A stopped-flow study of the reaction of cytochrome c peroxidase with hydroperoxides

AbstractTransient kinetic measurements show that cytochrome c peroxidase reacts with excess of hydroperoxides to produce compound ES in two phases. The activation energies for the fast and slow phases are calculated to be 6.3 and 20.5 kcal·mol−1, respectively. The fast phase is assigned to the reaction of native active (pulsed) cytochrome c peroxidase with peroxides, whereas the slow phase is due to the presence of an inactive (aged, resting) enzyme. As the active species is exhausted, the equilibrium between the active and inactive enzymes is shifted by a slow conformational change to replenish the active enzyme. Since the rate-limiting step of the reaction of the inactive enzyme with peroxides is the conformation change, the overall reaction rate is independent of the nature and concentration of peroxides

Effect of hospitalization on fetal growth

Objective : We aimed to demonstrate the effect of prolonged hospitalization on fetal growth in cases of threatened preterm labor (TPL). Methods : In this retrospective cohort study, we included women who received prenatal care for TPL but delivered their child after 36 weeks of gestation. These were compared with a control group of healthy pregnant women and fetuses delivered at term. Fetal growth was compared using biparietal diameter, abdominal circumference (AC), femur length, and estimated fetal weight (EFW) assessed using ultrasonography at 18, 26, 30, and 36 weeks of gestation. Neonatal parameters at birth were also compared. Results : In total, we enrolled 228 control women and 114 women with TPL who were treated with hospitalization, including bed rest. The AC at 30 and 36 weeks of gestation and EFW at 36 weeks of gestation were smaller in women treated with bed rest than for normal pregnant women. The mean duration of pregnancy was shorter in the hospitalization group than in the control group. Neonatal weight, length, head circumference, and chest circumference at birth were smaller after prolonged hospitalization for TPL than after normal pregnancy. Conclusion : Prolonged hospitalization for threatened preterm labor is associated with impaired fetal growth, particularly AC

monochorionic dizygotic twin with some blood chimerism

We report a very rare case of monochorionic dizygotic twins conceived spontaneously. The fetuses were sex-discordant in ultrasonography in spite of monochorionic twins. After birth, the girl and boy showed normal phenotypes but they showed blood chimerism in karyotype and blood group type

Vitamin D during pregnancy in Japanese

We aimed to demonstrate that the serum 25-hydroxyvitamin D (25(OH)D) level in maternal and umbilical cord blood has a seasonal variation in Japanese women. The study cohort comprised 256 healthy Japanese women with a singleton pregnancy who delivered after 36 gestational weeks between 2012 and 2015. The season at delivery was categorized for 3 months and recorded as “spring”, “summer”, “autumn” and “winter”. Subjects were divided into four groups according to season. A sample of peripheral venous blood at 35-36 gestational weeks and blood from the umbilical vein at delivery were taken. The mean serum 25(OH)D concentration (ng/mL) in maternal blood for each season (spring, summer, autumn and winter) was 18.0 (±6.7), 17.1 (±5.1), 21.6 (±8.0) and 16.0 (±5.1), whereas that for umbilical cord blood was 8.8 (±3.6), 8.6 (±2.6), 10.7 (±3.5) and 8.6 (±2.1), respectively. The mean serum 25(OH)D concentration of maternal and umbilical cord blood in autumn was higher than that for the other three seasons. In pregnant Japanese women, the mean serum 25(OH)D concentration in maternal and umbilical cord blood was affected by the season of delivery, with both being highest in autumn. Regardless of the season, the maternal serum concentration of 25(OH)D was low in Japan

Semihemoglobins, High Oxygen Affinity Dimeric Forms of Human Hemoglobin Respond Efficiently to Allosteric Effectors without Forming Tetramers

Significant reduction in oxygen affinity resulting from interactions between heterotropic allosteric effectors and hemoglobin in not only the unligated derivative but also the fully ligated form has been reported (Tsuneshige, A., Park, S. I., and Yonetani, T. (2002) Biophys. Chem. 98, 49-63; Yonetani, T., Park, S. I., Tsuneshige, A., Imai, K., and Kanaori, K. (2002) J. Biol. Chem. 277, 34508-34520). To further investigate this effect in more detail, alpha- and beta-semihemoglobins, namely, alpha(heme)beta(apo) and alpha(apo)beta(heme), respectively, were prepared and characterized with respect to the impact of allosteric effectors on both conformation and ligand binding properties. Semihemoglobins are dimers characterized by a high affinity for oxygen and lack of cooperativity. We found that, compared with stripped conditions, semihemoglobins responded to effectors (inositol hexaphosphate and L35) by decreasing the affinity for oxygen by 60- and 130-fold for alpha- and beta-semihemoglobins, respectively. 1H NMR and sedimentation velocity experiments carried out with their ligated and unligated forms in the absence and presence of effectors revealed that semihemoglobins always remain as single-heme-carrying dimers. Recombination kinetics of their photolyzed CO derivatives showed that effectors did indeed interact with their ligated forms. Measurements of the Fe-His stretching mode show that the semihemoglobins undergo a large ligand binding-induced conformational shift and that both ligand-free and ligand derivatives respond to the presence of effectors. Contradictions to the Monod-Wyman-Changeaux/Perutz allosteric model arise since 1) the modulation of ligand affinity is not achieved in semihemoglobins by the formation of a low affinity T conformation (quaternary effect) but by direct interaction with effectors, 2) effectors do interact significantly with ligated forms of high affinity semihemoglobins, and 3) modulation of the ligand affinity and the cooperativity are not necessarily linked but instead can be separated into two distinct phenomena that can be isolated

