Veratridine-induced high-frequency asynchronous release of inhibitory transmitter quanta in crayfish nerve-muscle synapses superfused with normal and low-calcium saline

Crayfish fibres of opener muscles were voltage clamped toE=–80 mV membrane potential (T=19–22°C), and veratridine (10–100 mol/l) was added to the superfusate. Within 30–60 s this caused large fluctuations of the clamp current due to vigorous asynchronous quantal release from the inhibitory nerve terminals along the muscle fibre. Excitatory postsynaptic receptors were previously desensitized by application of 5 mmol/l glutamate. Current fluctuations were evaluated by means of the noise analysis technique. Typically, 100 mol/l veratridine increased instantaneously the quantal release rate ñ from ñ<1 quantum/s toñ10,000 quanta/s. Thereafter, ñ declined exponentially with a time constant of 70s. On average, about 500,000 inhibitory quanta could be liberated in this way from the terminals on a single muscle fibre of 1 mm length. Serotonin (1 mol/l) facilitated the effect of lower veratridine concentrations (1–10 mol/l). In opener muscles veratridine-induced asynchronous quantal release showed little dependence on the bath concentration of Ca²⁺. The opposite was found for fibres of the superficial abdominal extensor muscle. Beside postsynaptic current fluctuations, veratridine elicited slowly changing average postsynaptic DC-currents which could be explained partly by superposition of individual inhibitory quantal currents. These DC-currents suggest that beside inhibitory quantal release another factor activates inhibitory postsynaptic receptors after application of veratridine.This investigation was supported by the Deutsche Forschungsgemeinschaft, SFB 220     

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     

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.     

Immunohistochemical studies on S-100 cells in the anterior pituitary gland of Sprague Dawley rats and spontaneous dwarf rats

The S-100 cells in the pituitary glands of adult male Sprague Dawley rats (SDs) and spontaneous dwarf rats (SDRs) were immunohistochemically examined using anti-S-100 and anti-S-100 monoclonal antibodies. The immunoreactive cells against S-100 protein were divided into three subtypes on the basis of their immunore-activity against subunits of S-100 protein: S-100 dominant type (the -type cell), S-100 dominant type (the \-type cell) and immunoreactive against both S-100 and S-100 (the -type cell). In the SD, -type cells represented 26% of the total S-100 immunoreactive cells (S-100 cells) and were localized in the peripheral area of the ventral region of the pituitary gland. This type of cell was observed forming clusters, with more abundant cytoplasm than the -type cell. The proportion of -type cells was 53%. They were diffusely distributed throughout the gland, and their processes were thicker than those of the -type cell. In the SDR, the proportion of -type cells was 55%, and they were observed throughout the gland. In contrast, -type cells totalled 12% and were localized in small areas of the central and peripheral region of the gland. The proportion of -type cells was 21% in the SD and 33% in the SDR and they were observed forming small clusters in both animal groups. The proportion of -type cells compared with the total of S-100-immunoreactive cells was significantly higher (P < 0.05) in the SDR than in the SD, while the proportion of -type cells was markedly lower (P < 0.05).     

Altered expression of the steroid bioconverting pathway in pAN 7-1 transformants of Cochliobolus lunatus

Summary The filamentous fungus C. lunatus converts progesterone mainly to its 11-hydroxy derivative. C. lunatus transformed with the plasmid pAN 7-1, which contains the E. coli hph gene expressed under the control of the A. nidulans gpd and trpC expression signals, lacks this activity, but exhibits acetyl side chain degradation of progesterone through the reaction scheme progesterone20-hydroxy-progesterone ⁴-androstene-3,17-dione testolactone+testosterone. The main partof this metabolic pathway is not expressed in the non-transformed strain. It was determined that the site-specific integration of the plasmid into the genome directly influences the expression of genes involved in the bioconversion of steroids.     

