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1.
Oecologia ; 192(2): 449-462, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31960145

RESUMEN

In forest communities, conspecific density/distance dependence (CDD) is an important factor regulating diversity. It remains unknown how and the extent to which gap creation alters the mode and strength of CDD via changes in the relative importance of pathogens and mycorrhizae. Seeds of two hardwoods (i.e., Acer mono associated with arbuscular mycorrhizae [AM] and Quercus serrata associated with ectomycorrhizae [EM]) were sown reciprocally at four distances from the boundary between Acer- and Quercus-dominated forests towards forest interior in each of forest understories (FUs) and gaps. The causes of seed and seedling mortality, seedling growth and colonization of mycorrhizal fungi were investigated. In Acer, seed and seedling mortality were highest in Acer forests and gradually decreased towards the interior of Quercus forests in FU, mainly due to severe attack of soil pathogens, invertebrates, and leaf diseases. The reverse was true in gaps, due to reduction of damping-off damage caused by distance-dependent colonization of AM. In Quercus, most seeds and seedlings were eaten by vertebrates in FUs. The seedling mortality caused by leaf diseases was not high, even beneath conspecific forests with higher colonization of EM in gaps, suggesting a positive EM influence. In both species, seedling mass was greatest in conspecific forests and gradually decreased towards the interior of heterospecific forests in gaps, due to higher colonization of mycorrhizae near conspecifics. In conclusion, light conditions strongly altered the mode of CDD via changes in relative influence of pathogens and mycorrhizae, suggesting that gap creation may regulate species diversity via changes in the mode of CDD.


Asunto(s)
Acer , Micorrizas , Animales , Bosques , Plantones , Árboles
3.
Lupus ; 23(11): 1124-32, 2014 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-24860121

RESUMEN

The objective of this study was to clarify the long-term outcome in patients with lupus nephritis (LN) according to the International Society of Nephrology and Renal Pathology Society classification. This retrospective analysis comprised 186 Japanese patients given a diagnosis of LN by renal specimen with a mean observation period of 12 years. Primary end point was defined as death or end-stage renal disease, and standardized mortality ratios were calculated. Five patients presented with histopathological class I, 62 with II, 21 with III or III+V, 73 with IV or IV+V and 25 with V. Fourteen deaths occurred, corresponding to an overall standardized mortality ratio of 3.59 (95% confidence interval 2.02-5.81, p < 0.0001). Kaplan-Meier analysis revealed a 10-year overall survival of 95.7%. Nephrotic proteinuria (≥3.5 g/day) at baseline was identified as an independent poor prognostic factor for overall survival in Cox regression analysis. Kaplan-Meier analysis revealed a 10-year renal survival as 94.3%. Male gender and nephrotic proteinuria at baseline were identified as independent poor prognostic factors for renal survival in Cox regression analysis. In conclusion, LN was associated with a 3.59-fold increase in mortality compared with the general population. Male gender and nephrotic proteinuria were predictive for poor renal outcome.


Asunto(s)
Fallo Renal Crónico/epidemiología , Nefritis Lúpica/fisiopatología , Proteinuria/epidemiología , Adolescente , Adulto , Anciano , Niño , Femenino , Humanos , Japón , Estimación de Kaplan-Meier , Fallo Renal Crónico/etiología , Nefritis Lúpica/mortalidad , Masculino , Persona de Mediana Edad , Pronóstico , Modelos de Riesgos Proporcionales , Proteinuria/etiología , Estudios Retrospectivos , Factores de Riesgo , Factores Sexuales , Tasa de Supervivencia , Factores de Tiempo , Adulto Joven
4.
J Eur Acad Dermatol Venereol ; 22(2): 168-73, 2008 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-18211409

RESUMEN

BACKGROUND: Mondor's disease (MD) is considered an inflammatory condition of superficial vasculitis that develops mainly in the anterolateral thoracoabdominal wall. The pathogenesis of the disease has been controversial, however, because of the lack of histopathologic methods for differentiating between the small vein and the lymphatic vessel. AIM: To objectively examine the origin of vascular lesions in MD, we investigated the endothelial cells of their blood and lymphatic vessels. METHODS: Immunohistochemical examinations were carried out on specimens involving vascular lesions from 16 patients with MD, using antibodies against von Willebrand factor and human lymphatic vessel endothelial hyaluronan receptor-1, which specifically discriminate between lymphatic and blood vessels. RESULTS: The histopathologic findings clearly showed thrombophlebitis in 14 patients, a lesion originating in the lymphatic vessel in one patient, and sclerosis that consisted of the artery together with veins in another. CONCLUSION: This study suggests that almost all cases of MD are due to thrombophlebitis, with a small minority due to lymphangitis or other conditions. We believe this study will contribute to the better recognition of the factual changes in the condition designated MD.


