Inhibitory effect of pre-gelatinized dialdehyde starch on heat-induced deterioration of sea cucumber.

BACKGROUND: This study sought to investigate the inhibitory effect of pre-gelatinized dialdehyde starch (P-DAS) on the deterioration of sea cucumber during high-temperature sterilization. RESULTS: It was found that pre-gelatinization reduced crystallinity and average molecular weight of dialdehyde starch (DAS), exposed free aldehyde groups, improved the solubility, and unified the particle sizes. According to the texture profiles of sea cucumber, the crosslinking power of P-DAS was higher than that of DAS. The results of free amino content, total soluble substance, water retention, water distribution, relaxation time and scanning electron microscopy all showed that the crosslinking effect was dose-dependent on crosslinking agent. CONCLUSION: These results have proved that large molecules such as P-DAS, when properly handled, could also efficiently enter collagen hydrogels and perform crosslinking, providing reference for the development of new protein food stabilizing agents. © 2022 Society of Chemical Industry.

Characterization of microbiota in acute leukemia patients following successful remission induction chemotherapy without antimicrobial prophylaxis.

PURPOSE: In the present study, we characterized the microbiomes of acute leukemia (AL) patients who achieved complete remission following remission induction chemotherapy (RIC) as outpatients, but who did not receive antimicrobials to treat or prevent febrile neutropenia. METHODS: Saliva and stool samples from 9 patients with acute myeloid leukemia, 11 patients with acute lymphoblastic leukemia, and 5 healthy controls were subjected to 16S ribosomal RNA sequencing at baseline and at 3 months following RIC. Only patients who achieved remission at 3 months post-treatment were included. We excluded anyone who used antimicrobials within 2 months of enrollment or at any time during the study period. RESULTS: At baseline, the relative abundances of species of Prevotella maculosa (P=0.001), Megasphaera micronuciformis (P=0.014), Roseburia inulinivorans (P=0.021), and Bacteroides uniformis (P=0.004) in saliva and Prevotella copri (P=0.002) in the stools of controls were significantly higher than in AL patients. Following RIC, the relative abundances of Eubacterium sp. oral clone DO008 (P=0.012), Leptotrichia sp. oral clone IK040 (P=0.002), Oribacterium sp. oral taxon 108 (P=0.029), Megasphaera micronuciformis (P=0.016), TM7 phylum sp. oral clone DR034 (P<0.001), Roseburia inulinivorans (P=0.034), Actinomyces odontolyticus (P=0.014), Leptotrichia buccalis (P=0.005), and Prevotella melaninogenica (P=0.046) in saliva and Lactobacillus fermentum (P=0.046), Coprococcus catus (P=0.050), butyrate-producing bacterium SS3/4 (P=0.013), and Bacteroides coprocola (P=0.027) in the stools of AL patients were significantly greater than in controls. CONCLUSION: Following RIC, several taxa are changed in stool and salvia samples of AL patients. Our results warrant future large-scale multicenter studies to examine whether the microbiota might have an effect on clinical outcomes of AL patients.

Mechanisms of Protective Effect of Ramulus Mori Polysaccharides on Renal Injury in High-Fat Diet/Streptozotocin-Induced Diabetic Rats.

BACKGROUND: Diabetic nephropathy (DN) is the most important complication of diabetes and the most common cause of end-stage renal disease (ESRD). AIMS: A recent study established that the Ramulus mori polysaccharides (RMP) exert antioxidant effects on DN in rats. METHODS: The diabetic rats which induced by high-fat diet and streptozotocin injection were orally administered RMP by doses of 250, 500 and 1000 mg/kg daily for 8 weeks. The effects of RMP on hyperglycemia and other biochemical changes were examined in the sera and kidney tissues. Additionally, the pathological and ultrastructural changes and expressions of nuclear-factor kappa B (NF-x03BA;B) and transforming growth factor-ß1 (TGF-ß1) were assessed. RESULTS: The results revealed that the serum levels of blood glucose, total cholesterol (TC) and triglycerides (TG) were significantly decreased by RMP. Furthermore, the blood urea nitrogen (BUN), serum creatinine (SCr) and 24-hour urine protein levels in the RMP-medicated rats were lower than those in untreated diabetic rats. Moreover, treatment of the DN rats with RMP normalized all biochemical changes, including the malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) levels in the serum and kidney tissues. In contrast, the protein expression levels of NF-x03BA;B and TGF-ß1, which were enhanced in the kidneys of DN rats, were reduced by RMP. CONCLUSION: These results suggest that RMP improving the renal function of diabeitc rats possibly via its ameliorating antioxidant activities.

