bluuebunny/crossref_metadata_2025 huggingface dataset:
Chronic kidney disease and periodontal disease. Case report
Authors: Nunes Camilla Magnoni Moretto , Ferreira Camila Lopes , Bernardo Daniella Vicensotto , De Marco Andréa Carvalho , Santamaria Mauro Pedrine , Neves Jardini Maria Aparecida
Published: April 2018

Chronic renal disease promotes a decrease on kidneys filterability and nitrogen products accumulation on blood, electrolyte and system endocrine functions imbalance. Among the many clinical manifestations of chronic renal failure (CRF) in the oral cavity, there are: dry mouth, uremic stomatitis, radiographic changes in maxillary and jaw bones and accumulation of calculus on the teeth that increases levels of periodonto pathogenic microorganisms able to lead a periodontal tissue destruction and also have the potential to act from a distance on other organs, e.g. the kidneys. Thus, it becomes evident that a periodontal treatment of patients suffering from chronic renal failure is crucial for maintaining their general health conditions and a subsequent successful organ transplant.Thus, the objectives of this case report were to highlight how important the periodontal treatment is for chronic renal failure patients and to demonstrate improvements in their clinical condition through the treatment plan proposed herein. A patient with 43 years old carrier generalized moderate chronic periodontitis and CRF was submitted to scaling and root planning sessions, and later surgical access for scaling where the basic treatment not resulted in a resolution of the inflammatory periodontal process. The results obtained from a well-developed periodontal treatment and an effective cooperation of patient showed satisfactory results with periodontal disease process resolution or stabilization.Thus, periodontal treatment and patient compliance were crucial for the improvement of periodontal clinical conditions enabling a future successful renal transplantation.KeywordsDental care; Periodontal diseases; Renal insufficiency.
Effect of different concentrations of nanohydroxyapatite on tooth bleaching effectiveness and enamel bond strength
Authors: Ferraz Laura Nobre , Vieira Júnior Waldemir Francisco , Ambrosano Gláucia Maria Bovi , Giorgi Maria Cecília Caldas , Aguiar Flávio Henrique Baggio , Lima Débora Alves Nunes Leite
Published: April 2018

Objective: To evaluate the effect of 35% hydrogen peroxide (35% HP) combined to different concentrations of nanohydroxyapatite (nHA) on the effectiveness of dental bleaching (superficial enamel and deep dentin) and enamel bond strength. Material and Methods: Fifty bovine dental specimens (5x5x2mm) were divided into 5 groups, according to the treatments (n = 10): no bleaching (negative control); 35% HP (positive control); 35% HP+ 5% nHA; 35% HP + 10% nHa; and 35% HP + 15% nHA. Three in-office bleaching sessions were made. The color analysis was performed on the enamel surface and the opposite dentin, using a spectrophotometer. The results were expressed in the CIE L*a*b* system. After this, the adhesive system was applied to the tooth structure, and the dental specimens received a composite restoration. The microshear bond strength test was performed 24 h after the restoration. Data were submitted to ANOVA and Tukey's test (?=0.05). Results: For the enamel color analysis, all bleached groups differed statistically from the unbleached group, with increasing L* values and decreasing b* values. The addition of different concentrations of nHA did not interfere with the bleaching effectiveness for the enamel and opposite dentin. For microshear bond strength, no statistically significant differences were presented between groups. The adhesive failure rate of the 35% HP + 10% nHA group was lower than the 35% HP group and similar to the negative control. Conclusion: The addition of different concentrations of nHA in 35% of hydrogen peroxide did not interfere with the bleaching efficacy of enamel and deep dentin and did not affect the enamel bond strength after bleaching KeywordsEnamel; Shear strength; Tooth bleaching.
Comparative evaluation of postoperative pain intensity after single-visit and multiple-visit retreatment cases: a prospective randomized clinical trial
Authors: Uyan Hatice Miray , Olcay Keziban , Özcan Mutlu
Published: April 2018

Objective: This study was designed to evaluate postoperative pain after endodontic retreatment. Material and Methods: Asymptomatic, multi-rooted molar & premolar teeth requiring retreatment with 2–5 mm periapical lesions were included. Seventy-eight teeth were randomly placed in four groups (n=20): single-visit (control, group 1), Ledermix (group 2), metronidazole, ciprofloxacin, minocycline mixture (group 3), calcium hydroxide (group 4). The postoperative pain was recorded using a VAS at 6, 12, 24, and 48 h after retreatment. Statistical evaluation was performed using Two-Way Repeated Measures ANOVA and Tukey test. Results: Mild pain occurred in 67.5%, moderate in 30%, and flare-ups in 2.5%, and there was a significant difference between the groups (p<0.01). Significantly lower postoperative pain was observed in TAP and CaOH2 groups(p<0.05). In the 6, 12, and 24 h intervals, there was a significant difference in the pain levels (p<0.05). Conclusion: TAP and CaOH2 are effective for reducing postoperative pain after retreatment.KeywordsIntracanal medicaments; Multiple-visit; Postoperative pain; Retreatment; Single-visit.
Effect of glide path on transportation promoted by NiTi and M-Wire instruments
Authors: Nogueira Tatiane Pires , Bessa Ellen Roberta Lima , Nunes Eduardo da Costa , Marques André Augusto Franco , Garcia Lucas da Fonseca Roberti , De Carvalho Fredson Márcio Acris
Published: April 2018

