The Post-Polyketide Synthase Modification Mechanism in Hitachimycin Biosynthesis.

Hitachimycin is a bicyclic macrolactam antibiotic with (S)-ß-phenylalanine (ß-Phe) at the starter position of the polyketide skeleton. While the enzymes that recognize ß-amino acids, modify the aminoacyl groups, and transfer the resultant dipeptide groups to the acyl carrier protein domains of polyketide synthases (PKSs) have been studied extensively, the post-PKS modification mechanism responsible for constructing the unique bicyclic structure of hitachimycin remains elusive. In this study, we first inactivated six genes encoding putative post-PKS modification enzymes, namely hitM1 to hitM6, in Streptomyces scabrisporus to determine their involvement in hitachimycin biosynthesis. The ΔhitM4 strain accumulated an all-trans-2,4,6,8,18-pentaene macrolactam, which was confirmed as a true intermediate in hitachimycin biosynthesis by cellular feeding experiments, and appears to be the initial intermediate in the post-PKS modification pathway. The ΔhitM1 strain accumulated 10-O-demethyl-10-oxohitachimycin (M1-A). In enzymatic experiments, M1-A was reduced by the NAD(P)H-dependent reductase HitM1 in the presence of NADPH. The product of the reaction catalyzed by HitM1 was converted to hitachimycin by the methyltransferase HitM6. We thus propose a plausible post-PKS modification mechanism for the biosynthesis of hitachimycin.

Caffeine intoxication as a result of excessive consumption of bottled coffee products: a case report.

Objectives: Most cases of caffeine intoxication result from the excessive intake of over-the-counter drugs and energy drinks. However, few cases of caffeine intoxication due to the excessive consumption of bottled coffee products have been reported. Herein, we present a case report of caffeine intoxication. Patient: A 39-year-old man experienced numbness and weakness in the extremities for three nights over five days. Results: Blood tests revealed hypophosphatemia and low 25-OH vitamin D concentration. The symptoms disappeared the next day without any additional treatment. A lifestyle interview revealed that he regularly consumed bottled coffee like it was water and had approximately 1 L of it from evening to night. He was diagnosed with weakness in the extremities due to hypophosphatemia caused by caffeine intoxication. Upon investigating some bottled coffee products, we found that only a few of them had labels disclosing caffeine content and warnings of the risks of excessive caffeine intake. Conclusion: We encountered a case of caffeine intoxication via coffee. Although rare in the past, caffeine intoxication might increase owing to the widespread use of bottled coffee products. The caffeine content of coffee products should be indicated on labels to warn consumers.

Biased reorientation in the chemotaxis of peritrichous bacteria Salmonella enterica serovar Typhimurium.

Many kinds of peritrichous bacteria that repeat runs and tumbles by using multiple flagella exhibit chemotaxis by sensing a difference in the concentration of the attractant or repellent between two adjacent time points. If a cell senses that the concentration of an attractant has increased, their flagellar motors decrease the switching frequency from counterclockwise to clockwise direction of rotation, which causes a longer run in swimming up the concentration gradient than swimming down. We investigated the turn angle in tumbles of peritrichous bacteria swimming across the concentration gradient of a chemoattractant because the change in the switching frequency in the rotational direction may affect the way tumbles. We tracked several hundreds of runs and tumbles of single cells of Salmonella enterica serovar Typhimurium in the concentration gradient of L-serine and found that the turn angle depends on the concentration gradient that the cell senses just before the tumble. The turn angle is biased toward a smaller value when the cells swim up the concentration gradient, whereas the distribution of the angle is almost uniform (random direction) when the cells swim down the gradient. The effect of the observed bias in the turn angle on the degree of chemotaxis was investigated by random walk simulation. In the concentration field where attractants diffuse concentrically from the point source, we found that this angular distribution clearly affects the reduction of the mean-square displacement of the cell that has started at the attractant source, that is, the bias in the turn angle distribution contributes to chemotaxis in peritrichous bacteria.

