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Objective To investigate the effects of sulfides produced by Porphyromonas gingivalis ( P. gingivalis ) on the corrosion behavior of titanium. Methods Commercially pure titanium disks were mirror-polished and immersed in culture medium (BHI), spent medium after culturing P. gingivalis (BHI-S), and culture medium with P. gingivalis (BHI-P), and incubated aerobically at 37 °C for 3–14 days. Titanium corrosion was evaluated through surface observation (using scanning electron microscope: SEM), color change (ΔE*ab), glossiness (Gs(20°)), chemical composition and state (using X-ray photoelectron spectroscopy: XPS), and titanium release. Results ΔE*ab and Gs(20°) did not significantly differ among specimens placed in test mediums for the study duration (p > 0.05). SEM images of specimens showed no signs of localized or overall corrosion. XPS analysis indicated showed clear titanium metal state peaks on all specimens in addition to sulfide and sulfate on BHI-S and BHI-P specimens. Valency fraction of titanium decomposed from Ti2p spectrum of BHI-S and BHI-P specimens indicated no progression of oxidation. No significant levels of titanium release were found regardless of the mediums’ sulfide content. Results suggested that sulfides produced by P. gingivalis attached on the surface of titanium specimens but did not cause titanium corrosion over the immersion period of 14 days. Significance It is imperative for dental practitioners to be aware of any elements which may influence the clinical success of titanium implants.

The aim of this study was to determine the effects of calcium hydroxide (Ca(OH)2) treatment on bond strength of resin cements to root dentin and retention force of fiber-reinforced composite (FRC) posts. Bovine root dentin was endodontically prepared and treated with Ca(OH)2 for 7 days. Root dentin for bond strength test was adhered to resin-composite with resin cements. For pull-out test, posts consisting of FRC posts and resin-composites were fabricated and cemented to root. Shear bond and pull-out tests were performed using a universal testing machine. No significant differences in bond strength and post retention force were found between Ca(OH)2 treated and untreated groups. Significant differences were found among the cements. A positive correlation was indicated between bond strength of cements and retention force of FRC posts. In conclusion, Ca(OH)2 treatment on root dentin did not affect bond strength of resin cements and retention force of FRC posts.

Based on a survey done recently in Japan, 30 percent of the serious accidents occurred in oral implant surgery were concerned with the mandibular canal and 3/4 of them were related to drilling. One of the reasons lies in the lack of the education system. To overcome this problem, a new educational system focusing on drilling the mandibular trabecular bone has been developed mainly for dental college students in the form of an oral implant surgery training simulator that enables student to sense the reaction force during drilling. On the other hand, the conventional system uses polymeric model. Based on these systems, two approaches were proposed; the evaluation by experienced clinicians using the simulator, and experimental works on the polymeric model. Focusing on the combination of the drilling force sensed and drilling speed obtained through both approaches, the results were compared. It was found that the polymeric models were much softer especially near the mandibular canal. In addition, the study gave us an insight of the understanding in bone quality through tactile sensation of the drilling force and speed. Furthermore, the clinicians positively reviewed the simulator as a valid tool.

