Differential Radiosensitization in DNA Mismatch Repair-Proficient and -Deficient Human Colon Cancer Xenografts with 5-Iodo-2-pyrimidinone-2′-deoxyribose

PURPOSE

5-iodo-2-pyrimidinone-2'-deoxyribose (IPdR) is a pyrimidinone nucleoside prodrug of 5-iododeoxyuridine (IUdR) under investigation as an orally administered radiosensitizer. We previously reported that the mismatch repair (MMR) proteins (both hMSH2 and hMLH1) impact on the extent (percentage) of IUdR-DNA incorporation and subsequent in vitro IUdR-mediated radiosensitization in human tumor cell lines. In this study, we used oral IPdR to assess in vivo radiosensitization in MMR-proficient (MMR+) and -deficient (MMR-) human colon cancer xenografts.

EXPERIMENTAL DESIGN

We tested whether oral IPdR treatment (1 g/kg/d for 14 days) can result in differential IUdR incorporation in tumor cell DNA and subsequent radiosensitization after a short course (every day for 4 days) of fractionated radiation therapy, by using athymic nude mice with an isogenic pair of human colon cancer xenografts, HCT116 (MMR-, hMLH1-) and HCT116/3-6 (MMR+, hMLH1+). A tumor regrowth assay was used to assess radiosensitization. Systemic toxicity was assessed by daily body weights and by percentage of IUdR-DNA incorporation in normal bone marrow and intestine.

RESULTS

After a 14-day once-daily IPdR treatment by gastric gavage, significantly higher IUdR-DNA incorporation was found in HCT116 (MMR-) tumor xenografts compared with HCT116/3-6 (MMR+) tumor xenografts. Using a tumor regrowth assay after the 14-day drug treatment and a 4-day radiation therapy course (days 11-14 of IPdR), we found substantial radiosensitization in both HCT116 and HCT116/3-6 tumor xenografts. However, the sensitizer enhancement ratio (SER) was substantially higher in HCT116 (MMR-) tumor xenografts (1.48 at 2 Gy per fraction, 1.41 at 4 Gy per fraction), compared with HCT116/3-6 (MMR+) tumor xenografts (1.21 at 2 Gy per fraction, 1.20 at 4 Gy per fraction). No substantial systemic toxicity was found in the treatment groups.

CONCLUSIONS

These results suggest that IPdR-mediated radiosensitization can be an effective in vivo approach to treat "drug-resistant" MMR-deficient tumors as well as MMR-proficient tumors.

CHK1 and CHK2 are differentially involved in mismatch repair–mediated 6-thioguanine-induced cell cycle checkpoint responses

The DNA mismatch repair (MMR) system plays an important role in mediating a G2-M checkpoint arrest and subsequent cell death following treatment with a variety of chemotherapeutic agents. In this study, using 6-thioguanine (6-TG) as a mismatch-inducing drug, we examine the role of ataxia telangiectasia mutated (ATM)/CHK2 and ATM and Rad-3 related (ATR)/CHK1 signaling pathways in MMR-mediated cell cycle responses in MMR-proficient human colorectal cancer RKO cells. We show that, in response to 6-TG (3 μmol/L × 24 hours), activating phosphorylation of CHK1 at Ser317 [CHK1(pS317)] and CHK2 at Thr68 [CHK2(pT68)] are induced differentially during a prolonged course (up to 6 days) of MMR-mediated cell cycle arrests following 6-TG treatment, with CHK1(pS317) being induced within 1 day and CHK2(pT68) being induced later. Using chemical inhibitors and small interfering RNA of the signaling kinases, we show that a MMR-mediated 6-TG-induced G2 arrest is ATR/CHK1 dependent but ATM/CHK2 independent and that ATR/CHK1 signaling is responsible for both initiation and maintenance of the G2 arrest. However, CHK2(pT68) seems to be involved in a subsequent tetraploid G1 arrest, which blocks cells that escape from the G2-M checkpoint following 6-TG treatment. Furthermore, we show that CHK2 is hyperphosphorylated at later times following 6-TG treatment and the phosphorylation of CHK2 seems to be ATM independent but up-regulated when ATR or CHK1 is reduced. Thus, our data suggest that CHK1(pS317) is involved in a MMR-mediated 6-TG-induced G2 arrest, whereas CHK2(pT68) seems to be involved in a subsequent tetraploid G1-S checkpoint. The two signaling kinases seem to work cooperatively to ensure that 6-TG damaged cells arrest at these cell cycle checkpoints.

CHK1 and CHK2 are differentially involved in mismatch repair-mediated 6-thioguanine-induced cell cycle checkpoint responses

The DNA mismatch repair (MMR) system plays an important role in mediating a G2-M checkpoint arrest and subsequent cell death following treatment with a variety of chemotherapeutic agents. In this study, using 6-thioguanine (6-TG) as a mismatch-inducing drug, we examine the role of ataxia telangiectasia mutated (ATM)/CHK2 and ATM and Rad-3 related (ATR)/CHK1 signaling pathways in MMR-mediated cell cycle responses in MMR-proficient human colorectal cancer RKO cells. We show that, in response to 6-TG (3 micromol/L x 24 hours), activating phosphorylation of CHK1 at Ser317 [CHK1(pS317)] and CHK2 at Thr68 [CHK2(pT68)] are induced differentially during a prolonged course (up to 6 days) of MMR-mediated cell cycle arrests following 6-TG treatment, with CHK1(pS317) being induced within 1 day and CHK2(pT68) being induced later. Using chemical inhibitors and small interfering RNA of the signaling kinases, we show that a MMR-mediated 6-TG-induced G2 arrest is ATR/CHK1 dependent but ATM/CHK2 independent and that ATR/CHK1 signaling is responsible for both initiation and maintenance of the G2 arrest. However, CHK2(pT68) seems to be involved in a subsequent tetraploid G1 arrest, which blocks cells that escape from the G2-M checkpoint following 6-TG treatment. Furthermore, we show that CHK2 is hyperphosphorylated at later times following 6-TG treatment and the phosphorylation of CHK2 seems to be ATM independent but up-regulated when ATR or CHK1 is reduced. Thus, our data suggest that CHK1(pS317) is involved in a MMR-mediated 6-TG-induced G2 arrest, whereas CHK2(pT68) seems to be involved in a subsequent tetraploid G1-S checkpoint. The two signaling kinases seem to work cooperatively to ensure that 6-TG damaged cells arrest at these cell cycle checkpoints.

[Epidemiological survey on the infection of Paragonimus westermani in Jiangxi Province]

OBJECTIVE

To investigate Paragonimus westermani infection in the intermediate hosts and animal reservoivs in Jiangxi Province.

METHODS

Two forest farms in Jingan and Wanzai Counties and one town in Yushan County of Jiangxi Province were selected as pilots for epidemiological and retrospective survey. The intermediate hosts (snails, crabs) and reservoir hosts (cat, dog, civet cat, wildcat, etc.) were collected and examined. Data on the changes of ecological environment and people's behaviors were also collected.

RESULTS

The average infection rate in Semisulcospira libertina and Sinopotamon spp. was 0.21% and 54.3% respectively, and that of reservoir hosts was 5.6%. Compared with those in 20 years ago, the infection rate in Sinopotamon spp. decreased considerably.

CONCLUSION

The three areas are still endemic for P. westermani with lower prevalence than before possibly due to the change of ecological environment.

