Effect of gene flow on spatial genetic structure in the riparian canopy tree Cercidiphyllum japonicum revealed by microsatellite analysis.

Few studies have analyzed pollen and seed movements at local scale, and genetic differentiation among populations covering the geographic distribution range of a species. We carried out such a study on Cercidiphyllum japonicum; a dioecious broad-leaved tree of cool-temperate riparian forest in Japan. We made direct measurement of pollen and seed movements in a site, genetic structure at the local scale, and genetic differentiation between populations covering the Japanese Archipelago. Parentage analysis of seedlings within a 20-ha study site indicated that at least 28.8% of seedlings were fertilized by pollen from trees outside the study site. The average pollination distance within the study site was 129 m, with a maximum of 666 m. The genotypes of 30% of seedlings were incompatible with those of the nearest female tree, and the maximum seed dispersal distance within the study site was over 300 m. Thus, long-distance gene dispersal is common in this species. The correlation between genetic relatedness and spatial distance among adult trees within the population was not significant, indicating an absence of fine-scale genetic structure perhaps caused by high levels of pollen flow and overlapping seed shadows. Six populations sampled throughout the distribution of C. japonicum in Japan showed significant isolation-by-distance but low levels of genetic differentiation (F(ST) = 0.043), also indicating long-distance gene flow in C. japonicum. Long-distance gene flow had a strong influence on the genetic structure at different spatial scales, and contributes to the maintenance of genetic diversity in C. japonicum.

Exaggerated responses to chronic nociceptive stimuli and enhancement of N-methyl-D-aspartate receptor-mediated synaptic transmission in mutant mice lacking D-amino-acid oxidase.

Formalin-induced nociceptive behaviors and N-methyl-D-aspartate (NMDA) subtype glutamate receptor-mediated excitatory synaptic transmission were analyzed in mutant mice lacking D-amino-acid oxidase, which catalyzes the oxidative deamination of D-amino acids. The second phase of the formalin-induced licking response, a part of which is known to be mediated by NMDA receptors in the spinal cord, was significantly augmented in mutant mice. NMDA receptor-mediated excitatory postsynaptic currents recorded from spinal cord dorsal horn neurons by tight-seal whole-cell methods were significantly potentiated in mutant mice. The present observations provide another line of evidence that D-serine functions as an endogenous coagonist at the glycine site of NMDA receptors, and raise the possibility that D-amino-acid oxidase exerts a neuromodulatory function by controlling the concentration of D-serine in the central nervous system.

[A case of amphetamine-induced down-regulation of beta-adrenoceptor].

A 29-year-old man with severe pyloric stenosis confessed that he had been a chronic amphetamine abuser just after awakening from anesthesia for partial gastrectomy. Anesthesia was maintained with thoracic epidural bupivacaine combined with continuous i.v. infusion of propofol. Decreased arterial blood pressure was observed 10 min after starting epidural anesthesia, and remained stable at 80-90 mmHg of systolic blood pressure in spite of massive fluid resuscitation in addition to repeated i.v. administration of ephedrine/methoxamine and continuous i.v. infusion of dopamine at a rate of 8 micrograms.kg-1.min-1. Finally, arterial blood pressure rose gradually after i.v. administration of methylpredonisolone 500 mg. We speculate that the down-regulation of beta-adrenoceptor induced by the sympathomimetic action of amphetamine, might be a major cause of refractory hypotension.

Comparison of hemodynamic effects of enhanced external counterpulsation and intra-aortic balloon pumping in patients with acute myocardial infarction.

This study compared the hemodynamic effects of enhanced external counterpulsation and intra-aortic counterpulsation in patients with acute myocardial infarction. Results demonstrated similarity between these 2 methods, except enhanced external counterpulsation had a transient effect of increasing right atrial pressure, pulmonary capillary wedge pressure, and cardiac index.

A simple method for detecting plasma propofol.