Past, present and future changes in the annual streamflow of the Lancang-Mekong River and their driving mechanisms.

The rapid development of the Greater Mekong Subregion (GMS) makes it essential to understand the major mechanisms controlling the streamflow, especially for the Lancang-Mekong River (abbr. Mekong River). We used instrumental annual streamflow data (1960-2007) from Chiang Saen hydrological station and several gridded hydroclimatic datasets to explore the hydroclimatic evolution of the Mekong River, together with its driving mechanisms. We found that changes in the Mekong streamflow are consistent with precipitation changes, and the Mekong is thus a precipitation-dominated river that is susceptible to the effects of ongoing climate change. The instrumental record of Mekong annual streamflow is closely related to hydroclimatic changes, especially those related to moisture, within the area from the Hengduan Mountains to the Chiang Saen Station. Based on these gridded records, we extended the Mekong annual streamflow record to cover 1891-2021 using nested multiple linear regression fitting. The fitted streamflow explained up to 57.6 % of the instrumental changes and it indicates that the major 2019 drought was not unique over the past century. Despite extremely low precipitation and high temperatures, it is likely that the effects of drought can be mitigated via hydraulic engineering regulation. Climatological analyses showed that the Mekong annual streamflow is driven by the El Niño-Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD), which is consistent with observed quasi-interannual cycles of 3-4 years. A multi-model ensemble of CMIP6 revealed that the Mekong annual streamflow will experience an upward trend in the future, accompanied by the more extreme impacts of ENSO and the IOD.

The Significance of the Redox Gene in the Prognosis and Therapeutic Response of Glioma.

OBJECTIVES: Glioblastoma (GBM) is a fatal adult central nervous system tumor. Due to its high heterogeneity, the survival rate and prognosis of patients are poor. Thousands of people die of this disease every year all over the world. At present, the treatment of GBM is mainly through surgical resection and the combination of later drugs, radiotherapy, and chemotherapy. An abnormal redox system is involved in the malignant progression and treatment tolerance of glioma, which is the main reason for poor survival and prognosis. The construction of a GBM redox-related prognostic model may be helpful in improving the redox immunotherapy and prognosis of GBM. METHODS: Based on glioma transcriptome data and clinical data from The Cancer Genome Atlas, databases, a risk model of redox genes was constructed by univariate and multivariate Cox analysis. The good prediction performance of the model was verified by the internal validation set of The Cancer Genome Atlas, and the external data of Chinese Glioma Genome Atlas. RESULTS: The results confirmed that the higher the risk score, the worse the survival of patients. Age and isocitrate dehydrogenase status were significantly correlated with risk scores. The analysis of immune infiltration and immunotherapy found that there were significant differences in the immune score, matrix score, and ESTIMATE score between high and low-risk groups. reverse transcription polymerase chain reaction and immunohistochemical staining of glioma samples confirmed the expression of the hub gene. CONCLUSION: Our study suggests that the 5 oxidative-related genes nitricoxidesynthase3 , NCF2 , VASN , FKBP1B , and TXNDC2 are hub genes, which may provide a reliable prognostic tool for glioma clinical treatment.

Oxidized inositol stabilizes rehydrated sea cucumbers against non-enzymatic deterioration.

