Incidence of respiratory depression after epidural administration of morphine for cesarean delivery: findings using a continuous respiratory rate monitoring system.

BACKGROUND: Epidural morphine is widely used for postoperative analgesia after cesarean delivery. However, respiratory depression can occur after neuraxial administration of morphine. Previous reports describing respiratory depression in obstetric patients have relied on intermittent visual counting of the respiratory rate. In this study, we estimated the incidence of respiratory depression in patients who had received epidural morphine after cesarean delivery, using a continuous respiratory rate monitoring system with a finger sensor. METHODS: One hundred patients scheduled to undergo elective cesarean delivery and receive intraoperative neuraxial morphine between April and December 2016 were recruited for this single-center, prospective observational study. Postoperatively, all patients received epidural morphine 3 mg and were equipped with the Nellcor respiratory rate monitoring system. Respiratory depression was defined as both bradypnea (respiratory rate ≤10 breaths/min) and oxygen desaturation (mild ≤95%; moderate ≤90%; severe ≤85%) for longer than one minute. The number of patients with respiratory depression between administration of morphine and first ambulation was recorded hourly. RESULTS: Complete monitoring was obtained for 89 of 100 women. The median duration of monitoring was 19.0 hours. Forty-six patients (52%) developed mild respiratory depression at least once before ambulation, but only one (1%) developed moderate respiratory depression. None required supplemental oxygen or naloxone. CONCLUSIONS: Approximately half the women experienced mild respiratory depression, but only one developed moderate respiratory depression. Continuous respiratory rate monitoring until ambulation may assist in early identification of respiratory depression after neuraxial administration of morphine.

Kainate-induced network activity in the anterior cingulate cortex.

Anterior cingulate cortex (ACC) plays a pivotal role in higher order processing of cognition, attention and emotion. The network oscillation is considered an essential means for integration of these CNS functions. The oscillation power and coherence among related areas are often dis-regulated in several psychiatric and pathological conditions with a hemispheric asymmetric manner. Here we describe the network-based activity of field potentials recorded from the superficial layer of the mouse ACC in vitro using submerged type recordings. A short activation by kainic acid administration to the preparation induced populational activities ranging over several frequency bands including theta (3-8Hz), alpha (8-12Hz), beta (13-30Hz), low gamma (30-50Hz) and high gamma (50-80Hz). These responses were repeatable and totally abolished by tetrodotoxin, and greatly diminished by inhibitors of ionotropic and metabotropic glutamate receptors, GABAA receptor or gap-junctions. These observations suggest that the kainate-induced network activity can be a useful model of the network oscillation in the ACC circuit.

Ultrasound predictors of mortality in monochorionic twins with selective intrauterine growth restriction.

OBJECTIVES: The aim of this study was to evaluate the use of ultrasound assessment to predict risk of mortality in expectantly managed monochorionic twin fetuses with selective intrauterine growth restriction (sIUGR). METHODS: This was a retrospective study of 101 monochorionic twin pregnancies diagnosed with sIUGR before 26 weeks of gestation. All patients were under expectant management during the observation period. At the initial evaluation, the presence or absence of each of the following abnormalities was documented: oligohydramnios; stuck twin phenomenon; severe IUGR < 3(rd) centile of estimated fetal weight; abnormal Doppler in the umbilical artery; and polyhydramnios in the larger twin. The relationships between these ultrasound findings and mortality of sIUGR fetuses were evaluated using multiple logistic regression analysis. RESULTS: Of 101 sIUGR twins, 22 (21.8%) fetuses suffered intrauterine demise and nine (8.9%) suffered neonatal death; 70 (69.3%) survived the neonatal period. Multiple logistic regression analysis revealed that the stuck twin phenomenon (odds ratio (OR): 14.5; 95% CI: 2.2-93.2; P = 0.006) and constantly absent diastolic flow in the umbilical artery (OR: 29.4; 95% CI: 3.3-264.0; P = 0.003) were significant risk factors for mortality. CONCLUSIONS: Not only abnormal Doppler flow in the umbilical artery but also severe oligohydramnios should be recognized as important indicators for mortality in monochorionic twins with sIUGR.

Monochorionic monoamniotic twin pregnancies with two yolk sacs may not be a rare finding: a report of two cases.

