Dissociation of the AhR/ARNT complex by TGF-β/Smad signaling represses CYP1A1 gene expression and inhibits benze[a]pyrene-mediated cytotoxicity

Cytochrome P450 1A1 (CYP1A1) catalyzes the metabolic activation of polycyclic aromatic hydrocarbons (PAHs) such as benzo[a]pyrene (B[a]P) and is transcriptionally regulated by the aryl hydrocarbon receptor (AhR)/AhR nuclear translocator (ARNT) complex upon exposure to PAHs. Accordingly, inhibition of CYP1A1 expression reduces production of carcinogens from PAHs. Although transcription of the CYP1A1 gene is known to be repressed by transforming growth factor-β (TGF-β), how TGF-β signaling is involved in the suppression of CYP1A1 gene expression has yet to be clarified. In this study, using mammalian cell lines, along with shRNA-mediated gene silencing, CRISPR/Cas9-based genome editing, and reporter gene and quantitative RT-PCR assays, we found that TGF-β signaling dissociates the B[a]P-mediated AhR/ARNT heteromeric complex. Among the examined Smads, Smad family member 3 (Smad3) strongly interacted with both AhR and ARNT via its MH2 domain. Moreover, hypoxia-inducible factor 1α (HIF-1α), which is stabilized upon TGF-β stimulation, also inhibited AhR/ARNT complex formation in the presence of B[a]P. Thus, TGF-β signaling negatively regulated the transcription of the CYP1A1 gene in at least two different ways. Of note, TGF-β abrogated DNA damage in B[a]P-exposed cells. We therefore conclude that TGF-β may protect cells against carcinogenesis because it inhibits CYP1A1-mediated metabolic activation of PAHs as part of its anti-tumorigenic activities.

PDZK1-interacting protein 1 (PDZK1IP1) traps Smad4 protein and suppresses transforming growth factor-β (TGF-β) signaling

Transforming growth factor (TGF)-β signaling in humans is stringently regulated to prevent excessive TGF-β signaling. In tumors, TGF-β signaling can both negatively and positively regulate tumorigenesis dependent on tumor type, but the reason for these opposite effects is unclear. TGF-β signaling is mainly mediated via the Smad-dependent pathway, and herein we found that PDZK1-interacting protein 1 (PDZK1IP1) interacts with Smad4. PDZK1IP1 inhibited both the TGF-β and the bone morphogenetic protein (BMP) pathways without affecting receptor-regulated Smad (R-Smad) phosphorylation. Rather than targeting R-Smad phosphorylation, PDZK1IP1 could interfere with TGF-β- and BMP-induced R-Smad/Smad4 complex formation. Of note, PDZK1IP1 retained Smad4 in the cytoplasm of TGF-β-stimulated cells. To pinpoint PDZK1IP1's functional domain, we created several PDZK1IP1 variants and found that its middle region, from Phe⁴⁰ to Ala⁴⁹, plays a key role in its Smad4-regulating activity. PDZK1IP1 knockdown enhanced the expression of the TGF-β target genes Smad7 and prostate transmembrane protein androgen-induced (TMEPAI) upon TGF-β stimulation. In contrast, PDZK1IP1 overexpression suppressed TGF-β-induced reporter activities, cell migration, and cell growth inhibition. In a xenograft tumor model in which TGF-β was previously shown to elicit tumor-promoting effects, PDZK1IP1 gain of function decreased tumor size and increased survival rates. Taken together, these findings indicate that PDZK1IP1 interacts with Smad4 and thereby suppresses the TGF-β signaling pathway.

TMED10 Protein Interferes with Transforming Growth Factor (TGF)-β Signaling by Disrupting TGF-β Receptor Complex Formation

The intensity and duration of TGF-β signaling determine the cellular biological response. How this is negatively regulated is not well understood. Here, we identified a novel negative regulator of TGF-β signaling, transmembrane p24-trafficking protein 10 (TMED10). TMED10 disrupts the complex formation between TGF-β type I (also termed ALK5) and type II receptors (TβRII). Misexpression studies revealed that TMED10 attenuated TGF-β-mediated signaling. A 20-amino acid-long region from Thr⁹¹ to Glu¹¹⁰ within the extracellular region of TMED10 was found to be crucial for TMED10 interaction with both ALK5 and TβRII. Synthetic peptides corresponding to this region inhibit both TGF-β-induced Smad2 phosphorylation and Smad-dependent transcriptional reporter activity. In a xenograft cancer model, where previously TGF-β was shown to elicit tumor-promoting effects, gain-of-function and loss-of-function studies for TMED10 revealed a decrease and increase in the tumor size, respectively. Thus, we determined herein that TMED10 expression levels are the key determinant for efficiency of TGF-β receptor complex formation and signaling.