Rehydrated sea cucumber (RSC) is a popular seafood in northeast Asia with high deep-processing potential. Yet the development of value-added RSC product is limited by non-enzymatic decrosslinking of RSC collagen hydrogel system, which could potentially be solved by crosslinking enhancement. In this work, NaIO4 oxidized inositol (NOXIN), a novel crosslinker, was synthesized and its capacity in RSC stabilization was evaluated with texture profile analysis, free amino group content, total soluble protein, water activity, water withholding capacity and scanning electron microscope (SEM). The results show that NOXIN could stabilize RSC in a dose dependent manner by crosslinking the amino groups on collagen, thus enhances the mechanical strength and water holding capacity, retains water activity, and suppresses protein degradation of the hydrogel system, although overdosing compromises the stabilizing effect. The results of this study have not only validated the capacity of NOXIN as protein crosslinker, but also provided reference to the development of new crosslinkers.

In leukemia, knock-down of the death inducer-obliterator gene would inhibit the proliferation of endothelial cells by inhibiting the expression of CDK6 and CCND1.

BACKGROUND: Endothelial cells (ECs) are a critical component of the hematopoietic niche, and the cross-talk between ECs and leukemia was reported recently. This study aimed to determine the genes involved in the proliferation inhibition of endothelial cells in leukemia. METHODS: Human umbilical vein endothelial cells (HUVEC) were cultured alone or co-cultured with K562 cell lines. GeneChip assays were performed to identify the differentially expressed genes. The Celigo, MTT assay, and flow cytometric analysis were used to determine the effect of RNAi DIDO on cell growth and apoptosis. The differently expressed genes were verified by qRT-PCR (quantitative real-time PCR) and western-blot. RESULTS: In K562-HUVEC co-cultured cell lines, 323 down-regulated probes were identified and the extracellular signal-regulated kinase 5 (ERK5) signaling pathway was significantly inhibited. Among the down-regulated genes, the death inducer-obliterator gene (DIDO) is a part of the centrosome protein and may be involved in cell mitosis. As shown in the public data, leukemia patients with lower expression of DIDO showed a better overall survival (OS). The HUVEC cells were infected with shDIDO lentivirus, and reduced expression, inhibited proliferation, and increased apoptosis was observed in shDIDO cells. In addition, the expression of Cyclin-Dependent Kinase 6 (CDK6) and Cyclin D1 (CCND1) genes was inhibited in shDIDO cells. Finally, the public ChIP-seq data were used to analyze the regulators that bind with DIDO, and the H3K4me3 and PolII (RNA polymerase II) signals were found near the Exon1 and exon2 sites of DIDO. CONCLUSION: The knock-down of DIDO will inhibit the proliferation of endothelial cells in the leukemia environment. The expression of DIDO may be regulated by H3K4me3 and the inhibition of DIDO may lead to the down-regulation of CDK6 and CCND1. However, how DIDO interacts with CDK6 and CCND1 requires further study.

[Reconstructing January-June precipitation in Southeastern Shanxi over the past 296 years inferred from tree-ring records of Pinus tabuliformis]. / åŸºäºŽæ²¹æ¾æ ‘è½®é‡å»ºæ™‹ä¸œå—åœ°åŒºè¿‘296年来1­6月降水变化.

The study of regional historical climate change is limited by the availability of observational data, which is not conducive to understanding long-term climate change. In this study, we used the tree-ring cores of Pinus tabuliformis to establish a tree ring width chronology (RES) from the southeast Shanxi Province, and analyzed the relationship between precipitation and tree-ring width chronology. The results showed that the residual chronology had a good correlation (r=0.636, n=59, P<0.01) with January-June precipitation. A linear regression was used to reconstruct the January-June precipitation for the southeastern Shanxi Province, which accounts for 40.4% of the instrumental precipitation variation during 1724-2019. Dry conditions occurred during 1742-1771, 1830-1848, 1872-1894, 1917-1945, 1961-1981, and 1990-2019, while the periods of 1727-1741, 1772-1829, 1849-1871, 1895-1916 were relatively wet. There were 10 extremely dry years and six extremely wet years during the period from 1724 to 2019. The longest dry periods were 1742-1771 and 1990-2019, while the longest wet period was 1772-1829. Results of spatial climate correlation analyses with gridded land surface data showed that the precipitation reconstruction contained a strong regional precipitation signal for southeast Shanxi Province. Power spectrum analysis of the precipitation reconstruction showed remarkable 2.3, 3.2-3.3, 3.7-3.8, 6.3-6.7, 8.3-8.7 years cycles for the past 296 years, the 2.3 year cycle corresponds to the 'quasi-two-year pulsation', and the 3.2-3.3, 3.7-3.8 and 6.3-6.7 year cycles might have a certain relationship with ENSO. Results of the spatial correlation analysis showed that the reconstructed precipitation series could better represent precipitation changes in the study area.