Objective: To evaluate the effect of glide path creation on transportation promoted by NiTi and M-Wire instruments. Material and Methods: Sixty polyester resin blocks containing a simulated root canal were distributed into four groups (n=15), according to the protocols/systems used for root canal preparation: GPR group - glide path + Revo-S system; R group - no glide path + Revo-S system; GPPN group - glide path + ProTaper Next system and PN group - no glide path + ProTaper Next system. Root canals were photographed before and after preparation, and the images were superimposed to evaluate the transportation at the apical, middle and coronal thirds. The time spent to perform preparation was also measured (seconds). Data were submitted to the non-parametric Kruskal-Wallis test (p<0.05) for statistical analysis. Results: In the apical third, there was no significant difference among groups (p>0.05). GPR and R groups were similar in the middle third (p>0.05). However, the transportation value in GPR group was statistically higher in comparison with GPPN and PN groups (p<0.05). In the coronal third, GPR and R groups were similar (p>0.05). Only R group presented significant difference in comparison with GPPN and PN groups (p<0.05). There was no difference among groups about time spent to perform preparation (p>0.05). Conclusion: None of the systems were capable of maintaining the original trajectory of the simulated root canal, and the glide path had no effect on the transportation promoted by instruments.KeywordsDental instruments; Endodontics; Root canal preparation.
Hearts on the agenda / Fifty Years of the First Heart Transplantation in Brazil: Dr. Zerbini Put the Brazilian Cardiac Surgery in the Map! / 50 Years of Cardiac Transplantation ... a medical journey of courage, dedication and innovation
Authors: Gonçalves Sergio Eduardo de Paiva , Amorim José Benedito Oliveira , Bonetti Ema Ely Salomão
Published: April 2018

Hearts on the agendaSymbol of affection and keeper of the deepest emotions of human beings, the heart is the agenda of BDS editorials of this issue.Two major Brazilian events, in two completely different sectors of knowledge, place side by side the deepest nationalist emotions: on the one hand, the heart transplant surgery that this year marks 50 years of its first realization in Brazil by Dr. Zerbini and team (Editorial written by the Physiologist Jose Benedito de Oliveira Amorim); on the other, the first Brazilian Rhapsody, composed by a woman (Zélia Marão), commissioned by a medical coordinator of an Environmental Preservation Center-CAEB (Dr. Ema Ely Salomão Bonetti), in whose libretto we extracted the fantastic cover image of this issue. Dr. Ema tells us in her editorial the worldwide position regarding heart transplants and provides us with the cover image of this issue.Science, health, art and emotion in an incentive to preserve the quality of life.
Cover
Authors: Nozaki Thaís , Gonçalves Sergio Eduardo de Paiva
Published: April 2018

Title: Como se ama Illustration Illustrator: Thaís Nozaki Editora Esthamária The Illustration is part of the Brazilian Rhapsody’s libretto, composed by Zélia Marão, produced and presented at CAEB (Eduardo Bonetti Environmental Center).
I Congresso Brasileiro de Ciências Farmacêuticas
Authors: João Walter Da Silva Jorge , De Santi Valmir , Canquerini Roberto , De Melo Angelita Cristine
Published: April 2018

Resumos de Trabalhos Científicos do I Congresso Brasileiro de Ciências Farmacêuticas, 6º Congresso Brasileiro sobre o Uso Racional de Medicamentos, I Congresso Pan-Americano sobre o Uso Racional de Medicamentos, I Congresso Latino-Americano de Estudantes de Farmácia, II Congresso Brasileiro de Farmácia Estética, II Simpósio Farmacêutico de Nutracêuticos e III Encontro Nacional de Educadores em Farmácia Clínica
Sustained Expression of Negative Regulators of Myelination Protects Schwann Cells from Dysmyelination in a Charcot–Marie–Tooth 1B Mouse Model
Authors: Florio Francesca , Ferri Cinzia , Scapin Cristina , Feltri M. Laura , Wrabetz Lawrence , D'Antonio Maurizio
Published: April 2018

Schwann cell differentiation and myelination in the PNS are the result of fine-tuning of positive and negative transcriptional regulators. As myelination starts, negative regulators are downregulated, whereas positive ones are upregulated. Fully differentiated Schwann cells maintain an extraordinary plasticity and can transdifferentiate into “repair” Schwann cells after nerve injury. Reactivation of negative regulators of myelination is essential to generate repair Schwann cells. Negative regulators have also been implicated in demyelinating neuropathies, although their role in disease remains elusive. Here, we used a mouse model of Charcot–Marie–Tooth neuropathy type 1B (CMT1B), the P0S63del mouse characterized by ER stress and the activation of the unfolded protein response, to show that adult Schwann cells are in a partial differentiation state because they overexpress transcription factors that are normally expressed only before myelination. We provide evidence that two of these factors, Sox2 and Id2, act as negative regulators of myelinationin vivo. However, their sustained expression in neuropathy is protective because ablation of Sox2 or/and Id2 from S63del mice of both sexes results in worsening of the dysmyelinating phenotype. This is accompanied by increased levels of mutant P0 expression and exacerbation of ER stress, suggesting that limited differentiation may represent a novel adaptive mechanism through which Schwann cells counter the toxic effect of a mutant terminal differentiation protein.