IMPLICATIONS: We measured plasma propofol levels by head space-gas chromatography analysis using solid-phase microextraction. This method saves time, and does not require elimination of interfering substances in the plasma. The coefficient variation was +/-5% to +/-30%. The detection limit was 10 ng/mL.

[Usefulness of tracheal tube with N2O gas-barrier cuff].

We evaluated three different tracheal tubes, Portex Profile Soft-Seal Cuff (PSSC), Portex Profile Cuff (PC) and Mallincrodt Lo-Contour (LC), when they are used in the artificial trachea and in anesthetized patients. When a cuff was inflated in the artificial trachea, PSSC with a cuff of high N2O gas-barrier property, and PC could achieve air-tight sealing with a smaller amount of injected air, compared with LC. This finding suggests that the inflated cuff-shape and cuff-fold formation are important to block the airway leakage with small volume of air. Either of three tubes was used randomly in thirty adult patients for general anesthesia using nitrous oxide 65%. Intracuff pressures were increased significantly with the passage of time. In PSSC group, however, intracuff pressure was 25 +/- 6 mmHg (mean +/- SD) at two hours, and in other two groups it was between 32 and 48 mmHg. The use of a tracheal tube with gas-barrier cuff is recommended to prevent a high tracheal wall pressure.

[Pathophysiology and strategy of shock in terms of tissue oxygen metabolism].

In both septic shock and hypovolemic shock, global oxygen consumption is characterized by the supply dependency phenomenon, which suggests tissue hypoxia. The conventional measurements of blood lactate level, oxygen delivery/oxygen consumption, and mixed venous oxygen saturation may not provide reliable information on the adequacy of tissue oxygenation. The intestinal mucosal villus is particularly vulnerable to a reduction in oxygen delivery because of the countercurrent mechanism. Intestinal mucosal hypoxia may have important clinical ramifications as it has been implicated in the etiology of bacterial translocation and cytokine synthesis. Gastric tonometry has been proposed as a simple, relatively noninvasive technique to detect occult tissue hypoxia. Since gastric intramucosal PCO2 is directly related to arterial PCO2, the gradient between gastric and arterial PCO2 is recommended as a sensitive and specific index of intestinal hypoperfusion. Although the effects of therapeutic interventions are far from consistent, dobutamine, but not dopamine, appears to increase intestinal mucosal blood flow in critically ill patients the most consistently. Further studies are needed to demonstrate the effects of other agents, such as angiotensin-converting enzyme inhibitor and vasodilator prostaglandins. Plasma volume expansion with colloid solution may improve the splanchnic microvascular blood flow. Older stored-blood transfusion, however, may lead to tissue hypoxia.

[Lidocaine metabolism associated with epidural anesthesia in patients for hepatic surgery].

We measured plasma concentrations of lidocaine and its principal metabolite, monoethylglycinexylidide (MEGX) associated with thoracic epidural anesthesia using continuous infusion of lidocaine in 10 patients for hepatectomy and other 10 patients for elective abdominal surgery as a control. Plasma concentrations of lidocaine and MEGX were analysed by fluorescence polarization immunoassay and high performance liquid chromatography, respectively. Plasma lidocaine concentration increased gradually, and peaked to 5.1 +/- 2.3 micrograms.ml-1 (mean +/- SD) at the end of surgery in the hepatectomy group, but not in the control group. No significant differences were observed in plasma MEGX concentration between these two groups. Our findings suggest that MEGX formation by the hepatic cytochrome P-450 system might be impaired associated with hepatic surgery. Hypoperfusion of the liver induced by surgical manipulation may have contributed to this impaired metabolism.

[Anesthesia for a patient with HELLP syndrome].

A 43-year-old female with HELLP syndrome underwent an emergency caesarean section under general anesthesia. Anesthesia was induced by fentanyl and thiopental with oxygen inhalation. Bolus injection of nicardipine was used to treat hypertensive crisis during operation. Continuous intravenous infusion of prostaglandin E1 was started after delivery to normalize arterial blood pressure. After surgery, both the patient and her baby were discharged uneventfully. It is suggested that a suitable dosage of fentanyl is effective without causing serious side effects for neonate. Prostaglandin E1 may have cytoprotective action in vital organs, such as the liver and the kidney, and may stabilize the arterial blood pressure.

