L-Ascorbate Biosynthesis Involves Carbon Skeleton Rearrangement in the Nematode Caenorhabditis elegans

Ascorbate (AsA) is required as a cofactor and is widely distributed in plants and animals. Recently, it has been suggested that the nematode Caenorhabditis elegans also synthesizes AsA. However, its biosynthetic pathway is still unknown. To further understand AsA biosynthesis in C. elegans, we analyzed the incorporation of the 13C atom into AsA using gas chromatography-mass spectrometry (GC-MS) in worms fed with D-Glc (1-13C)-labeled Escherichia coli. GC-MS analysis revealed that AsA biosynthesis in C. elegans, similarly to that in mammalian systems, involves carbon skeleton rearrangement. The addition of L-gulono-1,4-lactone, an AsA precursor in the mammalian pathway, significantly increased AsA level in C. elegans, whereas the addition of L-galactono-1,4-lactone, an AsA precursor in the plant and Euglena pathway, did not affect AsA level. The suppression of E03H4.3 (an ortholog of gluconolactonase) or the deficiency of F54D5.12 (an ortholog of L-gulono-1,4-lactone oxidase) significantly decreased AsA level in C. elegans. Although N2- and AsA-deficient F54D5.12 knockout mutant worm (tm6671) morphologies and the ratio of collagen to non-collagen protein did not show any significant differences, the mutant worms exhibited increased malondialdehyde levels and reduced lifespan compared with the N2 worms. In conclusion, our findings indicate that the AsA biosynthetic pathway is similar in C. elegans and mammals

頭部SPECTにおけるステップと連続回転データ収集法の検討 : デジタルファントムによる検討

核医学検査における頭部SPECT検査を想定したステップ回転収集法と連続回転収集法による断層像のサンプリング角度の影響について，デジタルファントムを作成してシミュレーション解析による検討を行った．SPECTの連続回転収集法は，ステップ回転収集法のように検出器移動時の非データ収集というタイムロスが発生しない特徴があるが，標本化定理よりも大きなサンプリング角度を設定すると接線方向への画像歪が増加することが確認された．しかし，標本化定理に基づいたサンプリング角度を採用した場合は，連続回転収集法とステップ回転収集法によるSPECT像の画質がほぼ同等であることから，原理的に感度特性に優れた連続回転収集法を選択する方が良好な結果が得られると考えられた

A Newly Developed Instrument of Dual Photon Absorptiometry for Bone Mineral Analysis of the Lumbar Vertebra: Study in Control and Aged Females

In order to determine the quantitatively bone mass, dual photon absorptiometry instrument using a scintillation camera was newly developed, and its basic performance was described. Furthermore, with this instrument, bone mineral at 3rd lumbar vertebra was measured in 57 women (31 controls: age 29.9±6.4 yrs., and 16 seniles: age 67.7±6.6 yrs.). The aged females, compared with the young control females, showed significantly low the all parameters of bone mineral such as bone mineral content (BMC), bone mineral density and total BMC at 3rd lumbar vertebra. Thus, it was shown that assessment of bone mineral with this instrument provided a useful information in the diagnosis of osteoporosis

運動パターンの違いがMR画像に及ぼす影響 : Radial Scanにおける検討

呼吸や血管の拍動などの周期的な動きがある被検体をMRI撮像する場合，画像再構成におけるk-スペースへのデータ充填法にRadial充填を使用すると動きによるボケ（モーションアーチファクト）を減少させることができる．本研究では，運動ファントムを使用してRadial充填の画像のアーチファクト低減効果を確認するとともに，Radial充填における動きの大きさや運動パターンの違いによるアーチファクトの出現特性について検証した．運動幅としては7㎜を超えると像のボケが大きくなり，アーチファクト低減効果は少ないと考えられた．また運動幅が大きい場合，運動距離が同じであっても運動周期に静止周期を含む場合では，ボケ発生の特性が異なることが確認できた．運動ファントムでモーションアーチファクトの検証実験を行う場合には，運動の大きさだけでなく対象の運動パターンを考慮して，実験を行わなければ，臨床上で現れる特性を再現できない可能性があるため注意が必要である

