Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 251
Filtrar
Más filtros

Bases de datos
País/Región como asunto
Tipo del documento
Intervalo de año de publicación
1.
Nature ; 604(7906): 525-533, 2022 04.
Artículo en Inglés | MEDLINE | ID: mdl-35388223

RESUMEN

Over the past few decades, neuroimaging has become a ubiquitous tool in basic research and clinical studies of the human brain. However, no reference standards currently exist to quantify individual differences in neuroimaging metrics over time, in contrast to growth charts for anthropometric traits such as height and weight1. Here we assemble an interactive open resource to benchmark brain morphology derived from any current or future sample of MRI data ( http://www.brainchart.io/ ). With the goal of basing these reference charts on the largest and most inclusive dataset available, acknowledging limitations due to known biases of MRI studies relative to the diversity of the global population, we aggregated 123,984 MRI scans, across more than 100 primary studies, from 101,457 human participants between 115 days post-conception to 100 years of age. MRI metrics were quantified by centile scores, relative to non-linear trajectories2 of brain structural changes, and rates of change, over the lifespan. Brain charts identified previously unreported neurodevelopmental milestones3, showed high stability of individuals across longitudinal assessments, and demonstrated robustness to technical and methodological differences between primary studies. Centile scores showed increased heritability compared with non-centiled MRI phenotypes, and provided a standardized measure of atypical brain structure that revealed patterns of neuroanatomical variation across neurological and psychiatric disorders. In summary, brain charts are an essential step towards robust quantification of individual variation benchmarked to normative trajectories in multiple, commonly used neuroimaging phenotypes.


Asunto(s)
Encéfalo , Longevidad , Estatura , Encéfalo/anatomía & histología , Humanos , Imagen por Resonancia Magnética/métodos , Neuroimagen
3.
Curr Microbiol ; 70(3): 436-40, 2015 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-25447271

RESUMEN

The DiversiLab™ rep-PCR system was used to amplify DNA regions of 28 well-characterized Escherichia coli O104 strains to generate a digital DNA fingerprint profile for strain differentiation. E. coli O104 strains from human stools and other sources were examined. The results indicate that this system can cluster similar O104 strains rapidly.


Asunto(s)
ADN Bacteriano , Reacción en Cadena de la Polimerasa , Secuencias Repetitivas de Ácidos Nucleicos , Escherichia coli Shiga-Toxigénica/clasificación , Escherichia coli Shiga-Toxigénica/genética , Análisis por Conglomerados , Microbiología Ambiental , Infecciones por Escherichia coli/microbiología , Humanos
4.
Minerva Urol Nefrol ; 64(2): 97-122, 2012 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-22617305

RESUMEN

The surgical treatment of prostate cancer has evolved considerably since it was first described in 1905. With the introduction of a robotic, surgical-assist device, minimally invasive techniques for prostate removal have been increasingly utilized throughout the world. Currently, there is a large body of literature suggesting that robotic-assisted laparoscopic prostatectomy is associated with certain improved perioperative and postoperative outcomes and similar cancer control rates compared to open radical prostatectomy. The goal of this review is to objectively evaluate and describe the current state-of-the-art in surgical technique, perioperative and long-term outcomes, complications and the future of robotic-assisted laparoscopic radical prostatectomy.


Asunto(s)
Laparoscopía , Prostatectomía/instrumentación , Prostatectomía/tendencias , Neoplasias de la Próstata/cirugía , Robótica , Ensayos Clínicos como Asunto , Medicina Basada en la Evidencia , Humanos , Tiempo de Internación , Masculino , Prostatectomía/métodos , Neoplasias de la Próstata/patología , Calidad de Vida , Medición de Riesgo , Resultado del Tratamiento , Incontinencia Urinaria/etiología , Incontinencia Urinaria/prevención & control
5.
J Econ Entomol ; 105(6): 1988-97, 2012 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-23356063

