Effects of storage and handling on vitamins in fresh lima beans

Fresh Lima beans were subjected to various combinations of handling factors, including storage time and temperature, air during storage, water during preparation, hulling, and preparation method, to determine their effects on ascorbic acid, thiamin, and carotene content. Freezing resulted in highly significant losses of ascorbic acid and thiamin. Longer storage time and higher storage temperature resulted in significant reduction in ascorbic acid. Bruising, such as that occurring when beans are mechanically hulled, caused significant losses of both carotene and ascorbic acid. Significant interactions indicated that subjecting beans to circulating air and to bruising increased degradation of ascorbic acid and carotene. Increasing storage temperature compounded the effects of air circulation and of storage time on ascorbic acid. For example, 24-hr. storage at 45 degrees F was as severe as 72 hr. at 37 degrees F. Highest overall content of ascorbic acid was attained with hand-hulled samples stored in still air before cooking. Lowest content of ascorbic acid occurred in bruised beans cooked in copper-fortified water.     

Effects of various handling and storage conditions on stability of Treponema pallidum DNA in cerebrospinal fluid

Treponema pallidum DNA from even small numbers of organisms was detectable in cerebrospinal fluid (CSF) stored at room temperature or at 4 degrees C for several hours and in CSF subjected to three freeze-thaw cycles. These results suggest that negative PCR results for T. pallidum from patients diagnosed with T. pallidum invasion of the central nervous system are probably not due to the loss of target DNA prior to testing.     

Magnesium homeostasis and renal magnesium handling

Magnesium is essentially an intracellular cation, which makes it difficult to evaluate magnesium status. About 1% of total body magnesium is present in serum and interstitial body fluid and only about 1% of the intracellular magnesium is in the free form, Mg2+. Recent studies show that this small fraction of free Mg2+ rapidly changes with the extracellular magnesium. These free Mg2+ levels are carefully controlled within the cell and total cellular magnesium content are maintained at the expense of extracellular fluid and bone magnesium levels. Regulation of magnesium balance is met between intestinal absorption and renal excretion. The excretory side of magnesium balance involves appropriate changes in renal magnesium handling. Present evidence indicates that renal handling of magnesium normally is a filtration-reabsorption process; magnesium is filtered at the glomerulus and reabsorbed along the various segments making up the renal nephron. About 80% of total serum magnesium (0.7-1 mmol/l) is filtered at the glomerular membrane. Of the ultrafilterable magnesium (0.6-0.8 mmol/l) 20-25% is reabsorbed by the proximal tubule, including the convoluted and straight portions. Some 50-60% of the filtered magnesium is reabsorbed in the loop of Henle, specifically by thick ascending limb cells. The terminal nephron segments, including the distal convoluted tubule and collecting ducts, reabsorb only a small portion of the filtered magnesium (about 5-10%). The loop of Henle plays the major role in determining magnesium reabsorption and urinary magnesium excretion. The loop of Henle also is the segment in which the major regulatory factors act to maintain magnesium balance.(ABSTRACT TRUNCATED AT 250 WORDS)     

Egg substitutes: chemical and biologic evaluations

Cercariae of Diplostomum spathaceum dropped onto the eyes of small unanaesthetized rabbits penetrated through the cornea, crossed the anterior chamber, and entered the lens. After 2-3 weeks they died and became semi-permanent amorphous cataracts. Cercariae remaining in the cornea became the centres of stromal nebulae 0.1-0.2 mm across which remained visible for at least 3 months. Re-exposure produced marked conjunctival inflammation. Parasites applied to the eyes of large adult rabbits or cold-stored enucleated eyes of man entered the cornea but failed to penetrate as far as the anterior chamber. It is suggested that cercariae are unlikely to reach the lens of bathers because of the thickness of the human cornea. However, exposure to infection may result in temporary conjunctival inflammation and more persistant stromal nebulae. Cercariae of the closely related D. adamsi, did not penetrate or develop in the eyes of mammals.     

Calcium-regulated renal calcium handling in healthy men: relationship to sodium handling

Several studies have shown an increase in urinary calcium excretion in response to a calcium load. However, because of the inverse changes in PTH levels with a calcium load, the effect of changes in serum calcium per se on its own excretion is unclear in humans. In this study we used a PTH clamp protocol to further characterize calcium-regulated renal calcium and magnesium handling and the relationship of the former to sodium excretion. Eight normal male subjects were evaluated using a calcium clearance protocol with graded calcium infusions under a PTH clamp while in balance during a high and then during a low sodium diet. The curves describing calcium and magnesium excretion as a function of serum ionized calcium on the high sodium diet were best fitted by sigmoidal functions, with midpoints (the levels of calcium resulting in half-maximal increases in urinary cation excretion) of 1.51 and 1.49 mmol/L, respectively. The curve describing urinary sodium as a function of serum calcium was also sigmoidal on the high sodium diet, with a midpoint of 1.55 mmol/L. Our data taken in conjunction with those of previous studies evaluating sodium and calcium excretion in diseases characterized by inactivating or activating mutations in the calcium receptor, are consistent with the hypothesis that PTH-independent, calcium-dependent changes in renal calcium, magnesium, and sodium handling may be mediated at least in part by this receptor, which is known to be located in the loop of Henle.     

