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1.
J Dairy Sci ; 106(6): 4443-4453, 2023 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-37080779

RESUMO

Kraft pulp (KP), an intermediate product obtained when wood chips are converted to paper, contains highly digestible fiber. This study evaluated the effect of KP inclusion in calf starters on growth performance, health, and plasma glucagon-like peptide 2 (GLP-2) concentration in calves. Twenty-five Holstein heifer calves were raised on a high plane of nutrition program using milk replacer containing 29% crude protein and 18% fat until 49 d after birth, and were fed calf starters containing KP at 0 (CON; n = 14) or 12% (KPS; n = 11) on a dry matter basis. All calves were fed the treatment calf starters and timothy hay ad libitum. Blood was collected at 4, 14, 21, 35, 49, 70, and 91 d after birth. Dry matter intake (DMI) of milk replacer and hay was not affected by treatment, whereas calf starter DMI was lower for KPS (0.93 kg/d) than for CON (1.03 kg/d). Higher neutral detergent fiber (NDF) content in KPS (31.7%) than in the CON starter (22.1%) resulted in higher NDF intake for KPS (0.55 kg/d) than for CON (0.47 kg/d). However, the consumption of starch was lower for KPS (0.29 kg/d) than for CON (0.33 kg/d). Despite the lower starter intake for KPS, body weight and average daily gain did not differ between treatments. No significant difference was observed in the plasma concentrations of metabolites, except for ß-hydroxybutyrate (BHB); BHB concentration was lower for KPS (216 µmol/L) than for CON (257 µmol/L). The area under the curve for plasma GLP-2 concentration was higher for KPS (54.1 ng/mL × d) than for CON (36.0 ng/mL × d). Additionally, the fecal score postweaning (1.19 and 1.48 for KPS and CON, respectively) and the number of days that calves developed diarrhea throughout the experimental period (2.50 d and 8.10 d for KPS and CON, respectively) were lower for KPS than for CON. These results indicate that feeding KP reduces the severity and frequency of diarrhea without adversely affecting growth performance. This could be attributed to the increased plasma GLP-2 concentration induced by higher NDF intake.


Assuntos
Dieta , Peptídeo 2 Semelhante ao Glucagon , Animais , Bovinos , Feminino , Desmame , Dieta/veterinária , Ração Animal/análise , Peso Corporal , Diarreia/veterinária , Ácido 3-Hidroxibutírico
2.
Osteoarthritis Cartilage ; 28(11): 1459-1470, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-32818603

RESUMO

OBJECTIVE: Exostosin-1 (EXT1) and EXT2 are the major genetic etiologies of multiple hereditary exostoses and are essential for heparan sulfate (HS) biosynthesis. Previous studies investigating HS in several mouse models of multiple hereditary exostoses have reported that aberrant bone morphogenetic protein (BMP) signaling promotes osteochondroma formation in Ext1-deficient mice. This study examined the mechanism underlying the effects of HS deficiency on BMP/Smad signaling in articular cartilage in a cartilage-specific Ext-/- mouse model. METHOD: We generated mice with a conditional Ext1 knockout in cartilage tissue (Ext1-cKO mice) using Prg4-Cre transgenic mice. Structural cartilage alterations were histologically evaluated and phospho-Smad1/5/9 (pSmad1/5/9) expression in mouse chondrocytes was analyzed. The effect of pharmacological intervention of BMP signaling using a specific inhibitor was assessed in the articular cartilage of Ext1-cKO mice. RESULTS: Hypertrophic chondrocytes were significantly more abundant (P = 0.021) and cartilage thickness was greater in Ext1-cKO mice at 3 months postnatal than in control littermates (P = 0.036 for femur; and P < 0.001 for tibia). However, osteoarthritis did not spontaneously occur before the 1-year follow-up. matrix metalloproteinase (MMP)-13 and adamalysin-like metalloproteinases with thrombospondin motifs(ADAMTS)-5 were upregulated in hypertrophic chondrocytes of transgenic mice. Immunostaining and western blotting revealed that pSmad1/5/9-positive chondrocytes were more abundant in the articular cartilage of Ext1-cKO mice than in control littermates. Furthermore, the BMP inhibitor significantly decreased the number of hypertrophic chondrocytes in Ext1-cKO mice (P = 0.007). CONCLUSIONS: HS deficiency in articular chondrocytes causes chondrocyte hypertrophy, wherein upregulated BMP/Smad signaling partially contributes to this phenotype. HS might play an important role in maintaining the cartilaginous matrix by regulating BMP signaling.


