[The role of facial nerve motor evoked potentials in predicting facial nerve function in vestibular schwannoma surgery].

Objective: To analyze the role of facial nerve motor evoked potentials in predicting facial nerve function in vestibular schwannoma surgery. Methods: In a retrospective clinical study of 226 patients with acoustic neuroma, admitted to our hospital from January 2016 to May 2019, were investigated by facial nerve motor evoked potentials (FNMEP) elicited by multi-pulse transcranial electrical motor cortex stimulation from. For recording the same electrode set-up was used as for continuous EMG monitoring of the orbicularis oculi,oris muscles and mentalis. Pre-surgical (opening dural), intraoperative and post-surgical (closing dural) FNMEP amplitudes and latencies were recorded. End (closing dura) to start (opening dura) amplitude ratios were compared to early-term(3 day after surgery) facial nerve function by House-Brackmann(HB) Grading. Results: 201 patients(88.9%) get a total tumor resection, 15 patients (6.6%) were a subtotal resection, 10 patients(4.4%) were a partial resection. 100 percent of patients had a integrated anatomical preservation of facial nerves, there were four (1.8%) death cases in this group. Reliable FNMEPs were obtained in all patients. The ratio of end-operative to start-operative FNMEP-amplitude showed a negative correlation with early facial nerve function. Correlation was especially close with early function: an amplitude preservation rate of 85.3% led to HB Ⅰ or Ⅱ in 190(84.1%) patients, of 45.6% to HB Ⅲ in 17(7.5%) patients, of 23.1% to HB Ⅳ in 13(5.8%) patients and of 6.7% to HB Ⅴor Ⅵ in 6(2.7%) patients. There was a negative correlation between FNMEP amplitude ratio and post-surgical early HB grading(r=-0.895, P=0.000). Conclusion: FNMEP was highly reliable in predicting early postoperative facial function of the resection of vestibular schwannoma, was a valid protection technique of facial nerve.

[Research progress of alpha-fetoprotein vaccine in hepatocellular carcinoma].

Hepatocellular carcinoma (HCC) is the fifth world's largest malignant tumor, which seriously endangers human health. The commonly used treatment effects are not satisfactory and the mortality rate is still high. Therefore, there is an urgent need for effective adjuvant treatment to improve patient survival. Alpha-fetoprotein (AFP) acts as the most common tumor marker used for HCC diagnosis. Studies have shown that alpha-fetoprotein can self-induce T cells in patients with hepatocellular carcinoma, and its immunogenic antigenic epitopes provide new ideas for the study of AFP vaccine. Presently, a variety of AFP vaccines have been developed, such as DC vaccine, DNA vaccine, and peptide vaccine, which have been successfully applied to HCC mouse model and phase I /II clinical trials, with evident results. This article discusses the molecular mechanism, categories and application prospects of AFP vaccine in HCC.

[The sodium fluorescein-guided microsurgical resection of glioblastoma].

