95% CI 1668, 2001 ml min −1 )) the glucuronide metabolites were eliminated more slowly (clearance M3G = 44.5 ml min −1 (35.1, 53.9 ml min −1 ), clearance M6G = 42.1 ml min −1 (36.4, 47.7 ml min −1 )) and their clearance could be described as a function of creatinine clearance. The central volumes of distribution were estimated to be 12.7 l (11.1, 14.3 l) for morphine. Transfer from the central compartment into the CSF was also rapid for M and considerably slower for both glucuronide metabolites. Maximum concentrations were achieved after 102 min (M), 417 min (M3G) and 443 min (M6G). A P‐glycoprotein exon 26 polymorphism previously found to be linked with transport activity could be involved in CSF accessibility, since the homozygous mutant genotype was associated ( P &lt; 0.001) with high maximum CSF concentrations of M but not M3G or M6G. Conclusions From the population pharmacokinetic model presented, CSF concentration profiles can be derived for M, M3G and M6G on the basis of dosing information and creatinine clearance without collecting CSF samples. Such profiles may then serve as the link between dose regimen and effect measurements in future clinical effect studies.
Low antibody responses to variant surface antigens of Plasmodium falciparum are associated with severe malaria and increased susceptibility to malaria attacks in Gabonese children.
2002-12-01

We measured the levels of IgG antibodies with specificity for the variant surface antigens (VSA) of Plasmodium falciparum in plasma samples from a cohort of Gabonese children participating in a longitudinal case-control malaria study. Children with mild malaria had significantly higher anti-VSA IgG responses than their matched counterparts with severe malaria, most markedly during convalescence and when they were healthy. Over the course of the study, almost twice as many children who presented initially with mild rather than severe malaria developed antibodies recognizing the VSA expressed by each of a panel of three isolates, and those with the highest anti-VSA IgG responses had the lowest malaria attack rates. The results suggest that the clinical outcome of P. falciparum infection in young African children depends on their ability to both develop and maintain a broad profile of anti-VSA IgG antibodies, and that this ability is diminished in children who have experienced a severe malaria attack.
Coding of Sound Intensity in the Chick Cochlear Nerve
2002-12-01

Tuning curves, spontaneous activity, and rate-intensity (RI) functions were obtained from units in the chick cochlear nerve. The characteristic frequency (CF) was determined from each tuning curve. The shape of each RI function was subjectively evaluated and assigned to one of four RI types. The breakpoint, discharge rate at the highest SPLs, and slopes of the primary and secondary segments were quantified for each function. The CF and RI type were then related to these variables. A new RI function was observed in which the discharge activity in the secondary segment diminished as stimulus level increased above the breakpoint. This function was called a “sloping-down” type. In 959 units, saturating, sloping-up, sloping-down, and straight RI types were identified in 39.2, 35.5, 12.6, and 12.7% of the sample, respectively. The slope of the primary segment was nearly the same in each of the four types and averaged 5.48 S · s −1 · dB −1 across all units. The slopes of the secondary segments formed four groupings when segregated by RI type based on the subjective assignments and averaged 0.03, 1.22, −0.90, and 3.95 S · s −1 · dB −1 in the saturating, sloping-up, sloping-down, and straight types, respectively. The data describing the secondary segments of all units were fit with a multi-compartment polynomial and showed a continuous distribution that segregated, with some overlap, into the different RI categories. The proportion of RI types, as well as the secondary and primary slopes were approximately constant across CFs. In addition, it would appear that the other parameters that define the four types were, for the most part, homogeneously distributed across the frequency axis of the chick inner ear. Finally, a comparison of RI functions having a common CF suggested that the compressive nonlinearity that determines RI type may be a phenomenon localized to individual hair cells in the bird ear.
3D QSAR of Serotonin Transporter Ligands: CoMFA and CoMSIA Studies
2002-12-01

