Artifact reduction of susceptibility-weighted imaging using a short-echo phase mask.

BACKGROUND: Susceptibility-weighted imaging (SWI) is utilized in magnetic resonance (MR) venography and other applications, but can include artifacts caused by the phase-masking process. PURPOSE: To demonstrate risks of filter processes used in making phase masks for SWI, and to propose a simple method for reducing artifacts. MATERIAL AND METHODS: Phase linearity related to echo time (TE) was evaluated for the original phase and high-pass-filtered phase using a CuSO(4)-doped water phantom. Effect of filter size of the Hanning window and background homogeneity were also evaluated in a phantom study. Use of a phase mask generated by data with differing magnitudes of TE was attempted in a human study. Shorter TE was used for making the phase mask, and the number of multiplications was increased. As short and long TEs were necessary simultaneously for phase mask and T2* contrast, a dual-echo technique was used. RESULTS: Linearity of TE and phase value collapsed, and an unexpected negative phase appeared in the high-pass-filtered phase. Using a short-TE phase mask, phase-aliasing artifacts were reduced and visibility of deep veins was equivalent to that under conventional methods with an increased number of multiplications. CONCLUSION: Use of a short-echo phase mask in SWI is useful for reducing artifacts.

Biodistribution of a positron-emitting suicide inactivator of monoamine oxidase, carbon-11 pargyline, in mice and a rabbit.

Carbon-11 (11C) pargyline, which is a suicide inactivator of Type B monoamine oxidase (MAO), was synthesized by the reaction of N-demethylpargyline with 11CH3I. Biodistribution was investigated in mice, and positron tomographic images of the heart and lung in a rabbit were obtained. The distribution of 11C after administration of [11C]pargyline was measured in several organs and blood at various time intervals. After 30 min its concentrations in the organs were constant. Subcellular distribution studies in the brain, lung, liver, and kidney showed that 59-70% of the 11C became acid-insoluble and 9-33% was present in the crude mitochondrial fraction at 60 min after injection. However, a high loading dose influenced the subcellular distribution but had little effect on tissue distribution. The uptakes of the 11C in each organ except for the kidney and spleen seemed to correlate with the in vitro enzymatic activity of Type B MAO. At high loading dose a nonspecific uptake was observed.

18F-fluoro-2'-deoxyuridine as a tracer of nucleic acid metabolism in brain tumors.

The value of 18F-fluoro-2'-deoxyuridine (18F-FUdR) as a tracer for nucleic acid metabolism was studied using an experimental rat brain-tumor model. The 18F activity in the tumor tissue 45 minutes after intravenous injection of 18F-FUdR was about 12 times higher than that in the contralateral cortex. Double-labeled autoradiography with 18F-FUdR and 14C-thymidine revealed similar brain-tumor images. In contrast, an autoradiographic comparison of 18F-FUdR with 14C-aminoisobutyric acid, which reveals the impairment of the blood-brain barrier, showed very different images. Also, the 18F radioactivity in the tumor tissue was at a constant level for 30 to 120 minutes, whereas a notable increase in 18F activity with time was observed in nucleotides and acid-insoluble fractions. These results suggest that the distribution pattern of 18F-FUdR closely correlates with the metabolism of nucleic acid and that this drug could be a useful tracer for positron emission tomography.

Alcohol fermentation of corn starch digested by Chalara paradoxa amylase without cooking.

Alcohol fermentation of corn starch without cooking was performed by using Chalara paradoxa glucoamylase preparation, which had stronger raw starch digesting activity than those of the conventionally known glucoamylases. A raw corn starch-enzyme-yeast mixture was fermented optimally at pH 5.0 and 30 degrees C for five days and produced ethanol. The yields of ethanol were between 63.5 and 86.8% of the theoretical value by baker's yeast (Saccharomyces cerevisiae), and between 81.1 and 92.1% of the theoretical value by sake yeast (Saccharomyces sake).

Biogenesis of Protein Bodies in Embryonic Axes of Soybean Seeds (Glycine max. cv. Enrei).

Protein bodies in embryonic axes of soybean seeds have inclusion structures containing phytin globoids. Biogenesis of the protein bodies during seed development was examined by transmission electron microscopy. Protein bodies in embryonic axes originated from central vacuoles. The central vacuole in embryonic axes subdivided into smaller vacuoles with internal membranous structure. Then the subdivided vacuoles were directly associated with rough endoplasmic reticulum (rER), and were filled with proteinaceous matrix from the peripheral region. The increase of matrix was simultaneous with accumulation of ß-conglycinin estimated by SDS-polyacrylamide gel electrophoresis. Glycinin-rich granules that had been found in developing cotyledons were not observed in embryonic axes. After proteinaceous matrix filled the protein bodies, electron-transparent regions presumably surrounded by a single membrane appeared in the matrix. Phytin globoids were constructed in this internal structures of protein bodies as the final step of protein body formation.

Convenient 77Kr production method for medical use.