Health service utilisation among African migrants in China: a nationwide cross-sectional study.

OBJECTIVES: To assess the health utilisation status and associated factors among African migrants in China. DESIGN: A national cross-sectional study was conducted among African migrants in China in 2019. SETTING: Participants were recruited online and offline to participate in a self-report survey. Online participants were recruited through WeChat across China, and offline participants were recruited in Guangzhou. PARTICIPANTS: We recruited participants who were from an African country; had spent at least 1 month cumulatively in China; were at least 18 years old; were willing to provide informed consent. A total of 1025 participants were recruited online and offline, 19 of them were excluded due to invalid response and 1006 people were finally included in the analysis. OUTCOME MEASURES: The primary outcome was health service utilisation and associated factors among African migrants during their stay in China in the past 12 months. The potential factors include the predisposing factors (demographic characteristics and social structure variables), enabling factors (annual income, health insurance in China) and need factors (non-communicable chronic and infectious diseases, depression) which determined by Anderson framework were measured. RESULTS: Eight hundred and seven online and 218 offline participants completed the survey, including 624 males and 382 females, with an average age of 26.4±8.9 years. Around 28.5% reported health utilization in the past 12 months. Results showed that longer duration in China, migration to China for business (aOR=2.23, 95% CI:1.13-4.40) and study (aOR=5.00, 95% CI:2.74-9.11), living in apartment (aOR=2.59, 95% CI:1.62-4.14) or dormitory (aOR=3.22, 95% CI:2.17-4.80) in China, suffering from chronic diseases, communicable diseases, and greater depressive symptoms (aOR=1.91, 95% CI:1.42-2.56) facilitated health service utilization. CONCLUSIONS: The healthcare service that African migrants received in China is low. The existing public health policies and intervention measures need to be improved to make health utilisation more accessible and feasible for African migrants.

Mental health on the move: An observational study to characterize post-migration depression symptoms among migrants from Sub-Saharan Africa in China.

OBJECTIVE: Migrants from Sub-Saharan Africa to China faced challenges in accessing healthcare. Less is known about their depression prevalence. We aim to address this gap by providing an initial estimation on symptoms indicative of depression. METHODS: A cross-sectional survey was conducted from August to October in 2019. Eligibility was defined as being originally from a Sub-Saharan African country and cumulative residence in China for at least one month. A convenience sample was drawn from snowball sampling online and venue-based sampling by community outreach. The primary outcome, symptoms indicative of depression, were measured by the Centre for Epidemiologic Studies Depression Scale using 16 as the cutoff. Multivariable logistic regressions were employed to examine the association between depression symptoms and their migration-related correlates. Data were analyzed using SAS 9.4. RESULTS: The prevalence of symptoms indicative of depression assessed by CES-D was high at 44% among 928 participants when using 16 as a cutoff. Depression symptoms were associated with unsatisfactory housing conditions (aOR: 1.7, 95%CI: 0.8 to 3.3) and perception of very unfriendly attitudes from the local people (aOR: 4.5, 95%CI: 1.2 to 16.1) after adjusting for covariates. CONCLUSIONS: Depression symptoms were prevalent among SSA migrants in China and warrants attention and intervention. Support should be provided during the post-migration period in China to mitigate depression risks. Future studies are needed to build more evidence on SSA migrants' mental health and to inform global health policies and programming.

LncRNA TUG1 contributes to the tumorigenesis of lung adenocarcinoma by regulating miR-138-5p-HIF1A axis.