Asunto(s)
Endotelio Linfático/metabolismo , Endotelio Linfático/patología , Endotelio Vascular/metabolismo , Endotelio Vascular/patología , Vasculitis/patología , Proteínas de Transporte Vesicular/metabolismo , Factor de von Willebrand/metabolismo , Pared Abdominal/patología , Adulto , Anciano , Diagnóstico Diferencial , Femenino , Humanos , Linfangitis/complicaciones , Linfangitis/diagnóstico , Vasos Linfáticos/metabolismo , Vasos Linfáticos/patología , Masculino , Persona de Mediana Edad , Tromboflebitis/complicaciones , Tromboflebitis/diagnóstico , Vasculitis/etiología , Vasculitis/metabolismo , Venas/metabolismo , Venas/patología
5.
Histopathology ; 51(3): 345-53, 2007 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-17727476

RESUMEN

AIMS: The lymphatic system is involved in fluid homeostasis of the cardiac interstitium, but lymphangiogenesis in myocardial remodelling has not previously been examined histopathologically. The aim was to investigate by D2-40 immunohistochemistry the sequential changes in lymphatic distribution in the process of myocardial remodelling after myocardial infarction (MI). METHODS AND RESULTS: Myocardial tissues in various phases of healing after MI were obtained from 40 autopsied hearts. D2-40+ lymphatic vessel density (LD) and CD34+ blood vessel density (BD) in the lesion were determined. BD decreased with advance of myocardial necrosis, subsequently increased at the early stage of granulation and thereafter decreased with the progression of scar formation. In contrast, lymphatic vessels were not detected in lesions with coagulation necrosis, and newly formed lymphatics first appeared in the early stages of granulation. A subsequent increase in LD was demonstrated in the late stages of granulation, and lymphatics remained up to the scar phase. Vascular endothelial growth factor-C was consistently expressed in viable cardiomyocytes around the lesion in all of these stages. CONCLUSION: In myocardial remodelling after MI, lymphangiogenesis lags behind blood vessel angiogenesis; newly formed lymphatics may be involved mainly in the maturation of fibrosis and scar formation through the drainage of excessive proteins and fluid.


Asunto(s)
Linfangiogénesis , Infarto del Miocardio/patología , Miocardio/patología , Remodelación Ventricular , Actinas/análisis , Adulto , Anciano , Anciano de 80 o más Años , Anticuerpos Monoclonales/análisis , Anticuerpos Monoclonales/inmunología , Anticuerpos Monoclonales de Origen Murino , Antígenos CD/análisis , Antígenos CD34/análisis , Antígenos de Diferenciación Mielomonocítica/análisis , Autopsia , Vasos Sanguíneos/química , Vasos Sanguíneos/patología , Femenino , Humanos , Inmunohistoquímica , Vasos Linfáticos/química , Vasos Linfáticos/patología , Masculino , Persona de Mediana Edad , Músculo Liso/química , Infarto del Miocardio/metabolismo , Infarto del Miocardio/fisiopatología , Miocardio/química , Índice de Severidad de la Enfermedad , Factor C de Crecimiento Endotelial Vascular/análisis
6.
Histopathology ; 49(3): 265-73, 2006 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-16918973

RESUMEN

AIMS: The renal lymphatics have not been fully documented in humans. The aim of this study was to clarify the morphology of the human renal lymphatic system under normal and pathological conditions by immunohistochemistry using anti-D2-40 antibody. METHODS AND RESULTS: Normal and pathological renal tissues obtained at autopsy as well as nephrectomy specimens with renal cell carcinoma (RCC) were used. Thin sections were immunostained with antibodies against D2-40 and CD31. In normal kidney, D2-40+ lymphatics were abundant in the interstitium around the interlobar and arcuate arteries/veins but sporadic in those around the glomeruli or between the tubules in the cortex. A few lymphatics contained erythrocytes in their lumina. Lymphatics were seldom present in the medulla. In RCC cases, lymphatics were evident at the tumour margin, whereas CD31+ capillaries were abundant throughout the tumour and lymphatics were increased in the fibrous interstitium around the tumour. Lymphatic invasion by RCC cells was also detectable. D2-40+ lymphatics were evident in other pathological conditions and end-stage kidney had a denser lymphatic distribution than normal kidney. CONCLUSIONS: Lymphatics are abundant around the arteries/veins and are also present in the renal cortex and medulla. D2-40 immunostaining is helpful for investigating the pathophysiological role of renal lymphatics.