C18 ORF1, a novel negative regulator of transforming growth factor-β signaling

Transforming growth factor (TGF)-β signaling is deliberately regulated at multiple steps in its pathway from the extracellular microenvironment to the nucleus. However, how TGF-β signaling is activated or attenuated is not fully understood. We recently identified transmembrane prostate androgen-induced RNA (TMEPAI), which is involved in a negative feedback loop of TGF-β signaling. When we searched for a family molecule(s) for TMEPAI, we found C18ORF1, which, like TMEPAI, possesses two PY motifs and one Smad-interacting motif (SIM) domain. As expected, C18ORF1 could block TGF-β signaling but not bone morphogenetic protein signaling. C18ORF1 bound to Smad2/3 via its SIM and competed with the Smad anchor for receptor activation for Smad2/3 binding to attenuate recruitment of Smad2/3 to the TGF-β type I receptor (also termed activin receptor-like kinase 5 (ALK5)), in a similar fashion to TMEPAI. Knockdown of C18ORF1 prolonged duration of TGF-β-induced Smad2 phosphorylation and concomitantly potentiated the expression of JunB, p21, and TMEPAI mRNAs induced by TGF-β. Consistently, TGF-β-induced cell migration was enhanced by the knockdown of C18ORF1. These results indicate that the inhibitory function of C18ORF1 on TGF-β signaling is similar to that of TMEPAI. However, in contrast to TMEPAI, C18ORF1 was not induced upon TGF-β signaling. Thus, we defined C18ORF1 as a surveillant of steady state TGF-β signaling, whereas TMEPAI might help C18ORF1 to inhibit TGF-β signaling in a coordinated manner when cells are stimulated with high levels of TGF-β.

Effect of paclitaxel on transient receptor potential vanilloid 1 in rat dorsal root ganglion

Peripheral neuropathy is a common adverse effect of paclitaxel treatment. To analyze the contribution of transient receptor potential vanilloid 1 (TRPV1) in the development of paclitaxel-induced thermal hyperalgesia, TRPV1 expression in the rat dorsal root ganglion (DRG) was analyzed after paclitaxel treatment. Behavioral assessment using the tail-flick test showed that intraperitoneal administration of 2 and 4 mg/kg paclitaxel induced thermal hyperalgesia after days 7, 14, and 21. Paclitaxel-induced thermal hyperalgesia after day 14 was significantly inhibited by the TRP antagonist ruthenium red (3 mg/kg, s.c.) and the TRPV1 antagonist capsazepine (30 mg/kg, s.c.). Paclitaxel (2 and 4 mg/kg) treatment increased the expression of TRPV1 mRNA and protein in DRG neurons. Immunohistochemistry showed that paclitaxel (4 mg/kg) treatment increased TRPV1 protein expression in small and medium DRG neurons 14 days after treatment. Antibody double labeling revealed that isolectin B4-positive small DRG neurons co-expressed TRPV1. TRPV1 immunostaining was up-regulated in paw skin day 14 after paclitaxel treatment. Moreover, in situ hybridization histochemistry revealed that most of the TRPV1 mRNA-labeled neurons in the DRG were small or medium in size. These results suggest that paclitaxel treatment increases TRPV1 expression in DRG neurons and may contribute to functional peripheral neuropathic pain.

Identification of amino acids in the pore region of Kv1.2 potassium channel that regulate its glycosylation and cell surface expression

The Kv1.4 potassium channel is reported to exhibit higher cell surface expression than the Kv1.1 potassium channel when expressed as a homomer in cell lines. Kv1.4 also shows highly efficient trans-Golgi glycosylation whereas Kv1.1 is not glycosylated. The surface expression and glycosylation of Kv1.2 is intermediate between those of Kv1.1 and Kv1.4. Amino acid determinants controlling the surface expression of Kv1 channels were localized to the highly conserved pore region and both positive and negative determinants of Kv1.1 and Kv1.4 trafficking have been reported. In this study, we analyzed the effect of substituting amino acids in the pore region of Kv1.2 with the corresponding amino acid present in Kv1.1 or Kv1.4 on glycosylation and trafficking of Kv1.2. Mutations in the outer pore region of Kv1.2 of Arg(354) to Pro (corresponding to Kv1.4) and to Ala (corresponding to Kv1.1) enhanced and reduced, respectively, cell surface expression of Kv1.2. Mutations in a different outer pore region of Val(381) to Lys (Kv1.4) and Tyr (Kv1.1) both reduced the cell surface expression. In contrast, mutation in the deep pore region of Ser(371) to Thr (Kv1.4) markedly enhanced cell surface expression. These results suggest that the cell surface expression of Kv1.2 is regulated by specific amino acids in the pore region in a similar manner to Kv1.1 and Kv1.4, and that the cell surface expression of Kv1.2, a channel intermediate between Kv1.1 and Kv1.4, can be attributed to these specific residues.

