Down症候群(DS)に伴う遺伝子異常は研究の途上であり, Alzheimer病を基本とした神経系細胞の研究に比べ, CRELD1やGATA4関連心奇形, 肺動脈の組織変化に関連する経路の研究はやや乏しい感がある. 基本的には, おおむね房室中隔欠損(AVSD)に伴う肺動脈性肺高血圧(pulmonary arterial hypertension:PAH)のリスクに関してはコンセンサスが得られているが, 臨床医として適切な検査時期, 多彩なPAH増悪因子, そして治療介入時期の判断を間違わなければ, 非DSと同程度の手術成績が得られることに関しては全く同感である. 特に呼吸器系の低形成は肺気腫に類似した組織像であり, 肺血管壁の構築もストレスに対して肥厚しやすく, 二次性または合併症PAHへの進展が懸念される. 発見後150年, 染色体異常確認後50年が過ぎたこの症候群についてはさらなる研究成果の臨床への応用が, DS患者に多くの光を与えるであろう.

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A 31-year-old woman with no significant past medical or family history was admitted with complaints of general weakness. Laboratory tests revealed: serum potassium 3.0 mEq/L, arterial blood pH 7.28, serum bicarbonate 17.8 mEq/L and urinary pH 7.0. Double-labeling confocal fluorescence microscopy using H⁺-ATPase and pendrin antibodies demonstrated a decreased expression of these proteins in the patient's renal collecting duct compared to normal controls. Anti-Sjögren's-syndrome-related antigen A (Anti-Ro/SS-A) and anti-Sjögren's syndrome type B (anti-La/SS-B) antibodies were strongly positive with very high titers, consistent with Sjögren's syndrome. We present a case of distal renal tubular acidosis-associated Sjögren's syndrome with a defect in H⁺-ATPase and pendrin in the renal collecting duct.

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The effect of glucosamine (GlcN) and N-acetylglucosamine (GlcNAc) on bone metabolism in ovariectomized (OVX) mice was studied. After 12 weeks of feeding with 0.2% GlcN and 0.2% GlcNAc, the femoral bone mineral density in OVX mice was significantly increased compared with that in OVX mice fed the control diet. Histomorphometric analysis of the tibia indicated that the rates of osteogenesis and bone resorption were reduced due to the GlcN diet. The erosion depth of osteoclasts on the tibia in GlcN- and GlcNAc-fed OVX mice was significantly lower than that in the control OVX mice. The number of tartrate-resistant acid phosphatase-positive osteoclasts induced from bone marrow stem cells isolated from GlcN-fed OVX mice was significantly lower than that from control OVX mice. A loss of uterine weight and higher serum calcium concentration in the GlcN- and GlcNAc-fed OVX mice were observed. The results suggest that the intake of GlcN suppresses bone loss by inhibiting osteoclast differentiation and activity in a nonestrogenic manner.

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Background:The clinical significance of osteoporosis in chronic heart failure (CHF) remains unclear.

Methods and Results:A total of 303 CHF patients (75 years, [interquartile range (IQR) 66–82 years]; 41% female) were retrospectively examined. Bone mineral densities (BMDs) at the lumbar spine, femoral neck, and total femur were measured by using dual-energy X-ray absorptiometry (DEXA), and osteoporosis was diagnosed when the BMD at any of the 3 sites was <70% of the Young Adult Mean percentage (%YAM). The prevalence of osteoporosis in CHF patients was 40%. Patients with osteoporosis were older (79 [IQR, 74–86] vs. 72 [IQR, 62–80] years), included a large percentage of females, had slower gait speed and had a lower body mass index. Multivariate logistic regression analysis indicated that sex, BMI, gait speed, loop diuretics use and no use of direct oral anticoagulants (DOACs) were independently associated with osteoporosis. Kaplan-Meier survival curves showed that the rate of death and heart failure hospitalization was higher in patients with osteoporotic BMD at 2 or 3 sites than in patients without osteoporosis (hazard ratio 3.45, P<0.01). In multivariate Cox regression analyses, osteoporotic BMD at 2 or 3 sites was an independent predictor of adverse events after adjustment for prognostic markers.

Conclusions:Loop diuretics use and no DOACs use are independently associated with osteoporosis in CHF patients. Osteoporosis is a novel predictor of worse outcome in patients with CHF.

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小児期PAHの薬物療法を行うにあたって，臨床医は小児は成人と異なり様々な特色があることを再認識しなければならない．すなわち，代謝酵素活性（p450など），受容体の濃度（密度）や感受性，器官の機能発達（特に腎臓と肝臓，心筋代謝），体脂肪の容積，蛋白（アルブミン）結合率，血中蛋白濃度，分散容積，薬物動態PKや薬力学PD，一定の年齢だけ反応する臓器（動脈管など），薬理遺伝子的背景，　遺伝子多型などによる個人差，特異体質，薬物相互作用，生体内活性物質（サイトカイン，ホルモン，伝達物質，カテコラミンなど）の影響である．特に小児期の重症疾患に対しては，“Right drug for the Right patient at Right time”という諺に準じて，その個人に見合った慎重なcase by caseの薬剤選択を心掛けなくてはいけない．小児期の肺高血圧治療薬には，NO-cGMP経路，PGI2-cAMP経路，エンドセリン受容体拮抗薬（ERA）の三大肺血管作動薬を使用する．小児では，世界的にもほとんどがoff-labelの状態で使用されている．しかし肺血管拡張作用以外の，細胞増殖抑制作用，線維化・肥大抑制作用，抗酸化ストレス・抗炎症作用を秘め，長期にわたって血管壁に抗リモデリン作用を発揮する薬剤を選択したい．また特発性（遺伝性，家族性）と二次性肺高血圧（左心不全，膠原病関連，呼吸器関連，肺血栓塞栓関連，そして新生児期肺高血圧など）では，3大治療薬が持つPDE5阻害作用，PGI2産生促進作用，エンドセリン受容体拮抗作用などの有効性もそれぞれ異なると予想される．本稿では，治療薬の小児期でのエビデンスを紹介しながら，最適の治療法を推奨したい．

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