[Ventilator-associated pneumonia among premature infants <34 weeks' gestational age in neonatal intensive care unit in China: a multicenter study]

Objective: To investigate the incidence and pathogen distribution of ventilator-associated pneumonia (VAP) among preterm infants admitted to level Ⅲ neonatal intensive care units (NICU) in China. Method: A prospective study was conducted in 25 level Ⅲ NICU, enrolling all preterm infants <34 weeks gestational age admitted to the participating NICU within the first 7 days of life from May 2015 to April 2016. Chi-square test, t test and Mann-Whitney U test were used for statistical analysis. Result: A total of 7 918 patients were enrolled, within whom 4 623(58.4%) were males. The birth weight was (1 639±415) g and the gestational age was (31.4±2.0) weeks; 4 654(58.8%) infants required non-invasive mechanical ventilation and 2 154(27.2%) required intubation. Of all the mechanically ventilated patients, VAP occurred in 95 patients. The overall VAP rate was 7.0 episodes per 1 000 ventilator days, varying from 0 to 34.4 episodes per 1 000 ventilator days in different centers. The incidence of VAP was 9.6 and 6.0 per 1 000 ventilator days in children's hospitals and maternity-infant hospitals respectively, without significant differences (t=1.002, P=0.327). Gram-negative bacilli (76 strains, 91.6%) were the primary VAP microorganisms, mainly Acinetobacter baumannii (24 strains, 28.9%), Klebsiella pneumonia (23 strains, 27.7%), and Pseudomonas aeruginosa (10 strains, 12.0%). Conclusion: The incidence of VAP in China is similar to that in developed counties, with substantial variability in different NICU settings. More efforts are needed to monitor and evaluate the preventable factors associated with VAP and conduct interventions that could effectively reduce the occurrence of VAP.

Cardiotoxicity evaluation of nine alkaloids from Rhizoma Coptis

PURPOSE

Alkaloids derived from Rhizoma Coptis (RC) has been widely applied to clinical treatments in China. However, the toxicity of RC and the alkaloids from RC remained controversial. The research is designed to clarify the cardiotoxic compounds found in RC.

METHODS

In this study, the real-time cellular analysis cardio system and the high-content analysis were applied to monitor the function of cardiomyocytes (CMs) in the treatment of nine alkaloids in RC. Luciferase-coupled adenosine triphosphate (ATP) assay was used to detect cell viability.

RESULTS

The results showed that berberine, palmatine, berbamine, and oxyberberine were cardiotoxic, which resulted in arrhythmia and cardiac arrest on CMs in a time- and dose-dependent manner. Meanwhile, berbamine and oxyberberine caused shrinkage and detachment on CMs at 10 μM. Cytotoxicity was induced by these two compounds with decline in cell index and ATP depletion. Cardiotoxicity or cytotoxicity was not observed in the other five alkaloids within 10 μM.

CONCLUSION

For the first time, the cardiotoxicity of the nine alkaloids was evaluated to clarify the cardiotoxic components in RC. Furthermore, the experimental evidences were provided to support the safety of drug application.

[Clinical features of malignant tumor liver infiltration with liver failure as initial clinical manifestation: a single-center retrospective analysis of 9 cases]

Objective: To investigate the clinical features of patients with liver failure caused by tumor diffuse liver infiltration. Methods: A retrospective analysis was performed for the clinical data of 1008 patients with liver failure who were admitted to our hospital from July 2009 to December 2015. Among these patients, 9 had acute liver failure caused by liver metastasis of malignant tumor. Their clinical manifestations, laboratory markers, clinical progress, and outcome were observed, and the clinical features were summarized. Results: Such patients were manifested as liver enlargement and rapid clinical progression, and imaging examination showed stenosis due to external compression in the inferior vena cava. The patients might be easily misdiagnosed with Budd-Chiari syndrome and had a poor prognosis, with a mortality rate as high as 100%. Conclusion: As for the liver failure patients with unexplained liver enlargement, the possibility of liver metastasis of malignant tumors should be considered. Liver biopsy should be performed as early as possible before the deterioration of liver function, in order to facilitate the targeted therapy for the primary tumor.

