Loss of Ftsj1 perturbs codon-specific translation efficiency in the brain and is associated with X-linked intellectual disability

FtsJ RNA 2'-O-methyltransferase 1 (FTSJ1) gene has been implicated in X-linked intellectual disability (XLID), but the molecular pathogenesis is unknown. We show that Ftsj1 is responsible for 2'-O-methylation of 11 species of cytosolic transfer RNAs (tRNAs) at the anticodon region, and these modifications are abolished in Ftsj1 knockout (KO) mice and XLID patient-derived cells. Loss of 2'-O-methylation in Ftsj1 KO mouse selectively reduced the steady-state level of tRNA^Phe in the brain, resulting in a slow decoding at Phe codons. Ribosome profiling showed that translation efficiency is significantly reduced in a subset of genes that need to be efficiently translated to support synaptic organization and functions. Ftsj1 KO mice display immature synaptic morphology and aberrant synaptic plasticity, which are associated with anxiety-like and memory deficits. The data illuminate a fundamental role of tRNA modification in the brain through regulation of translation efficiency and provide mechanistic insights into FTSJ1-related XLID.

Determination of Minerals and Trace Elements in Milk, Milk Products, Infant Formula, and Adult Nutrition: Collaborative Study 2011.14 Method Modification

Official Method SM 2011.14/ISO 15151:2018/IDF 229:2018 uses microwave digestion of samples and inductively coupled plasma–atomic emission spectrometry for determination of nine elements, including Ca, Cu, Fe, K, Mg, Mn, Na, P, and Zn. The method was evaluated in a collaborative study of 25 products, including 13 fortified nutritional products (powders, ready-to-feed liquids, and liquid concentrates), five product placebos, six dairy products (liquids, powders, butter, and processed cheese), and the National Institute for Standards and Technology (NIST) Standard Reference Material (SRM) 1849a, in compliance with AOAC INTERNATIONAL Standard Method Performance Requirement (SMPR®) 2014.004. This study significantly expanded the applicability of Official Method 2011.14 beyond the original scope of chocolate milk powder, dietetic milk powder, infant cereal, peanut butter, and wheat gluten. The study included 14 collaborators from 11 countries, and results were compared to SMPR 2014.004. Accuracy of the method was demonstrated using NIST SRM 1849a, yielding recoveries across all laboratories of 98–101% for the nine elements. Precision for the 13 fortified nutritional product samples was 2.2–3.9% for repeatability (relative SD of repeatability) and 6.0–12.2% for reproducibility (RSDR). Excluding Mn, which was present at a wide range of concentrations, the reproducibility was 6.0–9.5%, meeting the performance requirements of SMPR 2014.004. Placebo samples (not fortified with Cu, Fe, Mn, or Zn) yielded acceptable repeatability of 1.8–2.9% for Ca, K, Mg, Na, and P (minerals) but 5.4–29.4% for the low levels of Cu, Fe, Mn, and Zn (trace elements). Reproducibility for the placebos showed the same pattern, with acceptable reproducibility (5.4–10.3%) for minerals but not for the low levels of the trace elements (13.2–82.8%). In the six dairy product samples, repeatability ranged from 1.6 to 3.6% for the minerals, Zn, and the low range of Mn but from 9.4 to 24.6% for Cu, Fe, and the high range of Mn, where concentrations were low as for the nutritional placebos. Reproducibility in the dairy samples was 5.3–8.8% for the minerals but 11.4–55.0% for the trace elements. The mean concentrations of Cu, Fe, and Zn in the dairy products were similar with those in the placebo products, while Zn was present at levels more similar with the fortified nutritional products. Thus, the method met the SMPR criteria except where the trace minerals were present at very low levels. Based on these results, the AOAC Stakeholder Panel for Infant Formula and Adult Nutritionals recommended Final Action status of the expanded applicability of the method. The method was adopted as Final Action by the AOAC Official Methods Board.

In utero gene therapy rescues microcephaly caused by Pqbp1-hypofunction in neural stem progenitor cells

Human mutations in PQBP1, a molecule involved in transcription and splicing, result in a reduced but architecturally normal brain. Examination of a conditional Pqbp1-knockout (cKO) mouse with microcephaly failed to reveal either abnormal centrosomes or mitotic spindles, increased neurogenesis from the neural stem progenitor cell (NSPC) pool or increased cell death in vivo. Instead, we observed an increase in the length of the cell cycle, particularly for the M phase in NSPCs. Corresponding to the developmental expression of Pqbp1, the stem cell pool in vivo was decreased at E10 and remained at a low level during neurogenesis (E15) in Pqbp1-cKO mice. The expression profiles of NSPCs derived from the cKO mouse revealed significant changes in gene groups that control the M phase, including anaphase-promoting complex genes, via aberrant transcription and RNA splicing. Exogenous Apc4, a hub protein in the network of affected genes, recovered the cell cycle, proliferation, and cell phenotypes of NSPCs caused by Pqbp1-cKO. These data reveal a mechanism of brain size control based on the simple reduction of the NSPC pool by cell cycle time elongation. Finally, we demonstrated that in utero gene therapy for Pqbp1-cKO mice by intraperitoneal injection of the PQBP1-AAV vector at E10 successfully rescued microcephaly with preserved cortical structures and improved behavioral abnormalities in Pqbp1-cKO mice, opening a new strategy for treating this intractable developmental disorder.

SnoN: bridging neurobiology and cancer biology

The transcriptional regulator SnoN has been the subject of growing interest due to its diverse functions in normal and pathological settings. A large body of evidence has established a fundamental role for SnoN as a modulator of signaling and responses by the transforming growth beta (TGFbeta) family of cytokines, though how SnoN regulates TGFbeta responses remains incompletely understood. In accordance with the critical and complex roles of TGFbeta in tumorigenesis and metastasis, SnoN may act as a tumor promoter or suppressor depending on the stage and type of cancer. Beyond its role in cancer, SnoN has also been implicated in the control of axon morphogenesis in postmitotic neurons in the mammalian brain. Remarkably, signaling pathways that control SnoN functions in the divergent cycling cells and postmitotic neurons appear to be conserved. Identification of novel SnoN regulatory and effector mechanisms holds the promise of advances at the interface of cancer biology and neurobiology.

