Low prevalence of human papillomavirus in a geographic region with a high incidence of head and neck cancer

BACKGROUND: The main purpose of this study was to determine the prevalence of human papillomavirus (HPV) infection in patients with head and neck carcinomas from Brazil. MATERIALS AND METHODS: Forty-five patients with head and neck squamous cell carcinoma were included in the study, from 1995 to 1996. Forty-two were male and 3 female, with age ranging from 32 to 82 years (median 61). Five patients (11%) did not have previous history of use of tobacco and 38 (90.5%) were heavy smokers. Tumor sites were pyriform sinus, 10; tongue, 11 (oral, 6; base, 5); larynx, 7; floor of mouth, 3; tonsil, 6; retromolar area, 3; inferior gingiva 2; buccal mucosa, 2; and maxillary sinus in 1 patient. Twenty-five were stage IV, 17 stage III, and 3 stage II. RESULTS: The presence of HPV DNA was detected in 5 of 45 patients (11%), all of them with HPV 16. Two patients had HPV DNA in normal mucosa and tumor tissue, 1 patient had HPV DNA only in the normal mucosa and tumor tissue, 1 patient had HPV DNA only in the normal mucosa, and 2 patients were positive for HPV DNA in tumor tissue. Four patients were male and 1 was female; 2 patients were nonsmokers. Three patients had tonsil carcinoma, 1 patient had a tongue carcinoma, and 1 patient had a pyriform sinus cancer. CONCLUSIONS: The role of chemical carcinogens seems to be more important in the genesis of head and neck cancer than is HPV infection. The presence of HPV DNA in 5 of 45 patients stimulates further investigation to determine the role of HPV as a risk factor for head and neck carcinoma.     

Importance of platelets in increased vascular permeability evoked by experimental haemarthrosis in synovium of the rat

Increased vascular permeability of synovium induced by experimental haemarthrosis was studied in the stifle joint of the rat. Abnormal permeability was detected by injecting animals intravenously with colloidal carbon and examining the synovial vessels for intramural deposits of carbon. Both fresh and heparinized whole blood injected into the joint induced a marked permeability response of synovial venules which persisted for 18 hours. Platelets suspended in heparinized Tyrode solution induced a similar response, but one lasting only 12 hours. The permeability effects of suspensions of leucocytes and erythrocytes on the synovial vasculature were relatively mild and were maximal 5 and 12 h respectively after intra-articular injection. Heparinized platelet-free plasma had no significant permeability effects. These results indicate that platelets may play an important role in the pathogenesis of synovial inflammation in haemarthrosis.     

1.4 Fast volume determination using a differential capacitance manometer

The reliable pressure readings with a capacitance manometer are the basis for a new type of instrument designed for accurate and rapid measurements of capillary volumes. The basic measuring principle is based on expansion of air atmospheric pressure enclosed in a known volume into a pre-evacuated cylinder so that the enclosed volume will cause a reduced pressure in the cyllinder. The same is done with the air in an unknown volume into another identical pre-evacuated cylinder. A differential capacitance manometer is then used to measure the difference in pressure between the two cylinders with a high degree of accuracy. This difference in pressure is shown to be ainear function of the difference in volume between the unknown and the known volume. The accuracy and repeatability of the instrument is better than 0.5%.     

Preparation of DyPt2 Films by Using Magneto Controlled Sputtering and Phase Transformation of Dy/Pt Alloy Films

DyPt2 films were prepared by alternate deposition thin Dy and Pt layers on glass substrates by DC magneto controlled sputtering method. The XRD data indicated that for as-deposited Dy/Pt films, and the periodic layered structures along thickness direction were evidenced with low angle X-ray scattering. With increasing annealing temperature, the compounds of DyPt, DyPt2 and DyPt3 were formed successively at temperature ranging from 300 to 400℃. It was found that the composition reaction DyPt DyPt3→2DyPt2 took place at 500℃. After annealing at 500℃ for 1h, the compounds DyPt and DyPt3 transformed completely into the DyPt2 compound.     

CT□型弹簧操动机构的可靠性分析

近年来,随着自能式灭弧技术的不断进步,自能式高压SF6断路器的应用日渐增多.由于自能式原理主要是依靠电弧自身的能量熄灭电弧,而不需要操动机构提供能量,故断路器所需要的操作功大大减小,可采用低操作功的弹簧操动机构.     

断路器操作机构脱扣力的稳定

断路器操作机构的脱扣力对断路器工作的可靠性具有较大的影响,通过分析脱扣力的影响因素,制订了在不改变断路器结构的情况下,如何稳定断路器操作机构脱扣力的几点措施.目的在于使断路器在实际生产中,可快速、有效地解决脱扣力离散度大的问题.