[Effects of desmopressin acetate and pituitrin on proliferation, contraction, and secretion of hepatic stellate cells]

Objective: To investigate the effects of desmopressin acetate and pituitrin on the proliferation, contraction, and secretion of hepatic stellate cells (HSCs). Methods: The human HSC cell line LX-2 was selected as the research model. And three groups were designed: blank control group, desmopressin acetate group (three subgroups: 1×10^-10mol/L, 1×10^-9mol/L, and 1×10^-8mol/L desmopressin acetate), and pituitrin group (three subgroups: 0.1 U/L, 1.0 U/L, and 10.0 U/L pituitrin). Water-soluble tetrazolium salt (WST)-1 assay was used to evaluate cell proliferation; collagen gel contraction assay was used to assess cell contraction; enzyme-linked immunosorbent assay (ELISA) was used to identify cell secretion. The data was subjected to one-way analysis of variance. Results: (1) The results of WST-1 assay showed that the values of A₄₅₀in three desmopressin acetate subgroups (1×10^-10mol/L, 1×10^-9mol/L, and 1×10^-8mol/L) were 0.459±0.017, 0.467±0.024, and 0.436±0.015, respectively. And the values of A450 in three pituitrin subgroups (0.1 U/L, 1.0 U/L, and 10.0 U/L) were 0.495±0.011, 0.507±0.015, and 0.501±0.009, respectively. Compared with the control group, the desmopressin acetate at high concentration significantly inhibited the cell proliferation (P< 0.05), but the pituitrin at three different concentrations significantly promoted the cell proliferation (P< 0.05). (2) The collagen gel area ratios in three desmopressin acetate subgroups (1×10^-10mol/L, 1×10^-9mol/L, and 1×10^-8mol/L) were 77.07±4.42, 75.85±3.70, and 72.74±3.92, respectively. And the collagen gel area ratios in three pituitrin subgroups (0.1 U/L, 1.0 U/L, and 10.0 U/L) were 57.83±3.96, 50.28±6.69, and 43.56±7.68, respectively. Compared with the control group, the pituitrin at three different concentrations significantly reduced the collagen gel area (P< 0.01). (3) The matrix metalloproteinase(MMP)-2 concentrations in three desmopressin acetate subgroups (1×10^-10mol/L, 1×10^-9mol/L, and 1×10^-8mol/L) were 13.321±0.098, 12.230±0.153, and 12.061±0.126, respectively. And the MMP-2 concentrations in three pituitrin subgroups (0.1 U/L, 1.0 U/L, and 10.0 U/L) were 12.899±0.150, 13.662±0.152, and 13.698±0.119, respectively. Compared with the control group, the desmopressin acetate at low concentration significantly increased the secretion of MMP-2 (P< 0.01); the desmopressin acetate at high concentration significantly decreased the MMP-2 concentration (P< 0.05); the pituitrin at three different concentrations significantly increased the MMP-2 concentration (P< 0.01). The transforming growth factor-beta 1 (TGF-β1) concentrations in three desmopressin acetate subgroups (1×10^-10mol/L, 1×10^-9mol/L, and 1×10^-8mol/L) were 5.233±0.102, 17.749±0.188, and 36.060±0.227, respectively. And the TGF-β1 concentrations in three pituitrin subgroups (0.1 U/L, 1.0 U/L, and 10.0 U/L) were 15.615±0.099, 38.460±0.209, and 49.053±0.115, respectively. Compared with the control group, desmopressin acetate and pituitrin significantly promoted the secretion of TGF-β1 in a concentration-dependent manner (P< 0.01) and pituitrin had a stronger effect than desmopressin acetate (P< 0.01). Desmopressin acetate and pituitrin had no effect on the secretion of the collagenase type I and III (P> 0.05). Conclusion: Desmopressin acetate and pituitrin can induce the changes in the function and morphology of HSCs and may increase vascular resistance in the hepatic sinus. However, desmopressin acetate has less influence on HSCs than pituitrin.

