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1.
Phys Rev Lett ; 105(17): 176401, 2010 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-21231061

RESUMO

We discovered the chirality of charge-density waves (CDW) in 1T-TiSe2 by using STM and time-domain optical polarimetry. We found that the CDW intensity becomes Ia1∶Ia2∶Ia3 = 1∶0.7 ± 0.1∶0.5 ± 0.1, where Ia(i) (i=1,2,3) is the amplitude of the tunneling current contributed by the CDWs. There were two states, in which the three intensity peaks of the CDW decrease clockwise and anticlockwise. The chirality in CDW results in the threefold symmetry breaking. Macroscopically, twofold symmetry was indeed observed in optical measurement. We propose the new generalized CDW chirality H(CDW) ≡ q1·(q2×q3), where q(i) are the CDW q vectors, which is independent of the symmetry of components. The nonzero H(CDW)-the triple-q vectors do not exist in an identical plane in the reciprocal space-should induce a real-space chirality in CDW system.

2.
J Phys Condens Matter ; 32(16): 165803, 2020 Apr 17.
Artigo em Inglês | MEDLINE | ID: mdl-31842001

RESUMO

We report the coexistence of the Kondo effect and spin glass behavior in Fe-doped NbS2 single crystals. The Fe x NbS2 shows the resistance minimum and negative magnetoresistance due to the Kondo effect, and exhibits no superconducting behavior at low temperatures. The resistance curve follows a numerical renormalization-group theory using the Kondo temperature [Formula: see text] K for x = 0.01 as evidence of Kondo effect. Scanning tunneling microscope/spectroscopy (STM/STS) revealed the presence of Fe atoms near sulfur atoms and asymmetric spectra. The magnetic susceptibility exhibits a feature of spin glass. The static critical exponents determined by the universal scaling of the nonlinear part of the susceptibility suggest a three-dimensional Heisenberg spin glass. The doped-Fe atoms in the intra- and inter-layers revealed by the x-ray result can realize the coexistence of the Kondo effect and spin glass.

3.
Curr Biol ; 8(23): 1277-80, 1998 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-9822580

RESUMO

The maternal transcript of the anterior segmentation gene bicoid (bcd) is localized at the anterior pole of the Drosophila egg and translated to form a gradient in the nuclei of the syncytial blastoderm embryo after fertilization [1-3]. The nuclear gradient of Bcd protein - a transcription factor - leads to differential expression of zygotic segmentation genes. The rapid nuclear division during this stage [4] requires that Bcd quickly enters the nuclei after each mitosis using an active nuclear import system. Nuclear transport depends on the asymmetrical distribution of two forms of the small GTPase Ran: Ran-GTP is concentrated in the nucleus and Ran-GDP in the cytoplasm [5-8]. Ran requires RanGTPase-activating protein-1 (RanGAP1) on the cytoplasmic side of nuclear pore complexes to convert Ran-GTP to Ran-GDP. In vitro studies with vertebrate proteins demonstrate that the RanGAP1 associated with the nuclear pore complex is modified with small ubiquitin related modifier-1 (SUMO-1) by a ubiquitin-conjugating enzyme (E2 enzyme) [9-15]. Here, we show that mutation of the Drosophila semushi (semi) gene, which encodes an E2 enzyme, blocks nuclear import of Bcd during early embryogenesis and results in misregulation of the segmentation genes that are Bcd targets. Consequently, semi embryos have multiple defects in anterior segmentation. This study demonstrates that an E2 enzyme is required for nuclear transport during Drosophila embryogenesis.


Assuntos
Núcleo Celular/metabolismo , Drosophila/genética , Proteínas de Homeodomínio/metabolismo , Ligases/metabolismo , Mutação , Transativadores/metabolismo , Enzimas de Conjugação de Ubiquitina , Animais , Transporte Biológico , Drosophila/embriologia , Proteínas de Drosophila , Proteínas de Insetos/metabolismo , Ligases/genética
4.
Mol Cell Biol ; 14(8): 5392-401, 1994 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-8035817