Asunto(s)
Enfermedades Renales/patología , Riñón/anatomía & histología , Vasos Linfáticos/anatomía & histología , Anciano , Anticuerpos Monoclonales , Anticuerpos Monoclonales de Origen Murino , Carcinoma de Células Renales/metabolismo , Carcinoma de Células Renales/patología , Femenino , Humanos , Inmunohistoquímica , Riñón/metabolismo , Riñón/patología , Enfermedades Renales/metabolismo , Neoplasias Renales/metabolismo , Neoplasias Renales/patología , Vasos Linfáticos/metabolismo , Masculino , Persona de Mediana Edad
7.
Histopathology ; 47(3): 257-67, 2005 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-16115226

RESUMEN

AIMS: Secretory phospholipase A2 is associated with ischaemic injury in the human heart, but the distribution of type V secretory phospholipase A2 (sPLA2-V) remains unknown. The significance of sPLA2-V in myocardial infarction was investigated histopathologically. METHODS: Sequential changes in the localization of sPLA2-V and its mRNA in myocardial tissues obtained from 30 autopsied hearts were examined by immunohistochemistry and in situ hybridization and compared with those of fibronectin, vascular endothelial growth factor (VEGF), interleukin (IL)-1beta, tumour necrosis factor (TNF)-alpha, and cyclooxygenase-2 (COX-2). RESULTS: No expression of sPLA2-V was observed in normal heart, but it was promptly expressed in wavy myofibres positive for fibronectin just after the onset of infarction. sPLA2-V was subsequently expressed in ischaemic cardiomyocytes around the lesion. The expression decreased at the granulation tissue and disappeared at the chronic stage with scar formation. The distribution of the signal for sPLA2-V mRNA paralleled that of the protein. Ischaemic myocytes around the lesion expressed VEGF, IL-1beta, TNF-alpha and COX-2 at all stages. CONCLUSIONS: sPLA2-V production in myocardium is limited to the acute phase of infarction. sPLA2-V may play a dual role, acting both to remove degraded cell-membrane through cooperative activity with COX-2 in necrotic areas and to attack ischaemic myocytes around the lesion via degradation of membrane phospholipids.


Asunto(s)
Infarto del Miocardio/patología , Fosfolipasas A/genética , Remodelación Ventricular , Adulto , Anciano , Anciano de 80 o más Años , Autopsia , Ciclooxigenasa 2 , Femenino , Fibronectinas/análisis , Regulación Enzimológica de la Expresión Génica , Fosfolipasas A2 Grupo V , Humanos , Inmunohistoquímica , Hibridación in Situ , Interleucina-1/análisis , Masculino , Proteínas de la Membrana , Persona de Mediana Edad , Infarto del Miocardio/genética , Infarto del Miocardio/metabolismo , Miocardio/química , Miocardio/metabolismo , Miocardio/patología , Fosfolipasas A/metabolismo , Fosfolipasas A2 , Prostaglandina-Endoperóxido Sintasas/análisis , ARN Mensajero/genética , ARN Mensajero/metabolismo , Factor A de Crecimiento Endotelial Vascular/análisis
8.
Acta Neurochir (Wien) ; 147(7): 795-9; discussion 799, 2005 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-15864410

RESUMEN

Parafalcine chondrosarcoma is extremely rare, and may be difficult to differentiate preoperatively from falx meningioma. An 18-year-old woman presented with a parafalcine chondrosarcoma incidentally detected as a small lesion 2 years before admission, suggesting falx meningioma. Brain computed tomography and magnetic resonance imaging just before admission revealed the parafalcine lesion had increased by about nine times in volume during the last 2 years. Single-photon emission computed tomography (SPECT) after intravenous administration of both thallium-201 chloride ((201)TlCl) and N-isopropyl-p-[(123)I]iodoamphetamine ((123)I-IMP) demonstrated no abnormal uptake of either tracer. Histological examination revealed classic low-grade chondrosarcoma. Parafalcine chondrosarcoma should be considered at this site if relatively rapid growth is observed. SPECT using (201)TlCl and (123)I-IMP may be useful to discriminate parafalcine low-grade chondrosarcoma from meningioma or other tumours originating in this region.