Effects of different anesthetic approaches on postoperative complications in HIV-infected patients

The aim of this study was to investigate the effects of three different methods of anesthesia on patients with human immunodeficiency virus (HIV) infection, which could lead to an improvement in postoperative outcomes in these patients. A total of 90 patients undergoing an operation while being treated for an HIV infection were included in this study. Patients were divided into three groups (N = 30/group) based on the type of anesthesia administered: general anesthesia, local anesthesia, and combined spinal epidural anesthesia (CSEA). The effects of local infiltration of anesthesia and peripheral nerve block local anesthesia were examined in the local anesthesia group. The CSEA group examined the effects of spinal anesthesia in HIV-infected patients. We compared the vital signs of the three groups during the preoperative period, at incision, and during the postoperative recovery period. The CSEA group had a significantly higher mean preoperative CD4(+) T lymphocyte count compared with the general anesthesia and local anesthesia groups (P < 0.05). We found that the three kinds of anesthesia methods administered to HIV-infected patients could be used with considerable safety and can be selected according to the clinical need and type of surgical procedure.

High color rending index and high-efficiency white organic light-emitting diodes based on the control of red phosphorescent dye-doped hole transport layer

We have investigated the transport characteristics of red phosphorescent dye bis(1-(phenyl)isoquinoline) iridium (III) acetylanetonate (Ir(piq)₂acac) doped 4,4',4"-tri(N-carbazolyl)triphenylamine (TCTA), and found that the increasing doping ratio was facilitated to improve the ability of hole transporting. A high color rendering index (CRI) and high-efficiency WOLED was achieved by employing Ir(piq)₂acac doped TCTA film as an effective red emissive layer due to the generation of charge transfer complex (CTC) at the interface. The relative proportion in red: green: blue emission intensity can be controlled by the CTC concentration to obtain high CRI WOLEDs. The WOLED with an optimal red dye doping concentration of 5 wt% exhibits a high CRI of 89 and a power efficiency of 31.2 lm/W and 27.5 lm/W at the initial luminance and 100 cd/m², respectively. The devices show little variation of the Commission Internationale de I'Eclairage coordinates in a wide range of luminance.

Lifetime prevalence of suicide ideation, plan, and attempt in metropolitan China

OBJECTIVE

This is the first community-based epidemiological study examining the prevalence of suicidal behaviors, their transitional pathways, and their relationship with mental disorders in metropolitan China.

METHOD

Suicidal behaviors, including ideation, plans, and attempts were assessed by face-to-face household interviews among 5201 respondents in Beijing and Shanghai in 2001-2002. Lifetime prevalence and risk factors were examined using multivariate discrete-time survival models.

RESULTS

The lifetime prevalence estimates of suicidal ideation, plans, and attempts were 3.1%, 0.9%, and 1.0% respectively. Among suicide ideators, the conditional probability of ever making a plan and an attempt was 29.5% and 32.3% respectively. Progression from ideation to plan and attempt was the highest during the first year after onset. Suicide attempt was predicted by young adulthood, being unmarried, recent onset of ideation and plan, and the presence of mental disorders, especially mood disorder.

CONCLUSION

Suicidal behaviors in metropolitan China exhibit a low prevalence and an epidemiological profile resembling that found in Western countries.

Delay in initial treatment contact after first onset of mental disorders in metropolitan China

OBJECTIVE

There has been no community-based research on treatment delay among people with mental disorders in China. This study examines lifetime treatment and treatment delay in metropolitan China.

METHOD

A multi-stage probability survey of 5201 respondents was administered in Beijing and Shanghai. Age of first treatment contact after onset of each of the three lifetime DSM-IV/CIDI disorder classes was compared with retrospective information on age of disorder onset. Length and predictors of treatment delay were examined using survival analysis.

RESULTS

Survival curves estimate that 44.7%, 25.7%, and 7.9% of people with anxiety, substance, and mood disorders, respectively, will ever make treatment contact. Delays in first treatment contact of anxiety (21 years) and substance (17 years) disorders are longer than that of mood disorders (1 year). These delays are largely unrelated to sociodemographic variables.