Objective: To investigate the clinic effect of the sodium fluorescein-guided microsurgical resection of glioblastoma. Methods: In a retrospective clinical study, 82 patients with glioblastoma confirmed by post-operative pathologic inspection in the Department of Neurosurgery of Tianjin Huanhu Hospital from January 2016 to June 2017 were randomly divided into sodium fluorescein (FL) group (42 cases) and traditional microsurgical (TM) group (40 cases). The tumors were removed by the sodium fluorescein-guided surgical procedure in the FL group. The tissues which displayed different intensity of fluorescent staining were taken for the pathologic inspection. The resection of tumors were completed under common microscope in the TM group. The two groups of patients underwent MRI enhanced scan at 48 hours after operation to determine the degree of tumor resection. The rate of gross total resection, postoperative complication, recurrent rate of two groups were compared by χ(2) test or Fisher exact test. Results: Totally 135 fluorescent staining samples were obtained in the FL group. Forty-two samples were showed strong fluorescent staining, and all samples were proved to be tumor tissue by pathologic inspection, the sensitivity of FL was 100%. Thirty-seven gliomas were detected from 45 samples of faintly fluorescent staining, sensitivity of FL was 82.3%. Eight gliomas were found from 48 samples of non-fluorescent staining, the specificity of FL was 83.3%. The total resection rate of sodium fluorescein group was 85.7% (36/42), higher than that of traditional microsurgical group (62.5% (25/40)) (χ(2)=5.795, P=0.016). Two groups of patients were followed up to 6 months after the operation, and 6 cases (14.3%, 6/42) were recurred in the FL group. Among them, 1 case died and the average Karnofsky performance score was 82.2±15.2. There were 12 recurrent cases (33.3%, 12/36) in the TM group, of which 2 cases were died and the average Karnofsky performance score was 76.9±20.3. There was significantly statistical difference in recurrent rate (χ(2)=3.962, P=0.047). Conclusions: The sensitivity and specificity of fluorescein staining in glioblastoma tissue are high. And the application of sodium fluorescein-guided microsurgical resection of glioblastoma is safe and simple. Therefore, it is helpful to improve the total resection rate of glioblastoma patients and reduce the recurrence rate.

[Current status regarding the cardiovascular disease-related risk levels among the hypertensive population of different ethnicities in Xinjiang Uygur Autonomous Region, China].

OBJECTIVE: To assess the status of the cardiovascular disease associated risk levels among hypertensive population of Han, Uygur and Kazakh ethnicities, in Xinjiang Uygur Autonornous Region, to guide hypertension prevention and treatment in different ethnicities. METHODS: Four stages random cluster sampling method was used, and all the data was collected from Xinjiang local residents aged over 18 between October 2007 and March 2010. RESULTS: A total of 14 618 subjects completed this survey, in which 2 654 Han, 1 612 Uygur and 2034 Kazakh people diagnosed with hypertension was included in this research. Most of them were"grade 1 hypertension", and the percentage of grade 3 hypertension was Han (19.1%), Uygur (17.3%) and Kazakh (32.3%), respectively. Majority hypertensive people accompanied with 1 risk factor. The risk proportions of low, medium, high and very high in hypertension population of different ethnicities were Han (19.4%, 34.6%, 46.1%), Uygur (17.7%, 37.6%, 44.7%), Kazakh (12.5%, 38.0%, 49.4%) respectively. In Han, Uygur and Kazakh ethnicities, the percentage of high risk and very high risk was highest in hypertensive men aged over 60 years old.The percentages of hypertension awareness were 42.0%, 45.6%, 46.5% and percentages of medicine therapy were 29.6%, 23.4%, 25.2% for Han, Uygur and Kazakh ethnicities, respectively. CONCLUSIONS: Hypertensive people among Han, Uygur and Kazakh ethnicities in Xinjiang are mainly under high risk and very high risk situation of cardiovascular disease, especially in men aged ≥60. The percentage of hypertension awareness and medicine therapy in high risk and very high risk population is the highest, while percentage of awareness in medium risk population is low.

[Role and related mechanism of S1P/S1P1 signal pathway during post conditioning of hypertrophic cardiomyocytes].