[Evaluation of postoperative pain in spinal surgery--usefulness of the administration of local anesthetics into the peridural cavity].

Analgesic effects of perioperative administration of local anesthetics into the peridural cavity were examined in 21 patients with cervical or lumbar vertebral diseases. Sufficient analgesic effects were obtained particularly in patients with lumbar vertebral disease. Administration of local anesthetics was also effective for postoperative sleep on the day of operation. No postoperative neurological side effects were observed. These findings suggest that peridural administration of local anesthetics during spinal surgery is very useful.

[Convulsive seizure after craniotomy--comparison of isoflurane anesthesia and sevoflurane anesthesia].

The incidence of postoperative convulsive seizure was compared retrospectively during either isoflurane or sevoflurane anesthesia in patients after craniotomy. Overall, 5 of a total of 125 patients suffered convulsive seizures after craniotomy: 2 (4%) of 45 patients with isoflurane anesthesia and 3 (4%) of 80 patients with sevoflurane anesthesia. No significant differences were observed between these two groups. The duration of anesthesia and duration of the MAC.h were similar between these two groups. The occurrence of postoperative convulsive seizure was not related with the inhalational anesthetic agents, the underlying disorders and patient characteristics. It is suggested that either isoflurane or sevoflurane anesthesia in neurosurgical patients may have no specific relationship with the postoperative convulsive seizures.

[How should we treat intestinal ischemia?--II: Effects of pentoxifylline, glucagon and prostaglandin E1].

It is important to repair or ameliorate the intestinal ischemia in critically ill patients. Recent study of our suggests the superiority of dobutamine, but not dopamine, in improving the intestinal oxygenation. In this study we examined the effects of pentoxifylline (PF), glucagon (GL) and prostaglandin E1 (PGE1) during reduced blood flow of the superior mesenteric artery (SMA) in 20 anesthetized dogs. As an index of the intestinal oxygenation, tonometrically measured intestinal intramural pH (pHi) was used. A tonometer was inserted into the midjejunum through enterotomy. The SMA blood flow was measured by a transit-time flow meter. A vascular screw clamp for blood flow reduction was placed around the origin of the SMA, proximal to the flow probe. The SMA blood flow was adjusted to 70% of baseline for three hours. After two hours of decreased blood flow, pHi dropped significantly from baseline. Then, either PF (20 mg.kg-1.min-1 over 10 min, followed by 0.1 mg.kg-1.min-1), GL (1 microgram.kg-1.min-1) or PGE1 (0.05 and 0.5 microgram.kg-1.min-1) was infused intravenously for one hour. With infusions of GL and large dose of PGE1, pHi tended to decrease further, although GL increased the cardiac output. Small dose of PGE1 had no significant effect on pHi. PF treatment showed beneficial effects not only on the cardiac output and the SMA blood flow, but also on pHi. We conclude that PF therapy may restore the intestinal microvascular blood flow. Further study of the effects of PF on tissue oxygenation and blood rheology is warranted.

[How should we treat intestinal ischemia?--1: Effects of dobutamine and dopamine].

Intestinal mucosal ischemia is one of the earliest manifestations of impaired core tissue perfusion in critically ill patients. The aim of this study was to investigate the effects of dobutamine and dopamine on intestinal ischemia in ten anesthetized dogs. Intestinal intramural pH (pHi) by tonometry is an early reliable marker of assessing the adequacy of tissue oxygenation. A tonometer was inserted into the midjejunum through enterotomy. The superior mesenteric artery (SMA) blood flow was measured by a transit-time ultrasonic flowmeter. A vascular screw clamp for blood flow reduction was placed at the origin of the SMA, proximal to the flow probe. The SMA blood flow was maintained at 70% of baseline flow for three hours. After two hours of decreased blood flow, intravenous dobutamine or dopamine was infused at a rate of 5 micrograms.kg-1.min-1 for one hour. The pHi fell significantly from 7.16 +/- 0.04 to 7.08 +/- 0.04 in dobutamine group, and from 7.18 +/- 0.04 to 7.06 +/- 0.05 in dopamine group two hours after induction of intestinal ischemia. Treatments with dobutamine and dopamine increased the SMA blood flow to near baseline levels. Dobutamine caused a significant increase in pHi to 7.11 +/- 0.04. On the contrary, dopamine tended to decrease pHi further to 7.01 +/- 0.09. These results suggest that dobutamine may improve intestinal tissue oxygenation. However, dopamine even at lower doses, may induce constriction of the intestinal mucosal arterioles.

