Biomedical subjects

Wei Xia

Publications and source records attributed to Wei Xia.

At least 37 records · Page 2Linked to original sources

PubMed2005

Angiogenesis is required for successful bone induction during distraction osteogenesis.

UNLABELLED: The role of angiogenesis during mechanically induced bone formation is incompletely understood. The relationship between the mechanical environment, angiogenesis, and bone formation was determined in a rat distraction osteogenesis model. Disruption of either the mechanical environment or endothelial cell proliferation blocked angiogenesis and bone formation. This study further defines the role of the mechanical environment and angiogenesis during distraction osteogenesis. INTRODUCTION: Whereas successful fracture repair requires a coordinated and complex transcriptional program that integrates mechanotransductive signaling, angiogenesis, and osteogenesis, the interdependence of these processes is not fully understood. In this study, we use a system of bony regeneration known as mandibular distraction osteogenesis (DO) in which a controlled mechanical stimulus promotes bone induction after an osteotomy and gradual separation of the osteotomy edges to examine the relationship between the mechanical environment, angiogenesis, and osteogenesis. MATERIALS AND METHODS: Adult Sprague-Dawley rats were treated with gradual distraction, gradual distraction plus the angiogenic inhibitor TNP-470, or acute distraction (a model of failed bony regeneration). Animals were killed at the end of distraction (day 13) or at the end of consolidation (day 41) and examined with muCT, histology, and immunohistochemistry for angiogenesis and bone formation (n = 4 per time-point per group). An additional group of animals (n = 6 per time-point per group) was processed for microarray analysis at days 5, 9, 13, 21, and 41. RESULTS AND CONCLUSIONS: Either TNP-470 administration or disruption of the mechanical environment prevented normal osteogenesis and resulted in a fibrous nonunion. Subsequent analysis of the regenerate showed an absence of angiogenesis by gross histology and immunohistochemical localization of platelet endothelial cell adhesion molecule in the groups that failed to heal. Microarray analysis revealed distinct patterns of expression of genes associated with osteogenesis, angiogenesis, and hypoxia in each of the three groups. Our findings confirm the interdependence of the mechanical environment, angiogenesis, and osteogenesis during DO, and suggest that induction of proangiogenic genes and the proper mechanical environment are both necessary to support new vasculature for bone induction in DO.

Angiogenesis Inhibitors↗

PubMed2005

[Promotion of the survival of ischemic skin flap by transplanted endothelial progenitor cells transfected with VEGF165 gene: an experimental study with mice].

OBJECTIVE: To investigate the feasibility of transplanted endothelial progenitor cells transfected with VEGF165 gene to ischemic flap with increased neovascularization and augmented the survival areas. METHODS: EPCs were isolated from human cord blood and cultured in vitro. Plasmid PcDNA3.1(-)/VEGF165 containing VEGF gene was transfected into the EPCs. EPCs transfected with blank plasmid, and EPCs without transfection were used as controls. ELISA was used to detect the expression of VEGF protein in the culture fluids. The EPCs were dyed with CM-DiI 7 days later. Ischemic skin flaps were made on the backs of 27 nude mice. The mice were randomly divided into 3 equal groups with their skin flaps being transplanted with EPCs transfected with 3.1(-)/VEGF165 plasmid, EPCs not transfected with 3.1(-)/VEGF165 plasmid, and injected with M199 medium at the basal part. Four days after the peduncles of the skin flaps were cut. Seven days after the cutting-off of the peduncles the survival rate of skin flap was observed and the blood perfusion was observed with laser Doppler flowmetry, 10 days after the density of capillary arteries were observed with microcirculation microscope. Three specimens of skin flap were taken 7 and 11 days after the skin flaps were made to undergo histological examination to detect the density of capillary arteries by CD34 immunohistochemistry and to observe the proliferation of EPCs with fluorescence microscopy. Peripheral blood samples were collected 1, 4, 7, 14, and 28 days after the skin flaps were made to undergo ELISA to detect the levels of VEGF protein RESULTS: The VEGF levels in the culture supernatants of the groups A, B, and C were 352 ng/L +/- 35 ng/L, 45 ng/L +/- 5 ng/L, and 0 ng/L respectively with significant difference between any 2 groups (all P < 0.05). The skin flap survival rates of the three groups were 97.2%, 60.3%, and 34.2% respectively with significant difference between any 2 groups (all P < 0.05) and the survival quality of the group A was the best. The capillary density of the group A was greater than those of the groups B and C. The VEGF levels at any time point of the group A were all significantly higher than those of the group B and C (all P < 0.05) and there was not a significant difference between the groups B and C. The capillary density levels at different time points decreased progressively in the order of groups A, B, and C with significant difference between any 2 groups (all P < 0.05). No EPC was shown by fluorescence microscopy in the skin flaps of the group C. The EPC density in skin flap 7 and 11 days after the flaps were made were 136 +/- 10 and 75 +/- 6/mm(2) and 305 +/- 26 and 199 +/- 18/mm(2) respectively with significant differences between the groups A and B. (both P < 0.05). CONCLUSION: The EPCs from human cord blood, especially those transfected with VEGF165 gene increases the neovascularization in ischemic skin flaps and augments their survival rate.