SIGNIFICANCE STATEMENTIn many neuropathies, Schwann cells express high levels of early differentiation genes, but the significance of these altered expression remained unclear. Because many of these factors may act as negative regulators of myelination, it was suggested that their misexpression could contribute to dysmyelination. Here, we show that the transcription factors Sox2 and Id2 act as negative regulators of myelinationin vivo, but that their sustained expression in Charcot–Marie–Tooth type 1B (CMT1B) represents an adaptive response activated by the Schwann cells to reduce mutant protein toxicity and prevent demyelination.
Dose-response analysis of effects of antibodies to large ganglion cells on the cat's retinogeniculate pathways
Authors: Crabtree JW , Spear PD , McCall MA , Tong L , Jones KR , Kornguth SE
Published: April 2018

Previous studies have shown that antibodies against large retinal ganglion cells (alpha-/Y-cells) reduce the Y-cell retinogeniculate pathway while having little or no effect on the X- or W-cell pathways. The present study investigated the dose-response relationship of these effects. We began by studying effects on the T1 (largely Y-cell- mediated) and T2 (largely X-cell-mediated) waves of the retinal field- potential. Different concentrations of the antibodies were injected intraocularly in adult cats and retinal field-potentials evoked by optic chiasm stimulation were examined. The lowest concentration of immune serum tested (330 micrograms/100 microliter volume) reduced both the T1 and T2 amplitudes. With increasing concentrations, the ratio of T1:T2 amplitudes progressively decreased from 0.71 to only 0.05. The highest concentration of immune serum tested (1000 micrograms/100 microliter volume) virtually eliminated the T1 wave while the T2 wave remained (albeit reduced). Next, we carried out single-cell physiological and morphological studies to verify the effects of the highest antibody concentration and compare them with previous results on effects of the lowest antibody concentration (Kornguth et al., 1982; Spear et al., 1982). In single-cell recordings from the retina, the encounter rates of Y- and X-cells were reduced by 85 and 53%, respectively, after injection of the highest antibody concentration. There was no effect on the encounter rate of retinal W-cells. After injection of the lowest antibody concentration, there was no change in the encounter rates of any of the retinal cell types. Morphological studies revealed an 88–99% loss of alpha-cells in retinae treated with the highest antibody concentration. There also was a substantial (24– 57%) loss of medium-size ganglion cells but no loss of small ganglion cells. The loss of alpha-cells was much greater after high- concentration injections than after low-concentration injections. In recordings from the LGN, the proportion of Y-cells was reduced by 87% in laminae receiving input from an eye injected with the highest antibody concentration. Laminae receiving input from an eye injected with the lowest concentration had a 77% reduction in Y-cells. The encounter rate of LGN X-cells was not affected by either concentration. Morphological analysis indicated that the loss of Y-cells in the LGN was not due to changes in cell size. These findings indicate that antibody-mediated effects on retinogeniculate pathways are dose- dependent.(ABSTRACT TRUNCATED AT 400 WORDS)
Androgen receptor levels in cranial nerve nuclei and tongue muscles in rats
Authors: Yu WH , McGinnis MY
Published: April 2018

Specific in vitro binding of 3H-methyltrienolone (R1881) was demonstrated in 100,000 X g supernatant (cytosol) of hypoglossal, facial, and cochlear nuclei and tongue muscles of adult rats. Binding sites in these cranial nerve nuclei and tongue muscles were of high affinity, limited capacity, with steroid specificity; and they were capable of translocation to the cell nuclei in vivo. Accordingly, an androgen receptor system with properties very much akin to the androgen receptors described in the forebrain limbic regions has been quantitatively demonstrated for the first time in brain stem nuclei. Because of its widespread presence in neurons of the brain stem and spinal cord, androgen receptors may have important roles in regulation of neuron physiology beyond the sphere of reproductive function, including mediating androgen effects on regeneration of the hypoglossal nerve reported previously.
Presynaptic calcium channels in rat cortical synaptosomes: fast- kinetics of phasic calcium influx, channel inactivation, and relationship to nitrendipine receptors
Authors: Suszkiw JB , O'Leary ME , Murawsky MM , Wang T
Published: April 2018