RESUMEN

Before embarking on the 5-10 yr effort it can take to transfer plant resistance (R) genes to adapted crop cultivars, a question must be asked: is the pest a sufficient threat to warrant this effort? We used the recently discovered female-produced sex pheromone of the Hessian fly, Mayetiola destructor (Say) (Diptera: Cecidomyiidae),to explore this question for populations in the Upper Great Plains. Methods for pheromone trapping were established and trapping data were used to explore geographic distribution, phenology, and density. The pheromone lure remained attractive for up to 10 d and only attracted male Hessian flies. Traps placed within the crop canopy caught flies but traps placed above the crop canopy did not. Hessian flies were trapped throughout North Dakota starting in the spring and continuing through the summer and autumn. Densities were low in the spring but increased greatly during the early part of the summer, with peak adult emergence taking place at a time (July/August) when spring wheat was being harvested and winter wheat had not yet been planted. In the autumn, adults were found at a time when winter wheat seedlings are growing. The discovery of flies on Conservation Reserve Program land supports the idea that pasture grasses serve as alternate hosts. We conclude that the Hessian fly is a risk to wheat in the Upper Great Plains and predict that global warming and the increasing cultivation of winter wheat will add to this risk.


Asunto(s)
Dípteros/fisiología , Atractivos Sexuales , Triticum/parasitología , Animales , Femenino , Herbivoria , Masculino , North Dakota , Tumores de Planta/parasitología , Estaciones del Año
6.
J Econ Entomol ; 104(3): 1055-64, 2011 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-21735929

RESUMEN

We studied whether adaptation of the Hessian fly, Mayetiola destructor (Say) (Diptera: Cecidomyiidae), to plant resistance incurs fitness costs. In this gene-for-gene interaction, adaptation to a single H resistance gene occurs via loss of a single effector encoded by an Avirulence gene. By losing the effector, the adapted larva now survives on the H gene plant, presumably because it evades the plant's H gene-mediated surveillance system. The problem is the Hessian fly larva needs its effectors for colonization. Thus, for adapted individuals, there may be a cost for losing the effector, with this then creating a trade-off between surviving on H-resistant plants and growing on plants that lack H genes. In two different tests, we used wheat lacking H genes to compare the survival and growth of a nonadapted strain to two H-adapted strains. The two adapted strains differed in that one had been selected for adaptation to H9, whereas the other strain had been selected for adaptation to H13. Tests showed that two H-adapted strains were similar to the nonadapted strain in egg-to-adult survival but that they differed in producing adults with smaller wings. By using known relationships between wing length and reproductive potential, we found that losses in wing length underestimate losses in reproductive potential. For example, H9- and H13-adapted females had 9 and 3% wing losses, respectively, but they were estimated to have 32 and 12% losses in egg production. Fitness costs of adaptation will be investigated further via selection experiments comparing Avirulence allele frequencies for Hessian fly populations exposed or not exposed to H genes.


Asunto(s)
Dípteros/genética , Triticum/genética , Animales , Dípteros/crecimiento & desarrollo , Dípteros/patogenicidad , Dípteros/fisiología , Femenino , Genes de Insecto , Genes de Plantas , Aptitud Genética , Variación Genética , Genotipo , Larva/genética , Larva/crecimiento & desarrollo , Larva/fisiología , Masculino , Hojas de la Planta/crecimiento & desarrollo , Densidad de Población , Reproducción , Triticum/inmunología
7.
Phytopathology ; 100(3): 279-89, 2010 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-20128702

RESUMEN

Features shared by host-specific phytophagous insects and biotrophic plant pathogens include gene-for-gene interactions and the ability to induce susceptibility in plants. The Hessian fly shows both. To protect against Hessian fly, grasses have H genes. Avirulent larvae die on H-gene-containing resistant plants but the cause of death is not known. Imaging techniques were used to examine epidermal cells at larval attack sites, comparing four resistant wheat genotypes (H6, H9, H13, and H26) to a susceptible genotype. Present in both resistant and susceptible plants attacked by larvae were small holes in the tangential cell wall, with the size of the holes (0.1 microm in diameter) matching that of the larval mandible. Absent from attacked resistant plants were signs of induced susceptibility, including nutritive tissue and ruptured cell walls. Present in attacked resistant plants were signs of induced resistance, including cell death and fortification of the cell wall. Both presumably limit larval access to food, because the larva feeds on the leaf surface by sucking up liquids released from ruptured cells. Resistance was associated with several subcellular responses, including elaboration of the endoplasmic reticulum-Golgi complex and associated vesicles. Similar responses are observed in plant resistance to fungi, suggesting that "vesicle-associated penetration resistance" also functions against insects.


