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1.
Nature ; 576(7785): 85-90, 2019 12.
Article in English | MEDLINE | ID: mdl-31723266

ABSTRACT

Thermoelectric materials transform a thermal gradient into electricity. The efficiency of this process relies on three material-dependent parameters: the Seebeck coefficient, the electrical resistivity and the thermal conductivity, summarized in the thermoelectric figure of merit. A large figure of merit is beneficial for potential applications such as thermoelectric generators. Here we report the thermal and electronic properties of thin-film Heusler alloys based on Fe2V0.8W0.2Al prepared by magnetron sputtering. Density functional theory calculations suggest that the thin films are metastable states, and measurements of the power factor-the ratio of the Seebeck coefficient squared divided by the electrical resistivity-suggest a high intrinsic figure of merit for these thin films. This may arise from a large differential density of states at the Fermi level and a Weyl-like electron dispersion close to the Fermi level, which indicates a high mobility of charge carriers owing to linear crossing in the electronic bands.

2.
Phys Rev Lett ; 122(21): 217402, 2019 May 31.
Article in English | MEDLINE | ID: mdl-31283333

ABSTRACT

Zirconium pentatelluride was recently reported to be a 3D Dirac semimetal, with a single conical band, located at the center of the Brillouin zone. The cone's lack of protection by the lattice symmetry immediately sparked vast discussions about the size and topological or trivial nature of a possible gap opening. Here, we report on a combined optical and transport study of ZrTe_{5}, which reveals an alternative view of electronic bands in this material. We conclude that the dispersion is approximately linear only in the a-c plane, while remaining relatively flat and parabolic in the third direction (along the b axis). Therefore, the electronic states in ZrTe_{5} cannot be described using the model of 3D Dirac massless electrons, even when staying at energies well above the band gap 2Δ=6 meV found in our experiments at low temperatures.

3.
Arq. bras. med. vet. zootec. (Online) ; 70(5): 1403-1408, set.-out. 2018. ilus
Article in Portuguese | LILACS, VETINDEX | ID: biblio-946865

ABSTRACT

Relata-se um caso de pneumomediastino, pneumotórax e enfisema subcutâneo em um cão com pneumopatia associada à cinomose. As queixas principais eram tosse, secreção nasal purulenta, apatia e enfisema subcutâneo em face, região cervical e torácica. O exame radiográfico evidenciou pneumomediastino, pneumotórax e broncopneumopatia grave com áreas de consolidação pulmonar. Teste rápido imunocromatográfico para detecção de antígeno da cinomose foi positivo e houve melhora dos sinais respiratórios com antibioticoterapia, porém o quadro evoluiu para alterações neurológicas. De acordo com a revisão de literatura realizada, não há casos semelhantes relatados.(AU)


A case of pneumomediastinum, pneumothorax and subcutaneous emphysema in a dog with pneumopathy associated to distemper is reported. The main complaints were cough, purulent nasal discharge, lethargy and subcutaneous emphysema in the face, neck, and chest area. Radiographic examination showed pneumomediastinum, pneumothorax, and severe bronchopneumopathy with areas of pulmonary consolidation. Rapid test for canine distemper antigen detection was positive. After the antibiotic therapy there was an improvement of respiratory signs; however, the patient developed neurological symptomatology. As far as the author´s knowledge by literature review carried out, there are no similar cases reported.(AU)


Subject(s)
Animals , Dogs , Distemper , Lung Diseases/veterinary , Mediastinal Emphysema/veterinary , Pneumomediastinum, Diagnostic , Pneumothorax/veterinary
4.
Arq. bras. med. vet. zootec. (Online) ; 69(6): 1480-1484, nov.-dez. 2017. ilus
Article in Portuguese | LILACS, VETINDEX | ID: biblio-910167

ABSTRACT

Relata-se um caso de leishmaniose visceral canina com ceratoconjuntivite nodular como queixa exclusiva do proprietário. O diagnóstico se deu pela observação de formas amastigotas de Leishmania sp. no exame parasitológico direto de citologia aspirativa conjuntival. Lesões oculares raramente são queixas principais únicas de cães com leishmaniose, como o caso em questão, o que demonstra a variabilidade de apresentação clínica da doença e a importância da realização de testes laboratoriais diagnósticos para leishmaniose como triagem para pacientes de áreas endêmicas.(AU)


