Predictive performance of the sequential organ failure assessment score for in-hospital mortality in patients with end-stage kidney disease in intensive care units: A multicenter registry in Japan

INTRODUCTION

There is limited evidence regarding whether the performance of the Sequential Organ Failure Assessment (SOFA) score differs between patients with and without end-stage kidney disease (ESKD) in intensive care units (ICUs).

METHODS

We used a multicenter registry (Japanese Intensive care Patient Database) to enroll adult ICU patients between April 2018 and March 2021. We recalibrated the SOFA score using a logistic regression model and evaluated its predictive ability in both ESKD and non-ESKD groups. The primary outcome was in-hospital mortality.

RESULTS

128 134 patients were enrolled. The AUROC of the SOFA score was lower in the ESKD group than in the non-ESKD group [0.789 (95% CI, 0.774-0.804) vs. 0.846 (95% CI, 0.841-0.850)]. The calibration plot revealed good performance in both groups. However, it overestimated in-hospital mortality in ESKD groups.

CONCLUSION

The SOFA score demonstrated good predictive ability in patients with and without ESKD, but it overestimated the in-hospital mortality in ESKD patients.

Transcriptional, biochemical, and immunohistochemical analyses of CaMKKβ/2 splice variants that co-localize with CaMKIV in spermatids

Ca2+/calmodulin-dependent protein kinase kinase (CaMKK) phosphorylates and activates downstream protein kinases, including CaMKI, CaMKIV, PKB/Akt, and AMPK; thus, regulates various Ca2+-dependent physiological and pathophysiological pathways. Further, CaMKKβ/2 in mammalian species comprises multiple alternatively spliced variants; however, their functional differences or redundancy remain unclear. In this study, we aimed to characterize mouse CaMKKβ/2 splice variants (CaMKKβ-3 and β-3x). RT-PCR analyses revealed that mouse CaMKKβ-1, consisting of 17 exons, was predominantly expressed in the brain; whereas, mouse CaMKKβ-3 and β-3x, lacking exon 16 and exons 14/16, respectively, were primarily expressed in peripheral tissues. At the protein level, the CaMKKβ-3 or β-3x variants showed high expression levels in mouse cerebrum and testes. This was consistent with the localization of CaMKKβ-3/-3x in spermatids in seminiferous tubules, but not the localization of CaMKKβ-1. We also observed the co-localization of CaMKKβ-3/-3x with a target kinase, CaMKIV, in elongating spermatids. Biochemical characterization further revealed that CaMKKβ-3 exhibited Ca2+/CaM-induced kinase activity similar to CaMKKβ-1. Conversely, we noted that CaMKKβ-3x impaired Ca2+/CaM-binding ability, but exhibited significantly weak autonomous activity (approximately 500-fold lower than CaMKKβ-1 or β-3) due to the absence of C-terminal of the catalytic domain and a putative residue (Ile478) responsible for the kinase autoinhibition. Nevertheless, CaMKKβ-3x showed the ability to phosphorylate downstream kinases, including CaMKIα, CaMKIV, and AMPKα in transfected cells comparable to CaMKKβ-1 and β-3. Collectively, CaMKKβ-3/-3x were identified as functionally active and could be bona fide CaMKIV-kinases in testes involved in the activation of the CaMKIV cascade in spermatids, resulting in the regulation of spermiogenesis.

Postoperative nausea and vomiting after artificial joint replacement surgery: comparison between remimazolam and sevoflurane, a propensity score analysis

PURPOSE

Remimazolam, a newly synthesized ultrashort-acting benzodiazepine, has not been previously compared with sevoflurane with regard to postoperative nausea and vomiting (PONV). The aim of this study is to investigate the incidence of PONV between remimazolam and sevoflurane among patients undergoing artificial joint replacement surgery.

METHODS

We conducted a retrospective analysis of the electronic medical records of patients who underwent artificial joint replacement surgery at Kobe City Medical Center General Hospital from 2020 to 2022, with a focus on comparing the incidence of PONV among those who received sevoflurane versus remimazolam anesthesia. To control for confounding factors, we employed a propensity score-matching technique to pair patients who received sevoflurane anesthesia with those who received remimazolam anesthesia.

RESULTS

The records of 292 patients receiving general anesthesia for artificial joint replacement surgery were collected and categorized into group sevoflurane (n = 241) or group remimazolam (n = 51). Before propensity score matching, age and ASA-PS exhibited significant differences between two groups. There was no significant difference in the incidence of PONV between them (p = 0.461). After matching, there were 51 patients in each group. However, there is no significant difference in the incidence of PONV between the two matched cohorts (p = 0.243).

CONCLUSIONS

This study demonstrated that there was no difference in the prevalence of PONV between remimazolam and sevoflurane anesthesia in patients undergoing artificial joint replacement surgery.

