Inhibitory effect of eggs on vitamin B12 absorption: description of a simple ovalbumin 57Co-vitamin B12 absorption test

Ovalbumin and egg yolks, mixed separately in vitro with radiocyanocobalamin (57 Co-vitamin B12), were served to normal volunteers in a cooked form. Ovalbumin, and to a lesser degree, egg yolks were observed to inhibit vitamin B12 absorption. This observation explains the rather poor assimilation of vitamin B12 from eggs labelled in vivo with 57 Co-vitamin B12.     

Vitamin B12 absorption following human intestinal bypass surgery

Adaptation of vitamin B12 absorption by small intestine has been suggested by experimental and clinical studies. Five partial ileal bypass patients and ten jejunoileal bypass patients were studied for adaptation of B12 absorption following surgery. Adaptation of vitamin B12 absorption could not be demonstrated in either group. Few of the patients on an individual basis demonstrated adaptation. Parenteral B12 should be given to all patients who undergo bypass surgery unless evidence of persistent normal B12 absorption has been obtained.     

The absorption of vitamin B12 after subtotal pancreatectomy in the rat

Subtotal pancreatectomy in the rat was performed by a new method. Except for a small remnant along the splenal hilus, the gland was completely removed. Exocrine pancreatic insufficiency was confirmed by fat and nitrogen malabsorption. A moderate diabetes mellitus was seen. Insulin substitution or diet restriction was unnecessary. The absorption of vitamin B12 after oral administration of 10 ng 57CoB12 was 5.0 +/- 0.2 (ng 57CoB12 +/- S.E.M.) in unoperated rats and 5.1 +/- 0.1 in pancreatectomized rats (p greater than 0.5). Pancreatic extract (PE) (100 mg) increased the absorption of 57CoB12 in unoperated rats (p less than 0.01), but not in pancreatectomized rats (p greater than 0.2). PE (300 mg) reduced the absorption in unoperated rats (p less than 0.01). The results indicate that an optimal amount of pancreatic secretion may stimulate the absorption of vitamin B12.     

Intestinal absorption of vitamin B12 in patients with chronic pancreatic insufficiency and the effect of human duodenal juice on the intestinal uptake of vitamin B12

The mean absorption of vitamin B12 (Schilling test) was 13.1 +/- 1.0 (% +/- S.E.M.) in 21 patients with chronic pancreatic insufficiency and 17.6 +/- 1.4 in 13 control patients (p less than 0.01). There was no correlation between pancreatic bicarbonate production after secretion stimulation and vitamin B12 absorption in the patient group (r = 0.117). Human duodenal juice reduced the uptake of 57CoB12-rat intrinsic factor (IF) by perfused rat small intestinal segments in vivo (p less than 0.01) as well as the uptake of 57CoB12-human IF by purified guinea-pig intestinal brush borders in vitro (p less than 0.01). The results confirm reduced absorption of vitamin B12 in chronic pancreatic insufficiency, but the mechanism remains uncertain.     

Vitamin B12-binding substances elaborated by the mucous membrane of the stomach]

Accurate electrocardiographic diagnosis of myocardial ischemia or infarction is difficult in patients with the Wolff-Parkinson-White syndrome; however, myocardial ischemia may also have profound effects on the electrophysiologic characteristics of the bypass tract in these patients. Comparison of studies performed during and two months following an episode of significant myocardial ischemia demonstrated substantial prolongation of the refractoriness of the bypass tract during the period of ischemia. Bypass refractoriness was prolonged by 196 msec, yet atrioventricular nodal refractoriness was not significantly different from normal. These studies, therefore, suggest that, on occasion, the presence of acute myocardial ischemia may, in fact, obscure the electrocardiographic diagnosis of the Wolff-Parkinson-White syndrome.     

The value of the D-xylose test compared with the differential sugar absorption test in recognizing coeliac disease

Absorbable stapling devices have been described by several groups for the creation of continent urinary diversions. Experience with these devices in the creation of the LeBag ileocecal orthotopic pouch is described. Use of the staplers simplifies pouch construction and yields functional results similar to hand-sewn reservoirs.     

Enhanced rectal absorption of amphotericin B lyophilized with glycyrrhizinate in rabbits

The influence of bases and additives in the formulation for rectal absorption of amphotericin B (AMB) lyophilized with dipotassium glycyrrhizinate (GLYK) was investigated using rabbits in relation to an in vitro release test. The release of AMB from the fatty base of Witepsol or a medium chain triglyceride (MCT) was markedly faster than that from the hydrophilic base of macrogol. The addition of polyoxyethylene (2) lauryl ether (POE(2)LE) into the fatty bases led to a marked increase in the release rate, whereas POE(9)LE or sodium lauryl sulfate resulted in a significantly lower release rate. Animals received rectally each of seven AMB formulations of Witepsol H-15, macrogol, MCT with surfactants and aqueous solution. The absorption of the AMB lyophilized mixture with GLYK at a 1:9 molar ratio from a MCT base was significantly superior to that from macrogol. The addition of POE(2)LE into the MCT base resulted in a marked increase in bioavailability, showing the highest bioavailability of 4.9%. High serum levels of over 100 ng/ml of serum were maintained for 24 h following administration. The lowest bioavailability was 0.32% for the macrogol suppository. There was a good correlation between the release rate of AMB from the formulations and bioavailability. These results suggest that an AMB rectal formulation may provide a promising therapeutic alternative to infusion, taking into account the serum level of AMB exceeding the minimal inhibitory concentration of the infecting organism.     

火焰原子吸收光谱法测定矿石中锑的不确定度评定

针对火焰原子吸收光谱法测定矿石样品中锑的分析测定过程和数学模型,找出了影响测量不确定度的主要来源,对各不确定度分量进行了评定,并计算得到了合成标准不确定度和扩展不确定度,给出了相应的测定结果表示法。