We describe a case of canine visceral leishmaniasis with nodular keratoconjunctivits as the owner's only complaint. Diagnosis was made by the observation of Leishmania sp. amastigotes in parasitological examination from conjunctival aspirative cytology. Eye lesions are rarely the only complaint of dogs suspected of leishmaniasis, as the case reported, demonstrating the variability of clinical presentation of the disease and the importance of performing screening diagnostic laboratorial tests for leishmaniasis in endemic areas.(AU)


Subject(s)
Animals , Dogs , Eye Diseases/veterinary , Eye Injuries/veterinary , Keratoconjunctivitis/veterinary , Leishmania , Leishmaniasis, Visceral/complications
6.
Phys Rev Lett ; 118(24): 246601, 2017 Jun 16.
Article in English | MEDLINE | ID: mdl-28665644

ABSTRACT

Recent theoretical studies of topologically nontrivial electronic states in Kondo insulators have pointed to the importance of spin-orbit coupling (SOC) for stabilizing these states. However, systematic experimental studies that tune the SOC parameter λ_{SOC} in Kondo insulators remain elusive. The main reason is that variations of (chemical) pressure or doping strongly influence the Kondo coupling J_{K} and the chemical potential µ-both essential parameters determining the ground state of the material-and thus possible λ_{SOC} tuning effects have remained unnoticed. Here, we present the successful growth of the substitution series Ce_{3}Bi_{4}(Pt_{1-x}Pd_{x})_{3} (0≤x≤1) of the archetypal (noncentrosymmetric) Kondo insulator Ce_{3}Bi_{4}Pt_{3}. The Pt-Pd substitution is isostructural, isoelectronic, and isosize, and it therefore is likely to leave J_{K} and µ essentially unchanged. By contrast, the large mass difference between the 5d element Pt and the 4d element Pd leads to a large difference in λ_{SOC}, which thus is the dominating tuning parameter in the series. Surprisingly, with increasing x (decreasing λ_{SOC}), we observe a Kondo insulator to semimetal transition, demonstrating an unprecedented drastic influence of the SOC. The fully substituted end compound Ce_{3}Bi_{4}Pd_{3} shows thermodynamic signatures of a recently predicted Weyl-Kondo semimetal.

7.
J Med Entomol ; 54(1): 114-124, 2017 01.
Article in English | MEDLINE | ID: mdl-28082638

ABSTRACT

Recording the nycthemeral rhythm of sand flies allows the evaluation of the daily activity in different ecotypes, the period of greatest activity, and their degree of anthropophily. We investigated the fauna and the rhythm of sand fly activity in an ecotourism region in Mato Grosso do Sul (MS) state, Brazil. Sand flies were captured monthly, using a Shannon trap for 24 h periods between July 2012 and June 2014. We collected 1,815 sand flies, in which Lutzomyia whitmani (=Nyssomyia whitmani, sensu Galati) and Lutzomyia longipalpis were the most abundant species during the dry season, with activity from 5 p.m.-7 a.m. and 6 p.m.-5 a.m., respectively. Both species require particular attention as vectors of Leishmania (Viannia) braziliensis and Leishmania (Leishmania) infantum in several regions of Brazil, including MS. However, Lutzomyia dispar was more anthropophilic, and was most active between January and March, from 5 p.m. to 5 a.m. Lutzomyia misionensis (=Pintomyia misionensis, sensu Galati) was present throughout both years, active from 4 p.m. to 5 a.m. Other species were active from 5 p.m. to 6 a.m. Due to intense tourism in the months that coincide with a high number of vectors for leishmaniases in Piraputanga, it is essential to determine vector-monitoring strategies in the area by investigating sand fly rhythm while not neglecting other periods of the year when the insects are present.


Subject(s)
Circadian Rhythm , Psychodidae/physiology , Animals , Behavior, Animal , Biodiversity , Brazil , Feeding Behavior , Female , Male , Psychodidae/classification , Seasons , Species Specificity
8.
Int J Dev Biol ; 45(5-6): 753-8, 2001 Sep.
Article in English | MEDLINE | ID: mdl-11669377

ABSTRACT

Lens regeneration occurs in some urodeles and fish throughout their adult life. Such an event is possible by the transdifferentiation of the pigment epithelial cells (PECs) from the dorsal iris. Studies of this event at the cellular level have been facilitated owing to the ability of PECs to become lens cells even when they are placed in culture, outside of the eye. In fact, PECs possess the capacity for transdifferentiation regardless of the origin of species or age. However, studies at the molecular level are still hindered by the intrinsic problems of primary cultures, namely storage, reproducibility and genetic manipulation. In an attempt to establish an ideal model system for lens transdifferentiation, we have analyzed the ability of a human dedifferentiated PEC line to differentiate into lens. We have found that this cell line can indeed be induced to synthesize crystallin and morphologically differentiate to three-dimensional structures resembling lentoids under controlled treatment in vitro. Gene expression studies also provided important insights into the role of key genes. This human cell line can be used for detailed genetic studies in order to identify the key factors involved in lens transdifferentiation from PECs.


