表面处理对瓷牙材料机械强度影响的实验研究

目的 比较不同表面处理因素对瓷瓦材料机械强度的影响。方法 制备３００个表面均匀一致的实验标本,对抛光面进行表面处理,处理后的标本用万能实验机进行机械循环,然后用Ｐｉｓｔｏｎ－ｏｎ－ｔｈｒｅｅ ｂａｌｌ方法检查实验标本的挠屈强度。结果 双向卡方检验说明不同表面处理因素及不同循环次数对实验标本挠屈强度的影响都具有显著意义（（Ｐ〈０．０００１）;Ｑ－检验说明自然上釉、酸蚀、喷砂等表面自理和表面抛光相比,     

ImPact Test-Retest Reliability: Reliably Unreliable?

Context:

Computerized neuropsychological testing is commonly used in the assessment and management of sport-related concussion. Even though computerized testing is widespread, psychometric evidence for test-retest reliability is somewhat limited. Additional evidence for test-retest reliability is needed to optimize clinical decision making after concussion.

Objective:

To document test-retest reliability for a commercially available computerized neuropsychological test battery (ImPACT) using 2 different clinically relevant time intervals.

Design:

Cross-sectional study.

Setting:

Two research laboratories.

Patients or Other Participants:

Group 1 (n = 46) consisted of 25 men and 21 women (age = 22.4 ± 1.89 years). Group 2 (n = 45) consisted of 17 men and 28 women (age = 20.9 ± 1.72 years).

Intervention(s):

Both groups completed ImPACT forms 1, 2, and 3, which were delivered sequentially either at 1-week intervals (group 1) or at baseline, day 45, and day 50 (group 2). Group 2 also completed the Green Word Memory Test (WMT) as a measure of effort.

Main Outcome Measures:

Intraclass correlation coefficients (ICCs) were calculated for the composite scores of ImPACT between time points. Repeated-measures analysis of variance was used to evaluate changes in ImPACT and WMT results over time.

Results:

The ICC values for group 1 ranged from 0.26 to 0.88 for the 4 ImPACT composite scores. The ICC values for group 2 ranged from 0.37 to 0.76. In group 1, ImPACT classified 37.0% and 46.0% of healthy participants as impaired at time points 2 and 3, respectively. In group 2, ImPACT classified 22.2% and 28.9% of healthy participants as impaired at time points 2 and 3, respectively.

Conclusions:

We found variable test-retest reliability for ImPACT metrics. Visual motor speed and reaction time demonstrated greater reliability than verbal and visual memory. Our current data support a multifaceted approach to concussion assessment using clinical examinations, symptom reports, cognitive testing, and balance assessment.Key Words: intraclass correlation, concussions, mild traumatic brain injuries, neuropsychological testing, athletes

Key Points

• ImPACT had strong to weak test-retest reliability over time, consistent with the results of previous studies.
• Reliability was greater for the visual motor speed and reaction time subscores than for the verbal and visual memory subscores.
• Computerized neuropsychological testing is only 1 component of a multifaceted concussion-management program that uses all appropriate tools in clinical decision making.

