Direct determination of sodium and potassium in blood serum by flow injection and atomic absorption spectrophotometry

A simple and reliable method for the measurement of sodium and potassium in blood serum without any sample dilution by using flow injection and atomic absorption spectrophotometry is described. A sample throughout of 100 measurements per hour is possible. Matrix problems have not been encountered. The coefficient of variation for within-run determinations is about 1,14 and 2,36% for sodium and potassium, respectively, in serum samples (n = 10). The method is easily adaptable to pediatric research, because of the low required sample volume of 5 microliter.     

Calcium citrate markedly enhances aluminum absorption from aluminum hydroxide

The effect of calcium citrate on intestinal aluminum absorption, assessed by the increment in urinary aluminum excretion, was evaluated in eight normal men. Baseline urinary aluminum excretion was determined for 2 days; thereafter, subjects ingested aluminum hydroxide for 3 days. In a cross-over study, subjects were given either calcium citrate, 950 mg four times a day, or placebo during the 3 days of aluminum hydroxide ingestion (2.4 g/d). Plasma aluminum levels were measured on the second control day and the third day of aluminum hydroxide ingestion. Baseline urinary aluminum excretion was 0.02 +/- 0.004 (6.5 +/- 1.1 micrograms/g creatinine) and 0.03 +/- 0.005 mumol/mmol creatinine (7.4 +/- 1.3 micrograms/g creatinine). These values increased during aluminum hydroxide therapy, but values were much greater when calcium citrate was ingested with aluminum hydroxide. On 3 consecutive days, urinary aluminum excretion levels were 11.1 +/- 3.23, 8.8 +/- 2.9, and 5.3 +/- 0.7 times greater during the administration of calcium citrate with aluminum hydroxide than with aluminum hydroxide alone. Plasma aluminum levels did not differ in the two treatment groups. Thus, calcium citrate markedly enhances the absorption of aluminum from aluminum hydroxide and the two must not be prescribed together in patients with renal failure.     

The determination of bone density by radiation absorption

X-ray and -radiation techniques for evaluating bone density under field conditions in cattle and sheep were investigated. The best results were obtained from measurements of the density of radiographs of tibial tarsal bones of sheep and from the absorption of -radiation of the tibial tarsal bones of sheep and the fibular tarsal bones of cattle. The -radiation techniques may be carried out rapidly under field conditions (up to 30 animals an hour) and bone density can be estimated with a standard error of 0.042–0.046 SG units.     

Analysis of magnesium and trace elements in urinary calculi by atomic absorption spectrophotometry

Magnesium and trace element determinations in 29 urinary tract calculi were carried out using an atomic absorption spectrophotometric method. Of the calculi examined, 9 were pure calcium oxalate, 5 were mixed calcium oxalate/uric acid, 5 were mixed calcium oxalate/phosphate, 5 were magnesium ammonium phosphate and 5 were pure cystine. The measurement of magnesium and trace element levels has been considered useful in the elucidation of the mechanism of stone formation and the evaluation of factors leading to pathological consequences. In this study, the Mg, Zn, Cu, Fe, Cd and Pb content in all of the samples was determined and an attempt was made to compare the levels of these elements in calculi with the levels in normal hair.     

Enhanced gastrointestinal absorption of aluminum in uremic rats

To investigate the possibility of enhanced gastrointestinal absorption of aluminum in uremia, we measured the urinary aluminum excretion of rats following an oral load of 11 mg aluminum. Rats, in which uremia had been established by the remnant kidney model, excreted 1.5 to 2.2-fold higher amounts of aluminum in their urine over a collection period of five days compared with their controls. Within this period of time up to 0.17 +/- 0.08% of the oral dose of aluminum was recovered in the urine of the uremic animals. Serum concentrations of aluminum were significantly elevated five hours after ingestion of aluminum, but this increase was similar in rats with normal or reduced renal function. Uremic rats excreted significantly less aluminum during the first 24 hours after i.v. administration of 15 micrograms aluminum if the data were corrected for the higher baseline excretion rates. The excretion rate showed a negative correlation with the serum creatinine. Selective parathyroidectomy had no effect on the pattern or amount of urinary aluminum excretion after an oral load in either uremic rats or in rats with normal renal function. We conclude that the gastrointestinal absorption of aluminum is increased in uremic rats, and that parathyroid hormone has no detectable effect on the magnitude of aluminum absorption, regardless of the renal function in this model.     

