Causal dimensions of college students' perceptions of physical symptoms

According to attribution theory, controllability, locus, and stability are important dimensions underlying causal explanations. The extent to which these theoretical dimensions underlie lay explanations for physical symptoms is unclear. Accordingly, in this study, attributes relevant to the lay public were empirically derived using a multidimensional scaling (MDS) procedure. Undergraduates (N=194) provided similarity judgments for 18 potential causes of physical discomfort. The MDS analysis yielded a three-dimensional solution. The first dimension captured the distinction between physical and nonphysical causes. The second dimension distinguished either variable versus stable causes or those that are controllable versus uncontrollable by health care professionals. The third dimension differentiated causes under low versus high personal control. These findings empirically confirm the theoretically proposed dimensions of personal control and stability and suggest the utility of considering the physical/nonphysical and controllability by health care professional distinctions in future work on attributions in the health domain.     

Präzisierung der Reizwirkung mittelfrequenter Wechselströme

Zusammenfassung Bei der Mittelfrequenz-Impuls-Reizung ist streng darauf zu achten, daß keine polaritären Reizkomponenten auftreten. Die diesbezügliche Kontrolle wird am besten mit Hilfe des Konvertibilitätstestes vorgenommen, d. h., es darf beim Vertauschen der Zuführungen zu den Reizelektroden weder die Reizschwelle bzw. die Größe des kollektiven Reizerfolges noch dessen Latenzzeit eine signifikante Änderung erfahren. Auf diese Weise wird die Phasenunabhängigkeit des echten Mittelfrequenz-Reizeffektes nachgewiesen.Diesen Anforderungen entsprechen Mittelfrequenz-Impulse, deren Trägerfrequenz über einige wenige Perioden sich aufschaukelt und ebenso wieder abklingt. Demgegenüber sind Mittelfrequenz-Stromstöße mit phasenstarrem Einsatz und Ende nicht unbedingt frei von polaritären Ein- bzw. Ausschalt-effekten, indem sowohl die erste als auch die letzte Trägerperiode einen polaritären Wechselimpuls-Reizeffekt ergeben kann, je nach Phasenlage bezogen auf die wirksame Reizelektrode und Art der Ansprechbarkeit des Reizobjektes (Nerv) auf entsprechend kurze gleitspiegelsymmetrische Wechselimpulse. Für eine echte Mittelfrequenz-Stromstoß-Reizung ist demnach ebenfalls ein Aufschaukeln und Abklingen der Trägerfrequenz über einige wenige Perioden erforderlich.Es besteht ein prinzipieller Unterschied zwischen der echten Mittelfrequenz-Reizung, die phasen -bzw. periodenunabhängig ist und schon früher als apolaritär bezeichnet wurde, und der konventionellen polaritären Reizung, die als polaritäre Komplikation der Mittelfrequenz-Reizung auftreten kann.Diese Präzisierung der Reizwirkung mittelfrequenter Wechselströme wurde angeregt durch zwei im Text erwähnte Publikationen, in denen in keineswegs überzeugender Weise versucht wird, die Mittelfrequenz-Reizung letzten Endes auf das polare Gesetz der Erregung zurückzuführen.

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Summary The particular excitatory action exerted by middle-frequency alternating current can only be revealed if care is taken to eliminate the occurrence of so-called polarity effects. Such effects are produced by the short alternating impulses represented by the first and the last period of a middle-frequency current pulse and are based on the polar law of excitation.In order to prevent such polarity intrusions, it is necessary to increase and decrease the amplitude of the middle-frequency current pulses over a few carrierperiods, or, to use amplitude-modulated middle-frequency impulses of variable shape and duration of envelope.A true middle-frequency excitatory effect is easily demonstrated by resorting to the convertibility test. It will then become evident that stimulation threshold, magnitude as well as latency of response do not change during reversal of the stimulating poles. This means, that no significant phase change of the response with regard to the carrier-frequency occurs when the leads to the stimulating electrodes are commuted, and that, as a result, true middle-frequency effects do not depend upon one particular catelectrotonic variation among the carrier-periods of a middle-frequency current pulse.It can thus be concluded that a fundamental difference exists between true middle-frequency stimulation, which is based on a non-polarity or apolarity principle, and the conventional stimulation of the polar or polarity type.This paper has been written in the hope of dispelling some errors of interpretation (discussed in the text) tending to ascribe the excitatory effects of middle-frequency impulse stimulation to the classical polar law of excitation.

