Benzodiazepines inhibit the acetylcholine receptor-operated potassium current (IK.ACh) by different mechanisms in guinea-pig atrial myocytes

The anticholinergic effects of 7 benzodiazepines, bromazepam, camazepam, chlordiazepoxide, diazepam, lorazepam, medazepam and triazolam, were compared by examining their inhibitory effects on the acetylcholine receptor-operated potassium current (I(K).(ACh)) in guinea-pig atrial myocytes. All of these benzodiazepines (0.3-300 μM) inhibited carbachol (1 μM)-induced I(K).(ACh) in a concentration-dependent manner. The ascending order of IC(50) values for carbachol-induced I(K).(ACh) was as follows; medazepam, diazepam, camazepam, triazolam, bromazepam, lorazepam and chlordiazepoxide (>300 μM). The compounds, except for bromazepam, also inhibited I(K).(ACh) activated by an intracellular loading of 100 μM guanosine 5'-[γ-thio]triphosphate (GTPγS) in a concentration-dependent manner. The ascending order of IC(50) values for GTPγS-activated I(K).(ACh) was as follows; medazepam, diazepam, camazepam, lorazepam, triazolam chlordiazepoxide (>300 μM) and bromazepam (>300 μM). To clarify the molecular mechanism of the inhibition, IC(50) ratio, the ratio of IC(50) for GTPγS-activated I(K).(ACh) to carbachol-induced I(K).(ACh), was calculated. The IC(50) ratio for camazepam, diazepam, lorazepam, medazepam and triazolam was close to unity, while it for chlordiazepoxide could not be calculated. These compounds would act on the GTP binding protein and/or potassium channel to achieve the anticholinergic effects in atrial myocytes. In contrast, since the IC(50) ratio for bromazepam is presumably much higher than unity judging from the IC(50) values (104.0 ± 30.0 μM for carbachol-induced I(K).(ACh) and >300 μM for GTPγS-activated I(K).(ACh), it would act on the muscarinic receptor. In summary, benzodiazepines had the anticholinergic effects on atrial myocytes through inhibiting I(K).(ACh) by different molecular mechanisms.     

Histone H4 gene expression and morphological changes on shoot apices of strawberry (Fragaria × ananassa Duch.) during floral induction

To investigate flower induction in June-bearing strawberry plants, morphological changes in shoot apices and Histone H4 expression in the central zone during flower initiation were observed. Strawberry plants were placed under flower inducible, short-day conditions (23 °C/17 °C, 10 h day length) for differing number of days (8, 16, 20, 24 or 32 days) and then these plants were transferred to non-inducible, long-day conditions (25 °C/20 °C, 14 h day length). The shoot apices of plants placed under short-day conditions for 8 days were flat, similar to shoot apices of plants in the vegetative phase of development, and Histone H4 was not expressed in the central zone during the experimental period. On the other hand, the shoot apices of plants placed under short-day conditions for 16 days remained flat, similar to shoot apices of plants placed under short-day conditions for 8 days, but Histone H4 was expressed in the central zone at the end of the short-day treatment. Morphological changes in the shoot apices of these plants were observed 8 days after the change in day-length. These plants developed differentiated flower organs after they were grown for another 30 days under long-day conditions. These results indicate that changes in the expression pattern of the Histone H4 gene occur before morphological changes during flower induction and that the expression of the gene in the central zone can be used as one of the indicators of the flowering process in strawberries.     

Wind tunnel study on aerodynamic characteristics of shrubby specimens of three tree species

With the popularization of green roofing systems, their wind resistant performance is becoming more and more important especially in typhoon areas. A prerequisite study was carried out to determine the aerodynamic characteristics of suitable trees to provide basic scientific data. Shrubby specimens of three tree species appropriate for intensive green roofs with different aerodynamic forms were tested through a boundary layer wind tunnel experiment, including one deciduous tree, one coniferous tree and one broadleaf evergreen tree. Drags and overturning moments under different wind speeds were measured; wind-speed-specific frontal areas and tip displacements were recorded. After initial tests, trees were pruned to investigate the effect of crown porosity, and the effects of view angle and turbulence intensity were also considered. The results showed that even considering frontal area reduction due to increasing wind speeds, drag coefficients decreased with increase in wind speed for deciduous and coniferous trees. Drag coefficient characteristics for different trees agreed well with those obtained from previous researches. The effect of crown porosity varied among tree species, but view angle and turbulence intensity did not significantly affect it.     