In 2001, the Concussion in Sport (CIS) group concluded that neuropsychological testing was one of the “cornerstones” of concussion management.¹ Since that time, the CIS group has emphasized a multifaceted approach that includes neuropsychological testing in the management of sport-related concussion.^2,3Computerized neuropsychological tests are readily available and are believed to possess numerous benefits, including standardized and rapid delivery, a centralized means of data storage, and multiple forms to reduce the potential for practice effects while potentially measuring the same neurocognitive constructs as traditional neuropsychological tests.^4,5 Despite the benefits and empirical evidence supporting the use of computerized testing, questions regarding the psychometric properties and the clinical utility of these tests have been raised.⁶Randolph et al⁶ reviewed the psychometric properties of computerized neuropsychological testing platforms and found limited to no evidence of reliability and validity for all existing computerized platforms. Several groups^6–10 investigating the reliability of the ImPACT (ImPACT Applications, Pittsburgh, PA) have found intraclass correlation coefficients (ICCs) ranging from 0.15 to 0.85 for any 1 outcome measure. Specifically, higher ICCs (0.38 to 0.85) were reported for the ImPACT composite visual motor speed and composite reaction time scores and lower ICCs (0.23 to 0.64) for composite visual and verbal memory.^7,10,11 The highest ICC values were for the Web version of ImPACT (0.62 to 0.85), using a 1-year test-retest interval, in participants 13 to 18 years old.¹⁰ The rationale for these discrepancies in ICC values may be varying methods among studies. Schatz⁸ and Elbin et al¹⁰ (also P. Schatz, written communication, 2012, and R. J. Elbin, written communication, 2012) administered the same form (form 1) at 1- and 2-year intervals.⁸ Broglio et al⁷ administered forms 1, 2, and 3 over a 50-day period.³ The results from Schatz⁸ and Elbin et al¹⁰ are clinically meaningful in reestablishing baseline cognitive values for young athletes and athletes previously diagnosed with a concussion. The methods and results of Broglio et al⁷ reflect the clinical use of ImPACT when assessing an athlete with sport concussion. Variable test-retest reliability on computerized cognitive tests enhances the importance of the clinical examination and clinical judgment in the management of sport-related concussion.⁶ Although a multifaceted approach to sport-related concussion management is recommended (ie, neuropsychological testing, balance or motor-ability assessment, and monitoring self-reported symptoms), clinicians employed by institutions with limited resources may rely more heavily on computerized neuropsychological testing to determine the state of a concussed athlete and use these data in making return-to-play decisions.^2,4Because ImPACT is often used as a stand-alone instrument, we examined the test-retest reliabilities of ImPACT in 2 samples using 2 test-retest time intervals. We hypothesized that ImPACT outcome measures would reflect acceptable ICCs (≥0.75) at all time intervals. In addition to our primary hypothesis, we also hypothesized that ImPACT would have low false-positive and false-negative rates and limited practice effects.     

Knowledge and attitudes of infection prevention and control among health sciences students at University of Namibia

Background

Health Sciences students are exposed early to hospitals and to activities which increase their risk of acquiring infections. Infection control practices are geared towards reduction of occurrence and transmission of infectious diseases.

Objective

To evaluate knowledge and attitudes of infection prevention and control among Health Science students at University of Namibia.

Methods

To assess students'' knowledge and attitudes regarding infection prevention and control and their sources of information, a self-administered questionnaire was used to look at standard precautions especially hands hygiene.

Results

One hundred sixty two students participated in this study of which 31 were medical, 17 were radiography and 114 were nursing students. Medical students had better overall scores (73%) compared to nursing students (66%) and radiology students (61%). There was no significant difference in scores between sexes or location of the high school being either in rural or urban setting.

Conclusion

Serious efforts are needed to improve or review curriculum so that health sciences students'' knowledge on infection prevention and control is imparted early before they are introduced to the wards.     

Gene polymorphisms,tobacco exposure and oral cancer susceptibility: a study from Gujarat,West India

Polymorphic variability in the enzymes involved in biotransformation of tobacco‐related pro‐carcinogens plays an important role in modulating oral cancer susceptibility. CYP1A1*2A, CYP1A1*2C, GSTM1 and GSTT1 polymorphisms were determined in 122 oral carcinoma cases and 127 controls from Gujarat, West India using PCR‐based methods. The results revealed that the polymorphic variants of CYP1A1 gene did not show association towards oral cancer risk. The GSTM1 and GSTT1 null genotypes were found to be over‐represented in patients than controls, suggesting a moderate increase in risk of oral cancer. The oral cancer risk was significantly increased in the patients having either alone or concurrent deletion of GSTM1 and GSTT1. The results also suggested significant association between tobacco habits, especially chewing, variant genotypes of CYP1A1, GSTM1 and GSTT1 and oral cancer risk. Our data have provided evidence that GST polymorphism modified the susceptibility to oral cancer and individuals with variant genotypes of the three genes with tobacco habits are at significant risk of developing oral cancer.