Fast-mixing and rapid-filtration techniques were used to analyze the kinetics of potassium-depolarization-dependent (delta K+ = 47.5 mM) influx of 45Ca into synaptosomes, in the time range from 50 msec to 5 sec. The results are consistent with the presence in synaptosomes of a homogeneous population of voltage-sensitive Ca channels. With 1 mM Cao in the medium, the delta K+-dependent Ca influx has a single- exponential time course with the half-life, t1/2 approximately 0.5–0.7 sec. Ca influx, measured between 0.1 and 10 mM Cao, shows half- saturation (KCa) at 1.5 mM Cao and has the limiting value (JCamax) of 5.9 nmol/sec/mg protein, or a current of approximately 0.06 pA/micron2 surface area. The estimated density of functional Ca channels is 0.6–6 micron-2. Voltage- and time-dependent inactivation of Ca channels was measured in synaptosomes predepolarized in 52.5 mM Ko+ with Ca omitted from the medium. Channel inactivation is a single-exponential process with a half-life of t1/2 approximately 2.3 sec. Channel recovery in 5 mM Ko+ media is likewise a single-exponential process with a half-life of t1/2 approximately 4.3 sec. The slower rate of voltage-dependent channel inactivation than of decay of Ca influx suggests that Ca entry into synaptosomes terminates by a mechanism that depends on Ca influx itself. Synaptosomes contain 200 fmol/mg protein, or approximately 6 micron-2 high-affinity (KD = 0.12 nM) 3H-nitrendipine binding sites; however, nitrendipine at concentrations greater than 10(4) X KD is without effect on the phasic influx of Ca measured at 215 msec with either 1.0 or 0.1 mM Cao. This suggests that Ca channels characterized in this study belong to a class of dihydropyridine-insensitive channels.
Opioid antagonist (naltrexone) modulation of cerebellar development: histological and morphometric studies
Authors: Zagon IS , McLaughlin PJ
Published: April 2018

The role of endogenous opioid systems in preweaning cerebellar development was explored in rats utilizing naltrexone, a potent opioid antagonist. Sprague-Dawley rats were given daily subcutaneous injections of either 1 or 50 mg/kg naltrexone to invoke a temporary or complete blockade, respectively, of opioid receptors throughout the first 3 weeks of postnatal life; animals injected with sterile water served as controls. At weaning (day 21), macroscopic, morphometric, and histological determinations were conducted. In general, 50 mg/kg naltrexone had a stimulatory action on cerebellar development, whereas 1 mg/kg naltrexone had an inhibitory influence. Both sexes were affected comparably. Limits to naltrexone's ability to modulate cerebellar ontogeny were noted, with more latitude existing toward growth enhancement than impairment. The temporal course of ontogeny was generally unaltered in naltrexone-treated rats. Rather, only events that transpired over this period were dramatically affected. The most notable effects in 1 mg/kg naltrexone rats were marked decreases in cerebellar areal dimensions, the content of internal granule neurons, and cellular and tissue differentiation. Characteristics of the 50 mg/kg naltrexone group included increases in cerebellar areal dimensions, neural cell number, content, and size, and structural changes consistent with acceleration in growth and differentiation. Naltrexone influenced both neurons and glia, but only neural cells still being generated during the first 21 d after birth were altered in regard to quantity. Previous evidence has shown the presence of peak levels of endogenous opioids and opioid receptors in the cerebellum during the first weeks of life, as well as demonstrating the presence of enkephalin immunoreactivity on germinative cerebellar cells during postnatal neurogenesis but not in adult counterparts.(ABSTRACT TRUNCATED AT 250 WORDS)
Relative effectiveness of C primary afferent fibers of different origins in evoking a prolonged facilitation of the flexor reflex in the rat
Authors: Woolf CJ , Wall PD
Published: April 2018

Changes in the excitability of the hamstring flexor withdrawal reflex produced by conditioning stimuli applied to C-afferent fibers of different origins have been examined in the decerebrate spinal rat. In the absence of conditioning stimuli, the flexor reflex elicited by a standard suprathreshold mechanical stimulus to the toes is stable when tested repeatedly for hours. Three categories of conditioning stimuli have been used in an attempt to modify the excitability of the flexor reflex; electrical stimulation of a cutaneous (sural) nerve or a muscle (gastrocnemius-soleus) nerve at C-fiber strength; the application of mustard oil, a chemical irritant that activates chemosensitive C- afferents, to the skin or injected intramuscularly and intraarticularly; and the indirect activation of high-threshold muscle afferents by fused tetanic contractions of the tibial muscles. Conditioning stimuli of an intensity sufficient to activate C-afferent fibers result in a heterosynaptic facilitation of the flexor motoneuronal response to the standard test input, which lasts from 3 min to more than 3 hr, depending on the stimulus and the C-afferents activated. Pretreatment of the sciatic nerve with the C-fiber neurotoxin capsaicin abolishes all the postconditioning facilitations, which is an indication that it is likely that it is C-afferents that are primarily responsible for the facilitatory effects of the conditioning stimuli, although some A delta afferents may contribute. Capsaicin pretreatment does not modify the reflex response to the test stimulus. The most prolonged increase in the excitability of the flexor reflex resulted from intraarticular injections of 5 microliter mustard oil. Using the subsequent injection of lignocaine intraarticulary, it was found that the prolonged facilitation of the reflex is triggered by the afferent input generated by the conditioning stimulus and does not require an ongoing input for its maintenance. These results indicate that there is a spectrum of central changes in the stimulus response relations of the spinal cord resulting from the activation of C-fibers of different origins. The prolonged duration of some of these changes means that the peripheral activation of C-afferents will modify the functional response of the spinal cord to other inputs applied long after the conditioning input, and this may be responsible for some ofthe sensory and motor alterations found after peripheral tissue injury.
Amplitude modulation of EPSPs in motoneurons in response to a frequency- modulated train in single la afferent fibers
Authors: Collins WF , Davis BM , Mendell LM
Published: April 2018