Pressure-induced denaturation of monomer beta-lactoglobulin is partially irreversible: comparison of monomer form (highly acidic pH) with dimer form (neutral pH)

This study was conducted to assess the effect of high hydrostatic pressure on monomer beta-lactoglobulin (BLg) at acid pH by fluorescence spectroscopy under pressure and by circular dichroism (CD) and (1)H NMR spectroscopies after release of pressure. The intrinsic (tryptophan) fluorescence measurement and the study of 8-anilinonaphthalene-1-sulfonate (ANS) binding to BLg indicated that at pH 2.0 the recovery of center of spectral mass or ANS fluorescence was almost complete upon pressure release. No difference in (1)H NMR spectra was observed between pressurized and unpressurized BLg. In addition, NMR detection of the H/D exchange of aromatic protein indicated that the conformation of the vicinity of tryptophan residues could be refolded almost completely after release of pressure. These results seemingly confirm that the pressure-induced denaturation of BLg at pH 2.0 is reversible. However, cis-parinaric acid binding ability of pressurized BLg was largely lost, although its retinol binding ability was the same as its unpressurized one. Furthermore, CD spectra of the far-UV region and 2D NMR spectra evidently revealed the difference in the conformation of the molecule between unpressurized and pressurized BLg. These results are interpreted as an existence of partially fragile structure in the BLg molecule by high pressure.

S-myotrophin promotes the hypertrophy of myotube as insulin-like growth factor-I does

We have reported previously that a novel muscle cell growth factor, having a structure of a peptide with sugar chains, was successfully purified from porcine skeletal muscle. It was named s-myotrophin. To determine the role of s-myotrophin in skeletal muscle growth, the effect of s-myotrophin on primary cultured chick skeletal muscle cells (composed almost totally of multinucleated myotubes) was investigated by comparing s-myotrophin with Insulin-like growth factor-I (IGF-I). Both s-myotrophin and IGF-I significantly increased creatine kinase activity of the cultures; both substances gave similar responses. Intracellar protein content was also increased by the addition of these factors. The content of myosin and actin in s-myotrophin treated culture in the differentiation medium was significantly higher than that of the control (unstimulated). The content of those proteins in IGF-I treated culture was also higher than that of control, but the differences were not statistically significant. Immunoblot analysis confirmed that the amounts of myosin and actin in the myocytes were greatly increased by s-myotrophin stimulation and also by IGF-I stimulation. Morphological observations using an anti-desmin antibody staining procedure demonstrated that the size of both s-myotrophin and IGF-I treated myotubes was appreciably larger than that of control myotubes. These results suggest that s-myotrophin is a potent mediator of skeletal muscle cell hypertrophy thorough the accumulations of muscle structural proteins.

Promotion of radiation-induced formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine by nitro 5-deazaflavin derivatives

6-Nitro- and 8-nitro-5-deazaflavin derivatives have been found to enhance prominently the radiation-induced formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) at the expense of formation of 2,6-diamino-4-hydroxy-5-formamidopyrimidine nucleosides (FapydGuo) both in deaerated and in N(2)O saturated aqueous 2'-deoxyguanosine solutions. The radiosensitizing capacity of a 9-nitro-5-deazflavin derivative was observed only in the N(2)O saturated aqueous solutions.

The effects of prolonged low-flow sevoflurane anesthesia on renal and hepatic function

We assessed the effects of prolonged low-flow sevoflurane anesthesia on renal and hepatic functions by comparing high-flow sevoflurane with low-flow isoflurane anesthesia. Thirty patients scheduled for surgery of > or =10 h in duration randomly received either low-flow (1 L/min) sevoflurane anesthesia (n = 10), high-flow (6-10 L/min) sevoflurane anesthesia (n = 10), or low-flow (1 L/min) isoflurane anesthesia (n = 10). We measured the circuit concentrations of Compound A and serum fluoride. Renal function was assessed by blood urea nitrogen, serum creatinine, creatinine clearance, and urinary excretion of glucose, albumin, protein, and N:-acetyl-beta-D-glucosaminidase. The hepatic function was assessed by serum aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, alkaline phosphatase, and total bilirubin. Compound A exposure was 277 +/- 120 (135-478) ppm-h (mean +/- SD [range]) in the low-flow sevoflurane anesthesia. The maximum concentration of serum fluoride was 53.6 +/- 5.3 (43.4-59.3) micromol/L for the low-flow sevoflurane anesthesia, 47.1 +/- 21.2 (21.4-82.3) micromol/L for the high-flow sevoflurane anesthesia, and 7.4 +/- 3.2 (3.2-14.0) micromol/L for the low-flow isoflurane anesthesia. Blood urea nitrogen and serum creatinine were within the normal range, and creatinine clearance did not decrease throughout the study period in any group. Urinary excretion of glucose, albumin, protein, and N:-acetyl-beta-D-glucosaminidase increased after anesthesia in all groups, but no significant differences were seen among the three groups at any time point after anesthesia. Lactate dehydrogenase and alkaline phosphatase on postanesthesia Day 1 were higher in the high-flow sevoflurane group than in the low-flow sevoflurane group. However, there were no significant differences in any other hepatic function tests among the groups. We conclude that prolonged low-flow sevoflurane anesthesia has the same effect on renal and hepatic functions as high-flow sevoflurane and low-flow isoflurane anesthesia.

IMPLICATIONS

During low-flow sevoflurane anesthesia, intake of Compound A reached 277 +/- 120 ppm-h, but the effect on the kidney and the liver was the same in high-flow sevoflurane and low-flow isoflurane anesthesia.

Synthesis and antitumor activities of novel 5-deazaflavin-sialic acid conjugate molecules

6-Nitro-5-deazaflavin derivatives bearing O-(methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero-alpha- and beta-D-galacto-non-2-ulopyranosylonate)alkyl group (sialosylalkyl group) at N(3) or N(10) and 8-amino-5-deazaflavin substituted with the sialosylalkyl group at the amino group were synthesized and their physicochemical properties as well as antitumor effects on KB and L1210 cells have been investigated. The configurations of the glycosides were determined by 1H NMR and rate of hydrolysis of the glycosidic bond. It has been found that these conjugate molecules show significant antitumor activities. Combination of an 8-amino-5-deazaflavin with the sialosylalkyl group have been found to give rise to significant increase in antitumor activities of the compound. Antitumor effects of 6-nitro-5-deazaflavin-sialic acid conjugate molecules were similar or rather weak in comparison with those of the 6-nitro-5-deazaflavin derivatives without sialosylalkyl group.