Rapid detection of calmodulin/target interaction via the proximity biotinylation method

Calmodulin (CaM) is known to function as a central signal transducer in calcium-mediated intracellular pathways. In this study, a fusion molecule of a recently developed proximity biotinylation enzyme (AirID) with rat CaM (AirID-CaM) was expressed and purified to near homogeneity using an E. coli expression system to examine the physical interactions between CaM and its target proteins by converting the interaction to biotinylation of CaM targets under nondenatured conditions. AirID-CaM catalyzed a Ca²⁺-dependent biotinylation of a target protein kinase (Ca²⁺/CaM-dependent protein kinase kinase α/1, CaMKKα/1) in vitro, which was suppressed by the addition of excess amounts of CaM, and AirID alone did not catalyze the biotinylation of CaMKKα/1, indicating that the biotinylation of CaMKKα/1 by AirID-CaM likely occurs in an interaction-dependent manner. Furthermore, we also observed the Ca²⁺-dependent biotinylation of GST-CaMKIα and GST-CaMKIV by AirID-CaM, suggesting that AirID-CaM can be useful for the rapid detection of CaM/target interactions with relatively high sensitivity.

Cardiac Arrest Following Remimazolam-Induced Anaphylaxis: A Case Report

Remimazolam is a recently approved benzodiazepine sedative. We report a case of a 72-year-old man who experienced a cardiac arrest due to severe anaphylaxis immediately after general anesthesia induction. Based on the results of skin tests, including those for dextran 40, an excipient in the remimazolam solution, and a review of drugs given during 3 anesthetics, remimazolam was identified as the probable causative agent. Although remimazolam is structurally similar to midazolam, the patient was not allergic to midazolam as demonstrated before and after anaphylaxis. This report highlights the potential risk of allergic reactions to remimazolam.

Ventricular septal rupture with right hypochondrial pain mimicking acute cholecystitis

A 67-year-old man was admitted for anterior acute ST elevation myocardial infarction (STEMI) management. He developed a severe acute right subcostal pain with normal cardiac tests. On day 5 of hospitalization, cholecystectomy was performed for suspected acute cholecystitis, but the pain intensified with hemodynamical instability. Transthoracic echocardiography revealed ventricular septal rupture (VSR). After emergency operation was performed, the pain diminished with improved hemodynamics. Right subcostal pain associated with heart disease can be referred from STEMI or liver congestion with right heart failure. VSR and right heart failure may be considered as a cause of right subcostal pain of uncertain etiology.

<Learning objective: Patients presenting with signs suggestive of acute cholecystitis may be misdiagnosed, and we highlight the importance of considering ventricular septal rupture as a differential diagnosis.>

Longer term hemodialysis-dependent chronic renal failure increases the risk of post-cardiac surgery vasoplegic syndrome

PURPOSE

We evaluated whether longer term hemodialysis (HD) is associated with a higher incidence of vasoplegic syndrome (VS) after cardiac surgery.

METHODS

This retrospective, single-center cohort study included 562 consecutive patients who underwent cardiac surgery in a tertiary hospital from January 2015 to December 2016. We assessed VS occurrence and its relationship with HD duration and other risk factors. To assess the effect of the HD duration on VS occurrence, we constructed ordinal variables: HD = 0 (non-HD), 0 < HD ≤ 5 (HD ≤ 5 years), 5 < HD ≤ 10, and 10 < HD.

RESULTS

The overall mean (± standard deviation) age of patients was (73 ± 11) years, and there were 60.9% men. Forty-one patients (7.3%) were HD dependent. Cardiac surgeries included all coronary artery bypass graft procedures, all valvular procedures, and aortic surgery involving cardiopulmonary bypass (CPB). Sixty-six patients (10%) developed VS. Most preoperative patient characteristics were comparable between the VS and no-VS groups; a chronic HD status and a total CPB time of > 180 min were significantly more common in the VS group (P < 0.0001 and P = 0.02, respectively). Longer term HD significantly correlated with VS incidence (P < 0.0001). Ordinal variables for the HD duration and age and known risk factors for VS (preoperative use of angiotensin-converting enzyme inhibitors and beta-blockers, low left-ventricular ejection fraction, and CPB time > 180 min) were subjected to multivariate regression analysis. Long-term HD was identified as an independent predictor of VS (odds ratio, 2.29, 95% confidence interval, 1.66-3.18).

CONCLUSIONS

Longer term HD may be associated with a higher VS incidence after cardiac surgery. VS should be given attention after cardiac surgery in chronic HD-dependent patients.

Interaction between warfarin and short-term intravenous amiodarone in intensive care unit patients after cardiac surgery

Background

Amiodarone and warfarin are sometimes administered immediately after cardiac surgery. Although the interaction between long-term oral amiodarone and warfarin has been reported, the interaction between warfarin and short-term intravenous amiodarone has not been reported. In this study, we investigated the effect of short-term intravenous amiodarone on the anticoagulant effect of warfarin in patients who underwent cardiac surgery.