Asunto(s)
Dípteros/fisiología , Enfermedades de las Plantas/microbiología , Enfermedades de las Plantas/parasitología , Triticum/genética , Triticum/parasitología , Animales , Genotipo , Larva/fisiología , Enfermedades de las Plantas/genética , Hojas de la Planta/parasitología , Hojas de la Planta/ultraestructura
8.
Clin Exp Dermatol ; 34(3): 333-6, 2009 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-19040523

RESUMEN

Multinucleate cell angiohistiocytoma (MCAH) is an uncommon benign soft-tissue lesion with characteristic histological and immunohistochemical features. It is unclear if it represents a benign neoplasm or a reactive/inflammatory process. The overwhelming majority of these tumors have been described on cutaneous surfaces. One case has been reported on the skin of the lip. This is the first documentation of MCAH within the oral cavity. The clinical presentation, histopathological features and immunohistochemical reactivity pattern are described. Because of the benign nature of this lesion, a conservative approach is recommended in its management. Surgical excision appears to be curative.


Asunto(s)
Histiocitoma/patología , Neoplasias de la Boca/patología , Adulto , Núcleo Celular/patología , Células Dendríticas/patología , Caries Dental/complicaciones , Histiocitoma/etiología , Humanos , Masculino , Mucosa Bucal/patología , Neoplasias de la Boca/etiología
9.
Med Hypotheses ; 70(6): 1193-6, 2008.
Artículo en Inglés | MEDLINE | ID: mdl-18364249

RESUMEN

We briefly review some implications for therapeutic resistance in solid cancers that could be associated with more alkaline intra-tumor micro-regions reported to exist. Regions of increased alkalinity may provide a proliferative advantage for cancer "stem" or other cells, as more alkaline intra- and extra-cellular environments often are associated with increased cellular proliferation. If increased alkalinity is present in aerobic, but perhaps more especially in hypoxic micro-environments, proliferation of cells less susceptible to programmed cell death, with reduced expression of multi-drug resistance membrane proteins and altered efficacy of some therapeutic drugs should develop. Such cells are also more likely to generate aberrant clones resistant to additional therapy, particularly those dependent upon mitochondrial oxidative processes with greater generation of free radicals, compared to cells reliant on anaerobic glycolysis for metabolic energy. The interplay between alkalinity and normoxia, hypoxia or anoxia may differentially advantage some cancer "stem" cells.


Asunto(s)
Resistencia a Múltiples Medicamentos , Resistencia a Antineoplásicos , Modelos Biológicos , Neoplasias/tratamiento farmacológico , Neoplasias/metabolismo , Animales , Antineoplásicos/uso terapéutico , Apoptosis/efectos de los fármacos , Hipoxia de la Célula/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Respiración de la Célula/efectos de los fármacos , Células Clonales/efectos de los fármacos , Glucólisis/efectos de los fármacos , Humanos , Concentración de Iones de Hidrógeno , Hipoxia/metabolismo , Proteínas de la Membrana/genética , Proteínas de la Membrana/metabolismo , Mitocondrias/efectos de los fármacos , Neoplasias/patología , Células Madre Neoplásicas/efectos de los fármacos
10.
Anticancer Res ; 27(4B): 2141-53, 2007.
Artículo en Inglés | MEDLINE | ID: mdl-17695497

