Neurofilament Proteins Are Distributed in a Diminishing Proximodistal Gradient Along Rat Sciatic Nerve

Neurofilament (NF) proteins are distributed in a diminishing proximodistal gradient along rat sciatic nerve when compared with total noncollagen or other proteins in nerve. About a twofold decline of NF proteins can be detected by quantitating nerve proteins that have been separated by gel electrophoresis. A similar decrease of immunoreactivity to each NF subunit is seen in distal nerve segments when noncollagen nerve proteins are immunoblotted. Parallel decreases occur in all three NF proteins, thereby maintaining neurofilament subunit stoichiometry along the neuraxis. The same NF gradient can be detected when the NF contents in nerve branches to the gluteus and gastrocnemius muscles are compared with each other and with those in nerve segments taken from the same proximodistal levels of the parent sciatic nerve. The gradient of NF proteins increases during postnatal development and is readily detected by postnatal day 16. During the same period of development, the heavy NF subunit appears for the first time and is rapidly incorporated throughout the sciatic nerve. Hence, the NF gradient becomes manifest during the development and maturation of the adult form of the axonal cytoskeleton. The basis for the proximodistal gradient of NF proteins in peripheral nerve is presently unknown. The extent of the gradient cannot be accounted for on the basis of diminishing numbers of nerve fibers or increasing amounts of other nerve proteins, e.g., collagen, in distal nerve. An alternative interpretation is that the gradient reflects a low level of NF protein turnover during axonal transport.     

Stimulation of Guanosine 5'-O-(3-[35S]Thiotriphosphate) Binding by Cholinergic Muscarinic Receptors in Membranes of Rat Olfactory Bulb

Abstract: In membranes of rat olfactory bulb, a brain region in which muscarinic agonists increase cyclic AMP formation, the muscarinic stimulation of guanosine 5'- O -(3-[³⁵S]thiotriphosphate) ([³⁵S]GTPγS) binding was used as a tool to investigate the receptor interaction with the guanine nucleotide-binding regulatory proteins (G proteins). The stimulation of the radioligand binding by carbachol (CCh) was optimal (threefold increase) in the presence of micromolar concentrations of GDP and 100 m M NaCl. Exposure to N -ethylmaleimide and pertussis toxin markedly inhibited the CCh effect, whereas it increased the relative stimulation of [³⁵S]GTPγS binding elicited by pituitary adenylate cyclase-activating polypeptide (PACAP). On the other hand, membrane treatment with cholera toxin curtailed the PACAP stimulation of [³⁵S]GTPγS binding but did not affect the response to CCh. Like CCh, a number of cholinergic agonists stimulated [³⁵S]GTPγS binding in a concentration-dependent and saturable manner. The antagonist profile of the muscarinic stimulation of [³⁵S]GTPγS binding was highly correlated with that displayed by the muscarinic stimulation of adenylyl cyclase. These data indicate that the olfactory bulb muscarinic receptors couple to G_i/G_o, but not to G_s, and support the possibility that activation of G_i/G_o mediates the stimulatory effect on adenylyl cyclase activity.     

Migration of myogenic cells in the rat extensor digitorum longus muscle studied with a split autograft model

Summary The ability of myogenic cells to migrate perpendicular to the long axis of freely autografted muscles was examined. Rat extensor digitorum longus muscles were divided, and one half was devitalized by repeated freezing in liquid nitrogen while the other half was kept viable in physiologic saline. The halves were reunited with sutures and grafted back into the original muscle bed. At intervals between 5 and 25 days the grafts were removed and examined histologically for the presence of myotubes within the devitalized region. Myotubes were first seen in the devitalized half 10 days postgrafting with the maximum number of myotubes observed after 12 to 15 days. These results indicate that myogenic cells are capable of migration perpendicular to the long axis of the muscle fibers in an autograft.     

