Effects of age and mild cognitive impairment on direct and indirect access to arithmetic knowledge.

The present study aimed at investigating age-related changes and mild cognitive impairment (MCI) related effects in simple arithmetic. To pursue this goal, MCI patients, healthy old adults and young adults performed three computerised tasks. The production (e.g., 3 x 4=?) and the verification task (3 x 4 12?) evaluated direct access to multiplication knowledge, the number-matching task (3 x 4 34?, 'do 3 x 4 and 34 have the same digits?') tested indirect access. In verification and number-matching, interference from related distractors (e.g., 3 x 4 followed by 16) relative to unrelated distractors (17) reflects access to stored fact representations as well as efficiency of inhibition processes. Results indicated that, compared to young adults, MCI and healthy old adults were slower in responding across tasks. In production and verification, analyses of individual latency regression slopes and intercepts suggested that these age effects were related to differences at peripheral processing stages (e.g., encoding) rather than at the central (arithmetic retrieval) stage. Differences between MCI and healthy elderly emerged only in the number-matching task. While in verification effects were comparable between groups, in number-matching MCI patients were more susceptible to interference from irrelevant information than healthy old participants. Overall, the present findings indicate that aging has a general effect on peripheral processing speed, but not on arithmetic memory retrieval. Parietal cortico-subcortical circuits mediating arithmetic fact retrieval (Dehaene, S., & Cohen, L. (1995). Towards an anatomical and functional model of number processing. Mathematical Cognition, 1, 83-120; Dehaene, S., & Cohen, L. (1997). Cerebral pathways for calculation: Double dissociation between rote verbal and quantitative knowledge of arithmetic. Cortex, 33, 219-250) thus seem to be preserved in normal aging and MCI. In contrast, MCI patients show enhanced interference in number-matching. This task-specific lack of inhibition may point to dysfunctional frontal cortico-subcortical networks in MCI.

[Treatment of the polytraumatized patient in a hospital with basic care]. / Die Behandlung des Polytraumatisierten in einem Krankenhaus der Grundversorgung.

Severe traumatized patients with multiple injuries (polytrauma degree III according to Schweiberer [11]) can be treated also in a peripheral communal hospital, if some personal and technical suppositions are guaranteed. Preclinical treatment by an emergency doctor (surgeon or anaesthesist) on the accident place should as well be possible as the admission of the patient and diagnosis and treatment in all functional important fields by experienced personal for 24 hours daily. The therapeutic principle must be the stabilization of the patient after emergency operations making survival possible in a treatment schedule, planned by the surgeon and the anaesthesist in a cooperating team. Definitive treatment and rehabilitation can be performed in a special clinic or center, if necessary. The problems observed in a peripheral communal hospital in treatment of multiple injured patients are demonstrated in a series of 49 consecutive cases of polytrauma degree III.

[Management strategy in severe craniocerebral trauma in a general surgical department]. / Versorgungsstrategie beim schweren Schädel-Hirn-Trauma in der allgemeinchirurgischen Abteilung.

Emergency treatment of severe head injury combined with multiple trauma in most cases must be performed in regional hospitals and in general surgical units. Especially in acute intracranial hemorrhage (epidural hematoma) with the urgent indication to craniotomy the transmission of the patient in a special neurosurgical department is not possible in an adequate time. Therefore general surgeons should be trained in emergency trepanation of the skull and in basic treatment of severe head injury including measuring of intracranial pressure. The tactics of treatment of severe cranio-cerebral trauma is demonstrated on 46 cases out of 869 patients with head injury treated in our hospital from 1981 to 1984.

Effect of turgor pressure on water permeability of Allium cepa epidermis cell membranes.

Using onion epidermis layer a very accurate method for measuring the permeability of epidermis cells to water was standardized. In this method a 1.4 cm diameter epidermis disc was soaked in tritiated water (50 micronCi/ml) for about 1 hr. Next the disc was mounted in a specially designed elution chamber where it was held flat and washed on the noncuticular side with ordinary water. A constant flow rate, high enough to minimize unstirred layer effect, was used. Permeability was calculated in the usual way after separating different exponentials from the efflux curve of tritiated water. Turgor pressure of the cell was regulated by soaking thedisc in mannitol solutions containing tritiated water and washing it in the chamber with same concentration mannitol solution containing no radioactivity. Water permeability values were found to decrease less than 8% when the turgor pressure was decreased from 8 atm (full turgor) to zero. Turgor pressure had no significant effect on the water permeability of onion epidermal cells. Our results are contradictory to the findings of Zimmerman and Steudle (1974, J Membrane Biol. 16:331) but aresimilar to the findings of Tazawa and Kamiya (1966, Aust J. Biol. Sci. 19:399) and Kiyosawa and Tazawa (1972, Protoplasma 74:257).