Hypophosphatasia (HPP) is an inherited skeletal and dental disease caused by loss-of-function mutations in the gene that encodes tissue-nonspecific alkaline phosphatase (TNALP). The major symptoms of severe forms of the disease are bone defects, respiratory insufficiency, and epileptic seizures. In 2015, enzyme replacement therapy (ERT) using recombinant bone-targeted TNALP with deca-aspartate (D10) motif was approved to treat pediatric HPP patients in Japan, Canada, and Europe. However, the ERT requires repeated subcutaneous administration of the enzyme because of the short half-life in serum. In the present study, we evaluated the feasibility of neonatal ex vivo gene therapy in TNALP knockout (Akp2(-/-)) HPP mice using lentivirally transduced bone marrow cells (BMC) expressing bone-targeted TNALP in which a D10 sequence was linked to the C-terminus of soluble TNALP (TNALP-D10). The Akp2(-/-) mice usually die within 20 days because of growth failure, epileptic seizures, and hypomineralization. However, an intravenous transplantation of BMC expressing TNALP-D10 (ALP-BMC) into neonatal Akp2(-/-) mice prolonged survival of the mice with improved bone mineralization compared with untransduced BMC-transplanted Akp2(-/-) mice. The treated Akp2(-/-) mice were normal in appearance and experienced no seizures during the experimental period. The lentivirally transduced BMC were efficiently engrafted in the recipient mice and supplied TNALP-D10 continuously at a therapeutic level for at least 3 months. Moreover, TNALP-D10 overexpression did not affect multilineage reconstitution in the recipient mice. The plasma ALP activity was sustained at high levels in the treated mice, and tissue ALP activity was selectively detected on bone surfaces, not in the kidneys or other organs. No ectopic calcification was observed in the ALP-BMC-treated mice. These results indicate that lentivirally transduced BMC can serve as a reservoir for stem cell-based ERT to rescue the Akp2(-/-) phenotype. Neonatal ex vivo gene therapy thus appears to be a possible treatment option for treating severe HPP.

Using 15 cricothyroid joint (CT joint) specimens obtained from donated cadavers of elderly individuals, we examined the morphologies of the ceratocricoid ligaments as well as the synovial tissue. The ligaments consistently contained abundant elastic fibers: the fibers tended to be straight on the anterior side in contrast to a mesh-like arrangement on the posterior side. Thick and/or long synovial folds were often evident in the CT joint. The synovial tissue usually contained CD68-positive macrophages, but the positive cells were often restricted to certain parts of the tissue. Factor VIII-positive capillaries were present but few in number, and CD3- or IgM-positive lymphocytes were absent in the synovial tissue. Degenerative changes in the joint cartilage, such as roughness or thinning, were often present, but no cartilage defects were evident. Therefore, in contrast to the small, non-weight-bearing joints of the musculoskeletal system, we considered the degeneration of the CT joint to be a specific, silent form of osteoarthritis. For high-pitched phonation and ossification of the laryngeal cartilage, the CT joint in elderly individuals seemed to maintain its anterior gliding and rotation with the aid of elastic fiber-rich tissues compensating for the loss of congruity between the joint cartilage surfaces.

Surgical success of drilling in oral implantology depends on the sense of force on the fingers or feeling of a dental clinician, which is related to the quality of trabecular bone in the jawbone expressed by apparent mechanical characteristics. As the mechanical properties of trabecular bone depend on the bone volume fraction, microstructure, and many other factors closely related to individual differences, a probabilistic numerical procedure to assess drilling force is proposed. Using a micro-CT-based jawbone model, a first-order perturbation-based stochastic homogenization method was employed to estimate the possible scattering of apparent mechanical properties of the trabecular bone region. The complicated drilling problem was simplified to sequential linear static FEAs, to which the predicted apparent Young’s modulus and shearing moduli in the drilling direction were applied. The FEAs demonstrated that the homogenized mechanical properties showed anisotropy, which might lead to differences in the drilling forces at different drilling angles. The numerically estimated drilling forces were shown by the expected value, 50 %-probability result, and 90%-probability result and revealed that one patient among two or ten patients would probably have poor bone quality. There was a remarkable difference in the drilling forces between the expected value and the 90%-probability result.

There is little or no information about the distribution of elastic fibers in the human fetal head. We examined this issue in 15 late-stage fetuses (crown-rump length, 220-320 mm) using aldehyde-fuchsin and elastica-Masson staining, and we used the arterial wall elastic laminae and external ear cartilages as positive staining controls. The posterior pharyngeal wall, as well as the ligaments connecting the laryngeal cartilages, contained abundant elastic fibers. In contrast with the sphenomandibular ligament and the temporomandibular joint disk, in which elastic fibers were partly present, the discomalleolar ligament and the fascial structures around the pterygoid muscles did not have any elastic fibers. In addition, the posterior marginal fascia of the prestyloid space did contain such fibers. Notably, in the middle ear, elastic fibers accumulated along the tendons of the tensor tympani and stapedius muscles and in the joint capsules of the ear ossicle articulations. Elastic fibers were not seen in any other muscle tendons or vertebral facet capsules in the head and neck. Despite being composed of smooth muscle, the orbitalis muscle did not contain any elastic fibers. The elastic fibers in the sphenomandibular ligament seemed to correspond to an intermediate step of development between Meckel's cartilage and the final ligament. Overall, there seemed to be a mini-version of elastic fiber distribution compared to that in adults and a different specific developmental pattern of connective tissues. The latter morphology might be a result of an adaptation to hypoxic conditions during development.