DNA sequencing and transcriptional analysis of the kasugamycin biosynthetic gene cluster from Streptomyces kasugaensis M338-M1

Streptomyces kasugaensis M338-M1 produces the aminoglycoside antibiotic kasugamycin (KSM). We previously cloned, sequenced and characterized the KSM acetyltransferase, transporter, and some of the biosynthetic genes from this strain. To identify other potential genes in a chromosome walk experiment, a 6.8-kb EcoRI-PstI region immediately downstream from the KSM transporter genes was sequenced. Five open reading frames (designated as kasN, kasO, kasP, kasQ, kasR) and the 5' region of kasA were found in this region. The genes are apparently co-transcribed as bicistrons, all of which are co-directional except for the kasPQ transcript. Homology analysis of the deduced products of kasN, kasP, kasQ and kasR revealed similarities with known enzymes: KasN, D-amino acid oxidase from Pseudomonas aeruginosa (35% identity); KasP, F420-dependent H4MPT reductase from Streptomyces lavendulae (33% identity); KasQ, UDP-N-acetylglucosamine 2-epimerase from Streptomyces verticillus (45% identity); and KasR, NDP-hexose 3,4-dehydratase from Streptomyces cyanogenus (38% identity); respectively. A gel retardation assay showed that KasT, a putative pathway-specific regulator for this gene cluster, bound to the upstream region of kasN and to the intergenic region of kasQ-kasR, suggesting that the expression of these operons is under the control of the regulator protein.

Destruxin E, a Cyclodepsipeptide Antibiotic, Reduces Cyclin D1 Levels and Inhibits Anchorage-Independent Growth of v-Ki-ras-Expressed pMAM-ras-REF Cells

Destruxin E (DE), a cyclodepsipeptide isolated from fermentation broths of Metarhizium sp. MA324, inhibited the growth of v-Ki-ras-expressed pMAM-ras-REF (rasREF) cells in the suspension (anchorage-independent) culture (a) more strongly than that in the substratum-attached (anchorage-dependent) culture (b) or that of v-Ki-ras-unexpressed pMAM-ras-REF (REF) cells in the substratum-attached culture (c); the IC(50) values of DE were 0.07 microM (a), 0.4 microM (b), and 1.2 microM (c). DE arrested G1 phase cell cycle progression of rasREF cells in the substratum-attached culture (b). In rasREF cells treated with DE for 72 h in suspension culture (a), the levels of cyclin D1, cyclin A, p27(Kip1), and hyperphosphorylated Rb were decreased, but the levels of cdk4, cdk6, cdk2, p16(INK4a), and p21(Cip1) were not affected. Among these effects, the decrease in cyclin D1 was prominent. DE decreased the level of cyclin D1 in rasREF cells in the suspension culture (a) at 0.1 microM and in the substratum-attached culture (b) at 1 microM, while the level of cyclin D1 in REF cells in the substratum-attached culture (c) was not decreased at 1 microM. The extent of growth inhibition correlated with the decrease in cyclin D1. The level of cyclin D1 mRNA of rasREF cells in the suspension culture (a) was also decreased by DE. DE decreased cyclin D1 mRNA, resulting in inhibition of anchorage-independent growth of rasREF cells.

kasT gene of Streptomyces kasugaensis M338-M1 encodes a DNA-binding protein which binds to intergenic region of kasU-kasJ in the kasugamycin biosynthesis gene cluster

We previously reported that a 4.2 kb SacI-EcoRI DNA region from Streptomyces kasugaensis M338-M1, a kasugamycin (KSM) producer, included KSM transporter genes (kasKLM). As an extension of that study, a 3.7 kb Psti-SacI DNA region, located at 1.5 approximately 5.2 kb upstream of kasK, was cloned and sequenced, revealing three complete open reading frames, designated kasT, kasU and kasJ. The kasJ gene encodes a protein (KasJ) with a conserved dinucleotide (FAD)-binding motif Homology search for KasJ showed its similarity to NADH: N-amidino-scyllo-inosamine oxidoreductase (StsB) which is involved in biosynthesis of the streptidine moiety of streptomycin (SM) in S. griseus. The kasT gene encodes a DNA-binding protein (KasT), including a helix-turn-helix motif near the center of the sequence. This protein is similar in structure to a pathway-specific activator protein (StrR) that plays a role in regulating the SM biosynthesis gene cluster of S. griseus. A fusion protein (Trx-KasT) clearly showed DNA binding activity with the intergenic region of kasU-kasJ, suggesting that KasT is a pathway-specific regulator of the KSM biosynthesis gene cluster.

