[Performance of point-of-care testing for cervical cancer screening]

Objective: To evaluate the performance of point-of-care testing for cervical cancer and precancerous lesions screening. Methods: In September 2020, 197 and 273 women were selected by using simple random sampling method from "self-sampling" cohort and "physician-sampling" cohort established in Xiangyuan county, Shanxi Province, China, respectively. Cervical exfoliated cells were collected by women themselves or gynecologists. All samples were detected by POCT and women with positive result were directly referred for colposcopy. Subsequently, all the samples were detected by careHPV and PCR test. Colposcopy and punch biopsy were performed for women with POCT negative but careHPV or PCR test positive at another visit. Using histopathological diagnosis as the gold standard, we calculated sensitivity, specificity and drew the receiver operating characteristic (ROC) curves. The accuracy of POCT was analyzed and compared to that of careHPV and conventional PCR test in cervical cancer and precancerous lesions screening. Results: The median (Q₁ , Q₃) age of 470 women was 51 (45, 57) years old. Based on self-sampling, the sensitivity and specificity of POCT for CIN2+ were 100.00% (95%CI: 56.56%-100.00%) and 28.95% (95%CI: 22.97%-35.76%), respectively. Compared with POCT, POCT HPV16/18 test had similar sensitivity and higher specificity of 89.47% (95%CI: 84.30%-93.08%). Self-sampling POCT HPV16/18 test had an AUC of 0.947 (95%CI:0.910-0.985), which was higher than that of careHPV and PCR test. Physician-sampling POCT test had 100.00% sensitivity (95%CI: 64.57%-100.00%) and 55.85% specificity (95%CI: 49.83%-61.70%) for detecting CIN2+. POCT HPV16/18 test had lower sensitivity (71.43%, 95%CI: 35.90%-91.76%) and higher specificity (92.45%, 95%CI: 88.63%-95.06%). POCT HPV16/18 test generally showed similar AUC on both self-collected samples and clinician-collected samples (0.947 vs 0.819, P=0.217). Conclusion: POCT HPV16/18 test is an effective method with relatively high sensitivity and specificity for cervical cancer screening.

[Effect of body mass index on the assisted reproductive outcome of frozen-thawed embryo transfer in patients with polycystic ovary syndrome]

Objective: To investigate the effect of body mass index (BMI) on clinical pregnancy and neonatal outcomes in patients with polycystic ovary syndrome (PCOS) during frozen-thawed embryo transfer. Methods: A total of 650 patients with PCOS who received routine in vitro fertilization or intracytoplasmic sperm injection treatment for frozen-thawed embryo transfer from June 2014 to June 2019 in Tianjin Central Hospital of Gynecology Obstetrics were retrospectively analyzed. According to BMI, PCOS patients were divided into group A (18.5≤BMI<23 kg/m², n=253), group B (23≤BMI<25 kg/m², n=167), and group C (BMI≥25 kg/m², n=230). The general information, clinical pregnancy outcomes, pregnancy complications, the incidence of macrosomia and low-birth-weight infants were compared in the three groups, and the influencing factors of neonatal birth weight were analyzed. Results: The embryo implantation rate, clinical pregnancy rate, and ongoing pregnancy rate all showed downward trend with the increase of BMI, but the differences were not statistically significant (all P>0.05). The live birth rate in group C [47.0% (108/230)] was significantly lower than those in groups A and B, with statistical significance (χ²=7.43, P=0.024). The late miscarriage rate was higher in group C [9.4% (13/139)] than in groups A and B (χ²=7.66, P=0.022). The birth rates of macrosomia in groups B [22.2% (16/72)] and group C [21.1% (16/76)] were significantly higher than that in group A, and the difference was statistically significant (χ²=14.15, P=0.001). There was no statistically significant difference in the incidence of gestational diabetes between the three groups (χ²=3.81, P=0.149). The incidence of hypertension disorders complicating pregnancy increased with the increase of BMI, and the difference was not statistically significant (P>0.05). Regression analysis showed that macrosomia was significantly associated with maternal pre-pregnancy BMI and gestational weeks, and the risk of macrosomia increased by 15% (95%CI: 3%-28%) for every increase in maternal BMI. Conclusions: The embryo implantation rate, clinical pregnancy rate, and ongoing pregnancy rate of PCOS patients in frozen-thawed embryo transfer cycles show downward trend with the increase of BMI. Obese patients with PCOS have a significant increase in late miscarriage rate and a significant decrease in live birth rate. The incidence of hypertension disorders complicating pregnancy in PCOS patients in the obese group has an increasing trend, and the birth rate of macrosomia has increased significantly. Therefore, it is recommended that obese women with PCOS lose weight scientifically before pregnancy to improve pregnancy and neonatal outcomes.

[Impact of previous cesarean delivery on pregnancy outcomes of in vitro fertilization and frozen-thawed embryo transfer]

Objective: To investigate the impact of a previous cesarean delivery on pregnancy outcomes of in vitro fertilization and frozen-thawed embryo transfer (FET). Methods: The clinical data of 1 179 patients who received in vitro fertilization and FET in Tianjin Central Hospital of Gynecology Obstetrics from January 2014 to May 2019 and had a history of the previous delivery were retrospectively analyzed. The patients were divided into four groups according to different previous delivery history and the number of embryo transferred: group A (single embryo transfer group with cesarean delivery history, n=338), group B (single embryo transfer group with vaginal delivery history, n=78), group C (double embryo transfer group with cesarean delivery history, n=444), and group D (double embryo transfer group with vaginal delivery history, n=319). The 1∶1 propensity score based on age, body mass index (BMI), infertility duration, basal FSH, basal LH, number of oocytes retrieved and high-quality embryo rate was used to match group A and B (caliper value=0.15), group C and D (caliper value=0.05), and group A and C (caliper value=0.01) respectively to reduce the influence of selection bias. The clinical pregnancy outcomes of patients were compared. Results: (1) Group A and group B were single embryo transfer groups with a total of 77 pairs of matched patients. There were no statistically significant differences in clinical pregnancy rate [42.9% (33/77) vs 45.5% (35/77)], miscarriage rate, preterm birth rate, and neonatal birth weight (all P>0.05). (2) Group C and group D were double embryo transfer groups with a total of 304 pairs of matched patients. The clinical pregnancy rate [42.4% (129/304)] and twin pregnancy rate [9.5% (29/304)] of Group C were significantly lower than those of Group D [53.0% (161/304), 15.5% (47/304) respectively; both P<0.05). There were no statistically significant in miscarriage rate, preterm birth rate and neonatal birth weight between the two groups (all P>0.05). (3) Groups A and C matched 318 pairs of patients. The two groups had no statistical significances in clinical pregnancy rate [38.4% (122/318) vs 45.6% (145/318)], miscarriage rate and preterm birth rate (all P>0.05), but the twin pregnancy rate in group C was significantly higher than that of group A [11.3% (36/318) vs 0.3% (1/318), P<0.01). (4) The occurrence of the low-birth-weight infant were related to gestational age (OR=0.41, 95%CI: 0.32-0.54) and twin pregnancy (OR=4.44, 95%CI: 1.93-10.21), and the occurrence of macrosomia was related to BMI (OR=1.18, 95%CI: 1.06-1.32). Moreover, the previous delivery method was not related to the neonatal birth weight (P>0.05). Conclusions: Patients with different delivery histories receive FET therapy, the pregnancy outcomes of single embryo transfer are not significantly different, and the success rate of double embryo transfer in patients with a cesarean delivery history is low. The neonatal birth weight is not related to the history of the cesarean section. It is recommended that patients with a cesarean delivery history choose elective single embryo transfer to ensure the success rate and to reduce the risk.

[Effect of the number of previous spontaneous abortions on the first in vitro fertilization cycle]

Objective: To investigate the effect of the number of previous spontaneous abortions on the first in vitro fertilization or intracytoplasmic sperm injection (IVF/ICSI) cycle. Methods: A retrospective case-control study was conducted to analyze the clinical data of 1 279 patients who received IVF/ICSI treatment for the first time from July 2014 to July 2018 in Tianjin Central Hospital of Gynecology Obstetrics;they were divided into 0 time group (group A, n=924), 1 time group (group B, n=267) and 2 times group (group C, n=88) for comparison, according to the previous frequency of spontaneous abortions. Results: There were no statistically significant differences in age, basal testosterone, estradiol, progesterone, prolactin and embryo quality in group A, B and C (all P>0.05). The biochemical pregnancy rate of group C (9.1%) was higher than those of the other two groups (4.1% and 4.1%; all P>0.05). The clinical pregnancy rate of group A (42.5%) [>group B (40.4%) and >group C (35.2%)] was not statistically significant(P>0.05).Early abortion rate in group A (8.9%) was<group B (15.7%), also <group C (38.7%), there were significant differences (all P<0.05).The live birth rate of group C (21.6%) was significantly lower than that of group A (35.5%; P<0.05), but the difference between group C and group B (30.7%) was not statistically significant (P>0.05). Conclusions: Women with a history of one- or two-time spontaneous abortion have no obvious effect on embryo quality, and have a negative impact of clinical pregnancy rate, early abortion rate, live birth rate in the first IVF/ICSI cycle; especially for patients with a history of two times spontaneous abortion, early abortion rate has a significant increase, live birth rate decreases significantly, suggesting that patients with a history of two times of spontaneous abortion should find the causes of miscarriage according to the process of recurrent spontaneous miscarriage and receive treatment if necessary before subsequent pregnancy.

