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Background Pulmonary fibrosis is a fatal lung disease with limited treatment options. Icaritin is the active ingredient derived from the traditional Chinese medical plant Epimedium and possesses many biomedical activities. This study aimed to investigate the effects and molecular mechanisms of icaritin on bleomycin-induced pulmonary fibrosis in mice. Methods To assess its preventative effects, bleomycin treated mice received 0, 0.04, 0.2, and 1 mg/kg of icaritin from day 1 onwards. To assess its therapeutic effects, bleomycin treated mice received 0 and 1 mg/kg of icaritin from day 15 onwards. Mice were sacrificed on day 21 and lung tissues were collected, stained with HE, Masson and immunohistochemistry. Q-PCR was used to measure Collagen I and Collagen III expression, western blotting was used to quantify α-SMA, Collagen I expression. Hydroxyproline content was measured using a biochemical method. NIH3T3 and HLF-1 cells were treated with TGF-β1with or without icaritin, and α-SMA, Collagen I were tested. PPARγ antagonist GW9662 and PPARγ-targeted siRNA were used to investigate the mechanism of icaritin in inhibiting myofibroblast differentiation. Results Both preventative and therapeutic administration of icaritin improved the histopathological changes, decreased Collagen and α-SMA, lowered hydroxyproline content in bleomycin-treated lung tissues. Icaritin decreased α-SMA and Collagen I expression in TGF-β1-stimulated NIH3T3 and HLF-1 cells. However, its effect in reducing α-SMA and Collagen I expression was suppressed when expression or activity of PPARγ was inhibited. Conclusions Icaritin has therapeutic potential against pulmonary fibrosis via the inhibition of myofibroblast differentiation, which may be mediated by PPARγ.

Axillary reverse mapping (ARM) is a technique to identify arm lymphatic drainage during axillary lymph node dissection (ALND). This study compared the feasibility of ARM using indocyanine green (ICG) or methylene blue (MB), and accessed the oncologic safety of the procedure. Overall, 158 patients qualified for ALND were enrolled. The characteristics of ARM‐identified nodes were recorded with ICG (n = 78) or MB (n = 80) visualization. Fine‐needle aspiration cytology (FNAC) of the nodes were performed and validated by histologic analysis. The nodal identification rate in the ICG group significantly surpassed that of the MB group (87.2% vs 52.5%, P, Axillary reverse mapping (ARM) using indocyanine green is feasible with a higher identification rate of ARM nodes and fewer complications. Note that 10.9% of the patients had metastatic involvement of the ARM‐identified nodes. FNAC, together with the features of primary tumors and ARM nodes, could delineate the patient profiles who can use ARM safely.

Objective The present study explored the effects of grape seed procyanidin extract (GSPE) on rumen fermentation, methane production and archaeal communities in vitro. Methods A completely randomized experiment was conducted with in vitro incubation in a control group (CON, no GSPE addition; n = 9) and the treatment group (GSPE, 1 mg/bottle GSPE, 2 g/kg dry matter; n = 9). The methane and volatile fatty acid concentrations were determined using gas chromatography. To explore methane inhibition after fermentation and the response of the ruminal microbiota to GSPE, archaeal 16S rRNA genes were sequenced by MiSeq high-throughput sequencing. Results The results showed that supplementation with GSPE could significantly inhibit gas production and methane production. In addition, GSPE treatment significantly increased the proportion of propionate, while the acetate/propionate ratio was significantly decreased. At the genus level, the relative abundance of Methanomassiliicoccus was significantly increased, while the relative abundance of Methanobrevibacter decreased significantly in the GSPE group. Conclusion In conclusion, GSPE is a plant extract that can reduce methane production by affecting the structures of archaeal communities, which was achieved by a substitution of Methanobrevibacter with Methanomassiliicoccus.