Panepophenanthrin, from a mushroom strain, a novel inhibitor of the ubiquitin-activating enzyme

Screening for inhibitors of the ubiquitin-proteasome pathway, considered to regulate important cellular events and linked to serious diseases as well, led to isolation of a new compound, panepophenanthrin, from the fermented broth of a mushroom strain, Panus rudis Fr. IFO 8994. This is the first inhibitor of the ubiquitin-activating enzyme, which is indispensable for the ubiquitin-proteasome pathway. The structure of panepophenanthrin was determined by NMR and X-ray crystallographic analyses as 1,3a,10-trihydroxy-10c-(3-hydroxy-3-methylbut-1-enyl)-5,5-dimethyl-1,2,3,3a,5,5a,8,9,10,10a,10b,10c-dodecahydro-4-oxa-2,3,8,9-diepoxyacephenanthrylen-7-one.

Phenobarbital following phototherapy for Crigler-Najjar syndrome type II with good fetal outcome: a case report

In the presence of severe hyperbilirubinemia in Crigler-Najjar syndrome Type II, a fetus is at risk for kernicterus. A 34-year-old woman, gravida 4, para 1, with Crigler-Najjar syndrome Type II was treated with phenobarbital administration following phototherapy during each of 2 pregnancies. Both infants were healthy and developed normally.

Repetitive intermittent hypoxia-ischemia and brain damage in neonatal rats

OBJECTIVE

To know the effect of brief-repetitive intermittent hypoxia-ischemia on the development of perinatal brain damage.

STUDY DESIGN

Seven-day-old Wistar rats underwent ligation of the unilateral common carotid artery. The animals were allocated to three groups (n=12 in each group) and exposed to 8% oxygen as follows: group A: continuous exposure for 180 min; group B: continuous exposure for 90 min; and group C: 10 min of exposure repeated at 10-min intervals over a period of 180 min (total exposure time, 90 min). Seventy-two hours after exposure to hypoxia, the cerebral cortex was examined to assess the degree of neuronal necrosis and brain damage was classified into four grades of severity, 0-3. To evaluate the extent of brain damage, we used immunohistochemical staining with TIB-128 antibody, which reacts to MAC-1 antigen specific to microglia, and observed the glial reaction in the cerebral cortex, hippocampus, thalamus, and striatum.

RESULTS

All the brain damage observed in groups A-C occurred on the side where the ligation was performed. The most severe damage was found in group A animals, of which seven showed significant neuronal necrosis, having a grade 2 or more advanced lesion. In group B, neuronal necrosis was modest, with only one animal having a grade 2 lesion. In group C, a significant neuronal necrosis was found in six animals despite having the same period of hypoxic exposure as those in group B. MAC-1 positive cells appeared in the cerebral cortex of histologically damaged animals and extended to the hippocampus, thalamus, and striatum in severely damaged animals from groups A, B, and C.

CONCLUSION

Examination of the neonatal rat model suggested that repetitive and intermittent, rather than continuous hypoxia-ischemia, causes pronounced damage in the immature brain.

Immature brain injury via peroxynitrite production induced by inducible nitric oxide synthase after hypoxia-ischemia in rats

OBJECTIVE

To determine whether, and if so how, iNOS expresses and affects brain injury induced by hypoxia-ischemia in an immature brain.

MATERIAL AND METHODS

Seven-day-old Wistar rat pups were exposed to right common carotid artery ligation followed by 1.5 hours of hypoxia. The time course of iNOS mRNA expression, enzymatic activity, and protein production in the cerebral cortex were determined. The extent of the infarct area in the cerebral cortex and the production of 3-nitrotyrosine (a biomarker of peroxynitrite) were compared between the control pups and pups treated with S-methyl-isothiourea (a selective iNOS inhibitor).

RESULTS

In the cortex ipsilateral to carotid ligation, iNOS mRNA appeared from 6 hours to 24 hours after hypoxia-ischemia and disappeared at 48 hours. The iNOS protein and its activity also increased at 12 hours and reached a maximum level at 48 hours after the insult. The percentage of damage in the cerebral cortex was significantly higher in the control pups than in treated pups (31.9 vs 10.6%). Tri-nitrotyrosine following iNOS expression-positive cells were located predominantly at the infarct and peri-infarct regions.

CONCLUSIONS

iNOS expression might be an important determinant of ischemic immature brain injury.

The relationship between the response to external light stimulation and behavioral states in the human fetus: how it differs from vibroacoustic stimulation

OBJECTIVE

To determine the effects of external light stimulation on fetal behavioral states and know the difference from those of vibroacoustic stimulation.