RESUMO

The tom transposable element of Drosophila ananassae is mobilized with high frequency in the germ line of females from the ca; px strain, and its insertion results in mutations that show almost exclusively dominant eye phenotypes. tom is a long terminal repeat-containing retrotransposon that encodes three different open reading frames (ORFs). It is expressed in the nurse cells during oogenesis, in the central and peripheral nervous systems during embryonic development, and in the imaginal discs of the larva. tom RNA accumulates in the germarium of ovaries from ca; px females but not in the parental inactive strain, suggesting that this altered pattern of tom expression might be the cause of the high rate of mobilization of this retrotransposon. The specificity of tom-induced eye phenotypes can be explained by the presence of regulatory sequences responsible for expression of tom in the eye imaginal discs of third-instar larvae. These sequences might cause overexpression of adjacent genes affected by tom-induced mutations, resulting in the death of undifferentiated cells located anterior to the morphogenetic furrow. In addition to the full-length RNA, tom is also transcribed into a spliced subgenomic transcript that encodes a protein resulting from the fusion between the amino-terminal region of the first (gag) and the third ORFs. The protein encoded by this RNA shows structural characteristics such as a signal peptide, glycosylation sites, endopeptidase cleavage site, and fusion peptide that are typical of the envelope proteins of retroviruses. Antibodies against tom ORF3 recognize two different proteins present in female ovaries, suggesting that tom might be able to form infective viral particles that could play a role in the horizontal transmission of this retrotransposon.


Assuntos
Elementos de DNA Transponíveis , Drosophila melanogaster/genética , Regulação da Expressão Gênica , Genes env , Sequência de Aminoácidos , Animais , Sequência de Bases , Drosophila melanogaster/crescimento & desenvolvimento , Feminino , Genes de Insetos , Hibridização In Situ , Dados de Sequência Molecular , Morfogênese , Oogênese , Fases de Leitura Aberta , Mapeamento por Restrição , Distribuição Tecidual , Proteínas do Envelope Viral/genética
5.
Clin Nephrol ; 67(3): 182-7, 2007 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-17390743

RESUMO

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a hereditary systemic arteriopathy presenting with migraines, mood disorders, focal neurologic deficits, recurrent ischemic attacks and dementia in young adults. The genesis of this disease relates to missense mutation of the Notch3 gene. We report here a newly identified CADASIL patient and discuss unique vascular lesions observed in the kidney. A 64-year-old female was admitted to our hospital for the investigation of proteinuria, hematuria and progressive neurological abnormalities. Her mother and brother died of cerebral infarction at a relatively young age despite a lack of apparent risk factors for arteriosclerosis. Over the past 4 months before admission, she had suffered from frequent transient ischemic attacks despite appropriate antiplatelet therapy. Blood examination revealed mild renal insufficiency and urinalysis revealed moderate protein excretion and dysmorphic hematuria. Magnetic resonance imaging of the brain revealed multiple infarcts and leukoencephalopathy. Histopathological analysis of the kidney revealed focal segmental mesangial proliferation, the loss and degeneration of arterial medial smooth muscle cells and arterial intimal thickening. Immunofluorescence analysis of glomeruli revealed IgA deposition in the mesangial area. Electron microscope analysis revealed electron-dense deposition also in the mesangial area. In addition, granular osmophilic material (GOM) was observed in the extraglomerular mesangial area and around the vascular smooth muscle cells. Genetic analysis of Notch3 revealed an R141C missense mutation and she was diagnosed with CADASIL complicated with IgA nephropathy. In immunohistological analysis, Notch3 stains were positive in vascular smooth muscle cells of the interlobular arteries and both afferent and efferent arterioles, and weak in the glomerular mesangial area. Antihypertensive treatment using angiotensin II receptor blocker and a low protein diet were initiated, and her urinary protein excretion decreased to 0.2 g/day. However, due to the progression of her neurological abnormalities, she became socially withdrawn. In CADASIL, GOM, abnormal accumulation of Notch3 ectodomain, is thought to induce the degeneration and loss of vascular smooth muscle cells and subsequent intimal thickening. Analysis of our cases provided that these morphological abnormalities were also observed in the CADASIL patient kidney.


Assuntos
CADASIL/complicações , Angiopatia Amiloide Cerebral Familiar/complicações , Glomerulonefrite por IGA/etiologia , Antagonistas de Receptores de Angiotensina , Anti-Hipertensivos , Biópsia , CADASIL/diagnóstico , CADASIL/genética , Angiopatia Amiloide Cerebral Familiar/diagnóstico , Angiopatia Amiloide Cerebral Familiar/genética , Progressão da Doença , Feminino , Seguimentos , Glomerulonefrite por IGA/tratamento farmacológico , Glomerulonefrite por IGA/patologia , Humanos , Imuno-Histoquímica , Imageamento por Ressonância Magnética , Células Mesangiais/ultraestrutura , Microscopia Eletrônica , Pessoa de Meia-Idade , Mutação de Sentido Incorreto , Receptor Notch3 , Receptores Notch/genética , Pele/ultraestrutura
6.
Circ Res ; 89(8): 723-31, 2001 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-11597996