This study investigated the total viable counts, sensory and physicochemical qualities (total volatile basic nitrogen, K-value, thiobarbituric acid reactive substances value, water holding capacity and texture parameters), as well as water distribution of fresh hairtail fish during simulated cold chain. The results showed that total volatile basic nitrogen, thiobarbituric acid reactive substances and K-values increased with the increasing time, while sensory scores, water holding capacity, hardness and elasticity decreased. The transverse relaxation time T2 data detected by low-field nuclear magnetic resonance also showed that T22 (trapped water) gradually decreased with the increasing time, while T23 (free water) increased. It was observed that the quality deterioration of the fish fillets developed more quickly when the samples suffered frequent temperature fluctuations than they stored at higher but stable temperatures. The changes of T22 and T23 of both the samples stored at stable and fluctuated temperatures showed good correlations with sensory, total volatile basic nitrogen and thiobarbituric acid reactive substances values (R2 > 0.9, p

Tamoxifen resistance (TamR) prevents ER-positive breast cancer patients from benefitting from endocrine therapy, and miR-221 or miR-222 plays vital roles in inducing TamR. In this study, we designed synthetic sponges to reverse TamR by targeting these two miRs. First, we established a tamoxifen resistant breast cancer cell line (MCF-7TamR), we verified the high expressing level of these two miRs in TamR cells. miR-221 or miR-222 inhibitors rendered MCF-7TamR cells responsive to tamoxifen. Next, we designed a miR-221/222 sponge, which contains total 8 multi-antisense binding sites (MBSs) for these two onco-miRs, and inserted it into CMV promoter- or hTERT promoter-driven expressing vectors. After transfected miR-221/222 sponge expressing vectors into MCF-7TamR cells, we identified a strong interaction between miR-221/222 sponge and endogenous miR-221 or miR-222 by RNA pulldown assay. We also found that miR-221/222 sponge restored the expression of ERα and PTEN, arrested cells in G1 phase, and finally resulted in reduced cell growth and cell migration. Notably, miR-221/222 sponge expressing cells abrogates tamoxifen resistance through restoring the expression of ERα, suggesting that miR-221/222 sponge gene therapy especially driven by tumor specific promoter could provide an effective therapeutic approach against TamR in breast cancer. Supplementary Information The online version contains supplementary material available at 10.1186/s43556-021-00045-0.

Rationale: Although significant progress has been made in understanding the mechanisms of steatosis and insulin resistance, the physiological functions of regulators in these processes remain largely elusive. Evidence has suggested that the glutamate/N-methyl-D-aspartic acid receptor (NMDAR) axis contributes to acute lung injury, pulmonary arterial hypertension, and diabetes, but the specific metabolic contribution of the glutamate/NMDAR axis is not clear. Here we provide data at the animal, cellular, and molecular levels to support the role of the glutamate/NMDAR axis as a therapeutic target for metabolic syndrome in obesity. Methods: We examined the glutamate level in the obese mouse induced by a high-fat diet (HFD) for 12 weeks. To assess the role of NMDAR in insulin sensitivity and lipid metabolism, we tested the effects of Memantine (an NMDAR antagonist) and NMDA (an NMDAR agonist) on mice fed with HFD or standard chow diet. The in vitros NMDAR roles were analyzed in hepatocytes and potential mechanisms involved in regulating lipid metabolism were investigated. Results: Glutamate was increased in the serum of HFD-treated mice. The NMDAR blockade by Memantine decreased the susceptibility to insulin resistance and hepatic steatosis in obese mice. NMDA treatment for 6 months induced obesity in mice, characterized by hyperglycemia, hyperlipidemia, insulin resistance, and pathological changes in the liver. We provided in vitro evidence demonstrating that NMDAR activation facilitated metabolic syndrome in obesity through promoting lipid accumulation. NMDAR inhibition attenuated lipid accumulation induced by palmitic acid. Mechanistically, NMDAR activation impaired fatty acid oxidation by reducing PPARα phosphorylation and activity. The PPARα activity reduction induced by NMDAR activation was reversibly mediated by ERK1/2 signaling. Conclusion: These findings revealed that targeting NMDAR might be a promising therapeutic strategy for metabolic syndrome in obesity.