The aim of this study was to elucidate the association between the bone structure at implant insertion sites and stress distribution around the mandibular canal by means of three-dimensional finite element (3D FE) analysis. Four FE models were created with slice data using micro-computed tomography (micro-CT), and 3D FE analysis was performed. Mechanical analysis showed that the load reached the mandibular canal via the trabecular structure in all FE models. High levels of stress were generated around the mandibular canal when the distance between the mandibular canal and the implant decreased. High stress levels were also observed when cortical bone thickness and bone volume/total volume (BV/TV) were low. Our findings suggest that load is transmitted to the mandibular canal regardless of differences in the thickness of cortical bone or cancellous bone structure, but excessive load may be generated in bone with thin cortical and coarse cancellous structures.

This study assessed the corrosion behavior of titanium in response to sulfide by determining the effects of sulfide concentration and pH over immersion period. Corrosion was evaluated through changes in color, glossiness, surface characterization, and titanium release. Sulfide solutions were prepared in 3 different concentrations with Na2S, each in pH unadjusted (sulfide-alkaline) and pH adjusted to 7.5 (sulfide-neutral). Titanium discoloration increased and glossiness decreased as sulfide concentration and immersion period increased in sulfide-alkaline solutions. Coral-like complexes were observed on the surface of these specimens, which became more pronounced as concentration increased. Small amounts of titanium release were detected in sulfide-alkaline solutions; however, this was not affected by immersion periods. Corrosion was indicated through considerable surface oxidation suggesting the formation of a thick oxide layer. No significant changes in color and glossiness, or titanium release were indicated for titanium specimens immersed in sulfide-neutral solutions indicating that pH had a significant effect on corrosion. Our findings suggest that a thick oxide layer on the titanium surface was formed in sulfide-alkaline solutions due to excessive oxidation.

Muscle directed transduction was demonstrated after the injection of scAAV8-MCK-EGFP. The plasma ALP activity was elevated and sustained at therapeutic level, (>1.0 unit/ml) for at least 3 months of scAAV8-MCK-TNALP-D10 treated Akp2–/– mice. The treated Akp2–/– mice grew well and survived over 3 months with healthy appearance (9/10), while untreated Akp2 −/- mice died within 3 weeks (n=10; P

The anodic steady-state current by a sulfhydryl compound in concentrations about 10 μM at a dialysis membrane covered phthalocyanine-embedded carbon paste electrode (mCoPCPE) completely vanished after the addition of N -ethylmaleimide (NEM) in double concentrations of the sulfhydryl compounds. The concentrations of reduced glutathione (GSH) in whole blood and serum were determined by measuring the current decrease at 150 mV after the addition of NEM in blood solutions of pH 6.8. This method has the advantage of eliminating the procedures for deproteinization. The correlation coefficients between the GSH concentration determined in this method and those by a spectrometric measurement were 0.98 and 0.90 for 10 whole blood and 15 serum samples, respectively

The concentration of fructosamine (FSA) in serum, reflecting the level of blood glucose during two weeks, was determined by an amperometric measurement of H2O2 generated by fructosyl amino acid oxidase (FAOD) after degradation of the serum protein by proteinase K (PK) using a membrane-covered, peroxidase-entrappedand ferrocene -embedded carbon paste electrode. After 20 min degradation of 1/25 diluted serum by 10 U ml-1 PK, FSA was determined by measuring the current increase after the addition of 20 U ml-1 FAOD at pH 9. The ratio of the determined FSA concentration using the current magnitude of N-fructosyl N-Z-lysine (FZL) as a standard to that using diagonostic FSA calibrator as a standard was 0.8. The correlation coefficient between the FSA concentration determined in this method and that by a diagonostic kit based on the spectrometric measurement was 0.97 for 14 serum samples.

