Involvement of tissue plasminogen activator-plasmin system in depolarization-evoked dopamine release in the nucleus accumbens of mice

Tissue plasminogen activator (tPA), a serine protease, catalyzes the conversion of plasminogen to plasmin. In the present study, we investigated the role of the tPA-plasmin system in depolarization-evoked dopamine (DA) and acetylcholine (ACh) release in the nucleus accumbens (NAc) and hippocampus, respectively, of mice, by using in vivo microdialysis. Microinjection of either tPA or plasmin significantly potentiated 40 mM KCl-induced DA release without affecting basal DA levels. In contrast, plasminogen activator inhibitor-1 dose-dependently reduced 60 mM KCl-induced DA release. The 60 mM KCl-evoked DA release in the NAc was markedly diminished in tPA-deficient (tPA-/-) mice compared with wild-type mice, although basal DA levels did not differ between the two groups. Microinjections of either exogenous tPA (100 ng) or plasmin (100 ng) into the NAc of tPA-/-mice restored 60 mM KCl-induced DA release, as observed in wild-type mice. In contrast, there was no difference in either basal or 60 mM KCl-induced ACh release in the hippocampus between wild-type and tPA-/-mice. Our findings suggest that the tPA-plasmin system is involved in the regulation of depolarization-evoked DA release in the NAc.     

Electrophysiological and neurochemical characterization of the effect of repeated treatment with milnacipran on the rat serotonergic and noradrenergic systems

The present study was undertaken to elucidate the effects of repeated treatment with milnacipran, a serotonin (5-HT) and noradrenaline (NA) reuptake inhibitor (SNRI), on the synaptic plasticity in the hippocampal CA1 field, focusing on the interaction between the serotonergic and noradrenergic system. Repeated treatment with milnacipran (30 mg/kg, i.p. after 30 mg/kg, p.o. x 14 days) completely restored the suppression of the long-term potentiation (LTP) induced by single milnacipran treatment (30 mg/kg, i.p.). Single and repeated milnacipran increased to a similar extent extracellular NA in the hippocampus. Single milnacipran increased extracellular 5-HT and this effect tended to be enhanced by repeated treatment. The restoration of LTP and facilitation of the 5-HT level were not shown after repeated treatment with a selective 5-HT reuptake inhibitor (SSRI) fluvoxamine (30 mg/kg, p.o. x 14 days). These results suggest that milnacipran-induced restoration of LTP suppression is responsible for the enhancement of 5-HT neurotransmission, which appears to be associated with noradrenergic neuronal activity. In addition, the 5-HT1A receptor agonist tandospirone-induced suppression of LTP was completely blocked by repeated treatment with milnacipran, indicating the possibility that this reversal effect is due to the functional changes in postsynaptic 5-HT1A receptors. Taken together, the present data suggest that the interaction between the serotonergic and noradrenergic mechanism play an important role in the modulation of synaptic plasticity caused by repeated treatment with milnacipran, which may be implicated in the therapeutic effects of SNRI on psychiatric disorders.     

Genetic heterogeneity of urease gene loci in urease-positive thermophilic Campylobacter (UPTC)

Degenerate PCR primers in silico based on the two urease structural genes, ureA and ureB, were designed for urease-positive thermophilic Campylobacter (UPTC). Resultant PCR amplification employing these primers generated an amplicon of approximately 2kb, which was cloned and sequenced in UPTC (n=12) isolated from various parts of Europe and Japan. Overall, sequence similarities were shown to be 96.7 to 99.9%. Following sequence alignment analysis, the approximate 1.96kb regions were deduced to consist of parts of ureA (about 570bps) and ureB (about 1390bps) with an overlapping region between the ureA and ureB gene loci. Although a total of 144 heterogeneous sites of all substitutions were located throughout this region, the substitution ratio was higher in the ureA region (1/Omega10bases) than in the ureB region (1/Omega15bases). A resulting dendrogram was constructed, which was based on the nucleotide sequence data of 12 UPTC isolates and demonstrated that the UPTC were genetically variable. They formed a major cluster with Helicobacter, separate from the other urease-producing bacteria examined, suggesting a shared ancestry between UPTC and Helicobacter.     

