Extrahepatic Expression of Apolipoprotein A-II in Mouse Tissues: Possible Contribution to Mouse Senile Amyloidosis

Apolipoprotein A-II (apoA-II), an apolipoprotein in serum high-density lipoprotein, is a precursor of mouse senile amyloid fibrils. The liver has been considered to be the primary site of synthesis. However, we performed nonradioactive in situ hybridization analysis in tissue sections from young and old amyloidogenic (R1.P1- Apoa2 c ) and amyloid-resistant (SAMR1) mice and revealed that other tissues in addition to the liver synthesize apoA-II. We found a strong hybridization signal in the basal cells of the squamous epithelium and the chief cells of the fundic gland in the stomach, the crypt cells and a small portion of the absorptive epithelial cells in the small intestine, the basal cells of the tongue mucosa, and the basal cells of the epidermis and hair follicles in the skin in both mouse strains. Expression of apoA-II mRNA in those tissues was also examined by RT-PCR analysis. Immunolocalization of apoA-II protein also indicated the cellular localization of apoA-II. ApoA-II transcription was not observed in the heart. Amyloid deposition was observed around the cells expressing apoA-II mRNA in the old R1.P1- Apoa2 c mice. These results demonstrate that the apoA-II mRNA is transcribed and translated in various extrahepatic tissues and suggest a possible contribution of apoA-II synthesized in these tissues to amyloid deposition.

Synthesis of highly refractive and highly fluorescent rigid cyanuryl polyimines with polycyclic aromatic hydrocarbon pendants

A series of rigid cyanuryl polyimines, polyguanamines (PGs) bearing polycyclic aromatic hydrocarbon pendants were successfully synthesized from 2-substituted 4,6-dichloro-1,3,5-triazine and aromatic diamine monomers.

Determination of passive-sampled sulphur dioxide in ambient air as sulphate ion by flow injection analysis with an in-line reaction column

A modified FIA method was developed for the determination of sulphur dioxide (SO(2)) in ambient air collected by a passive sampler. SO(2) was oxidized by hydrogen peroxide and determined as sulphate ion in solution. Barium-dimethylsulfoazo-III complex was used as spectrophotometric reagent. A BaSO(4)-immobilized in-line reaction column was introduced into the flow system to increase the sensitivity and reproducibility. An in-line cation exchange column was used to eliminate triethanolamine, which was used as the absorbent reagent in the passive sampler. Sulphate ions can be analyzed in the range of 0.08-10.00 mg l(-1) with the R.S.D. less than 1.6% at the rate of 15 samples h(-1). It was satisfactory to apply this method to the analysis of sulphur dioxide in ambient air and the results agreed with those obtained by ion chromatography.

Cumulative ecological impacts of two successive annual treatments of imidacloprid and fipronil on aquatic communities of paddy mesocosms

Agricultural landscapes, including paddies, play an important role in maintaining biodiversity, but this biodiversity has been under the threat of toxic agro-chemicals. Our knowledge about how aquatic communities react to, and recover from, pesticides, particularly in relation to their residues, is deficient, despite the importance of such information for realistic environmental impact assessment of pesticides. The cumulative ecological impacts on aquatic paddy communities and their recovery processes after two successive annual applications of two systemic insecticides, imidacloprid and fipronil, were monitored between mid-May and mid-September each year. The abundance of benthic organisms during both years was significantly lower in both insecticide-treated fields than in the controls. Large-impacts of fipronil on aquatic arthropods were found after the two years. Growth of medaka fish, both adults and their juveniles, was affected by the application of the two insecticides. A Principal Response Curve analysis (PRC) showed the escalation and prolongation of changes in aquatic community composition by the successive annual treatments of each insecticide over two years. Residues of fipronil in soil, which are more persistent than those of imidacloprid, had a high level of impact on aquatic communities over time. For some taxonomic groups, particularly for water surface-dwelling and water-borne arthropods, the second annual treatment had far greater impacts than the initial treatment, indicating that impacts of these insecticides under normal use patterns cannot be accurately assessed during short-term monitoring studies, i.e., lasting less than one year. It is concluded that realistic prediction and assessment of pesticide effects at the community level should also include the long-term ecological risks of their residues whenever these persist in paddies over a year.