Abstract The main purpose of this study was the investigation of quantitative structure‐activity relationships of serotonin transporter ligands with regard to the future development of potential new and selective PET radiotracers for the serotonin transporter. A heterogeneous data set of 19 selective and non‐selective serotonin reuptake inhibitors was used. Affinity data for both the serotonin transporter and the norepinephrine transporter was available. As a necessary prerequisite for our 3D QSAR studies a reasonable alignment of the compounds was developed using GASP. It was based on an existing pharmacophore model. In addition to the widely used CoMFA method, the somewhat newer CoMSIA method was applied. Statistically reliable CoMFA models for both the serotonin transporter (q 2 =0.538) and the norepinephrine transporter (q 2 =0.445) were developed, further improving the internal predictability by applying region focusing for the serotonin transporter (q 2 =0.674). These models were compared with the CoMSIA models for the serotonin and the norepinephrine transporter that yielded comparable cross‐validated correlation coefficients (q 2 =0.531 and q 2 =0.502, respectively). Certain structural features that are distinctive of each transporter and important for high binding affinity were identified. Highly comparable results were obtained for CoMFA and CoMSIA. Both methods were applied to elucidate structural requirements for serotonin transporter selectivity. The resulting CoMSIA map provides important information for lead optimization with respect to selectivity enhancement.
Dominances in Finger Arteries
2002-12-01

We studied the patterns of dominance in the palmar digital arteries of the fingers in 39 fresh cadaver arms which had been injected with coloured latex solution. We also performed photoplethysmographic studies in 20 hands. The ulnar digital artery in the index finger and the radial digital artery of the little finger were usually dominant, and their counterparts were slim and often hypoplastic. The findings are relevant to digit revascularization and might influence the planning of digital island-flaps or toe transfers.
OCCURRENCE OF LOW-Ti AND HIGH-Ti FREUDENBERGITE IN ALKALI SYENITE DIKES FROM THE KATZENBUCKEL VOLCANO, SOUTHWESTERN GERMANY
2002-12-01

La freudenbergite (Na 2 Fe 3 + 2 Ti 6 O 1 6 ) est presente dans des filons de syenite hyperalcaline a Katzenbuckel, dans le sud-ouest de l'Allemagne, en association avec lorenzenite, pyrochlore, landauite et des silicates de Na-Zr comme manifestations tardives de cristallisation. Elle montre un intervalle de composition important; nous en documentons deux varietes: 1) une variete a teneur en Ti relativement faible, avec tout le fer sous forme trivalente, ce qui a ete confirme par spectroscopie de Mossbauer; il s'agit de la freudenbergite normale rencontree dans la syenite de Katzenbuckel; 2) une variete a concentrations elevees de Ti et de cations bivalents (Mg 2 + , Mn 2 + , Zn 2 + ) a la place de Fe 2 + . Des niveaux accrus de Nb sont la cause d'un deficit de sodium dans le site A. La freudenbergite, en cristaux atteignant 0.75 mm, montre une zonation en secteurs, avec un enrichissement selectif en (Nb + Zr) et Ti dans les secteurs (001) et (100), respectivement. Dans un filon (Kb 45), la freudenbergite remplace par metasomatose l'ilmenite primaire, de meme que de minces lamelles d'exsolution au sein de cristaux d'hematite. La pseudobrookite, l'ilmenite, l'hematite ou la magnetite sont les oxydes de Fe-Ti presents dans les echantillons de syenite porteurs de freudenbergite. Les paires ilmenite-hematite font preuve de larges lacunes de miscibilite, et indiquent une cristallisation sur l'intervalle 750-550°C a faible pression, environ 0.2-0.3 kbar. Le developpement unique de la freudenbergite primaire serait surtout du a un processus efficace de fractionnement d'un liquide syenitique a nepheline, ce qui a mene a un liquide evolue riche en Na et Ti, mais depourvu de Ca, et anormalement enrichi en niobium et en zirconium.
Microcirculation in Chronic Venous Insufficiency
2002-12-01

