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1.
Glauber T Silva Alejandro C Frery Mostafa Fatemi 《Computerized medical imaging and graphics》2006,30(5):321-327
We study the image formation of vibro-acoustography systems based on a concave sector array transducer taking into account depth-of-field effects. The system point-spread function (PSF) is defined in terms of the acoustic emission of a point-target in response to the dynamic radiation stress of ultrasound. The PSF on the focal plane and the axis of the transducer are presented. To extend the obtained PSF to the 3D-space, we assume it is a separable function in the axial direction and the focal plane of the transducer. In this model, an image is formed through the 3D convolution of the PSF with an object function. Experimental vibro-acoustography images of a breast phantom with lesion-like inclusions were compared with simulated images. Results show that the experimental images are in good agreement with the proposed model. 相似文献
2.
Adalberto Parra Jorge Ramírez-Peredo Rocío Hidalgo Amelia Morales-Toquero Gabriela Velásquez-Ramírez Alejandro Ruiz-Argüelles Guillermo J Ruiz-Argüelles 《Biology of blood and marrow transplantation》2006,12(5):566-572
We compared the functional status of the hypothalamic dopaminergic tone in patients given an allogeneic hematopoietic stem cell transplantation (allo-HSCT) with chronic graft-versus-host disease (GVHD) with that observed in patients with allo-HSCT without chronic GVHD and in healthy controls. The effect of acute dopaminergic blockade with intravenous metoclopramide on serum prolactin (PRL) concentrations was evaluated. Twenty volunteers, 20 to 52 years of age, seronegative for both hepatitis C virus and the human immunodeficiency virus, were studied: (1) 10 clinically healthy men (group 1), and (2) 9 patients with leukemia, and 1 patient with refractory aplastic anemia who underwent allo-HSCT, 5 of whom (3 men and 2 women) developed chronic GVHD (group 2), and 5 (3 men and 2 women) who did not develop chronic GVHD (group 3). Serum PRL concentrations were measured both fasting and after intravenous administration of metoclopramide (10-mg bolus). The area under the PRL curve was calculated. Patients in group 2 were older than those in groups 1 and 3 (P<.018), but their body mass index was similar. Fasting serum PRL concentrations were similar among the 3 groups; however, group 2 had higher PRL concentrations throughout the test (P<.001) and a greater area under the PRL curve than groups 1 and 3 (P<.001), without differences between the last 2 groups. The differences remained significant after adjustment for age (P<.01). Our results in a small group of patients with chronic GVHD after allo-HSCT suggest the existence of an increased functional level of their hypothalamic dopamine tone, which would favor a tendency toward a diminished endogenous production, release of pituitary PRL, or both. This could represent an adaptive mechanism aiming to maintain circulating PRL concentrations within a physiological range. 相似文献
3.
D Mezzano G E del Pino M Montesinos M E García E Aranda A Foradori 《Thrombosis and haemostasis》1991,66(2):254-258
Thrombocytopenia was induced in mongrel dogs by two mechanisms: immunologically, by intravenous injection of heterologous antiplatelet antibody, and non-immunologically, by circulating the blood through glass beads in anesthetized animals. The platelet content of 5-HT was monitored before and during the recovery of the blood platelet counts. This period is associated with the normalization of the mean platelet survival time and with a progressive increase in the mean age of the circulating platelet population. A continuous increment in platelet 5-HT closely followed the increase in platelet counts in both models of thrombocytopenia, and a strong correlation was found between the platelet age and 5-HT content. These findings support the concept that platelets accumulate 5-HT during their physiological aging process, contradicting the notion that a negative balance in 5-HT content results at the end of their physiological lifespan in circulation. These results are not in conflict with the concept that circulating platelets release and re-uptake 5-HT. 相似文献
4.
In the present paper, the results obtained are shown after a study by means of multivariant statistical analysis, of the quantity of Eimeria spp. oocyst elimination in sheep, bearing in mind the variations observed in the different areas, in the different age-groups, from month to month, and from year to year. Climatic factors, development of immunity, lambing seasons, and poor hygienic conditions seem to be the factors responsible for the statistically significant differences found when analysing the aforementioned main effects. 相似文献
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This study investigates whether tissue recoil or patient intrinsic factors influence the final position of the nipple areola
complex (NAC) after reduction mammoplasty.
The age, pre-operative ptosis, BMI and weight of the tissue resected were recorded as patient intrinsic factors in 37 patients
undergoing reduction mammoplasty. The “spring-back” value was defined as the distance from the sternal notch to a nipple landmark
on the breast meridian with the patient sitting up, minus the same measurement repeated with the patient recumbent to eliminate
the pull of gravity on the breast. Spring back was measured pre-operatively for the nipple and nipple mark then post-operative
for the nipple. The difference in centimeters between the final post-operative distance from the sternal notch to the nipple
and the level intended by the pre-operative nipple mark was termed the “judgment error.” The final position of the post-operative
nipple and the judgment error was compared to the spring-back values and patient intrinsic factors.
