H5N8 avian influenza virus acquires enhanced pathogenicity after a single passage in chicken.

The H5N8 highly pathogenic avian influenza viruses (HPAIVs) isolated in Japan during the 2014-2015 winter differed in their pathogenicity in chickens. In the present study, we examined the possibility that a comparatively less pathogenic strain was first brought into the country by migratory birds, and then acquired enhanced pathogenicity by infecting chicken flocks. We showed that the A/tundra swan/Tottori/C6nk/2014 (H5N8) (Tottori P0) strain required 10 days to kill all chickens via the intranasal route. However, Tottori P1-B, a strain recovered from the brain of a chicken infected with parental Tottori P0, showed enhanced pathogenicity; Tottori P1-B replicated significantly in the lung and liver, and killed all infected birds within 6 days, which was comparable to a chicken farm isolate obtained in the same season, A/environment/Miyazaki/11/2014 (H5N8). Tottori P1-B showed more marked proliferation in MDCK and chicken fibroblast cells, especially during the early phase of infection. Sequence analysis revealed a single mutation, M374 V, in nucleoprotein (NP) of the passaged virus, and this substitution was conserved after a further inoculation study. Position 374 in NP is located in the functional domain interacting with polymerase protein, PB2, indicating that viral polymerase activity was involved in the rapid growth of Tottori P1-B in vitro and in vivo. These results suggest that HPAIV, which originally had comparatively low pathogenicity to chickens, can increase its pathogenicity through the infection from migratory birds to domestic chickens.

Effects of atropine sulfate and neostigmine on gastric electrical activity in human subjects--electrogastrographic study.

BACKGROUND/AIMS: There are few reports about the cholinergic regulation of gastric electrical activities using percutaneous electrogastrograms (EGG). To determine the effect of intravenous administration of a vagal blocker (atropine sulfate) or a vagal stimulator (neostigmine) on gastric electrical activities EGG was utilized in this study. METHODOLOGY: EGG was recorded before and after administration of a vagal blocker (atropine sulfate, 0.02mg/kg) and/or vagal stimulator (neostigmine, 0.008mg/kg) in six normal volunteers. RESULTS: After administration of atropine sulfate, the original waves on EGG almost disappearedand decreased amplitudes were detected by visual inspection in all subjects. Moreover, increase amplitude on EGG was clearly demonstrated after administration of neostigmine in all subjects. It was also shown that the effects of these medicines persisted more than 60 minutes after injection. CONCLUSIONS: These findings suggest that the EGG reflected gastric motility, and that neurological regulation of EGG was mediated through the vagal and/or cholinergic efferent pathway.

Anatomical evidence of regional specific effects of acupuncture on gastric motor function in rats.

To obtain the anatomical evidences of possible neural pathways in mediating acupuncture-induced gastric motor responses, we studied c-Fos immunohistochemistry of the brain stem in response to acupuncture in rats. Acupuncture needles were inserted at the bilateral acupoints of ST-36 (lower limb) or ST-25 (abdomen) for 30 min. After acupuncture, the brainstem was removed for c-Fos immunohistochemistry. The total number of c-Fos immunopositive cells was counted in the dorsal motor nucleus of the vagus (DMV), the nucleus tractus solitarius (NTS) and the rostral ventrolateral medulla (RVLM). Acupuncture at ST-36, but not ST-25, significantly increased the number of c-Fos immunopositive cells at the DMV to 6.7 +/- 0.4 cells/section, compared to that of controls (1.7 +/- 0.2 cells/section) (n=5, P<0.05). Acupuncture at ST-25, but not ST-36, significantly increased the number of c-Fos immunopositive cells at the RVLM to 12.6 +/- 0.8 cells/section, compared to that of controls (4.2 +/- 0.7 cells/section) (n=5, P<0.05). Acupuncture at ST-36 also increased the number of c-Fos immunopositive cells at the medio-caudal and caudal NTS. On the other hand, acupuncture at ST-25 increased the number of c-Fos immunopositive cells at the medio-caudal NTS. It is suggested that somatic afferents activated by acupuncture at ST-36 is conveyed to the medio-caudal and caudal NTS and stimulates the DMV neurons. In contrast, somatic afferents activated by acupuncture at ST-25 is conveyed to the medio-caudal NTS and stimulates the RVLM neurons. The RVLM neurons are known as premotor sympatho-excitatory neurons that provide drive to the sympathetic preganglionic neurons in the intermediolateral nucleus of the spinal cord. Thus, acupuncture at ST-36 stimulates gastric motility via vagal efferents, while acupuncture at ST-25 inhibits gastric motility via sympathetic efferents in rats.