Alteration of cellular phenotype and responses to oxidative stress by manganese superoxide dismutase and a superoxide dismutase mimic in RWPE-2 human prostate adenocarcinoma cells

To study biologic effects of increased manganese superoxide dismutase (MnSOD) on cell behavior, we overexpressed MnSOD in a human prostate cancer cell line RWPE-2 by cDNA transfection. Stable transfectants of MnSOD showed a two- to threefold increase in MnSOD protein and enzymatic activity and a decrease in growth rate with prolonged cell population doubling times. Western blot analysis showed a 1.5- to twofold increase in the cyclin-dependent kinase inhibitor p21(Waf1) in MnSOD transfectants. Overexpression of MnSOD resulted in a seven- to eightfold increase in reduced glutathione (GSH), 18- to 26-fold increase in oxidized glutathione (GSSG), and a two- to threefold decrease in the ratio of GSH to GSSG. MnSOD-overexpressing cells showed an increase in sensitivity to the cytotoxicity of buthionine sulfoximine, a glutathione-depleting agent, and vitamin C, but a decrease in sensitivity to sodium selenite. Treatment with a superoxide dismutase (SOD) mimic MnTMPyP resulted in similar effects of MnSOD overexpression on cell responses to vitamin C and selenium. These data demonstrate that overexpression of MnSOD or treatment with SOD mimics can result in antioxidant or prooxidant effects in cells, depending on the presence of other antioxidants and prooxidants. MnSOD also has redox regulatory effects on cell growth and gene expression. These findings suggest that MnSOD and SOD mimics have the potential for cancer prevention or treatment.

Short Communication: Effects of Feeding Level on Energy Concentration in Grass Silage-Based Diets Offered to Dairy Cattle

Twelve grass silages were offered to sheep as a sole diet at maintenance and to lactating dairy cows ad libitum as mixed silage and concentrates diets (n = 13 diets). Fecal and urinary energy outputs were measured for silages and mixed diets. Digestible energy (DE) and metabolizable energy (ME) concentrations for mixed diets with sheep at maintenance were estimated based on the silage dry matter (DM) proportion obtained in the cattle trials, the silage energy utilization values (methane energy-predicted) determined using sheep, and tabulated concentrate values. A comparison of dietary mean data (n = 13) indicated that concentrations of ME (P < 0.01) and DE (P < 0.001) in mixed diets were significantly lower for cows at production feeding level than for sheep at maintenance. The reductions were proportionately 0.015 and 0.020 with each unit increase in feeding level above maintenance, respectively. These ME and DE data were also used to evaluate the feeding level correction factors previously proposed by Van Es (1975) (ME, 0.018) and Yan et al. (2002) (ME, 0.016; DE, 0.025) using the mean square prediction error technique. The ME correction factor proposed by Yan et al. (2002) had a greater prediction accuracy than that proposed by Van Es (1975) for the prediction of ME concentration in mixed diets offered to dairy cattle at production feeding level.

Prediction of nutritive values in grass silages: II. Degradability of nitrogen and dry matter using digestibility, chemical composition, and fermentation data1

One hundred thirty-six perennial rye-grass silages with wide variations in quality were evaluated for N and DM degradability in three beef steers offered grass silage of medium quality ad libitum. The silages were incubated in the rumen of each animal in triplicate for 0, 6, 12, 24, 48, and 72 h, respectively. The disappearance rates of N or DM were used to calculate the readily soluble fraction ("a" value), potentially degradable fraction ("b" value), and the fractional degradation rate of"b" ("c" value). The effective degradability (P) of N or DM was then estimated assuming a ruminal outflow rate of 0.02, 0.05, or 0.08/h (P0.02, P0.05, or P0.08). The objective was to use these data to develop prediction equations for N and DM degradability in grass silages. There were considerable variations in "a," "b," and "c" values and the P0.02, P0.05, or P0.08 of N and DM (e.g., the P0.02 of N ranged from 75.0 to 93.4% and the P0.02 of DM from 51.5 to 82.5%). The P0.02, P0.05, or P0.08 of N and DM were negatively related (P < 0.001) to ADF, NDF, and lignin concentrations but positively related (P < 0.001) to protein fractions (CP, soluble CP, and true protein concentrations) and digestibility of DM, OM, GE, CP, and NDF and digestible OM in the total DM (measured with sheep). The N and DM degradability data were also positively related to silage lactic acid concentration, but the relationships between DM degradability data and pH, ammonia N/total N, and VFA concentration in silages were negative (P < 0.05). Several sets of prediction equations (linear and multiple) were thus developed for N and DM degradability using CP or NDF concentration, "a" value or digestibility data as primary predictors, together with or without other nutrient concentration and silage fermentation variables. All these relationships were highly significant (P < 0.001), and each predictor had a significant effect on the relationship (P < 0.05). The R2 values in multiple regression for N and DM degradability were generally over 0.70 and higher than in linear regression equations. Four equations were also developed to convert N and DM degradability at a given ruminal outflow rate, predicted using the above-mentioned equations, to their counterparts at any ruminal outflow rate (0.02 to 0.10/h), respectively.

A conical piezoelectric transducer with integral sensor as a self-calibrating acoustic emission energy source

The experimental results of a conical piezoelectric transducer with integral backing sensor as a self-calibrating simulated acoustic emission (SAE) energy source are presented. It has been shown that there is a negative linear relationship between the energy of SAE signal detected by the backing sensor and the relative strength (signal energy) of SAE source in the structure detected by a reference sensor under different transducer-to-structure coupling efficiencies, with AC drives of the same wave packet, frequency and peak amplitude to excite the conical transducer as a SAE source at all the investigated frequencies over the frequency range of interest in AE measurements (nominally from 50 kHz to around 1 MHz). This should enable the relative strength of the SAE source in a structure to be determined using the SAE measurement from the backing sensor for the selected electrical inputs to the conical transducer, and hence to remove the concerns about inconsistent transducer-to-structure coupling affecting the relative strength of the SAE source for calibration.

Experimental and simulation study of neon collision dynamics with a 1-decanethiol monolayer

A study of the energy accommodation of neon colliding with a crystalline self-assembled 1-decanethiol monolayer adsorbed on Au(111) is presented. The intensity and velocity dependencies of the scattered neon as a function of incident angle and energy were experimentally measured. Scattering calculations show good agreement with these results, which allows us to examine the detailed dynamics of the energy and momentum exchange at the surface. Simulation results show that interaction times are, at most, a few picoseconds. Even for these short times, energy exchange with the surface, both normal and in-plane, is very rapid. An important factor in determining the efficiency of energy exchange is the location at which the neon collides with the highly corrugated and structurally dynamic unit cell. Moreover, our combined experimental and theoretical results confirm that these are truly surface collisions in that neon penetration into the organic boundary layer does not occur, even for the highest incident energies explored, 560 meV.

Role of MutSalpha in the recognition of iododeoxyuridine in DNA

We have previously demonstrated that both the MLH1 and MSH2 status impact the DNA levels of the halogenated thymidine (dThd) analogues iododeoxyuridine (IdUrd) and bromodeoxyuridine (BrdUrd), and thereby radiosensitization induced by these analogues, indirectly implicating both mismatch repair (MMR) proteins in the removal of these bases from DNA. More recent data from our group demonstrate that base excision repair (BER) also impacts IdUrd-DNA levels, supporting a role for the BER pathway in IdUrd removal as well. In this study, we have examined more direct interactions between the MSH2 protein and the processing of IdUrd incorporated in DNA. Our data demonstrate that the MutSalpha (MSH2/MSH6) complex binds specifically to DNA containing an IdUrd-G mismatch, using both purified human MutSalpha as well as nuclear extracts from Msh2-proficient and-deficient mouse cell lines. MutSalpha binding to a IdUrd-G is better recognized than a G-T mismatch in the same sequence context. In addition, MSH2 protein can be found colocalized with IdUrd-DNA using confocal microscopy in G(1) synchronized cells after treatment with IdUrd. Consistent with our recent publication, coadministration of IdUrd and a chemical inhibitor of BER, methoxyamine (MX), also increases the extent of MSH2 nuclear colocalization with IdUrd. Furthermore, we show that the extent of MSH2 colocalization with IdUrd in G(1)-synchronized human tumor cells varies with MLH1 status, suggesting a role for the MLH1 protein in stabilizing the interaction between the MSH2 protein and DNA containing IdUrd. These data, both in vitro and in vivo, suggest direct involvement of MSH2 in processing IdUrd in DNA.