Quantification of the degradation products of sevoflurane using four brands of CO 2 absorbent in a standard anesthetic circuit

PURPOSE

CO(2) absorbents convert sevoflurane to fluoromethyl-2,2-difluoro-1-(trifluoromethyl) vinyl ether (compound A), whose toxicity in rats raises concern regarding the safety of sevoflurane in a low-flow system. The type of CO(2) absorbent is one of factors that affect compound A concentration in the anesthetic circuit. The aim of the present study was to investigate the concentration of compound A in an anesthetic model circuit following the use of different brands of soda lime and Baralyme.

METHODS

We measured the concentrations of compound A in four different brands of CO(2) absorbent using a low-flow (1 l.min(-1) fresh gas) model circuit in which 2% sevoflurane was circulated. Sodasorb II, Baralyme, Sofnolime and Wakolime-A were used as CO(2) absorbents. The concentration of compound A was measured hourly, and the temperature of the CO(2) absorbent was monitored.

RESULTS

The maximum concentration of compound A in the circuit was highest for Baralyme (25.5 +/- 0.6 ppm) (mean +/- SD), followed by Sodasorb II (18.9 +/- 1.6 ppm), Wakolime-A (16.1 +/- 0.7 ppm), and Sofnolime (15.8 +/- 1.4 ppm). The maximum temperature was 50.8 +/- 1.3 degrees C for Baralyme, 48.8 +/- 1.3 degrees C for Wakolime-A, 47.0 +/- 1.4 degrees C for Sodasorb II, and 43.5 +/- 3.9 degrees C for Sofnolime.

CONCLUSION

The relative concentrations of compound A in the low-flow circuit were Baralyme > Sodasorb II > Wakolime-A = Sofnolime.

Excitatory cortical inputs to pallidal neurons via the subthalamic nucleus in the monkey

How the motor-related cortical areas modulate the activity of the output nuclei of the basal ganglia is an important issue for understanding the mechanisms of motor control by the basal ganglia. In the present study, by using awake monkeys, the polysynaptic effects of electrical stimulation in the forelimb regions of the primary motor and primary somatosensory cortices on the activity of globus pallidus (GP) neurons, especially mediated by the subthalamic nucleus (STN), have been characterized. Cortical stimulation induced an early, short-latency excitation followed by an inhibition and a late excitation in neurons of both the external and internal segments of the GP. It also induced an early, short-latency excitation followed by a late excitation and an inhibition in STN neurons. The early excitation in STN neurons preceded that in GP neurons. Blockade of STN neuronal activity by muscimol (GABA(A) receptor agonist) injection resulted in abolishment of both the early and late excitations evoked in GP neurons by cortical stimulation. At the same time, the spontaneous discharge rate of GP neurons decreased, pauses between the groups of spikes of GP neurons became prominent, and the firing pattern became regular. Injection of (+/-)-3-(2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP) [N-methyl-D-aspartate (NMDA) receptor antagonist], but not 1,2,3, 4-tetrahydro-6-nitro-2,3-dioxo-benzo[f]quinoxaline-7-sulfonamide disodium [NBQX (non-NMDA receptor antagonist)], into the STN attenuated the early and late excitations in GP neurons, suggesting that cortico-subthalamic transmission is mediated mainly by NMDA receptors. Interference with the pallido-subthalamic transmission by bicuculline (GABA(A) receptor antagonist) injection into the STN made the inhibition distinct without affecting the early excitation. The present results indicate that the cortico-subthalamo-pallidal pathway conveys powerful excitatory effects from the motor-related cortical areas to the GP with shorter conduction time than the effects conveyed through the striatum.

A cortical motor region that represents the cutaneous back muscles in the macaque monkey

A cortical motor region that represented the cutaneous muscles on the back was identified on the medial wall of the frontal lobe in the macaque monkey. In this region, neurons responded to somatosensory stimuli such as light touch or squeezing of the back skin, and intracortical microstimulation elicited contraction of the back skin. Such a region was located primarily on the dorsal bank of the cingulate sulcus, corresponding to the dorsal cingulate motor area.

Anthropogenic radionuclides in seawater of the Far Eastern Seas

Large quantities of radioactive wastes have been dumped in the Far Eastern Seas by the former Soviet Union and the Russian Federation, and small amounts of radioactive wastes have been dumped by Japan and the Republic of Korea. In order to investigate the concentrations of anthropogenic radionuclides in the nine dumping areas, a second expedition was conducted in 1995 by Japan, the Republic of Korea, the Russian Federation and IAEA, following the first expedition in 1994. The results show that 137Cs, 90Sr and 239 + 240Pu concentrations in surface and bottom waters at dumping areas do not significantly differ from the values observed in background areas, and from historical values. There is no clear effect of possible contamination due to radioactive waste dumping. The concentrations and water column inventories of 137Cs, 90Sr and 239 + 240Pu in the Far Eastern seas are controlled by physical oceanic processes such as horizontal transport and biogeochemical processes such as scavenging.

Marine radioactivity assessment of Mururoa and Fangataufa atolls

The International Atomic Energy Agency (IAEA) carried out an international project. 'The Study of the Radiological Situation at the Atolls of Mururoa and Fangataufa' with the aim of assessing the present and future radiological situation at the atolls and making recommendations for either monitoring or remedial actions if they are deemed necessary. The paper concentrates on marine radioactivity aspects and gives an estimation of present radionuclide concentrations in water, sediment and biota of the Mururoa and Fangataufa lagoons and the surrounding ocean. The dominant radionuclide in both lagoons is Pu in sediments (the total inventory is approximately 30 TBq). A decline in radionuclide concentrations has been observed in recent years in lagoon water, with the exception of 3H and 90Sr, for which a contribution from underground sources is to be expected. Radionuclide concentrations in biota from the lagoons and the surrounding ocean are low and consistent with previous measurements. The observed radionuclide concentrations in both lagoons imply that no radiological risk exists for hypothetical inhabitants of Mururoa and Fangataufa Atolls.

