Biomedical subjects

Min Chen

Publications and source records attributed to Min Chen.

At least 145 records · Page 8Linked to original sources

PubMed2005

[Multilayer amniotic membrane transplantation for treatment of necrotizing herpes simplex stromal keratitis].

OBJECTIVE: To evaluate the efficacy of multilayer amniotic membrane transplantation (AMT) combined with antivirus and corticosteroid drug to treat necrotizing herpes simplex stromal keratitis. METHODS: Thirteen patients (13 eyes) of necrotizing stromal keratitis were referred to Shandong Eye Institute and Qingdao Eye Hospital between January 2003 and April 2004. The course of disease was 3 - 22 months (mean 15 months). Corneal inflammation persisted and corneal ulcer progressed despite topical and systemic antiviral treatment for over 1 weeks. Multilayer amniotic membrane transplantation was performed after excluding of bacterial and fungal infection by microbiologic studies including smears and cultures of necrotic corneal tissue and confocal microscope. Topical and systemic antiviral medications were given with adjuvant corticosteroid eyedrops postoperatively. We investigated the healing of corneal ulcer and improvement of stromal edema with slit lamp biomicroscope, the integrity of corneal defect with fluorescein staining, the migration of healthy corneal epithelial cells and transformation of amniotic membrane with confocal microscopy. All patients were followed up for 3 - 13 months (mean 10 months). RESULTS: Corneal ulcer healed within 1 - 3 weeks postoperatively with negative fluorescein staining. Corneal stromal edema faded away within 1 month. Superficial amniotic membrane patches dissolved or shed on postoperative day 7 - 10, while the deeper grafts were adhered into the ulcer and fused with the surrounding fibroblasts. One of these grafts remained in situ more than 3 months. Confocal microscope examination indicated flat epithelial progenitor cells on the surface of residual amniotic membrane. Corneal transparence was achieved in 7 eyes, macula in 4 eyes and leucoma in 2 eyes 3 months after the operation. No recurrence of necrotizing stromal keratitis was occurred in 13 patients during the follow-up period. CONCLUSION: Multilayer AMT combined with antivirus and corticosteroid treatment is an effective method to treat necrotizing herpes simplex stromal keratitis.

Acyclovir↗

PubMed2005

[Development of the study on germplasm resources of medicinal plants: construction of core collection].

According to the successful experience of studying on crops, this paper introduced the conception of the core collection of medicinal plants, and analyzed the characteristic and the way to construct it. Studies on the core collection would fulfill the management and utilize the germplasm resources conveniently and provide a new idea and a method to study on the germplasm resources of medicinal plants. It is necessary to study on the core collection for the development of the germplasm resources of medicinal plants.

Chromatography, High Pressure Liquid↗

PubMed2005

[Development and application of multiplex-PCR for identification of Actinobacillus pleuropneumoniae].

A multiplex-PCR assay was developed to identify Actinobacillus pleuropneumoniae (App). Two pairs of polymerase chain reaction (PCR) primers were designed for the 16S rRNA and the apxlVA gene, which is specific to all serotypes of App. Two PCR products of 692bp and 363bp were obtained, from the 16S rRNA and the apxlVA gene respectively, for 27 reference A. pleuropneumoniae strains. Only the 692bp fragment was amplified for closely related strains including A. lignieresii. Using the designed primers, the method is capable of detecting A. pleuropneumoniae of as low as 1.3 x 10(3) CFU or 9pg DNA. For 302 suspected isolates, this multiplex-PCR method correctly identified 4 A. pleuropneumoniae strains. The result suggests the use of the multiplex-PCR for routine identification of App.

Actinobacillus pleuropneumoniae↗

PubMed2005

[Clustered shoot induction and rapid propagation on Pinellia ternate].

OBJECT: To establish the rapid propagation system of Pinellia ternate. METHOD: The Clustered shoots were induced by the explant lamina and petiole from the terminal bud of Pinellia ternate tuber in test tube. RESULT: The plantlets could regenerate from the lamina and petiole directly without via the callus. The MS Medium with 2.0 mg/L 6-BA and 0.1 mg/L NAA was optimal for the induction of culstered shoots from explants of lamina; the MS with 2.0 mg/L 6-BA and 0.25 mg/L NAA was best for the explants of petiole; and the 1/2 MS with 1.0 mg/L KT and 2.0 mg/L NAA was the better medium for induction of roots. CONCLUSION: The regenerated rate of Pinellia ternata can improve by inducing the clustered shoots from the explants of lamina and petiole directly.