CONCLUSION

Failure to receive treatment is a pervasive phenomenon among people with mental disorders in metropolitan China.

A new ultrasound instrument for in vivo microimaging of mice

We report here on the design and evaluation of the first high-frequency ultrasound (US) imaging system specifically designed for microimaging of the mouse. High-frequency US or US biomicroscopy (UBM) has the advantage of low cost, rapid imaging speed, portability and high resolution. In combination with the ability to provide functional information on blood flow, UBM provides a powerful method for the investigation of development and disease models. The new UBM imaging system is demonstrated for mouse development from day 5.5 of embryogenesis through to the adult mouse. At a frequency of 40 MHz, the resolution voxel of the new mouse scanner measures 57 microm x 57 microm x 40 microm. Duplex Doppler provides blood velocity sensitivity to the mm per s range, consistent with flow in the microcirculation, and can readily detect blood flow in the embryonic mouse heart, aorta, liver and placenta. Noninvasive UBM assessment of development shows striking similarity to invasive atlases of mouse anatomy. The most detailed noninvasive in vivo images of mouse embryonic development achieved using any imaging method are presented.

[Repair and reconstruction of radial nerve injury]

OBJECTIVE

To investigate the reparative method and effect of radial nerve injury.

METHODS

From 1990 to 2000, 50 cases with radial nerve injuries were adopted in this study. Among them, there were 38 males and 12 females, aged from 5 to 65 years. For the 50 cases, there were 28 cases with complete nerve rupture, 3 cases with incomplete nerve rupture, 10 cases with compressive injury, 5 cases with contusion injury and 4 cases with defect and irreversible injury. All the patients were treated with radial nerve exploration in 1 hour to 6 months after injury. 31 cases were treated with nerve anastomosis, 10 cases with nerve lytic operation, 4 cases with tendon transfer and 5 cases with palliative treatment.

RESULTS

All the cases were followed up 3 months to 10 years. The curative effect was assessed according to Highest grade method. There were excellent and good results in 46 cases, moderate results in 4 cases.

CONCLUSION

It is necessary to explore and repair the radial nerve injury immediately after the diagnosis being confirmed. If the function of radial nerve could not recover in 6 months, tendon transfer should be carried out to reconstruct the extension of elbow, thumb and fingers.

Antibody-based resistance to plant pathogens

Plant diseases are a major threat to the world food supply, as up to 15% of production is lost to pathogens. In the past, disease control and the generation of resistant plant lines protected against viral, bacterial or fungal pathogens, was achieved using conventional breeding based on crossings, mutant screenings and backcrossing. Many approaches in this field have failed or the resistance obtained has been rapidly broken by the pathogens. Recent advances in molecular biotechnology have made it possible to obtain and to modify genes that are useful for generating disease resistant crops. Several strategies, including expression of pathogen-derived sequences or anti-pathogenic agents, have been developed to engineer improved pathogen resistance in transgenic plants. Antibody-based resistance is a novel strategy for generating transgenic plants resistant to pathogens. Decades ago it was shown that polyclonal and monoclonal antibodies can neutralize viruses, bacteria and selected fungi. This approach has been improved recently by the development of recombinant antibodies (rAbs). Crop resistance can be engineered by the expression of pathogen-specific antibodies, antibody fragments or antibody fusion proteins. The advantages of this approach are that rAbs can be engineered against almost any target molecule, and it has been demonstrated that expression of functional pathogen-specific rAbs in plants confers effective pathogen protection. The efficacy of antibody-based resistance was first shown for plant viruses and its application to other plant pathogens is becoming more established. However, successful use of antibodies to generate plant pathogen resistance relies on appropriate target selection, careful antibody design, efficient antibody expression, stability and targeting to appropriate cellular compartments.