INTRODUCTION: Increasing evidence indicates that lncRNA TUG1 represents an oncogenic factor in cancer. But, the mechanisms by which lncRNA TUG1 contributes to lung adenocarcinoma (LAC) remain undocumented. METHODS: The relationship between lncRNA TUG1/miR-138-5p expression and clinical outcomes in patients with LAC was indicated by qPCR, FISH, and TCGA cohort. Gain- or loss-of-function experiments and in vivo tumorigenesis were used to assess the role of lncRNA TUG1 in LAC. The interplay between TUG1 and miR-138-5p was validated by luciferase gene report and RIP assays. qPCR and Western blot analyses were used to investigate the effects of TUG1 on miR-138-5p/HIF1A axis in LAC cells. RESULTS: We found that upregulation of TUG1 or downregulation of miR-138-5p was associated with lymph node or distant metastasis and indicated a poor survival in LAC. Reduced expression of TUG1 restrained the growth of LAC cells, while restored expression of TUG1 had the opposite effects. TUG1 was identified to negatively regulate miR-138-5p expression, and miR-138-5p reversed TUG1-induced cell proliferation by targeting HIF1A. Elevated expression of HIF1A predicted a poor survival in LAC. CONCLUSION: Our findings demonstrate that lncRNA TUG1 promotes the growth of LAC by regulating miR-138-5p-HIF1A axis.

Perioperation ulinastatin intervention protects liver function in hepatectomy: a systematic review of randomized controlled trials and meta-analysis.

BACKGROUND: Vascular occlusion during hepatectomy accompanies ischemia-reperfusion (IR) injury, which can cause liver dysfunction and affect patients' outcome. Ulinastatin or urinary trypsin inhibitor (UTI), a polyvalent inhibitor of various enzymes, has been confirmed of anti-IR injury effect in recent studies. Here we performed a systematic review and meta-analysis to assess the benefits of perioperation UTI using to protect liver function in hepatectomy. METHODS: Randomized controlled trials (RCTs) evaluating UTI in hepatectomy were identified. Two independent reviewers extracted data on basic characteristics and risk of bias in the studies, and on outcomes such as alanine transaminase (ALT), aspartate transaminase (AST), and total bilirubin (TBIL) from 1 to 7 days after operation. RESULTS: A total of 9 RCTs including 408 UTI and 372 control participants were identified. There was no significant difference in basic characteristics such as age or sex. The majority of the patients who underwent hepatectomy had primary liver carcinoma, liver metastases and benign liver lesions. A significant improvement in liver function was associated with UTI use not only at 1 and 3 days postoperatively, but also at 7 days (all P≤0.01). However, significant heterogeneity existed between the pooled studies (all P<0.01). CONCLUSIONS: UTI has positive protective effects against IR injury in hepatectomy. However, further highquality RCTs are needed to confirm this conclusion.

Dendritic cells fused with endothelial progenitor cells play immunosuppressive effects on angiogenesis in acute myeloid leukemia mice.

This study aimed to explore role of dendritic cells (DCs) fused with endothelial progenitor cells (EPCs) in inhibiting angiogenesis in acute myeloid leukemia (AML) mice. EPCs were isolated from human AML bone marrow mononuclear cells and fused with DCs, which were then injected back into AML mice. Changes in leukemia cells, micro-vessel density (MVD), early EPC molecular markers vascular endothelial growth factor receptor 2 (VEGFR2/KDR) and CD133 in bone marrow were measured. The results indicated that CD133 and KDR expression in EPCs was significantly higher than in epithelial cells (HUVECs). There were 46.14% ± 8.21% DCs doubly positive for VEGFR2 and CD11c, and it was 8.53% ± 1.27% in co-culture group. Fusion rate of DC/EPCs was 37.61% ± 6.94%, and 35.63% ± 6.09% in DC/ECs group. Growth rate of DC/EPCs was faster than that of EPCs (P<0.05). At 14-20 days after fused cells injection, symptoms gradually decreased. There were a greater number of micro-vessels in bone marrow biopsy sections of AML mice than in normal controls (P<0.05). There was slightly lower MVD in EC/DCs compared with EPC/DCs (P>0.05). Positive expression of CD133 and VEGFR2 in bone marrow biopsies of AML mice was significantly higher than that in control mice (P<0.05). Positive expression of CD133 and VEGFR2 in DC/EC fused cells was significantly lower than that before fusion (P<0.05). In conclusion, DC-EPCs play a certain immunosuppressive effect on angiogenesis in AML mice. Our findings provide experimental data support for the construction of a cell vaccine with anti-angiogenic effect.