Alternatives to Linear Analysis of Energy Balance Data from Lactating Dairy Cows

The current energy requirements system used in the United Kingdom for lactating dairy cows utilizes key parameters such as metabolizable energy intake (MEI) at maintenance (MEm), the efficiency of utilization of MEI for 1) maintenance, 2) milk production (kl), 3) growth (kg), and the efficiency of utilization of body stores for milk production (kt). Traditionally, these have been determined using linear regression methods to analyze energy balance data from calorimetry experiments. Many studies have highlighted a number of concerns over current energy feeding systems particularly in relation to these key parameters, and the linear models used for analyzing. Therefore, a database containing 652 dairy cow observations was assembled from calorimetry studies in the United Kingdom. Five functions for analyzing energy balance data were considered: straight line, two diminishing returns functions, (the Mitscherlich and the rectangular hyperbola), and two sigmoidal functions (the logistic and the Gompertz). Meta-analysis of the data was conducted to estimate kg and kt. Values of 0.83 to 0.86 and 0.66 to 0.69 were obtained for kg and kt using all the functions (with standard errors of 0.028 and 0.027), respectively, which were considerably different from previous reports of 0.60 to 0.75 for kg and 0.82 to 0.84 for kt. Using the estimated values of kg and kt, the data were corrected to allow for body tissue changes. Based on the definition of kl as the derivative of the ratio of milk energy derived from MEI to MEI directed towards milk production, MEm and kl were determined. Meta-analysis of the pooled data showed that the average kl ranged from 0.50 to 0.58 and MEm ranged between 0.34 and 0.64 MJ/kg of BW0.75 per day. Although the constrained Mitscherlich fitted the data as good as the straight line, more observations at high energy intakes (above 2.4 MJ/kg of BW0.75 per day) are required to determine conclusively whether milk energy is related to MEI linearly or not.

[Biological characteristics of the juvenile Paragonimus westermani]

AIM

To observe the biological characteristics of the juvenile of Paragonimus westermani.

METHODS

Kunmin strain mice and Wistar rats inoculated orally with 100-150 metacercariae of Paragonimus westermani were autopsied 10-30 days and 80-580 days after infection, respectively. Life-span, survival time in dead hosts or physiological saline at 5 degrees C to 8 degrees C and invasiveness of juveniles to new hosts were detected by host transfer.

RESULTS

All the worms recovered from the mice and rats were stunted juveniles. The worm detection rates in the mice and rats were 19.3% and 22.2%-37.5%, respectively. The life-span of the juveniles was rather long, being not limited by the life-span of a host. Host transfer could prolong longevity and preserve invasiveness. The juveniles recovered from dead mice still possess strong vitality and invasiveness.

CONCLUSION

The juvenile of P. westermani is an infective stage, having strong vitality and invasiveness.

DNA mismatch repair (MMR) mediates 6-thioguanine genotoxicity by introducing single-strand breaks to signal a G2-M arrest in MMR-proficient RKO cells

PURPOSE

The DNA mismatch repair (MMR) system plays an important role in mediating cell death after treatment with various types of chemotherapeutic agents, although the molecular mechanisms are not well understood. In this study, we sought to determine what signal is introduced by MMR after 6-thioguanine (6-TG) treatment to signal a G(2)-M arrest leading to cell death.

EXPERIMENTAL DESIGN

A comparison study was carried out using an isogenic MMR(+) and MMR(-) human colorectal cancer RKO cell system, which we established for this study. Cells were exposed to 6-TG (3 micro M x 24 h) and then harvested daily for the next 3-6 days for growth inhibition assays. Cell cycle effects were determined by flow cytometry, and DNA strand breaks were measured using pulsed-field gel electrophoresis and alkaline Comet assays.

RESULTS

We first established MMR(+) RKO cell lines by transfection of human MutL homologue 1 (hMLH1) cDNA into the hMLH1-deficient (MMR(-)) RKO cell line. The ectopically expressed hMLH1 protein restored a MMR-proficient phenotype in the hMLH1(+) transfectants, showing a significantly increased and prolonged G(2)-M arrest followed by cell death after 6-TG exposure, compared with the vector controls. The MMR-mediated, 6-TG-induced G(2)-M arrest started on day 1, peaked on day 3, and persisted to day 6 after 6-TG removal. We found that DNA double-strand breaks were comparably produced in both our MMR(+) and MMR(-) cells, peaking within 1 day of 6-TG treatment. In contrast, single-strand breaks (SSBs) were more frequent and longer lived in MMR(+) cells, and the duration of SSB formation was temporally correlated with the time course of 6-TG-induced G(2)-M arrest.

CONCLUSIONS

Our data suggest that MMR mediates 6-TG-induced G(2)-M arrest by introducing SSBs to signal a persistent G(2)-M arrest leading to enhanced cell death.

Fouling of offshore structures in China--a review

Biofouling on ships' hulls and other man-made structures is a major economic and technical problem around the world. In recent decades, the development and growth of the offshore oil and gas industry has led to increased interest in, and studies on marine fouling in offshore regions. This paper reviews the effects of marine fouling on offshore structures, the development of offshore fouling studies in China, and the characteristics of marine fouling in relevant areas. Future research strategies are also proposed.

Evaluation of different energy feeding systems with production data from lactating dairy cows offered grass silage-based diets

A set of data from 838 lactating dairy cows, drawn from 12 long-term feeding studies (at least 8 wk/period), was used to evaluate the energy feeding systems for dairy cows currently adopted in Australia, France, The Netherlands, the United Kingdom, and the United States. The animals were offered mixed diets of concentrates, forage [grass silages (n = 33) and corn silages (n = 5)] ad libitum. Data used in the present evaluation were either measured [dry matter (DM) intake, milk production and live weight], measured/estimated [dietary metabolizable energy (ME) concentration] or estimated [milk energy output and live weight change (LWC)]. The mean-square prediction error (MSPE) was used for the evaluation. Total ME intake, milk yields, and LWC varied from 91 to 338 MJ/d, 7.7 to 48.9, and -1.23 to 1.73 kg/d, respectively. Australian and French systems predicted total energy requirement and milk yield relatively well, while British, Dutch and American systems underpredicted total energy requirement by proportionately 0.06, 0.04, and 0.03, respectively; and overpredicted milk yield by 0.09, 0.06, and 0.04. The Agricultural and Food Research Council (AFRC) each produced a relatively larger error of the bias (predicted - actual data) over the total MSPE for ME requirement and milk yield and a relatively smaller error of random than other systems. However, an addition of proportionately 0.05 to the total predicted ME requirement of AFRC, as suggested in this system and currently used in the UK, indicated the prediction accuracy of ME requirement and milk yield is similar to Australian and French systems. Nevertheless, all the systems had a poor prediction of LWC. For each system, the total prediction error (total MSPE) was mainly derived from the line (slope; 0.49 to 0.64 of total MSPE), while less derived from the random (0.20 to 0.48 of total MSPE), indicating a large variation between the predicted and actual LWC existed among individual cows. The residual plots of the residual differences in LWC against predicted LWC revealed that the prediction error was greater with increasing LWC. It is concluded that Australian and French systems have a better prediction of total energy requirement and milk yield than other systems, and LWC is an inappropriate indicator of energy balance in lactating dairy cows.

