Dopamine inhibits cytosolic Ca2+ increases in rat lactotroph cells. Evidence of a dual mechanism of action.

Single rat lactotroph cells were studied after loading with the cytosolic free Ca2+ concentration ([Ca2+]i) indicator fura-2 either 1 or 3 days after cell dispersion. Under unstimulated conditions, two groups of lactotrophs were observed, the first (predominant at day 1) with large [Ca2+]i fluctuations (peaks up to 300 nM) probably due to spontaneous action potentials and the second (predominant at 3 days) with stable [Ca2+]i (values variable between 65 and 200 nM). The effect of dopamine on the resting [Ca2+]i was different in the two groups. Even at high dopamine concentrations, no change occurred in the second group; whereas in the first, disappearance of fluctuations and marked decrease of [Ca2+]i were observed. These effects of dopamine appear to be due to hyperpolarization that was demonstrated by the use of a specific fluorescent indicator, bis(oxonol). Two types of triggered [Ca2+]i transients were studied in detail: those due to redistribution of Ca2+ from the intracellular stores (induced by thyrotropin-releasing hormone) and those due to Ca2+ influx through voltage-gated Ca2+ channels (induced by high [K+]). Dopamine (1 microM) markedly inhibited both these transients by the action of D2 receptors (blocked by 1-sulpiride and domperidone). All effects of dopamine were prevented by treatment of the cells with pertussis toxin, indicating the involvement of one (or more) GTP-binding protein(s). Another consequence of D2 receptor activation is the inhibition of adenylate cyclase. Treatments (cholera toxin, forskolin), known to raise cAMP levels, were found to dissociate the effects of dopamine on [Ca2+]i inasmuch as they markedly relieved the inhibition of the redistributive transients by thyrotropin-releasing hormone but left hyperpolarization and inhibition of K+ transients unaffected. The spectrum of intracellular signals elicited by the activation of D2 receptors is therefore complex and includes at least two mechanisms that involve [Ca2+]i, one related and the other independent of the decrease of cAMP levels

Tumor promoter phorbol myristate acetate inhibits Ca2+ influx through voltage-gated Ca2+ channels in two secretory cell lines, PC12 and RINm5F.

Protein kinase C is known to be involved both in initiation and termination of cellular responses due to phosphoinositide breakdown. Here we report that in PC12 cells (a line of neurosecretory cells derived from a rat pheochromocytoma), pretreatment with nanomolar concentrations of phorbol myristate acetate, PMA, which is believed to specifically activate protein kinase C, inhibits the cytosolic-free Ca2+ concentration rise induced by depolarizing agents. In contrast, plasma membrane potential and 45Ca efflux from preloaded cells were unaffected by PMA pretreatment. Inhibition by PMA and diacylglycerol of the cytosolic-free Ca2+ concentration rise induced by depolarization was observed also in another cell line, the insulin secreting line RINm5F. These results raise the possibility that the voltage-gated Ca2+ channel is under inhibitory control by protein kinase C

Correlation of Shear Bond Strength and Degree of Conversion in Conventional and Self-Adhesive Systems Used in Orthodontic Bonding Procedures

Abstract (1) Background: Self-adhesive systems have been proposed for the orthodontic bonding with the intention to reduce the traditional three-component system. (2) Methods: The sample consisted of 32 extracted intact permanent premolars randomly divided into two groups (n = 16). In Group I the metal brackets were bonded with Transbond XT Primer and Transbond XT Paste. In Group II the metal brackets were bonded with GC Ortho connect. The resin was polymerized for 20 s from two directions (mesial and occlusal) using a Bluephase light-curing unit. The shear bond strength (SBS) was measured using a universal testing machine. Immediately after SBS testing, Raman microspectrometry was performed for each sample to calculate the degree of conversion (DC). (3) Results: There was no statistically significant difference in the SBS between the two groups. A significantly higher DC (p < 0.001) value was recorded in Group II, in which the brackets were bonded with GC. Very weak or no correlation (0.01) was recorded between SBS and DC in Group I and moderate positive correlation was recorded in Group II (0.33). (4) Conclusions: No difference was found in SBS between the conventional and two-step systems used in orthodontics. The two-step system demonstrated higher DC compared to the conventional system. There is a very weak or moderate correlation between DC and SBS

Motion-capture patterns of dynamic facial expressions in children and adolescents with and without ASD

Research shows that neurotypical individuals struggle to interpret the emotional facial expressions of people with Autism Spectrum Disorder (ASD). The current study uses motion-capture to objectively quantify differences between the movement patterns of emotional facial expressions of individuals with and without ASD. Participants volitionally mimicked emotional expressions while wearing facial markers. Recorded marker movement was grouped by expression valence and intensity. We used Growth Curve Analysis to test whether movement patterns were predictable by expression type and participant group. Results show significant interactions between expression type and group, and little effect of emotion valence on ASD expressions. Together, results support perceptions that expressions of individuals with ASD are different from -- and more ambiguous than -- those of neurotypical individuals’

Accuracy of the digital workflow for guided insertion of orthodontic palatal TADs: a step-by-step 3D analysis