Culture Media↗

PubMed2004

Streamlined system for purifying and quantifying a diverse library of compounds and the effect of compound concentration measurements on the accurate interpretation of biological assay results.

As part of an overall systems approach to generating highly accurate screening data across large numbers of compounds and biological targets, we have developed and implemented streamlined methods for purifying and quantitating compounds at various stages of the screening process, coupled with automated "traditional" storage methods (DMSO, -20 degrees C). Specifically, all of the compounds in our druglike library are purified by LC/MS/UV and are then controlled for identity and concentration in their respective DMSO stock solutions by chemiluminescent nitrogen detection (CLND)/evaporative light scattering detection (ELSD) and MS/UV. In addition, the compound-buffer solutions used in the various biological assays are quantitated by LC/UV/CLND to determine the concentration of compound actually present during screening. Our results show that LC/UV/CLND/ELSD/MS is a widely applicable method that can be used to purify, quantitate, and identify most small organic molecules from compound libraries. The LC/UV/CLND technique is a simple and sensitive method that can be easily and cost-effectively employed to rapidly determine the concentrations of even small amounts of any N-containing compound in aqueous solution. We present data to establish error limits for concentration determination that are well within the overall variability of the screening process. This study demonstrates that there is a significant difference between the predicted amount of soluble compound from stock DMSO solutions following dilution into assay buffer and the actual amount present in assay buffer solutions, even at the low concentrations employed for the assays. We also demonstrate that knowledge of the concentrations of compounds to which the biological target is exposed is critical for accurate potency determinations. Accurate potency values are in turn particularly important for drug discovery, for understanding structure-activity relationships, and for building useful empirical models of protein-ligand interactions. Our new understanding of relative solubility demonstrates that most, if not all, decisions that are made in early discovery are based upon missing or inaccurate information. Finally, we demonstrate that careful control of compound handling and concentration, coupled with accurate assay methods, allows the use of both positive and negative data in analyzing screening data sets for structure-activity relationships that determine potency and selectivity.

Biological Assay↗

PubMed2004

Chondrocyte-specific knockout of the G protein G(s)alpha leads to epiphyseal and growth plate abnormalities and ectopic chondrocyte formation.

UNLABELLED: G(s)alpha is a ubiquitously expressed G protein alpha-subunit that couples receptors to adenylyl cyclase. Mice with chondrocyte-specific ablation of the G(s)alpha gene had severe epiphyseal and growth plate abnormalities and ectopic cartilage formation within the metaphyseal region of the tibia. These results show that G(s)alpha negatively regulates chondrocyte differentiation and is the critical signaling mediator of the PTH/PTH-rP receptor in growth plate chondrocytes. INTRODUCTION: G(s)alpha is a ubiquitously expressed G protein alpha-subunit that mediates signaling through G protein-coupled receptors to activate the cAMP/protein kinase A signaling pathway. Although studies suggest an important role for G(s)alpha in regulating growth plate development, direct in vivo results examining this role are lacking. MATERIALS AND METHODS: The G(s)alpha gene was ablated in murine cartilage by mating mice with loxP sites surrounding the G(s)alpha promoter and first exon with collagen 2a1 promoter-Cre recombinase transgenic mice. Skeletal tissues were studied by gross and microscopic pathology, and gene expression was determined by in situ hybridization. RESULTS AND CONCLUSIONS: Mice with complete chondrocyte-specific G(s)alpha deficiency (homozygotes) died within minutes after birth and had severe epiphyseal and growth plate defects with shortening of the proliferative zone and accelerated hypertrophic differentiation of growth plate chondrocytes, a phenotype similar to that of PTH/PTH-related peptide (PTHrP) receptor knockout mice. Indian hedgehog and PTH/PTHrP receptor expression in prehypertrophic chondrocytes was unaffected in mutant mice. PTHrP expression in periarticular cartilage was increased in the mutant mice, probably because of the closer proximity of Ihh-secreting chondrocytes to the periarticular zone. In addition, these mice developed ectopic cartilage at the anterior side of the metaphyseal region in the tibia. Mice with partial G(s)alpha deficiency (heterozygotes) exhibited no phenotype. These results show that G(s)alpha negatively regulates chondrocyte differentiation and is the critical signaling mediator of the PTH/PTHrP receptor in epiphyseal and growth plate chondrocytes.

Animals↗

PubMed2004

Poly(ADP-Ribose) polymerase promotes cardiac remodeling, contractile failure, and translocation of apoptosis-inducing factor in a murine experimental model of aortic banding and heart failure.