A novel mechanism for the regulation of osteoblast differentiation: transcription of periostin, a member of the fasciclin I family, is regulated by the bHLH transcription factor, twist

Periostin is a secreted protein that is highly expressed in early osteoblastic cells in vitro and in periosteum and periodontal ligament tissues in vivo. It is known that periostin supports cellular adhesion and spreading in vitro. Although, the mechanisms of transcriptional regulation of periostin are poorly understood, gene-profiling data have revealed that overexpression of Twist, a basic helix-loop-helix (bHLH) transcription factor, resulted in increased periostin expression as validated by Northern blot and reverse transcription-polymerase chain reaction (RT-PCR) analyses. Twist is an important transcription factor for cell type determination and differentiation and has been shown to play an important regulatory role in early osteogenesis. In situ hybridization of mouse calvarial bones indicated that periostin and Twist mRNA are co-localized at the osteogenic fronts of calvarial bones. To characterize the 5' flanking region of the periostin gene, primer extension was carried out to identify the transcription start site, and DNA sequence analysis confirmed the presence of a 'Twist-box' response element. The results of electrophoretic mobility shift assay (EMSA) using nuclear extracts of MC3T3-E1 cells revealed that Twist bound to the Twist-box sequence on the periostin promoter. In vivo footprinting experiments using ligation-mediated PCR (LM-PCR) indicated that the Twist-box sequence was protected in undifferentiated MC3T3-E1 preosteoblasts but not in differentiated MC3T3-E1 osteoblasts. To determine whether Twist actually regulates the periostin expression, 293T cells were transiently co-transfected with the periostin promoter construct and the human Twist expression vector. Reporter analysis indicated that the periostin promoter activities were enhanced by overexpression of Twist. These data suggest that Twist can bind to the periostin promoter in undifferentiated preosteoblasts and up-regulate periostin expression, consistent with the up-regulation of periostin expression by Twist as observed in the gene-profiling data.

[Experimental studies on development of Paragonimus heterotremus in rats]

AIM

To study the polymorphism of the development of Paragonimus heterotremus in rats and to ascertain the host nature of the rat.

METHODS

SD and Wistar rats were each infected orally with 100 metacercariae of P. heterotremus. The distribution and development of the worms recovered from rats 14-156 days after infection were observed.

RESULTS

Thirty days after infection, reproductive organs appeared in the worms recovered from the body cavities. Seventy days after infection, worm-cysts were found in the lungs, livers and pleural wall, the worms in the cysts matured but the worms detected in the muscles were still stunted on the 156 th day after infection.

CONCLUSION

Rat is the definitive host and paratenic host of P. heterotremus. The development of P. heterotremus is polymorphic.

[A case-control study on risk factors for advanced schistosomiasis japonica]

OBJECTIVE

To investigate risk factors for the development of advanced schistosomiasis.

METHODS

The case-control study was designed with a match of 1:1 and 1:2. Healthy persons and chronic schistosomiasis patients were used as control. Each group was composed of 213 cases. Items investigated included: history of schistosomiasis and treatment, exposure to the contaminated water, social-economical condition and nutritional status, other concomitant diseases. Cellular and humoral immunity, HBVMs and ABO blood groups were also detected. Statistical analysis was performed by 1:1 and 1:2 matched single and stepwise conditional logistic regression analysis with SAS software.

RESULTS

By stepwise conditional logistic regression analysis, it was revealed that number of schistosomiasis examination (OR = 1.168-1.311), interval from first infection to last treatment(OR = 1.142), interval from first infection to this investigation (OR = 1.089), HBsAg+ (OR = 4.683-10.759), HBcAb+ (OR = 2.873), HBsAg+ + HBeAb+ + HBcAb+ (OR = 7.64) were risk factors of developing advanced schistosomiasis. The average living space and cellular immunity were lower in advanced schistosomiasis patients than others. No association was found between advanced schistosomiasis and ABO blood groups.

CONCLUSION

The development of advanced schistosomiasis is associated with repeated infections, and delayed or incomplete treatment. Combined infection with hepatitis B, poor socio-economic conditions and impaired cellular immunity may increase the pathogenetic risk of schistosomiasis.

Inhibition of human osteoblast marker gene expression by retinoids is mediated in part by insulin-like growth factor binding protein-6

All-trans -retinoic acid (atRA) inhibits osteoblast marker gene expression and markedly increases expression of insulin-like growth factor binding protein-6 (IGFBP-6) in human osteoblasts. The possibility that IGFBP-6 inhibits the osteoblast phenotype and also mediates the inhibitory effect of atRA on osteoblast marker gene expression was explored using an antisense approach. Stable human osteoblast-like osteosarcoma SaOS-2 cells were prepared that expressed antisense IGFBP-6 RNA under basal and atRA-stimulated conditions. The functional expression of IGFBP-6 antisense RNA was confirmed by measuring IGFBP-6 mRNA by Northern analysis or by measuring IGFBP-6 protein in the conditioned media (CM) by radioimmunoassay. Antisense clones produced less mRNA and had less IGFBP-6 protein in the CM than controls. IGFBP-6 protein levels in the CM were inversely correlated with alkaline phosphatase (ALP) activity, whereas IGFBP-3 and IGFBP-4 protein levels were not. We reasoned that atRA would have little or no effect on ALP activity in IGFBP-6 antisense clones if atRA mediated its inhibitory effects by recruiting IGFBP-6. In the majority of IGFBP-6 antisense clones with the lowest IGFBP-6 mRNA and CM protein levels and only modest changes in other IGF system components, atRA did not significantly decrease ALP activity. These findings provide evidence that atRA recruits IGFBP-6 to inhibit the human osteoblast phenotype.

Loss of DNA mismatch repair imparts defective cdc2 signaling and G(2) arrest responses without altering survival after ionizing radiation

Our previous data demonstrated that cells deficient in MutL homologue-1 (MLH1) expression had a reduced and shorter G(2) arrest after high-dose-rate ionizing radiation (IR), suggesting that the mismatch re pair (MMR) system mediates this cell cycle checkpoint. We confirmed this observation using two additional isogenetically matched human MLH1 (hMLH1)-deficient and -proficient human tumor cell systems: human ovarian cancer cells, A2780/CP70, with or without ectopically expressed hMLH1, and human colorectal carcinoma cells, RKO, with or without azacytidine treatment to reexpress hMLH1. We also examined matched MutS homologue-2 (hMSH2)-deficient and -proficient human endometrial carcinoma HEC59 cell lines to determine whether hMSH2, and MMR in general, is involved in IR-related G(2) arrest responses. As in MLH1-deficient cells, cells lacking hMSH2 demonstrated a similarly altered G(2) arrest in response to IR (6 Gy). These differences in IR-induced G(2) arrest between MMR-proficient and -deficient cells were found regardless of whether synchronized cells were irradiated in G(0)/G(1) or S phase, indicating that MMR indeed dramatically affects the G(2)-M checkpoint arrest. However, unlike the MMR-dependent damage tolerance response to 6-thioguanine exposures, no significant difference in the clonogenic survival of MMR-deficient cells compared with MMR-proficient cells was noted after high-dose-rate IR. In an attempt to define the signal transduction mechanisms responsible for MMR-mediated G(2) arrest, we examined the levels of tyrosine 15 phosphorylation of cdc2 (phospho-Tyr15-cdc2), a key regulator of the G(2)-M transition. Increased phospho-Tyr15-cdc2 levels were observed in both MMR-proficient and -deficient cell lines after IR. However, the levels of the phospho-Tyr15-cdc2 rapidly decreased in MMR (hMLH1 or hMSH2)-deficient cell lines at times coincident with progress from the IR-induced G(2) arrest through M phase. Thus, differences in the levels of phospho-Tyr15-cdc2 after high-dose-rate IR correspond temporally with the observed differences in the IR-induced G(2) arrest, suggesting that MMR proteins may exert their effect on IR-induced G(2) arrest by signaling the cdc2 pathway. Although MMR status does not significantly affect the survival of cells after high-dose-rate IR, it seems to regulate the G(2)-M checkpoint and might affect overall mutation rates.

