Impact of metformin on neocortical development during pregnancy: Involvement of ERK and p35/CDK5 pathways

Metformin, the most commonly prescribed drug for the treatment of diabetes, is increasingly used during pregnancy to address various disorders such as diabetes, obesity, preeclampsia, and metabolic diseases. However, its impact on neocortex development remains unclear. Here, we investigated the direct effects of metformin on neocortex development, focusing on ERK and p35/CDK5 regulation. Using a pregnant rat model, we found that metformin treatment during pregnancy induces small for gestational age (SGA) and reduces relative cortical thickness in embryos and neonates. Additionally, we discovered that metformin inhibits neural progenitor cell proliferation in the sub-ventricular zone (SVZ)/ventricular zone (VZ) of the developing neocortex, a process possibly mediated by ERK inactivation. Furthermore, metformin induces neuronal apoptosis in the SVZ/VZ area of the developing neocortex. Moreover, metformin retards neuronal migration, cortical lamination, and differentiation, potentially through p35/CDK5 inhibition in the developing neocortex. Remarkably, compensating for p35 through in utero electroporation partially rescues metformin-impaired neuronal migration and development. In summary, our study reveals that metformin disrupts neocortex development by inhibiting neuronal progenitor proliferation, neuronal migration, cortical layering, and cortical neuron maturation, likely via ERK and p35/CDK5 inhibition. Consequently, our findings advocate for caution in metformin usage during pregnancy, given its potential adverse effects on fetal brain development.

Dinaciclib inhibits the growth of acute myeloid leukemia cells through either cell cycle-related or ERK1/STAT3/MYC pathways

Although immature differentiation and uncontrolled proliferation of hematopoietic stem cells are thought to be the primary mechanisms of acute myeloid leukemia (AML), the pathophysiology in most cases remains unclear. Dinaciclib, a selective small molecule targeting multiple cyclin-dependent kinases (CDKs), is currently being evaluated in oncological clinical trials. Despite the proven anticancer potential of dinaciclib, the differential molecular mechanisms by which it inhibits the growth of different AML cell lines remain unclear. In the current study, we treated HL-60 and KG-1 AML cell lines with dinaciclib and investigated the potential mechanisms of dinaciclib-induced AML cell growth inhibition using flow cytometry and western blotting assays. Data from HL-60 and KG-1 AML cells were validated using human primary AML cells. The results showed that the growth inhibitory effect of dinaciclib was more sensitive in HL-60 cells (IC50: 8.46 nM) than in KG-1 cells (IC50: 14.37 nM). The protein decline in Cyclin A/B and CDK1 and cell cycle arrest in the G2/M phase were more profound in HL-60 cells, corresponding to its growth inhibition. Although the growth inhibition of KG-1 cells by dinaciclib was still pronounced, the cell cycle-associated proteins were relatively insensitive. In addition to cell cycle regulation, the activation/expression of ERK1/STAT3/MYC signaling was significantly reduced by dinaciclib in KG-1 cells compared with that in HL-60 cells. Regarding the results of primary AML cells, we observed ERK1/STAT3/MYC inhibition and cell cycle regulation in different patients. These findings suggest that the cell cycle-associated and ERK1/STAT3/MYC signaling pathways might be two distinct mechanisms by which dinaciclib inhibits AML cells, which could facilitate the development of combination therapy for AML in the future.

367 Combinational use of sodium butyrate and phytogenics on intestinal health of nursery pigs

The effects of encapsulated sodium butyrate (SB), phytogenics (PH), or a combination were studied on intestinal health of nursery pigs. Phytogenics were blends of dry herbs and essential oil components. Forty-eight weaned pigs (21-d-old; 6.9 ± 0.6 kg BW) were individually housed, blocked by initial BW and sex, allotted to 4 dietary treatments (n = 12) in a RCBD, and fed for 33-d (P1: 0–7; P2: 7–19; and P3: 19–33). Treatments were arranged by 2 factors: SB (P1: 0.2% and P2: 0.1%) and PH (P3: 0.033%). Diets were formulated to meet or exceed NRC (2012) nutrient requirements and pigs were fed ad libitum. For each phase, ADG, ADFI, and G:F were measured. Fecal scores were assessed during d 3–19 and d 26–33. Blood samples were drawn in P2 and P3 to measure tumor necrosis factor alpha (TNF-α), IL-6, and immunoglobulin G (IgG). Four pigs at P2 and 8 pigs in P3 from each treatment were euthanized to collect jejunal tissue, jejunal mucosa, and ileal digesta to measure gut histology, TNF-α, IL-6, myeloperoxidase (MPO), malondialdehyde (MDA), and protein carbonyl. Data were analyzed using PROC MIXED of SAS. Fixed effects were treatments and random effects were blocks. In P2 and P1-2, SB decreased (P < 0.05) ADFI whereas no effect on ADG and G:F. In P2, SB tended to decrease (P = 0.063) villus height to crypt depth ratio (VH:CD) whereas increased (P < 0.05) enterocyte proliferation in P3. In P3 and overall, PH increased (P < 0.05) G:F. No changes were found in TNF-α, IL-6, MPO, MDA, IgG, and protein carbonyl. Conclusively, SB and a combinational use of SB and PH showed minimal effects on growth performance and gut health when added to the diets of nursery pigs. However, PH supplementation increased feed efficiency of nursery pigs during 19–33 d post-weaning.

126 Evaluation of true ileal amino acid digestibility of fermented soybean meal fed to nursery pigs

Fermented soybean meal (FSBM) has smaller peptides and reduced anti-nutritional factors compared with those in conventional SBM. Apparent and true ileal digestibilities (AID and TID) of AA in FSBM were measured using both a direct method and a substitution method. Forty eight (24 barrows and 24 gilts) pigs at 7 kg BW were allotted to 4 dietary treatments (n = 12) based on a randomized complete block design with sex and initial body weight as blocks. Treatments includes NFD (semi-purified N free diet to measure endogenous AA loss), NFSB (NFD with 20% FSBM; Genebiotech Co., Ltd. and Nutraferma, Inc), CBD (corn basal diet), and CBSB (CBD at 80% and FSBM at 20%). NFD and NFSB were used to directly measure AID and TID AA of FSBM, whereas NFD, CBD, and CBSB were used to indirectly calculate AID and TID AA of FSBM using a substitution method. Experimental diets included TiO2 (0.4%). Pigs were fed experimental diets for 10 days. Feed allowance was based on 0.09 x BW0.75 kg per day. All pigs were euthanized at the end of the experiments to collect ileal digesta. Diets and ileal digesta were used to quantify TiO2 and AA. Data were analyzed using Mixed Procedure of SAS 9.4. Dietary treatment was the main effect and blocks were random effects. Endogenous AA loss was 2.48 g. When measured by a direct method, AID and TID of Lys, Met, Thr, and Trp were 72.1 and 89.8%, 74.9 and 92.1%, 61.0 and 88.5%, and 72.2 and 92.2%, respectively. When measured by a substitution method, AID and TID of Lys, Met, Thr, and Trp were 64.7 and 84.4%, 60.5 and 77.9%, 36.2 and 57.0%, and 58.2 and 81.0%, respectively. Overall, a direct method showed higher AID and TID AA in FSBM than those measured by a substitution method.

