牛奶和钙盐在胃肠道内的钙吸收

目的和方法目前尚不清楚，摄入非水溶性钙盐的钙吸收是否比摄入水溶性差的钙盐钙吸收更好；另外也不清楚，牛奶制品的钙吸收是否比钙盐钙吸收更好。作者采用一种单次服用就能精确测定钙的净吸收率的方法，给８例健康空腹受试者服用含５００mg钙的５种不同水溶性的钙盐和牛奶，服用顺序是随机的。结果按钙盐的水溶性递减次序排列，以平均钙的净吸收率±标准误表示：醋酸钙（３２±４）％，乳酸钙（３２±４）％，葡萄糖酸钙（２７±３）％，柠檬酸钙（３０±３）％；碳酸钙（３９±３）％。按方差分析，钙盐和牛奶的钙吸收率差异无统计学意义…     

Biosynthesis of selenocysteine, the 21st amino acid in the genetic code, and a novel pathway for cysteine biosynthesis

The biosynthetic pathway for selenocysteine (Sec), the 21st amino acid in the genetic code whose codeword is UGA, was recently determined in eukaryotes and archaea. Sec tRNA, designated tRNA([Ser]Sec), is initially aminoacylated with serine by seryl-tRNA synthetase and the resulting seryl moiety is converted to phosphoserine by O-phosphoseryl-tRNA kinase to form O-phosphoseryl-tRNA([Ser]Sec). Sec synthase (SecS) then uses O-phosphoseryl-tRNA([Ser]Sec) and the active donor of selenium, selenophosphate, to form Sec-tRNA([Ser]Sec). Selenophosphate is synthesized from selenide and ATP by selenophosphate synthetase 2 (SPS2). Sec was the last protein amino acid in eukaryotes whose biosynthesis had not been established and the only known amino acid in eukaryotes whose biosynthesis occurs on its tRNA. Interestingly, sulfide can replace selenide to form thiophosphate in the SPS2-catalyzed reaction that can then react with O-phosphoseryl-tRNA([Ser]Sec) in the presence of SecS to form cysteine-(Cys-)tRNA([Ser]Sec). This novel pathway of Cys biosynthesis results in Cys being decoded by UGA and replacing Sec in normally selenium-containing proteins (selenoproteins). The selenoprotein, thioredoxin reductase 1 (TR1), was isolated from cells in culture and from mouse liver for analysis of Cys/Sec replacement by MS. The level of Cys/Sec replacement in TR1 was proportional to the level of selenium in the diet of the mice. Elucidation of the biosynthesis of Sec and Sec/Cys replacement provides novel ways of regulating selenoprotein functions and ultimately better understanding of the biological roles of dietary selenium.     

Management of Localized Breast Angiosarcoma by North American Radiation and Medical Oncologists

Introduction

Primary breast angiosarcoma is a rare malignancy with no clinical trials to guide management. The current use of surgery, chemotherapy, and radiotherapy among North American oncologists is unknown.

Experimental intrahepatic portacaval anastomosis: use of expandable Gianturco stents

Original Gianturco expandable stents and their modifications were used to create an experimental intrahepatic portacaval anastomosis (EIPCA) in 30 young domestic swine without portal hypertension. The study focused on the design of a suitable stent, the technique of its application, and the evaluation of short-term patency of the EIPCA. A stent with a 2.5-cm-long body and wire skirts on both ends was most suitable for EIPCA creation. Well-positioned stents shunted most of the portal blood in the inferior vena cava circulation and remained patent for 4-6 weeks. Ingrowth of liver parenchyma and abundant proliferation of the intima and connective tissue inside the stent lumen in these rapidly growing animals gradually decreased EIPCA patency, and thrombus formation with diminished blood flow closed them completely.     

