Neighborhood disadvantage and parenting predict longitudinal clustering of uncinate fasciculus microstructural integrity and clinical symptomatology in adolescents.

Parenting behaviors and neighborhood environment influence the development of adolescents' brains and behaviors. Simultaneous trajectories of brain and behavior, however, are understudied, especially in these environmental contexts. In this four-wave study spanning 9-18 years of age (N=224 at baseline, N=138 at final assessment) we used longitudinal k-means clustering to identify clusters of participants with distinct trajectories of uncinate fasciculus (UF) fractional anisotropy (FA) and anxiety symptoms; we examined behavioral outcomes and identified environmental factors that predicted cluster membership. We identified three clusters of participants: 1) high UF FA and low symptoms ("low-risk"); 2) low UF FA and high symptoms ("high-risk"); and 3) low UF FA and low symptoms ("resilient"). Adolescents in disadvantaged neighborhoods were more likely to be in the resilient than high-risk cluster if they also experienced maternal warmth. Thus, neighborhood disadvantage may confer neural risk for psychopathology that can be buffered by maternal warmth, highlighting the importance of considering multiple environmental influences in understanding emotional and neural development in youth.

Progesterone receptor expression is associated with longer overall survival within high-grade histotypes of endometrial carcinoma: A Canadian high risk endometrial cancer consortium (CHREC) study.

OBJECTIVE: To assess the association of hormone receptor expression with outcome in high-grade endometrial carcinomas. METHODS: This study included three sites participating in the Canadian High Risk Endometrial Cancer (CHREC) consortium. Sections from tissue microarrays containing cases with a diagnosis of endometrioid grade 3 (EC3) and endometrial serous carcinoma (ESC) were assessed for estrogen (ER) and progesterone receptor (PR) expression by immunohistochemistry. Expression was considered present if >1% of tumor cell nuclei were labeled. Associations with overall survival were assessed. RESULTS: ER expression was present in 168/216 (78%) of EC3 and 124/192 (65%) of ESC. PR expression was present in 148/212 (70%) of EC3 and 83/196 (42%) of ESC. PR expression was significantly associated with favorable overall survival in EC3 and ESC (log rank, p=0.018 and p=0.0024) but ER expression was not. PR expression was significantly associated with favorable overall survival in EC3 independent of age, stage, center and lymph-vascular invasion (hazard ratio=0.457, 95% CI 0.257-0.811, p=0.0075) as well as in stage I and II ESC (hazard ratio=0.266, 95% CI 0.094-0.750, p=0.0123). CONCLUSION: Our data provide support for the assessment of the PR expression status in EC3 and ESC. Future work will be required to determine how PR expression may be incorporated into management of patients with EC3 and ESC.

Treatment related outcomes in high-risk endometrial carcinoma: Canadian high risk endometrial cancer consortium (CHREC).

OBJECTIVE: The lack of randomized clinical data pertaining to optimal surgery and adjuvant treatment in women with high-risk histotypes of endometrial cancer has resulted in selective management based on institutional policies. The objective of this study was to assess differences in treatment strategies and their outcomes among various institutions. METHOD: High-risk endometrial cancer cases (2000-2012) with corresponding clinicopathologic data were collected from 7 academic cancer centers. Histotypes included grade 3 endometrioid (EC3), serous (ESC), clear cell (CCC) and carcinosarcoma (CS). Associations with overall survival were performed using Cox proportional hazard regression. RESULTS: 1260 patients treated between 2000 and 2012 were included in the study: 398 EC3, 449 ESC, 91 CCC, 236 CS and 83 'other'. The use of adjuvant chemotherapy, adjuvant radiation, and extent of surgical staging were statistically different among the 7 centers (P<0.001). Histotype was independently associated with overall survival (OS) in patients with stage 1 and 2 disease who underwent surgical staging (P=0.0324). Adjuvant radiation was associated with improved OS for EC3 and CCC and adjuvant chemotherapy was associated with improved OS for ESC and CS. There was a high rate of recurrence (17.8% and 21.4%) in completely staged, stage 1A patients with ESC and CS respectively. CONCLUSION: There exists a wide variation in practice and outcomes for high-risk histotypes of endometrial cancer. The relative impact of adjuvant therapy appears to be histotype dependent and prospective studies examining adjuvant treatment in high-risk histotypes should use caution combining them together.