[Study on the distribution and related factors of birth weight of live births in Guangxi Zhuang Autonomous Region of China from 2016 to 2018]

Objective: To investigate the distribution and related factors of birth weight of live births and full-term infants in Guangxi Zhuang Autonomous Region of China. Methods: Based on Guangxi women and children information system from 2016 to 2018, a large real-time database about maternal and live-birth information was established. It covered 1 712 midwifery institutions in Guangxi. A total of 2 394 240 cases of live births were collected and 2 243 129 cases of which were full-term infants. The multivariate logistic regression model was used to analyze the related factors of low birth weight. Results: The birth weight of 2 394 240 live births, (3 123.49±461.08) g, in Guangxi was approximately normal distribution with a peak distribution to the left. The incidence of low birth weight was 8.05%, and the incidence of macrosomia was 2.07%. The incidence of low birth weight was 10.92% for the puerpera with body mass index (BMI, kg/m(2)) <18.5, 16.82% for the puerpera with height <145 cm, 8.92% for the puerpera with age <20 years old, 7.67% for the puerpera with age ≥35 years old, and 54.65% for the puerpera with premature birth. The birth weight of 2 243 129 full-term infants, (3 176.01±400.78) g, was approximately normal distribution with a peak distribution to the right. The incidence of low birth weight was 2.97%, and the incidence of macrosomia was 2.19%. The incidence of low birth weight was 4.73% for puerpera with BMI<18.5, 8.17% for puerpera with height<145 cm, 4.83% for puerpera with age <20 years old, and 3.05% for puerpera with age ≥35 years old. The risks of low birth weight [OR (95%CI) value] of pregnant women aged <20, 25-29 and 30-34 years old were 1.31 (1.28-1.35), 0.88 (0.86-0.90) and 0.89 (0.87-0.91) times of those aged ≥35 years old. The risks of low birth weight [OR (95%CI) value] of pregnancy BMI <18.5 and 18.5-23.9 kg/m(2) group were 1.98 (1.94-2.03) and 1.20 (1.18-1.23) times of those pregnancy BMI ≥24 kg/m(2). The risks of low birth weight [OR (95%CI) value] of pregnant women's height (cm)<145, 145-154, 155-159 and 160-164 cm were 4.67 (4.39-4.97), 2.36 (2.29-2.44), 1.58 (1.53-1.63) and 1.22 (1.18-1.26) times of those heights ≥165 cm group. The risks of low birth weight [OR (95%CI) value] of pregnant women's gestational age <28, 28-31 and 32-36 years old were 136.65 (124.33-150.20), 1 704.37 (1 509.02-1 925.02) and 33.45 (32.98-33.94) times of those gestational age ≥37 years old. Conclusion: The incidence of low birth weight of live births was higher in Guangxi from 2016 to 2018. There is a higher risk of low birth weight for younger, older, low height, low BMI and preterm women in Guangxi from 2016 to 2018.

[Expression of Tim-3 on natural killer cells in patients with acute myeloid leukemia and its clinical significance]

目的

探讨负性共刺激分子Tim-3在初诊急性髓系白血病（AML）患者外周血自然杀伤细胞（NK细胞）表面的表达特征及其临床意义。

方法

采集2013年6月至2014年6月苏州大学附属第一医院血液内科收治的未经任何临床措施干预的39例AML患者外周血及28名健康志愿者的外周血，采用CD3⁻、CD56⁺、Tim-3⁺为标志，经免疫荧光标记和流式细胞术检测Tim-3在AML患者外周血NK细胞上的表达。

结果

初诊AML患者外周血NK细胞占淋巴细胞比例为（5.74±5.31）%，较正常对照组的（12.55±6.33）%显著下降（t=4.596，P<0.001）；初诊AML患者外周血NK细胞上Tim-3的表达水平为（42.67±19.08）%，较正常对照组的（60.99±20.69）%显著下降（t=3.781，P<0.001）。AML患者外周血NK细胞比例与其染色体核型相关（t=2.915，P<0.05）；Tim-3在AML患者NK细胞表达水平与患者诱导缓解率、危险分层相关（P值均<0.05）。

结论

AML患者外周血中NK细胞比例及Tim-3表达水平明显下降，Tim-3在AML患者外周血NK细胞上表达下调与AML的预后相关。

[Clinical observation on the anthracyclines-induced cardiotoxicity in patients with early-stage breast cancer]

Objective: To evaluate the anthracyclines-induced cardiotoxicity in patients with early-stage breast cancer. Methods: This retrospective study analyzed data of 64 patients (aged from 36 to 59 years old) with early-stage breast cancer after surgery. Patients were divided into ACT group (n=21), FAC group (n=19) and EC group (n=24). The NCI CTC 4.0 scores was used to evaluate the side effects at the time of 2 weeks, 4 weeks and 6 weeks after chemotherapy. Meanwhile, the level of cTnT, the incidence of abnormal electrocardiogram (ECG) and left ventricular ejection fraction (LVEF) were used to evaluate the anthracyclines-induced cardiotoxicity, the follow-up observation points were as follows: at the acute cardiotoxicity (time A), subacute cardiotoxicity (time B), 24 months after chemotherapy (time C), 36 months after chemotherapy (time D), 48 months after chemotherapy (time E), 60 months after chemotherapy (time F). The 3-years and 5-years overall survival and progress free disease survival among three groups were compared. Results: The ages, clinical stage, the size of tumor, axillary lymph node positivity and Eastern Cooperative Oncology Group Scores were similar among three groups (P>0.05); the incidence of side effects level 4 was 0. The levels of cTnT in the three groups were significantly lower than those at the baseline and time points C, D, E and F (all P<0.05), and the levels of cTnT were significantly higher in EC group than in FAC and ACT group at the time points B, C, D, E and F (P<0.05); however, the incidence of abnormal ECG and LVEF was similar among the 3 groups (P>0.05). The 5-year overall survival was 95.2% (20/21) ,100% (19/19) and 95.8% (23/24) in ACT group, FAC group and EC group, respectively; 5-year progress free disease survival was 95.2% (20/21) ,94.7% (18/19) and 91.7% (22/24) in ACT group, FAC group and EC group, respectively (P>0.05) . Conclusions: Patients with early-stage breast cancer after surgery could tolerate the anthracyclines-induced cardiotoxicity. Three chemotherapy schemes of ACT, FAC and EC, especially the EC protocol, could affect the myocardial damage. However, outcome is comparable among patients treated with above chemotherapy schemes in this patient cohort.

[Primary investigation of immunoglobulin A synthesis and secretion in human mesangial cells]

OBJECTIVE

To investigate the expression of immunoglobulin A (IgA) in human mesangial cells (HMCs).

METHODS

The HMCs were cultured. The subcellular location of IgA was detected by immunofluorescence staining; the transcripts of Igα,Igκ and IgΛ constant region were detected by reverse transcription-polymerase chain reaction (RT-PCR) and further analyzed by DNA sequencing. The expressions of Igα and IgΛ were detected at transcription level by Western blot after the cytoplasmic protein extraction. The culture supernatant was collected to explore whether IgA could be secreted out of the cell and the protein was further analyzed by mass spectrometry after being purified by affinity chromato-graphy with jacalin-sepharose. The results of DNA sequencing and mass spectrometry were aligned with the mRNA and amino acid sequences in the National Center of Biotechnology Information (NCBI) database.

RESULTS

By immunofluorescence staining, we detected the presence of IgA heavy chain Igα, light chain, both Igκ and IgΛ in expressions of transcripts of Igα1, Igα2, Igκ and IgΛ in the HMCs and the alignment of the sequences of the RT-PCR products with those of the IgCα1, IgCα2, Igκ and IgΛ mRNA in the NCBI database exhibited that the similarities were 99%, 97%, 98% and 97%, respectively. Western blot showed Igα and IgΛ expressions in the cell lysate and secretion of Igα1 and Igα2 heavy chains in cell culture supernatant. To further explore the protein that secreted into the supernatant, after supernatant affinity chromatography with jacalin-sepharose, the proteins were separated by sodium dodecyl sulfonate-polyacrylamide gel electrophoresis (SDS-PAGE) and the band approximating to 65 000 was cut and sent to mass spectrometry. The results were aligned with the amino acid sequences of Igα1 and Igα2 constant region in NCBI database, showing that amino acids between No.52 and No.104, amino acids between No.154 and No.221, amino acids between No.276 and No.327 from IgCα1 and amino acids between No.52 and No.113, amino acids between No.151 and No.204, amino acids between No.251 and No.314 from IgCα2 were the same with those derived from B cells.