Despite remarkable advancements in our understanding of breast cancer, it remains the leading cause of cancer deaths in women. Distant recurrence and metastasis is the main reason for death due to breast cancer. It is well recognized that the GATA binding protein 3 (GATA3), a transcription factor, is a tumor suppressor in breast cancer. To date, the mechanistic molecular details of GATA3 remain elusive, because, as a transcription factor, it is not a direct executor in physiological and pathological processes. Here, we demonstrate that GATA3 reduces the ATP level in the breast cancer microenvironment and inhibits breast cancer metastasis by up-regulating ectonucleoside triphosphate diphosphohydrolase 3 (ENTPD3). The extracellular ATP concentration is significantly higher in tumor tissues than in normal tissues and promotes the migration of cancer cells from the primary site. ENTPD3 hydrolyzes ATP in tumor microenvironment and suppresses breast cancer metastasis. Furthermore, ENTPD3 inhibits epithelial-to-mesenchymal transition, a key program responsible for the development of metastatic disease. These findings provide novel insights into the tumor suppressor activity of GATA3.

Increasing evidence has shown that pseudogenes can widely regulate gene expression. However, little is known about the specific role of PTENP1 and miR-499-5p in insulin resistance. The relative transcription level of PTENP1 was examined in db/db mice and high fat diet (HFD)-fed mice by real-time PCR. To explore the effect of PTENP1 on insulin resistance, adenovirus overexpressing or inhibiting vectors were injected through the tail vein. Bioinformatics predictions and a luciferase reporter assay were used to explore the interaction between PTENP1 and miR-499-5p. The relative transcription level of PTENP1 was largely enhanced in db/db mice and HFD-fed mice. Furthermore, the overexpression of PTENP1 resulted in impaired Akt/GSK activation as well as glycogen synthesis, while PTENP1 inhibition led to the improved activation of Akt/GSK and enhanced glycogen contents. More importantly, PTENP1 could directly bind miR-499-5p, thereby becoming a sink for miR-499-5p. PTENP1 overexpression results in the impairment of the insulin-signaling pathway and may function as a competing endogenous RNA for miR-499-5p, thereby contributing to insulin resistance.

Cationic latexes have received wide attention due to their special properties and potential applications in wood coatings, fabric treatment, etc. However, the practical application of cationic latexes was hindered due to their poor stability, especially the alkali resistance stability. In this work, various stable cationic polyacrylate latexes were prepared by an efficient route. Three cationic comonomers, i.e., methacrylatoethyl trimethyl ammonium chloride (DMC), 2-(dimethylamino)ethyl methacrylate (DMAEMA), and 2-aminoethyl methacrylate hydrochloride (AEMH), were used in the aqueous semi-continuous seeded emulsion polymerization of methyl methacrylate (MMA) and butyl acrylate (BA) using cetyl trimethyl ammonium bromide (CTAB) and 2,2′-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (AIBI) as the cationic emulsifier and initiator, respectively. The alkali resistance of the latex could be significantly improved by the addition of cationic monomer DMC and be simply tuned by adjusting DMC dosage. The improved stability of the latex might originate from the higher charge density on the surface of the latex by the introduction of DMC. Moreover, the effects of initiator dosage, emulsifier dosage and different cationic comonomers on the latex preparation and the film properties were also systematically investigated. This work not only introduces an efficient route to prepare cationic latexes with superior stability, but also paves the way for latexes to be used in applications such as textile finishing, paper industry, and biomedical field, etc.

For deep imaging depth and least invasiveness, people commonly use 1100-1300 nm femtosecond laser sources to perform label-free in vivo microscopy. The modalities include reflectance confocal, two & three photon fluorescence, and second & third harmonic generation microscopy. However, most of the laser sources are typically based on bulky oscillators, which are sensitive to environment conditions and less stable for routine clinical use. In contrast, fiber-based lasers have simpler cavity design and potentially compact size for movable use. In this presentation, we demonstrate a fiber-based 1150 nm femtosecond laser source, with 6.5 nJ pulse energy, 86 fs pulse-width, and 11.25 MHz pulse repetition rate. It was achieved by a Bismuth Borate (BIBO) or Magnesium-doped periodically poled Lithium Niobate (MgO:PPLN) mediated frequency doubling of the 2300 nm solitons, generated from an excitation of 1550 nm Er:fiber femtosecond laser pulses on a large mode area photonic crystal fiber. Combined with a laser scanned microscope and a home-build data acquisition card, we achieve a pulse-per-pixel harmonic generation microscopy in vivo at a 30 Hz frame rate. In the future, this solution is potential to be used for label-free clinical virtual optical biopsy.