Methods

We retrospectively reviewed the medical records of 11 patients who received oral warfarin before and after cardiac surgery, and loading doses of 125–150 mg or a 750 mg continuous infusion of amiodarone, or both in the intensive care unit (ICU) within 5 days after the surgery between July 2011 and January 2017. The prothrombin time-international normalized ratio (PT-INR)/daily warfarin dose (PT-INR/dose) was used as an indicator of anticoagulant effect. The values before surgery were considered as the baseline.

Results

The PT-INR and PT-INR/dose values were elevated in 7 and 10 patients, respectively, after amiodarone administration. The mean PT-INR values were not significantly different before and after amiodarone administration (2.13 ± 0.58 vs 2.29 ± 0.50, respectively, p = 0.643). In contrast, the mean PT-INR/dose values were significantly elevated after the administration of amiodarone (0.93 ± 0.46 vs 1.54 ± 0.63, respectively, p = 0.002).

Conclusions

Short-term intravenous amiodarone enhanced the anticoagulant effect of warfarin in patients admitted to the ICU after cardiac surgery. We suggest that the dose of warfarin should be carefully adjusted for a few days after cardiac surgery if intravenous amiodarone is coadministered.

[Investigation of the outcomes and complications in right thoracotomy approach for mitral valve reoperation]

BACKGROUND

Right thoracotomy is an alternative surgical technique for mitral valve reoperation. The purpose of this study is to determine whether right thoracotomy for mitral valve reoperation affects its perioperative outcomes and complications.

METHODS

We investigated the perioperative events in consecutive mitral valve reoperations between January 2006 and November 2009. Demographic, intraoperative and postoperative data were collected and analyzed retrospectively.

RESULTS

Five right thoracotomy cases and 22 repeated sternotomy cases were included. Thoracotomy group needed more platelet transfusion (median, 20 units in thoracotomy; 10 units in sternotomy; P=0.047). We had a higher frequency of adrenaline administration (60% in thoracotomy; 4.6% in sternotomy; P=0.005) and needed more doses of dobutamine in thoracotomy group (median, 16.0 microg x kg(-1) x min(-1) in thoracotomy ; 7.5 microg x kg(-1) x min(-1) in sternotomy; P=0.037) to wean them from cardiopulmonary bypass. Right thoracotomy did not reduce cardiopulmonary bypass time (median, 265 min in thoracotomy ; 199 min in sternotomy; P=0.126). We experienced two serious complications requiring reoperation in thoracotomy group, but diagnosed them with intraoperative transesophageal echocardiography.

CONCLUSIONS

When we choose right thoracotomy for mitral valve reoperation, we should prepare more blood products and inotropic agents and should evaluate cardiac function by using intraoperative transesophageal echocardiography.

[Remifentanil prevents hyperglycemia and reduces insulin use during cardiopulmonary bypass in adult cardiac surgery]

BACKGROUND

Remifentanil may be beneficial in patients undergoing cardiac surgery, by attenuating the neurohumoral stress response to surgical stimulation and inflammation evoked by cardiopulmonary bypass (CPB).

METHODS

We retrospectively examined blood glucose monitored every 30 minutes during CPB and insulin dose in patients during CPB under remifentanil anesthesia (remifentanil group) and those under low dose fentanyl anesthesia (fentanyl group) in adult cardiac surgery. Furthermore we also investigated incidence of atrial fibrillation within 72 hours after surgery in both groups.

RESULTS

There were 35 patients in remifentanil group and 22 patients in fentanyl group. Although blood glucose at the beginning and the end of CPB in both groups were not different, remifentanil group showed lower maximum blood glucose (median 172 mg x dl(-1), interquatile range 156-205 mg x dl(-1)) during CPB than in fentanyl group (197 mg x dl(-1), 176-219 mg x dl(-1); P = 0.009). Significantly less insulin was administered during CPB in remifentanil group than in fentanyl group. Incidence of postoperative atrial fibrillation was similar between the groups.

CONCLUSIONS

Maximum blood glucose was lower and less insulin was administered during CPB in remifentanil group. These data may suggest that remifentanil reduce stress response to surgical stimulation in cardiac surgery.

[Perioperative management of living-donor liver transplantation in two patients with severe portopulmonary hypertension]

Liver transplantation for patients with severe portopulmonary hypertension (PPHTN) has been associated with high mortality. We conducted perioperative management of two patients with severe PPHTN for living-donor liver transplantation. The first case was a 17-year-old male with biliary atresia. He developed dyspnea at the age of 14, for which he was treated with intravenous epoprostenol for 8 months. As a result, the mean pulmonary artery pressure (MPAP) was reduced from 61 to 40 mmHg. Intraoperatively, he was treated with intravenous epoprostenol and nitric oxide (NO) inhalation. His intraoperative course was uneventful but he died from right heart failure on postoperative day (POD) 11. The second case was a 6-year-old girl with biliary atresia. When she was 5 years old, examination for a persistent cough revealed MPAP of 49 mmHg. Neither intravenous epoprostenol nor NO inhalation was effective, and she twice showed transient pulmonary hypertension during the operation. She was extubated 14 hours after the surgery, transferred out of ICU on POD 3 and discharged from the hospital on POD 99. When we compare the two cases, the factors responsible for the success of the management of the second case appear to be early extubation and the short duration of PPHTN.