Subject(s)
Lens, Crystalline/cytology , Pigment Epithelium of Eye/cytology , Animals , Base Sequence , Cell Differentiation , Cell Line , Cellular Senescence , Crystallins/biosynthesis , DNA Primers/genetics , Eye Proteins , Gene Expression , Homeodomain Proteins/genetics , Humans , In Situ Hybridization , Lens, Crystalline/physiology , Models, Biological , Nerve Tissue Proteins/genetics , PAX6 Transcription Factor , Paired Box Transcription Factors , Pigment Epithelium of Eye/metabolism , Receptor Protein-Tyrosine Kinases/genetics , Receptor, Fibroblast Growth Factor, Type 1 , Receptors, Fibroblast Growth Factor/genetics , Regeneration , Repressor Proteins , Homeobox Protein SIX3
9.
Invest Ophthalmol Vis Sci ; 41(5): 1122-9, 2000 Apr.
Article in English | MEDLINE | ID: mdl-10752950

ABSTRACT

PURPOSE: Lens epithelial cells transdifferentiate to myofibroblasts during the formation of anterior subcapsular cataracts and secondary cataracts. One of the defining characteristics of myofibroblasts is the expression of alpha-smooth muscle actin (alpha-SMA). This study investigated some of the factors that influence alpha-SMA expression in lens epithelial cells. METHODS: Bovine, rabbit, and human lens epithelial explants or cells were cultured with or without serum. Immunohistochemistry and immunoblotting were used to detect and quantitate alpha-SMA expression. RESULTS: Cells from all species studied expressed alpha-SMA in primary explant culture with or without serum. Immunostaining for alpha-SMA first appeared in a diffuse granular pattern, then accumulated at the cell cortex, and eventually was detected along stress fibers. When lens epithelial cells migrated onto cell-free regions of the capsule or were transferred to a plastic culture dish, alpha-SMA expression increased significantly. Expression of alpha-SMA positively correlated with cell size and cell migration. CONCLUSIONS: Expression of alpha-SMA is a common feature of cultured mammalian lens epithelial cells. Because alpha-SMA expression occurred without the addition of exogenous factors, the fibrosis seen in anterior subcapsular cataracts or secondary cataracts may reflect the intrinsic properties of lens epithelial cells. Interaction between lens epithelial cells and their substratum appears to be an important regulator of myofibroblast formation. Understanding the factors that regulate alpha-SMA expression in lens epithelial cells could lead to the development of methods for preventing secondary cataracts and anterior subcapsular cataracts.


Subject(s)
Actins/biosynthesis , Epithelial Cells/metabolism , Lens, Crystalline/metabolism , Muscle, Smooth/metabolism , Animals , Cattle , Cell Differentiation , Cell Division , Cell Size , Cells, Cultured , Fluorescent Antibody Technique, Indirect , Humans , Immunoblotting , Immunoenzyme Techniques , Lens, Crystalline/cytology , Rabbits
10.
Differentiation ; 64(3): 143-9, 1999 Mar.
Article in English | MEDLINE | ID: mdl-10234811

ABSTRACT

The spatio-temporal expression of three crystallin genes (alpha A, beta B1 and gamma) in lenses of Xenopus laevis was studied by in situ hybridization to compare the process of lens formation in embryonic development with that of lens regeneration from cornea that occurs in the tadpole. During embryonic lens development, all three crystallin transcripts were initially detected at the same stage of lens placode formation, and subsequently their signals became restricted to the presumptive lens fiber region. At later stages, the three crystallin genes were expressed in primary and secondary lens fibers, but not in lens epithelium. During lens regeneration, alpha A- and beta B1-crystallin signals were first detected in the presumptive lens fiber region of the lens vesicle. The expression of gamma-crystallin, however, appeared later than the other two crystallin genes and was detected only in morphologically discernible lens fibers. In the later stages of lens regeneration, expression of these crystallins was observed only in the lens fiber region, similar to embryonic lens development. These results reveal that lens regeneration from the inner layer of the outer cornea is not simply a repetition of embryonic lens development, when examined at the level of crystallin gene transcription.


