New insights into salivary lactate dehydrogenase of human subjects

Lactate dehydrogenase (LDH) is a ubiquitous enzyme that plays a significant role in the clinical diagnosis of pathologic processes. The purpose of the current study was to examine LDH activity and isoenzyme profile of whole saliva and to compare it with the LDH activity of salivary glands and plasma before and after exposure to cigarette smoke (CS). The range of LDH activity in whole saliva at rest was 360 to 430 U/L. The mean +/- SEM of LDH activity in parotid and submandibular/sublingual salivary secretions was 41.3 +/- 19.2 U/L and 77.5 +/- 30.4 U/L, respectively, which implied that 75% of the whole-saliva LDH originated from an extra-salivary gland source. The profile of salivary LDH isoenzymes was found to have an entirely different pattern from that found in plasma, similar to that found in oral epithelium, indicating that the major source of salivary LDH is probably the oral epithelium-shedding cells. Therefore, salivary LDH may be evaluated for possible oral mucosal pathologies in a manner similar to that used for evaluating other tissue pathologies--such as those in heart, muscle, or liver--that can be detected in plasma. Exposure of whole saliva to CS in vitro resulted in a 41% reduction in LDH activity. However, CS exposure had no effect on LDH activity in plasma. Whole saliva, in contrast to plasma, contains redox-active metal ions such as iron and copper that may enhance LDH loss of activity. Therefore we conclude that whole saliva in the presence of CS becomes a potent protein-modifying agent that can destroy some of its endogenous components.     

酶联免疫吸附试验中影响全自动加样系统加样准确性的因素分析

目的探讨酶联免疫吸附试验(ELISA)中使用不同容量加样针和分液高度,对全自动加样系统加样准确度和精密度的影响。方法选取10μL和100μL两种加样量,每种加样量分4个小组进行实验,分别使用不同容量(400μL和800μL)的加样针和不同分液高度(浸润和未浸润)加样,计算每组的最终加样量、均值相对误差(E)和变异系数(CV),与实际工作标准进行比较。结果10μL加样E在-37.9%~-2.8%,CV在3.29%~14.49%;100μL加样E在-1.9%~0.8%,CV在0.44%~0.95%。结论不同容量加样针和分液高度对10μL加样影响较为明显,对100μL加样影响较小,在使用全自动加样系统进行ELISA时,应当选择适当容量的加样针和分液高度。     

Plasma lipoproteins in visceral leishmaniasis and their effect on Leishmania‐infected macrophages

This work aimed at investigating the lipid profile of zoonotic visceral leishmaniasis (VL) patients’ sera and the effect of lipoproteins on the in vitro production of tumour necrosis factor‐α (TNF‐α), interleukin (IL)‐6, IL‐10 and IL‐12 by Leishmania infantum‐infected and uninfected macrophages. Lipids were quantified in 26 VL patients’ sera and 26 healthy controls from a VL endemic area. The patients’ sera had higher triglyceride and very low density lipoprotein (VLDL) levels, and much lower apolipoprotein A1, total cholesterol, low density lipoprotein (LDL) and high density lipoprotein (HDL) levels than the control sera. Lipoprotein fractions were obtained by ultracentrifugation of sera. The addition of LDL and HDL to Leishmania‐infected and uninfected macrophages, in physiological concentrations, enhanced the production of IL‐6 and IL‐10, but not of IL‐12. LDL stimulated the production of TNF‐α only in infected macrophages, whereas HDL stimulated the production of lower amounts of TNF‐α in both infected and uninfected macrophages. VLDL stimulated only the production of IL‐10. It is proposed herein that LDL may influence the development of VL by promoting the production of TNF‐α by infected macrophages. A decrease in plasma LDL in some VL patients (to 20 mg/mL or less); however, would tend to reduce the production of TNF‐α and therefore to limit the development of immune‐mediated pathology, not withstanding the fact that it would perhaps increase the permissiveness of macrophages to Leishmania growth.     

The efficacy of a computer-assisted preoperative tutorial for clinical clerks

Objective

To assess the effectiveness of computer-assisted preoperative tutorials on human anatomy in improving the operating-room learning experience for clinical clerks.