Animals↗

PubMed2005

Gene transfer of somatostatin receptor type 2 by intratumoral injection inhibits established pancreatic carcinoma xenografts.

AIM: To investigate the therapeutic effect of somatostatin receptor type 2 (SSTR2) gene transfection on pancreatic carcinoma xenografts in vivo in experimental cancers. METHODS: Human pancreatic cancer cell line Panc-1 was inoculated subcutaneously into the back of nude mice. When tumor nodules were grown as large as about 5 mmX5 mm days after inoculation, the mice were randomly divided into 3 groups (6 mice in each group). Group I served as untreated control group. Group II received an intratumoral injection of a combination of human cytomegalovirus promoter-6C (pCMV-6C) and lipofectamine 2000. Group III received an intratumoral injection of a combination of pCMV-6C-SSTR2 and lipofectamine 2000. The rate of tumor growth was compared among these three groups. The expression of SSTR2 in these tumors was detected by immunohistochemistry and Western-blot. Apoptosis index (AI) in these tumors was examined by using TUNEL in situ. RESULTS: Intratumoral injection of a combination of pCMV-6C-SSTR2 and lipofectamine 2000 resulted in the expression of SSTR2 protein. The tumor size and weight in group III (0.318+/-0.098 cm3, and 0.523+/-0.090 g, respectively) were significantly lower than those in group I (2.058+/-0.176 cm3, and 1.412+/-0.146 g, respectively) and group II (2.025+/-0.163 cm3, and 1.365+/-0.116 g, respectively) (P<0.05) The AI in group III (1.47+/-0.13%) was significantly higher than that in group I (0.56+/-0.09%) and group II (0.57+/-0.11%) (P<0.05). But there were no significant differences between groups I and II. CONCLUSION: Our data demonstrate that re-expression of SSTR2 gene has antitumor effects on experimental pancreatic cancer. Restoration of SSTR2 gene expression through gene transfer in vivo might be a potential gene therapy strategy for human pancreatic cancer.

Animals↗

PubMed2005

High-dose retinoic acid modulates rat calvarial osteoblast biology.

Retinoic acid has been shown to adversely affect craniofacial development. Cleft palate and craniosynostosis are two examples of craniofacial defects associated with prenatal exposure to this agent. Although the effects of retinoic acid on cephalic neural crest-derived tissues have previously been studied, the specific effects of retinoic acid on the cellular biology of osteoblasts remain unclear. The purpose of this study was to analyze in detail the effects of pharmacologic doses of retinoic acid on the differentiation and proliferation of osteoblasts derived from an intramembranous source. Primary rat calvarial osteoblasts were established in culture and treated with 1 or 10 microM all-trans-retinoic acid. Retinoic acid treatment markedly increased expression of osteopontin up to 48 h after stimulation. Consistent with this early stage of differentiation, both mRNA and protein analysis of FGF receptor isoforms demonstrated a switch in predominance from fibroblast growth factor receptor 2 (fgfr2) to fgfr1. Analysis of PCNA protein confirmed inhibition of proliferation by retinoic acid. To determine whether these alterations in osteoblast biology would lead to increased differentiation, we examined short term [alkaline phosphatase (AP) activity] and long term (von Kossa staining) surrogates of bone formation in vitro. These assays confirmed that retinoic acid increased osteogenesis, with a 4-fold increase in bone nodule formation in cells treated with 10 microM retinoic acid after 28 days. Overall, our results demonstrated that pharmacologic doses of all-trans-retinoic acid decreased osteoblast proliferation and increased differentiation, suggesting that retinoic acid may effect craniofacial development by pathologically enhancing osteogenesis.

