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1.
Br J Cancer ; 93(3): 364-71, 2005 Aug 08.
Artículo en Inglés | MEDLINE | ID: mdl-16079783

RESUMEN

Reproductive factors are associated with reduced risk of breast cancer, but less is known about whether there is differential protection against subtypes of breast cancer. Assuming reproductive factors act through hormonal mechanisms they should protect predominantly against cancers expressing oestrogen (ER) and progesterone (PR) receptors. We examined the effect of reproductive factors on subgroups of tumours defined by hormone receptor status as well as histology using data from the NIHCD Women's Contraceptive and Reproductive Experiences (CARE) Study, a multicenter case-control study of breast cancer. We estimated odds ratios (ORs) and 95% confidence intervals (CIs) as measures of relative risk using multivariate unconditional logistic regression methods. Multiparity and early age at first birth were associated with reduced relative risk of ER + PR + tumours (P for trend=0.0001 and 0.01, respectively), but not of ER - PR - tumours (P for trend=0.27 and 0.85), whereas duration of breastfeeding was associated with lower relative risk of both receptor-positive (P for trend=0.0002) and receptor-negative tumours (P=0.0004). Our results were consistent across subgroups of women based on age and ethnicity. We found few significant differences by histologic subtype, although the strongest protective effect of multiparity was seen for mixed ductolobular tumours. Our results indicate that parity and age at first birth are associated with reduced risk of receptor-positive tumours only, while lactation is associated with reduced risk of both receptor-positive and -negative tumours. This suggests that parity and lactation act through different mechanisms. This study also suggests that reproductive factors have similar protective effects on breast tumours of lobular and ductal origin.


Asunto(s)
Neoplasias de la Mama/epidemiología , Estudios de Casos y Controles , Receptores de Estrógenos , Receptores de Progesterona , Adulto , Factores de Edad , Lactancia Materna , Neoplasias de la Mama/metabolismo , Femenino , Número de Embarazos , Humanos , Persona de Mediana Edad , Paridad , Factores de Riesgo , Factores de Tiempo
3.
N Engl J Med ; 343(23): 1681-7, 2000 Dec 07.
Artículo en Inglés | MEDLINE | ID: mdl-11106717

RESUMEN

BACKGROUND: The existence of a post-tubal-ligation syndrome of menstrual abnormalities has been debated for decades. We used data from the U.S. Collaborative Review of Sterilization to determine whether the likelihood of persistent menstrual abnormalities was greater among women who had undergone tubal sterilization than among women who had not. METHODS: A total of 9514 women who underwent tubal sterilization and 573 women whose partners underwent vasectomy were followed in a multicenter, prospective cohort study for up to five years by means of annual telephone interviews. All women were asked the same questions about six characteristics of their menstrual cycles in the presterilization and follow-up interviews. Multiple logistic-regression analysis was used to assess the risk of persistent menstrual changes. RESULTS: The women who had undergone sterilization were no more likely than those who had not undergone the procedure to report persistent changes in intermenstrual bleeding or the length of the menstrual cycle. They were more likely to have decreases in the number of days of bleeding (odds ratio, 2.4; 95 percent confidence interval, 1.1 to 5.2), the amount of bleeding (odds ratio, 1.5; 95 percent confidence interval, 1.1 to 2.0), and menstrual pain (odds ratio, 1.3; 95 percent confidence interval, 1.0 to 1.8) and to have an increase in cycle irregularity (odds ratio, 1.6; 95 percent confidence interval, 1.1 to 2.3). Among women who had had very heavy bleeding at base line, women who had undergone sterilization were more likely than women who had not undergone the procedure to report decreased bleeding (45 percent vs. 33 percent, P=0.03). CONCLUSIONS: Women who have undergone tubal sterilization are no more likely than other women to have menstrual abnormalities.