Peripheral telomere length and hippocampal volume in adolescents with major depressive disorder.

Several studies have reported that adults with major depressive disorder have shorter telomere length and reduced hippocampal volumes. Moreover, studies of adult populations without major depressive disorder suggest a relationship between peripheral telomere length and hippocampal volume. However, the relationship of these findings in adolescents with major depressive disorder has yet to be explored. We examined whether adolescent major depressive disorder is associated with altered peripheral telomere length and hippocampal volume, and whether these measures relate to one another. In 54 unmedicated adolescents (13-18 years) with major depressive disorder and 63 well-matched healthy controls, telomere length was assessed from saliva using quantitative polymerase chain reaction methods, and bilateral hippocampal volumes were measured with magnetic resonance imaging. After adjusting for age and sex (and total brain volume in the hippocampal analysis), adolescents with major depressive disorder exhibited significantly shorter telomere length and significantly smaller right, but not left hippocampal volume. When corrected for age, sex, diagnostic group and total brain volume, telomere length was not significantly associated with left or right hippocampal volume, suggesting that these cellular and neural processes may be mechanistically distinct during adolescence. Our findings suggest that shortening of telomere length and reduction of hippocampal volume are already present in early-onset major depressive disorder and thus unlikely to be only a result of accumulated years of exposure to major depressive disorder.

Canadian high risk endometrial cancer (CHREC) consortium: analyzing the clinical behavior of high risk endometrial cancers.

OBJECTIVES: The objective of this study is to analyze the clinical behavior of endometrial carcinomas by high risk(HR) histotype, including stage, overall survival, recurrence free survival and patterns of failure. METHODS: This is a retrospective multi-institutional cohort study performed at 7 tertiary care centers across Canada between 2000 and 2012 and included: grade 3 endometrioid (EC3), endometrial serous cancer (ESC), clear cell carcinomas (CCC) and carcinosarcoma (CS). Clinicopathological and outcome data was collected. RESULTS: 1260 women with endometrial carcinoma with 1013 having staging procedures were identified; 398 EC3, 449 ESC, 236 CS and 91 CCC. 51.8% had lymphovascular space invasion (LVSI) and 18.5% had omental involvement with a statistically significant difference between tumor types (p=0.0005 and 0.0047 respectively); ESC had a significantly greater rate of omental involvement compared to EC3 (22% to 9%, p=0.0005). Within the entire cohort 49.3% were stage 1, 10.6% were stage 2, 27.4% were stage 3 and 12.7% were stage 4. Overall survival and recurrence free survival were significantly different between histotypes (p<0.0001) with CS having the worst outcome. Overall 31.5% of patients recurred. CS and ESC had a higher distant recurrence rate compared to EC3 (29.6%, 31.0% compared to 16.4%, p=0.0002 and p<0.001). CONCLUSION: This study is one of the largest clinical cohorts of HR endometrial cancers. We have further clarified the impact of histotype and stage on recurrence and survival, and the high likelihood of distant recurrence. However, the differences are modest and risk prediction models will require additional molecular markers.

The development and evolution of full thickness macular hole in highly myopic eyes.