[The utility of coronary magnetic resonance angiography in children under six years of age with Kawasaki disease]

BACKGROUND

To follow up coronary arterial lesions due to Kawasaki disease (KD) using noninvasive magnetic resonance coronary angiography (MRCA), we studied a method to improve the quality of images in young children.

METHOD

Non-contrast enhanced, free-breathing MRCA with the vector ECG gating real-time navigator-echo 3D steady-state free precession (SSFP) technique was performed using a 1.5-T whole-body MR imaging system (Philips) in 68 children with KD aged 4 months to less than 6 years. A flex medium coil was used. Data were acquired with a 180 to 200 mm field of view (FOV) and were reconstructed with a 512 x 360 matrix. Patients were sedated during the examination. Many parameters were optimized for each patient; i.e., FOV, acquisition delay, turbo-field echo-factor, navigator-window and resolution, which resulted in the acquisition of high-resolution and high-signal images of the coronary arteries.

RESULTS

These conditions remarkably improved not only the quality of the images, but also the detection rate of coronary arterial segments (American Heart Association) in the children. The rates were as follows; Segments 1 (97%), 2 (97%), 3 (87%), 4 (66%), 5 (97%), 6 (96%), 7 (83%), 8 (56%), 9 (53%), 10 (21%), 11 (96%), 12 (29%), 13 (93%), 14 (54%), and 15 (65%).

CONCLUSION

MRCA is a useful method for evaluation coronary aneurysms from the early stages of KD, even in infants and small children.

Simultaneous determination of D-lactic acid and 3-hydroxybutyric acid in rat plasma using a column-switching HPLC with fluorescent derivatization with 4-nitro-7-piperazino-2,1,3-benzoxadiazole (NBD-PZ)

A highly sensitive method for the determination of D-lactic acid and 3-hydroxybutyric acid (3-HB) in rat plasma was developed using high-performance liquid chromatography with octadecylsilica (ODS) connected to a chiral column. At first, (D + L)-lactic acid and 3-HB in the plasma were derivatized with a fluorescent reagent, 4-nitro-7-piperazino-2,1,3-benzoxadiazole (NBD-PZ), separated on the ODS column and determined fluorimetrically at 547 nm with 491 nm of excitation wavelength. During the separation step on the ODS, the peak fraction of (D + L)-lactate derivative was introduced directly to a phenylcarbamoylated beta-cyclodextrin chiral column by changing the flow of the eluent via a six-port valve. Then, D-lactate derivative was separated enantiomerically from the L-lactate derivative, and the enantiomeric ratio was determined from the chromatogram. Intra- and inter-day accuracy values for the determination of D-lactic acid in 10 microL of rat plasma were 97.8-109.2 and 98.4-109.9%, and those for 3-HB were 99.8-108.4 and 99.8-103.8%, respectively. The intra- and inter-day precision values were within 4.6 and 5.1% for D-lactic acid, and 2.7 and 2.4% for 3-HB, respectively. The detection limits for D-lactic acid and 3-HB were approximately 2.0 and 0.04 microM, respectively (signal-to-noise ratio 3). The proposed method was applied to the plasma of diabetic rats induced by intraperitoneal administration of streptozotocin, and the significant increases of both D-lactic acid and 3-HB concentrations were observed in the diabetic rats as compared to the normal rats.

Fluorescent derivatization of nitrite ions with 2,3-diaminonaphthalene utilizing a pH gradient in a Y-shaped microchannel

The on-chip derivatization of nitrite ions with 2,3-diaminonaphthalene (DAN) utilizing a pH gradient formed in a Y-shaped microchannel was investigated. Nitrite ions react with DAN at low pH, and strongly fluoresced at high pH. Therefore, a reaction at low pH followed by the addition of a strong alkaline solution is the usual procedure in a batch scheme. However, a strong alkaline solution, like an NaOH aqueous solution, erodes the wall of the microchannels in substrates made of glass or polymers, and has not been considered suitable for use in microchannels. We first investigated the derivatization reaction and fluorescent properties of nitrite ions with DAN. We found that the on-chip fluorescent derivatization reaction and detection without the addition of an alkaline solution is possible by controlling the pH values of the nitrite solution and the DAN solution to form a suitable pH gradient by utilizing a buffering effect of triethanolamine solution, which is used as an NO2 gas-absorption medium. These results have suggested the feasibility of novel reaction schemes which can provide the desired products due to a controlled pH gradient in the microchannels, as well as the possibility of an on-site monitoring microchip device for ambient NO2.

