Evidence for the involvement of the posterior parietal cortex in coordination of fingertip forces for grasp stability in manipulation

Grasp stability during object manipulation is achieved by the grip forces applied normal to the grasped surfaces increasing and decreasing in phase with increases and decreases of destabilizing load forces applied tangential to the grasped surfaces. This force coordination requires that the CNS anticipates the grip forces that match the requirements imposed by the self-generated load forces. Here, we use functional MRI (fMRI) to study neural correlates of the grip-load force coordination in a grip-load force task in which six healthy humans attempted to lift an immovable test object held between the tips of the right index finger and thumb. The recorded brain activity was compared with the brain activity obtained in two control tasks in which the same pair of digits generated forces with similar time courses and magnitudes; i.e., a grip force task where the subjects only pinched the object and did not apply load forces, and a load force task, in which the subjects applied vertical forces to the object without generating grip forces. Thus neither the load force task nor the grip force task involved coordinated grip-load forces, but together they involved the same grip force and load force output. We found that the grip-load force task was specifically associated with activation of a section of the right intraparietal cortex, which is the first evidence for involvement of the posterior parietal cortex in the sensorimotor control of coordinated grip and load forces in manipulation. We suggest that this area might represents a node in the network of cortical and subcortical regions that implement anticipatory control of fingertip forces for grasp stability.     

Engagement of gaze in capturing targets for future sequential manual actions

We investigated the role of saccadic gaze fixations in encoding target locations for planning a future manual task consisting of a sequence of discrete target-oriented actions. We hypothesized that fixations of the individual targets are necessary for accurate encoding of target locations and that there is a transfer of sequence information from visual encoding to manual recall. Subjects viewed four targets presented at random positions on a screen. After various delays following target extinction, the subjects marked the remembered target locations on the screen with the tip of a hand-held stick. When the targets were presented simultaneously among distracting elements, the overall accuracy of marking increased with presentation time and total number of targets fixated because the subjects had to serially fixate the individual targets to locate them. Without distractors, the marking accuracy was similarly high regardless of duration of target presentation (0.25-8 s) and number of targets fixated; it was comparable to that with distractors when all four targets had been fixated. This indicates parallel encoding of target locations largely based on peripheral vision. Location memory was stable in these tasks over the delay periods investigated (0.5-8 s). With parallel encoding there was a "shrinkage" in the visuomotor transformation, i.e., the distances between the markings were systematically smaller than the corresponding inter-target distances. When the targets were presented sequentially without distractors, marking accuracy improved with the total number of targets fixated and shrinkage in the visuomotor transformation occurred only with parallel encoding, i.e., when subjects did not fixate the targets. In all experimental conditions for trials in which targets were fixated during encoding, there was little correspondence between the marking sequence and the sequence in which the targets were fixated. We conclude that subjects benefit from fixating targets for subsequent target-oriented manual actions when the targets are presented among distractors and when presented sequentially; when distinct targets are presented simultaneously against a blank background, they are efficiently encoded in parallel largely by peripheral vision.     

Recombinant congenic strains of mice from B10.D2 and DBA/2: Their contribution to behavior genetic research and application to audiogenic seizures

Recombinant congenic strains (RCS) represent a series of related strains, each of which carries a small fraction of the genome of one strain (donor strain) on the genetic background of another strain (background strain). Recombinant inbred strains (RIS) are commonly used to identify major gene segregation and linkage and associations between behavior and quantitative trait loci, whereas recombinant congenic strains (RCS) open other complementary leads. The variability in the reactivity of RCS to a trait is thus the expression of few minor-effect genes originating from the donor strain, because the probability that major genes are present in any one RCS is low. Unlike RIS in which minor-effect genes are often masked by major genes, RCS enable the effects of minor genes to be studied. With our method, for a given trait, an estimate can be made of the gene strength distribution as well as an estimate of the minimal number of genes involved having a certain strength.This study was supported by the Centre National de la Recherche Scientifique (URA 1924 and CSEAL-UPS 44, CNRS), Université René-Descartes, Paris V UFR Biomédicale, and the Fondation pour la Recherche Médicale.     