Radionuclide concentrations in underground waters of Mururoa and Fangataufa Atolls

In 1997 an expedition to Mururoa and Fangataufa Atolls was carried out to sample underground waters from cavity-chimneys and carbonate monitoring wells. The aim of this study was to determine the prevailing concentration and distribution status of radionuclides. Elemental analysis of interstitial waters was carried out in the water fraction as well as in particles collected at 11 underground monitoring wells. 238Pu, 239,240Pu, 241Am, 137Cs, 90Sr, 3H, 125Sb, 155Eu and 60Co were analyzed in both fractions by alpha-, beta- and gamma-spectrometry. Measurements showed that at 60% of the sites, pH and Eh seemed to be related to tidal cycles; in contrast HTO was constant during the sampling time. Interstitial waters from carbonates and transition zones shared similar chemical composition that were not different from that of the surrounding seawater. Waters collected from basalt cavities left after nuclear tests, (Aristee and Ceto) have a different chemical signature characterized by a deficiency in Mg, K and SO4 as well as enrichment in Sr, Si, Al and Cl compared to the rest of the stations. Radionuclide concentrations present in both, water and particulate fractions, were significantly higher at Ceto and Aristee than at any other monitoring wells, except for Fuseau and Mitre monitoring wells (Fangataufa) where values similar to Ceto were found (e.g. 239,240Pu: > 20 mBq g-1). Considering that Pu isotopes showed high Kd values compared to non-sorbing radionuclides such as 3H, 90Sr and 137Cs it is very unlikely that migration from cavities to monitoring wells accounts for the concentration of Pu isotopes and Am at Fuseau 30 and Mitre 27. Perhaps the contact of lagoon waters with the well before sealing could be a possible source of the transuranics found at these sites. The 238Pu/239,240Pu ratios measured in the particles were similar to that of the lagoon (0.38), thus supporting this hypothesis. The fact that transuranics were found only in the particle fraction, in the water (colloids included) these radionuclides were below detection limits, may be accounted for the conspicuous quantity of iron oxy-hydroxides present in the particulate fraction that under the appropriate redox conditions may be interacting selectively with elements in solution (scavenging) resulting in the enhanced transuranic signal. While transuranics have been found in places of their origin, radionuclides with low Kd values (3H, 90Sr, 137Cs) have already been transported to monitoring wells, as well as to the atolls' lagoons and the open ocean.

Formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine under anaerobic conditions by reductively activated nitro 5-deazaflavin derivatives

Electrolytically reduced 6- and 8-nitro-5-deazaflavin derivatives have been found to interact to react specifically with guanine base by means of cyclic voltammetry. Electrolytic reductions of 6- and 8-nitro-5-deazaflavin derivatives in the presence of the 2'-deoxyguanosine under anaerobic conditions resulted in prominent formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine.

Rough surfaced smooth endoplasmic reticulum in rat and mouse cerebellar Purkinje cells visualized by quick-freezing techniques

The in vivo structure of the smooth endoplasmic reticulum (ER) was visualized in rat and mouse cerebellar Purkinje cells by using quick-freezing techniques followed by freeze-substitution for ultrathin-sectioning or freeze-fracturing and deep-etching for replicas. High magnification electron microscopy of the ultrathin sections revealed a surprising finding that all the smooth ER are apparently rough surfaced, and heavily studded with a large number of small dense projections. In the soma the smooth ER appears to be similar to its rough counterpart, except that the projections are slightly smaller, less electron dense and less protrusive on the ER membranes than the ribosomes. The projections were short rectangles, 20 x 20 x 6 nm3 in size, covering the cytoplasmic surface of the smooth ER in a checker-board manner where closely packed. After freeze-etching and replication, they appeared to be composed of four subparticles, surrounding a central channel. Thus the projections are very similar to the foot structure (ryanodine receptor) of the sarcoplasmic reticulum. Furthermore, they were distributed exclusively in the ER compartment and were highly concentrated especially in the smooth ER. This localization of the projections coindides with the intracellular distribution of the inositol 1,4,5-trisphosphate (IP3) receptor determined by quantitative immunogold electron microscopy. These findings would suggest that the projections are tetramers of IP3 receptor molecules and could be used as a morphological marker for the smooth ER in Purkinje cells, which spreads from the soma to the axon and dendrite, up to the tips including the spines. In Purkinje cells tubular smooth ER runs freely in a serpentine fashion or are intertwined to make large membraneous tangles without forming cisternal stacks. It is highly probable that the ER cisternal stacks do not exist naturally in Purkinje cells but are formed artificially during the various procedures for chemical fixation.

The enhancing of a cysteine proteinase activity at acidic pH by protein engineering, the role of glutamic 50 in the enzyme mechanism of caricain

Carica papaya produces four cysteine proteinases. Calculations show that the Cys25, His159 essential ion pair is fully ionised at pH 2.99, where activity cannot be detected, but apparently an additional ionisation with a pKa of 4 is essential for activity (an electrostatic switch). Caricain (EC 3.4.22.30) wt and D158E genetic backgrounds were used to study the contribution of E50A to activity. E50 or E135 are candidates for the switch, E50A would be expected to reduce activity. However, activity increased at pH 5.0 in both backgrounds and at the pH optimum in D158E E50A but decreased slightly in the wt background. This challenges the hypothesis of an electrostatic switch.

A modified microsyringe for extracellular recording of neuronal activity

We describe a modified Hamilton microsyringe that allows extracellular recording of neuronal activity and subsequent injections. It is assembled with a Hamilton removable needle and a syringe for injection, a Teflon-coated tungsten wire for recording, and polyimide tubing as a sheath. The device is inexpensive and easy to handle in anatomical and physiological experiments in awake monkeys.