BACKGROUND: The introduction in the orthodontic field of the digital workflow for guided insertion of palatal TADs and the development of the 1-visit protocol led to the reduction of chair time and the possibility of complete customization of designs and materials. Conversely, the reduction of operative steps implicates a lower tolerance of deviations between the planned and the actual position of the miniscrews, particularly when the orthodontic device is fixed on 4 palatal TADs or has a rigid structure. This study aims to analyze the influence of each step of the digital workflow on the deviation of the miniscrews' axis of insertion in a bicortical sample. The null hypothesis is that there are no significant differences in the deviations among the operative steps. METHODS: 33 subjects were selected for insertion of bicortical palatal miniscrews with a 1-visit protocol. Digital files were collected at the three stages of the workflow (i.e., digital planning, laboratory prototype, post-insertion impression). A 3D software analysis was performed on a total of 64 miniscrews. After automatic shape recognition of the guiding holes of the digital plan and the scanbodies of the laboratory prototype and post-insertion impression as geometric cylinders, their three-dimensional longitudinal axis was traced and the deviation among them was calculated. Friedman test with Bonferroni correction was performed to assess the significance of the deviations among the three steps, with significance set at p < 0.05. RESULTS: The laboratory step has a significantly lower degree of deviations (2.12° ± 1.62) than both the clinical step (6.23° ± 3.75) and the total deviations (5.70° ± 3.42). No significant differences were found between miniscrews inserted on the left or the right side. CONCLUSIONS: This study suggests that laboratory procedures such as surgical guide production or rapid prototyping don't play a significant role in the degree of deviations between the planned and the positioned palatal TADs. Conversely, the clinical steps have a bigger influence and need to be carefully evaluated. Despite this difference, there is a cumulative effect of deviations that can lead to the failure of the 1-visit protocol

Second language processing and revision of garden-path sentences: a visual word study

Tower of post office and plaza clock, viewed from Zaanstraat; This five-storey building with 102 dwellings, a post office (2 storeys), a meeting hall for residents and the annexed school is the best example of what was termed a "worker's palace" in Amsterdam. There are 18 different floor plans for the units. In 1917 the housing association Eigen Haard commissioned de Klerk again for a block in the Spaarndammerbuurt neighborhood. A few years earlier a school had been built near the triangular site on Oostzannstraat and de Klerk was required to include it in the plan. At the apex of the triangle is the post office, resembling a huge piece of sculpture. De Klerk also designed the interior of the post office; the counters, seats and even telephone booth. At the center of the triangular block are private gardens and the school playground. It is not by chance that all the formal comparisons for the building, ranging from ship to locomotive, suggest, together with associations with movement and power, an organic entity with identifiable components. Today the Museum Het Schip is housed in the post office, with an extension in the school. Source: Casciato, Maristella, ed.; The Amsterdam School, Rotterdam: 010 Publishers, 1996 (9064502463) (accessed 6/10/2014

English possessive gender agreement in production and comprehension: Similarities and differences between young monolingual English learners and adult Mandarin-English second language learners

Second language learners of English occasionally establish gender agreement between a possessive determiner and the local noun that follows it, rather than with its target antecedent (*"Maryi loves hisi brother"). The production and comprehension profiles of adult Mandarin second language learners of English and monolingual English-speaking children were examined to establish (a)if such errors result from an inherent tendency to establish agreement locally within the noun phrase or rather from transfer of first language agreement procedures, and (b)if these errors are production specific or rather reflect nontarget grammatical representations, thus also affecting comprehension. The results of the elicited production portion of the study support the hypothesis that gender agreement errors in learners' production of possessives result from a generalized tendency to establish local agreement. The results of the comprehension portion of the study suggest that the observed tendency for local agreement within the noun phrase is production specific and does not characterize learners' grammatical representations as a whole

Long-lasting Changes of Calcium Oscillations in Astrocytes A NEW FORM OF GLUTAMATE-MEDIATED PLASTICITY

Long-term changes of synaptic strength in the central nervous system are mediated by an increase of cytosolic calcium concentration ([Ca2+]i) following activation of excitatory neurotransmitter receptors. These phenomena, which represent a possible cellular basis for learning and memory processes in eukaryotes, are believed to be restricted to neurons. Here we provide evidence for a long-term change of the response elicited by the excitatory neurotransmitter glutamate in a non-neuronal cell population of the central nervous system, i.e. visual cortical astrocytes in culture. Stimulation with glutamate induces in astrocytes a regular pattern of [Ca2+]i oscillations. A second stimulation, after an interval ranging from 2 to 60 min, induces an oscillatory response characterized by an increased frequency. Induction of this change in the astrocyte response is abolished by a specific inhibitor of the nitric oxide synthase and recovers upon exogenous nitric oxide generation or addition of a permeant cGMP analogue. Local brief pulses of glutamate to individual astrocytes, at a rate of 1 Hz, also elicit [Ca2+]ioscillations whose frequency increases following a second series of pulses. The long-lasting modification in the [Ca2+]i oscillatory response induced by glutamate in astrocytes demonstrates that in the central nervous system cellular memory is not a unique feature of neurons