Subject(s)
Crystallins/genetics , Lens, Crystalline/embryology , Lens, Crystalline/physiology , Regeneration/genetics , Amino Acid Sequence , Animals , Base Sequence , Embryo, Nonmammalian , Gene Expression Regulation, Developmental , In Situ Hybridization , Molecular Sequence Data , Protein Isoforms , Sequence Homology, Amino Acid , Transcription, Genetic , Xenopus laevis/embryology , Xenopus laevis/growth & development
11.
Differentiation ; 65(3): 141-9, 1999 Nov.
Article in English | MEDLINE | ID: mdl-10631811

ABSTRACT

Lens regeneration from non-lens ocular tissues has been well documented in amphibians, from the dorsal iris in the newt and from the outer cornea in Xenopus. To understand the early molecular events which govern lens regeneration, we examined the expression of two early marker genes of normal lens development, Pax-6 and Prox 1. In both Cynops (newt) iris and Xenopus cornea, Pax-6 is expressed soon after lentectomy in a region broader than that giving rise to the regenerating lens, indicative of an important role for Pax-6 in determination of the regeneration potential. Then Prox 1 expression begins within the Pax-6-expressing tissue, and these Prox 1-expressing cells give rise to the regenerating lens. This sequence of events also takes place in the lens placode of the embryo, indicating that the presence of the same genetic program operates in both embryonic lens development and lens regeneration, at least partly. In the Cynops iris, Pax-6 expression occurs initially in the entire marginal region of the iris after lentectomy but then becomes restricted to the dorsal region. Further studies are expected to elucidate the mechanism of this long-standing problem of the dorsal-restriction of lens regeneration from the newt iris.


Subject(s)
Cornea/physiology , Eye Proteins/biosynthesis , Gene Expression Regulation, Developmental , Homeodomain Proteins/biosynthesis , Iris/physiology , Lens, Crystalline/physiology , Regeneration/genetics , Salamandridae/physiology , Xenopus laevis/physiology , Amino Acid Sequence , Animals , Biomarkers , Chickens , DNA, Complementary/genetics , DNA-Binding Proteins/biosynthesis , DNA-Binding Proteins/genetics , Eye Proteins/genetics , Homeodomain Proteins/genetics , In Situ Hybridization , Larva , Lens, Crystalline/embryology , Mice , PAX6 Transcription Factor , Paired Box Transcription Factors , Repressor Proteins , Salamandridae/embryology , Salamandridae/genetics , Sequence Alignment , Sequence Homology, Amino Acid , Species Specificity , Tumor Suppressor Proteins , Xenopus laevis/embryology , Xenopus laevis/genetics , Xenopus laevis/growth & development
12.
Exp Cell Res ; 245(2): 245-51, 1998 Dec 15.
Article in English | MEDLINE | ID: mdl-9851864

ABSTRACT

Dissociated cells of the iris-pigmented epithelium (IPE) from a 1-day-old chick grew in monolayer culture and stably maintained their differentiated state when cultured with standard culture medium. After replacement of the control medium by EdFPH medium, which is effective in inducing dedifferentiation of retinal pigmented epithelium (RPE) cells, all cells rapidly lost pigment granules, proliferated intensively, and dedifferentiated. By further addition of ascorbic acid, dedifferentiated cells accumulated and formed a large number of lentoids. This system provides a useful opportunity for analyzing cellular and molecular mechanism involved in each step of transdifferentiation. Furthermore, Northern blot data indicates that the up-regulation of pax-6 gene could be an important event during lens regeneration as well as during normal lens development.