[Investigation of the cognition and behavior on drug safety in Beijing middle school students]

OBJECTIVE

To understand the cognition and behavior of drug safety in Beijing middle school students and provide advice for relevant education.

METHODS

A cross-sectional survey using paper questionnaires was carried out on the student body of nine Beijing middle schools. Multi-stage proportionate stratified cluster sampling was adopted to enroll participants. In addition to demographic questions, the questionnaire included 17 questions assessing the cognition and behavior of safe drug use, prioritizing questions that aligned with the health education guideline for primary and secondary school students from Chinese Ministry of Education. Descriptive statistical methods were applied using the SAS 9.2 software.

RESULTS

Of the 4 220 students investigated, 2 097(49.7%) were males and 2 123(50.3%) were females. The average age was (14.3±1.7) years. 2 030(48.1%) students were from downtown areas, 1 511(35.8%) were from urban-rural linking areas and 679(16.1%) were from rural areas. Half (51.5%) of the respondents were junior high school students, and the others were from senior high schools (34.2%) and vocational high schools (14.3%). Most of the students (89.6%) lived off campus. The awareness rate of drug safety knowledge was 74.4%, the median score of drug safety behavior was 4 points (full score was 5 points) and there was a statistically positive correlation between the two (Spearman's correlation coefficient was 0.156, P<0.001). Both the awareness rates and the drug safety behavior scores were statistically different among the students in different regions, different school types and different residence types (P<0.001). Multiple factors analysis demonstrated the correlation between the cognition degrees of both drug safety knowledge, behavior and the above factors. Of all the students, 80.4% agreed that any drug could have adverse drug reactions; 40.5% were aware that antibiotics couldn't kill viruses; as many as 49.6% mistook aspirin as antibiotic; 97.4% would read drug instructions before taking them; Only 42.4% put expired drugs into special recycling bins; 49.8% would deviate from the suggested dosage and frequency of their medication when they were sick with common diseases.

CONCLUSION

Overall, the cognition of drug safety in Beijing middle school students is good, but problems still exist in medication adherence, the management of expired drugs and the antibiotics cognition, which need to be fixed through specific, pointed way of education. And more efforts should be made to improve the cognition in rural regions, vocational high schools and on campus students.

Abstract P5-16-09: Overall survival of patients with non-metastatic triple negative breast cancer who received neoadjuvant vs adjuvant chemotherapy: Cohort analysis of National cancer data base (NCDB) 2010 - 2011

Background: One of the benefits of neoadjuvant approach to the treatment of breast cancer is early microscopic disease control, which should translate to improved survival. However, clinical trials have not yet shown a survival benefit for neoadjuvant approach in even high risk patients, such as triple negative cases. Few studies have been performed outside of clinical trials.

Purpose: The objective of our study was to compare the overall survival of Stage I-III triple negative breast cancer patients who received neoadjuvant vs adjuvant chemotherapy within the NCDB, a prospectively collected, large, nationwide, hospital-based cancer outcomes database which contains information for more than 1,500 Commission on Cancer-accredited cancer programs in the U.S.

Patient and Method: We identified a cohort of women, aged &gt; 18 year-old at diagnosis, with clinical stage I-III triple negative breast cancer diagnosed in 2010-2011, who received either neoadjuvant chemotherapy only or adjuvant chemotherapy only. Patients with incomplete or missing vital status, receptors status and treatment information were excluded. Demographic (age at diagnosis, race, ethnicity, comorbidities, insurance, median income, urbanicity), tumor (clinical stage, histology, grade) and treatment (breast surgery, surgical margin, radiation) factors were examined. Stabilized inverse proportion weights were developed and assigned to balance the neoadjuvant and adjuvant groups on all demographic, tumor and treatment covariates. Unadjusted and adjusted overall survival was calculated using the Kaplan-Meier method and compared using the log-rank test.

Results: Among the 15,483 women with triple negative breast cancer, 4,335 (28%) received neoadjuvant chemotherapy and 11,148 (72%) received adjuvant chemotherapy. Most of the demographic, tumor and treatment factors were similarly distributed among neoadjuvant and adjuvant groups except age at diagnosis and clinical stage. Compared to patients received adjuvant chemotherapy, patients received neoadjuvant chemotherapy were more likely to be younger (45% vs. 31% &lt; 50 year-old, p&lt;0.0001) and have a higher clinical stage (35% vs. 6% stage III, p&lt;0.0001). The unadjusted 4-year overall survival of patients received neoadjuvant vs adjuvant approach was 75.8% (95% CI 74.4%-77.4%) and 87.5% (95% CI 87.1%-87.9%), respectively. After adjusting for demographic, tumor and treatment factors, the 4-year overall survival of patients received neoadjuvant vs adjuvant approach was 81.9% (95% CI 79.5%-84.3%) and 85.3% (95% CI 85.2%-85.4%), respectively.

Conclusion: In this NCDB study, the overall survival of triple negative breast cancer patients received neoadjuvant chemotherapy was inferior to those received adjuvant chemotherapy, even after adjusting for demographic, tumor and treatment factors. However, information regarding the chemotherapy regimen used and whether a full course of chemotherapy was delivered (2 factors that affect disease response and outcome) was not available. Patient and tumor factors at the time of disease presentation that are important in determining which triple negative patients will benefit from neoadjuvant approach remain to be defined.

Citation Format: Cheng YC, Smith E, Yen T. Overall survival of patients with non-metastatic triple negative breast cancer who received neoadjuvant vs adjuvant chemotherapy: Cohort analysis of National cancer data base (NCDB) 2010 - 2011 [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P5-16-09.

