[Validation of a hyperkalemia prediction model in chronic kidney disease].

Objective: To validate the accuracy and consistency of a previously established prediction model for the occurrence of hyperkalemia in non-dialytic chronic kidney disease (CKD) patients. Methods: All patients diagnosed with CKD from Outpatient Department of Shanghai Changzheng Hospital during the 4th quarter of 2020 were recruited. Demographic data, clinical characteristics and prediction model-related parameters of the patients were collected and analyzed. Receiver operating characteristic (ROC) curve was drawn to evaluate the effectiveness of the model, and the specificity and sensitivity were calculated based on the cut-off value of 4 obtained from the previous model. The improved Hanley method was used to compare the area under the curve (AUC) between the previously established model and current validation dataset. The calibration curve was drawn to verify the model calibration degree. Results: A total of 434 patients diagnosed with non-dialytic CKD were enrolled, among whom 233 were males and 201 were females, with an average age of (55±16) years. According to the measured serum potassium values, the prevalence of hyperkalemia was 7.6%. And 33 patients were allocated to the hyperkalemia group and 401 patients were to the normal potassium group. There was no significant difference in age and sex between the two groups (both P>0.05). A combination of hyperkalemia and heart failure (27.3% vs 3.7%, P<0.001), diabetes (42.4% vs 19.7%, P=0.002), and acidosis (51.5% vs 7.0%, P<0.001) were more frequently in the hyperkalemia group, compared with the normal serum potassium group. Patients in the hyperkalemia group were more likely to have a past history of serum potassium ≥5.0 mmol/L (48.5% vs 2.5%, P<0.001). For the drugs that could increase serum potassium levels, there was a significant correlation between Chinese herbal medicine and the occurrence of hyperkalemia, while renin-angiotensin-aldosterone system inhibitor (RAASi) and potassium supplementation showed no significant difference between the two groups. The results of ROC curve analysis showed that the AUC was 0.914, with the sensitivity of 84.8% and the specificity of 79.8% with the cut-off value of 4. The difference of AUC between the previously established risk assessment model of hyperkalemia in patients with non-dialytic CKD and current validation dataset was not statistically significant (Z=1.924, P=0.054), indicating the good accuracy and consistency of the prediction model. In the calibration curve, when the predicted risk of patients was below 0.4 or above 0.6, the prediction effect of the model was better. Conclusion: The previously-constructed hyperkalemia prediction model in non-dialytic CKD patients had good accuracy and consistency, and could be used to evaluate the risk of hyperkalemia in all stages of non-dialytic CKD patients.

[Incidence of unintended pregnancy within 2 years after delivery and its influencing factors in China].

Objective: To investigate the present situation of unintended pregnancy within two years postpartum and its influencing factors in China. Methods: Participants who delivered a live birth at 60 hospitals in 15 provinces in the eastern, central and western regions of China during July 2015 to June 2016 were interviewed by using structured questionnaire. Information on occurrence of unintended pregnancy within 2 years after delivery, postpartum contraceptive use, sexual resumption, breastfeeding, and women's socio-demographic characteristics, and so on, were collected. Life-table analysis, cluster log-rank tests and a 2-level Cox regression model were used for data analysis. Results: A total of 18 045 postpartum women were investigated. The cumulative 1- and 2-year unintended pregnancy rates after delivery were 5.3% (95%CI: 4.5%－6.1%) and 13.1% (95%CI: 11.3%－14.8%), respectively. Cox regression model analysis showed that the risk of unintended pregnancy within 2 years postpartum were increased in younger women, ethnic minorities, women with abortion history, and those who had a vaginal delivery with short lactation time and late postpartum contraceptive initiation (all P<0.01). The risk of postpartum unintended pregnancy was not associated with geographic regions and hospitals where women gave a birth (all P>0.05). Conclusions: In China, the risk of unintended pregnancy within 2 years after delivery is relatively high. Service institutions and service providers should improve the quality of postpartum family planning services, promote the use of high effect contraceptive methods, and educate women to use a method at the time of their sexual resumption or even before.

Arbuscular mycorrhizal fungi effect growth and photosynthesis of Phragmites australis (Cav.) Trin ex. Steudel under copper stress.