Aluminum and Temperature Alteration of Cell Membrane Permeability of Quercus rubra.

This report extends research on Al-induced changes in membrane behavior of intact root cortex cells of Northern red oak (Quercus rubra). Membrane permeability was determined by the plasmometric method for individual intact cells at temperatures from 2 or 4 to 35 degrees C. Al (0.37 millimolar) significantly increased membrane permeability to urea and monoethyl urea and decreased permeability to water. Al significantly altered the activation energy required to transport water (+32%), urea (+9%), and monoethyl urea (-7%) across cell membranes. Above 9 degrees C, Al increased the lipid partiality of the cell membranes; below 7 degrees C, Al decreased it. Al narrowed by 6 degrees C the temperature range over which plasmolysis occurred without membrane damage. These changes in membrane behavior are explainable if Al reduces membrane lipid fluidity and kink frequency and increases packing density and the occurrence of straight lipid chains.

Al and Ca Alteration of Membrane Permeability of Quercus rubra Root Cortex Cells.

This study was undertaken to quantify the effect of aluminum and calcium on membrane permeability. The influence of Ca(2+) (0.2-3.7 millimolar) and Al(3+) (0-3.7 millimolar) on the permeability of root cortical cells of Quercus rubra was measured using three nonelectrolytes (urea, methyl urea, and ethyl urea) as permeators of progressively increasing lipid solubility. Water permeability was also measured. Al(3+) (a) increased membrane permeability to the nonelectrolytes, (b) decreased the membrane's partiality for lipid permeators, and (c) decreased membrane permeability to water. Ca(2+) had effects on permeability that were opposite to those of Al(3+). When Al(3+) and Ca(2+) were tested in combination, these opposite effects counteracted each other. The results suggest that Al(3+) altered the architecture of membrane lipids.

Influence of decenylsuccinic Acid on water permeability of plant cells.

Decenylsuccinic acid altered permeability to water of epidermal cells of bulb scales of Allium cepa and of the leaf midrib of Rhoeo discolor. Water permeability, as determined by deplasmolysis time measurements, was related to the dose of undissociated decenylsuccinic acid (mm undissociated decenylsuccinic acid x minute). No relationship was found between permeability and total dose of decenylsuccinic acid, or dose of dissociated decenylsuccinic acid, suggesting that the undissociated molecule was the active factor in permeability changes and injury.At doses which did not damage cells (0.0008 to 0.6 [mm of the undissociated molecule x minute]) decenylsuccinic acid decreased water permeability. At higher doses (e.g., 4 to 8 [mm x minute]) injury to cells was common and decenylsuccinic acid increased permeability. Doses above the 10 to 20 (mm x minute) range were generally lethal. The plasmolysis form of uninjured cells was altered and protoplasmic swelling occasionally was observed. The dose-dependent reversal of water permeability changes (decreased to increased permeability) may reflect decenylsuccinic acid-induced changes in membrane structure. Reported effects of decenylsuccinic acid on temperature dependence of permeability and frost resistance were not verified.

Freezing injury in onion bulb cells: I. Evaluation of the conductivity method and analysis of ion and sugar efflux from injured cells.

Onion (Allium cepa L.) bulbs were frozen to -4 and -11 C and kept frozen for up to 12 days. After slow thawing, a 2.5-cm square from a bulb scale was transferred to 25 ml deionized H(2)O. After shaking for standard times, measurements were made on the effusate and on the effused cells. The results obtained were as follows.Even when the scale tissue was completely infiltrated, and when up to 85% of the ions had diffused out, all of the cells were still alive, as revealed by cytoplasmic streaming and ability to plasmolyze. The osmotic concentration of the cell sap, as measured plasmolytically, decreased in parallel to the rise in conductivity of the effusate. The K(+) content of the effusate, plus its assumed counterion, accounted for only 20% of the total solutes, but for 100% of the conductivity. A large part of the nonelectrolytes in the remaining 80% of the solutes was sugars.The increased cell injury and infiltration in the -11 C treatment, relative to the -4 C and control (unfrozen) treatments, were paralleled by increases in conductivity, K(+) content, sugar content, and pH of the effusate. In spite of the 100% infiltration of the tissue and the large increase in conductivity of the effusate following freezing, no increase in permeability of the cells to water could be detected.The above observations may indicate that freezing or thawing involves a disruption of the active transport system before the cells reveal any injury microscopically.