[Clinical observation on human alpha glucosidase in treatment of five patients with glycogen storage disease Ⅱ]

Objective: To evaluate the effect of enzyme replacement therapy (ERT) on glycogen storage disease typeⅡ(GSDⅡ). Method: The clinical data of three juvenile onset and two infant onset GSDⅡpatients were collected from First Affiliated Hospital of Sun Yat-sen University in October 2015 to July 2016.Patient 1 was female, the age of onset was 15 months. Patient 2 was male, the age of onset was 20 months. Patient 3 was female, the sister of patient 2, the age of onset was 47 months. Patient 4 was male, the age of onset was 5 months. Patient 5 was male, the age of onset was 1 month.The age at the start of ERT of the 5 patients was 32, 31, 56, 34, and 3 months respectively and the duration of ERT was 19, 9, 4, 5, 5 doses respectively.ERT was administered at 20 mg/kg every 2 weeks.Dexamethasone was regularly given before each infusion. Result: ERT was well tolerated, only one time, Patient 1 developed tachycardia and hypertension without using dexamethasone.Patient 2 underwent successfully ventilator weaning.Patient 1 underwent a tracheotomy, also needed mechanical ventilation treatment.Patient 4 noninvasive ventilation was tried. Conclusion: Recombinant human alpha-glucosidase treatment was effective and well tolerated in patients with GSDⅡ.

Heritability of young- and old-onset ischaemic stroke

BACKGROUND AND PURPOSE

Although the genetic contribution to stroke risk is well known, it remains unclear if young-onset stroke has a stronger genetic contribution than old-onset stroke. This study aims to compare the heritability of ischaemic stroke risk between young and old, using common genetic variants from whole-genome array data in population-based samples.

METHODS

This analysis included 4050 ischaemic stroke cases and 5765 controls from six study populations of European ancestry; 47% of cases were young-onset stroke (age < 55 years). To quantify the heritability for stroke risk in these unrelated individuals, the pairwise genetic relatedness was estimated between individuals based on their whole-genome array data using a mixed linear model. Heritability was estimated separately for young-onset stroke and old-onset stroke (age ≥ 55 years).

RESULTS

Heritabilities for young-onset stroke and old-onset stroke were estimated at 42% (±8%, P < 0.001) and 34% (±10%, P < 0.001), respectively.

CONCLUSIONS

Our data suggest that the genetic contribution to the risk of stroke may be higher in young-onset ischaemic stroke, although the difference was not statistically significant.

Beam focalization in reflection from flat dielectric subwavelength gratings

We experimentally demonstrate the recently predicted effect of near-field focusing for light beams from flat dielectric subwavelength gratings (SWGs). This SWGs were designed for visible light 532 nm and fabricated by direct laser writing in a negative photoresist, with the refractive index n=1.5 and the period d=314  nm. The laterally invariant gratings can focus light beams without any optical axis to achieve the transversal invariance. We show that focal distances can be obtained up to 13 μm at normal reflection for TE polarization.

The origin of the pseudogap in α-Ga

Density functional theory, the free-electron empty lattice approximation and the nearly free-electron approximation are employed to investigate the electronic properties of partially covalent α-Ga. Whereas free-electron-like properties are revealed over a large energy range, a deep pseudogap at the Fermi level is characteristic of α-Ga. We explain the origin of the pseudogap in terms of a delicate interplay between the electronic states and the specific Brillouin zone geometry.

GaN epitaxial layers prepared on nano-patterned Si(001) substrate

We report the growth of GaN epitaxial layer on Si(001) substrate with nano-patterns prepared by dry etching facility used in integrated circuit (IC) industry. It was found that the GaN epitaxial layer prepared on nano-patterned Si(001) substrate exhibits both cubic and hexagonal phases. It was also found that threading dislocation observed from GaN prepared on nano-patterned Si(001) substrate was significantly smaller than that prepared on conventional unpatterned Si(111) substrate. Furthermore, it was found that we can reduce the tensile stress in GaN epitaxial layer by about 78% using the nano-patterned Si(001) substrate.

Addition of GM-CSF to trastuzumab stabilises disease in trastuzumab-resistant HER2+ metastatic breast cancer patients

Background:

One of the proposed mechanisms of trastuzumab-induced regression of human epidermal growth factor receptor 2-positive (HER2+) tumours includes facilitation of antibody-dependent cell-mediated cytotoxicity (ADCC). Granulocyte-macrophage colony-stimulating factor (GM-CSF) mediates ADCC. We presented our pilot study of adding GM-CSF to trastuzumab in patients with trastuzumab-resistant HER2+ metastatic breast cancer.

Methods:

Patients with HER2+ metastatic breast cancer that progressed after trastuzumab +/− chemotherapy were continued on trastuzumab 2 mg kg^–1 intravenous weekly and GM-CSF 250 μg m^–2 subcutaneous daily. Patients were assessed for response every 8 weeks. Treatment was continued until disease progression or intolerable toxicity.

Results:

Seventeen patients were evaluable (median age 48 years, range 27–75 years). The median number of metastatic sites was 2 (range 1–3); the most common site was the liver (n=10). The median number of prior regimens for metastatic disease was 2 (range 1–5). No objective disease response was observed, but five patients (29%) had stable disease for a median duration of 15.8 (range 10–53.9) weeks. The most common adverse event was rash at the injection site. No grade 4 or irreversible adverse event was seen.

Conclusion:

The addition of GM-CSF to trastuzumab alone had a modest clinical benefit and acceptable safety profile in heavily pretreated patients with trastuzumab-resistant HER2+ metastatic breast cancer.

Quaternary ZnCdSeTe nanowires

We report the growth of needle-like high density quaternary ZnCdSeTe nanowires on oxidized Si(100) substrate using vapor-liquid-solid mechanism by molecular beam epitaxy with an Au-based nanocatalyst. It was found that average length and average diameter of the nanowires were 1.3 microm and 91 nm, respectively. It was also found that the as-grown ZnCdSeTe nanowires exhibit mixture of cubic zinc-blende and hexagonal wurtzite structures. Energy depersive results indicate that composition ratio of our nanowire should be Zn0.87Cd0.13Se0.98Te0.02, which agrees excellently with the designated composition ratio of Zn0.87Cd0.13Se0.98Te0.02.