RESUMEN

Reasons for the lodgment of metastases from several types of solid cancer at apparently non-random sites have not been established. Recently, a group of genes expressed in human fibroblasts obtained from different anatomic locations was implicated in "positional" genomic information. Essentially, a Cartesian coordinate system identifying fibroblasts originally resident at anterior or more posterior, proximal or distal and dermal or non-dermal (heart, lung, etc.) locations was proposed. The determinants used for these identifications included HOX genes, central to embryonic segmental development, some of which are expressed in differentiated, post-embryonic cells. To the extent that HOX or other homeobox genes are expressed in ectodermal, mesodermal or endodermally-derived, malignantly transformed cells, they might contribute "positional" information to nidation of specific malignant clones at non-random sites. As understood in the past, interdiction of HOX or homeobox-related gene expression might reduce the probability of cancer cell implantation or alter their destinations in complex ways. Ideally, by interfering with HOX or other homeobox gene-related expression of antigenic determinants potentially contributing to their "homing" and nidation, reduced implantation of circulating cancer cells could render them more susceptible to systemic chemotherapy or immunotherapy, as demonstrated in mice. Furthermore, HOX or other homeobox genes or their products could provide novel intra- or extracellular targets for therapy.


Asunto(s)
Genes Homeobox , Neoplasias/genética , Neoplasias/patología , Expresión Génica , Humanos , Metástasis de la Neoplasia
11.
Med Hypotheses ; 68(1): 166-8, 2007.
Artículo en Inglés | MEDLINE | ID: mdl-16934948

RESUMEN

Resistance to various cancer therapies with survival or recurrence of a malignancy has been ascribed to the inability to "kill" hypoxic cancer cells. The reported resistance of cancer "stem" cells has also been proposed as a major reason for this outcome. In planning therapy, it should be important to know whether these two categories "overlap": do "hypoxic" cells subsume cancer "stem" cells; alternately, are "stem" cells somewhat hypoxic or are these categories distinct? If the former is true and these categories overlap, to what extent do their properties share biochemical elements in common; if the latter is the case, should both properties be "targeted" independently? The inability of a proposed therapy to suppress these foci of resistance could preclude a successful outcome. Results from pre-clinical and clinical laboratory determination of the stem cell/hypoxic cell response may reflect the likely outcome of the proposed clinical treatment.


Asunto(s)
Transformación Celular Neoplásica/patología , Modelos Biológicos , Neoplasias/irrigación sanguínea , Neoplasias/patología , Neovascularización Patológica/patología , Células Madre/patología , Animales , Diferenciación Celular , Hipoxia de la Célula/inmunología , Humanos , Neoplasias/cirugía
12.
Anticancer Res ; 26(6B): 4155-62, 2006.
Artículo en Inglés | MEDLINE | ID: mdl-17201127

RESUMEN

BACKGROUND: Hypoxic cancer cells located beyond the diffusion path of sufficient oxygen are considered a nidus of therapeutic failure. Due to the dependence of many malignantly transformed cells on glycolysis for metabolic energy, inhibiting this and other sources of energy should seriously reduce cell viability and proliferation, additively or even synergistically. MATERIALS AND METHODS: To try and duplicate in vitro some of the features of in vivo cancer cells likely to resist therapy, HeLa cells were incubated with sub-lethal concentrations of 2-deoxy-D-glucose under aerobic, hypoxic or virtually anoxic conditions, verified by increased synthesis of Hif-1alpha, and their replication and survival determined. MK 886, an inhibitor of mitochondrial function was used to estimate participation of that organelle in energy metabolism. RESULTS: Culture of cervical cancer-derived HeLa cells with 2-deoxy-D-glucose under these restrictive conditions did not reduce their proliferation or viability to the expected extent. Their surprisingly robust survival included the anticipated increase in dependence upon glycolysis and implied a likely entrainment of other constitutive and possibly facultative energy sources and pathways. Increased synthesis of Hif-1alpha, increased binding to its consensus sequence and reduced inhibition from MK 886 in cells under oxygen-deficient environments confirmed the presence of restrictive conditions. CONCLUSION: Efforts to suppress HeLa cell survival by reducing glucose consumption and metabolic energy from ambient oxygen may require inhibition of multiple energy sources, possibly not all of them identified. In vitro assessment of agents directed against sources of metabolic energy or of other therapeutic agents against these or additional potential targets should include studies under hypoxia and relative anoxia. In this way, the possible responses of in vivo hypoxic or anoxic cancer cells believed to contribute to therapeutic failure may be estimated.