RESUMO

To investigate mechanisms of vascular morphogenesis in tissue repair, we performed ovariectomy with resection of the corresponding branches of the ovarian vessels in nude mice. This induces a vascular network remodeling response in the healing ovarian pedicle. Reconstruction of 2000 histological serial sections demonstrated that a new vascular network composed of venous-venous loops forms in the wall of the dilated ovarian vein. Preexisting veins of all sizes, including a branch of the main artery, are subjected to segmentation. Loop formation and segmentation are based on intussusceptive microvascular growth. Loop formation is followed by elongation. Loop remodeling occurs also by intussusception and results in the formation of compound loop systems. All loop systems observed were completely patent. Blind-ending sprouts were extremely rare. Anastomoses between the preexisting vessels subjected to segmentation and the loop systems were established to include the newly formed vessels into the preexisting vascular network. The formation of an increasing number of patent loop systems likely decreases hypoxia and subsequently arrests angiogenesis with transformation of the granulation tissue into a scar. Loop formation also occurred inside a large thrombus that occluded a part of the lumen of the main vein.


Assuntos
Vasos Sanguíneos/crescimento & desenvolvimento , Microcirculação/crescimento & desenvolvimento , Neovascularização Fisiológica/fisiologia , Ovário/irrigação sanguínea , Cicatrização/fisiologia , Animais , Vasos Sanguíneos/citologia , Feminino , Processamento de Imagem Assistida por Computador , Camundongos , Camundongos Nus , Microcirculação/citologia , Modelos Biológicos , Ovariectomia , Ovário/citologia , Ovário/cirurgia , Fatores de Tempo
7.
Circ Res ; 89(8): 732-9, 2001 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-11597997

RESUMO

To determine mechanisms of blood vessel formation and growth in solid tumors, we used a model in which LS174T human colon adenocarcinomas are grown in the isolated ovarian pedicle of nude mice. Reconstruction of 3500 histological serial sections demonstrated that a new vascular network composed of venous-venous loops of varying sizes grows inside the tumor from the wall of the adjacent main vein. Loops elongate and remodel to establish complex loop systems. The mechanisms of loop formation and remodeling correspond to intussusceptive microvascular growth (IMG). In the tissue surrounding the tumor segmentation, another mechanism of IMG is prevalent in venous vessels. Comparison to vascular morphogenesis in the ovariectomized pedicle not only confirms the existence of corresponding mechanisms in both systems, but also reveals numerous sprouts that are superimposed onto loop systems and pathological deviations of loop formation, remodeling, and segmentation in the tumor. These pathological mechanisms interfere with vessel patency that likely cause heterogenous perfusion and hypoxia thus perpetuating angiogenesis. Blood vessel formation based on IMG was also detected in a large thrombus that completely occluded a part of an ovarian artery branch.


Assuntos
Adenocarcinoma/irrigação sanguínea , Vasos Sanguíneos/crescimento & desenvolvimento , Neoplasias do Colo/irrigação sanguínea , Neovascularização Patológica , Adenocarcinoma/patologia , Animais , Vasos Sanguíneos/patologia , Neoplasias do Colo/patologia , Feminino , Humanos , Camundongos , Camundongos Nus , Transplante de Neoplasias , Neovascularização Patológica/patologia , Ovariectomia , Ovário/irrigação sanguínea , Ovário/patologia , Trombose/patologia , Fatores de Tempo , Transplante Heterólogo , Veias/crescimento & desenvolvimento , Veias/patologia
8.
Clin Nephrol ; 65(3): 222-6, 2006 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-16550755

RESUMO

A 48-year-old man was admitted to our hospital for investigation of mild renal dysfunction. A blood examination revealed mild elevation of creatinine level (1.77 mg/dl). Urinary examination revealed mild protein excretion (0.54 g/day) and microhematuria; renal biopsy revealed the focal proliferation of large mononuclear cells with mitosis in glomerular capillaries. According to immunohistochemical analysis, the intravascular lymphomatous cells stained positively with anti-leukocyte common antigen (LCA: CD45) and CD20, indicating a B lymphocyte lineage. In electron microscopy, the glomerular capillary was filled with lymphoma cells and epithelial foot process fusion was noted. Immunohistochemical analysis on adhesive molecules revealed a lack of CD11a expression on lymphoma cells, but positive CD54 expression on endothelial cells. Systemic 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) revealed no abnormal uptake of isotopes. On the basis of these findings, we diagnosed intravascular diffuse large B cell lymphoma localized in the kidney. Despite treatment with rituximab and CHOP (prednisolone, doxorubicin, vincristine, cyclophosphamide) for 3 cycles at 1-month intervals, the renal dysfunction did not change. In histopathological analysis of the second biopsy, lymphoma cells disappeared, but focal segmental glomerulosclerosis and moderate interstitial fibrosis were noted. Electron microscopic findings revealed severe subendothelial edema with mesangial interposition, indicating severe endothelial damage. Epithelial foot process fusion was improved. These pathological analyses let us conclude that a lack of CD11a could be a candidate factor for prevention of the extravasation of lymphoma cells from blood vessels in our patient. We also presumed that the intraglomerular endothelial damage occurred due to chemotherapy-associated cell injury.