Assuntos
Proteínas Morfogenéticas Ósseas/metabolismo , Cartilagem Articular/metabolismo , Condrócitos/metabolismo , Heparitina Sulfato/deficiência , Osteoartrite do Joelho/metabolismo , Proteína ADAMTS5/metabolismo , Animais , Proteínas Morfogenéticas Ósseas/antagonistas & inibidores , Cartilagem Articular/citologia , Condrócitos/patologia , Modelos Animais de Doenças , Hipertrofia , Metaloproteinase 13 da Matriz/metabolismo , Camundongos , Camundongos Knockout , Camundongos Transgênicos , N-Acetilglucosaminiltransferases/genética , Osteoartrite do Joelho/genética , Osteoartrite do Joelho/patologia , Pirazóis/farmacologia , Pirimidinas/farmacologia , Proteína Smad1/metabolismo , Proteína Smad5/metabolismo , Proteína Smad8/metabolismo
3.
Phys Rev Lett ; 120(19): 196401, 2018 May 11.
Artigo em Inglês | MEDLINE | ID: mdl-29799253

RESUMO

Quantum mechanics tells us that the hopping integral between local orbitals makes the energy band dispersive. In a lattice with geometric frustration, however, dispersionless flat bands may appear due to quantum interference. Several models possessing flat bands have been proposed theoretically, and many attracting magnetic and electronic properties are predicted. However, despite many attempts to realize these models experimentally, compounds that are appropriately described by this model have not been found so far. Here we show that pyrochlore oxides Sn_{2}Nb_{2}O_{7} and Sn_{2}Ta_{2}O_{7} are such examples, by performing first-principles band calculation and several tight-binding analyses. Moreover, spin-polarized band calculation shows that the hole-doped systems Sn_{2}Nb_{2}O_{6}N and Sn_{2}Ta_{2}O_{6}N have complete spin polarization, and their magnetic moments are mostly carried by Sn-s and N-p orbitals, which are usually nonmagnetic. These compounds are not only candidates for ferromagnets without a magnetic element, but also will provide an experimental platform for a flat-band model which shows a wide range of physical properties.

4.
Nat Mater ; 11(8): 675-81, 2012 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-22797829

RESUMO

The electron-phonon interaction is of central importance for the electrical and thermal properties of solids, and its influence on superconductivity, colossal magnetoresistance and other many-body phenomena in correlated-electron materials is the subject of intense research at present. However, the non-local nature of the interactions between valence electrons and lattice ions, often compounded by a plethora of vibrational modes, presents formidable challenges for attempts to experimentally control and theoretically describe the physical properties of complex materials. Here we report a Raman scattering study of the lattice dynamics in superlattices of the high-temperature superconductor YBa(2)Cu(3)O(7) (YBCO) and the colossal-magnetoresistance compound La(2/3)Ca(1/3)MnO(3) that suggests a new approach to this problem. We find that a rotational mode of the MnO(6) octahedra in La(2/3)Ca(1/3)MnO(3) experiences pronounced superconductivity-induced line-shape anomalies, which scale linearly with the thickness of the YBCO layers over a remarkably long range of several tens of nanometres. The transfer of the electron-phonon coupling between superlattice layers can be understood as a consequence of long-range Coulomb forces in conjunction with an orbital reconstruction at the interface. The superlattice geometry thus provides new opportunities for controlled modification of the electron-phonon interaction in complex materials.