Synthesis and evaluation of nitro 5-deazaflavin-pyrrolecarboxamide(s) hybrid molecules as novel DNA targeted bioreductive antitumor agents

A series of 6-nitro-5-deazaflavins bearing at N(3) or N(10) position the pyrrolecarboxamide(s) group as DNA minor groove binder has been synthesized. These hybrid molecules show similar redox properties to those of 6-nitro-5-deazaflavins with no pyrrolecarboxamide(s) group, suggesting that they generate stable one- and two-electron reduction product(s). Electrolytic reductions of the hybrid molecules were carried out at a controlled potential under anaerobic conditions in the presence of plasmid pBR322 DNA. Significant conversions of the supercoiled circular pBR322 DNA (form I) to the open circular DNA (form II) have been found by treatment with the reductively activated 6-nitro-5-deazaflavin derivatives. Their DNA damaging effects have been found to be enhanced as the number of pyrrolecarboxamide group as the DNA binder increases. Antitumor activities of the hybrid molecules towards KB and L1210 cells were evaluated in vitro. It has been found that the antitumor effects of the compounds on KB cells slightly change and those on L1210 cells decrease as the number of the pyrrolecarboxamide group increases. These results reveal that the combination of 6-nitro-5-deazaflavin molecule with the pyrrolecarboxamide(s) group increase the DNA binding properties of the compounds, giving rise to promoted DNA damaging effects, and also suggest that the combination would affect the capacity of the compounds to act as the substrate for intracellular reductases and/or the cellular uptake of the compounds.

Effects of the water content of soda lime on compound A concentration in the anesthesia circuit in sevoflurane anesthesia

BACKGROUND

Sevoflurane anesthesia is usually performed with fresh gas flow rates greater than 2 l/min due to the toxicity of compound A in rats and limited clinical experience with sevoflurane in low-flow systems. However, to reduce costs, it would be useful to identify ways to reduce compound A concentrations in low-flow sevoflurane anesthesia. This goal of this study was to determine if compound A concentrations can be reduced by using soda lime with water added.

METHODS

Low-flow sevoflurane anesthesia (fresh gas flow of 1 l/min) was performed in 37 patients using soda lime with water added (perhydrated soda lime) or standard soda lime as the carbon dioxide (CO2) absorbent. The soda lime was not changed between patients, but rather was used until CO2 rebreathing occurred. The perhydrated soda lime was prepared by spraying 100 ml distilled water onto 1 kg fresh soda lime, and water was added only when a new bag of soda lime was placed into the canister. Compound A concentrations in the circle system, soda lime temperatures, inspired and end-tidal CO2 and end-tidal sevoflurane concentrations, and CO2 elimination by the patient were measured during anesthesia.

RESULTS

Compound A concentrations were significantly lower for the perhydrated soda lime (1.9 +/- 1.8 ppm; means +/- SD) than for the standard soda lime (13.9 +/- 8.2 ppm). No differences were seen between the two types of soda lime with regard to the temperature of the soda lime, end-tidal sevoflurane concentrations, or CO2 elimination. Compound A concentration decreased with the total time of soda lime use for both types of soda lime. The CO2 absorption capacity was significantly less for perhydrated soda lime than for standard soda lime.

CONCLUSIONS

Compound A concentrations in the circuit can be reduced by using soda lime with water added. The CO2 absorption capacity of the soda lime is reduced by adding water to it, but this should not be clinically significant.

Structural features of membrane fusion between influenza virus and liposome as revealed by quick-freezing electron microscopy

The structure of membrane fusion intermediates between the A/PR/8(H1N1) strain of influenza virus and a liposome composed of egg phosphatidylcholine, cholesterol, and glycophorin was studied using quick-freezing electron microscopy. Fusion by viral hemagglutinin protein was induced at pH 5.0 and 23 degrees C. After a 19-s incubation under these conditions, small protrusions with a diameter of 10-20 nm were found on the fractured convex faces of the liposomal membranes, and small pits complementary to the protrusions were found on the concave faces. The protrusions and pits corresponded to fractured parts of outward bendings of the lipid bilayer or "microprotrusions of the lipid bilayer." At the loci of the protrusions and pits, liposomal membranes had local contacts with viral membranes. In many cases both the protrusions and the pits were aligned in regular polygonal arrangements, which were thought to reflect the array of hemagglutinin spikes on the viral surface. These structures were induced only when the medium was acidic with the virus present. Based on these observations, it was concluded that the microprotrusions of the lipid bilayer are induced by hemagglutinin protein. Furthermore, morphological evidence for the formation of the "initial fusion pore" at the microprotrusion was obtained. The protrusion on the convex face sometimes had a tiny hole with a diameter of <4 nm in the center. The pits transformed into narrow membrane connections <10 nm in width, bridging viruses and liposomes. The structures of the fusion pore and fusion neck with larger sizes were also observed, indicating growth of the protrusions and pits to distinct fusion sites. We propose that the microprotrusion of the lipid bilayer is a fusion intermediate induced by hemagglutinin protein, and suggest that the extraordinarily high curvature of this membrane structure is a clue to the onset of fusion. The possible architecture of the fusion intermediate is discussed with regard to the localization of intramembrane particles at the microprotrusion.

Effects of low-flow sevoflurane anesthesia on renal function: comparison with high-flow sevoflurane anesthesia and low-flow isoflurane anesthesia

BACKGROUND

The safety of low-flow sevoflurane anesthesia, during which CF2=C(CF3)-O-CH2F (compound A) is formed by sevoflurane degradation, in humans has been questioned because compound A is nephrotoxic in rats. Several reports have evaluated renal function after closed-circuit or low-flow sevoflurane anesthesia, using blood urea nitrogen (BUN) and serum creatinine as markers. However, these are not the more sensitive tests for detecting renal damage. This study assessed the effects of low-flow sevoflurane anesthesia on renal function using not only BUN and serum creatinine but also creatinine clearance and urinary excretion of kidney-specific enzymes, and it compared these values with those obtained in high-flow sevoflurane anesthesia and low-flow isoflurane anesthesia.

METHODS

Forty-eight patients with gastric cancer undergoing gastrectomy were studied. Patients were randomized to receive sevoflurane anesthesia with fresh gas flow of 1 l/min (low-flow sevoflurane group; n = 16) or 6-10 l/min (high-flow sevoflurane group; n = 16) or isoflurane anesthesia with a fresh gas flow of 1 l/min (low-flow isoflurane group; n = 16). In all groups, the carrier gas was oxygen/nitrous oxide in the ratio adjusted to ensure a fractional concentration of oxygen in inspired gas (FiO2) of more than 0.3. Fresh Baralyme was used in the low-flow sevoflurane and low-flow isoflurane groups. Glass balls were used instead in the high-flow sevoflurane group, with the fresh gas flow rate adjusted to eliminate rebreathing. The compound A concentration was measured by gas chromatography. Gas samples taken from the inspiratory limb of the circle system at 1-h intervals were analyzed. Blood samples were obtained before and on days 1, 2, and 3 after anesthesia to measure BUN and serum creatinine. Twenty-four-hour urine samples were collected before anesthesia and for each 24-h period from 0 to 72 h after anesthesia to measure creatinine, N-acetyl-beta-D-glucosaminidase, and alanine aminopeptidase.