General synthetic route to chiral flexible biphenylphosphine ligands: the use of a chiral additive enables the preparation and observation of metal complexes incorporating the enantiopure form

[figure: see text] The enantio- and diastereomerically pure metal complex of a chirally flexible BIPHEP ligand is obtained through enantiomer-selective coordination of a BIPHEP-Ru complex with enantiopure 3,3'-dimethyldiaminobinaphthyl, DM-DBN, followed by epimerization of the remaining BIPHEP-Ru enantiomer to complex with DM-DABN. Thus, an efficient and general synthetic route to a variety of substituted BIPHEP ligands from biphenol and observation of the enantiomerically pure BIPHEP ligands in their Ru(II) complexes are described.

A new fluorimetric method for the determination of formaldehyde in air based on the liquid droplet sampling technique

A new, simple, sensitive, selective and in-field fluorimetric method for the determination of formaldehyde is proposed. The reaction of formaldehyde with hydralazine in acidic medium, heating on a boiling water-bath for 25 min, produces s-triazolo[3,4-a]phthalazine (Tri-P). The fluorescence intensity of the product formed (Tri-P) was determined at lambda em = 389 nm with lambda ex = 236 nm. The fluorescence intensity is linear over a formaldehyde concentration range of 1.2-33.0 micrograms l-1. The proposed method was applied successfully to the determination of formaldehyde sampled from the atmosphere using the liquid droplet technique. Formaldehyde vapour in a wind tunnel was produced by a mean of permeater. A linear curve was obtained between the concentration in the wind tunnel and that in the droplet. The detection limit for formaldehyde was 2.0 micrograms l-1 with RSDs varying from 3 to 12% in ambient air, using a droplet correction solution (boric acid and hydralazine). The effect of interfering substances on the determination shows that most cations and anions did not interfere. The results obtained were satisfactory compared with a reference method.

Sensitive spectrophotometric determination of nitrite in human saliva and rain water and of nitrogen dioxide in the atmosphere

A new simple, sensitive, and selective spectrophotometric method was developed for the determination of nitrite. The method is based on the reaction of nitrite with sulfathiazole in acidic medium to form a diazonium cation, which is subsequently coupled with N-(1-naphthyl)ethylenediamine dihydrochloride to form a highly stable, violet azo dye. The reaction product has an absorption maximum at 546 nm and obeys Beer's law over a nitrite range of 0.054-0.816 microg/mL. The molar absorptivity of the colored compound is 4.61 x 10(4) L/mol x cm). The detection limit is 12.1 microg/L. The relative standard deviation is 0.85% for 5 determinations of nitrite at 0.27 microg/mL. The reproducibility and validity of the proposed method are discussed in the present paper. The simplicity of the method is demonstrated by the high stability of the azo-dye product as well as the short time required for its complete formation in a reaction at room temperature without pH control or extra extraction. The sensitivity of the method is shown by the successful determination of nitrite in human saliva and rain water, and of nitrogen dioxide in the atmosphere. The results compare favorably with those obtained by the reference method. The selectivity of the method is indicated by its freedom from most interferences, even at high concentrations of nitrate (500 microg/mL).