Arbuscular mycorrhizal fungi (AMF) is an effective way to remove heavy metals' inhibition on plants, however, few relevant research attempts have been made to determine the contribution of AMF to the physiological and biochemical changes related to the enhanced copper tolerance of Phragmites australis under metal-stressed conditions. In this study, the effects of AMF inoculation on P. australis under different concentrations of copper stress were investigated according to the changes in the parameters related to growth and development, and photosynthetic charateristics. Then, differentially expressed proteins (DEPs) were evaluated by the Isobaric Tag for Relative and Absolute Quantification (iTRAQ) system, which could accurately quantify the DEPs by measuring peak intensities of reporter ions in tandem mass spectrometry (MS/MS) spectra. It was found that AMF inoculation may relieve the photosynthesis inhibition caused by copper stress on P. australis and thus promote growth. Proteomic analysis results showed that under copper stress, the inoculation of R. irregularis resulted in a total of 459 differently-expressed proteins (200 up-regulated and 259 down-regulated) in root buds. In addition, the photosynthetic changes caused by AMF inoculation mainly involve the up-regulated expression of transmembrane protein-pigment complexes CP43 (photosystem II) and FNR (ferredoxin-NADP+ oxidoreductase related to photosynthetic electron transport). These results indicate that AMF could effectively improve the growth and physiological activity of P. australis under copper stress, and thus provides a new direction and instructive evidence for determining the mechanisms by which AMF inoculation enhances the copper tolerance of plants.

[Associations of parental thalassemia with preterm birth and low birth weight].

Objective: To investigate the association between the preterm birth and low birth weight and parental thalassemia. Methods: Pregnant women and their husbands receiving prenatal examination in local hospitals or maternal and child health centers in Jingxi and Debao in Guangxi from January to December 2017 were selected as study subjects. A total of 758 pregnant women with pregnancy outcomes and their husbands, who were both or alone diagnosed with thalassemia through thalassemia gene detection, were selected as case group and 758 pregnant women with pregnancy outcomes and their husbands, who were negative in thalassemia gene detection and hemoglobin electrophoresis test were selected as control groups. The case group were further divided into mother group, father group and both mother and farther group. Clinical and pregnancy outcome data of the study subjects were collected for the analysis on the association between parental thalassaemia and preterm birth or low birth weight by the independent sample t test, χ(2) test and Cox regression analysis. Results: The incidence of preterm birth in case group and control group was about 6.5% and 1.6% and the incidence of low birth weight in case group and control group was about 7.3% and 0.8%. After adjusting for possible confounding factors, Cox regression analysis results showed that mother suffering from thalassemia (aRR=3.45, 95%CI: 1.35-8.81, P=0.010), fathers suffering from thalassemia (aRR=4.93, 95%CI: 2.16-11.21, P<0.001) and both mother and farther suffering from thalassemia (aRR=5.13, 95%CI: 2.62-10.04, P<0.001) were associated with preterm birth. Mother suffering from thalassemia (aRR=12.98, 95%CI: 4.91-34.30, P<0.001), fathers suffering from thalassemia (aRR=9.40, 95%CI: 3.40-25.95, P<0.001) and both mother and farther suffering from thalassemia (aRR=10.74, 95%CI: 4.44-26.00, P<0.001) were associated with low birth weight. The newborn whose parent all suffered from thalassemia had higher risks for preterm birth (χ(2)=22.72, P<0.001)and low birth weight (χ(2)=34.03, P<0.001) compared with those only with mother or father suffering from thalassemia. Conclusion: Parental thalassaemia, including both sides and single side, might increase the risks of preterm birth and low birth weight for newborn, and the risks might be higher in newborn with both mother and father suffering from thalassaemia.

[Construction of latent membrane protein 2A chimeric antigen receptor-T cells and their lethal effects on nasopharyngeal carcinoma cells].