Metabolic reprogramming is a hallmark of cancer. Glycine decarboxylase (GLDC), an oxidoreductase, plays an important role in amino acid metabolism. While GLDC promotes tumor initiation and proliferation in non-small cell lung cancer and glioma and it was reported as a putative tumor suppressor gene in gastric cancer, the role of GLDC in hepatocellular carcinoma (HCC) is unknown. In the current study, microarray-based analysis suggested that GLDC expression was low in highly malignant HCC cell lines, and clinicopathological analysis revealed a decrease in GLDC in HCC tumor samples. While the knockdown of GLDC enhanced cancer cell migration and invasion, GLDC overexpression inhibited them. Mechanistic studies revealed that GLDC knockdown increased the levels of reactive oxygen species (ROS) and decreased the ratio of glutathione/oxidized glutathione (GSH/GSSG), which in turn dampened the ubiquitination of cofilin, a key regulator of actin polymerization. Consequently, the protein level of cofilin was elevated, which accounted for the increase in cell migration. The overexpression of GLDC reversed the phenotype. Treatment with N-acetyl-L-cysteine decreased the protein level of cofilin while treatment with H2O2 increased it, further confirming the role of ROS in regulating cofilin degradation. In a tumor xenographic transplant nude mouse model, the knockdown of GLDC promoted intrahepatic metastasis of HCC while GLDC overexpression inhibited it. Our data indicate that GLDC downregulation decreases ROS-mediated ubiquitination of cofilin to enhance HCC progression and intrahepatic metastasis.

Adsorption and desorption of proteins on biomaterial surfaces play a critical role in numerous biomedical applications. Spherical diblock polymer brushes (polystyrene with photoiniferter (PSV) as the core) with different block sequence, poly(acrylic acid)-b-poly(N-(2-hydroxyethyl) acrylamide) (PSV@PAA-b-PHEAA) and poly(N-(2-hydroxyethyl) acrylamide)-b-poly(acrylic acid) (PSV@PHEAA-b-PAA) were prepared via surface-initiated photoiniferter-mediated polymerization (SI-PIMP) and confirmed by a series of characterizations including TEM, Fourier transform infrared (FTIR) and elemental analysis. Both diblock polymer brushes show typical pH-dependent properties measured by dynamic light scattering (DLS) and Zeta potential. It is interesting to find out that conformation of PSV@PAA-b-PHEAA uniquely change with pH values, which is due to cooperation of electrostatic repulsion and steric hindrance. High-resolution turbidimetric titration was applied to explore the behavior of bovine serum albumin (BSA) binding to diblock polymer brushes, and the protein adsorption could be tuned by the existence of PHEAA as well as apparent PAA density. These studies laid a theoretical foundation for design of diblock polymer brushes and a possible application in biomedical fields.

The effect of the graphite/epoxy composite patch parameters on the static and fatigue strength of the cracked aluminum plate was investigated experimentally. A series of specimens repaired by six types of composite patches including four different patch lengths and two different patch thicknesses were tested on the material tester. Specimens single-sided repaired and double-sided repaired by the same composite patches were also tested. The experiment results show that composite patches can provide an improvement in static and fatigue strength of the cracked aluminum plate, double-sided repair is more effective than single-sided repair, if the thickness and the length were selected properly, the composite patches can significantly enhance the strength of the repaired specimens.