Asunto(s)
Hipoxia de la Célula , Proliferación Celular/efectos de los fármacos , Desoxiglucosa/farmacología , Neoplasias/patología , Células HeLa , Humanos , Subunidad alfa del Factor 1 Inducible por Hipoxia/metabolismo , Mitocondrias/efectos de los fármacos , Mitocondrias/fisiología , Neoplasias/metabolismo
13.
J Natl Cancer Inst ; 82(4): 286-90, 1990 Feb 21.
Artículo en Inglés | MEDLINE | ID: mdl-2299677

RESUMEN

We examined the relation between central body fat distribution and breast cancer in a prospective cohort of women who participated in the Framingham Study. At the baseline examination in 1948, a total of 2,201 women aged 30-62 years were analyzed. An index of central to peripheral body fat (the central adiposity ratio) was calculated from the sum of the trunkal skinfolds (chest, subscapular, and abdominal) divided by the sum of the extremity skinfolds (triceps and thigh). These skinfolds were measured at the fourth examination in 1954. The cohort was followed for up to 28 years and yielded 106 cases of breast cancer. When divided into quartiles based on the central adiposity ratio, only women in the fourth quartile (those with the highest central to peripheral body fat distribution) demonstrated an increased risk for breast cancer. The age- and adiposity-adjusted relative risk estimate for having an increased central adiposity ratio (fourth quartile) compared to lower central adiposity ratios was 1.8 (95% confidence interval, 1.2-2.6). Adjustment for potential confounders of height, parity, and education did not appreciably alter this estimate (1.7, 1.1-2.5). There was no association between degree of adiposity, as measured by the sum of the five skinfolds or by body mass index (weight in kg divided by height in m2), and subsequent breast cancer. The results of this study suggest that increased central to peripheral body fat distribution predicts breast cancer risk independently of the degree of adiposity and may be a more specific marker of a premalignant hormonal pattern than degree of adiposity.


Asunto(s)
Neoplasias de la Mama/epidemiología , Obesidad/complicaciones , Adulto , Factores de Edad , Índice de Masa Corporal , Neoplasias de la Mama/complicaciones , Femenino , Humanos , Menopausia , Persona de Mediana Edad , Estudios Prospectivos , Factores de Riesgo , Grosor de los Pliegues Cutáneos
14.
J Natl Cancer Inst ; 81(1): 31-5, 1989 Jan 04.
Artículo en Inglés | MEDLINE | ID: mdl-2908919

RESUMEN

We studied the relation between alcohol consumption and breast cancer among women in the Framingham Heart Study cohort. A total of 2,636 women aged 31-64 years provided information on alcohol consumption at the second biennial examination. They were followed for up to 32 years; during this period, breast cancer was diagnosed in 143 of these women. Alcohol intake was also assessed at 10 and 20 years of follow-up and every 2 years thereafter. In analyses using only baseline alcohol intake, the multiple risk factor-adjusted relative risk (RR) estimate of breast cancer for any drinking, compared with nondrinking, was 0.8 [95% confidence interval (CI), 0.5-1.1]. For three levels of alcohol intake (0.1-1.4 g/day, 1.5-4.9 g/day, and greater than or equal to 5.0 g/day), the baseline analyses yielded RRs (vs. nondrinking) of 1.0 (CI, 0.6-1.5), 0.7 (CI, 0.4-1.1), and 0.6 (CI, 0.4-1.0), respectively. In analyses incorporating repeated measures of alcohol, the comparable RRs were 0.9 (CI, 0.6-1.2) for any drinking (vs. nondrinking) and 0.7 (CI, 0.4-1.4), 1.1 (CI, 0.7-1.8), and 0.8 (CI, 0.5-1.2), respectively, for the three levels of intake (vs. nondrinking). Alcohol consumption was not associated with an increased risk of breast cancer in this cohort.