Treatment of an Autoimmune Disease with “Classical” T Cell Veto: A Proposal

Immune responses protect against infectious diseases and cancers. In normal circumstances, the immune system is tolerant to self. However, under certain conditions this tolerance is broken. The immune system attacks otherwise normal tissue. An autoimmune disease ensues. Strategies are now being sought that remove the pathogenic T cells without affecting other immune functions. Classical veto has been described as an immune suppressive mechanism able to remove T cells in a highly specific and effective manner. The present article briefly reviews the current knowledge on the development of autoreactive T cells and their regulation in the periphery. It describes classical veto, its mechanisms, and its novel applications. Finally, it argues that classical veto can be adapted to treat an autoimmune disease, such as type I diabetes mellitus.     

Erythromycin and cycloheximide sensitivities of protein and RNA Synthesis in sporulating cells of Saccharomyces cerevisiae: Environmentally induced modifications controlled by chromosomal and mitochondrial genes

Summary The purpose of the experiments reported below was to examine the response in sporulation medium of the three diploid cell types MAT MAT, MAT MAT (asporogenic diploids) and MAT MAT (sporogenic diploid) to erythromycin, a specific inhibitor of mitochondrial protein synthesis (MPS) in vegetative cultures, and cycloheximide, a specific inhibitor of cytosol protein synthesis (CPS) in vegetative cultures. When MAT MAT diploids are transferred to sporulation medium a significant fraction of total protein synthesis (CPS + MPS) becomes sensitive to erythromycin in contrast to the behavior of MATa MATa and MAT MAT diploids in which the resistance of CPS to erythromycin is maintained. The decompartmentalization of erythromycin sensitivity is thus cell type specific. Erythromycin stimulates total RNA synthesis of MAT MAT cells in sporulation medium but not of MAT MAT and MAT MAT cells. Cycloheximide inhibits protein synthesis and stimulates RNA synthesis in all three diploid cell types. An erythromycin resistant mutant, shown to be due to a mutation of the mitochondrial genome, exhibited only partial resistance of CPS to erythromycin in sporulation medium in the background of the MAT MAT mating type genotype. Total RNA synthesis in this mutant was not stimulated. The results reported indicate that mitochondrial functions during sporulation are not restricted to those involving respiratory metabolism.     

Lack of additive effect between mechanisms of resistance to carbapenems and other beta-lactam agents inPseudomonas aeruginosa

Eighty-nine clinical isolates resistant (n=61) or susceptible (n=28) to imipenem and exhibiting the main patterns of susceptibility to other -lactam agents (wild type pattern, penicillinase pattern, constitutive cephalosporinase pattern) were studied in order to investigate (i) the mechanism of resistance involved and (ii) whether resistance to carbapenems affects the level of resistance to other -lactam agents and, conversely, if resistance to other -lactam agents affects the level of resistance to carbapenems. For this purpose, the presence of OprD protein in the cell wall was detected by Western blot and -lactamase activity by spectrophotometric assay and isoelectric focusing. OprD expression was not detectable in the imipenem-resistant (MIC16 g/ml) strains. It was decreased in half the strains for which MICs of imipenem were 2 to 8 g/ml and was close to a normal level in the most susceptible strains (MIC 1 g/ml), thus demonstrating a direct correlation between the level of susceptibility to imipenem and the level of OprD expression. No imipenemase activity was detected in imipenem-resistant strains. Synergy between imipenem or meropenem and BRL42715 was observed for all of the strains, demonstrating the role of cephalosporinase in carbapenem resistance. Within each pattern of susceptibility, the mean MICs of -lactam agents other than carbapenems were similar, whether the strains were susceptible or resistant to imipenem. Conversely, the mean MICs of imipenem or meropenem for either the imipenem-resistant or the imipenem-susceptible strains were similar, regardless of the susceptibility of these strains to the other -lactam agents. Thus, when several mechanisms of resistance to -lactam agents are present in the same strain ofPseudomonas aeruginosa, there is no additive effect between these mechanisms.     