Alkaline Phosphatase↗

PubMed2005

Transient transfection of CHO-K1-S using serum-free medium in suspension: a rapid mammalian protein expression system.

With the recent completion of the human genome sequencing project, scientists now face the daunting challenge of deciphering the function of these newly found genes quickly and efficiently. For biotechnology, it is equally important to identify the therapeutically relevant genes as quickly as possible. Mammalian expression systems provide many advantages to aid in this task. Mammalian cell lines have the capacity for proper post-translational modifications, including proper protein folding and glycosylation. In response to these needs, a CHO-K1 cell line that grows in suspension and in serum-free media was initially established and designated CHO-K1-S. An antibody gene of interest was chosen as the target for optimization rather than a reporter gene system. A comparison of various lipid transfection reagents was made using recombinant protein expression as the endpoint readout. Various other parameters including lipid:DNA ratios, cell density, and transfections in shaker versus spinner flasks were tested using the CHO-K1-S cell line. As a result, a rapid and reliable transient transfection protocol was developed. Using this procedure, we have produced milligram/per liter quantities of bioactive recombinant proteins from several genes of interest.

Animals↗

PubMed2005

Potentiation of T cell function by a marine algae-derived sulfated polymannuroguluronate: in vitro analysis of novel mechanisms.

Marine algae-derived sulfated polymannuroguluronate (SPMG), a candidate drug for AIDS treatment, was intraperitoneally injected into normal mice for 6 weeks, and the in vivo and in vitro mechanisms of SPMG for immunomodulation were investigated in isolated lymphocytes by MTT assay, flow cytometry, and surface plasmon resonance assay. SPMG treatment at 5 and 10 mg/kg enhanced concanavalin A (ConA)-induced T cell proliferation, cellular levels of CD69, interleukin-2 (IL-2), and interferon-gamma (IFN-gamma), as well as CD4/CD8 ratio, while decreasing tumor necrosis factor-alpha (TNF-alpha) level in T cells of peripheral blood mononuclear cells. In addition, 1 molecule of SPMG bound to 2/3 molecules of IL-2 with a K(D) of 9.53 x 10(-7) M. Heparin prevented SPMG binding to IL-2 by 72.2%; thus, to a large extent, SPMG and heparin share common binding sites on IL-2. In contrast, other glycosaminoglycans (e.g., chondroitin sulfate and dermatan sulfate) had little effect on SPMG and IL-2 interaction, suggesting the requirement of a defined sequence within the sugar chain for specific recognition of IL-2. Concomitant treatment of IL-2 and SPMG augmented lymphocyte proliferation, compared with IL-2 alone; in contrast, SPMG alone had no proliferative effect. Taken together, our findings demonstrated for the first time that SPMG exerted its immunomodulation by direct activation of T cell function, accompanied by simultaneous modulation of cytokine function, which suggests that SPMG would show great promise for use in anti-AIDS therapy.

Adjuvants, Immunologic↗

PubMed2005

[Reversal of multidrug resistance in drug-resistant cell line EAC/ADR by cepharanthine hydrochloride and its mechanism].

AIM: To investigate the correlation between reversal effect of cepharanthine hydrochloride (CH) on multidrug resistance (MDR) in drug-resistant cell line EAC/ADR and the nuclear transcription factor-KB (NF-KB). METHODS: Cytotoxicity was determined by the tetrazolium (MTT) assay in vitro. An EAC/ADR cell homograft model was established to investigate the effect of CH on reversing MDR in vivo. The constitutive activity and activation of NF-KB by drugs were measured by Dot-Enzyme-linked Immune Sorbent Assay (Dot-ELISA). RESULTS: CH was shown to potentiate the cytotoxicity of ADR, a 13- fold reversal effect of resistance was achieved in vitro. In mice bearing EAC/ADR cell homografts, CH was found to prolong the survival time of animals bearing tumor. Increase in life span over control was 75. 37%. In addition, the constitutive activity of NF-KB and activation of NF-KB by chemotherapy were lowered by CH. CONCLUSION: The findings suggest that CH is able to reverse drug resistance and its mechanism may be related to suppressing the constitutive activity and activation of NF-KB by drugs.

