[Examination of the optimal midazolam dose required for loss of puncture memory at the time of spinal anesthesia]

BACKGROUND

We examined midazolam ED50 according to age that was necessary for loss of puncture memory at the time of spinal anesthesia and determined whether we could estimate the presence of puncture memory from the degree of sedation after midazolam administration.

METHODS

We enrolled patients with ASA PS 1 or 2 and patients from 50 to 80 years of age who had been planned for surgery with spinal anesthesia. We divided the patients into groups according to their age--50s, 60s, and 70s as L, M, and H groups, respectively. We evaluated the degree of sedation with six phases of scores after intravenous administration of midazolam and spinal anesthesia was performed. The midazolam dose was based on the ups and downs method.

RESULTS

The midazolam ED50s required for the loss of puncture memory in groups L, M, and H were 0.043, 0.035, and 0.026 mg x kg(-1), respectively. We estimated the association between the sedation degree score after midazolam administration and the puncture memory from ROC curve, but AUC was 0.56 for all cases.

CONCLUSIONS

The midazolam ED50 required for the loss of puncture memory decreased with age but it was difficult to estimate puncture memory from the degree of sedation.

A new modification for safer submental orotracheal intubation

In patients in whom a tracheal tube cannot be inserted through the nostrils due to multiple facial trauma or hypoplasty of the nose, submental orotracheal intubation (SOI) is performed to avoid tracheostomy. We report a new modification for SOI to minimize the risk of apnea. A 20-year-old man was scheduled for sagittal split ramus osteotomy. As the patient had severe hypoplasia of the nose, SOI was planned. Following orotracheal intubation with a spiral tube (first tube), a submental tunnel was surgically created. A second tube that had been confirmed, in advance, to snugly fit into the proximal end of the first tube was passed into the submental tunnel via a polypropylene cylinder and connected between the first tube and the breathing circuit. After careful withdrawal of the second tube through the submental tunnel, the first tube was directly connected to the breathing circuit after removal of the second tube. Although this technique requires additional time, apnea time is minimal even in patients in whom withdrawal of the tracheal tube through the submental tunnel takes time, because the second tube forms a link between the first tube and the breathing circuit, making it possible to ventilate the patient throughout the procedure.

Eed/Sox2 regulatory loop controls ES cell self-renewal through histone methylation and acetylation

Transcription factors and epigenetic modulators are involved in the maintenance of self-renewal in embryonic stem (ES) cells. Here, we demonstrate the existence of a regulatory loop in ES cells between Sox2, an indispensable transcription factor for self-renewal, and embryonic ectoderm development (Eed), an epigenetic modulator regulating histone methylation. We found that Sox2 and Eed positively regulate each other's expression. Interestingly, Sox2 overexpression suppressed the induction of differentiation-associated genes in Eed-deficient ES cells without restoring histone methylation. This Sox2-mediated suppression was prevented by knockdown of the histone acetyltransferase (HAT), Tip60 or Elp3, and Sox2 stimulated expression of these HATs. Furthermore, forced expression of either HAT resulted in repression of differentiation-associated genes in Eed-deficient cells. These results suggest that Sox2 overcame the phenotype of Eed-deficient ES cells by promoting histone acetylation. We also found that knockout of Eed and knockdown of these HATs synergistically enhanced the upregulation of differentiation-associated genes in ES cells. Taken together, our results suggest that the Eed/Sox2 regulatory loop contributes to the maintenance of self-renewal in ES cells by controlling histone methylation and acetylation.