OBJECTIVE: To study the role and mechanism of sphingosine-1-phosphate (S1P)/ sphingosine-1-phosphate receptor 1(S1P1) signal pathway during post conditioning of hypertrophic cardiomyocytes. METHODS: Neonatal rat cardiomyocytes were isolated and cultured, then stimulated by norepinephrine (NE) to induce cardiomyocytes hypertrophy. Using tri-gas incubator to create hypoxia and reoxygenation enviroment to mimic ischemia-reperfusion and postconditioning. Hypertrophic cardiomyoctyes were divided into five groups according to the presence or absence of various drugs and postconditiong and relevant signal pathways changes were detected: (1) IPost group (hypoxia+ postconditioning); (2) IPost+ S1P group (cells were pretreated with S1P (1 µmol/L) for 2 h before IPost); (3) IPost+ W-146+ S1P group (cells in IPost+ W-146+ S1P group were pretreated with S1P1 inhibitor W-146 (0.4 µmol/L) for 20 min); (4) IPost+ PD98059+ S1P group (cells in IPost+ S1P group were pretreated with MAPK antagonist PD98059 (125 µmol/L) for 20 min); (5) IPost+ LY-294002+ S1P group (cells in IPost+ S1P group were pretreated with PI3K antagonist LY294002 (0.1 µmol/L) for 20 min). Apoptosis was detected by flow cytometry and protein expression of relevant signal pathways were detected by Western blot. RESULTS: (1)Apoptosis rate was significantly increased in hypoxia/reoxygenation (27.90±4.49)% group compared with normal control group (7.97±2.18)%, which could be significantly reduced in IPost group (15.90±1.77)% (all P<0.05). (2)Apoptosis rate and caspase-3 expression were both significantly lower in IPost+ S1P and IPost+ S1P+ LY-294002 groups than in IPost and IPost+ S1P+ W-146 and IPost+ S1P+ PD98059 group (all P<0.05). (3)p-ERK1/2 expression was significantly higher in IPost+ S1P and IPost+ S1P+ LY-294002 group than in IPost and IPost+ S1P+ W-146 group and IPost+ S1P+ PD98059 group (all P<0.05) while p-Akt expression was similar among IPost, IPost+ S1P+ W-146 and IPost+ S1P+ PD98059 groups. p-ERK1/2 and p-Akt levels in IPost+ S1P+ W-146 group and IPost+ S1P+ PD98059 were similar as in IPost group. CONCLUSIONS: S1P can play protective role on NE induced cardiomyocytes hypertrophy during post conditioning through downregulating caspase-3 expression and reducing apoptosis rate via targeting S1P1 and activating ERK1/2 signal pathway.

[Effect and potential mechanism of ß3-adrenoceptor activation on fibrosis in cardiac fibroblast cell].

OBJECTIVE: To observe the effect of ß3 adrenergic receptor (ß3-AR) on fibrosis in cardiac fibroblasts(CFBs) and explore the related mechanisms. METHODS: Neonatal CFBs were divided into negative control group (N-CFC): CFBs without any intervention; group treated with ß3 adrenergic receptor agonist (AngⅡ-CFC-ß3-AR BRL): CFBs treated with 10(-6) mol/L angiotensin Ⅱ(AngⅡ), 1 hour later treated with 10(-5) mol/L ß3 adrenergic receptor agonist (ß3-AR BRL37344); group treated with ß3 adrenergic receptor antagonist (AngⅡ-CFC-ß3-AR SR): CFBs treated with 10(-6) mol/L AngⅡ, 1 hour later treated with 10(-5) mol/L ß3 adrenergic receptor antagonist (ß3-AR SR59230A); and positive control group (AngⅡ-CFC): CFBs treated with 10(-6) mol/L AngⅡonly. Proliferation of CFBs was detected by the method of WST-1. Protein expression of ß3-AR, transforming growth factor ß1 receptor (TGF-ß1-R), transforming growth factor ß1(TGF-ß1), Smad-2, phospho-Smad-2 (p-Smad-2), collagen-Ⅰ (COL-Ⅰ) and collagen-Ⅲ(COL-Ⅲ) was determined by Western blot assay. RESULTS: (1) The proliferation of CFBs was the highest in AngⅡ-CFC-ß3-AR BRL, followed by AngⅡ-CFC-ß3-AR SR and AngⅡ-CFC group (all P<0.05 vs. N-CFC group). (2) The protein expression level of ß3-AR, TGF-ß1-R, TGF-ß1 and p-Smad-2 was in the same order as proliferation of CFBs. (3) The expression level of COL-Ⅰ and COL-Ⅲ protein was also in the same order as proliferation of CFBs. CONCLUSION: Activation of ß3-AR may promote fibrosis of CFBs through the TGF-ß/Smad signaling pathway and thus aggravate myocardial remodeling.

Genetic polymorphisms of serum amyloid A1 and coronary artery disease risk.

