A novel nicotinoprotein aldehyde dehydrogenase involved in polyethylene glycol degradation

A gene (pegC) encoding aldehyde dehydrogenase (ALDH) was located 3.4 kb upstream of a gene encoding polyethylene glycol (PEG) dehydrogenase (pegA) in Sphingomonas macrogoltabidus strain 103. ALDH was expressed in Escherichia coli and purified on a Ni-nitrilotriacetic acid agarose column. The recombinant enzyme was a homotetramer consisting of four 46.1-kDa subunits. The alignment of the putative amino acid sequence of the cloned enzyme showed high similarity with a group of NAD(P)-dependent ALDHs (identity 36-52%); NAD-binding domains (Rossmann fold and four glycine residues) and catalytic residues (Glu225 and Cys259) were well conserved. The cofactor, which was extracted from the purified enzyme, was tightly bound to the enzyme and identified as NADP. The enzyme contained 0.94 mol NADP per subunit. The enzyme was activated by Ca(2+), but by no other metals; no metal (Zn, Fe, Mg, or Mn) was detected in the purified recombinant enzyme. Activity was inhibited by p-chloromercuric benzoate, and heavy metals such as Hg, Cu, Pb and Cd, indicating that a cysteine residue is involved in the activity. Enzyme activity was independent of N,N-dimethyl-p-nitrosoaniline as an electron acceptor. Trans-4-(N,N-dimethylamino)-cinnamaldehyde was not oxidized as a substrate, but the compound worked as an inhibitor for the enzyme, as did pyrazole. The enzyme acted on n-aldehydes C(2)-C(14)) and PEG-aldehydes. Thus the enzyme was concluded to be a novel Ca(2+)-activating nicotinoprotein (NADP-containing) PEG-aldehyde dehydrogenase involved in the degradation of PEG in S. macrogoltabidus strain 103.

Linalool suppresses voltage-gated currents in sensory neurons and cerebellar Purkinje cells

Linalool is a major component of essential oils and possesses various biological effects in sensory or central nervous systems. To investigate the pharmacological and biophysical effects of linalool on voltage-gated currents in sensory neurons, we used the whole-cell patch clamp and the Ca(2+) imaging techniques. Under the voltage clamp, membrane depolarization generated time- and voltage-dependent current responses in newt olfactory receptor cells (ORCs). Linalool significantly and reversibly suppressed the voltage-gated currents in ORCs. The dose-suppression relation of linalool for the voltage-gated Na(+) current could be fitted by the Hill equation with a half-blocking concentration of 0.56 mM and a Hill coefficient of 1.2. To test whether linalool suppresses voltage-gated currents in ORCs specifically or suppresses currents in other neurons generally, we next examined the effects of linalool on voltage-gated currents in newt retinal neurons and rat cerebellar Purkinje cells. Linalool suppressed the voltage-gated currents not only in retinal horizontal cells and ganglion cells but also in Purkinje cells. Furthermore, bath application of linalool inhibited the KCl-induced [Ca(2+)](i) response of ORCs, suggesting that linalool suppresses Ca(2+) currents in ORCs. These results suggest that linalool non-selectively suppresses the voltage-gated currents in newt sensory neurons and rat cerebellar Purkinje cells.

Treatment of the yeast Rhodotorula glutinis with AlCl3 leads to adaptive acquirement of heritable aluminum resistance

When aluminum (Al) was added to a culture, growth of Rhodotorula glutinis IFO1125 was temporarily arrested, showing longer lag phases, depending on the Al concentrations (50-300 microM) added, but the growth rates were not affected at all. Resistant strains obtained by one round of plate treatment containing Al reverted the resistance level to the wild-type level when cultivated without Al. Repeated Al treatments, however, induced heritable and stable Al resistance, the level of which was increased up to 4,000 microM by stepwise increments in Al concentrations. Thus, the heritable Al resistance adaptively acquired was due neither to adaptation nor to mutation, but to a mechanism which has yet to be studied. Heritable Al resistance seemed to release the Al inhibition of magnesium uptake.

Direct suppression by odorants of ionotropic glutamate receptors in newt retinal neurons

Odorants are known to suppress voltage-gated channels not only in olfactory receptor cells but also in neurons of outside of the olfactory system. Here we found that odorants suppress glutamate-gated channels in newt retinal neurons using the Ca(2+) imaging technique. Bath application of 100 microM glutamate rose [Ca(2+)](i) under application of the voltage-gated Ca(2+) channel blocker. Thus, [Ca(2+)](i) rises in the neurons were most likely attributable to Ca(2+) influx via Ca(2+)-permeable glutamate-gated channels rather than voltage-gated Ca(2+) channels. A similar increase of [Ca(2+)](i) was observed by application of 100 microM NMDA and 50 microM kainate, suggesting that both NMDA and AMPA/kainate receptors were expressed in newt retinal neurons. Application of odorants, 1 mM amyl acetate and acetophenone, reversibly reduced [Ca(2+)](i) increased by glutamate, NMDA and kainate. This suggests that odorants can suppress not only voltage-gated channels but also ligand-gated channels such as NMDA and AMPA/kainate receptors.