The Optical Resolution of Racemic Chlorpheniramine and Its Stereoselective Pharmacokinetics in Rat Plasma

An ovomucoid-conjugated column has been developed for the chiral stationary-phase liquid chromatographic resolution of racemic chlorpheniramine with a quantitation limit of 0·05 μg mL−1. The assay was used to study the stereoselective kinetics of chlorpheniramine enantiomers in rats. After bolus intravenous administration of racemic chlorpheniramine maleate (20 mg kg−1), plasma concentration of the (–)-form was higher than that of the (+)-form. In the elimination phase, the concentrations of (+)- and (–)-chlorpheniramine in the plasma declined biexponentially with half-lives of 18·2 and 50·0 min, respectively. Although there was no significant difference in blood-to-plasma concentration ratio of both enantiomers, the apparent total blood clearance of (+)-chlorpheniramine was twice as large as that of the (–)-isomer. Binding of (–)-chlorpheniramine to rat plasma protein was stronger than that of (+)-chlorpheniramine suggesting stereoselective pharmacokinetics may be due to a difference in the plasma protein binding.

On the use of prothrombin complex concentrate in patients with coagulopathy requiring tooth extraction

In patients on high-level anticoagulant therapy (prothrombin time-international normalized ratio [PT-INR] ≥ 4.5), surgical procedures can be carried out with bridging therapy using heparin. However, surgical treatment options are severely limited in patients on high-level anticoagulant therapy and who have heparin-induced thrombocytopenia (HIT), as heparin use is contraindicated. We performed tooth extraction using prothrombin complex concentrate (PCC) in 2 HIT patients on high-level anticoagulation therapy (PT-INR ≥ 4.5). Five hundred units of PCC were administered intravenously, and after 15 minutes, it was confirmed that PT-INR was less than 2.0. Tooth extraction was then performed and sufficient local hemostasis was achieved. At 3 hours after tooth extraction, PT-INR was 2.0 or higher and later increased to 4.0 or higher, but postoperative bleeding was mostly absent. When performing tooth extraction in HIT patients on high-level anticoagulant therapy, favorable hemostatic management was achieved through sufficient local hemostasis and transient warfarin reversal using PCC.

Choice of random rather than imprinted X inactivation in female embryonic stem cell-derived extra-embryonic cells

In female mammals, one of two X chromosomes is epigenetically inactivated for gene dosage compensation, known as X inactivation (Xi). Inactivation occurs randomly in either the paternal or maternal X chromosome in all embryonic cell lineages, designated as random Xi. By contrast, in extra-embryonic cell lineages, which are segregated from somatic cell lineages in pre-implantation development, the paternal X chromosome is selectively inactivated, known as imprinted Xi. Although it is speculated that erasure of the imprinted mark on either the maternal or paternal X chromosome in somatic cell lineages might change the mode of Xi from imprinted to random, it is not known when this event is completed in development. Here, we tested the mode of Xi during the differentiation of female mouse embryonic stem (ES) cells derived from the inner cell mass (ICM) of blastocyst-stage embryos toward trophectoderm (TE) and primitive endoderm (PrE) lineages induced by artificial activation of transcription factor genes Cdx2 and Gata6, respectively. We found that random Xi occurs in both TE and PrE cells. Moreover, cloned embryos generated by the transfer of nuclei from the female ES cells showed random Xi in TE, suggesting the complete erasure of all X imprints for imprinted Xi in ICM-derived ES cells.

Hemodynamic and autonomic response to acute hemorrhage in streptozotocin-induced diabetic rats

Background

The various autonomic control systems lead to characteristic changes in heart rate (HR) and blood pressure (BP) during acute hemorrhage. However, cardiovascular autonomic neuropathy due to diabetes mellitus may interfere with the normal compensation for hemorrhage.

Materials and methods

A controlled graded bleeding (6 - 36% loss of estimated total blood volume: ETBV) was performed in streptozotocin-induced diabetic rats (STZ rats) under a conscious state. Hemodynamic and autonomic responses to acute hemorrhage were examined using analysis of BP-HR variability. The effects of dextran treatment after hemorrhage were also examined.

Results

A significant reduction in mean arterial pressure began at 12% ETBV loss in STZ rats and 18% in the control rats, respectively. When blood loss reached 18% of TEBV, the decrease in HR was prominent in STD rats due to the activation of a parasympathetic drive, as indicated by the increase in high frequency (HF; 0.75~3.0 Hz) power in HR variability, while in the control rats this response was not observed. The administration of dextran prevented the activation of the parasympathetic drive in STZ rats during hemorrhaging. In the control rats, the dextran treatment sustained the initial increase in HR with reduced HF power in HR variability.

