The first synthesis and antifungal activities of 9-methoxystrobilurin-type beta-substituted beta-methoxyacrylate

The first synthesis of 9-methoxystrobilurin-type beta-substituted MOAs was successfully achieved. A chiral oudemansin-type beta-substituted MOA was also synthesized utilizing Mukaiyama's asymmetric aldol reaction. Antifungal activities of the synthesized compounds against several representative fungi were examined by disk-diffusion assay. As a result, unique and superior antifungal properties of 9-methoxystrobilurin-type beta-substituted MOAs compared with those of oudemansin-type analogue were clearly revealed.     

Complete deoxygenation from a hemoglobin solution by an electrochemical method and heat treatment for virus inactivation

Hemoglobin (Hb) has been widely studied as a raw material for various types of oxygen carriers. In the purification of Hb from red blood cells including virus inactivation and denaturation of other proteins and the long-term storage of Hb vesicles (HbV), a deoxygenation process is one of the important processes because of the high stability of deoxygenated Hb to heating and metHb formation. Though an oxygenated Hb solution can be deoxygenated with an artificial lung, it is difficult to reduce the oxygen partial pressure of the Hb solution to less than 10 Torr. We developed an electrochemical system for complete deoxygenation of the Hb solution at the cathode compartment using hydrogen containing nitrogen gas at the anode compartment. Oxygen in the Hb solution was reduced to OH(-) at the cathode compartment within several minutes at a potential value of -1.67 V and was finally converted to water by neutralization with H(+) from the anode in the whole system. The resulting completely deoxygenated Hb could tolerate heat treatment at 62 degrees C for 10 h with no denaturation of deoxygenated Hb. The metHb formation rate of reoxygenated Hb at 37 degrees C was not changed after heat treatment. Furthermore, vesicular stomatitis virus (VSV) could be inactivated at an inactivation degree of more than 5.96 log by heat treatment.     

Methacholine-induced cGMP production is regulated by nitric oxide generation in rabbit submandibular gland cells

Guanosine 3′,5′-monophosphate (cGMP) is an intracellular messenger in various kinds of cell. We investigated the regulation of cGMP production by nitric oxide (NO) in rabbit submandibular gland cells. Methacholine, a muscarinic cholinergic agonist, stimulated cGMP production in a dose- and time-dependent manner, but the α-agonist phenylephrine, substance P and the β-agonist isoproterenol failed to evoke cGMP production. In fura-2-loaded cells, methacholine induced an increase in intracellular Ca²⁺ ([Ca²⁺]_i) in a concentration-dependent manner, which was similar to that for cGMP production. When the external Ca²⁺ was chelated with EGTA, methacholine failed to induce cGMP production. Ca²⁺ ionophore A23187 and thapsigargin, which induce the increase in [Ca²⁺]_i without activation of Ca²⁺-mobilizing receptors, mimicked the effect of methacholine. cGMP production induced by methacholine, A23187 and thapsigargin was clearly inhibited by N^G-nitro- -arginine methylester (L-NAME), a specific inhibitor of nitric oxide synthase (NOS). S-Nitroso-N-acetyl- -penicillamine (SNAP), a NO donor, induced cGMP formation. In the lysate of rabbit submandibular gland cells, Ca²⁺-regulated nitric oxide synthase activity was detected. These findings suggest that cGMP production induced by the activation of muscarinic cholinergic receptors is regulated by NO generation via the increase in [Ca²⁺]_i.     

Effect of postprandial posture on digestion and absorption of dietary carbohydrate

The effect of postprandial body posture on digestion and absorption of dietary carbohydrate were examined through breath hydrogen test on 6 female subjects. During the experiment, the participants either sat on a chair or lay on their backs for the first 4 hr (from 08:00 to 12:00) after eating the test breakfast meal. They then remained sedentary on a sofa for 6 hr (12:00 to 18:00). Participants' end alveolar breath samples were collected for 10 hr (every 15 min from 08:00 to 12:30, and then every 30 min until 18:00). The experiment was conducted on two consecutive days using a randomized, crossover study design. The results demonstrated that in the supine position orocecal transit time of the test meal was significantly slower than in the sitting position (260 +/- 21 min and 238 +/- 20 min, respectively, p < 0.01). In addition, afternoon breath hydrogen excretion due to a partial malabsorption of dietary carbohydrate and its fermentation in the colon was significantly larger in the sitting position (144.0 +/- 24.1 ppm.hr) than in the supine position (110.0 +/- 26.1 ppm.hr, p < 0.05). These results support the hypothesis that there was a marked effect of postprandial body posture on the function of the digestive system. The present findings suggest that the postprandial supine position is preferable to the sitting position for the digestion and absorption of dietary carbohydrate.     