Microbial degradation of polyethers

This paper summarizes studies on microbial degradation of polyethers. Polyethers are aerobically metabolized through common mechanisms (oxidation of terminal alcohol groups followed by terminal ether cleavage), well-characterized examples being found with polyethylene glycol (PEG). First the polymer is oxidized to carboxylated PEG by alcohol and aldehyde dehydrogenases and then the terminal ether bond is cleaved to yield the depolymerized PEG by one glycol unit. Most probably PEG is anaerobically metabolized through one step which is catalyzed by PEG acetaldehyde lyase, analogous to diol dehydratase. Whether aerobically or anaerobically, the free OH group is necessary for metabolization of PEG. PEG with a molecular weight of up to 20,000 was metabolized either in the periplasmic space (Pseudomonas stutzeri and sphingomonads) or in the cytoplasm (anaerobic bacteria), which suggests the transport of large PEG through the outer and inner membranes of Gram-negative bacterial cells. Membrane-bound PEG dehydrogenase (PEG-DH) with high activity towards PEG 6,000 and 20,000 was purified from PEG-utilizing sphingomonads. Sequencing of PEG-DH revealed that the enzyme belongs to the group of GMC flavoproteins, FAD being the cofactor for the enzyme. On the other hand, alcohol dehydrogenases purified from other bacteria that cannot grow on PEG oxidized PEG. Cytoplasmic NAD-dependent alcohol dehydrogenases with high specificity towards ether-alcohol compound, either crude or purified, showed appreciable activity towards PEG 400 or 600. Liver alcohol dehydrogenase (equine) also oxidized PEG homologs, which might cause fatal toxic syndrome in vivo by carboxylating PEG together with aldehyde dehydrogenase when PEG was absorbed. An ether bond-cleaving enzyme was detected in PEG-utilizing bacteria and purified as diglycolic acid (DGA) dehydrogenase from a PEG-utilizing consortium. The enzyme oxidized glycolic acid, glyoxylic acid, as well as PEG-carboxylic acid and DGA. Similarly, dehydrogenation on polypropylene glycol (PPG) and polytetramethylene glycol (PTMG) was suggested with cell-free extracts of PPG and PTMG-utilizing bacteria, respectively. PPG commercially available is atactic and includes many structural (primary and secondary alcohol groups) and optical (derived from pendant methyl groups on the carbon backbone) isomers. Whether PPG dehydrogenase (PPG-DH) has wide stereo- and enantioselective substrate specificity towards PPG isomers or not must await further purification. Preliminary research on PPG-DH revealed that the enzyme was inducibly formed by PPG in the periplasmic, membrane and cytoplasm fractions of a PPG-utilizing bacterium Stenotrophomonas maltophilia. This finding indicated the intracellular metabolism of PPG is the same as that of PEG. Besides metabolization of polyethers, a biological Fenton mechanism was proposed for degradation of PEG, which was caused by extracellular oxidants produced by a brown-rot fungus in the presence of a reductant and Fe3+, although the metabolism of fragmented PEG has not yet been well elucidated.

The first step in polyethylene glycol degradation by sphingomonads proceeds via a flavoprotein alcohol dehydrogenase containing flavin adenine dinucleotide

Several Sphingomonas spp. utilize polyethylene glycols (PEGs) as a sole carbon and energy source, oxidative PEG degradation being initiated by a dye-linked dehydrogenase (PEG-DH) that oxidizes the terminal alcohol groups of the polymer chain. Purification and characterization of PEG-DH from Sphingomonas terrae revealed that the enzyme is membrane bound. The gene encoding this enzyme (pegA) was cloned, sequenced, and expressed in Escherichia coli. The purified recombinant enzyme was vulnerable to aggregation and inactivation, but this could be prevented by addition of detergent. It is as a homodimeric protein with a subunit molecular mass of 58.8 kDa, each subunit containing 1 noncovalently bound flavin adenine dinucleotide but not Fe or Zn. PEG-DH recognizes a broad variety of primary aliphatic and aromatic alcohols as substrates. Comparison with known sequences revealed that PEG-DH belongs to the group of glucose-methanol-choline (GMC) flavoprotein oxidoreductases and that it is a novel type of flavoprotein alcohol dehydrogenase related (percent identical amino acids) to other, so far uncharacterized bacterial, membrane-bound, dye-linked dehydrogenases: alcohol dehydrogenase from Pseudomonas oleovorans (46%); choline dehydrogenase from E. coli (40%); L-sorbose dehydrogenase from Gluconobacter oxydans (38%); and 4-nitrobenzyl alcohol dehydrogenase from a Pseudomonas species (35%).

Enhancement by T-type Ca2+ currents of odor sensitivity in olfactory receptor cells

Mechanisms underlying action potential initiation in olfactory receptor cells (ORCs) during odor stimulation were investigated using conventional and dynamic patch-clamp recording techniques. Under current-clamp conditions, action potentials generated by a least effective odor-induced depolarization were almost completely blocked by 0.1 mm Ni(2+), a T-type Ca(2+) channel blocker, but not by 0.1 mm Cd(2+), a high voltage-activated Ca(2+) channel blocker. Under voltage-clamp conditions, depolarizing voltage steps induced a fast transient inward current, which consisted of Na(+) (I(Na)) and T-type Ca(2+) (I(Ca,T)) currents. The amplitude of I(Ca,T) was approximately one-fourth of that of I(Na) (0.23 +/- 0.03, mean +/- SEM). Because both I(Na) and I(Ca,T) are known to show rapid inactivation, we examined how much I(Na) and I(Ca,T) are activated during the gradually depolarizing initial phase of receptor potentials. The ratio of I(Ca,T)/I(Na) during a ramp depolarization at the slope of 0.5 mV/msec was 0.56 +/- 0.03. Using the dynamic patch-clamp recording technique, we also recorded I(Ca,T) and I(Na) during the generation of odor-induced action potentials. This ratio of I(Ca,T)/I(Na) was 0.54 +/- 0.04. These ratios were more than twice as large as that (0.23) obtained from the experiment using voltage steps, suggesting that I(Ca,T) carries significant amount of current to generate the action potentials. We conclude that I(Ca,T) contributes to enhance odor sensitivity by lowering the threshold of spike generation in ORCs.

