Tatsuo Koshino

Assessment of the hepatic arterial and portal venous blood flows during pregnancy with Doppler ultrasonography.

Abstract Purpose: The aim of this study was to evaluate whether the dual hepatic blood supply is altered in healthy pregnant women compared with that in nonpregnant women. Materials and methods: Flow waveforms in common hepatic artery and portal vein were obtained in 67 healthy pregnant women at 10–40 weeks gestation and 22 nonpregnant women by using Doppler ultrasonography. Results: In the nonpregnant group, the mean (SD) hepatic arterial blood flow, portal venous blood flow, and total liver blood flow were 0.57 (0.31) L/min, 1.25 (0.46) L/min, and 1.82 (0.63) L/min, respectively. In the healthy pregnant group, the portal venous blood flow and total liver blood flow significantly increased after 28 weeks gestation. However, the hepatic arterial blood flow remained unchanged during pregnancy. There was no relationship between the hepatic arterial blood flow and the portal venous blood flow. Conclusion: The results demonstrated that the hepatic perfusion increased during third trimester compared to nonpregnant level. Because the hepatic arterial blood flow remained unchanged during pregnancy, major determinant of the increase in the hepatic perfusion was the portal venous return. The data suggest that the hepatic arterial and portal venous vascular territories have regulatory mechanisms that allow for independent changes during pregnancy.

Developmental changes in mitochondrial activity and energy metabolism in fetal and neonatal rat brain

Experiments were undertaken to investigate mitochondrial activity and energy metabolism in the developing rat brain from the late fetal stage to the neonatal stage. Samples of cerebral cortical tissue were obtained from fetuses at 14, 16, 18, and 20 days of gestation, and from pups at 1 h, 1 day and 7 days after birth. Mitochondrial respiration was measured polarographically using homogenates. Fetal and neonatal brains were frozen in situ and fluorometric enzymatic techniques were used for the analysis of ATP, ADP, AMP, and lactate. In the fetal brain, there was a gradual increase in stimulated (+ADP) and uncoupled respiratory rates using glutamate and malate as substrates, from 14 days to 20 days of gestation, together with a moderate increase in ATP concentration and in the sum total of adenine nucleotides, and a significant decrease in lactate. Since non-stimulated (-ADP) respiratory rates did not change with increasing gestational age, the respiratory control ratio appeared to increase over the same period. An increase in mitochondrial activity was more pronounced immediately after birth, together with a marked increase in ATP concentration and in the sum total of adenine nucleotides. The highest rate of mitochondrial respiration was observed in 1-hour-old pups. These results indicate that, in the rat brain, there is maturation of oxidative metabolism in mitochondria that is initiated in late gestation. Acceleration in mitochondrial respiration occurs immediately after birth in order to maintain high-energy phosphate levels, and this may be crucial for the successful outcome of the newborn.

Effect of α-phenyl-N-tert-butyl nitrone (PBN) on fetal cerebral energy metabolism during intrauterine ischemia and reperfusion in rats

The objective of the present study was to explore whether a free radical spin trap agent, α-phenyl-N-tert-butyl nitrone (PBN), influences bioenergetic failure induced in the 20-day-old fetal brain by 30 min of intrauterine ischemia in Wistar rats. Fetal brains were frozen in situ at the end of ischemia and after 1, 2, and 4 h of recirculation for analysis of ATP, ADP, AMP, and lactate. PBN or vehicle was given 1 h after recirculation. Tissue oxygen tension was evaluated in placental and fetal cerebral tissues throughout the whole periods of 30 min of ischemia and 4 h of recirculation. Ischemia was associated with a decrease in ATP concentration and an increase in lactate concentration (p < 0.001). Recirculation (1 and 2 h) led to a recovery of ATP concentration, but continued reflow (4 h) was associated with a secondary deterioration of high-energy phosphates (p < 0.01). Lactate concentration increased during this recovery period. This deterioration was prevented by PBN (p < 0.05). After 30 min of ischemia, tissue oxygen tension in placenta and fetal brain decreased to about 30% and 50% of control, respectively. However, recirculation brought about a recovery of oxygen delivery. The results indicate that although during the early time period after ischemia fetal cerebral energy metabolism is maintained by an acceleration of the anaerobic glycolytic rate, secondary deterioration of cellular bioenergetic state develops in the immature fetal brain. This deterioration may be due to mitochondrial dysfunction, which may be induced by oxygen-derived free radicals, and not by compromised microcirculation.