In anesthetized cats, single group Ia fibers were activated with a train of 52 stimuli whose interspike intervals were obtained from the discharge of a group Ia fiber in a walking cat (courtesy of Dr. G. E. Loeb, NIH). The EPSPs recorded in motoneurons to which the afferents projected were averaged in register (EPSP1, EPSP2, ..., EPSP52) in response to multiple presentations of the train at a rate (0.77 Hz) similar to the stepping rate of the cat. Amplitudes of these averaged EPSPs were found to be highly variable, depending both on afferent discharge rate and history of activation. The initial EPSP was generally potentiated, and EPSPs in the high-frequency (greater than 200 Hz) middle portion of the train were generally reduced in amplitude. Connections at which the first EPSP was most potentiated tended to be those which showed the most depression of EPSP amplitude during the high-frequency portion of the train. Thus, at some connections, modulation of EPSP amplitude during the frequency- modulated train was much greater than at other connections. In general, the extent of modulation was greater on low-rheobase motoneurons than on high-rheobase motoneurons. We suggest that these differences in transmission permit type S (i.e., low-rheobase) motoneurons, which on average generate the largest EPSPs, to reach threshold at low levels of input (size principle) but prevent excessive depolarization due to temporal summation during high-frequency stimulation.
Learned changes of feeding behavior in Aplysia in response to edible and inedible foods
Authors: Susswein AJ , Schwarz M , Feldman E
Published: April 2018

Feeding behavior in Aplysia fasciata and A. oculifera is modified by pairing the behavior with reinforcing consequences. Successful and unsuccessful attempts to transfer food from the buccal cavity to the crop act as positive and negative reinforcers, respectively. A number of changes in feeding behavior occur as a result of pairing of feeding with the negative reinforcer: feeding responses become less effective in leading to the entry of food into the buccal cavity; when food does enter the buccal cavity, it exits sooner; swallowing responses after food entry are less likely to occur; Aplysia eventually cease responding to food. Pairing successful transfer of food into the crop with feeding behavior produces opposite effects. Behavioral change is specific to pairing, as shown by lack of change when reinforcement is explicitly unpaired with feeding behavior. Behavioral change is specific to foods with a particular taste and texture; generalization to alternate foods was not observed. In spite of cessation of feeding, animals remain aroused, as shown by low response latency to alternate foods. Memory of response change persists for at least 48 hr.
Distribution of intersegmental inputs to nonspiking local interneurons and motor neurons in the locust
Authors: Laurent G , Burrows M
Published: April 2018

Intersegmental interneurons in a mesothoracic population that receive inputs from extero- and proprioceptors on a middle leg of a locust (Laurent, 1987a) make direct synaptic connections with nonspiking local interneurons and motor neurons controlling the movements of the ipsilateral hindleg. Of 25 direct connections that were established, 80% are excitatory, and 60% are made with nonspiking interneurons. Two or more intersegmental interneurons with outputs of either polarity and with different or overlapping receptive fields can converge onto one metathoracic nonspiking interneuron. Direct connections were found with motor neurons of the coxotrochanteral, femorotibial, and tibiotarsal joints of the hindleg. An intersegmental interneuron can make divergent connections with several motor neurons of the same pool or with a motor neuron and a nonspiking interneuron presynaptic to it. By virtue of the lateral inhibitory connections between nonspiking interneurons controlling different pools of motor neurons (Burrows, 1979), an intersegmental interneuron can excite directly one pool and disynaptically inhibit the antagonistic pool. Metathoracic nonspiking interneurons also receive inputs from afferents of mechanoreceptors on a hindleg. They thus have 2 receptive fields: one on the hindleg whose motor neurons they control and one on the ipsilateral middle leg, provided by inputs from the mesothoracic intersegmental interneurons. Nonspiking local interneurons are thus a point of convergence of local and intersegmental pathways. The effectiveness of the intersegmental pathways can thus be modified by local inputs to the nonspiking interneurons.
Evidence for hippocampal regulation of neuroendocrine neurons of the hypothalamo-pituitary-adrenocortical axis
Authors: Herman JP , Schafer MK , Young EA , Thompson R , Douglass J , Akil H , Watson SJ
Published: April 2018

Expression of mRNAs coding for the ACTH secretagogues corticotropin- releasing factor (CRF) and arginine vasopressin (AVP) was examined in the hypothalamic paraventricular nucleus (PVN) of rats bearing hippocampal lesions. Either total hippocampectomy (HPX) or extirpation of the dorsal hippocampus (DHPX) precipitated a 4-fold increase in CRF mRNA expression relative to sham-operated controls (SHAM), as determined by semiquantitative in situ hybridization histochemistry. AVP mRNA was localized to individual parvocellular neurons of the medial parvocellular division of the PVN in only the HPX and DHPX groups, consistent with enhanced production of AVP message in this neuronal population subsequent to hippocampal damage. HPX did not affect AVP mRNA content in magnocellular divisions of PVN. Plasma beta- endorphin levels were significantly elevated in the HPX and DHPX groups relative to SHAM animals, indicating a chronic increase in release of proopiomelanocortin peptides from the anterior pituitary gland in response to hippocampal lesion. Circulating corticosterone levels were elevated in HPX rats as well. To control for effects of lesion size and location, additional animals received large ablations of cerebral cortex or cerebellum. In neither case was CRF or AVP mRNA significantly altered in the PVN. The results suggest that the hippocampus exercises a tonic inhibitory role on ACTH secretagogue production in neuroendocrine neurons promoting ACTH release.
Spatial selectivity and binaural responses in the inferior colliculus of the great horned owl
Authors: Volman SF , Konishi M
Published: April 2018