The exact determination of amnionicity is a major issue for the clinical management of monochorionic twin pregnancies, due to the high risk of perinatal mortality and morbidity in monochorionic monoamniotic (MCMA) twins. Counting the number of yolk sacs is believed to be a good indicator of amnionicity in the early first trimester, and it has previously been suggested that the number of yolk sacs is equal to amnionicity in both MCMA and monochorionic diamniotic twin pregnancies. However, the accuracy of the relationship between number of yolk sacs and amnionicity has recently been called into question. To the best of our knowledge, no previous reports have shown two yolk sacs in MCMA twin pregnancies. We report two cases of MCMA twins with two yolk sacs on first-trimester ultrasonography, and confirmed monoamnionicity in the second trimester showing umbilical cord entanglement. Postnatal examination showed an MCMA placenta in both cases, and entangled umbilical cords confirmed monoamnionicity. The possibility of monoamnionicity must still be suspected when two yolk sacs are detected early in the first trimester on ultrasound examination in monochorionic twin pregnancies.

Validation of Quintero stage III sub-classification for twin-twin transfusion syndrome based on visibility of donor bladder: characteristic differences in pathophysiology and prognosis.

OBJECTIVE: To validate the Quintero stage III subclassification for twin-twin transfusion syndrome (TTTS) based on visibility of the bladder of the donor twin. METHODS: Between July 2002 and August 2006, there were 131 pregnant Japanese women affected by severe TTTS before 26 weeks' gestation, treated with fetoscopic laser surgery at five centers in Japan, whose pregnancies continued beyond 22 weeks. Outcome data were available in all cases and surviving infants were followed up for at least 6 years. This study focused on the Stage III TTTS patients. These were subclassified into Stage III atypical (abnormal Doppler flow with visible donor bladder) and Stage III classical (abnormal Doppler flow with non-visible donor bladder) groups. Perioperative data and postnatal outcomes were compared between the groups. RESULTS: Seven Stage I, 22 Stage II, 82 Stage III and 20 Stage IV pregnancies continued beyond 22 weeks. There was a significantly higher incidence of absent or reversed end-diastolic velocity in the umbilical artery (UA-AREDV) of the donor in Stage III atypical than in Stage III classical patients (83.8% vs. 53.3%, P = 0.004). Stage III atypical cases also had a significantly higher incidence of arterioarterial (AA) anastomoses (72.9% vs. 17.8%, P < 0.001) and intrauterine fetal demise (IUFD) of the donor (43.2% vs. 13.3%, P = 0.002). However, there were no differences in overall survival or in abnormal brain scans of surviving infants. Donors with both UA-AREDV and AA anastomoses had a significantly higher incidence of IUFD compared with the others (53.3%, P < 0.001). CONCLUSIONS: Quintero stage III atypical was characterized by a high incidence of AA anastomoses and UA-AREDV of the donor, resulting in IUFD. Subclassification of Stage III based on visibility of the bladder of the donor twin was adequate for and compatible with differentiating prognosis and pathophysiology.

In vivo endoscopic assessment of arterioarterial anastomoses: insight into their hemodynamic function.

OBJECTIVE: To assess endoscopically the hemodynamic function of arterioarterial (AA) anastomoses in twin-twin transfusion syndrome (TTTS) and monochorionic selective intrauterine growth restriction (IUGR). MATERIALS AND METHODS: The videotapes of TTTS and IUGR patients undergoing laser surgery between July 1997 and December 2001 were reviewed for the presence of AA anastomoses. The hemodynamic equator was defined as the site within the AA anastomosis with color flashing. AA anastomoses were classified as having unidirectional flow, having bi-directional flow, or being non-functional, depending on whether the hemodynamic equator reached a returning vein to one, both, or neither twin, respectively. TTTS was classified in stages as previously described. RESULTS: AA anastomoses were present in 35/183 (19.1%) of TTTS and in 12/24 (50%) IUGR patients. Of these, the hemodynamic equator was visible in 8/35 (22.8%) TTTS patients (all in stage III, and mostly in atypical stage III) and in 6/12 (50%) IUGR patients (overall 14/47, 29.8%). Of the 14 patients with a visible hemodynamic equator, 13 (92.8%) AA anastomoses showed unidirectional (9/13, 69.2% from the smaller to the larger twin) flow, and only 1/14 (7.1%) showed bi-directional flow. CONCLUSION: The hemodynamic equator is visible in approximately 30% of patients with AA anastomoses. Within this group, most AA anastomoses behave as functional arteriovenous anastomoses, and the direction of flow can be from the smaller to the larger twin or vice versa. The data suggest a correlation between sonographic findings and placental vascular design, also implying possible interfetal oxygenation differences. Further assessment of the functional behavior of AA anastomoses is warranted to understand the pathophysiology of TTTS and selective IUGR.

