High-pressure and -temperature ion exchange of aluminosilicate and gallosilicate natrolite.

The simultaneous application of high pressure and high temperature has been used to achieve direct ion exchange of large cesium cations for the small sodium cations found in the zeolite natrolite by putting it into a superhydrated state with increased pore size. The larger cations remain trapped upon pressure release, and thus, this method is a means of producing new cationic forms of zeolites.

Dopamine, but not serotonin, regulates reversal learning in the marmoset caudate nucleus.

Studies of visual discrimination reversal learning have revealed striking neurochemical dissociations at the level of the orbitofrontal cortex (OFC) with serotoninergic, but not dopaminergic, integrity being important for successful reversal learning. These findings have considerable implications for disorders such as obsessive compulsive disorder and schizophrenia, in which reversal learning is impaired, and which are primarily treated with drugs targeting the dopaminergic and serotoninergic systems. Dysfunction in such disorders however, is not limited to the OFC and extends subcortically to other structures implicated in reversal learning, such as the medial caudate nucleus. Therefore, because the roles of the serotonin and dopamine within the caudate nucleus are poorly understood, this study compared the effects of selective serotoninergic or selective dopaminergic depletions of the marmoset medial caudate nucleus on serial discrimination reversal learning. All monkeys were able to learn novel stimulus-reward associations but, unlike control monkeys and monkeys with selective serotoninergic medial caudate depletions, dopamine-depleted monkeys were markedly impaired in their ability to reverse this association. This impairment was not perseverative in nature. These findings are the opposite of those seen in the OFC and provide evidence for a neurochemical double dissociation between the OFC and medial caudate in the regulation of reversal learning. Although the specific contributions of these monoamines within the OFC-striatal circuit remain to be elucidated, these findings have profound implications for the development of drugs designed to remediate some of the cognitive processes underlying impaired reversal learning.

Autonomic, behavioral, and neural analyses of mild conditioned negative affect in marmosets.

Avoidance and alerting behaviors and accompanying physiological responses, including changes in heart rate (HR), are core components of negative emotion. Investigations into the neural mechanisms underlying the regulation and integration of these responses require animal models that simultaneously measure both the physiological and behavioral components of emotion. A primate model is of particular importance in view of the well developed prefrontal cortex of primates, and this region's critical role in emotion regulation and the etiology of affective disorders. Therefore, we have developed a simple aversive conditioning paradigm to assess, simultaneously, cardiovascular and behavioral responses in the marmoset (Callithrix jacchus). Validation of the paradigm was achieved by (1) comparing conditioned responses to a predictive cue with pseudoconditioned responses to a nonpredictive cue; (2) assessing the acquisition of conditioning following lesions of the amygdala, a region essential for associative learning in humans and rats; and (3) determining the contributions of the sympathetic and parasympathetic nervous system to the conditioned autonomic responses. Marmosets acquired conditioned HR and behavioral responses in the conditioned, but not the pseudoconditioned or amygdala lesioned groups. Conditioned HR accelerations were reduced by both parasympathetic and sympathetic blockade. Thus, a model of associative learning of mild negative emotion in the marmoset has been validated by psychological, neurological, and pharmacological investigation. Future studies will determine the role of the prefrontal cortex in the regulation of these negative emotional responses, to provide insights into the neuropathology of affective disorders.

Single linkage group per chromosome genetic linkage map for the horse, based on two three-generation, full-sibling, crossbred horse reference families.

A genetic linkage map of the horse consisting of 742 markers, which comprises a single linkage group for each of the autosomes and the X chromosome, is presented. The map has been generated from two three-generation full-sibling reference families, sired by the same stallion, in which there are 61 individuals in the F2 generation. Each linkage group has been assigned to a chromosome and oriented with reference to markers mapped by fluorescence in situ hybridization. The average interval between markers is 3.7 cM and the linkage groups collectively span 2772 cM. The 742 markers comprise 734 microsatellite and 8 gene-based markers. The utility of the microsatellite markers for comparative mapping has been significantly enhanced by comparing their flanking sequences with the human genome sequence; this enabled conserved segments between human and horse to be identified. The new map provides a valuable resource for genetically mapping traits of interest in the horse.

The effect of low-intensity pulsed ultrasound on repair of epithelial cell monolayers in vitro.

Low intensity pulsed ultrasound (LIPUS) is widely used to accelerate tissue regeneration following injury, but the biological mechanisms of this effect are poorly understood. An in vitro model of epithelial wound healing was used to investigate the effect of LIPUS on the reepithelialization of scrape wounds in normal human urothelial (NHU) cell monolayers. The effects of clinical doses of ultrasound treatment on NHU cell growth and migration were investigated in cells grown under optimal conditions, without growth supplements and in media containing low vs. physiological calcium concentrations. No differences in cell growth or migration were observed. We conclude that there is no direct effect upon uro-epithelial regeneration by therapeutic ultrasound in vitro and suggest that any stimulation of epithelial wound repair in vivo may occur indirectly, for example by modulating the extracellular matrix composition and/or production of paracrine factors by the stroma.

Autocrine regulation of human urothelial cell proliferation and migration during regenerative responses in vitro.

Regeneration of the urothelium is rapid and effective in order to maintain a barrier to urine following tissue injury. Whereas normal human urothelial (NHU) cells are mitotically quiescent and G0 arrested in situ, they rapidly enter the cell cycle upon seeding in primary culture and show reversible growth arrest at confluency. We have used this as a model to investigate the role of EGF receptor signaling in urothelial regeneration and wound-healing. Transcripts for HER-1, HER-2, and HER-3 were expressed by quiescent human urothelium in situ. Expression of HER-1 was upregulated in proliferating cultures, whereas HER-2 and HER-3 were more associated with a growth-arrested phenotype. NHU cells could be propagated in the absence of exogenous EGF, but autocrine signaling through HER-1 via the MAPK and PI3-kinase pathways was essential for proliferation and migration during urothelial wound repair. HB-EGF was expressed by urothelium in situ and HB-EGF, epiregulin, TGF-alpha, and amphiregulin were expressed by proliferating NHU cells. Urothelial wound repair in vitro was attenuated by neutralizing antibodies against HER-1 ligands, particularly amphiregulin. By contrast, the same ligands applied exogenously promoted migration, but inhibited proliferation, implying that HER-1 ligands provoke differential effects in NHU cells depending upon whether they are presented as soluble or juxtacrine ligands. We conclude that proliferation and migration during wound healing in NHU cells are mediated through an EGFR autocrine signalling loop and our results implicate amphiregulin as a key mediator.