Midazolam induces expression of c-Fos and EGR-1 by a non-GABAergic mechanism

Gene expression changes induced by general anesthetics have not been extensively examined. In this investigation, we treated rat pheochromocytoma PC12 cells with IV anesthetics, and assessed expression of immediate early gene products, c-Fos and EGR-1, by immunoblot analysis. Thiopental, ketamine, propofol, and diazepam did not significantly change the expression level of c-Fos and EGR-1. In contrast, midazolam dose- and time-dependently induced expression of c-Fos and EGR-1, which was not affected by antagonists of the benzodiazepine receptors, flumazenil and PK11195. The midazolam-induced c-Fos and EGR-1 expression was abolished by PD98059, an inhibitor for mitogen- activated protein kinase/extracellular signal-regulated kinase kinase, suggesting the involvement of extracellular signal-regulated kinases (ERKs). Immunoblot analysis demonstrated that midazolam induces phosphorylation and activation of ERKs. These results indicate that midazolam induces the expression of c-Fos and EGR-1, by activation of ERKs through a mechanism independent from gamma-aminobutyric acid(A) receptors, in PC12 cells, and suggest the possibility that midazolam can induce long-term changes of neural functions by changing gene expression.

IMPLICATIONS

Gene expression changes induced by anesthetics in neuronal cells have not been noticed. We demonstrate that a large concentration of midazolam can induce expression of immediate early genes by a non-GABAergic mechanism in PC12 cells, suggesting that the administration of midazolam might lead to long-term changes of neural functions by changing gene expression.

Activation of mu-opioid receptor induces expression of c-fos and junB via mitogen-activated protein kinase cascade

BACKGROUND

Opioid-induced long-term functional alterations of the nervous system, such as tolerance, addiction, and dependence, conceivably involve changes in gene expression. The authors have previously reported that opioid receptors are functionally coupled to extracellular signal-regulated kinase, a class of the mitogen-activated protein kinase. To address whether activation of the opioid receptor induces changes in gene expression through the activation of extracellular signal-regulated kinase, the authors examined mu-opioid receptor (MOR)-induced immediate early gene expression.

METHODS

Chinese hamster ovary cells stably expressing MOR were used. Cells were stimulated by MOR agonists after 24-h serum starvation. Expression of c-fos and junB genes was analyzed by RNA blot hybridization. To explore the mechanism of MOR-mediated c-fos and junB expression, activity of a transcription factor, Elk-1, was assessed by reporter assay. Furthermore, to investigate the functional consequences of c-fos and junB induction, MOR-mediated formation of the functional transcription factor complex AP-1 was examined by reporter assay and electrophoretic mobility shift assay.

RESULTS

Mu-opioid receptor activation induced c-fos and junB messenger RNAs, which were inhibited by pretreatment of the cells with pertussis toxin and PD98059, an inhibitor of extracellular signal-regulated kinase cascade. MOR stimulation elevated Elk-1-mediated transcriptional activity by about 10-fold. AP-1-mediated transcriptional activity was stimulated by MOR agonists by about twofold. Electrophoretic mobility shift assay revealed that AP-1 binding activity in the nuclear extract was elevated by MOR activation and further showed that products of c-fos and junB genes are involved in formation of AP-1 complex.

CONCLUSIONS

Mu-opioid receptor activation induces c-fos and junB expression and elevates AP-1-mediated transcriptional activities via the mitogen-activated protein kinase cascade.

Opioid potentiation of N-type Ca2+ channel currents via pertussis-toxin-sensitive G proteins in NG108-15 cells

Opioids have both inhibitory and stimulatory effects on neurotransmitter release. While the inhibitory effect has been ascribed to presynaptic inhibition of Ca2+ channels, the cellular mechanism underlying the stimulatory effect is not clear. In order to address this issue, we analyzed the effects of [d-Ala2, d-Leu5]-enkephalin (DADLE) on whole-cell Ba2+ currents (IBa) through voltage-gated Ca2+ channels in NG108-15 neuroblastoma x glioma hybrid cells. Application of DADLE inhibited and washout of DADLE transiently potentiated IBa. Furthermore, potentiation of IBa was elicited even in the presence of DADLE, when inhibition was relieved by a large depolarizing prepulse. DADLE-induced potentiation, as well as inhibition, had both voltage-sensitive and -insensitive components and was abolished by treatment with ICI174864, a delta-opioid antagonist, pertussis toxin (PTX) and omega-conotoxin GVIA. Potentiation developed over @3 min and took 5-20 min to recover, whereas inhibition was complete within 30 s and recovered within 1 min. Although this potentiation should contribute to DADLE-induced desensitization of Ca2+ channel inhibition, it was not the sole mechanism for desensitization. We conclude that the delta-opioid receptor exerts a dual action on N-type Ca2+ channels via PTX-sensitive G proteins, i.e., rapid inhibition followed by slowly developing potentiation.