Subject(s)
Cell Culture Techniques/methods , Homeodomain Proteins , Iris/cytology , Pigment Epithelium of Eye/cytology , Animals , Ascorbic Acid/pharmacology , Biomarkers/analysis , Blotting, Northern , Cell Differentiation/drug effects , Cell Division/drug effects , Cell Size/drug effects , Cells, Cultured , Chickens , Crystallins/genetics , Crystallins/metabolism , DNA-Binding Proteins/genetics , Eye Proteins , Fibroblast Growth Factor 2/pharmacology , Gene Expression Regulation , Iris/drug effects , Iris/metabolism , Lens, Crystalline/cytology , Lens, Crystalline/physiology , Melanins/metabolism , PAX6 Transcription Factor , Paired Box Transcription Factors , Pigment Epithelium of Eye/drug effects , Pigment Epithelium of Eye/metabolism , Regeneration/drug effects , Repressor Proteins , Retina , Transcriptional Activation/drug effects
13.
Differentiation ; 63(5): 247-52, 1998 Sep.
Article in English | MEDLINE | ID: mdl-9810703

ABSTRACT

The role of the optic vesicle in lens development was reinvestigated in Cynops pyrrhogaster. To study the necessity for the optic vesicle in early lens development, the optic anlages of stage 17-27 embryos were ablated and the frequency of free lens formation was examined with lens specific markers. Free lens formation was not observed when operations were performed prior to contact between the head surface epidermis and the optic vesicle (stages 17-18). On the contrary, free lens formation occurred in all cases where the optic vesicles were removed after the initiation of lens placode formation in the head surface epidermis (stage 27). However, no lens fiber formation was observed in these free lenses as judged by the absence of lens fiber specific gene expression, namely gamma-crystallin, at stages when secondary lens fiber formation could be found in the control lenses of the unoperated sides. The pattern of expression of alpha A-crystallin in the developing free lens also differed from that of the normally developing lens. This paper is the first report to indicate that the coordinated and sequential expression of crystallin genes are influenced by the optic vesicle; the optic vesicle is required for proper regulation of the alpha A- and gamma-crystallin but not beta B1-crystallin genes.


Subject(s)
Embryonic Development , Eye/embryology , Lens, Crystalline/embryology , Salamandridae/embryology , Animals , Biomarkers , Embryo, Nonmammalian/metabolism , Eye/metabolism , Gene Expression Regulation, Developmental/physiology , Lens, Crystalline/metabolism , Salamandridae/metabolism
14.
Dev Biol ; 196(2): 145-59, 1998 Apr 15.
Article in English | MEDLINE | ID: mdl-9576828

ABSTRACT

An ectopic neural retina is formed at the outer layer of the retina in the silver homozygote (B/B) of the Japanese quail. In situ hybridization and immunohistochemical analysis revealed that cells in the outer layer of retina first expressed a pigment-cell-specific gene, mmp115, and then began to express a neural marker in B/B embryos, indicating that the ectopic neural retina is formed via transdifferentiation of differentiated pigmented epithelial cells (PECs). An in vitro study revealed that cultured retinal PECs (rPECs) from B/B embryos exhibit less pigment granule and a higher growth rate than cells from heterozygotes (B/+). B/+ PECs stopped proliferating when confluency was reached, while B/B PECs continued to proliferate. Some B/B cells overlaid other B/B cells and formed lentoid bodies. Immunological analysis revealed that B/B rPECs transdifferentiated to lens cells and neural cells in vitro with no addition of basic FGF (bFGF), while B/+ rPECs required bFGF to transdifferentiate. Expression of PEC-specific genes, mmp115, tyrosinase, and TRP-1, was downregulated, but that of Mitf and pax6 was upregulated in B/B PECs. Antibody against Mitf stained the nucleus of B/+ PECs but not that of B/B cells, suggesting that the normal Mitf is not present in the silver homozygote due to mutation. Sequence analysis revealed that Mitf from the silver homozygote has an amino acid substitution in the basic region and is truncated in the C-terminal region. Transient transfection analysis revealed that Mitf from the silver homozygote exhibits a lower level of activity than wild-type Mitf with respect to transactivation of the mmp115 promoter. Furthermore, overexpression of chicken Mitf induced normal pigmentation in B/B rPECs. These results strongly suggest that the silver phenotype is caused by the mutation of Mitf and that Mitf plays a critical role in rPEC differentiation and transdifferentiation.