RESULTS

The average inspired concentration of compound A was 20 +/- 7.8 ppm (mean +/- SD), and the average duration of exposure to this concentration was 6.11 +/- 1.77 h in the low-flow sevoflurane group. Postanesthesia BUN and serum creatinine concentrations decreased, creatinine clearance increased, and urinary N-acetyl-beta-D-glucosaminidase and alanine aminopeptidase excretion increased in all groups compared with preanesthesia values, but there were no significant differences between the low-flow sevoflurane, high-flow sevoflurane, and low-flow isoflurane groups for any renal function parameter at any time after anesthesia.

CONCLUSIONS

The only difference between the low-flow and high-flow sevoflurane groups was compound A formation, and postanesthesia laboratory data showed no significant effects of compound A formation during sevoflurane anesthesia on renal function. No significant effects on renal function were observed in either the low-flow or high-flow sevoflurane groups compared with the low-flow isoflurane group.

Long-lasting enhancement of ACh receptor currents by lysophospholipids

Lysophosphatidylcholine (LysoPtdCho) and lysophosphatidylethanolamine (LysoPtdEtn), which are formed by phospholipase A2-catalyzed hydrolysis of phosphatidylcholine (PtdCho) and phosphatidylethanolamine (PtdEtn), respectively, are proposed to be involved in protein kinase C (PKC) activation. Their physiological significance, however, remains unclear. We examined the effects of lysoPtdCho and lysoPtdEtn on acetylcholine (ACh) receptor currents using oocytes expressing Torpedo nicotinic ACh receptors. LysoPtdCho enhanced the currents in a washing time- and dose-dependent manner (10 nM-1 microM), reaching a maximum of 191% at 20 min after treatment. The currents were enhanced to a lesser extent at higher concentrations, and instead, inhibited to 81% at 10 microM. Likewise, lysoPtdEtn also potentiated the currents to 200% at 10 microM, although its dose-dependent curve shifted to right as compared with that of lysoPtdCho. The current potentiation was blocked by a PKC inhibitor, PKC inhibitor peptide (PKCI), or removal of extracellular Ca2+. In addition, lysoPtdCho and lysoPtdEtn enhanced the currents in mutant ACh receptors lacking PKC phosphorylation sites on the alpha and delta subunits. These results suggest that lysophospholipids such as lysoPtdCho and lysoPtdEtn potentiated ACh receptor currents by Ca2+-dependent PKC activation, but that this effect did not require PKC phosphorylation of the ACh receptor.

Thermal gelation profile changes in reconstituted actomyosin due to storage under a high salt concentration and low temperature

Changes in the heat-induced gelation properties of reconstituted rabbit skeletal actomyosin stored under a high salt concentration at pH 6.0 and 0 degree C were investigated at different weight ratios of actin to myosin by using dynamic rheological and biochemical measurements. The addition of actin resulted in a pronounced peak maximum at about 50 degrees C and an accompanying temporary reduction in the range at about 50 degrees C to 60 degrees C. The more the initial actin concentration was increased, the greater was the area of the peak/shoulder. However, this area was markedly diminished with increasing storage time. As a result, the dynamic rheological pattern was transformed from an actomyosin type into a myosin type. The relationship between the G' value at 80 degrees C and the actin/myosin weight ratio was curvilinear, with a peak at the ratio of 0.05, immediately after storage was started. This profile changed during storage, depending on the extent to denaturation of actin and myosin in the reconstituted actomyosin (RAM). The G' value of actomyosin in 0.5 M KCl with a small actin/myosin ratio of 0.05 decreased to one-half of its initial value after 7 days of storage, whereas the G' value with a large actin/myosin ratio of 0.225 increased by about 1.6 times. In 1.5 M KCl, all the G' values declined to the level with myosin alone after 7 days of storage. The time-course plots of the remaining actin concentration in RAM at different weight ratios of actin to myosin after being treated with 0.5 M or 1.5 M KCl showed a decrease in the actin content with increasing storage time, and an increase in the KCl concentration to 1.5 M KCl promoted the denaturation of actin in RAM faster than with 0.5 M KCl. The surface hydrophobicity of each RAM sample progressively increased with increasing storage time, while little significant increase in the sulfhydryl (SH) content during storage was observed. It is concluded that changes in the heat-induced gelation properties of actomyosin during storage are largely attributable to the denaturation of actin rather than to the denaturation of myosin or to quantitative changes in the SH content and hydrophobicity.

Short-term depression and long-term enhancement of ACh-gated channel currents induced by linoleic and linolenic acid

The effects of cis-unsaturated free fatty acids such as linoleic and linolenic acid on ACh-evoked currents were examined using normal and mutant nicotinic acetylcholine (ACh) receptors lacking protein kinase C (PKC) phosphorylation sites on the alpha and delta subunits expressed in Xenopus oocytes. These free fatty acids reduced ACh-gated channel currents during treatment and to a greater extent in Ca2+-free extracellular solution. After treatment, the currents were enhanced as the drug was washed out, but this effect was not observed in the absence of extracellular Ca2+. Linolenic acid was more potent of the current enhancement (300% of the control) than linoleic acid (190% of the control). The current enhancement induced by these free fatty acids was inhibited by the selective PKC inhibitor, GF109203X, while the current depression was not affected. Furthermore, these lipids decreased ACh-evoked currents in mutant ACh receptors to the same extent as in normal ACh receptors, but never enhanced the currents. These results indicate that linoleic and linolenic acid have biphasic actions on ACh receptor currents; a short-term depression and a long-term enhancement. The short-term depression may be due to an interaction with the ACh receptor channels, presumably at Ca2+ binding sites. The long-lasting enhancement appears to result from Ca2+-dependent PKC activation followed by PKC phosphorylation of the ACh receptors.