Site and mechanism of enhanced gastrointestinal absorption of aluminum by citrate

Clinical and experimental studies have shown that citrate markedly enhances the intestinal absorption of aluminum (Al), but the site and mechanism of enhanced absorption are unknown. To determine where in the gastrointestinal tract aluminum citrate (Alcitr) was absorbed. Alcitr was gavaged with D-[1-3H] glucose in male Sprague-Dawley rats. Plasma Al levels increased rapidly and simultaneously peaked with D-[1-3G] glucose, suggesting early proximal bowel absorption. In in vitro duodenal and jejunal everted gut preparations, Alcitr incubation resulted in increased tissue Al levels and markedly enhanced transmural transport of Al and citr. Unlike citr, the transmural movement of Al was independent of temperature (37 degrees C vs. 4 degrees C). On the other hand, Al lactate (al Lac) increased tissue associated Al levels but had no effect on transmural Al movement. To determine if this large flux of Al following Alcitr administration was due to paracellular movement, ruthenium red and Ussing chamber studies were used to evaluate the morphologic and functional integrity of cellular tight junctions. Alcitr, as opposed to AlCl3, markedly increased ruthenium red deposits in intercellular spaces, especially around goblet cells, and induced a prolonged significant reduction in transmural resistance. Alcitr also resulted in rapid and nearly complete (99.7%) chelation of free calcium, an event known to disrupt cellular tight junction integrity. Taken together, these data suggest that enhanced Al absorption following administration of Alcitr occurs in the proximal bowel via the paracellular pathway due to the opening of cellular tight junctions.     

血清抗精子抗体的酶联免疫吸附定量测定

目的：研究抗精子抗体（AsAb)的酶联免疫吸附试验（ELISA）定量测定方法。方法：对ELISA－SPC310试剂盒的线性，回收率，重复性，批内变异值（CV）及最终颜色产物的呈色稳定性进行测定，并用试剂盒对42例不育夫女进行了血清抗精子抗体的定量测定。结果：抗精子抗体总抗体（TIg),IgG,IgA的浓度在250U／ml以下具有良好的线性；回收率在96．5％－98．7％之间；CV值在6．7％－9．3％之间；在自然条件下，最终颜色产物在20min内吸光度减退8．2％。不育夫妇血清中TIg浓度超过参考值上限的比例，男性为25．9％，女性为33．3％。结论：ELISA－SPC 310试剂盒是一种可靠的定量测定AsAb的方法。     

Role of iron metabolism in absorption and cellular uptake of aluminum

The effect of iron status on aluminum (Al) absorption was investigated in this study in vivo using an animal model and in vitro using an intestinal mucosal cell line. In the in vivo model rats were rendered iron overloaded by intraperitoneal injection of iron dextran (5 mg/48 hr) or iron deficient by phlebotomy (2.5 to 3 ml blood/week). These rats, and normal controls, were then dosed with Al(OH)3 (40 mg/day) for 30 days. Urinary excretion of Al was significantly greater in the iron deficient group than in the other two groups throughout the study period, and brain Al at the end of the experiment was significantly increased in the iron depleted group (1.93 micrograms/g) and decreased in the iron overloaded group (0.73 microgram/g) compared with controls (1.42 micrograms/g). The brain Al levels in iron overloaded rats were no higher than those in normal rats that had not been dosed with Al(OH)3 (0.61 microgram/g). No significant differences were found in serum Al levels. In the in vitro experiments cultures of the rat intestinal cell line RIE1 were iron overloaded by addition of iron nitrilotriacetate (0.1 mM) or iron depleted with desferrioxamine (5 micrograms/ml) for 20 days prior to pulsing with Al transferrin (0.5 mg/ml) for 24 hours. Uptake of Al was significantly greater in the iron depleted cells (2.3 ng/micrograms cell DNA) than in iron overloaded (0.81 ng) or untreated (0.83 microgram) cells. These studies show that iron depletion markedly increases absorption and cellular uptake and suggest that susceptible individuals, such as renal failure patients, run an increased risk of toxicity if they are iron deficient.     