The ultrastructural characteristics of eccrine sweat glands in a Fabry disease patient with hypohidrosis

As an investigation of the pathogenetic mechanism of diminished sweating in Fabry disease, an electron microscopy ultrastructural study was conducted on specimens of eccrine sweat glands from a typical patient with Fabry disease who had hypohidrosis, a low skin moisture content, and diminished thermoregulation ability. Numerous characteristic cytoplasmic inclusions were observed in the eccrine sweat glands, the lamellar pattern of which was considerably variable in various types of gland cells. Large vacuolar inclusions predominated in clear cells of secretory coil; lesser vacuoles were also seen in the coiled duct, and the basal cells of the straight duct toward the coiled duct displayed mulberry-like figures. There were some clear cells showing cell damage and necrosis in the secretory coil. Lamellated inclusions were noted in the unmyelinated axons innervating the eccrine sweat glands. The small blood vessels around the eccrine glands were narrowed by swollen endothelial cells with heavy inclusions. These intracytoplasmic deposits may be responsible for the decreased sweating ability in Fabry disease. The factors related to hypohidrosis are also discussed.

Activation of phospholipase A2 by the nociceptin receptor expressed in Chinese hamster ovary cells

To gain insight into the molecular mechanism for nociceptin function, functional coupling of the nociceptin receptor expressed in Chinese hamster ovary (CHO) cells with phospholipase A2 (PLA2) was examined. In the presence of A23187, a calcium ionophore, activation of the nociceptin receptor induced time- and dose-dependent release of arachidonate, which was abolished by pretreatment of the cells with pertussis toxin (PTX). Immunoblot analysis using anti-Ca2+-dependent cytosolic PLA2 (cPLA2) monoclonal antibody demonstrates that activation of the nociceptin receptor induces a time- and dose-dependent electrophoretic mobility shift of cPLA2, suggesting that phosphorylation of cPLA2 is induced by the nociceptin receptor. Pretreatment of the cells with PD98059, a specific mitogen-activated protein kinase/extracellular signal-regulated kinase kinase 1 inhibitor, or staurosporine, a potent inhibitor of serine/threonine protein kinases and tyrosine protein kinases, partially inhibited the nociceptin-induced cPLA2 phosphorylation and arachidonate release. These results indicate that the nociceptin receptor expressed in CHO cells couples with cPLA2 through the action of PTX-sensitive G proteins and suggest that cPLA2 is activated by phosphorylation induced by the nociceptin receptor via mechanisms partially dependent on p44 and p42 mitogen-activated protein kinases.

Partial agonistic activity of naloxone on the opioid receptors expressed from complementary deoxyribonucleic acids in Chinese hamster ovary cells

Naloxone is a widely used opioid antagonist. To analyze the cellular responses induced by naloxone in the absence of opioid agonists, Chinese hamster ovary (CHO) cells, which do not endogenously express the opioid receptors, have been permanently transfected with the cloned complementary DNAs to produce the mu-, delta-, and kappa-opioid receptors. Naloxone dose-dependently reduced forskolin-stimulated cyclic adenosine monophosphate (cAMP) formation in the cells expressing the mu- and kappa-opioid receptors, although the effect was less than that of opioid agonists [D-Ala2, N-Me-Phe4, Gly-ol5]enkephalin and U50,488, respectively. The naloxone-induced cAMP reduction was abolished by pretreatment of the cells with pertussis toxin, which suggests that pertussis toxin-sensitive G proteins (Gi and/or Go) are involved in the response. Cellular guanosine triphosphatase activity was significantly increased by naloxone in the cells expressing the mu- and kappa-opioid receptors, which suggests that the application of naloxone to these receptors induces activation of the G proteins. We conclude that naloxone possesses partial agonistic activity on the mu- and kappa-opioid receptors expressed from complementary DNAs in CHO cells.

IMPLICATIONS

In this study, we examined whether naloxone has agonistic activity on the opioid receptors by using cultured cells transfected with delta-, mu-, and kappa-opioid receptor complementary DNAs. Our data indicate that naloxone is a partial agonist on the mu- and kappa-opioid receptors.

Nociceptin receptor-mediated Ca2+ channel inhibition and its desensitization in NG108-15 cells

It has been shown that the membrane of hybrid NG108-15 neuroblastoma x glioma cells contains a high-affinity binding site for nociceptin. In the present study, we first demonstrated the expression of nociceptin receptor mRNA in NG108-15 cells. Application of nociceptin to NG108-15 cells produced a concentration-dependent (EC50 = 29 nM) inhibition of Ca2+ channel currents in a pertussis toxin-sensitive fashion. This nociceptin-induced inhibition of Ca2+ channel currents was prevented in the presence of omega-conotoxin GVIA, a blocker of the N-type Ca2+ channel, and had both voltage-dependent and -independent components. Prolonged application of nociceptin elicited homologous desensitization of the inhibition with a time constant of 5.3 min. These results indicate that the nociceptin receptor is coupled to the N-type Ca2+ channel via pertussis toxin-sensitive G proteins in NG108-15 cells and that this coupling is associated with rapid and homologous desensitization.