Objective: To produce latent membrane protein 2A (LMP2A) chimeric antigen receptor (CAR)-T cells and detect the lethal effect of LMP2A CAR-T cells on nasopharyngeal carcinoma (NPC) cells. Methods: The study was conducted from September 2016 to December 2017.Genetic engineering technology was used to construct anti-LMP2A CAR lentiviral expression vector and sequencing was identified. The expression of anti-LMP2A CAR in the 293T cells was confirmed by western blot. CCK8 assay was used to evaluate the cytotoxicity of LMP2A CAR-T cells to NPC cells. ELISA assay was performed to test IL-2 and IFN-γ releasing of activated LMP2A CAR-T cells. The inhibition effect of LMP2A CAR-T cells on NPC xenograft tumor was observed in vivo. Statistical analysis was performed by statistical software SPSS 21.0. Results: The results of PCR and sequencing showed that anti-LMP2A CAR lentiviral expression vector was constructed successfully. The result of western blot indicated the expression of anti-LMP2A CAR in the 293T cells effectively. The results of CCK-8 assay showed that the killing activities of LMP2A CAR-T cells to LV-LMP2A-CNE1 cells were (72.11±9.75)%, (54.65 ±5.42)% and (36.68±3.80)% at 20∶1, 10∶1 and 5∶1 ratio of effective cells to target cells, and had a statistical difference compared to CD19 CAR-T cells and T cells (P<0.05). There was no significant difference in the killing activities of LMP2A CAR-T cells to CNE1 cells compared with CD19 CAR-T cells and T cells. The results of ELISA showed that the content of IL-2 and IFN-γ in the co-culture supernatant of LMP2A CAR-T cells and LV-LMP2A-CNE1 cells was significantly higher than that of LMP2A CAR-T cells and CNE1 cells which had statistical difference (P<0.05); In vivo experiment, the volume of LMP2A CAR-T cell group was (80.3±10.0) mm(3) which was significantly lower than that of the control groups, and the difference was statistically significant (P<0.05). Conclusion: LMP2A CAR-T cells are successfully prepared and have an obvious targeting cytotoxicity on LMP2A-positive NPC cells.

[Molecular epidemiologic study on Mycobacterium tuberculosis from drug resistance monitoring sites of Guangdong Province, 2015].

Objective: To understand the characteristics of Mycobacterium tuberculosis (MTB) in epidemiology and distribution from Guangdong Province, and to explore the risk factors associated with drug resistance. Methods: A total of 225 clinical strains of MTB collected from 5 drug resistance monitoring sites of Guangdong Province in 2015 were tested by Regions of Difference 105 (RD105) deletion test and 15 loci mycobacterial interspersed repetitive units (MIRU) were used for genotyping. Gene clustering was analyzed using BioNumerics7.6. Drug susceptibility test was tested by proportion method. The statistical analysis used chi-square test and multivariate logistic regression. Results: There were 158 (70.2%) Beijing family strains from the 225 cases. Hunter-gaston index of MIRU loci varied from each other. The MTBs from Guangdong Province were categorized into 2 gene clusters by clustering analysis in which the rate of cluster of complexⅠwas significantly higher than complexⅡ(χ(2) values were 9.331, P values were 0.020). It was found by multivariate logistic regression that Qub11b was associated with resistance to rifampicin and isoniazid (P values were 0.013, 0.012 respectively.), ETR F with resistance to isoniazid, streptomycin, ethambutol and ofloxacin (P values were 0.039, 0.040, 0.023 and 0.003 respectively), Mtub21 with resistance to capreomycin (P values were 0.040), and QUB26 with resistance to ethionamide (P values were 0.047). Conclusions: The genes of MTB from Guangdong Province were of polymorphisms and the distribution of strains were stable. QUB11b, ETR F, Mtub21 and QUB26 could be related to biomarkers for predicting drug resistance.

An instrument for measuring scintillators efficiently based on silicon photomultipliers.

An instrument used for measuring multiple scintillators' light output and energy resolution was developed. The instrument consisted of a light sensor array which was composed of 64 discrete SiPMs (Silicon Photomultipliers), a corresponding individual channel readout electronics system, and a data processing algorithm. A Teflon grid and a large interval between adjacent SiPMs were employed to eliminate the optical cross talk among scintillators. The scintillators' light output was obtained by comparing with a reference sample with known light output. Given the SiPM temperature dependency and the difference among each SiPM, a temperature offset correction algorithm and a non-uniformity correction algorithm were added to the instrument. A positioning algorithm, based on nine points, was designed to evaluate the performance of a scintillator array. Tests were performed to evaluate the instrument's performance. The uniformity of 64 channels for light output measurement was better than 98%, the stability was better than 98% when temperature varied from 15 °C to 40 °C, and the nonlinearity under 511 keV was better than 2%. This instrument was capable of selecting scintillators and evaluating the packaging technology of scintillator arrays with high efficiency and accuracy.