Asunto(s)
Condrosarcoma/diagnóstico , Hallazgos Incidentales , Neoplasias Meníngeas/diagnóstico , Adolescente , Adulto , Condrosarcoma/patología , Condrosarcoma/cirugía , Fosa Craneal Posterior/patología , Fosa Craneal Posterior/cirugía , Diagnóstico Diferencial , Femenino , Estudios de Seguimiento , Humanos , Yofetamina , Imagen por Resonancia Magnética , Neoplasias Meníngeas/patología , Neoplasias Meníngeas/cirugía , Meninges/patología , Meninges/cirugía , Tomografía Computarizada de Emisión de Fotón Único , Tomografía Computarizada por Rayos X
9.
Biochim Biophys Acta ; 1514(2): 291-302, 2001 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-11557028

RESUMEN

System L is a major nutrient transport system responsible for the transport of large neutral amino acids including several essential amino acids. We previously identified a transporter (L-type amino acid transporter 1: LAT1) subserving system L in C6 rat glioma cells and demonstrated that LAT1 requires 4F2 heavy chain (4F2hc) for its functional expression. Since its oncofetal expression was suggested in the rat liver, it has been proposed that LAT1 plays a critical role in cell growth and proliferation. In the present study, we have examined the function of human LAT1 (hLAT1) and its expression in human tissues and tumor cell lines. When expressed in Xenopus oocytes with human 4F2hc (h4F2hc), hLAT1 transports large neutral amino acids with high affinity (K(m)= approximately 15- approximately 50 microM) and L-glutamine and L-asparagine with low affinity (K(m)= approximately 1.5- approximately 2 mM). hLAT1 also transports D-amino acids such as D-leucine and D-phenylalanine. In addition, we show that hLAT1 accepts an amino acid-related anti-cancer agent melphalan. When loaded intracellularly, L-leucine and L-glutamine but not L-alanine are effluxed by extracellular substrates, confirming that hLAT1 mediates an amino acid exchange. hLAT1 mRNA is highly expressed in the human fetal liver, bone marrow, placenta, testis and brain. We have found that, while all the tumor cell lines examined express hLAT1 messages, the expression of h4F2hc is varied particularly in leukemia cell lines. In Western blot analysis, hLAT1 and h4F2hc have been confirmed to be linked to each other via a disulfide bond in T24 human bladder carcinoma cells. Finally, in in vitro translation, we show that hLAT1 is not a glycosylated protein even though an N-glycosylation site has been predicted in its extracellular loop, consistent with the property of the classical 4F2 light chain. The properties of the hLAT1/h4F2hc complex would support the roles of this transporter in providing cells with essential amino acids for cell growth and cellular responses, and in distributing amino acid-related compounds.


Asunto(s)
Proteínas Portadoras/metabolismo , Sistemas de Transporte de Aminoácidos , Aminoácidos Esenciales/metabolismo , Animales , Antígenos CD/biosíntesis , Antígenos CD/genética , Proteínas Portadoras/biosíntesis , Proteínas Portadoras/química , Proteínas Portadoras/genética , Sondas de ADN , ADN Complementario/genética , ADN Complementario/aislamiento & purificación , Feto/metabolismo , Proteína-1 Reguladora de Fusión , Humanos , Datos de Secuencia Molecular , Oocitos/metabolismo , Biosíntesis de Proteínas , ARN Complementario/genética , ARN Complementario/aislamiento & purificación , ARN Mensajero/análisis , ARN Mensajero/biosíntesis , Especificidad por Sustrato , Células Tumorales Cultivadas , Xenopus
10.
Shokuhin Eiseigaku Zasshi ; 42(6): 404-12, 2001 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-11875827

RESUMEN

The mean concentration and daily intake of five preservatives were estimated based on the results of an analysis of 89,927 samples of food obtained in official inspections by Japanese local governments in fiscal year 1998. The mean concentration of benzoic acid was 9.5% of the allowable limit, and those of dehydroacetic acid, p-hydroxybenzoic acid, propionic acid, and sorbic acid were 1.5%, 5.7%, 1.7%, and 23.9%, respectively. Daily intake levels of these preservatives per person estimated from the concentration and daily consumption of foods were 6.23 mg, 0.0303 mg, 1.02 mg, 8.10 mg, and 25.0 mg, respectively, and assuming a body weight of 50 kg, the amounts of benzoic acid, p-hydroxybenzoic acid, and sorbic acid consumed were 2.5%, 0.2%, and 2.0% of their acceptable daily intakes, respectively. These values were similar to those obtained based on the results of the official inspections in fiscal years 1994 and 1996.