CONCLUSION

Our fin-dings suggested that HMCs could synthesize and secret IgA.

Root cone angle is enlarged in docs1 LRR-RLK mutants in rice

BACKGROUND

The DEFECTIVE IN OUTER CELL LAYER SPECIFICATION 1 (DOCS1) gene belongs to the Leucine-Rich Repeat Receptor-Like Kinase (LRR-RLK) subfamily. It has been discovered few years ago in Oryza sativa (rice) in a screen to isolate mutants with defects in sensitivity to aluminum. The c68 (docs1-1) mutant possessed a nonsense mutation in the C-terminal part of the DOCS1 kinase domain.

FINDINGS

We have generated a new loss-of-function mutation in the DOCS1 gene (docs1-2) using the CRISPR-Cas9 technology. This new loss-of-function mutant and docs1-1 present similar phenotypes suggesting the original docs1-1 was a null allele. Besides the aluminum sensitivity phenotype, both docs1 mutants shared also several root phenotypes described previously: less root hairs and mixed identities of the outer cell layers. Moreover, our new results suggest that DOCS1 could also play a role in root cap development. We hypothesized these docs1 root phenotypes may affect gravity responses. As expected, in seedlings, the early gravitropic response was delayed. Furthermore, at adult stage, the root gravitropic set angle of docs1 mutants was also affected since docs1 mutant plants displayed larger root cone angles.

CONCLUSIONS

All these observations add new insights into the DOCS1 gene function in gravitropic responses at several stages of plant development.

Narcissus yellow stripe virus and Narcissus mosaic virus detection in Narcissus via multiplex TaqMan-based reverse transcription-PCR assay

AIMS

Development of a multiplex TaqMan RT-qPCR assay to simultaneously detect Narcissus yellow stripe virus (NYSV) and Narcissus mosaic virus (NMV), frequently causing mixed narcissus infection. Feasibility verification was confirmed in natural samples.

METHODS AND RESULTS

Primers and probes were designed based on the conserved CP gene regions of NYSV or NMV and their suitability for singleplex and multiplex TaqMan RT-qPCR assays as well as for conventional RT-PCR. Conventional RT-PCR, singleplex and multiplex TaqMan RT-qPCR assays proved to be NYSV and NMV specific. P-values and coefficients of variation of TaqMan RT-qPCR assays indicated high reproducibility. Significantly increased sensitivity was achieved compared to conventional RT-PCR. The detection limit of both viruses was 10³ copies with superior correlation coefficients and linear standard curve responses between plasmid concentrations and Ct values. NYSV and NMV infection of narcissus leaves, petals and bulbs could successfully be detected via our multiplex RT-qPCR method at 1·25 mg.

CONCLUSION

Our multiplex TaqMan RT-qPCR assay provides rapid, specific, sensitive and reliable testing to simultaneously detect NYSV and NMV, supplying useful routine monitoring for different narcissus samples.

SIGNIFICANCE AND IMPACT OF THE STUDY

Efficient identification and discrimination of the narcissus viruses provides reliable information for scientists and conventional growers. Furthermore, it enriches the information of NYSV, NMV and other narcissus viruses.

[Changes in genotype prevalence of human papillomavirus over 10-year follow-up of a cervical cancer screening cohort]

Objective: To evaluate the dynamic variation of genotypes distribution of human papillomavirus (HPV) over 10-year follow-up in a cervical cancer screening cohort. Methods: Based on the Shanxi Province Cervical Cancer Screening Study Ⅰ cohort, we detected HPV genotypes on the well-preserved exfoliated cervical cells from women who were tested HPV positive from year 2005 to year 2014 using reverse linear probe hybridization assay. The changes of prevalence of type-specific HPV over time among the overall population were estimated using linear mixed models. The association between the type-specific HPV and cervical intraepithelial neoplasia grade 2 or worse (CIN2 +) was calculated by linear Chi-square test. Finally, the trends of multiple infections of HPV with the increase of the age were analyzed. Results: During the cervical cancer screening of the overall population from 2005 to 2014, the most common genotypes among the population were HPV16 and 52. The prevalence of HPV16 decreased over time from 4.6% in 2005 to 2.2% in 2010 and 2014 (F=8.125, P<0.001). The prevalence of HPV52 remained pretty stable and HPV33, 51 and 58 slightly decreased then apparently increased. Further stratification analysis by pathological lesions showed the same trend of the HPV prevalence for the histology normal women with the overall population. Of note, for those women with the cervical intraepithelial neoplasia (CIN2 +), the detection rate of HPV16 decreased from 65.22% in 2005 to 41.03% in 2010 and finally to 31.58% in 2014 (χ(2)=4.420, P=0.036) and that of HPV33 substantially increased. No significant variation was found for other types of HPV. Multiple infection rate varied with the growing age of the women. Conclusions: The genotypes prevalence of HPV tended to vary over time during cervical cancer screening in the context of regular screening combining with immediate treatment for those CIN2 + women. HPV16 prevalence significantly decreased over time, which indicated that the variation of type-specific HPV prevalence should be considered when regular cervical cancer screening was organized using HPV technique.

Comparison of 2015 Medicare relative value units for gender-specific procedures: Gynecologic and gynecologic-oncologic versus urologic CPT coding. Has time healed gender-worth?

BACKGROUND

In 1992, Congress implemented a relative value unit (RVU) payment system to set reimbursement for all procedures covered by Medicare. In 1997, data supported that a significant gender bias existed in reimbursement for gynecologic compared to urologic procedures. The present study was performed to compare work and total RVU's for gender specific procedures effective January 2015 and to evaluate if time has healed the gender-based RVU worth.

METHODS

Using the 2015 CPT codes, we compared work and total RVU's for 50 pairs of gender specific procedures. We also evaluated 2015 procedure related provider compensation. The groups were matched so that the procedures were anatomically similar. We also compared 2015 to 1997 RVU and fee schedules.

RESULTS

Evaluation of work RVU's for the paired procedures revealed that in 36 cases (72%), male vs female procedures had a higher wRVU and tRVU. For total fee/reimbursement, 42 (84%) male based procedures were compensated at a higher rate than the paired female procedures. On average, male specific surgeries were reimbursed at an amount that was 27.67% higher for male procedures than for female-specific surgeries. Female procedure based work RVU's have increased minimally from 1997 to 2015.

CONCLUSION

Time and effort have trended towards resolution of some gender-related procedure worth discrepancies but there are still significant RVU and compensation differences that should be further reviewed and modified as surgical time and effort highly correlate.

[Effects of iron chelation therapy on allogeneic hematopoietic stem cell transplantation in myelodysplastic syndrome patients with iron overload]

OBJECTIVE

To investigate the effects of iron chelation therapy on hematopoietic reconstitution and related complications of allogeneic hematopoietic stem cell transplantation (allo-HSCT) in patients with myelodysplastic syndrome (MDS).

METHODS

Various clinical parameters were analyzed retrospectively in 57 MDS patients with iron overload who received allo-HSCT. According to the level of serum ferritin (SF) before transplantation divided patients into two groups: the effective treatment group (SF<1 000 μg/L) and iron overload group (SF≥1 000 μg/L).

RESULTS

①30/57 cases were received iron chelation treatment, 27/57 patients didn' t received iron chelating therapy before transplantation. 19/30 cases were in the effective treatment group, and the median SF level before transplantation was 561 (223-846) μg/L. 11/30 cases were in the iron overload group, and the median SF level before transplantation was 1 262 (1 100-2 352) μg/L. The median SF level was 1 540 (1 320-3 112) μg/L of 27 patients didn't received iron chelating therapy before transplantation. ② The rate of fully-engraftment in the effective treatment group and iron overload group was 19 cases (100.0% ) and 34 cases (89.5% ), myeloid reconstitution of 12(10-18) and 12(11-30) days respectively (P=0.441), and platelet reconstitution of 13(12-30) and 15 (10-32) days respectively (P=0.579). ③The infection risk rate of the effective treatment group was less than iron overload group [36.8% (7/19) vs 82.4% (28/34), P=0.002]. ④The incidence of aGVHD in effective treatment group was less than iron overload group [26.3%(5/19) vs 64.7%(22/34), P= 0.010]. All patients of the effective treatment group were Ⅰ/Ⅱ degree. 16 cases were Ⅰ/Ⅱ degree and 6 cases were Ⅲ/Ⅳ degree in the iron overload group. ⑤ 6 cases of iron overload group accepted iron chelation treatment early post-transplantation, and SF level decreased from 2 870 (2 205-3 580) μg/L to 1 270 (1 020-1 650) μg/L. ⑥The difference of median disease-free survival time between the effective treatment group and iron overload group was not statistically significant [28.9 (0.3-89.5) months vs 21.2(0.1-81.0) months, χ(2)=3.751, P=0.053].