Characterization of microRNA expression profiles by deep sequencing of small RNA libraries in leukemia patients from Naxi ethnic.

BACKGROUND: Leukemia is a hematological malignancy characterized by the proliferation of early lymphoid precursors that replaces normal hematopoietic cells of the bone marrow. Nakhi (Naxi) ethnic minorities considered to be an area of low incidence. MicroRNAs (miRNAs) are a class of small noncoding RNAs that regulate the expression of other genes in various biological processes. The purpose of this work is to study the molecular mechanism of miRNAs in the leukemia from Naxi. METHODS: Six leukemia patients (case 2 to case 7) and one healthy person (case 1) from Nakhi (Naxi) ethnic minorities were recruited. Total RNA was extracted from these samples and small RNA deep sequencing was performed. RESULTS: A list of miRNAs (1,392 known and candidate 125 novels) expressed in leukocytes were identified, and many differentially regulated targets involved in several cellular pathways, such as cancer, Rap1 signaling pathway, Ras signaling pathway, and endocytosis. Additionally, quantitative real time-polymerase chain reaction (qRT-PCR) results show that hsa-miR-181b-5p, hsa-miR-181a-3p, hsa-miR-181a-5p, and hsa-miR-342-3p has different expression patterns in different cancer cells, hsa-miR-450a-5p, and hsa-miR-1255a were dysregulated in all leukemia cells. CONCLUSIONS: Several abnormal expressed miRNAs in leukemia patients were identified, the correlation of miRNAs dysregulation and leukemia biology demonstrates that specific miRNA can be potential therapeutic target.

Effect of mesenchymal stem cells transplantation combining with hyperbaric oxygen therapy on rehabilitation of rat spinal cord injury.

OBJECTIVE: To investigate the effect of BMSCs transplantation plus hyperbaric oxygen (HBO) on repair of rat SCI. METHODS: Seventy five male rats were divided randomly into five groups: sham, vehicle, BMSCs transplantation group, combination group, 15 rats in each group. Every week after the SCI onset, all animals were evaluated for behavior outcome by Basso-Beattle-Bresnahan (BBB) score and inclined plane test. Axon recovery was examined with focal spinal cord tissue by electron microscope at 6 weeks after the SCI onset. HE staining and BrdU staining were performed to examine the BMSCs and lesion post injury. Somatosensory evoked potential (SEP) testing was performed to detect the recovery of neural conduction. RESULTS: Results from the behavior tests from combination group were significant higher than rats which received only transplantation or HBO treatment. Results from histopathology showed favorable recovery from combination group than other treatment groups. The number of BrdU(+) in combination group were measureable more than transplantation group (P < 0.05). The greatest decrease in TNF-α, IL-1ß, IL-6, IFN-α determined by Elisa assay in combination group were evident too. CONCLUSIONS: BMSCs transplantation can promote the functional recovery of rat hind limbs after SCI, and its combination with HBO has a synergistic effect.

The effects of hyperbaric oxygen on macrophage polarization after rat spinal cord injury.

The immunoreactive responses are a two-edged sword after spinal cord injury (SCI). Macrophages are the predominant inflammatory cells responsible for this response. However, the mechanism underlying the effects of HBOT on the immunomodulation following SCI is unclear now. The present study was performed to examine the effects of hyperbaric oxygen therapy (HBOT) on macrophage polarization after the rat compressive injury of the spinal cord. HBOT was associated with significant increases in IL-4 and IL-13 levels, and reductions in TNF-α and IFN-É£ levels. This was associated simultaneously with the levels of alternatively activated macrophages (M2 phenotype: arginase-1- or CD206-positive), and decreased levels of classically activated macrophages (M1 phenotype: iNOS- or CD16/32-positive). These changes were associated with functional recovery in the HBOT-transplanted group, which correlated with preserved axons and increased myelin sparing. Our results suggested that HBOT after SCI modified the inflammatory environment by shifting the macrophage phenotype from M1 to M2, which may further promote the axonal extension and functional recovery.