Analysis of Ca(2+) currents in spermatocytes from mice lacking Ca(v)2.3 (alpha(1E)) Ca(2+) channel.

In mammalian male germ-line cells, low-voltage-activated (LVA) Ca(2+) current has been identified and its electrophysiological properties have been studied. To investigate whether alpha(1)2.3 (alpha(1E)) subunit of the voltage-dependent Ca(2+) channel codes for the LVA current, whole-cell patch clamp and following reverse transcription-polymerase chain reaction (RT-PCR) experiments were performed in pachytene spermatocytes from Ca(v)2.3+/+ and Ca(v)2.3-/- mice. Whole-cell current in acutely dissociated pachytene spermatocytes from Ca(v)2.3+/+ and Ca(v)2.3-/- mice displayed a typical profile of LVA Ca(2+) currents and kinetics with no significant differences. Single-cell RT-PCR revealed the expression of Cacna1g in the pachytene spermatocytes from Ca(v)2.3+/+ and Ca(v)2.3-/- mice in which LVA Ca(2+) currents were actually recorded. These results suggest that the Ca(v)2.3 channel makes no detectable contribution to the LVA Ca(2+) current in the pachytene spermatocyte. Instead, Ca(v)3 family such as Ca(v)3.1 may be the likely candidates responsible for the LVA currents in pachytene spermatocytes.

Multiple G-protein-coupled receptors mediate presynaptic inhibition at single excitatory synapses in the rat visual cortex.

Modulation of excitatory synaptic transmission by agonists for several neurotransmitter receptors was investigated at intrinsic cortical synapses derived from single presynaptic neurons. Excitatory postsynaptic currents (EPSCs) were recorded from layer 5 pyramidal neurons in the rat visual cortex in response to minimal stimulation within the same layer. 5-hydroxytryptamine, adenosine, baclofen, carbachol and DCG-IV all suppressed EPSCs with an increase in paired-pulse ratio. These agonists reduced the frequency of miniature EPSCs without significantly affecting their amplitude distribution. These results suggest that glutamatergic excitatory transmission in the neocortex is under the control of presynaptic inhibition mediated by multiple neuromodulator receptors co-expressed in single presynaptic terminals.

Intact LTP and fear memory but impaired spatial memory in mice lacking Ca(v)2.3 (alpha(IE)) channel.

To investigate the functional roles of the Ca(v)2.3 (alpha(1E)) channel in hippocampal CA1 pyramidal neurons, we studied in vitro synaptic properties and in vivo behaviors of the Ca(v)2.3 gene deficient mice. The Ca(v)2.3 channel mRNA was identified in the hippocampal formation of the wild-type mouse by in situ hybridization. The basic excitatory synaptic transmission and long-term potentiation by theta-burst stimulation were intact in CA1 region of Ca(v)2.3-/- mice. We performed two forms of behavioral tests to examine the hippocampus-dependent function, i.e., emotional and spatial learning tests. The Ca(v)2.3-/- mice were able to establish and maintain fear memories. Although general improvement in the performance of Morris water maze test was seen in Ca(v)2.3-/- mice, they displayed an obvious impairment in the probe test. These results suggest that the Ca(v)2.3 channel plays some role in formation of the accurate spatial memory but not of the fear memory.

Pulmonary stenosis in recipient twins in twin-to-twin transfusion syndrome: report on 3 cases and review of literature.