Subject(s)
DNA-Binding Proteins/genetics , Mutation , Pigment Epithelium of Eye/cytology , Pigment Epithelium of Eye/embryology , Transcription Factors , Amino Acid Sequence , Animals , Avian Proteins , Base Sequence , Cell Differentiation/genetics , Cell Division , Cell Nucleus/chemistry , Cells, Cultured , Cloning, Molecular , Coturnix , DNA-Binding Proteins/analysis , Gene Expression Regulation, Developmental , Heterozygote , Homozygote , L Cells , Lens, Crystalline/cytology , Mice , Microphthalmia-Associated Transcription Factor , Molecular Sequence Data , Neurons/cytology , Pigment Epithelium of Eye/chemistry , Proteins/genetics , RNA, Messenger/analysis , Retina/embryology
15.
Dev Biol ; 193(1): 47-62, 1998 Jan 01.
Article in English | MEDLINE | ID: mdl-9466887

ABSTRACT

Mitf encodes a basic helix-loop-helix-leucine-zipper (bHLHzip) protein that is known to function in the development of melanocytes, pigmented epithelial cells (PECs), osteoclasts, and mast cells. In this paper, we report on the isolation, expression, and overexpression of the chicken Mitf and discuss the role of its protein product in the differentiation and transdifferentiation of PECs. Northern blotting showed that chicken Mitf is predominantly expressed in embryonic retinal pigmented epithelium (PE), but is expressed at low levels in other tissues. A 5' RACE analysis revealed differences in the 5' region Mitf nRNA in PE and other tissues. Immunological analysis revealed that Mitf, the protein encoded by Mitf, is first detected in the nuclei of the optic vesicle cells at embryonic stage 13 in a restricted region covered with mesenchymal cells. From stage 14 to 24, the specific staining is observable in the PE and precursor of the PE, the outer layer of the optic cup. In embryos at stages later than stage 29 the signals for Mitf in the future iris, ciliary body, and posterior retinal regions become faint. These results show that expression of Mitf starts at the optic vesicle stage at which no other marker genes for PECs such as mmp115 and tyrosinase are expressed. Dedifferentiation of cultured retinal PECs (rPECs) was induced by phenylthiourea and testicular hyaluronidase, bFGF, or TGF-beta. Mitf expression was inhibited by these factors and reactivated during redifferentiation of the dedifferentiated cells into rPECs, showing the correlation between Mitf expression and rPEC differentiation. Retrovirus-mediated overexpression of Mtif inhibited bFGF-induced dedifferentiation and transdifferentiation of rPECs to both lens and neural cells. These findings showed that downregulation of Mitf expression is essential for the transdifferentiation of rPEC. Mitf overexpression caused hyperpigmentation in cultured rPECs and suppressed the changes in gene expression induced by bFGF. Mitf overexpression promoted expression of mmp115 and tyrosinase in bFGF-treated rPECs suggesting a critical role for Mitf in rPEC differentiation. Mitf overexpression, however, did not promote expression of another rPEC-specific gene, pP344, in bFGF-treated rPECs. This result suggests the presence of other regulatory genes promoting rPEC differentiation. The expression patterns of pax6 and Mitf are complementary both in vivo in vitro. Overexpression of Mitf inhibited expression of pax6 in cultured rPECs. These observations suggest that Mitf regulates pax6 expression negatively.


Subject(s)
DNA-Binding Proteins/genetics , DNA-Binding Proteins/physiology , Pigment Epithelium of Eye/cytology , Pigment Epithelium of Eye/embryology , Transcription Factors , Amino Acid Sequence , Animals , Base Sequence , Cell Differentiation , Cell Nucleus/chemistry , Cell Size , Cells, Cultured , Chick Embryo , Cloning, Molecular , DNA, Complementary/analysis , DNA-Binding Proteins/analysis , Eye/embryology , Fibroblast Growth Factor 2/pharmacology , Gene Expression Regulation, Developmental , Genetic Vectors , Microphthalmia-Associated Transcription Factor , Molecular Sequence Data , Organ Specificity , Pigment Epithelium of Eye/chemistry , RNA, Messenger/analysis , Retroviridae/genetics , Sequence Analysis, DNA , Sequence Homology, Amino Acid
16.
J Cataract Refract Surg ; 23(8): 1254-9, 1997 Oct.
Article in English | MEDLINE | ID: mdl-9368173