Asunto(s)
Análisis de los Alimentos , Inspección de Alimentos , Conservantes de Alimentos/administración & dosificación , Conservantes de Alimentos/análisis , Ácido Benzoico/administración & dosificación , Ácido Benzoico/análisis , Ingestión de Alimentos , Gobierno , Humanos , Japón , Parabenos/administración & dosificación , Parabenos/análisis , Propionatos/administración & dosificación , Propionatos/análisis , Pironas/administración & dosificación , Pironas/análisis , Ácido Sórbico/administración & dosificación , Ácido Sórbico/análisis , Factores de Tiempo
12.
J Biol Chem ; 275(27): 20787-93, 2000 Jul 07.
Artículo en Inglés | MEDLINE | ID: mdl-10777485

RESUMEN

The properties of system y(+)L-mediated transport were investigated on rat system y(+)L transporter, ry(+)LAT1, coexpressed with the heavy chain of cell surface antigen 4F2 in Xenopus oocytes. ry(+)LAT1-mediated transport of basic amino acids was Na(+)-independent, whereas that of neutral amino acids, although not completely, was dependent on Na(+), as is typical of system y(+)L-mediated transport. In the absence of Na(+), lowering of pH increased leucine transport, without affecting lysine transport. Therefore, it is proposed that H(+), besides Na(+) and Li(+), is capable of supporting neutral amino acid transport. Na(+) and H(+) augmented leucine transport by decreasing the apparent K(m) values, without affecting the V(max) values. We demonstrate that although ry(+)LAT1-mediated transport of [(14)C]l-leucine was accompanied by the cotransport of (22)Na(+), that of [(14)C]l-lysine was not. The Na(+) to leucine coupling ratio was determined to be 1:1 in the presence of high concentrations of Na(+). ry(+)LAT1-mediated leucine transport, but not lysine transport, induced intracellular acidification in Chinese hamster ovary cells coexpressing ry(+)LAT1 and 4F2 heavy chain in the absence of Na(+), but not in the presence of physiological concentrations of Na(+), indicating that cotransport of H(+) with leucine occurred in the absence of Na(+). Therefore, for the substrate recognition by ry(+)LAT1, the positive charge on basic amino acid side chains or that conferred by inorganic monovalent cations such as Na(+) and H(+), which are cotransported with neutral amino acids, is presumed to be required. We further demonstrate that ry(+)LAT1, due to its peculiar cation dependence, mediates a heteroexchange, wherein the influx of substrate amino acids is accompanied by the efflux of basic amino acids.


Asunto(s)
Sistemas de Transporte de Aminoácidos Básicos , Sistemas de Transporte de Aminoácidos Neutros , Aminoácidos/metabolismo , Proteínas Portadoras/metabolismo , Animales , Antígenos CD/genética , Sitios de Unión , Transporte Biológico , Células COS , Proteínas Portadoras/genética , Fluoresceínas , Proteína-1 Reguladora de Fusión , Concentración de Iones de Hidrógeno , Cinética , Leucina/metabolismo , Lisina/metabolismo , Microscopía Fluorescente , Oocitos/metabolismo , Ratas , Sodio/farmacología , Especificidad por Sustrato , Xenopus
13.
J Biol Chem ; 275(13): 9690-8, 2000 Mar 31.
Artículo en Inglés | MEDLINE | ID: mdl-10734121

RESUMEN

A cDNA was isolated from the mouse brain that encodes a novel Na(+)-independent neutral amino acid transporter. The encoded protein, designated as Asc-1 (asc-type amino acid transporter 1), was found to be structurally related to recently identified mammalian amino acid transporters for the transport systems L, y(+)L, x(C)(-), and b(0,+), which are linked, via a disulfide bond, to the type II membrane glycoproteins, 4F2 heavy chain (4F2hc), or rBAT (related to b(0,+) amino acid transporter). Asc-1 required 4F2hc for its functional expression. In Western blot analysis in the nonreducing condition, a 118-kDa band, which seems to correspond to the heterodimeric complex of Asc-1 and 4F2hc, was detected in the mouse brain. The band shifted to 33 kDa in the reducing condition, confirming that Asc-1 and 4F2hc are linked via a disulfide bond. Asc-1-mediated transport was not dependent on the presence of Na(+) or Cl(-). Although Asc-1 showed a high sequence homology (66% identity at the amino acid level) to the Na(+)-independent broad scope neutral amino acid transporter LAT2 (Segawa, H., Fukasawa, Y., Miyamoto, K., Takeda, E., Endou, H., and Kanai, Y. (1999) J. Biol. Chem. 274, 19745-19751), Asc-1 also exhibited distinctive substrate selectivity and transport properties. Asc-1 preferred small neutral amino acids such as Gly, L-Ala, L-Ser, L-Thr, and L-Cys, and alpha-aminoisobutyric acid as substrates. Asc-1 also transported D-isomers of the small neutral amino acids, in particular D-Ser, a putative endogenous modulator of N-methyl-D-aspartate-type glutamate receptors, with high affinity. Asc-1 operated preferentially, although not exclusively, in an exchange mode. Asc-1 mRNA was detected in the brain, lung, small intestine, and placenta. The functional properties of Asc-1 seem to be consistent with those of a transporter subserving the Na(+)-independent small neutral amino acid transport system asc.


