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).     

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.     

Key word: Chromosome

The word chromosome has survived for over 100 years, because it succinctly defines what early cytologists were able to see with the most modern instrument of their time, a light microscope. It was introduced in a review that became widely known and was published almost simultaneously in German, English and French (Waldeyer 1888, 1889, 1890a, 1890b). In the late 19th century, these three languages were in strong competition for international status as the idiom of science. At the same time, Greek was also considered as a candidate for a nationalistically neutral language of science, and it seems more than coincidence that the word ó matches well the coherent Greek terminology used to describe the cell cycle in mitosis as well as meiosis. Emil Heitz (1935) maintained – in the face of reactionary German efforts to replace the term – that in using the ineradicable word chromosome we think last of all that it indicates a body that stains intensely. Significantly, the key word is no longer restricted to eukaryotes, but has been readily adopted by microbial geneticists (Heidelberg et al. 2000) and acknowledged as defining the elementary unit of genomic partition.     

Extramembranous deposits and “membranous” glomerulonephritis

Summary In 15 renal puncture biopsies from 14 patients, electron microscopy revealed extramembranous deposits (EMD) in various developmental stages (or their residues) in glomerular capillaries. Florid EMD exhibited a regular granular substructure as well as a typical localization within the subpodocytal space. Ultrastructurally, a gradual regression of EMD and their incorporation into the basement membrane could be observed. Early florid EMD were found in acute glomerulonephritis or in the nephrotic syndrome persisting for several months, with only discrete to absent membranous changes with light microscopy. Late stages of EMD with predominantly degenerative changes of glomerular basement membranes and apparent membranous thickening in light microscopy, on the other hand, were characteristic of the nephrotic syndrome lasting for several years. At early stages of EMD, long-lasting remission up to clinical healing were observed in a half of the cases studied, whereas at a late membranous stage long-lasting remission took place only once in six cases.     

Effects of ryanodine on skinned skeletal muscle fibers of the rabbit

The mechanism(s) of ryanodine-induced contracture of skeletal muscle were studied in skinned fibers from soleus (SL) and adductor magnus (AM) (slow- and fast-twitch skeletal muscles) of rabbits. Pieces of SL or AM were homogenized (sarcolemma disrupted). Single fibers were dissected from the homogenate and mounted on photodiode force transducers. At concentrations 1–50 M, ryanodine slightly but significantly increased the submaximal Ca²⁺-activated tension development of the contractile proteins in skinned fibers of AM but not of SL. Ryanodine in uptake phase or release phase increased caffeine-induced tension transients in the SR of both muscle types; however, no dose-response relation was found. Ryanodine 1 M decreased, however, the second control tension transients in a dose-dependent manner. The depression was nearly irreversible and activity-dependent. The concentrations of ryanodine that inhibited the second control tension transients by 50% were 10 M and 5 M for SL and AM, respectively, following ryanodine administration in the release phase, and 100 M and 30 M, respectively, for these preparations after the drug was present in the uptake phase. The quantity of calcium released from the SR by Triton X-100 and caffeine in the second control tension transient was unchanged by ryanodine at all concentrations tested when compared with that of the absence of ryanodine. The present findings suggest that the ability of ryanodine to increase immediate calcium release from the SR, and in AM but not SL, to increase the sensitivity of the contractile proteins to Ca²⁺ underlies the contracture caused by this agent in intact skeletal muscles. The delayed decreased Ca²⁺ efflux by caffeine, as evidenced by depression of tension transient with no change in the calcium content may be responsible for the decreased twitch tension caused by this agent.     

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.     

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.     

Cycloheximide inhibits the induction of collagenase mRNA in chondrocytes exposed to synovial factors or recombinant interleukin-1

Synoviocytes secrete chondrocyte activating factors (CAF) which, like recombinant interleukin-1 (IL-1), induce the synthesis of collagenase by cultures of articular chondrocytes. Enzyme synthesis is preceded by the appearance of collagenase mRNA some 3–5 hours after exposure of the chondrocytes to CAF or IL-1. Cycloheximide (CX) inhibits the appearance of this message in a dose-dependent manner. At a concentration of 5 g/ml inhibition by CX is completely reversible, with superinduction being observed in certain experiments.Identification of the newly synthesised proteins which are required for collagenase mRNA induction would greatly advance our understanding of collagenase gene expression     

On the regulation of the expressed L-type calcium channel by cAMP-dependent phosphorylation

The Ca²⁺ channel subunits _1C-a and _1C-b were stably expressed in Chinese hamster ovary (CHO) and human embryonic kidney (HEK) 293 cells. The peak Ba²⁺ current (I _Ba) of these cells was not affected significantly by internal dialysis with 0.1 mM cAMP-dependent protein kinase inhibitor peptide (mPKI), 25 M cAMP-dependent protein kinase catalytic subunit (PKA), or a combination of 25 M PKA and 1 M okadaic acid. The activity of the _1C-b channel subunit expressed stably in HEK 293 cells was depressed by 1 M H 89 and was not increased by superfusion with 5 M forskolin plus 20 M isobutylmethylxanthine (IBMX). The _1C-a·₂·₂/ complex was transiently expressed in HEK 293 cells; it was inhibited by internal dialysis of the cells with 1 M H 89, but was not affected by internal dialysis with mPKI, PKA or microcystin. Internal dialysis of cells expressing the _1C-a·₂·₂/ channel with 10 M PKA did not induce facilitation after a 150-ms prepulse to +50 mV. The Ca²⁺ current (I _Ca) of cardiac myocytes increased threefold during internal dialysis with 5 M PKA or 25 M microcystin and during external superfusion with 0.1 M isoproterenol or 5 M forskolin plus 50 M IBMX. These results indicate that the L-type Ca²⁺ channel expressed is not modulated by cAMP-dependent phosphorylation to the same extent as in native cardiac myocytes.     