Asunto(s)
Consumo de Bebidas Alcohólicas , Neoplasias de la Mama/etiología , Adulto , Femenino , Estudios de Seguimiento , Humanos , Persona de Mediana Edad , Riesgo
15.
Cancer Res ; 49(5): 1138-42, 1989 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-2492901

RESUMEN

When replicating U937 cells were incubated with up to 80 microM concentrations of the in vitro inhibitor of eicosanoid biosynthesis, 5,8,11,14-eicosatetraynoic acid (ETYA), DNA synthesis measured by labeling with [3H]thymidine was inhibited in a concentration-dependent manner. No reduction in cellular viability occurred, as judged by exclusion of trypan blue, unaltered release of 51Cr-labeled proteins, and the reversibility of inhibition after incubation for 72 h with ETYA. Neither indomethacin nor acetylsalicylic acid, inhibitors of cyclooxygenase, altered DNA synthesis in control or ETYA-inhibited cells, excluding participation of the products of this enzyme in the inhibition of DNA synthesis. Incubation of inhibited cells with extracts prepared from log-phase media partially reversed the inhibition of DNA synthesis. Addition of leukotriene B4 or D4 at 10(-7) to 10(-8) M did not reverse ETYA-induced inhibition of DNA synthesis, nor did the addition of a series of long chain fatty acids, including arachidonic acid. However, leukotriene C4 at 10(-7) M partially reversed the inhibition of DNA synthesis. Extracts of media from log-phase cells were shown by high-pressure liquid chromatography to contain leukotriene C4, and synthesis of this compound was inhibited by ETYA, as judged by measurement of UV absorbance and radioactivity. Additional inhibitors of eicosanoid metabolism including nordihydroguaiaretic acid and esculetin also suppressed DNA synthesis in U937, K562, and prostate PC3 cells, without altered cellular viability; the effect is not limited to lymphohematopoietic cells or to a single inhibitor of arachidonic acid metabolism. Suppression of U937 DNA and eicosanoid synthesis by ETYA and the partial reversal of DNA synthesis by leukotriene C4 suggest that in these cells eicosanoids may modulate DNA synthesis. Other possible consequences of incubating cells with ETYA including creation of arachidonic acid-deficient membranes, and even incorporation of the agent into membrane phospholipids, may also contribute to the reversible inhibition of DNA synthesis.


Asunto(s)
Ácido 5,8,11,14-Eicosatetrainoico/farmacología , Ácidos Araquidónicos/metabolismo , ADN/biosíntesis , Ácidos Grasos Insaturados/farmacología , SRS-A/farmacología , Ácido Araquidónico , Línea Celular Transformada , Humanos
16.
Cancer Res ; 36(6): 1935-40, 1976 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-1268848

RESUMEN

Female C57BL/J6 mice pretreated with dehistonized ependymoblastoma chromatin rejected 5 x 10(4) or 10(5) s.c.-implanted syngeneic ependymoblastoma cells. Control mice that received Freund's adjuvant containing dehistonized chromatin from normal mouse brain developed palpable tumor nodules in 90% and 35 to 45% of the animals, respectively. Increased binding of spleen lymphocytes from mice pretreated with dehistonized tumor chromatin to Sepharose 4B coupled with components of dehistonized tumor chromatin was observed. This provides initial evidence for the presence of "committed" lymphocytes in mice pretreated with dehistonized chromatin from this mouse ependymoblastoma.


Asunto(s)
Cromatina/inmunología , Ependimoma/inmunología , Rechazo de Injerto , Inmunización , Animales , Cromatina/aislamiento & purificación , Ependimoma/análisis , Femenino , Inmunidad Celular , Linfocitos/inmunología , Ratones , Ratones Endogámicos C57BL , Trasplante de Neoplasias , Neoplasias Experimentales/inmunología , Bazo/inmunología
17.
Cancer Res ; 50(12): 3610-3, 1990 Jun 15.
Artículo en Inglés | MEDLINE | ID: mdl-2340509