It is attractive to use multi-wall carbon nanotubes (MWNTs), which has a high modulus and strength, to enhance the properties of metal matrix composites by hybrid strategy. In this paper, novel aluminum borate whisker (ABOw) and MWNTs hybrid composites were prepared by squeeze cast technique and the properties were investigated. The results show that hybrid preforms may be made by co-deposition of ABOw and MWNTs in a solution by wet method. MWNTs separate the ABOw from whisker-to-whisker contact and decrease the compressive deformation of the hybrid preforms during squeeze cast processing. MWNTs distribute along mainly in the grains of aluminum matrix, making the mechanical properties of the hybrid composites higher than singularly reinforced composite.

A squeeze casting 15vol.%SiCw/Al and pure aluminum were cold rolled to 50 pct reduction in thickness and then annealed at 500°C for 1h. The textures of the treated materials were examined using XRD. The dominant texture components in the cold rolled composites consisted of {112}、{100} and {123} and were much weaker than those in the cold rolled aluminum. The new texture components in annealed composites were {211}、{013} and {011} and had the similar intensity as those remained from the deformation state. This indicated that the recovery reaction and recrystallization occurred simultaneously when the cold rolled composite was annealed at 500°C. Also, the annealing texture was much weaker in the composite than that in the aluminum. The weaker deformation and annealing textures in the composites can be attributed to the introduction of the whiskers.

Objective To test the effect of 8 weeks of lower body resistance training on hyperglycemia and dyslipidemia, which may be prevalent among nonelderly, nondiabetic, chronically disabled stroke patients. Design Randomized controlled study. Setting Outpatient clinics of rehabilitation centers. Participants Nonelderly, nondiabetic, chronically disabled stroke subjects (N=56) were enrolled and randomly assigned to an experimental group (n=28) and a control group (n=28). Interventions Lower body resistance training was performed by subjects in the experimental group 3 times a week for 8 weeks. The control group was given duration-matched stretch exercises. Main Outcome Measures Fasting glucose level, fasting insulin level, 2-hour blood glucose level during oral glucose tolerance test, homeostasis model assessment of insulin resistance (HOMA-IR), glycosylated hemoglobin (Hb A 1c ), total triglyceride level, total cholesterol level, high-density lipoprotein (HDL) cholesterol level, low-density lipoprotein (LDL) cholesterol level, body mass index, lower limb muscle strength, and Fugl-Meyer motor score. Results Before the intervention, 34 subjects (60.7%) had hyperglycemia and 38 (67.9%) had dyslipidemia. Fifty-one subjects finished the study. Subjects in the experimental group (n=26) showed significant improvements in fasting insulin and 2-hour blood glucose levels; HOMA-IR; total cholesterol, HDL cholesterol, and LDL cholesterol levels; and muscle strength compared with control subjects (n=25) after the intervention ( P Conclusions Resistance training may play a significant role in improving hyperglycemia and dyslipidemia, which are frequently present among nonelderly, nondiabetic, chronically disabled stroke patients.

OBJECTIVE Impaired glucose tolerance (IGT) and diabetic glucose tolerance (DGT) are closely associated with vascular disease mortality and morbidity. This study was designed to determine whether routine stroke rehabilitation training can be used to improve the glucose status and whether IGT and DGT persist among nondiabetic stroke patients at discharge after such training. METHODS Eighty eligible subjects were evaluated using Oral Glucose Tolerance Tests (OGTTs) at entry and discharge at the rehabilitation medical departments of two large hospitals in China. Routine rehabilitation training was provided during hospitalization. The secondary outcome measurements were BMI, Fugl-Meyer motor score, Barthel index, HbA1c, triglycerides, HDL cholesterol and LDL cholesterol. Non-acute and nondiabetic stroke patients treated at the rehabilitation department. RESULTS Fifty-four patients had IGT or DGT at entry, while 61 patients exhibited abnormal glucose tolerance at discharge, accounting for 67.7% and 76.25% of all subjects respectively. The mean 2-hour plasma glucose level was 8.98 mmol/L at entry and 9.11 mmol/L at discharge. No changes were noted in the OGTT results or secondary outcomes after training (p>0.05), with the exceptions of significant improvements in the Fugl-Meyer motor score and Barthel index (p

Amino acid phosphoramidates of adenosine were synthesized and determined by positive and negative ion electrospray ionization mass spectrometry (ESI-MS) in conjunction with tandem mass spectrometry (MS/MS). The fragmentation pathways were investigated. In the positive ion mass spectra abundant characteristic fragment ions appeared, and many complementary ions were found. In the negative ion mass spectra only a few fragment ions were observed, and most of them contained phosphoryl groups. The results show that ESI-MS is a useful tool for structural determination of amino acid phosphoramidates of nucleosides.