Oxidant stress-induced activation of poly(ADP-ribose) polymerase (PARP) plays a role in the pathogenesis of various cardiovascular diseases. We have now investigated the role of PARP in the process of cardiac remodeling and heart failure in a mouse model of heart failure induced by transverse aortic constriction (banding). The catalytic activity of PARP was inhibited by the potent isoindolinone-based PARP inhibitor INO-1001 or by PARP-1 genetic deficiency. PARP inhibition prevented the pressure overload-induced decrease in cardiac contractile function, despite the pressure gradient between both carotid arteries being comparable in the two experimental groups. The development of hypertrophy, the formation of collagen in the hearts, and the mitochondrial-to-nuclear translocation of the cell death factor apoptosis-inducing factor (AIF) were attenuated by PARP inhibition. The ability of the inhibitor to block the catalytic activity of PARP was confirmed by immunohistochemical detection of poly(ADP-ribose), the product of the enzyme in the heart. Plasma levels of INO-1001, as measured at the end of the experiments, were in the concentration range sufficient to block the oxidant-mediated activation of PARP in murine cardiac myocytes in vitro. Myocardial hypertrophy and AIF translocation was also reduced in PARP-1-deficient mice undergoing aortic banding, compared with their wild-type counterparts. Overall, the current results demonstrate the importance of poly(ADP-ribos)ylation in the pathogenesis of banding-induced heart failure.

Animals↗

PubMed2004

Cloning and functional analysis of a cDNA encoding Ginkgo biloba farnesyl diphosphate synthase.

Farnesyl diphosphate synthase (FPS; EC2.5.1.1/EC2. 5.1.10) catalyzes the synthesis of farnesyl diphosphate, and provides precursor for biosynthesis of sesquiterpene and isoprenoids containing more than 15 isoprene units in Ginkgo biloba. Here we report the cloning, characterization and functional analysis of a new cDNA encoding FPS from G. biloba. The full-length cDNA (designated GbFPS) had 1731 bp with an open reading frame of 1170 bp encoding a polypeptide of 390 amino acids. The deduced GbFPS was similar to other known FPSs and contained all the conserved regions of trans-prenyl chain-elongating enzymes. Structural modeling showed that GbFPS had the typical structure of FPS, the most prominent feature of which is the arrangement of 13 core helices around a large central cavity. Southern blot analysis revealed a small FPS gene family in G. biloba. Expression analysis indicated that GbFPS expression was high in roots and leaves, and low in stems. Functional complementation of GbFPS in an FPS-deficient strain confirmed that GbFPS mediates farnesyl diphosphate biosynthesis.

Alkyl and Aryl Transferases↗

PubMed2004

Unique origin and lateral transfer of prokaryotic chlorophyll-b and chlorophyll-d light-harvesting systems.

pcb genes, encoding proteins binding light-harvesting chlorophylls, were cloned and sequenced from the Chl d-containing cyanobacterium, Acaryochloris marina, and the Chl b-containing cyanobacterium, Prochloron didemni. Both organisms contained two tandem pcb genes. Peptide fingerprinting confirmed the expression of one of the A. marina pcb genes. Phylogenetic tree reconstruction using distance-matrix and maximum-likelihood methods indicated a single origin of the pcb gene family, whether occurring in Chl b-containing or Chl d-containing organisms. This may indicate widespread lateral transfer of the Pcb protein-based light-harvesting system.

Biological Evolution↗

PubMed2004

Mitochondrial-to-nuclear translocation of apoptosis-inducing factor in cardiac myocytes during oxidant stress: potential role of poly(ADP-ribose) polymerase-1.

OBJECTIVE: Oxidant stress-induced activation of poly(ADP-ribose) polymerase (PARP) plays a role in the pathogenesis of various cardiovascular diseases. We have now investigated the role of PARP in the death of cardiac myocytes in response to oxidant stress induced by hydrogen peroxide, with focus on the mitochondrial function. METHODS AND RESULTS: Using wild-type and PARP-1-deficient murine myocytes challenged with hydrogen peroxide, we found that mitochondrial respiration and mitochondrial membrane potential were better preserved in PARP-deficient myocytes and cellular NAD+ levels were maintained. The release of the mitochondrial cell death factor cytochrome c, and the mitochondrial-to-nuclear translocation of apoptosis-inducing factor (AIF) were also attenuated in the PARP-deficient myocytes. CONCLUSION: PARP-1, directly or indirectly, regulates the translocation of AIF in myocytes subjected to oxidative stress. The current results are consistent with the view that PARP-1 activation, via induction of mitochondrial dysfunction and promotion of mitochondrial cell death pathways, plays a deleterious pathophysiological role under conditions of oxidative stress.

