[Distribution of mosquito species and associated viruses in Hami City of Xinjiang Uygur Autonomous Region from 2019 to 2020].

OBJECTIVE: To investigate the distribution of mosquito species and their associated viruses, and identify Culex pipiens subspecies in Hami City, Xinjiang Uygur Autonomous Region. METHODS: Mosquitoes were captured using mosquito trapping lamps method in Yizhou District, Yiwu County, and Balikun County of Hami City in mi-July, 2019 and 2020. The species and subspecies of all captured mosquitoes were characterized. In addition, the flavivirus, alphavirus, bunyavirus, Japanese encephalitis virus, Liaoning virus, Tahyna virus, tick-borne encephalitis virus and West Nile virus were detected using reverse-transcription PCR assay in captured mosquitoes. RESULTS: A total of 1 496 mosquitoes were captured from Yizhou District, Yiwu County, and Balikun County of Hami City, belonging to 3 genus and 3 species. Cx. pipiens was the dominant mosquito species (986 mosquitoes, 65.91%), followed by Aedes caspius (457 mosquitoes, 30.55%), while Culiseta alaskaensis had the lowest number (53 mosquitoes, 3.54%). All captured Cx. pipiens mosquitoes were identified as Cx. pipiens pipiens based on the terminalia of male mosquitoes. RT-PCR assay tested negative for flavivirus, alphavirus, bunyavirus, Japanese encephalitis virus, Liaoning virus, Tahyna virus, tick-borne encephalitis or West Nile virus in captured Cx. pipiens mosquitoes. CONCLUSIONS: There were 3 species of mosquitoes in Hami City from 2019 to 2020, including Cx. pipiens, Ae. Caspius and C. alaskaensis, with Cx. pipiens as the dominant mosquito species, and all captured Cx. pipiens mosquitoes were Cx. pipiens pipiens; however, no arboviruses were detected.

[Consistency of ALK Ventana-D5F3 immunohistochemistry interpretation in lung adenocarcinoma among Chinese histopathologists].

Objective: To understand the consistency of ALK Ventana-D5F3 immunohistochemistry (IHC) interpretation in Chinese lung adenocarcinoma among histopathologists from different hospitals, and to recommend solution for the problems found during the interpretation of ALK IHC in real world, with the aim of the precise selection of patients who can benefit from ALK targeted therapy. Methods: This was a multicenter and retrospective study. A total of 109 lung adenocarcinoma cases with ALK Ventana-D5F3 IHC staining were collected from 31 lung cancer centers in RATICAL research group from January to June in 2018. All cases were scanned into digital imaging with Ventana iSCANcoreo Digital Slide Scanning System and scored by 31 histopathologists from different centers according to ALK binary (positive or negative) interpretation based on its manufacturer's protocol. The cases with high inconsistency rate were further analyzed using FISH/RT-PCR/NGS. Results: There were 49 ALK positive cases and 60 ALK negative cases, confirmed by re-evaluation by the specialist panel. Two cases (No. 2302 and No.2701) scored as positive by local hospitals were rescored as negative, and were confirmed to be negative by RT-PCR/FISH/NGS. The false interpretation rate of these two cases was 58.1% (18/31) and 48.4% (15/31), respectively. Six out of 31 (19.4%) pathologists got 100% accuracy. The minimum consistency between every two pathologists was 75.8%.At least one pathologist gave negative judgement (false negative) or positive judgement (false positive) in the 49 positive or 60 negative cases, accounted for 26.5% (13/49), 41.7% (25/60), respectively, with at least one uncertainty interpretation accounted for 31.2% (34/109). Conclusion: There are certain heterogeneities and misclassifications in the real world interpretation of ALK-D5F3 IHC test, which need to be guided by the oncoming expert consensus based on the real world data.

[Correlation analysis on meteorological factors regarding the incidence of hand, foot and mouth disease in Xinjiang Uygur Autonomous Region, 2011-2018].