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     

Neuronal mechanisms for pitch analysis in the time domain

Summary Many units in the auditory midbrain nucleus (MLD) of the Guinea fowl are found to be tuned to amplitude modulated tones (AM). For a given response maximum the relationship of the period _m of the modulation frequency f_m and the period _c of the carrier frequency f_c may be given by an empirical equation: m · _m + n · _c = 1 · ₁, where m, n and 1 are small integers typical for a unit. ₁ is a time constant of 0.4 ms. The temporal pattern of the neuronal response support these findings. The averages of spike trains oscillate with periods multiple to ₁. These oscillations are elicited by stimulus onsets and zero crossings of f_m and may be coupled strongly to f_m depending on f_c. Variation of f_m or f_c shifts the mean delay of the phase coupled activity proportional to m · _m and n · _c, respectively. These effects may be explained with activity phase coupled to f_c which coincides at the level of the recorded units with oscillations coupled to f_m. This is expressed by the above given periodicity equation. Psychophysical results with AM-stimuli indicate that the mechanisms described and the periodicity equation are adequate for the explanation of the analysis of periodicity pitch in humans. Hence the period corresponding to pitch is defined by m · _m + n · _c = 1 · ₁, where n and 1 are integers and ₁ = 0.4 ms. Plots of _p as a function of _c reveal steps at 0.4 ms intervals indicating that the neuronal time constant is the same in both species.Supported by the DFG, SFB 45     

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)     

Transformation of Cochliobolus lunatus with pUT 720 changes the steroid hydroxylating ability of the fungus

Summary The filamentous fungus Cochliobolus lunatus, a known 11-hydroxylator of steroids, was transformed to bleomycin resistance using the heterologous plasmid pUT 720. This plasmid contains the Sh ble gene expressed under the control of the Aspergillus nidulans gpd and trpC expression signals. The bleomycin-resistant colonies appeared with a frequency of six per g of DNA. All colonies were real transformants and no abortive growth was observed. In all transformants tested the plasmid molecules became stably integrated into the genome of the host, and one of the plasmid molecules integrated in a site-specific manner. Transformants retained the ability to hydroxylate the steroid ring, but the hydroxy group was inserted at the 15 position.     

Molecular organisation of an A mating type factor of the basidiomycete fungus Coprinus cinereus

Summary The A3 and A3 genes, which together constitute the A42 mating type factor of Coprinus cinereus, were isolated from a cosmid genomic library by walking 50 kb, a map distance of 0.5 units, from the closely linked metabolic gene pab-1. Cosmid clones having A gene function were identified by transformation into compatible A6 (22) and A5 (11) host cells where either 3 or 3 was expected to elicit the A factor — regulated development of unfused clamp cells. DNAs were digested with various enzymes before transformation in order to identify the smallest fragments containing an active 3 or 3 gene. Two non-overlapping fragments were identified as containing the 3 and 3 genes respectively. Southern hybridisation analyses showed that these two cloned genes had no detectable sequence homology, and that there was little or no hybridisation to the and gene alleles that constitute the A5 and A6 factors. 3 and 3 were shown to be less than 2.0 kb apart and embedded in a DNA sequence extending over 9.0 kb which was unique to our A42 strain and may contain a third A factor gene.     

Partitioning of Cortical and Deep Cytoskeleton Responses from Transient Magnetic Bead Twisting