Objective: To study the microcirculation of the skin of the leg in patients with chronic venous disease of the lower limb, and to assess the effect of compression treatment. Patients and Methods: Patients were recruited from the vascular clinic and investigated by direct capillary pressure, transcutaneous oxygen tension, intravital video capillaroscopy and fluorescence video microscopy. The microcirculation was observed over the healing period in patients with venous leg ulcers. The effects of compression therapy on microcirculatory changes were studied in patients with Widmer stage I and II chronic venous disease. Results: In patients suffering from lipodermatosclerosis or venous leg ulcers retrograde pressure waves were detected in the nutritive capillaries of the skin by the ‘servo nulling’ pressure measurement during simulated calf muscle contraction. A close correlation was found between the degree of trophic skin change and the microangiopathy observed. Healing of venous ulcers occurred only if the cutaneous microcirculation in the ulcer area improved. Capillary density in base of the ulcer and at the border predicted venous ulcer healing. Conclusions: Cutaneous microangiopathy precedes the development of trophic skin alterations due to chronic venous disease and microcirculatory changes are closely related to the clinical stage of the disease as well as to the outcome of treatment.
Neurons of the superior olivary complex do not excite startle-mediating neurons in the caudal pontine reticular formation
2002-12-01

The acoustic startle response is an important mammalian model for studying the cellular mechanisms of emotions and learning. Lesions in the superior olivary complex have been shown to attenuate the amplitude of the acoustic startle response, thus a substantial contribution of these neurons to the startle response was proposed. We here explored the putative connection of olivary neurons to the startle-mediating giant neurons in the reticular formation in rat brain slices in vitro. Tracing studies and electrical stimulation in the superior olivary complex revealed a strong connection; however it was not possible to distinguish between olivary neurons and traversing auditory fibres. Glutamate uncaging in the olivary complex excited a subpopulation of olivary neurons but never PnC giant neurons, as shown by patch-clamp recordings. This clearly contradicts an excitatory connection from olivary neurons to PnC giant neurons and thus an involvement of the superior olivary complex in eliciting a startle response.
Clinically significant persistence and enlargement of an antenatally diagnosed isolated choroid plexus cyst
2002-12-01

Abstract Isolated choroid plexus cysts are usually diagnosed at the time of screening ultrasonography during the second trimester. While they raise the question of underlying chromosomal abnormalities, their clinical course is almost invariably benign with complete resolution often by the third trimester. We report the highly unusual case of a choroid plexus cyst diagnosed at 14 weeks of gestational age with subsequent further enlargement of the cyst,necessitating postpartum neurosurgical intervention. Copyright © 2002 International Society of Ultrasound in Obstetrics and Gynecology
Early Restitution of Electrocorticogram Predicts Subsequent Behavioral Recovery from Cardiac Arrest
2002-12-01

Previous studies have shown that parameters of EEG restitution reflect the severity of global hypoxic-ischemic brain injury. Here, the hypothesis is tested that patterns of EEG restitution during the first 4 hours predict later behavioral recovery. Time course and correlations between behavior, electrocorticogram (EcoG), and neuronal injury were investigated in a rodent model of asphyctic cardiac arrest. Forty Wistar rats were subjected to 5 minutes of asphyxia and cardiopulmonary resuscitation. Behavior was assessed by repeated scoring of neurodeficits and open field activity until euthanasia at 48 hours. Electrocorticographic bursting occurred at 13.2 +/- 4 minutes after resuscitation. Bursts increased in frequency and duration until the EcoG reverted to a continuous signal. The resuscitation-continuous EcoG interval correlated with the first appearance of spontaneous movements (r = 0.80, P < 0.05). Larger intervals were associated with hyperactivity in the open field at 24 hours (r = 0.61, P < 0.05), indicating a more severe behavioral deficit. Larger intervals were also associated with worse 48-hour neurodeficit scores (P < 0.05). Neuronal damage in the hippocampus correlated with the degree of open field hyperactivity at 14 hours (P < 0.05). These findings demonstrate a close temporal and prognostic relationship between electrical and behavioral recovery after hypoxic-ischemic brain injury.
Statins and menopausal health
2002-12-01