A minimal cytoplasmic subdomain of the erythropoietin receptor mediates p70 S6 kinase phosphorylation

Erythropoietin (EPO) is a lineage-restricted growth factor that is required for erythroid proliferation and differentiation. EPO stimulates the phosphorylation and activation of p70 S6 kinase (p70 S6K), which is required for cell cycle progression. Here, the minimal cytoplasmic domains of the EPO receptor (EPO-R) required for p70 S6K activation were determined.Ba/F3 cells were stably transfected with wild-type (WT) EPO-R or EPO-R carboxyl-terminal deletion mutants, designated by the number of amino acids deleted from the cytoplasmic tail (-99, -131, -221). Transfected cells were growth factor deprived and then stimulated with EPO. p70 S6K, JAK2, IRS-2, and ERK1/2 phosphorylation/activation were examined. The ability of transfected 3-phosphoinositide-dependent protein kinase 1 (PDK1) to reconstitute p70 S6K phosphorylation in EPO-R mutants also was determined. Phosphorylation and activation of p70 S6K, JAK2, IRS-2, and ERK1/2 in Ba/F3 cells transfected with EPO-R-99 or EPO-R-99Y343F were similar to WT EPO-R. In contrast, EPO-dependent p70 S6K phosphorylation/activation, as well as IRS-2 and ERK1/2 phosphorylation, were minimal or absent in cells transfected with EPO-R-131 or EPO-R-221. JAK2 phosphorylation was reduced significantly in cells transfected with EPO-R-131 and abolished with EPO-R-221. To examine the role of PDK1, a kinase known to phosphorylate p70 S6K, Ba/F3 EPO-R-131 cells were transiently transfected with PDK1. WT constitutively active PDK1 restored p70 S6K phosphorylation in Ba/F3 EPO-R-131 cells but not in Ba/F3 EPO-R-221 cells. The results demonstrate that a minimal cytoplasmic subdomain of the EPO-R extending between -99 and -131 is required for p70 S6K phosphorylation and activation. The results also demonstrate that PDK1 is a critical component in this signaling pathway, which requires the presence of domains between -131 and -221 for its activation of p70 S6K.

Recombinant single chain cardiac troponin I-C polypeptides: superior calibration and control materials for cardiac troponin I immunoassays

There has been a need to create stable and reproducible calibration and control materials for cardiac troponin I assays. Free troponin I, native or recombinant, has been known to be unstable, while troponin CI complex can be easily dissociated in low concentrations or in the presence of chelating agents. In order to overcome these difficulties, two single chain troponin I-C polypeptides have been engineered and expressed separately in Escherichia coli. One consists of a full-length of human cardiac troponin I and C, termed as ScTnI-C and the other consists of a stable fragment (aa28-110) of human cardiac troponin I and a full-length troponin C, termed as ScTnI-C-2. Both ScTnI-C and ScTnI-C-2 were purified to homogeneity by affinity chromatography using anti-cTnI monoclonal antibodies. ScTnI-C and ScTnI-C-2 have apparent molecular weights of 45 kD and 30 kD by SDS-PAGE, respectively. Stability studies by Stratus showed that ScTn I-C and ScTnI-C-2 were stable for 4 months at 2-8 degrees C and at least one year at -20 degrees C. When incubated in human serum at 37 degrees C, ScTnI-C-2 was more resistant to proteolysis than ScTnI-C. ScTnI-C can be recognized by all commercial TnI immunoassays with excellent activity. ScTnI-C-2 can be recognized by all immunoassays that target the stable region of cardiac troponin I. Judging by their performances, ScTnI-C and ScTnI-C-2 are both superior materials to be used as calibrators and controls in clinical laboratories.

Renal expression of the sodium/phosphate cotransporter gene, Npt2, is not required for regulation of renal 1 alpha-hydroxylase by phosphate