PURPOSE: To evaluate the morphological changes before and after the formation of a full-thickness macular hole (MH) in highly myopic eyes. PATIENTS AND METHODS: Retrospective observational case series. From 2006 to 2013, clinical records of patients with MH and high myopia who had optical coherence tomography (OCT) before the development of MH were reviewed. All patients had been followed for more than 1 year since MH formation to observe the morphological changes. RESULTS: Twenty-six eyes of 24 patients were enrolled. The initial OCT images could be classified into four types: (1) normal foveal depression with abnormal vitreo-retinal relationship (eight cases), (2) macular schisis without detachment (six cases), (3) macular schisis with concomitant/subsequent detachment (nine cases), and (4) macular atrophy with underlying/adjacent scar (three cases). After MH formation, one case in type 1 and one case in type 4 group developed retinal detachment (RD). In type 2 group, four cases developed RD at the same time of MH formation. The preexisting detachment in type 3 group extended in eight cases and improved in one case. Among all the cases, 14 eyes received vitrectomy and 7 eyes received gas injection. MH sealed in nine eyes after vitrectomy and four eyes by gas injection. CONCLUSION: The study revealed four pathways of MH formation in highly myopic eyes. MH from macular schisis tended to be associated with detachment. However, the evolution and the results of surgical intervention were not always predictable.

Photodynamic therapy combined with posterior subtenon triamcinolone acetonide injection in the treatment of choroidal neovascularization.

PURPOSE: To evaluate the therapeutic effect of photodynamic therapy (PDT) combined with posterior subtenon injection of triamcinolone acetonide (PSTA) in the treatment of choroidal neovascularization (CNV). METHODS: In this retrospective case-control study, treatment outcomes at 12 months of patients with CNV were reviewed. One hundred and two consecutive patients (102 eyes) with subfoveal CNV of various causes were included. Patients in the study group (n=46) received PDT followed within 2 days by 40 mg of PSTA. Patients in the control group (n=56) received PDT alone. Patients were retreated 3 months later or more if fluorescein angiography showed residual membrane leakage. Treatment outcomes were compared between the two groups and among different CNV subgroups. RESULTS: Gain in mean best-corrected visual acuity (BCVA) was significantly higher in the study group (+0.78 lines) than in the control group (-1.86 lines) (P<0.0001). The number of treatments within 1 year was significantly less in the study group (1.26 vs 1.63, P=0.008). The mean BCVA change for myopic CNV and age-related predominantly classic CNV subgroups was significantly higher in the study group (+2.82 vs -0.91 lines, P=0.0005 for myopic CNV; +0.6 vs -1.79 lines, P=0.01 for age-related predominantly classic CNV). The main side effect in the study group was increased intraocular pressure (8.7%). CONCLUSION: Compared with PDT alone, PDT combined with PSTA has a better therapeutic effect for both myopic and age-related predominantly classic CNV; the myopic CNV subgroup shows the best response.

Peripapillary intrachoroidal cavitation in high myopia: reappraisal.

PURPOSE: To evaluate optical coherence tomography (OCT) and clinical findings of a peripapillary lesion in high myopia recently named peripapillary detachment in pathologic myopia (PDPM) or intrachoroidal cavitation. METHODS: Observational case report by chart review, analysis of colour fundus photography, fluorescein angiography, and OCT in 16 eyes of 12 patients with myopic degeneration and the presence of a slightly elevated, patchy peripapillary, yellow-orange lesion on the fundus. RESULTS: Patients were mean age 53.1+/-10.7 years, with a spherical-equivalent refractive error of -10.99+/-3.33 D and mean axial length of 27.34+/-1.44 mm. The mean best-corrected visual acuity was log MAR 0.3+/-0.2 (between 20/100 and 20/20). Six eyes also showed myopic maculopathy. In 13 eyes, OCT showed an intrachoroidal hyporeflective space located below the normal plane of the retinal pigment epithelium. Six of these 13 eyes were found to have apparent communication between the intrachoroidal cavity and the vitreous space at the junction of the lesion and the myopic conus. In three eyes, OCT revealed intrachoroidal splitting. The fluorescein angiogram showed early hypofluorescence, without pooling or staining in late phase. CONCLUSIONS: The yellow-orange elevated patchy lesions adjacent to the peripapillary conus in high myopic eyes may represent either intrachoroidal cavitation or choroidal schisis, which may be different stages of one disease spectrum. Vitreous fluid may be the source of the disruption of choroid and fluid accumulation.