5.
Sci Rep ; 13(1): 4743, 2023 Mar 23.
Artigo em Inglês | MEDLINE | ID: mdl-36959386

RESUMO

Electron systems with strong geometrical frustrations have flat bands, and their unusual band dispersions are expected to induce a wide variety of physical properties. However, for the emergence of such properties, the Fermi level must be pinned within the flat band. In this study, we performed first-principles calculations on pyrochlore oxide Pb[Formula: see text]Sb[Formula: see text]O[Formula: see text] and theoretically clarified that the self-doping mechanism induces pinning of the Fermi level in the flat band in this system. Therefore, a very high density of states is realized at the Fermi level, and the ferromagnetic state transforms into the ground state via a flat band mechanism, although the system does not contain any magnetic elements. This compound has the potential to serve as a new platform for projecting the properties of flat band systems in the real world.

7.
J Exp Med ; 144(1): 193-208, 1976 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-180229

RESUMO

Thymocytes from preleukemic AKR mice aged 5-6 mo have an altered pattern of cell surface antigens. The expression of four MuLV-related antigens on the cell surface (GIX, GCSA, gp70, p30) is markedly increased in comparison to 2-mo-old AKR mice and approximates the heightened levels of these antigens found on thymic leukemia cells. H-2 and Thy-1 alloantigens also show characteristic modifications in relation to age and leukemia development. In contrast to the high Thy-1/low H-2 levels on 2-mo-old AKR thymocytes, thymocytes from 6-mo-old mice and thymic leukemia cells frequently show a low Thy-1/high H-2 surface phenotype. As thymocytes from mouse strains with a low incidence of leukemia do not show these changes, they appear to represent a stage in the conversion of normal cells to leukemia cells.


Assuntos
Envelhecimento , Antígenos de Neoplasias , Antígenos Virais , Leucemia Experimental/imunologia , Camundongos Endogâmicos AKR/imunologia , Timo/imunologia , Animais , Antígenos de Neoplasias/análise , Antígenos Virais/análise , Antígenos de Histocompatibilidade , Isoantígenos/análise , Vírus da Leucemia Murina/imunologia , Camundongos , Propriedades de Superfície , Linfócitos T/imunologia , Proteínas Virais/imunologia
8.
Nanoscale Res Lett ; 13(1): 63, 2018 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-29484486

RESUMO

Quantum mechanics states that hopping integral between local orbitals makes the energy band dispersive. However, in some special cases, there are bands with no dispersion due to quantum interference. These bands are called as flat band. Many models having flat band have been proposed, and many interesting physical properties are predicted. However, no real compound having flat band has been found yet despite the 25 years of vigorous researches. We have found that some pyrochlore oxides have quasi-flat band just below the Fermi level by first principles calculation. Moreover, their valence bands are well described by a tight-binding model of pyrochlore lattice with isotropic nearest neighbor hopping integral. This model belongs to a class of Mielke model, whose ground state is known to be ferromagnetic with appropriate carrier doping and on-site repulsive Coulomb interaction. We have also performed a spin-polarized band calculation for the hole-doped system from first principles and found that the ground state is ferromagnetic for some doping region. Interestingly, these compounds do not include magnetic element, such as transition metal and rare-earth elements.