RESUMEN

We examined the relation between self-reported physical activity and large bowel cancer in a prospective cohort of men and women who participated in the Framingham Study. Self-assessments of physical activity were available from the fourth biennial examination on a total of 1906 men and 2308 women aged 30 to 62 yr in 1954. The cohort was followed for up to 28 yr and yielded 152 cases (73 men, 79 women) of large bowel cancer. Inactivity was associated with an increased risk of large bowel cancer among men but not among women. The relative risk estimates for large bowel cancer among men in the middle and lowest tertiles of a physical activity index (compared with the highest tertile) were 1.4 (95% confidence intervals, 0.8-2.6) and 1.8 (1.0-3.2), respectively. Among women the comparable estimates were 1.2 (0.7-2.1) and 1.1 (0.6-1.8), respectively. These findings were unchanged after adjustment for body mass index, serum cholesterol, alcohol, and other potentially confounding variables. The narrow range of physical activity and the minimal heavy activity reported by women in this cohort may have limited our ability to detect an association between physical activity and large bowel cancer among women.


Asunto(s)
Ejercicio Físico , Neoplasias Intestinales/epidemiología , Adulto , Factores de Edad , Escolaridad , Femenino , Humanos , Intestino Grueso , Estilo de Vida , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Factores de Riesgo , Factores Sexuales
18.
Biochim Biophys Acta ; 383(1): 56-66, 1975 Feb 24.
Artículo en Inglés | MEDLINE | ID: mdl-164243

RESUMEN

Mammary gland nuclear extracts from late-pregnant Wistar or Sprague-Dwaley rats, analyzed by DEAE-Sephadex chromatography, were found to contain DNA-dependent RNA polymerases, cyclic nucleotide-binding proteins, and cyclic AMP-independent protein kinases. 1. The fractions from chromatographed nuclear extracts which contained nucleolar enzymes or nucleoplasmic enzyme II, bound radioactive cyclic AMP and cyclic GMP. Other fractions also bound cyclic nucleotides, some preferentially associating with one or the other compound. 2. Cyclic AMP increased the amount of RNA formed by several alpha-amanitin-insensitive fractions containing nucleolar enzymes. 3. Cyclic AMP reduced the amount of RNA formed by column fractions which included nucleoplasmic enzyme II. 4. Cyclic GMP increased the amount of RNA synthesized by column fractions containing enzyme II. 5. Two major cyclic AMP-independent protein kinases which did not elute with enzymes Ib and II, and several minor protein kinases were present. These findings may have important implications for understanding the proximate control of transcription. A relationship between them is not established, but is under study.


Asunto(s)
Núcleo Celular/enzimología , ARN Polimerasas Dirigidas por ADN/metabolismo , Glándulas Mamarias Animales/enzimología , Amanitinas/farmacología , Animales , Nucléolo Celular/enzimología , Cromatografía en Gel , AMP Cíclico/farmacología , GMP Cíclico/farmacología , ARN Polimerasas Dirigidas por ADN/aislamiento & purificación , Femenino , Embarazo , Unión Proteica , Proteínas Quinasas/metabolismo , Ratas
19.
Biochim Biophys Acta ; 959(3): 296-304, 1988 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-3128336