国产沉香化学成分的研究——Ⅲ.异白木香醇的结构测定和低沸点成分的分离与鉴定

自国产沉香(Aquilaria sinensis)[瑞香科(Thymeleaceae)植物]的挥发油中,经硅胶柱层析和离心薄层层析分离得到一新的倍半萜,命名为异白木香醇(isobaimuxinol),根据光谱(IR,¹HNMR,¹³CNMR,2 D-NMR和MS)分析确定其结构式为(Ⅰ)所示,并用X-光衍射晶体解析进一步确定了其立体化学。同时,也从该植物挥发油的低沸点部分分离得到四个已知化合物:苄基丙酮,对甲氧基苄基丙酮,茴香酸和β-沉香呋喃。这些化合物均为首次从该植物中得到。     

Gastric ulceration as a complication of hepatic artery infusion chemotherapy

Based upon the cases reported in this paper and upon a literature review encompassing 1,783 patients having received HAIC, it is our opinion that upper gastrointestinal tract ulceration is a potentially significant complication of hepatic artery infusion chemotherapy. In addition, we believe that the mechanism responsible for HAIC-induced ulceration often involves direct perfusion of the gastric arterial supply with chemotherapeutic agents. The occurrence of ulcerations in patients with surgically placed catheters is disconcerting, and does not allow for any apparent easy method of alleviating HAIC-induced ulceration. Clinicians should be alerted to the possibility of gastric and duodenal ulceration in patients treated with HAIC, and should afford particular attention to gastrointestinal symptoms during hepatic artery infusion chemotherapy.     

Endstage renal failure due to polycystic kidney disease managed by continuous ambulatory peritoneal dialysis

Over a five and one half year period, four of nine patients with endstage renal failure due to polycystic kidney disease managed by continuous ambulatory peritoneal dialysis (CAPD) developed peritonitis following intestinal perforation. Two patients had colonic perforation associated with diverticular disease, one necrosis of the terminal ileum, and one acute appendicitis. Two of the patients died subsequent to these complications. The survivors had early transfer to haemodialysis. In contrast, over the same period, only two of 125 patients with renal failure due to other causes and managed by CAPD had acute intestinal perforation. In both cases this was associated with acute appendicitis. Both patients survived. All episodes of peritonitis in CAPD patients with polycystic kidneys demand very close monitoring, cessation of CAPD, and early surgical intervention. CAPD is relatively contraindicated in such patients.     

Effect of gastric mucosal injury on ornithine decarboxylase in young and aged rats

The present investigation examines the changes in ornithine decarboxylase (ODC) activity, level of the enzyme, and the expression of its gene in gastric mucosa of young (4-month) and aged (24-month) Fischer-344 male rats 6 h after intragastric administration of either 2 M NaCl (1 ml/130 g b.w.) or an equivalent volume of water (controls). In addition, electronmicroscopy was performed to evaluate the ultrastructural changes in the gastric mucosa. Although administration of 2 M NaCl virtually eliminated the surface epithelium in both young and aged rats, the extent to injury in older animals extended beyond the surface epithelium. In aged rats, epithelial cells in the deeper parts of the gastric glands demonstrated severe swelling with vacuolization and disintegration of the cell organelles, with dying and dead cells. Basal gastric mucosal ODC activity (data from the controls) in aged rats was found to be 118% (p less than 0.001) above the young animals. This was also associated with similar increases in the concentration of ODC (as determined by Western-blot analysis) and a steady-state rise in ODC mRNA. Intragastric administration of 2 M NaCl (which caused gastric mucosal injury) resulted in a 625% increase in mucosal ODC activity in young rats, but in aged rats it produced a 112% increase when compared with the corresponding controls. In young rats, the increase in gastric mucosal ODC activity after injury was also associated with about a 2-fold rise in the enzyme protein concentration and a 4-fold increase in steady-state ODC mRNA levels. In contrast, gastric mucosal injury in aged rats, which resulted in a 112% increase in ODC activity, produced about a 30% reduction in the concentration of ODC and a 15-20% reduction in steady-state mRNA levels, when compared with the respective controls. The current data demonstrate that aging is associated with decreased responsiveness of gastric mucosal ODC to injury which may in part be responsible for diminished regenerative capacity of the gastric mucosa in aged animals. Furthermore, in aged rats the injury-induced stimulation of mucosal ODC activity is not associated with increased activation of its gene.     

EMPHYSEMATOUS PYELONEPHRITIS RESPONDING TO MEDICAL THERAPY

We describe two type 2 diabetic patients with unilateral emphysematous pyelonephritis who responded to medical treatment alone. Escherichia coli was isolated in both patients. The presence of gas was confirmed early by ultrasound and CT scan of abdomen. Following treatment, good functional recovery was demonstrable in the affected kidneys by isotope renogram. We stress the need for early diagnosis of this condition and aggressive treatment with broad spectrum antibiotics.