Alkaloids↗

PubMed2004

The two-step chemical vapor deposition of Pd(allyl)Cp as an atom-efficient route to synthesize highly dispersed palladium nanoparticles on carbon nanofibers.

Highly dispersed palladium nanoparticles supported on carbon nanofibers, which show high catalytic activity and stability in the hydrogenation of cyclooctene, were synthesized by the two-step metal organic chemical vapor deposition (MOCVD) of allylcyclopentadienylpalladium (Pd(allyl)Cp) as precursor at atmospheric pressure.

Journal Article↗

PubMed2004

Identification of hypoxia-regulated proteins in head and neck cancer by proteomic and tissue array profiling.

Hypoxia within solid tumors decreases therapeutic efficacy, and identification of hypoxia markers may influence the choice of therapeutic modality. Here, we used a proteomic approach to identify hypoxia-regulated proteins and validated their use as endogenous indicators of tumor hypoxia. Using two-dimensional gel electrophoresis and PowerBlot (antibody-based array), we identified a group of 20 proteins that are increased >/=1.5-fold during hypoxia. The majority of these proteins such as IkappaB kinase beta (IKKbeta), MKK3b, highly expressed in cancer (HEC), density-regulated protein 1, P150(glued), nuclear transport factor 2, binder of ARL 2, Paxillin, and transcription termination factor I have not been previously reported to be hypoxia inducible. The increase in these proteins under hypoxia was mediated through posttranscriptional mechanisms. We additionally characterized the role of IKKbeta, a regulator of the nuclear factor-kappaB transcription factor, during hypoxia. We demonstrated that IKKbeta mediates cell survival during hypoxia and is induced in a variety of squamous cell carcinoma cell lines. Furthermore, we showed that IKKbeta expression from tumor specimens correlated with tumor oxygenation in patients with head and neck squamous cell carcinomas. These data suggest that IKKbeta is a novel endogenous marker of tumor hypoxia and may represent a new target for anticancer therapy.

Carcinoma, Squamous Cell↗

PubMed2004

LB films of rodlike phthalocyanine aggregates: specular X-ray reflectivity studies of the effect of interface modification on coherence and microstructure.

We present here X-ray specular reflectivity (XRR) characterization of the ordering of Langmuir-Blodgett films of the liquid crystalline phthalocyanine (Pc) 2,3,9,10,16,17,23,34-octakis(2-benzyloxyethoxy)copper(II) phthalocyanine, 1, on Si(100) wafers with a native oxide layer and these same substrates modified with monolayers of varying percentages of methyl- and phenyl-terminated silanes. The central copper atom in these Pc's provides for high contrast in X-ray reflectivity for single-bilayer films of 1. The XRR data are modeled as arising from multiple layers of organic material, above and below the rows of copper atoms in the aligned Pc cores; variations in the total thickness of these films, and the spacing between the rows of copper atoms, are attributed to changes in the interaction with the substrate, and changes in the Pc orientation and side chain packing. The most pronounced effect on these parameters comes from variations in the ratio of the phenyl-silane versus methyl-silane content of the substrate modifiers and annealing of these films past their crystalline (K) --> liquid crystalline (LC) mesophase transition temperature. Transfer of multiple bilayers of this Pc leads to additional changes in the thickness of each layer, eventually forming a hexagonal close-packed array, reminiscent of bulk fibers of this material, as revealed by X-ray diffraction (XRD).

Journal Article↗

PubMed2004

Ring finger protein ZIN interacts with human immunodeficiency virus type 1 Vif.

Virion infectivity factor (Vif) protein of human immunodeficiency virus type 1 (HIV-1) is essential for the productive infection of primary human CD4 T lymphocytes and macrophages. Vif overcomes the HIV-inhibitory effects of cellular factor APOBEC3G, which has cytidine deaminase activity. We previously reported the isolation of a Vif-interacting ring finger protein, Triad 3, from a human leukocyte cDNA library, using the yeast two-hybrid system. The full-length cellular protein homologue of Triad 3 has been recently identified as the zinc finger protein inhibiting NF-kappaB (ZIN). Sequence analysis indicates that Triad 3 protein contains all four major ring-like motifs of ZIN. We report here that ZIN binds to purified Vif in vitro and that Triad 3/ZIN interacts with HIV-1 Vif in transfected human 293T cells, as demonstrated by coimmunoprecipitation. To test the biological relevance of this interaction, we produced infectious HIV-1 NL4.3 in the presence or absence of cotransfected ZIN. HIV-1 NL4.3 virus stocks produced in the presence of exogenously expressed ZIN were twofold less infectious in a single-cycle infectivity assay than virus produced in the absence of exogenous ZIN. It was further shown that cells infected with HIV NL4.3 virus stocks produced in the presence of exogenously expressed ZIN were impaired in viral DNA synthesis by twofold. The impairment in viral reverse transcription and the reduction in single-cycle viral infectivity were both shown to be dependent on the presence of Vif in the virus producer cells. The possible mechanisms by which ZIN interferes with the early events of HIV-1 replication are discussed.