Scintigraphic Findings of Bone and Bone-Marrow and Determination of Bone Mineral Density Using Photon Absorptiometry in Osteopetrosis

On a 15-year-old girl with osteopetrosis, bone and bonemarrow scintigraphy were performed. Also, bone mineral density (BMD) with quantitative CT (QCT), single photon absorptiometry (SPA) and dual photon absorptiometry (DPA) were measured. On bone scintigraphy the diffusely increased skeletal uptake and relatively diminished renal uptake were noted. On the other hand, on bone marrow scintigraphy poor accumulation in central marrow and peripheral expansion were shown. BMD value by QCT and DPA (mainly trabecular bone) was markedly high, while BMD by SPA (mainly cortical bone) was within normal range. Thus, it was shown that bone and bone-marrow scintigraphy combined with BMD measurement by photon absorptiometry were useful and essential in evaluating the pathophysiology of osteosclerosis

Comparative Studies of Values of Bone Mineral Density Measured with Different Photon Absorptiometries : A Preliminary Report

In order to compare values of bone mineral density measured with various photon absorptiometries, fundamental studies, using four different types of phantoms were performed in four instruments. The QDR-1000 (dual energy X-ray absorptiometry, DEXA) and Dualomex HC-1 (dual photon absorptiometry) were employed for the determination of bone mineral of a lumbar phantom and a cylindrical phantom, and the DCS-600 (DEXA) and Bone Densitometer (single photon absorptiometry) were used for the determination of bone mineral of a rectangular phantom and a ring phantom. The results indicate that the methodology for identification of the bone edge, which is necessary to calculate bone area or bone width, and the bone mineral per unit volume, which is defined as the line bone mineral content per cross-secional area, differ with the instruments used. Furthermore, the bone mineral per unit volume depends on the bone shape of the measured objects. Therefore, it seems taht the cross calibration of bone mineral density between instruments using phantoms is limited and in vivo investigation will be required in the future

A Study of Cases with Rib Metastasis Difficult to Distinguish from Microfractures on Bone Scintigraphy

A retrospective study of about 10,000 cases at Kawasaki Medical School Hospital on whom bone scans were performed over a six year period revealed five cases in which metastasis was mistaken for a benign rib lesion. This mistake occurred because the accumulation pattern of the radionuclide in the rib region on the bone scan indicated a so-called "hot spot" observed with microfractures rather than the rod-like increased accumulation along costal bones that is coincident with the finding of bone metastasis. This experience suggests that solitary hot spots in the rib region on bone scans should be diagnosed carefully, as such an accumulation is most frequently associated with a benign etiology but rarely may be a malignant lesion

Serial Cerebral Perfusion Imaging in a Case with Herpes Simplex Encephalitis

To evaluate cerebral blood flow, single photon emission computed tomographies (SPECTs) were serially performed in a case with herpes simplex encephalitis (HSE). Increased accumulation of N-ispropyl-I-123-p-iodoamphetamine (I-123-IMP) and Tc - 99m - hexamethylpropyleneamine oxime (Tc - 99m - HM - PAO) were noticed in the acute phase, and continued for seven weeks after the onset of the disease. In the third week, regional cerebral blood flow (rCBF) was estimated with I-123-IMP SPECT, and rCBF showed a high value in the affected temporal and occipital lobes of 60 to 70 ml/100 g/min (normal value; 40-50 ml/100 g/min), reflecting high accumulation of the tracer. After the twelfth week, when chinical symptoms and laboratory data had improved, the increased accumulation of these tracers was converted to a decreased accumulation

The Usefulness of Bone Scintigraphy in the Detection of Hypertrophic Pulmonary Osteoarthropathy

In a patient with lung cancer, increased accumulation in both lower legs on bone scintigraphy with 99mTc-hydroxymethylene diphosphonate was confirmed radiographically to be hypertrophic pulmonary osteoarthropathy. A characteristic scintigraphic pattern of radionuclide accumulation could be distinguished from bone metastasis