We attempted to estimate in living adherent epithelial alveolar cells, the degree of structural and mechanical heterogeneity by considering two individualized cytoskeleton components, i.e., a submembranous cortical cytoskeleton and a deep cytoskeleton (CSK). F-actin structure characterizing each CSK component was visualized from spatial reconstructions at low and high density, respectively, especially in a 10-m-cubic neighborhood including the bead. Specific mechanical properties (Young elastic and viscous modulus E and ) were revealed after partitioning the magnetic twisting cytometry response using a double viscoelastic solid model with asymmetric plastic relaxation. Results show that the cortical CSK response is a faster ( ₁ 0.7s), softer (E₁: 63-109 Pa), moderately viscous (₁: 7-18 Pa s), slightly tensed, and easily damaged structure compared to the deep CSK structure which appears slower (₂ min), stiffer (E₂: 95-204 Pa), highly viscous (₂: 760-1967 Pa s), more tensed, and fully elastic, while exhibiting a larger stress hardening behavior. Adding drug depolymerizing actin filaments decreased predominantly the deep CSK stiffness. By contrast, an agent altering cell–matrix interactions affected essentially the cortical CSK stiffness. We concluded that partitioning the CSK within cortical and deep structures is largely consistent with their respective functional activities. © 2003 Biomedical Engineering Society. PAC2003: 8716Ka, 8716Ac, 8380Lz     

Epidermal growth factor,transforming growth factor-α, and epidermal growth factor receptor content in normal and carcinomatous gastric and colonic tissue

Summary Epidermal growth factor (EGF) and transforming growth factor- (TGF-) are polypeptides which bind to the EGF receptor (EGFr) and may play a role in cell growth and carcinogenesis. Our study investigated the content of EGF, TGF-, and EGFr in tumors of the stomach and the colon in comparison with the sourrounding mucosa. EGF was detected in half of the stomach specimens with concentrations between 1 and 9 ng/g weight irrespective of histology. In the colon no EGF was found in the tumor or normal mucosa. In the stomach normal mucosa contained higher TGF- concentrations (mean 22.4 ng/g) than the tumors (mean 11.8 ng/g), but the difference was not statistically significant because of a wide variation in mucosal values. By contrast, the colon mucosa displayed significantly higher TGF- concentrations than the tumor tissues (33 ng/g versus 12 ng/g; P < 0.01). EGFr content in the gastric mucosa was lower compared to gastric carcinoma (48 fmol/g versus 75 fmol/g) yet not significantly different. In contrast, colorectal tumor specimens disclosed significantly higher concentrations than the mucosal tissues (mean of 155 fmol/g versus 80 fmol/g; P < 0.01). In conclusion, TGF- should not be considered a tumorigenic but a physiological growth factor in the stomach and colon. An elevated EGFr content in colorectal tumors in comparison with the normal mucosa could lead to a growth advantage by an autostimulating mechanism.Abbreviations EGF epidermal growth factor - EGFr epidermal growth factor receptor - TGF- transforming growth factor - ROC receiver operating characteristic Dedicated to Prof. Dr. G. Paumgartner on the occasion of his 60th birthday     

Polypeptides associated with the 250 S mengovirus-induced RNA polymerase structure

Summary The mengovirus-induced 250 S RNA polymerase structure was separated from the bulk of the soluble protein and membrane particulates by two cycles of sucrose gradient centrifugation. After labeling cells 2–5 hours after infection the major polypeptides detected were capsid polypeptides and and polypeptides F and G. Intermediate amounts of capsid precursor s and capsid polypeptide were also present. Small amounts of capsid precursors A, B, and D₁ and stable polypeptide E were also detected. About 18–20 per cent of the labeled protein associated with the 250 S polymerase structure was present in mengovirus particles which cosediment with the polymerase preparation. After removal of these virus particles by CsCl gradient centrifugation the RNA-associated proteins recovered in the CsCl gradient pellet contained polypeptides , , and , capsid precursors A and B and the stable polypeptides E, F, and G. The capsid polypeptide is sharply reduced in amount and the reduction can be accounted for the by percent of mengovirus contaminating the polymerase structure. This polypeptide composition resembles the composition of poliovirus procapsid polypeptides in that it contains precursor capsid polypeptides and a low amount of capsid polypeptides .This work was initially presented at the 1973 FASEB Meeting in Atlantic City, New Jersey, and taken, in part, from the doctoral dissertation of W. T.Loesch, Jr.     