Serum amyloid A (SAA) protein is not only an inflammatory factor but also an apolipoprotein that can replace apolipoprotein A1 (apoA1) as the major apolipoprotein of high-density lipoprotein cholesterol (HDL-C). However, the relationship between genetic polymorphisms of SAA and coronary artery disease (CAD) remains unclear. A total of four single nucleotide polymorphisms (rs12218, rs4638289, rs7131332, and rs11603089) of the SAA gene were genotyped using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method in two independent case-control studies, one of the Han population (1416 CAD patients and 1373 control subjects) and the other of the Uygur population (588 CAD patients and 529 control subjects). We found that the rs12218 CC genotype was more frequent among the CAD patients than among the controls in both the Han (8.3% vs. 4.8%, P < 0.001) and Uygur populations (15.5% vs. 11.3%, P < 0.05). After adjustments for confounding factors, such as sex, age, smoking, drinking, hypertension, diabetes, and serum levels of triglycerides, total cholesterol, HDL, and plasma SAA, the differences remained significant in the Han (CC vs. CT+TT, P < 0.001, OR = 3.863, 95% CI: 1.755-12.477) and Uygur groups (CC vs. CT+TT, P = 0.031, OR = 3.022, 95% CI: 1.033-8.840). Genetic polymorphisms in SAA1 are associated with CAD in the Han and Uygur populations in western China.

Association of a transforming growth factor-ß1 polymorphism with acute coronary syndrome in a Chinese Han population.

Acute coronary syndrome (ACS) is a complex multifactorial and polygenic disorder that is thought to result from the interaction between an individual's genetic makeup and various environmental factors. The aim of this study was to investigate the association of a transforming growth factor-ß1 (TGF-ß1) polymorphism (-509C>T) with ACS in a Chinese Han population. The TGF-ß1 polymorphism was evaluated in 336 patients with ACS and 396 healthy control subjects by polymerase chain reaction-restriction fragment length polymorphism. The genotype distributions of the control and ACS groups were in Hardy-Weinberg equilibrium (X(2) = 3.54 and X(2) = 1.72, respectively, P > 0.05). The frequencies of the CC, CT, and TT genotypes were 22.61, 53.57, and 20.83% in the ACS group, respectively, whereas they were 8.33, 48.74, and 42.17% in controls. There were significant differences between controls and ACS patients in the frequencies of the CC genotype and the C allele. These results suggest that the promoter polymorphism (-509C>T) in TGF-ß1 is associated with ACS in this population. The CC genotype and the C allele of TGF-ß1 might be a specific risk factor of ACS in the Chinese Han population in Xinjiang.

Prevalence of diabetes and impaired fasting glucose in Uygur children of Xinjiang, China.

This study was designed to estimate the prevalence of diabetes and impaired fasting glucose (IFG) in Xinjiang children in western China. Data were obtained from the Chun-Miao Project, a community-based, cross-sectional study designed to investigate the prevalence and risk factors of diabetes in children of the Chinese Uygur population in Xinjiang from February 2010 to May 2012. A total of 3644 children completed the survey and measurements of fasting glucose. Diabetes and IFG were defined using American Diabetes Association 2009 criteria. Overall, 0.7% of the 3644 Uygur children had IFG and 0.1% had diabetes. In the newborn to 8-year-old group, the prevalence of diabetes and IFG was 0.6 and 1.1%, respectively. In the 9-13-year-old group, the prevalence of diabetes and IFG was 0.1 and 0.7%, respectively. There was no evidence of IFG or diabetes in the 14-17-year-old group. Logistic regression analysis suggested that overweight and obesity were independent risk factors of diabetes in Uygur children of Xinjiang. The prevalence of diabetes and IFG in Uygur children was lower than that reported previously in children of other ethnicities in China.

Activation of the ERK1/2 pathway by the CaMEK gene via adeno-associated virus serotype 9 in cardiomyocytes.