A flow injection system for determination of hydrogen peroxide was constructed using a peroxidase/ferrocene-embedded carbon paste (POD-Fc-CP) electrode covered with a membrane. H2O2 was reduced bioelectrocatalytically at 100 mV (versus Ag/AgCl/sat. KCl). A Nafion®-coated cellulose acetate membrane prepared on the surface of water proved to be suitable for the covering membrane. The detection limit (signal : noise = 6) for H2O2 was 200 fmol (10 nM × 20 μl) and the response linearity was retained at least up to 25 μM. The relative standard deviation was 4.4% for 1.0 μM H2O (n = 7). The flow injection system was successfully applied to the determination of glucose and urate in serum by using the corresponding oxidase-immobilized pre-column. The detection limits were 1.5 pmol for glucose and 2 pmol for urate.

NAD(P)H can be detected sensitively with peroxidase (POD)-entrapped and ferrocene (Fc)-embedded carbon paste electrodes in the presence of 1-methoxy-phenazine methosulfate (MPMS + ), where MPMS + catalyzes NAD(P)H oxidation with dioxygen to generate H 2 O 2 . It is essential to cover the POD/Fc-CP electrodes using a suitable membrane with fine mesh in order for the sequential reactions to proceed stoichiometrically. Under suitable conditions, the current response showed a linear relation to the NAD(P)H concentration ranging from 0.1 to 40 μM with a relative standard deviation of 3.4% ( n =6 at 1 μM). The detection limit of NAD(P)H was 40 nM. This method was successfully applied to isocitrate dehydrogenase activity measurements in serum.

By using an unmodified carbon electrode, a sulfhydryl compound can be detected in a potential region more positive than 400 mV vs. SCE, where currents by uric acid, phenols and NADH are also detected. A membrane-covered cobalt phthalocyanine embedded carbon-paste electrode (CoPCP electrode) allows the detection of glutathion (GSH) as low as 2μM at 200 mV with practically no influence from coexisting substances in a biological sample, except for another sulfhydryl compound and ascorbic acid. The GSH contents in twelve samples of yeast extract measured by a CoPCP electrode and those by a photometric method using glyoxalase I are in good agreement with the correlation coefficient of 0.96. The current by GSH increased 3.5 times with the addition of 5, 5'-dithio bis-(2-nitro benzoic acid) (DTNB), since the membrane pearmiability of GSH and TNB formed from DTNB by GSH are quite different from each other. Similarly, the current by yeast extract increased 3.5 times with the addition of DTNB. This result confirms that the current by yeast extract was practically due to GSH. The current due to cysteine was reduced by 13% upon the addition of DTNB.

A peroxidase-entrapped and ferrocene-embedded carbon paste (POD-Fc-CP) electrode allows a highly sensitive detection of H2O2 at levels as low as 10 nmol/L with practically no interference by coexisting substances, turbidity or coloration of samples. The electrode was applied to the amperometric determination of high-density lipoprotein (HDL)-cholesterol in a very small volume (1–2 μL) using polyethylene glycol (PEG)-modified cholesterol esterase and cholesterol oxidase without prior precipitation or separation of HDL. PEG-modified enzymes exhibit a selective activity toward HDL-cholesterol in the presence of dextran sulphate and MgCl2 to generate H2O2. The HDL-cholesterol concentrations of human serum samples determined by this method showed a good correlation with those determined by an ordinary spectrophotometric method using PEG-modified enzymes and peroxidase or by a conventional precipitation method.

