An evaluation of radioactive colloid for measuring the volume of effective liver

A methods for liver scintigraphy for finding the effective liver volume were developed. Matrix ROI (region of interest) was set on the anterior liver scintigram with 99mTc tin colloid and 198Au colloid, respectively. The various depths of liver under matrix ROI were calculated from the count rate noting the absorption coefficient. The effective liver volume was the sum total of the areas of matrix ROI to the various depths. In order to check the accuracy of this method, the effective liver volume was calculated using the liver phantom and the patient's liver scintigraphy. The volume obtained for the liver phantom was nearly equal to the real volume. The liver volume in 19 patients using 99mTc tin colloid and 198Au colloid showed good correlation with the volume as measured by computed tomography (CT) scan (r = 0.841, r = 0.749).     

A multi-wafer growth technique for GaAs vapor phase epitaxy using the AsCl3-Ga-N2 system with a horizontal reactor

A multi-wafer growth technique for vapor phase epitaxial GaAs has been developed using the open-tube AsCl₃-Ga-N₂ system with a conventional horizontal reactor. Use of this technique allows to process 4 wafers in a run with each wafer being 6 cm². The uniformities of growth rate, carrier concentration, and Hall mobility with wafer-to-wafer are typically ∽±3%, ∽±4%, and ∽±3%, respectively, and are shown to be sufficient for demanding microwave device applications.     

Studies on natural antioxidants in citrus species. I. Determination of antioxidative activities of citrus fruits.

The antioxidative activities of twenty types of citrus fruits were investigated with a screening method which is based on rat liver microsomal lipid peroxidation induced by dihydronicotinamide adenine dinucleotide phosphate (NADPH) and adenosine diphosphate (ADP). The activities of the exocarp were greater than those of the sarcocarp and the activities from immature fruits (collected in July-August) were greater than those from mature fruits. The strongest antioxidative activity was found in ponkan (Citrus reticulata Blanco) collected in July.     

Synthesis of poly(O-phospho-L-serine) and its structure in aqueous solution

A novel polypeptide, poly(O-phospho-L -Ser), was synthesized through the following three steps: i) preparation of O-diphenylphospho-L -serine N-carboxyanhydride [Ser(PPh₂) NCA]; ii) polymerization of Ser(PPh₂) NCA; iii) removal of phenyl groups from poly[Ser(PPh₂)]. The overall yield in the three- step synthesis was 71%, and the phospho-Ser content in poly(O-phospho-L -Ser) was 98 ± 1%. Circular dichroism spectra suggest that the polypeptide has two different disordered structures in aqueous solution.     

Chiral Biomineralization: Mirror‐Imaged Helical Growth of Calcite with Chiral Phosphoserine Copolypeptides

The O‐phospho‐L ‐serine [Ser(P)] containing peptides and proteins play an important role in controlling the morphology of biominerals. The poly[Ser(P)] and copoly[Ser(P)^xAsp^y] affect the calcium carbonate (CaCO₃) morphology and polymorph. The CaCO₃ helical structures were obtained in the presence of copoly[Ser(P)⁷⁵Asp²⁵]. When the L ‐copolymer was used as an additive, a clockwise P twisted spiral morphology was formed. On the other hand, when using D ‐copolymer, a counterclockwise M twisted spiral morphology was obtained.

Optical micrographs of chiral morphologies of CaCO₃ in the presence of a) L ‐copolymer and b) D ‐copolymer.     

Polyphosphate-dependent nicotinamide adenine dinucleotide (NAD) kinase: A novel missing link in human mitochondria

Polyphosphate [poly(P)] is described as a homopolymer of inorganic phosphates. Nicotinamide adenine dinucleotide kinase (NAD kinase) catalyzes the phosphorylation of NAD⁺ to NADP⁺ in the presence of ATP (ATP-NAD kinase). Novel NAD kinase that explicitly phosphorylates NAD⁺ to NADP⁺ using poly(P), besides ATP [ATP/poly(P)-NAD kinase], was found in bacteria, in particular, Gram-positive bacteria, and the gene encoding ATP/poly(P)-NAD kinase was also newly identified in Mycobacterium tuberculosis H37Rv. Both NAD kinases required multi-homopolymeric structures for activity expression. The enzymatic and genetic results, combined with their primary and tertiary structures, have led to the discovery of a long-awaited human mitochondrial NAD kinase. This discovery showed that the NAD kinase is a bacterial type of ATP/poly(P)-NAD kinase. These pioneering findings, i.e., ATP/poly(P)-NAD kinase, NAD kinase gene, and human mitochondrial NAD kinase, have significantly enhanced research on the biochemistry, molecular biology, and evolutionary biology of NAD kinase, mitochondria, and poly(P), including some biotechnological knowledge applicable to NADP⁺ production.     