     

Foraging strategies ofDrosophila melanogaster: A chromosomal analysis

Two larval foraging strategies inDrosophila melanogaster were identified, rover and sitter. Rovers traverse a large area while feeding whereas sitters cover a small area. The difference between rovers and sitters was analyzed genetically by chromosomal substitutions between isogenic stocks. Differences in larval locomotor behavior (crawling behavior) can be attributed to the second chromosome, the rover strategy being dominant over the sitter strategy. Differences in feeding rate (shoveling behavior) are affected additively by both the second and third chromosomes. Natural populations ofDrosophila larvae were sampled three times over a 2-month period; rovers and sitters were at constant frequencies in these populations. The two foraging strategies are discussed in the light of resource utilization in environments where food is distributed continuously or discontinuously.     

Increase in TCRγδ T lymphocytes in synovia from rheumatoid arthritis patients with active synovitis

To determine the relative presence of TCR+ and TCR+ T cells in synovial tissue from patients with various types of inflammatory synovitis and in tissues from patients with a number of chronic T cell-mediated conditions, we stained frozen tissue sections with monoclonal antibodies in indirect immunofluorescence assays. In tissues obtained from patients with chronic T cell-mediated granulomatous conditions (Wegener's granulomatosis, lymphomatoid granulomatosis, granuloma annulare, Langerhan's cells granulomatosis, pigmented villonodular synovitis, Takayasu's arteritis, and talc granulomatosis), the T cells present were predominantly TCR+, without an increased presence of TCR+ cells. In contrast, 6 of 14 (43%) synovia from patients with rheumatoid arthritis (RA) showed increased TCR+ T cells (3–10 cells/hpf). The RA synovia with increased TCR+ cells present had an increased tissue inflammation score compared to RA synovia with few TCR+ cells [18.6±5.8 versus 11.6±4.2 (mean±SE),P<0.05]. In contrast, synovia from patients with osteoarthritis, systemic lupus erythematosus, and trauma did not show an increased presence of TCR+ T cells. Thus, in cellular inflammatory infiltrates the presence of increased TCR cells is not a component of noninfectious granulomatous inflammation but is found in approximately 40% of RA synovia with high levels of inflammation.     

Mechanism of modulation of single sodium channels from skeletal muscle by the β 1-subunit from rat brain

We studied the molecular mechanism of the rat skeletal muscle -subunit (_I) gating kinetics modulation by the brain ₁-subunit by heterologous expression of single sodium channels from _I and ₁ in Xenopus laevis oocytes. Coexpression of ₁ reduced mean open time at –10 mV to 21% when compared to channels expressed by _I alone. Channels formed by _I exerted multiple openings per depolarization, which occurred in bursts, in contrast to the channels formed by the _I/₁ complex that opened in average only once per depolarizing voltage pulse. Macroscopic current decay (mcd), as evidenced by reconstructed open probability vs. time , was greatly accelerated by ₁, closely resembling mcd of sodium currents from native skeletal muscle. Generally was larger for channels expressed from the pure _I subunit.From our single channel data we conclude that ₁ accelerates the inactivation process of the sodium channel complex.     

Comparison of the estrous cycles in mice of high and low cancer lines

Summary In February and May the author studied the duration of the estrous cycle stages in female mice of high A and low C₅₇ cancer lines. It was established that the average duration of the estrus is much greater and of diestrus much shorter in the A than that of the corresponding stages in the C₅₇ line.The estrous cycles of the C₅₇ line females do not undergo any significant seasonal changes while in the A line they approach the character of the normal mice spring cycles.Desviations from the normal duration of the estrous cycle stages in the high cancer line mice denote a disturbed hypophyseal — ovarian hormonal balance.Presented by Active Member AMN SSSR V. N. Chernigovskii     

Electrophysiological characterization of histamine receptor subtypes in sheep cardiac Purkinje fibers