ポリエチレングリコール(PEG)修飾したコレステロールエステラーゼ及びコレステロールオキシダーゼを血清希釈液に作用させて生成するH2O2を,ペルオキシダーゼを固定した膜被覆フェロセン練り込みカーボンペースト電極で直接検出することにより,簡便にリポタンパク(LP)-コレステロール(CR)値の測定ができた.更に,デキストラン硫酸ナトリウムとMgCl2等のLP凝集剤濃度並びにPEG修飾酵素量を最適化することにより,高密度リポタンパク(HDL)-CR値を直接測定できることを明らかにし,PEG修飾酵素並びに凝集剤のHDLとそれ以外のLP間の識別に関して考察した.又,界面活性剤を利用することによりHDL-CR値と総CR値を直接分別測定できることを示した.17種の血清試料のHDL-CR値を本法で評価したところ,その値は,PEG修飾酵素反応を利用する市販の分光測定キットで得られたHDL-CR値,及び沈殿法で得たHDL画分の電流測定から得られたHDL-CR値とよく相関した.

Peroxidase (POD) was entrapped on a ferrocene (Fc)-embedded carbon paste (CP) electrode with a dialysis membrane to construct a POD-Fc-CP electrode for the reductive amperometric determination of hydrogen peroxide (H2O2). The electrode allowed the H2O2 detection down to 10 nM (under stirring), with a linear relation up to 15 μM, and without change of the response over one month. On the other hand, a plastic-formed carbon (PFC) electrode can donate electrons to POD without any specific mediator. The POD-entrapped PFC electrode produced a relative current density of 24% compared with the POD-Fc-CP electrode. The reductive detection of H2O2 with the POD-Fc-CP electrode was applied to the determination of creatinine and creatine in serum and urine using sarcosine oxidase, creatine amidinohydrolase, and creatinine amidohydrolase as the reagents. The significance of the membrane-covered POD-Fc-CP electrode in the coupling of the oxidase reaction is also discussed.

The mediobasal segment (S7) of the right lung has been considered to correspond to the cardiac lobe generally seen in mammals. To investigate fetal development of the right mediobasal segmental bronchus (B7), we examined paraffin-embedded serial sections of 15 embrynic and fetal lungs at 7-8 weeks (serial sections) as well as semiserial sections of 8 fetuses at 15-18 weeks (semiserial sections). All of the smaller specimens did not contain B7, but 2 of the 8 larger specimens carried B7: one was found in the immediately anterior side of the inferior pulmonary vein, while in the other, the subdivisions (B7a, B7b) were overriding the vein. Although the incidence might be underestimated because of observations using semiserial sections, the B7 was most likely to develop secondarily during a period from 8 to 15 weeks. Fetal topographical changes (mainly, the descent) of the middle lobe and the inferior pulmonary vein might relate with the secondarily budding of B7. The present result does not reduce a clinical relevance of B7 as a segmental bronchus of the lung segment system.

Yttrium Iron Garnet (YIG) granular composite materials in the high particle content show negative permeability spectra under external magnetic field in the microwave range. In this study, the complex permeability spectra (μr = μr' - jμr") of 56.2 vol.% YIG composite under external dc field have been analyzed using a permeability dispersion formula having the domain wall (DW) vibration and the gyromagnetic spin rotation susceptibilities, χd and χs. Frequency dispersion parameters of the DW and spin resonances were evaluated. With increasing dc external field, static susceptibility of the two components decreases and the resonance frequencies shift toward higher frequency range. The DW resonance contributes to the negative permeability as well as the spin resonance up to about 600 Oe. Above 600 Oe, DW contribution becomes very small; spin resonance contribution becomes dominant. The variation of the maximum frequency in the imaginary part of susceptibilities with damping factors has fairly good agreement with the theoretical calculation.

To avoid procedural accidents during/after oral implant surgery in a jawbone (e.g., perforation of the lingual side due to an inadequate drilling angle or scratching the mandibular canal), it is important for dentists to develop skilled drilling techniques. We have developed a stochastic multi-scale prediction of apparent elastic moduli of the jawbone with modified first-order perturbation-based stochastic homogenization in which individual differences of drilling properties relating to bone quality can be evaluated with a force-sensitive device. To establish drilling properties in various types of jawbone and the perforation case, and for drill diameters, we propose an original computational method that avoids procedural accidents by defining the drilling angle as a parameter and quantifying individual differences and the inner distribution of bone quality in several jawbones as a drilling force. Three samples demonstrated that drilling forces changed depending on the trabecular structure, with the drilling force changing little around the mandibular canal and increasing just before perforation. Drilling force also depended on the drill diameter but did not always match its size. Estimated drilling forces of the expected value and 50% and 90% probability results suggested prominent differences in drilling properties. This information enables dentists to develop a skillful surgical technique.