Objective: To study the correlation between meteorological factors and the incidence of hand, foot and mouth disease (HFMD) in Xinjiang Uygur Autonomous Region (Xinjiang) so as to provide scientific evidence for the early warning, prediction, prevention and control of HFMD. Methods: Data on HFMD surveillance and related population was collected from the China Information System for Disease Control and Prevention from 2011 to 2018. Meteorological data was obtained from http://www.tianqihoubao.com. Correlation analysis on meteorological factors and the incidence of HFMD in Xinjiang was conducted, using the Excel 2007, SPSS 17.0, and Spatial Distribution Map by ArcGIS 10.2 software. Results: HFMD usually occurred between April and July. Numbers of patients reached the top in May and June. Temperature was positively correlated with the incidence of HFMD (r=0.370, P<0.01) while precipitation was positively correlated with the incidence of HFMD (r=0.747, P<0.01). The temperature threshold appeared as 5 ℃-35 ℃ for the incidence of HFMD. Interval period was one month between the peak of both the incidence of HFMD and the precipitation. A power function relationship (y=0.009 4x(2.332 9), R(2)=0.898 9) was noticed between the precipitation and the incidence of HFMD. Conclusions: The incidence of HFMD was closely related to the meteorological factors including temperature and precipitation in Xinjiang during 2011-2018. Our findings have provided evidence for the development of early warning system on HFMD in Xinjiang.

[Diagnostic significance of lymph node core needle biopsy for lymphoproliferative disease: a clinicopathologic study of 1 013 cases].

Objective: To study the clinicopathologic features of lymphoproliferative disease by lymph node core needle biopsy(CNB)and to evaluate the diagnostic significance of CNB for lymphoproliferative disease. Methods: The annual distribution, entity constitute, clinical finding, gross feature, morphologic change, affiliate study and repeat biopsy diagnosis of 1 013 cases of lymph node CNB diagnosed at West China Hospital of Sichuan University from January 2009 to December 2015 were investigated. Results: (1) Proportion of lymph node CNB in total amount of biopsy specimens increased from 0.2% in 2009 to 0.8% in 2015.(2) The study cohort included 471 lymphomas, 12 atypical lymphoid hyperplasia (ALH), 136 suspected lymphomas, 372 benign lesions, and 22 cases of descriptive diagnoses. The most common types were diffuse large B cell lymphoma and T-lymphoblastic lymphoma. (3) Majority of patients were adolescents and children younger than 20 years or the elderly older than 60 years. 53.1% CNB tumor specimen consisted of ≥4 tissue cores and 40.5% were >2 cm in length. (4) 104 CNB cases with previous history of excision biopsy was included 45 carcinomas(no metastatic carcinoma was found), 32 lymphomas for treatment observation.1/14 suspicious lymphomas, 1/1 ALH and 3/22 cases benign lesions were diagnosed as lymphoma by repeat biopsy respectively. (5) 217 CNB cases were diagnosed as lymphoma by subsequent CNB (70), or subsequent excision biopsy (147) including 78.5%(73/93) suspected lymphomas, 5/7 ALH and 32.3%(20/62)benign lesions. Conclusions: Lymph node CNB has certain clinical indications, although limited for the diagnosis of lymphoproliferative disorders. Suspected lymphomas and ALH diagnosed by CNB should be followed by repeat tissue biopsy. For the benign lesions by CNB it does not rule out additional biopsy to further investigate the lesion.

[Application of immunohistochemistry for p16 and GATA3 and molecular HPV typing in diagnosis of secondary bladder involvement by cervical carcinoma].