Anatomical and functional outcome of surgery of primary rhegmatogenous retinal detachment in high myopic eyes.

PURPOSE: To analyse the anatomical and functional outcome of surgery for primary rhegmatogenous retinal detachment (RRD) in highly myopic eyes. METHODS: We retrospectively reviewed the medical records of 111 high myopic patients (111 eyes) with primary RRD treated by scleral buckling or pars plana vitrectomy in a tertiary referral university hospital. The postoperative retinal status and best-corrected visual acuity were recorded. Risk factors including age, refractive error, duration of retinal detachment, preoperative visual acuity, extent of detachment, and intraoperative and postoperative complications were evaluated. Multiple logistic regression analysis was used to determine the independent correlation of each variable on anatomical and functional outcome. RESULTS: Primary surgery resulting in retinal reattachment was achieved in 96 (86.5%) eyes with more than 6 months follow-up (range, 6-60 months). Sixty-eight (61.3%) eyes had postoperative corrected visual acuity 20/50 or more. Postoperative complications in high myopic eyes were variable, and the most common was cataract progression (19.8%). Upon multiple logistic regression analysis, young patients had significantly better anatomical outcome, although the variables including less refraction error, better preoperative visual acuity, scleral buckling procedure, and less surgical intervention showed better functional outcome in our series. CONCLUSIONS: The anatomical outcome of surgery for primary RRD in highly myopic eyes was favourable, and young patients tended to have a higher success rate. Functional outcome was significantly correlated with refractive error, preoperative visual acuity, surgical procedure, and number of vitreoretinal surgery.

PEDF induces p53-mediated apoptosis through PPAR gamma signaling in human umbilical vein endothelial cells.

OBJECTIVE: Pigment epithelial-derived factor (PEDF) is a potent anti-angiogenic factor whose effects are partially mediated through the induction of endothelial cell apoptosis. The pathway mediating endothelial cell apoptosis has not been fully established. Here we investigated the participation of peroxisome proliferator-activated receptor gamma (PPARgamma) and p53 in the apoptosis of human umbilical vein endothelial cells (HUVECs). METHODS AND RESULTS: HUVECs pretreated with either PPARgamma antagonist or PPARgamma small interfering RNA (siRNA) suppressed PEDF-induced apoptosis as determined by TUNEL assay, annexin V-FITC/PI staining, and cleavage of procaspase-8, -9, -3. PEDF sequentially induced PPARgamma and p53 expression as observed in immunoblotting and immunofluoresence assays. PEDF also increased the transcriptional activity of PPARgamma as evident from electromobility shift assays, and p53 as determined by the phosphorylation and acetylation of p53 and the induction of Bax. The induction of p53 by PEDF was abolished by either PPARgamma antagonist or PPARgamma siRNA. PEDF-mediated HUVEC apoptosis and cleavage of procaspases were significantly attenuated by p53 siRNA. CONCLUSIONS: Our observations indicate that PEDF induces HUVECs apoptosis through the sequential induction of PPARgamma and p53 overexpression. With the growing interest in anti-angiogenesis as a novel approach to cancer therapy, defining the mechanism of PEDF-mediated HUVEC apoptosis may facilitate the development of new therapeutics.

Peroxisome proliferator-activated receptor-gamma agonists cause growth arrest and apoptosis in human ovarian carcinoma cell lines.