Differential effects of the serotonin receptors on cultured rat cerebral cortical neurons

Effects of serotonin (5-HT) on cerebral cortical neurons were examined by patch clamp techniques. 5-HT produced a variety of responses such as outward (19/73 patches/neurons), slow inward (15/73 patches/neurons), fast inward (8/73 patches/neurons), and mixed currents (initially fast inward deflection followed by an outward response: 2.73 patches/neurons), with a latency of 12 sec, 15 sec, 0 sec, and 0 sec respectively, at a holding potential of -60 mV in whole-cell patches. The fast inward currents were again evoked by a selective 5-HT3 receptor agonist, 1-(m-chlorophenyl)-biguanide hydrochloride (CPBG). In the cell-attached patch clamp configuration, 5-HT inside the patch pipette elicited single channel currents with slope conductances of 42 pS and 132 pS (4/42 patches/neurons). CPBG inside the patch pipette evoked inward single channel currents with a lower slope conductance of 41 pS (3/23 patches/neurons). In contrast, application of 5-HT or a 5-HT2 receptor agonist, alpha-methyl-5-hydroxytryptamine-maleate, outside the patch pipette induced outward single channel currents with a major slope conductance of 140 pS (8/30 patches/neurons) or 135 pS (6/20 patches neurons), respectively. These results indicate that the outward and fast inward currents may be mediated respectively by the 5-HT2 receptor, which is coupled to a G-protein, and by the 5-HT3 receptor, which contains the non-selective cation channel, and that the mixed type may be caused by both the 5-HT2 and 5-HT3 receptors.

Oleic acid enhances ACh receptor currents by activation of Ca2+/calmodulin-dependent protein kinase II

Oleic acid, a cis-unsaturated free fatty acid, is proposed to be involved in the protein kinase C (PKC) activation pathway. Its biological actions, however, have not been well-characterized. We examined the effects of oleic acid on acetylcholine (ACh)-gated channel currents using Torpedo nicotinic ACh receptors expressed in Xenopus oocytes. Oleic acid (10 microM) enhanced the currents, reaching a maximum (140%) 20 min after treatment, while no enhancement was observed in Ca(2+)-free extracellular solution. The current potentiation by oleic acid was not inhibited by PKC inhibitors such as PKCI or GF109203X. Furthermore, oleic acid potentiated the currents in mutant ACh receptors lacking potential PKC phosphorylation sites. In contrast, the potentiation was fully inhibited by a CaMKII inhibitor, KN-62. These results strongly suggest that oleic acid potentiates ACh receptor currents by activation of calmodulin-dependent protein kinase II (CaMKII), independent of the PKC pathway.

Adenosine activates the K+ channel and enhances cytosolic Ca2+ release via a P2Y purinoceptor in hippocampal neurons

The effects of adenosine on hippocampal neurons were examined by patch-clamp recording and Ca2+ imaging using fura-2 fluorescence. In the whole-cell patch-clamp configuration, adenosine evoked outwardly rectifying K+ currents in a dose-dependent manner. These currents were not inhibited by a nonselective P1 purinoceptor antagonist or selective adenosine A1, A2A receptor antagonists and moreover, selective adenosine A1, A2A receptor agonists evoked no current. In contrast, P2 purinoceptor agonists produced similar outward currents with the order of potency: ADP > or = 2-methylthio ATP > ATP > adenosine >> AMP. No response was obtained to UTP, alpha, beta-methylene ATP or beta, gamma-methylene ATP. The intracellular perfusion of a broad G-protein inactivator, guanosine-5'-O-(2-thiodiphosphate) (GDP beta S), abolished adenosine-evoked currents, whereas a Gi/Go-protein inhibitor, pertussis toxin, had no effect. Furthermore, the currents were blocked by a phospholipase C inhibitor, neomycin, or specific protein kinase C inhibitors, GF109203X (bisindolyl maleimide, C25H24N4O2) and protein kinase C inhibitor peptide. In the cell-attached patch-clamp configuration, adenosine elicited single-channel currents with two major kinds of slope conductances. Likewise, application of adenosine outside the patch electrode again produced single-channel currents with same conductances. A potent protein kinase C activator, 12-O-tetradecanoylphorbol-13-acetate (TPA), induced single-channel currents in a fashion that mimics the effect of adenosine. The evoked currents were blocked by GF109203X. In addition, adenosine enhanced intracellular free Ca2+ concentration ([Ca2+]i). This [Ca2+]i increase was inhibited by GDP beta S or neomycin, but was not affected by pertussis toxin. These results, thus, suggest that adenosine activates the K+ channel and enhances cytosolic Ca2+ release via a P2Y purinoceptor linked to a pertussis toxin-insensitive G-protein, which is involved in a phospholipase C-mediated phospholipid-signaling pathway.

ATP-regulated K+ channel and cytosolic Ca2+ mobilization in cultured rat spinal neurons

ATP activated the K+ channel responsible for outwardly rectifying currents via a P2Y purinoceptor linked to a pertussis toxin-insensitive G-protein in cultured rat spinal neurons. The evoked currents were inhibited by a selective protein kinase C inhibitor, GF109203X, whereas a phospholipase C inhibitor, neomycin had no effect. These indicate that the currents are regulated by phospholipase C-independent protein kinase C activation. In addition, ATP enhanced intracellular free Ca2+ concentration. The increase in intracellular free Ca2+ concentration was inhibited by a broad G-protein inhibitor, GDP beta S, but not affected by neomycin or an inositol 1,4,5-triphosphate receptor antagonist, heparin, suggesting that the cytosolic Ca2+ mobilization is regulated by a mechanism independent of a phospholipase C-mediated phosphatidylinositol signaling. These results, thus, demonstrate that ATP has dual actions on the coupled K+ channel and cytosolic Ca2+ release.