10.
Endoscopy ; 39(5): 390-3, 2007 May.
Artigo em Inglês | MEDLINE | ID: mdl-17516343

RESUMO

BACKGROUND AND STUDY AIMS: Multiple studies have demonstrated the feasibility of peroral transgastric endoscopic procedures in animal models. The aim of the study was to evaluate the feasibility of a peroral transgastric endoscopic approach to repair abdominal wall hernias. PATIENTS AND METHODS: We performed acute experiments under general anesthesia with endotracheal intubation using 50-kg pigs. Following peroral intubation an incision of the gastric wall was made and the endoscope was advanced into the peritoneal cavity. An internal anterior abdominal wall incision was performed with a needle knife to create an animal model of a ventral hernia. After hernia creation an endoscopic suturing device was used for primary repair of the hernia. After completion of the hernia repair the endoscope was withdrawn into the stomach and the gastric wall incision was closed with endoscopic clips. Then the animals were killed for necropsy. RESULTS: Two acute experiments were performed. Incision of the gastric wall was easily achieved with a needle knife and a pull-type sphincterotome. A large (3 x 2 cm) defect of the abdominal wall (ventral hernia model) was closed with five or six sutures using the endoscopic suturing device. Postmortem examination revealed complete closure of the hernia without any complications. CONCLUSIONS: Transgastric endoscopic primary repair of ventral hernias in a porcine model is feasible and may be technically simpler than laparoscopic surgery.


Assuntos
Endoscopia do Sistema Digestório/métodos , Hérnia Abdominal/cirurgia , Animais , Modelos Animais de Doenças , Estudos de Viabilidade , Intubação/métodos , Suínos
11.
Nanoscale Res Lett ; 12(1): 127, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28235362

RESUMO

Valence-skip compound is a good candidate with high T c and low anisotropy because it has a large attractive interaction at the site of valence-skip atom. However, it is not easy to synthesize such compound because of (i) the instability of the skipping valence state, (ii) the competing charge order, and (iii) that formal valence may not be true in some compounds. In the present study, we show several examples of the valence-skip compounds and discuss how we can design them by first principles calculations. Furthermore, we calculated the electronic structure of a promising candidate of valence skipping compound RbTlCl3 from first principles. We confirmed that the charge-density wave (CDW) is formed in this compound, and the Tl atoms in two crystallographic different sites take the valence Tl1+ and Tl3+. Structure optimization study reveals that this CDW is stable at the ambient pressure, while this CDW gap can be collapsed when we apply pressure with several gigapascals. In this metallic phase, we can expect a large charge fluctuation and a large electron-phonon interaction.

12.
Benef Microbes ; 8(3): 353-365, 2017 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-28504574

RESUMO

Herein we investigated the intestinal carriage of α-toxigenic and enterotoxigenic Clostridium perfringens during infancy, focusing on its association with other gut microbes and mode of delivery and feeding. Faecal samples from 89 healthy term infants were collected at age 7 days, 1 month, 3 months, 6 months and 3 years. C. perfringens was quantified by qPCR; other gut bacteria were quantified by reverse-transcription-qPCR. Alpha-toxigenic C. perfringens was detected in 3.4% infants at day 7 but was present in 35-40% infants at subsequent time-points, with counts ranging from 103-107 cells/g faeces. Enterotoxigenic C. perfringens remained undetected at day 7 but was detected in 1.1, 4.5, 10.1 and 4.5% infants at 1 month, 3 months, 6 months and 3 years, respectively. Intriguingly, infants carrying α-toxigenic C. perfringens had lower levels of Bacteroides fragilis group, bifidobacteria, lactobacilli and organic acids as compared to non-carriers. Further analyses revealed that, compared to vaginally-born infants, caesarean-born infants had higher carriage of C. perfringens and lower levels of B. fragilis group, bifidobacteria, lactobacilli and faecal organic acids during first 6 months. Compared to formula-fed infants, breast-fed infants were slightly less often colonised with C. perfringens; and within caesarean-born infants, breast-fed infants had slightly lower levels of C. perfringens and higher levels of B. fragilis group, bifidobacteria, and lactobacilli than formula-fed infants. This study demonstrates the quantitative dynamics of toxigenic C. perfringens colonisation in infants during the early years of life. Caesarean-born infants acquire a somewhat perturbed microbiota, and breast-feeding might be helpful in ameliorating this dysbiosis. Higher carriage of toxigenic C. perfringens in healthy infants is intriguing and warrants further investigation of its sources and clinical significance in infants, particularly the caesarean-born who may represent a potential reservoir of this opportunistic pathogen and might be more prone to associated illnesses.


