Observation of Transverse Spin-Dependent Azimuthal Correlations of Charged Pion Pairs in p^{↑}+p at sqrt[s]=200 GeV

We report the observation of transverse polarization-dependent azimuthal correlations in charged pion pair production with the STAR experiment in p^{↑}+p collisions at RHIC. These correlations directly probe quark transversity distributions. We measure signals in excess of 5 standard deviations at high transverse momenta, at high pseudorapidities η>0.5, and for pair masses around the mass of the ρ meson. This is the first direct transversity measurement in p+p collisions.

Azimuthal Anisotropy in U+U and Au+Au Collisions at RHIC

Collisions between prolate uranium nuclei are used to study how particle production and azimuthal anisotropies depend on initial geometry in heavy-ion collisions. We report the two- and four-particle cumulants, v_{2}{2} and v_{2}{4}, for charged hadrons from U+U collisions at sqrt[s_{NN}]=193  GeV and Au+Au collisions at sqrt[s_{NN}]=200  GeV. Nearly fully overlapping collisions are selected based on the energy deposited by spectators in zero degree calorimeters (ZDCs). Within this sample, the observed dependence of v_{2}{2} on multiplicity demonstrates that ZDC information combined with multiplicity can preferentially select different overlap configurations in U+U collisions. We also show that v_{2} vs multiplicity can be better described by models, such as gluon saturation or quark participant models, that eliminate the dependence of the multiplicity on the number of binary nucleon-nucleon collisions.

Avoiding misannotation of in-source fragmentation products as cellular metabolites in liquid chromatography-mass spectrometry-based metabolomics

Liquid chromatography-mass spectrometry (LC-MS) technology allows for rapid quantitation of cellular metabolites, with metabolites identified by mass spectrometry and chromatographic retention time. Recently, with the development of rapid scanning high-resolution high accuracy mass spectrometers and the desire for high throughput screening, minimal or no chromatographic separation has become increasingly popular. When analyzing complex cellular extracts, however, the lack of chromatographic separation could potentially result in misannotation of structurally related metabolites. Here, we show that, even using electrospray ionization, a soft ionization method, in-source fragmentation generates unwanted byproducts of identical mass to common metabolites. For example, nucleotide-triphosphates generate nucleotide-diphosphates, and hexose-phosphates generate triose-phosphates. We evaluated yeast intracellular metabolite extracts and found more than 20 cases of in-source fragments that mimic common metabolites. Accordingly, chromatographic separation is required for accurate quantitation of many common cellular metabolites.

Chemical genetics of rapamycin-insensitive TORC2 in S. cerevisiae

Current approaches for identifying synergistic targets use cell culture models to see if the combined effect of clinically available drugs is better than predicted by their individual efficacy. New techniques are needed to systematically and rationally identify targets and pathways that may be synergistic targets. Here, we created a tool to screen and identify molecular targets that may synergize with new inhibitors of target of rapamycin (TOR), a conserved protein that is a major integrator of cell proliferation signals in the nutrient-signaling pathway. Although clinical results from TOR complex 1 (TORC1)-specific inhibition using rapamycin analogs have been disappointing, trials using inhibitors that also target TORC2 have been promising. To understand this increased therapeutic efficacy and to discover secondary targets for combination therapy, we engineered Tor2 in S. cerevisiae to accept an orthogonal inhibitor. We used this tool to create a chemical epistasis miniarray profile (ChE-MAP) by measuring interactions between the chemically inhibited Tor2 kinase and a diverse library of deletion mutants. The ChE-MAP identified known TOR components and distinguished between TORC1- and TORC2-dependent functions. The results showed a TORC2-specific interaction with the pentose phosphate pathway, a previously unappreciated TORC2 function that suggests a role for the complex in balancing the high energy demand required for ribosome biogenesis.

Triptolide inhibits the multidrug resistance in prostate cancer cells via the downregulation of MDR1 expression

Triptolide (TPL) is a diterpenoid triepoxide derived from the Chinese herb Tripterygium wilfordii and possesses anti-tumor activity against a range of cancer cells. However, the effect of TPL on prostate cancer cells and its potential to overcome multidrug resistance (MDR) have not been explored. Therefore, in this study we used prostate cancer cell line DU145 as the experimental model and established DU145/ADM cell line resistant to adriamycin (ADM). Our results showed that TPL inhibited the proliferation and induced the cell cycle arrest and apoptosis of DU145 cells in a dose and time dependent manner. TPL decreased the levels of Cyclin D1 and anti-apoptotic protein Bcl-2, and increased the levels of pro-apoptotic proteins Fas and Bax. Furthermore, we found that TPL restored the sensitivity DU145/ADM cells to ADM in a dose dependent manner, and this was accompanied by the inhibition of MDR1 expression at both mRNA and protein levels. Taken together, these results provide strong evidence that TPL overcomes MDR in prostate cancer cells by downregulating MDR1 expression, and suggest that TPL is a promising agent for prostate cancer therapy, especially for chemoresistant prostate cancer.

GATA-3 is down-regulated in patients with clear cell renal carcinoma

BACKGROUND

GATA-3 is a transcription factor involved in human growth and development. Recent studies found its association with breast cancer, however, its expression profile in renal cell carcinoma (RCC) has not been investigated.

MATERIAL AND METHOD

The study included 35 patients submitted to radical nephrectomy with confirmed pathological diagnosis of RCC. Normal control kidney tissues were obtained from 25 living kidney donors and tissues were biopsied before implantation. The majority of RCC samples were diagnosed as clear cell renal cell carcinoma (94.3%) except for 1 case of papillary RCC and 1 case of collecting duct carcinoma. GATA-3 expression was evaluated by quantitative PCR and Western blotting (WB) in RCC samples and normal kidneys respectively, immunohistochemical staining was performed as well. Meanwhile, the GATA-3 expression in two cancer cell lines (786-O, ACHN) and normal kidney epithelial cells (HK-2) was detected by PCR and WB. In addition, renal cancer cells and HK-2 cells were cultivated and detected by confocal microscopy for the exact intra-cellular localization of GATA-3.

RESULTS

Data showed a significant down-regulation of GATA-3 expression present in neoplastic tissues compared with normal tissues; similarly, GATA-3 was significantly attenuated in all renal cancer cell lines compared with normal HK-2 cells. Confocal displayed a strong cytoplasmic immno-fluorescence activity of GATA-3 with peri-nuclear zone in HK-2, whereas the intensity in cancer cells was markedly weaker than that of HK-2.

CONCLUSIONS

In summary, our present study clarifies that the aberrant expression profile of GATA-3 in human RCC is possibly involved with tumorigenesis, and the complicated mechanism is worthy of further investigation.

Nucleotide degradation and ribose salvage in yeast

Nucleotide degradation is a universal metabolic capability. Here we combine metabolomics, genetics and biochemistry to characterize the yeast pathway. Nutrient starvation, via PKA, AMPK/SNF1, and TOR, triggers autophagic breakdown of ribosomes into nucleotides. A protein not previously associated with nucleotide degradation, Phm8, converts nucleotide monophosphates into nucleosides. Downstream steps, which involve the purine nucleoside phosphorylase, Pnp1, and pyrimidine nucleoside hydrolase, Urh1, funnel ribose into the nonoxidative pentose phosphate pathway. During carbon starvation, the ribose-derived carbon accumulates as sedoheptulose-7-phosphate, whose consumption by transaldolase is impaired due to depletion of transaldolase's other substrate, glyceraldehyde-3-phosphate. Oxidative stress increases glyceraldehyde-3-phosphate, resulting in rapid consumption of sedoheptulose-7-phosphate to make NADPH for antioxidant defense. Ablation of Phm8 or double deletion of Pnp1 and Urh1 prevent effective nucleotide salvage, resulting in metabolite depletion and impaired survival of starving yeast. Thus, ribose salvage provides means of surviving nutrient starvation and oxidative stress.