Allogeneic hematopoietic cell transplantation for metastatic breast cancer

We reviewed 66 women with poor-risk metastatic breast cancer from 15 centers to describe the efficacy of allogeneic hematopoietic cell transplantation (HCT). Median follow-up for survivors was 40 months (range, 3-64). A total of 39 patients (59%) received myeloablative and 27 (41%) reduced-intensity conditioning (RIC) regimens. More patients in the RIC group had poor pretransplant performance status (63 vs 26%, P=0.002). RIC group developed less chronic GVHD (8 vs 36% at 1 year, P=0.003). Treatment-related mortality rates were lower with RIC (7 vs 29% at 100 days, P=0.03). A total of 9 of 33 patients (27%) who underwent immune manipulation for persistent or progressive disease had disease control, suggesting a graft-vs-tumor (GVT) effect. Progression-free survival (PFS) at 1 year was 23% with myeloablative conditioning and 8% with RIC (P=0.09). Women who developed acute GVHD after an RIC regimen had lower risks of relapse or progression than those who did not (relative risk, 3.05: P=0.03), consistent with a GVT effect, but this did not affect PFS. These findings support the need for preclinical and clinical studies that facilitate targeted adoptive immunotherapy for breast cancer to explore the benefit of a GVT effect in breast cancer.

Spontaneous fractures in nursing home residents

OBJECTIVES

To evaluate spontaneous long bone fractures occurring in nursing home residents and to identify what factors put them at risk for fractures.

DESIGN

Retrospective study.

SETTING

Department of Orthopaedics and Traumatology of a pubic hospital in Hong Kong.

PATIENTS

A total of 30 nursing home residents who developed spontaneous long bone fractures between 1994 and 2005 were reviewed.

MAIN OUTCOME MEASURES

Demographic data, mechanism of injury, pattern of fractures, associated risk factors, complications, outcomes, and post-treatment status.

RESULTS

The mean age of patients was 84 years. Co-morbidities were as follows: 22 patients were bedridden, 21 required long-term feeding by Ryle's tube, 19 had a history of cerebrovascular accident and 18 of whom had a long bone fracture on the side of the hemiplegia, 15 had dementia, and 25 had lower limb contractures. Closed supracondylar fractures of the femur occurred in 23 patients, 17 of whom presented with limb deformity. In 21 patients, fractures were treated successfully with hinged braces. In one patient, the fracture changed from closed to open. In five patients, the fractures were complicated by sacrum or heel sores, and in one by infected nonunion. In 28 patients, the fractures eventually healed without further complications. Three formerly bedridden patients were able to sit after their fractures had been treated.

CONCLUSIONS

Female nursing home residents who require long-term Ryle's tube feeding, have dementia, hemiplegia, lower limb contractures, osteoporosis, or are bedridden, are at high risk for spontaneous fractures.

Fabrication and field emission property of a Si nanotip array

Using a Si-based porous anodic alumina membrane as a mask, we demonstrate a way to pattern Si surface. After removing the SiO(2) nanoislands formed during anodization of the Al/Si interface, we obtain a Si nanotip array on the surface of a Si wafer. This array shows an excellent field emission property with a low turn-on field of 8.5 V µm(-1). The Fowler-Nordheim plot obtained is linearly dependent, indicating that the emission current arises from the quantum tunnelling effect. The Si nanotip array can be expected to have important applications in nanoelectronic devices.

Optical properties and carrier dynamics of self-assembled GaN/Al(0.11)Ga(0.89)N quantum dots

GaN quantum dots were grown on an Al(0.11)Ga(0.89)N buffer layer by using flow rate modulation epitaxy. The Stranski-Krastanov growth mode was identified by an atomic force microscopy study. The thickness of the wetting layer is about 7.2 monolayers. The temperature dependent photoluminescence studies showed that at low temperature the localization energy, which accounts for de-trapping of excitons, decreases with the reducing dot size. The decrease in emission efficiency at high temperature is attributed to the activation of carriers from the GaN dot to the nitrogen vacancy (V(N)) state of the Al(0.11)Ga(0.89)N barrier layer. The activation energy decreases with reducing dot size.

Coherence in the B800 ring of purple bacteria LH2

We study the quantum coherence in the B800 ring and how it affects the dynamics of excitation energy transfer (EET) in photo-synthetic light-harvesting systems. From an analysis of the spectrum, we determine the disorder parameters for the B800 ring and show that the relatively weak electronic coupling between B800 pigments subtly changes the dynamics of EET and improves the uniformity and robustness of B800 --> B850 EET at room temperature, an example of how a multichromophoric assembly can exploit coherence to optimize the efficiency of photosynthesis. A molecular-level description for the dynamics of EET in the light-harvesting system may prove useful for understanding other nanoscale molecular assemblies and designing efficient nanoscale optical devices.

Markovian Approximation in the Relaxation of Open Quantum Systems

In this paper, we examine the validity of the Markovian approximation and the slippage scheme used to incorporate short time transient memory effects in the Markovian master equations (Redfield equations). We argue that for a bath described by a spectral function, J(omega), that is dense and smoothly spread out over the range omega(d), a time scale of tau(b) approximately 1/omega(d) exists; for times of t > tau(b), the Markovian approximation is applicable. In addition, if J(omega) decays to zero reasonably fast in both the omega --> 0 and omega --> infinity limits, then the bath relaxation time, tau(b), is determined by the width of the spectral function and is weakly dependent on the temperature of the bath. On the basis of this criterion of tau(b), a scheme to incorporate transient memory effects in the Markovian master equation is suggested. Instead of using slipped initial conditions, we propose a concatenation scheme that uses the second-order perturbation theory for short time dynamics and the Markovian master equation at long times. Application of this concatenation scheme to the spin-boson model shows that it reproduces the reduced dynamics obtained from the non-Markovian master equation for all parameters studied, while the simple slippage scheme breaks down at high temperatures.

Neuroradiological findings in atypical teratoid/rhabdoid tumor of the central nervous system

PURPOSE

To evaluate the computed tomography (CT) and magnetic resonance imaging (MRI) findings of atypical teratoid tumor/rhabdoid tumor (AT/RT) of the central nervous system (CNS).

MATERIAL AND METHODS

Twenty cases of CNS AT/RT have been found over the past 23 years in our hospital; these involving 11 boys and 9 girls whose mean age at diagnosis was 5.5 years. Their clinical data, the CT, and MRI findings were reviewed retrospectively.

RESULTS

AT/RT was located in the cerebellum in 15 cases. Four cases arose from the supratentorial region, while only one occurred primarily in the lumbar spinal cord. Almost all cases revealed heterogeneous intensity and heterogeneous enhancement. Peripheral cystic components were common. Survival time ranged from 2 months to 3 years, with a mean survival of 11.6 months.

CONCLUSION

Most cases of AT/RT are located in the cerebellum. The radiologic manifestations are non-specific. The diagnosis mainly depends on the pathologic findings. However, AT/RT should still remain in the differential diagnosis of brain tumors in young children, especially those located in the cerebellar hemisphere and with eccentric cysts.