Asymmetric Activation

While nonracemic catalysts can generate nonracemic products with or without the nonlinear relationship in enantiomeric excesses between catalysts and products, racemic catalysts inherently give only a racemic mixture of chiral products. Asymmetric catalysts, either in nonracemic or racemic form, can be further evolved into highly activated catalysts with association of chiral activators. This asymmetric activation process is particularly useful in racemic catalysis through selective activation of one enantiomer of the racemic catalyst. Recently, a strategy whereby a racemic catalyst is selectively deactivated by a chiral additive has been reported to yield nonracemic products. However, reported herein is an alternative and conceptually opposite strategy in which a chiral activator selectively activates, rather than deactivates, one enantiomer of a racemic chiral catalyst. The advantage of this activation strategy over the deactivation counterpart is that the activated catalyst can produce a greater enantiomeric excess in the products-even with the use of a catalytic amount of activator relative to chiral catalyst-than that attained by the enantiomerically pure catalyst on its own. Therefore, asymmetric activation could provide a general and powerful strategy for not only the use of atropisomeric, racemic ligands but also chirally flexible and proatropisomeric ligands without enantiomeric resolution!

Ion chromatographic method for simultaneous determination of nitrate and nitrite in human saliva

A simple, rapid, accurate and sensitive method is proposed for the simultaneous determination of nitrite and nitrate in human saliva. Nitrite and nitrate present in the human saliva were determined after 10- to 100-fold dilution with ion chromatography (IC) using suppressed conductivity detection. Recoveries of nitrite and nitrate were found to be ranged between 95% and 101%. The method was linear (r2=0.9991) over the concentration working range. The detection limits were found to be 15.0 microg/l and 33.5 microg/l, for nitrite and nitrate, respectively. Ions that are present in human saliva and several other ions that are suspected to affect nitrite and nitrate determination were checked. It was found that most of the ions did not cause any interference in the determination. The method allows simultaneous determination of nitrite and nitrate in human saliva.

Optical rotation per refractive index unit, or enantiomeric (e) factor, for screening enantioselective catalysts through asymmetric activation or carbohydrates

A super high-throughput screening (SHTS) system can be constructed by combining high-performance liquid chromatography (HPLC), optical rotation (OR), and refractive index unit (RIU) to determine not only the enantioselectivity of the addition of diethylzinc to an aliphatic aldehyde catalyzed by a binaphthol-zinc complex through asymmetric activation with chiral Schiff bases, but also the enantiopurity of a carbohydrate. The enantiomeric (e) factor, which we define here as optical rotation per refractive index unit, is linearly related to the percent enantiomeric excess (%ee) and is independent of concentration.

Enantiomer-selective activation of racemic catalysts

Asymmetric catalysts can be evolved into highly activated catalysts by association with chiral activators. This asymmetric activation process is particularly useful in racemic catalysis through selective activation of one enantiomer of the racemic catalysts. Recently, a strategy whereby a racemic catalyst is selectively deactivated by a chiral additive has been reported to yield nonracemic products. However, we have reported a strategy that is an alternative to asymmetric catalysts but is conceptually opposite, in which a chiral activator selectively activates rather than deactivates one enantiomer of a racemic chiral catalyst. The advantage of this activation strategy over the deactivation counterpart is that the activated catalyst can produce a greater enantiomeric excess (x(act)% ee) in the products than the ee attained by the enantiomerically pure catalyst on its own. Therefore, 'asymmetric activation' could provide a general and powerful strategy for the use of not only atropisomeric and, hence, racemic ligands but also chirally flexible and 'pro-atropisomeric' ligands without enantiomeric resolution!

CT-Guided acetic acid injection therapy for aldosterone-producing adrenocortical adenoma: a preliminary report of three cases

We reported the preliminary outcomes of CT-guided percutaneous injection therapy for aldosterone-producing adrenocortical adenoma (APA). Five sessions of injection therapy, 4 percutaneous acetic acid injections (PAI) and 1 percutaneous ethanol injection (PEI) were performed in 3 patients with APA. A small amount of acetic acid or ethanol solution was injected via a needle placed precisely inside the tumor. The procedure was frequently monitored by repetitive CT scanning. The follow-up period ranged from 5 to 27 months. After the treatment, hypertension was normalized or controlled by a low dose of conventional anti-hypertensive drug. In 2 of 3 cases the plasma aldosterone levels were normalized. Although temporary symptoms of alcoholic intoxication were observed in the single session of PEI, the 4 sessions of PAI were associated with no adverse symptoms or complications. Although this study covers only short-term results in 3 patients, CT-guided PAI appears to be a safe and effective treatment and may be a promising alternative as a simple and far less invasive therapy for APA.