Accurate and simplified determination of ketamine in plasma by gas chromatography mass spectrometry

An accurate and simplified method has been developed for determination of ketamine in human plasma using gas chromatography and electron impact mode mass spectrometry with selected ion recording from 0.5ml of plasma. Standards and samples of plasma underwent the same procedure of two step extraction by methanol. Ketamine concentrations in the plasma were determined from the peak in the selected ion profile of ketamine (m/e: 237). Standard curve was linear with the increasing amount of ketamine (0.63-5.0 micrograms.ml-1) in plasma with mean CV = 5.2% mean RR = 63.8% and r = 0.998. The concentration of ketamine in plasma ranged from 1.6 micrograms.ml-1 to 2.5 micrograms.ml-1 during ketamine anesthesia (2mg.kg-1.h-1) in a surgical patient.     

飞行质谱技术筛选肝癌肿瘤标志物的临床意义

目的探讨蛋白质质谱分析方法鉴定肝癌生物标志物的临床应用价值。方法用美国CipherGen公司金属亲和表面（IMAC3）芯片和蛋白芯片仪，检测24例肝癌患者，56例正常人血清中的蛋白质相对含量。结果肝癌患者与正常人血清蛋白质在质荷比为3500Da至12000Da间有6个蛋白质含量差异有统计学意义（P〈0．05）。经Biomarker Pattern软件分析，用4801Da蛋白质可将其中24例肝癌患者中全部被正确分组，56例正常人均被正确识别，准确率为100％（80／80），灵敏度和特异性分别为100％（24／24），100％（56／56）。结论本实验中查获的4801Da蛋白质可能为肝癌患者的特异蛋白，该方法可快速、准确检测肝癌，灵敏度、特异性高，临床应用前景广阔。     

Determination of the distribution of Zinc and Cadmium in cellular fractions of BPH,normal prostate and prostatic cancers of different histologies by atomic and laser absorption spectrometry in tissue slices

Summary The distribution of Zinc (Zn) and Cadmium (Cd) was analyzed in nuclear, mitochondrial and cytosol cellular fractions of prostatic carcinoma of different histological grading, BPH and normal prostate by electrothermal atomic absorption spectrometry (AAS). Distinct differences in Zn and Cd concentration in carcinomatous material in comparison with BPH and normal prostates was found. The highest concentration of Cd and the lowest level of Zn were found in poorly differentiated carcinomas. The results in cellular fractions were compared with investigations on Zn and Cd distribution in prostatic slices by laser AAS.     

A simple method for determination of flurbiprofen in human plasma by gas chromatography-mass spectrometry

A method for gas chromatograph-mass spectrometric assay has been developed for the quantitation of flurbiprofen in human plasma. Extraction or condensing procedure was not required and the method reduced time involved in sample preparation. The analytes were separated on the fused-silica capillary column. The operating conditions were: injector, 250 degrees C; detector, 300 degrees C; and column, 50-280 degrees C. The total gas flow-rate of helium (carrier) was 50 ml.min-1 and the pressure of column inlet was 100-200 kPa. The retention time was 18.1 min and the limit of quantitation was 0.5 microgram.ml-1. This method provides an easy and simple method for the detection of flurbiprofen.     

Influence of some dietary constituents on aluminum absorption and retention in rats

Eight groups of female Sprague-Dawley rats were treated with 281 mg Al(OH)3/kg/day by gastric intubation five times a week for five weeks. Concurrently, animals in seven groups received ascorbic acid (56.3 mg/kg/day), citric acid (62 mg/kg/day), gluconic acid (62.7 mg/kg/day), lactic acid (28.8 mg/kg/day), malic acid (42.9 mg/kg/day), oxalic acid (28.8 mg/kg/day), and tartaric acid (48 mg/kg/day) in the drinking water. The eighth group did not receive any dietary constituent in the water and was designated as the control group. Animals were placed in plastic metabolic cages and urine was collected during the treatment period. The liver, spleen, kidney, brain and bone aluminum levels of each rat were measured, as well as the total amount of aluminum excreted into urine. All the dietary constituents significantly increased the aluminum concentrations in most of the tissues, with ascorbic and citric acids showing the highest rate of aluminum accumulation. In contrast, no significant differences between control and treated rats were observed in the concentrations of aluminum excreted into urine. In view of these results, we suggest that the effects of the simultaneous ingestion of aluminum hydroxide and those dietary constituents in uremic animals should be evaluated. Meanwhile, the diet of uremic patients should be carefully monitored.