Assuntos
Toxinas Bacterianas/metabolismo , Proteínas de Ligação ao Cálcio/metabolismo , Cesárea/efeitos adversos , Clostridium perfringens/isolamento & purificação , Disbiose , Enterotoxinas/metabolismo , Microbioma Gastrointestinal/fisiologia , Intestinos/microbiologia , Fosfolipases Tipo C/metabolismo , Bacteroides fragilis/isolamento & purificação , Bifidobacterium/isolamento & purificação , Pré-Escolar , Clostridium perfringens/patogenicidade , Fezes/microbiologia , Feminino , Humanos , Lactente , Recém-Nascido , Lactobacillus/isolamento & purificação , Masculino
13.
J Natl Cancer Inst ; 72(3): 715-24, 1984 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-6583456

RESUMO

The correlation between induction of spinal cord tumor by N-ethyl-N-nitrosourea (ENU) (CAS: 759-73-9; 1-ethyl-1-nitrosourea) and postnatal cellular differentiation of the spinal cord was examined in 6 different strains of rats [noninbred Wistar and inbred F344, WF, LE, WF (female) X LE (male), and LE (female) X WF (male)]. By perinatal injection of 40 mg ENU/kg, 258 spinal cord tumors were induced in 175 of 372 ENU-treated rats. The spinal cords of rats at ages ranging from day 1 to day 8 after birth were particularly susceptible to the oncogenic effect of ENU. All spinal cord tumors developed in the white matter without any segmental predilection site. Moreover, most (93%) were found in the subpial region of the spinal cord and were classified as oligodendrogliomas. Morphologic and autoradiographic examinations revealed accumulation of spinal subpial immature glial cells from day 1 to day 8 after birth when the spinal cord had a high susceptibility and most of the cells were destined to differentiate into oligodendrocytes. These data show the existence of target cells in the spinal cords of rats after ENU carcinogenesis.


Assuntos
Etilnitrosoureia/toxicidade , Compostos de Nitrosoureia/toxicidade , Neoplasias da Medula Espinal/patologia , Medula Espinal/patologia , Envelhecimento , Animais , Animais Recém-Nascidos , Encéfalo/efeitos dos fármacos , Replicação do DNA/efeitos dos fármacos , Feminino , Troca Materno-Fetal , Tamanho do Órgão/efeitos dos fármacos , Gravidez , Ratos , Ratos Endogâmicos F344 , Ratos Endogâmicos , Especificidade da Espécie , Medula Espinal/efeitos dos fármacos , Medula Espinal/crescimento & desenvolvimento , Neoplasias da Medula Espinal/induzido quimicamente
14.
J Natl Cancer Inst ; 76(1): 115-8, 1986 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-3455734

RESUMO

The carcinogenicity of o-ethoxybenzamide (CAS: 938-73-8), which is also called ethenzamide and which is widely used as an antipyretic anodyne in Japan, was examined in 298 (C57BL/6N X C3H/HeN)F1 mice. Groups of males and females were fed a diet containing 0 (control), 0.4, or 1.2% o-ethoxybenzamide for 96 weeks and sacrificed at the 100th week. Among the male mice fed the higher dose of the drug, the total incidence of liver cell tumors was 68%, with 18% of the mice developing hepatocellular carcinomas; both yields were significantly higher than those in the controls. In o-ethoxybenzamide-treated male mice the multiplicities of the hepatic cell tumors were also significantly higher than the multiplicity of the hepatic tumor in male control mice. A dose-response relationship with regard to both incidence and multiplicities of hepatic cell tumors in male mice was observed. In female mice fed o-ethoxybenzamide the incidence and multiplicities of the liver cell tumors were increased compared to those of the controls, but statistical significance was observed only in the multiplicity of tumors in mice given the lower dose. In both sexes hepatic cell tumors developed earlier than in the controls. These results show that o-ethoxybenzamide enhances the development of hepatic cell tumors in male (C57BL/6N X C3H/HeN)F1 mice.