Na(+) action potentials in human photoreceptors

Mammalian photoreceptors are hyperpolarized by a light stimulus and are commonly thought to be nonspiking neurons. We used the whole-cell patch-clamp technique on surgically excised human retina to examine whether human photoreceptors can elicit action potentials. We discovered that human rod photoreceptors express voltage-gated Na(+) channels, and generate Na(+) action potentials, in response to membrane depolarization from membrane potentials of -60 or -70 mV. Na(+) spikes in human rods were elicited at the termination of a light response that hyperpolarized the potential well below -50 mV. This served to amplify the release of a neurotransmitter when a bright light is turned off, and thus selectively amplify the off response to the light signal.

Modulation by cGMP of the voltage-gated currents in newt olfactory receptor cells

Effects of cGMP on voltage-gated currents in the somatic membrane of isolated newt olfactory receptor cells were investigated using the whole-cell mode of the patch-clamp technique. Under voltage clamp, membrane depolarization generated time- and voltage-dependent current responses, a transient inward current and a sustained outward current. When cGMP or a membrane permeant analog of cGMP, 8-p-chlorophenylthio-cGMP (CPT-cGMP), was applied to the recorded cell, the amplitude of the transient inward current increased markedly, but that of the sustained outward current did not change significantly. When each current was isolated by pharmacological agents, 0.1 mM CPT-cGMP increased the peak amplitude of a Na(+) current (I(Na)) by approximately 40%, a T-type Ca(2+) current (I(Ca,T)) by approximately 40%, and an L-type Ca(2+)current (I(Ca,L)) by approximately 10%; however it did not change significantly the amplitude of a delayed rectifier K(+) current (I(K)). A selective cGMP-dependent protein kinase inhibitor, KT5823, blocked the enhancement by cGMP of I(Na) and I(Ca,T), suggesting that cGMP increases these currents via cGMP-dependent phosphorylation. Under current-clamp conditions, application of CPT-cGMP lowered the current threshold of action potentials induced by current injection, and increased the maximum spike frequency in response to strong stimuli. We suggest that cGMP may lower the threshold in olfactory perception by decreasing the current threshold to generate spikes, and also prevent the saturation of odor signals by increasing the maximum spike frequency.

Screening and characterization of trehalose-oleate hydrolyzing lipase

Various soil samples were collected to screen the presence of microorganisms which have ability to degrade TOE. One strain (AKU-883) with good TOE degrading activity was isolated and identified as Burkholderia cepacia and the extracellular enzyme was purified to homogeneity. The purification was achieved by ultrafiltration, Super Q anion-exchange chromatography and Superdex 200HR gel-filtration in the presence of Triton X. The enzyme was purified to 85-fold, and specific activity of 4.910 kU mg protein(-1). The peak preparation on gel filtration showed a single band of 34 kDa on SDS-PAGE and native PAGE which indicate the monomeric nature of the enzyme. The pI of the enzyme was 6.3. The enzyme showed the maximum activity at pH 9 and 65 degrees C, and was stable in the range of pH 5--10 and up to 60 degrees C. Almost all the activity (92%) was kept after incubation for more than 1 week at 50 degrees C (pH 7.3). High activities remained even in water-miscible solvents such as ethanol, dimethyl formamide, diisopropyl ether, and dioxane. The N-terminal 16 amino acid residues were determined as A-N-G-Y-A-A-T-R-Y-P-I-I-L-V-G-G, which showed a consensus sequence for lipases from Burkholderia species. Thus the enzyme was concluded to be a kind of lipase.

Direct suppression by odorants of cyclic nucleotide-gated currents in the newt photoreceptors

Odorants are known to suppress the cyclic nucleotide-gated (CNG) current in olfactory receptor cells. It is unclear, however, whether odorants suppress the olfactory CNG current directly or whether they suppress the current by decreasing the second messenger (cAMP) through the activation of phosphodiesterase. We found that odorants also suppress CNG currents in photoreceptor cells. Under voltage clamp, an odorant puff immediately suppressed the currents induced by the intracellular cGMP in isolated newt rods and cones. Odorants also suppressed the currents induced by another cGMP analog (8-p-chlorophenylthio-cGMP, which strongly resists hydrolysis by phosphodiesterase), suggesting that the second messenger metabolism via phosphodiesterase is not involved in the suppression by odorants. This suggests that odorants suppress the CNG currents directly rather than via the second messenger system in photoreceptors, and also likely in olfactory receptor cells.

Isolation and characterization of acid- and Al-tolerant microorganisms

Acid- and aluminum (Al)-tolerant microorganisms were isolated from tea fields, from which six strains were selected and identified as Cryptococcus humicola, Rhodotorula glutinis, Aspergillus flavus Link, Penicillium sp., Penicillium janthinellum Biourge and Trichoderma asperellum. They were tolerant to Al up to 100-200 mM and could grow at low pH, 2.5-2.2. In a glucose medium (pH 3.5) the pH of the spent medium decreased to below 3.0. The toxic inorganic monomeric Al in the spent medium decreased with three strains (A. flavus F-6b, Penicillium sp. F-8b and P. janthinellum F-13), but the total Al remained constant for all strains. In a soil extract medium (pH 3.5), the pH of the spent medium of all strains increased to around 6.0-7. 2 and total Al in the spent medium was removed by precipitation due to pH increase. Thus, different tolerance mechanisms were suggested in glucose and soil extract media.