Plant cis-acting regulatory DNA elements (PLACE) database: 1999

PLACE (http://www.dna.affrc.go.jp/htdocs/PLACE/) is a database of nucleotide sequence motifs found in plant cis-acting regulatory DNA elements. Motifs were extracted from previously published reports on genes in vascular plants. In addition to the motifs originally reported, their variations in other genes or in other plant species in later reports are also compiled. Documents for each motif in the PLACE database contains, in addition to a motif sequence, a brief definition and description of each motif, and relevant literature with PubMed ID numbers and GenBank accession numbers where available. Users can search their query sequences for cis-elements using the Signal Scan program at our web site. The results will be reported in one of the three forms. Clicking the PLACE accession numbers in the result report will open the pertinent motif document. Clicking the PubMed or GenBank accession number in the document will allow users to access to these databases, and to read the of the literature or the annotation in the DNA database. This report summarizes the present status of this database and available tools.

[Common bile ductal carcinoma, hilar cholangiocarcinoma: evaluation with MR cholangiography]

Recently, imaging of bile ductal carcinoma has been improved by new techniques such as MR cholangiography. Cancer invasion along the bile duct has been demonstrated by MR cholangiography. MR cholangiography will be useful for obtaining more detailed information in the diagnosis and staging of common bile ductal carcinoma, hilar cholangiocarcinoma.

Malignant lymphoma of the gingiva: MR evaluation

PURPOSE

Our purpose was to document the MR imaging findings of malignant lymphoma of the gingiva.

METHODS

Five patients with histologically proved malignant lymphoma of the gingiva were studied by MR imaging. The MR images were analyzed for tumor size, extent, and signal characteristics, bone involvement, and associated cervical lymph node enlargement.

RESULTS

Clinical examination tended to underestimate the size of lymphomatous lesions. The signal intensity of the lesions was isointense to hyperintense relative to muscle on noncontrast T1-weighted images and showed variable contrast enhancement patterns. On T2-weighted images, signal intensity was isointense to hypointense relative to the oral mucosa. In one case, the mass extended to the submandibular space; in the remaining cases, the masses were limited to the gingiva and the adjacent bone. MR imaging revealed that gingival lymphomatous masses were broad-based along the mandible or maxilla and eroded through the cortex into the marrow space, but the cortex was still recognizable. No nodal involvement was noted in any of the patients with malignant lymphoma.

CONCLUSION

The signal characteristics of gingival lymphoma overlap those of other tumors. The cortex separating marrow involvement from the broad-based gingival mass generally appears to be permeated with small erosions but is still recognizable.

Squamous cell carcinoma of the oral cavity: MR findings and value of T1-versus T2-weighted fast spin-echo images

OBJECTIVE

The purposes of this study were to describe the characteristics of squamous cell carcinomas of the oral cavity on unenhanced and contrast-enhanced T1-weighted spin-echo (SE) MR images and unenhanced T2-weighted fast spin-echo (FSE) MR images and to determine which sequences best delineate the margins and extent of the tumors.

MATERIALS AND METHODS

Forty-four patients with proved squamous cell carcinoma of the oral cavity (tongue, 24; floor of mouth, seven; buccal mucosa, four; maxillary gingiva, two; and mandibular gingiva, seven) underwent unenhanced axial T2-weighted FSE MR imaging and unenhanced and enhanced axial and coronal T1-weighted SE MR imaging. The appearance, signal characteristics, and extent of the tumors were assessed, and the delineation of tumor margins with each sequence or combination of sequences was evaluated by use of a grading system ranging from 1 (poor) to 3 (excellent). Three patients were excluded because of artifacts on the MR images caused by dental restorations.

RESULTS

Tumors in all 41 patients were depicted on unenhanced T1-weighted SE images, but in four patients, tumors were not visible on T2-weighted FSE images. Except for tumors that invaded the maxillary gingiva, the tumors generally had homogeneous, low signal intensity on unenhanced T1-weighted images and nonhomogeneous, high signal intensity on T2-weighted FSE images. All tumors showed enhancement, 76% with a nonhomogeneous appearance. The delineation of tumor margins was excellent (grade 3) in 31 cases and fair (grade 2) in 10 cases. The highest rating was given for unenhanced T1-weighted images in 10 cases, for contrast-enhanced T1-weighted images in 10 cases, for the combination of both unenhanced and contrast-enhanced T1-weighted images in 18 cases, for the combination of unenhanced T1-weighted and T2-weighted FSE images in five cases, and for T2-weighted FSE images in one case. In three cases, the highest rating was given for both combinations of pulse sequences.