Reactions of fresh pentacoordinate phosphoric-amino acid mixed anhydrides with amine and alcohol yielded peptide analogs, N-phosphoamino acid esters, phosphodiesters and some products of ester exchange, which might provid some evidence that the formation of pentacoordinate intermediates was crucial to some bioorganic reactions of N-Phosphoamino acids.

Dimyristoylphosphatidylglycerol (DMPG), dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylethanolamine (DMPE) were characterized by electron impact (EIMS), field desorption (FDMS) and liquid secondary ion (LSIMS) mass spectrometry. The results showed that the fragmentation processes of the three phospholipids are very similar. In the EI mass spectra, no molecule-ion peaks were found, the peaks of the fatty acid chains being dominant. The results of FDMS and LSIMS showed that both techniques worked particularly well with all three kinds of phospholipids. The FD mass spectra of all three phospholipid gave strong MH+ peaks, and no fragmental peaks were found except that of DMPC. With LSIMS, the fragmentations of all the phospholipids were extensive and clear, and gave dominant peaks of MH+. The cleavages around phosphate groups were the most abundant. An interesting phenomenon was found in the LSIMS measurements that all three kinds of phospholipids formed intense peaks of molecule-ion clusters, [2M+H]+, [3M+H]+ and [4M+H]+, etc. It was found that the formation of the molecule-ion clusters was related to several factors: concentration, ionic strength, pH, etc., among which concentration is the most important. The degree of cluster formation increased with increase in concentration of phospholipid. The results also showed that the nature of the matrix is critical to a successful LSIMS analysis of phospholipids, and (S)-glycerol was confirmed as a very satisfactory matrix for these phospholipids. © 1997 John Wiley & Sons, Ltd.

Harmonic generation microscopy (HGM) has become one unique tool of optical virtual biopsy for the diagnosis of cancer and the in vivo cytometry of leukocytes. Without labeling, HGM can reveal the submicron features of tissues and cells in vivo. For deep imaging depth and minimal invasiveness, people commonly adopt 1100- to 1300-nm femtosecond laser sources. However, those lasers are typically based on bulky oscillators whose performances are sensitive to environmental conditions. We demonstrate a fiber-based 1150-nm femtosecond laser source, with 6.5-nJ pulse energy, 86-fs pulse width, and 11.25-MHz pulse repetition rate. It was obtained by a bismuth borate or magnesium-doped periodically poled lithium niobate (MgO:PPLN) mediated frequency doubling of the 2300-nm solitons, generated from an excitation of 1550-nm femtosecond pulses on a large mode area photonic crystal fiber. Combined with a home-built laser scanned microscope and a tailor-made frame grabber, we achieve a pulse-per-pixel HGM imaging in vivo at a 30-Hz frame rate. This integrated solution has the potential to be developed as a stable HGM system for routine clinical use.

A 45-year-old woman visited our department due to enlargement and ulceration of the right breast. Core needle biopsy and pathological examination revealed invasive ductal carcinoma of right breast (grade II). Immunohistochemistry showed that tissues were negative for estrogen receptor (ER) and progesterone receptor (PR), but positive for epidermal growth factor receptor-2 (Her-2) (+++) and vascular endothelial growth factor (VEGF) (+). Whole body positron emission tomography (PET) scan indicated multiple lymph node metastases and bone metastases. On examination, the performance status scored 1 (Eastern Cooperative Oncology Group (ECOG) score system). Salvage therapy was performed with bevacizumab and taxotere, carboplatin and herceptin (TCH) regimen (Taxol: 130 mg [d1, 8 and 15] + carboplatin: 160 mg [d1, 8 and 15] + herceptin: [first dose: 220 mg] 110 mg once weekly, 28 days as a course of chemotherapy). Bevacizumab (Avastin; 500 mg) was administered four times (once every two weeks). If necessary, zoledronic acid (Zometa) was given at 4 mg once monthly. Nine days after treatment, the tumor significantly shrunk and the ulcered tissues fell off. After 4 courses of treatment, positron emission tomography-computed tomography (PET-CT) showed that the cancer disappeared. Key words: Metastatic breast cancer, pathological complete remission, partial remission, avastin, trastuzumab.