Asunto(s)
Aminoácidos/metabolismo , Proteínas Portadoras/metabolismo , Sodio/metabolismo , Secuencia de Aminoácidos , Sistemas de Transporte de Aminoácidos , Animales , Transporte Biológico , Proteínas Portadoras/química , ADN Complementario , Concentración de Iones de Hidrógeno , Ratones , Datos de Secuencia Molecular , Ratas , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Homología de Secuencia de Aminoácido , Especificidad por Sustrato , Xenopus
14.
J Biol Chem ; 274(28): 19745-51, 1999 Jul 09.
Artículo en Inglés | MEDLINE | ID: mdl-10391916

RESUMEN

We have isolated a cDNA from rat small intestine that encodes a novel Na+-independent neutral amino acid transporter with distinctive characteristics in substrate selectivity and transport property. The encoded protein, designated L-type amino acid transporter-2 (LAT-2), shows amino acid sequence similarity to the system L Na+-independent neutral amino acid transporter LAT-1 (Kanai, Y., Segawa, H., Miyamoto, K., Uchino, H., Takeda, E., and Endou, H. (1998) J. Biol. Chem. 273, 23629-23632) (50% identity) and the system y+L transporters y+LAT-1 (47%) and KIAA0245/y+LAT-2 (45%) (Torrents, D., Estevez, R., Pineda, M., Fernandez, E., Lloberas, J., Shi, Y.-B., Zorzano, A., and Palacin, M. (1998) J. Biol. Chem. 273, 32437-32445). LAT-2 is a nonglycosylated membrane protein. It requires 4F2 heavy chain, a type II membrane glycoprotein, for its functional expression in Xenopus oocytes. LAT-2-mediated transport is not dependent on Na+ or Cl- and is inhibited by a system L-specific inhibitor, 2-aminobicyclo-(2,2,1)-heptane-2-carboxylic acid (BCH), indicating that LAT-2 is a second isoform of the system L transporter. Compared with LAT-1, which prefers large neutral amino acids with branched or aromatic side chains, LAT-2 exhibits remarkably broad substrate selectivity. It transports all of the L-isomers of neutral alpha-amino acids. LAT-2 exhibits higher affinity (Km = 30-50 microM) to Tyr, Phe, Trp, Thr, Asn, Ile, Cys, Ser, Leu, Val, and Gln and relatively lower affinity (Km = 180-300 microM) to His, Ala, Met, and Gly. In addition, LAT-2 mediates facilitated diffusion of substrate amino acids, as distinct from LAT-1, which mediates amino acid exchange. LAT-2-mediated transport is increased by lowering the pH level, with peak activity at pH 6.25, because of the decrease in the Km value without changing the Vmax value. Because of these functional properties and a high level of expression of LAT-2 in the small intestine, kidney, placenta, and brain, it is suggested that the heterodimeric complex of LAT-2 and 4F2 heavy chain is involved in the trans-cellular transport of neutral amino acids in epithelia and blood-tissue barriers.


Asunto(s)
Proteínas Portadoras/genética , Intestino Delgado/metabolismo , Secuencia de Aminoácidos , Sistemas de Transporte de Aminoácidos , Aminoácidos/metabolismo , Animales , Antígenos CD/genética , Transporte Biológico , Proteínas Portadoras/química , Clonación Molecular , Proteína-1 Reguladora de Fusión , Concentración de Iones de Hidrógeno , Cinética , Leucina/metabolismo , Proteínas de la Membrana/química , Proteínas de la Membrana/genética , Datos de Secuencia Molecular , Oocitos/metabolismo , ARN Complementario/genética , ARN Mensajero/metabolismo , Ratas , Alineación de Secuencia , Especificidad por Sustrato , Xenopus
15.
Biol Pharm Bull ; 21(9): 958-63, 1998 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-9781847