CONCLUSIONS

Iron overload obviously increased transplant-related complications, and effective iron chelation therapy before transplantation significantly decreased the incidence of infection and degree of aGVHD, thereby reduced the non-relapse mortality in patients with MDS.

Apoptotic-induced cleavage shifts HuR from being a promoter of survival to an activator of caspase-mediated apoptosis

Little is known about the cellular mechanisms modulating the shift in balance from a state of survival to cell death by caspase-mediated apoptosis in response to a lethal stress. Here we show that the RNA-binding protein HuR has an important function in mediating this switch. During caspase-mediated apoptosis, HuR is cleaved to generate two cleavage products (CPs). Our data demonstrate that the cleavage of HuR switches its function from being a prosurvival factor under normal conditions to becoming a promoter of apoptosis in response to a lethal stress. In the absence of an apoptotic stimuli, HuR associates with and promotes the expression of caspase-9 and prothymosin α (ProT) mRNAs, and pro- and antiapoptotic factors, respectively, both of which have been characterized as important players in determining cell fate. During the early steps of caspase-mediated apoptosis, however, the level of caspase-9 protein increases, while ProT remains unchanged. Under these conditions, the two HuR-CPs selectively bind to and stabilize caspase-9 mRNA, but do not bind to ProT. Hence, taken together, our data show that by maintaining a threshold of expression of proapoptotic factors such as caspase-9 in response to a lethal stress, the HuR-CPs help a cell to switch from resisting death to undergoing apoptosis.

Use of an expanded gold standard to estimate the accuracy of colposcopy and visual inspection with acetic acid

We estimate the accuracy of colposcopy and visual inspection with acetic acid (VIA) while minimizing the effects of misclassification bias, and maximizing ascertainment of disease. VIA was performed by experienced physicians on a population-based sample of women aged 30 to 49 years in rural Shanxi province, China. Each woman received VIA, liquid-based cytology (LBC) and hybrid capture 2 (hc2, QIAGEN, Gaithersburg, MD; formerly Digene Corporation). Any woman who tested positive on any test had colposcopy, endocervical curettage (ECC) with directed biopsies as necessary and 4-quadrant random biopsies from normal-appearing areas of the cervix. A standard diagnosis based on colposcopy and directed biopsy, and an expanded diagnosis including ECC and 4-quadrant random biopsy were generated for each woman. In 1,839 women, use of the expanded versus the standard diagnostic criteria increased the prevalence of histologically confirmed high-grade cervical intraepithelial neoplasia and cancer (CIN2+) from 3.2% (59/1,839) to 4.2% (77/1,839) and decreased the sensitivity of VIA for CIN2+ from 69.5% (95% CI: 56.8-79.8) to 58.4% (95% CI: 47.3-68.8%) with little change in specificity of approximately 89%. Compared with the expanded diagnostic criterion, the sensitivity of a visual diagnosis of high-grade CIN or cancer by a colposcopist was 49.4% (95% CI: 38.2-60.5). The use of an expanded diagnostic criterion in this study yielded more conservative estimates of the sensitivity of VIA and colposcopy.

Mitigation of arsenic accumulation in rice with water management and silicon fertilization

Rice represents a major route of As exposure in populations that depend on a rice diet. Practical measures are needed to mitigate the problem of excessive As accumulation in paddy rice. Two potential mitigation methods, management of the water regime and Si fertilization, were investigated under greenhouse conditions. Growing rice aerobically during the entire rice growth duration resulted in the leastAs accumulation. Maintaining aerobic conditions during either vegetative or reproductive stage of rice growth also decreased As accumulation in rice straw and grain significantly compared with rice grown under flooded conditions. The effect of water management regimes was consistent with the observed effect of flooding-induced arsenite mobilization in the soil solution. Aerobic treatments increased the percentage of inorganic As in grain, but the concentrations of inorganic As remained lower than in the flooded rice. Silicon fertilization decreased the total As concentration in straw and grain by 78 and 16%, respectively, even though Si addition increased As concentration in the soil solution. Silicon also significantly influenced As speciation in rice grain and husk by enhancing methylation. Silicon decreased the inorganic As concentration in grain by 59% while increasing the concentration of dimethylarsinic acid (DMA) by 33%. There were also significant differences between two rice genotypes in grain As speciation. This study demonstrated that water management Si fertilization, and selection of rice cultivars are effective measures that can be used to reduce As accumulation in rice.

Arsenic uptake and metabolism in plants

Arsenic (As) is an element that is nonessential for and toxic to plants. Arsenic contamination in the environment occurs in many regions, and, depending on environmental factors, its accumulation in food crops may pose a health risk to humans.Recent progress in understanding the mechanisms of As uptake and metabolism in plants is reviewed here. Arsenate is taken up by phosphate transporters. A number of the aquaporin nodulin26-like intrinsic proteins (NIPs) are able to transport arsenite,the predominant form of As in reducing environments. In rice (Oryza sativa), arsenite uptake shares the highly efficient silicon (Si) pathway of entry to root cells and efflux towards the xylem. In root cells arsenate is rapidly reduced to arsenite, which is effluxed to the external medium, complexed by thiol peptides or translocated to shoots. One type of arsenate reductase has been identified, but its in planta functions remain to be investigated. Some fern species in the Pteridaceae family are able to hyperaccumulate As in above-ground tissues. Hyperaccumulation appears to involve enhanced arsenate uptake, decreased arsenite-thiol complexation and arsenite efflux to the external medium, greatly enhanced xylem translocation of arsenite, and vacuolar sequestration of arsenite in fronds. Current knowledge gaps and future research directions are also identified.

Arsenic uptake and metabolism in plants

Arsenic (As) is an element that is nonessential for and toxic to plants. Arsenic contamination in the environment occurs in many regions, and, depending on environmental factors, its accumulation in food crops may pose a health risk to humans.Recent progress in understanding the mechanisms of As uptake and metabolism in plants is reviewed here. Arsenate is taken up by phosphate transporters. A number of the aquaporin nodulin26-like intrinsic proteins (NIPs) are able to transport arsenite,the predominant form of As in reducing environments. In rice (Oryza sativa), arsenite uptake shares the highly efficient silicon (Si) pathway of entry to root cells and efflux towards the xylem. In root cells arsenate is rapidly reduced to arsenite, which is effluxed to the external medium, complexed by thiol peptides or translocated to shoots. One type of arsenate reductase has been identified, but its in planta functions remain to be investigated. Some fern species in the Pteridaceae family are able to hyperaccumulate As in above-ground tissues. Hyperaccumulation appears to involve enhanced arsenate uptake, decreased arsenite-thiol complexation and arsenite efflux to the external medium, greatly enhanced xylem translocation of arsenite, and vacuolar sequestration of arsenite in fronds. Current knowledge gaps and future research directions are also identified.

The pulmonary toxicity of multi-wall carbon nanotubes in mice 30 and 60 days after inhalation exposure

The pulmonary toxicity, induced by multi-wall carbon nanotubes in mice, was studied after 30-day and 60-day inhalation exposure. The mice were exposed to multi-wall carbon nanotubes aerosol with weighted mean concentration of 32.61 mg/m3, once in very two days, 6 hours in an exposure day. After 30-day and 60-day inhalation exposure, the pulmonary toxicity of multi-wall carbon nanotubes was assessed using biochemical indices in bronchoalveolar lavage fluid and pathological examination. It was found that the aerosolized multi-wall carbon nanotubes did not induce obvious pulmonary toxicity in 30-day exposure group, but induced severe pulmonary toxicity in 60-day exposure group.

A major quantitative trait locus controlling cadmium translocation in rice (Oryza sativa)

The trait of low cadmium (Cd) accumulation in brown rice (Oryza sativa) is important for food safety. An effective way to reduce Cd accumulation in the grain is to control Cd transfer from the roots to the shoots. Here, we investigated genotypic variation in the shoot Cd concentration among 146 accessions from a rice core collection and performed a quantitative trait locus (QTL) analysis to determine the loci controlling shoot Cd accumulation. Furthermore, we physiologically characterized the two accessions used for QTL analysis. Large genotypic variation (13-fold) in the shoot Cd concentration was found. A major QTL was detected on chromosome 11 using a F2 population derived from Badari Dhan (a high-Cd accession) and Shwe War (a low-Cd accession). This QTL explained 16.1% of the phenotypic variation in Cd accumulation. Furthermore, this QTL was confirmed by analysis of advanced progeny. Physiological studies showed that Badari Dhan and Shwe War did not differ in uptake of Cd by the roots, but differed greatly in the translocation of Cd from the roots to the shoots. Taken together, our findings suggest that the major QTL detected is responsible for the translocation of Cd from the roots to the shoots.