METHODS

A flashlight and a vibroacoustic stimulator was applied directly on the maternal abdomen to determine the response of 56 normal fetuses at 36-40 weeks gestation. Fetal heart rate (FHR) and body movements were recorded using an actocardiograph, and fetal eye movements were observed using real-time ultrasonography. Using Nijhuis's criteria, the fetal behavioral states (1F-4F) were determined. FHR acceleration was considered a fetal response to the stimulations.

RESULTS

The lag time between stimulation and fetal response was within 4 s. A positive response rate to the light stimulation was higher at behavioral states 2F (82%) and 3F (83%) than at state 1F (4%). Light stimulation changed the behavioral state of two of the six 3F fetuses (33%) from 3F to 4F. No change of state was observed in fetuses that were in states 1F and 2F. For vibroacoustic stimulation, fetal response was 100% positive and changes of states were observed frequently irrespective of the behavioral state before the stimulation.

CONCLUSION

Fetal response to light stimulation is closely connected to fetal behavioral states and may reflect some distinct stages of the sleep-wakefulness cycle.

ABC transporter genes, kasKLM, responsible for self-resistance of a kasugamycin producer strain

We previously reported that a 7.6-kb DNA fragment from Streptomyces kasugaensis M338-M1, a kasugamycin (KSM) producer, included KSM acetyltransferase gene (kac338) and some other genes possibly involved in KSM biosynthesis. As an extension of that study, a 10-kb SacI-KpnI DNA fragment, located approximately 5-15-kb upstream of kac33, was cloned and a 4.2-kb SacI-EcoRI fragment therefrom was sequenced, revealing one incomplete (designated ORF J) and three complete open reading frames (designated kasK, kasL and kasM). The coding frames of kasK, L and M overlap one another with terminator/initiator ATGA sequence. RT-PCR analysis of a DNA region including kasKLM indicated the presence of one transcript that is long enough to span the three genes. The kasK gene potentially encodes an ATP-binding protein of the ATP-binding cassette (ABC) transporter superfamily. Homology search for the deduced KasK protein shows similarity to other ABC transporters involved in self-resistance of a mithramycin and possibly doxorubicin producer strain. The kasL and kasM genes encode different integral membrane proteins, both having six putative transmembrane helices. An expression plasmid for kasKLM (pTV-KLM) was constructed and these genes were expressed in E. coli JM 109, which had been sensitive to KSM. The transformant acquired resistance to KSM, suggesting that KasK, L and M proteins as a set in S. kasugaensis M338-M1 pump out KSM to protect the producer from its toxic metabolite.

Placenta previa increta penetrating the entire thickness of the uterine myometrium: ultrasonographic and magnetic resonance imaging findings

This is the first report of placenta previa increta in which the placenta villi penetrated the entire thickness of the uterine myometrium, but did not invade the pubocervical fascia. Ultrasonographic and magnetic resonance imaging findings are described.

Propofol does not affect the canine cardiac conduction system under autonomic blockade

PURPOSE

To determine the effects of propofol on the cardiac conduction system in dogs with pharmacological autonomic blockade.

METHODS

In eight mongrel dogs receiving 6 mg.kg-1.hr-1 propofol and vecuronium under pharmacological autonomic blockade with atropine and propranolol the infusion rates of propofol were increased from 6, (baseline), to 12, 18 and 24 mg.kg-1.hr-1 at 60-min intervals. An electrophysiological study assessed sinus rate, sinus node recovery time, corrected sinus node recovery time, intraatrial conduction time, AV nodal effective refractory period, Wenckebach cycle length and AV conduction times. Electrocardiographical variables and arterial pressures were also measured. All measurements were repeated at 30 min after the beginning of each infusion of propofol.

RESULTS

Propofol did not produce direct effects on the electrophysiological or electrocardiographical variables at any infusion rates. Heart rates did not change at higher infusion rates in the presence of decreases in arterial pressures.

CONCLUSION

Propofol did not affect the cardiac conduction system in the presence of autonomic blockade. Thus, the direct cardiac effects of propofol do not play a causative role in the genesis of propofol-associated bradyarrhythmias.