Gastric arrhythmia and nausea of motion sickness induced in healthy Japanese subjects viewing an optokinetic rotating drum.

The purpose of this study was to investigate whether nausea or gastric dysrhythmia, including tachygastria, which was determined by electrogastrography (EGG), were observed during optokinetic motion sickness in healthy Japanese volunteers. Twelve volunteers (9 men and 3 women) participated in the study. The subjects were asked to sit in a chair with their heads positioned in the center of a drum whose inside had been painted with black and white stripes. After a 15 min resting period, the drum was rotated at a speed of 60 degree/sec for 15 min. The EGG was continuously recorded for a total of 45 min (15 min resting period, 15 min rotation period, and 15 min recovery period). The severity of nausea was evaluated with a visual analogue scale (VAS) before, immediately after, and 15 min after the cessation of drum rotation. Other motion sickness symptoms were evaluated by scores of subjective symptoms of motion sickness (SSMS). Of 12 subjects who completed the study, 10 complained of nausea immediately after cessation of drum rotation. The VAS score for nausea immediately after the drum rotation period and 15 min after cessation of the rotation was significantly higher than during the resting period. The EGG during the drum rotation period showed a decrease in normogastria, which was accompanied with an increase in tachygastria. We conclude that gastric tachyarrhythmia and nausea may be induced by viewing an optokinetic rotating drum in healthy Japanese subjects who may have a hypersusceptibility to vection-induced motion sickness. The gastric dysrhythmia obtained with EGG could be a useful observation to support the appearance of nausea induced by optokinetic motion sickness.

Pre- and postoperative electrogastrography in patients with gastric cancer.

BACKGROUND/AIMS: To investigate the changes of electrogastrography (EGG) after stomach resection, fasting and postprandial EGG were recorded in 10 volunteers and 23 gastric cancer patients who had undergone total or subtotal gastrectomy. METHODOLOGY: EGG signals in patients were recorded before and after surgery and were analyzed by power spectrum. RESULTS: The power spectrum components at three cycles/minute (cpm) as normal subject, had completely disappeared in all patients after total gastrectomy, and irregular powers, especially under 9 cpm, had increased. These results suggest that the activity of the 3-cpm component is specific for the stomach. In subtotal gastrectomy patients, 3-cpm power peaks were clearly observed in seven of twelve patients, but it was not recorded in the remaining five patients, who showed irregular powers similar to that in patients after total gastrectomy. Therefore, it was speculated that the area containing the "pacemaker" of gastric electric potentials was removed during gastrectomy in these five patients. The postprandial dip, which is considered to reflect autonomic nervous function, was not observed in six of seven subtotal gastrectomy patients who demonstrated the 3-cpm component in their EGG, and it was speculated that the gastric branch of the vagus nerve in these six patients might have been partially removed by surgery. CONCLUSIONS: These findings suggest that EGG is available as a non-invasive method to evaluate the motility and autonomic function of the remnant stomach after gastrectomy.

Corticotropin-releasing factor and interleukin-1beta are involved in the electroacupuncture-induced analgesic effect on inflammatory pain elicited by carrageenan.