Assuntos
Anticorpos Monoclonais/uso terapêutico , Antineoplásicos/uso terapêutico , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Moléculas de Adesão Celular/metabolismo , Mesângio Glomerular/ultraestrutura , Neoplasias Renais/patologia , Linfoma de Células B/patologia , Anticorpos Monoclonais Murinos , Biópsia , Ciclofosfamida/uso terapêutico , Diagnóstico Diferencial , Doxorrubicina/uso terapêutico , Mesângio Glomerular/metabolismo , Humanos , Imuno-Histoquímica , Neoplasias Renais/tratamento farmacológico , Neoplasias Renais/metabolismo , Linfoma de Células B/tratamento farmacológico , Linfoma de Células B/metabolismo , Masculino , Microscopia Eletrônica , Pessoa de Meia-Idade , Prednisona/uso terapêutico , Rituximab , Vincristina/uso terapêutico
9.
Cancer Res ; 53(22): 5528-34, 1993 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-8221694

RESUMO

To elucidate the microvascular mechanisms of change in tumor blood flow elicited by vasopressors, a functional morphometric study of the s.c. microcirculation within a rat transparent chamber was performed. Arteriolar vessels were classified centripetally (a2-a5) according to Strahler's method. Arteriolar pressure in each segment both under normotension and under hypertension induced by angiotensin II, epinephrine, or methoxamine was measured using a microocclusion technique. Vasoconstriction was estimated by changes in vessel diameters. In addition, tissue blood flow of the subcutis and s.c. tumor (LY80, a variant of Yoshida sarcoma) under the same conditions was measured with the hydrogen clearance method. By comparing the sites of the greatest pressure drop and the vasoconstriction induced by each vasopressor, we assessed the sites of vascular resistance (VR) which showed increases due to these vasopressors. The greatest VR increase elicited by angiotensin II occurred across a2 vessels. On the other hand, the sites of VR increase due to epinephrine were in a3 vessels and larger vessels upstream from a3 arterioles. The VR increase induced by methoxamine was much smaller than that induced by epinephrine. We conclude that the fact that the sites of increased VR differ with each vasopressor is the primary reason that various vasopressors have been found to produce different changes in tumor blood flow.


Assuntos
Angiotensina II/farmacologia , Epinefrina/farmacologia , Metoxamina/farmacologia , Pele/irrigação sanguínea , Animais , Arteríolas/efeitos dos fármacos , Arteríolas/fisiologia , Pressão Sanguínea/efeitos dos fármacos , Capilares/efeitos dos fármacos , Capilares/fisiologia , Cultura em Câmaras de Difusão , Hipertensão/induzido quimicamente , Hipertensão/fisiopatologia , Masculino , Microcirculação/efeitos dos fármacos , Microcirculação/fisiologia , Ratos , Fluxo Sanguíneo Regional/efeitos dos fármacos
10.
Cancer Res ; 52(4): 912-6, 1992 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-1737354

RESUMO

Circadian fluctuation in tumor blood flow of the rat subcutaneous tumor was investigated. Tumor tissue blood flows in the daytime zone (10 a.m. to 4 p.m.) and in the nighttime zone (10 p.m. to 4 a.m.) in both the first phase (doubling time of tumor volume = 1.7 days) and the second phase (doubling time of tumor volume = 5.7 days) of growth of the LY80 tumor in rats were measured using the hydrogen gas clearance technique. In the first phase of tumor growth, the tumor blood flow was 20.3 +/- 12.2 ml/min/100 g in the daytime zone (n = 22) and 46.6 +/- 19.3 ml/min/100 g in the nighttime zone (n = 22). In the second phase, tumor blood flow was 9.6 +/- 5.7 ml/min/100 g in the daytime zone (n = 45) and 19.4 +/- 8.2 ml/min/100 g in the nighttime zone (n = 38). Tumor blood flow in the nighttime zone was significantly higher than that in the daytime zone (first phase, P less than 0.001; second phase, P less than 0.001). However, there were no significant differences in the mean arterial blood pressure, tumor size, and body weight of rats between the daytime zone and the nighttime zone. There was also a marked difference in the effect of angiotensin II-induced hypertension on tumor blood flow between the daytime zone and the nighttime zone. These results suggest that circadian fluctuations in tumor blood flow should be carefully considered when developing strategies to maximize the effectiveness of cancer therapy in relation to the flow rate of circulating blood.