Animals↗

PubMed2004

Minireview: GNAS: normal and abnormal functions.

GNAS is a complex imprinted gene that uses multiple promoters to generate several gene products, including the G protein alpha-subunit (G(s)alpha) that couples seven-transmembrane receptors to the cAMP-generating enzyme adenylyl cyclase. Somatic activating G(s)alpha mutations, which alter key residues required for the GTPase turn-off reaction, are present in various endocrine tumors and fibrous dysplasia of bone, and in a more widespread distribution in patients with McCune- Albright syndrome. Heterozygous inactivating G(s)alpha mutations lead to Albright hereditary osteodystrophy. G(s)alpha is imprinted in a tissue-specific manner, being primarily expressed from the maternal allele in renal proximal tubules, thyroid, pituitary, and ovary. Maternally inherited mutations lead to Albright hereditary osteodystrophy (AHO) plus PTH, TSH, and gonadotropin resistance (pseudohypoparathyroidism type 1A), whereas paternally inherited mutations lead to AHO alone. Pseudohypoparathyroidism type 1B, in which patients develop PTH resistance without AHO, is almost always associated with a GNAS imprinting defect in which both alleles have a paternal-specific imprinting pattern on both parental alleles. Familial forms of the disease are associated with a mutation within a closely linked gene that deletes a region that is presumably required for establishing the maternal imprint, and therefore maternal inheritance of the mutation results in the GNAS imprinting defect. Imprinting of one differentially methylated region within GNAS is virtually always lost in pseudohypoparathyroidism type 1B, and this region is probably responsible for tissue-specific G(s)alpha imprinting. Mouse knockout models show that G(s)alpha and the alternative G(s)alpha isoform XLalphas that is expressed from the paternal GNAS allele may have opposite effects on energy metabolism in mice.

Animals↗

PubMed2004

A Cyp1a2-luciferase transgenic CD-1 mouse model: responses to aryl hydrocarbons similar to the humanized AhR mice.

Here we describe a transgenic mouse model [Crl:CD-1(ICR)BR-Tg(Cyp1a2-luc)Xen] using luciferase as a reporter for Cyp1a2 gene regulation. An 8.4-kilobase mouse Cyp1a2 promoter driving the firefly luciferase gene was microinjected into single-cell-stage CD-1 mouse embryos. A transgenic mouse line was selected based on basal and induced levels of the transgene in mouse liver by an in vivo bioluminescent imaging method. The basal levels of the luciferase reporter in liver were expressed much higher than other tissues, which correlated well with the endogenous Cyp1a2 mRNA tissue distribution. Male signals were about 23-fold higher than females in liver. However, the Cyp1a2 mRNA showed no gender difference. When mice were challenged with xenobiotics, the liver luciferase signal was induced to various degrees. At the doses we used, the relative effects were phenobarbital > 2,3,7,8-tetrachlorodibenzo-p-dioxin > 3-methylcholanthrene > benzo[a]pyrene and beta-naphthoflavone. Induction of the Cyp1a2-luc reporter was generally consistent with the endogenous Cyp1a2 mRNA. However, phenobarbital induction was unexpectedly higher, while beta-naphthoflavone induction of the reporter was much lower than that of the endogenous Cyp1a2 gene. Induction of the Cyp1a2-luc transgene by aryl hydrocarbons (Ah) in the CD-1 background was much less than that found in the Ah responsive C57BL/6 mice, while being similar to the nonresponsive DBA/2 strain. Sequence analysis of the CD-1 Ah receptor (AhR) cDNA clones demonstrated that consensus sequence was identical to some of the Ah-responsive strains such as BALB/C and CBA/J mice. The 104-kD AhR protein was not detectable in CD-1 mice, while the 97-kD AhR was detected in the C57BL/6 mice by Western blot using an AhR antibody. Low expression of the AhR in CD-1 mice could be in part responsible for low responsiveness to Ah compounds. The findings demonstrated the outbred CD-1 mouse is a low-responsive strain, and the Cyp1a2-luc transgenic CD-1 mice can be used for studying the regulation of the mouse Cyp1a2 gene in an Ah low-responsive strain in real time using the bioluminescent imaging approach.

