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91.
Gunnar Rølla Bjørn Øsard Roberval de Almeida Cruz 《Journal of clinical periodontology》1993,20(2):105-108
Abstract Prevention of caries in exposed root surfaces constitutes an important clinical problem. It is thus important that clinicians involved with periodontology have an insight into fluoride prophylaxis. The understanding of the cariostatic mechanism of fluoride has improved during recent years. The aim of the present review is to give a short account of the present concept. Calcium fluoride appears to be the only product which is formed on enamel, dentin or cementum during brief topical treatments with fluoride or use of toothpaste containing fluoride. This calcium fluoride is stable in the oral environment: this is contrary to what was believed until recently. The calcium fluoride constitutes a pH-dependant reservoir of fluoride which releases fluoride when pH drops. The practical consequences of this concept is discussed. 相似文献
92.
Dodd Steven W. Havel Henry A. Kovach Paul M. Lakshminarayan Chitra Redmon Martin P. Sargeant Charlene M. Sullivan Gary R. Beals John M. 《Pharmaceutical research》1995,12(1):60-68
Mixing pharmaceutical preparations of soluble neutral regular insulin solution (NRI) and neutral protamine Hagedorn (NPH) crystalline insulin suspension leads to a reduction in the measurable amount of soluble insulin in the formulation supernatant. However in spite of the loss in soluble insulin, the time-actions of these components have been shown, in clinical trials, to be unaffected. The interaction between these different physical forms of insulin has been studied using reversed-phase HPLC, isothermal titrating calorimetry, and Doppler electrophoretic light scattering analysis. Sorbent surface and solution perturbation studies revealed that the NRI adsorbs to the surface of the NPH crystal with an equilibrium constant ranging from 104 M–1 to 107 M–!, depending on the protamine concentration, pH, ionic strength, and temperature. This adsorption behavior suggests that the binding is mediated by electrostatic interactions arising between the positively-charged NPH crystal and the negatively-charged NRI hexamer. Doppler electrophoretic light scattering results, used to probe the pH-dependent surface charge of NPH and soluble insulin hexamer, support the conclusion that electrostatic interactions mediate the adsorption process. Adsorption studies under physiological conditions indicate that the elevated temperature and ionic strength, in a subcutaneous depot, are sufficient to lead to the dissociation of the NRI/NPH complex that exists in these NPH mixture formulations. 相似文献
93.
94.
煤烟型大气污染对儿童肺功能的影响 总被引:4,自引:1,他引:3
为观察煤烟型大气污染对儿童健康的影响 ,选择了太原市 3个污染程度不同地区的 45 0名儿童进行肺功能测试和问卷调查。研究结果显示 ,儿童呼吸功能表现为重度污染区 <中度污染区 <相对清洁区 ;肺通气功能阻塞性异常率表现为重度污染区 >中度污染区 >相对清洁区 ;Logistic回归分析发现肺通气功能阻塞性异常率与小学生家庭的取暖方式、厨房和卧室是否分开以及污染物的水平有关 ;多元线性回归分析显示重度污染区儿童的FVC、FEF5 0与相对清洁区相比分别减少了 65 80ml、119 2 7ml,中度污染区儿童的FVC、FEF5 0与相对清洁区相比分别减少了 5 7 2 8ml和 114 2 9ml;Ln(SO2 )每升高一个单位 ,FVC和FEF5 0分别减少69 10ml和 119 79ml,Ln(PM1 0 )每升高一个单位 ,FVC、FEF5 0等分别减少了 193 5 0ml和 171 69ml。结果提示 ,太原市煤烟型大气污染对儿童呼吸系统产生了危害。 相似文献
95.
单克隆抗体对溶组织内阿米巴吞噬红细胞的影响 总被引:1,自引:0,他引:1
用具有抗细胞膜活性和抗细胞核、胞浆活性的单克隆抗体3F7和4G6与致病性溶组织内阿米巴HM-1∶IMSS株滋养体37℃孵育,在孵育即刻、5min、10min加入红细胞,检测滋养体吞噬红细胞的能力,并以正常小鼠血清和抗克氏锥虫抗体TCE04作为对照。结果,经单克隆抗体3F7孵育即刻的HM-1∶IMSS虫株滋养体吞噬红细胞能力明显减弱(P<0.001),而4G6抑制滋养体吞噬红细胞的作用不如前者明显。提示,抗细胞膜单克隆抗体对抑制滋养体吞噬红细胞有显著作用,但随着时间的推移,抑制作用明显减弱。 相似文献
96.
应用戊二醛、甲醛甲酚消毒感染根管各80例,观察其细菌学培养情况,结果表明戊二醛消毒根管后细菌培养阳性率4%,甲醛甲酚消毒根管后细菌培养阳性率为18%,说明戊二醛对感染根管的消毒作用显著优于甲醛甲酚消毒剂。 相似文献
97.