Intracerebral haemorrhage and Qigong

We report on a 65-year-old woman who presented with acute right-sided weakness because of an intracerebral (thalamic) haemorrhage. As a Qigong enthusiast with a long-standing history of hypertension, she developed a stroke syndrome soon after practising Qigong one morning. Following neurological recovery, the patient exhibited erratic blood pressure responses while practising Qigong, despite the fact that resting blood pressure was normal. The haemodynamic responses to exercise are discussed and a review of the therapeutic implications of practising Qigong is presented.

Regulation of osteoclastogenesis and RANK expression by TGF-beta1

Transforming growth factor-beta (TGF-beta) has been shown to both inhibit and to stimulate bone resorption and osteoclastogenesis. This may be due, in part, to differential effects on bone marrow stromal cells that support osteoclastogenesis vs. direct effects on osteoclastic precursor cells. In the present study, we used the murine monocytic cell line, RAW 264.7, to define direct effects of TGF-beta on pre-osteoclastic cells. In the presence of macrophage-colony stimulating factor (M-CSF) (20 ng/ml) and receptor activator of NF-kappaB ligand (RANK-L) (50 ng/ml), TGF-beta1 (0.01-5 ng/ml) dose-dependently stimulated (by up to 120-fold) osteoclast formation (assessed by the presence of tartrate-resistant acid phosphatase (TRAP) positive multinucleated cells and expression of calcitonin and vitronectin receptors). In addition, TGF-beta1 also increased steady state RANK mRNA levels in a time- (by up to 3.5-fold at 48 h) and dose-dependent manner (by up to 2.2-fold at 10 ng/ml). TGF-beta1 induction of RANK mRNA levels was present both in undifferentiated RAW cells as well as in cells that had been induced to differentiate into osteoclasts by a 7-day treatment with M-CSF and RANK-L. Using a fluorescence-labeled RANK-L probe, we also demonstrated by flow cytometry that TGF-beta1 resulted in a significant increase in the percentage of RANK+ RAW cells (P < 0.05), as well as an increase in the fluorescence intensity per cell (P < 0.05), the latter consistent with an increase in RANK protein expression per cell. These data thus indicate that TGF-beta directly stimulates osteoclastic differentiation, and this is accompanied by increased RANK mRNA and protein expression.

Inhibition of egg hatching success and larvae survival of the scallop, Chlamys farreri, associated with exposure to cells and cell fragments of the dinoflagellate Alexandrium tamarense

We report an apparently novel toxic effect of the dinoflagellate Alexandrium tamarense, manifested by inhibition of the egg hatching success of the scallop, Chlamys farreri. The hatching rate of C. farreri approached only 30% of controls when its fertilised eggs were exposed for 36h to A. tamarense cells or cellular fragments at a concentration of 100 cells/ml, and the hatching rate was just 5% after exposure to A. tamarense of 500 cells/ml. Similar exposures of the fertilised scallop eggs to two other algal species, the diatom Phaeodactylum tricornutum and the raphidophyte Heterosigma carterae, resulted in no such toxicity or inhibitory effects. Likewise, exposure of eggs to standard STX toxin, as well as to A. tamarense cell contents (supernant of re-suspended algal cells following ultrasonication and centrifugation), did not elicit this inhibitory response. However, exposure of the scallop eggs to cell cultures, intact algal cells, or cell fragments of A. tamarense produced marked toxicity. The alga also influenced larvae at early D-shape stage of scallop. The survival rates began to decrease significantly after exposed for 6 days at concentration of 3000 cells/ml and above; no larvae could survive after 14-day exposure to A. tamarense at 10,000 cells/ml or 20-day at 5000 cells/ml. The results indicated the production of novel substances from A. tamarense which can cause adverse effects on egg hatching and survival of the scallop larvae. The experiment also found that the developmental stages before blastula was the developmental period most sensitive to the A. tamarense toxin(s) and the alga at early exponential stage had the strongest effect on egg hatching comparing with other growth phases. The adverse effect of A. tamarense on early development of scallops may cause decline of shellfish population and may have further impact on marine ecosystem.

A zebrafish vitellogenin gene (vg3) encodes a novel vitellogenin without a phosvitin domain and may represent a primitive vertebrate vitellogenin gene

By analysis of zebrafish EST (expressed sequence tag) clones from an adult cDNA library, we have identified 44 clones, about 11% of the adult EST clones, encoding vitellogenins. These vitellogenin EST clones have been derived from at least seven distinct vitellogenin genes. One of the largest vitellogenin cDNA clones, vg3, and its 5' extended clone isolated by 5' RACE (rapid amplification of cDNA ends)-PCR, have been sequenced completely. The deduced complete sequence includes a predicted mature vitellogenin of 1233 amino acids and a truncated signal peptide of 18 amino acids. Interestingly, the predicted vitellogenin has no polyserine phosvitin domain. The lack of the phosvitin domain was confirmed by isolation and sequencing of the vg3 genomic region. Phylogenetic analysis indicates that the phosvitinless vitellogenin is an intermediate between invertebrate vitellogenins and all known vertebrate vitellogenins, and thus may represent a primitive vertebrate vitellogenin. Like other vitellogenins in vertebrates, the phosvitinless vitellogenin is also synthesized mainly in the liver and weakly in the intestine.

The role of cellular glutathione peroxidase redox regulation in the suppression of tumor cell growth by manganese superoxide dismutase

Manganese-containing superoxide dismutase (MnSOD) is an essential primary antioxidant enzyme that converts superoxide radical to hydrogen peroxide and molecular oxygen within the mitochondrial matrix. Cytosolic glutathione peroxidase (GPX) converts hydrogen peroxide into water. MnSOD is reduced in a variety of tumor types and has been proposed to be a new kind of tumor suppressor gene, but the mechanism(s) by which MnSOD suppresses malignancy is unclear. According to the enzymatic reactions catalyzed by MnSOD and cytosolic GPX, change in the cellular redox status, especially change attributable to accumulation of hydrogen peroxide or other hydroperoxides, is a possible reason to explain the suppression of tumor growth observed in MnSOD-overexpressing cells. To test this possible mechanism, we transfected human cytosolic GPX cDNA into human glioma cells overexpressing MnSOD. The results showed that GPX overexpression not only reversed the tumor cell growth inhibition caused by MnSOD overexpression but also altered the cellular contents of total glutathione, reduced glutathione, oxidized glutathione, and intracellular reactive oxygen species. Overexpression of GPX also inhibited degradation of the inhibitory subunit alpha of nuclear factor-KB. These results suggest that hydrogen peroxide or other hydroperoxides appear to be key reactants in the tumor suppression by MnSOD overexpression, and growth inhibition correlates with the intracellular redox status. This work suggests that manipulations that inhibit peroxide removal should enhance the tumor suppressive effect of MnSOD overexpression.