Peroxisome proliferator-activated receptor gamma (PPARgamma) is a member of the nuclear hormone receptor superfamily of ligand-activated transcription factors. PPARgamma agonists inhibit the growth of many types of cancers. To our knowledge, the effect of PPARgamma agonist on ovarian tumors is not reported. In this study, we used two human ovarian carcinoma cell lines (ES-2 and PA-1) to examine the effects of the PPARgamma agonists troglitazone (TGZ) and ciglitazone (CGZ) on cell survival. CGZ and TGZ inhibited viability in a dose-dependent manner in both types of ovarian cancer cells. The agonists also decreased cellular proliferation in association with an increase in the number of cells arrested in the G0/G1 phase of the cell cycle. Moreover, they increased apoptosis while increasing caspase-3 activity. Incubation of both the cell lines with the PPARgamma agonists led to upregulated PPARgamma expression. This effect appeared to be PPARgamma independent because the PPARgamma antagonist GW9662 did not reverse it. Along with the induction of apoptosis in ovarian cancer cells, protein expression levels of p53 and Bax markedly increased in response to the PPARgamma agonists. Our results demonstrated that PPARgamma agonists inhibited the viability of human ovarian cancer cells, at least partly by inducing apoptosis. As a result, these agonists may serve as future drugs for the prevention and treatment of ovarian cancer.

Characteristics of primary rhegmatogenous retinal detachment in Taiwan.

PURPOSE: To investigate the epidemiological characteristics and related risk factors for primary rhegmatogenous retinal detachment (RRD) in Taiwan. METHODS: The case-control study was based on retrospective chart review of hospital patients treated for primary RRD from 1995 to 2001, inclusively. The preoperative fundus findings and refractive status were collected for each patient. Controls were selected from a nationwide survey of visual impairment in the adult population during the same period. Risk factors for RRD were analysed by logistic regression. A total of 1032 RRD cases and 3537 controls were enrolled for the study. RESULTS: A pronounced bipeak pattern was evident in the age distribution for primary RRD in the third and sixth decades of life. Atrophic hole with lattice degeneration was preferential to younger (20-30 years) and highly myopic individuals (-7.4+/-5 D), whereas the flap tear tended to occur in middle-aged individuals (50-60 years) and those with moderate myopia (-4.1+/-5 D). The odds ratio for primary RRD with myopia, male gender, and older age (>40 years) were 1.33/D, 2.15, and 1.69, respectively. CONCLUSIONS: Myopia is an important RRD risk factor for young Taiwanese. The increasing prevalence of myopia has predisposed the young population to RRD.

Transpupillary thermotherapy for the treatment of choroidal neovascularization in age-related macular degeneration in Taiwan.

PURPOSE: To evaluate the therapeutic outcome and the recurrence of choroidal neovascularization (CNV) secondary to age-related macular degeneration (AMD) after transpupillary thermotherapy (TTT) in light-brown retinas. METHODS: A retrospective, non-randomized study of 58 eyes in 55 patients with subfoveal CNV treated with TTT was conducted. Power settings were set about half the value for Caucasian eyes. The outcome was assessed with best-corrected visual acuity, fluorescein angiography, indocyanine green angiography, and fundoscopic examination. RESULTS: Forty-four membranes were occult, six classic, and eight mixed. Mean follow-up was 16.6+/-10.7 months (range: 6-48 months). Membranes closed in 46 eyes. Iatrogenic complications included three subretinal haemorrhage, two retinal pigment epithelium tears, and two macular area cystic changes. In eyes with occult CNV, visual acuity improved in six (13.6%), 14 (31.8%) remained unchanged, and 24 (54.6%) deteriorated. For various CNV, average logMAR changes from baseline at last follow-up were 0.30 in occult, -0.08 in classic, and 0.59 in mixed (P<0.01). Thirty eyes experienced recurrence within 9.2+/-6.2 months (range: 2-22 months). Cumulative recurrence rate was 45% at 12 months and 71% at 22 months, with no significant difference between occult and non-occult type CNV. CONCLUSIONS: Transpupillary thermotherapy does not cure CNV secondary to AMD. High recurrence was found independent of CNV type. Most improved vision was found mostly in classic CNV. Complications associated with high energy level should be considered in light-brown retinas.

Activation of mitogen-activated protein kinases is essential for hydrogen peroxide -induced apoptosis in retinal pigment epithelial cells.

