[Microbore liquid chromatography with dual electrode electrochemical detection of monoamine transmitters in brain microdialysates]

In the present work, the method of microbore liquid chromatography(MLC) with dual electrode electrochemical detection (DEED) was used to determine the monoamine transmitters and their metabolites in the striatal microdialysates from the anaesthetized rats. The potentials applied on the upstream (anodic) electrode and downstream (cathodic) electrode were set at +0.72V and +0.05V versus an Ag/AgCl reference electrode respectively. The interference of the large early-eluting peaks from brain dialysate was well eliminated on cathodic detection on the basis of electrochemical reversibility of catechol compounds. The collection efficiency of catecholamine (NA, A and DA) and DOPAC, that is the ratio of their responses in downstream electrode to those in upstream, was found to be in the range of 0.690 to 0.768, thereby providing reliable identification and measurement of early elutes. MLC-DEED is one of the best methods for the determination of monoamine transmitters at trace level. To optimize separation and detection, these adaptations were made to the system with respect to the injection valve, flow rate of the pump, connections between injector, column and detector, and cell volume of the detector. The detection limit could reach 1pg or less per injection, and the amounts, at least in the range of 2-200pg, were linearly correlated with the peak areas both at anodic detection and at cathodic detection. Prior to the collection of samples the probe recovery was measured in vitro at room temperature, and the recovery (%) for NA, DA, DOPAC, 5-HIAA, 5-HT and HVA were 19.5, 18.9, 22.1, 14,6, 16.5 and 19.3 respectively. The reported concentration of each compound was corrected according to probe recovery. The basal concentration of DA and 5-HT in striatal microdialysates was 12.5 +/- 1.8 and 5.0 +/- 0.7nmol/L. The perfussion of high K+ (100 mmol/L) through the dialysis probe induced a large increase of the concentration of NA, DA and 5-HT in microdialysates, and further increase of the concentration was observed in rat postmortem. The critical points for MLC-DEED are briefly discussed.

Simultaneous determination of phenytoin and carbamazepine in human hair by high-performance liquid chromatography

Drug detection in human hair has been regarded as a potentially useful technique for therapeutic drug monitoring and for the assessment of therapeutic compliance. An isocratic high-performance liquid chromatography (HPLC) assay for the simultaneous measurement of phenytoin and carbamazepine in human hair was used to assess therapeutic compliance in a population of patients with epilepsy. After alkaline digestion, phenytoin and carbamazepine were separated on a reverse-phase column by using a mobile phase of acetonitrile/methanol/water (9:37:54) and monitored at a wavelength of 214 nm with methylphenyl-5-phenylhydantoin as internal standard. The assay was linear in the range from 0 to 66.66 ng/mg hair, and recoveries of both drugs at concentrations of 8.33, 33.3, and 66.66 ng/mg hair from the hair matrix ranged from 91.2 to 104.0%. Inter- and intraassay coefficients of variation for both drugs (assessed at three concentrations in the calibration range) were < 10%. The limits of detection for phenytoin and carbamazepine were 2.0 and 1.33 ng/mg hair, respectively.

The development of a MUAC-for-height reference, including a comparison to other nutritional status screening indicators

Mid-upper-arm circumference (MUAC) based on a single cut-off value for all the children less than 5 years of age has been used for many years as an alternative nutritional status index for children during famines or refugee crises, and as an additional screening tool in nonemergencies. However, it has recently been questioned whether MUAC is age- and sex-independent. After reviewing the scientific evidence underlying the use and interpretation of MUAC, a WHO Expert Committee recommended a new MUAC-for-age reference for under-5-year-olds. In some settings, however, it is difficult to assess a child's age and in such circumstances MUAC-for-height may be a good alternative. The height-based QUAC stick is a simple means of adjusting MUAC cut-offs according to height, and the MUAC-for-height reference and the construction and use of the QUAC stick are described in this article. Described also is the use of the receiver operating characteristic (ROC) curve method to evaluate the performance of MUAC, MUAC-for-age, and MUAC-for-height in screening malnourished children.