CONCLUSION

An unenhanced T1-weighted sequence should be used as the basic pulse sequence for MR imaging of tumors of the oral cavity. When tumor margins are not clearly delineated with this sequence, T2-weighted FSE and contrast-enhanced T1-weighted sequences should be added. Although both of these sequences provide supplementary information, the contrast-enhanced T1-weighted sequence is more useful in delineating the margins and extent of tumors than is the T2-weighted FSE sequence.

Purification of geranylgeranyl diphosphate synthase from bovine brain

Geranylgeranyl diphosphate (GGPP) synthase was purified to homogeneity from bovine brain in a one-step affinity column procedure. For the construction of the affinity column, a farnesyl diphosphate (FPP) analog, O-(6-amino-1-hexyl)-P-farnesylmethyl phosphonophosphate, was synthesized and linked to the spacer of the matrix of Affigel 10 via the amino group. The native enzyme appeared to be homooligomer (150-195 kDa) with a molecular mass of the monomer of 37.5 kDa. The pI for the enzyme was 6.2. The Km values for dimethylallyl diphosphate (DMAPP), geranyl diphosphate (GPP) and FPP were estimated to be 33 microM, 0.80 microM and 0.74 microM, respectively. The Km value for isopentenyl diphosphate (IPP) in the presence of both IPP and FPP mixture was 2 microM. The ratio of the reaction velocity for formation of GGPP from DMAPP, GPP or FPP was 0.004:0.145:1. The intermediate FPP was formed in the reaction with GPP as an allylic primer. FPP synthase catalyzing the formation of FPP from DMAPP and IPP was also purified to homogeneity from the same organ by a similar affinity chromatography procedure using a GPP analog, O-(6-amino-1-hexyl)-P-geranylmethyl phosphonophosphate as a ligand. The enzyme was a homodimer with a monomeric molecular mass of 40.0 kDa. These results indicate that GGPP, a lipid precursor for the biosynthesis of a majority of prenylated proteins, is synthesized from DMAPP and IPP by the action of FPP synthase catalyzing the reactions C5-->C15 followed by the action of GGPP synthase catalyzing the reaction C15-->C20.

Phosphorylation of farnesol by a cell-free system from Botryococcus braunii

Farnesol was incorporated into squalene as well as botryococcenes when the alcohol was fed to the culture of Botryococcus braunii B race strain. In in vitro experiments with a 10,000 x g supernatant of cell homogenate, squalene was synthesized from farnesyl diphosphate in the presence of NADPH or NADH, but botryococcenes were not synthesized under the same conditions. A 100,000 x g pelet fraction was able to phosphorylate farnesol to give its mono- and diphosphate esters in a CTP dependent manner.

Formation of farnesal and 3-hydroxy-2,3-dihydrofarnesal from farnesol by protoplasts of Botryococcus braunii

Farnesal and 3-hydroxy-2,3-dihydrofarnesal (3-hydroxy-3,7,11-trimethyl-6,10-dodecadiene-1-al) were formed from farnesol when the alcohol was incubated with the protoplast of Botryococcus braunii B race strain. This fact suggests the existence of farnesal hydratase in the alga. Feeding experiments showed that both farnesal and 3-hydroxy-2,3-dihydrofarnesal were efficiently incorporated into botryococcenes, triterpenoid hydrocarbons of the alga.