A simple method for measurement of inulin in nanoliter samples using glass capillaries

Summary A simple method using glass capillaries instead of microcuvettes for measurement of inulin in nanoliter samples is given. Inulin was determined with anthron reagent (5 or 10 nl samples +3 l anthron reagent). Glass capillary tubes (o.d.=1 mm, i.d.=0.68 mm, length=150 mm) in which the chemical reaction took place during incubation at 56°C were directly introduced into the optical system of a Zeiss spectrophotometer PMQ II with sphere attachment and objective.Extinction was measured vertically to the axis of the capillary. The changes of extinction of 20 different capillaries with the blank at different positions was only 1.13×10^–3. The exactness of measurement in the concentration range of 100 200 400 750 1500 3000 mg-% inulin was for 5nl/3 l: 19.8 11.0 6.7 4.7 3.0 2.2%. 10nl/3 l: 13.0 8.4 5.1 3.9%.This method of measurement may also be applicable for other colorimetric reactions with nanoliter samples.This work was supported by Fonds zur Förderung der wissenschaftlichen Forschung.     

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.

     

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.     

A comparative immunohistological study of cerebellar enolases

Summary A comparative immunohistological study of the neurone-specific enolase and enolase, demonstrates the exclusive neuronal localization of enolase and its absence from glial cells. In contrast, enolase is located in astroglial cells. The validity of enolase as a neuronal marker and enolase as an astrocytic marker, is confirmed both by a double labelling technique, using antibodies to and to revealed with fluorescence or peroxidase in the same tissue sections, and by immunoelectronmicroscopy.     

Adenoma of the human pituitary producing growth hormone and thyrotropin

Summary A pituitary adenoma removed by surgery from a 22-year-old man was studied by histology, immunocytology, transmission electron microscopy and immunoelectron microscopy. Clinically, the patient had acromegaly and euthyroidism with elevated blood GH concentrations. Blood TSH and T₄ levels were within the normal range. Histologically, the adenoma was chromophobic and exhibited no PAS, lead hematoxylin, aldehyde thionin or Grimelius silver positivity. By the immunoperoxidase technique GH, -TSH and -subunit but no PRL, ACTH, -endorphin, -FSH or -LH were demonstrated in the adenoma cells. Electron microscopy revealed adenoma cells which were similar to TSH cells and showed no resemblance to GH cells of nontumorous pituitaries or GH-secreting tumors. Immunoelectron microscopy demonstrated GH and -TSH in the secretory granules.It is concluded that pituitary adenomas composed of TSH-like cells may secrete GH, resulting in acromegaly. Production of GH by adenomatous TSH cells cannot be explained on the basis of the one cell- one hormone theory. The question is raised whether bihormonal or multihormonal clones, capable of synthesizing more than one hormone, exist in the human pituitary. These cells are apparently dormant under normal conditions, but in the course of neoplastic transformation may undergo functional dedifferentiation and acquire the ability to produce two or more different hormones.     

Inability of various immune mechanisms to establishin vitro latent infection in sensory neurons infected by HSV-1

Summary Various immune mechanisms were tested for their ability to alter a normally productive infection of herpes simplex virus in cultures of dissociated rat sensory neurons. These mechanisms included anti-HSV antibody with and without the aid of complement, HSV-sensitized T cells, natural killer cells, and K cells plus anti-HSV antibody (ADCC reactions). Although both anti-HSV antibody plus complement and the ADCC mechanism significantly limited infectious HSV production, no mechanism was capable of preventing the eventual infection of the majority of neurons. It appears, therefore, that none of these mechanisms by themselves can convert a normally productive infection of sensory neurons in culture to a non-productive or latent infection.With 1 Figure     

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).     

Structure of the liver as a possible factor in the regulation of α-fetoprotein synthesis

During regeneration of the mouse liver after poisoning with CCl₄ and paracetamol, hepatocytes containing -fetoprotein (FP) lose their membrane antigen that served as marker for biliary capilaries. Both during regeneration and in early postnatal development, cessation of FP synthesis by the cells coincides with the appearance of an antigen marking the biliary capillaries on their surface. It is suggested that cessation of FP synthesis is the result of establishment of a system of contacts characteristic of the definitive hepatic column.Laboratory of Immunochemistry and Diagnosis of Tumors, Oncologic Scientific Center, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR L. M. Shabad.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 87, No. 6, pp. 576–579, June, 1979.     

Effect of muscular work on the motor function of the stomach and duodenum

Summary The effect of muscle work on the gastric and duodenal motor function was studied in dogs.It was observed that the static stress inhibited the hunger contractions of the stomach and duodenum; the inhibitory effect disappeared as the stress ceased. The static muscle work effect was more pronounced in hunger contractions of the stomach than in those of the duodenum. Under the influence of static stress, the periodic hunger contractions of the stomach varied more extensively than its acid and digestive contractions.Presented by Active Member Acad. Med. Sci. USSR V. N. Chernigovsky