Functions and transport of silicon in plants

Silicon exerts beneficial effects on plant growth and production by alleviating both biotic and abiotic stresses including diseases, pests, lodging, drought, and nutrient imbalance. Recently, two genes (Lsi1 and Lsi2) encoding Si transporters have been identified from rice. Lsi1 (low silicon 1) belongs to a Nod26-like major intrinsic protein subfamily in aquaporin, while Lsi2 encodes a putative anion transporter. Lsi1 is localized on the distal side of both exodermis and endodermis in rice roots, while Lsi2 is localized on the proximal side of the same cells. Lsi1 shows influx transport activity for Si, while Lsi2 shows efflux transport activity. Therefore, Lsi1 is responsible for transport of Si from the external solution to the root cells, whereas Lsi2 is an efflux transporter responsible for the transport of Si from the root cells to the apoplast. Coupling of Lsi1 with Lsi2 is required for efficient uptake of Si in rice.

Variation in root-to-shoot translocation of cadmium and zinc among different accessions of the hyperaccumulators Thlaspi caerulescens and Thlaspi praecox

Efficient root-to-shoot translocation is a key trait of the zinc/cadmium hyperaccumulators Thlaspi caerulescens and Thlaspi praecox, but the extent of variation among different accessions and the underlying mechanisms remain unclear. Root-to-shoot translocation of Cd and Zn and apoplastic bypass flow were determined in 10 accessions of T. caerulescens and one of T. praecox, using radiolabels (109)Cd and (65)Zn. Two contrasting accessions (Pr and Ga) of T. caerulescens were further characterized for TcHMA4 expression and metal compartmentation in roots. Root-to-shoot translocation of (109)Cd and (65)Zn after 1 d exposure varied 4.4 to 5-fold among the 11 accessions, with a significant correlation between the two metals, but no significant correlation with uptake or the apoplastic bypass flow. The F(2) progeny from a cross between accessions from Prayon, Belgium (Pr) and Ganges, France (Ga) showed a continuous phenotype pattern and transgression. There was no significant difference in the TcHMA4 expression in roots between Pr and Ga. Compartmentation analysis showed a higher percentage of (109)Cd sequestered in the root vacuoles of Ga than Pr, the former being less efficient in translocation than the latter. Substantial natural variation exists in the root-to-shoot translocation of Cd and Zn, and root vacuolar sequestration may be an important factor related to this variation.

The genetic basic and fine-mapping of a stable quantitative-trait loci for aluminium tolerance in rice

Aluminium (Al) toxicity is a primary cause of low rice productivity in acid soils. We have mapped a number of quantitative-trait loci (QTL) controlling Al tolerance in a recombinant inbred line population derived from a cross between the tolerant japonica cultivar Asominori and the sensitive indica cultivar IR24. Tolerance was assessed on the basis of relative root elongation. QTL were detected on chromosomes 1, 9, and 11, with the percentages of phenotypic variance explained ranging from 13.5 to 17.7%. Alleles from Asominori at all three QTL were associated with increased Al tolerance. qRRE-9 is expressed both in the genetic background of IR24 and in an Asominori/IR24-mixed background. qRRE-9 was reduced to the single recessive Mendelian factor Alt-9. High-resolution genetic and physical maps were constructed for Alt-9 in a BC(3)F(2) population of 1,043 individuals. Alt-9 maps between RM24702 and ID47-2 on chromosome 9, and co-segregates with RM5765.

Identification of two novel phytosiderophores secreted by perennial grasses

It has been suggested that some perennial grasses secrete phytosiderophores in response to iron (Fe) deficiency, but the compounds have not been identified. Here, we identified and characterized the phytosiderophores secreted by two perennial grasses, Lolium perenne cv. Tove and Poa pratensis cv. Baron. Root exudates were collected from the roots of Fe-deficient grasses and then purified with various chromatographies. The structure of the purified compounds was determined using both nuclear magnetic resonance and fast atom bombardment mass spectrometry. Both species secreted phytosiderophores in response to Fe deficiency, and the amount of phytosiderophores secreted increased with the development of Fe deficiency. The type of phytosiderophores secreted differed with plant species; L. perenne cv. Tove secreted 3-epihydroxy-2'-deoxymugineic acid (epiHDMA), 2'-deoxymugineic acid (DMA) and an unknown compound, whereas P. pratensis cv. Baron secreted DMA, avenic acid A (AVA) and an unknown compound. Purification and subsequent analysis with nuclear magnetic resonance and mass led to identification of the two novel phytosiderophores; 3-hydroxy-2'-deoxymugineic acid (HDMA) from L. perenne, and 2'-hydroxyavenic acid A (HAVA) from P. pratensis. Both novel phytosiderophores have similar chelating activity to known phytosiderophores.

Role of root hairs and lateral roots in silicon uptake by rice

The rice plant (Oryza sativa L. cv Oochikara) is known to be a Si accumulator, but the mechanism responsible for the high uptake of Si by the roots is not well understood. We investigated the role of root hairs and lateral roots in the Si uptake using two mutants of rice, one defective in the formation of root hairs (RH2) and another in that of lateral roots (RM109). Uptake experiments with nutrient solution during both a short term (up to 12 h) and relatively long term (26 d) showed that there was no significant difference in Si uptake between RH2 and the wild type (WT), whereas the Si uptake of RM109 was much less than that of WT. The number of silica bodies formed on the third leaf in RH2 was similar to that in WT, but the number of silica bodies in RM109 was only 40% of that in WT, when grown in soil amended with Si under flooded conditions. There was also no difference in the shoot Si concentration between WT and RH2 when grown in soil under upland conditions. Using a multi-compartment transport box, the Si uptake at the root tip (0-1 cm, without lateral roots and root hairs) was found to be similar in WT, RH2, and RM109. However, the Si uptake in the mature zone (1-4 cm from root tip) was significantly lower in RM109 than in WT, whereas no difference was found in Si uptake between WT and RH2. All these results clearly indicate that lateral roots contribute to the Si uptake in rice plant, whereas root hairs do not. Analysis of F(2) populations between RM109 and WT showed that Si uptake was correlated with the presence of lateral roots and that the gene controlling formation of lateral roots and Si uptake is a dominant gene.

Role of root hairs and lateral roots in silicon uptake by rice

The rice plant (Oryza sativa L. cv Oochikara) is known to be a Si accumulator, but the mechanism responsible for the high uptake of Si by the roots is not well understood. We investigated the role of root hairs and lateral roots in the Si uptake using two mutants of rice, one defective in the formation of root hairs (RH2) and another in that of lateral roots (RM109). Uptake experiments with nutrient solution during both a short term (up to 12 h) and relatively long term (26 d) showed that there was no significant difference in Si uptake between RH2 and the wild type (WT), whereas the Si uptake of RM109 was much less than that of WT. The number of silica bodies formed on the third leaf in RH2 was similar to that in WT, but the number of silica bodies in RM109 was only 40% of that in WT, when grown in soil amended with Si under flooded conditions. There was also no difference in the shoot Si concentration between WT and RH2 when grown in soil under upland conditions. Using a multi-compartment transport box, the Si uptake at the root tip (0-1 cm, without lateral roots and root hairs) was found to be similar in WT, RH2, and RM109. However, the Si uptake in the mature zone (1-4 cm from root tip) was significantly lower in RM109 than in WT, whereas no difference was found in Si uptake between WT and RH2. All these results clearly indicate that lateral roots contribute to the Si uptake in rice plant, whereas root hairs do not. Analysis of F(2) populations between RM109 and WT showed that Si uptake was correlated with the presence of lateral roots and that the gene controlling formation of lateral roots and Si uptake is a dominant gene.

Prostatic expression of hensin, a protein implicated in epithelial terminal differentiation

OBJECTIVES

Hensin induces terminal differentiation in rabbit kidney collecting tubule cells. Rabbit hensin and human DMBT1 result from alternative splicing of the same gene. The human DMBT1 gene is located on chromosome 10q25-26, a region often deleted in prostate cancer. In this study we examined the potential role of this gene in terminal differentiation of prostate, as well as its role in prostatic carcinogenesis.

METHODS

We searched for deletions of this gene in prostatic cells cultured from cancer and benign tissues using PCR and cDNA cloning. The expression of hensin/DMBT1 in cultured cells and during prostate development was characterized by immunochemistry.

RESULTS

No deletions of hensin/DMBT1 similar to those found in glioblastomas, lung and esophageal cancers were observed in prostate cancer or BPH cells. Hensin/DMBT1 protein was localized in intracellular vesicles of epithelial cells in neonatal and 6-week-old mouse prostates. By 6 weeks, hensin/DMBT1 began to localize in the basal lamina of the prostate and vas deferens. In matured 6-month-old prostates, there was extensive deposition of hensin/DMBT1 in the basal lamina.