Process modeling of the lipase-catalyzed dynamic kinetic resolution of (R, S)-suprofen 2,2,2-trifluoroethyl thioester in a hollow-fiber membrane

A Candida rugosa lipase immobilized on polypropylene powder was employed as the biocatalyst for the enantioselective hydrolysis of (R, S)-suprofen 2,2,2-trifluorothioester in cyclohexane, in which trioctylamine was added as the catalyst to perform in situ racemization of the remaining (R)-thioester. A hollow-fiber membrane was also integrated with the dynamic kinetic resolution process in order to continuously extract the desired (S)-suprofen into an aqueous solution containing NaOH. A kinetic model for the whole process (operating in batch and feed-batch modes) was developed, in which enzymatic hydrolysis and deactivation, lipase activation, racemization and non-enantioselective hydrolysis of the substrate by trioctylamine, and reactive extraction of (R)- and (S)-suprofen into the aqueous phase in the membrane were considered. Theoretical predictions from the model for the time-course variations of substrate and product concentrations in each phase were compared with experimental data.

Animal models for the study of HBV infection and the evaluation of new anti-HBV strategies

BACKGROUND

Our aim was to evaluate the anti-HBV activity of a novel L-nucleoside analog, 2',3'-dideoxy-2',3'-didehydro-beta-L-5-fluorocytidine (beta-L-Fd4C), in study models of HBV infection.

METHOD

Its mechanism of action was evaluated on the in vitro expressed duck HBV (DHBV) reverse transcriptase and in primary hepatocyte cultures of duck and human origin. The capacity of antiviral therapy to clear viral infection was analyzed in vivo in the duck and woodchuck models.

RESULTS

beta-L-Fd4C-TP exhibited a more potent inhibitory effect on the RT activity of the DHBV polymerase than other cytidine analogs (lamivudine-TP, ddC-TP, beta-L-FddC-TP). In primary duck hepatocyte cultures, beta-L-Fd4C exhibited a long-lasting inhibitory effect on viral DNA synthesis but could not clear viral cccDNA. In vivo treatment with beta-L-Fd4C in infected ducklings and woodchucks, induced a greater suppression of viremia and intrahepatic viral DNA synthesis than with lamivudine. However, covalently closed circular DNA persistence explained the relapse of viral replication after treatment withdrawal. Viral spread was strongly reduced in the case of early therapeutical intervention, but the number of infected cells did not decline when therapy was started during chronic infection. Liver histology analysis showed a decrease in the inflammatory activity of chronic hepatitis while no ultrastructural modification of liver cells was observed in electron microscopy studies. Furthermore, in human primary hepatocyte cultures, beta-L-Fd4C induced a significant inhibition of HBV DNA synthesis.

CONCLUSION

beta-L-Fd4C is a potent inhibitor of hepadnavirus RT and inhibits viral DNA synthesis in hepatocytes both in vitro and in vivo. These experimental studies allowed as to show that beta-L-Fd4C is a promising anti-HBV agent. Combination therapy should be evaluated to eradicate viral infection.

L-Nucleoside analogues against cancer-causing viruses have potential in the prevention, delayed onset and treatment of viral associated cancers

It has been established that several types of cancers have a strong association with viruses. Thus, a potent antiviral compound without toxicity upon long-term usage will be useful not only for the treatment of viral diseases but also for the prevention or the delayed onset of those cancers that have a strong association with viruses. These compounds, depending upon their mechanism of action, could also potentially be useful for the treatment of those viral-associated cancers. L(-)Deoxynucleoside analogues were discovered in my laboratory and by others as an important class of antiviral and anti-cancer chemical entities. L(-)SddC (3TC, lamivudine), L(-)FTC, L(-)Fd4C, and L(-)FMAU are compounds with potent activity against hepatitis B virus (HBV), but with different biological and pharmacological profiles. These compounds may be useful in the prevention or delayed onset of hepatocellular carcinoma associated with HBV. L(-)I-OddU is a potent anti-Epstein-Barr virus (EBV) compound without cytotoxicity and animal toxicity upon long-term dosing, which allows drug concentration in plasma that are much higher than those that are antivirally active. This compound may have the potential to prevent B-cell lymphoma associated with patients undergoing organ transplants in addition to its potential use for the treatment of EBV infection. Furthermore, it may also be useful for the treatment of EBV-associated cancers. In this manuscript, the metabolism, mechanism of action and the resistance, as well as the potential use of this class of compounds targetted against HBV, will be discussed.

Synthesis of halogen-substituted 3-deazaadenosine and 3-deazaguanosine analogues as potential antitumor/antiviral agents

Various 2-halogen-substituted analogues (38, 39, 43 and 44), 3-halogen-substituted analogues (51 and 52), and 2',3'-dihalogen-substituted analogues (57-60) of 3-deazaadenosine and 3-halogen-substituted analogues (61 and 62) of 3-deazaguanosine have been synthesized as potential anticancer and/or antiviral agents. Among these compounds, 3-deaza-3-bromoguanosine (62) showed significant cytotoxicity against L1210, P388, CCRF-CEM and B16F10 cell lines in vitro, producing IC50 values of 3, 7, 9 and 7 microM, respectively. Several 3-deazaadenosine analogues (38, 51, 57 and 59) showed moderate to weak activity against hepatitis B virus.

Predicting BOLD signal changes as a function of blood volume fraction and resolution

The appropriate choice of resolution in fMRI remains an open question. To address this issue, we simulate the signal change between activated and resting states as a function of blood volume fraction (lambda). From these results, the relative contrast-to-noise ratio (CNR) from the resting to the activated state can be calculated as a function of resolution. We consider different vessel orientations and note that, in most cases, the most efficient scanning procedure is for low resolution imaging. To overcome this limitation, a T(1) enhancing contrast agent is proposed to increase the signal from the blood and, hence, the intravascular contribution to the BOLD effect. We show that this effect dramatically increases both the signal changes and the efficiency of high-resolution imaging and should lead to much better visualization and localization of parenchymal changes.

Were there enough physicians in an emergency department in the affected area after a major earthquake? An analysis of the Taiwan Chi-Chi earthquake in 1999

STUDY OBJECTIVE

The purpose of this study was to evaluate physician manpower and mobilization in an urban emergency department receiving patients after a major earthquake.

METHODS

Patient charts were reviewed. The workload of physicians was assessed semiquantitatively before and after a major earthquake. The physicians' mobilization in the postearthquake emergency response was assessed by using a confidential questionnaire.