Assuntos
Ritmo Circadiano , Hipertensão/fisiopatologia , Sarcoma Experimental/irrigação sanguínea , Angiotensina II/farmacologia , Animais , Pressão Sanguínea/efeitos dos fármacos , Divisão Celular , Ritmo Circadiano/efeitos dos fármacos , Hipertensão/induzido quimicamente , Masculino , Ratos , Ratos Endogâmicos , Fluxo Sanguíneo Regional/efeitos dos fármacos , Sarcoma Experimental/patologia , Sarcoma Experimental/fisiopatologia
11.
Genetics ; 151(2): 667-74, 1999 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-9927459

RESUMO

Phylogenetic analysis identified a highly conserved eight-base sequence (AAGGCTGA) within the 3'-untranslated region (UTR) of the Drosophila alcohol dehydrogenase gene, Adh. To examine the functional significance of this conserved motif, we performed in vitro deletion mutagenesis on the D. melanogaster Adh gene followed by P-element-mediated germline transformation. Deletion of all or part of the eight-base sequence leads to a twofold increase in in vivo ADH enzymatic activity. The increase in activity is temporally and spatially general and is the result of an underlying increase in Adh transcript. These results indicate that the conserved 3'-UTR motif plays a functional role in the negative regulation of Adh gene expression. The evolutionary significance of our results may be understood in the context of the amino acid change that produces the ADH-F allele and also leads to a twofold increase in ADH activity. While there is compelling evidence that the amino acid replacement has been a target of positive selection, the conservation of the 3'-UTR sequence suggests that it is under strong purifying selection. The selective difference between these two sequence changes, which have similar effects on ADH activity, may be explained by different metabolic costs associated with the increase in activity.


Assuntos
Álcool Desidrogenase/genética , Sequência Conservada , Drosophila melanogaster/genética , Regulação da Expressão Gênica , Genes de Insetos , Animais
12.
Genetics ; 145(4): 1041-52, 1997 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-9093856

RESUMO

Here we describe a new segment polarity gene of Drosophila melanogaster, oroshigane (oro). Identified as a dominant enhancer of Bar (B), oro is also recessive embryonic lethal, and homozygous oro embryos show variable substitution of naked cuticle with denticles. These patterns are distinctly similar to those of hedgehog (hh) and wingless (wg) embryos, which indicates that oro functions in determining embryonic segment polarity. Evidence that oro function is involved in Hh signal transduction during embryogenesis is provided by its genetic interactions with the segment polarity genes patched (ptc) and fused (fu). Furthermore, ptcIN is a dominant suppressor of the oro embryonic lethal phenotype, suggesting a close and dose-dependent relationship between oro and ptc in Hh signal transduction. oro function is also required in imaginal development. The oroI allele significantly reduces decapentaplegic (dpp), but not hh, expression in the eye imaginal disc. Furthermore, oro enhances the fui wing phenotype in a dominant manner. Based upon the interactions of oro with hh, ptc, and fu, we propose that the oro gene plays important roles in Hh signal transduction.


Assuntos
Proteínas de Drosophila , Drosophila melanogaster/genética , Regulação da Expressão Gênica no Desenvolvimento , Genes de Insetos , Genes Reguladores , Proteínas de Insetos/genética , Fatores de Transcrição , Animais , Drosophila melanogaster/embriologia , Embrião não Mamífero/ultraestrutura , Desenvolvimento Embrionário , Epistasia Genética , Olho/embriologia , Olho/ultraestrutura , Proteínas do Olho/biossíntese , Proteínas do Olho/genética , Feminino , Genes Letais , Genes Supressores , Proteínas Hedgehog , Proteínas de Homeodomínio , Proteínas de Insetos/fisiologia , Masculino , Proteínas de Membrana/fisiologia , Morfogênese , Fenótipo , Proteínas Serina-Treonina Quinases/fisiologia , Receptores de Superfície Celular , Transdução de Sinais/fisiologia , Asas de Animais/embriologia , Asas de Animais/ultraestrutura
13.
Genetics ; 123(3): 495-502, 1989 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-2557262

RESUMO

From the ca;px stock, which is the progenitor of Om mutants caused by insertions of the tom retrotransposon, 50 kb of genomic DNA including the Om(1D) locus was cloned by tom tagging and chromosome walking. Southern blot analyses of six Om(1D) mutants exposed one or two tom elements inserted at five nonrandom sites within an 18-kb distal segment of the restriction map; the phenotypic uniformity between these mutants was not affected by variations in the position, number or orientation of their inserts. Spontaneous revertants or more extreme derivatives of Om(1D) alleles were nonlinearly associated with losses or gains of tom inserts. Seven of eight radiation induced derivatives of Om(1D) mutants had one breakpoint of a chromosome rearrangement in polytene section 13A which includes the Om(1D) locus. Two Om(1D) derivatives, a spontaneous revertant and an induced extreme allele, were associated with overlapping deficiencies which define a region that is likely to contain the Om(1D) coding seguences proximal to the tom insertion sites. Incidental results confirm the previously indicated homology of the Om(1D) locus with the Bar locus of Drosophila melanogaster.