[Gastrointestinal mucosal ischemia in hemorrhagic shock--measurement with a tonometer].

Splanchnic ischemia produces the most rapid progression of mucosal injury. A reliable method for monitoring the adequacy of tissue oxygenation in the mucosal layer would be clinically valuable. In this study, we investigated the potential value of tonometric intestinal intramucosal pH (pHi) monitoring during hemorrhagic shock in twelve anesthetized dogs. The tonometer consists of a sampling tube with a silicone balloon attached to the tip that is freely permeable to CO2. Intestinal pHi was calculated by the Henderson-Hasselbalch equation and measurements of the PCO2 of the normal saline within the balloon and arterial bicarbonate. The tonometer was placed in the midpart of the small intestine through a small enterotomy. Arterial blood was removed into a heparinized bag to achieve a mean arterial blood pressure of 50-60 mmHg for two hours. Baseline pHi level was 7.28 +/- 0.02 (mean +/- SE). Following hemorrhage, pHi continued to decrease significantly during the experiments down to 6.94 +/- 0.05 at one hour and 6.82 +/- 0.12 at two hours. By treatment with an intravenous infusion of dopamine at a rate of 3 micrograms.kg-1.min-1 started at one hour after hemorrhage, pHi did not returned to baseline levels. Monitoring pHi in the small intestine using tonometer could be a useful technique to provide early detection of insufficient mucosal blood flow.

[The effect of xanthine oxidase inhibitor on hindlimb ischemia-induced thromboxane A2 release].

Our previous studies demonstrated that the bilateral hindlimb ischemia/reperfusion stimulates thromboxane A2 (TXA2) production. The present study tests the role of xanthine oxidase-derived oxygen free radicals in mediating this event. In twelve anesthetized dogs, the abdominal aorta and the inferior vena cava were clamped for 150 min, declamped and reperfused for 30 min. Two groups were studied: untreated control group and pretreated group with xanthine oxidase inhibitor, allopurinol 100 mg.kg-1 orally 24 hr before clamping plus 25 mg.kg-1 intravenously 15 min before clamping. In the control group, plasma TXB2 levels increased markedly after reperfusion. On the other hand, prior treatment with allopurinol attenuated the increase in plasma TXB2 levels at 30 min after reperfusion. This model revealed partial ischemia, because the femoral arterial blood flow was approximately 15% of baseline during clamping. However, the present study suggests that ischemia/reperfusion stimulates TXA2 production, which may be partly affected by hypoxanthine-xanthine oxidase-derived oxygen free radicals and may be an important mechanism responsible for reperfusion injury.

[The effectiveness of angiotensin II antagonist on experimental pulmonary embolism--comparison of propranolol with prostaglandin F2 alpha].