Cytotoxicity, thiol depletion and inhibition of O6-methylguanine-DNA methyltransferase by various aldehydes in cultured human bronchial fibroblasts

Lipid peroxidation aldehydes of the 4-hydroxy-, ß-unsaturatedtype, as well as the tobacco-smoke related , ß-unsaturatedaldehyde, acrolein, were highly cytotoxic and decreased theintracellular thiol content in cultured human bronchial fibroblastsafter treatment with micromolar concentrations. In comparison,formaldehyde and acetaldehyde were less toxic and 100- to 300-foldhigher doses were required to affect cell survival or thiollevels. The unsaturated aldehydes also markedly inhibited theDNA repair enzyme O⁶-methylguanine-DNA methyltransferase knownto have a cysteine residue in its active site, but had no effecton the activity of uracil-DNA glycosylase. Our results indicatethat reactive aldehydes of either exogenous or endogenous originhave direct cytotoxic effects and may also make cells more susceptibleto other toxic chemicals due to an impairment in cellular defensemechanisms, e.g., DNA repair and detoxification by systems requiringglutathione.     

A Novel HR-pQCT Image Registration Approach Reveals Sex-Specific Changes in Cortical Bone Retraction With Aging

During aging, changes in endosteal and periosteal boundaries of cortical bone occur that differ between men and women. We here develop a new procedure that uses high-resolution peripheral quantitative CT (HR-pQCT) imaging and 3D registration to identify such changes within the timescale of longitudinal studies. A first goal was to test the sensitivity of the approach. A second goal was to assess differences in periosteal/endosteal expansion over time between men and women. Rigid 3D registration was used to transform baseline and all follow-up (FU) images to a common reference configuration for which the region consisting of complete slices (largest common height) was determined. Periosteal and endosteal contours were transformed to the reference position to determine the net periosteal and endosteal expansion distances. To test the sensitivity, images from a short-term reproducibility study were used (15 female, aged 21 to 47 years, scanned three times). To test differences between men and women, images from a subset of the Geneva Retirees Cohort were used (248 female, 61 male, average age 65 years, 3.5 and 7 years FU). The sensitivity study indicated a least significant change for detecting periosteal/endosteal expansion of 41/31 microns for the radius and 17/26 microns for the tibia. Results of the cohort study showed significant net endosteal retraction only in females at the radius and tibia after 3.5 years (38.0 and 38.4 microns, respectively) that further increased at 7 years FU (70.4 and 70.8 microns, respectively). No significant net periosteal changes were found for males or females at 7 years. The results demonstrate that it is possible to measure changes in endosteal contours in longitudinal studies within several years. For the investigated cohort, significant endosteal retraction was found in females but not in males. Whether these changes in cortical geometry are related to fracture risk remains to be investigated in larger cohorts © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).     

Reported disease and psychological well-being in Swiss adults

Summary In Switzerland, and in many other countries as well, the distribution of morbidity and perceived health in the general population and their determining factors have not been systematically studied so far. This article reports an exploratory study of prevalence of two complex health indicators, longstanding disease (Disease) and psychological well-being (Well-being) and of their environmental, person-specific and behavioural determinants. Data from a health survey conducted in five cantons and three language regions as part of the Swiss Intercantonal Health Indicators Project were used. Whereas distributions of prevalence of Disease according to gender, age, level of education and place of living confirm results of other studies, unexpected prevalence patterns were found for Well-being, especially with regard to gender differences. Multivariate analyses by general linear models (independent sub-samples of the study population were used to develop and validate models) showed different sets of environmental, person-specific and behavioural factors to explain inter-individual differences of Disease and Well-being, both in the total validation sample and in sub-samples of women and men. The results are discussed with regard to implications for socioepidemiological health research.

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Zusammenfassung Wie in zahlreichen anderen Ländern so sind bisher in der Schweiz die Verteilung und die Determinanten von Morbidität und wahrgenommener Gesundheit in der Gesamtbevölkerung nicht systematisch untersucht worden. Die vorliegende Arbeit berichtet über eine explorative Studie über die Prävalenz zweier komplexer Gesundheitsindikatoren, länger andauernde Krankheit (Disease) und psychisches Wohlbefinden (Well-being), und über deren jeweilige umweltbedingte, personale und verhaltensbezogene Einflußfaktoren. Grundlage dafür waren Daten, die in einer Bevölkerungsbefragung in 5 Kantonen und 3 Sprachregionen im Rahmen des Interkantonalen Gesundheitsindikatorenprojekts (IGIPPROMES) erhoben wurden. Während die Verteilung der Prävalenz von Krankheit nach Geschlecht, Alter, Bildungsstatus und Wohnortgrösse den Ergebnissen anderer Studien entspricht, ergaben sich bei der Prävalenz von Wohlbefinden unerwartete Verteilungsmuster, insbesondere Unterschiede zwischen Frauen und Männern. Eine Analyse interindividueller Unterschiede von Krankheit und Wohlbefinden mit Hilfe eines allgemeinen linearen Modells (Modellentwicklung und Validierung an unabhängigen Teilstichproben) zeigte, dass diese durch jeweils spezifische Konstellationen von Umwelt-, Personen- und Verhaltensfaktoren erklärt werden können, sowohl in der gesamten Validierungsstichprobe als auch in den Teilstichproben für Frauen und Männer. Die Ergebnisse der Studie werden in Hinblick auf die Weiterentwicklung der sozialepidemiologischen Gesundheitsforschung diskutiert.