Odorants suppress voltage-gated currents in retinal horizontal cells in goldfish

Odorants are known to suppress non-selectively voltage-gated currents in olfactory receptor cells. We found that odorants also suppress voltage-gated currents in neurons of outside of the olfactory system. Under voltage clamp, odorants such as amyl acetate, limonene, and acetophenone suppressed non-selectively voltage-gated currents (a Ca(2+) current, a delayed rectifier K(+) current, a fast transient K(+) current, and an anomalous rectifier K(+) current) in horizontal cells from the goldfish retina. An amyl acetate puff completely and immediately suppressed the Ca(2+) current (I(Ca)) and the delayed rectifier K(+) current induced by repetitive depolarizations, suggesting that amyl acetate is a closed-channel blocker. Odorants did not change significantly the activation curve of I(Ca), but made the slope of inactivation curve of I(Ca) gentler and shifted its half-inactivation voltage toward a negative voltage. These results are similar to the effects of odorants on voltage-gated currents in olfactory receptor cells. This suggests that odorants may suppress the voltage-gated currents in retinal horizontal cells by the same mechanism described in olfactory receptor cells.

Purification and inactivation by substrate of an allene oxide synthase (CYP74) from corn (Zea mays L.) seeds

The allene oxide synthase (AOS) was purified from corn (Zea mays) seeds to homogeneity and characterized partially. The corn AOS was a hemoprotein cytochrome P450 with a molecular weight and pI of 53,000 and 6.0, respectively. The corn AOS was found to be irreversibly inactivated by a substrate, 13-hydroperoxyoctadienoic acid. The rate of the enzyme inactivation was higher at low pHs.

Odorants suppress T- and L-type Ca2+ currents in olfactory receptor cells by shifting their inactivation curves to a negative voltage

Mechanisms underlying suppression of T- and L-type Ca2+ currents (I(Ca,T) and I(Ca,L)) by odorants were investigated in newt olfactory receptor cells (ORCs) using the whole-cell version of the patch-clamp technique. Under voltage clamp, odorants (amyl acetate, limonene and acetophenone) reversibly suppressed I(Ca,T) and I(Ca, L). These currents disappeared completely within 150 ms following amyl acetate puffs, and recovered in approximately 1 s after the washout. Hyperpolarization of the membrane greatly relieved the odorant block of I(Ca,T) and I(Ca,L). The activation curves of both currents were not changed significantly by odorants, while their inactivation curves were shifted to negative voltages. Half-inactivation voltages of I(Ca,T) were - 66 mV (control), - 102 mV (amyl acetate), - 101 mV (limonene) and - 105 mV (acetophenone) (all 0.3 mM); those of I(Ca,L) were -33 mV (control), - 61 mV (amyl acetate), - 59 mV (limonene), and - 63 mV (acetophenone) (all 0.3 mM). These phenomena are similar to the effects of local anesthetics on I(Ca) in various preparations and also similar to the effects of odorants on I(Na) in ORCs, suggesting that these types of suppression are caused by the same mechanism.

Simulation analysis of effects of adrenaline on spike generation in olfactory receptor cells

Adrenaline is known to affect action potentials induced by the step current injection in an olfactory receptor cell (ORC). It is unclear, however, whether it also modulates action potentials induced by odor stimuli. In the present study, the effects of adrenaline on action potentials in ORCs were investigated quantitatively using a computer simulation. Adrenaline suppressed simulated action potentials induced by step current injection near threshold, and increased spike frequency to strong stimuli by 8-25%. Similar effects were obtained by applying a pseudo-transduction current to a model cell. Surprisingly, adrenaline markedly increased spike frequency to strong stimuli by 30-140%, and increased the slope of the stimulus-response relation compared with that of the step current injection. This suggests that adrenaline enhances odorant contrast in olfactory perception by modulating signal encoding of ORCs.

[Ultrasound-guided fine-needle aspiration cytology for neck lesions]

In 1997, 240 cases of ultrasound-guided fine-needle aspiration cytology (FNAC) were performed for neck lesion at Jichi Medical School Hospital. We compared the preoperative cytology findings with postoperative pathologic results for 63 cases (56 lesions) from patients who underwent surgery or open biopsy. The sensitivity, specificity and accuracy of cytological diagnosis were 93.5%, 100% and 96.2%, respectively. There were 2 false negative cases in thyroid gland, which were follicular and medullary carcinomas. Insufficient material for cytological analysis was obtained in 62 of 240 cases (25.8%). Since FNAC can provide high accuracy, we need to reduce insufficient material cases.

Sphingomonads involved in the biodegradation of xenobiotic polymers

Sphingomonads involved in the microbial degradation of xenobiotic polymers are introduced. The metabolism of polyethylene glycol was the primary focus of the study. Several others, including polyvinyl alcohol, polyethylene and polyaspartate were also studied. It is suggested that these xenobiotic polymers are metabolized by intracellular enzymes located in the periplasmic space or bound to membranes, indicating that transport of these polymers through outer membranes is requisite for their metabolism. Involvement of specific membrane structures of sphingomonads such as unusual sphingolipids is suggested for membrane transport of xenobiotic compounds, especially hydrophobic materials.

Characterization of spontaneous excitatory synaptic currents in newt retinal bipolar cells

The kinetics of glutamate concentration in the synaptic cleft is an important determinant of synaptic function. To elucidate peak concentration of glutamate released from a single vesicle in the cleft, spontaneous excitatory postsynaptic currents (sEPSCs) in Off-bipolar cells from the sliced newt retina were analyzed using whole-cell patch clamp recording and the computer simulation. The sEPSCs were blocked by an AMPA/kainate (KA) antagonist, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), and prolonged by cyclothiazide. However, an N-methyl-D-aspartate (NMDA) antagonist, D-2-amino-5-phosphonopentanoic acid (D-AP5), was ineffective. These suggest that sEPSCs in Off-bipolar cells are mediated exclusively by AMPA/KA receptors. sEPSCs simulated by a detailed kinetic model of AMPA receptor best approximated the data, when peak glutamate concentration was 10 microM. Therefore, it was concluded that peak concentration of glutamate released from a single vesicle would be elevated to approximately 10 microM at the newt Off-bipolar dendrite.