Organochlorine pesticides and polychlorinated biphenyls in soils surrounding the Tanggu Chemical Industrial District of Tianjin, China

The spatial distribution of persistent organic pollutants (POPs) was examined in soils surrounding the Tanggu Chemical Industrial District in Tianjin, China. The concentrations of hexachlorocyclohexanes (HCHs), dichlorodiphenyltrichloroethanes (DDTs), hexachlorobenzenes (HCBs), and polychlorinated biphenyls (PCBs) were determined in 70 surface soils using accelerated solvent extraction and gas chromatography with electron capture detection. The results showed that the ranges of ∑HCH, ∑DDT, ΣHCB, and ∑PCB concentrations in soils were 2.1-12,549 μg kg(-1) (average, 965 μg kg(-1)), n.d.-2,033 μg kg(-1) (average, 88.4 μg kg(-1)), n.d.-1,924 μg kg(-1) (average, 349 μg kg(-1)), and n.d.-373 μg kg(-1) (average, 46.2 μg kg(-1)), respectively. Of these, HCHs were the dominant POPs, accounting for 75 % of the total organochlorine pesticide (OCP) residues. Overall, the spatial distribution of OCP concentrations showed a decreasing trend from the center of the Tanggu District to the surrounding areas. Two major pollution sources were Tianjin Dagu Chemical Co., Ltd. in the district center and the Tianjin Chemical Plant in Hangu District. In contrast, PCB concentrations were relatively high in the Haihe estuary to the east and low to the west of the study area. Component analysis of OCPs in these soils showed that they mainly came from industrial point sources. Compared with soils in other regions, soil DDT pollution was at a medium level in the Tanggu Chemical Industrial District, but associated HCH, HCB, and PCB pollution was relatively heavy. By multivariate statistical analyses, Tianjin Dagu Chemical Co., Ltd. was recognized as the main source of POPs, and soil properties were clarified to play an important role on the distribution and composition of POPs, especially the organic carbon content.

Naloxone inhibition of lipopolysaccharide-induced activation of retinal microglia is partly mediated via the p38 mitogen activated protein kinase signalling pathway

OBJECTIVES

To investigate the effects and underlying mechanism of action of naloxone on lipopolysaccharide (LPS)-induced activation of retinal microglia in vitro.

METHODS

Rat retinal microglia primary cultures were divided into four treatment groups: untreated; 1 μg/ml LPS for 12 h; 0.5, 1.0 or 2.0 μM naloxone for 30 min before LPS; 2.5 or 5.0 μM SB203580 for 12 h before LPS and naloxone. Levels of tumour necrosis factor (TNF)-α and interleukin (IL)-1β were determined by enzyme-linked immuno sorbent assay. Western blot analysis and double immunofluorescence were used to examine activation of the mitogen activated protein kinase (MAPK) signalling pathway.

RESULTS

LPS induced an increase in TNF-α and IL-1β in culture supernatants, which was dose-dependently inhibited by naloxone. Naloxone also dose-dependently inhibited LPS-induced increases in phosphorylated p38 MAPK. Pretreatment of cells with SB203580 attenuated the inhibitory effect of naloxone on TNF-α and IL-1β production.

CONCLUSIONS

Naloxone suppressed LPS-induced activation of cultured retinal microglia and this suppression appeared to occur partly through the p38 MAPK signalling pathway. Naloxone may have therapeutic potential in neuro degenerative diseases characterized by the activation of microglia.

Ultrasensitive regulation of anapleurosis via allosteric activation of PEP carboxylase

Anapleurosis is the filling of the tricarboxylic acid cycle with four-carbon units. The common substrate for both anapleurosis and glucose phosphorylation in bacteria is the terminal glycolytic metabolite phosphoenolpyruvate (PEP). Here we show that Escherichia coli quickly and almost completely turns off PEP consumption upon glucose removal. The resulting buildup of PEP is used to quickly import glucose if it becomes available again. The switch-like termination of anapleurosis results from depletion of fructose-1,6-bisphosphate (FBP), an ultrasensitive allosteric activator of PEP carboxylase. E. coli expressing an FBP-insensitive point mutant of PEP carboxylase grow normally when glucose is steadily available. However, they fail to build up PEP upon glucose removal, grow poorly when glucose availability oscillates and suffer from futile cycling at the PEP node on gluconeogenic substrates. Thus, bacterial central carbon metabolism is intrinsically programmed with ultrasensitive allosteric regulation to enable rapid adaptation to changing environmental conditions.

[Monitoring the total suspended matter of Lake Chaohu based on quasi-analytical algorithm]

There has been some effort by using quasi-analytical algorithm (QAA), which is based on radiative transfer theory to calculate backscattering coefficients of waters. A field investigation in Lake Chaohu was carried out in June, 2009, and a dataset including many parameters such as remote sensing reflectance, absorption and attenuation coefficients, concentration of total suspended matter (c(TSM)), had been obtained. Thereafter, a model for estimating c(TSM), was built, and in order to improve the accuracy, we employed the QAA algorithm to simulate backscattering ratio of Lake Chaohu. The results show that: 1) 807 nm and 834 nm are determined as optimum bands for the Two Near-Infrared Bands Method in Lake Chaohu, and the average specific scattering coefficient of suspended matters at the wavelength of 807 nm and 834 nm is 0.411 m2 x g(-1) and 0.395 m2 x g(-1) respectively; 2) The backscattering ratio of Lake Chaohu is 0.029, and better accuracy is achieved by using this value rather than other empirical values. The root mean square error (RMSE) and mean absolute percentage error (MAPE) of the estimated c(TSM) with calculated backscattering ratio are 12. 143 mg x L(-1) and 24.378%; 3) It is found that stations with high c(TSM) (nearly greater than 30 mg x L(-1)) can have more stable and reliable estimated results.

Molecular cloning of a new wheat calreticulin gene TaCRT1 and expression analysis in plant defense responses and abiotic stress resistance

Calreticulin proteins play essential roles in regulating various metabolic processes and in molecular signal transduction in animals and plants. Using homologous PCR, we screened a cDNA library of the wheat resistance gene Yr5 from a near-isogenic line in the susceptible common wheat variety Taichung 29, which was inoculated with an incompatible race CYR32 of Puccinia striiformis. We isolated a novel full-length cDNA encoding calreticulin protein, which we named TaCRT1. Sequence analyses indicated that TaCRT1 contains an open reading frame of 1287 bp in length; it was deduced to encode 428 amino acids. Clustering analysis showed that TaCRT1 belongs to group III of the calreticulin protein family. Semi-quantitative RT-PCR was used to analyze expression profiles of the isolated gene under biotic and abiotic stresses. Expression of TaCRT1 was suppressed by exogenous application of phytohormones, such as abscisic acid and methyl jasmonate, and by dehydration; but it was induced by CYR32 infection and cold treatment. Based on the expression patterns, we propose that TaCRT1 participates in regulatory processes involved in defense responses and stress resistance in wheat.