Asunto(s)
Trastornos de la Menstruación/etiología , Esterilización Tubaria/efectos adversos , Adulto , Factores de Edad , Femenino , Humanos , Modelos Logísticos , Masculino , Menorragia/prevención & control , Estudios Prospectivos , Riesgo , Vasectomía
4.
Neuroimage ; 11(3): 188-202, 2000 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-10694461

RESUMEN

Three studies were carried out to assess the applicability of fMRI at 3.0 T to analysis of vibrotaction in humans. A novel piezoelectric device provided clean sinusoidal stimulation at 80 Hz, which was initially applied in separate runs within a scanning session to digits 2 and 5 of the left hand in eight subjects, using a birdcage RF (volume) coil. Significant clusters of activation were found in the primary somatosensory cortex (SI), the secondary somatosensory cortex (SII), subcentral gyrus, the precentral gyrus, posterior insula, posterior parietal regions (area 5), and the posterior cingulate. Digit separation in SI was possible in all subjects and the activation sites reflected the known lateral position of the representation of digit 2 relative to that of digit 5. A second study carried out in six additional subjects using a surface coil, replicated the main contralateral activation patterns detected in study one and further improved the discrimination of the digits in SI. Significant digit separation was also found in SII and in the posterior insula. A third study to investigate the frequency dependence of the response focused on the effect of an increase in vibrotactile frequency from 30 to 80 Hz, with both frequencies applied to digit 2 during the same scanning session in four new subjects. A significant increase in the number of pixels activated within both SII and the posterior insula was found, while the number of pixels activated in SI declined. No significant change in signal intensity with frequencies was found in any of the activated areas.


Asunto(s)
Mapeo Encefálico/métodos , Encéfalo/fisiología , Dedos/inervación , Imagen por Resonancia Magnética , Adulto , Estimulación Eléctrica , Femenino , Lateralidad Funcional , Humanos , Masculino , Valores de Referencia
5.
Brain Res ; 815(2): 326-36, 1999 Jan 09.
Artículo en Inglés | MEDLINE | ID: mdl-9878812

RESUMEN

Dense multichannel recordings of scalp electroencephalogram (EEG) were obtained in the vicinity of primary somatosensory cortex, time-locked to repetitive vibrotactile stimulation of sites on the right index finger of a single human subject. Frequency-domain analysis of cross-trial averages revealed prominent 'driving' responses in the EEG at the frequency of stimulation, which under specific stimulus conditions displayed pronounced changes in amplitude and topographic organization over brief (4 s) durations of stimulus exposure. The changes were systematic and physiologically coherent, evolving toward driving-response topographies observed in the same subject in conjunction with periodic microstimulation of single mechanoreceptive afferents whose receptive fields occupied corresponding positions on the digit. This dynamic process was orderly and reproducible, and could be controlled by manipulating factors such as the amplitude, frequency, and temporal spacing of the stimuli. The results are tentatively interpreted in light of a previously proposed neurophysiological model of stimulus-driven response plasticity in mammalian somatosensory cortex.


Asunto(s)
Electroencefalografía , Corteza Somatosensorial/fisiología , Mapeo Encefálico/métodos , Simulación por Computador , Electroencefalografía/métodos , Mano/fisiología , Humanos , Imagen por Resonancia Magnética , Masculino , Mecanorreceptores/fisiología , Modelos Neurológicos , Neuronas Aferentes/fisiología , Estimulación Física , Reproducibilidad de los Resultados , Vibración
6.
J Neurosci Methods ; 81(1-2): 121-9, 1998 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-9696317

RESUMEN

A new method of time-frequency analysis, based on the Matching Pursuit (MP) algorithm, was used to extract and quantify EEG 'driving' or frequency-following responses produced in human primary somatosensory cortex (SI) by 33 Hz vibrotactile stimulation of the right index fingertip in a single subject. EEG signals were recorded from a 5 x 5 array of electrodes centered over the left hand area, time-locked to repeated presentations of four vibratory stimulus amplitudes. The MP algorithm was used to decompose the edited and and filtered EEG signals into waveforms selected from a large and redundant dictionary. Statistical discrimination of the vibratory stimulus amplitudes was then readily achieved in terms of trial-by-trial measures of response amplitude constructed in automated fashion from the calculated MP parameters. The results were orderly and physiologically coherent, and potentially open the way to correlation of psychophysical magnitude estimates with measures of neurophysiological response on a trial-by-trial basis. The approach developed here appears well suited to detection and characterisation of time dependent or transient target signals embedded in a noisy background.