Retinal pigment epithelial (RPE) cells are constantly exposed to oxidative injury while clearing byproducts of photoreceptor turnover, a circumstance thought to be responsible for degenerative retinal diseases. The mechanisms of hydrogen peroxide (H(2)O(2))-induced apoptosis in RPE cells are not fully understood. We studied signal transduction mechanisms of H(2)O(2)-induced apoptosis in the human RPE cell line ARPE-19. Activation of two stress kinases (JNK and p38) occurs during H(2)O(2) stimulation, and H(2)O(2)-mediated cell death was significantly reduced by their specific inhibition. Exposure to a lethal dose of H(2)O(2) elicited Bax translocation to the mitochondria and release of apoptosis-inducing factor (AIF) from the mitochondria, both of which were abolished by either JNK- or p38-specific inhibitors. Both H(2)O(2)-induced cell death and JNK/p38 phosphorylation were partially inhibited by C. difficile toxin B, inhibitor of Rho, Rac, and cdc42. Use of pull-down assays revealed that the small GTPase activated by H(2)O(2) is Rac1. This study is the first to demonstrate that H(2)O(2) induces a Rac1/JNK1/p38 signaling cascade, and that JNK and p38 activation is important for H(2)O(2)-induced apoptosis as well as AIF/Bax translocation of RPE cells.

Visual outcomes for high myopic patients with or without myopic maculopathy: a 10 year follow up study.

AIM: To evaluate the visual outcomes for high myopic patients aged 40 years and older with or without myopic maculopathy. METHODS: 552 high myopic (spherical equivalent < or =-6.0D or axial length > or =26.5 mm) patients were enrolled in the study, 230 cases with myopic maculopathy (at least lacquer cracks were identified) and 322 cases without maculopathy. The initial and final visual acuity (VA) (after 10 years) was compared between two groups. Additionally, the relation between sex, age, refraction, and axial length was analysed to find out the possible risk factors associated with visual outcome in myopic maculopathy. RESULTS: In 92% of patients aged 40-49, final VA was better than 20/40 after 10 years of follow up. However, it was less than 40% in those older than 60 years. For more than 50% of patients older than 40 years of age with maculopathy, their vision had decreased more than two lines in Snellen VA after 10 years of follow up, compared to only 4.3% of analogues without myopic maculopathy. Patchy atrophy and choroidal neovascularisation in myopic macular degeneration groups showed poorer visual outcome than lacquer cracks in the macular lesion group. Other prognostic factors of visual outcomes were myopic refraction, axial length, and ageing. CONCLUSIONS: Clearly, prognosis for patients with maculopathy is poorer than for those without maculopathy. Refractive status, axial length, and ageing are the main factors involved in determining the visual outcomes. The macular grading also affects the visual outcome for high myopic patients.

Long-term visual prognosis of infantile-onset high myopia.

PURPOSE: To investigate the clinical course and changes of refractive status in infantile-onset myopic children who received fully corrected glasses and to determine their visual prognosis. METHODS: In all, 57 children with infantile-onset high myopia (spherical equivalent over -5.0 D prior to the age of 5 years) were included in this study. All children received initial full-correction glasses at the mean age of 3.52 years. The cycloplegic refraction, axial length, and the best-corrected visual acuity were collected every 6 months. The mean follow-up time was 9.36 years. RESULTS: We noted that the tendency toward progression or regression of myopia appeared to be related to the degree of refractive error. Lower grades of high myopia (-5.0 to -7.75 D) showed a greater tendency to progress than those of the highest initial myopic refraction level (< or = -11.0 D). While the latter group exhibited a more-substantial regression rate than those cases of the lower initial refraction level. About 80% of infantile-onset high myopes demonstrated a final best-corrected vision of greater than 20/40, with 37% of children revealing a best-corrected vision level even better than 20/25. CONCLUSION: Clinical course of infantile high myopia is different to school myopia. Usually, higher degree of high myopia showed a stable state of myopia, or even possible regression, whereas the lower grades of high myopia revealed a strong tendency to progress.