In this study we have investigated the processing of auditory cues for sound localization in the great horned owl (Bubo virginianus). Previous studies have shown that the barn owl, whose ears are asymmetrically oriented in the vertical plane, has a 2-dimensional, topographic representation of auditory space in the external division of the inferior colliculus (ICx). As in the barn owl, the great horned owl's ICx is anatomically distinct and projects to the optic tectum. Neurons in ICx respond over only a small range of azimuths (mean = 32 degrees), and azimuth is topographically mapped. In contrast to the barn owl, the great horned owl has bilaterally symmetrical ears and its receptive fields are not restricted in elevation. The binaural cues available for sound localization were measured both with cochlear microphonic recordings and with a microphone attached to a probe tube in the auditory canal. Interaural time disparity (ITD) varied monotonically with azimuth. Interaural intensity differences (IID) also changed with azimuth, but the largest IIDs were less than 15 dB, and the variation was not monotonic. Neither ITD nor IID varied systematically with changes in the vertical position of a sound source. We used dichotic stimulation to determine the sensitivity of ICx neurons to these binaural cues. Best ITD of ICx units was topographically mapped and strongly correlated with receptive-field azimuth. The width of ITD tuning curves, measured at 50% of the maximum response, averaged 72 microseconds. All ICx neurons responded only to binaural stimulation and had nonmonotonic IID tuning curves. Best IID was weakly, but significantly, correlated with best ITD (r = 0.39, p less than 0.05). The IID tuning curves, however, were broad (mean 50% width = 24 dB), and 67% of the units had best IIDs within 5 dB of 0 dB IID. ITD tuning was sensitive to variations in IID in the direction opposite to that expected for time-intensity trading, but the magnitude of this effect was only 1.5 microseconds/dB IID. We conclude that, in the great horned owl, the spatial selectivity of ICx neurons arises primarily from their ITD tuning. Except for the absence of elevation selectivity and the narrow range of best IIDs, ICx in the great horned owl appears to be organized much the same as in the barn owl.
Operant conditioning of head-waving in Aplysia. III. Cellular analysis of possible reinforcement pathways
Authors: Cook DG , Carew TJ
Published: April 2018

Operant conditioning of the head-waving response in Aplysia, as well as conditioning of the electrical activity of identified neck muscles, can be induced readily when bright light is used as aversive reinforcement (Cook and Carew, 1986, 1989b). A cellular analysis of this type of operant conditioning requires an understanding of the neural circuitry that underlies the reinforcement pathways involved in the conditioning. In the present paper we describe a cellular analysis of possible reinforcement pathways that mediate the aversive effects of bright light in the CNS of Aplysia. Using a semi-intact “split-body” preparation, we explored the effects of bright light on the operant response pathway by recording intracellularly from identified pedal neck and body wall motor neurons, which contribute to the operant response. In these experiments we identified 2 light-sensitive pathways. One pathway, from the eyes and rhinophores, mediated functional inhibition of light-induced excitation of pedal motor neurons. The other pathway, from the oral veil (cerebral ganglion nerves C1-C3) mediated significant excitation of the same motor cells. Randomly occurring blank trials ruled out the possibility that the light-induced effects were due to sampling bias. Finally, surgical isolation of the CNS from the periphery showed that none of the effects of light were due to direct illumination of central neurons. This identification of candidate reinforcement pathways will facilitate a cellular analysis of operant conditioning of head-waving in Aplysia.
A single-cell analysis of early retinal ganglion cell differentiation in Xenopus: from soma to axon tip
Authors: Holt CE
Published: April 2018