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Résumé En Suisse, comme dans beaucoup d'autres pays, la morbidité et le bien-être psychologique de la population générale n'ont presque pas été étudiés jusqu'à présent. Dans ce rapport, les résultats d'une étude exploratoire sur deux indicateurs complexes de santé, maladie chronique (Disease) et bien-être psychologique (Well-being) et sur les facteurs de l'environnement, de la personnalité et du comportement qui influencent ces deux indicateurs sont présentés. Cette étude faisait part du projet intercantonal sur les indicateurs de santé (IGIP-PROMES) et se base sur les données tirées d'une enquête auprès des populations de cinq cantons et trois régions linguistique de la Suisse. Tandis que la prévalence de l'indicateur «maladie» par sexe, age, degré de formation et dimension du lieu de résidence était conforme aux résultats d'autres études, des distributions inattendues de la prévalence de «bien-être psychologique», notamment des différences entre hommes et femmes ont été trouvées. Une analyse des différences entre individue de «maladie» et «bien-être» au moyen d'un modèle linéaire généralisi — le développement et l'évaluation duquel ont été faits à l'aide de deux échantillons d'occasion indépendents — a montré que des constellations spécifiques constituées de facteurs de l'environnement, de la personnalité et du comportement, peuvent expliquer ces différences, soit dans l'échantillon d'évaluation totale, soit dans les échantillons partiels de femmes et d'hommes. Ces résultats sont discutés par rapport à l'évolution de la recherche socio-épidémiologique.

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Paper presented at a symposium on The Public Health Perspective of Social and Preventive Medicine, in celebration of the 20th anniversary of the Department of Social and Preventive Medicine, University of Berne, 25 June 1992 in Berne.     

Surgical Decompression of the Eighth Nerve for Tinnitus

This article reports two cases of vascular decompression for tinnitus, both of which were successful. The pathophysiology of vascular compression syndromes in general and specifically eighth nerve vascular compression syndromes is reviewed. The anatomy of the anterior inferior cerebellar artery and its relationship to the eighth nerve complex is discussed in detail and the literature of vascular compression syndrome reviewed. Although no unequivocal definitive test procedure is available for preoperative diagnosis of vascular compression syndrome, the presence of the following features makes the diagnosis more likely: I-III interpeak latency abnormalities on auditory brain stem response (ABR), abnormalities of stapedius reflex, unilateral sensorineural hearing loss, ipsilateral electronystagmography (ENG) abnormalities, especially spontaneous nystagmus, and radiographic visualization of a vessel contacting the eighth nerve complex.     

Cationic-amphiphilic arpromidine-derived guanidines and a histamine trifluoromethyl-toluidide derivative may activate pertussis toxin-sensitive G-proteins by a receptor-independent mechanism

Formyl peptides activate superoxide anion (O₂ ^–) formation in human neutrophils and in HL-60 cells via pertussis toxin (PTX)-sensitive guanine nucleotide-binding proteins (G-proteins), and histamine (HA) mediates inhibition of O₂ ^– formation via H₂-receptors. We have studied the effects of lipophilic arpromidine-derived guanidines, which are potent, full H₂-receptor agonists in the guinea pig atrium, on O₂ ^– formation and on activation of G-proteins in HL-60 membranes and on purified G-proteins. We have also studied the effects of a HA trifluoromethyl-toluidide derivative (HTMT), a cationic-amphiphilic HA derivative which activates O₂ ^– formation in HL-60 cells through a mechanism which is independent of known HA receptor subtypes, on G-protein activation. Guanidines, at concentrations, up to 30 mol/l inhibited and, at concentrations above 30 mol/l, enhanced formyl peptide-induce O₂ ^– formation in neutrophils. In HL-60 cells, guanidines per se activated O₂ ^– formation. The stimulatory effects of guanidines on O₂ ^– formation were not inhibited by H₁- or H₂-receptor antagonists. In HL-60 membranes, guanidines and HTMT, activated high-affinity GTPase in a PTX-sensitive manner. These substances also increased GTP hydrolysis effected by transducin and G_i/G_o-proteins. Our data suggest that lipophilic guanidines and HTMT may act as receptor-independent activators of PTX-sensitive G-proteins, resulting in stimulation of O ₂ ^– formation.