The development of MUAC-for-age reference data recommended by a WHO Expert Committee

Low mid-upper-arm circumference (MUAC), determined on the basis of a fixed cut-off value, has commonly been used as a proxy for low weight-for-height (wasting). The use of a fixed cut-off value was based on the observation that MUAC showed small age- and sex-specific differences. However, in 1993, a WHO Expert Committee concluded that age independence is not reflected in the true pattern of mid-upper arm growth, recommended the use of MUAC-for-age, and presented age- and sex-specific MUAC reference data developed with observations obtained from a representative sample of children in the USA aged 6-59 months. In this article, we explain the methodology for the development of these data, present age- and sex-specific growth curves and tables and discuss the applications and limitations of MUAC as a nutritional indicator. To develop the reference data, estimates were first obtained for the mean and standard deviation of MUAC for each month of age using 7-month segmental regression equations; a 5th-degree and a 3rd-degree polynomial in age was then used to describe the mean and standard deviation, respectively, of MUAC-for age. These curves show important age-specific differences, and significant sex-specific differences for boys and girls < 24 months of age. Correct interpretation of MUAC with regard to nutritional status requires the use of MUAC-for-age reference data such as those presented here.

PSK protects macrophages from lipoperoxide accumulation and foam cell formation caused by oxidatively modified low-density lipoprotein

In previous works, it has been evidenced that lipoperoxidative injury to macrophages caused by oxidatively modified low-density lipoprotein (O-LDL) plays an important role in foam cell formation, and that PSK, a protein bound polysaccharide extracted from the class Basidiomycetes Coriolus Versicolor, can protect macrophages from lipoperoxidative injury induced by tert-butyl hydroperoxide (tbOOH). In this paper PSK protection of macrophages from lipoperoxide (LPO) accumulation and foam cell formation caused by O-LDL and its action mechanism were further studied. The LPO accumulation was determined by using ACAS 570. Dynamic assay of the LPO level in eight single cells after adding O-LDL or determination of the average LPO content in a lot of cells incubated in advance with O-LDL for 12 h, both indicated that O-LDL might induce LPO accumulation in macrophages and the effects of O-LDL could be prevented by PSK. O-LDL might cause the changes of morphological structure in macrophages and the transformation of macrophages into foam cells, and the effects could also be prevented by PSK. The determination of selenium-dependent glutathione peroxidase (SeGSHPx) activities and mRNA contents of macrophages and changes of SeGSHPx activity and mRNA content after incubation with tbOOH showed that PSK might increase the SeGSHPx activity of macrophage and the enhanced SeGSHPx activity may occur at the level of gene transcription.

Investigation of fluorocarbon blowing agents in insulating polymer foams by 19F NMR imaging

Currently, there is no reliable and readily accessible technique with which the distribution and diffusion of blowing agents in rigid insulating foams can be detected and monitored. In this paper, we demonstrate that 19F NMR microscopic imaging together with 19F solid-state MAS NMR spectroscopy is ideally suited for such measurements and yield quantitatively reliable information that will be critical to the development and fabrication of optimized insulating materials with alternative blowing agents. Polystyrene (PS) and polyurethane (PU) foam samples were investigated with the objective of determining quantitatively the amount of blowing agents in the gaseous phase and dissolved in the polymer phase, and to determine and monitor the distribution of the blowing agents in aged foams as a function of time and temperature. The concentrations of the gaseous blowing agents in the cells and dissolved in the solid were simultaneously and quantitatively measured by 19F MAS NMR spectroscopy. An unfaced 1-yr-old PS foam filled with CH3CF2Cl has about 13% of total HCFCs dissolved in the solid; while there is about 24% of HCFCs in the solid of a faced 3-mos-old PU foam filled with CH3CCl2F. The data from 19F NMR imaging demonstrate that the distributions of the blowing agents in an aged foam are quite uniform around the center part (2 cm away from any edge) of a foam board; however, a gradient in blowing agent concentration was found as a function of distance from the initial factory cut edge. The effective diffusion coefficients of the blowing agents can be directly calculated from the imaging data. Quantitative diffusion constants and activation barriers were determined. Additionally, a foam treated with a second blowing agent was monitored with chemical shift selective imaging and the diffusion of the second gas into the foam and the out-diffusion of the original gas were determined.