The histamine-receptor-subtype-mediated effects on action potentials of electrically driven and spontaneously active isolated sheep cardiac Purkinje fibers were investigated using H₁-and H₂-selective agonists and antagonists.In electrically stimulated Purkinje fibers, histamine (3 mol/l) increased the action potential plateau height, decreased the action potential duration measured at a repolarization level of –60 mV and enhanced the pacemaker activity. These effects were abolished by the H₂-selective antagonist cimetidine (30 mol/l), but were not impaired by the H₁-selective antagonist dimetindene (0.3 mol/l).In spontaneously active Purkinje fibers, histamine (10 mol/l) increased the spontaneous rate by 24%, the slope of diastolic depolarization by 45% and shortened the duration of the diastole by 32% of the respective control measurements. These effects were blocked by 30 mol/l cimetidine, but remained unchanged in the presence of 0.3 mol/l dimetindene.Concentration-response curves of histamine were shifted to the right by approximately 2 logarithmic units in the presence of 30 mol/l cimetidine, but were not influenced in the presence of 0.3 mol/l dimetindene. The H₂-selective agonist impromidine (0.001–0.3 mol/l) had similar actions as histamine on spontaneously active Purkinje fibers, while the H₁-selective agonist 2-(2-pyridyl-)ethylamine was ineffective. It is concluded that the pronounced stimulatory action of histamine on spontaneous activity in sheep cardiac Purkinje fibers is exclusively mediated by H₂ receptors.Dedicated to Prof. Dr. E. Mutschler on the occasion of his 60th birthday.Supported by Ministerium für Wissenschaft und Forschung, Nordrhein-Westfalen, Projekt-Nr. 40008786.     

Activation of atrial muscarinic K+ channels by low concentrations ofβγ subunits of rat brain G protein

Effects of G protein subunits from rat brain on cardiac K⁺ channel was examined in single atrial cells of guinea-pig, using patch clamp techniques. We found that 10 pM concentration of rat brain subunits preparation could activate the atrial muscarine receptor-gated K⁺ channel (I_K.ACh). Neither the detergent, CHAPS, used to suspend nor the boiled preparation activated I_K.ACh. Furthermore, preincubation of subunits preparation in Mg²⁺-free solution, which easily inactivated -GTP-S, did not affect -activation of I_K.ACh. We concluded, therefore, that subunits themselves can activate I_K.ACh.Supported by the grants from the Ministry of Education, Culture and Science of Japan and from the Calcium Signal Workshop on Cardiovascular Systems     

Neural nicotinic acetylcholine responses in solitary mammalian retinal ganglion cells

Using the patch-clamp technique,whole-cell recordings from solitary rat retinal ganglion cells in culture have established the nicotinic nature of the acetylcholine responses in these central neurons. Currents produced by acetylcholine (5–20 mol/l) or nicotine (5–20 mol/l) reversed in polarity near –5 mV and were unaffected by atropine (10 mol/l). Agonist-induced currents were blocked by low doses(2–10 mol/l) of the classical ganglionic antagonists hexamethonium and mecamylamine, as well as by d-tubocurarine and dihydro--erythroidine (the latter two do not discriminate clearly between ganglionic and neuromuscular junction receptors). Treatment with the potent neuromuscular blocking agent -bungarotoxin (10 mol/l) did not affect the cholinergic responses of these cells, while toxin F (0.2 mol/l), a neural nicotinic receptor antagonist, readily abolished acetylcholine-induced currents. Thus, the experiments performed to date show that the nicotinic responses of retinal ganglion cells in the central nervous system share the pharmacology of autonomic ganglion cells in the peripheral nervous system. The ionic current carried by the nicotinic channels was selective for cations, similar to that described for nicotinic channels in other tissues. In addition, single-channel currents elicited by acetylcholine were observed in whole-cell recordings with seals > 5 G as well as in occasional outside-out patches of membrane. These acetylcholine-activated events, which had a unitary conductance of 48 pS and a reversal potential of 0 mV, represent the ion channels that mediate the neural nicotinic responses observed in these experiments on retinal ganglion cells.     