Conclusion

STZ rats showed different hemodynamic and autonomic responses to acute hemorrhage from the control rats. STZ rats were prone to develop bradycardiac hypotension characterized by marked parasympathetic activation during hemorrhaging. This finding suggests enhancement of the Bezold-Jarisch reflex in STZ rats. Dextran treatment to maintain a normovolemic hemorrhage state inhibits this reflex.

PIH1D1, a subunit of R2TP complex, inhibits doxorubicin-induced apoptosis

We have previously reported that the two components of R2TP complex, RNA polymerase II-associated protein 3 (RPAP3), and Reptin, regulate apoptosis. Here we characterize another component of the complex, PIH1 domain containing protein 1 (PIH1D1). PIH1D1 interacts with both RPAP3 and Monad in HEK293 or U2OS cells. PIH1D1 transcripts were abundant in lung, leukocyte, and placenta. The reduction in endogenous PIH1D1 by siRNA enhanced apoptosis and caspase-3 activation induced by doxorubicin in U2OS cells. These results suggest that PIH1D1 may also function as a novel modulator of apoptosis pathway.

Molecular pathway and cell state responsible for dissociation-induced apoptosis in human pluripotent stem cells

Human embryonic stem cells (hESCs), unlike mouse ones (mESCs), are vulnerable to apoptosis upon dissociation. Here, we show that the apoptosis, which is of a nonanoikis type, is caused by ROCK-dependent hyperactivation of actomyosin and efficiently suppressed by the myosin inhibitor Blebbistatin. The actomyosin hyperactivation is triggered by the loss of E-cadherin-dependent intercellular contact and also observed in dissociated mouse epiblast-derived pluripotent cells but not in mESCs. We reveal that Abr, a unique Rho-GEF family factor containing a functional Rac-GAP domain, is an indispensable upstream regulator of the apoptosis and ROCK/myosin hyperactivation. Rho activation coupled with Rac inhibition is induced in hESCs upon dissociation, but not in Abr-depleted hESCs or mESCs. Furthermore, artificial Rho or ROCK activation with Rac inhibition restores the vulnerability of Abr-depleted hESCs to dissociation-induced apoptosis. Thus, the Abr-dependent "Rho-high/Rac-low" state plays a decisive role in initiating the dissociation-induced actomyosin hyperactivation and apoptosis in hESCs.

DNA methylation is dispensable for the growth and survival of the extraembryonic lineages

DNA methylation regulates development and many epigenetic processes in mammals, and it is required for somatic cell growth and survival. In contrast, embryonic stem (ES) cells can self-renew without DNA methylation. It remains unclear whether any lineage-committed cells can survive without DNA-methylation machineries. Unlike in somatic cells, DNA methylation is dispensable for imprinting and X-inactivation in the extraembryonic lineages. In ES cells, DNA methylation prevents differentiation into the trophectodermal fate. Here, we created triple-knockout (TKO) mouse embryos deficient for the active DNA methyltransferases Dnmt1, Dnmt3a, and Dnmt3b (TKO) by nuclear transfer (NT), and we examined their development. In chimeric TKO-NT and WT embryos, few TKO cells were found in the embryo proper, but they contributed to extraembryonic tissues. TKO ES cells showed increasing cell death during their differentiation into epiblast lineages, but not during differentiation into extraembryonic lineages. Furthermore, we successfully established trophoblastic stem cells (ntTS cells) from TKO-NT blastocysts. These TKO ntTS cells could self-renew, and they retained the fundamental gene expression patterns of stem cells. Our findings indicated that extraembryonic-lineage cells can survive and proliferate in the absence of DNA methyltransferases and that a cell's response to the stress of epigenomic damage is cell type dependent.