Tyrosine kinase inhibitors suppress N-type and T-type Ca2+ channel currents in NG108-15 cells

Modulation of Ca2+ channel activity by protein kinases constitutes one of the major mechanisms regulating neuronal functions. Here, we explored the possible modulation of neuronal Ca2+ channels by protein tyrosine kinases (PTKs). To this end, the effects of PTK inhibitors on whole-cell Ba2+ currents (IBa) through voltage-gated Ca2+ channels were analysed in differentiated NG108-15 neuroblastoma x glioma hybrid cells. Genistein suppressed IBa in a concentration-dependent fashion (IC50 = 22 microM). Although daidzein, an analogue of genistein that is devoid of PTK inhibitory activity, also suppressed IBa, we estimated that specific PTK inhibition by genistein reduced IBa amplitude by 30%. In addition, lavendustin A (20 microM) and herbimycin A (20 microM), two other distinct PTK inhibitors, depressed IBa by 22% and 20%, respectively. Genistein suppressed N-type and T-type currents, sparing L-type current, and its effect was independent of G protein activation. The results suggest that the activity of neuronal Ca2+ channels can be modulated by PTKs, opening the possibility that some of the functions of PTKs in the nervous system are mediated by Ca2+ channel modulation.

Adaptations to chronic agonist exposure of mu-opioid receptor-expressing Chinese hamster ovary cells

To investigate cellular adaptation responses induced by chronic agonist treatment of the mu-opioid receptor, Chinese hamster ovary (CHO) cells were stably transfected with the rat mu-opioid receptor cDNA. Chronic treatment with agonists selective for the mu-opioid receptor, [D-Ala2, N-MePhe4, Gy-ol5]enkephalin (DAMGO), morphine and fentanyl, time- and dose-dependently induced down-regulation of the mu-opioid receptor. The down-regulation was not significantly affected by pretreatment with pertussis toxin, but was completely blocked by treatment with hypertonic sucrose, suggesting that receptor internalization mediated by clathrin-coated vesicles is an essential step in the mu-opioid receptor down-regulation. On the other hand, forskolin-stimulated cyclic AMP formation was increased by chronic DAMGO treatment, which was inhibited by pertussis toxin pretreatment. These results indicate that two adaptation responses induced by chronic agonist treatment of the mu-opioid receptor-expressing CHO cells, down-regulation of the mu-opioid receptor and supersensitization of adenylate cyclase, are mediated by distinct mechanisms.

Desensitization and resensitization of delta-opioid receptor-mediated Ca2+ channel inhibition in NG108-15 cells

1. To approach the mechanisms underlying desensitization of the opioid receptor-mediated Ca2+ channel inhibition, the effects of prolonged application of [D-Ala2, D-Leu5]enkephalin (DADLE) on Ba2+ currents (I(Ba)) through Ca2+ channels were analysed in NG108-15 neuroblastoma x glioma hybrid cells. 2. Inhibition of I(Ba) by 100 nM DADLE desensitized by 57% with a time constant of 4.4 min. 3. Maximal desensitization of the delta-opioid receptor-Ca2+ channel coupling was attained by 1 microM DADLE. The EC50 value for desensitization was estimated to be 78 nM. 4. RNA blot hybridization analysis and immunoblot analysis revealed the expression of beta-adrenoceptor kinase-1 (betaARK1) in NG108-15 cells. 5. Heparin, an inhibitor of betaARK, significantly reduced the magnitude and rate of desensitization, whereas Rp-cyclic AMPS and PKI (14-24)amide, inhibitors of cyclic AMP-dependent protein kinase (PKA), or long-term treatment with phorbol 12-myristate 13-acetate to induce down-regulation of protein kinase C (PKC) had no significant effect. 6. Recovery from desensitization (resensitization) proceeded with a time constant of 6.7 min. Okadaic acid, an inhibitor of serine/threonine phosphatases 1 and 2A, significantly attenuated the degree of resensitization. 7. In summary, we have characterized the time course and concentration-dependence of the desensitization of DADLE-induced I(Ba) inhibition in NG108-15 cells. This desensitization was reversible after removal of DADLE. It is suggested that betaARK, but neither PKA nor PKC, is involved in desensitization, while serine/threonine phosphatases mediate resensitization.