Several reports have suggested that the regulation of renal 1,25-dihydroxyvitamin D [1,25-(OH)(2)D] synthesis by extracellular phosphate (Pi) is dependent on normal transepithelial Pi transport by the renal tubule. Mice homozygous for the disrupted Na/Pi cotransporter gene Npt2 (Npt2(-/-)) exhibit renal Pi wasting, an approximately 85% decrease in renal brush border membrane Na/Pi cotransport, hypophosphatemia, and an increase in serum 1,25-(OH)(2)D concentration. We undertook 1) to determine the mechanism for the increased circulating levels of 1,25-(OH)(2)D in Npt2(-/-) mice and 2) to establish whether renal 1alpha-hydroxylase was appropriately regulated by dietary Pi in the absence of Npt2 gene expression. On a control diet, the 2.5-fold increase in the serum 1,25-(OH)(2)D concentration in Npt2(-/-) mice, relative to that in Npt2(+/+) littermates, is associated with a corresponding increase in renal mitochondrial 25-hydroxyvitamin D-1 alpha-hydroxylase (1 alpha-hydroxylase) activity and messenger RNA (mRNA) abundance. A low Pi diet elicits an increase in serum 1,25-(OH)(2)D concentration, renal 1alpha-hydroxylase activity, and mRNA abundance in Npt2(+/+) and Npt2(-/-) mice to similar levels in both mouse strains. A high Pi diet has no effect on serum 1,25-(OH)(2)D concentration, renal 1 alpha-hydroxylase activity, or mRNA abundance in Npt2(+/+) mice, but normalizes these parameters in Npt2(-/-) mice. In addition, renal 24-hydroxylase mRNA abundance is significantly reduced in Npt2(-/-) mice compared with that in Npt2(+/+) mice under all dietary conditions. In summary, we demonstrate that 1) increased renal synthesis of 1,25-(OH)(2)D is responsible for the increased serum 1,25-(OH)(2)D concentration in Npt2(-/-) mice; and 2) renal 1alpha-hydroxylase gene expression is appropriately regulated by dietary manipulation of serum Pi in both Npt2(+/+) and Npt2(-/-) mice. Thus, intact renal Na/Pi cotransport is not required for the regulation of renal 1alpha-hydroxylase by Pi.

GST fusion proteins cause false positives during selection of viral movement protein specific single chain antibodies

Glutathione S-transferase (GST) fusion proteins are used frequently for investigating protein-protein and protein-DNA interactions. The present study demonstrates that the use of GST fusion proteins caused false positives during selection of phage-displayed single-chain antibody fragments (scFvs) specific for three domains of the movement protein (NS(M)) of tomato spotted wilt virus (TSWV). To identify and exclude the false positives when using GST as a fusion partner linked to the antigen of interest, indirect phage enzyme-linked immunosorbent assay (ELISA) was compared with capture phage ELISA. Of 210 enriched phage clones, indirect phage ELISA identified 106 clones specific for binding to GST-domain fusions but not to GST. In contrast, using capture phage ELISA, all 106 selected clones were identified as false positives, reacting with the GST fusion proteins and GST. This was confirmed by characterization of soluble scFv antibodies. The data indicate that GST fusion proteins seem unsuitable for screening of phage-displayed antibody fragments and it is essential to use capture phage ELISA, instead of the indirect phage ELISA used commonly to exclude false positives in characterization of selected clones with GST fusion proteins.

The nuclear migration gene NudC and human hematopoiesis

The filamentous fungus Aspergillus nidulans nudC (nuclear distribution C) gene is required for movement of nuclei following mitosis and for normal colony growth. It is highly conserved, structurally and functionally, throughout most of evolution. The human homolog, called HnudC, has been cloned and has an important role in cell proliferation. In hematopoiesis, HNUDC is highly expressed in early hematopoietic precursors and declines during normal differentiation. Stimulation of proliferation of the erythroleukemia cell line TF-1 with GM-CSF enhances HnudC protein and mRNA expression and treatment with antisense (but not sense) oligonucleotides to HnudC mRNA significantly reduces cell division. A significant increase in HNUDC is present in bone marrow aspirates from patients with acute lymphoblastic leukemia (ALL) and acute myelogenous leukemia (AML) compared to the level in normal cellular counterparts, demonstrating dysregulated expression in leukemia. These data support the conclusion that HnudC plays a functional role in promoting hematopoietic cell growth and that it is involved in leukemogenesis.