Hypophosphatasia (HPP) is an inherited disease caused by genetic mutations in the gene encoding tissue-nonspecific alkaline phosphatase (TNALP). This results in defects in bone and tooth mineralization. We recently demonstrated that TNALP-deficient (Akp2 (-/-) ) mice, which mimic the phenotype of the severe infantile form of HPP, can be treated by intravenous injection of a recombinant adeno-associated virus (rAAV) expressing bone-targeted TNALP with deca-aspartates at the C-terminus (TNALP-D10) driven by the tissue-nonspecific CAG promoter. To develop a safer and more clinically applicable transduction strategy for HPP gene therapy, we constructed a self-complementary type 8 AAV (scAAV8) vector that expresses TNALP-D10 via the muscle creatine kinase (MCK) promoter (scAAV8-MCK-TNALP-D10) and examined the efficacy of muscle-directed gene therapy. When scAAV8-MCK-TNALP-D10 was injected into the bilateral quadriceps of neonatal Akp2 (-/-) mice, the treated mice grew well and survived for more than 3 months, with a healthy appearance and normal locomotion. Improved bone architecture, but limited elongation of the long bone, was demonstrated on X-ray images. Micro-CT analysis showed hypomineralization and abnormal architecture of the trabecular bone in the epiphysis. These results suggest that rAAV-mediated, muscle-specific expression of TNALP-D10 represents a safe and practical option to treat the severe infantile form of HPP.

新炭素素材(plastic formed carbon)を使用したPFC電極に透析膜を被覆した電極を用いて還元型ニコチンアミドアデニンジヌクレオチド(NADH)の定常状態での酸化電流値を測定すると,pH5～9の溶液では500～300mV(対SCE)で限界値に達した.その電流値はNADH濃度と2.5～1500μMの間で直線比例した.pH7.8で200μM NADHを5回測定したときの相対標準偏差は2.6%であった.NADH,アスパラギン酸,2-オキソグルタル酸,リンゴ酸デヒドロゲナーゼ及び乳酸デヒドロゲナーゼ(LD)を含むトリス緩衝液(pH7.8)に血清を添加しNADHの時間変化より血清中のアスパラギン酸トランスアミナーゼ(AST)活性を測定した.UV法による結果との相関はr=0.996(n=17)であった.AST測定と同様に,NADH,アラニン,2-オキソグルタル酸,LDを含むpH7.5のトリス緩衝液に血清を添加しアラニントランスアミナーゼ(ALT)活性を測定した.UV法による結果との相関はr=0.992(n=17)であった.

The magnitude of the steady-state current by a sulfhydryl compound at a dialysis membrane (molecular cut off: 5000) coverd cobalt phthalocyanine-embedded electrode was inversly proportional to the molecular weight. That is, the currents by 1 μM glutathione (GSH), glutamylcysteine and cysteine at 200 mM and at pH 8.3 were 0.07, 0.14 and 0.39 nA, respectively. The activity of γ-glutamyltransferase (γ-GT) in serum was determined by measuring the current increase for a given time due to the degradation of GSH to cysteinylglysine in a 0.1 M tris buffer of pH 8.3 containing 1.2 mM GSH, 50 mM glysylglysine and 5 mM EDTA. The activities of γ-GT determined amperometrically using GSH as a substrate for sixteen serum samples were in good agreement with those determined by a colorimetric method using γ-glutamy1-3-carboxy-4-nitroanilide (Glucana) a as substrate (r=0.98).