Assuntos
Neoplasias Hepáticas Experimentais/induzido quimicamente , Salicilamidas/toxicidade , Animais , Peso Corporal/efeitos dos fármacos , Feminino , Fígado/efeitos dos fármacos , Masculino , Camundongos , Camundongos Endogâmicos C3H , Camundongos Endogâmicos C57BL , Tamanho do Órgão/efeitos dos fármacos
15.
J Natl Cancer Inst ; 81(23): 1823-8, 1989 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-2585529

RESUMO

An allo-major histocompatibility complex class I gene (H-2Kb) was transfected to murine mastocytoma P1.HTR (P815 subline) cells, after which several transfectant clones were obtained. Two clones, which expressed a low level of H-2Kb antigen, grew well and killed the syngeneic DBA/2 mice when they were inoculated ip. These mice lived longer than the mice given injections of the parental P1.HTR tumor. However, one clone, which expressed a high level of H-2Kb antigen, was rejected completely by the syngeneic DBA/2 mice and induced a generation of H-2Kb-specific cytotoxic T cells. Interestingly, the mice that had rejected the clone with high H-2Kb expression received strong anti-tumor immunity for rejection of the parental P1.HTR tumor challenged at the high dose.


Assuntos
Antígenos/análise , Leucemia Experimental/imunologia , Complexo Principal de Histocompatibilidade/genética , Transfecção/imunologia , Animais , Testes de Carcinogenicidade , Células Clonais , Rejeição de Enxerto , Leucemia Experimental/genética , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos DBA , Transplante de Neoplasias , Plasmídeos/genética , Linfócitos T Citotóxicos/imunologia , Imunologia de Transplantes , Células Tumorais Cultivadas
16.
Eur J Pediatr Surg ; 16(2): 115-9, 2006 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-16685618

RESUMO

Recessive dystrophic epidermolysis bullosa (RDEB) is an inherited disorder of squamous epithelium that results in dystrophic scarring of the skin after minor trauma. RDEB is classified into two subtypes: Hallopeau-Siemens (HS) and non-Hallopeau-Siemens (nHS). Although severe scarring of the skin is the most common and obvious complication of the disease, esophageal scarring with formation of long strictures may also develop. Treatment options for esophageal stenosis in patients with RDEB include steroids, hyperalimentation, esophageal dilation and replacement. This report describes a child who was dilated immediately after diagnosis of severe esophageal stenosis subsequent to nHS-RDEB and managed successfully. Endoscopic esophageal balloon dilation under fluoroscopic control was very useful for detecting the region of stenosis and bougienage. The literature on such injuries is reviewed here, and the problems associated with the treatment of children with esophageal stenosis associated with RDEB are discussed.


Assuntos
Cateterismo/métodos , Epidermólise Bolhosa Distrófica/complicações , Estenose Esofágica/terapia , Criança , Transtornos de Deglutição/etiologia , Transtornos de Deglutição/terapia , Estenose Esofágica/etiologia , Estenose Esofágica/patologia , Esofagoscopia , Humanos , Masculino
17.
Cancer Res ; 48(22): 6450-4, 1988 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-3263189