Antioxidant enzyme expression and reactive oxygen species damage in prostatic intraepithelial neoplasia and cancer

BACKGROUND

Oxidative stress results in damage to cellular structures and has been linked to many diseases, including cancer. The authors sought to determine whether the expression of three major antioxidant enzymes, copper-zinc superoxide dismutase (SOD1), manganese superoxide dismutase (SOD2), and catalase, was altered in human prostate carcinoma and its likely precursor, high grade prostatic intraepithelial neoplasia (PIN). The level of reactive oxygen species damage was evaluated by measuring the expression of the DNA adduct 8-hydroxydeoxyguanosine.

METHODS

The authors evaluated the tissue expression of the antioxidant enzymes in prostate carcinoma by immunohistochemistry, immunogold electron microscopy, and enzymatic assay. The polymerase chain reaction was used to amplify and screen tissue specimens for the genes of SOD1, SOD2, and extracellular SOD (SOD3). Matched paraffin embedded tissue sections were evaluated by RNA in situ hybridization for expression of SOD1 and immunohistochemically for the DNA adduct 8-hydroxydeoxyguanosine.

RESULTS

All prostatic tissues, including cancer, displayed immunoreactivity for the three antioxidant enzymes in epithelial cells, with no staining of the stroma, inflammatory cells, or endothelial cells. The number of immunoreactive cells was greater in benign epithelium than in PIN and cancer for each enzyme. The mean percentage and intensity of immunoreactive cells was greatest for SOD2, intermediate for SOD1, and lower for catalase. Staining in cancer was heterogeneous. Immunogold ultrasound studies revealed strong mitochondrial labeling for SOD2, which was greater in benign epithelium than in cancer; SOD1 labeling was invariably weaker, with nuclear labeling in benign epithelium and cytoplasmic labeling in cancer cells. There was no difference in enzyme activity for the three antioxidant enzymes between benign epithelium and cancer. No mutations were found in the 5 exons of SOD1, 5 exons of SOD2, and 3 exons of SOD3, except for 3 of 20 cases with polymorphisms for exon 3 of SOD1. Intense nuclear immunoreactivity for 8-hydroxydeoxyguanosine was present in fewer than 3% of epithelial cells, with no apparent differences among benign epithelium, PIN, and cancer.

CONCLUSIONS

SOD1, SOD2, and catalase had lower expression in PIN and prostate carcinoma than in benign epithelium. The number of immunoreactive cells in PIN was similar to cancer, indicating that these are closely related. Enzyme activities were variable, with no difference between benign epithelial cells and cancer, although this lack of change in enzyme activity could have been due to the presence of contaminating benign cells within the cancer specimens. The results of reactive oxygen species damage were found only in the epithelium and not in the stroma. Expression of the DNA adduct 8-hydroxydeoxyguanosine was present in fewer than 3% of cells, with no apparent differences among benign epithelium, PIN, and cancer. These findings suggest that oxidative stress is an early event in carcinogenesis.

[Clinical analysis of 13 infected total knee replacements]

OBJECTIVE

To investigate the cause, treatment and its result of infected total knee replacements (TKRs).

METHODS

Between 1987 and 1999, 13 infected TKRs in 13 patients were treated with surgical debridement and one-stage or two-stage reimplantation. The preoperative average ROM of knees was 55 degrees and the average Hospital for Special Surgery (HSS) knee score was 36.5 points. Clinical results were evaluated after average follow-up for 3 years and 5 months. We analyzed the factors for TKR infection.

RESULTS

No recurrent infection was noted, and pain was significantly alleviated in all patients. The average ROM of knees was 85 degrees and the average HSS knee score was 73.5 points.

CONCLUSIONS

The high risk factors for TKR infection are rheumatoid arthritis, steroid administration, associated diabetes mellitus, hinged prosthesis and previous knee surgery. Early surgical debridement with intravenous antibiotics is necessary as soon as deep infection is detected. Two-stage reimplantation is more effective in eradicating deep infection than single debridement or one-stage reimplantation.

Comparison of effects of two polymorphic variants of manganese superoxide dismutase on human breast MCF-7 cancer cell phenotype

Two polymorphic variants of manganese superoxide dismutase (MnSOD), with either Ile or Thr at amino acid 58, (Ile58MnSOD or Thr58MnSOD), have been found in the human population. The MnSOD activity of these two variants and their effects on the malignant phenotype of human breast cancer MCF-7 cells were compared. It was demonstrated that MnSOD-overexpressing clones obtained from transfection of the two MnSOD cDNAs into MCF-7 cells had increased MnSOD immunoreactive protein and increased MnSOD activity. Cells overexpressing Ile58MnSOD had 3-fold higher MnSOD activity than cells overexpressing Thr58MnSOD in vivo at an equal MnSOD protein level. Tumor-suppressive effects of MnSOD-overexpressing cells were indicated by: (a) decreased plating efficiency; (b) elongated cell population doubling time; (c) lower clonogenic fraction in soft agar; and (d) complete inhibition or delayed onset of tumor formation in nude mice. When compared on the same activity basis, the suppressive effects of Ile58MnSOD were similar to those of Thr58MnSOD. However, far more Thrs58MnSOD protein was required to obtain the same amount of MnSOD activity, making the Thr58MnSOD far less effective. A dose-response suppressive effect was observed when the increase of MnSOD activity was moderate. We conclude that MnSOD is a tumor suppressor in human breast cancer, but the Thr58 form of the protein is a much less effective tumor suppressor than the Ile58 form of the protein.

Expression of superoxide dismutases, catalase, and glutathione peroxidase in glioma cells

Four primary antioxidant enzymes were measured in both human and rat glioma cells. Both manganese-containing superoxide dismutase (MnSOD) and copper-zinc-containing superoxide dismutase (CuZnSOD) activities varied greatly among the different glioma cell lines. MnSOD was generally higher in human glioma cells than in rat glioma cells and relatively higher than in other tumor types. High levels of MnSOD in human glioma cells were due to the high levels of expression of MnSOD mRNA and protein. Heterogeneous expression of MnSOD was present in individual glioma cell lines and may be due to subpopulations or cells at different differentiation stages. Less difference in CuZnSOD, catalase, or glutathione peroxide was found between human and rat glioma cells. The human glioma cell lines showed large differences in sensitivity to the glutathione modulating drugs 1,3-bis (2-chloroethyl)-1-nitrosourea (BCNU) and buthionine sulfoximine (BSO). A good correlation was found between sensitivity to BCNU and the activities of catalase in these cell lines. Only one cell line was sensitive to BSO and this line had low CuZnSOD activity.

Assembly of a complete zebrafish mitochondrial 16S rRNA gene from overlapping expressed sequence tags

A complete zebrafish mitochondrial 16S ribosomal RNA gene was assembled from our existing zebrafish EST clones by aligning them with the carp mitochondria 16S rRNA sequence. The overall homology between our assembled zebrafish mt 16S rRNA and the carp mt 16S rRNA is 83.5%. As the number of zebrafish ESTs grows, the assembly of more full-length cDNA sequences from overlapping EST data could be expected.