A 7.6kb DNA region from Streptomyces kasugaensis M338-M1 includes some genes responsible for kasugamycin biosynthesis

A 7.6kb PstI-KpnI DNA fragment including a sequence highly similar to kasugamycin acetyltransferase gene (kac) was isolated from Streptomyces kasugaensis M338-M1 and sequenced. Nine open reading frames (ORFs), designated as ORF A, B, C, D, E, F, G, H and I, were recognized in this region, although ORF A was incomplete. ORF G runs in the opposite direction to the others. The amino acid sequence deduced from ORF H showed 98% similarity to that of the kasugamycin acetyltransferase from S. kasugaensis MB273-C4, another kasugamycin (KSM) producer. Transformation of E. coli JM109 with ORF H made the strain highly resistant to KSM. The deduced amino acid sequences of the ORF A, C and D products were similar, respectively, to glucosyltransferase I from E. coli (26%), beta-alanine: pyruvate transaminase from Pseudomonas putida (32%) and dTDP-D-glucose 4,6-dehydratase (StrE) from Streptomyces griseus (37%). The strE-like ORF (ORF D) seems to be the gene responsible for formation of the 6-deoxy structure of the kasugamine moiety. ORF A and ORF C are also likely to have roles in KSM biosynthesis. Taken together, our analyses strongly suggest that this DNA region includes at least a part of the gene cluster of KSM biosynthesis.

Inhibition of anchorage-independent growth of tumor cells by IT-62-B, a new anthracycline

IT-62-B, a new anthracycline isolated from fermentation broths of Streptomyces sp. IT-62, reversed certain tumor cell phenotypes in vitro including some of human origin. The observed normal phenotypes were anchorage dependence of cell growth, flattened cell morphology and restoration of actin stress fibers. The extent of the anchorage dependence of cell growth induced by IT-62-B was generally greater than that by doxorubicin or pirarubicin. The cell-flattening effect of IT-62-B on cells of T24 (human bladder), but not on C-33A (human cervix), accompanied inhibition of fos gene expression. T24 cells, once flattened by IT-62-B, retained their flat morphology even in drug-free, fresh medium and eventually died in several days. IT-62-B, unlike doxorubicin, only slightly inhibited the topoisomerase II reaction in vitro and DNA synthesis in isolated cell nuclei.

Effects of magnesium sulphate on the cardiovascular system, coronary circulation and myocardial metabolism in anaesthetized dogs

We have studied the effects of i.v. bolus doses of magnesium sulphate (MgSO4) 60, 90 and 120 mg kg-1 on haemodynamic state, the coronary circulation and myocardial metabolism in nine dogs anaesthetized with pentobarbitone and fentanyl. MgSO4 produced dose-dependent decreases in arterial pressure, heart rate, left ventricular dP/dtmax and left ventricular minute work index (LVMWI) and an increase in the time constant of left ventricular isovolumic relaxation. Stroke volume increased, systemic vascular resistance decreased and cardiac output did not change significantly. MgSO4 produced decreases in coronary perfusion pressure, coronary vascular resistance and myocardial oxygen consumption (MVO2). Coronary sinus blood flow, lactate extraction ratio and the ratio of LVMWI to myocardial MVO2, that is an index of cardiac efficiency, did not change significantly. This study indicated that the depressant effect of MgSO4 on cardiac function was offset by lowering of peripheral vascular resistance, so that cardiac pump function remained effective, and the almost constant coronary sinus blood flow resulted from the decrease in coronary vascular resistance even at higher doses.

Ultrasonographic findings in the periventricular region in premature newborns with antenatal periventricular leukomalacia

Cranial ultrasonography was carried out at least three times a week during the first 16 days of life in all 53 premature newborns born within study period. If a cyst of more than three mm was detected in the periventricular region by fourteenth day of life, it was judged to be antenatal PVL. Periventricular echodensity was classified into mild, moderate or severe periventricular echodensity (PVE). Among 53 newborns, 11 babies (20.8%) were diagnosed as having antenatal PVL. Cysts were observed in the first two days in 9 cases (81.8%) out of 11 babies, and in bilateral periventricular regions in 8 cases (72.7%) out of 11 babies. All 3 babies with severe PVE in the periventricular region had PVL at the time of diagnosis or developed PVL shortely after severe PVE was detected.

Effects of magnesium sulphate on atrioventricular conduction times and surface electrocardiogram in dogs anaesthetized with sevoflurane

We have studied the effects of magnesium on atrioventricular (AV) conduction times and surface electrocardiogram during both sinus rhythm and atrial pacing in seven dogs anaesthetized with 1 MAC of sevoflurane. A bolus dose of magnesium sulphate (MgSO4) 30, 60 and 90 mg kg-1 significantly increased plasma magnesium concentrations from 1.3 (SEM 0.1) to 15.3 (1.3) mg dl-1. MgSO4 significantly prolonged A-H (AV nodal conduction time during sinus rhythm), St-H (intra-atrial and AV nodal conduction time during atrial pacing) and H-S (total ventricular conduction time) intervals at doses > or = 30 mg kg-1 ; H-V interval (His-Purkinje conduction time) at doses > or = 60 mg kg-1; RR and PR intervals and QRS duration at doses > or = 30 mg kg-1 in a dose-related manner during both sinus rhythm and atrial pacing. QTc interval remained unchanged during sinus rhythm. The doses of MgSO4 used did not have deleterious effects on AV conduction times and surface electrocardiogram during 1 MAC of sevoflurane anaesthesia. This finding suggests that MgSO4 in high doses was safe and may be indicated for cardiac arrhythmia and hypertension during sevoflurane anaesthesia. However, further study is required to apply these findings to clinical anaesthesia.