CONCLUSIONS

There is no evidence that hensin/DMBT1 is implicated in prostatic carcinogenesis. The localization of hensin/DMBT1 during maturation raises the possibility that hensin/DMBT1 is involved in terminal differentiation of the prostate and vas deferens.

Distribution and mobility of aluminium in an Al-accumulating plant, Fagopyrum esculentum Moench

Buckwheat (Fagopyrum esculentum Moench. cv. Jianxi) accumulates high concentrations of Al in the leaves without showing any toxicity. To understand the accumulation mechanism of Al in buckwheat, the distribution and mobility of Al in buckwheat were investigated. Relatively long-term treatment (28 d) with Al led to a decrease in Al concentration from old to young leaves, while a short-term (1 d) exposure to Al resulted in a uniform distribution of Al in the leaves. When the fourth leaf was wrapped inside a transparent plastic bag to suppress transpiration, the Al concentration of this leaf was only one-quarter of that in the corresponding leaf without wrapping. Within a leaf, the Al concentration at the margins was much higher than that in the centre. These results indicate that Al distribution in the leaves is controlled by both rate and duration of transpiration. The mobility of Al between old and new leaves was studied by first growing plants in a solution with Al, followed by culture in a solution without Al. The Al content in the two new leaves appeared after removal of external Al was very low, whereas that in the old leaves did not decrease but continued to increase. The increased Al content was found to be translocated from Al remaining in the roots. It is concluded that Al is not mobile once it is accumulated in the leaf.

Aluminium tolerance in plants and the complexing role of organic acids

The aluminium cation Al(3+) is toxic to many plants at micromolar concentrations. A range of plant species has evolved mechanisms that enable them to grow on acid soils where toxic concentrations of Al(3+) can limit plant growth. Organic acids play a central role in these aluminium tolerance mechanisms. Some plants detoxify aluminium in the rhizosphere by releasing organic acids that chelate aluminium. In at least two species, wheat and maize, the transport of organic acid anions out of the root cells is mediated by aluminium-activated anion channels in the plasma membrane. Other plants, including species that accumulate aluminium in their leaves, detoxify aluminium internally by forming complexes with organic acids.

Hydrogen peroxide sensitivity of catechol-2,3-dioxygenase: a cautionary note on use of xylE reporter fusions under aerobic conditions

Catechol-2,3-dioxygenase (C23O) of Pseudomonas putida, encoded by the xylE gene, was found to be sensitive to hydrogen peroxide (H(2)O(2)) when used as a reporter in gene fusion constructs. Exposure of Pseudomonas aeruginosa katA or katA katB mutants harboring katA- or katB-lacZ (encoding beta-galactosidase) or -xylE fusion plasmids to H(2)O(2) stimulated beta-galactosidase activity, while there was little or no detectable C23O activity in these strains. More than 95% of C23O activity was lost after a 5-min exposure to equimolar H(2)O(2), while a 10,000-fold excess was required for similar inhibition of beta-galactosidase. Electron paramagnetic resonance spectra of the nitrosyl complexes of C23O showed that H(2)O(2) nearly stoichiometrically oxidized the essential active-site ferrous ion, thus accounting for the loss of activity. Our results suggest using caution in interpreting data derived from xylE reporter fusions under aerobic conditions, especially where oxidative stress is present or when catalase-deficient strains are used.

Pattern of aluminum-induced secretion of organic acids differs between rye and wheat

Al-Induced secretion of organic acids from the roots has been considered as a mechanism of Al tolerance, but the processes leading to the secretion of organic acids are still unknown. In this study, the secretion pattern and alteration in the metabolism of organic acids under Al stress were examined in rye (Secale cereale L. cv King) and wheat (Triticum aestivum L. cv Atlas 66). Al induced rapid secretion of malate in the wheat, but a lag (6 and 10 h for malic and citric acids, respectively) between the exposure to Al and the secretion of organic acids was observed in the rye. The activities of isocitrate dehydrogenase, phosphoenolpyruvate carboxylase, and malate dehydrogenase were not affected by Al in either plant. The activity of citrate synthase was increased by the exposure to Al in the rye, but not in the wheat. The secretion of malate was not suppressed at low temperature in the wheat, but that of citrate was stopped in the rye. The Al-induced secretion of citrate from roots of the rye was inhibited by the inhibitors of a citrate carrier, which transports citrate from the mitochondria to the cytoplasm. All of these results suggest that alteration in the metabolism of organic acids is involved in the Al-induced secretion of organic acids in rye, but only activation of an anion channel seems to be responsible for the rapid secretion of malate in the wheat.

AnkB, a periplasmic ankyrin-like protein in Pseudomonas aeruginosa, is required for optimal catalase B (KatB) activity and resistance to hydrogen peroxide

In this study, we have cloned the ankB gene, encoding an ankyrin-like protein in Pseudomonas aeruginosa. The ankB gene is composed of 549 bp encoding a protein of 183 amino acids that possesses four 33-amino-acid ankyrin repeats that are a hallmark of erythrocyte and brain ankyrins. The location of ankB is 57 bp downstream of katB, encoding a hydrogen peroxide-inducible catalase, KatB. Monomeric AnkB is a 19.4-kDa protein with a pI of 5.5 that possesses 22 primarily hydrophobic amino acids at residues 3 to 25, predicting an inner-membrane-spanning motif with the N terminus in the cytoplasm and the C terminus in the periplasm. Such an orientation in the cytoplasmic membrane and, ultimately, periplasmic space was confirmed using AnkB-BlaM and AnkB-PhoA protein fusions. Circular dichroism analysis of recombinant AnkB minus its signal peptide revealed a secondary structure that is approximately 65% alpha-helical. RNase protection and KatB- and AnkB-LacZ translational fusion analyses indicated that katB and ankB are part of a small operon whose transcription is induced dramatically by H(2)O(2), and controlled by the global transactivator OxyR. Interestingly, unlike the spherical nature of ankyrin-deficient erythrocytes, the cellular morphology of an ankB mutant was identical to that of wild-type bacteria, yet the mutant produced more membrane vesicles. The mutant also exhibited a fourfold reduction in KatB activity and increased sensitivity to H(2)O(2), phenotypes that could be complemented in trans by a plasmid constitutively expressing ankB. Our results suggest that AnkB may form an antioxidant scaffolding with KatB in the periplasm at the cytoplasmic membrane, thus providing a protective lattice work for optimal H(2)O(2) detoxification.

Form of aluminium for uptake and translocation in buckwheat (Fagopyrum esculentum Moench)

The forms of Al for uptake by the roots and translocation from the root to the shoot were investigated in a buckwheat (Fagopyrum esculentum Moench, cv. Jianxi) that accumulates Al in its leaves. The Al concentration in the xylem sap was 15-fold higher in the plants exposed to AlCl3 than in those exposed to an Al-oxalate (1:3) complex, suggesting that the roots take up Al in the ionic form. The Al concentration in the xylem sap was 4-fold higher than that in the external solution after a 1-h exposure to AICl3 solution and 10-fold higher after a 2-h exposure. The Al concentration in the xylem sap increased with increasing Al concentration in the external solution. The Al uptake was not affected by a respiratory inhibitor, hydroxylamine, but significantly inhibited by the addition of La. These results suggest that Al uptake by the root is a passive process, and La3+ competes for the binding sites for Al3+ on the plasma membrane. The form of Al in the xylem sap was identified by 27Al-nuclear magnetic resonance analysis. The chemical shift of 27Al in the xylem sap was around 10.9 ppm, which is consistent with that of the Al-citrate complex. Furthermore, the dominant organic acid in the xylem sap was citric acid, indicating that Al was translocated in the form of Al-citrate complex. Because Al is present as Al-oxalate (1:3) in the root, the present data show that ligand exchange from oxalate to citrate occurs before Al is released to xylem.

Role of organic acids in detoxification of aluminum in higher plants

Phytotoxicity of aluminum ion (Al3+) is a serious problem limiting crop production on acid soils. Organic acids with Al-chelating ability play an important role in the detoxification of Al both externally and internally. Al is detoxified externally by the secretion of organic acids such as citric, oxalic, and/or malic acids from the roots. The secretion of organic acids is highly specific to Al and the site of secretion is localized to the root apex. The kind of organic acids secreted as well as secretion pattern differ among plant species. There are two patterns of Al-induced secretion of organic acids: In pattern I, there is no discernible delay between the addition of Al and the onset of the release of organic acids. Activation of the anion channel seems to be involved in this pattern; In pattern II, there is a marked lag phase between the addition of Al and the onset of organic acid release. The action of genes related to the metabolism and secretion of organic acids seems to be involved in this pattern. Internal detoxification of Al in Al-accumulating plants is achieved by the formation of Al-organic acid complex. For instance, the complex of Al-citrate (1:1) in hydrangea and Al-oxalate (1:3) in buckwheat has been identified.