Expression of angiotensin II type I receptor on erythroid progenitors of patients with post transplant erythrocytosis

BACKGROUND

The pathogenesis of posttransplant erythrocytosis (PTE) has been elusive. Angiotensin converting enzyme inhibitors (ACEI) are efficacious in lowering the hematocrit of patients with PTE and angiotensin II (AII) type I receptors (AT1R) were recently detected on red blood cell precursors, burst-forming unit-erythroid- (BFU-E) derived cells. The purpose of this study was to determine whether there is increased expression of the AT1R on BFU-E-derived cells of patients with PTE, which might contribute to the pathogenesis of PTE.

METHODS

Twelve healthy volunteers and 25 transplant recipients (13 patients with and 12 without PTE) were studied. BFU-E from peripheral blood were cultured in methylcellulose and BFU-E-derived colonies were harvested on day 10. Western blotting was used to detect AT1R and erythropoietin receptor (EpoR) expression. Intracellular free calcium in response to AII and erythropoietin (Epo) was measured with digital video imaging.

RESULTS

There were no differences between transplant patients, with and without PTE, with respect to weight, age, sex, blood pressure, serum creatinine, circulating renin, angiotensin II, and Epo levels. Hematocrit, red blood cell number, BFU-E-derived colony number,and size were significantly increased in PTE compared with other two groups. AT1R expression was increased by 44% on the erythroid progenitors of PTE versus non posttransplant erythrocytosis patients and by 32% in PTE patients versus normal volunteers. AT1R expression correlated significantly with the hematocrit in PTE (Spearman r=0.68, P=0.01). In contrast, EpoR expression was equivalent in all groups. The AT1R was functional since a significant increase in [Ca(i)] was observed in Fura-2 loaded day 10 cells when stimulated with AII (182%, P<0.0001).

CONCLUSION

An increase in AT1R density was observed in erythroid precursors of transplant patients with PTE compared to those without PTE and normal volunteers, and the level of AT1R expression in PTE correlated significantly with the hematocrit. In contrast, EpoR expression was not different in PTE compared with non posttransplant erythrocytosis or normal controls. This study supports a role for the AT1 receptor signaling pathway in the pathogenesis of PTE.

[Studies on the construction and expression of recombinant human fusion gene Nm23-H1/HbFGF in Escherichia coli]

First, a piece of intermediate nucleic acid chain was designed according to the nucleic acid sequences of Nm23-H1 and HbFGF cDNA, then it was combined with the upstream primer of Nm23-H1 or the downstream primer of HbFGF to perform Polymerase Chain Reaction (PCR) respectively. The fusion gene Nm23-H1/HbFGF was constructed by four steps of PCR, and it was cloned into the plasmid vector pBV220. The recombinant was induced at 42 degrees C and analyzed by SDS-PAGE. Results show that the fusion gene Nm23-H1/HbFGF highly expresses its product in inclusion body in E. coli BL21(DE3). The expressing product is 14% of the total bacterial protein and it is 34 kD. ELISA assay and Western blot indicate that the inclusion body contains antigens of Nm23-H1 and HbFGF. By denaturation, renaturation and purification, the inclusion body was purified. Determination and biological activity assay show that the purified product contains two kinds of antigens which have biological activities of Nm23-H1 and HbFGF. All these data establish good base to study the tumor suppressor activity and oncogenicity of the fusion gene Nm23-H1/HbFGF in eukaryocyte.

Inhibitory effects of 8-(N,N-diethylamino)-n-octyl-3,4,5-trimethoxybenzoate (TMB-8) on intracellular Ca2+ elevated by neurotransmitters in brain cells

AIM

To study the effects of TMB-8 on [Ca2+]i elevation induced by neurotransmitters in dissociated brain cells.

METHODS

The brain cell suspension was made using a gentle trituration for 1 min with a polished pipette. The changes of [Ca2+]i were detected by the fluorescent indicator, Fura 2-AM.