Intracellular injections of Lucifer yellow (LY) were made into the cell bodies of Xenopus retinal ganglion cells from the earliest stages of axonogenesis to the beginning of target innervation. Embryos were intact during the injection so that the entire cell (cell body, dendrites, axon, and growth cone) could be visualized. The purpose of the study was 3-fold: (1) to characterize the early steps in retinal ganglion cell differentiation before the axon reaches its target; (2) to determine whether guidepost cells exist as possible navigation cues in the vertebrate optic pathway; and (3) to investigate whether the morphology of early retinal ganglion cell growth cones varies in a position-dependent manner along the primordial optic pathway. Axons were generally initiated before dendrites and followed a well-defined course along the primordial optic pathway without branching. Surprisingly, at least 5% of the retinal ganglion cells sent more than one axon into the optic pathway. Sister axons from the same parent cell traveled separately in the pathway, indicating that their growth cones navigated independently. Examination of dendrite genesis showed that dendrites usually begin to emerge from the cell body well before the axon tip reaches the target. This observation argues against the possibility that target contact influences dendrite initiation. Nascent dendrites were commonly tipped with pronounced varicosities that did not resemble axon growth cones. Their number and branching correlated well with axon length, indicating that the age of the retinal ganglion cell itself, rather than the age of its presynaptic cells or local environment, is the strongest influence on dendrite genesis. Examination of LY-filled growth cones at varying points in the pathway showed no evidence of dye transfer to adjacent cells. This indicates that gap junctional contacts probably do not form during axonal pathfinding and suggests that direct intercellular communication between growing axons and other cells in the pathway does not play a major role in axon guidance. Growth cone morphology was analyzed quantitatively and found to vary at different positions along the pathway. Growth cones entering the optic nerve head were the largest and most complex; those on the retinal surface were the smallest and showed a simple morphology. Growth cones in the chiasm and optic tract showed a degree of complexity similar to those in the optic nerve head but were smaller.(ABSTRACT TRUNCATED AT 400 WORDS)
Compartments and the topography of leg afferent projections in Drosophila
Authors: Murphey RK , Possidente DR , Vandervorst P , Ghysen A
Published: April 2018

The legs of Drosophila are covered with mechanosensory bristles, innervated by sensory neurons that project to the CNS in a very orderly manner. We examined this afferent projection by staining the sensory neurons associated with identified bristles in wild-type, engrailed and scute flies. We observe that anterior neurons project to an anterior region of the ventral neuropil, while posterior neurons project to a more posterior region. We rule out that this difference depends on the compartment of origin of the receptors. Our results also argue against explanations based on other factors that might correlate to anterior/posterior position: peripheral organization of the leg nerve, competitive interactions, or differences in times of birth. We suggest that position itself is the primary determinant of this projection.
Modulation of ionic currents in Aplysia motor neuron B15 by serotonin, neuropeptides, and second messengers
Authors: Taussig R , Sweet-Cordero A , Scheller RH
Published: April 2018

Both 5-HT and the 9 amino acid neuropeptide SCPb modulate 3 ionic currents in B15, enhancing a voltage-dependent inward sodium current, decreasing an outward potassium current and increasing an inward rectifying potassium current. In contrast, FMRFamide decreases a voltage-dependent inward sodium current and increases an outward potassium current. We have also investigated the roles of several second-messenger systems that may be mediating the effects of these modulators. Bath application of membrane permeable analogs of cAMP enhance the voltage-dependent inward sodium current and both 5-HT and SCPb increase cAMP levels in B15, suggesting that cAMP may be mediating part of the observed effects of these transmitters on B15. Experiments with phorbol ester, a protein kinase inhibitor, and a phospholipase inhibitor suggest that the phospholipase C/protein kinase C cascade may decrease an outward potassium current. Thus, 5-HT and SCPb may activate multiple second-messenger systems to modulate 3 ionic currents in B15. Additional studies suggest that a cascade involving arachidonic acid may be involved in mediating part of the FMRFamide responses in B15. These studies are beginning to define molecular mechanisms whereby a neuron differentially modulates multiple ionic currents in response to distinct chemical messengers.
Visuomotor adaptation to displacing prisms by adult and baby barn owls
Authors: Knudsen EI , Knudsen PF
Published: April 2018

The capacity of barn owls to adapt visuomotor behavior in response to prism-induced displacement of the visual field was tested in babies and adults. Matched, binocular Fresnel prisms, which displaced the visual field 11 degrees, 23 degrees, or 34 degrees to the right, were placed on owls for periods of up to 99 d. Seven baby owls wore the prisms from the day the eyelids first opened; 2 owls wore them as adults. Prism adaptation was measured by the accuracy with which a target was approached and struck with the talons, a behavior similar to pointing behavior used commonly to assess prism adaptation in primates. Baby and adult owls exhibited a limited capacity to adapt this visuomotor behavior. Acquisition of adapted behavior was slow, taking place over a period of weeks, and was never complete even for owls that were raised viewing the world through relatively weak (11 degrees) displacing prisms. When the prisms were removed from adapted owls, they struck to the opposite side of the target. The recovery of strike accuracy following prism removal was rapid; 7 of 9 owls recovered normal accuracy within 30 min of prism removal, despite having worn the prisms for months. This limited capacity for adaptation contrasts dramatically with the extensive and rapid adaptation exhibited by adult primates exposed to comparable prismatic displacements. The mechanism of adaptation used by the owls was to alter the movements employed for approaching targets. Instead of moving straight ahead, the head and body moved diagonally relative to the orientation of the head. Thus, in contrast to prism adaptation by humans that can involve reinterpretation of eye, head, and limb position, prism adaptation by owls is based on changes in the motor commands that underlie approach behavior.
Vision calibrates sound localization in developing barn owls
Authors: Knudsen EI , Knudsen PF
Published: April 2018