Assuntos
Elementos de DNA Transponíveis , Drosophila/genética , Olho/anatomia & histologia , Animais , Mapeamento Cromossômico , Rearranjo Gênico/genética , Microscopia Eletrônica de Varredura , Mutação , Fenótipo , Mapeamento por Restrição
14.
Int J Oncol ; 2(2): 289-96, 1993 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-21573553

RESUMO

This review summarizes our recent experiments on the process of tumor vascularization and character of tumor vessels. By vitalscopic observation with transparent chambers in rats, we found that the sites where tumor vessels originated were usually terminal portions of terminal arterioles and that an intricate tumor vascular network was constructed from incorporated preexisting vessels and newly formed vessels by three different modes, i.e., sprouting, cross-connecting and splitting. Observation and hydrogen clearance studies showed that tumor blood flow changed remarkably during the development of the tumor vascular network. At an early stage of tumor growth, there were some regions of high flow in the tumor. At an advanced stage, however, there was a rapid increase in low-flow or no-flow areas which were resistant to access of anticancer drugs and oxygen. Angiotensin II-induced hypertension produced a several-fold increase in tumor blood flow without increasing tissue blood flow of normal tissues. These good conditions for drug delivery to tumor tissue are able to enhance therapeutic effects of chemotherapy, irradiation, antibody and photodynamic therapy.

15.
Int J Oncol ; 9(5): 955-62, 1996 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-21541601

RESUMO

The purpose of this study was to assess the usefulness of the Eppendorf 'Kistograph' as a device for measuring pO(2) in tumor and normal tissues of the laboratory mouse. To determine the appropriate calibration and electrode condition, nitrogen bubbling time was changed, and the current during calibration was recorded. Reproducibility of pO(2) measurements was tested in the series of human xenografts and murine isoplants at different time points or in the same tumor in successive determinations. pO(2) values obtained with the Eppendorf 'Histograph' were compared to those obtained with a manually controlled needle-type electrode manufactured by the Diamond-General Company. The pO(2) values after 9 min of nitrogen bubbling were closer to the expected values than those after 3 min bubbling. The current during nitrogen bubbling in calibration declined following the pO(2) measurement by an amount corresponding to 0.8 mm Hg. Good reproducibility of pO(2) measurement was shown in i) pO(2) values in the same cell line at different time points and ii) pO(2) values in two or three consecutive measurements in related regions within the same tumor. The Eppendorf 'Histograph' and the Diamond-General device showed no significant differences in pO(2) distribution in either subcutaneous tissue or MCaIV tumors. In conclusion, results of the Eppendorf 'Histograph' were consistent and reproducible and were similar to those obtained by the Diamond-General set-up.

16.
Genes Genet Syst ; 74(6): 271-86, 1999 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-10791023

RESUMO

The classic concept of epistatic fitness interactions between genes has been extended to study interactions within gene regions, especially between nucleotides that are important in maintaining pre-mRNA/mRNA secondary structures. It is shown that the majority of linkage disequilibria found within the Drosophila Adh gene are likely to be caused by epistatic selection operating on RNA secondary structures. A recently proposed method of RNA secondary structure prediction based on DNA sequence comparisons is reviewed and applied to several types of RNAs, including tRNA, rRNA, and mRNA. The patterns of covariation in these RNAs are analyzed based on Kimura's compensatory evolution model. The results suggest that this model describes the substitution process in the pairing regions (helices) of RNA secondary structures well when the helices are evolutionarily conserved and thermodynamically stable, but fails in some other cases. Epistatic selection maintaining pre-mRNA/mRNA secondary structures is compared to weak selective forces that determine features such as base composition and synonymous codon usage. The relationships among these forces and their relative strengths are addressed. Finally, our mutagenesis experiments using the Drosophila Adh locus are reviewed. These experiments analyze long-range compensatory interactions between the 5' and 3' ends of Adh mRNA, the different constraints on secondary structures in introns and exons, and the possible role of secondary structures in RNA splicing.