Role of organic acids in detoxification of aluminum in higher plants

Phytotoxicity of aluminum ion (Al3+) is a serious problem limiting crop production on acid soils. Organic acids with Al-chelating ability play an important role in the detoxification of Al both externally and internally. Al is detoxified externally by the secretion of organic acids such as citric, oxalic, and/or malic acids from the roots. The secretion of organic acids is highly specific to Al and the site of secretion is localized to the root apex. The kind of organic acids secreted as well as secretion pattern differ among plant species. There are two patterns of Al-induced secretion of organic acids: In pattern I, there is no discernible delay between the addition of Al and the onset of the release of organic acids. Activation of the anion channel seems to be involved in this pattern; In pattern II, there is a marked lag phase between the addition of Al and the onset of organic acid release. The action of genes related to the metabolism and secretion of organic acids seems to be involved in this pattern. Internal detoxification of Al in Al-accumulating plants is achieved by the formation of Al-organic acid complex. For instance, the complex of Al-citrate (1:1) in hydrangea and Al-oxalate (1:3) in buckwheat has been identified.

Aluminum tolerance genes on the short arm of chromosome 3R are linked to organic acid release in triticale

Triticale, a hybrid between wheat and rye, shows a high degree of Al tolerance that is inherited from rye, but the mechanisms of high Al tolerance in both rye and triticale are unknown. We found that the short arm of chromosome 3R carries genes necessary for Al tolerance in triticale (x Triticosecale Wittmark cv Currency). Detailed comparative studies with a 3DS.3RL translocation line (ST22) and a non-substitution line (ST2) were conducted. Root elongation was similarly inhibited by Al in ST2 and ST22 during the first 12 h of Al treatment, but more strongly in ST22 than in ST2 at 18 h and thereafter. The root inhibition induced by other metals (Cu, Cd, and La) was similar between ST2 and ST22, suggesting that the action of the genes for Al tolerance on the short arm of triticale chromosome 3R is highly specific to Al. A 2-fold larger amount of malate and citrate was released from the roots of ST2 than from ST22 at 12 and 18 h after Al treatment, respectively. The marked lag phase in the inhibition of root elongation and the release of organic acids implies that the expression of genes on the short arm of triticale chromosome 3R is induced by Al, and that these genes are necessary for the release of organic acids.

Quorum sensing in Pseudomonas aeruginosa controls expression of catalase and superoxide dismutase genes and mediates biofilm susceptibility to hydrogen peroxide

Quorum sensing (QS) governs the production of virulence factors and the architecture and sodium dodecyl sulphate (SDS) resistance of biofilm-grown Pseudomonas aeruginosa. P. aeruginosa QS requires two transcriptional activator proteins known as LasR and RhlR and their cognate autoinducers PAI-1 (N-(3-oxododecanoyl)-L-homoserine lactone) and PAI-2 (N-butyryl-L-homoserine lactone) respectively. This study provides evidence of QS control of genes essential for relieving oxidative stress. Mutants devoid of one or both autoinducers were more sensitive to hydrogen peroxide and phenazine methosulphate, and some PAI mutant strains also demonstrated decreased expression of two superoxide dismutases (SODs), Mn-SOD and Fe-SOD, and the major catalase, KatA. The expression of sodA (encoding Mn-SOD) was particularly dependent on PAI-1, whereas the influence of autoinducers on Fe-SOD and KatA levels was also apparent but not to the degree observed with Mn-SOD. beta-Galactosidase reporter fusion results were in agreement with these findings. Also, the addition of both PAIs to suspensions of the PAI-1/2-deficient double mutant partially restored KatA activity, while the addition of PAI-1 only was sufficient for full restoration of Mn-SOD activity. In biofilm studies, catalase activity in wild-type bacteria was significantly reduced relative to planktonic bacteria; catalase activity in the PAI mutants was reduced even further and consistent with relative differences observed between each strain grown planktonically. While wild-type and mutant biofilms contained less catalase activity, they were more resistant to hydrogen peroxide treatment than their respective planktonic counterparts. Also, while catalase was implicated as an important factor in biofilm resistance to hydrogen peroxide insult, other unknown factors seemed potentially important, as PAI mutant biofilm sensitivity appeared not to be incrementally correlated to catalase levels.

Pseudomonas aeruginosa biofilm sensitivity to biocides: use of hydrogen peroxide as model antimicrobial agent for examining resistance mechanisms

The biofilm mode of bacterial growth may be the preferred form of existence in nature. Because of the global impact of problematic biofilms, study of the mechanisms affording resistance to various biocides is of dire importance. Furthermore, understanding the physiological differences between biofilm and planktonic organisms ranks particularly high on the list of important and necessary research. Such contributions will only serve to broaden our knowledge base, especially regarding the development of better antimicrobials while also fine-tuning the use of current highly effective antimicrobials. Using H2O2 as a model oxidizing biocide, we demonstrate the marked resistance of biofilm bacteria relative to planktonic cells. Because many biocides are good oxidizing agents (e.g., H2O2, HOCl), understanding the mechanisms by which genes involved in combating oxidative stress are activated is important in determining the overall efficacy of such biocides. Future studies will focus on determining mechanisms of oxidative stress gene regulation in bacterial biofilms.

Bacterioferritin A modulates catalase A (KatA) activity and resistance to hydrogen peroxide in Pseudomonas aeruginosa

We have cloned a 3.6-kb genomic DNA fragment from Pseudomonas aeruginosa harboring the rpoA, rplQ, katA, and bfrA genes. These loci are predicted to encode, respectively, (i) the alpha subunit of RNA polymerase; (ii) the L17 ribosomal protein; (iii) the major catalase, KatA; and (iv) one of two iron storage proteins called bacterioferritin A (BfrA; cytochrome b1 or b557). Our goal was to determine the contributions of KatA and BfrA to the resistance of P. aeruginosa to hydrogen peroxide (H2O2). When provided on a multicopy plasmid, the P. aeruginosa katA gene complemented a catalase-deficient strain of Escherichia coli. The katA gene was found to contain two translational start codons encoding a heteromultimer of approximately 160 to 170 kDa and having an apparent Km for H2O2 of 44.7 mM. Isogenic katA and bfrA mutants were hypersusceptible to H2O2, while a katA bfrA double mutant demonstrated the greatest sensitivity. The katA and katA bfrA mutants possessed no detectable catalase activity. Interestingly, a bfrA mutant expressed only approximately 47% the KatA activity of wild-type organisms, despite possessing wild-type katA transcription and translation. Plasmids harboring bfrA genes encoding BfrA altered at critical amino acids essential for ferroxidase activity could not restore wild-type catalase activity in the bfrA mutant. RNase protection assays revealed that katA and bfrA are on different transcripts, the levels of which are increased by both iron and H2O2. Mass spectrometry analysis of whole cells revealed no significant difference in total cellular iron levels in the bfrA, katA, and katA bfrA mutants relative to wild-type bacteria. Our results suggest that P. aeruginosa BfrA may be required as one source of iron for the heme prosthetic group of KatA and thus for protection against H2O2.

In vitro translation of a 2.3-kb splicing variant of the hamster pgp1 gene whose presence in transfectants is associated with decreased drug resistance

PURPOSE

P-glycoprotein (P-gp), a product of the Chinese hamster pgpl gene, confers multidrug resistance to mammalian cells in which it is overexpressed either by transfection or as a result of drug selection. It is encoded by a 4.3-kb mRNA and in its unglycosylated form has a predicted molecular weight of approximately 141 kDa. When a cDNA containing this sequence is transfected into drug-sensitive Chinese hamster lung cells and is expressed under the control of the beta-actin promoter, both the full-length 4.3-kb mRNA and a 2.3-kb transcript are produced. The latter results from a splicing event that utilizes near consensus 5' and 3' splicing signals resident in the full-length mRNA, and it has also been found to be present in cell lines that express the native gene. Therefore, it is a splicing product of pgpl per se. This report is concerned with the biological relevance of this transcript.

METHODS

In vitro transcription and translation experiments were used to show that the putative open reading frame of the 2.3-kb transcript encodes a novel 57-kDa protein (p57pgp1) that contains transmembrane domains 9-12 and the C-terminal ATP binding fold of P-gp. To elucidate the function of p57pgp1, expression vectors containing cDNAs representing (1) the 2.3-kb transcript, (2) the full-length 4.3-kb mRNA, and (3) a splice-disabled 4.3-kb transcript in which production of the 2.3-kb transcript is eliminated by an in-frame mutation at the 3' splice site, were constructed and transfected into DC-3F cells. Additional expression vectors in which p57pgp1 represented the N-terminus of a green fluorescent protein fusion construct were also prepared and used for transient expression studies.