Oligomycins as inhibitors of K-Ras plasma membrane localisation.

Frequently present in pancreatic, colorectal and non-small cell lung carcinomas, oncogenic mutant K-Ras must be localised to the plasma membrane (PM) to be functional. Inhibitors of K-Ras PM localisation are therefore putative cancer chemotherapeutics. By screening a microbial extract library in a high content cell-based assay we detected the rare oligomycin class of Streptomyces polyketides as inhibitors of K-Ras PM localisation. Cultivation and fractionation of three unique oligomycin producing Streptomyces strains yielded oligomycins A-E (1-5) and 21-hydroxy-oligomycin A (6), together with the new 21-hydroxy-oligomycin C (7) and 40-hydroxy-oligomycin B (8). Structures for 1-8 were assigned by detailed spectroscopic analysis. Cancer cell viability screening confirmed 1-8 were cytotoxic to human colorectal carcinoma cells (IC50 > 3 µM), and were inhibitors of the ABC transporter efflux pump P-glycoprotein (P-gp), with 5 being comparable in potency to the positive control verapamil. Significantly, oligomycins 1-8 proved to be exceptionally potent inhibitors of K-Ras PM localisation (Emax 0.67-0.75 with an IC50 ~ 1.5-14 nM).

Association of MEF2A gene 3'UTR mutations with coronary artery disease.

Association of variants in the myocyte enhancer factor 2A (MEF2A) gene and the risk of coronary artery disease (CAD) has drawn much attention but remains controversial. We hypothesized that the 3'-untranslated region (3'-UTR) of this gene could harbor functionally relevant nucleotide changes. Here, we assessed the association between single nucleotide polymorphisms (SNPs) in the 3'-UTR of MEF2A and CAD in the Chinese Han population. A case-control study of 236 CAD patients and 278 controls was carried out. The four target SNPs were genotyped using a multiplex PCR-ligase detection reaction method. Logistic regression under three genetic models was used to analyze the association between target SNPs and the risk of CAD. Associations were detected between two SNPs (rs325380, rs897074) and CAD; however, after Bonferroni's correction, these associations were not deemed significant. A further haplotype study indicated that a 'TA' haplotype carrier of rs325380-rs325381 was associated with CAD risk. Our study thus indicates that variants in the 3'-UTR of MEF2A are associated with CAD in a Chinese Han population.

Synergistic effects of arsenic trioxide combined with ascorbic acid in human osteosarcoma MG-63 cells: a systems biology analysis.

OBJECTIVE: To further understand the synergistic mechanism of As2O3 and asscorbic acid (AA) in human osteosarcoma MG-63 cells by systems biology analysis. MATERIALS AND METHODS: Human osteosarcoma MG-63 cells were treated by As2O3 (1 µmol/L), AA (62.5 µmol/L) and combined drugs (1 µmol/L As2O3 plus 62.5 µmol/L AA). Dynamic morphological characteristics were recorded by Cell-IQ system, and growth rate was calculated. Illumina beadchip assay was used to analyze the differential expression genes in different groups. Synergic effects on differential expression genes (DEGs) were analyzed by mixture linear model and singular value decomposition model. KEGG pathway annotations and GO enrichment analysis were performed to figure out the pathways involved in the synergic effects. RESULTS: We captured 1987 differential expression genes in combined therapy MG-63 cells. FAT1 gene was significantly upregulated in all three groups, which is a promising drug target as an important tumor suppressor analogue; meanwhile, HIST1H2BD gene was markedly downregulated in the As2O3 monotherapy group and the combined therapy group, which was found to be upregulated in prostatic cancer. These two genes might play critical roles in synergetic effects of AA and As2O3, although the exact mechanism needs further investigation. KEGG pathway analysis showed many DEGs were related with tight junction, and GO analysis also indicated that DEGs in the combined therapy cells gathered in occluding junction, apical junction complex, cell junction, and tight junction. CONCLUSIONS: AA potentiates the efficacy of As2O3 in MG-63 cells. Systems biology analysis showed the synergic effect on the DEGs.

Establishment of an acute rejection model by transplanting both renal grafts into two different rats using a modified method of ureterovesical anastomosis.