Ca2+ channel inhibition by endomorphins via the cloned mu-opioid receptor expressed in NG108-15 cells

Endomorphin-1 and -2, recently isolated endogenous peptides specific for the mu-opioid receptor, inhibited Ca2+ channel currents with EC50 of 6 and 9 nM, respectively, in NG108-15 cells transformed to express the cloned rat mu-opioid receptor. On the other hand, they elicited no response in nontransfected NG108-15 cells. It is concluded that endomorphin-1 and -2 induce Ca2+ channel inhibition by selectively activating the mu-opioid receptor.

Acquired laryngomalacia as a cause of airway obstruction immediately after unilateral mouth floor surgery

We report a case of acquired laryngomalacia in which airway obstruction due to prolapse of the epiglottis during inspiration was observed immediately after a unilateral mouth floor resection. Suggested causes are resection of unilateral elevator muscles of the hyoid bone, epiglottic oedema and transient loss of pharyngeal motor control due to surgical intervention and high-dose radiation.

[A case report of prostate cancer resistant to endocrine therapy successfully treated with intra-arterial chemotherapy]

A 73-year-old male with low abdominal pain on urination and frequent urination was diagnosed as poorly differentiated adenocarcinoma of prostate. He received endocrine therapy with DESD and bilateral orchiectomy. This treatment was not effective, so he was given intra-arterial infusion chemotherapy with MTX, ADM and CDDP using the reservoir system. After 2 courses of this chemotherapy the regression rate was 75%, and the pathological examination after the chemotherapy revealed no cancer cells. There is no established chemotherapy for prostate cancer at present. Thus this case is very suggestive for the treatment of prostate cancer.

Oxygen embolism due to hydrogen peroxide irrigation during cervical spinal surgery

Hydrogen peroxide is used to cleanse and irrigate wounds. As it decomposes immediately into water and oxygen on contact with organic tissue, it is usually regarded as a safe agent. We report a case of oxygen embolism associated with hydrogen peroxide irrigation of the surgical field during anterior fusion of the cervical vertebrae. It was accompanied by precipitous hypotension and decrease in pulse oximetry oxygen saturation and end-tidal CO2 tension. Semi-closed spaces formed under the apatite dowel and between the apatite dowel and vertebral bodies may have precipitated the absorption of oxygen bubbles into the vasculature. Although this case was associated with a rapid recovery and uneventful sequelae, it discourages the use of hydrogen peroxide in this procedure because of the potential hazards including cardiovascular collapse.

Vaginal absorption of a potent luteinizing hormone-releasing hormone analogue (leuprolide) in rats. IV: Evaluation of the vaginal absorption and gonadotropin responses by radioimmunoassay

The vaginal absorption of leuprolide (a potent luteinizing hormone-releasing hormone analogue), which has the potential for producing regression of hormone-dependent tumors as well as high gonadotropin-releasing and ovulation-inducing activities, was evaluated in rats by radioimmunoassay. Gonadotropin (luteinizing hormone and follicle-stimulating hormone) release was concomitantly determined. Although leuprolide disappeared rapidly from the serum after intravenous administration (the biological half-lives were 8.4 min in the alpha-phase and 33.2 min in the beta-phase), long-lasting serum levels were observed when the analogue was administered vaginally. The vaginal absorption was enhanced by adding citric acid to the test solution. The absolute bioavailability, estimated by the AUC of serum leuprolide levels, was 25.8% over 6 h and 38.0% over 12 h in the 5% citric acid solution (pH 3.5). The sustained release of gonadotropin was also obtained after vaginal administration of the analogue. A linear dose absorption correlation of leuprolide was obtained in the range of 10-1000 micrograms/kg in an aqueous solution or methylcellulose jelly. The release of gonadotropin showed a plateau level at greater than 10 micrograms/kg, which corresponds to an effective dose for antitumor activity. The vaginal absorption of leuprolide varied with the estrous cycle, but this effect was eliminated by prior subcutaneous pretreatment with the analogue.

Desensitization of gonadotropin-releasing response following vaginal consecutive administration of leuprolide in rats

The vaginal absorption of a potent luteinizing hormone-releasing hormone analog (leuprolide), and the gonadotropins (luteinizing hormone and follicule-stimulating hormone)-releasing response after continuous vaginal and subcutaneous administration of the analog to rats were determined by the radioimmunoassay. A marked suppressive effect on the gonadotropin-releasing response along with long-lasting serum levels of leuprolide were paradoxically observed after consecutive 3-d vaginal administration of the analog at doses of 1 microgram/kg or greater. Pituitary function recovered progressively with cessation of the treatment but was not complete 4 d after cessation. Continuous vaginal and subcutaneous infusion resulted in an almost complete inhibition of both gonadotropins response. It is suggested that effective desensitization of the pituitary gonadotropin response is elicited by continuous administration of leuprolide and, therefore, the vaginal administration resulting in prolonged serum levels of the analog could be preferable as a self-administration method for medical treatments such as anti-tumor therapy and birth control.