Assuntos
Evolução Biológica , Códon , Genética Populacional , RNA/química , RNA/genética , Álcool Desidrogenase/genética , Animais , Drosophila/genética , Modelos Biológicos , Mutação , Conformação de Ácido Nucleico , Splicing de RNA
17.
Int Angiol ; 19(1): 52-8, 2000 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-10853686

RESUMO

BACKGROUND: Under systemic hypertension induced by angiotensin II (AII) infusion, an attenuated vasoconstrictive response to the infusion in tumours was observed and a marked increase in tumour blood flow was observed in comparison with that in normal tissues. The results show a parallel circuit that connects the vascular bed of the pre-existing tissue to that of the tumour. The phenomenon was absent when hypertension was provoked by other vasoconstrictive agents such as norepinephrine or endothelin-1. However, the biological basis for this attenuated vasoconstrictive response to angiotensin II observed in tumours has not been fully elucidated. METHODS: We assessed this response to characterise the angiotensin II receptor density and affinity in normal and tumour tissues. AH109A and LY80 tumour cell lines were transplanted to the skin in nude rats. Four weeks later, the rats were sacrificed. 125I-[Sar1, Ile8] angiotensin II was used to map its receptors in rat tissues using in vitro computerised autoradiography. Operated human gastric cancer tissues from a 49-year-old and a 66-year-old male patients were also investigated. RESULTS: The numbers of angiotensin II receptors were markedly reduced in tumour tissues without a change of affinity. The numbers in AII-R in tumours were shown to be mainly AT1 by the marked reduction in radioligand binding achieved by losartan but not by PD123177. The same results were observed in human gastric cancer. CONCLUSIONS: These results suggest that the decrease in angiotensin II receptors in tumours may explain the haemodynamic effect of angiotensin II-induced hypertension on tumour blood flow. This condition for drug delivery to tumour tissue may play a major role in enhancing the therapeutic effects of chemotherapy.


Assuntos
Angiotensina II/metabolismo , Autorradiografia , Carcinoma/metabolismo , Receptores de Angiotensina/metabolismo , Neoplasias Cutâneas/metabolismo , Neoplasias Gástricas/metabolismo , Idoso , Angiotensina II/antagonistas & inibidores , Bloqueadores do Receptor Tipo 1 de Angiotensina II , Bloqueadores do Receptor Tipo 2 de Angiotensina II , Antagonistas de Receptores de Angiotensina , Animais , Anti-Hipertensivos/farmacologia , Sítios de Ligação , Biomarcadores Tumorais , Velocidade do Fluxo Sanguíneo , Carcinoma/patologia , Carcinoma/fisiopatologia , Humanos , Imidazóis/farmacologia , Losartan/farmacologia , Masculino , Pessoa de Meia-Idade , Transplante de Neoplasias , Neoplasias Experimentais , Piridinas/farmacologia , Ratos , Ratos Nus , Receptor Tipo 1 de Angiotensina , Receptor Tipo 2 de Angiotensina , Receptores de Angiotensina/efeitos dos fármacos , Neoplasias Cutâneas/patologia , Neoplasias Gástricas/patologia , Neoplasias Gástricas/fisiopatologia , Células Tumorais Cultivadas
18.
Gan To Kagaku Ryoho ; 17(3 Pt 2): 554-63, 1990 Mar.
Artigo em Japonês | MEDLINE | ID: mdl-1690967

RESUMO

Using a rat transparent chamber and a device for measurement of microvascular pressure, we observed tumor vascularization process in vivo and measured the daily change in pressure of a "starting vessel" which supplies blood to the tumor vascular network. Results were summarized as follows: (1) The position from which tumor vessels originated was usually the terminal portion of a terminal arteriole (starting vessel). The frequency with which new capillaries originated from vein and venule was very low. (2) Pressure of a starting vessel increased from 30-40 cm H2O (22-30 mmHg) to 120-130 cm H2O (88-96 mmHg) with enlargement of the tumor vascular network. As soon as pressure of a starting vessel reached a plateau, no-flow vessels appeared in places within a tumor. (3) Pressure of a starting vessel was elevated by angiotensin II. In turn, the elevated pressure of a starting vessel brought about a marked increase in tumor blood flow, resulting in the blood flow in no-flow vessels.


Assuntos
Neoplasias Hepáticas Experimentais/irrigação sanguínea , Angiotensina II/farmacologia , Animais , Pressão Sanguínea/efeitos dos fármacos , Neoplasias Hepáticas Experimentais/fisiopatologia , Masculino , Microcirculação/efeitos dos fármacos , Microcirculação/patologia , Microcirculação/fisiopatologia , Transplante de Neoplasias , Neovascularização Patológica/patologia , Neovascularização Patológica/fisiopatologia , Ratos , Ratos Endogâmicos , Fluxo Sanguíneo Regional/efeitos dos fármacos
19.
Gan To Kagaku Ryoho ; 27(8): 1191-200, 2000 Jul.
Artigo em Japonês | MEDLINE | ID: mdl-10945016