OBJECTIVE: To establish an acute rejection model after kidney transplantation in the rat using a modified method of ureterovesical anastomosis. METHODS: Thirty-nine Wistar rat donors, were transplanted into 70 male SD rats. Wistar rats (group 1; n = 18) underwent harvest of both kidneys, cold perfusion, and transplantation into 36 SD rats. Wistar rats (group 2; n = 18) underwent left kidney harvest, cold perfusion and transplantation into 18 SD rats. Groups 1 and 2 did not receive immunosuppression after transplantation. Six kidneys were harvested from 3 Wistar rats (group 3), were transplanted into 6 SD rats that were treated with CsA (5 mg/kg per day) postoperatively, and humanely killed at 21 days. There were 10 SD in sham operated rats (group 4). The renal allograft vein was end-to-end anastomosed to the recipient renal vein using an epidural catheter. The renal allograft was anastomosed end-to-side to the recipient abdominal aorta with an abdominal aortic flap. The renal allograft ureterovesical flap was directly inserted into the recipient bladder, and attached by 4-5 interrupted sutures. The recipient's right kidney vessels were ligated at 3 days postoperatively. RESULTS: The success rates were 91.7% and 88.9% in groups 1 and 2, respectively. Except for the time for removal of the renal allografts, the operative durations and warm ischemia times differed insignificantly between both groups (P > .05). Blood creatinine levels increased significantly after kidney transplantation in groups 1 and 2 compared with the sham operated and CsA-treated cohorts (P < .01), but insignificantly between groups 1 and 2 (P > .05). CONCLUSIONS: A dual renal allograft model was established in the rat using a modified ureterovesical anastomosis. The technique can be reproduced reliably, reducing costs and shorten using overall operative duration.

Association study of human leucocyte antigen-A gene with idiopathic male infertility in Han population of China.

Human leucocyte antigen (HLA) is a complex gene family that contains several highly polymorphic genes. Some studies have reported HLA-A gene to have a strong role in idiopathic male infertility in Japanese and Yugoslavia populations. Prompted by these findings, we investigated the distributions of HLA-A gene to ascertain their associations with idiopathic male infertility in Chinese population. Polymerase chain reaction-sequence-based typing (PCR-SBT) method was used for DNA typing at HLA-A locus in 109 patients with idiopathic male infertility and 152 healthy controls in Han male population of Shaanxi Province, situated in north-western China. In total, we detected 23 HLA-A alleles in all infertile patients, 22 HLA-A alleles in control subjects. However, no significant differences of these allelic frequencies were found between the patients and the control subjects, suggesting that the HLA-A gene was unlikely a major risk factor of idiopathic male infertility in this sample population. As different populations have different HLA polymorphisms, investigation into the relationship of other HLA genes and idiopathic male infertility in our population is needed in the future.

Fortisterol, a novel steroid with an unusual seven-membered lactone ring B from the Chinese marine sponge Biemna fortis Topsent.

Fortisterol (1), a novel steroid with a rare seven-membered lactone ring B, has been isolated from the marine sponge Biemna fortis and its structure gas been elucidated on the basis of spectroscopic data.

Angiotensin II type 2 receptor-mediated apoptosis of cultured neurons from newborn rat brain.

Angiotensin II (Ang II) type 2 (AT2) receptors are highly expressed in neonate brain and may have a role in developmental processes such as apoptosis. Concurrent activation of c-Jun N-terminal kinase (JNK) and inhibition of Erk mitogen-activated protein kinase activities is important for apoptosis in many cells, and we previously demonstrated that stimulation of AT2 receptors causes decreased mitogen-activated protein kinase activity in neurons cultured from newborn rat hypothalamus and brain stem. Using such cultures we have employed terminal deoxynucleotidyl transferase-mediated deoxy-UTP nick end labeling and internucleosomal DNA fragmentation to assess the role of AT2 receptors in neuronal apoptosis. Ang II (100 nM; 4-72 h) alone produced no significant neuronal apoptosis, and AT2 receptor activation did not stimulate JNK activity. However, exposure of cultures to UV radiation (6 J/m2/sec for 4 sec) to stimulate JNK elicited neuronal apoptosis that was significantly enhanced by Ang II, an effect that was abolished by the AT2 receptor antagonist PD 123,319 (1 microM) or the serine/threonine phosphatase inhibitor okadaic acid (3 nM). Additionally, Ang II enhanced the UV radiation-induced decrease in the levels of the DNA repair enzyme poly-(ADP-ribose) polymerase. These data indicate that Ang II, via AT2 receptors and activation of a serine/threonine phosphatase, contributes to neuronal apoptosis.