C. F. POETS A. ARNING W. BERNHARD C. ACEVEDO & H. VON DER HARDT 《European journal of clinical investigation》1997,27(4):293-298
Alveolar surfactant is well known for its ability to reduce minimal surface tension at the alveolar air–liquid interface to values below 5 mN m?1. In addition, it has been suggested that surfactant is also present in the airways, particularly in the perinatal period. We isolated surfactant from pharyngeal aspirates obtained from 33 neonates immediately after delivery and analysed it for both phospholipid (PL) composition and surface tension function. PL classes and phosphatidylcholine (PC) molecular species were determined by normal and reversed-phase high-performance liquid chromatography (HPLC), respectively. Static and dynamic surface properties of the surfactant were studied in a pulsating bubble surfactometer. Sample volume was 1.3 ± 0.5 mL (mean ± SD) with a total amount of 2.5 ± 1.3 μmol of PL and a concentration of 2.1 ± 1.0 μmol mL?1 PL. HPLC analyses of PL classes revealed a composition identical with surfactant prepared from alveolar washes, i.e. PC 83.6 ± 2.1%, sphingomyelin 1.4 ± 0.5%, phosphatidylglycerol 8.1 ± 1.6%, phosphatidylethanolamine 2.1 ± 0.5% and phosphatidylinositol 2.6 ± 1.1%. Thin-layer chromatography showed almost identical results but was more time-consuming and needed more material for analysis. Analysis of PC molecular species revealed a composition typical of human alveolar surfactant with 54.7 ± 3.9% dipalmitoyl PC, 10.3 ± 1.9% palmitoyloleoyl PC and 9.1 ± 1.5% palmitoylmyristoyl PC. Minimal surface tension fell to values below 5 mN m?1 within 5 min of cycling in all subjects. The methods used in this study allowed for complete PL and surface tension analyses of surfactant obtained during routine pharyngeal suctioning after delivery at term. Whether they are also applicable to preterm neonates with respiratory distress remains to be determined. 相似文献
98.
Surface-related triggering of the neutrophil respiratory burst. Characterization of the response induced by IgG adsorbed to hydrophilic and hydrophobic glass surfaces 总被引:1,自引:0,他引:1
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L LIU H ELWING A KARLSSON G NIMERI C DAHLGREN 《Clinical and experimental immunology》1997,109(1):204-210
Hydrophilic and hydrophobic glass surfaces precoated with human albumin, fibrinogen, or IgG were investigated with respect to their ability to activate the neutrophil NADPH-oxidase. We found that IgG-coated surfaces induced a substantial and prolonged neutrophil production of reactive oxygen species (ROS). When a hydrophilic surface was used to support protein binding, a somewhat lower neutrophil response (around 35%) was obtained, compared with the response induced by IgG on a hydrophobic surface. The production of ROS was completely eliminated when cytochalasin B was added to the measuring system, suggesting the involvement of the cell cytoskeleton in the activation process. The relation between the intra- and extracellular generation of ROS was further assessed, and we found that most of the ROS produced were released from the cells, in agreement with a model in which the activating surfaces induce a ‘frustrated’ phagocytic response. Serum totally inhibited ‘frustrated’ phagocytosis provided that the IgG molecules were sticking to a hydrophilic surface. 相似文献
99.
E. Zuskin J. Mustajbegovic E. N. Schachter D. Pavicic A. Budak 《International archives of occupational and environmental health》1997,70(6):413-418
A follow-up investigation was performed on 49 female workers studied 2 years earlier in a vegetable-pickling plant. Acute
and chronic respiratory symptoms and ventilatory capacity measurements were recorded during the original and the follow-up
studies. Maximal expiratory flow-volume (MEFV) curves were recorded during the Monday morning work shift. The forced vital
capacity (FVC), 1-s forced expiratory volume (FEV1), and flow rates at 50% and the last 25% of the FVC (FEF50, FEF25) were
measured. There were small increases in the prevalence of chronic symptoms between the two studies for both smokers and nonsmokers,
but these did not reach statistical significance. Five workers at the time of the initial study had a diagnosis of occupational
asthma; only one of these was still working at the time of follow-up. Workers lost to the follow-up had lower lung function
than those seen at follow-up. In workers who were followed, larger than expected mean annual declines were noted for all ventilatory
capacity parameters in both smokers (FVC 0.070 l, FEV1 0.070 l; FEF50 0.355 l/s, FEF25 0.270 l/s) and nonsmokers (FVC 0.045
l, FEV1 0.045 l, FEF50 0.285 l/s; FEF25 0.130 l/s). The decrease was particularly pronounced for FEF50 and FEF25. The accelerated
decline in ventilatory capacity tests noted in the female nonsmokers suggests an independent effect on lung function of work
exposure in this environment. Our data confirm that work in the pickling industry, particularly in small, poorly regulated
plants, has deleterious effects on respiratory function.
Received: 24 September 1996 / Accepted: 19 June 1997 相似文献
100.
K. ROELEVELD D. F. STEGEMAN H. M. VINGERHOETS A. VAN OOSTEROM 《Acta physiologica (Oxford, England)》1997,160(2):175-183
The background of the bioelectric activity of muscle recorded from the surface of the skin (surface electromyography) in terms of the representation of single motor units of the underlying muscle(s) is not very well documented or understood. An insight into the composition of an electromyogram is essential for the proper interpretation of one of the most widely applied electrophysiological techniques. In the present paper, a study of the contribution of single motor unit potentials to the surface electromyogram is presented. To this end, the decline of different components of the motor unit potential with depth of the motor unit is quantified. Experimentally, the action potentials from motor units at several positions in the muscle were recorded by 30 skin surface electrodes. Simultaneous use of scanning electromyography provided information about the actual position and size of the motor unit. Observed linear log–log relationships between motor unit potential magnitudes and distance indicated the usefulness of a power function to describe the motor unit potential's dependence on recording distance. It is shown that different specific surface motor unit potential characteristics fall off differently with depth. The magnitude–distance relationship is shown to be dependent on the recording configuration (unipolar vs. bipolar recording, including the inter-electrode distance) and the chosen motor unit potential parameter (negative peak amplitude, positive peak amplitude and area). 相似文献