Amino Acid Sequence↗

PubMed2004

Functional non-equivalence of ATP-binding cassette signature motifs in the transporter associated with antigen processing (TAP).

The transporter associated with antigen processing (TAP) is a key component of the cellular immune system. As a member of the ATP-binding cassette (ABC) superfamily, TAP hydrolyzes ATP to energize the transport of peptides from the cytosol into the lumen of the endoplasmic reticulum. TAP is composed of TAP1 and TAP2, each containing a transmembrane domain and a nucleotide-binding domain (NBD). Here we investigated the role of the ABC signature motif (C-loop) on the functional non-equivalence of the NBDs, which contain a canonical C-loop (LSGGQ) for TAP1 and a degenerate C-loop (LAAGQ) for TAP2. Mutation of the leucine or glycine (LSGGQ) in TAP1 fully abolished peptide transport. However, TAP complexes with equivalent mutations in TAP2 still showed residual peptide transport activity. To elucidate the origin of the asymmetry of the NBDs of TAP, we further examined TAP complexes with exchanged C-loops. Strikingly, the chimera with two canonical C-loops showed the highest transport rate whereas the chimera with two degenerate C-loops had the lowest transport rate, demonstrating that the ABC signature motifs control peptide transport efficiency. All single site mutants and chimeras showed similar activities in peptide or ATP binding, implying that these mutations affect the ATPase activity of TAP. In addition, these results prove that the serine of the C-loop is not essential for TAP function but rather coordinates, together with other residues of the C-loop, the ATP hydrolysis in both nucleotide-binding sites.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2004

One-step synthesis of FePt nanoparticles with tunable size.

A one-step synthesis of FePt nanoparticles is reported. The size, composition, and shape of the particles are controlled by varying the synthetic parameters such as molar ratio of stabilizers to metal precursor, addition sequence of the stabilizers and metal precursors, heating rate, heating temperature, and heating duration. An assembly of large (6 nm or greater) FePt nanoparticles, especially oxide-coated FePt nanoparticles, can sustain higher temperature (up to 650 degrees C) annealing without noticeable particle sintering. Room temperature coercivity of an assembly containing discrete FePt dots can reach as high as 1.3 T, a value that is suitable for hard magnetic applications.

Journal Article↗

PubMed2004

[Supraorbital keyhole approach for microsurgical treatment of aneurysms in the anterior circulation].

OBJECTIVE: To study the method with endoscope-assisted microsurgical technique through the supraorbital keyhole approach to treat aneurysms in the anterior circulation. METHODS: According to preoperative diagnostic imagings, to work out of the individual operation planning. Skin incision was made in the eyebrow, and the diameter of supraorbital craniotomy was about 2 cm, endoscope-assisted microsurgical technique was used to clip aneurysm. The technique was used in the most recent 12 consecutive patients. RESULTS: Five different kinds of aneurysms in the anterior circulation were clipped through this method and 12 patients were cured. One patient, intraoperative accidental aneurysm rupture occurred. There were no approach-related complications. CONCLUSIONS: This endoscope-assisted microsurgical technique via supraorbital keyhole approach is a safe, minimal invasive and effective way for the treatment of aneurysms in the anterior circulation, and there is more sufficient operating space.

Adult↗

PubMed2004

A rapid and efficient method to express target genes in mammalian cells by baculovirus.

AIM: To investigate the modification of baculovirus vector and the feasibility of delivering exogenous genes into mammalian cells with the culture supernatant of Spodoptera frugiperta (Sf9) cells infected by recombinant baculoviruses. METHODS: Two recombinant baculoviruses (BacV-CMV-EGFPA, BacV-CMV-EGFPB) containing CMV-EGFP expression cassette were constructed. HepG2 cells were directly incubated with the culture supernatant of Sf9 cells infected by recombinant baculoviruses, and reporter gene transfer and expression efficiencies were analyzed by flow cytometry (FCM). The optimal transduction conditions were investigated by FCM assay in HepG2 cells. Gene-transfer and expression efficiencies in HepG2 or CV1 cells by baculovirus vectors were compared with lipofectAMINE, recombinant retrovirus and vaccinia virus expression systems. Twenty different mammalian cell lines were used to investigate the feasibility of delivering exogenous genes into different mammalian cells with the culture supernatant of infected Sf9 cells. RESULTS: CMV promoter could directly express reporter genes in Sf9 cells with a relatively low efficiency. Target cells incubated with the 1:1 diluted culture supernatant (moi=50) for 12 h at 37 degrees C could achieve the highest transduction and expression efficiencies with least impairment to cell viability. Under similar conditions the baculovirus vector could achieve the highest gene-transfer and expression efficiency than lipofectAMINE, recombinant retrovirus and vaccinia virus expression systems. Most mammalian cell lines could be transduced with recombinant baculovirus. In primate adherent culture cells the recombinant baculovirus could arrive the highest infection and expression efficiencies, but it was not very satisfactory in the cell lines from mice and suspended culture cells. CONCLUSION: Mammalian cells incubated with the culture supernatant of infected Sf9 cells could serve as a very convenient way for rapid and efficient expression of foreign genes in mammalian cells, but it might be more suitable for primate adherent culture cells.