Abnormal renal magnesium handling

The normal fractional urinary excretion of filtered magnesium is about 5%. In magnesium deficiency in man, the kidneys can normally reduce the 24-hour urinary magnesium excretion to less than 1 mmol (24 mg) via unknown mechanisms, and initially without a fall in plasma magnesium concentration. Renal magnesium wasting may be defined as a urinary excretion greater than 1 mmol/day in the presence of hypomagnesemia (plasma magnesium < 0.7 mmol/l). Congenital renal magnesium wasting occurs in several syndromes including Bartter's syndrome in which it is associated with hypercalciuria, and the defect may be in the thick ascending limb of Henle's loop, and Gitelman's syndrome in which there is hypocalciuria, and the defect may be in the distal convoluted tubule. Other causes of renal magnesium wasting include diabetes mellitus, hypercalcemia and diuretics. Magnesium wasting may also result from various toxicities including those of cis-platinum, in which the biochemical features resemble Gitelman's syndrome, and those of aminoglycosides, pentamidine and cyclosporin. Calcitriol deficiency may also contribute to renal magnesium wasting in some circumstances. Mild hypermagnesemia may occur in familial hypocalciuric hypercalcemia and may reflect abnormal sensitivity of the loop of Henle to calcium and magnesium ions. By contrast, the hypermagnesemia that occurs in chronic renal failure results from the reduced glomerular filtration of magnesium.     

Egg culture: the foundation

Bacterial lipopolysaccharide and a diverse array of other immunostimulants and cytokines suppress the metabolism of endogenous and exogenous substances by reducing the activity of hepatic cytochrome P-450 mixed function oxidase system. Although this effect of immunostimulants was first described almost 40 years ago, the mechanism is obscure. Immunostimulants are now known to cause nitric oxide overproduction by cells via induction of nitric oxide synthase. The highly reactive NO radical binds to prosthetic groups such as heme or iron-sulfur clusters leading to either activation or (more often) inhibition of iron-containing enzymes. It has been known for years that NO also binds to the heme moiety of cytochrome P-450 (CYP) with high affinity. However it was only recently demonstrated that binding of NO to CYPs also inhibits their enzymatic activity. This applies to both exogenously derived as well as endogenously synthesized NO. Suppression of CYP-dependent metabolism, which is a major problem of inflammatory liver diseases, can be significantly reversed by inhibition of NO synthesis in vivo under experimental conditions. The present paper reviews the findings implicating NO as a major factor mediating the suppression of CYP expression caused by endotoxins and immunostimulants in general. NO-mediated suppression of the metabolism of endogenous and exogenous substances under inflammatory conditions may contribute to the clinical manifestations and may be an important consideration for rational drug therapy in these conditions.     

Safe handling of cytotoxic drugs

Guidelines for the handling of cytotoxic drugs and related waste in health care establishments have recently been developed by the WorkCover Authority of NSW in collaboration with the New South Wales College of Nursing. Competencies for accreditation of staff involved in the reconstitution, storage, transport, administration and management of waste related to cytotoxic drug use have also been developed.     

Sample handling for proteome analysis

The main factor limiting the sensitivity range for the identification of proteins isolated by two-dimensional (2-D) electrophoresis is sample handling: protein detection limits on the gel, losses during extraction and digestion, as well as interference of gel contaminants and detergents with the mass spectrometry (MS) detection increasing background noise. At the one hundred picomole level, losses are fairly negligible but when the amounts drop below 1 picomole (and subfemtomole peptide detection limits have been reported recently by MS), the losses become a critical point. In order to extend proteome analysis to include very low copy number proteins, methods must be developed to minimize losses and handling steps, maximize digestion and extraction yields, as well as to lower chemical noise. We present several methods that we have developed in our laboratory to: (i) increase the amount of material available in a sodium dodecyl sulfate (SDS)-free form which does not require staining, (ii) increase protein extraction and digestion yields and lower the contamination by autoproteolytic products, and (iii) allow direct modification of the peptide mixture to generate sequence tags.     