Dynamic features of cells expressing macrophage properties in tissue cultures of dissociated cerebral cortex from the rat

Summary Two previously identified forms of macrophage were investigated in primary cultures of cerebral cortical cells. Dynamic features were revealed through time-lapse video recording and aspects of macrophage function were assessed. The two cell forms were shown to be different pre-mitotic stages of a single cell type. The cell cycle for these cells involved an initial large, flat, quiescent cell which retracted to yield a slightly rounded form with numerous processes. This latter form lost processes and developed profuse filopodia as it became very rounded just prior to division; both resulting daughter cells then regained the initial large flat appearance. These cells possessed several properties of macrophages, including phagocytosis, nucleoside diphosphatase enzyme, and CR3 receptors. These properties were transient, expressed just before and after mitosis, but subsequently down-regulated in the flat daughter cells. Because of this feature, it was difficult to determine the exact size of this cell population; however, the observed rate of proliferation suggests it may be substantial. It is suggested that these cells correspond to non-microglial macrophages of brain tissue and, because of their significant down-regulation, they may be difficult to detect. This may be important in studies of brain accessory immune cells in tissue culture.     

A protein in rat prostatic interacting with androgen regulated gene

2M NaCl-insoluble fraction of rat ventral prostatechromatin(residual proteins)contain proteins able tointeract specifically with androgen-receptor complex andis,therefore,a part of the acceptor complex.Amongresidual proteins,a 97 KDa protein has been found whichbinds signifieantly to a genomic fragment containingan androgen-regulated gene coding for a 22 KDa protein.The biological significance of this binding in androgenaction need to be further studied. A mini-plasmid clone containing 22 KDa proteincoding sequence was cloned into Charon 4A genomiclibrary from which a 5.7 Kb genomic fragment wasisolated,identified by hybridization with a 5' and a 3'cDNA probes,and shown to contain the 5' flankingsequence.Restriction enzyme treatment of this fragmentyielded a 4.7 Kb restriction fragment representingthe 5' upstream region and a 1.0 Kb containing part ofthe coding sequence.Deletion studies indicated that the97 KDa protein bound only to a subclone of about 300 bpsegment.Furthermore,gel shifting experiment supportedits DNA-prptein binding.     

Impact on energy metabolism of quantitative and functional cyclosporine-induced damage of kidney mitochondria

In this study we have measured, under experimental conditions which maintained efficient coupling, respiratory intensity, respiratory control, oxidative phosphorylation capacity and protonmotive force. Succinate cytochrome-c reductase and cytochrome-c oxidase activities were also studied. These investigations were carried out using kidney mitochondria from cyclosporine-treated rats (in vivo studies) and from untreated rats in the presence of cyclosporine (in vitro studies). Inhibition of respiratory intensity by cyclosporine did not exceed 21.1% in vitro and 15.9% in vivo. Since there was no in vitro inhibition of succinate cytochrome-c reductase and cytochrome-c oxidase activities, the slowing of electron flow observed can be interpreted as a consequence of an effect produced by cyclosporine between cytochromes b and c₁. Cyclosporine had no effect on respiratory control either in vitro or in vivo. Statistically significant inhibition of the oxidative phosphorylation was observed both in vitro (6.6%) and in vivo (12.1%). Moreover, cyclosporine did not induce any change of membrane potential either in vivo or in vitro. Our findings show that cyclosporine is neither a protonophore, nor a potassium ionophore. In cyclosporine-treated rats we noticed a decrease of protein in subcellular fraction, including the mitochondrial fraction. The role of the inhibition respiratory characteristics by cyclosporine in nephrotoxicity in vivo must take account of these two parameters: inhibition of the respiratory characteristics measured in vitro and diminution of mitochondrial protein in cyclosporine-treated rats.     

Über intraepitheliale nervöse Endformationen in mehrschichtigem Plattenepithel

Zusammenfassung Im Anschluß an frühere lichtmikroskopisch erhobene Befunde (Silberimprägnation; 1924, 1928) weist der Verfasser durch elektronenmikroskopische Untersuchungen nach, daß durch die Interzellularspalten des Epithels (Schnauze der weißen Ratte) Nervenfasern hindurchziehen. Diese Nervenfäserchen, ihre Varikositäten und ihre Endknöpfchen liegen in den Spalten zwischen den Epithelzellen. Die Ultrastruktur der nackten, d.h. von Schwannschen Zellen nicht umhüllten terminalen Nervenfasern und ihrer Endigungen im Epithel wird beschrieben.