Electrical cardiometry for hemodynamics

Few reports have focused on hemodynamics around delivery in pregnant women because of the difficulty of continuous and noninvasive measurement. Electrical cardiometry allows noninvasive continuous monitoring of hemodynamics and has recently been used in non-pregnant subjects. We compared the use of electrical cardiometry versus transthoracic echocardiography in healthy pregnant women and evaluated hemodynamics immediately after vaginal delivery. In Study 1, electrical cardiometry and transthoracic echocardiography were used to measure cardiac output in 20 pregnant women with threatened premature delivery. A significant correlation was found between the two methods, with electrical cardiometry showing the higher cardiac output. In Study 2, heart rate, stroke volume, and cardiac output were continuously measured in 15 women during vaginal delivery up to 2 h postpartum. Cardiac output increased markedly because of an increased heart rate and stroke volume at the time of newborn delivery. The heart rate then immediately returned to baseline, while cardiac output remained elevated for at least 2 h after delivery because of a sustained high stroke volume. Electrical cardiometry was as readily available as transthoracic echocardiography for evaluating hemodynamics and allowed for continuous measurement during labor. High intrapartum cardiac output was sustained for at least 2 h after vaginal delivery

Maternal hospitalization and vitamin D

Aim: We aimed to evaluate the effect of prolonged hospitalization for threatened preterm labor on maternal and fetal vitamin D status. Methods: This was a retrospective cohort study, spanning 4 years, including 18 women with threatened preterm labor and 36 women with normal pregnancy, who received prenatal care for a singleton pregnancy at our center. Threatened preterm labor cases were women who were admitted to our hospital after the second trimester test, for at least 28 days, during which, the third trimester test was also performed. Controls were randomly sampled from women matched for age as well as the season during which the third trimester test was performed. Serum 25-hydroxyvitamin D concentration in maternal blood was compared between the two groups at second trimester, third trimester and in the umbilical cord blood at delivery. Results: The mean±SD of maternal serum 25-hydroxyvitamin D concentration in the threatened preterm labor group (14.0±3.0 ng/mL) was significantly lower than that in the control group (17.8±5.9 ng/mL) (p<0.01) in the third trimester, although there was no significant difference in the second trimester (p=0.30). There was a significant reduction (p<0.01) in the maternal serum 25-hydroxyvitamin D from the second to third trimester,in the threatened preterm labor group, compared to the control group (p=0.60). There was no significant difference between the two groups in umbilical cord blood 25-hydroxyvitamin D concentrations at delivery (p=0.41). Conclusions: Prolonged hospitalization for threatened preterm labor reduced the maternal vitamin D status, but did not influence the neonatal status at delivery

Ultrasonographic changes in quadriceps femoris thickness in women with normal pregnancy and women on bed rest for threatened preterm labor

This study aimed to evaluate the changes in quadriceps femoris muscle thickness during the pregnancy and postpartum periods and to elucidate the effect of bed rest for threatened preterm labor on muscle thickness. In 26 women with normal pregnancy, quadriceps femoris thickness was measured at 11–13, 26, 30, and 35 weeks’ gestation, and at 3–5 days and 1 month postpartum using ultrasonography. In 15 pregnant women treated with bed rest for threatened premature labor, quadriceps femoris thickness was measured at 30 and 35 weeks’ gestation and postpartum. In women with normal pregnancy, quadriceps femoris thickness increased, peaking at 35 weeks’ gestation, followed by a postpartum decrease. In women on bed rest, quadriceps femoris thickness showed no significant change during the pregnancy and postpartum periods, and the muscle was significantly thinner at 35 weeks’ gestation than that in women with normal pregnancy. In conclusion, a significant increase in quadriceps femoris muscle thickness during normal pregnancy was found using ultrasonography. Meanwhile, in pregnant women on bed rest treatment, the quadriceps femoris was significantly thinner in the late third trimester than that in normal pregnant women. Prolonged bed rest can affect normal changes in the quadriceps femoris muscle thickness during the pregnancy and postpartum periods

A method for the preparation of heavy-atom derivatives of yeast cytochrome c peroxidase

This Letter describes a strategy for preparation of heavy-atom derivatives which has succeeded with yeast cytochrome c peroxidase and which may be useful for other crystalline proteins. Transfer of the crystals from methylpentanediol solutions, in which they were grown, to solutions of polyethylene glycol (Mr 6000) maintains the crystal structure so that crystals tolerate heavy-atom concentrations at least ten times larger than could be attained in methylpentanediol mother liquors.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23653/1/0000619.pd