The use of microdialysis to monitor rapid changes in glucose concentration.

As a result of the Diabetes Control and Complications Trial, there is increased emphasis on the importance of blood glucose concentration self-monitoring for people with diabetes. The current methods for this are not ideal, and there are many other possible techniques currently under investigation. One of these techniques is microdialysis, which can be used to analyse subcutaneous interstitial glucose concentrations. A system with high recovery has recently been used to monitor glucose concentrations with sampling over one- or two-hour periods. We have investigated whether this system can be used to monitor rapid changes in blood glucose concentration in healthy volunteers with collection intervals of only ten minutes. The results show that microdialysis can be used to monitor rapidly changing blood glucose concentration, but in some subjects, dialysate glucose lagged behind the whole blood and plasma glucose concentrations to a degree that would be clinically significant. It would therefore be necessary to assess the system, comparing dialysate with plasma glucose concentrations in each individual, prior to use in a clinical setting.     

The use of wildlife to monitor zoonoses

Wildlife are usually considered vectors, reservoirs or primary targets of infectious disease. A seldom considered epidemiological role which they can play involves their use as disease sentinels for the detection and monitoring of zoonoses. Their potential for such utilization has been demonstrated with the wild turkey (Meleagris gallopava intermedia) and St. Louis encephalitis in Texas and the white-tailed deer (Odocoileus virginianus) and California encephalitis in North America. The limitations and criteria which are important in the use of wild populations for "sentinel" duty are discussed.     

The transfer of glucose to steroids by chimpanzee liver microsomes.

Microsomal preparations from chimpanzee liver can transfer glucose from UDPglucose to the 17alpha-hydroxyl group of 17alpha-estradiol and of 17alpha-estradiol-3-glucuronide. A phenolic glucoside of estrone, but not of either 17alpha- or 17beta-estradiol is also formed. No formation of glucosides of p-nitrophenol, or of diethylstilbestrol was demonstrated. The specificity of glucosyl transfer in the chimpanzee is not identical to that in either the human, the rabbit, or the sheep.     

The activation of glucose dehydrogenase by p-chloromercuribenzoate

Summary P-Chloromercuribenzoate alters various reactions of rat liver glucose (hexose phosphate) dehydrogenase differently. The reagent has little effect on the glucose: NAD or the glucose: NADP oxidoreductases, doubles the rates of oxidations of galactose-6-phosphate and glucose-6-phosphate by NADP and greatly stimulates the oxidations of glucose-6-phosphate and galactose-6-phosphate by NAD. The reagent appears to react with a sulfhydryl group of the enzyme since activation is reversed and prevented by mercaptoethanol. The direct reaction of the reagent with the enzyme is indicated by its lower thermal stability in the presence of the p-chloromercuribenzoate. The size of the enzyme appears to be the same when determined by sucrose gradient centrifugation in the presence or absence of p-chloromercuribenzoate. In microsomes, the oxidation of NADH or NADPH hampers measurements of glucose dehydrogenase. Since p-chloromercuribenzoate inhibits microsomal oxidation of reduced nicontinamide nucleotides, it is possible to assay for glucose dehydrogenase accurately in the presence of the mercurial in microsomes and microsomal extracts and thus measure the effectiveness of a detergent in extracting the enzyme from microsomes.Abbreviation pcMB p-chloromercuribenzoic acid     

The preparation of nylon-tube-supported hexokinase and glucose 6-phosphate dehydrogenase and the use of the co-immobilized enzymes in the automated determination of glucose.

Triethyloxonium tetrafluoroborate was used to O-alkylate nylon-tube thus producing the imidate salt of the nylon which was further made to react with 1,6-diaminohexane. 2. Hexokinase (EC 2.7.1.1) and glucose 6-phosphate dehydrogenase (EC 1.1.1.49) were immobilized on the amino-substituted nylon tube through glutaraldeyde and bisimidates. 3. The effect of varying the conditions of O-alkylation and the amount of enzyme immobilized on the activity of nylon tube-hexokinase derivatives was determined. 4. The effect of varying the amount of enzyme immobilized on the activity of nylon-tube-glucose 6-phosphate dehydrogenase derivatives was determined. 5. The thermal stability of nylon-tube-hexokinase and nylon-tube-glucose 6-phosphate dehydrogenase derivatives was studied. 6. Different ratios of hexokinase and glucose 6-phosphate dehydrogenase were co-immobilized on nylon tube, and the rate of conversion of glucose into 6-phosphogluconolactone was compared with the individual activities of the immobilized enzymes. 7. Hexokinase and glucose 6-phosphate dehydrogenase co-immobilized on nylon tube were used in the automated analysis of glucose.     