Quantitative determination of phosphatidylcholine hydroperoxides during copper oxidation of LDL and HDL by liquid chromatography/mass spectrometry

1-Palmitoyl-2-linoleoylphosphatidylcholine monohydroperoxide (PC 16:0/18:2-OOH) and 1-stearoyl-2-linoleoylphosphatidylcholine monohydroperoxide (PC 18:0/18:2-OOH) were measured by liquid chromatography/mass spectrometry (LC/MS) using nonendogenous 1-palmitoyl-2-heptadecenoylphosphatidylcholine monohydroperoxide as an internal standard. The calibration curves for synthetic PC 16:0/18:2-OOH and PC 18:0/18:2-OOH, which were obtained by direct injection of the internal standard into the LC/MS system, were linear throughout the calibration range (0.8-12.8 pmol). Within-day and between-day coefficients of variation were less than 10%, and the recoveries were between 86% and 105%. The limit of detection (LOD) and the limit of quantification (LOQ) were determined using synthetic standards. The LOD (signal-to-noise ratio 3:1) was 0.01 pmol, and the LOQ (signal-to-noise ratio 6:1) was 0.08 pmol for both PC 16:0/18:2-OOH and PC 18:0/18:2-OOH. With use of this method, the concentrations of PC 16:0/18:2-OOH and PC 18:0/18:2-OOH in the lipoprotein fractions during copper-mediated oxidation were determined. We prepared oxLDL and oxHDL by incubating native LDL and native HDL from human plasma (n = 10) with CuSO(4) for up to 4 h. The time course of the PC 16:0/18:2-OOH and PC 18:0/18:2-OOH levels during oxidation consisted of three phases. For oxidized LDL, both compounds exhibited a slow lag phase and a subsequent rapidly increasing propagation phase, followed by a gradually decreasing degradation phase. In contrast, for oxidized HDL, both compounds initially exhibited a prompt propagation phase with a subsequent plateau phase, followed by a rapid degradation phase. The analytical LC/MS method for phosphatidylcholine hydroperoxides might be useful for the analysis of biological samples.     

Enzymatic degradation of p-chlorophenol in a two-phase flow microchannel system

Enzymatic degradation of p-chlorophenol was carried out in a two-phase flow in a microchannel (100 microm width, 25 microm depth) fabricated on a glass plate (70 mm x 38 mm). This is the first report on the enzymatic reaction in a two-phase flow on a microfluidic device. The surface of the microchannel was partially modified with octadecylsilane groups to be hydrophobic, thus allowing clear phase separation at the end-junction of the microchannel. The enzyme (laccase), which is surface active, was solubilized in a succinic aqueous buffer and the substrate (p-chlorophenol) was in isooctane. The degradation of p-chlorophenol occurred mainly at the aqueous-organic interface in the microchannel. We investigated the effects of flow velocity and microchannel shape on the enzymatic degradation of p-chlorophenol. Assuming that diffusion of the substrate (p-chlorophenol) is the rate-limiting step in the enzymatic degradation of p-chlorophenol in the microchannel, we proposed a simple theoretical model for the degradation in the microchannel. The calculated degradation values agreed well with the experimental data.     

Synthesis of peptide–cellulose conjugate mediated by a soluble cellulose derivative having β-Ala esters (II): conjugates with O-phospho-l-serine-containing peptides

A synthetic route is described here for novel peptide-cellulose conjugates containing O-phospho-l-serine. First, Boc-Ser(PO₃Ph₂) and the related dipeptides, Boc-Ser(PO₃Ph₂)-Asp(OBzl) and Boc-Asp(OBzl)-Ser(PO₃Ph₂), were synthesized by adopting the phosphoryl-protection strategy. The condensation reaction between the α-carboxyl group of the protected Boc-Ser(PO₃Ph₂) and the β-amino groups of β-Ala-Cellulose using isobutyl chloroformate and N-methylmorpholine yielded the product conjugate, N ^β -[Boc-Ser(PO₃Ph₂)]-β-Ala-Cellulose. The degree of substitution of Boc-Ser(PO₃Ph₂) towards the β-amino groups of β-Ala-Cellulose was estimated as DS ^N  = 0.75 (maximum, 1.0). Similar reactions between β-Ala-Cellulose and two kinds of protected dipeptides, Boc-Asp(OBzl)-Ser(PO₃Ph₂) and Boc-Ser(PO₃Ph₂)-Asp(OBzl), gave the corresponding conjugates, and the DS ^N was estimated to be 0.95 and 0.69, respectively. The phenyl, benzyl, and Boc groups were removed in one-pot using the Pt₂O catalyst in 50 % trifluoroacetic acid/acetic acid. The ³¹P-NMR and UV–Visible spectra indicated the complete deprotection without any observable elimination of the phosphorylated peptides.