This report describes 3 cases of pulmonary stenosis in the recipient twin in twin-twin transfusion syndrome. Fetal echocardiography showed cardiomegaly, tricuspid valve regurgitation, and increased reverse flow in the inferior vena cava, as signs of congestive heart failure in all 3 cases. We diagnosed 2 cases of pulmonary stenosis by fetal echocardiography prenatally and confirmed our findings in all 3 cases postnatally. Two cases underwent postnatal balloon valvuloplasty to release the pulmonary valvular stenosis in neonatal period. The third one died soon after delivery and autopsy showed a slightly thickened pulmonary valve. One of the cases was diagnosed in the early second trimester (20 weeks of pregnancy), the earliest detection of fetal pulmonary stenosis reported in literature. The presence of high peak velocity of the pulmonary artery at 20 weeks of pregnancy preceded the development of pulmonary stenosis in this case. This supports the hypothesis that alterations in fetal hemodynamics may result in structural cardiac abnormality.

Neonatal periventricular leukomalacia preceded by fetal periventricular echodensity.

OBJECTIVE: The purpose of this prospective study is to verify whether fetal periventricular echodensity (PVE) precedes neonatal periventricular leukomalacia (PVL). METHODS: Fetal brains were studied with transvaginal scan in 63 high-risk fetuses from 17 to 32 weeks of pregnancy, PVE echogenicity was quantified with ultrasonic histogram, and neonatal brains and clinical courses were studied after birth. RESULTS: No fetal cystic PVL was found, instead, fetal PVE was detected in 42 fetuses. The quantified echogenicity value was higher in PVE than in normal brain. Four cases developed neonatal PVL among 28 preterm and 1 among 14 term births. Neonatal PVL developed in the 23 cases of persistent fetal PVE, whereas no neonatal PVL was found when fetal PVE was negative or disappeared. Cord compression signs were common in PVL cases. CONCLUSION: Neonatal PVL was preceded by antepartum persistent fetal PVE in the present study.

Spinocerebellar ataxia type 6 mutation alters P-type calcium channel function.

Abnormal CAG repeat expansion in the alpha1A voltage-dependent calcium channel gene is associated with spinocerebellar ataxia type 6, an autosomal dominant cerebellar ataxia with a predominant loss of the Purkinje cell. A reverse transcriptase-polymerase chain reaction analysis of mRNA from mouse Purkinje cells revealed a predominant expression of the alpha1A channel lacking an asparagine-proline (NP) stretch in the domain IV (alpha1A(-NP)). Human alpha1A channels carrying various polyglutamine length with or without NP were expressed in HEK293 cells, and channel properties were compared using a whole-cell voltage clamp technique. alpha1A(-NP), corresponding to P-type channel, with 24 and 28 polyglutamines found in patients showed the voltage dependence of inactivation shifting negatively by 6 and 11 mV, respectively, from the 13 polyglutamine control. Contrarily, the alpha1A channel with NP (alpha1A(+NP)), corresponding to Q-type channel, with 28 polyglutamines exhibited a positive shift of 5 mV. These results suggest that altered function of alpha1A(-NP) may contribute to degeneration of Purkinje cells, which express predominantly alpha1A(-NP), due to the reduced Ca(2+) influx resulting from the negative shift of voltage-dependent inactivation. On the other hand, other types of neurons, expressing both alpha1A(-NP) and alpha1A(+NP), may survive because the positive shift of voltage-dependent inactivation of alpha1A(+NP) compensates Ca(2+) influx.

[A case of successful palliative operation of asplenia syndrome with total anomalous pulmonary venous return in young infant].

We reported a successful palliative operation for asplenia syndrome with total anomalous pulmonary venous return (TAPVR Ia) in an infant. The boy was suffering from cyanosis and tachypnea. He was diagnosed as asplenia syndrome with TAPVR and hiatus hernia. After he was admitted to our hospital, pulmonary congestion gradually progressed in a month. At 58 days of age, a palliative operation (repair of TAPVR and pulmonary artery banding with band of 20 mm in length) was performed. The postoperative course was uneventful. At 114 days of age, he underwent curative operation for hiatus hernia without cardiac failure. Postoperative cardiac catheterization at 179 days of age showed appropriate pulmonary artery pressure. We emphasize that pulmonary artery banding which is tighter than usual well controls pulmonary blood flow, although the length of the band in each case should be considered individually.

Cloning and characterization of two human cDNAs encoding the mRNA capping enzyme.