The use of DNA-intercalating dye to monitor cell fusion and microinjection

A conventional method for microinjection, using erythrocyte ghosts as the injection vector, has been modified to provide a protocol for the highly efficient delivery of small quantities of material into the cytoplasm of target cells. The technique is applicable for use with a variety of proteins, sugars, nucleotides and dyes. When the intercalating dye propidium iodide is included within the sealed ghosts their subsequent fusion with target cells can be continuously monitored by fluorescence spectroscopy, providing a convenient and sensitive parameter of cell-cell fusion. The protocol can be adapted for use with both adherent and non-adherent target cells, and can be used to monitor the relative effectiveness of a variety of fusogenic agents.     

水生双翅目昆虫监测水体重金属污染的研究

水生双翅目昆虫是监测水体重金属污染的理想对象。文章归纳用于监测重金属污染的水生双翅目昆虫的种类,重点介绍水生双翅目昆虫在重金属污染下外部形态、内部结构、生化及分子水平的变化,以及相关生物标志物的研究,为水生双翅目昆虫用于水体重金属污染的生物监测提供科学依据。     

The use of the three-ridge clam (Amblema perplicata) to monitor trace metal contamination

The three-ridge clamAmblema perplicata was used to monitor two streams for the presence of zinc (Zn) and cadmium (Cd) derived from an industrial source. Clams were collected from a relatively uncontaminated area in one river and transported to four study sites in the two contaminated streams. The clams were placed into polyethylene cages and left in these streams for one week. Control clams were treated in a similar manner and left in the uncontaminated river.The highest mean concentration of Zn (956 µg/g dry wt) was found in the gill tissue of clams from the most contaminated site. The highest mean Cd concentration (18.6 µg/ g dry wt) was found in digestive glands of clams, also from the most contaminated site. Mean concentrations at contaminated sites were significantly higher than background and control levels; the findings suggest that these particular organs of clams may be useful in monitoring levels of Zn and Cd in other freshwater systems.     

The use of milk progesterone to monitor reproductive function in beef suckler cows

Milk progesterone analysis was used to monitor reproductive function in 134 autumn calving cross-bred suckler cows. Progesterone was measured in milk samples collected three times per week from around 4 week post-calving to around day 60 of pregnancy during 1st and 2nd lactation. The mean day of onset of luteal activity (OLA) was 40.7 +/- 1.1 with the distribution skewed towards a later return. Once cyclicity had been initiated the incidence of reproductive cycle problems (6.5%) was low, though animals with such problems (n = 14) exhibited a delayed interval to first service (P < 0.05), lower conception and calving rates (P < 0.001), increased services per pregnancy (P < 0.001) and a higher (P < 0.10) barren rate (14.3% versus 4.0%) compared to animals with normal cycles (n = 201). In conclusion, using milk progesterone analysis we found a relatively low incidence of reproductive cycle problems in beefxdairy suckler cows. However, while the incidence of cycle problems was low, those animals with problems showed significantly impaired reproductive function.     