Reversal of inhibition of reactive oxygen species on respiratory burst of macrophages by polysaccharide from Coriolus versicolor

Using a luminol-dependent, chemiluminescence assay we found tert-butylhydroperoxide to be a strong inhibitor of the respiratory burst of mouse peritoneal macrophages. However, the inhibition of respiratory burst induced by tert-butylhydroperoxide could be prevented after the interperitoneal injection of polysaccharide from Coriolus versicolor (PSK). Further investigation showed that glutathione peroxidase activity was markedly elevated in PSK-treated macrophages. After incubation with tert-butylhydroperoxide, higher activity of glutathione peroxidase was maintained in PSK-treated macrophages. These results suggest that the immunological function of macrophages is related to the activity of glutathione peroxidase. The non-specific immunopolysaccharide might protect macrophages from the damage induced by reactive oxygen species by enhancing antioxidative capacity.

Association of a change in chromatin structure with a tissue-specific switch in transcription start sites in the alpha 2(I) collagen gene

Chick embryonic sternal chondrocytes do not synthesize alpha 2(I) collagen until they are shifted by treatment with 5-bromo-2'-deoxyuridine (BrdUrd) to a fibroblastic phenotype, yet they transcribe this gene as rapidly as BrdUrd-treated cells. To examine further this transcription, the DNase I hypersensitive sites were mapped in the 5' region of this gene in chondrocytes, BrdUrd-treated chondrocytes, fibroblasts and three types of non-transcribing cells. A DNase I hypersensitive site at -200 bp, previously shown to be associated with the active transcription of this gene in fibroblasts, is not present in chondrocyte chromatin. The chondrocyte alpha 2(I) gene contains, however, a novel major hypersensitive site in the DNA region corresponding to the fibroblast intron 2, near the chondrocyte-specific transcription initiation site of this gene. This novel hypersensitive site is associated with the use of this alternate start site by chondrocytes, since it is lost when BrdUrd treatment causes these chondrocytes to switch to the initiation of transcription at the fibroblast start site. The BrdUrd-treated chondrocytes contain the same alpha 2(I) hypersensitive sites as fibroblasts, except that fibroblasts have an additional, previously unreported, site at -1000 bp.

Replication of an RK2 miniplasmid derivative in vitro by a DNA/membrane complex extracted from Escherichia coli: involvement of the dnaA but not dnaK host proteins and association of these and plasmid-encoded proteins with the inner membrane

A DNA/membrane complex extracted from a miniplasmid derivative of the broad host range plasmid RK2 cultured in Escherichia coli capable of synthesizing new plasmid supercoiled DNA in vitro was treated with antibodies that were made against or reacted with the dnaA and dnaK host-encoded proteins, respectively. Anti-dnaA protein antibody inhibited total plasmid DNA synthesis significantly and the synthesis of supercoil plasmid DNA almost completely. In contrast, anti-dnaK protein antibody and nonimmune serum had little or no effect on total plasmid DNA synthesis. Both proteins were found to be present in the inner but not outer membrane fraction of E. coli. A variety of miniplasmid-encoded proteins which had previously been found in the DNA/membrane complex have also been localized to the inner but not outer membrane fraction. These include an essential initiation protein of 32 kDa (and an overlapping protein of 43 kDa coded for by the same gene), as well as a 30-kDa protein that may be linked to incompatibility functions. Various extraction methods were used to distinguish between the associated and the integral nature of the plasmid-encoded proteins. The results demonstrated that the essential replication proteins (32 and 43 kDa) as well as the 30-kDa protein was tightly bound to the inner membrane. Computer analysis of the amino acid sequence of the 32 (and 43)-kDa protein revealed a hydrophobic region that is only half that normally required to span the membrane. Other interactions are discussed with respect to attaching this protein to the membrane.