Asunto(s)
Algoritmos , Electroencefalografía/métodos , Tacto/fisiología , Vibración , Análisis de Varianza , Humanos , Modelos Neurológicos , Modelos Teóricos , Estimulación Física , Procesamiento de Señales Asistido por Computador , Factores de Tiempo
7.
J Neurophysiol ; 77(1): 137-44, 1997 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-9120554

RESUMEN

Dense multichannel recordings of scalp electroencephalogram were obtained in the vicinity of primary somatosensory cortex, time-locked to repetitive train microstimulation of single, physiologically characterized skin mechanoreceptive afferents in the median nerve of a single human subject. Frequency-domain analysis of cross-trial averages for fast-adapting type one and slowly adapting type one afferents revealed prominent, topographically organized "driving" responses in the electroencephalogram at the frequency of stimulation, which vanished under various statistical and experimental control conditions. The responses also exhibited systematic declines in amplitude both across and within trials, and orderly changes in scalp topography as a function of the location of afferents' receptive fields on the hand. The observed response properties are tentatively explained in terms of characteristics of the pattern of afferent drive impressed on the cortex by microstimulation.


Asunto(s)
Electroencefalografía , Mecanorreceptores/fisiología , Neuronas Aferentes/fisiología , Estimulación Eléctrica , Electrofisiología , Análisis de Fourier , Humanos , Microelectrodos , Piel/inervación , Corteza Somatosensorial/fisiología
8.
Exp Brain Res ; 109(3): 500-6, 1996 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-8817281

RESUMEN

Surface recordings made at the wrist during moderate vibrotactile stimulation of a digit display rhythmic activity at the frequency of the driving stimulus. This activity is abolished by local anesthesia of the stimulated digit and by substitution of the corresponding digit of the opposite hand with the recording geometry and the load on the stimulator unchanged. Several additional features of the response are similarly incompatible with an artifactual origin in properties of the stimulus motion or the associated electromagnetic field, but consistent with previous neurophysiological observations. The frequency-domain analysis extends readily to the single-trial level, making the technique potentially useful for a variety of basic research and clinical purposes.


Asunto(s)
Potenciales Evocados Somatosensoriales/fisiología , Neuronas Aferentes/fisiología , Tacto/fisiología , Vibración , Adulto , Artefactos , Femenino , Dedos/inervación , Dedos/fisiología , Humanos , Masculino , Persona de Mediana Edad , Proyectos Piloto , Desempeño Psicomotor/fisiología , Factores de Tiempo
9.
J Histochem Cytochem ; 41(9): 1441-6, 1993 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-8354884

RESUMEN

We describe the production of polyclonal chicken antibodies specific for bovine growth hormone (bGH) and prolactin (PRL). Antibodies were generated by immunization of laying hens with recombinant bGH (rbGH), pituitary derived bGH (pbGH), and ovine PRL (oPRL). After the lipoprotein fraction was removed by dextran sulfate precipitation the antibodies were isolated from the egg yolks by ammonium sulfate precipitation. Immunization with rbGH and oPRL generated large amounts of specific antibodies, as revealed by ELISA and Western blot analysis. Antibodies against pbGH showed pronounced crossreactions with oPRL. The antibodies against rbGH and oPRL were well suited for sensitive and specific labeling of the GH- and PRL-synthesizing cells in bovine pituitary glands by immunohistochemistry. In addition, a quick and sensitive procedure for demonstration of both bGH- and PRL-synthesizing cells in a single paraffin section by double immunohistochemistry is presented. The chicken anti-bGH antibodies showed excellent results in combination with rabbit anti-PRL antibodies. The main advantage of avian antibodies in double immunostaining methods is the lack of crossreactions between avian antibodies and mammalian immunoglobulins and receptors which bind to the crystalline fragment of mammalian immunoglobulins (Fc receptors).


Asunto(s)
Anticuerpos/análisis , Proteínas del Huevo/inmunología , Hormona del Crecimiento/análisis , Hipófisis/química , Prolactina/análisis , Animales , Anticuerpos/inmunología , Western Blotting , Bovinos , Pollos/inmunología , Yema de Huevo/inmunología , Electroforesis en Gel de Poliacrilamida , Ensayo de Inmunoadsorción Enzimática , Hormona del Crecimiento/inmunología , Inmunoglobulina G/análisis , Inmunoglobulina G/inmunología , Inmunohistoquímica/métodos , Hipófisis/citología , Hipófisis/inmunología , Prolactina/inmunología , Ovinos
10.
MMWR CDC Surveill Summ ; 42(1): 9-22, 1993 Mar 19.
Artículo en Inglés | MEDLINE | ID: mdl-8474428

