• Tuberculosis and Respiratory Diseases
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• v.40 no.1
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• pp.16-22
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• 1993

Background: The Microbicidal and cytotoxic activities of neutrophils are to a large extent dependent on a burst of oxidative metabolism which generates superoxide anion, hydrogen peroxide, and other reactive products of oxygen. The respiratory burst of PMN is initiated by intracellular calcium mobilization that follows immune or particular stimulation and is very sensitive to modulation by c-AMP or adenosine. Despite its antagonism against adenosine, earlier study has demonstrated potent theophylline inhibition of the PMN respiratory burst at variable ranges of blood concentrations of theophylline in the healthy normal volunteers and in the septic animals pretreated or early post-treated with aminophylline (AMPH) or pentoxifylline. However it is unclear whether theophylline inhibits the superoxide generation or not in the established human sepsis caused by acute pneumonia, as taking into consideration of the fact that full activation of neutrophils have occurred within minutes after the septic insult in the animal experiments. Methods: We measured the $O_2$ generation of peripheral arterial neutrophils obtained from 11 human septic subjects caused by acute pneumonia before and 1 hour after completion of continuous AMPH infusion. Patients were identified and studied within 48 hour of admission. All subjects were administered an intravenous loading and maintenance dose of AMPH. The generation of $O_2$ was measured at a discrete time point (60 min) by the reduction of ferricytochrome c.PMA (10 ${\mu}g/ml$) was used as a stimulating agent. PMNs were isolated at a concentration of $2{\times}10^6$ cells/ml. The arterial oxygen tension, blood pressure and heart rates were also checked to evaluate the systemic effects of AMPH in the acute pneumonia. Results: The mean serum concentration of AMPH at 60 minutes was $8.8{\pm}0.6{\mu}g/ml$. Sixty minutes after AMPH infusion the generatition of $O_2$ was decreased from $0.076{\pm}0.034$ to $0.013{\pm}0.004$(OD) (p<0.05) and from $0.177{\pm}0.044$ to $0.095{\pm}0.042$(OD) (p<0.01) in the resting and stimulated PMNs respectively. $PaO_2$ was not changed after AMPH infusion. Conclusion: AMPH may compromise host defense by significant inhibition of neutrophil release of superoxide anion and it had no effect on improving $PaO_2$ in the acute pneumonia.

• Journal of Dental Rehabilitation and Applied Science
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• v.24 no.3
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• pp.269-281
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• 2008

Fatigue or overload can result in mechanical problems of implant components. The mechanical strength in the implant system is dependent on several factors, such as screw and fixture diameters, material, and design of the fixture-abutment connection and abutment. In these factors, the last rules the strength and stability of the fixture-abutment assembly. There have been some previous reports on the mechanical strength of the fixture-abutment assembly with the compressive bending test or short-term cyclic loading test. However, it is restrictive to predict the long-term stability of the implant system with them. The purpose of this study was to evaluate the influence of the design of the fixture-abutment connection and abutment on the mechanical strength and failure mode by conducting the endurance limit test as well as the compressive bending strength test. Tests were performed according to a specified test(ISO/FDIS 14801) in 4 fixture-abutment assemblies of the Osstem implant system: an external butt joint with Cemented abutment (group BJT), an external butt joint with Safe abutment (group BJS), an internal conical joint with Solid abutment (group CJO), and an internal conical joint with ComOcta abutment (group CJT). The following conclusions were drawn within the limitation of this study. Compressive bending strengths were decreased in order of group BJS(1392.0N), group CJO(1261.8N), group BJT(1153.2N), and group CJT(1110.2N). There were no significant differences in compressive bending strengths between group BJT and group CJT(P>.05). Endurance limits were decreased in order of group CJO(600N), group CJT(453N), group BJS(360N), and group BJT(300N). 3. Compressive bending strengths were influenced by the connection and abutment design of the implant system, however endurance limits were affected more considerably by the connection design.