[Simulation of backscattering coefficients of inland waters]

When we simulated backscattering coefficients (b(bp)) using quasi-analytical algorithm and optical closure theory, it was found that the position of reference wavelength (lambda(0)) had great impact on final results. In order to identify influence factors of the optimum lambda(0), datasets of Lake Taihu, Lake Chaohu and Lake Dianchi were used. After simulating of b(bp), the relationship between optimum lambda(0) and associated water quality parameters were analyzed. Meanwhile, power functions were utilized to model b(bp) spectra, and spectral slope parameters of Lake Taihu, Lake Chaohu and Lake Dianchi were 2.643 +/- 0.317, 2.719 +/- 0.242, 1.638 +/- 0.534, respectively. The results indicate that: (1) When the whole lakes are taken as objects of study, the lambda(0) should be changed to longer wavelength with the increasing of total suspended particle matter concentration (c(SPM)), suspended organic particle matter concentration (c(SPOM)) and chlorophyll a concentration (c(CHL)), the optimum location of lambda(0) of Lake Taihu is 695 nm, Lake Chaohu is 720 nm and Lake Dianchi is 730 nm; (2) When the samples in lakes are taken as objects of study, the influence factors are different due to the complexity of optical properties of inland waters. But it is to be noted that, c(SPM) is a key factor in common. Besides, the regularity mentioned above should be weakened with high c(CHL). (3) The relationship between b(bp) and c(SPM) is much stronger in the waters with suspended particles dominated by inorganic particles, in Lake Taihu, for example, relationship between these two variables is strong with R2 = 0.852.

[Estimating of backscattering rate in Lake Chaohu based on bio-optical model]

Backscattering rate is the important factor of above water spectra. A bio-optical model simplified in near-infrared bands was constructed to estimate backscattering rate in Lake Chaohu by using the in-situ data measured in June 2009. The results show that the maximum value of backscattering rate in Lake Chaohu is 0.059, the minimum value is 0.001 4 and the mean value is 0.023 6. Backscattering rate and spatial differences in the west of Lake Chaohu are all greater than that in the east. In addition, particle refractive index of each sampling site was calculated by using backscattering rate. The dominant factors of in-water particles were determined according to the change scopes of refractive index. The results show that 74% of all sampling sites are dominated by inorganic particles, 18.5% of all sampling sites are dominated by both phytoplankton and inorganic particles, and the rest of sampling sites which accounts only for 7.4% of all sampling sites are dominated by phytoplankton. This indicates that backscattering character of Chaohu Lake is mainly affected by inorganic particles, while the effect of algae particle is relatively small.

[Three wavelengths factor model of chlorophyll concentrations inversion based on different spectral dominating factors for inland lake]

A hierarchical cluster analysis is applied to the data set of R(rs) spectra. Combing the inherent optical and measured water color characteristics, we determine factors of the variability for each class of R(rs) spectra. The R(rs) measured from Lake Taihu, Chaohu, Dianchi and Three Gorges Reservoir can be divided into three spectrally distinct classes: class 1, class 2 and class 3. Class 1 is associated with water optical property dominated by total suspended matter and phytoplankton. Class 2 is associated with water optical property dominated by phytoplankton. And Class 3 is associated with water optical property dominated by total suspended matter. The three wavelengths factor Chlorophyll a concentration inversion models were developed according to different class water optical characteristics, which means relative error and RMSE are 23.8% and 8.5 mg/m3, and have higher accuracy than the model developed without classification.

Inhibition of the rapid component of the delayed rectifier potassium current in ventricular myocytes by angiotensin II via the AT1 receptor

BACKGROUND AND PURPOSE

There is increasing evidence that angiotensin II (Ang II) is associated with the occurrence of ventricular arrhythmias. However, little is known about the electrophysiological effects of Ang II on ventricular repolarization. The rapid component of the delayed rectifier K(+) current (I(Kr)) plays a critical role in cardiac repolarization. Hence, the aim of this study was to assess the effect of Ang II on I(Kr) in guinea-pig ventricular myocytes.

EXPERIMENTAL APPROACH

The whole-cell patch-clamp technique was used to record I(Kr) in native cardiocytes and in human embryonic kidney (HEK) 293 cells, co-transfected with human ether-a-go-go-related gene (hERG) encoding the alpha-subunit of I(Kr) and the human Ang II type 1 (AT(1)) receptor gene.

KEY RESULTS

Ang II decreased the amplitude of I(Kr) in a concentration-dependent manner with an IC(50) of 8.9 nM. Action potential durations at 50% (APD(50)) and 90% (APD(90)) repolarization were prolonged 20% and 16%, respectively by Ang II (100 nM). Ang II-induced inhibition of the I(Kr) was abolished by the AT(1) receptor blocker, losartan (1 muM). Ang II decreased hERG current in HEK293 cells and significantly delayed channel activation, deactivation and recovery from inactivation. Moreover, PKC inhibitors, stausporine and Bis-1, significantly attenuated Ang II-induced inhibition of I(Kr).

CONCLUSIONS AND IMPLICATIONS

Ang II produces an inhibitory effect on I(Kr)/hERG currents via AT(1) receptors linked to the PKC pathway in ventricular myocytes. This is a potential mechanism by which elevated levels of Ang II are involved in the occurrence of arrhythmias in cardiac hypertrophy and failure.

Properties of MSW fly ash-calcium sulfoaluminate cement matrix and stabilization/solidification on heavy metals

In this paper, investigations were undertaken to formulate the properties of fly ash-calcium sulfoaluminate (CSA) cement matrix by blending MSW fly ash with CSA cement. The compressive strength, pore structure, hydration phases, and leaching behavior of Zn and Pb doped MSW fly ash-CSA cement matrices were determined by XRD, MIP, DSC, FTIR, EDX, TCLP leaching test and other experiments. The results showed that the addition of MSW fly ash to form fly ash-CSA cement matrix reduced the compressive strengths of matrices and made the pore distribution of matrices coarser, compared to that of pure CSA cement matrix. However, fly ash-CSA cement matrix could effectively immobilize high concentration of heavy metal such as lead and zinc with much lesser leaching of TCLP. Besides ettringite AFt, Friedel phase was a new hydration phase formed in the matrix. The formation of these hydration phases was responsible for huge reservoir of heavy metal stabilization by chemical fixing. Therefore, it could be postulated that MSW fly ash-CSA cement matrix was a potential new constituent of S/S matrix for high concentration of heavy metals such as Zn and Pb ions.

FePt nanocluster films for high-density magnetic recording

High anisotropy L1(0) ordered FePt thin films are considered to have high potential for use as high areal density recording media, beyond 1 Tera bit/in2. In this paper, we review recent results on the synthesis and magnetic properties of L1(0) FePt nanocomposite films. Several fabrication methods have been developed to produce high-anisotropy FePt films: epitaxial and non-epitaxial growth of (001)-oriented FePt:X (X = Au, Ag, Cu, C, etc.) composite films that might be used for perpendicular media; monodispersed FePt nanocluster-assembled films grown with a gas-aggregation technique and having uniform cluster size and narrow size distribution; self-assembled FePt particles prepared with chemical synthesis by reduction/decomposition techniques, etc. The magnetic properties are controllable through variations in the nanocluster properties and nanostructure. FePt and related films show promise for development as heat-assisted magnetic recording media at extremely high areal densities. The self-assembled FePt arrays show potential for approaching the ultimate goal of single-grain-per-bit patterned media.