Geranylgeranyl diphosphate synthase catalyzing the single condensation between isopentenyl diphosphate and farnesyl diphosphate

Geranylgeranyl diphosphate synthase was purified 191-fold from bovine brain by Mono Q column chromatography followed by preparative isoelectric focusing electrophoresis and Superose 12 gel filtration. The synthase had a pI value at 6.0, and it was made free of farnesyl diphosphate synthase, the pI of which was 5.1. The partially purified enzyme catalyzed the formation of geranylgeranyl diphosphate from isopentenyl diphosphate and farnesyl diphosphate with the Km values for isopentenyl diphosphate and farnesyl diphosphate being 14 and 0.8 microM, respectively. Dimethylallyl diphosphate and geranyl diphosphate were poor substrates with velocities of only 0.003 and 0.03, respectively, relative to that of farnesyl diphosphate. These results indicate that geranylgeranyl diphosphate synthase catalyzes a single condensation between isopentenyl diphosphate and farnesyl diphosphate and that farnesyl diphosphate is the common intermediate at the branch point for the synthesis of geranylgeranylated proteins as well as cholesterol, ubiquinone, dolichol, and farnesylated proteins. The enzyme required Mg2+ or Mn2+ for maximum activity. Octylglucoside showed a stimulatory effect on the enzyme activity.

Biosynthesis of prenyl diphosphates by cell-free extracts from mammalian tissues

When assayed by the conventional method for prenyltransferase using a combination of [1-14C]isopentenyl and geranyl diphosphates, 100,000 x g supernatants of homogenates of rat liver and brain catalyzed the formation of geranylgeranyl diphosphate at a much lower rate than that of farnesyl diphosphate. Surprisingly, however, the formation of geranylgeranyl diphosphate in incubations of [1-14C]isopentenyl diphosphate alone with these enzyme systems was comparable to that of farnesyl diphosphate. Addition of dimethylallyl diphosphate to the same enzyme systems in the presence of [1-14C]isopentenyl diphosphate resulted in a marked increase in the rate of formation of farnesyl diphosphate, while the rate of formation of geranylgeranyl diphosphate was saturated. Metabolic labeling of rat liver and kidney slices with [5-3H]mevalonic acid revealed that the major prenyl residue of the detectable prenylated proteins was actually the geranylgeranyl group. Coupled with the previous finding that geranylgeranyl diphosphate accumulates during metabolic labeling of rat liver slices with [2-3H]mevalonic acid [Sagami, H., Matsuoka, S., and Ogura, K. (1991) J. Biol. Chem. 266, 3458-3463], these results indicate that the rate of de novo synthesis of geranylgeranyl diphosphate from mevalonic acid is comparable to that of farnesyl diphosphate.

Flow-injection analysis for malondialdehyde in plasma with the thiobarbituric acid reaction

A simple, precise, and rapid method to measure plasma malondialdehyde (MDA) was developed by use of solvent extraction--flow-injection analysis. The reagent solution, containing thiobarbituric acid (TBA), 5 g/L in 100 mL/L phosphoric acid, and extraction solvent (methylisobutyl ketone, MIBK) were propelled with a double-plunger micropump at a flow rate of 0.3 mL/min, and 20 microL of sample was introduced into the reagent stream. After TBA-MDA reactant was extracted into MIBK, the organic phase was continuously separated by a successive phase-separation system equipped with two phase separators, and the absorbance of the TBA-MDA reactant was measured at 532 nm. This approach resulted in excellent sensitivity, a CV of < 1.5%, a good correlation with the conventional manual method, and a sampling frequency of 7 samples/h, suggesting that this semiautomated method is suitable for measuring plasma MDA.

Flow-Injection Analysis for Malondialdehyde in Plasma with the Thiobarbituric Acid Reaction

A simple, precise, and rapid method to measure plasma malondialdehyde (MDA) was developed by use of solvent extraction--flow-injection analysis. The reagent solution, containing thiobarbituric acid (TBA), 5 g/L in 100 mL/L phosphoric acid, and extraction solvent (methylisobutyl ketone, MIBK) were propelled with a double-plunger micropump at a flow rate of 0.3 mL/min, and 20 microL of sample was introduced into the reagent stream. After TBA-MDA reactant was extracted into MIBK, the organic phase was continuously separated by a successive phase-separation system equipped with two phase separators, and the absorbance of the TBA-MDA reactant was measured at 532 nm. This approach resulted in excellent sensitivity, a CV of &lt; 1.5%, a good correlation with the conventional manual method, and a sampling frequency of 7 samples/h, suggesting that this semiautomated method is suitable for measuring plasma MDA.