RESUMO

Tumor tissue is composed of cancer cells (parenchyma) and tumor vessels (interstitium). Many investigators have pointed out that blood flow in tumors has a very inhomogenous distribution, and that this inhomogeneity in blood flow increases as tumors grew. This would be a certain cause of insufficient drug delivery to tumor tissues. Among the experimental evidence using Yoshida Sarcoma and Ascites Hepatomas, functional differences in microcirculation between tumor and normal tissues were found by Suzuki et al. (1977). Under hypertensive state induced by the continuous infusion of angiotensin II, tumor blood flow increased remarkably, while there was no change or decrease in blood flow in normal tissues such as the brain, bone marrow, liver and kidney. Moreover, the increase in blood flow in tumors was selective, as the mean blood pressure remained at the level of 150 mmHg. Increases were confirmed not only in many growing sites such as in the liver, muscle, subcutis, and even microfoci, but also in various kinds of xenografted human tumors and autochthonous tumors. Augmentation of the anti-tumor effects of angiotensin II-induced hypertension chemotherapy (IHC) for advanced gastric carcinoma was revealed in two randomized controlled trials (RCT-1 & 2) of collaborative study groups in Japan. The response rates were 42.9% vs 10.5% in RCT-1 and 31.3% vs 6.7% in RCT-2. The frequencies of toxicities were not statistically different. In the results of phase II studies from 1978 to 1994 (OPN-1) and 1995 to 1999 (OPN-2) for advanced gastric carcinoma (GC), the response rates were 37.9% and 35.7%. Down staging in which the conclusive stage score was lower than the score of the clinical stage, was observed in 8 out of 94 cases (19%) with primary lesions in total and in 30 patients (63%) receiving reduction surgery after IHC, since 1978. It is very important for exact evaluation after chemotherapy to understand or estimate the pathohistological changes in the tumor and its degenerated or repaired tissues, which present various clinical images. In the present study, the actual administered dose intensity of adriamycin (aDIadm) was 5.9 +/- 2.4 mg/sqm/w, and the ratio of aDIadm to the proposed DIadm of reported FAM/FAP schedules was 0.78 +/- 0.32. IHC with smaller DI could lead to a reduction in the accumulation of toxicities of anti-cancer drugs in the host. In conclusion, IHC might be applied to all kinds of tumors to enhance the chemotherapeutic effects through selective increase of drug delivery to tumors.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Sistemas de Liberação de Medicamentos/métodos , Sarcoma de Yoshida/irrigação sanguínea , Sarcoma de Yoshida/tratamento farmacológico , Neoplasias Gástricas/tratamento farmacológico , Animais , Pressão Sanguínea/efeitos dos fármacos , Doxorrubicina/administração & dosagem , Esquema de Medicação , Fluoruracila/administração & dosagem , Humanos , Microcirculação , Mitomicina/administração & dosagem , Ratos , Sarcoma de Yoshida/patologia , Neoplasias Gástricas/patologia , Neoplasias Gástricas/fisiopatologia
20.
Gan To Kagaku Ryoho ; 14(3 Pt 2): 961-70, 1987 Mar.
Artigo em Japonês | MEDLINE | ID: mdl-2436577

RESUMO

By using transparent chambers in rats, it proved possible to observe directly the normal vascular pattern and early neovascular response to solid tumor growth at high magnification. Morphologic studies of the vascularization patterns were performed daily by construction of photomontages from color instant film taken with a Polaroid camera. Noteworthy results obtained in this study were: In the normal subcutaneous tissue within the chamber, the main vascular pattern was similar to that described by Nicoll and Webb, showing the so-called "arcuate arteriolar pattern". The thoroughfare channel reported by Chambers and Zweifach was also observed. The establishment of new functional capillaries was observed within 2 weeks following the implantation of AH109A and AH272 tumors. The sprouts of newly formed vessels were seen originating at the arterial ends of the host capillaries, where the blood velocity was relatively high. The formation of intricate networks in the tumor occurred easily in a haphazard way; the three modes of network formation observed were sprouting, cross-connection and splitting. Progressive dilatation and tortuosity were observed in the preexisting vessels, especially capillaries and venules, in the neighborhood of the tumor implant. The arterioles, however, remained little altered and in a location almost identical to that at the time of tumor implantation. The vascular systems in the tumors were proved to parallel those in the normal organs from which they originated, from the microfocus stage to the large tumor stage. An understanding of the differences in the vascular architecture between normal and tumor tissue seems to be essential in order to elucidate the mechanism of enhancement of therapeutic effect by angiotensin II induced hypertension chemotherapy.


Assuntos
Neoplasias Hepáticas Experimentais/irrigação sanguínea , Animais , Arteríolas/patologia , Anastomose Arteriovenosa/patologia , Capilares/patologia , Masculino , Necrose , Neovascularização Patológica/patologia , Ratos , Ratos Endogâmicos
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