Research on inhibitive behaviors of electrolysis on the growth of Microcystis aeruginosa

Electrochemical method using a novel Ti/RuO2 anode was employed to inhibit a typical cyanobacteria, Microcystis aeruginosa (M. aeruginosa) under different electrolytic conditions. It is demonstrated that Ti/RuO2 anode was more efficient than traditional graphite anode in M. aeruginosa inhibition. The experimental results showed that the higher current density or longer electrolytic time could effectively improve the inhibition of M. aeruginosa. In addition, sodium chloride was a more effective electrolyte than sodium sulfate to enhance inhibition. The maximum inhibiting rate dose to 100% could be obtained at a current density of 12 mA cm(-2) when sodium chloride was used as a supporting electrolyte. Furthermore, UV-Visible spectra demonstrated that the structures of phycocyanins and chlorophyll a (Chl a) in M. aeruginosa could be changed or destroyed during electrolysis. Moreover, EPR spectra showed the generation of the free radicals through electrolysis, which might be one of the reasons responsible for the inhibition of algal growth.

The tumor suppressor adenomatous polyposis coli gene is associated with susceptibility to schizophrenia

The etiology of schizophrenia is unclear, although family, twin, and linkage studies implicate genetic factors. Here, we identified adenomatous polyposis coli (APC), a tumor suppressor gene, as a risk factor for schizophrenia. We compared leukocytic gene expression patterns of six pairs of patients with schizophrenia and healthy controls by microarray. APC expression levels were significantly increased in all patients compared to healthy controls. To confirm the findings of microarray analysis, we measured expression levels of APC in the leukocytes from 30 relapse patients taking antipsychotic medication, 29 first-episode drug-naïve patients, and 30 healthy controls using real-time quantitative reverse transcription (RT)-polymerase chain reaction (PCR). APC expression levels were significantly increased in leukocytes of schizophrenics both taking and not taking antipsychotic medication and hence the increase of APC expression was not due to antipsychotic medication. APC is located at 5q21-22, which has been previously reported to be linked with schizophrenia. Further, we performed the transmission disequilibrium test (TDT) and TDT based on haplotypes to search for the association between schizophrenia and APC by examining 163 parent-offspring trios of Chinese descent. We analyzed three single-nucleotide polymorphisms (SNPs) (rs2229992, rs42427, rs465899) at the exon region of APC. TDT showed that the three SNPs are significantly associated with schizophrenia (TDT chi(2)=4.23, P<0.05; 4.15, P<0.05; 8.49 P<0.01, respectively; HHRRchi(2)=5.54, P<0.05; 4.40, P<0.05; 9.79, P<0.01, respectively). We found a significant association between the APC haplotypes from rs2229992-rs42427-rs465899 and schizophrenia (Global chi(2)=44.376,df=7, P<0.001). The C-A-T haplotype has a frequency of more than 57% and has a strong association with schizophrenia (chi(2)=15.04, P<0.001). These results indicate that the APC may be a candidate gene conferring susceptibility to schizophrenia and also may be associated with reduced vulnerability to cancer in schizophrenia.

Possible association of the MAG locus with schizophrenia in a Chinese Han cohort of family trios

Neurotransmitter-based hypotheses have so far led to only moderate success in predicting new pathogenetic findings in etiology of schizophrenia. On the other hand, the more recent oligodendroglia hypotheses of this disorder have been supported by an increasing body of evidence. For example, the expression level of the myelin associated glycoprotein (MAG) gene has been shown to be significantly lower in schizophrenia patient groups compared to control groups. Such an effect might be a result of genetic variations of the MAG gene. In order to test this hypothesis, we genotyped four markers within the MAG locus in 413 trios sample of the Han Chinese using allele-specific PCR. None of the four markers revealed noticeable allelic significance. However, the four-marker and two-marker haplotypes covering components rs720309 and rs720308 were observed to be significantly associated with schizophrenia (P < 0.0001) in this study. In addition, we identified one common risk haplotype TA (rs720309-rs720308, present in 78.5% of the general population) that showed increased evidence of overtransmission from parents to affected offspring (P = 0.0001). The results demonstrated MAG might play a role in genetic susceptibility to schizophrenia. Furthermore, our finding of a possible association between the MAG locus and schizophrenia is in agreement with the hypotheses of oligodendrltic and myelination dysfunction.

Quantitative analysis of the response of an electrochemical biosensor for progesterone in milk

An electrochemical biosensor for progesterone in cow's milk was developed and used in a competitive immunoassay by Hart et al. (1977, Studies towards a disposable screenprinted amperometric biosensor for progesterone, Biosens. Bioelectron. 12, 1113-1121). The sensor was fabricated by depositing anti-progesterone monoclonal antibody (mAb) onto screen-printed carbon electrodes (SPCEs) which were coated with rabbit anti-sheep IgG (rIgG). This sensor was operated following the steps of competitive binding between sample and conjugate (alkaline-phosphatase-labelled progesterone) for the immobilised mAb sites and measurements of an amperometric signal in the presence of p-nitrophenylphosphate using either colorimetric assays or cyclic voltammetry. The hook effect of the progesterone biosensor was found in the concentration range of milk progesterone between 0 and 5 ng/ml when the sensor was fabricated using a loading of 25 ng rIgG per electrode of a diameter of 3 mm and a 1/50 dilution of mAb. A computer model has been developed in this study to simulate the operation of this progesterone biosensor with consideration of the fabrication processes. This paper presents the results of validating the computer model and the model has predicted the hook effect as observed in tests. The model thus reveals that the hook effect is determined by the total number of binding sites available and the rates of labelled and unlabelled progesterone diffusing towards the sensor surface and the binding rates.

[Role of calcineurin in cardiac fibroblast proliferation stimulated by angiotensin II]

The present study was undertaken to observe the role of calcineurin (CaN) in the angiotensin II (Ang II) stimulated cardiac fibroblast proliferation. In cultured cardiac fibroblasts of neonatal rats, Ang II was used to stimulate proliferation while CaN was inhibited by CaN CsA inhibitor cyclosporin A (CsA). (3)H-TdR incorporation, activity of CaN and intracellular calcium concentration were measured. (3)H-TdR incorporation of Ang II stimulated fibroblasts was 72% higher than control (P<0.01), which was inhibited by CsA (0.1 10 micromol/L) in a dose dependent manner. Intracellular Ca(2+) level and CaN activity of Ang II stimulated fibroblasts were respectively 112% (P<0.01) and 17%(P<0.05) higher than control. It is concluded that CaN may play an important role in signal transduction of the Ang II induced cardiac fibroblast proliferation.

Effect of moxonidine on carotid sinus baroreflex in anesthetized rats

AIM

To study the effect of moxonidine (Mox) on carotid sinus baroreflex.

METHODS

By perfusing the carotid sinus in anesthetized rats, the functional parameters of baroreflex were measured. The femoral artery was perfused with constant flow and the change of perfusing pressure was recorded to determine the effect of Mox on vascular tone.

RESULTS

Mox 32 and 100 mumol.L-1 shifted the functional curve of carotid sinus baroreflex to the right and upward, with the reduction in peak slope and in reflex decrease of mean arterial pressure, suggesting that Mox produced an inhibitory effect on baroreflex. The effect of Mox 100 mumol.L-1 on baroreflex was completely blocked by efaroxan 100 mumol.L-1. Mox increased vascular resistance.

CONCLUSION

Mox inhibits carotid baroreflex via its constrictive action on sinus wall.

[Isolation of novel expression sequences of C2H2 type zinc finger protein gene from human brain tissue according to the conservation of zinc finger motif]

By low stringency PCR amplification of genomic DNA using the primers designed based on the conservation of zinc finger motif, we got 8 gradient eletrophoretic bands. After recovery of the second and third bands, the DNA fragments in them were cloned and sequenced. Compared to the GenBank database, among these 60 segments containing zinc finger motif, 23 segments were novel zinc finger genes' genomic segments. Then the human brain tissue cDNA library was screened, using these segments as probes, and 44 positive clones were obtained. Rescreening 28 of them, we got 20 rescreened clones. All of them were sequenced and sent to the GenBank DNA database for sequence analysis, the results showed that 16 were novel C2H2 type zinc finger protein cDNA segments. The cDNA segments encoding the novel C2H2 type zinc finger proteins provide the basic materials for cloning of full length cDNA of valuable novel zinc finger protein genes.