Arachidonic acid potentiates ACh receptor currents by protein kinase C activation but not by receptor phosphorylation

The effects of arachidonic acid on ACh-gated channel currents were examined using Torpedo nicotinic ACh receptors expressed in Xenopus oocytes. Arachidonic acid decreased ACh-evoked currents during treatment, to a greater extent in Ca(2+)-free extracellular solution. The currents were enhanced for more than 30 min after washing, reaching 150 and 170% in Ca(2+)-containing and -free extracellular solutions, respectively. The current enhancement was inhibited by the selective protein kinase C (PKC) inhibitor, GF109203X, whereas the current depression was not affected. Furthermore, arachidonic acid-evoked current depression was blocked in mutant ACh receptors with PKC phosphorylation site deletions on the alpha and delta subunits, but the long-lasting potentiation effect remained. These results indicate that arachidonic acid may decrease ACh receptor currents by a direct binding to PKC phosphorylation sites of the ACh receptors and may potentiate the currents via a novel pathway related to arachidonic acid-regulated PKC activation, but not via PKC phosphorylation of the ACh receptor itself.

Repetitive applications of ATP potentiate potassium current by Ca2+/calmodulin kinase in cultured rat hippocampal neurons

ATP evoked whole-cell potassium currents in hippocampal neurons. The second application of ATP to the same cell potentiated the current amplitude to around 140% and the current potentiation was maintained by further applications. A calmodulin inhibitor, W-7, or a selective Ca2+/calmodulin-dependent protein kinase II (CaMKII) inhibitor, KN-62, inhibited the current potentiation, although a selective protein kinase C inhibitor, GF109203X, or a selective cAMP-dependent protein kinase inhibitor, H-89, had no effect. In addition, ATP enhanced intracellular free Ca2+ concentration, which may activate CaMKII, but this enhancement was blocked by repetitive applications. These results provide an indication that CaMKII may be involved in the current potentiation by repetitive applications of ATP.

Regulation of the serum-activated Ca(2+)-dependent chloride channel in Xenopus oocytes

Fetal bovine serum evoked Ca(2+)-dependent chloride currents with two components in Xenopus oocytes. The evoked currents were inhibited by GDP beta S, but not by pertussis toxin (PTX). An inositol 1,4,5-triphosphate (IP3) receptor antagonist, heparin completely inhibited the currents, although a phospholipase C inhibitor, neomycin had no effect. The serum-activated currents were enhanced to 171% by a selective protein kinase C (PKC) inhibitor, GF109203X. By contrast, a potent PKC activator, TPA, abolished the initial component of the currents and arachidonic acid enhanced this effect. The effects of TPA and/or arachidonic acid on the currents inhibited by GF109203X. These results indicate that the receptor for serum is linked to a PTX-insensitive G-protein involving cytosolic Ca2+ release through IP3 and PKC activation by a mechanism independent of a phospholipase C-mediated phospholipid signaling. Furthermore, the evoked currents are regulated by PKC and arachidonic acid appears to potentiate its effect.

Regulation of the potassium current and cytosolic Ca2+ release induced by 2-methylthio ATP in hippocampal neurons

A potent P2Y purinoceptor agonist, 2-methylthio ATP (2-MeSATP), produced whole-cell potassium currents through a purinoceptor linked to a pertussis toxin (PTX)-insensitive G-protein in rat hippocampal neurons. The currents were not affected by a selective protein kinase C or A inhibitor. Single channel recordings demonstrated that the potassium channel is activated without latency even in outside-out patches. These suggest that the channel may be regulated directly by the beta gamma subunits of a G-protein. In addition, 2-MeSATP enhanced intracellular free Ca2+ concentration ([Ca2+]i) with a very rapid initiation time. The [Ca2+]i increase was inhibited by a broad G-protein inhibitor, but not by a phospholipase C (PLC) inhibitor or an IP3 receptor antagonist. These indicate that this Ca2+ mobilization may be regulated by a mechanism independent of a PLC-mediated phosphatidylinositol signaling pathway.

P2 purinoceptor-operated potassium channel in rat cerebellar neurons

P2 purinoceptor agonists produced whole-cell potassium currents in cerebellar neurons with the order of potency 2-methylthio ATP (2-MeSATP) > ADP > ATP > adenosine > alpha,beta- methylene ATP > AMP > UTP. In the outside-out patch clamp configuration, 2-MeSATP evoked single channel currents with two major classes of slope conductances without latency. The currents were blocked by a G-protein inhibitor, GDP beta S, although they were not affected by a phospholipase C inhibitor, a selective protein kinase C or A inhibitor. In contrast, a potent G-protein activator, GTP gamma S, produced single channel currents with same conductances as those of the currents induced by 2-MeSATP. These provide an indication that the P2 purinoceptor-operated potassium channel is regulated by the beta gamma subunits of a G-protein.

Adenosine evokes potassium currents by protein kinase C activated via a novel signaling pathway in superior colliculus neurons

Adenosine evoked whole-cell potassium currents and enhanced intracellular free Ca2+ concentration ([Ca2+]i) in superior colliculus neurons through a P2Y purinoceptor linked to a pertussis toxin-insensitive G-protein, possibly Gq-protein, which is involved in a protein kinase C (PKC) activation pathway. The [Ca2+]i increase was inhibited by a phospholipase C (PLC) inhibitor, whereas the evoked currents were not affected by a PLC inhibitor or a phospholipase A2 (PLA2) inhibitor. Adenosine elicited single channel currents via PKC activation in cell-attached patches and furthermore, those currents with conductances of the same slope were induced even in excised patches, suggesting that PKC can be activated only by cell membrane factors without intracellular components. These results thus indicate that the P2Y purinoceptor-coupled potassium channel is regulated via a novel PKC activation pathway independent of PLC or PLA2.

Lysophosphatidylcholine inhibits NMDA-induced currents by a mechanism independent of phospholipase A2-mediated protein kinase C activation in hippocampal glial cells

Lysophosphatidylcholine (LysoPC), which is formed by phospholipase A2 (PLA2)-mediated phosphatidylcholine hydrolysis, is involved in enhancement of the diacylglycerol- or phorbol ester-dependent protein kinase C (PKC) activation. In the present study, the effect of lysoPC on NMDA-evoked currents was examined by whole-cell patches in cultured rat hippocampal glial cells. NMDA activated the receptor channel and produced currents in glial cells. LysoPC reversibly inhibited the NMDA-gated currents by 43% and this inhibition was not affected by a selective PKC inhibitor, GF109203X. These results indicate that lysoPC inhibits NMDA-induced currents by a mechanism independent of PLA2-mediated PKC activation. A possible explanation for the effect could be that lysoPC directly alters channel-gating kinetics of NMDA receptor or interacts with membrane components surrounding NMDA receptors.