Observations on normal body temperatures in Vietnamese and Japanese in Vietnam

The observations described in this paper were made during a study of the effects of tropical climate upon Vietnamese and Japanese. We measured rectal and skin temperatures every 10 min for 26 hrs in 6 Vietnamese and 6 Japanese. The experiments have been conducted for 2 hot months, June and July 1999 and 2000 in Hanoi, Vietnam. The ambient temperatures ranged from 33 to 36 degrees C. The results obtained are summarized as follows: 1) Skin temperatures at thigh, forearm and hand during the daytime were significantly higher in the Vietnamese subjects than in the Japanese ones. It would be physiological reactions to warm ambient temperatures, which is advantageous for dissipation of body heat. 2) The average rectal temperature during the daytime is significantly higher in the Vietnamese than in the Japanese, while significantly lower at night. 3) Average range of oscillation of rectal temperature was 1.26 degrees C in the Vietnamese, which was clearly greater than in the Japanese. The higher core temperature, which was actively regulated under warm temperature, seemed of adaptive significance, resulting in the reduction of water consumption like camels in the desert. A greater range of oscillation in tropical Vietnamese people might have ecological significance for efficient acclimatization in the warm environment, suggesting that the setpoint of core temperature could show a greater range of oscillation.     

A novel species of alkaliphilic Bacillus that produces an oxidatively stable alkaline serine protease

A novel gram-positive, strictly aerobic, motile, sporulating, and facultatively alkaliphilic bacterium designated KSM-KP43 was isolated from a sample of soil. The results of 16S rRNA sequence analysis placed this bacterium in a cluster with Bacillus halmapalus. However, the level of the DNA-DNA hybridization of KSM-KP43 with B. halmapalus was less than 25%. Moreover, the G + C contents of the genomic DNA were 41.6 mol% for KSM-KP43 and 38.6 mol% for B. halmapalus. Because there were also differences in physiological properties and cellular fatty acid composition between the two organisms, we propose KSM-KP43 as a novel species of alkaliphilic Bacillus. This novel strain produces a new class of protease, an oxidatively stable serine protease that is suitable for use in bleach-based detergents. The enzyme contained 640 amino acid residues, including a possible approximately 200-amino-acid prepropeptide in the N-terminal and a unique stretch of approximately 160 amino acids in the C-terminal regions (434-amino-acid mature enzyme with a calculated molecular mass of 45,301 Da). The C-terminal half after the putative catalytic Ser255 and the contiguous C-terminal extension shared local similarity to internal segments of a membrane-associated serine protease of a marine microbial assemblage and the serine protease/ABC transporter precursors of the slime mold Dictyostelium discoideum, and to the C-terminal half of a cold-active alkaline serine protease of a psychrotrophic Shewanella strain.     

Analysis of membrane stereochemistry with homology modeling of sn-glycerol-1-phosphate dehydrogenase

Different enantiomeric isomers, sn-glycerol-1-phosphate and sn-glycerol-3-phosphate, are used as the glycerophosphate backbones of phospholipids in the cellular membranes of Archaea and the remaining two kingdoms, respectively. In Archaea, sn-glycerol-1-phosphate dehydrogenase is involved in the generation of sn-glycerol-1-phosphate, while sn-glycerol-3-phosphate dehydrogenase synthesizes the enantiomer in Eukarya and Bacteria. The coordinates of sn-glycerol-3-phosphate dehydrogenase are available, although neither the tertiary structure nor the reaction mechanism of sn-glycerol-1-phosphate dehydrogenase is known. Database searching revealed that the archaeal enzyme shows sequence similarity to glycerol dehydrogenase, dehydroquinate synthase and alcohol dehydrogenase IV. The glycerol dehydrogenase, with coordinates that are available today, is closely related to the archaeal enzyme. Using the structure of glycerol dehydrogenase as the template, we built a model structure of the Methanothermobacter thermautotrophicus sn-glycerol-1-phosphate dehydrogenase, which could explain the chirality of the product. Based on the model structure, we determined the following: (1) the enzyme requires a Zn(2+) ion for its activity; (2) the enzyme selectively uses the pro-R hydrogen of the NAD(P)H; (3) the putative active site and the reaction mechanism were predicted; and (4) the archaeal enzyme does not share its evolutionary origin with sn-glycerol-3-phosphate dehydrogenase.     