The fullerenes C 60 and C 70 were prepared in gram quantities by the Kraetschmer-Huffman method and purified by Al 2 O 3 column chromatography. The characterization of mass spectra of C 60 and C 70 were studied by EIMS, DEIMS, FDMS, and metastable ion MS techniques.

The self-assembly products of N-(O,O'-diisopropyl)-L-alpha-amino acids in aqueous media, N-(O,O'-diisopropyl)phosphoryl dipeptides and tripeptides, were identified by electrospray ionization mass spectrometry. A stepwise fragmentation of the [M + H](+) ions from the C-terminus of N-phosphopeptides was observed. Copyright 2000 John Wiley & Sons, Ltd.

Aminoacyl adenylate pentacoordinated phosphorus compounds were analyzed by field desorption (FD) and fast atom bombardment (FAB) mass spectrometries, together with the B/E linked scan technique, and their mass spectral fragmentation pathways were investigated. For the five bonds (one P-N bond, three P-O bonds and one mixed anhydride bond P-O-CO), the cleavage usually occurred more on the P-N bond, the mixed anhydride bond and the O-C bond adjacent to the P-O bond, and less on the P-O bond. Ion YH(+), corresponding to water loss from protonated 2',3'-O-isopropylidene-adenosine, was the base peak. The results reflect the structural characteristics of aminoacyl adenylate pentacoordinated phosphorus compounds. Copyright 1999 John Wiley & Sons, Ltd.

Amino acid-nucleotide conjugates have important biological functions and therapeutic applications. For example, aminoacyl adenylates are key intermediates in aminoacyl tRNA synthetase reactions. They may also be involved in the prebiotic synthesis of polypeptides. Finally, various amino acid carbomethoxy aryl phosphoramidates of nucleotide prodrugs may be activated through a mechanism involving a pentacoordinated phosphorane intermediates. In order to understand better the chemistry of these compounds, a phenylalanyl adenylate pentacoodinated phosphorane has been synthesized in 72% yield and its decomposition in aqueous solution studied. Hydrolysis gave 2′,3′-O-isopropylidene adenosine 5′-monophosphate, 2′,3′-O-isopropylidene adenosine, and phenylalanine. The results provide model chemistry for the enzymatic degradation mechanism of antiviral aryl amino acid phosphodiester amidates in cells, which leads to their activation.

Circulation in bubble columns, such as those used in fischer-tropsch synthesis, detracts from their performance in that gas is carried on average more rapidly through the column, and the residence time distribution of the gas in the column is widened. Both of these factors influence mass-transfer operations in bubble columns. Circulation prediction and measurement has been undertaken using probes, one-dimensional models, laser Doppler velocimetry, and numerical modeling. Local void fraction was measured using resistance probes and a newly developed approach to determining air/water threshold voltage for the probe. A tall column of eight inch diameter was constructed of Plexiglas and the distributor plate was manufactured to distribute air evenly through the base of the column. Data were gathered throughout the volume at three different gas throughputs. Bubble velocities proved difficult to measure using twin probes with cross-correlation because of radial bubble movement. A series of three-dimensional mean and RMS bubble and liquid velocity measurements were also obtained for a turbulent flow in a laboratory model of a bubble column. These measurements have been made using a three-component laser Doppler velocimeter (LDV), to determine velocity distributions non-intrusively. Finally, the gas-liquid flow inside a vertically situated circular isothermal column reactor was simulated numerically. 74 refs., 170 figs., 5 tabs.