Unterschiedlich hoher Ureterdruck in Abhängigkeit von der Diureseform beim Hund

Zusammenfassung Bei Vorliegen einer normalen Diurese wird nach Ureterabklemmung der sog. hohe Ureterdruck, unter osmotischer Diurese der maximale erreicht. Die Differenz von Blutdruck und maximalem Ureterdruck war im Mittel der Versuche um 20 mm Hg kleiner als diejenige des hohen. Die Ursache dafür wird kurz diskutiert.Herrn Prof. Dr.S. Janssen zum 70. Geburtstag gewidmet.     

Establishment of immortalized Schwann cells from Sandhoff mice and corrective effect of recombinant human β-hexosaminidase A on the accumulated GM2 ganglioside

We have established spontaneously immortalized Schwann cell lines from dorsal root ganglia and peripheral nerves of Sandhoff mice. One of the cell lines exhibited genetically and biochemically distinct features of Sandhoff Schwann cells. The enzyme activities toward 4-methylumbelliferyl N-acetyl--D-glucosamine (-hexosaminidases A, B, and S) and 4-methylumbelliferyl N-acetyl--D-glucosamine-6-sulfate (-hexosaminidases A and S) were decreased, and GM2 ganglioside accumulated in lysosomes of the cells. Incorporation of recombinant human -hexosaminidase isozymes expressed in Chinese hamster ovary cells into the cultured Sandhoff Schwann cells via cation-independent mannose 6-phosphate receptors was found, and the incorporated -hexosaminidase A degraded the accumulated GM2 ganglioside. The established Sandhoff Schwann cell line is useful for investigation and development of therapies for Sandhoff disease.     

Isolierung von Amoeben des Typs „Hartmannella-Acanthamoeba“ und „Naegleria“ aus Kaltblütern

Zusammenfassung Aus einer großen Anzahl von Kaltblütern, insbesondere Reptilien, wurde eine Reihe von Amoebenstämmen isoliert, die auf Grund von Größe und Kernstruktur dem Typus Hartmannella-Acanthamoeba und Naegleria zuzuordnen sind. Häufig traten diese Amoeben bei Reptilien zusammen mit typischen Entamoeben auf. In den Fällen, in denen nur Hartmannella gefunden wurden, lag aber bei der Mehrzahl der Tiere ebenfalls eine charakteristische Amoebiasis vor, so daß anzunehmen ist, daß auch diese Amoeben pathogene Eigenschaften gegenüber dem Reptilgewebe besitzen. Besonders zu erwähnen ist, daß auch das Gehirn besiedelt werden kann. Kotuntersuchungen lieferten aber auch den Beweis, daß klinisch gesunde Tiere diese Amoeben beherbergen können, ein Befund, der für die Epidemiologie von Bedeutung sein kann. Inwieweit diese Amoeben eine Pathogenität dem Warmblüter gegenüber besitzen, ist noch ungeklärt.

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Isolation of amoebae of the type Hartmannella-Acanthamoeba and Naegleria from cold-blooded vertebrates

Summary Many strains of the complex Hartmannella-Acanthamoeba and Naegleria amebae could be isolated from cold-blooded vertebrates, especially reptiles. The morphology of the nucleus and the size of these amebae separate them distinctly from the classical genus Entamoeba. In many cases the Hartmannella were associated with typical amebae of the genus Entamoeba, but we could see such infections also were the Hartmannella-types, were not mixed with other amebae. In spite of that we found the characteristic amebic alterations of the tissue. It is to conclude that these amebae have a pathogenic capability against the reptile tissue. In six cases the brain was also infected. A number of strains were isolated from feces only and no clinical symptoms could be observed. These observations may be important for the epidemiology at least in such cases were amphibians and reptiles have contact to unchlorinated swimming pools or in which these animals are kept as pets. — Pathogenicity against warm-blooded vertebrates is not tested as yet.

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Nach brieflicher Auskunft von Prof. Dr. W. Balamuth (Univ. of California, Berkely) handelt es sich bei dem an ihn gesandten Stamm 2 um eine Naegleria-Art.

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Durchgeführt mit Mitteln der Deutschen Forschungsgemeinschaft.     