RESUMO

T-cell clone K4L, the cell surface phenotypes of which were Thy-1+, Lyt-1-, Lyt-2+, and L3T4-, was established from the spleen cells of a murine leukemia L1210-immune mouse. Clone K4L was specific for antigen B on L1210, and this antigen was different from antigen A for which the previously reported T-cell clone K7L was specific. K4L possessed cytotoxicity and tumor growth-inhibitory activity against both L1210 and antigen A loss variant, L1210-K7L-, but not against syngeneic tumor P388 or L5178Y. Previously we showed that antigen A was lost frequently for generation of antigen loss variants. In contrast, antigen B was barely found to be lost. When mice were inoculated with L1210 plus a moderate dose of K4L, the tumor grew after initial suppression but this newly emerging tumor was K4L sensitive and was ultimately rejected. The mice initially given L1210 plus K4L attained a high-grade tumor-specific immunity for rejecting the subsequently challenged high-dose (10(7) cells) L1210. This immunity did not involve any bystander antitumor activity against the third party P388 lymphoma that was injected together with L1210 but accompanied the increase in the L1210-specific cytotoxic T-lymphocyte activity. Evidence was provided that the live L1210, the outgrowth of which was inhibited by K4L, induced an effective immune response of radiation-sensitive host lymphocytes including L3T4+ helper T-cells. Taken together, our results show a novel strategy for inducing high-grade host-dependent antitumor immunity by use of a cytotoxic T-lymphocyte clone specific for a stable tumor-specific transplantation antigen.


Assuntos
Antígenos de Neoplasias/imunologia , Antígenos de Histocompatibilidade/imunologia , Leucemia L1210/imunologia , Linfócitos T Citotóxicos/imunologia , Animais , Células Clonais , Feminino , Imunização Passiva , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos DBA
18.
Cancer Res ; 45(12 Pt 1): 6436-41, 1985 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-4063991

RESUMO

A new transplantable pituitary tumor, designated MtT/F84, was induced in estrogenized female F344 rats and has been serially passaged in 17 beta-estradiol-treated females. It grew well in rats treated with estrone, 17 beta-estradiol, or estriol but not in intact females or in rats given progesterone or testosterone. The growth of MtT/F84 in rats grafted with up to 1.6 X 10(6) tumor cells and given 17 beta-estradiol was inhibited by orally administered high dose bromocriptine (37.5 mg/kg in food) or by intraperitoneal injection of tamoxifen citrate but was not inhibited by low dose bromocriptine (3.75 mg/kg in food). The tumors grown in intact females contain high amounts of estrogen receptor, and they were greatly reduced in the tumors grown either in 17 beta-estradiol or 17 beta-estradiol-plus-tamoxifen loaded rats. However, administration of bromocriptine resulted in estrogen receptor levels significantly higher than those of tumors grown in 17 beta-estradiol. The existence of dopamine receptor was also confirmed. Growth inhibition of MtT/F84 either by high dose bromocriptine or by tamoxifen may be a direct action and may be an estrogen and dopamine receptor-mediated phenomenon.


Assuntos
Bromocriptina/uso terapêutico , Neoplasias Hipofisárias/tratamento farmacológico , Tamoxifeno/uso terapêutico , Animais , Relação Dose-Resposta a Droga , Estradiol/farmacologia , Feminino , Transplante de Neoplasias , Neoplasias Hipofisárias/metabolismo , Neoplasias Hipofisárias/patologia , Ratos , Ratos Endogâmicos F344 , Receptores Dopaminérgicos/metabolismo , Receptores de Estrogênio/metabolismo
19.
Cancer Res ; 47(24 Pt 1): 6494-9, 1987 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-3499976

