Over-reinforcement protects against memory deficits induced by muscarinic blockade of the striatum

It has been shown that blockade of muscarinic receptors of the anterior striatum (AS) induces significant impairments in the retrieval of stored information of a passive avoidance task, trained with conventional parameters of footshock, and that the same blockade is ineffective in altering short-term memory of this task. The results of the present experimental series showed that in conditions of over-reinforcement, microinjections of scopolamine into the AS shortly after training or before retention testing of passive avoidance, do not produce memory deficits when retention is assessed 30 min, 24 h or 48 h after training. It is suggested that after an enhanced learning experience (over-reinforcement) striatal cholinergic activity is not involved in short- and long-term memory functions.     

Immunohistochemical study of cat Pacinian corpuscles: co-localization of vimentin- and S-100 protein-like in the inner core

The presence of vimentin and S-100 protein in cat Pacinian corpuscles of cat mesentery has been investigated immunohistochemically (streptavidin-biotin method) using monoclonal antibodies. A positive reaction for both vimentin- and S-100 protein-like was found only in the lamellae of the inner core. The presence of vimentin and the co-expression of vimentin/S-100 protein-like in sensory corpuscles is reported for the first time. The authors discuss the origin of the inner core and capsule of sensory corpuscles on the basis of their immunohistochemical characteristics.     

American oncology and the discourse on hope

From the perspective of medical anthropology and comparative research, American oncology appears as a unique variant of international biomedical culture, particularly when contrasted with oncological practice in societies such as Japan and Italy. Based on interviews with 51 oncologists in Harvard teaching hospitals, this paper argues that American oncological practice draws on distinctive cultural meanings associated with hope and is infused with popular notions about the relationship between psyche and soma, the progressive efficacy of biotechnical interventions, truth-telling, and the nature of the physician-patient relationship.     

B lymphocyte regulation of the immune system. I. In vivo biologic activity of the novel lymphokine, B cell-derived enhancing factor (BEF)

B cell-derived enhancing factor (BEF) is a lymphokine of B cell origin which was originally identified and characterized by its ability to enhance in vitro antibody responses, an effect shown to be due to the ability of BEF to reduce the activation of suppressor T cells. The present study was undertaken to determine whether BEF could also be active in modulating antibody responses in vivo. The data presented here demonstrate that BEF is biologically active in vivo, as manifested by significantly enhanced primary IgM and IgG antibody responses in mice that were either injected with BEF prepared exogenously or implanted with growing BEF-secreting cells of a B cell line. Moreover, BEF was shown to enhance subsequent development of immunologic memory in mice pretreated with BEF at the time of primary immunization; these mice then displayed enhanced secondary responses when challenged with the same antigen some weeks later. The mechanism by which BEF exerts biologic activities to positively modulate in vivo antibody responses and immunologic memory reflects the ability of BEF to modulate one or more T cell functions, as evidenced by the following findings. 1) Transient in vitro exposure to BEF of T cells, but not of B cells, endowed such cells with the capacity to adoptively transfer enhanced primary antibody responses to irradiated recipients. 2) Utilizing adoptive in vivo antibody responses, in which fractionated B cell or T cell populations were obtained from BEF-pretreated mice, revealed that one effect of BEF which results in enhanced immunologic memory is related to its activity on T cells during the priming phase of the immune response. Finally, the existence of this B cell-derived lymphokine and the demonstration of its in vivo regulatory effects on the immune system provide yet another example of the emerging biologic importance of B lymphocytes in the overall regulation of the immune system.     

Sensitivity of the motor endplate to carbachol in the presence of sulfhydryl reagents

The effect that bath application of sulphydryl reagents (SR) exerts on frog sartorius motor endplate sensitivity to iontophoretically applied carbachol (CCh) has been studied. Sensitivity to CCh is expressed as the ratio of the CCh potential (mV) to the nanocoulombs delivered by the iontophoretic pulse and has been determined before and after addition of SR to the bath. Two groups of SR have been tested: oxidizing reagents, o-iodosobenzoate and reducing agents, dithiothreitol (DTT). CCh was applied iontophoretically by means of a microelectrophoretic programmer with constant current source. Exposure of the muscle to 1 mM DTT in a bath pH range of 7-8 for 2 to 85 min showed no significant differences in endplate sensitivity to CCh before and after addition of the reducing agent. o-Iodosobenzoate at a 1 mM bath concentration (pH 7) for 2 to 19 min strongly decreases endplate sensitivity to CCh. The statistical methods used were Wilcoxon rank tests and linear regression. Since previous studies have shown that oxidizing and reducing SR evoke depolarizations when applied iontophoretically at the endplate region, these results suggest that activation of the receptor is achieved only when SR are delivered iontophoretically, and that discrepancies observed can be attributed mainly to the different techniques of drug application.     