Regression of rat mammary tumors by a potent luteinizing hormone-releasing hormone analogue (leuprolide) administered vaginally

Potent luteinizing hormone-releasing hormone analogues are known to cause regression of hormone-dependent mammary tumors. We have observed that high and long-lasting serum levels of a potent luteinizing hormone-releasing hormone analogue [desglycyl10-(D-leucyl6) luteinizing hormone-releasing hormone ethylamide, leuprolide] resulted from vaginal administration which effectively caused down regulation in the pituitary by chronic treatment. Regression of 7,12-dimethylbenz(a)-anthracene-induced mammary tumors in Sprague-Dawley rats by consecutive daily vaginal administration of leuprolide was investigated. In untreated rats, 71% of tumors were growing at 8 weeks, whereas after i.p. injection of leuprolide (500 micrograms/kg) all tumors were regressing 2 weeks after commencement of treatment and 86.7% of tumors disappeared by 8 weeks. Vaginal administration of 100 micrograms/kg for 8 weeks produced regression in 80% of tumors and disappearance in 35%. The vaginal administration of a higher dose (500 to 5000 micrograms/kg) produced highly significant antitumor effects [regression in 82.2 +/- 4.0% (S.E.) and disappearance in 52.9 +/- 2.1%]. These results are consistent with the effects produced by ovariectomy. Whereas 13 and 7 new tumors appeared in untreated rats and those treated vaginally with leuprolide (100 micrograms/kg), respectively, only one or two tumors appeared in i.p. and vaginally (above 500 micrograms/kg) treated rats during treatment. Histological classification of the mammary tumors after treatment indicated therapeutic effects similar to those shown by tumor size determination. Thus, it was concluded that vaginal application of leuprolide at doses above 500 micrograms/kg might be a potentially useful method for antitumor therapy.

Vaginal absorption of a potent luteinizing hormone-releasing hormone analogue (leuprolide) in rats III: Effect of estrous cycle on vaginal absorption of hydrophilic model compounds

The effect of estrous cycle stages on vaginal absorption was determined by the use of insulin, phenolsulfonphthalein, and salicylic acid as hydrophilic model compounds. Absorption of these compounds was markedly affected by the stage, possibly due to the change of transport rate through the pore-like pathways. The absorption of phenolsulfonphthalein during proestrus and estrus is roughly one-tenth of that during metestrus and diestrus. An increase of the nonionized form of salicylic acid, produced by a lowered pH, resulted in an enhancement of absorption during proestrus and diestrus; higher contribution of the transport through the cell membrane possibly reduced an effect of the estrous cycle. However, consecutive daily administration of leuprolide halted the cycle at diestrus and reduced the cycle effect on the vaginal absorption of phenolsulfonphthalein; when the treatment was started at any of the four stages of the cycle, vaginal absorption was enhanced approximately 20%, with less variance than that observed in normal diestrous rats.

Vaginal absorption of a potent luteinizing hormone-releasing hormone analogue (leuprolide) in rats II: mechanism of absorption enhancement with organic acids

Organic acids such as citric acid enhance the vaginal absorption of luteinizing hormone-releasing hormone, the potent analogue (leuprolide), and insulin. The mechanism of this absorption enhancement was investigated with leuprolide and hydrophilic markers such as phenol red and Evan's blue. The absorption of the analogue was increased by lowering the pH of the solution and increased more by adding citric, succinic, tartaric, and malonic acids. The absolute bioavailability after vaginal administration of the 5% citric acid solution was 16.7% at pH 3.5 and 38.4% at pH 1.8. The enhancing potency of the absorption correlated well with the chelating ability of the organic acids. The vaginal absorption of phenol red was also enhanced with citric acid and edetic acid, but the enhancing effect of edetic acid was eliminated by adding equimolar calcium ion. These results suggest that the acidifying and chelating abilities of the acids may result in a potent enhancement of the vaginal absorption of leuprolide. A leakage experiment using Evan's blue on the vaginal membrane indicated that the blood-vaginal epithelium barrier was loosened with the administration of citric acid; this change was overcome rapidly.

Vaginal absorption of a potent luteinizing hormone-releasing hormone analog (leuprolide) in rats I: absorption by various routes and absorption enhancement

The absorption of a potent luteinizing hormone-releasing hormone analog (leuprolide) through different routes was evaluated by determining the ovulation-inducing activity in diestrous rats. Vaginal administration showed the greatest potency among nonparenteral routes and was followed successively by rectal, nasal, and oral administration. Mixed micellar solution with monoolein-bile acids improved the intestinal absorption of leuprolide, and nasal absorption was enhanced by adding sodium glycocholate, surfactin, or polyoxyethylene 9 lauryl ether, but these bioavailabilities were still insufficient. The vaginal absorption was enhanced by organic acids: citric, succinic, tartaric, and glycocholic; the absolute bioavailability increased to approximately 20%. The vaginal absorption from jellies, as practical dosage forms, yielded sufficient activity of leuprolide, but absorption was slightly reduced with highly polar polymers or with higher concentrations of polymers. It was concluded that vaginal administration of leuprolide can be a rational dosage method for a long-term antitumor therapy.