Mercury-metallothionein and the renal accumulation and handling of mercury

In the present study, we evaluated the renal and hepatic accumulation of mercury, the intrarenal distribution of mercury and the urinary and fecal excretion of mercury in rats injected intravenously with a non-toxic 0.1 mumol/kg-dose of mercury in the form of mercuric chloride (HgCl2) or a complex of mercury-metallothionein (Hg-MT). Between 6 and 72 h after injection, the concentration of mercury in the kidneys of the rats injected with Hg-MT was significantly greater than that in the rats injected with HgCl2. The greatest difference in the renal concentration of mercury between the two groups of rats was detected 6 h after injection. In the kidneys of both experimental groups of rats, the cortex and the outer stripe of the outer medulla contained the highest concentrations of mercury, with the greatest concentrations found in the renal cortex and outer stripe of the outer medulla of the rats injected with Hg-MT. No differences were found between the two experimental groups with respect to the concentration of mercury in the renal inner stripe of the outer medulla and inner medulla throughout 72 h of study. The content of mercury in the blood and liver decreased over time in both groups of rats, but was always significantly greater in the blood and liver of rats injected with HgCl2. The rats injected with Hg-MT excreted more than eight times the amount of mercury in the urine than the corresponding rats injected with HgCl2 during 72 h. These data indicate that there may be decreased tubular reabsorption of filtered Hg-MT and/or tubular secretion of mercury in the rats injected with Hg-MT. In contrast, the rats injected with HgCl2 excreted significantly more mercury in the feces during the same period of time than the corresponding rats injected with Hg-MT. In conclusion, our data clearly indicate that the renal and hepatic uptake and accumulation of mercury, and the urinary and fecal excretion of mercury, are altered significantly when inorganic mercury is administered intravenously as a complex with metallothionein.     

Renal potassium handling in aging rats

The use of Gore-Tex (W. L. Gore & Associates, Flagstaff, AZ, U.S.A.) spheres as orbital implants is investigated. The left eyes of six New Zealand white rabbits were enucleated and spherical implants made of modified Gore-Tex were implanted. After 6 weeks of follow-up, the implants were harvested. No rabbit developed a postoperative infection and no cases of exposure or extrusion were noted. Histopathologic study revealed varying degrees of acute and chronic inflammation surrounding each implant. There was also evidence of inflammatory infiltration and fibrovascular ingrowth into each implant to a maximum distance of 500 microns. This preliminary study demonstrates that the Gore-Tex implant is well tolerated in vivo, allows cellular ingrowth, and may have a role as a permanent implant.     

高压断路器的故障及其处理

本文主要论述了某公司高压断路器主要故障的产生原因及其处理措施.     

Sources and dissemination of contamination in material handling operations

To assess the potential risks to personnel preparing feed for carcinogen bioassay research, a tracer was mixed with a meal diet to yield 10 kg batches of 100, 3,000 and 5,890 ppm. Wipe samples were obtained from horizontal and vertical surfaces, equipment and personnel before operations began, after they were completed, and following clean-up. Total and respirable suspended particulate matter samples were obtained. All operations led to contamination of clothing and equipment; cleaning did not remove all contamination. These results, obtained in a well controlled environment in which trained and well protected personnel were working, suggest that a higher level of process control may be required for adequate protection of personnel performing material handling operations with known or suspected carcinogens.     

醋蛋保健口服液的研制

[目的]改善醋蛋液口味.[方法]以醋蛋、蜂蜜为主要原料.加入中草药提取液,研制具有保健功能的醋蛋保健口服液,并对稳定剂和矫味剂的选择、口服液的配方等进行探讨.[结果]β-环糊精为最佳稳定剂,添加量为0.1%.阿斯巴甜为最佳矫味剂,添加量为0.3g/ml.通过正交试验和感官评定,确定了该保健口服液的最佳配方为:醋蛋酶解液25%、蜂蜜10%、中草药提取液1%、阿斯巴甜0.3g/ml.[结论]该产品改善了醋蛋风味,营养丰富且具有保健养生功效.     

现场总线抗干扰能力的提升和故障处理

梅钢2号精炼炉的电气控制采用了当今自动化系统中流行的现场总线控制技术,但在试生产期间却经常受到现场总线网络工作不稳定的困扰。通过对现场总线网络故障产生的原因进行分析并加以排查和解决,提出现场总线控制系统在设计中必须保证接地系统的可靠性,接地电阻必须小于1Ω;电缆施工过程中尽可能避免动力电缆对通讯电缆所产生的电磁干扰;合理使用现场总线通讯元件提升系统的抗干扰能力,从而保证整个控制系统的稳定运行。