A convenient method of 77Kr production has been developed for its routine medical use in cerebral blood flow measurement. An aqueous solution of NaBr (40 wt%) was used as the target and 77Kr produced by the 79Br(p, 3n)77Kr reaction was rapidly recovered from the target under a He stream. The optimal target thickness was determined to be 5 approximately 6 mm by investigating radionuclidic purity and proton current effect on the yield. About 740 MBq (20 mCi) of 77Kr with a radionuclidic purity of 92% was obtained within 5 min after a 5 microA-20 min irradiation. The present method has been demonstrated to be suitable for routine 77Kr production.

Emulsifying and oil-binding properties of bovine serum albumin and its enzymatic hydrolyzate.

Bovine serum albumin (BSA) was hydrolyzed with proteases, and the emulsifying and oil-binding properties of the hydrolyzates were then studied. By limiting hydrolysis with trypsin, the emulsifying activity index (EAI) increased about 40% above its original level. In order to find out which peptides contributed to the good emulsifying properties of the hydrolyzate, the peptides adsorbed onto the emulsified oil globule surface were extracted and analyzed. SDS-polyacrylamide gel electrophoresis showed that a peptide with a molecular weight of about 24kDa was preferentially adsorbed onto the oil surface. This 24kDa peptide was found to be fairly hydrophobic and corresponds to the third domain of BSA, residues 377-582. In spite of the preferential adsorption characteristics of the 24kDa peptide, this peptide itself had a lower EAI value than that of the whole hydrolyzate. The contribution of some small hydrophilic peptides, as well as the 24kDa peptide, to the good emulsifying properties of the BSA hydrolyzate was suggested.

[Automated synthesis system for production of 11C-glucose].

A fully automated synthesis system of 11C-glucose by the photosynthesis method has been developed for clinical use. This system has been designed to be as convenient as possible for routine use, and the full automation of the whole procedure from the target gas recovery to collection of the final 11C-glucose/fructose mixture has been accomplished by microcomputer control. A mixture of 11C-glucose/fructose (1:1) was obtained with 20 approximately 35% of radiochemical yield within 60 min.

Molecular phylogeny based on the kappa-casein and cytochrome b sequences in the mammalian suborder Ruminantia.

Nucleotide sequences for the kappa-casein precursor proteins have been determined from the genomic DNAs or hair roots of the Ruminantia. The coding regions, exons 2, 3, and 4, were amplified separately via the three kinds of PCRs and then directly sequenced. The primers were designed from the sequence of bovine kappa-casein gene; they were applicable for the amplification of the kappa-casein genes from the 13 species in the Ruminantia except exon 2 of the lesser mouse deer. These results permitted an easy phylogenetic analysis based on the sequences of an autosomal gene. A phylogenetic tree was constructed from the mature kappa-casein sequences and compared with the tree of the cytochrome b genes which were sequenced from the same individuals. The Cervidae (sika deer, Cervus nippon) were separated from the branch of the Bovidae on the tree of kappa-casein genes with a relatively high confidence level of the bootstrap analysis, but included in the branch of the Bovidae on the tree of cytochrome b genes. The kappa-casein tree indicated a monophyly of the subfamily Caprinae, although the internal branches were uncertain in the Caprinae. The tree based on the nucleotide sequences of cytochrome b genes clearly showed the relationships of the closely related species in the genus Capricornis consisting of serow (C. smatorensis), Japanese serow (C. crispus), and Formosan serow (C. swinhoei). These results would be explained by the difference of resolving power between the kappa-casein and the cytochrome b sequences.

Molecular cloning, DNA nucleotide sequencing, and expression in Bacillus subtilis cells of the Bacillus macerans cyclodextrin glucanotransferase gene.

The gene for cyclodextrin glucanotransferase from Bacillus macerans was cloned in an Escherichia coli bacteriophage, lambda D69, and was recloned in a Bacillus subtilis plasmid, pUB110. Starting from an ATG initiation codon, a unique reading frame was shown to extend for 2,142 base pairs (714 amino acids). The nucleotide sequence revealed that the enzyme is composed of two identical subunits.

Increased carbon monoxide in exhaled air of subjects with upper respiratory tract infections.

Viral infection may induce the expression of heme oxygenase, resulting in increased carbon monoxide (CO) formation. CO may be produced by various cells of the upper and lower respiratory tract and may be detected in the exhaled air. Therefore, exhaled CO concentrations were measured on a CO monitor by vital capacity maneuver in subjects with upper respiratory tract infections (URTIs) and in nonsmoking and smoking healthy control subjects. At the time of symptoms of URTI, exhaled CO concentrations were 5.6 +/- 0.4 ppm and decreased to 1.0 +/- 0.1 ppm during recovery. Recovery values of exhaled CO were similar to those in age-matched nonsmoking healthy control subjects (1.2 +/- 0.3 ppm). Smoking healthy control subjects had the highest levels of exhaled CO concentration among the groups (18.5 +/- 2.5 ppm). These findings suggest that symptomatic URTIs increase the concentration of CO in exhaled air. This may reflect the induction of heme oxygenase that has an antiviral effect in the airways.

Exhaled carbon monoxide levels during treatment of acute asthma.

