A density-functional study of Al-doped Ti clusters: TinAl (n=1–13)

Equilibrium geometries, stabilities, and electronic properties of TinAl (n = 1-13) clusters have been studied by using density-functional theory with local spin density approximation and generalized gradient approximation. The ground-state structures of TinAl clusters have been obtained. The resulting geometries show that the aluminum atom remains on the surface of clusters for n < 9, but is slowly getting trapped beyond n = 9, meanwhile, the Al atom exhibits a valent transition from monovalent to trivalent. The geometric effects and electronic effects clearly demonstrate the Ti4Al cluster to be endowed with special stability. The studies on the bonds indicate the change from ionic to metalliclike.

Improved method for measurement of human plasma xanthine oxidoreductase activity

The XOR activity in human plasma was measured by quantifying the XOR-derived uric acid (UA) in plasma using the high-performance liquid chromatography (HPLC) equipped with a UV detector. Chromatographic separation consisted of the mobile phase (a mixture of 0.1% trifluoroacetic acid in Milli-Q water and 0.085% trifluoroacetic acid in acetonitrile in a mix ratio of 99:1) running through a Zorbax StableBond SB-C(18) column at a flow-rate of 1 ml/min. Deproteinization with heat-treatment of plasma samples after the reaction was used in the assay to avoid splitting of the UA and xanthine peaks caused by acid deproteinization that could interfere the accurate determination of human plasma XOR activity in our case. Based on the examination of the dependence of XOR activity on added amounts of xanthine and reaction times, the amount of xanthine and reaction time for XOR activity assay were determined to prevent the errors caused by the limiting effect of substrates and plateau phase of the reaction. Using this method, human plasma XOR activities of 25 healthy people were measured. The average human plasma XOR activity was 2.1+/-0.8 (x10(-3) U/ml).

Quantitative assessment of cerebral ventricular volumes in chronic fatigue syndrome

Previous qualitative volumetric assessment of lateral ventricular enlargement in chronic fatigue syndrome (CFS) has provided evidence for subtle structural changes in the brains of some individuals with CFS. The aim of this pilot study was to determine whether a more sensitive quantitative assessment of the lateral ventricular system would support the previous qualitative findings. In this study, we compared the total lateral ventricular volume, as well as the right and left hemisphere subcomponents in 28 participants with CFS and 15 controls. Ventricular volumes in the CFS group were larger than in control groups, a difference that approached statistical significance. Group differences in ventricular asymmetry were not observed. The results of this study provide further evidence of subtle pathophysiological changes in the brains of participants with CFS.

[Establishment of human neuroectodermal tumor cell line (PFSK) with stable expression of xanthine oxidoreductase]

Xanthine Oxidoreductase (XOR) is the key enzyme in purine metabolism and also produces oxygen free radicals. As a continuation of our previous work, in this study, we constructed a retrovirus expression vector (pLNCX2-XOR) containing full length of XOR cDNA. Retrovirus was produced by the virus package cell line PT-67 following the transfection of PT-67 with pLNCX2-XOR and used to infect the human primitive neuroectodermal tumor cell line (PFSK). Infected PFSK cells were selected by G418 to establish cell line with stable expression of XOR. The expression of XOR in the cell line we established was confirmed by RT-PCR, Immunocytochemistry and XOR activity assay.

[Determination of catechol-O-methyltransferase activity in human erythrocytes by high performance liquid chromatography]

A rapid assay method for catechol-O-methyltransferase (COMT) activity in human erythrocyts by high performance liquid chromatography (HPLC) with UV detection was established. Enzyme activity was determined from erythrocyte lysates using S-adenosyl-L-methionine (SAM) as methyl donor and 3, 4-dihydroxybenzoic acid (DBA) as substrate. The 3-O-methylated reaction products were measured by HPLC with UV detection. The linear range of COMT was from 1 U/mL to 60 U/mL with an average RSD < 10%, and the detection limit was 0.5 U/mL(S/N > or = 5).

[HPLC determination of PAHs from electric power plant by UVD-FLD connected in series]

An HPLC method of UVD-FLD connected in series was used to detect naphthalene, biphenyl, fluorene, phenanthrene, anthracene, fluoranthene, 2-methyl-anthracene, chrysene, benzanthracene, benzfluoranthene [b], benzfluoranthene[k], benzopyrene PAH compounds in electricity plant environment. A CLC-ODS column (150 mm x 6.0 mm i.d.) with acetonitrile-water(85:15, V/V) as mobile phase and UV detector set at 250 nm and fluorescent detector set at lambda ex295 nm and lambda em427 nm were used. These 12 PAHs can be separated completely by this method. The earlier eluted eight PAHs were detected by UVD and the rest were detected by FLD. The minimum detectable concentrations of the 12 PAHs were 0.002 mg/L-0.1 mg/L. Satisfactory results were obtained in the analysis of PAH compounds in waste water, flue gas and flyash from several electric power plant in Hunan Province.