Faithful expression of green fluorescent protein (GFP) in transgenic zebrafish embryos under control of zebrafish gene promoters

Although the zebrafish has become a popular model organism for vertebrate developmental and genetic analyses, its use in transgenic studies still suffers from the scarcity of homologous gene promoters. In the present study, three different zebrafish cDNA clones were isolated and sequenced completely, and their expression patterns were characterized by whole-mount in situ hybridization as well as by Northern blot hybridization. The first clone encodes a type II cytokeratin (CK), which is specifically expressed in skin epithelia in early embryos and prominently expressed in the adult skin tissue. The second clone is muscle specific and encodes a muscle creatine kinase (MCK). The third clone, expressed ubiquitously in all tissues, is derived from an acidic ribosomal phosphoprotein P0 (arp) gene. In order to test the fidelity of zebrafish embryos in transgenic expression, the promoters of the three genes were isolated using a rapid linker-mediated PCR approach and subsequently ligated to a modified green fluorescent protein (gfp) reporter gene. When the three hybrid GFP constructs were introduced into zebrafish embryos by microinjection, the three promoters were activated faithfully in developing zebrafish embryos. The 2.2-kb ck promoter was sufficient to direct GFP expression in skin epithelia, although a weak expression in muscle was also observed in a few embryos. This pattern of transgenic expression is consistent with the expression pattern of the endogenous cytokeratin gene. The 1.5-kb mck promoter/gfp was expressed exclusively in skeletal muscles and not elsewhere. By contrast, the 0.8-kb ubiquitous promoter plus the first intron of the arp gene were capable of expressing GFP in a variety of tissues, including the skin, muscle, lens, neurons, notochord, and circulating blood cells. Our experiments, therefore, further demonstrated that zebrafish embryos can faithfully express exogenously introduced genes under the control of zebrafish promoters.

Altered levels of primary antioxidant enzymes in progeria skin fibroblasts

Free radicals are involved in the aging process. In this study, the profile of primary antioxidant enzymes that scavenge reactive oxygen species (ROS) was examined for the first time in human skin fibroblasts from progeria, a premature aging disease. Altered levels of antioxidant enzymes were found in progeria cells. Basal levels of MnSOD were decreased in progeria cells as well as a blunted induction in response to chronic stress. This change may contribute to the accelerated aging process in progeria cells. In contrast, the levels of CuZnSOD showed no progeria-related change. Two H2O2 removing enzymes demonstrated a significant reduction in progeria cells: only 50% of normal CAT activity and 30% of normal GPX activity can be detected in progeria cells. This diminished H2O2 removing capacity in progeria cells may lead to an imbalance of intracellular ROS and therefore may play an important role in the development of progeria.

A class of neuroD-related basic helix-loop-helix transcription factors expressed in developing central nervous system in zebrafish

Neuronal basic helix-loop-helix (bHLH) transcription factors such as neuroD and neurogenin have been shown to play important roles in neuronal development. In the present study, several distinct bHLH DNA fragments were isolated from the zebrafish genomic DNA by a pair of degenerate polymerase chain reaction (PCR) primers deduced from the conserved bHLH domains of neuroD and neurogenins. Based on the bHLH fragments, three complete neuroD-related cDNA clones, including complete coding regions, ndr1a, ndr1b, and ndr2 (ndr for neuroD related), were isolated and assembled by 5' and 3' rapid amplification of cDNA ends (RACE). A phylogenetic analysis indicated the presence of four groups of neuroD-related genes in the neuroD subfamily in vertebrates: neuroD, ndr1a/ndr1b/MATH-2, ndr2/NDRF, and neuroM/MATH3. Expression of the newly isolated neuroD-related genes was examined by reverse transcriptase (RT)-PCR and whole-mount in situ hybridization. Unlike neuroD, which was expressed broadly in primary neurons during early zebrafish development starting from 10 h postfertilization (hpf), expression of ndr1a and ndr1b started relatively late (around 22 hpf) and was restricted to the olfactory system: olfactory bulbs in the telecephalon (ndr1a and ndr1b) and olfactory organs (ndr1b) starting around 22 hpf. Although a faint ndr2 mRNA signal was detected by RT-PCR in early embryos, no ndr2 mRNA was detected by whole-mount in situ hybridization in embryos up to 72 hpf, suggesting that it is expressed rather late. Our observations suggest that the two novel neuroD-related genes, ndr1a and ndr1b, are involved in the development of the olfactory system and perhaps contribute to its functional complexity.

Fast skeletal muscle-specific expression of a zebrafish myosin light chain 2 gene and characterization of its promoter by direct injection into skeletal muscle

A zebrafish myosin light chain 2 cDNA clone was isolated and characterized. Sequence analysis of the clone revealed a high homology with the mammalian and avian genes encoding the fast skeletal muscle isoform, MLC2f. In situ hybridization and Northern blot hybridization analyses indicated that the zebrafish MLC2f mRNA is expressed exclusively in the fast skeletal muscle. Ontogenetically, the MLC2f mRNA appears around 16 hours postfertilization (hpf) in the first few well-formed anterior somites. At later stages, the MLC2f mRNA can also be detected in fin buds, eye muscles, and jaw muscles. To develop a useful model system for analyzing muscle gene regulation, the promoter of the zebrafish MLC2f gene was isolated and linked to the chloramphenicol acetyltransferase (CAT) reporter gene. The MLC2f/CAT chimeric constructs were analyzed by direct injection into the zebrafish skeletal muscle, and significant CAT activity was observed; in contrast, little or no CAT activity was generated from a similarly injected prolactin gene promoter/CAT gene construct. Within the 1 kb of the MLC2f promoter region, several MEF2-binding sites and E-boxes were identified, suggesting that MLC2f can be regulated by muscle transcription factors MEF2 and myogenic bHLH proteins. A 5' deletion analysis indicated that the proximal 79 nucleotides from the transcription start site, which contains a single MEF2-binding site, is sufficient to drive a high level of CAT activity in injected muscle. Internal deletion of the MEF2 element in the -79-bp construct caused an 80% decrease in CAT activity, whereas internal deletion of the same MEF2 element in a -1044-bp construct had no effect on induced CAT activity. These observations suggest that an MEF2 element is important to activate the MLC2f gene in muscle cells, and the effect of loss of the proximal MEF2 element can be compensated for by the presence of the upstream MEF2 elements. This study also demonstrated that direct injection of DNA into skeletal muscle is a valid and valuable approach to analyze muscle gene promoters in the zebrafish.

Use of commercial antibodies for detection of the primary antioxidant enzymes

Fourteen commercial antibodies against human antioxidant enzymes were tested on whole cell lysates by Western analysis for specificity and species crossreactivity. All antibodies, except one, recognized pure protein antigen. All four catalase antibodies were of high quality, and they could also recognize the catalases from rat, mouse, dog, and hamster cells. Two CuZnSOD antibodies were very specific for CuZnSOD protein. They could also crossreact with CuZnSOD from rat, mouse, and hamster cells, but not from dog cells. All five MnSOD antibodies detected only very high levels of MnSOD. We believe that they could not properly be used in immunohistochemistry. Three GPX antibodies could not detect the specific GPX band from cell lysates. We believe that it is difficult to use these GPX antibodies in both Western blotting and immunohistochemistry.

Contribution of the absence of aspartic acid at position 57 of the HLA-DQ beta chain to predisposition to insulin-dependent diabetes mellitus in a southern Chinese population

OBJECTIVE

To investigate the association of the absence or presence of aspartic acid at position 57 of the HLA-DQ beta chain (NA or A) with susceptibility or resistance to insulin-dependent diabetes mellitus (IDDM) in a Southern Chinese population.

METHODS

Sixty-nine IDDM patients and 47 healthy controls in a Southern Chinese population were HLA-DQB1 genotyped by one-step sequence specific polymerase chain reaction (ssPCR).