Previous studies demonstrated that the mammalian mRNA capping enzyme is a bifunctional enzyme containing RNA 5'-triphosphatase and mRNA guanylyl-transferase activities in a single polypeptide. In yeast, both the above activities are separated into two different subunits, alpha and beta, the genes for which we have cloned recently. It is thus interesting to compare the structural and functional relationships between the mammalian and yeast capping enzymes. Here we isolated two human cDNAs encoding mRNA capping enzymes termed hCAP1a and hCAP1b which encode 597 and 541 amino acids, respectively. They are different only at the region coding for the C-terminal portion of the enzyme. Comparison of the deduced amino acid sequences with other cellular and viral capping enzymes showed that all the regions conserved among mRNA guanylyltransferases are observed in our clones except one conserved C-terminal region which was absent in the hCAP1b protein. The purified recombinant hCAP1a gene product, hCAP1a, exhibited both RNA 5'-triphosphatase and mRNA guanylyltransferase activities. Deletion mutant analysis of hCAP1a showed that the N-terminal 213 amino acid fragment containing a tyrosine specific protein phosphatase motif catalyzed the RNA 5'-triphosphatase activity and the C-terminal 369 amino acid fragment exhibited the mRNA guanylyltransferase activity. On the other hand, hCAP1b showed RNA 5'-triphosphatase activity, but neither enzyme-GMP covalent complex formation nor cap structure formation was detected.

Isolation and characterization of the yeast mRNA capping enzyme beta subunit gene encoding RNA 5'-triphosphatase, which is essential for cell viability.

The yeast Saccharomyces cerevisiae mRNA capping enzyme is composed of two subunits of alpha (52 kDa, mRNA guanylyltransferase) and beta (80 kDa, RNA 5'-triphosphatase). We have isolated the alpha subunit gene (CEG1) by immunological screening. In this report, with the aid of partial amino acid sequences of purified yeast capping enzyme, we isolated the gene, designated CET1, encoding the S. cerevisiae capping enzyme beta subunit. Amino acid sequence analysis revealed that the gene encodes for 549 amino acids with a calculated M(r) of 61,800 which is unexpectedly smaller than the size estimated by SDS-PAGE. Gene disruption experiment showed that CET1 is essential for yeast cell growth. The purified recombinant CET1 gene product, Cet1, exhibited an RNA 5'-triphosphatase activity which specifically removed the gamma-phosphate from the triphosphate-terminated RNA substrate, but not from nucleoside triphosphates, confirming the identity of the gene. Interaction between the Cet1 and the Ceg1 was also studied by the West-Western procedure using recombinant Ceg1-[32P]GMP as probe.

[Ca2+ channels in the central nervous system].

Roles of Ca2+ channels in physiological functions of mammalian central synapses were discussed from a system-oriented point of view. In the presynaptic terminals of the mammalian CNS so far studied, synaptic transmission is mediated by the subclass of Ca2+ channels designated as the N-type (alpha 1B channels) and/or by that designated as the P/Q-type (alpha 1A channels). In some central synapses such as those between neocortical pyramidal neurons, synaptic transmission is presynaptically suppressed by various transmitter-modulators. Our electrophysiological data indicate that the receptors for amines, glutamate, GABA and adenosine co-exist on individual terminals, and they exert a common modulatory effect on synaptic transmission. Details of the intracellular cascade, i.e., G-protein and Ca2+ channel subtypes that are linked in this modulation, remain to be elucidated. Although the direct 'membrane delimited' action of G-proteins on Ca2+ channels is strongly suggested as a modulatory mechanism by the resemblance to the modulation observed in other neurons, the indirect second messenger pathways, however, may also be involved in the control of Ca2+ channels. Postsynaptically located Ca2+ channels are considered to play important roles in the regulation of neuronal excitability and synaptic plasticity. Individual dendritic spines apparently serve as a primary unit in an increase in Ca2+ level. This compartmentalized increase of Ca2+ seems essential for determining plastic changes of the synaptic efficacy in those particular spines. There is ample evidence indicating that the postsynaptic Ca2+ channels are involved in this Ca2+ transient. In order to understand the physiological significance of Ca2+ channels in CNS functions, further elucidation of channel subtypes, intracellular cascades of the modulator actions and characterization of the channel modifications will be essential.

Coincident induction of K rev-1/rap 1A, rap 1B and H-ras mRNAs in the rat spinal cord by noxious stimulation.

