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81.
The functional and physical properties of cellular membranes isolated from Triticum aestivum, cvs Norstar and Fredrick, were altered coincident with changes in composition after a lethal ice-encasement stress and further during a 6 hour post-thaw period. Crowns encased in ice for a duration which inhibited regrowth, exhibited enhanced rates of electrolyte leakage. Furthermore, the recovery of total microsomal protein and phospholipid declined, suggesting that some membrane degradation had been induced during the anoxic stress. The microviscosity of microsomes and liposomes prepared from such membranes increased during stress, and this was correlated with a 2- to 4-fold increase in the free fatty acid levels in the microsomal fraction. There was, however, only a relatively minor change in fatty acid unsaturation during the ice-encasement stress. The process continued during a 6 hour aerobic post-thaw treatment, but the pattern was somewhat different. During this phase, the leakage of electrolytes was further increased and the recovery of microsomal protein and phospholipid continued to decline, indicating general degradation; but, in contrast to the anoxic phase, the degree of fatty acid unsaturation declined markedly, indicating lipid peroxidation.  相似文献   
82.
The treatment of velopharyngeal incompetence remains unsatisfactory because the causes are many, as are the variations in anatomic and physiologic defects. Therefore, full assessment and investigation are essential in tailoring the surgery to the defect. A modified Hynes pharyngoplasty has been used in 40 patients, aged 4 to 52, over a 4-year period for velopharyngeal incompetence of varying etiologic causes. Speech was assessed before and at least 6 months after pharyngoplasty. At the same time, radiologic and, when possible, nasendoscopic investigations were undertaken. Thirty-eight patients had no or variable nasal escape (variable defined as achieving intermittent closure), whereas 33 had normal or slight hyponasal resonance. There was only one complication, an asymptomatic dehiscence of the "bucket handle" flap from the posterior wall. Thirteen patients had an assortment of side effects, none requiring surgical treatment. We believe that patients who are suitable for the described sphincter pharyngoplasty are those with slight or moderate nasal escape having a mobile palate with an anteroposterior gap of 5 mm or less.  相似文献   
83.
Further refinements on the triangular flap closure of the cleft lip   总被引:1,自引:0,他引:1  
Refinements in the triangular flap closure of the unilateral cleft lip are presented. Randall's mathematical interpretation of the Tennison repair has been extended by using a series of arcs to determine the crucial points which form the triangular flap. Using this easily taught method, an isosceles triangular flap can be plotted which will interdigitate into the noncleft side of the lip. Two symmetrical vertical distances on either side of the cleft are thus formed. This allows for a standardized repair which may be more readily taught than the rotation-advancement technique. In addition, flaps are created which are turned medically toward the cleft and are used to accentuate the philtral pout, close the nostril floor, and reinforce the lip repair, allowing closure of even extremely wide clefts in one stage. These refinements in using the triangular flap closure for the repair of the unilateral cleft lip are diagrammatically presented. We believe that these refinements enhance the results of this closure.  相似文献   
84.
We studied the effects of ionizing radiation on the morphology of the pulmonary circulation using an in vivo rat model and an in vitro pulmonary artery endothelial cell model. Gamma radiation was given as either an acute (30 Gy) or fractionated (5 X 6 Gy) dose to one hemithorax of rats. An acute 30-Gy dose delivered resulted in a 70% decrease in pulmonary arterial perfusion, using technetium-99m microaggregated albumin (99mTc-MAA), in the irradiated lung by 2-3 weeks after irradiation. Pulmonary microradiographs, using a barium sulfate perfusion method, obtained 2-3 weeks after irradiation demonstrated widespread loss of capillary filling and segmentation of the vessels. Histologic examination demonstrated intact capillaries, suggesting that the alterations in pulmonary perfusion were at the precapillary level. Similar abnormalities in lung perfusion and morphology were found after delivery of fractionated doses of radiation, but the onset of the changes was delayed, occurring 4-6 weeks postirradiation. Using cultured pulmonary endothelial cell monolayers, cell sloughing and retraction from the surface substrate were observed within 24 h after in vitro delivery of 30 Gy. Similar findings occurred in monolayers given fractionated doses (5 X 6 Gy) of radiation 2-3 days after the final dose. The in vivo animal and in vitro endothelial cell models offer a useful means of examining the morphologic alterations involved in radiation lung vascular damage.  相似文献   
85.