Passive transfer of Lambert-Eaton myasthenic syndrome induces dihydropyridine sensitivity of ICa in mouse motor nerve terminals

Mice were injected for 30 days with plasma from three patients with Lambert-Eaton Myasthenic Syndrome (LEMS). Recordings were made from the perineurial sheath of motor axon terminals of triangularis sterni muscle preparations. The objective was to characterize pharmacologically the identity of kinetically distinct, defined potential changes associated with motor nerve terminal Ca2+ currents (ICa) that were affected by LEMS autoantibodies. ICa elicited at 0.01 Hz were significantly reduced in amplitude by approximately 35% of control in LEMS-treated nerve terminals. During 10-Hz stimulation, ICa amplitude was unchanged in LEMS-treated motor nerve terminals, but was depressed in control. During 20- or 100-Hz trains, facilitation of ICa occurred in LEMS-treated nerve terminals whereas in control, no facilitation occurred during the trains at 20 Hz and marked depression occurred at 100 Hz. Saturation for amplitude and duration of ICa in control terminals occurred at 2 and 4-6 mM extracellular Ca2+, respectively; in LEMS-treated terminals, the extracellular Ca2+ concentration had to increase by two to three times of control to cause saturation. Amplitude of the two components of ICa observed when the preparation was exposed to 50 microM 3,4-diaminopyridine and 1 mM tetraethylammonium were both reduced by LEMS plasma treatment. The fast component (ICa,s) was reduced by 35%, whereas the slow component (ICa, s) was reduced by 37%. omega-Agatoxin IVA (omega-Aga-IVA; 0.15 microM) and omega-conotoxin-MVIIC (omega-CTx-MVIIC; 5 microM) completely blocked ICa in control motor nerve terminals. The same concentrations of toxins were 20-30% less effective in blocking ICa in LEMS-treated terminals. The residual ICa remaining after treatment with omega-Aga-IVA or omega-CTx-MVIIC was blocked by 10 microM nifedipine and 10 microM Cd2+. Thus LEMS plasma appears to downregulate omega-Aga-IVA-sensitive (P-type) and/or omega-CTx-MVIIC-sensitive (Q-type) Ca2+ channels in murine motor nerve terminals, whereas dihydropyridine (DHP)-sensitive (L-type) Ca2+ channels are unmasked in these terminals. Acute exposure (90 min) of rat forebrain synaptosomes to LEMS immunoglobulins (Igs; 4 mg/ml) did not alter the binding of [3H]-nitrendipine or [125I]-omega-conotoxin-GVIA (-omega-CgTx GVIA) when compared with synaptosomes incubated with an equivalent concentration of control Igs. Conversely, LEMS Igs significantly decreased the Bmax for [3H]-verapamil to approximately 45% of control. The apparent affinity of verapamil (KD) for the remaining receptors was not significantly altered. Thus acute exposure of isolated central nerve terminals to LEMS Igs does not increase DHP sensitivity, whereas it reduces the number of binding sites for verapamil but not for nitrendipine or omega-CgTx-GVIA. These results suggest that chronic but not acute exposure to LEMS Igs either upregulates or unmasks DHP-sensitive Ca2+ channels in motor nerve endings.

Effects of moxonidine injected into rostral ventrolateral medulla on blood pressure, heart rate, and renal sympathetic nerve activity in rats

AIM

To examine the effects of moxonidine (Mox) injected into the rostral ventrolateral medulla (RVLM) on blood pressure (BP), heart rate (HR), and the renal sympathetic nerve activity (RSNA) in anesthetized normotensive rats.

METHODS

BP, HR, and RSNA were simultaneously recorded after 1 microL Mox 1, 10, and 100 mumol.L-1 was injected into RVLM.

RESULTS

Mox 1, 10, and 100 mumol.L-1 reduced BP from 13.9 +/- 1.0 kPa to 13.0 +/- 1.7 kPa (P < 0.05), 13.8 +/- 1.8 kPa to 11.4 +/- 1.5 kPa (P < 0.01), and 13.9 +/- 1.9 kPa to 9.4 +/- 1.7 kPa (P < 0.01), respectively. Mox did not influence HR. RSNA varied with the doses: Mox 1 mumol.L-1 increased RSNA by 50% (P < 0.05), 10 mumol.L-1 insignificantly influenced RSNA (P > 0.05), and 100 mumol.L-1 reduced RSNA by 23% (P < 0.05). In sinoaortic barodenervated rats, Mox 10 mumol.L-1 inhibited RSNA by 50% (P < 0.05), which substantially differed from that in buffer nerve intact rats (P < 0.01).

CONCLUSION

Mox injected into RVLM decreased BP, but did not influence HR. The changes of RSNA did not parallel with the depressor effect of Mox.

Effects of omega-agatoxin-IVA and omega-conotoxin-MVIIC on perineurial Ca++ and Ca(++)-activated K+ currents of mouse motor nerve terminals

Effects of omega-agatoxin-IVA (omega-Aga-IVA) and omega-conotoxin-MVIIC (omega-CTx-MVIIC) on mouse motor nerve terminal Ca+2 currents and Ca(+2)-activated K+ currents (IK,Ca) were compared using the triangularis sterni preparation and perineurial recording techniques. omega-Aga-IVA caused concentration- and time-dependent block of both the fast (ICa-f) and slow (ICa-s) components of Ca+2 current. Low concentrations (10 nM) caused preferential block of ICa-s. Higher concentrations (100-150 nM) of omega-Aga-IVA blocked ICa-f effectively. omega-CTx-MVIIC blocked both ICa-s and ICa-f with equal sensitivity; however, higher concentrations and longer exposure times than those required for omega-Aga-IVA were needed. omega-CTx-MVIIC could block the residual ICa-f that remained after pretreatment with Cd+2 or omega-Aga-IVA. Increasing the extracellular Ca+2 concentration partially antagonized the effects of both omega-Aga-IVA and omega-CTx-MVIIC on ICa-s and ICa-f. Washing the preparation with toxin-free solution only slightly antagonized the effect of omega-Aga-IVA and was ineffective in omega-CTx-MVIIC-treated preparations. Low concentrations of omega-Aga-IVA and omega-CTx-MVIIC increased the duration of IK,Ca whereas higher concentrations reduced the amplitude of IK,Ca. Thus, at mouse motor nerve terminals, both omega-Aga-IVA- and omega-CTx-MVIIC-sensitive Ca+2 currents exist. omega-Aga-IVA appears to be more selective in blocking nerve terminal Ca+2 current than does omega-CTx-MVIIC. Paradoxically, block of ICa-s alone by omega-Aga-IVA and, to a lesser extent, omega-CTx-MVIIC was associated with increased duration of IK,Ca whereas block of ICa-s and ICa-f by omega-Aga-IVA and omega-CTx-MVIIC was associated with reduced amplitude of IK,Ca.

Multidrug resistance in leukemic cell line K562/A02 induced by doxorubicin

AIM

To study the mechanism of the development of multidrug resistance in leukemic cells.

METHODS

A human leukemic cell line K562/A02 was established by stepwise increase of concentrations of doxorubicin (Dox) in medium. P-glycoprotein was detected by immunohistochemistry assay. The mdr1 gene expression was measured by RT-PCR. The amplification of mdr1 gene in its genome, and DNA topisomerase II (Top II) gene expression were determined by dot-blot hybridization.