RESULTS

The frequencies of NA and A were 64.5% and 35.5% in the IDDM patients, and 40.4% and 59.6% in the control subjects respectively (RR for NA was 2.68, P < 0.01). The frequencies of NA/NA, NA/A and A/A phenotypes were 47.8%, 33.3% and 18.8% in the IDDM patients, and 31.9%, 17.0% and 51.1% in the controls respectively (P < 0.01). The frequency of A/A phenotype was significantly lower in the IDDM patients than in the control subjects (RR = 0.22, P < 0.01). DQB1* 0302 and DQB1* 0201 were more frequent in IDDM patients than in control subjects. The younger the age of IDDM onset, the higher the allele frequencies of DQB1* 0201 and DQB1* 0302.

CONCLUSION

The present study suggests that the NA confers the susceptibility to IDDM, while the A confers the protection against IDDM in patients of Southern Chinese origin. These associations are more clearcut in childhood-onset IDDM patients.

[The development of JX-300 high quality head stereotactic guided surgical system]

Based on the technology of three dimensions image forming and the arc stereotactic guided operator, this system has the advantages of locating precisely, convenient operation, and good result of curing. It has the imitation checking system of operation to guarantee the safe of patients.

Overexpression of human superoxide dismutase inhibits oxidation of low-density lipoprotein by endothelial cells

Oxidation of LDL in the subendothelial space has been proposed to play a key role in atherosclerosis. Endothelial cells produce superoxide anions (O2.-) and oxidize LDL in vitro; however, the role of O2.- in endothelial cell-induced LDL oxidation is unclear. Incubation of human LDL (200 microg/mL) with bovine aortic endothelial cells (BAECs) for 18 hours resulted in a 4-fold increase in LDL oxidation compared with cell-free incubation (22.5+/-1.1 versus 6.3+/-0.2 [mean+/-SEM] nmol malondialdehyde/mg LDL protein, respectively; P<0.05). Under similar conditions, incubation of LDL with porcine aortic endothelial cells resulted in a 5-fold increase in LDL oxidation. Inclusion of exogenous copper/zinc superoxide dismutase (Cu/ZnSOD, 100 microg/mL) in the medium reduced BAEC-induced LDL oxidation by 79%. To determine whether the intracellular SOD content can have a similar protective effect, BAECs were infected with adenoviral vectors containing cDNA for human Cu/ZnSOD (AdCu/ZnSOD) or manganese SOD (AdMnSOD). Adenoviral infection increased the content and activity of either Cu/ZnSOD or MnSOD in the cells and reduced cellular O2.- release by two thirds. When cells infected with AdCu/ZnSOD or AdMnSOD were incubated with LDL, formation of malondialdehyde was decreased by 77% and 32%, respectively. Two other indices of LDL oxidation, formation of conjugated dienes and increased LDL electrophoretic mobility, were similarly reduced by SOD transduction. These data suggest that production of O2.- contributes to endothelial cell-induced oxidation of LDL in vitro. Furthermore, adenovirus-mediated transfer of cDNA for human SOD, particularly Cu/ZnSOD, effectively reduces oxidation of LDL by endothelial cells.

Overexpression of manganese superoxide dismutase suppresses tumor necrosis factor-induced apoptosis and activation of nuclear transcription factor-kappaB and activated protein-1

Several recently identified intracellular proteins associate with the tumor necrosis factor (TNF) receptor and activate nuclear transcription factor (NF)-kappaB, c-Jun kinase, and apoptosis. However, the mechanism is not understood. In the present report, we investigated the role of reactive oxygen intermediates in TNF-induced signaling. Overexpression of manganese superoxide dismutase (Mn-SOD) in human breast cancer MCF-7 cells completely abolished TNF-mediated NF-kappaB activation, IkappaB alpha degradation, p65 nuclear translocation, and NF-kappaB-dependent reporter gene expression. Besides TNF, phorbol ester-, okadaic acid-, ceramide-, and lipopolysaccharide-induced activation of NF-kappaB was blocked by Mn-SOD, indicating a common pathway of activation. H2O2-induced NF-kappaB activation, however, was potentiated. In addition, Mn-SOD blocked the TNF-mediated activation of activated protein-1, stress-activated c-Jun protein kinase, and mitogen-activated protein kinase kinase. TNF-induced antiproliferative effects and caspase-3 activation, indicators of apoptosis, were also completely suppressed by transfection of cells with Mn-SOD. Suppression of apoptosis induced by okadaic acid, H2O2, and taxol was also inhibited by Mn-SOD but not that induced by vincristine, vinblastine, or daunomycin. Overall, these results demonstrate that, in addition to several recently identified signaling molecules, reactive oxygen intermediates play a critical role in activation of NF-kappaB, activated protein-1, c-Jun kinase, and apoptosis induced by TNF and other agents.

Protective effect of the angiotensin-converting enzyme inhibitor perindopril on diabetic glomerulopathy in streptozotocin-induced diabetic rats

OBJECTIVES

To evaluate the protective effect of the angiotensin-converting enzyme inhibitor perindopril on diabetic glomerulopathy in rats with experimentally induced diabetes and explore its possible mechanisms.

METHODS

Ninety-two adult male Wistar rats were randomly allocated into diabetes mellitus (DM), diabetes mellitus + perindopril (DMP) and control (C) groups. According to the duration of diabetes or observation (1, 3, 6 months), each group was randomly subdivided into DM1, DM3, DM6; DMP1, DMP3, DMP6; and C1, C3, C6 groups. Diabetes was induced by intraperitoneal injection of streptozotocin. The rats in the DMP groups received perindopril 1 mg.kg-1.d-1, through gastric intubation. Urinary protein excretion rate was determined by the method of Coomassie brilliant blue. Plasma renin activity, renal tissue renin activity, and plasma and renal tissue angiotensin II concentration were assayed by radioimmunoassay (RIA). Renal tissue total RNA was extracted by the Chomezymskis AGPC method. Renal angiotensinogen mRNA expression level was assessed by slot blot hybridization using a full length rat angiotensinogen cDNA probe labelled with 32P-dCTP and a random primer.

RESULTS

There was increased activity of the renin angiotensin system in diabetic rats. Perindopril decreased proteinuria and delayed the progression of glomerular basement membrane thickening. However, it did not reduce the expansion of the mesangial matrix (P < 0.05). Renin activity increased and angiotensin II concentration decreased significantly in both plasma and renal tissue in diabetes + perindopril groups (P < 0.05).

CONCLUSIONS

Perindopril may help prevent the progression of diabetic glomerulopathy, and the inhibition of renin angiotensin system activity may be a mechanism for this action.

[Time selection for RA synovectomy]

OBJECTIVE

To discuss the time selection for RA synovectomy.

METHOD

Eighty-six knees in 64 RA patients underwent synovectomy in 7 years. 8 of the 64 patients were in RA stage I, 26 in II, 24 in III, 8 in IV. The mean age was 43.9 years and the average follow-up period lasted 38.2 months.

RESULTS

Pain relief and swelling reduction were significant clinical features after synovectomy. The overall assessment of the effect of synovectomy showed satisfactory results (72.9%) including all RA-I, and RA-II (87.2%).

CONCLUSION

If the patients have sustained or intractable joint swollening with exuberant synovium after strict drug therapy over half a year, synovectomy is an appropriate consideration, it is very important to select the time for synovectomy.

[Effects of simulated microgravity on the distribution of 45Ca2+ in asparagus]

In order to find out the effects of microgravity on the distribution of Ca2+ in asparagus seedlings, tropic reaction of rhizome, the response of cells and organizations, as well as the distribution and transportation in organization under simulated microgravity condition were observed by means of 45CaCl2 labelled autoradiography. The results showed that the distribution of calcium cations highly correlated with gravity. The absorption, distribution and transportation of calcium were greatly affected by gravity.