Objective: To investigate the expression of p16 and GATA3 and the detection of human papillomavirus (HPV) in secondary bladder involvement by cervical carcinomas. Methods: Sixteen cases of cervical carcinoma with bladder involvement diagnosed from December 2008 to March 2016 were collected and evaluated by light microscopy, immunohistochemistry for p16 and GATA3 detection and PCR-reverse dot blot for molecular typing of HPV. Results: The age of the patients ranged from 25 to 76 years with median of 52 years. Morphologically, 14 cases(14/16) showed tumor nests infiltrating lamina propria or muscle bundles of the bladder. By immunohistochemistry, 15 cases (15/16) were found to be diffusely and strongly positive for p16, and 1 showed patchy staining pattern. Seven cases (7/7) of corresponding original cervical cancers were also diffusely and strongly positive for p16. GATA3 staining was negative in 13 cases (13/16), and focal weak to moderate positivity was detected in 3 cases.Three cases (3/7) of corresponding original cervical cancers showed focal weak to moderate positivity of GATA3. Fifteen cases (15/16) showed concordant high risk HPV-positivity, including HPV16 in 8 cases and HPV31 in one case. Five cases showed co-infection of HPV16 and HPV18. One case showed co-infection with HPV18 and HPV45. Conclusion: Differential diagnosis by p16 or GATA3 alone is of limited value. Combination of immunohistochemistry for p16 and GATA3 and molecular typing for HPV detection are useful to distinguish primary bladder carcinoma from the secondary involvement by cervical carcinoma.

Preparation of carotenoid extracts and nanoemulsions from Lycium barbarum L. and their effects on growth of HT-29 colon cancer cells.

Lycium barbarum L., a traditional Chinese herb widely used in Asian countries, has been demonstrated to be protective against chronic diseases such as age-related macular degeneration. The objectives of this study were to determine the carotenoid content in L. barbarum by high-performance liquid chromatography-mass spectrometry, followed by preparation of a carotenoid nanoemulsion to evaluate the mechanism of inhibition on HT-29 colon cancer cells. The highest extraction yield of carotenoids was attained by employing a solvent system of hexane-ethanol-acetone (1:1:1, v/v/v). Nine carotenoids, including neoxanthin (4.47 µg g-1), all-trans-zeaxanthin and its cis-isomers (1666.3 µg g-1), all-trans-ß-cryptoxanthin (51.69 µg g-1), all-trans-ß-carotene and its cis-isomers (20.11 µg g-1), were separated within 45 min and quantified using a YMC C30 column and a gradient mobile phase of methanol-water (9:1, v/v) (A) and methylene chloride (B). A highly stable carotenoid nanoemulsion composed of CapryolTM 90, Transcutol®HP, Tween 80 and deionized water was prepared with a mean particle size of 15.1 nm. Characterization of zeaxanthin standard, blank nanoemulsion, carotenoid extract and carotenoid nanoemulsion by differential scanning calorimetry curves and Fourier transform infrared spectra revealed a good dispersion of zeaxanthin-dominated carotenoid extract with no significant chemical change after incorporation into nanoemulsion. The in vitro release kinetic study showed a higher release profile at pH 5.2 than at physiological pH 7.4, suggesting a rapid release of carotenoids in the acidic environment (pH 4.5-6.5) characteristic of tumors. Both the carotenoid nanoemulsion and the extract were effective at inhibiting growth of HT-29 colon cancer cells, with an IC50 of 4.5 and 4.9 µg ml-1, respectively. Also, both treatments could up-regulate p53 and p21 expression and down-regulate CDK2, CDK1, cyclin A and cyclin B expression and arrest the cell cycle at G2/M. The study may form a basis for further exploration of L. barbarum nanoemulsion in cancer treatment.

[Survey of the first case of Zika virus disease in the mainland of China].