Two cDNA fragments, K rev-1/rap 1A and rap 1B, were amplified from total cellular RNA of the rat spinal cord by reverse transcription-polymerase chain reaction with a set of oligonucleotide primers specific for the human rap 1A cDNA. We report here using Northern blot analysis with these cDNA probes that noxious stimulation causes a marked and coincident increase in rap 1A, rap 1B and H-ras mRNAs in the rat spinal cord. This suggests that Rap 1 participates in sensory processing in spinal neurons in parallel with Ras.

Tachykininergic synaptic transmission in the coeliac ganglion of the guinea-pig.

1. The responses of coeliac ganglion neurones of the guinea-pig to electrical stimulation of the mesenteric nerves and applications of tachykinin receptor agonists were investigated by use of intracellular recording techniques. 2. Ganglion neurones were classified into three groups based on firing patterns in response to a depolarizing current pulse: phasic (38% of the population), tonic (39%) and atypical (23%). In the majority of phasic neurones (91%) a long after-hyperpolarization (LAH) lasting 5-8 s followed action potentials induced by a train of depolarizing current pulses. In contrast, LAH was rarely observed in tonic neurones (5%). 3. In most of tonic neurones (90%) slow excitatory post-synaptic potentials (e.p.s.ps) lasting 3-10 min were evoked by repetitive electrical stimulation of the mesenteric nerves. Prolonged depolarizations were also evoked in most tonic neurones by applications of substance P (SP), neurokinin A (NKA) or senktide, a tachykinin NK3 receptor agonist. 4. In most of phasic neurones (73%), mesenteric nerve stimulation did not induce an obvious depolarization but induced a prolonged inhibition of LAH lasting 3-10 min. Bath-applied tachykinin receptor agonists similarly induced an inhibition of LAH without causing depolarization in most of the phasic neurones. 5. GR 71251 (5 microM), a tachykinin NK1 receptor antagonist, partially depressed the nerve-evoked slow e.p.s.ps in tonic neurones and the nerve-evoked LAH inhibition in phasic neurones. 6. Capsaicin (0.1-5 microM) induced a prolonged depolarization in tonic neurones and an inhibition of LAH in phasic neurones. 7. A mixture of peptidase inhibitors potentiated the depolarization and the LAH inhibition evoked by nerve stimulation, SP and NKA, but not those evoked by senktide. 8. It is concluded that tonic neurones respond to repetitive mesenteric nerve stimulation preferentially with slow e.p.s.ps and that phasic neurones respond preferentially with LAH inhibition. The present study further suggests that SP and NKA, released from axon collaterals of primary afferent neurones, produce slow e.p.s.ps in tonic neurones and the LAH inhibition in phasic neurones via NK1 receptors.

Electrophysiological elucidation of pathways of intrinsic horizontal connections in rat visual cortex.

Cortical neurons receive synaptic inputs through both vertical and horizontal pathways. We made a systematic survey of the synaptic strength and intracortical pathways of intrinsic horizontal connections in rat visual cortex using intracellular recordings from alice preparations. Excitatory postsynaptic potentials were recorded from pyramidal neurons of layers 2/3 and layers 5/6 in response to electrical shocks applied to these layers at a lateral distance of 1.0 mm from the impaled neuron or to the underlying white matter. When the threshold intensity of stimulation to activate monosynaptic excitatory postsynaptic potentials was compared, the vertical input had a lower threshold than the horizontal inputs. The threshold intensity of the horizontal inputs was lower, and the amplitude of the responses was larger in sagittally sectioned slices than in coronal slices, suggesting that the horizontal synaptic connection in the rat visual cortex was stronger in the rostrocaudal than in the mediolateral direction. Tetrodotoxin puffs focally applied to gray matter between the stimulation and the recording sites caused a transient depression of excitatory postsynaptic potentials, which was selective to the input conveyed through the puffed area. This pharmacological dissection revealed that routes parallel to the cortical Iaminae in the same layer as the stimulation site mediated the largest part of excitation conduction of intrinsic connections. Obliquely ascending routes mediated almost half of all the detected inputs originating from a deep layer to the neurons in either layers 5/6 or layers 2/3, whereas the contribution of obliquely descending routes from layers 2/3 to layers 5/6 was small (25%). Our results present semi-quantitative data on the connection diagram of the intrinsic neuronal circuits in the rat visual cortex, which will provide the basis for further investigations of the roles of the intrinsic connections in information processing in rodent cerebral cortex.