On three new species of the genus Criconemoides Taylor, 1936 (Nematoda: Criconematidae) from North India

Summary The definition of the genus Criconemoides should be extended so as to include those aberrant forms which possess slight cuticular ornamentation. Three new species of the genus Criconemoides Taylor, 1936 are described and illustrated from North India. Criconemoides aberrans n. sp. is distinctive in having 38–43 body annules, rough cuticular outgrowths on the body, 68–78 long spear, bluntly rounded tail, absence of spermatheca and males unknown. Criconemoides neoaxeste n. sp. has 45–49 body annules marked with faint longitudinal lines and rough posterior margins, 65–75 long spear, rounded tail terminus, vulva located at 7th or 8th annule from the posterior end and larva having a cuticular flap with rough margins on each annule. Criconemoides macrolobatus n. sp. is distinguished by 81–86 body annules, very large oval sublateral lobes, 71–75 long spear, tail terminus rounded and the absence of spermatheca and males unknown.

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Zusammenfassung Die Definition der Gattung Criconemoides sollte so erweitert werden, daß auch solche aberranten Formen eingeschlossen werden können, die leichte cuticulare Ornamente besitzen. Drei neue Arten der Gattung Criconemoides Taylor (1936) aus Nordindien werden beschrieben und abgebildet. C. aberrans n. sp. ist deutlich charakterisiert durch 38 bis 43 Körperringe, cuticulare Auswüchse am Körper, 68–78 langen Lanzen, stumpf-abgerundeten Schwanz; Spermatheke fehlt, Männchen nicht bekannt. C. neoaxeste n. sp. hat 45–49 Körperringe mit feiner longitudinaler Linienzeichnung und groben hinteren Rändern, 65–75 lange Lanzen, abgerundetes Schwanzende. Vulva im 7. oder 8. Ring vom hinteren Ende lokalisiert; die Larven haben eine cuticulare Klappe mit groben Rändern an jedem Ring. C. macrolobatus n. sp. ist gekennzeichnet durch 81–86 Körperringe mit sehr breitovalen sublateralen Loben, 71–75 lange Lanzen, Schwanzende abgerundet, Spermatheken fehlen und Männchen unbekannt.

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With 17 Figures in the Text     

Anticipatory postural changes induced by active unloading and comparison with passive unloading in man

Normal human subjects, sitting in a chair, were required to maintain stable elbow flexion against loads of 0.5 kg or 1.0 kg. Unloading was affected either passively by the experimenter, or actively with the subject's own contralateral arm. Elbow angle, force exerted by the load, and electromyographic activity (EMG) of biceps and triceps muscles of both arms were recorded and averaged. Passive unloading was followed by a reduction of biceps EMG activity, starting 50–80 ms after weight lift, and by an upward deflection of the forearm. With active unloading, however, a reduction of the biceps EMG activity slightly preceded the onset of unloading (0–30 ms). This reduction of the actively unloaded arm occurred at about the same time as the activity of the contralateral unloading arm. In this experiment, the unloaded forearm maintained an almost stable position. Thus, the anticipatory adjustment of elbow posture, observed when unloading was performed by the subject, appears to optimize limb stability during the mechanical perturbation.     

Congenic AB mice: A novel means for studying the (molecular) genetics of aggression

Congenic strains (CS) of mice were established to identify genomic regions which are associated with the male behavioral trait isolation-induced aggression (iia). For this purpose the trait was backcrossed for 10 generations onto the genetic background of a closely related, but nonaggressive, strain. Brother/sister matings were subsequently performed for 10 generations. Genomic screening for iia-associated markers was performed via multilocus DNA fingerprinting with a panel of oligonucleotide probes containing simple tandem repetitive motifs. Pools of DNAs from 10 mice each were composed from inbred generations to minimize residual genetic variability in the CS. The representation of iia-associated DNA fingerprint bands was additionally ascertained by investigating the individual mouse genomes constituting the pools. The CS system may allow rational approaches to the behavioral trait aggression, even under various experimental conditions of different environments.