OBJECTIVE: To analyze epidemiological characteristics of the first laboratory confirmed case of Zika virus disease in the mainland China, and provide evidence for the prevention and control of the spread of Zika virus disease. METHODS: Epidemiological survey was conducted for the first suspect case of Zika virus disease in China, and medical observation was conducted for the close contacts. The nucleic acid detection of Zika virus was conducted with Real-time RT-PCR by using blood and urine samples collected from the cases. RESULTS: The first case of Zika virus disease was confirmed. The case was cured and discharged on 18(th) day after the onset. The blood sample on 10(th) day after the onset and urine samples on 11-13(th) days after the onset were all positive for Zika virus. The case had the history of mosquito bites in the endemic country before the onset. The close contacts showed no Zika virus disease-like symptoms during the medical observation period. CONCLUSION: The case reported by Jiangxi province was the first imported case of Zika virus disease in the mainland of China. The infection was related with the mosquito bites in Venezuela where Zika virus disease in endemic.

Restoration of erectile function with intracavernous injections of endothelial progenitor cells after bilateral cavernous nerve injury in rats.

Endothelial progenitor cells (EPCs) are bone marrow-derived endothelial cells capable of circulating, proliferating, and differentiating into mature endothelial cells. Circulating EPCs can be directly recruited to some extent at sites of injury, and their administration could accelerate repair or endothelialization of the damaged tissue. We investigated the effects of intracavernous injections of EPCs into the corpora cavernosa of rats with erectile dysfunction (ED) caused by bilateral cavernous nerve (CN) injury. Overall, 24 male Sprague-Dawley rats were randomized into three groups: sham surgery, vehicle-only, or EPC treatment. Rats in the EPC treatment and vehicle-only groups were subjected to bilateral CN injury before injection of EPCs or vehicle, respectively, into the corpora cavernosa. Four weeks after surgery, erectile function was assessed by measuring maximum intracavernosal pressure (ICP), change in ICP, area under the ICP curve, and ratio of change in ICP and mean arterial pressure (MAP; ΔICP/MAP). Penile tissue was histomorphometrically analyzed for the expression of neural nitric oxide synthase (nNOS), neurofilament-1 (NF-1), von Willebrand factor (vWF), endothelial NOS (eNOS), and smooth muscle cell content. Maximum ICP and all other functional parameters of erectile function were significantly reduced in the vehicle-only group vs. the sham and EPC treatment groups (all p < 0.001). Smooth muscle cell content was decreased in the vehicle-only vs. the sham and EPC treatment groups (both p < 0.01). Expressions of vWF and eNOS in the dorsal artery were significantly higher in the EPC treatment than the vehicle-only group (p < 0.05). In conclusion, EPC treatment restored erectile function in a rat model of bilateral CN injury through recruitment of EPCs toward the dorsal artery and preservation of smooth muscle cells in the corpus cavernosum. These findings elucidate the therapeutic potential of EPCs for treating ED in humans.

Hepatitis B virus X protein activates human hepatic stellate cells through upregulating TGFß1.

We investigated the effects of the hepatitis B virus X gene (HBV X) on the activation of human hepatic stellate cells (HSCs) and the possible mechanisms underlying the pathway. Recombinant plasmid pHBV-X-IRES2-EGFP was constructed and transfected into HL-7702 cells using a lipid-mediated method. Transfected cells were screened by G418, which detected stable expression of the X gene by reverse transcription (RT)-PCR and Western blot analysis, and named L02/x. Cells not subjected to G418-selection were analyzed to confirm the transient expression of the X gene and named L02/48x. Subsequently, L02/x and L02/48x, together with non-HBx-expressing cells, were co-cultured with HSCs in a non-contact transwell system. After 36 h of co-culture, the proliferation and migration of HSCs was detected using different cell counting methods. Finally, the mRNA and protein levels of α-SMA, Col I, and TGFß1 in HSCs were detected by real-time PCR and western blot analysis. RT-PCR and Western blot analysis showed that L02/x and L02/48x cells can express HBV X gene mRNA and protein. Additionally, HSCs co-cultured with L02/x or L02/48x cells showed significantly higher proliferation and migration levels than control groups. Real-time PCR and Western blot analysis showed that the mRNA and protein expressions of α-SMA, Col I, and TGFß1 in HSCs co-cultured with HBx-expressing liver cells were higher than those in control groups. HBx protein activated HSCs in vitro, leading to increased proliferation and migration of HSCs and upregulation of α-SMA and Col I. The TGFß1 gene may be involved in this pathway.