This study demonstrates that continuous exposure of baby barn owls to a displaced visual field causes a shift in sound localization in the direction of the visual displacement. This implies an innate dominance of vision over audition in the development and maintenance of sound localization. Twelve owls were raised from the first day of eye opening wearing binocular prisms that displaced the visual field to the right by 11 degrees, 23 degrees, or 34 degrees. The prisms were worn for periods of up to 7 months. Consistent with previous results (Knudsen and Knudsen, 1989a), owls reared with displacing prisms did not adjust head orientation to visual stimuli. While wearing prisms, owls consistently oriented the head to the right of visual targets, and, as soon as the prisms were removed, they oriented the head directly at visual targets, as do normal owls. In contrast, prism-reared owls did change head orientation to sound sources even though auditory cues were not altered significantly. Birds reared wearing 11 degrees or 23 degrees prisms oriented the head to the right of acoustic targets by an amount approximately equal to the optical displacement induced by the prisms. Birds raised wearing 34 degrees prisms adjusted sound localization by only about 50% of the optical displacement. Thus, visually guided adjustment of sound localization appears to be limited to about 20 degrees in azimuth. The data indicate that when confronted with consistently discordant localization information from the auditory and visual systems, developing owls use vision to calibrate associations of auditory localization cues with locations in space in an attempt to bring into alignment the perceived locations of auditory and visual stimuli emanating from a common source. Vision exerts this instructive influence on sound localization whether or not visual information is accurate.
Developing cholinergic basal forebrain neurons are sensitive to thyroid hormone
Authors: Gould E , Butcher LL
Published: April 2018

The influence of thyroid hormone on the development of cholinergic neurons in nucleus basalis was assessed in hyperthyroid, hypothyroid, and euthyroid rats by use of CAT immunohistochemistry and single- section Golgi-impregnation histology. Animals were made either hyperthyroid by daily injections of 1.0 micrograms/gm body weight triiodothyronine starting at postnatal day (P) 3 or hypothyroid by providing 0.4% propylthiouracil in the diet of dams from P2. Compared to developing control rats, increased exposure to thyroid hormone resulted in accelerated expression of CAT in nucleus basalis neurons. Overshoot in cell body size, a normal developmental phenomenon of cholinergic neurons in the basal nuclear complex, occurred earlier in hyperthyroid brains and was of a greater magnitude than in controls. Furthermore, increased numbers of primary dendrites and dendritic branchpoints accompanied by dendritic and perisomal filopodia-like structures were observed for nucleus basalis neurons in hyperthyroid rats. These dendritic changes persisted throughout the second postnatal month. After the fifth postnatal week, cell body sizes of these hyperthyroid CAT-positive neurons began to decrease and by P50 were significantly less than controls or similarly treated animals at earlier ages. By P64, the number of cholinergic neurons in nucleus basalis was appreciably less than in age-matched controls. Hypothyroidism resulted in a delay of normal CAT expression that persisted throughout the third postnatal week. After this time, CAT staining increased until normal immunoreactivity was attained in cell bodies, fibers, and terminal regions by P35. A deficit in thyroid hormone during development prevented overshoot in perikaryal size and resulted in diminished cross-sectional areas throughout the cholinergic nucleus basalis at all ages examined. Hypothyroidism also prevented the normal overproduction of dendrites in those cells and produced stunted dendritic trees at all ages examined. These morphological abnormalities persisted throughout the second postnatal month. The effects of thyroid hormone on cholinergic projection neurons in the rat brain appeared relatively selective for cells in the basal nuclear complex because neither hypothyroid nor hyperthyroid treatment produced changes in the cell body areas of the phenotypically similar CAT-positive neurons of the pontomesencephalotegmental complex.(ABSTRACT TRUNCATED AT 400 WORDS)
Head-direction cells recorded from the postsubiculum in freely moving rats. I. Description and quantitative analysis
Authors: Taube JS , Muller RU , Ranck JB
Published: April 2018

This paper is a study of the behavioral and spatial firing correlates of neurons in the rat postsubiculum. Recordings were made from postsubicular neurons as rats moved freely throughout a cylindrical chamber, where the major cue for orientation was a white card taped to the inside wall. An automatic video/computer system monitored cell discharge while simultaneously tracking the position of 2 colored light emitting diodes (LEDs) secured to the animal's head. The animal's location was calculated from the position of one of the LEDs and head direction in the horizontal plane calculated from the relative positions of the 2 LEDs. Approximately 26% of the cells were classified as head-direction cells because they discharged as a function of the animal's head direction in the horizontal plane, independent of the animal's behavior, location, or trunk position. For each head-direction cell, vectors drawn in the direction of maximal firing were parallel throughout the recording chamber and did not converge toward a single point. Plots of firing rate versus head direction showed that each firing-rate/head-direction function was adequately described by a triangular function. Each cell's maximum firing rate occurred at only one (the preferred) head direction; firing rates at head directions on either side of the preferred direction decreased linearly with angular deviation from the preferred direction. Results from 24 head-direction cells in 7 animals showed an equal distribution of preferred firing directions over a 360 degrees angle. The peak firing rate of head- direction cells varied from 5 to 115 spikes/sec (mean: 35). The range of head-direction angles over which discharge was elevated (directional firing range) was usually about 90 degrees, with little, if any, discharge at head directions outside this range. Quantitative analysis showed the location of the animal within the cylinder had minimal effect on directional cell firing. For each head-direction cell, the preferred direction, peak firing rate, and directional firing range remained stable for days. These results identify a new cell type that signals the animal's head direction in its environment.