RESUMEN

Phorbol esters induce morphologic and biochemical differentiation in U937 cells, a monocyte/macrophage-like line derived from a human histiocytic lymphoma. We are interested in the phorbol ester-stimulated release of arachidonic acid from cellular membranes and the subsequent synthesis of eicosanoids, as it may prove to correlate with the induced cellular differentiation. Undifferentiated log-phase U937 cells released little recently incorporated [3H]arachidonic acid, but phorbol 12-myristate 13-acetate increased its apparent rate of release to that of cells differentiated by exposure to phorbol myristate acetate for 3 days. Exposure of washed differentiated cells immediately prelabelled with [3H]arachidonic acid to additional phorbol myristate acetate did not augment the release of [3H]arachidonic acid. The basal release of nonradioactive fatty acids from differentiated cells was 5-10 times that of undifferentiated cells, and phorbol myristate acetate increased their release from both types of cell 2- to 3-fold. Differentiated cells immediately prelabelled with [3H]arachidonic acid exhibited greater incorporation into phosphatidylinositol and phosphatidylcholine, and contained more radioactive free arachidonic acid, compared with undifferentiated cells. Undifferentiated cells contained more radioactivity in phosphatidylserine, phosphatidylethanolamine and neutral lipids. Phorbol myristate acetate caused differentiated cells to release [3H]arachidonic acid from phosphatidylinositol, phosphatidylserine, phosphatidylcholine and phosphatidylethanolamine, but release from neutral lipids was reduced, and the content of [3H]arachidonic acid increased. In undifferentiated cells incubated with phorbol myristate acetate, radioactivity associated with phosphatidylserine, phosphatidylethanolamine and neutral lipid was reduced and [3H]arachidonic acid was unchanged. Synthesis of cyclooxygenase products exceeded that of lipoxygenase products in both differentiated and undifferentiated cells. Phorbol myristate acetate increased the synthesis of both types of product, cyclooxygenase-dependent more than lipoxygenase-dependent, especially in differentiated cells. The biological significance of these changes in lipid metabolism that accompany phorbol myristate acetate-induced differentiation are yet to be established.


Asunto(s)
Ácidos Araquidónicos/metabolismo , Ácidos Eicosanoicos/biosíntesis , Metabolismo de los Lípidos , Linfoma de Células B Grandes Difuso/metabolismo , Fosfolípidos/metabolismo , Acetato de Tetradecanoilforbol/farmacología , Ácido Araquidónico , Diferenciación Celular , Línea Celular/efectos de los fármacos , Cromatografía de Gases , Cromatografía Líquida de Alta Presión , Cromatografía en Capa Delgada , Ácidos Grasos no Esterificados/metabolismo , Humanos , Microscopía Electrónica de Rastreo
20.
Biochim Biophys Acta ; 1105(2): 285-90, 1992 Apr 13.
Artículo en Inglés | MEDLINE | ID: mdl-1586665

RESUMEN

ETYA (5,8,11,14-eicosatetraynoic acid), a competitive analogue of arachidonic acid (AA), inhibits the proliferation of U937 (human monoblastoid) and PC3 (human prostate) cancer cells, without the overt cytotoxicity associated with AA at similar concentrations. The mechanism of inhibition is not established. ETYA at 100 microM acutely increased whole cell and isolated microsomal membrane fluidity of both cell lines to a greater extent than arachidonic acid. PC3 cells incubated with ETYA for 72 h evidenced increased membrane fluidity. This was measured by the fluorescence polarization parameter, R, using the probes TMA-DPH and DPH for whole cell and isolated membrane fractions, respectively. Compared with whole cells, isolated membranes yielded a 10-20-fold increase in fluorescence intensity. The intramolecular conformational profiles of both ETYA and AA were explored using a combination of molecular mechanics energy minimization and molecular dynamics simulation. While it is possible that not all of the low energy conformational states of either molecule were sampled, the large number of low-energy conformers determined for ETYA correspond to kink deformed conformers relative to the family of AA conformers. These kinks make the molecular cross sections of ETYA larger than AA and arise from the four alkyne bond geometries. This structural finding is consistent with ETYA's greater effect on membrane fluidity. Dissociation between the extent of change in membrane fluidity due to ETYA or AA and inhibition of DNA synthesis can suggest that either (A) increased fluidity and inhibition of DNA synthesis are independent, or as we believe more likely, (B) greater membrane fluidity evoked by ETYA is important for inhibiting DNA synthesis, while changes induced by AA are insufficient or differ qualitatively from those required to initiate and sustain these nonlethal events.


Asunto(s)
Ácidos Araquidónicos/farmacología , Ácidos Grasos Insaturados/farmacología , Fluidez de la Membrana/efectos de los fármacos , Ácidos Araquidónicos/química , Membrana Celular/ultraestructura , Simulación por Computador , Ácidos Grasos Insaturados/química , Polarización de Fluorescencia , Humanos , Microscopía Electrónica , Modelos Moleculares , Células Tumorales Cultivadas
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA