[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.

Protective effect of hsa-miR-570-3p targeting CD274 on triple negative breast cancer by blocking PI3K/AKT/mTOR signaling pathway

To find out the role of hsa-miR-570-3p targeting CD274 in triple negative breast cancer (TNBC) via PI3K/AKT/mTOR signaling pathway. Hsa-miR-570-3p and CD274 expressions in 175 TNBC patients were detected by qRT-PCR and immunohistochemistry respectively. The human TNBC cell lines (MDA-MB-468 and MDA-MB-231) were used to verify the targeting relationship between hsa-miR-570-3p and CD274 via dual-luciferase reporter gene assay. Then, MDA-MB-468 and MDA-MB-231 cells were divided into Blank, miR-NC, miR-570-3p mimics, NC siRNA, CD274 siRNA, and miR-570-3p inhibitors + CD274 siRNA groups. Next, the biological activities of cells were detected by MTT, Cell-Light EdU, Annexin-V-FITC/PI, wound healing and Transwell invasion assays. Western blotting was conducted to detect protein expressions.MiR-570-3p expression was lower in tumor tissues than that in adjacent normal tissues, which was more obvious in CD274-positive TNBC patients, which targeted CD274 in TNBC cell lines. MiR-570-3p inhibited cell proliferation, invasion and migration, but induced cell apoptosis accompanying the upregulation of apoptotic proteins and downregulation of anti-apoptotic protein. CD274 siRNA had the similar results of miR-570-3p mimics, which could be reversed by miR-570-3p inhibitors. Besides, both miR-570-3p mimics and CD274 siRNA blocked PI3K/AKT/mTOR signaling pathway in TNBC cell lines. Hsa-miR-570-3p was downregulated and CD274 was upregulated in TNBC patients. Besides, hsa-miR-570-3p targeted CD274 to inhibit cell proliferation, invasion, migration, and induce cell apoptosis, which may be related to the suppression of PI3K/AKT/mTOR pathway.

[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.

[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.

[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.

Patient harboring a novel PIK3CA point mutation after acquired resistance to crizotinib in an adenocarcinoma with ROS1 rearrangement: A case report and literature review

ROS1 rearrangement occurs in 1–2% of non‐small cell lung cancer (NSCLC) cases. These patients would benefit from treatment with the anaplastic lymphoma kinase inhibitor, crizotinib; however, resistance to crizotinib inevitably develops in such patients despite an initial response. The mechanism of acquired resistance to crizotinib in patients with NSCLC with ROS1 rearrangement has not yet been identified. Herein, we report a case of a 66‐year‐old woman diagnosed with adenocarcinoma. PCR revealed no EGFR or ALK mutations. After the patient underwent several rounds of chemotherapy, crizotinib was administered. The disease explosively progressed six months later. A novel PIK3CA gene point mutation (p.L531P) was detected by next generation sequencing. This case is the second report of bypass activation conferred crizotinib resistance in a patient with NSCLC with ROS1‐rearrangement, but is the first to confirm that activation of the mTOR signaling pathway leads to acquired crizotinib resistance.

[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-β-cryptoxanthin (51.69 μg g-1), all-trans-β-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.

[Pathological features and ultrastructure of N-methyl-N-nitrosourea (MNU)-induced thymic lymphomas in mice]

The objective of study was to investigate the origin and to classify the subtype of N-methyl-N-nitrosourea (MNU)-induced thymic lymphomas in mice. Histopathologic, immunohistochemical and ultrastructural studies were performed to analyze the pathological features of the neoplasms. The results showed that the thymus in all cases became totally replaced by sheets of cells of the lymphoid series. All the tumors coexpressed CD3 and TdT. Transmission electron microscopic study showed the plasma membranes of malignant lymphoma cells were smooth. The nuclear profiles were usually regular, with varying percentage of convoluted nuclei. Few cell organoids were observed in cytoplasm. In conclusion, all the MNU-induced tumor classified by histopathologic, immunohistochemical and ultrastructural studies as precursor lymphoblastic lymphoma that were unquestionably related to the thymus origin and T-cell lineage.

[Establishment of an animal model with thymic lymphoma in mice]

The objective of study was to establish an animal model with thymic lymphoma in mice induced by intraperitoneal injection of DNA alkylating agent N-methyl-N-nitrosourea (MNU). Male and female mice of the C57BL/6 strain were injected by the intraperitoneal route with MNU solution in a dosage of 50 mg/kg body weight. The injection was repeated at week 8. Following injection of MNU, the general status of mice was observed. All mice were sacrificed for autopsy at the 22nd experimental week. Complete gross examination was performed for detection of tumor masses. The results showed that at the 22nd week, the incidence of thymic lymphoma in MNU-treated animals was 67.5% (27/40). No significant sex difference in the incidence of thymic lymphoma was observed. In conclusions, an animal model with thymic lymphoma in mice can be established by twice intraperitoneal administration of MNU. The biological behavior of the induced tumors resembles to those of human thymic lymphoma derived from thymic T-cells.

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.

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.

Capture envelopes of rectangular hoods in cross drafts

The suction fields of the rectangular hoods of various aspect ratios varying from 0.1 to 10 that are subject to the influence of cross drafts were experimentally studied in an apparatus consisting of a hood model/wind tunnel assembly. The velocity field on the symmetry plane was measured with a two-component laser Doppler anemometer. Being under the influence of cross draft, the suction field presents a characteristic capture envelope, which is described by a dividing streamline. The characteristics of the capture envelope were found to be determined by the cross-draft to hood-suction velocity ratio R and the hood-opening aspect ratio AR. The flow characteristics of the hoods with aspect ratios less than unity were dramatically different from those with aspect ratios greater than one. If areas of the hood openings had the same values, the hydraulic-diameter normalized characteristic length scales of the capture zone of the square hood were as same as those of the circular hood. When the diameter of a circular hood was equal to the width of a square hood, the physical dimensions of the capture zones created by these two hoods coincided with each other.

Homocysteine thiolactone induces apoptotic DNA damage mediated by increased intracellular hydrogen peroxide and caspase 3 activation in HL-60 cells

The cytotoxicity of homocysteine derivatives on chromosomal damage in somatic cells is not well established. The present study used reactive homocysteine derivative of homocysteine thiolactone (Hcy) to investigate its causal effect on apoptotic DNA injury in human promyeloid HL-60 cells. Our results demonstrated that Hcy induced cell death and features of apoptosis including increased phosphotidylserine exposure on the membrane surface, increased apoptotic cells with hypoploid DNA contents, and internucleosomal DNA fragmentation, all of which occurred in a time- and concentration-dependent manner. Hcy treatment also significantly increased intracellular reactive oxygen species H2O2, which coincided with the elimination of caspase 3 proenzyme levels and increased caspase 3 activity at the time of the appearance of apoptotic DNA fragmentation. Preincubation of Hcy-treated HL-60 cells with catalase completely scavenged intracellular H2O2, thus inhibiting caspase 3 activity and protecting cells from apoptotic DNA damage. In contrast, superoxide dismutase failed to inhibit Hcy-induced DNA damage. Taken together, these results demonstrate that Hcy exerted its genotoxic effects on HL-60 cells through an apoptotic pathway, which is mediated by the activation of caspase 3 activity induced by an increase in intracellular hydrogen peroxide.

The capture envelope of a flanged circular hood in cross drafts

The flow patterns of an exterior circular hood subject to the influence of various uniform cross drafts were experimentally studied in an apparatus consisting of hood-model/wind-tunnel assembly. A two-component laser Doppler anemometer was employed to measure the velocity field on the symmetry plane. The streamline patterns were obtained from the measured velocity data. The cross draft caused a characteristic envelope similar to a half Rankine body-of-revolution to form in the flow field. The boundary of the envelope is described by a dividing streamline. All streamlines within the envelope lead to the opening; those outside the envelope evolve to the downstream area. The normalized geometry of the capture envelope is theoretically justified and correlated by modifying the potential theory of point-sink-plus-rectilinear-flow. The domain and shape of the envelope enclosing the hood opening are determined primarily by the velocity ratio between the cross draft and hood suction. The correlated formula is applicable to design the hood parameters, including the sizes of opening and flange as well as the location of contaminant sources.

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 depletion and elevated plasma homocysteine promote oxidative stress in rat livers

This study was designed to determine whether nutritional folate depletion exerts hepatic oxidative stress in relation to elevated plasma homocysteine. To mimic various extents of folate depletion status in vivo, male Wistar rats were fed an amino acid-defined diet containing either 8 (control), 2, 0.5, or 0 mg folic acid/kg diet. After a 4-wk feeding period, the plasma and hepatic folate concentrations of the rats decreased significantly with each decrement of dietary folate. Folate depletion did not significantly affect two major liver antioxidants: reduced glutathione and alpha-tocopherol. Conversely, folate depletion decreased Cu-Zn superoxide dismutase and glutathione peroxidase activities, but had no effect on catalase activity in liver homogenates. Lipid peroxidation products, as measured by thiobarbituric acid-reactive substances, were significantly higher in livers of folate-depleted rats than in those of the controls. This occurrence of hepatic oxidative stress in folate-depleted rats was confirmed by demonstrating an increased susceptibility of livers of folate-depleted rats to lipid peroxidation induced by additional H2O2 or Fe(2+) treatments compared with the controls. Decreasing dietary folate intake resulted in graded increases in plasma homocysteine concentrations of folate-depleted rats. Elevated plasma homocysteine and decreased plasma and hepatic folate concentrations in folate-depleted rats were all strongly and significantly correlated with increased liver lipid peroxidation (/r/ > or = 0.58, P < 0.0003). These data demonstrate that folate depletion and elevated plasma homocysteine promote oxidative stress in rat livers.

Cytoskeletal inhibitors suppress the stomatal opening of Vicia faba L. induced by fusicoccin and IAA

Stomatal movement is governed by osmotic potential, in which K(+) concentration plays the dominant role. Our previous work has shown that both microtubules and microfilaments are involved in regulating stomatal movement. In the present investigation the relationships between cytoskeletal components and K(+) fluxes in stomatal opening were addressed by using fusicoccin (FC), indoleacetic acid (IAA), and cytoskeletal inhibitors to treat both epidermal strips and protoplasts of guard cells. The results revealed that FC and IAA induced stomatal opening with or without KCl in the dark. Also FC or IAA induced guard cell protoplast swelling in the dark even without added KCl. However, the induction was partially suppressed when strips and protoplasts were pretreated with cytochalasin B (CB), an inhibitor of F-actin polymerization, or oryzalin, an inhibitor of plant microtubule polymerization. Thus our preliminary results indicate for the first time that microtubules and microfilaments can affect stomatal opening independently of K(+) fluxes.

Gibberellic acid stabilises microtubules in maize suspension cells to cold and stimulates acetylation of alpha-tubulin

Gibberellic acid is known to stabilise microtubules in plant organs against depolymerisation. We have now devised a simplified cell system for studying this. Pretreatment of a maize cell suspension with gibberellic acid for just 3 h stabilised protoplast microtubules against depolymerisation on ice. In other eukaryotes, acetylation of alpha-tubulin is known to correlate with microtubule stabilisation but this is not established in plants. By isolating the polymeric tubulin fraction from maize cytoskeletons and immunoblotting with the antibody 6-11B-1, we have demonstrated that gibberellic acid stimulates the acetylation of alpha-tubulin. This is the first demonstrated link between microtubule stabilisation and tubulin acetylation in higher plants.

Folate deficiency induces a cell cycle-specific apoptosis in HepG2 cells

The human hepatoma HepG2 cell line was chosen as a representative of solid tissue-derived cell systems in which folate metabolism and apoptosis induction have not been thoroughly investigated. HepG2 cells were cultivated in the control or folate-deficient media (control media lacking of folate, glycine, thymidine and hypoxanthine) for 4 wk. This resulted in a decrease in intracellular folate levels to 32% of the control within 1 wk, which was followed by growth arrest and greater cell death rates. These disturbances of folate deficiency coincided with apoptotic induction, as characteristically shown by nucleosomal DNA fragmentation of 180-200 base pair multimers, nuclear chromatin condensation and positive terminal transferase-mediated dUTP nick end labeling assay. Apoptosis coincided with an accumulation of cells in S-phase, a subsequent G2/M phase block and a significant increase in mean protein content as evaluated by flow cytometric analyses employing a double-staining method. The growth and cell cycle arrest under folate-deficient conditions was independent of a change of p53 expression as measured by an enzyme-linked immunosorbent assay. Supplementation of 2 micromol/L folate normalized cell cycles and diminished DNA fragmentation. Taken together, these data indicate that HepG2 cells cultivated in folate-deficient medium have a low folate concentration, decreased growth and viability, and increased apoptotic propensity. This occurrence of apoptosis was associated with a cell cycle-specific mechanism and independent of p53-mediated pathway.

The solution structure of a cytotoxic ribonuclease from the oocytes of Rana catesbeiana (bullfrog)

RC-RNase is a pyrimidine-guanine sequence-specific ribonuclease and a lectin possessing potent cell cytotoxicity. It was isolated from the oocytes of Rana catesbeiana (bull frog). From analysis of an extensive set of 1H homonuclear 2D NMR spectra we have completed the resonance assignments. Determination of the three-dimensional structure was carried out with the program X-PLOR using a total of 951 restraints including 814 NMR-derived distances, 61 torsion angles, and 76 hydrogen bond restraints. In the resultant family of 15 best structures, selected from a total of 150 calculated structures, the root-mean-square deviation from the average structure for the backbone heavy-atoms involved in well-defined secondary structure is 0.48 A, while that for all backbone heavy-atoms is 0.91 A. The structure of RC-RNase consists of three alpha-helices and two triple-stranded anti-parallel beta-sheets and folds in a kidney-shape, very similar to the X-ray crystal structure of a homolo gous protein, onconase isolated from Rana pipiens. We have also investigated the interaction between RC-RNase and two inhibitors, cytidylyl(2'-->5')guanosine (2',5'-CpG) and 2'-deoxycytidylyl(3'-->5')-2'-deoxyguanosine (3',5'-dCpdG). Based on the ligand-induced chemical shift changes in RC-RNase and the NOE cross-peaks between RC-RNase and the inhibitors, the key residues involved in protein-inhibitor interaction have been identified. The inhibitors were found to bind in a "retro-binding" mode, with the guanine base bonded to the B1 subsite. The His103 residue was found to occupy the B state with the imidazole ring pointing away from the active site. The structure coordinates and the NMR restraints have been deposited in the Brookhaven Protein Data Bank (1bc4 and 1bc4mr, respectively).

Multinuclear NMR resonance assignments and the secondary structure of Escherichia coli thioesterase/protease I: a member of a new subclass of lipolytic enzymes

Escherichia coli thioesterase/protease I is a 183 amino acid protein with a molecular mass of 20,500. This protein belongs to a new subclass of lipolytic enzymes of the serine protease superfamily, but with a new GDSLS consensus motif, of which no structure has yet been determined. The protein forms a tetramer at pH values above 6.5 and exists as a monomer at lower pH values. Both monomer and tetramer are catalytically active. From analysis of a set of heteronuclear multidimensional NMR spectra with uniform and specific amino acid labeled protein samples, we have obtained near-complete resonance assignments of the backbone 1H, 13C and 15N nuclei (BMRB databank accession number 4060). The secondary structure of E. coli thioesterase/protease I was further deduced from the consensus chemical shift indices, backbone short- and medium-range NOEs, and amide proton exchange rates. The protein was found to consist of four beta-strands and seven alpha-helices, arranged in alternate order. The four beta-strands were shown to form a parallel beta-sheet. The topological arrangement of the beta-strands of -1x, +2x, +1x appears to resemble that of the core region of the alpha beta hydrolase superfamily, typically found in common lipases and esterases. However, substantial differences, such as the number of beta-strands and the location of the catalytic triad residues, make it difficult to give a definitive classification of the structure of E. coli thioesterase/protease I at present.

The secondary structure of a pyrimidine-guanine sequence-specific ribonuclease possessing cytotoxic activity from the oocytes of Rana catesbeiana

RC-RNase is a pyrimidine-guanine sequence-specific ribonuclease and a sialic-acid-binding lectin purified from Rana catesbeiana (bullfrog) oocytes. This 111-amino acid protein exhibits cytotoxicity toward several tumor cell lines. In this paper we report the assignments of proton NMR resonances and the identification of the secondary structure deduced from NOE constraints, chemical shift index, 3JNH alpha and amide proton exchange rates. The protein was directly isolated from bullfrog oocytes; we were able to assign all but five of the amino acid backbone protons of the unlabeled protein by analyzing a large set of two-dimensional proton NMR spectra obtained at several temperatures and pH conditions. Our results indicate that the structure of RC-RNase is dominated by the presence of two triple-stranded antiparallel beta-sheets and three alpha-helices, similar to those of the pyrimidine family ribonucleases. Two sets of resonances were observed for 11 amide protons and 8 alpha-protons located in the loop-1 region, an alpha 2 helix, and three beta-strands, (beta 1, beta 3 and beta 4), suggesting the presence of nonlocalized multiple conformations for RC-RNase.

The solution structure of the active domain of CAP18--a lipopolysaccharide binding protein from rabbit leukocytes

We have employed the circular dichroism (CD) technique to characterize the solution structure of CAP18(106-137), a lipopolysaccharide (LPS) binding, antimicrobial protein, and its interaction with lipid A. Our results revealed that CAP18(106-137) may exist in at least three lipid A concentration-dependent, primarily helix conformations. The 'model' structure of CAP18(106-137) in 30% (v/v) TFE, determined by nuclear magnetic resonance (NMR) technique, was found to be a complete and very rigid helix. In this conformation, the cationic and hydrophobic groups of CAP18(106-137) are separated into patches and stripes in such a way that it can favorably interact with lipid A through either coulombic interaction with the diphosphoryl groups or hydrophobic interaction with the fatty acyl chains.

Regulation of folate and one-carbon metabolism in mammalian cells. III. Role of mitochondrial folylpoly-gamma-glutamate synthetase

Wild-type Chinese hamster ovary (CHO) cells and CHO cell transfectants expressing human folylpoly-gamma-glutamate synthetase (FPGS) activity contain mitochondrial FPGS activity of higher specific activity than the cytosolic isozyme. Expression of mitochondrial FPGS activity is required for folate accumulation by mitochondria. The mitochondrial folate pool in CHO cells is not in equilibrium with the cytosolic pool and contains folylpolyglutamates of longer glutamate chain length than cytosolic folates. The inability of AUX-coli, a CHO cell expressing high levels of Escherichia coli FPGS activity and containing pteroyltriglutamate, to support glycine synthesis is due to a lack of mitochondrial FPGS activity. AUX-coli cells lack mitochondrial folate despite containing high levels of cytosolic folate.

Retinopathy, neuropathy and nephropathy in non-insulin-dependent diabetic patients

In 1978, an epidemiological survey for adult diabetes was conducted in Taipei City. A total of 219 Chinese non-insulin-dependent diabetic patients were discovered and 217 of them were examined for retinopathy, neuropathy and nephropathy. Among the 110 men and 107 women studied, 63.1% were free of complications and the prevalences for retinopathy, nephropathy and neuropathy were 24.0%, 12.9% and 23.5%, respectively. The clinical and biochemical data of the patients were compared. For those with and those without complications, the diabetic duration (8.2 +/- 6.7 vs 4.1 +/- 2.7, years), percentage of insulin treatment (8.8% +/- 0.7%), percentage of hypertension (42.5% vs 26.3%), and the fasting plasma glucose (182.8 +/- 63.6 vs 135.0 +/- 44.6, mg/dl) were significantly different. Diabetic duration and glycemic control consistently correlated with retinopathy, nephropathy and neuropathy. Hypertension and insulin treatment were also associated positively with the complications. The more complications the diabetic patients had, the poorer the glycemic control, the longer the diabetic duration, a higher percentage of insulin treatment and hypertension were found.