Modeling of mercury sorption by activated carbon in a confined, a semi-fluidized, and a fluidized bed.

A process model was developed to simulate elemental mercury sorption by activated carbon in three distinct beds, namely a confined, a semi-fluidized, and a fluidized bed. The model involved the coupling of a kinetic model based on the mechanisms of surface equilibrium and external mass transfer, and a material balance model based on the tank-in-series approach. For surface equilibrium, three different equilibrium laws were used in the model, namely the Henry's Law, the Langmuir isotherm and the Freundlich isotherm. Literature mercury sorption data were used to determine the best-fit values of parameters for these equilibrium expressions. The parameter-fitted model was then used to simulate mercury sorption processes in the three distinct beds. The simulation parameters were mercury concentration, gas flow rate, adsorption temperature and the degree of semi-fluidization. The simulation results have indicated that the model is capable of describing the literature available mercury sorption data. All the three surface equilibrium laws appear to simulate the adsorption profiles equally well mainly because the sorption process occurs in an extremely low concentration range. The simulation results for the three distinct beds have suggested that the confined bed has the best mercury control performance; however, it generates the highest pressure-drop across the bed. A fluidized bed creates the least pressure drop; however, its sorption performance is poor. A semi-fluidized bed offers acceptable performance with affordable pressure-drops and can be a practical candidate for the process.

Simultaneous capture of metal, sulfur and chlorine by sorbents during fluidized bed incineration.

Metal capture experiments were carried out in an atmospheric fluidized bed incinerator to investigate the effect of sulfur and chlorine on metal capture efficiency and the potential for simultaneous capture of metal, sulfur and chlorine by sorbents. In addition to experimental investigation, the effect of sulfur and chlorine on the metal capture process was also theoretically investigated through performing equilibrium calculations based on the minimization of system free energy. The observed results have indicated that, in general, the existence of sulfur and chlorine enhances the efficiency of metal capture especially at low to medium combustion temperatures. The capture mechanisms appear to include particulate scrubbing and chemisorption depending on the type of sorbents. Among the three sorbents tested, calcined limestone is capable of capturing all the three air pollutants simultaneously. The results also indicate that a mixture of the three sorbents, in general, captures more metals than a single sorbent during the process. In addition, the existence of sulfur and chlorine apparently enhances the metal capture process.

Effects of genomic length on translocation of hepatitis B virus polymerase-linked oligomer.

Accurate translocation of the polymerase-linked oligomer to the acceptor site (DR1*) in reverse transcription is crucial for maintaining the correct size of the hepatitis B virus (HBV) genome. Various sizes of foreign sequences were inserted at different sites of the HBV genome, and their effects on accurate translocation of polymerase-linked oligomer to DR1* were tested. Three types of replicate DNA products were observed in these insertion mutants: RC (relaxed circle) and type I and type II DL (duplex linear) DNA. Our results indicated that the minus strand of RC and type I DL form was elongated from DR1*, while the minus strand of the type II DL form was elongated from multiple internal acceptor sites (IAS), such as IAS2. These IASs were also found to be used by wild-type HBV but with a very low frequency. Mutation of IAS2 by base substitution abrogated polymerase-linked oligomer transferring to IAS2, demonstrating that base pairing also plays an important role in the function of IAS2 as a polymerase-linked oligomer acceptor site. Data obtained from our insertion mutants also demonstrate that the distance between the polymerase-linked oligomer priming site and the acceptor is important. The polymerase-linked oligomer prefers to translocate to an acceptor, DR1* or IAS2, which are ca. 3.2 kb apart. However, it will translocate to both DR1* and IAS2 if they are not located 3.2 kb apart. These results suggest that the polymerase-linked oligomer may be able to scan bidirectionally for appropriate acceptor sites at a distance of 3.2 kb. A model is proposed to discuss the possible mechanism of polymerase-linked oligomer translocation.