Atrioventricular conduction during adenosine-induced hypotension in dogs anaesthetized with sevoflurane

We have studied the effects of adenosine-induced hypotension on A-H interval (atrioventricular (AV) nodal conduction time during sinus rhythm), St-H interval (intra-atrial plus AV nodal conduction time during atrial pacing), H-V interval (His-Purkinje conduction time) and H-S interval (total ventricular conduction time) by His-bundle electrocardiography in addition to surface electrocardiogram during both sinus rhythm and atrial pacing in nine dogs anaesthetized with 1 MAC of sevoflurane. Stepwise increases in infusion rates of adenosine to 0.1, 0.3, 0.5 and 1.0 mg kg-1 min-1 produced a dose-related decrease in mean arterial pressure from 91 (6) to 38 (2) mm Hg. Adenosine significantly increased the A-H interval at infusion rates of 0.5 mg kg-1 min-1 and above, and the St-H interval at 1.0 mg kg-1 min-1. The H-V and H-S intervals remained unchanged. Heart rate decreased significantly only at 1.0 mg kg-1 min-1 with a significant increase in the PR interval. Adenosine-induced hypotension did not have deleterious effects on AV conduction times and the surface electrocardiogram in dogs anaesthetized with 1 MAC of sevoflurane. This may indicate that the effects of adenosine on AV conduction were small and therefore are unlikely to be a contraindication to the use of adenosine for inducing hypotension in patients with initially normal conduction during sevoflurane anaesthesia.

Hydroxymycotrienins A and B, new ansamycin group antibiotics

New ansamycins designated hydroxymycotrienins A and B were isolated from culture broths of Bacillus sp. BMJ958-62F4. The two antibiotics inhibited more strongly the growth of human cervical cancer cell lines of human papilloma virus (HPV) positive than that of HPV negative cell lines. The structures, some biological and biochemical properties are reported.

Airway management for patients with a tracheal bronchus

A tracheal bronchus is an aberrant, accessory or ectopic bronchus arising almost invariably from the right lateral wall of the trachea, causing hypoxaemia, atelectasis, or both, during anaesthesia. We describe two patients with a tracheal bronchus found before anaesthesia. One tracheal bronchus was found by tracheobronchoscopy and the other by chest x-ray. Because of recognition of the anomaly before operation, anaesthesia was uneventful in each patient.

[Anesthesia in a patient with history of multiple drug allergies]

A 38-year-old woman was admitted for intranasal ethmoidectomy. She had a history of serious anaphylactic reactions, including respiratory distress, hypotension and unconsciousness, to nonsteroidal anti-inflammatory drugs (Loxonin, Niflan) and antibiotics (Kefral, Minomycin). Preoperative intradermal skin tests against anesthesia-related drugs showed positive reactions to succinylcholine and vecuronium. After bilateral maxillary nerve block with 0.5 % bupivacaine (negative intradermal test) 3 ml, anesthesia was induced with diazepam, nitrous oxide, oxygen and sevoflurane. Trachea was intubated smoothly without muscle relaxants. Anesthesia was maintained with nitrous oxide, oxygen and sevoflurane 0.5-1 %. The anesthesia and postoperative course of this patient were uneventful. To confirm the initiation of allergic reaction to anesthetics used in the patient, serum histamine, tryptase, and complement 1, 3 and 4 factors were measured at 3 points: preoperatively, immediately after the induction, and after extubation. They showed normal levels. These results showed that no allergic reaction occurred perioperatively. In conclusion, the valuable information was provided for the choice of anesthetics by thorough evaluation of the past history and intradermal testing.

[Continuous epidural buprenorphine for postoperative pain relief after thoracotomy]

To evaluate postoperative analgesia and side effects of epidural buprenorphine, 60 patients after thoracotomy were divided into 6 groups. All patients received a bolus epidural administration of buprenorphine 0.1 mg in 8 ml of 0.25% bupivacaine. Following this epidural bolus, 10 patients in each group were given 0.25% bupivacaine alone (group A), buprenorphine 5 micrograms in 1 ml of 0.25% bupivacaine (group B), buprenorphine 8 micrograms in 1 ml of 0.25% bupivacaine (group C), buprenorphine 12 micrograms in 1 ml of 0.25% bupivacaine (group D), buprenorphine 15 micrograms in 1 ml of 0.25% bupivacaine (group E) or buprenorphine 18 micrograms in 1 ml of 0.25% bupivacaine (group F) with a portable disposable device at a rate of 1 ml.h-1 for 48 h. The percentages of patients who did not need additional narcotics for the first 24 hours postoperatively in group A, B, C, D, E, and F were 20%, 40%, 30%, 50%, 60%, and 70%, respectively. Those for the second 24 hours postoperatively in each group were 40%, 50%, 70%, 60%, 90%, and 90%, respectively. No significant difference in the incidence of side-effect was found among 6 groups. We concluded that optimal epidural doses of buprenorphine for post-thoracotomy pain relief are 15 and 18 micrograms.h-1 in the first and second 24 hours postoperatively, respectively.