Odorant suppression of delayed rectifier potassium current in newt olfactory receptor cells

Effects of odorants on a delayed rectifier potassium current (IK) in newt olfactory receptor cells (ORCs) were investigated using the whole-cell version of the patch-clamp technique. Under voltage clamp, odorants (amyl acetate, limonene and acetophenone) reversibly suppressed I(K) without shifting its I-V curve. An amyl acetate puff completely suppressed I(K) induced by the first step pulse of repetitive depolarizations, suggesting that binding of an odorant molecule to the open channel is not required to block the channel. Although it is known that odorants suppress Na+ and Ca2+ currents (I(Na), I(Ca)) by shifting their inactivation curves to a negative voltage, odorants did not shift the inactivation curve of I(K) significantly. This suggests that odorants suppress I(K) without changing its voltage dependence. Therefore, the blocking mechanisms by odorants of I(K) in ORCs are different from those of I(Na) and I(Ca).

AMPA receptor activates a G-protein that suppresses a cGMP-gated current

The AMPA receptor, ubiquitous in brain, is termed "ionotropic" because it gates an ion channel directly. We found that an AMPA receptor can also modulate a G-protein to gate an ion channel indirectly. Glutamate applied to a retinal ganglion cell briefly suppresses the inward current through a cGMP-gated channel. AMPA and kainate also suppress the current, an effect that is blocked both by their general antagonist CNQX and also by the relatively specific AMPA receptor antagonist GYKI-52466. Neither NMDA nor agonists of metabotropic glutamate receptors are effective. The AMPA-induced suppression of the cGMP-gated current is blocked when the patch pipette includes GDP-beta-S, whereas the suppression is irreversible when the pipette contains GTP-gamma-S. This suggests a G-protein mediator, and, consistent with this, pertussis toxin blocks the current suppression. Nitric oxide (NO) donors induce the current suppressed by AMPA, and phosphodiesterase inhibitors prevent the suppression. Apparently, the AMPA receptor can exhibit a "metabotropic" activity that allows it to antagonize excitation evoked by NO.

Hyperechoic renal papillae as a physiological finding in neonates

AIM

The increased echogenicity of medullary pyramids in neonates and children is poorly understood. Hence we conducted a prospective ultrasound study of the kidneys of neonates and fetuses. Hence we conducted a prospective ultrasound study of the kidneys of neonates and fetuses.

PATIENTS AND METHODS

Ultrasound images of kidneys in neonates and fetuses in late pregnancy were analysed.

RESULTS

Thirteen percent of the studied neonates showed hyperechogenicity in the renal papillae that disappeared spontaneously within 1 week, although no hyperechoic papillae were seen in any of the fetuses. Urine volume of the neonates with hyperechogenicity was significantly less than that of those without it.

CONCLUSION

The fact that no hyperechoic findings appeared before the 34th week of gestation suggests that maturation of renal tubules and ability to concentrate urinary substances were contributing factors. Because only the tips of the pyramids were hyperechogenic, however, the term hyperechoic papillae would seem more appropriate than hyperechoic pyramids, the term generally used today.

Adrenaline enhances odorant contrast by modulating signal encoding in olfactory receptor cells

Olfactory perception is influenced by hormones. Here we report that adrenaline can directly affect the signal encoding of olfactory receptor cells. Application of adrenaline suppressed action potentials near threshold and increased their frequency in response to strong stimuli, resulting in a narrower dynamic range. Under voltage-clamp conditions, adrenaline enhanced sodium current and reduced T-type calcium current. Because sodium current is the major component of spike generation and T-type calcium current lowers the threshold in olfactory receptor cells, the effects of adrenaline on these currents are consistent with the results obtained under current-clamp conditions. Both effects involved a common cytoplasmic pathway, cAMP-dependent phosphorylation. We suggest that adrenaline may enhance contrast in olfactory perception by this mechanism.

Desensitization of the GABAA receptor shifts the dynamic range of retinal horizontal cells due to light and dark adaptation

The effects of the GABAergic pathway on the dynamic range of the light response of cone-driven horizontal cells (HCs) in the carp retina were investigated using conventional intracellular recordings and computer simulations. The amplitude of the HC responses to repetitive test flashes was altered by background illumination in control Ringer's solution, but was not changed following the application of picrotoxin or bicuculline, which suggests that GABAA receptors mediate the subsequent change in light response. This phenomenon was simulated by introducing the desensitization mechanism of the GABAA receptor into a cone-HC network model. These results suggest that desensitization of the GABAA receptor shifts the dynamic range of the HCs due to light and dark adaptation.

Quantitative analysis of Na+ and Ca2+ current contributions on spike initiation in the newt olfactory receptor cell

The contribution of Na+ (INa) and T-type Ca2+ (ICa,T) currents on the action potential initiation in newt olfactory receptor cells (ORC) was investigated quantitatively. Since both the Na+ channel and T-type Ca2+ channel show rapid inactivation, it was questioned how much INa and ICa,T are activated during the gradually depolarizing initial phase of the receptor potential. Because the conventional voltage clamp technique does not allow direct current measurement during voltage changes, we estimated the amplitude of INa and ICa,T in an ionic current model. The model was constructed based on voltage clamp experiments. The estimated ratio of ICa,T/INa during the action potential induced by ramp current injection was 0.59 +/- 0.03 (mean +/- SD) under control Ringer's solution. This ratio was more than twice as large as that (0.25) obtained from the previous voltage clamp experiment using step commands. This result suggests that the T-type Ca2+ channel carries a more significant amount of current to generate the action potentials than expected previously.