ABSTRACT

PURPOSE: To evaluate the mechanical relationship between the intraocular lens (IOL) haptic and the capsular bag by quantitatively analyzing the fit of the haptic with the capsule equator and the capsular bag deformity induced by the implanted lens haptics. SETTING: Division of Morphogenesis, Department of Developmental Biology, National Institute for Basic Biology, Okazaki, Japan. METHODS: Following implantation of a poly(methyl methacrylate)(PMMA) ring in three excised human capsular bags with continuous curvilinear capsulorhexis (CCC), IOLs with different overall lengths or haptic designs were implanted in the bags and photographed. The straight length of the area of contact between the haptic and the capsule equator on the photographs was measured to provide a quantitative index of in-the-bag fixation and the length from the external margin of the PMMA ring to the external margin of the loop along the maximal diameter of the capsular bag, to indicate the quantitative degree of capsular deformity induced by an IOL. RESULTS: An IOL with modified-C loops produced better fit along the capsule equator and less deformity than an IOL with modified-J loops, and an IOL with an overall length of 12.0 or 12.5 mm produced a sufficiently good fit and less distortion of the capsular bag than an IOL with an overall length over 13.0 mm. CONCLUSION: An IOL with modified-C loops and an overall length of 12.0 or 12.5 mm is adequate for in-the-bag implantation following CCC.


Subject(s)
Biocompatible Materials , Lens Capsule, Crystalline/pathology , Lens Implantation, Intraocular , Lenses, Intraocular , Adult , Humans , Lens Capsule, Crystalline/surgery , Middle Aged , Polymethyl Methacrylate , Prosthesis Design
17.
J Cataract Refract Surg ; 23(6): 866-72, 1997.
Article in English | MEDLINE | ID: mdl-9292670

ABSTRACT

PURPOSE: To find the conditions that prevent posterior capsule opacification through in vitro analysis of the relationship between intraocular lens (IOL) optic configuration and lens epithelial cell (LEC) migration. SETTING: Division of Morphogenesis, Department of Developmental Biology, National Institute for Basic Biology, Okazaki, Japan. METHODS: In a preliminary experiment, we measured the size of the capsular bag of rabbits at 8, 16, 20, and 26 weeks of age. The size of a 20-week-old capsular bag was the same size as the capsular bag in senescent Japanese eyes. We isolated the capsular bags in 20- and 8-week-old rabbits. The bags along with a biconvex (BC), convex-plano (CP), or no IOL (C) were cultured, and the eyes were divided into one of six groups (8W-C, 8W-BC, 8W-CP, 20W-C, 20W-BC and 20W-CP), each including six specimens. RESULTS: Two specimens in the 8W-CP group completely blocked LEC migration at the optic edge. All specimens in the 20W-CP group and one in the 20W-BC group showed cell aggregation along the optic edge. None of the other specimens in the BC and C groups blocked migration or showed cell aggregation. CONCLUSIONS: In the rabbit-model study, the convex-plano lens was superior to the biconvex lens in inhibiting migration of LECs. A firm contact between the IOL and the posterior capsule blocked the migration.


Subject(s)
Cell Movement , Lens Capsule, Crystalline/pathology , Lens, Crystalline/pathology , Lenses, Intraocular , Animals , Cataract/pathology , Cataract/prevention & control , Cell Aggregation , Cells, Cultured , Epithelium/pathology , Microscopy, Phase-Contrast , Prosthesis Design , Rabbits
18.
Neuroreport ; 8(4): 925-7, 1997 Mar 03.
Article in English | MEDLINE | ID: mdl-9141066

ABSTRACT

We used digoxigenin-labelled single strand DNA probes to examine the expression of the mRNA encoding gamma-aminobutyric acid receptor rho 3 subunit in sections of the adult rat retina. Transcript for the rho 3 subunit was found in cell somata of a portion of cells lying in the ganglion cell layer.


Subject(s)
Receptors, GABA/biosynthesis , Retina/metabolism , Retinal Ganglion Cells/metabolism , Transcription, Genetic , Animals , DNA Probes , Digoxigenin , In Situ Hybridization , RNA, Messenger/biosynthesis , Rats , Rats, Sprague-Dawley , Receptors, GABA/analysis , Retina/cytology , Retinal Ganglion Cells/cytology , Retinal Rod Photoreceptor Cells/cytology , Retinal Rod Photoreceptor Cells/metabolism
19.
Dev Biol ; 192(2): 211-27, 1997 Dec 15.
Article in English | MEDLINE | ID: mdl-9441663