Extracellular signal-regulated kinase (ERK1/2) is one of the mitogen-activated protein kinases, key components of the reperfusion injury salvage kinase pathway, which plays an important role in protecting the myocardium from lethal ischemia-reperfusion injury. Constitutive activation of the mitogen-activated protein kinase kinase 1 (CaMEK) can promote ERK1/2 expression, which is thereby expected to exert protective action on the heart against ischemia-reperfusion injury. The adeno-associated virus serotype 9 vector (AVV9) is a novel tool for gene therapies targeting human diseases owing to its nonpathogenic capability for transducing nondividing cells and its long-term transgene expression. We used a recombinant AAV9 vector to deliver the CaMEK gene into cardiomyocytes and assessed whether AAV9 vector-mediated CaMEK gene transfection could enhance the long-term expression and activity of ERK1/2. Our observations suggest that AAV9-mediated gene expression is preferentially restricted to cardiomyocytes and that mediated CaMEK gene transfection enhanced the expression of ERK1/2 phosphorylation and consequently upregulated the expression of downstream components of ERK1/2 and its transcription factors.

S323I polymorphism of the C5L2 gene was not identified in a Chinese population with familial combined hyperlipidemia or with type 2 diabetes.

C5L2, a G protein-coupled receptor, is known to be a functional receptor of acylation-stimulating protein, which is a stimulator of triglyceride synthesis and glucose transport. A novel C5L2 variant (S323I) was identified and its association with familial combined hyperlipidemia (FCH) was recently reported. We looked for this SNP in three Chinese ethnic groups, including Han, Uygur, and Kazakh controls and patients with FCH and type 2 diabetes. One hundred and eighty-two unrelated subjects (77 of Han, 57 of Uygur, and 48 of Kazakh) with FCH were genotyped by direct sequencing, and 852 subjects (342 of Han, 338 of Uygur, 172 of Kazakh) with type 2 diabetes and 200 healthy controls (67 of Han, 72 of Uygur, and 61 of Kazakh) chosen from a cardiovascular risk survey study were genotyped with PCR-RFLP analysis. All 182 subjects with FCH, 99.5% of the type 2 diabetes patients and 100% of the healthy controls were successfully genotyped. Neither the FCH subjects nor the type 2 diabetes patients were found to have the S323I variant. This variant was also not identified in the healthy controls. We found no evidence to demonstrate that the S323I polymorphism contributes to familial combined hyperlipidemia or type 2 diabetes in the Chinese population.

Erythropoietin causes down regulation of colony-stimulating factor (CSF-1) receptors on peritoneal exudate macrophages of the mouse.

We have shown that erythropoietin (epo), the primary regulator of erythrocyte formation, diminished the binding to peritoneal exudate macrophages (PEM) of the principal macrophage growth regulator, colony-stimulating factor (CSF-1). The effect of epo on 125I-CSF-1 binding was dose-dependent; at a concentration of 1-2 U of epo/ml (10(-10) M), CSF-1 binding was almost completely suppressed. Erythropoietin did not compete with CSF-1 for occupancy of the latter's receptors. The effect of epo on CSF-1 binding occurred at 37 degrees C but not at 2 degrees C, and during the continuous exposure of PEM to epo at 37 degrees C we found that CSF-1 binding reached a nadir at 1 h and recovered to pre-exposure levels in 7 h. Our novel results are consistent with the notion that specific receptors for epo exist on the cell surface of PEM and that binding of epo sets in motion a series of cellular events resulting in the internalization of CSF-1 receptors. Thus epo causes down regulation of CSF-1 receptors on PEM. We have previously shown that epo causes suppression of CSF-induced granulocyte-macrophage colony formation by mouse bone marrow cells. The results we present here provide a possible mechanism for these results.

Impact of arbuscular mycorrhizal fungi on uranium accumulation by plants.