Ciliogenesis and left-right axis defects in forkhead factor HFH-4-null mice

Cilia have been classified as sensory or motile types on the basis of functional and structural characteristics; however, factors important for regulation of assembly of different cilia types are not well understood. Hepatocyte nuclear factor-3/forkhead homologue 4 (HFH-4) is a winged helix/forkhead transcription factor expressed in ciliated cells of the respiratory tract, oviduct, and ependyma in late development through adulthood. Targeted deletion of the Hfh4 gene resulted in defective ciliogenesis in airway epithelial cells and randomized left-right asymmetry so that half the mice had situs inversus. In HFH-4-null mice, classic motile type cilia with a 9 + 2 microtubule ultrastructure were absent in epithelial cells, including those in the airways. In other organs, sensory cilia with a 9 + 0 microtubule pattern, such as those on olfactory neuroepithelial cells, were present. Ultrastructural analysis of mutant cells with absent 9 + 2 cilia demonstrated that defective ciliogenesis was due to abnormal centriole migration and/or apical membrane docking, suggesting that HFH-4 functions to direct basal body positioning or anchoring. Evaluation of wild-type embryos at gestational days 7.0 to 7.5 revealed Hfh4 expression in embryonic node cells that have monocilium, consistent with a function for this factor at the node in early determination of left- right axis. Analysis of the node of HFH-4 mutant embryos revealed that, in contrast to absent airway cilia, node cilia were present. These observations indicate that there are independent regulatory pathways for node ciliogenesis compared with 9 + 2 type ciliogenesis in airways, and support a central role for HFH-4 in ciliogenesis and left-right axis formation.

Forkhead transcription factor HFH-4 expression is temporally related to ciliogenesis

Members of the forkhead/winged-helix family of transcription factors are expressed in tissue-specific patterns and play critical roles in development and cell differentiation. The expression of forkhead family member hepatocyte nuclear factor-3/forkhead homologue 4 (HFH-4) has been localized by RNA-blot analysis and in situ hybridization to the proximal airway of the lung (trachea, bronchi, and bronchioles) with onset at mouse embryonic day (E) 14.5 and is present in the choroid plexus, ependymal cells, oviduct, and testis. We hypothesized that the restricted expression of HFH-4 messenger RNA suggests a function common to these tissues and therefore a cell-specific role for HFH-4. Accordingly, an anti-HFH-4 antibody was generated and used for cell-specific localization of protein expression to begin to identify the functions of HFH-4. We found HFH-4 expression in proximal airway ciliated epithelial cells, but not Clara cells or alveolar epithelial cells. HFH-4 was also expressed in ciliated epithelial cells of the nose and paranasal sinuses, choroid plexus, ependyma, and oviduct. In developing mouse lung, HFH-4 expression was initially detected in airway epithelial cells at E15.5, before the appearance of cilia, and at later stages was localized to epithelial cells with cilia. In the testis, HFH-4 expression in spermatids was coincident with stage-specific generation of flagella. The temporal relationship of HFH-4 expression to the development of cilia and flagella, and the restricted expression in ciliated epithelial cells, suggest that this transcription factor has a role in regulation and maintenance of the ciliated cell phenotype in epithelial cells.

Sequencing and characterization of the citrus weevil, Diaprepes abbreviatus, trypsin cDNA. Effect of Aedes trypsin modulating oostatic factor on trypsin biosynthesis

Trypsin mRNA from the citrus weevil, Diaprepes abbreviatus, was reverse transcribed and amplified by PCR. A cDNA species of 513 bp was cloned and sequenced. The 3' and 5' ends of the gene (262 bp and 237 bp, respectively) were amplified by rapid amplification of cDNA ends, cloned and sequenced. The deduced sequence of the trypsin cDNA (860 bp) encodes for 250 amino acids including 11 amino acids of activation and signal peptides and exhibited 16.8% identity to trypsin genes of selected Lepidoptera and Diptera. A three-dimensional model of Diaprepes trypsin contained two domains of beta-barrel sheets as has been found in Drosophila and Neobellieria. The catalytic active site is composed of the canonical triad of His41, Asp92 and Ser185 and a specificity pocket occupied by Asp179 with maximal activity at pH 10.4. Southern blot analysis indicated that at least two copies of the gene are encoded by Diaprepes midgut. Northern blot analysis detected a single RNA band below 1.35 kb at different larval ages (28-100 days old). The message increased with age and was most abundant at 100 days. Trypsin activity, on the other hand, reached a peak at 50 days and fell rapidly afterwards indicating that the trypsin message is probably regulated translationally. Feeding of soybean trypsin inhibitor and Aedes aegypti trypsin modulating oostatic factor affected trypsin activity and trypsin biosynthesis, respectively. These results indicate that Diaprepes regulates trypsin biosynthesis with a trypsin modulating oostatic factor-like signal.