Amino Acid Sequence↗

PubMed2004

[The design of the expanded flap for the repair of the temporal and cheek area].

OBJECTIVE: To explore the design of an expanded flap at the temporal and cheek area. METHODS: The expanded flap was used for the repair of 619 temporal and cheek defects secondary to scar, nevus or hemangioma excision. In the frontal area, the rotational flap was usually used. For the repair of the cheek, the applied flap included the rotational, advanced, and transposition flap from the neck, as well as the pedicle flap from the thoracic area. RESULTS: Eight thoracic-deltoid flaps had distal necrosis of 1 approximately 5 cm. Of them, 5 flaps were repositioned with subsequent good result; the other 3 flaps underwent skin grafting. The five facial expanded flaps showed distal necrosis of 0.5 approximately 1 cm. Of them, 4 flaps occurred delayed healing, 1 flap underwent skin grafting. Expander extrusion happened in 41 cases (6.62%), which resulted in deficiency of the expanded area. Satisfactory results were achieved in all the other cases. CONCLUSIONS: According to our experience, careful design of the flap is very important for obtainingbetter surgical results and decreasing complications.

Adolescent↗

PubMed2004

[Isolation of beta-carotene from discarded tobacco leaves].

Beta-carotene was isolated from discarded tobacco leaves by column chromatography using petroleum ether as eluent. Its structure was characterized by 1H-NMR and 13C-NMR spectra. The purity of the beta-carotene was determined to be 98% by a high performance liquid chromatographic (HPLC) method which was demonstrated to be accurate and reproducible. Infra-red spectrum and melting point of the isolated sample were also characterized in agreement with those reported in literature. The overall yield of 80%, the high purity and the easiness to recycle as the results of only a single solvent employed, would make the method an important reference for future research of beta-carotene and a favorable technique for future development.

Chromatography, High Pressure Liquid↗

PubMed2003

Expression of urokinase-type plasminogen activator and its receptor is up-regulated during tendon healing.

The urokinase-type plasminogen activator (uPA) system has been implicated in cell migration, angiogenesis, extracellular matrix synthesis and tissue remodelling. However, little is known about the role of the system in tendon healing. We used a rat Achilles tendon model to study mRNA and protein expression of uPA and its receptor (uPAR) during tendon healing using immunohistochemical, Northern and Western blot analyses. Time-dependent increases in uPA/uPAR mRNAs and proteins, maximal on days 4-7 and 7-14 respectively, were found following Achilles tendon division. Interestingly, uninjured control tendons expressed uPA mRNA and protein, but little uPAR transcripts and protein. On day 14 following Achilles tendon division, uPA receptor protein increased 12.6-fold (p<0.001) while uPA itself increased only 1.3-fold (p<0.05). Immunohistochemical analyses revealed that both uPAR/uPA positive staining cells were increased in the healing tendon tissue section. These findings show for the first time that uPA, and especially its receptor uPAR, are up-regulated during tendon healing.

Achilles Tendon↗

PubMed2003

[Effects of chromium and fish oil on blood lipid and blood glucose in obese rats].

UNLABELLED: Obesity does great harm to people's health. In order to study the effects of chromium and fish oil on blood lipid and blood glucose in obese rats, 32 obese model rats were divided randomly into four groups: fish oil group(5 ml/kg BW), chromium group(3 mg/kg BW), fish oil + chromium group and high fat diet group. In the end of the experiment(6 weeks) fats around kidney and spermary were weighted and blood samples were collected to determine blood glucose and blood lipid. Result shows that blood glucose and blood lipid in experimental groups were lower than those in high fat diet group. The ratios of fats around kidney and/or around spermary to body weight in experimental groups were lower than those in high fat diet group. CONCLUSION: Chromium and fish oil decrease the risk of obese relative diseases.