RESUMEN

PROBLEM/CONDITION: CDC monitors the emergence and spread of new influenza virus variants and the impact of influenza on morbidity and mortality annually from October through May. REPORTING PERIOD COVERED: This report covers United States influenza surveillance conducted from October 1988 through May 1989. DESCRIPTION OF SYSTEM: Weekly reports from the vital statistics offices of 121 cities provided an index of influenza's impact on mortality; 58 WHO collaborating laboratories reported weekly identification of influenza viruses; weekly morbidity reports were received both from the state and territorial epidemiologists and from 153 sentinel family practice physicians. Nonsystematic reports of outbreaks and unusual illnesses were received throughout the year. RESULTS: During the 1988-89 influenza season, influenza A (H1N1) and B viruses were identified in the United States with essentially equal frequency overall, although both regional and temporal patterns of predominance shifted over the course of the season. Throughout the season increases in the indices of influenza morbidity in regions where influenza B predominated. Only 7% of identified viruses were influenza A (H3N2), but not isolations of this subtype increased as the season waned and it subsequently predominated during the 1989-90 season. During the 1988-89 season outbreaks in nursing homes were reported in association with influenza B and A (H3N2), but not influenza A (H1N1). INTERPRETATION: The alternating temporal and geographic predominance of influenza strains A (H1N1) and B during the 1988-89 season emphasizes the importance of continual attention to regional viral strain surveillance, since amantadine is effective only for treatment and prophylaxis of influenza A. ACTIONS TAKEN: Weekly interim analyses of surveillance data produced throughout the season allow physicians and public health officials to make informed choices regarding appropriate use of amantadine. CDC's annual surveillance allows the observed viral variants to be assessed as candidates for inclusion as components in vaccines used in subsequent influenza seasons.


Asunto(s)
Brotes de Enfermedades , Vacunas contra la Influenza , Gripe Humana/epidemiología , Humanos , Virus de la Influenza A/inmunología , Virus de la Influenza A/aislamiento & purificación , Virus de la Influenza B/inmunología , Virus de la Influenza B/aislamiento & purificación , Gripe Humana/microbiología , Gripe Humana/prevención & control , Vigilancia de la Población , Estaciones del Año , Estados Unidos/epidemiología , Organización Mundial de la Salud
11.
Horm Res ; 37 Suppl 3: 74-87, 1992.
Artículo en Inglés | MEDLINE | ID: mdl-1427647

RESUMEN

The objectives and the methodology of mammalian gene transfer are discussed and findings in growth hormone (GH) transgenic mice are reported to illustrate the potential offered by genetically designed animal models for investigations in various areas of biomedical research. Transgenic mice expressing hybrid genes composed of either human or bovine GH coding sequences fused to the mouse metallothionein I promoter show high serum levels of heterologous GH, increased growth rates and final adult size, decreased life expectancy and a variety of pathological changes.


Asunto(s)
Hormona del Crecimiento/genética , Crecimiento/genética , Animales , Femenino , Expresión Génica , Hormona del Crecimiento/sangre , Masculino , Ratones , Ratones Transgénicos , Modelos Biológicos , Regiones Promotoras Genéticas , Transfección
12.
Pediatr Nephrol ; 5(4): 513-21, 1991 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-1911131

RESUMEN

Effects of growth hormone (GH) overproduction were studied in transgenic mice expressing murine metallothionein I-GH fusion genes. The most obvious consequence was the acceleration of growth, which led to substantial increases in body weight of up to more than twice that seen in controls. Growth of the internal organs was stimulated, with hepatomegaly and nephromegaly as the most prominent features. GH transgene expression was also reflected in increased skeletal growth which affected various bones to different extents. The mean life-span of human GH transgenic mice with serum levels of hGH ranging from 3 x 10(3) to 9 x 10(5) ng/ml was drastically reduced at 160 days in both sexes. Severe renal lesions were the primary cause of the decrease in life expectancy and were characterized by marked nephron atrophy, obsolescence of numerous glomeruli, and a massive cystic dilation of the tubules. Initial changes involved the glomeruli, which showed significant enlargement and sclerotic lesions. The liver exhibited a pronounced hepatocellularmegaly and progressive degenerative as well as hyperplastic changes. One-third of the hGH transgenic animals displayed myocardial fibrosis. Hepatocellular carcinoma was found in bovine GH transgenic mice older than 12 months. Our observations are compared with results of other investigators.


Asunto(s)
Hormona del Crecimiento/genética , Metalotioneína/genética , Ratones Transgénicos/crecimiento & desarrollo , Animales , Expresión Génica , Hipertrofia , Riñón/patología , Hígado/patología , Ratones , Ratones Transgénicos/genética
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