RESUMO

Originally T-cell clone K7L-sensitive L1210 murine leukemia clones were tested for their capacity to generate K7L-insensitive variants at various times after cloning. All of the L1210 clones (L1210/1, -2, -4, and -7) maintained in vitro for 1 month were severely inhibited in their growth in the culture in which K7L was added and in mice given injections of K7L at the initial stage. This indicated that any L1210 clone tested was not a mixture of K7L-sensitive and K7L-insensitive clones at the time of cloning. By both in vivo and in vitro K7L-mediated tumor suppression assays, K7L-insensitive antigen loss variants were then found to be generated from some (L1210/4, L1210/7) but not other (L1210/1, L1210/2) originally K7L-sensitive L1210 clones during 1 month of maintenance. Ratios of variant cells to total clone cells 1 month after cloning were estimated around 0.1% for L1210/7, 0.01% for L1210/4, and less than 0.001% (undetectable) for L1210/1 and L1210/2. Neither L1210/1 nor L1210/2 generated detectable K7L-insensitive variant cells during long-term (14-month) maintenance. All of the ten subclones of L1210/7 which were obtained 7 or 11 months after the initial cloning of L1210/7 were K7L sensitive, and not all the subclones generated K7L-insensitive variants in 1-2 months of maintenance after recloning. However, all of the subclones of L1210/7 which were maintained for 7 months generated antigen loss variants. All eight clone cells obtained from original L1210 and K7L-insensitive L1210 expressed H-2Kd and H-2Dd antigens detected by H-2Kd or Dd-specific cytotoxic T-lymphocyte clones or monoclonal antibodies. These results suggest that the antigen loss variants arise in originally K7L-sensitive L1210 clones at different times after cloning, and the probability of generation of the variants is clonally determined. The antigen loss variants seem to be generated by rare (once per 1 to 2 months or less frequent) chance with unproportionally rapid growth rather than by more frequent development for simple accumulation. The ratio of K7L-insensitive variant cells to total L1210/7 cells did not increase progressively during long-term (13 months or more) maintenance in vivo or in vitro and was always below 0.1%. It was suggested that the population size of antigen loss variants was controlled biphasically.


Assuntos
Variação Antigênica , Antígenos de Neoplasias/análise , Leucemia L1210/imunologia , Linfócitos T/imunologia , Animais , Células Clonais , Citotoxicidade Imunológica , Feminino , Antígenos H-2/análise , Leucemia L1210/genética , Camundongos , Camundongos Endogâmicos , Linfócitos T/ultraestrutura
20.
Cancer Res ; 50(22): 7198-202, 1990 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-1699657

RESUMO

The effect of recombinant human granulocyte colony-stimulating factor (G-CSF) on DNA topoisomerase II (topo II) expression was studied in two human acute myelogenous leukemia cell lines, NKM-1 and NOMO-1, which express G-CSF receptor and proliferate in response to exogenous G-CSF. Northern blot analysis revealed that the level of topo II mRNA in 16-h stimulated cells in serum-free medium with G-CSF (10 ng/ml) was approximately 2-fold higher than that in cells without G-CSF. Enhanced topo II mRNA expression was detectable within 3 h after the addition of G-CSF. Topo II activity in crude nuclear extracts from 16-h G-CSF-stimulated cells was also found to be approximately 2-fold greater than that from unstimulated cells. According to in vitro cytotoxic assay, the sensitivity of G-CSF-stimulated cells to intercalating (daunorubicin) and nonintercalating (etoposide) topo II-targeting drugs increased significantly, whereas no enhancement of sensitivity was observed with an alkylating agent (4-hydroperoxycyclophosphamide). The augmented drug sensitivity observed was not due to the increased level of drug transport, as suggested by the similar extent of [3H]etoposide uptake between G-CSF-stimulated and unstimulated cells. By measuring the topo II mRNA and the cytotoxicity of the above mentioned drugs, we obtained essentially the same results in G-CSF-responsive leukemia cells isolated from three acute myeloblastic leukemia patients, as observed in the cultured cell lines. These findings strongly suggest that the sensitivity to "topo II-targeting drugs" could be augmented by exogenous G-CSF through elevated topo II activity in G-CSF-responsive leukemia cells.


Assuntos
DNA Topoisomerases Tipo II/genética , Fator Estimulador de Colônias de Granulócitos/farmacologia , Northern Blotting , Ciclofosfamida/análogos & derivados , Ciclofosfamida/toxicidade , DNA Topoisomerases Tipo II/metabolismo , Daunorrubicina/toxicidade , Relação Dose-Resposta a Droga , Etoposídeo/metabolismo , Etoposídeo/toxicidade , Expressão Gênica/efeitos dos fármacos , Humanos , Leucemia Mieloide Aguda/genética , RNA Mensageiro/genética , RNA Neoplásico/genética , Proteínas Recombinantes , Células Tumorais Cultivadas
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