An improved apparatus for the optical recording of contraction of single heart cells

An optical system for measuring changes in cell length during unloaded contractions of cardiac myocytes is described. A one-dimensional video image of a cell is obtained every 4 ms with a linear photodiode array, which is aligned with the longitudinal axis of the cell. The circuit used to process the image from the photodiode array has a variety of features to aid in the accurate determination of the distance between the ends of the cell, i.e. the cell length. First, the video image of the cell is divided into two windows, one encompassing the front edge of the cell, the other encompassing the rear edge. Other cells or debris beyond the cell edges are excluded. Changes in the general light level, for example as a result of debris floating above the cell, have little effect because within the windows the background light level is subtracted from the signals before they are processed further. To detect the cell edges, the system determines when the signals within the windows exceed (front edge) or drop below (rear edge) chosen threscholds, which are different for the front and rear edges. The system has memory and it identifies the rear edge of the cell as the last time the signal falls below the threshold; because of this bright spots within the cell are not mistaken for the end of the cell. The system has hysteresis, which enables it to ignore small fluctuations in brightness around the threshold. The system is easy to use, accurate, readily calibrated, and it has good spatial and time resolution (about 0.25 m and 4 ms respectively).     

The role ofγδ T cells in the normal and disordered immune system

Summary A small population of T cells does not express the conventional T cell receptor characterized by the and polypeptide chains (TCR) but instead, two polypeptides termed and (TCR). This alternative receptor is able to recognize antigen. It appears early in T cell ontogeny, but its role in the thymus prior to the availability of TCR remains unclear. In selected sites such as skin or gut TCR predominates in mice which might suggest a role of T cells in the first line of defense against infection, T cells secrete lymphokines and display cytotoxic activity. However, their activation requirements may differ from what is known for T cells since MHC-nonrestricted and also CD4 and CD8 negative T cells have been described. Preferential activation by mycobacterial antigens possibly indicates a special repertoire of the T cells. In various diseases slightly increased numbers of T cells were found, but these preliminary studies have not yet provided evidence for a major pathogenetic role of T cells.List of abbreviations C constant region (immunoglobulin or TCR gene segment) - CD4 cluster of differentiation 4 (mainly on helper cells) - CD8 cluster of differentiation 8 (mainly on cytotoxic cells) - D diversity region (immunoglobulin or TCR gene segment) - DNA desoxyribonucleic acid - IL2 interleukin 2 - J joining region (immunoglobulin or TCR gene segment) - kD kiloDalton - MHC major histocompatibility complex - NK natural killer (cells) - RA rheumatoid arthritis - TCR T cell receptor - V variable region (immunoglobulin or TCR gene segment)     

Symmetry, broken symmetry, and handedness in bimanual coordination dynamics

Summary The symmetrical dynamics of 11 rhythmic bimanual coordination may be specified by an order parameter equation involving the relative phase between rhythmic components, and an interlimb coupling which determines the relative attractiveness of in-phase and anti-phase patterns. Symmetry breaking of these dynamics can occur via the difference in the natural frequencies, , of the left and right rhythmic components, or by the intrinsic asymmetrical dynamics of the body. The latter is captured by additional terms that render the symmetrical coupling slightly anisotropic. A major prediction resulting from this step is that although =0, as the frequency of coordination is increased, the asymmetrical coupling will increase and the symmetrical coupling will decrease. This results in a greater left-limb bias in left-handers and right-limb bias in right-handers. This increased handedness prediction was confirmed in an experiment in which 20 left-handed and 20 right-handed individuals performed 1 1 coordination with hand-held rigid pendulums. Manipulations of left and right pendulum lengths controlled , and the coupled frequency was determined by a metronome. Also confirmed was the prediction that the small shift in equilibria from in-phase and anti-phase due to the intrinsic asymmetry should be amplified in left-handers when > 0 and in right-handers when < 0. Further, the bias in left-handers was more consistent than the bias in right-handers, and a subgroup of right-handers was identified who performed similarly to left-handers. The coordination dynamics of functional asymmetry provides insights into the elementary synergy between the limbs, the dynamical mechanism that modulates it, and the nature of the asymmetry in left-handed and right-handed individuals.     