[Meralgia paresthetica after spinal anesthesia]

A 27-year-old man underwent appendectomy under spinal anesthesia with 0.3% dibucaine 2.7 ml. The perioperative course was uneventful. The surgical procedure, however, lasted for 1.5 hours in the supine position. On the second postoperative day, a postspinal headache occurred and lasted for 18 days. On the seventh postoperative day the patient complained of numbness along the anterolateral aspect of the left thigh innervated by the lateral cutaneous nerve. There was no reflex or motor deficit indicative of the involvement of other nerves. The disorder was diagnosed as meralgia paresthetica caused by the surgical procedures. The numbness disappeared after the oral administration of mecobalamin in several days. In the treatment of a case like this, it is important to exclude neurological complications caused by spinal anesthesia.

[Serum nitroglycerin concentrations during extracorporeal circulation with a membrane oxygenator incorporated with a cardiopulmonary bypass circuit]

The effect of a cardiopulmonary bypass circuit (CPB) on serum nitroglycerin (TNG) concentrations was studied in eight patients scheduled for cardiac surgery. The CPB consisted of polyvinyl chloride tubes and polypropyrene membrane oxygenator. TNG was administered intravenously at a rate of 1 microgram.kg-1.min-1 after induction of anesthesia. Blood samples were obtained from the radial artery, central vein, venous inlet of the CPB, and arterial outlet of the CPB. No significant difference in serum TNG concentration was found between the venous inlet of the CPB and arterial outlet of the CPB. Serum TNG concentration tended to increase during complete extracorporeal circulation. This suggests that the hypothermic inhibition of TNG metabolism may be greater than the adsorption of TNG by the CPB.

[Spread of spinal anesthesia with 0.5% isobaric bupivacaine]

The effects of age, weight, height, weight.height ratio, and body mass index on the spread of spinal anesthesia with 3.0 ml of 0.5% isobaric bupivacaine was examined in 185 patients. No significant correlation was found between the spread of analgesia and the age, weight, height, weight.height ratio, or body mass index. A significant correlation was found between the decrease in mean arterial pressure and the height of sensory analgesia (rho = -0.21, P < 0.05) as well as the aging (rho = -0.35, P < 0.001).

Cloning and nucleotide sequencing of the antitumor antibiotic C-1027 apoprotein gene

The apoprotein gene for a chromoprotein antitumor antibiotic, C-1027, was cloned from the producer strain, Streptomyces globisporus C-1027, and sequenced. The process verified that; (1) the sequence included the entire structural gene directing a precursor of the apoprotein (pre-apoprotein having Met1---Ala33 leader peptide ahead of the apoprotein) and flanking regions, (2) the amino acid sequence of the apoprotein deduced from the base sequence perfectly matched the one based on protein analysis, (3) 3rd letters of the codons were 88% G or C, while the 1st plus the 2nd letters were 63% G or C, (4) the structural gene had 57% homology with that of macromomycin apoprotein (mcmA) while the flanking regions had little homology with the corresponding ones of mcmA, except some homology at the -10th and -35th promoter regions, and (5) the gene was transcribed as a monocistronic mRNA in an early growth phase, independent of chromophore production.

[Postoperative pain relief by continuous epidural infusion of bupivacaine and buprenorphine]

Continuous postoperative pain relief produced by epidural block with bupivacaine and buprenorphine was evaluated in 12 patients after thoracotomy, 19 patients after upper abdominal surgery, and 14 patients after lower abdominal surgery. Patients initially received 8 ml of 0.25% bupivacaine and 0.1 mg of buprenorphine at recovery room in operating theater and continuously received the mixture of 0.25% bupivacaine and 5 micrograms.ml-1 buprenorphine at a rate of 1 ml.h-1 using a portable pump. About fifty percent of the patients did not need additional narcotics during 48 postoperative hours. About ninety percent of the patients needed one additional narcotics during 48 postoperative hours. The authors conclude that epidural analgesia with the mixture of bupivacaine and buprenorphine produces satisfactory postoperative pain relief.