Effect of metformin on adipose tissue resistin expression in db/db mice

Resistin, a novel adipose-derived protein, has been proposed to cause insulin-resistant states in obesity. To evaluate whether an insulin-sensitizing drug, metformin, regulates adipose tissue resistin expression, murine models of obesity and diabetes, db/db mice, were treated with metformin (metformin group), insulin (insulin group), and vehicle (control group) for 4 weeks, followed by analyzing resistin protein expression in their adipose tissues. Unexpectedly, resistin protein expression was increased by 66% in the metformin group relative to the control group, while it did not differ between the insulin and control groups. Hyperinsulinemia was improved in the metformin group, while the insulin group exhibited severe hyperinsulinemia, similar to the control group. Furthermore, in comparison between obese mice (db/db mice) and age-matched lean controls, resistin protein expression was reduced by 58% in the obese mice with severe hyperinsulinemia. These data collectively suggest that resistin expression may be suppressed by hyperinsulinemia and that metformin may upregulate resistin expression via the improvement of hyperinsulinemia in obesity.     

Interaction of plexin-B1 with PDZ domain-containing Rho guanine nucleotide exchange factors

The Rho family GTPase has been implicated in plexin-B1, a receptor for Semaphorin 4D (Sema4D), mediating signal transduction. Rho may also play a function in this signaling pathway as well as Rac, but the mechanisms for Rho regulation are poorly understood. In this study, we have identified two kinds of PDZ domain-containing Rho-specific guanine nucleotide exchange factors (RhoGEFs) as proteins interacting with plexin-B1 cytoplasmic domain. These PDZ domain-containing RhoGEFs showed significant homology to human KIAA0380 (PDZ-RhoGEF) and LARG (KIAA0382), respectively. Both KIAA0380 and LARG could bind plexin-B1 and a deletion mutant analysis of plexin-B1, KIAA0380 and LARG revealed that KIAA0380 and LARG bound plexin-B1 cytoplasmic tail through their PDZ domains. The tissue distribution analysis indicated that plexin-B1 was co-localized with KIAA0380 and LARG in various tissues. Immunocytochemical analysis showed that LARG was recruited to plasma membrane by plexin-B1. These results suggest that PDZ domain-containing RhoGEFs play a role in Sema4D-plexin-B1 mediating signal transduction.     

Fe(2+)-catalyzed oxidation and cleavage of sarcoplasmic reticulum ATPase reveals Mg(2+) and Mg(2+)-ATP sites

Fe(2+) can substitute for Mg(2+) in activation of the sarcoplasmic reticulum (SR) ATPase, permitting approximately 25% activity in the presence of Ca(2+). Therefore, we used Fe(2+) to obtain information on the binding sites for Mg(2+) and the Mg(2+)-ATP complex within the enzyme structure. When the ATPase is incubated with Fe(2+) in the presence of H(2)O(2) and/or ascorbate, specific patterns of Fe(2+)-catalyzed oxidation and cleavage are observed in the SR ATPase, depending on its Ca(2+)-bound (E1-Ca(2)) or Ca(2+)-free conformation (E2-TG), as well as on the presence of ATP. The ATPase protein in the E1-Ca(2) state is cleaved efficiently by Fe(2+) with H(2)O(2) and ascorbate assistance, yielding a 70-75 kDa carboxyl end fragment. Cleavage of the ATPase protein in the E2-TG state occurs within the same region, but with a more diffuse pattern, yielding multiple fragments within the 65-85 kDa range. When Fe(2+) catalysis is assisted by ascorbate only (in the absence of H(2)O(2)), cleavage at the same protein site occurs much more slowly, and is facilitated by ATP (or AMP-PNP) and Ca(2+). Amino acid sequencing indicates that protein cleavage occurs at and near Ser346, and is attributed to Fe(2+) bound to a primary Mg(2+) site near Ser346 and neighboring Glu696. In addition, incubation with Fe(2+) and ascorbate produces Ca(2+)- and ATP-dependent oxidation of the Thr441 side chain, as demonstrated by NaB(3)H(4) incorporation and analysis of fragments obtained by extensive trypsin digestion. This oxidation is attributed to bound Fe(2+)-ATP complex, as shown by structural modeling of the Mg(2+)-ATP complex at the substrate site.