RESULTS

In the presence of extracellular Ca2+ 1.3 mmol.L-1, sodium glutamate (Glu), histamine (His), and serotonin (5-HT) markedly increased the [Ca2+]i which were reduced by TMB-8 30 mumol.L-1. TMB-8 3 mumol.L-1 produced inhibitory effects on the increase of [Ca2+]i by His and 5-HT in a Ca(2+)-free Hanks' solution. The increase of [Ca2+]i by His and 5-HT was reduced to control level by TMB-8 10 mumol.L-1.

CONCLUSION

TMB-8 inhibited the [Ca2+]i elevation induced by Glu, 5-HT, and His in brain cells.

Identification of the erythropoietin receptor domain required for calcium channel activation

Erythropoietin (Epo) activates a voltage-independent Ca2+ channel that is dependent on tyrosine phosphorylation. To identify the domain(s) of the Epo receptor (Epo-R) required for Epo-induced Ca2+ influx, Chinese hamster ovary (CHO) cells were transfected with wild-type or mutant Epo receptors subcloned into pTracer-cytomegalovirus vector. This vector contains an SV40 early promoter, which drives expression of the green fluorescent protein (GFP) gene, and a cytomegalovirus immediate-early promoter driving expression of the Epo-R. Successful transfection was verified in single cells by detection of GFP, and intracellular Ca2+ ([Ca]i) changes were simultaneously monitored with rhod-2. Transfection of CHO cells with pTracer encoding wild-type Epo-R, but not pTracer alone, resulted in an Epo-induced [Ca]i increase that was abolished in cells transfected with Epo-R F8 (all eight cytoplasmic tyrosines substituted). Transfection with carboxyl-terminal deletion mutants indicated that removal of the terminal four tyrosine phosphorylation sites, but not the tyrosine at position 479, abolished Epo-induced [Ca]i increase, suggesting that tyrosines at positions 443, 460, and/or 464 are important. In CHO cells transfected with mutant Epo-R in which phenylalanine was substituted for individual tyrosines, a significant increase in [Ca]i was observed with mutants Epo-R Y443F and Epo-R Y464F. The rise in [Ca]i was abolished in cells transfected with Epo-R Y460F. Results were confirmed with CHO cells transfected with plasmids expressing Epo-R mutants in which individual tyrosines were added back to Epo-R F8 and in stably transfected Ba/F3 cells. These results demonstrate a critical role for the Epo-R cytoplasmic tyrosine 460 in Epo-stimulated Ca2+ influx.

A homolog of the fungal nuclear migration gene nudC is involved in normal and malignant human hematopoiesis

The filamentous fungus Aspergillus nidulans nudC gene has an essential function in movement of nuclei following mitosis and is required for normal colony growth. Here, the molecular cloning and role in hematopoiesis of a human gene (designated HnudC) homologous to A. nidulans nudC is reported. The amino terminus of the larger human protein (HNUDC = 45 kDa) does not overlap with A. nidulans NUDC (22 kDa). However, NUDC and the C-terminal 94 amino acids of HNUDC are 67% identical. The C-terminal region of the HnudC gene fully complements the A. nidulans temperature-sensitive nudC3 mutation, suggesting that nudC has an essential function in cell growth that is conserved from filamentous fungi to humans. In initial studies, HNUDC levels were much higher in erythroid precursors compared to most other human tissues. Therefore, the potential role of HnudC in hematopoiesis was explored. In normal human bone marrow, HNUDC protein and mRNA are highly expressed in early myeloid and erythroid precursors and decline as these cells terminally differentiate. To determine whether hematopoietic growth factors induce HnudC expression, TF-1 cells were stimulated by granulocyte-macrophage colony-stimulating factor. This induced a significant increase in HNUDC protein and HnudC mRNA, suggesting that enhancement of HnudC expression in response to growth factor stimulation may be mediated at the transcription level. Furthermore, HNUDC was significantly enhanced in lysates of bone marrow aspirates from patients with acute myelogenous and acute lymphoblastic leukemia compared to aspirates from normal controls, suggesting that HnudC is involved in malignant hematopoietic cell growth as well. These data demonstrate that HNUDC is highly expressed in normal and malignant human hematopoietic precursors and suggest it is of functional importance in the proliferation of these cells.