[Surgical treatment for tumors in the superior sulcus]

Surgical challenge for tumors arising posterior-apical lung well known as Pancoast tumor and those of the apical lung involving anterior thoracic outlet structures (mainly subclavian vessels) have been continued with seeking the pathway of the proper approaches and the strategy combined modalities as radiotherapy or chemoradiotherapy followed by surgery for these 50 years, and operative outcome have been improved these decades. As complete resection of the tumors is the main factor for operative results, the preoperative evaluation on involved structures and the choice among the different approaches is important. We present our experience for Pancoast tumors with posterior approaches and for cervico-thoracic tumors resected with anterior approaches.

Influence of acute hypoxia combined with nitrous oxide on cardiovascular variability in conscious hypertensive rats

Anesthetics have been reported to depress autonomic nervous system (ANS) responses to hypoxia. The mechanisms by which cardiovascular variability responds to acute progressive hypoxia (APH) under nitrous oxide (N(2)O) inhalation, however, remain unclear. Additionally, the effect of hypertension on ANS responses in such cases has not been fully clarified. The present study examined the influence of APH (10% O(2)) under 60% N(2)O inhalation on cardiovascular variability in conscious, spontaneously hypertensive rats (SHR). Twenty-seven male SHR were randomly assigned to 3 treatment groups receiving N(2)O inhalation alone, APH stress alone or APH stress under N(2)O inhalation, using Wistar Kyoto rats (WKY) or non-N(2)O inhalation rats as controls. Systolic blood pressure (SBP) and heart rate (HR) variability were evaluated time-dependently using the wavelet method. While inhalation of N(2)O alone induced more powerful sympathomimetic actions in SHR than in WKY, circulatory and parasympathetic reactions were weaker. APH stress alone evoked significant inhibition of cardiac parasympathetic activity from immediately after exposure to hypoxic stress in SHR in contrast to WKY, facilitating tachycardia. This inhibition of parasympathetic activity in SHR continued without coupled changes in sympathetic activity. In SHR, APH under N(2)O inhalation decreased SBP and sympathetic activity more prominently and earlier than APH alone, and earlier than APH under N(2)O inhalation in WKY. Additionally, APH under N(2)O inhalation inhibited cardiac parasympathetic activity in SHR as compared to APH stress alone. In conclusion, APH under N(2)O inhalation in SHR potentially results in exacerbation of circulatory suppression from the earlier hypoxic phase, compared with non-N(2)O inhalation.

Mouse ES cell culture system as a model of development

Mouse embryonic stem (mES) cells are pluripotent stem cells derived from pre-implantation embryos. They are regarded as an essential tool for studying mouse development, as they provide a means for generating knock-out mouse lines. This, however, is not the sole utility of the mES cell system. They undergo differentiation in culture, mimicking the morphological differentiation of peri-implantation embryos from epiblast to egg-cylinder stage. Moreover, they retain the capacity to respond to triggers of differentiation toward trophectoderm and primitive endoderm by forced activation. For these reasons, mES cells can be regarded as a useful tool for analyzing molecular mechanisms underlying early mouse development.

[Surgical treatment for Pancoast tumors--significance of surgical approach and induction chemoradiotherapy]

We analyzed 46 patients with Pancoast tumor who underwent surgical resection. Anterior approach was employed for 16 patients and hook approach for 30 patients. Twenty-one patients received preoperative treatment; chemotherapy for 1 patient, radiotherapy for 11 patients, and chemoradiotherapy for 9 patients. Complete resection was achieved in 59% (27/46) of patients. The overall 5-year survival rate was 10.9%. Five-year survival was significantly higher in the patients received complete resection than the patients received incomplete resection (18.5 vs 0%, p=0.0016). The complete resection rate has improved in recent cases, and one of the reasons seems to be the adoption of preoperative chemoradiotherapy. But postoperative complications occurred more frequently in patients who received induction therapy than the others. Optimal selection of surgical approach and induction chemoradiotherapy for Pancoast tumors appear to provide improved complete resection rate and long term survival.