Dose-dependent folic acid and memantine treatments promote synergistic or additive protection against Aß(25-35) peptide-induced apoptosis in SH-SY5Y cells mediated by mitochondria stress-associated death signals.

Increased dietary folic acid (FA) is associated with reduced risks of Alzheimer's disease (AD). The AD drug memantine (Mn) has had limited therapeutic effects for the treatment of patients with moderate to severe AD. This study investigated whether and the underlying mechanisms by which the combination of Mn and FA may have synergistic or additive effects in protecting against amyloid-ß(25-35) peptide (Aß)-induced neurocytotoxicity. Aß treatment of human neuroblastoma SH-SY5Y cells significantly induced a 6-fold increase of apoptotic cells compared with the Aß-untreated group. Preincubation of Aß-exposed cells with FA (500 µM) or Mn (20 µM) caused a 22% and 10% reduction of apoptotic cells, respectively, whereas the combo-treatments at such doses synergistically alleviated Aß-induced apoptosis by 60% (P<0.05). The apoptotic protection by the combo-treatments coincided with attenuating Aß-elicited mitochondrial (mt) membrane depolarization and abolishing Aß-induced mt cytochrome c release to the cytosol. Increased levels of FA at 1000 µM in combination with 20 µM Mn exerted an additive protection against Aß(25-35)-induced-apoptosis as compared to the isolate Mn group (P<0.05). The combo-treatments reversed Aß-elicited mt membrane depolarization, attenuated Aß-elicited mt cytochrome c release to the cytosol, and diminished Aß-promoted superoxide generation. The apoptotic-protection by such combo-treatments was partially abolished by carbonyl cyanide 3-chlorophenylhydrazone (mt membrane potential uncoupler) and sodium azide (mt cytochrome c oxidase inhibitor). Taken together, the data demonstrated that dose-dependent FA and Mn synergistically or additively protected SH-SY5Y cells against Aß-induced apoptosis, which was partially, if not completely, mediated by mt stress-associated death signals.

Correlations between folate, B12, homocysteine levels, and radiological markers of neuropathology in elderly post-stroke patients.

OBJECTIVE: To investigate serum levels of folate, B12, and total homocysteine (tHcy) in elderly post-stroke patients, and the possible correlations with radiological markers of neuropathology. DESIGN: Cross-sectional study. SETTING: Department of Neurology, Cardinal Tien Hospital. SUBJECTS: Eighty-nine elderly post-stroke patients were enrolled for dietary assessment and blood tests. Neuroradiological assessment was done in 62 of these patients. MAIN OUTCOME MEASURES: Dietary folate and vitamin B12 intakes were evaluated by a 24-h recall system using a semi-quantitative questionnaire. Circulating levels of folate, B12, and tHcy were measured. Magnetic resonance imaging (MRI) or computed tomography (CT) was used for evaluation of brain lesions including infarction and atrophy. RESULTS: Mean folate and B12 intakes of these post-stroke patients were 69% and 261% of the recommended dietary allowances (RDA), respectively. Inadequate folate levels, defined as serum folate < 6 ng/mL, was noted in 68% of these patients. Hyperhomocysteinemia levels (tHcy >or=15 micromol/L) were observed in 48%. According to tertiles of serum tHcy and folate levels, the rate of brain atrophy, but not brain infarctions, are significantly associated with elevated tHcy (P = 0.0126) and decreased folate levels (P = 0.0273). After adjustments for age, sex, disease status, brain infarctions and carotid stenosis, the odds ratio of brain atrophy was 9.8 (95% CI: 1.7-56.4, P = 0.0101) in the hyperhomocysteinemia group and 9.6 (95% CI: 1.1-81.3, P = 0.0377) in the low folate group (serum folate < 3.0 ng/mL) compared with the group with normal tHcy and folate levels. No significant association was noted between vitamin B12 levels and brain lesions. CONCLUSIONS: Our data shows that folate deficiency and hyperhomocysteinemia are prevalent in elderly post-stroke patients. These two conditions are strongly and independently associated with the development of brain atrophy.

Development and evaluation of an air-curtain fume cabinet with considerations of its aerodynamics.

In order to avoid the inherent aerodynamic difficulties of the conventional fume hood, an innovative design--the 'air curtain-isolated fume hood' is developed. The new hood applies a specially designed air curtain (which is generated by a narrow planar jet and a suction slot flow at low velocities) across the sash plane. The hood constructed for the study is full size and transparent for flow visualization. The aerodynamic characteristics are diagnosed by using the laser-light-sheet-assisted smoke flow visualization method. Four characteristic air-curtain flow modes are identified in the domain of jet and suction velocities when the sash remains static. Some of these characteristic flow modes have much improved flow patterns when compared with those of the conventional fume hoods. From the viewpoint of the aerodynamics and mass transport, the results indicate that the air curtain properly setup across the sash opening allows almost no sensible exchange of momentum and mass between the flowfields of the cabinet and the outside environment. Two standard sulfur hexafluoride (SF6) tracer gas concentration measurement methods following the ANSI/ASHRAE 110-1995 standard and the prEN14175 protocol for static test are employed to examine the contaminant leakage levels. Results of the rigorous examinations of leakage show unusually satisfactory hood performance. The leakage of the tracer gas can approach almost null (<0.001 p.p.m.) if the jet and suction velocities are properly adjusted.

Aerodynamic characteristics and design guidelines of push-pull ventilation systems.

Aerodynamic characteristics such as the flow patterns, velocity field, streamline evolutions, characteristic flow modes and characteristic flow regimes of the push-pull ventilation system are cross-examined by using the laser-light sheet smoked-flow visualization method and laser Doppler velocimetry. Four characteristic flow modes, which are denoted as dispersion, transition, encapsulation and strong suction, are identified in the domain of the push-jet and pull-flow velocities at various open-surface tank widths and rising gas velocities. It is argued phenomenologically, from the aerodynamic point of view, that operating the system in the strong suction regime would be a better strategy than operating it in other characteristic regimes for the consideration of capture efficiency. Design guidelines are developed and summarized based on the results obtained from this study. The regression formulas for calculating the critical values of the push-jet and the pull-flow velocities are provided for easy access. The sulfur hexafluoride tracer gas validation technique is performed to measure the capture efficiency. The results of tracer gas validations are consistent with those obtained from the aerodynamic visualization and measurements. The operation points obtained by employing the American Conference of Governmental Industrial Hygienists design criteria are compared with the results obtained in this study for both the aerodynamics and the capture efficiency. Methods for improving the capture efficiency and energy consumptions are suggested.

In vitro folate supplementation alleviates oxidative stress, mitochondria-associated death signalling and apoptosis induced by 7-ketocholesterol.

Folate has recently been proposed as a new antioxidant. Folate supplementation may have a protective effect in counteracting oxidant-induced apoptotic damage. The present studies were undertaken to examine whether there is a direct link between folate levels, antioxidant capability and reduced apoptotic damage. Using an in vitro cellular model of 7-ketocholesterol (KC)-induced apoptosis, U937 cells were pre-cultured with a folate-deficient medium supplemented with various levels of folate (2-1500 micromol/l) before treatment with 7-KC. Apoptotic markers, mitochondria-associated death signals and levels of reactive oxygen species were assayed. After treatment with 7-KC for 30 h, low and high levels of folate supplementation significantly (P<0.05) reduced nuclear DNA loss. Only high levels of folate supplementation (>1000 micromol/l) were effective in counteracting 7-KC-promoted apoptotic membrane phosphatidylserine exposure and DNA laddering. The attenuation of 7-KC-induced apoptotic damage by high-dose folate supplementation coincided with a partial normalization of mitochondria membrane potential dissipation, a suppression of cytochrome c release and an inhibition of procaspase 3 activation. The prevention of mitochondrial dysfunctions and apoptotic processes was associated with antioxidant actions of high-dose folate by a marked scavenging of intracellular superoxide. Collectively, our present results demonstrate that in vitro folate supplementation exerts differentially protective effects against 7-KC-induced damage. High-dose supplementation alleviates oxidative stress, mitochondria-associated death signalling and apoptosis induced by 7-KC. However, the in vivo relevance is not clear and requires further study.

