RESUMO
The effects of a large arteriovenous fistula on left and right ventricular hemodynamics and cardiac myocyte size were examined in adult rats at 1 week and 1 month after surgery. Cardiac output, left ventricular function, and right ventricular function were evaluated before obtaining isolated myocytes for cell size measurements. Average heart weight increased 35% at 1 week and 86% at 1 month in rats with fistulas. In general, myocyte hypertrophy was due to a proportional increase in length and width (length/width ratio remained constant). This change was more evident in the large hearts from rats with 1-month fistulas. At both the 1-week and 1-month intervals, the hypertrophic response of right ventricular myocytes was slightly greater than that observed in the left ventricle or interventricular septum. Left ventricular systolic pressure and dP/dtmax were significantly reduced at 1 week but returned to normal after 1 month of overloading. Left ventricular end-diastolic pressure was increased approximately fivefold and twofold at 1 week and 1 month, respectively. Right ventricular systolic pressure and dP/dtmax were increased at both intervals examined. We conclude that severe volume overloading from a large aortocaval fistula in the rat is characterized by 1) depressed left ventricular function at 1 week followed by a large compensatory hypertrophy and near normal function at 1 month, 2) right ventricular pressure overload, and 3) changes in myocyte shape that resemble normal physiological growth.
Assuntos
Aorta , Fístula Arteriovenosa/fisiopatologia , Cardiomegalia/fisiopatologia , Hemodinâmica , Miocárdio/patologia , Veias Cavas , Animais , Fístula Arteriovenosa/patologia , Cardiomegalia/patologia , Feminino , Ratos , Ratos EndogâmicosRESUMO
The considerable decrease in microkeakage in the compound-reinforced restorations may be due to the tighter fit of the matrix band at the gingival wall of the preparation, which allows better condensation and marginal sealing of the restoration. The compound prevents lateral migration of the band during condensation pressures.
Assuntos
Amálgama Dentário , Pinos Dentários , Restauração Dentária Permanente/métodos , Colagem Dentária , Forramento da Cavidade Dentária , Materiais Dentários , Humanos , Estresse Mecânico , Propriedades de SuperfícieRESUMO
Subjects read an interview in which either a 36-year-old or a 76-year-old widow talked about her life and discussed how she had spent the previous day; they then recorded their impressions of the woman and rated her on a number of scales. Contrary to expectations, subjects rated the older woman significantly more favorably than the younger woman, even when her behavior corresponded to negative stereotypes of older person. Evidence from subjects' written impressions and spontaneous comments indicated that an older person who is alert, interesting, and involved is perceived as deviating from stereotyped expectations and is evaluated more positively than a younger person who exhibits these same characteristics. This may account for the fact that perceivers consistently view specific older persons as exceptional, even while they retain negative stereotypes of older people in general.
Assuntos
Envelhecimento , Atitude , Comportamento , Percepção Social , Comportamento Estereotipado , Adulto , Idoso , Feminino , Humanos , Personalidade , Comportamento SocialRESUMO
An instrument for recording extreme ultraviolet television images of the sun was flown in the Apollo Telescope Mount on Skylab. Solar radiation in the 171-630 A wavelength range, defined by the transmission band of three thin-film aluminum filters, was focused onto a p-quaterphenyl photon conversion layer by a platinum-coated mirror at normal incidence. The conversion layer was attached to the faceplate of a low light level SEC vidicon. An onboard video monitor enabled the Skylab crews to observe the images in realtime and to identify and follow the development of solar features. Images were also transmitted to the mission control center, where they were used in planning the ATM observing schedule.
RESUMO
The addition of proximal retention grooves to various designs of the Class II cavity preparation considerably improves the retention and resistance characteristics of amalgam restorations. The incorporation of proximal grooves should reduce the necessity for gross outline form as a means of gaining adequate retention adn resistance in the Class II preparation.