Ozonation of seawater produces residual oxidants which do not occur in fresh water. Most of them are bromine compounds, such as HBrO. In this study, the acute toxicity of these ozone-produced oxidants (OPO) to eggs and larvae of Japanese whiting, Sillago japonica, was tested under static-flow conditions of water with a temperature of 21.6 ?? 23.1°C, salinity 33.4 ?? 34.4‰, and pH 8.2 ?? 8.3. In analysis of the results, initial OPO concentrations measured as total residual chlorine were given importance since OPO disappeared gradually through contact with eggs or larvae. Based on the initial OPO concentration and normal survival rate, LC50's were estimated as 0.18mgC1/l (after 38h) and 0.23mgC1/l (after 24h) for eggs and larvae, respectively. Eggs were found to delay hatching. Many eggs exposed to near sublethal OPO stayed unhatched beyond the expected hatching time. After that, the death of these eggs was observed.

1,4-ベンゾキノンを練り込んだグラファイトペースト表面にオリゴ糖デヒドロゲナーゼを固定した電極を用いるとグルコース及びオリゴ糖の酸化電流が得られ,単位濃度当たりの電流値はグルコース,マルトース,マルトトリオース,マルトペンタオースの順に減少した.マルトペンタオースを基質にしてアミラーゼを添加するとマルトースとマルトトリオースが生成するので,電流値が増大し,単位時間当たりの電流値変化はアミラーゼ量に比例した.しかしアミラーゼ活性の低い血清の測定ではベース電流及び測定ごとの変動の大きさが無視できない値となった.a-グルコシダーゼを添加して,マルトース,マルトトリオースを更にグルコースにまで分解させると,単位時間当たり7倍大きい電流値変化が測定され,実分析に十分な測定感度となった.本法で得られた血清アミラーゼ活性値と,臨床的に使用されている比色法による値との相関係数はr=0.974,(n=13)であった.

Anodic current at a steady-state by uric acid was obtained reproducibly at a dialysis membrane-covered graphite paste electrode and was independent of the compounds in serum except ascorbic acid, when measured at a relatively negative potential in acidic solutions. The difference in magnitude of current by serum solution between 0.35 V and 0.50V was proportional to the concentration of uric acid and was independent of the concentration of ascorbic acid at pH

In order to examine effects of seawater temperature on the growth of Porphyra foliose thalli, outdoor raceway tanks with circulating water were newly designed, and provided the experimental condition simulating Nori cultivation farms in the sea. Frozen seed nets of Porphyra yezoensis form. narawaensis were set in the raceway tanks. During the period of the two experiments, December in 1985 and February in 1986, mean seawater temperature ranged from 8.0 to 23.4°C. Standing crop of foliose thalli increased normally at 10-17°C, but the increase rate of standing crop lessened at the temperature higher and lower beyond these limits. Visible absorption spectra of living foliose thalli, indicating concentrations of photosynthetic pigments, did not vary much within the range of seawater temperature from 8 to 20°C. The optimum seawater temperature for the growth of Porphyra foliose thalli ranged from 10 to 17°C in the raceway tanks. This temperature range confirmed results obtained through in vitro experiments but was higher than that in Nori cultivation farm.

A mediated amperometric enzyme electrode, which was constructed by immobilizing oligosacharide dehydrogenase behind a dialysis membrane on the surface of a carbon paste electrode containing p -benzoquinone, showed a current response to d -xylose, d -galactose, d -mannose, lactose, maltose, maltotriose, maltopentaose and maltohexaose. The sensitivity of the current response to these carbohydrates was dependent on the kinetics of the immobilized enzyme reaction and/or the permeation rate of the substrate through the dialysis membrane. Hence the sensitivity could be varied by controlling the amount of the immobilized enzyme and the thickness of the dialysis membrane. The time dependence of the current response ofthe enzyme electrode with a large amount of the immobilized enzyme and a thicker dialysis membrane could be explained by an equation describing diffusion of the substrate in the membrane. The enzyme electrode was used to measure lactose in milk and to assay α-amylase in standard serum.

Sodium nitrite in acidic solutions produces a voltammetric cathodic wave starting from −0.5 V (vs. Ag/AgCl) in the presence of a small amount of cytochrome c (cyt c), in which cyt c works as a catalyst for the electroreduction of nitric oxide produced by the disproportionation reaction of nitrite. Hemoglobin (Hb) and myoglobin (Mb) are also effective as catalysts for this type of reaction.