We studied the effects of angiotensin II (A-II) antagonist, propranolol and prostaglandin F2 alpha (PGF2 alpha) on arterial hypoxemia after injecting autologous muscle to induce massive pulmonary embolism. Twenty-four anesthetized paralyzed dogs were divided into four groups; control, intravenous A-II antagonist (1-sarcosine, 8-isoleucine A-II) infusion at 5 micrograms.kg-1.min-1, intravenous propranolol injection at 1.5-2.0 mg, and intravenous PGF2 alpha infusion at 1 microgram.kg-1.min-1. With FIO2 of 0.33, the administration of A-II antagonist produced an increase in arterial PO2 from 134 +/- 16 (mean +/- SE) to 155 +/- 11 mmHg during infusion, and to 160 +/- 9 mmHg 30 min after infusion. Simultaneous hemodynamic measurements demonstrated no significant changes in arterial blood pressure and heart rate, but a slight increase in cardiac output was observed. On the other hand, propranolol and PGF2 alpha did not reverse the pulmonary oxygenation. Cardiac output decreased after propranolol, and alveolar dead space and pulmonary artery pressure increased further after PGF2 alpha. We conclude that A-II antagonist may be effective in the treatment of massive pulmonary embolism, possibly by improving the ventilation-perfusion relationship. The exact mechanism of the effect of A-II antagonist has not been clarified.

Effects of dibutyryl cyclic AMP on hemodynamics and plasma catecholamine concentrations during ammonium chloride-induced metabolic acidosis in anesthetized dogs.

We investigated, using anesthetized dogs, the effect of dibutyryl cyclic AMP (db-cAMP), a derivative of cyclic AMP (cAMP), on cardiovascular variants and plasma catecholamines during metabolic acidosis. These effects were also compared with those of dopamine. The db-cAMP and dopamine were infused at 200 and 20 micrograms/kg.min, respectively. Metabolic acidosis (pH 7.00, PaCO2 40 torr) was induced by the iv infusion of 1-M ammonium chloride solution (NH4Cl). In the normal acid-base state, both db-cAMP and dopamine significantly increased cardiac output and decreased systemic vascular resistance (SVR). During metabolic acidosis, db-cAMP increased cardiac output by 69 +/- 14% and decreased SVR by 36 +/- 2%, while dopamine did not produce changes in cardiac output and increased SVR. Dopamine caused an elevation of epinephrine and norepinephrine in the normal acid-base state, but db-cAMP did not. During metabolic acidosis, dopamine significantly increased the plasma concentration of epinephrine and norepinephrine, while db-cAMP significantly decreased epinephrine concentration. These results suggest that db-cAMP may have a more beneficial effect on hemodynamics compared with dopamine when therapeutic support is needed during circulatory insufficiency with severe metabolic acidosis.

[Transesophageal endoscopic ultrasonography in lung cancer involving mediastinal organs in the assessment of resectability].

The resectability of primary lung cancer depends on the extent of invasion to the mediastinum. To evaluate whether transesophageal endoscopic ultrasonography (E-EUS) could detect mediastinal invasion of lung cancer or not, this method was applied in 22 lung cancer cases in which mediastinal invasion was suspected on the basis of the chest roentgenogram and/or CT scan. An ultrasonic probe with a 5 MHz linear array transducer, 12 mm in diameter and 40 mm in length was attached to the tip of an esophagofiberscope for this study. Ultrasonographic findings were classified into four grades, grade 0; existence of a hyperechoic area between the tumor mass and the mediastinum, grade I; tumor mass in direct contact with mediastinum which appears to be normal in structure accompanied by movement of tumor mass on respiration, grade II; partial disappearance of laminar structures and changes in the mediastinal wall, with no movement of the tumor mass relative to the mediastinum, grade III; tumor invasion within the lumen of the mediastinum. Organs contained by the mediastinum include the pulmonary arteries, aorta, left atrium, pulmonary veins, superior vena cava (SVC) and the esophagus were clearly visualized in detail as real-time images, therefore more detailed information about changes in the laminar structures of walls could be obtained. The sensitivity, specificity and accuracy of E-EUS were 77.8%, 81.8% and 80.0%, respectively. E-EUS could detect mediastinal invasion more accurately than chest roentgenogram, CT or MRI. Particularly, in the SVC, descending aorta and esophagus, the longitudinal extent of tumor can be analyzed accurately. These results suggest that E-EUS can be useful to assess resectability and also to decide the surgical margin preoperatively in case of primary lung cancer in which mediastinal involvement is considered.