Anti-obesity activity of hen egg anti-lipase immunoglobulin yolk, a novel pancreatic lipase inhibitor.

BACKGROUND: There is completely no report about both hen egg anti-lipase immunoglobulin yolk (IgY) and its anti-obesity action. Thus, we tried to isolate and characterize a novel anti-lipase immunoglobulin from hen egg yolk. Moreover, we investigated whether hen egg yolk anti-lipase IgY inhibits pancreatic lipase activity in vitro, and examined its ability to prevent obesity in a murine high fat diet-induced obesity model. METHODS: We determined the inhibitory action of Anti-lipase IgY on lipase activity in vitro. We also focused our evaluation on the anti-obesity properties of Anti-lipase IgY in a murine high fat diet-induced obesity model. RESULTS: Anti-lipase IgY blocked porcine lipase activity with an IC50 of 0.49 µM. Supplementing the high fat diet with only 0.2% (w/w) of Anti-lipase IgY for 35 days significantly decreased the weights of intraperitoneal adipose tissues, epididymal, mesenteric, retroperitoneal and perirenal adipose tissues, and the amounts of hepatic total lipid, triglyceride, and cholesterol. This was accompanied by a significant increase in the fecal excretion of triglyceride in the absence of diarrhea. Furthermore, Anti-lipase IgY treatment restored body weight gain to levels similar to mice fed with Control IgY. CONCLUSIONS: This study provides the first report of the development of anti-lipase IgY and the direct evidence that inhibition of pancreatic lipase using Anti-lipase IgY is an effective anti-obesity treatment due to the associated increase in fecal excretion of triglyceride.

[Anesthetic management in two infants undergoing hemilaminectomy for giant mediastinal neuroblastoma].

We report the anesthetic management in two infants who were a three-month-old boy (case 1) and a two- month-old girl (case 2), undergoing hemilaminectomy for giant mediastinal neuroblastoma. Neuroblastoma invades into the intrathecal space in a rare occasion, resulting in paraplegia, which requires emergent operation to save the spinal cord. Mediastinal neuroblastoma also possesses significant respiratory and cardiovascular risks due to the close anatomic relationship with vital organs. In the present report, we show that preoperative computed tomography (CT) scan and/or echocardiography revealed tracheal deviation in case 1 and mass compression of the left atrium in case 2. Therefore, the patients with mediastinal masses should be carefully evaluated before subjecting them to anesthesia. Especially, there is a possibility that the masses which do not appear to compress the airway and cardiovascular systems develop the airway obstruction and cardiovascular collapse after induction of general anesthesia. In fact, before induction of general anesthesia in the case 2, trial of the prone positioning which was scheduled for the hemilaminectomy, resulted in bradycardia and hypotension, presumably due to the compression of the left atrium. In summary, the authors here discussed the preoperative evaluation and anesthetic management for giant mediastinal neuroblastoma in infants.

[Pulmonary artery obstruction in a pediatric patient during removal of a right ventricular myxoma].

Cardiac myxoma, especially right ventricular myxoma is very rare. We report a 2-year-old girl who underwent the emergent surgical resection of a right ventricular myxoma. She was noticed to have systolic murmur and was referred to our hospital. Echocardiography and magnetic resonance imaging (MRI) revealed the presence of tumor extending from the right ventricle across the pulmonic valve into the pulmonary artery. Anesthesia for the removal of a right ventricular myxoma should be carried out carefully, because pulmonary tract obstruction may occur during the procedure. During the removal of the tumor, the tumor obstructed the pulmonary artery resulting in severe decrease of the blood pressure and the heart rate. Because pulmonary artery occulusion occurred after pericardiotomy, chest massage was started quickly and in 15 minutes cardiopulmonary bypass was established. The tumor was removed completely and was diagnosed as myxoma by histological examination. The patient recovered uneventfully and was discharged without complications.