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On intraepithelial nerve endings in a stratified squamous epithelium

Summary In addition to former light microscopical observations the author demonstrates electronmicroscopically that nerve fibers pass through the intercellular spaces of the epithelium. The nerve fibers, their varicosities and terminal bulbs lie within the spaces between the epithelial cells. The ultrastructure of the terminal nerve fibers in the epithelium is described.

     

Hymenolepis diminuta: Action of worm RNase against RNA

Hymenolepis diminuta possesses a tegumental ribonuclease (RNase) which hydrolyzes rat liver and degraded yeast RNA. Polyacrylamide gel electrophoresis and gel chromatography of rat liver RNA after incubation with intact worms demonstrated significant hydrolysis of the high molecular weight RNA fractions (28 S and 18 S), with the appearance of fractions of intermediate molecular weight (i.e., between 18 S and 4 S), as well as ethanol-soluble fractions. Hydrolysis of degraded yeast RNA (with a molecular weight of approximately 25,000) yielded a single ethanol-precipitable hydrolysis product, as well as ethanol-soluble hydrolysis products.     

Lactosylceramide-induced stimulation of liposome uptake by Kupffer cells in vivo

Incorporation of 8 mol percent lactosylceramide into small unilamellar vesicles consisting of cholesterol and sphingomyelin in an equimolar ratio and containing [³H]inulin as a marker resulted in an increase in total liver uptake and a drastic change in intrahepatic distribution of the liposomes after intravenous injection into rats. The control vesicles without glycolipid accumulated predominantly in the hepatocytes, but incorporation of the glycolipid resulted in a larger stimulation of Kupffer-cell uptake (3.2-fold) than of hepatocyte uptake (1.2-fold). Liposome preparations both with and without lactosylceramide in which part of the sphingomyelin was replaced by phosphatidylserine, resulting in a net negative charge of the vesicles, were cleared much more rapidly from the blood and taken up by the liver to higher extents. The negative charge had, however, no influence on the intrahepatic distributions. The fast hepatic uptake of the negatively charged liposomes allowed competition experiments with substrates for the galactose receptors on liver cells. Inhibition of blood clearance and liver uptake of lactosylceramide-containing liposomes by $\text{N-}\text{acetyl-}\text{d}\text{-galactosamine}$ indicated the involvement of specific recognition sites for the liposomal galactose residues. This inhibitory effect of $\text{N-}\text{acetyl-}\text{d}\text{-galactosamine}$ was shown to be mainly the result of a decreased liposome uptake by the Kupffer cells, compatible with the reported presence of a galactose specific receptor on this cell type (Kolb-Bachofen et al. (1982) Cell 29, 859–866). The difference between the results on sphingomyelin-based liposomes as described in this paper and those on phosphatidylcholine-based liposomes as published previously (Spanjer and Scherphof (1983) Biochim. Biophys. Acta 734, 40–47) are discussed.     

Dynorphin-Related Opioid Peptides in the Neurointermediate Pituitary of Rats Are Not α-N-Acetylated

Immunoreactive dynorphin in the neurointermediate pituitary of rats was found to consist of four different molecular weight forms. The three larger molecular weight forms, with apparent molecular weights of 4800, 3200, and 1700, constituted more than 80% of the total dynorphin immunoreactivity, and each liberated leucine-enkephalin but not alpha-N-acetyl-leucine-enkephalin upon enzymatic treatment with trypsin followed by carboxypeptidase B. Only a minor portion of the smallest dynorphin-related molecular weight form, dynorphin-(1-8), released alpha-N-acetyl-leucine-enkephalin upon enzymatic cleavage. This suggests that the vast majority of dynorphin-related peptides in the rat neurointermediate pituitary is not alpha-N-acetylated. The exceptionally high opiate-like activity of the molecular weight 1700 dynorphin suggests that this dynorphin-related opioid peptide may constitute the major part of opioid activity in the neurointermediate pituitary of rats.