RESULTS

K562/A02 was highly cross-resistant to vincristine (VCR), homoharringtonin (HHT), amsacrine (m-AMSA), daunorubicin (Dau) and etoposide (VP-16), slightly to cytosine arabinoside (Ara-C), but not cisplatin (Cis), methotrexate (MTX) and fluorouracil (5-FU), showing a typical phenotype of MDR. Intracellular accumulation of Dau in K562/A02 was 33% as high as that in K562. P-glycoprotein P-170 was positive. In K562/A02, the mdr1 gene did not amplify, the mdr1 mRNA level was markedly higher, the Top II mRNA level was lower, and glutathione-S-transferase (GST) activity was higher than in K562.

CONCLUSION

mdr1 mRNA was overexpression and thus the encoded P-170 was responsible for MDR in K562/A02 while Top II or GST may play a role in MDR.

[Reversible elimination of K+ and Na+ currents at motor nerve terminals by SM486, a derivative of artemisinin]

Some derivatives of Artemisinin have been used as malariacides. Artemisinin derivative SM486 is water-soluble and has been shown also to have local anesthesia action. Here we report the effect of SM486 on Na+ and K+ channels at motor nerve terminals. Experiments were performed on mouse triangularis sterni nerve-muscle preparations. Presynaptic currents were picked up with a microelectrode inserted into the subendothelial space of the superficial nerve bundle under visual control using a x400 magnification water immersion objective. The results showed: (1) Both IK and INa were depressed in a dose-dependent manner, although the minimal effective concentration of SM486 for IK was lower than that for INa; (2) The depression was reversible as shown by the fact that the nearly completely blocked INa and IK currents could be restored to the control by simply washing away the perfusate SM486. (3) The decrease of IK was progressive, while the change of INa always began after IK proceeded to decrease rapidly. The effects of procaine on INa and IK are similar to SM486 but the effective concentration was higher.

The v-sis oncoprotein loses transforming activity when targeted to the early Golgi complex

The location of autocrine interactions between the v-sis protein and PDGF receptors remains uncertain and controversial. To examine whether receptor-ligand interactions can occur intracellularly, we have constructed fusion proteins that anchor v-sis to specific intracellular membranes. Fusion of a cis-Golgi retention signal from a coronavirus E1 glycoprotein to v-sis protein completely abolished its transforming ability when transfected into NIH3T3 cells. Fusion proteins incorporating mutations in this retention signal were not retained within the Golgi complex but instead were transported to the cell surface, resulting in efficient transformation. All chimeric proteins were shown to dimerize properly. Derivatives of some of these constructs were also constructed bearing the cytoplasmic tail from the glycoprotein of vesicular stomatitis virus (VSV-G). These constructs allowed examination of subcellular localization by double-label immunofluorescence, using antibodies that distinguish between the extracellular PDGF-related domain and the VSV-G cytoplasmic tail. Colocalization of sis-E1-G with Golgi markers confirmed its targeting to the early Golgi complex. The sis-E1 constructs, targeted to the early Golgi complex, exhibited no proteolytic processing whereas the mutant forms of sis-E1 exhibited normal proteolytic processing. Treatment with suramin, a polyanionic compound that disrupts ligand/receptor interactions at the cell surface, was able to revert the transformed phenotype induced by the mutant sis-E1 constructs described here. Our results demonstrate that autocrine interactions between the v-sis oncoprotein and PDGF receptors within the early Golgi complex do not result in functional signal transduction. Another v-sis fusion protein was constructed by attaching the transmembrane domain and COOH-terminus of TGN38, a protein that localizes to the trans-Golgi network (TGN). This construct was primarily retained intracellularly, although some of the fusion protein reached the surface. Deletion of the COOH-terminal region of the TGN38 retention signal abrogated the TGN-localization, as evidenced by very prominent cell surface localization, and resulted in increased transforming activity. The behavior of the sis-TGN38 derivatives is discussed within the context of the properties of TGN38 itself, which is known to recycle from the cell surface to the TGN.

The A and B isoforms of the human progesterone receptor operate through distinct signaling pathways within target cells

The biological response to progesterone is mediated by two distinct forms of the human progesterone receptor (hPR-A and hPR-B). In most cell contexts, hPR-B functions as a transcriptional activator of progesterone-responsive genes, whereas hPR-A functions as a transcriptional inhibitor of all steroid hormone receptors. We have created mutations within the carboxyl terminus of hPR which differentially effect the transcriptional activity of hPR-B in a cell- and promoter-specific manner. Analogous mutations, when introduced into hPR-A, have no effect on its ability to inhibit the transcriptional activity of other steroid hormone receptors. The observed differences in the structural requirements for hPR-B and hPR-A function suggest that transcriptional activation and repression by PR are mediated by two separate pathways within the cell. In support of this hypothesis, we have shown that hPR-A mediated repression of human estrogen receptor (hER) transcriptional activity is not dependent on hER expression level but depends largely on the absolute expression level of hPR-A. Thus, it appears that hPR-A inhibits hER transcriptional activity as a consequence of a noncompetitive interaction of hPR-A with either distinct cellular targets or different contact sites on the same target. We propose that hPR-A expression facilitates a ligand-dependent cross-talk among sex steroid receptor signaling pathways within the cell. It is likely, therefore, that alterations in the expression level of hPR-A or its cellular target can have profound effects on the physiological or pharmacological responses to sex steroid hormone receptor ligands.

Effects of inhibitor of endothelium-derived relaxing factor on hypoxic contraction of isolated pig coronary artery

Exposure of isolated pig coronary artery with endothelium intact to hypoxia Krebs-Henseleit solution aerated with 95% N2 + 5% CO2 caused a transient contractile response, and the coronary artery without endothelium exhibited a gradual decrease in basal tension. The endothelium-dependent contractile response to hypoxia was almost completely blocked by nitro-L-arginine (0.2 mmol.L-1), and inhibited by methylthioninium chloride (10 mumol.L-1). The inhibitory effect of the NLA was partially reversed by L-arginine (2 mmol.L-1). Sodium nitroprusside (10 mumol.L-1) was also completely antagonized and nicorandil (0.3 mol.L-1) remarkably reduced the hypoxic contractile response. Tetraethylammonium (10 mmol.L-1) and glibenclamide (1 mumol.L-1) had little effect on hypoxia-induced vascular contraction, whereas cromakalim (1 mumol.L-1) produced obvious relaxing effect on hypoxic response. These results suggest that suppression of basally released nitric oxide (NO) is an important mechanism of coronary vasoconstriction induced by hypoxia.