Influence of mild hypothermia on delayed mitochondrial dysfunction after transient intrauterine ischemia in the immature rat brain

The aim of this study was to determine the effect of different maternal thermal conditions during transient intrauterine ischemia on the mitochondrial respiratory activities in the immature rat brain. On 17 days of gestation, transient intrauterine ischemia was induced by 30 min of right uterine artery occlusion under hypothermic (33.5-34.5 degrees C, n=6), normothermic (36.5-37.5 degrees C, n=6), and hyperthermic conditions (39.5-40.5 degrees C, n=6). All of the pups were delivered by cesarean section at 21 days of gestation and cerebral neocortical tissue was sampled 1 h after delivery. The mitochondrial respiration was measured polarographically in homogenates. In the ischemic uterine horn, ADP-stimulated respiration of the normothermia and the hyperthermia groups decreased significantly to 73 and 74% of the non-ischemic controls, respectively. Since non-stimulated respiration remained unchanged, the respiratory control ratio (RCR) of the normothermia and the hyperthermia groups decreased significantly to 59 and 54% of the non-ischemic levels, respectively. In contrast, the mitochondrial respiratory activities of the hypothermia group showed no differences between the non-ischemic and the ischemic uterine horns. The results demonstrate that mild maternal hypothermia ameliorates the cerebral mitochondrial dysfunction in neonatal rats after intrauterine ischemia due to transient uterine artery occlusion and suggest that maternal thermal conditions, particularly during uteroplacental insufficiency, have important implications for the neuropathological outcome of the newborn.

Changes in uterine and ovarian arterial impedance during the periovulatory period in conception and nonconception cycles.

Objective: To evaluate whether the Doppler velocimetry of uterine and ovarian arteries during the periovulatory period in conception cycles differs from that in nonconception cycles.

Continuous Observation of Nitric Oxide Production in the Fetal Rat Brain during Uteroplacental Ischemia

Objectives: To demonstrate real-time changes in nitric oxide (NO) production within fetal rat brain during uteroplacental ischemia and subsequent reperfusion. Methods: Using a selective microsensor for NO, changes in NO electrocurrent in the brains of 10 fetal rats at gestational day 20 were observed during and after 30 min occlusion of uterine vessels in anesthetized pregnant rats. Results: The NO electrocurrent reached 397 ± 71.0% of the control level 30 min after occlusion and increased throughout the observation (p < 0.05) until placental administration of 1 M of L-NAME. In contrast, no significant changes in NO electrocurrent were found in 7 sham operated rats. Conclusion: An NO-specific microelectric sensor detected excessive NO production by fetal rat brains in response to uteroplacental ischemia.

Effect of the immunosuppressant drug FK506 on neonatal cerebral mitochondrial function and energy metabolism after transient intrauterine ischemia in rats.

Mitochondrial respiratory activities and energy metabolism were measured in neonatal rat brains to evaluate the influence of transient intrauterine ischemia on the near-term fetus and to assess the effect of the immunosuppressant drug FK506 treatment. Transient intrauterine ischemia was induced by 30 min of right uterine artery occlusion at 17 days of gestation in Wistar rats. The vehicle or 1.0 mg/kg of FK506 was administered after 1 h of recirculation. All of the pups were delivered by cesarean section at 21 days of gestation and samples of cerebral cortical tissue were obtained from pups at 1 h after birth. The mitochondrial respiration was measured polarographically in homogenates. For the analysis of ATP, ADP, and AMP, neonatal brains were frozen in situ and fluorometric enzymatic techniques were used. In the neonatal cortical tissue exposed to ischemia, mitochondrial respiratory activities and ATP concentrations decreased significantly to approximately 59 and 67% of those in normoxic controls, respectively. The deterioration of both mitochondrial respiratory activities and high-energy phosphates was prevented by FK506, given 1 h after the start of recirculation. The present results indicate that transient intrauterine ischemia is accompanied by mitochondrial dysfunction and cellular bioenergetic failure in the neonatal rat brain and suggest that treatment with FK506 prevents the deterioration, even when administered after the ischemic periods.