The use of DNA barcoding to monitor the marine mammal biodiversity along the French Atlantic coast

In the last ten years, 14 species of cetaceans and five species of pinnipeds stranded along the Atlantic coast of Brittany in the North West of France. All species included, an average of 150 animals strand each year in this area. Based on reports from the stranding network operating along this coast, the most common stranding events comprise six cetacean species (Delphinus delphis, Tursiops truncatus, Stenella coeruleoalba, Globicephala melas, Grampus griseus, Phocoena phocoena)and one pinniped species (Halichoerus grypus). Rare stranding events include deep-diving or exotic species, such as arctic seals. In this study, our aim was to determine the potential contribution of DNA barcoding to the monitoring of marine mammal biodiversity as performed by the stranding network.We sequenced more than 500 bp of the 5’ end of the mitochondrial COI gene of 89 animals of 15 different species (12 cetaceans, and three pinnipeds). Except for members of the Delphininae, all species were unambiguously discriminated on the basis of their COI sequences. We then applied DNA barcoding to identify some “undetermined” samples. With again the exception of the Delphininae, this was successful using the BOLD identification engine. For samples of the Delphininae, we sequenced a portion of the mitochondrial control region (MCR), and using a non-metric multidimentional scaling plot and posterior probability calculations we were able to determine putatively each species. We then showed, in the case of the harbour porpoise, that COI polymorphisms, although being lower than MCR ones, could also be used to assess intraspecific variability. All these results show that the use of DNA barcoding in conjunction with a stranding network could clearly increase the accuracy of the monitoring of marine mammal biodiversity.     

The functional significance of glucose dehydrogenase in Klebsiella aerogenes

In order to assess the functional significance of the quinoprotein glucose dehydrogenase recently found to be present in K⁺-limited Klebsiella aerogenes, a broad study was made of the influence of specific environmental conditions on the cellular content of this enzyme. Whereas high activities were manifest in cells from glucose containing chemostat cultures that were either potassium- or phosphate-limited, only low activities were apparent in cells from similar cultures that were either glucose-, sulphate- or ammonia-limited. With these latter two cultures, a marked increase in glucose dehydrogenase activity was observed when 2,4-dinitrophenol (1 mM end concentration) was added to the growth medium. These results suggested that the synthesis of glucose dehydrogenase is not regulated by the level of glucose in the growth medium, but possibly by conditions that imposed an energetic stress upon the cells. This conclusion was further supported by a subsequent finding that K⁺-limited cells that were growing on glycerol also synthesized substantial amounts of glucose dehydrogenase.The enzyme was found to be membrane associated, and preliminary evidence has been obtained that it is located on the periplasmic side of the cytoplasmic membrane and functionally linked to the respiratory chain. This structural and functional orientation is consistent with glucose dehydrogenase serving as a low impedance energy generating system.Abbreviations D dilution rate - DNP 2,4-dinitrophenol - PQQ 2,7,9-tricarboxy-1H-pyrrolo(2,3-f)quinoline-4,5-dione - PTS phosphoenolpyruvate: glucose phosphotransferase - WB Wurster's Blue     

The levels of nicotinamide nucleotides in liver microsomes and their possible significance to the function of hexose phosphate dehydrogenase.

The concentrations of NAD and NADP have been determined in detergent extracts of washed rat liver microsomes. Precautions were taken during the preparation of the microsomes to remove nicotinamide nucleotides from their external surface both by hydrolysis by nucleotide pyrophosphatase (EC 3.6.1.9) and by washing them three times in 0.15 M-Tris/HCl, pH 8.0, to remove soluble proteins which bind these nucleotides. The mannose phosphatase was essentially completely latent, indicating that the microsomes were intact. Assuming these nucleotides are in the cisternae of the microsomes, the concentrations in the cisternae are 240 +/- 25 microM-NAD and 55 +/- 12 microM-NADP. These levels of nucleotides are compatible with both the glucose:NAD+ and the glucose 6-phosphate:NADP+ oxidoreductase activities of hexose phosphate dehydrogenase (EC 1.1.1.47). Since the organ and subcellular distributions of this dehydrogenase and glucose-6-phosphatase are similar, and Pi stimulates the glucose:NAD+ oxidoreductase activity, it is proposed that the combined action of these two enzymes leads to the reduction of both coenzymes in the lumen of the endoplasmic reticulum. A modification of the colorimetric method of Nisselbaum & Green [(1969) Anal. Biochem. 27, 212-217] for the determination of NADP+ is described. Colour formation is linear with the concentration of NADP+ and is sensitive to less than 0.3 nmol of NADP+.