Freezing Injury in Onion Bulb Cells: II. Post-thawing Injury or Recovery.

Onion (Allium cepa L.) bulbs were subjected for 12 days to either a moderate freeze (-4 C) or a severe freeze (-11 C). They were then thawed slowly over ice. During 7 to 12 days following the thaw, the injury progressed with time in the severely frozen bulbs, but appeared completely repaired in the moderately frozen bulbs. This was shown by the following post-thawing changes.Infiltration of the intercellular spaces increased from 80 to 90% to 100% after the severe freeze, and decreased from 30 to 50% to zero after the moderate freeze. All of the cells were alive immediately after thawing whether the freeze was moderate or severe. Corresponding to the infiltration results 7 to 12 days later, many to most were dead following the severe freeze, all were alive following the moderate freeze.The conductivity of the effusate from pieces of bulb tissue increased after the severe freezing, and decreased after the moderate freezing. The concentration of K(+), total solutes, and sugars in the effusate paralleled the conductivity changes. Neither the pH of the effusate nor the permeability of the cells (as long as cells were living) to water was changed following either the severe or the moderate freezes. Some treatments of the thawed tissue following the severe freeze halted the progress of injury.The above results indicate that the semipermeable properties of the cell are uninjured but that the ion and sugar transport mechanism is damaged by freezing. Most likely the primary injury is to the active transport mechanism involved in their transport. It must be concluded that the final injury following freezing and thawing cannot be evaluated from the degree of infiltration or the conductivity of the effusate immediately after thawing, since injury may progress or recede following the thawing.

Effects of Octylguanidine on Cell Permeability and Other Protoplasmic Properties of Allium cepa Epidermal Cells.

Effects of octylguanidine (OG) were studied on the permeability of cells of the adaxial epidermis of Allium cepa bulb scales to water and methyl urea and on the protoplast surface. Interference of OG with the Ca(2+) and Al(3+) action on the cell surface was also investigated.Permeability of the cell membrane for water and methyl urea increased nearly three times in presence of OG. The effect of OG on cell permeability depended on its direct contact with the protoplast surface.The effect of OG on the interaction between the protoplast surface and the cell wall (wall attachment) was marked and rapid; OG (225 micromolar) decreased the time for protoplast detachment in hypertonic solutions from 420 to 120 seconds. The plasmolyzed protoplasts were immediately rounded off while the controls without OG remained heavily concave.A considerable increase in protoplast detachment time and a decrease in rounding percentage were found when cells were plasmolyzed after pretreatment with AlCl(3) (0.05 molar for 2 minutes). This effect was partially reversed by KCl which was further enhanced by addition of OG.Penetration of OG into the mesoplasm was manifested only after 10 to 15 minutes. Vacuolization and swelling of the protoplasm, fragmentation of the protoplast, and aggregation of the spherosomes, however, were observed only 30 minutes after transfer. No evidence for penetration of OG into the vacuole was found.The results support earlier suggestions that OG acts primarily on the protoplast surface by interacting with membrane proteins as well as with phospholipids. In several aspects, OG acts on the cell surface similarly to a surfactant.

Water Permeability and Cold Hardiness of Cortex Cells in Cornus stolonifera Michx.-A Preliminary Report.

The relationship of freezing resistance to water permeability of cortex cells was studied in stems of red osier dogwood (Cornus stolonifera Michx.). Permeability was estimated by determining the diffusion flux of tritiated water from cortex slices previously equilibrated in tritiated water. Energy of activation and diffusion time comparisons of tritiated water flux from living cortex slices and slices killed by immersion in liquid N(2) verified that intact membranes of uninjured cortex cells limited water flux.Water permeability of living phloem and cortical parenchyma cells increased during the initial (photoperiodically induced) phase of cold acclimation. This accompanied an increase in hardiness from -3 to -12 C. Little if any further increase in permeability was noted during subsequent acclimation to below -65 C.Permeability measurements on nonhardy cortex samples yielded consistent results, but measurements on samples from hardy twigs were often difficult to reproduce. This unexplained variability precludes specific conclusions, but the tritiated water diffusion flux technique may provide an alternative to traditional plasmolytic techniques in studying water permeability in woody plant tissues.