RESULTS

In the 3 days after the earthquake, 566 patients with earthquake-related illnesses or injuries were sent to the urban ED. Three hundred one (53.2%) patients arrived within the initial 10 hours. In the initial hours, there was no significant difference between the number of patients per physician per hour before and after the earthquake. Workloads of wound treatment and advanced life support procedures were significantly higher after the earthquake compared with before the earthquake, during the first to sixth hour and second to fifth hour, respectively. Sixty-five percent of the hospital's physicians did not assist in either the ED or in any other parts of the hospital in the initial 6 hours after the earthquake.

CONCLUSION

The number of physicians in the ED was insufficient in the initial hours after the earthquake because of the sudden influx of a large number of patients. Future disaster planning must address the issue of physicians' behavior with regard to their priorities immediately after a major earthquake and include greater provision for efficient mobilization of physicians.

Synthesis and biological evaluation of L- and D-configurations of 2',3'-dideoxy-4'-C-methyl-3'-oxacytidine analogues

Novel L- and D-configuration 2',3'-dideoxy-4'-C-methyl-3'-oxacytidine and their 5-fluoro analogues have been synthesized from 1-benzyloxy-2-propanone and L-ascorbic acid in eight steps and evaluated for biological activity.

An exact form for the magnetic field density of states for a dipole

We present an analytical form for the density of states for a magnetic dipole in the center of a spherical voxel. This analytic form is then used to evaluate the signal decay as a function of echo time for different volume fractions and susceptibilities. The decay can be considered exponential only in a limited interval of time. Otherwise, it has a quadratic dependence on time for short echo times and an oscillatory decaying behavior for long echo times.

Sox8 gene expression identifies immature glial cells in developing cerebellum and cerebellar tumours

Sox8 is a member of the E subgroup of Sox genes, the other members of which are Sox9 and Sox10, both of which are implicated in specific human disorders. Recently, Sox8 homologues have been cloned in chick, mouse and human and have been shown to be strongly expressed in the embryonic and adult brain. Nevertheless, the cell types that express Sox8 have not been determined. We show here that Sox8 is expressed in immature glia in the developing cerebellum. Sox8 is also expressed in scattered cells in the cerebellar tumour, medulloblastoma. This gene therefore provides an early glial marker that may provide more detailed insight into the cellular makeup and consequent behaviour of medulloblastomas.

Prenatal diagnosis of cleft palate by three-dimensional ultrasound

Prenatal diagnosis of cleft palate is very important to prenatal consultation and management after birth. To examine if three-dimensional (3-D) ultrasound (US) is an accurate diagnostic method for clinical use, we analyzed our experience in detecting cleft palate by 3-D US. From June 1996 to January 2000, 21 fetuses with facial clefts were scanned by 2-D US, as well as by 3-D US. The coronal and oblique planes were reconstructed by 3-D US to detect the cleft palate. In addition, level II US was performed to find any possibly associated anomalies. All the scans were recorded on optic disks for final analysis. In our study, the gestational age when prenatal diagnosis was made by US initially was between 20 and 34 weeks. The accuracy for prenatal diagnosis of cleft lip with or without cleft palate by 3-D US was 100%, which was superior to that by 2-D US (p < 0.05). In addition, we proposed a novel method to evaluate the cleft palate systemically by 3-D US. In conclusion, from our study, fetuses with cleft lip combined with or without cleft palate can be easily differentiated by 3-D US. The reconstruction of coronal and oblique planes by 3-D US is a powerful tool for detecting cleft palate.

Dysfunctional regulation of endothelial nitric oxide synthase (eNOS) expression in response to exercise in mice lacking one eNOS gene

BACKGROUND

Previous data suggest that 1 endothelial NO synthase (eNOS) gene is sufficient to allow normal expression and function of eNOS under basal conditions. We hypothesized that this might not hold true for conditions known to increase eNOS gene expression, such as exercise.

METHODS AND RESULTS

Male mice heterozygous for a disruption of the eNOS gene (eNOS(+/)(-)) and normal C56Bl/6J mice (eNOS(+/+)), 3 to 4 months of age, underwent exercise training for 3 weeks. Nontrained mice were exposed to the exercise environment (noise and vibration of the treadmill) without exercise for an identical period. In eNOS(+/+) mice (n=7), exercise increased aortic eNOS protein expression by 3.4+/-0.4-fold (P<0.002). This was associated with a greater vascular cGMP accumulation on stimulation with acetylcholine (P<0.05). Furthermore, exercise training increased eNOS mRNA (1.78+/-0.4-fold) and protein (1.76+/-0.17-fold) in left ventricular tissue, as determined by competitive reverse transcription-polymerase chain reaction and Western analysis (P<0.05 for both). In striking contrast, exercise had no effect on aortic eNOS expression and cGMP accumulation in eNOS(+/)(-) mice (P>0.05). Thus, although eNOS expression appears to be normal in eNOS(+/)(-) mice under basal conditions, these mice are unable to increase eNOS expression during exercise.

CONCLUSIONS

These findings show that regulation of eNOS expression during exercise requires the presence of both alleles of the gene and may have implications for conditions in which polymorphisms of eNOS are present in only 1 allele in humans. These individuals may have a normal vascular reactivity under basal conditions but may be unable to adapt their vascular reactivity in response to exercise training.

Antiviral activity of beta-L-2',3'-dideoxy-2',3'-didehydro-5-fluorocytidine in woodchucks chronically infected with woodchuck hepatitis virus

The L-nucleoside analog beta-L-2',3'-dideoxy-2',3'-didehydro-5-fluorocytidine (beta-L-Fd4C) was first shown to exhibit potent activity against hepatitis B virus (HBV) in tissue culture and then to significantly inhibit viral spread during acute infection in the duck HBV model (F. Le Guerhier et al., Antimicrob. Agents Chemother. 44:111-122, 2000). We have therefore examined its antiviral activity in a mammalian model of chronic HBV infection, the woodchuck chronically infected with woodchuck hepatitis virus (WHV). Side-by-side comparison of beta-L-Fd4C and lamivudine administered intraperitoneally during short-term and long-term protocols demonstrated a more profound inhibition of viremia in beta-L-Fd4C-treated groups. Moreover, beta-L-Fd4C induced a marked inhibition of intrahepatic viral DNA synthesis compared with that induced by lamivudine. Nevertheless, covalently closed circular (CCC) DNA persistence explained the lack of clearance of infected hepatocytes expressing viral antigens and the relapse of WHV replication after drug withdrawal. Liver histology showed a decrease in the inflammatory activity of chronic hepatitis in woodchucks receiving beta-L-Fd4C. An electron microscopy study showed the absence of ultrastructural changes of hepatic mitochondria, biliary canaliculi, and bile ducts. However, a loss of weight was observed in all animals, whatever the treatment, as was a transient skin pigmentation in all woodchucks during beta-L-Fd4C treatment. There was no evidence that lamivudine or beta-L-Fd4C could prevent the development of hepatocellular carcinoma with the protocols used. These results indicate that beta-L-Fd4C exhibits a more potent antiviral effect than lamivudine in the WHV model but was not able to eradicate CCC DNA and infected cells from the liver at the dosage and with the protocol used.