Animals↗

PubMed2004

Increased insulin sensitivity in paternal Gnas knockout mice is associated with increased lipid clearance.

The G protein alpha-subunit Gsalpha is required for hormone-stimulated cAMP generation. The Gsalpha gene Gnas is a complex gene with multiple imprinted gene products. Mice with heterozygous disruption of the Gnas paternal allele (+/p-) are partially Gsalpha deficient and totally deficient in XLalphas, a neuroendocrine-specific Gsalpha isoform that is expressed only from the paternal Gnas allele. We previously showed that these mice are hypermetabolic and lean and have increased insulin sensitivity. We now performed hyperinsulinemic-euglycemic clamp studies, which confirmed the markedly increased whole body insulin sensitivity in +/p- mice. +/p- mice had 1.4-, 7- and 3.8-fold increases in insulin-stimulated glucose uptake in muscle and white and brown adipose tissue, respectively, and markedly suppressed endogenous glucose production from the liver. This was associated with increased phosphorylation of insulin receptor and a downstream effector (Akt kinase) in both liver and muscle in response to insulin. Triglycerides cleared more rapidly in +/p- mice after a bolus administered by gavage. This was associated with decreased liver and muscle triglyceride content and increased muscle acyl-CoA oxidase mRNA expression. Resistin and adiponectin were overexpressed in white adipose tissue of +/p- mice, although there was no difference in serum adiponectin levels. The lean phenotype and increased insulin sensitivity observed in +/p- mice is likely a consequence of increased lipid oxidation in muscle and possibly other tissues. Further studies will clarify whether XLalphas deficiency is responsible for these effects and if so, the mechanism by which XLalphas deficiency leads to this metabolic phenotype.

Adiponectin↗

PubMed2004

Three-wave solitons and continuous waves in media with competing quadratic and cubic nonlinearities.

We formulate a general model of three-wave optical interactions (in the spatial domain), which combines quadratic (chi(2)) and cubic (chi(3)) nonlinearities, the latter including four-wave mixing. The model can be realized in chi(2) materials where an effective chi(3) nonlinearity is engineered by means of the quasi-phase-matching technique. Both self-focusing and self-defocusing chi(3) nonlinearities are considered. The birefringence of the two fundamental-frequency (FF) waves is taken into regard. Several types of solitons in this system are found, by means of the variational approximation and numerical methods. These are exact single-component solitons and generic three-wave (3W) ones, which are classified by relative signs of their components. Stability of the solitons is investigated by means of the Vakhitov-Kolokolov (VK) criterion, and then tested by direct simulations. One type of the single-component FF solitons (the "fast" one, in terms of the known two-component birefringent chi(3) model) is, chiefly, unstable, as in that model, but nevertheless a stability interval is found for it, which provides for the first example of stable fast solitons. The other FF soliton (the "slow" one, in terms of the same chi(3) model, where it is always stable) has its stability and instability regions. A single-component soliton in the second harmonic (SH) is found too; it also has its stability region, contrary to the common belief that such a soliton must always be unstable due to the parametric interaction. The 3W solitons are stable indeed if this is predicted by the VK condition, in the case when all the three components are positive. Following variation of the chi(2) mismatch parameter, the 3W soliton bifurcates from the SH one, and at another point it bifurcates back into the slow-FF single-component soliton; conjectured normal forms of the respective bifurcations are given. 3W solitons with different signs of their components may be unstable contrary to the VK criterion, which is explained by consideration of the chi(2) term in the system's Hamiltonian. In direct simulations, unstable solitons evolve into stable breathers. A different instability takes place in the case of the self-defocusing chi(3) nonlinearity, when all the solitons blow up into a turbulent state. Parallel to the solitons, continuous-wave solutions are studied too. In terms of the existence and stability, they resemble solitons of similar types.

Journal Article↗