Microtubule dynamics are involved in stomatal movement of Vicia faba L.

To obtain a full picture of microtubule (MT) behavior during the opening and closure of guard cells we have microinjected living guard cells of Vicia faba with fluorescent tubulin, examined fine detail by freeze shattering fixed cells, and used drug treatments to confirm aspects of MT dynamics. Cortical MTs in fully opened guard cells are transversely oriented from the ventral wall to the dorsal wall. When the stomatal aperture was decreased by darkness, these MTs became twisted and patched and broken down into diffuse fragments when stomata were closed. When the closed stomata were opened in response to light, the MTs in guard cells changed from the diffused, transitional pattern back to one in which MTs are transversely oriented from stomatal pore to dorsal wall. This observation indicates a linkage between these MT changes and stomatal movement. To confirm this, we used the MT-stabilizing agent taxol and the MT-depolymerizing herbicide oryzalin and observed their effects on the stomatal aperture and MT dynamics. Both drugs suppressed light-induced stomatal opening and dark-induced closure. MTs are known to be necessary for maintaining the static kidney shape of guard cells; the present data now show that the dynamic properties of polymeric tubulin accompany changes in shape with stomatal movement and may be functionally involved in stomatal movement.

Folate deficiency-induced oxidative stress and apoptosis are mediated via homocysteine-dependent overproduction of hydrogen peroxide and enhanced activation of NF-kappaB in human Hep G2 cells.

Folate coenzymes are critical for de novo synthesis of purine and thymidine, and for interconversion of amino acids. Folate deficiency inhibits cellular proliferation, disturbs cell cycling, causes genetic damage and eventually results in cell death. Previously, we demonstrated that the demise of human hepatoma Hep G2 cells mediated by folate deficiency proceeded via a p53-independent apoptosis, and the perturbation of intracellular calcium homeostasis was also shown to be involved. To further delineate the mechanism associated with this observed phenomenon, Hep G2 cells were cultivated in the control or folate-deficient media (control media lacking folate, glycine, thymidine and hypoxanthine) for 4 weeks. At the end of this cultivation period, we found that TBARS (an index of lipid peroxidation) concentrations in the folate-deficient cells were drastically increased as compared to the control cells (0.04 vs 0.01 nmole/10(6) cells), indicating that a severe oxidative stress of the former cells had occurred. This phenomenon was also shown to coincide with the ability of these folate-deficient cells to elaborate increased amounts of H2O2 as compared to its folate-supplemented cells (2.87 vs 0.98 nmole/10(5) cells/h). Furthermore, the accelerated production of H2O2 by the folate-deficient cells was also closely correlated with the elevated homocysteine concentrations released in the culture medium (15.37 +/- 2.4 vs 3.58 +/- 2.4 micromole/L; P< 0.001). Finally, we demonstrated that folate deficiency was indeed capable of activating a redox-sensitive transcription factor, NF-kappaB, which is crucial in the control of a reactive oxygen species-mediated apoptosis. In summary, we show that folate deficiency-induced apoptosis is proceeded via the enhanced activation of NF-kappaB, which is the resulting form of the homocysteine-mediated overproduction of hydrogen peroxide.