Studies on geranylgeranyl diphosphate synthase from rat liver: specific inhibition by 3-azageranylgeranyl diphosphate

Geranylgeranyl diphosphate synthase from rat liver was separated from farnesyl diphosphate synthase, the most abundant and widely occurring prenyltransferase, by DEAE-Toyopearl column chromatography. The enzyme catalyzed the formation of E,E,E-geranylgeranyl diphosphate (V) from isopentenyl diphosphate (II) and dimethylallyl diphosphate (I), geranyl diphosphate (III), or farnesyl diphosphate (IV) with relative velocities of 0.09:0.15:1. 3-Azageranylgeranyl diphosphate (VII), designed as a transition-state analog for the geranylgeranyl diphosphate synthase reaction, was synthesized and found to act as a specific inhibitor for this synthase, but not for farnesyl diphosphate synthase. Diphosphate V and its Z,E,E-isomer (VI) also inhibited geranylgeranyl diphosphate synthase, but the effect was not as striking as that of the aza analog VII. Specific inhibition of geranylgeranyl diphosphate synthase by VII was also observed in experiments with 100,000g supernatants of rat brain and liver homogenates which contained isopentenyl diphosphate isomerase and prenyltransferases including farnesyl diphosphate synthase as well as geranylgeranyl diphosphate synthase. For farnesyl:protein transferase from rat brain, however, the aza compound did not show a stronger inhibitory effect than E,E,E-geranylgeranyl diphosphate.

[Percutaneous transluminal angioplasty of dialysis access shunts]

Sixteen balloon angioplasties were performed in 10 patients with upper-extremity dialysis access shunts. The initial success rate was 80% (12/15). Of the initial successes, 58% (7/12) were patent at six months and 13% (1/8) at one year. In nine cases, repeat PTA was necessary. The mean interval of patency was about four months. The longest interval was two and a half years. The complication of thrombosis of the loop shunt during PTA was successfully treated by fibrinolytic therapy.

[Fracture of percutaneously inserted IVC filters--two cases of Günther's filter]

During the period from 1988 to 1990, percutaneous insertion of Günther vena caval filters were performed in ten patients in our institution. In two of them, fracture and partial migration of anchoring limbs were observed. Günthter's filter is an attractive device for interventional radiologist because of its technical ease of percutaneous placement and relative stability within the vein. However, our experience suggests that this device is not entirely safe and reliable. The patients should be carefully followed up with a possibility of distal migration in mind. Further structural improvement seems necessary.

MR imaging of the breast with Gd-DTPA enhancement: comparison with mammography and ultrasonography

The accuracy of MR imaging with Gd-DTPA enhancement was compared with mammography and ultrasonography in 52 patients with clinically palpable benign and malignant breast masses (36 carcinomas, 2 malignant phyllodes tumors, 7 fibroadenomas, 7 cysts). On dynamic MR imaging, carcinomas and fibroadenomas were discriminated by their different dynamic enhancement profiles. In carcinomas, signal intensity increased rapidly, reaching a peak or plateau within 2 min after the injection of contrast medium. In fibroadenomas, signal intensity showed a much slower continuous increase without ceasing until about 8 min after injection. Malignant phyllodes tumors showed a dynamic enhancement profile identical to that of benign fibroadenomas. MR imaging correctly identified 84% of malignant tumors, 86% of fibroadenomas, and 100% of cysts, and was substantially more accurate in tissue characterization than mammography. The results of ultrasonography were highly similar to those of MR imaging. However, no single modality was infallible, and the three modalities were complementary rather than competitive. Considering the high cost and long examination time of MR imaging, mammography supplemented by ultrasonography seems to be the method of choice in the diagnosis of breast lesions. Nevertheless, MR imaging can add important information when the results of mammography and ultrasonography are insufficient or contradictory.

Whole body intravenous digital subtraction angiography

A new type of intravenous digital subtraction angiography using an extra large field size is reported. Excellent image quality of large field size enables better evaluation of widespread vascular disease and eliminates the need for repeated injections of contrast material in almost all patients.