Mutation detection by ligation to complete n-mer DNA arrays.

A new approach to comparative nucleic acid sequence analysis is described that uses the ligation of DNA targets to high-density arrays containing complete sets of covalently attached oligonucleotides of length eight and nine. The combination of enzymatic or chemical ligation with a directed comparative analysis avoids many of the intrinsic difficulties associated with hybridization-based de novo sequence reconstruction methods described previously. Double-stranded DNA targets were fragmented and labeled to produce quasirandom populations of 5' termini suitable for ligation and detection on the arrays. Kilobase-size DNA targets were used to demonstrate that complete n-mer arrays can correctly verify known sequences and can determine the presence of sequence differences relative to a reference. By use of 9-mer arrays, sequences of 1.2-kb targets were verified with >99.9% accuracy. Mutations in target sequences were detected by directly comparing the intensity pattern obtained for an unknown with that obtained for a known reference sequence. For targets of moderate length (1.2 kb), 100% of the mutations in the queried sequences were detected with 9-mer arrays. For higher complexity targets (2.5 and 16.6 kb), a relatively high percentage of mutations (90% and 66%, respectively) were correctly identified with a low false-positive rate of <0.03 percent. The methods described provide a general approach to analyzing nucleic acid samples on the basis of the interpretation of sequence-specific patterns of hybridization and ligation on complete n-mer oligonucleotide arrays.

Angiotensin II stimulates activation of Fos-regulating kinase and c-Jun NH2-terminal kinase in neuronal cultures from rat brain.

c-Fos/c-Jun dimers (activating protein-1 transcription factor) are involved in the modulatory actions of angiotensin II (Ang II) on brain norepinephrine neurons, effects mediated via Ang II type 1 (AT1) receptors. The transcriptional activities of c-Fos and c-Jun can be augmented by Fos-regulating kinase (FRK) and c-Jun NH2-terminal kinase (JNK), respectively. In this study, we investigated the effects of Ang II on FRK and JNK activities in neurons cultured from newborn rat hypothalamus and brain stem, which include a population of catecholaminergic cells containing AT1 receptors. Ang II caused time-dependent increases in the activation of FRK and JNK, effects completely inhibited by the AT1 receptor antagonist losartan but not by the Ang II type 2 (AT2) receptor blocker PD123,319. The stimulation of FRK activity by Ang II was abolished by the protein kinase C (PKC) inhibitor GF109203X or the calcium chelator BAPTA, but not by inhibition of calmodulin or calcium/calmodulin-dependent protein kinase II. However, the activation of JNK by Ang II was not dependent on PKC or another calcium-dependent mechanism. These data demonstrate that Ang II stimulates activation of FRK and JNK in neuronal cells, actions that may contribute to the neuromodulatory effects of this peptide.

Modulation of angiotensin II type 2 receptor mRNA in rat hypothalamus and brainstem neuronal cultures by growth factors.

This study investigates the regulatory effects of growth factors upon angiotensin II type 2 (AT2) mRNA levels in neurons co-cultured from newborn rat hypothalamus and brainstem. Incubation of cultured neurons with nerve growth factor (NGF; 5-50 ng/ml) caused time-dependent changes in the steady-state levels of AT2 receptor mRNA. Short-term (0.5-1.0 h) incubations with NGF resulted in significant increases in AT2 receptor mRNA, whereas longer-term incubations (4-24 h) caused significant decreases. Activation of NGF receptors is known to stimulate phospholipase C-gamma and subsequently activate protein kinase C (PKC). Incubation of cultures with the PKC activator, phorbol-12-myristate-13-acetate (PMA; 100 nM), caused temporal changes in AT2 receptor mRNA levels similar to those observed with NGF. By contrast, insulin (0.1-10 microg/ml) elicited only significant decreases in AT2 receptor mRNA levels. The observed abilities of NGF and insulin to regulate the expression of AT2 receptor mRNA are consistent with the fact that the AT2 receptor gene promoter region contains several cis DNA regulatory elements that respond to growth factor-stimulated transcription factors. These novel observations which show that NGF and insulin can regulate AT2 receptor mRNA in neurons derived from neonatal rat CNS lend support to the idea that AT2 receptors have a role in development and differentiation.