Animals↗

PubMed2003

[Change of expression of P-selectin in avulsion-injured vessels].

OBJECTIVE: To determine the change of P-selectin in avulsion-injured vessels. METHODS: Different stretch forces of 60, 70, 80 and 90 g were applied to a vascular injury model. The expression changes of P-selectin were evaluated by RT-PCR. RESULTS: The expression of P-selection mRNA in the injured vessels increased with the stretch force. CONCLUSION: The result associated with our previous study indicated that P-selectin may be involved in thrombosis.

Animals↗

PubMed2002

Mitogen-induced, FAK-dependent tyrosine phosphorylation of the SSeCKS scaffolding protein.

The ability of mitogens to rapidly induce tyrosine phosphorylation of cellular proteins has been taken as evidence of participation in subsequent signaling pathways. SSeCKS, a major protein kinase C (PKC) substrate with protein scaffolding and tumor suppressive properties, becomes tyrosine phosphorylated in NIH3T3 and rodent embryo fibroblasts after short-term treatment with epidermal growth factor (EGF), platelet-derived growth factor (PDGF), or fetal calf serum in the presence of pervanadate, but not by treatment with insulin or insulin-like growth factor-1. The relative phosphotyrosine level on SSeCKS was higher in actively dividing cells than in confluent cultures. Tyrosine phosphorylation of SSeCKS was apparent in cells deficient in Src, Fyn, Yes, or Abl tyrosine kinases or in NIH3T3 cells expressing a temperature-sensitive v-Src allele, but not in FAK-deficient embryo fibroblasts. Purified FAK or Src enzyme failed to directly phosphorylate SSeCKS in vitro. EGF failed to induce SSeCKS tyrosine phosphorylation in FAK-/- fibroblasts, indicating that the EGF receptor is probably not the direct kinase of SSeCKS. Phosphorylation under these conditions was rescued by the transient reexpression of wt-FAK but not FAK mutated at Y397, a major autophosphorylation and SH2-based docking site. Adhesion of FAK+/+ cells to fibronectin failed to significantly induce SSeCKS tyrosine phosphorylation although FAK was activated, suggesting that SSeCKS phosphorylation is mediated through a growth factor receptor-FAK rather than an integrin-FAK pathway. Moreover, PDGF could induce SSeCKS tyrosine phosphorylation in the absence of FAK activation, suggesting a role for FAK SH2-based docking rather than kinase activity. Immunofluorescence analysis showed that in FAK-/- cells, SSeCKS costains along F-actin stress fibers, in contrast to FAK+/+ cells, where most SSeCKS stains at the cell edge and along a cortical cytoskeletal matrix. This correlated with increased coprecipitation of SSeCKS with biotin-phalloidin-bound F-actin from FAK-/- compared to FAK+/+ cell lysates. Similarly, bacterially expressed, unphosphorylated SSeCKS cosedimented with F-actin in ultracentrifugation assays. These data suggest that mitogen-induced, FAK-dependent tyrosine phosphorylation of SSeCKS modulates its binding to the actin-based cytoskeleton, suggesting a role for SSeCKS in mitogen-induced cytoskeletal reorganization.

3T3 Cells↗

PubMed2002

Role of planar chirality of S,N- and P,N-ferrocene ligands in palladium-catalyzed allylic substitutions.

Palladium-catalyzed asymmetric allylic substitutions using thioether and phosphino derivatives of ferrocenyloxazoline as ligands have been investigated with a focus on studying the role of planar chirality. In allylic alkylation, up to 98% ee and 95% ee were achieved with S,N- and P,N-ligands, respectively. In allylic amination, 97% ee was realized with P,N-ligands in the presence of TBAF. Several palladium allylic complexes were characterized by X-ray diffraction and/or solution NMR. Thioether derivatives of ferrocenyloxazolines with only planar chirality showed lower enantioselectivity in the allylic alkylation except 5c because of the formation of a new chirality on sulfur atom during the coordination of sulfur with palladium. On the other hand, in the planar chiral P,N-ligands without central chirality, (Sp)-11a-c there was no such disturbance and comparatively higher enantioselectivity in both palladium-catalyzed allylic alkylation and amination was provided.

Journal Article↗