Selection of hormone-responsive advanced breast cancer with a cytoplasmic estrogen receptor assay. Analysis of 100 cases

One hundred women with advanced breast cancer were treated with endocrine therapy alone and the clinical response was correlated with the estrogen receptor status of the tumor as determined by a fluorescent histochemical assay designed to estimate the percentage of cancer cells with high cytoplasmic estrogen binding activity. Using clinical response rates as the standards for measurement, this histochemical method showed an 84% sensitivity, a 74% specificity, a 76% positive predictive value and an 82% negative predictive value. These results indicate that the histochemical assay may serve as a supplementary means to identify hormone-responsive mammary carcinomas and as a research tool to study the biology of this group of tumors.

Differential Effects of selenium on the proliferation of human pulmonary adenocarcinoma cells and human embryonic lung diploid cells in vitro

The effect of different concentrations of Na2SeO3 on human pulmonary adenocarcinoma cells and human embryonic lung diploid cells in vitro was investigated. For human pulmonary adenocarcinoma cells, mitotic index and cell count decreased with increasing selenium concentrations. At 1 μg/mL sodium selenite, mitotic activity and growth of human lung cancer cells were partially inhibited, and the progression of human lung cancer cell cycle was partially arrested. When human embryonic lung diploid cells were treated with 1 μg/mL sodium selenite for five continuous days, cell counts of the treated group were closely parallel to those of the control group. After treating human embryonic lung diploid cells with 1-5μg/mL sodium selenite for 1-3 d, the mitotic index (MI), labeled index (LI), and average silver grain (SG) number per 20 labeled nuclei were the same as those of the control. In mixed cultures of human embryonic lung diploid cells and human pulmonary adenocarcinoma cells, treated with 3 and 5 μg/mL sodium selenite for 24 h, the lung diploid cells showed a normal fusiform morphology, whereas the lung cancer cells showed heavily vacuolated cytoplasms and distorted nuclei.

In vitro differential effects of sodium selenite on the growth of human hepatoma cells and human embryonic liver cells

The effects of various concentrations of Na2SeO3 on human hepatoma cells and human embryonic liver cells was investigated in vitro. For human hepatoma cells, mitotic index and cell count decreased with increasing selenium concentrations. At 1 μg/mL Na2SeO3, mitotic activity of human hepatoma cells were partially arrested. In human embryonic liver cells continuously treated with Na2SeO3, (1 μg/mL) cell count of the treated group decreased only by d 7; mitotic index, labeled index, and mean silver grain number per 50 labeled nuclei were the same as in the control group on exposure to 1, 3, and 5 μg/mL for up to 72 h. In mixed cultures of human hepatoma and embryonic liver cells treated with 3 and 5 μg/mL of Na2SeO3 for 24 h, hepatoma cells showed vacuolated cytoplasms, distorted nuclei, condensed chromatin, and even pyknosis, whereas the embryonic liver cells retained a normal morphology under the same treatment.

Some differentiating effects of selenium on the cultured human hepatoma cells and human pulmonary adenocarcinoma cells in vitro

Two human hepatoma cell lines, QGY-7703 and SMMC-7721, and two human pulmonary adenocarcinoma cell lines, LTEP-a-2 and SPC-A-1, were found to respond to 1 μg/mL Na2SeO3, 24 h, in-vitro treatment by decreasing its confluent saturation density. The same treatment was found to cause an increase in the adhesiveness of cells measured as resistance to detachment by trypsin/EDTA. The pathological features of tumors after heterotransplantation of treated and untreated cells were similar, but the size of tumor grown from treated cells was much smaller.