Accessing genetic information with high-density DNA arrays.

Rapid access to genetic information is central to the revolution taking place in molecular genetics. The simultaneous analysis of the entire human mitochondrial genome is described here. DNA arrays containing up to 135,000 probes complementary to the 16.6-kilobase human mitochondrial genome were generated by light-directed chemical synthesis. A two-color labeling scheme was developed that allows simultaneous comparison of a polymorphic target to a reference DNA or RNA. Complete hybridization patterns were revealed in a matter of minutes. Sequence polymorphisms were detected with single-base resolution and unprecedented efficiency. The methods described are generic and can be used to address a variety of questions in molecular genetics including gene expression, genetic linkage, and genetic variability.

Mitogen-activated protein kinases in rat brain neuronal cultures are activated by angiotensin II type 1 receptors and inhibited by angiotensin II type 2 receptors.

Neurons cultured from neonatal rat hypothalamus and brainstem contain many angiotensin II (Ang II) type 2 (AT2) receptors, and we previously determined that activation of these sites elicited a stimulation of serine/threonine phosphatase 2A (PP2A). Here, we have investigated the effects of Ang II on neuronal mitogen-activated protein (MAP) kinases, potential targets for PP2A. Using in-gel kinase assays and immunoprecipitation analyses we have shown that Ang II (10 nM-1 microM) elicits significant increases in p44(MAPK) (Erk1) and p42(MAPK) (Erk2) activities in cultured neurons, mediated via Ang II type 1 (AT1) receptors. This stimulatory effect of Ang II on Erk1 and Erk2 activities was potentiated by blockade of AT2 receptors with (S)-1-[4-(dimethylamino)-3-methylphenyl]methyl-5-(diphenylacetyl)- 4, 5,6,7-tetrahydro-1H-imidazo[4,5-C]pyridine-6-carboxylic acid (PD 123319, 1 microM). Furthermore, the AT2 receptor agonist N-alpha-nicotinoyl-Tyr-Lys-(N-alphaCBZ-Arg)-His-Pro-Ile-OH (CGP42112A) (10-50 nM) caused significant decreases in neuronal Erk1 and Erk2 activities, which were abolished by PD 123319 (1 microM) and by the PP2A inhibitor okadaic acid (3 nM). This indicates that AT1 and AT2 receptors have opposite actions on Erk1 and Erk2 activities in neonatal neurons. Since MAP kinases are involved in the regulation of growth/differentiation and apoptosis, our data may provide an intracellular basis for modulatory effects of Ang II receptors on these processes.

Angiotensin II stimulates protein phosphatase 2A activity in cultured neuronal cells via type 2 receptors in a pertussis toxin sensitive fashion.

Recent studies have suggested a role for an inhibitory G protein (Gi) and protein phosphatase 2A (PP2A) in the angiotensin II (Ang II) type 2 (AT2) receptor mediated stimulation of neuronal K+ currents. In the present study we have directly analyzed the effects of Ang II on PP2A activity in neurons cultured from newborn rat hypothalamus and brainstem. Ang II elicited time (30 min-24 h)- and concentration (10 nM -1 microM)-dependent increases in PP2A activity in these cells. This effect of Ang II involved AT2 receptors, since it was inhibited by the AT2 receptor selective ligand PD123319 (1 microM), but not by the Ang II type 1 receptor antagonist losartan (1 microM). Furthermore, the stimulatory effects of Ang II on PP2A activity were inhibited by pretreatment of cultures with pertussis toxin (PTX) (200 ng/ml; 24 h) indicating the involvement of an inhibitory G-protein; and by cycloheximide (CHX) (1 microgram/ml; 30 min) indicating a requirement for protein synthesis. These effects of Ang II appear to be via activation of PP2A, since Western Blot analyses revealed no effects of this peptide on the protein levels of the catalytic subunit of PP2A in cultured neurons. In summary, these data suggest that PP2A is a key component of the intracellular pathways coupled to neuronal AT2 receptors.