Differentiation of renal cell carcinomas from angiomyolipomas by ultrasonic frequency dependent attenuation

PURPOSE

We determined the usefulness of ultrasonic frequency dependent attenuation in differentiating hyperechoic renal cell carcinoma from angiomyolipoma.

MATERIALS AND METHODS

Frequency dependent attenuation values were determined in 29 renal cell carcinomas and 13 angiomyolipomas.

RESULTS

Frequency dependent attenuation values were significantly lower in renal cell carcinomas than in angiomyolipomas (0.42 versus 0.76 dB./cm./MHz.). Two of the renal cell carcinomas were as hyperechoic as the angiomyolipomas but they were clearly differentiated by the low frequency dependent attenuation. Two other renal cell carcinomas exhibited high values because of the abundance of fibrous tissue. However, they were readily diagnosed by the typical low echoic B-mode images. Frequency dependent attenuation did not differ between histological types of renal cell carcinoma. One angiomyolipoma that was poor in fat and rich in muscle components had an exceptionally low frequency dependent attenuation. Therefore, frequency dependent attenuation values can be regarded as an inversion of computerized tomography numbers.

CONCLUSIONS

Frequency dependent attenuation measurement is a promising diagnostic aid in differentiating hyperechoic renal cell carcinomas from angiomyolipomas.

Nonselective suppression of voltage-gated currents by odorants in the newt olfactory receptor cells

Effects of odorants on voltage-gated ionic channels were investigated in isolated newt olfactory receptor cells by using the whole cell version of the patch-clamp technique. Under voltage clamp, membrane depolarization to voltages between -90 mV and +40 mV from a holding potential (Vh) of -100 mV generated time- and voltage-dependent current responses; a rapidly (< 15 ms) decaying initial inward current and a late outward current. When odorants (1 mM amyl acetate, 1 mM acetophenone, and 1 mM limonene) were applied to the recorded cell, the voltage-gated currents were significantly reduced. The dose-suppression relations of amyl acetate for individual current components (Na+ current: I(Na), T-type Ca2+ current: I(Ca), T, L-type Ca2+ current: I(Ca), L, delayed rectifier K+ current: I(KV) and Ca2(+)-activated K+ current: IK(Ca)) could be fitted by the Hill equation. Half-blocking concentrations for each current were 0.11 mM (INa), 0.15 mM (ICa,T), 0.14 mM (ICa,L), 1.7 mM (IKV), and 0.17 mM (IK(Ca)), and Hill coefficient was 1.4 (INa), 1.0 (ICa,T), 1.1 (ICa,L), 1.0 (IKV), and 1.1 (IK(Ca)), suggesting that the inward current is affected more strongly than the outward current. The activation curve of INa was not changed significantly by amyl acetate, while the inactivation curve was shifted to negative voltages; half-activation voltages were -53 mV at control, -66 mV at 0.01 mM, and -84 mV at 0.1 mM. These phenomena are similar to the suppressive effects of local anesthetics (lidocaine and benzocaine) on INa in various preparations, suggesting that both types of suppression are caused by the same mechanism. The nonselective blockage of ionic channels observed here is consistent with the previous notion that the suppression of the transduction current by odorants is due to the direst blockage of transduction channels.

Comparative ultrasonographic and angiographic study of carotid arterial lesions in Takayasu's arteritis

The purpose of this study was to compare the usefulness of ultrasonography to that of angiography for studying arterial lesions in Takayasu's arteritis. Ultrasonographic and angiographic findings from 44 carotid arteries of 22 patients with Takayasu's arteritis (2 men and 20 women; mean age, 41.2 years) were compared. Angiography was used to classify the patency of the carotid arteries into three groups: nonstenotic, stenotic, and occlusive. Ultrasonography was also used to classify the same arteries into four groups: nonstenotic, mildly stenotic, moderately stenotic, and occlusive. Thickness of the wall (intima-media complex) of the carotid artery was measured with high-frequency transducers. Angiography showed 23 carotid arteries to be nonstenotic; 12, stenotic; and 9, occlusive; whereas ultrasonography showed 16 to be nonstenotic; 18, mildly stenotic; 7, moderately stenotic; and 3, occlusive. Results of the two diagnostic modalities correlated closely (P < 0.0001). Ultrasonography, aided by color flow imaging, detected six instances of a marginal but definite blood flow that angiography had failed to reveal. Arterial wall thickness correlated closely with the severity of ultrasonographic stenosis (P < 0.005). This thickness was 1.3 +/- 0.4 mm in the nonstenotic group, 1.6 +/- 0.5 mm in the mildly stenotic group, 2.2 +/- 0.8 mm in the moderately stenotic group, and 1.9 +/- 0.2 mm in the occlusive group. Even the walls of the nonstenotic arteries were significantly thicker than those of the normal carotid arteries (0.7 +/- 0.1 mm, P < 0.01). Ultrasonography appeared to be more useful than angiography in estimating stenotic severity of the carotid artery in Takayasu's arteritis. Characteristic ultrasonic findings included luminal stenosis or occlusion on two-dimensional ultrasonograms, decrease in or lack of flow shown by color Doppler flow imaging, and concentric thickening of the carotid arterial walls. Ultrasonographic mural thickness was the most sensitive indicator of early, latent inflammation.