Glucocorticoids modulate TGF-beta production by human fetal lung fibroblasts

TGF- is thought to play a central role in pulmonary fibrosis inducing fibroblast differentiation and extracellular matrix synthesis. In human lung fibroblasts, it is still unclear how various TGF- isoforms affect TGF- production and whether glucocorticoids, commonly used agents to treat fibrotic lung disease, modulate these processes. To this end, human fetal lung fibroblasts (HFLF) were cultured with various concentrations of glucocorticoids (budesonide, dexamethasone or hydrocortisone) with and without TGF-1, -2, or -3. Post-culture media were collected for ELISA assays of TGF-1, -2, and -3 . TGF- mRNA was assessed by real time RT-PCR. Smad 2, 3, and 4 and AP-1 complex (c-fos and c-Jun) cellular localization were evaluated by immunostaining. TFG-2 and -3 stimulated TGF-1 production significantly (p < 0.01 relative to control). TGF-1 stimulated TGF-2 production (p < 0.01 relative to control). TGF-3 was undetectable. Glucocorticoids significantly inhibited TGF-1 and TGF-2 production and reduced expression of the up-regulated TGF-1 and TGF-2 mRNA induced by exogenous TGF-1, -2, or -3 (p < 0.01 for each) but had no effect on Smads. Although c-jun-related nuclear staining was not intensified in TGF--stimulated cells, it was reduced by glucocorticoids. Thus, TGF- isoforms may stimulate production of various TGF- isoforms in the lung. Glucocorticoids then may block TGF- production by modulating mRNA levels and c-Jun.     

Bioactive 5-Reduced 16α,17α-Cyclohexanoprogesterone Derivatives Weakly Interact with Proteins of the Soluble Uterine Fraction

We studied competitive activities of 16,17-cyclohexano-5- and 5-dihydroprogesterone in replacing ₃H-progesterone and ₃H-16,17-cyclohexano-6-methylprogesterone from protein complexes. Direct binding of ₃H-5-reduced derivatives with proteins of soluble fractions from rat and rabbit uteri was also assayed. Cd values for 5-reduced derivatives were in the micro- or submicromolar range. The data suggest that biological effects of these analogues are not mediated via soluble uterine receptors.     

Effect of lysolecithin on blood vessel reactivity and of some ethers and esters of glycerophosphocholine and phosphocholine,respectively, on aggregation of rat platelets

Infusion of lysolecithin (LPC; e.g. 88 g/ml for 0.5–1.0 min) did not significantly impair the vasopressor action of norepinephrine (NE), prostaglandin F₂ (PGF₂) and extract of posterior pituitary (EPP) in the isolated perfused hind legs of rats. In other words, vascular smooth muscle behaves differently from the smooth muscle of the guinea-pig small intestine, since, in the latter, contractions evoked by acetylcholine, prostaglandins etc., are inhibited by LPC. Triton X 100 which, by comparison, was used as a detergent effective on the guinea-pig small intestine, depressed the vasopressor effect of NE, PGF₂ and EPP.LPC, at low concentrations (40 mol/l), potentiated (15% max.) ADP-induced platelet aggregation (PA) in rat PRP but, at high concentrations, inhibited PA (IC₅₀=390 mol/l). 2-Hexadecylglycerophosphocholine and its short-chain 1-alkyl ethers, which are structurally related to platelet-activating factor, as well as some long-chain alkanol phosphocholine esters, were somewhat more active than LPC. Dipalmitoyllecithin (4–700 mol/l) was without any effect.     

The favorite cigarette of the day

The choice of a favorite cigarette smoked during a given day varies considerably. Preferences are related to nicotine dependence and the lifestyles of smokers. In a sample of 5124 smokers, the after-dinner cigarette was chosen as the cigarette which they would miss most, while the next largest proportion of smokers (33%) said that they would miss the first cigarette of the morning most. The latter group scored highest on tests of nicotine dependence. In contrast, infrequent smokers (chippers) chose the after-dinner cigarette.Supported in part by NHLBI Grant HL39770 and California Tobacco-Related Disease Program Grant 1RT-87.