Summary Two methods for harvesting osteoblast-like cell populations from newborn (10 days) rat calvaria were compared. The first one
consisted in culturing the periosteum-free bones and then trypsinizing the cells on the bone surface. The second one involved
the migration of the osteoblasts on glass fragments before trypsinization. Since the plating efficiency, the proportion of
alkaline phosphatase-positive cells, the population doubling time, and the calcium deposition were more adequate, the second
method was used to further characterize the behavior of the cultures. During the first week of culture, the cells featured
shapes similar to those observedin vivo on the surface of periosteum-free calvaria. They formed multilayers and, in the presence of ascorbic acid, synthetized an
organic matrix containing exclusively type I collagen. Later, small amounts of type III collagen appeared. The cells were
embedded in the matrix and progressively acquired the morphologic phenotype of osteocyte-like cells. The matrix mineralized
in the presence of β-glycerophosphate. The technique of dropinoculation (high concentration of cells in a small volume of
medium) promoted the multilayer formation and the achievement of large mineralized plates (about 1 cm2) in 3 weeks of culture. 相似文献
Carcinoids of the pancreas are exceedingly rare tumors that orieinate from the enterochromaffin cells of the gastroenteropancreatic neuroendocrine system. According to a recent report,1 pancreatic carcinoids are found in only 0.58% (79/13 715 cases) of the entire carcinoid group. Todate, very limited information regarding the detection and diagnosis of this entity has been reported in the available literature. Although pancreatic carcinoid tumors grow. 相似文献
Background: The analgesic nefopam does not compromise ventilation, is minimally sedating, and is effective as a treatment for postoperative shivering. The authors evaluated the effects of nefopam on the major thermoregulatory responses in humans: sweating, vasoconstriction, and shivering.
Methods: Nine volunteers were studied on three randomly assigned days: (1) control (saline), (2) nefopam at a target plasma concentration of 35 ng/ml (low dose), and (3) nefopam at a target concentration of 70 ng/ml (high dose, approximately 20 mg total). Each day, skin and core temperatures were increased to provoke sweating and then reduced to elicit peripheral vasoconstriction and shivering. The authors determined the thresholds (triggering core temperature at a designated skin temperature of 34[degrees]C) by mathematically compensating for changes in skin temperature using the established linear cutaneous contributions to control of each response.
Results: Nefopam did not significantly modify the slopes for sweating (0.0 +/- 4.9[degrees]C [middle dot] [mu]g-1 [middle dot] ml; r2 = 0.73 +/- 0.32) or vasoconstriction (-3.6 +/- 5.0[degrees]C [middle dot] [mu]g-1 [middle dot] ml; r2 = -0.47 +/- 0.41). In contrast, nefopam significantly reduced the slope of shivering (-16.8 +/- 9.3[degrees]C [middle dot] [mu]g-1 [middle dot] ml; r2 = 0.92 +/- 0.06). Therefore, high-dose nefopam reduced the shivering threshold by 0.9 +/- 0.4[degrees]C (P < 0.001) without any discernible effect on the sweating or vasoconstriction thresholds. 相似文献
The excretion of four inhibitors of urinary stone formation (zinc, magnesium, citrates and glycosaminoglycans (GAG) was studied in 20 normal controls and 40 recurrent calcium stone formers who were placed on a fixed diet restricted in calcium, oxalates and purines. We were unable to show any abnormality in the excretion of Zn, Mg or GAG. In 11 patients, a low level of urinary citrate was a significant feature that was associated in most cases with a urinary pH value above 6. Citrate concentration (per litre) and output (per 24 h) were found to be lower than in the controls in 19 and 33% respectively of the determinations. The overall ratio of average urinary citrate concentration in patients and controls was 0.56, a figure in agreement with previous data. 相似文献