Selective induction of leukemia-associated fusion genes by high-dose ionizing radiation

There is strong clinical and epidemiological evidence that ionizing radiation can cause leukemia by inducing DNA damage. This crucial initiation event is believed to be the result of random DNA breakage and misrepair, whereas the subsequent steps, promotion and progression, must rely on mechanisms of selective pressure to provide the expanding leukemic population with its proliferative/renewal advantage. To investigate the susceptibility of human cells to external agents at the genetic recombination stage of leukemogenesis, we subjected two hematopoietic cell lines, KG1 and HL60, to high doses of gamma-irradiation. The irradiation induced the formation of fusion genes characteristic of leukemia in both cell lines, but at a much higher frequency in KG1 than in HL60. In KG1 cells, the AML1-ETO hybrid gene [associated with the t(8;21) translocation of acute myeloid leukemia] occurred significantly more often than the BCR-ABL [associated with t(9;22) chronic myeloid leukemia] or the DEK-CAN [associated with t(6;9) acute myeloid leukemia] fusion genes. These findings support the notion that ionizing radiation can directly generate leukemia-specific fusion genes but emphasize the differing susceptibility of different cell populations and the differing frequency with which the various fusion genes are formed. The selectivity observed at the primary level of gene fusion formation may explain at least in part the differential risk for development of some but not other forms of leukemia after high-dose radiation exposure.

[Determination of sinomenine HCl in serum and urine by HPLC and its pharmacokinetics in normal volunteers]

A RP-HPLC method was developed to determine the concentrations of sinomenine HCl in serum and urine and its pharmacokinetics was studied in healthy volunteers. C18H37 column was eluted with the mobile phase of acetonitrile--0.01 mol.L-1 sodium phosphate monobasic--N, N, N', N'-tetramethylenediamine (46:54:0.22 v/v, pH 6.9) and the ultraviolet absorbance was monitored at 263 nm. Triazolan was used as internal standard. The calibration curves were linear in the range of 6-480 ng.ml-1 in serum and 0.06-3 micrograms.ml-1 in urine, with mean recoveries of 75.46% and 91.38% respectively. The lowest detectable limits were 4 ng.ml-1 in serum and 40 ng.ml-1 in urine and the RSD for the intra-day and inter-day were less than 5%. A single oral dose of 80 mg sinomenine HCl tablet was given to 8 healthy male volunteers. The concentrations of sinomenine HCl in serum and urine were determined. The serum concentration--time curve was found to fit a two-compartment open model with first order elimination. The pharmacokinetic parameters were: T1/2 alpha 0.791 +/- 0.491 h, T1/2 beta 9.397 +/- 2.425 h, Tmax 1.040 +/- 0.274 h, Cmax 246.604 +/- 71.165 ng.ml-1, AUC 2651.158 +/- 1039.050 ng.h.ml-1, CL 0.033 +/- 0.010 ng.ml-1.

Expression of interferon regulatory factor (IRF) genes and response to interferon-alpha in chronic myeloid leukaemia

Interferon regulatory factors (IRF) 1 and 2 are DNA-binding proteins which control interferon (IFN) gene expression. IRF1 functions as an activator for IFN and IFN-inducible genes, whereas IRF2 represses the action of IRF1. Expression of the two regulatory genes is itself IFN-inducible. Because therapeutic responses of chronic myeloid leukaemia (CML) patients to IFN-alpha may be determined by intracellular levels of these two mutually antagonistic transcription factors, we have devised a competitive reverse-transcription polymerase chain reaction (RT-PCR) assay which provides an estimate of the ratio of IRF1 to IRF2 expression in a given cell population. Analysis of peripheral blood leucocytes from 25 normal individuals showed that the IRF1:IRF2 ratio varied between 1.13 and 2.30 (mean +/- s.d. 1.49 +/- 0.33). Similar values were obtained for normal bone marrow specimens, with no significant difference between CD34+ and CD34- cells. In contrast, the IRF1:IRF2 ratio in leucocytes from CML patients showed a much wider variation (0.53-5.11). Eleven out of 130 patients in chronic phase had ratios above the normal range, whereas none of the 33 blast crisis samples had a ratio >2.5. Analysis of diagnostic specimens in 59 CML patients treated subsequently with IFN-alpha showed a high IRF1:IRF2 ratio of 5.11 in one of two patients who became complete responders; all the 53 patients with minimal or no cytogenetic response had ratios below 2.5. In a separate series of 97 CML patients studied after IFN-alpha therapy a highly significant correlation was found between the IRF1:IRF2 ratio and both the cytogenetic and the molecular response (ie low concentration of BCR-ABL transcripts) to treatment: 53 out of 115 prospectively analysed samples of good cytogenetic responders had ratios above 2.0, as opposed to only 13 out of 91 samples from poor responders (P < 0.0001; chi2 test). We conclude that a high ratio of IRF1/IRF2 expression may be associated with good cytogenetic and molecular response to IFN-alpha in CML.

BCR-ABL-positive lymphoblastoid cells display limited proliferative capacity under in vitro culture conditions

We studied the kinetics of EBV-transformed B-cell lines from patients with chronic myeloid leukaemia (CML) using RT-PCR for BCR-ABL transcripts and immunoglobulin heavy chain (IgH) gene rearrangements. Peripheral blood mononuclear cells, obtained from four patients with CML in chronic phase and from one in accelerated phase, were incubated with supernatant from the B95-8 EBV producing cell line. In 11/25 (44%) B-cell cultures established we demonstrated the presence of BCR-ABL transcripts at intervals ranging from 32 to 125 d post EBV transformation. In all but two cases, evidence of BCR-ABL transcripts disappeared with time. Cultures were initially polyclonal with respect to IgH rearrangements but became progressively oligoclonal, suggesting the longer-term survival of fewer clones, all of which were BCR-ABL negative. We conclude that BCR-ABL-positive lymphoid cultures can be established in the short term from the majority of patients with CML but they have limited capacity to survive in the longer term. Therefore, in lymphoid cells the presence of the BCR-ABL chimaeric gene appears to confer no survival advantage.

Reverse transcription/polymerase chain reaction (RT/PCR) amplification of very small numbers of transcripts: the risk in misinterpreting negative results

Technical modifications of the reverse-transcription/polymerase chain reaction (RT/PCR) amplification method now permit its use to detect amplified products from as few as one abnormal cell, either isolated or mixed with a larger number of normal cells. We studied the reproducibility of such results using as targets low numbers of cells from chronic myeloid leukaemia (CML) patients and CML cell lines in quintuplicate two-step RT/PCR designed to amplify BCR-ABL sequences. When one K562 or KYO1 cell was diluted in 10(3) non-CML HL60 cells, an amplification product was obtained in each test; at greater dilutions BCR-ABL transcripts were detected erratically. Titration of cDNA synthesised from 5 x 10(7) cells from four CML patients showed that whereas positive BCR-ABL sequences could be amplified in some tests starting with as little as a 1 in 10(7) dilution of cDNA template (corresponding to 5-10 cells), the dilution threshold for reproducible amplification was around 1 to 5 in 10(5) (100-500 cells). Quantitative PCR analysis revealed that reactions from 1 in 10(7) diluted cDNA contained less than 10 BCR-ABL transcripts as the starting template. The stochastic nature of the amplification from such small numbers of transcripts was illustrated by results of 10 replicate PCR tests on cDNA from a patient expressing both b3a2 and b2a2 transcripts: dilutions of cDNA up to 1 in 10(5) yielded dual transcript amplification in all 10 tests, but the 1 in 10(7) cDNA dilution resulted in b3a2 and b2a2 products in three tests, b3a2 only in three, b2a2 only in one and no amplification in three tests. We conclude that this 'sampling effect' may yield false-negative results and thus misinterpretation of data regarding assessment of gene expression when the quantity of target material available for study is very small.