Pre-operative ptosis was statistically related to increasing patient BMI and mass of tissue resected per breast. Pre-operative
spring-back values for the nipple increased with increasing ptosis, BMI and decreasing age. Spring-back values were greater
in the lower pole of the breast than in the upper pole. The final position of the nipple was higher than the pre-operative
mark in 65% of cases, lower in 8% and as marked in 27% of cases. The post-operative NAC was, on average, 0.6 cm higher than
planned pre-operatively. The post-operative distance from the sternal notch to the nipple increased with increasing pre-operative
ptosis, mass of breast tissue resected per breast and all three spring-back values. The difference between the level of the
pre-operative mark and the final nipple position showed a weak correlation with post-operative spring-back values.
The parameters of ptosis, BMI, weight of tissue resected per breast and pre-operative nipple spring back reflect body habitus
and breast size. Spring-back values vary between the upper and lower pole of the breast. The final NAC position was higher
than that intended at pre-operative marking in the majority of cases. The surgeon instinctively marks the nipple lower in
patients with greater pre-operative ptosis and in whom a larger resection is anticipated. Judgment error did not relate to
intrinsic factors nor to pre-operative spring-back values; hence, these parameters cannot be applied as predictive tools for
more accurate pre-operative marking of the nipple position. This study suggests that the pre-operative nipple mark should
be placed, with the patient sitting up, at least 23 cm from the sternal notch and 0.6 cm lower than the final position estimated
using the inframammary crease as a landmark.
An invited commentary on this paper is available at . 相似文献
9.
Manuel Sosa P. Saavedra J. del Pino-Montes J. Alegre R. Pérez-Cano G. Martínez Díaz Guerra M. Díaz-Curiel C. Valero M. Muñoz-Torres A. Torrijos J. Mosquera C. Gómez-Alonso GIUMO Study Group 《Journal of clinical densitometry》2005,8(4):430-435
Measurement of ultrasonographic parameters provides information concerning not only bone density but also bone architecture. We investigated the usefulness of ultrasonographic parameters and bone mineral density (BMD) to evaluate the probability of Colles' fracture. Two-hundred eighty-nine postmenopausal women (62.3 +/- 8.7 yr) with (n = 76) and without (n = 213) Colles' fracture were studied. BMD of lumbar spine and proximal femur was evaluated in all women by dual-energy X-ray absorptiometry (DXA) and speed of sound (SOS), broadband ultrasound attenuation (BUA), and stiffness in the calcaneus were measured by a Sahara ultrasonometer (Hologic). Patients suffering from Colles' fracture had lower values of BMD adjusted by height at the lumbar spine, L2-L4 (0.797 g/cm2 vs 0.860 g/cm2), femoral neck (0.685 g/cm2 vs 0.712 g/cm2 ), SOS (1518 m/sg vs 1525 m/sg), and stiffness (74.6 vs 77.7) (p < 0.05). Nevertheless, BUA values were similar in both groups. After stepwise logistic regression analysis, the area found under receiver operating characteristic (ROC) curves was 0.60 for L2L4 and 0.63 for a formula combining L2L4 and height. Our data suggest that patients suffering from Colles' fracture have lower values of BMD by DXA, SOS, and stiffness. However, the ability of these techniques to discriminate is low because the values for the area under ROC curve are 0.60 for L2-L4 and 0.63 for a formula derived of the combination of L2-L4 and height. 相似文献
10.
I M Rebeyka R A Axford-Gatley B G Bush P J del Nido D A Mickle A D Romaschin G J Wilson 《The Journal of thoracic and cardiovascular surgery》1990,99(3):475-483
The production and prevention of calcium paradox injury in myocardium was studied in a canine model of cardiopulmonary bypass with multidose, moderately hypothermic, crystalloid cardioplegic solution. During 4 1/2 hours of global ischemia, three groups of six dogs each received one of three histidine-buffered cardioplegic solutions (500 ml initially and 250 ml every 30 minutes) at 27 degrees C. Group 1 cardioplegic solution was calcium free, group 2 solution contained a trace amount of calcium chloride (70 mumols /L), and group 3 cardioplegic solution was calcium free but contained diltiazem (150 micrograms/kg body weight). Left ventricular function measured as percent control of developed pressure revealed significantly greater (p less than 0.05) recovery in groups 2 and 3. Triphenyltetrazolium chloride staining showed 35% +/- 9% (mean +/- standard error) of heart mass necrosis in group 1 versus 0% and 0.5% +/- 0.4% in groups 2 and 3, respectively (p less than 0.001). Electron microscopy revealed ultrastructural changes characteristic of calcium paradox injury in group 1 myocardium. Calcium paradox injury was produced in an in vivo model of global myocardial ischemia and multidose cardioplegia despite moderate hypothermia and non-coronary collateral flow. The addition of either trace levels of calcium or diltiazem to the cardioplegic solution was effective in preventing this injury. 相似文献