Jac1, a mitochondrial J-type chaperone, is involved in the biogenesis of Fe/S clusters in Saccharomyces cerevisiae

A minor Hsp70 chaperone of the mitochondrial matrix of Saccharomyces cerevisiae, Ssq1, is involved in the formation or repair of Fe/S clusters and/or mitochondrial iron metabolism. Here, we report evidence that Jac1, a J-type chaperone of the mitochondrial matrix, is the partner of Ssq1 in this process. Reduced activity of Jac1 results in a decrease in activity of Fe/S containing mitochondrial proteins and an accumulation of iron in mitochondria. Fe/S enzyme activities remain low in both jac1 and ssq1 mutant mitochondria even if normal mitochondrial iron levels are maintained. Therefore, the low activities observed are not solely due to oxidative damage caused by excess iron. Rather, these molecular chaperones likely play a direct role in the normal assembly process of Fe/S clusters.

Successful pregnancy by transmyometrial and transtubal embryo transfer after IVF in a patient with congenital cervical atresia who underwent uterovaginal canalization during Caesarean section: case report

Successful pregnancy in a patient with congenital cervical atresia is a great challenge for assisted reproductive techniques and reproductive medicine. We report a case of successful pregnancy by transmyometrial and transtubal embryo transfer simultaneously after in-vitro fertilization (IVF) in a 33 year-old patient with congenital cervical atresia diagnosed at the age of 18 years. The patient had experienced cyclic abdominal pain and amenorrhoea since she was 13 years old. She had had two unsuccessful attempts to create a new uterovaginal canal in another hospital. At the age of 32 years, she was referred to our unit and had a successful pregnancy after transmyometrial and transtubal embryo transfer. Caesarean section was performed at 36 weeks gestation due to progressive pre-eclampsia and gestational diabetes. A healthy male baby weighing 2812 g was safely delivered. Uterovaginal canalization with amniotic membrane for the covering of the neo-endocervical wall was performed during Caesarean section. Normal menstrual outflow and symptomatic relief have continued for 5 months after the operation. To the best of our knowledge, this is the first reported case of successful pregnancy by transmyometrial and transtubal embryo transfer as well as uterovaginal canalization performed during Caesarean section in a patient with congenital cervical atresia.

Application of the SUSHI method to the design of gradient coils

An approach to potential improvements in magnetic field shielding for a gradient coil system with cylindrical geometry is presented, utilizing "supershielding" conditions for the currents on both the primary and the secondary coils. It is demonstrated that the field can be strongly suppressed everywhere outside a cylindrical shield coil radius, even though the finite-length active shield only partially surrounds a primary coil. The supershielding method, which is aimed at controlling eddy currents, still has sufficient freedom to maintain the desired magnetic field behavior inside the imaging volume. The trade-off is an additional primary current oscillation and increased current peaks and field energy. This method has been applied to design short transverse and axial gradient coils, giving substantially improved shielding compared to an apodization method. Magn Reson Med 45:147-155, 2001.

Potential use of antiviral L(-)nucleoside analogues for the prevention or treatment of viral associated cancers

Several types of virus were found to have a strong association with different types of cancers. Thus, a selective antiviral compound without toxicity upon long-term usage will be useful not only for the treatment of viral diseases but also for the prevention or the delayed onset of those cancers, which have a strong association with viruses. L(-)Nucleoside analogs were discovered recently in my laboratory as an important class of antiviral and anticancer chemical entities. L(-)SddC (3TC, Lamivudine), FTC, Fd4C, and L(-)FMAU are potent anti-HBV compounds with different pharmacological profiles. These compounds may be useful in the prevention or delayed onset of hepatocellular carcinoma associated with HBV. L(-)I-OddU is the most potent anti-Epstein-Barr Virus (EBV) compound without cytotoxicity and animal toxicity upon long-term dosing which gives the pharmacological levels of the drug in plasma. This compound may have the potential to prevent B-cell lymphoma associated with patients undergoing organ transplants in addition to its potential use for the treatment of EBV infection.

Characterization of novel human hepatoma cell lines with stable hepatitis B virus secretion for evaluating new compounds against lamivudine- and penciclovir-resistant virus

L-Nucleoside analogs are new therapeutic agents for treatment of chronic hepatitis B. However, their clinical application was limited by the emergence of viral resistance. It is important to develop a new system to evaluate drug cross-resistance and to test new agents that may overcome resistant virus. In this report, three cell lines HepG2-WT10, HepG2-SM1, and HepG2-DM2 are presented; these cell lines were established by transfection of HepG2 cells with unique fully functional 1.1x hepatitis B virus (HBV) genomes: wild-type HBV-adr and its L526M and L526MM550V variants, respectively. We have demonstrated that these genomes have different susceptibilities to lamivudine [L(-)SddC] and penciclovir (PCV). By examining HBV RNA transcription, antigen expression, progeny DNA replication, and viral susceptibilities to L(-)SddC, PCV, and other nucleoside analogs, it is concluded that the cell lines are able to stably produce L(-)SddC- and PCV-sensitive and -resistant HBV virions. In addition, the relative susceptibilities of the wild-type and mutant HBV produced from the stably transfected cell lines to several anti-HBV nucleoside analogs were also examined and found to be about the same as those found by using a transient infection system. PMEA [9-(2-phosphonylmethoxytehyl)-adenine] and QYL685 are able to suppress L(-)SddC- and PCV-resistant HBV. In conclusion, this cell culture system is a novel and useful tool for evaluating anti-HBV compounds and biologics.