RESUMEN

2-Methylimidazole (2MI), as well as imidazole, has been thought to undergo cupro-ascorbate (Cu-VC)-catalyzed oxidative transformation in vitro to become a reactive species capable of combining with aldehydes intrinsic to connective-tissue proteins. We attempted to seize the essence of the above reaction through obtaining the structural information of an aldehyde-bonding species. As major products from 2MI in the in vitro Cu-VC system, 2-hydroxymethylimidazole (2(OH)MI) and 2-methyl-4(5H)(or 5(4H))-imidazolone (2MIone) were identified by mass-spectral and chromatographic comparison with the corresponding authentic standards synthesized. The in situ addition of acetaldehyde or propionaldehyde as a simple protein-aldehyde model to the system resulted in the deducible formation of an aldol condensate, 2-methyl-4(or 5)-ethylidene-4(5H)(or 5(4H))-imidazolone (2MEIone) or its possible analogue with a propylidene moiety, respectively. The authentic compound of 2MIone directly reacted with acetaldehyde and easily afforded the products assignable to the isomers of 2MEIone through the ethylidene moiety at physiological pH and temperature, whereas neither 2MI or 2(OH)MI reacted at all. These results suggest that a 4(5H)(or 5(4H))-imidazolone product, although simply a monooxygenated form, is sufficiently reactive to give aldol condensation-typed covalent adducts with aldehydes, even under physiological conditions, probably having an activated methylene moiety in the ring structure. Based on the present results, we discussed the mechanism of the retention of imidazole-containing drugs in connective tissue.


Asunto(s)
Aldehídos/metabolismo , Tejido Conectivo/metabolismo , Imidazoles/metabolismo , Acetaldehído/química , Acetaldehído/metabolismo , Aldehídos/química , Ácido Ascórbico/química , Radioisótopos de Carbono , Cromatografía Líquida de Alta Presión , Cromatografía Liquida , Cobre , Imidazoles/química , Imidazoles/farmacocinética , Espectrometría de Masas , Compuestos Organometálicos/química , Oxidación-Reducción , Especies Reactivas de Oxígeno/metabolismo
16.
Pathol Int ; 48(1): 47-52, 1998 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-9589464

RESUMEN

A case of malignant solitary fibrous tumor (SFT) is reported, occurring in a 61-year-old man with frequent hypoglycemia. Endocrinological analyses showed high serum levels of insulin-like growth factor II (IGF-II) and suppressed secretion of insulin. After the removal of a pleural tumor, which weighed 3150 g, serum IGF-II levels returned to normal and hypoglycemic attacks ceased. The tumor was composed of uniform spindle cells arranged in bundles, and fascicles with varying amounts of collagen and reticulin fibers. Mitotic figures at the rate of 6/10 high-power fields, and frequent foci of necrosis and hemorrhage were seen. Almost all of the tumor cells were immunohistochemically positive for vimentin and CD34. Electron microscopy revealed the immature mesenchymal or myofibroblastic nature of the tumor cells. These findings are consistent with malignant SFT of the pleura. Moreover, the tumor produced IGF-II mRNA as demonstrated by northern blot analysis. Thus, hypoglycemia of this patient was induced by SFT through the production and secretion of IGF-II.


Asunto(s)
Fibroma/metabolismo , Hipoglucemia/etiología , Factor II del Crecimiento Similar a la Insulina/metabolismo , Neoplasias Pleurales/metabolismo , Antígenos CD34/metabolismo , Northern Blotting , Fibroma/complicaciones , Fibroma/patología , Humanos , Hipoglucemia/sangre , Inmunohistoquímica , Factor II del Crecimiento Similar a la Insulina/análisis , Masculino , Microscopía Electrónica , Persona de Mediana Edad , Neoplasias Pleurales/complicaciones , Neoplasias Pleurales/patología , ARN Neoplásico/análisis
17.
Biol Pharm Bull ; 21(12): 1334-7, 1998 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-9881649

RESUMEN

Formation of a nucleophilic 4(5H)(or 5(4H))-imidazolone structure has been postulated from in vitro studies to be one of the causative elements involved in the retention of drugs with imidazole moiety in connective tissue. To confirm this, we searched for the imidazolone-related metabolite in rats after intravenous dosing of 2-methylimidazole (2MI; 14C-labeled and unlabeled form, 3 and 300 micromol/kg body weight) as a model compound. The excreted urine, the major route of elimination of the compound, was collected and analyzed using the HPLC/MS system with a counterion effect for metabolite separation. 2-Methyl-4(5H)(or 5(4H))-imidazolone (2MIone) was identified as a urinary metabolite by chromatographic and mass-spectral inspection with the corresponding authentic standard. Pretreatment of rats with either SKF-525A (50 mg/kg, i.p.) or cimetidine (200 mg/kg, i.p.) significantly increased the excreted amount of 2MIone in urine and the irreversible binding of 2MI equivalents in the aortic tissue, whereas both factors were reduced by pretreatment with triethylenetetramine dihydrochloride (150 mg/kg/d for 5 d, s.c.). These results support the aforementioned deduction, and also raise the possibility that a cytochrome P450-independent, copper-related metabolic reaction might be involved in the imidazolone formation in vivo.