T-type Ca2+ channel lowers the threshold of spike generation in the newt olfactory receptor cell

Mechanisms underlying action potential generation in the newt olfactory receptor cell were investigated by using the whole-cell version of the patch-clamp technique. Isolated olfactory cells had a resting membrane potential of -70 +/- 9 mV. Injection of a depolarizing current step triggered action potentials under current clamp condition. The amplitude of the action potential was reduced by lowering external Na+ concentration. After a complete removal of Na+, however, cells still showed action potentials which was abolished either by Ca2+ removal or by an application of Ca2+ channel blocker (Co2+ or Ni2+), indicating an involvement of Ca2+ current in spike generation of newt olfactory receptor cells. Under the voltage clamp condition, depolarization of the cell to -40 mV from the holding voltage of -100 mV induced a fast transient inward current, which consisted of Na+ (INa) and T-type Ca2+ (ICa.T) currents. The amplitude of ICa,T was about one fourth of that of INa. Depolarization to more positive voltages also induced L-type Ca2+ current (ICa,L). ICa,L was as small as a few pA in normal Ringer solution. The activating voltage of ICa,T was approximately 10 mV more negative than that of INa. Under current clamp, action potentials generated by a least effective depolarization was almost completely blocked by 0.1 mM Ni2+ (a specific T-type Ca2+ channel blocker) even in the presence of Na+. These results suggest that ICa,T contributes to action potential in the newt olfactory receptor cell and lowers the threshold of spike generation.

Lipid composition of commercial bakers' yeasts having different freeze-tolerance in frozen dough

The lipid composition of some commercial bakers' yeasts having different freeze-sensitivity in frozen dough was investigated to clarify the correlation between their lipid composition and freeze-tolerance. The total lipid content including neutral lipid, free fatty acid, sterol, and phospholipid ranged between 23.0 to 32.2 mg/100 mg protein of the yeasts tested. Phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, and phosphatidylserine were the main phospholipids found in all yeast strains, but no distinct difference in these components between freeze-tolerant and freeze-sensitive strains was observed. Palmitoleic (C16:1), oleic (C18:1), palmitic (16:0), and stearic (C18:0) acids were the major fatty acids present in total lipid and phospholipid, and unsaturation indices of fatty acid in these lipid components were almost equal by the strains. The molar ratios of sterol to phospholipid of freeze-sensitive strains were higher than those of freeze-tolerant strains. The difference in the sterol-phospholipid ratio that influences the fluidity of plasma membranes in yeast cells was supposed to reflect the difference in freeze-sensitivity of bakers' yeast.

Differential regulation of the mcb and emr operons of Escherichia coli: role of mcb in multidrug resistance

The mcb operon (which is responsible for microcin B17 production) and the emr operon (which encodes a multidrug resistance pump) share a common negative regulator, EmrR. Nevertheless, compounds that induce the emr operon repress the mcb operon. The pump dedicated to microcin B17 extrusion can also protect the calls against sparfloxacin and other toxic compounds.

Bacterial degradation of glycol ethers

Assimilation of ethyleneglycol (EG) ethers by polyethyleneglycol-utilizing bacteria was examined. Ethyleneglycol ether-utilizing bacteria were also isolated from soil and activated sludge samples by enrichment-culture techniques. Three strains (4-5-3, EC 1-2-1 and MC 2-2-1) were selected and characterized as Pseudomonas sp. 4-5-3, Xanthobacter autotrophicus, and an unidentified gram-negative, non-spore-forming rod respectively. Their growth characteristics were examined: Pseudomonas sp. 4-5-3 assimilated EG (diethyleneglycol, DEG) monomethyl, monoethyl and monobutyl ethers, DEG, propanol and butanol. X. autotrophicus EC 1-2-1 grew well on EG monoethyl and monobutyl ethers, EG and primary alcohols (C1-C4), and slightly on EG monomethyl ether. The strain MC 2-2-1 grew on EG monomethyl ether, EG, primary alcohols (C1-C4), and 1,2-propyleneglycol (PG). The mixed culture of Pseudomonas sp. 4-5-3 and X. autotrophicus EC 1-2-1 showed better growth and improved degradation than respective single cultures towards EG monomethyl, monoethyl or monobutyl ethers. Intact cells of Pseudomonas sp. 4-5-3 degraded various kinds of monoalkyl ethers, which cannot be assimilated by the strain. Metabolic products were characterized from reaction supernatants of intact cells of Pseudomonas sp. 4-5-3 with EG or DEG monoethyl ethers: they were analyzed by thin-layer chromatography and GC-MS and found to be ethoxyacetic acid and ethoxyglycoxyacetic acid. Also, PG monoalkyl ethers (C1-C4), dipropyleneglycol monoethyl and monomethyl ethers and tripropyleneglycol monomethyl ether were assimilated by polypropyleneglycol-utilizing Corynebacterium sp. 7.

Breakdown of plastics and polymers by microorganisms

The interest in environmental issues is still growing and there are increasing demands to develop materials which do not burden the environment significantly. Awareness of the waste problem and its impact on the environment has awakened new interest in the area of degradable polymers. Biodegradation is necessary for water-soluble or water-miscible polymers because they eventually enter streams which can neither be recycled nor incinerated. It is important to consider the microbial degradation of natural and synthetic polymers in order to understand what is necessary for biodegradation and the mechanisms involved. This requires both biochemical insight and understanding of the interactions between materials and microorganisms. It is now widely requested that polymeric materials come from renewable resources instead of petrochemical sources. The microbial production of polymeric and oligomeric materials is also described.