Contamination by uranium (U) occurs principally at U mining and processing sites. Uranium can have tremendous environmental consequences, as it is highly toxic to a broad range of organisms and can be dispersed in both terrestrial and aquatic environments. Remediation strategies of U-contaminated soils have included physical and chemical procedures, which may be beneficial, but are costly and can lead to further environmental damage. Phytoremediation has been proposed as a promising alternative, which relies on the capacity of plants and their associated microorganisms to stabilize or extract contaminants from soils. In this paper, we review the role of a group of plant symbiotic fungi, i.e. arbuscular mycorrhizal fungi, which constitute an essential link between the soil and the roots. These fungi participate in U immobilization in soils and within plant roots and they can reduce root-to-shoot translocation of U. However, there is a need to evaluate these observations in terms of their importance for phytostabilization strategies.

Role and influence of mycorrhizal fungi on radiocesium accumulation by plants.

This review summarizes current knowledge on the contribution of mycorrhizal fungi to radiocesium immobilization and plant accumulation. These root symbionts develop extended hyphae in soils and readily contribute to the soil-to-plant transfer of some nutrients. Available data show that ecto-mycorrhizal (ECM) fungi can accumulate high concentration of radiocesium in their extraradical phase while radiocesium uptake and accumulation by arbuscular mycorrhizal (AM) fungi is limited. Yet, both ECM and AM fungi can transport radiocesium to their host plants, but this transport is low. In addition, mycorrhizal fungi could thus either store radiocesium in their intraradical phase or limit its root-to-shoot translocation. The review discusses the impact of soil characteristics, and fungal and plant transporters on radiocesium uptake and accumulation in plants, as well as the potential role of mycorrhizal fungi in phytoremediation strategies.

Effects of the arbuscular mycorrhizal fungus Glomus mosseae on growth and metal uptake by four plant species in copper mine tailings.

A greenhouse experiment was conducted to evaluate the potential role of arbuscular mycorrhizal fungi (AMF) in encouraging revegetation of copper (Cu) mine tailings. Two native plant species, Coreopsis drummondii and Pteris vittata, together with a turf grass, Lolium perenne and a leguminous plant Trifolium repens associated with and without AMF Glomus mosseae were grown in Cu mine tailings to assess mycorrhizal effects on plant growth, mineral nutrition and metal uptake. Results indicated that symbiotic associations were successfully established between G. mosseae and all plants tested, and mycorrhizal colonization markedly increased plant dry matter yield except for L. perenne. The beneficial impacts of mycorrhizal colonization on plant growth could be largely explained by both improved P nutrition and decreased shoot Cu, As and Cd concentrations. The experiment provided evidence for the potential use of local plant species in combination with AMF for ecological restoration of metalliferous mine tailings.

Effects of arbuscular mycorrhizal inoculation on uranium and arsenic accumulation by Chinese brake fern (Pteris vittata L.) from a uranium mining-impacted soil.

A glasshouse experiment was conducted to investigate U and As accumulation by Chinese brake fern, Pteris vittata L., in association with different arbuscular mycorrhizal fungi (AMF) from a U and As contaminated soil. The soil used contains 111 mg U kg(-1) and 106 mg As kg(-1). P. vittata L. was inoculated with each of three AMF, Glomus mosseae, Glomus caledonium and Glomus intraradices. Two harvests were made during plant growth (two and three months after transplanting). Mycorrhizal colonization depressed plant growth particularly at the early stages. TF (transfer factor) values for As from soil to fronds were higher than 1.0, while those for roots were much lower. Despite the growth depressions, AM colonization had no effect on tissue As concentrations. Conversely, TF values for U were much higher for roots than for fronds, indicating that only very small fraction of U was translocated to fronds (less than 2%), regardless of mycorrhizal colonization. Mycorrhizal colonization significantly increased root U concentrations at both harvests. Root colonization with G. mosseae or G. intraradices led to an increase in TF values for U from 7 (non-inoculation control) to 14 at the first harvest. The highest U concentration of 1574 mg kg(-1) was recorded in roots colonized by G. mosseae at the second harvest. The results suggested that P. vittata in combination with appropriate AMF would play very important roles in bioremediation of contaminated environments characterized by a multi-pollution.