Asunto(s)
Tejido Conectivo/metabolismo , Imidazoles/metabolismo , Imidazoles/farmacocinética , Animales , Biotransformación , Quelantes/farmacología , Cromatografía Líquida de Alta Presión , Cobre/metabolismo , Inhibidores Enzimáticos del Citocromo P-450 , Inhibidores Enzimáticos/farmacología , Imidazoles/orina , Masculino , Espectrometría de Masas , Ratas , Ratas Wistar
18.
Tuber Lung Dis ; 78(2): 117-22, 1997.
Artículo en Inglés | MEDLINE | ID: mdl-9692180

RESUMEN

OBJECTIVE: To characterize the correlation of the mutations in the pncA gene encoding pyrazinamidase (PZase) of Mycobacterium tuberculosis to a loss of PZase activity and development of pyrazinamide (PZA) resistance. DESIGN: The association of PZase activity, minimum inhibitory concentrations (MICs), and mutations in the pncA gene of M. tuberculosis isolated in mostly Asian countries was investigated. RESULTS: One hundred thirty-five out of 168 isolates were PZase positive, and 33 were negative. The MICs of PZA at pH 6.0 were over 400 micrograms/ml for all 33 PZase-negative isolates, while those of PZase-positive isolates were equal to or less than 200 micrograms/ml. Among 33 PZase-negative isolates sequenced, 32 (97%) had mutations within the pncA gene. A mutation was seen in various regions throughout the pncA gene. It was surprising that all three strains of in vitro selected PZA resistant mutants were PZase-positive and showed no change in the pncA gene. These results indicate that additional mechanisms may be involved in PZA resistance. No mutations were observed in all of 135 PZase-positive M. tuberculosis isolates tested, indicating that mutations in the pncA gene could be involved in the loss of PZase activity. CONCLUSIONS: Sequencing analysis of the pncA gene should provide rapid diagnosis of PZA resistant clinical isolates of M. tuberculosis.


Asunto(s)
Amidohidrolasas/genética , Farmacorresistencia Microbiana/genética , Mutación , Mycobacterium tuberculosis/genética , Pruebas de Sensibilidad Microbiana , Mycobacterium tuberculosis/enzimología , Reacción en Cadena de la Polimerasa , Pirazinamida
19.
Biol Pharm Bull ; 18(8): 1094-103, 1995 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-8535403

RESUMEN

Electroencephalogram (EEG) alterations in rat after the i.v. administration of pentobarbital (PTB) and chlorpromazine (CPZ) were measured by power spectral analysis. The time courses of PTB concentrations in plasma, cerebrospinal fluid (CSF) and brain were determined after the i.v. administration of PTB (20, 40 mg/kg) by GC-MS. The PTB concentrations in plasma, CSF and brain could be described by a biexponential equation, a CSF model and a blood flow limited model, respectively. The relationship between the alteration of EEG and the PTB concentrations in the CSF or brain or the effect compartment were analyzed using the sigmoid Emax model. The alteration of EEG after PTB administration could be described by the PTB concentration in these compartments using the sigmoid Emax model. These results indicated that the site of action for the alteration of EEG after PTB administration is in instantaneous equilibrium with the CSF, the brain and the effect compartment. Thus, alterations in EEG after PTB administration can be predicted by monitoring the total PTB concentration in plasma. The alteration of EEG after i.v. administration of CPZ (4 mg/kg) showed a two-phase variation. Although the relationship between the alteration of EEG and the CPZ concentrations in CSF or the striatum or the effect compartment (total and free drug) were analyzed using the linear model, the Emax model or the sigmoid Emax model, the two-phase alteration of EEG after CPZ administration could not be described by any of these models. These results indicated that the pharmacokinetic and pharmacodynamic modeling of CPZ during the alteration of EEG may be complicated due to several pharmacokinetic and pharmacodynamic factors, such as an alteration of the free fraction of CPZ in the striatum, the formation of active metabolites, and two different intrinsic effects of CPZ on the EEG (one in an increase and the other in a decrease of the brain's electrical activity.


Asunto(s)
Encéfalo/efectos de los fármacos , Clorpromazina/farmacología , Electroencefalografía/efectos de los fármacos , Pentobarbital/farmacología , Animales , Encéfalo/fisiología , Clorpromazina/farmacocinética , Masculino , Pentobarbital/farmacocinética , Ratas , Ratas Wistar
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