ABSTRACT

F-spondin is a secreted protein expressed at high levels by the floor plate cells. The C-terminal half of the protein contains six thrombospondin type 1 repeats, while the N-terminal half exhibited virtually no similarity to any other protein until recently, when a Drosophila gene termed M-spondin was cloned; its product was found to share two conserved domains with the N-terminal half of F-spondin. We report the molecular cloning of four zebrafish genes encoding secreted proteins with these conserved domains. Two are zebrafish homologs of F-spondin, while the other two, termed mindin1 and mindin2, encode mutually related novel proteins, which are more related to the Drosophila M-spondin than to F-spondin. During embryonic development, all four genes are expressed in the floor plate cells. In addition to the floor plate, mindin1 is expressed in the hypochord cells, while mindin2 is expressed in the sclerotome cells. When ectopically expressed, Mindin proteins selectively accumulate in the basal lamina, suggesting that Mindins are extracellular matrix (ECM) proteins with high affinity to the basal lamina. We also report the spatial distribution of one of the F-spondin proteins, F-spondin2. F-spondin2 is localized to the thread-like structure in the central canal of the spinal cord, which is likely to correspond to Reissner's fiber known to be present in the vertebrate phylum. In summary, our study has defined a novel gene family of ECM molecules in the vertebrate, all of which may potentially be involved in development of the midline structure.


Subject(s)
Extracellular Matrix Proteins/physiology , Gene Expression Regulation, Developmental , Growth Substances , Neural Cell Adhesion Molecules/physiology , Peptides , Zebrafish Proteins , Zebrafish/embryology , Amino Acid Sequence , Animals , Consensus Sequence , Drosophila Proteins , Drosophila melanogaster/embryology , Drosophila melanogaster/genetics , Embryo, Nonmammalian/physiology , Extracellular Matrix Proteins/biosynthesis , Extracellular Matrix Proteins/genetics , Membrane Proteins , Molecular Sequence Data , Multigene Family , Sequence Alignment , Sequence Homology, Amino Acid
20.
Dev Biol ; 192(2): 289-99, 1997 Dec 15.
Article in English | MEDLINE | ID: mdl-9441668

ABSTRACT

Despite a number of reports on transgenic zebrafish, there have been no reports on transgenic zebrafish in which the gene is under the control of a promoter of zebrafish origin. Neither have there been reports on transgenic zebrafish in which the gene is under the control of a tissue-specific promoter/enhancer. To investigate whether it is possible to generate transgenic zebrafish which reliably express a reporter gene in specific tissues, we have isolated a zebrafish muscle-specific actin (alpha-actin) promoter and generated transgenic zebrafish in which the green fluorescent protein (GFP) reporter gene was driven by this promoter. In total, 41 GFP-expressing transgenic lines were generated with a frequency of as high as 21% (41 of 194), and GFP was specifically expressed throughout muscle cells in virtually all of the lines (40 of 41). Nonexpressing transgenic lines were rare. This demonstrates that a tissue-specific promoter can reliably drive reporter gene expression in transgenic zebrafish in a manner identical to the control of the endogeneous expression of the gene. Levels of GFP expression varied greatly from line to line; i.e., fluorescence was very weak in some lines, while it was extremely high in others. We also isolated a zebrafish cytoskeletal beta-actin promoter and generated transgenic zebrafish using a beta-actin-GFP construct. In all of the four lines generated, GFP was expressed throughout the body like the beta-actin gene, demonstrating that consistent expression could also be achieved in this case. In the present study, we also examined the effects of factors which potentially affect the transgenic frequency or expression levels. The following results were obtained: (i) expression levels of GFP in the injected embryo were not strongly correlated to transgenic frequency; (ii) the effect of the NLS peptide (SV40 T antigen nuclear localization sequence), which has been suggested to facilitate the transfer of a transgene into embryonic nuclei, remained to be elusive; (iii) a plasmid vector sequence placed upstream of the construct might reduce the expression levels of the reporter gene.


Subject(s)
Actins/genetics , Gene Expression Regulation, Developmental , Muscle, Skeletal/embryology , Promoter Regions, Genetic/genetics , Zebrafish/genetics , Actins/biosynthesis , Animals , Animals, Genetically Modified , Antigens, Polyomavirus Transforming/genetics , Cloning, Molecular , Embryo, Nonmammalian/metabolism , Genes, Reporter , Green Fluorescent Proteins , Luminescent Proteins/biosynthesis , Luminescent Proteins/genetics , Muscle, Skeletal/metabolism , Organ Specificity , Recombinant Fusion Proteins/biosynthesis , Simian virus 40/genetics , Transgenes , Zebrafish/embryology
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