Thermographic demonstration of nonshivering thermogenesis in human newborns after birth: its relation to umbilical gases

This study was undertaken to measure the extent of nonshivering thermogensis (NST) in brown adipose tissue of human newborns receiving routine thermal care and to examine the influence of oxygen levels at birth on the initiation of NST. Fifteen human neonates were studied in an incubator set at 31-31 degrees C. Thermographic measurements were made every 5 seconds for 5 minutes at 10 and 30 minutes, 1, 3, 6 and 24 hours, and 3 days after birth. The skin temperature and rate of heat dissipation from the interscapular area (location of subcutaneous brown adipose tissue), whole back area, and head area were measured. A heat dissipation ratio (HDR) was calculated as (A-B)/B, where A and B, expressed in Cal/cm2/h, represent rates of heat dissipation from the interscapular area and the whole back area, respectively. Umbilical arterial blood gases were measured immediately after birth. The skin temperature of the interscapular, whole back, and head areas increased significantly during the interval from 10 minutes to 1 hour after birth (p < 0.05). The skin temperature of the interscapular area was highest among the sampled sites during the first hour after birth (p < 0.05). The HDR was highest 10 minutes after birth (p < 0.05). By 1 hour after birth the temperature had reached constant values with low HDR. There was a negative correlation between the HDR and the temperature of the whole back area (p < 0.001). A positive correlation was found between the HDR within 30 minutes after birth and the PO2 of the umbilical arterial blood (p < 0.001). The data support the conclusion that nonshivering thermogenesis is initiated within minutes of birth and contributes to the elevation of body temperature. Furthermore, nonshivering thermogenesis after birth is reduced by low arterial PO2 at the time of birth.

Vitamins ameliorate secondary mitochondrial failure in neonatal rat brain

Recirculation after transient intrauterine ischemia has previously been found to be accompanied by secondary mitochondrial dysfunction in the immature rat brain. This study was performed to assess the efficacy of combined treatment with ascorbic acid and alpha-tocopherol in improving secondary brain damage. On the 17th day of gestation, transient intrauterine ischemia was induced by 30 minutes of uterine artery occlusion. Either vehicle, ascorbic acid, alpha-tocopherol, or combination of ascorbic acid and alpha-tocopherol was randomly administered to pregnant rats before and after occlusion. The pups were delivered by cesarean section at 21 days of gestation, and cerebral neocortical tissue was sampled. The mitochondrial respiration was measured polarographically in homogenates. In the ischemia uterine horn, mitochondrial activity of the vehicle treatment decreased significantly to 56% of nonischemic controls. Treatment with ascorbic acid or alpha-tocopherol alone demonstrated a moderate improvement of the secondary mitochondrial dysfunction to 64% and 62% of nonischemic controls, respectively. The combined treatment caused a normalization of mitochondrial activity to 91% of nonischemic controls. These results indicate that combined treatment with ascorbic acid and alpha-tocopherol has a more protective effect against secondary mitochondrial dysfunction after transient intrauterine ischemia compared with the administration of ascorbic acid or alpha-tocopherol alone.

Secondary Mitochondrial Dysfunction after Transient Intrauterine Ischemia in the Fetal Rat Brain

Objective: Recirculation following transient intrauterine ischemia has previously been found to cause partial recovery and secondary deterioration of cellular bioenergetic states in the fetal rat brain. Our objective was to assess whether secondary bioenergetic failure is due to mitochondrial dysfunction.