Euopsis and Harpidium,Genera of the Lichinaceae (Lichenes) with Rostrate Asci*

Based on corresponding ascocarp ontogeny and thallus structure, the genera Euopsis and Harpidium are included in the family Lichinaceae. In the two species of Euopsis, E. granatina and E. pulvinata, the apothecia develop from ascogonia in generative tissue, while in H. rutilans they are pycnoascocarps. In thallus anatomy, the species of Euopsis resemble Pyrenopsis haematopsis and allied species, while H. rutilans corresponds in structure and development of the thallus and apothecia to Pyrenopsis haemaleella (syn. P. sphinctotricha). H. rutilans is the first member of Lichinaceae known to have only a green algal symbiont. In E. granatina, two phycobionts are always present, a species of Gloeocapsa and a chlorococcalean alga. In Euopsis and Harpidium, the ascus wall is composed of an outer, non-expansible and an inner, expansible layer; the latter surrounds the protoplast as an amyloid collar, which expands during spore release into a long, tapering rostrum. In Euopsis, the outer wall layer is strongly amyloid and the upper part separated from the expanded amyloid rostrum by a non-amyloid zone, appearing like a slit in LM studies. The ultrastructure and function of the ascus in E. granatina has been studied in TEM and is interpreted as functionally unitunicate-rostrate. Unitunicate asci with short rostrum are described for P. haemaleella and P. haematopsis.     

Aspects of the spawning biology of the Brazilian sardine, Sardinella brasiliensis (Steindachner, 1879), (Clupeidae)

Biological data, size frequency distribution of intraovarian oocytes, maturity indices and histological observations of the gonads were used to assess the spawning cycle of S. brasiliensis , sampled September 1981–August 1982 throughout the main fishing area off the Brazilian coast (22°S to 28°S). Post-ovulatory follicles are described and classified, and the incidence of mature females displaying these structures was calculated. The main findings were (a) spawning occurred during the spring and summer with a maximum in December and January; (b) spawning occurred throughout the area studied; (c) spawning was fractional; (d) average batch fecundity was 26 000 oocytes per female, or 393 eggs g⁻¹; (e) spawning frequency reached values of approximately 50% during the spawning peak, but was sensibly lower during the other months of spawning activity.     

Subcellular Distribution Studies of Diadenosine Polyphosphates—Ap4A and Ap5A—in Bovine Adrenal Medulla: Presence in Chromaffin Granules

Diadenosine tetraphosphate (Ap4A) and diadenosine pentaphosphate (Ap5A) have been identified in bovine adrenal medullary tissue using an HPLC method. The values obtained were 0.1 +/- 0.05 mumol/g of tissue for both compounds. The subcellular fraction where Ap4A and Ap5A were present in the highest concentration was chromaffin granules: 32 nmol/mg of protein for both compounds (approximately 6 mM intragranularly). This value was 30 times higher than in the cytosolic fraction. Enzymatic degradation of Ap4A and Ap5A, isolated from chromaffin granules, with phosphodiesterase produces AMP as the final product. The Ap4A and Ap5A obtained from this tissue were potent inhibitors of adenosine kinase. Their Ki values relative to adenosine were 0.3 and 2 microM for Ap4A and Ap5A, respectively. The cytosolic fraction also contains enzymatic activities that degrade Ap4A as well as Ap5A. These activities were measured by an HPLC method; the observed Km values were 10.5 +/- 0.5 and 13 +/- 1 microM for Ap4A and Ap5A, respectively.     

Changing glycine 21 for glutamic acid in the β-subunit of penicillin G acylase from Kluyvera citrophila prevents protein maturation

Summary Active penicillin acylase from Kluyvera citrophila strain ATCC 21 285 consists of two different -and -subunits derived from a single precursor by post-translational processing. Using the chemical mutagen hydroxylamine we have treated plasmid pYKD59 containing the active penicillin acylase gene (pga) from K. citrophila and have generated different point mutant penicillin acylase genes, one producing a muturation deficient precursor. This point mutation has changed the gylcine 310 residue of the precursor for a glutamic acid (residue number 21 of the mature -subunit). The introduction of a charged residue in this position did not prevent translocation of the precursor to the periplasm but the resultant molecule was not able to undergo subsequent post-translational modification to yield the active protein.