There is increasing interest in the bidirectional communication between the mammalian host and prokaryotic cells. Catecholamines (CA), candidate molecules for such communication, are presumed to play an important role in the gut lumen; however, available evidence is limited because of the lack of actual data about luminal CA. This study evaluated luminal CA levels in the gastrointestinal tract and elucidated the involvement of gut microbiota in the generation of luminal CA by comparing the findings among specific pathogen-free mice (SPF-M), germ-free mice (GF-M), and gnotobiotic mice. Substantial levels of free dopamine and norepinephrine were identified in the gut lumen of SPF-M. The free CA levels in the gut lumen were lower in GF-M than in SPF-M. The majority of CA was a biologically active, free form in SPF-M, whereas it was a biologically inactive, conjugated form in GF-M. The association of GF-M with either Clostridium species or SPF fecal flora, both of which have abundant β-glucuronidase activity, resulted in the drastic elevation of free CA. The inoculation of E. coli strain into GF-M induced a substantial amount of free CA, but the inoculation of its mutant strain deficient in the β-glucuronidase gene did not. The intraluminal administration of DA increased colonic water absorption in an in vivo ligated loop model of SPF-M, thus suggesting that luminal DA plays a role as a proabsorptive modulator of water transport in the colon. These results indicate that gut microbiota play a critical role in the generation of free CA in the gut lumen.

Background There is increasing evidence suggesting the existence of an interaction between commensal microbiota, the gut and the brain. The aim of this study was to examine the influence of commensal microbiota on the host behaviors in a contaminationfree environment, which was verified by culture-based methods. Methods Open-field and marble-burying tests were used to analyze anxiety-like behaviors and locomotor activity in gnotobiotic BALB/c mice with a common genetic background in a sterile isolator. The monoamine levels in several regions of the brain were measured in germfree (GF) mice and commensal fecal microbiota-associated mice (EX-GF). Key Results A 24-h exposure to the environment outside the sterile isolators rendered GF mice less anxious than those not contaminated, while there was no change in the locomotion. EX-GF mice, the gnotobiotic mice with normal specific pathogen-free microbiota, were less anxious and active than GF mice using open-field and marble-burying tests. The norepinephrine, dopamine, and serotonin turnover rates were higher in the EX-GF mice than in the GF mice in most regions of the brain, suggesting that monoaminergic neurotransmission might increase in the EX-GF mice comparing the GF mice. Monoassociation with Brautia coccoides reduced the anxiety level, but it did not affect the locomotor activity. In contrast, colonization with Bifidobacterium infantis decreased the locomotor activity, while having little effect on the anxiety level. Conclusions & Inferences These results strongly support the current view that gut microorganisms modulate brain development and behavior.

Rho-independent transcription terminators of the genes encoding bacterial Hfq-binding sRNAs possess a set of seven or more T residues at the 3 ′ ′ ′ ′ ′ end, as noted in previous studies. Here, we have studied the role of the terminator hairpin in the biogenesis of sRNAs focusing on SgrS and RyhB in Escherichia coli. We constructed variant sRNA genes in which the GC-rich inverted repeat sequences are extended to stabilize the terminator hairpins. We demonstrate that the extension of the hairpin stem leads to generation of heterogeneous transcripts in which the poly(U) tail is shortened. The transcripts with shortened poly(U) tails no longer bind to Hfq and lose the ability to repress the target mRNAs. The shortened transcripts are generated in an in vitro transcription system with purified RNA polymerase, indicating that the generation of shortened transcripts is caused by premature transcription termination. We conclude that the terminator structure of sRNA genes is optimized to generate functional sRNAs. Thus, the Rho-independent terminators of sRNA genes possess two common features: a long T residue stretch that is a prerequisite for generation of functional sRNAs and a moderate strength of hairpin structure that ensures the termination at the seventh or longer position within the consecutive T stretch. The modulation of the termination position at the Rho-independent terminators is critical for biosynthesis of functional sRNAs.

Thoracic epidural anesthesia (TEA) and paravertebral block (PVB) have been performed for perioperative regional anesthesia in the trunk. However, TEA and PVB are associated with a risk of serious complications, such as pneumothorax, hypotension, or nerve damage. Retrolaminar paravertebral block (RLB) was introduced as a new alternative to PVB. This new approach might lower the risk of serious complications, but its use has not been well established yet. Therefore, we conducted a double-masked, placebo-controlled, randomized clinical trial to evaluate the efficacy of a double-level RLB for postoperative analgesia after breast cancer surgery. A total of 122 women who underwent breast cancer surgery with axillary lymph node dissection under general anesthesia were allocated into RLB group (60 patients) and Control group (62 patients). RLB was performed upon surgery completion with 15 ml ropivacaine (0.5%) for each lamina of the T2 and T4 vertebrae. In Control group, the same volume of normal saline was injected at each level. The time to first postoperative analgesic administration was significantly longer in RLB group than that in Control group (161.5 min vs. 64.0 min). The pain score in RLB group was significantly lower immediately after surgery. However, the number of patients requiring analgesics during the 12-hour post-surgical period was similar between RLB group (20 patients) and Control group (22 patients). In conclusion, the double-level RLB could delay the time to initial administration of analgesics, but this technique may be insufficient to reduce the analgesic requirement within the 12-hour postoperative period following breast cancer surgery.

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