Caprine enteritis associated with Yersinia pseudotuberculosis infection

Yersiniosis was prevalent among a caprine herd during the late autumn of 2003 in Iwate Prefecture, Japan. The disease affected 29 of about 100 lactating goats, but not dried or nonparous goats, mature male goats or kids. Four animals died within an epidemic period of 20 days. Affected animals developed decreased milk production with subsequent watery diarrhea, neutrophilia with increased band forms and multiple microabscesses characteristic of yersiniosis in the intestinal mucosa from the jejunum to caecum as well as in the mesenteric lymph nodes. Y. pseudotuberculosis serotype III was isolated from intestinal contents and mesenteric lymph nodes. The organism was also cultured from clinically normal dried animals. The outbreak might have been precipitated by multiple stress factors, such as lactation, cold weather, Corynebacterium pseudotuberculosis infection resulting in abscess formation and tapeworm and coccidium parasitisms.     

Effect of nitrate fertilization of gametophytes of the kelp Undaria pinnatifida on growth and maturation of the sporophytes cultivated in Matsushima Bay, northern Honshu, Japan

In northern Japan, the early production of high-quality specimens of kelps Undaria pinnatifida prior to the outbreak of pinhole disease is needed. To address this need, we tested the effect of nitrate fertilization of gametophytes on the growth and maturation of sporophytes using experimental and control gametophytes derived from sporophytes cultivated in Matsushima Bay, northern Honshu, Japan. From mid-August to October 2008, experimental gametophytes were cultured on a rope indoors at a nitrate concentration of 1 mg/L at the optimal seawater temperature of 20 °C, whereas control gametophytes were cultured without the addition of nitrate in normal seawater at an average temperature of 23.5 °C during this period in the past 30 years. Next, the seedlings were cultivated in Matsushima Bay until March 2009. For the experimental kelps, the total length, stipe length, stipe width, sporophyll length, sporophyll width, and dry weight of the blade, midrib, and sporophyll increased significantly from December to January compared to those of control kelps. Matured sporophylls of the experimental kelps were more than those of the control kelps from early December to late January. Significant higher photosynthesis occurred at seawater temperatures of 10 and 15 °C, as well as higher uptake rates of NO₃–N of the experimental kelps in December and January. These results show that nitrate fertilization of the gametophytes makes it possible to harvest the high-priced blade, midrib, and sporophyll in January, which is earlier than the traditional harvest date.     

Purification and characterization of an angiotensin I‐converting enzyme inhibitory peptide derived from porcine troponin C

To search for a novel angiotensin I‐converting enzyme (ACE) inhibitory peptide, porcine skeletal troponin was hydrolyzed with pepsin. This hydrolysate showed ACE inhibitory activity, and was applied to various kinds of chromatography to separate an active peptide. Analysis using a protein sequencer identified this peptide as RMLGQTPTK (9mer). This sequence was estimated to occur at the 44–52 position of troponin C, and its 50% inhibitory protein concentration (IC₅₀) was 34 µM. RMLGQTP (7mer), a partial peptide of 9mer, showed activity with an IC₅₀ of 503 µM. RP‐HPLC analysis of a reaction mixture of 9mer and ACE showed that 9mer was slowly hydrolyzed by ACE. On the other hand, 7mer was rapidly hydrolyzed by ACE. Activity of 9mer was reduced as its hydrolysis by ACE proceeded. To estimate the resistance of 9mer to digestive proteases after oral administration, it was reacted with pepsin, α‐chymotrypsin, or trypsin. In each of these reaction mixtures, a significant amount of 9mer remained as a substrate after digestion. Remaining ACE inhibitory activity was close to that of 9mer. These results suggest that 9mer might not be digested after oral administration, because of its relatively high resistance to digestive proteases. Therefore, 9mer might be expected to work well in vivo as an ACE inhibitor.     

Changes of serum alkaline phosphatase activity in dry and lactational cows

Serum alkaline phosphatase (ALP) activities were measured during dry and lactational periods to investigate the influence of lactation on serum ALP activity in cows. Higher levels of serum ALP activity were seen in lactational periods than in dry periods. The serum activities of bone-specific ALP (BALP), liver ALP (LALP), tartrate resistant acid phosphatase (TRAP) and aspartate aminotransferase also increased in lactational periods. ALP activities in the bone extract and in whey were decreased at similar rates by the addition of lectin. Moreover, since the ALP band in whey was observed to have the same migration in polyacrylamide gel (PAG) disk electrophoresis as that of the bone extract, analysis of ALP isoenzymes by lectin affinity or PAG disk electrophoresis could not distinguish ALP originating from the mammary gland from that of bone. In this study, it was clear that the increased level of serum ALP activity was due to increases of BALP and LALP in lactational periods. However, the extent of the influence of ALP originating from the mammary glands on serum ALP activity was unknown. Judging from changes of BALP and TRAP activities in the serum and the correlation between the both, it was guessed that ALP originating from the mammary glands influenced serum ALP activity.