Dissolution characteristics of cylindrical particles and tablets

In this paper, dissolution characteristics of primary-particles and compressed tablets were investigated by experiments using a mathematical model. For the primary-particle, it was found that the dissolution rate increased with a decrease in the particle size. Assuming that primary-particles of size distribution were of cylindrical shape and that the dissolution occurs from the total external surface, an extended Nernst–Noyes–Whitney equation fitted to the experimental data well. As the influences of particle size and shape on thickness of a diffusion-boundary film were found to be quite low, the dissolution rate was considered to be affected by the specific surface area dominantly. Furthermore, the same model was applied to a compressed tablet and fitted to the data well. Though the rate constant obtained were not affected by the properties of primary-particles forming the tablet, it was found to increase with the apparent voidage which occupies the inter-particle volume of tablet diluent among less soluble particles. Consequently, an increase in the apparent voidage is presumed to accelerate penetration of water into the internal voids of the tablet. Thus, the dissolution going, the effective surface area inside the tablet is considered to be extended.     

A resectable case of gastrointestinal stromal tumor derived from the rectal wall after oral targeted molecular therapy with imatinib mesylate

We performed targeted molecular therapy in a patient with a non-resectable pelvic gastrointestinal stromal tumor (GIST). Imatinib mesylate was administered at 400-600 mg/day for 6 months, and the tumor became resectable. The patient was a 58-year-old female who visited a gynecologic hospital with the chief complaint of a swollen feeling in the lower abdomen. A pelvic tumor was found by imaging, and the patient was referred to our hospital. Laparotomy was performed, but it was found that the tumor arose from the intestinal serous membrane, rather than from the uterus, and complete excision was difficult. A portion of the tumor tissue was excised, and the abdomen was closed. GIST was diagnosed on postoperative pathological examination, and the tissue was positive for c-kit protein on immunostaining. The tumor had markedly shrunk after oral administration of imatinib mesylate for 6 months, and excision by laparotomy became possible.     

High sensitive analysis of rat serum bile acids by liquid chromatography/electrospray ionization tandem mass spectrometry

Sensitive liquid chromatography (LC)/electrospray ionization (ESI) tandem mass spectrometry (MS) can be used to analyze the bile acid composition of rat serum. This method can analyze eight common bile acids and their glycine and taurine conjugates in 100 μl rodent serum by gradient elution on a reversed-phase column using a mixture of 20 mM ammonium acetate buffer (pH 8.0), acetonitrile and methanol as a mobile phase. Selected reaction monitoring analysis under negative ion detection mode allowed the achievement of a high sensitive assay with a simple solid phase extraction using an ODS cartridge column. We used this method to investigate the effect of a one-day fast on the concentration and composition of serum bile acids in rats. The results suggested that the method described here is useful for the dynamic analysis of serum bile acids in rats.     

Polygraphic study during whole night sleep in infantile spasms.

The whole night EEG were polygraphically recorded and analyzed in 9 patients with infantile spasms prior to ACTH therapy. The subjects were divided into two groups, favorable and unfavorable, depending upon the response to the ACTH therapy. (1) Among the unfavorable group, the deep sleep stage was not observed; while the light sleep stage tended to dominate. (2) REM sleep period was noted less among the unfavorable than among the favorable group. REM density also tended to be lower among the unfavorable group. (3) Of the 4 unfavorable cases, 2 did not manifest REM sleep at all. Of the remaining 2, 1 had a remarkably long REM interval period. Even among the favorable cases, REM sleep tended to be short and appear frequently. (4) The period of muscle atonia during NREM sleep was markedly prolonged in all cases. (5) Body movements of both types (gross and twitch) were less frequent comparing to those of normal younger children, more remarkably in unfavorable cases. From the above findings, a disorder of the pontine reticular formation would be suggested in cases of infantile spasms. Reduction of body movements at each sleep stage might indicate abnormalities of monoamine metabolism in the brain stem of patients with this condition.