RESULTS

Overexpression of the 2.3-kb transcript alone did not confer multidrug resistance. Transfectants in which both the 4.3-kb transcript and the 2.3-kb transcript were present, compared with transfectants in which no 2.3-kb transcript was expressed, but in which the level of expression of the 4.3-kb mRNA alone was the same, showed little change in cross-resistance pattern. However, the overall level of resistance in the latter cells was increased by approximately twofold. Hence the presence of the 2.3-kb transcript was associated with a decrease in drug resistance. In vitro transcription and translation experiments and transient expression studies indicate that p57pgp1 can be expressed both in vitro and in vivo.

CONCLUSION

These results demonstrate that a splicing variant of pgp1 contains an open reading frame capable of translation in vitro and in vivo and suggest that alterations in splicing may contribute both directly and indirectly to the overall mechanism of pgp1-mediated multidrug resistance in CHL cells.

Cloning and characterization of the Pseudomonas aeruginosa zwf gene encoding glucose-6-phosphate dehydrogenase, an enzyme important in resistance to methyl viologen (paraquat)

In this study, we cloned the Pseudomonas aeruginosa zwf gene, encoding glucose-6-phosphate dehydrogenase (G6PDH), an enzyme that catalyzes the NAD+- or NADP+-dependent conversion of glucose-6-phosphate to 6-phosphogluconate. The predicted zwf gene product is 490 residues, which could form a tetramer with a molecular mass of approximately 220 kDa. G6PDH activity and zwf transcription were maximal in early logarithmic phase when inducing substrates such as glycerol, glucose, or gluconate were abundant. In contrast, both G6PDH activity and zwf transcription plummeted dramatically when bacteria approached stationary phase, when inducing substrate was limiting, or when the organisms were grown in a citrate-, succinate-, or acetate-containing basal salts medium. G6PDH was purified to homogeneity, and its molecular mass was estimated to be approximately 220 kDa by size exclusion chromatography. Estimated Km values of purified G6PDH acting on glucose-6-phosphate, NADP+, and NAD+ were 530, 57, and 333 microM, respectively. The specific activities with NAD+ and NADP+ were calculated to be 176 and 69 micromol/min/mg. An isogenic zwf mutant was unable to grow on minimal medium supplemented with mannitol. The mutant also demonstrated increased sensitivity to the redox-active superoxide-generating agent methyl viologen (paraquat). Since one by-product of G6PDH activity is NADPH, the latter data suggest that this cofactor is essential for the activity of enzymes critical in defense against paraquat toxicity.

Mutations in the sixth transmembrane domain of P-glycoprotein that alter the pattern of cross-resistance also alter sensitivity to cyclosporin A reversal

The expression of a P-glycoprotein (Pgp1) cDNA encoding two amino acid substitutions in the sixth transmembrane domain of the protein (G338A339 to A338P339) confers a unique cross-resistance profile that displays preferential resistance to actinomycin D and diminished resistance to colchicine and daunorubicin. We report here that this multidrug-resistant phenotype is also insensitive to reversal by cyclosporin A (CsA) but not verapamil (VRP). However, the ability of VRP to increase the accumulation of [3H]vincristine is poor in both wild-type and mutant transfectants. In contrast, the accumulation of [3H]vincristine in wild-type versus mutant transfectants in the presence of CsA is dramatically increased. It is the substitution of the alanine residue at position 339 with proline that is primarily responsible for the lowered sensitivity to CsA and for the altered drug accumulation levels. Both substitutions are required to confer the unique cross-resistance profile of the double mutant, although each independently confers a specific profile of its own. These results indicate that alterations in Pgp1 structure can differentially affect the activity of CsA and VRP to mediate drug accumulation in multidrug-resistant cells and support the conclusion that the sixth transmembrane domain of the Pgp1 transporter plays important roles, in both the specificity of drug efflux and the sensitivity of the transporter to reversal agents.

Internal Detoxification Mechanism of Al in Hydrangea (Identification of Al Form in the Leaves)

An internal detoxification mechanism for Al was investigated in an Al-accumulating plant, hydrangea (Hydrangea macrophylla), focusing on Al forms present in the cells. The leaves of hydrangea contained as much as 15.7 mmol Al kg-1 fresh weight, and more than two-thirds of the Al was found in the cell sap. Using 27Al- nuclear magnetic resonance, the dominant peak of Al was observed at a chemical shift of 11 to 12 parts per million in both intact leaves and the extracted cell sap, which is in good accordance with the chemical shift for the 1:1 Al-citrate complex. Purification of cell sap by molecular sieve chromatography (Sephadex G-10) combined with ion-exclusion chromatography indicated that Al in fractions with the same retention time as citric acid contributed to the observed 27Al peak in the intact leaves. The molar ratio of Al to citric acid in the crude and purified cell sap approximated 1. The structure of the ligand chelated with Al was identified to be citric acid. Bioassay experiments showed that the purified Al complex from the cell sap did not inhibit root elongation of corn (Zea mays L.) and the viability of cells on the root tip surface was also not affected. These observations indicate that Al is bound to citric acid in the cells of hydrangea leaves.

Glucose stimulates alginate production and algD transcription in Pseudomonas aeruginosa

A previous study [DeVault et al. (1991) Mol. Microbiol. 5, 2503-2509] suggested that growth of Pseudomonas aeruginosa in glucose-containing medium represses algD gene transcription. In this study, growth of P. aeruginosa in rich medium containing glucose or gluconate increased alginate production and algD transcription at concentrations ranging from 1 to 5%.

Ferric uptake regulator (Fur) mutants of Pseudomonas aeruginosa demonstrate defective siderophore-mediated iron uptake, altered aerobic growth, and decreased superoxide dismutase and catalase activities

Pseudomonas aeruginosa is considered a strict aerobe that possesses several enzymes important in the disposal of toxic oxygen reduction products including iron- and manganese-cofactored superoxide dismutase and catalase. At present, the nature of the regulation of these enzymes in P. aeruginosa Is not understood. To address these issues, we used two mutants called A4 and C6 which express altered Fur (named for ferric uptake regulation) proteins and constitutively produce the siderophores pyochelin and pyoverdin. Both mutants required a significant lag phase prior to log-phase aerobic growth, but this lag was not as apparent when the organisms were grown under microaerobic conditions. The addition of iron salts to mutant A4 and, to a greater extent, C6 cultures allowed for an increased growth rate under both conditions relative to that of bacteria without added iron. Increased manganese superoxide dismutase (Mn-SOD) and decreased catalase activities were also apparent in the mutants, although the second catalase, KatB, was detected in cell extracts of each fur mutant. Iron deprivation by the addition of the iron chelator 2,2'-dipyridyl to wild-type bacteria produced an increase in Mn-SOD activity and a decrease in total catalase activity, similar to the fur mutant phenotype. Purified wild-type Fur bound more avidly than mutant Fur to a PCR product containing two palindromic 19-bp "iron box" regions controlling expression of an operon containing the sodA gene that encodes Mn-SOD. All mutants were defective in both ferripyochelin- and ferripyoverdin-mediated iron uptake. Two mutants of strain PAO1, defective in pyoverdin but not pyochelin biosynthesis, produced increased Mn-SOD activity. Sensitivity to both the redox-cycling agent paraquat and hydrogen peroxide was greater in each mutant than in the wild-type strain. In summary, the results indicate that mutations in the P. aeruginosa fur locus affect aerobic growth and SOD and catalase activities in P. aeruginosa. We postulate that reduced siderophore-mediated iron uptake, especially that by pyoverdin, may be one possible mechanism contributing to such effect.

Increased sensitivity of poliovirus detection in tap water concentrates by reverse transcriptase-polymerase chain reaction

This study developed a methodology to increase the sensitivity of enteric virus detection in tap water concentrates. Polymerase chain reaction (PCR) detection of virus in reduced volumes of virus-containing water concentrates was successful following removal of PCR inhibitory substances. Poliovirus 1 and coxsackievirus B3 were seeded into 378 l of tap water, concentrated with 1MDS filters, and reconcentrated by organic flocculation. The volume of concentrates was successfully reduced from 25 to 5 ml without loss of virus recovery. PCR detection of virus after treatment of a water concentrate (1.1 x 10(5)-fold concentration) with a Sephadex G-100 plus Chelex-100 column, or Sephadex G-50 plus Chelex-100 column, followed by heat treatment to release viral RNA, was compared with direct phenol-chloroform-isoamyl alcohol (PCI) extraction of viral RNA. The Sephadex G-50 plus Chelex-100 column did not remove inhibitory substances efficiently. The Sephadex G-100 plus Chelex-100 column could remove inhibitory substances, however, 99% of the viruses were also removed by the column. PCI extraction was found to be sufficient to remove inhibitory substances for reverse transcriptase (RT)-seminested PCR with a sensitivity of 0.2 plaque-forming units/10 microliters (0.2 PFU/l tap water).