Electroacupuncture (EA) is used to relieve various kinds of pain. However, the mechanistic basis of electroacupuncture analgesia (EAA) in inflammatory pain remains unclear. In the present study, we investigated whether endogenous peripheral corticotropin-releasing factor (CRF) or interleukin-1beta (IL-1) participated in EAA during hyperalgesia elicited by carrageenan-induced inflammation. Carrageenan was subcutaneously administered by intraplantar (i.pl.) injection of the left hind paw to induce inflammation. Nociceptive thresholds were measured using the paw pressure threshold (PPT) (Randall Sellito Test). Rats received 3 Hz EA in the left anterior tibial muscles for 1 hour after carrageenan injection. The selective CRF antagonist, alpha-helical CRF, or the recombinant IL-1 receptor antagonist, IL-1ra, was administered by i.pl. injection of the inflamed paw or by intravenous (i.v.) injection 1 hour before EA. PPT decreased significantly 3 hours after carrageenan injection. This decrease persisted at least 24 hours after carrageenan injection. EA resulted in significant increases of PPT, moreover, PPT elevations lasted 24 hours after carrageenan injection. By contrast, PPT elevations produced by EA were dose-dependently antagonized by local i.pl. injection of alpha-helical CRF or IL-1ra. This PPT elevation was not influenced by i.v. injection of alpha-helical CRF or IL-1ra. These findings suggest that peripheral CRF or IL-1 participate in EAA during hyperalgesia. The release of CRF or IL-1 elicited by EA may trigger the release of opioid peptides within inflamed tissue which may activate peripheral opioid receptors and inhibit the pain.

Differences of electroacupuncture-induced analgesic effect in normal and inflammatory conditions in rats.

It has been reported by Stein et al. that the immune system and peripheral opioid receptors are involved in the control of pain accompanying inflammation. Electroacupuncture (EA) is used to relieve various kinds of pain. However, little is known about the effect of electroacupuncture analgesia (EAA) during hyperalgesia elicited by inflammation. The aim of the present study was to compare (1) the individual variation of EAA, (2) the durability of EAA, and (3) the effect of naloxone on EAA between normal rats and rats subjected to acute inflammatory pain. Carrageenan was subcutaneously administered by intraplantar (i.pl.) injection of the left hind paw to induce a nociceptive response. Nociceptive thresholds were measured using the paw pressure threshold (PPT). Rats received EA at 3 Hz in the left anterior tibial muscles for 1 hour after carrageenan injection. Naloxone was administered by intraperitoneal (i.p.) or i.pl. injection just before EA. EAA was elicited in 15 of 29 normal rats. These rats were divided into responders and non-responders. EAA in the responder group was almost completely antagonized by i.p. injection of naloxone. In contrast, in all the rats with carrageenan-induced inflammation, EAA was elicited, lasted for at least 24 hours after carrageenan injection, and was dose-dependently antagonized by i.pl. injection, but not significantly by i.p. injection of naloxone. It seems likely that the EAA in the rats with carrageenan-induced inflammation differs from that in normal rats, and these findings suggest that peripheral opioid receptors are involved in EAA during inflammatory conditions.

Analgesic effects induced by TENS and electroacupuncture with different types of stimulating electrodes on deep tissues in human subjects.

Effects of conditioning peripheral nerve stimulation with different types of stimulating electrodes on pain thresholds in various deep tissues were measured in human subjects. Cone-shaped metal (phi 13 mm), rubber (phi 13 mm), and large soft surface electrodes (50 x 150 mm) were used for transcutaneous electrical nerve stimulation (TENS), and insulated and non-insulated acupuncture needles (diameter: 240 microns) were used for electroacupuncture (EA). Two pairs of electrodes were placed around the point of deep pain measurement. Symmetrical positive and negative square pulses (0.1 msec at 100 Hz) of just below the pain tolerance intensity were used for both TENS and EA. Deep pain thresholds were measured at the center of the thigh with a pulse algometer and insulated needle electrodes. Pain thresholds of deep tissues were in the order periosteum < fascia < skin (including subcutaneous tissues) < muscle. TENS with surface electrodes significantly increased pain thresholds of skin and fascia but not those of muscle or periosteum. The shape, material and size of the surface electrodes hardly affected the degree of analgesic effect, except in the fascia by large soft electrodes. In contrast, EA with non-insulated needles induced a greater increase in pain threshold in skin, fascia and muscle, although statistically significant results were obtained in only the first two tissues. EA with insulated needle electrodes was the only technique with which we obtained a significant increase in pain threshold in muscle and periosteum. These results suggest that the choice of electrode and stimulus parameters is important for the production of sufficient analgesic effects in different somatic tissues and that insulated needle electrodes are useful for pain relief in deeper tissues such as muscle and periosteum.