In a longitudinal prospective study of 1,529 women pregnant in 1974-1975, aspirin and acetaminophen were the two medications most frequently taken during the first half of pregnancy (46 and 41%, respectively). In a selected cohort of 421 offspring of these women, examined at 4 years of age, maternal aspirin use during the first half of pregnancy was significantly related to IQ and attention decrements in the exposed children. Multiple regression analyses were used to statistically adjust for a variety of potentially confounding factors including demographic characteristics, child characteristics, other exposures, and lifestyle/environmental variables. Continuous dose-response and step-function parameterizations of aspirin exposure were both statistically significant and not clearly distinguishable from each other. The estimated aspirin effect is significantly greater for girls than boys. Aspirin effects on offspring function were found in the absence of effects on physical size both at birth and at 4 years. Maternal acetaminophen use was not significantly related to child IQ or attention. As this exploratory research originated from observations of a data set gathered for other purposes, it would be desirable to have these findings replicated in other studies. Further follow-up of the children at a later age is planned.  相似文献   
86.
Studies have been made on the role of the thyroid in the development of rats. In the first group of experiments, newborn rat received within a month mercazolyl which inhibits the activity of the thyroid; in animals of the second group, mercazolyl injections were combined with cold exposures which stimulated motor activity in animals. It was found that hypothyroid rats in both groups exhibit retardation of growth as compared to normal animals. However, retardation is less significant in animals of the second group, as it is indicated by smaller changes in the protein content and total mass of skeletal muscles.  相似文献   
87.
88.
Normal keratinocytes, SV40-transformed keratinocytes (SVK14), and various squamous carcinoma cell (SCC) lines have been used as an in vitro model system to study the properties of phorbol ester receptor and protein kinase C expression during keratinocyte differentiation. The cell lines used exhibit a decreasing capacity to differentiate in the order of keratinocytes approximately SVK14 greater than SCC-12F2 greater than SCC-15 greater than SCC-4; moreover, all cell lines respond to a low external Ca2+ concentration by a decreased capacity to differentiate. Normal keratinocytes exhibited the highest number of phorbol ester receptors as compared to the other cell lines, while each individual cell line exhibited a higher number of phorbol ester receptors during growth under normal Ca2+ conditions as compared to cells grown under low Ca2+ conditions. The apparent dissociation constant (Kd) demonstrated only small variations in the various cell lines. In contrast, the cytoplasmic protein kinase C activity, was found to be higher in cells grown under low Ca2+ conditions than in cells grown under normal Ca2+ conditions, indicating the absence of a causal relationship between cytoplasmic protein kinase C activity and phorbol ester receptor expression. Therefore the properties of protein kinase C have been determined in more detail in normal keratinocytes and SCC-15 cells. These studies revealed differences between protein kinase C properties from the two cell lines grown under normal and low Ca2+ conditions. The differences included the effect of phorbol 12-myristate 13-acetate (PMA) on the redistribution pattern of protein kinase C between the cytoplasmic and particulate fractions as well as the activating effect of diolein in vitro on protein kinase C activity, partly purified from particulate or cytoplasmic fractions. These observations demonstrate that the functional protein kinase C activity of keratinocytes is determined by various endogenous and exogenous activators and that these activators are modulated differently in various cell lines, under various growth conditions (low Ca2+ versus normal Ca2+).  相似文献   
89.
Summary The purpose of this paper is to describe the immunocytochemical localization of M protein of vesicular stomatitis virus (VSV) in infected cells. Vero cells, MDBK cells, Swiss 3T3 cells, and BHK cells were examined at various times after infection. For immunofluorescent staining, the cells were fixed with PLP fixative and then treated with 0.05% Triton X-100 before incubation with antibodies. Three hours after infection, M protein exhibited diffuse immunostaining throughout the cytoplasm and later accumulated along the cell membrane. The localization of M protein differed from the granular localization of the nucleocapsid N protein of VSV in the cytoplasm. For electron microscopy, the cells were fixed first in a mixture of 2% paraformaldehyde and 0.05% glutaraldehyde and then with PLP fixative, this being followed by treatment with 0.05% saponin. They were then immunostained using the immunoperoxidase method. The M protein was found to be distributed throughout the cytoplasm and later under the cell membrane, especially at virus budding sites. We also used postembedding immunostaining and freeze-fracture immunostaining to avoid the translocation of M protein caused by the detergent treatment. These techniques confirmed our previous results. Our findings are consistent with the view that the M protein of VSV is synthesized on free ribosomes and is then associated with the cell membrane where viral assembly may occur.S. Ohno was a visiting fellow from the Fogarty International Center at the National Institutes of Health, USA, from September 1981 to August 1983, while some parts of this work were in progress.  相似文献   
90.
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