Carbon monoxide is known to be present in measurable quantities in the exhaled air of normal subjects and at higher concentrations in asthmatic patients not treated with glucocorticoids. To examine whether exhaled CO is useful in monitoring asthma control, time course changes in peak expiratory flow rate (PEFR) and exhaled CO concentration before and after treatment of acute asthma exacerbations were measured in 20 asthmatic patients. Exhaled CO was measured in triplicate by a portable CO analyser. Exhaled CO was reproducible at all time points. Asthma exacerbations caused a fall in PEFR and a rise in exhaled CO (towards an average of 3.3 parts per million (ppm)) in all patients, and treatment with oral glucocorticoids reversed these changes in both parameters. An improvement of PEFR was closely associated with a reduction of exhaled CO (to an average of 1.5 ppm) after treatment. The maximal exhaled CO concentration significantly correlated with recovery time of PEFR after treatment with oral glucocorticoids (p<0.01). The present study suggests that exhaled CO may be a useful noninvasive means of monitoring the control of asthma.

11C-coenzyme Q10: a new myocardial imaging tracer for positron emission tomography.

Coenzyme Q10 (CoQ10) is a co-factor of the mitochondrial electron-transfer system. 11C-Labeled CoQ10 was synthesized and its biodistribution in rats was examined comparing two kinds of preparation methods using different emulsifiers as a basic study for application of positron emission tomography. 11C-CoQ10 emulsified in saline with polyoxyethylene hydrogenated castor oil was present in the highest concentration in the blood at 30 min. On the other hand, the 11C-CoQ10 emulsified with phospholipids was rapidly cleared from the blood. The liver and spleen uptakes were high probably due to endocytosis, reflecting the characteristics of liposomes. The myocardial uptake was also high just after administration, and the heart-to-blood concentration ratio was over 10 after 5 min. These results suggest that 11C-CoQ10 prepared with liposomes may be a myocardial imaging tracer.

Tuberculin responses and risk of pneumonia in immobile elderly patients.

BACKGROUND: Delayed type hypersensitivity (DTH) response to tuberculin is an important marker of T helper 1 (Th1) mediated acquired immunity against tuberculosis. Depressed DTH responses to tuberculin are observed in immobile elderly individuals with reduced activities of daily living (ADL) scores. Immobility in older people increases the risk of pneumonia related mortality. The decline in the competence of the immune system might be a reason for the increased susceptibility to infection in the elderly and the depressed DTH response to tuberculin might be a predictor for increased risk of pneumonia. METHOD: The DTH responses to tuberculin were examined in 49 older patients with limited ADL of similar severity, all of whom had a past history of positive DTH responses to tuberculin. Responses with an induration diameter of >/=10 mm were considered positive. Reactivities of Th1 and Th2 lymphocytes taken from the peripheral blood of each subject were also examined and compared between the positive tuberculin responders and the negative tuberculin responders. The rates of pneumonia in these groups were then compared prospectively for two years. RESULTS: The number of CD4 lymphocytes differed significantly between patients with a positive tuberculin response (n=22, mean (SE) 1018 (118) x 10(6)/l) and those with a negative response (n=27, 666 (80) x 10(6)/l, p=0.02). Likewise, the number of Th1 cells was significantly higher in positive tuberculin responders than in negative responders (276 (5.8) x 10(6)/l versus 149 (14) x 10(6)/l, p=0.01). However, the numbers of Th2 cells were similar between patients with positive and negative responses (22 (3) x 10(6)/l versus 19 (3) x 10(6)/l, p=0.41). During the follow up period new pneumonia was diagnosed in 18 (67%) of the 27 negative tuberculin responders and in seven (31%) of the 22 positive tuberculin responders. According to the Cox regression model, a hazard ratio of developing pneumonia in patients with a negative tuberculin response compared with those with a positive tuberculin response was 2.57 (95% CI 1.12 to 6.17, p=0.03). CONCLUSION: The diminished DTH response to tuberculin may be a predictor for increased risk of pneumonia in elderly disabled patients.

Immobilization of the exo-maltohexaohydrolase by the irradiation method.

Exomaltohexaohydrolase (E.C.3.2.1.98) was immobilized by radiocopolymerization of some synthetic monomers which were mixed in various combinations. Irradiation was carried out while the mixture of monomers and enzymes was frozen in petroleum ether-dry-ice bath. Recovery of the immobilized enzyme was 44-75%.The optimum pH of the enzyme slightly shifted to the acidic side. The pH stability was improved remarkably by immobilization. The enzyme was stable retaining more than 90% of its original activity in the range pH 4-11. The optimum reaction temperature of the enzyme increased about 2 degrees C. Heat stability was also improved by immobilization, and that the enzyme retained about 40% of its original activity after treatment at 75 degrees C for 15 min. The immobilized enzyme was stable to the repeated use of 20 cycles. The K(m) value of the enzyme for short-chain amylose was almost the same as that of native enzyme. When soluble starch was used as the substrate, the K(m), value of the enzyme was three times as large as that of native enzyme. Effects of various metal ions and inhibitors on the immobilized enzyme were also studied compared to the native enzyme.