Cardiovascular disease is associated with high morbidity and mortality. Cholesterol-lowering statins can reduce health risks both in men and women. While this benefit has thus far been attributed to the lipid-lowering effects of these drugs, the importance of their direct actions on vascular tissue is gaining more recognition. Furthermore, recent studies suggest that statins might also be effective in preventing osteoporosis and Alzheimer's disease. Equally interesting are experimental results showing that statins may inhibit growth of certain malignancies such as the breast. When statins are combined with hormone replacement therapy (HRT), even greater beneficial effects on the lipid profile can be obtained. To our knowledge we have investigated for the first time direct vascular effects by combining statins with HRT. We were able to identify significant beneficial effects on endothelial function and vascular smooth muscle proliferation. In the context of current discussions on the benefits and risks of HRT in treating patients with pre-existing cardiovascular disease, it appears particularly important that interventional studies should be conducted to evaluate the therapeutic relevance of statin/HRT combinations. At present, this is the most important conclusion drawn from the data collected thus far on the combination of these two drug types. There is some evidence suggesting drug-specific effects, particularly adverse reactions and statin interactions, which should be considered when using this combination therapy.
Quantification of the influence of soil conditions on atrazine degradation rates
2002-12-01

Atrazine degradation rates are known to vary in dependence of a range of environmental factors. In the present study we used statistical techniques to identify the major dependencies and to quantify these relationships. It was found that atrazine degradation rates can be related to depth, organic carbon content, and redox potential. Furthermore, the effects of previous treatment, carbon amendment, and saturation were quantified. The statistical models are based upon a vast number of observations, and therefore are expected to be more reliable than existing atrazine degradation models. The two major factors in atrazine degradation were identified to be the availability of substrate and the oxidation state of the soil. The here found model for redox dependent degradation of atrazine can now be incorporated into rate expressions that are used in biogeochemical transport models where the redox-state is routinely computed.
Skin Grafting of Venous Ulcers: A Review of its Current Role
2002-12-01

As a therapeutic option, grafting of venous ulcers has not been very successfully received despite the different types of grafting methods. Currently, there are only a few controlled randomized trials offering clear guidance to clinicians. The development of artificially bioengineered skin constructs has led to a renewed interest in wound bed preparation, and preliminary successes suggest that the role of skin grafting could be studied in the current context.
Reconstruction of extended cortical sources for EEG and MEG based on a Monte‐Carlo‐Markov‐chain estimator
2002-12-02

Abstract A new procedure to model extended cortical sources from EEG and MEG recordings based on a probabilistic approach is presented. The method (SPMECS) was implemented within the framework of maximum likelihood estimators. Neuronal activity generating EEG or MEG signals was characterized by the number of sources and their location and extension. Based on the noise distribution of the measured data, source configurations were associated with the according value of the likelihood function. To find the most likely source, i.e., the maximum likelihood estimator, and its level of confidence, a stochastic solver (Metropolis algorithm) was applied. The method presented supports the incorporation of virtually any constraint, e.g., based on physiological and anatomical a priori knowledge. Thus, ambiguity of the ill‐posed inverse problem was reduced considerably by confining sources to the cortical surface extracted from individual MR images. The influence of different levels and types of noise on the outcome was investigated by means of simulations. Somatosensory evoked magnetic fields analyzed by the method presented suggest that larger extended cortical areas are involved in the processing of combined finger stimulation as compared to single finger stimulation. Hum. Brain Mapping 18:100–110, 2003. © 2002 Wiley‐Liss, Inc.