Phosphorus-31 nuclear magnetic resonance study of energy metabolism in intact slow- and fast-twitch muscles of rats

The time course of the catabolism of phosphorylated metabolites was studied by phosphorus-31 NMR(31P NMR) spectroscopy over a 6-h period after the isolation of rat slow- and fast-twitch muscles, the soleus and the extensor digitorum longus (EDL), respectively, obtained without any muscle damage. In both muscles, rapid depletion of creatine phosphate was followed by a decrease in ATP. These high-energy phosphates disappeared earlier in the soleus than in the EDL. In both muscles, inorganic phosphate (Pi) largely increased in a biphasic pattern, and sugar phosphates (SP) also showed considerable increase. The NMR-visible total phosphates (NTP) increased significantly in the soleus during the latter stage of observation. This increase in NTP was attributed to an increase in Pi. Although the two muscles showed the same initial (7.21) and final (approximately 5.9) intracellular pH (pHi), the pattern of pHi decline differed between these muscles. The rapid fall of pHi in the soleus in the early stage suggests that nonlactic acid acidosis plays a significant role in postmortem changes.

Effects of moderate hypercapnia on hypothermia induced by cold He-O2 in rats

1. Effects of moderate hypercapnia (10% CO2) on rectal temperature, oxygen consumption and body weight loss were examined during and after acute hypothermia induced by cold and helium-oxygen. 2. Hypothermia induction time was reduced significantly by hypercapnia. Rewarming tended to be faster in hypercapnic animals than in normocapnic animals. 3. Hypercapnia significantly reduced body weight loss when measured during hypothermia and during normothermia after rewarming. 4. Oxygen consumption during cooling was decreased by hypercapnia. 5. Exposure to 10% CO2 during cooling may spare energy substrate and favor survival in hypothermia.

Isolation and purification of a rat liver-specific antigen from hepatocyte membrane

A rat liver-specific antigen (RLSA) solubilized with the nonionic detergent non-anonyl-N-methylglucamide was purified through affinity column chromatography with a monoclonal antibody and by high-performance liquid chromatography with a hydroxylapatite column. The purified RLSA showed a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and its molecular weight was determined to be 105,000 in the presence of 2-mercaptoethanol. The antigen was reactive to the Schiff reagent and contained glucosamine, but not galactosamine, indicating that the RLSA is a glycoprotein containing an asparagine-binding type of sugar chain.

Biodegradation of polyethylene glycol by symbiotic mixed culture (obligate mutualism)

Neither Flavobacterium sp. nor Pseudomonas sp. grew on a polyethylene glycol (PEG) 6000 medium containing the culture filtrate of their mixed culture on PEG 6000. The two bacteria did not grow with a dialysis culture on a PEG 6000 medium. Flavobacterium sp. grew well on a dialysis culture containing a tetraethylene glycol medium supplemented with a small amount of PEG 6000 as an inducer, while poor growth of Pseudomonas sp. was observed. Three enzymes involved in the metabolism of PEG, PEG dehydrogenase, PEG-aldehyde dehydrogenase and PEG-carboxylate dehydrogenase (ether-cleaving) were present in the cells of Flavobacterium sp. The first two enzymes were not found in the cells of Pseudomonas sp. PEG 6000 was degraded neither by intact cells of Flavobacterium sp. nor by those of Pseudomonas sp., but it was degraded by their mixture. Glyoxylate, a metabolite liberated by the ether-cleaving enzyme, inhibited the growth of the mixed culture. The ether-cleaving enzyme was remarkably inhibited by glyoxylate. Glyoxylate was metabolized faster by Pseudomonas sp. than by Flavobacterium sp., and seemed to be a key material for the symbiosis.

[Bacteriological and clinical studies of cefoxitin with special reference to anaerobic infections in the patients of abdominal surgery (author's transl)]

Both bacteriological and clinical studies of the effectiveness of cefoxitin (CFX) in the treatment of infections associated with abdominal surgery have been carried out at Tokyo Metropolitan Toshima Hospital from September 1979 through August 1980. The results of these studies are summarized in the following: 1. The clinical isolates from the 29 surgical patients were studied and anaerobes were found in 16 patients (55% of the patients). B. fragilis was found in 11 of the 16 patients (69%) from whom anaerobes were isolated. In all of these patients, aerobes were also isolated--most frequently E. coli or K. pneumoniae. 2. The in vitro antibacterial activity of cefoxitin (CFX) against 83 clinical isolates was compared to that of cephalothin (CET), cefazolin (CEZ) and carbenicillin (CBPC). The activity of CFX against Gram-positive bacteria was generally slightly inferior to that of the other 3 antibiotics. Among the Gram-negative aerobic organisms, CEZ was the most active against E. coli and CFX and CEZ against K. pneumoniae. However, CFX, with MIC's of 0.78-12.5 micrograms/ml, showed the greatest activity against B. fragilis, followed by CBPC, CEZ and CET, in order of decreasing activity. 3. CFX was administered in a 1-hour drip infusion to 3 patients following abdominal surgery, and concentrations of CFX in the serum and the exudate were measured. Peak serum concentrations were obtained at the end of the infusion, with a mean peak level of 97.93 micrograms/ml. Peak concentrations in the exudate were observed 30 to 60 minutes later and varied from 21.10 to 56.25 micrograms/ml. 4. Of the 20 patients administered of CFX, complete clinical and bacteriological data of anaerobic infections were available in 8 patients. The clinical evaluation was 'good' in 7 patients and 'fair' in 1. The bacteriological evaluation was 'eradicated' in 5 patients and 'decreased' in 3. As for side effects, elevations of S-GOT and S-GPT were observed in 4 of the 20 patients received CFX, but these abnormalities might also be attributable to other factors such as underlying disease, surgical intervention etc. No other side effects were found in these patients.