Plasmenylcholine (1-O-alk-1'-enyl-2-acyl-sn-glycero-3-phosphocholine) biosynthesis in guinea-pig heart and liver: cholinephosphotransferase is a bifunctional enzyme for the synthesis of phosphatidylcholine and plasmenylcholine

Plasmenylcholine is present in significant proportion (32% of choline phosphoglycerides) in the guinea-pig heart but exists as a minor component (3% of choline phosphoglycerides) in the guinea-pig liver. In this study, the biosynthesis of plasmenylcholine in these two organs was examined. The organs were perfused with labelled choline for 15 min and chased with unlabelled choline for up to 7 h. The labelling of phosphatidylcholine was 6-fold higher than that of plasmenylcholine in the heart and about 60-fold higher in the liver. However, the same labelling ratio was maintained throughout the chase period in both organs. Alterations in the specific radioactivity of CDP-choline caused corresponding changes in the labelling of phosphatidylcholine and plasmenylcholine. Our results suggest that in guinea-pig heart and liver, CDP-choline is the immediate precursor of biosynthesis of phosphatidylcholine and plasmenylcholine. The biochemical cause for the difference in their rates of formation between the two organs was explored. The enzyme activities for the formation of both choline phosphoglycerides were determined. The two reactions share the same characteristics, and 1,2-diacylglycerol and 1-alk-1'-enyl-2-acylglcerol were found to be mutually inhibitory in a competitive fashion. The pool sizes of 1,2-diacylglycerol and 1-alk-1'-enyl-2-acylglycerol were determined, and their ratios were found to be 42 in the heart and 422 in the liver. We conclude that cholinephosphotransferase catalyses the formation of both phosphatidylcholine and plasmenylcholine in the guinea-pig tissues and the rate of plasmenylcholine biosynthesis is dependent on the availability of 1-alk-1'-enyl-2-acylglycerol. Plasmenylcholine biosynthesis is also subjected to modulation by the 1,2-diacylglycerol content of the tissue.

Cellular transformation by a transmembrane peptide: structural requirements for the bovine papillomavirus E5 oncoprotein

The E5 oncoprotein of bovine papillomavirus, only 44 amino acids long, occurs as a disulfide-bonded transmembrane dimer. This remarkable oncoprotein stimulates signal transduction through activation of the platelet-derived growth factor (PDGF) receptor, and E5 exhibits limited amino acid sequence similarity with PDGF. Results presented here suggest that a key feature of the hydrophobic transmembrane domain is an amino acid side chain that participates in interhelical hydrogen bond formation. These data are reminiscent of the activated neu oncogene, in which a point mutation in the transmembrane domain leads to ligand-independent dimerization and activation of a receptor tyrosine kinase. Significantly, the transmembrane domain of E5 can be largely replaced by the transmembrane domain from the activated neu receptor tyrosine kinase. Extensive mutagenesis defines the minimal structural features required for transformation by the E5 oncoprotein as, first, the ability to dimerize and, second, presentation of a negatively charged residue at the extracellular side of the membrane. The biological activity of E5 mutants that lack most amino acid residues similar to PDGF suggests that E5 and PDGF activate the PDGF receptor by distinct mechanisms.

Effect of Pinellia ternata lectin on membrane currents of mouse motor nerve terminals

Pinellia ternata lectin (PTL) extracted from the fresh juice of rhizome of pinellia ternata used as a traditional Chinese medicine facilitated the quantal release of acetylcholine (ACh) in the mouse motor nerve terminals and formed cation channels in artificial lipid bilayer. Here we report the action of PTL on presynaptic membrane currents of motor nerve terminals. The experiments were performed on the intercostal nerve triangularis sterni muscle preparations. By means of the perineurial recording, the effects of PTL on the sodium current in the preterminal part, three potassium currents and two calcium currents generated from the nerve terminals were investigated. The results show that PTL increases voltage-dependent fast Ca2+ current (ICa.f), Na+ current (INa) and Ca(2+)-activated K+ current (IK,Ca) without action on either the voltage-dependent fast K+ current (IK,f) or the slow K+ current (IK,s). These effects are irreversible, but can be reversed by mannan, the specific binding sugar for PTL. The total action of PTL can be considered to raise [Ca2+]i by promoting Ca2+ influx, and then facilitate the neurotransmitter release. To our knowledge, this is the first report about the influence of lectin on presynaptic membrane currents at mammalian motor nerve terminals.

[Effect of nanhumycin on neuromuscular transmission and its mechanism]

Nanhumycin (NHM) is a new polyether antibiotic, which suppresses the growth Bacillus subtilis and shows an anticoccidial effect. By means of intracellular recording technique, the effects of NHM on mouse phrenic nerve-diaphragm preparations were observed. The main results are as follows: (1)20 micrograms/ml NHM irreversibly blocked neuromuscular transmission in 1.5-2.0 h. (2) 2-20 micrograms/ml NHM evoked a drastic and spasmodic increase of the frequency of miniature endplate potentials (MEPPs) and a simultaneous increase of the mean quantal content of endplate potentials for 40-60 min, which was followed by complete blockage of EPPs. (3) NHM decreased the resting potential (RP) of muscle cells progressively and irreversibly. (4) NHM's effects on RP or MEPP disappeared in Na(+)-free physiological solution but persisted in the presence of tetrodotoxin (TTX). All these results support the notion that NHM is a cation ionophore, Na+ carrier.

The v-sis protein retains biological activity as a type II membrane protein when anchored by various signal-anchor domains, including the hydrophobic domain of the bovine papilloma virus E5 oncoprotein

Membrane-anchored forms of the v-sis oncoprotein have been previously described which are oriented as type I transmembrane proteins and which efficiently induce autocrine transformation. Several examples of naturally occurring membrane-anchored growth factors have been identified, but all exhibit a type I orientation. In this work, we wished to construct and characterize membrane-anchored growth factors with a type II orientation. These experiments were designed to determine whether type II membrane-anchored growth factors would in fact exhibit biological activity. Additionally, we wished to determine whether the hydrophobic domain of the E5 oncoprotein of bovine papilloma virus (BPV) can function as a signal-anchor domain to direct type II membrane insertion. Type II derivatives of the v-sis oncoprotein were constructed, with the NH2 terminus intracellular and the COOH terminus extracellular, by substituting the NH2 terminal signal sequence with the signal-anchor domain of a known type II membrane protein. The signal-anchor domains of neuraminidase (NA), asialoglycoprotein receptor (ASGPR) and transferrin receptor (TR) all yielded biologically active type II derivatives of the v-sis oncoprotein. Although transforming all of the type II signal/anchor-sis proteins exhibited a very short half-life. The short half-life exhibited by the signal/anchor-sis constructs suggests that, in some cases, cellular transformation may result from the synthesis of growth factors so labile that they activate undetectable autocrine loops. The E5 oncoprotein encoded by BPV exhibits amino acid sequence similarity with PDGF, activates the PDGF beta-receptor, and thus resembles a miniature membrane-anchored growth factor with a putative type II orientation. The hydrophobic domain of the E5 oncoprotein, when substituted in place of the signal sequence of v-sis, was indistinguishable compared with the signal-anchor domains of NA, TR, and ASGPR, demonstrating its ability to function as a signal-anchor domain. NIH 3T3 cells transformed by the signal/anchor-sis constructs exhibited morphological reversion upon treatment with suramin, indicating a requirement for ligand/receptor interactions in a suramin-sensitive compartment, most likely the cell surface. In contrast, NIH 3T3 cells transformed by the E5 oncoprotein did not exhibit morphological reversion in response to suramin.

[Facilitatory effect of Pinellia ternata lectin on quantal release of acetylcholine from nerve terminals]

Pinellia ternata lectin (PTL) extracted from the rhizome of Pinellia ternata Briet by porcine thyroglobulin-Sepharose 4B column exhibits hemagglutination activity and carbohydrate binding specificity for mannan. Here we reported the effects of PTL on the resting membrane potential of muscle fiber and on the release of acetylcholine (ACh) from the motor nerve terminals in the phrenic nerve diaphragm preparations of mice. The results showed that PTL increased the frequency of miniature end-plate potential (MEPP). In 30 min after the treatment of the preparation with lectin 100 micrograms.ml-1, the frequency of MEPP reached 20 times higher than that of the control. Addition of mannan 1 mg.ml-1 restored the raised discharge of MEPP to its control level immediately. Similar to the effect of PTL on MEPP frequency, the amplitude and mean quantal content of end-plate potential also increased after PTL. At 100 micrograms.ml-1, the lectin depolarized the muscle membrane slightly, while at 10 micrograms.ml-1 no effect on the membrane potential was found. These results were interpreted as the intracellular Ca2+ elevation due to a permeability increase of the nerve terminal to ions after PTL.