Syntheses and structure-activity relationships of nonnatural beta-C-nucleoside 5'-triphosphates bearing an aromatic nucleobase with phenolic hydroxy groups: inhibitory activities against DNA polymerases.

Five nonnatural beta-C-nucleoside 5'-triphosphates bearing a 3,4-dihydroxyphenyl (1TP), a 2-hydroxyphenyl (2TP), a 3-hydroxyphenyl (3TP), a 4-hydroxyphenyl (4TP), or a phenyl (5TP) group were synthesized, and their structure-activity relationships were examined for a series of DNA polymerase reactions in vitro under typical polymerase chain reaction conditions. We found that the 5'-triphosphates (1TP-5TP) are not incorporated into DNA strands but inhibit the DNA polymerase reactions in the presence of natural nucleoside 5'-triphosphates (dNTPs). 1TP having two phenolic hydroxy groups at the nucleobase moiety showed the most potent inhibitory effect against DNA synthesis by Ex Taq polymerase (IC(50) = 30 microM). The competition assay indicated that 1TP and dNTPs are most likely to affect DNA polymerase reactions competitively. This finding may raise the appealing possibility that artificial nucleoside 5'-triphosphates having phenolic hydroxy groups could exhibit potent inhibitory activity against DNA-directed enzymatic reactions.

Role of a non-natural beta-C-nucleotide unit in DNA as a template for DNA and RNA syntheses and as a substrate for nucleolytic digestion.

A non-natural beta-C-nucleoside bearing a 3,4-dibenzyloxyphenyl group as a nucleobase (X) was synthesized and incorporated into a 34-mer oligomer with the sequence 5'-dTTTTTAAAAAAXATATAGCAGCGACATGTCACCG-3'. This synthetic oligonucleotide was examined for template activity in the enzymatic syntheses of DNA by the Klenow fragments of Escherichia coli DNA polymerase I and the recombinant DNA polymerase I, and in the synthesis of RNA by the E. coli RNA polymerase core enzyme. As a result, the template-directed polymerization of both DNA and RNA was precisely terminated at the position of X. The X-containing oligonucleotide was also tested for digestion by an exonuclease, Exo III nuclease (Exo III), and an endonuclease, Mung Bean nuclease (MB). The results indicate that the artificial nucleobase X acts as a terminator for digestion by Exo III, whereas the site X becomes susceptible to digestion by MB. These findings provide a useful tool for the size control of products in the synthesis and degradation of nucleic acids.

Cholesterol-phospholipid complexation in fluid bilayers as evidenced by nearest-neighbor recognition measurements.

Nearest-neighbor recognition experiments have been carried out using varying ratios of exchangeable dimer analogs of 1,2-dimyristoyl-sn-glycero-3-phosphatidylglycerol and 1,2-distearoyl-sn-glycero-3-phosphatidylglycerol in cholesterol-rich unilamellar vesicles at 60 degrees C. Equilibrium dimer distributions that were obtained support a structural model of the liquid-ordered bilayer in which free cholesterol and the longer-chain phospholipid homodimer are in equilibrium with a complex of unique stoichiometry, where one cholesterol molecule combines with two of the long-chain phospholipid homodimers. In this model, the mixing of the short-chain phospholipids with the uncomplexed long-chain phospholipids is ideal, and the complexed dimers are shielded from the disulfide exchange reaction.

Ethanol-induced reorganization of the liquid-ordered phase: enhancement of cholesterol-phospholipid association.

This paper records what is believed to be the first evidence for the reorganization of the liquid-ordered phase by ethanol. Specifically, ethanol has been found to significantly enhance sterol-phospholipid association in liquid-ordered bilayers derived from 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) plus cholesterol and also 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) plus cholesterol. The evidence for such reorganization comes from a series of nearest-neighbor recognition (NNR) experiments that have been carried out, where low concentrations of equilibrating lipid dimers (i.e., "reporter molecules") have been used to detect changes in the phase composition of host membranes made from varying mixtures of DPPC/cholesterol, and also DSPC/cholesterol, in the presence and in the absence of ethanol. These findings have important biological implications, which are briefly discussed.