Lack of correlation between ABL-BCR expression and response to interferon-alpha in chronic myeloid leukaemia

Interferon-alpha (IFN-alpha) is useful in the treatment of Philadelphia (Ph)-positive chronic myeloid leukaemia (CML). There is, however, a marked heterogeneity among CML patients in relation to their response to IFN-alpha treatment, the reasons for which are unknown. Since the reciprocal ABL-BCR gene is transcriptionally active in only a proportion of CML patients, it has been suggested that response to IFN-alpha may correlate with ABL-BCR expression. In the present study we have tested 209 Ph-positive CML patients for expression of ABL-BCR, BCR-ABL and the normal BCR and ABL genes by reverse transcriptase/polymerase chain reaction (RT/PCR). Whereas BCR-ABL, BCR and ABL transcripts were detected in all the patients, ABL-BCR expression was observed in 59% of the cases. A group of 105 patients within this series was treated with IFN-alpha; 33% achieved a complete or major cytogenetic response (< 35% Ph-positive metaphases) and the remaining 67% showed minimal or no response to IFN-alpha. The proportions of patients who were ABL-BCR positive (63%) and ABL-BCR negative (37%) were the same for good responders and poor responders, suggesting that there is no correlation between ABL-BCR expression and cytogenetic response to IFN-alpha in CML.

Singles transmission in volume-imaging PET with a 137Cs source

The feasibility of a new method of attenuation correction in PET has been investigated, using a single-photon emitter for the transmission scan. The transmission scan is predicted to be more than a factor of ten faster with the singles method than the standard coincidence method, for comparable statistics. Thus, a transmission scan be completed in 1-2 min, rather than 10-20 min, as is common practice with the coincidence method. In addition, a potential advantage of using the single-photon source 137Cs, which has an energy of 662 keV, is that postinjection transmission studies can be performed using energy discrimination to separate the transmission from the emission data at 511 keV. In order to compensate for the energy difference of the attenuation coefficients at 662 keV compared to 511 keV, the transmission images are segmented into two compartments, tissue and lung, and known values (for 511 keV) of attenuation are inserted into these compartments. This technique also compensates for the higher amount of scatter present with the singles method, since it is not possible to use a position gate (based on collinearity of the source and two detector positions) as is commonly done with a positron-emitting source. We have demonstrated, with experimental phantom studies, that the singles transmission method combined with segmentation gives results equivalent both qualitatively and quantitatively to the coincidence method, but requires significantly less time.

Balanced parental contribution to the ABL component of the BCR-ABL gene in chronic myeloid leukemia

Genomic imprinting has recently been associated with the reciprocal t(9;22) chromosome translocation of chronic myeloid leukaemia (CML). This translocation gives rise to a 22q-, or Philadelphia (Ph), chromosome and a derivative 9q+. Based on heterochromatin polymorphisms, it was reported that the former is of maternal and the latter of paternal origin in every case of CML. This parental bias led to the hypothesis that the genes disrupted by the translocation, BCR and ABL, were themselves imprinted, and that in CML the BCR-ABL gene was formed by BCR sequences of maternal and ABL sequences of paternal origin. We have identified a BstNl restriction fragment length polymorphism in the ABL coding sequence which enabled us to investigate directly the expression and inheritance of the two ABL alleles in heterozygous CML patients. Amplification of the specific BCR-ABL and normal ABL mRNA messages by reverse transcriptase-polymerase chain reaction in these patients showed that the ABL moiety of the BCR-ABL gene has an even chance of being the paternal or the maternal copy. We conclude therefore that there is no parental bias in the origin of the translocated ABL gene and no evidence for genomic imprinting of ABL in CML.

Enhanced immunogenicity in mice with hepatitis B vaccine complexed to human hepatitis B immunoglobulin

Purified human hepatitis B immunoglobulin (HBIG) was complexed to plasma derived hepatitis B vaccine (HBVac) at different concentrations and used to immunize Balb/c mice. An enhanced humoral immune response was observed when HBVac was complexed to HBIG in excess of antigen, compared to that immunized with the vaccine alone. Proliferation of splenic lymphocytes was detected when mice were immunized with HBIG complexed to HBVac (0.2-1 microgram), whereas in mice immunized only with HBVac at one microgram, no lymphocyte proliferation was observed. The enhanced immunogenicity of HBIG: HBVac is T cell dependent. The importance of using critical ratio of HBIG and HBVac is indicated, and future application of this complex for vaccination of low- or nonresponders to the present HBVac, as well as for treatment of chronic hepatitis B patients is discussed.

Temperature and Size Variabilities of the Western Pacific Warm Pool

Variabilities in sea-surface temperature and size of the Western Pacific Warm Pool were tracked with 10 years of satellite multichannel sea-surface temperature observations from 1982 to 1991. The results show that both annual mean sea-surface temperature and the size of the warm pool increased from 1983 to 1987 and fluctuated after 1987. Possible causes of these variations include solar irradiance variabilities, EI Niño-Southern Oscillation events, volcanic activities, and global warming.