[Effects of aureofuscin on muscle cell membrane and quantal release of acetylcholine (ACh) from the motor nerve terminals]

By means of the intracellular recording technique, the effect of aureofuscin (20 micrograms/ml, oversaturation solution) on the ACh release from motor nerve terminals and on muscle cell membrane potential were investigated in phrenic nerve diaphragm preparations of the mice. The results showed that (a) aureofuscin reduced the resting membrane potential of the muscle cell slightly; (b) the frequency of miniature end-plate potentials and the mean quantal content of end-plate potentials increased at first and then recovered approximately to the control level; (c) the depolarization produced by aureofuscin in the muscle cell membrane was reversible and the aureofuscin-invoked facilitation in miniature end-plate potential discharges was Ca(2+)-dependent; and (d) aureofuscin did not block neuromuscular transmission.

[Histamine and early ischemic arrhythmia in anesthetized cats]

Ligation of left anterior descending coronary artery caused various arrhythmias and reduced histamine content in ischemic myocardium in anesthetized cats. Intracoronary injection of compound 48-80 100 micrograms shortened the onset of VT and VF from 13 +/- 5, 18 +/- 5 min (n = 7) in control to 7.2 +/- 1.1 (P less than 0.01), 11 +/- 5 min (P less than 0.05) (n = 6) respectively, elevated the histamine concentration of plasma after acute coronary artery occlusion (15 +/- 3, 26 +/- 10 ng/ml, P less than 0.05, before and after ligation respectively). Iv chlorpheniramine (5, 10 mg/kg) or cimetidine (20, 40 mg/kg) dose-dependently reduced arrhythmia score, incidence of VF and mortality after myocardial ischemia, but with little influence on histamine content in ischemic myocardium and plasma. These results suggest that release of histamine from the ischemic myocardium is involved in the generation of early arrhythmias through H1 and H2 receptors in anesthetized cats subjected to acute coronary artery occlusion.

Physiological consequences of the complete loss of phosphoryl-transfer proteins HPr and FPr of the phosphoenolpyruvate:sugar phosphotransferase system and analysis of fructose (fru) operon expression in Salmonella typhimurium

Mutants of Salmonella typhimurium defective in the proteins of the fructose operon [fruB(MH)KA], the fructose repressor (fruR), the energy-coupling enzymes of the phosphoenolpyruvate:sugar phosphotransferase system (PTS) (ptsH and ptsI), and the proteins of cyclic AMP action (cya and crp) were analyzed for their effects on cellular physiological processes and expression of the fructose operon. The fru operon consists of three structural genes: fruB(MH), which encodes the enzyme IIIFru-modulator-FPr tridomain fusion protein of the PTS; fruK, which encodes fructose-1-phosphate kinase; and fruA, which encodes enzyme IIFru of the PTS. Among the mutants analyzed were Tn10 insertion mutants and lacZ transcriptional fusion mutants. It was found that whereas a fruR::Tn10 insertion mutant, several fruB(MH)::Mu dJ and fruK::Mu dJ fusion mutants, and several ptsHI deletion mutants expressed the fru operon and beta-galactosidase at high constitutive levels, ptsH point mutants and fruA::Mu dJ fusion mutants retained inducibility. Inclusion of the wild-type fru operon in trans did not restore fructose-inducible beta-galactosidase expression in the fru::Mu dJ fusion mutants. cya and crp mutants exhibited reduced basal activities of all fru regulon enzymes, but inducibility was not impaired. Surprisingly, fruB::Mu dJ crp or cya double mutants showed over 10-fold inducibility of the depressed beta-galactosidase activity upon addition of fructose, even though this activity in the fruB::Mu dJ fusion mutants that contained the wild-type cya and crp alleles was only slightly inducible. By contrast, beta-galactosidase activity in a fruK::Mu dJ fusion mutant, which was similarly depressed by introduction of a crp or cya mutation, remained constitutive. Other experiments indicated that sugar uptake via the PTS can utilize either FPr-P or HPr-P as the phosphoryl donor, but that FPr is preferred for fructose uptake whereas HPr is preferred for uptake of the other sugars. Double mutants lacking both proteins were negative for the utilization of all sugar substrates of the PTS, were negative for the utilization of several gluconeogenic carbon sources, exhibited greatly reduced adenylate cyclase activity, and were largely nonmotile. These phenotypic properties are more extreme than those observed for tight ptsH and ptsI mutants, including mutants deleted for these genes. A biochemical explanation for this fact is proposed.

Immunoreactive apolipoprotein E is a widely distributed cellular protein. Immunohistochemical localization of apolipoprotein E in baboon tissues

Apolipoprotein (apo)E is an important protein determinant in cholesterol homeostasis in man. The protein is synthesized by the liver as well as by a number of extrahepatic tissues. In the present study, immunohistochemical techniques were used to identify apoE in specific cells in various baboon organs. In the 11 tissues studied, the following cell types have been found to harbor apoE immunoreactivity: cerebral astrocytes; thyroid follicular cells; alveolar type II pneumocytes; hepatocytes, and Kupffer cells; adrenocortical cells in zona fasciculata and zona reticularis; adrenal medullary cells; some renal tubular epithelia; some pancreatic islet cells; histiocytic macrophages in lymph nodes and the spleen; some gastric mucosal epithelia; and ovarian oocytes. These observations indicate the wide distribution of apoE in many organs and suggest that the protein might perform other important functions such as regulation of local hormonal homeostasis in addition to its role in cholesterol metabolism.

Production and characterization of polyclonal and monoclonal antibodies to rat brain L-glutamate decarboxylase

Specific monoclonal and polyclonal antibodies to rat brain glutamate decarboxylase (GAD) were produced and characterized. Polyclonal antibodies against GAD were raised in rabbits by injecting a total of 70-210 micrograms of purified GAD i.m. The specificity of anti-GAD serum was established from a variety of tests including Ouchterlony immunodiffusion, immunoelectrophoresis, immunoprecipitation, dot immunoassay, ELISA tests and Western immunoblottings. In immunodiffusion and immunoelectrophoresis tests using partially purified GAD preparations and anti-GAD serum a single, sharp precipitin line corresponding to GAD activity was obtained. Quantitative immunoprecipitation of GAD activity was achieved using anti-GAD IgG and Staphylococcus aureus. Specificity of the antiserum was further indicated from a dot immunoassay and ELISA tests in which the intensity of the reaction product was proportional to the amount of GAD protein present. In the Western immunoblotting experiments using partially purified GAD preparations only two protein bands corresponding to the position of the two subunits of GAD were stained by anti-GAD IgG, further supporting the specificity of polyclonal antibodies against GAD. In addition to polyclonal antibodies, several specific GAD-antibodies-producing clones were also obtained by the hybridoma technique. The specificity of monoclonal antibodies against GAD were established from the following criteria: positive on ELISA test using homogeneous GAD as antigen; formation of GAD--anti-GAD IgG complex as indicated from gel filtration chromatography and sodium dodecyl sulfate polyacrylamide gel electrophoresis; and specific recognition of GAD subunit in a partially purified GAD preparation in Western immunoblotting test. Monoclonal antibodies were further characterized by immunohistochemical localization of known GABAergic neurons and their processes in the cerebellum and retina.