Induction of prostaglandin production by hyperthermia in murine peritoneal exudate macrophages.

In response to inflammatory stimuli, macrophages synthesize and secrete prostaglandins (PGE) along with other potent inflammatory mediators. We have studied the effect of hyperthermia on the production of PGE by murine mononuclear phagocytes. Exposure to high temperature induced PGE production by cultured C3H/HeJ exudate macrophages in a time- and temperature-dependent manner. Increase in PGE production was detected when macrophages were treated at 41 degrees C and above for 1 h with a much greater increase at 42 and 43 degrees C. The secretion of PGE into culture supernatants by heat-treated macrophages reached a maximum approximately 24 h after heat treatment. The production of PGE by macrophages after hyperthermia was inhibited either by the addition of 5 X 10(-7) M indomethacin or by the subsequent incubation at 4 degrees C, suggesting that the elevated PGE production by macrophages is mediated through the activation of cyclooxygenase. Heat treatment under the same conditions failed to stimulate the production of PGE by either a human monocyte-like tumor cell line (U-937) or a mouse fibroblast cell line (L-929).

Human THP-1 monocytic leukemic cells induced to undergo monocytic differentiation by bryostatin 1 are refractory to proteasome inhibitor-induced apoptosis.

The ubiquitin-proteasome pathway is the principal mechanism for the degradation of short-lived proteins in eukaryotic cells. We demonstrated that treatment of THP-1 human monocytic leukemia cells with Z-LLL-CHO, a reversible proteasome inhibitor, induced cell death through an apoptotic pathway. Apoptosis in THP-1 cells induced by Z-LLL-CHO involved a cytochrome c-dependent pathway, which included the release of mitochondrial cytochrome c, activation of caspase-9 and -3, and cleavage of Bcl-2 into a shortened 22-kDa fragment. Induction of apoptosis by protease inhibitor also was detected in U937 and TF-1 leukemia cell lines and cells obtained from acute myelogenous leukemia patients but not in normal human blood monocytes. Treatment of human blood monocytes with Z-LLL-CHO did not induce apoptosis or Bcl-2 cleavage in these cells that rarely proliferate. Interestingly, when THP-1 cells were induced to undergo monocytic differentiation by bryostatin 1, a naturally occurring protein kinase C activator, they were no longer susceptible to apoptosis induced by Z-LLL-CHO. Bryostatin 1-induced differentiation of THP-1 cells was associated with growth arrest, acquisition of adherent capacity, and expression of membrane markers characteristic of blood monocytes. Likewise, differentiated THP-1 cells were refractory to Z-LLL-CHO-induced cytochrome c release, caspase activation, and Bcl-2 cleavage. Resistance to Z-LLL-CHO-induced apoptosis in differentiated THP-1 cells was not due to cell cycle arrest. These findings show that the action of proteasome inhibitors is mediated primarily through a cytochrome c-dependent pathway and induces apoptosis in leukemic cells that are not differentiated.

Binding, internalization and degradation of colony-stimulating factor by peritoneal exudate macrophages.

Iodinated colony-stimulating factor produced by L-cells (125I-CSF-1) binds specifically to murine peritoneal exudate macrophages. At 37 degrees C, the cell-bound 125I-CSF-1 was internalized and degraded very rapidly, with the appearance of radioactive iodotyrosine in the medium. At 0 degree C, the cell-bound 125I-CSF-1 was not internalized and degraded, nor did it dissociate from the membrane. The internalization and degradation at 37 degrees C could be blocked or reduced by the presence of phenylglyoxal, methylamine and NH4Cl. The chemical nature of the CSF-1 binding site is polypeptide as judged by its sensitivity to trypsin treatment. After the binding and degradation of unlabeled CSF-1, the exudate cells were no longer able to rebind freshly added 125I-CSF-1, indicating the removal of CSF-1 binding site. The binding capacity of these cells, however, could be restored by prolonged incubation at 37 degrees C but not at 0 degrees C in culture medium containing fetal calf serum.