Anti-Epstein-Barr virus (EBV) activity of beta-L-5-iododioxolane uracil is dependent on EBV thymidine kinase

beta-L-5-Iododioxolane uracil was shown to have potent anti-Epstein-Barr virus (EBV) activity (50% effective concentration = 0.03 microM) with low cytotoxicity (50% cytotoxic concentration = 1,000 microM). It exerts its antiviral activity by suppressing replicative EBV DNA and viral protein synthesis. This compound is phosphorylated in cells where the EBV is replicating but not in cells where the EBV is latent. EBV-specific thymidine kinase could phosphorylate beta-L-5-iododioxolane uracil to the monophosphate metabolite. The K(m) of beta-L-5-iododioxolane uracil with EBV thymidine kinase was estimated to be 5.5 microM, which is similar to that obtained with thymidine but about fivefold higher than that obtained with 2' fluoro-5-methyl-beta-L-arabinofuranosyl uracil, the first L-nucleoside analogue discovered to have anti-EBV activity. The relative V(max) is seven times higher than that of thymidine. The anti-EBV activity of beta-L-5-iododioxolane uracil and its intracellular phosphorylation could be inhibited by 5'-ethynylthymidine, a potent EBV thymidine kinase inhibitor. The present study suggests that beta-L-5-iododioxolane uracil exerts its action after phosphorylation; therefore, EBV thymidine kinase is critical for the antiviral action of this drug.

Metabolism and mode of inhibition of varicella-zoster virus by L-beta-5-bromovinyl-(2-hydroxymethyl)-(1,3-dioxolanyl)uracil is dependent on viral thymidine kinase

A nonnaturally occurring L-configuration nucleoside analog, L-beta-5-bromovinyl-(2-hydroxymethyl)-1,3-(dioxolanyl)uracil (L-BVOddU) selectively inhibited varicella-zoster virus growth in human embryonic lung (HEL) 299 cell culture with an EC(50) of 0.055 microM, whereas no inhibition of CEM and HEL 299 cell growth or mitochondrial DNA synthesis was observed at concentrations up to 200 microM. L-BVOddU was phosphorylated by viral thymidine kinase but not by human cytosolic thymidine kinase, and the antiviral activity of this compound is dependent on the viral thymidine kinase. Unlike other D-configuration bromovinyl deoxyuridine analogs, such as E-5-(2-bromovinyl)-2'-deoxyuridine and 1-beta-arabinofuranosyl-E-5-(2-bromovinyl)uracil, this compound was metabolized only to its monophosphate metabolite. The di- or triphosphate metabolites were not detected. This suggested that the inhibitory mechanism may be unique and different from other anti-herpesvirus nucleoside analogs.

[Dynamic changes of serum lipids in patients with acute stroke]

The dynamic changes of the serum levels of total cholesterol(TC), triglyceride(TG), high density lipoprotein-cholesterol(HDL-c) and subfraction(HDL2-c), apolipoprotein(Apo) A-I, ApoB, lipoprotein(a)[Lp(a)] and fibrinogen(Fg) were measured in forty-one patients with acute[including 31 cerebral hemorrhagic patients(ICH), and 10 cerebral infraction patients(CI)]. The results showed that the serum levels of HDL-c and subfractions, ApoA-I and TC gradually decreased in ICH during acute phase, and reduced to the lowest level on the fourteenth day, while the levels of TG and ApoB had no obvious change, the serum levels of Fg and Lp(a) increased to the highest level on the seventh day. The serum levels of Lp(a), ApoB and TG had no obvious change in CI during acute phase, and the serum levels of TC, HDL-c and subfraction, ApoA-I decreased, while the level of Fg increased in CI, but there was no statistical significance. It is suggested that Lp (a) is a positive acute reactive lipoprotein in ICH, and HDL and ApoA-I are negative acute reactive substances in ICH and CI.

Synthesis and antiviral activity of oxaselenolane nucleosides

As dioxolane and oxathiolane nucleosides have exhibited promising antiviral and anticancer activities, it was of interest to synthesize isoelectronically substituted oxaselenolane nucleosides, in which the 3'-CH(2) is replaced by a selenium atom. To study structure-activity relationships, various pyrimidine and purine oxaselenolane nucleosides were synthesized from the key intermediate, (+/-)-2-benzoyloxymethyl-1,2-oxaselenolane 5-acetate (6). Among the synthesized racemic nucleosides, cytosine and 5-fluorocytosine analogues exhibited potent anti-HIV and anti-HBV activities. It was of interest to obtain the enantiomerically pure isomers to determine if they have differential antiviral activities. However, due to the difficult and time-consuming nature of enantiomeric synthesis, a chiral HPLC separation was performed to obtain optical isomers from the corresponding racemic mixtures. Each pair of enantiomers of Se-ddC and Se-FddC was separated by an amylose chiral column using a mobile phase of 100% 2-propanol. The results indicate that most of the anti-HIV activity of both cytosine and fluorocytosine nucleosides resides with the (-)-isomers.

A novel action of human apurinic/apyrimidinic endonuclease: excision of L-configuration deoxyribonucleoside analogs from the 3' termini of DNA

beta-l-Dioxolane-cytidine (l-OddC, BCH-4556, Troxacitabine) is a novel unnatural stereochemical nucleoside analog that is under phase II clinical study for cancer treatment. This nucleoside analog could be phosphorylated and subsequently incorporated into the 3' terminus of DNA. The cytotoxicity of l-OddC was correlated with the amount of l-OddCMP in DNA, which depends on the incorporation by DNA polymerases and the removal by exonucleases. Here we reported the purification and identification of the major enzyme that could preferentially remove l-OddCMP compared with dCMP from the 3' termini of DNA in human cells. Surprisingly, this enzyme was found to be apurinic/apyrimidinic endonuclease (APE1) (), a well characterized DNA base excision repair protein. APE1 preferred to remove l- over d-configuration nucleosides from 3' termini of DNA. The efficiency of removal of these deoxycytidine analogs were as follows: l-OddC > beta-l-2',3'-dideoxy-2', 3'-didehydro-5-fluorocytidine > beta-l-2',3'-dideoxycytidine > beta-l-2',3'-dideoxy-3'-thiocytidine > beta-d-2',3'-dideoxycytidine > beta-d-2',2'-difluorodeoxycytidine > beta-d-2'-deoxycytidine >/= beta-d-arabinofuranosylcytosine. This report is the first demonstration that an exonuclease can preferentially excise l-configuration nucleoside analogs. This discovery suggests that APE1 could be critical for the activity of l-OddC or other l-nucleoside analogs and may play additional important roles in cells that were not previously known.

Synthesis and biological evaluation of L- and D-configuration 1,3-dioxolane 5-azacytosine and 6-azathymine nucleosides

Novel L- and D-configuration dioxolane 5-azacytosine and 6-azathymine nucleosides have been synthesized and evaluated for biological activity. (-)-(2S,4S)-1-[2-(Hydroxymethyl)-1,3-dioxolan-4-yl]-5-azacytosine (6) showed significant activity against HBV, whereas the D-configuration analogue (14) has been found to exhibit potent anti-HIV activity.