Design

Crossover trials with immediate assessment and approximately 1-week delay between trials.

Setting

General surgery operating room of a university teaching hospital.

Subjects

Eight 4th-year clinical clerks on a single 8-week surgical rotation.

Main Outcome Measures

The senior surgeon’s assessment of the clerk’s knowledge and understanding of the operation, according to a six-item questionnaire, and the clerk’s own assessment of the experience in the operating room, according to an eight-item questionnaire.

Results

Surgeons rated the clerks’ performances in the operating room as better when they had received the preoperative tutorial (mean [and standard deviation], 3.7 [0.4]) than when they had not received the preoperative tutorial (3.0 [0.3]). The difference (0.7 [0.6]) was statistically significant (t₇ = 3.3, p < 0.01). Similarly, clerks rated their own experience more positively when they had received the tutorial (4.0 [0.2]) than when they had not (3.1 [0.3]), with the difference (0.9 [0.5]) being statistically significant (t₇ = 4.9, p < 0.001).

Conclusions

Short, preoperative, computer-assisted tutorials on human anatomy can have a positive impact on the clerk’s level of knowledge and confidence in the operating room. Further research is warranted into the extent to which students spontaneously make use of these tutorials.     

Saliva--a pivotal player in the pathogenesis of oropharyngeal cancer

Oropharyngeal (OP) cancer, which is usually squamous cell carcinoma, is the most common head and neck malignancy and accounts for 2-4% of all new cancers. It is primarily induced by exposure to tobacco. The paradigm of cigarette smoke (CS)-induced OP cancer's pathogenesis is based on the assumption that a constant direct attack of various CS carcinogens causes widespread accumulating cellular and DNA aberrations in the OP mucosal cells, in turn eventually resulting in malignant transformation. However, there is never a direct contact between CS and the OP mucosa. Saliva, bathing the mucosa from the oral cavity to the larynx, always intervenes, and CS must first interact with saliva before it reaches the mucosa. The current study investigated the role of saliva in the pathogenesis of OP cancer. A synergistic effect of CS and saliva on oral cancer cells was demonstrated. This synergism is based on the reaction between redox active metals in saliva and low reactive free radicals in CS, which results in the production of highly active hydroxyl free radicals. Thus, when exposed to CS, salivary behavior is reversed and the saliva loses its antioxidant capacity and becomes a potent pro-oxidant milieu. The devastating role of CS-borne aldehydes was demonstrated as well. Based on these results and on our recent reports demonstrating that CS destroys various salivary components, including protective ones such as peroxidase, the most important salivary antioxidant enzyme, a comprehensive view of the pivotal role of saliva in the pathogenesis of CS-induced OP cancer is suggested.     

The effects of enforced running on the gastrocnemius muscle in aging mice: An ultrastructural study

C57BL/6J mice (6, 19 and 27 months old) were trained in an electrically driven treadmill for a total period of 10 weeks. The training program started with 5 min. run per day and reached a maximum of 30 min. perday. Light and electron microscopy examinations of the gastrocnemius muscle showed that in young animals endurance training did not evoke any appreciable changes. In contrast, both test animals and their controls in the old group revealed clear signs of muscle cell atrophy which for the most part was accompanied by focal loss of myofilaments, mitochondrial changes and an increase in the amount of endomyseal collagen fibrils. In the old-trained group, the most obvious abnormally comprised of multiplication of both the T-tubules and of the tubules of the sarcoplasmic reticulum. Consequently, most of these animals showed the formation of tubular aggregates in their gastrocnemius muscle. Hence, it appears that endurance training in old animals tends to enhance the regressive changes that accompany the aging process of mammalian skeletal muscle.     

Teaching invasive perinatal procedures: assessment of a high fidelity simulator-based curriculum.

OBJECTIVE: Learning curves pose a difficult problem in the teaching of technical skills: how do you teach procedural skills without compromising patients' health? A simulator-based curriculum has been designed to minimize the risks to patients undergoing amniocentesis by shifting the learning curve away from patients and into the laboratory. This study evaluated the effectiveness of a high-fidelity simulator-based curriculum in improving the performance of amniocentesis by obstetric trainees. DESIGN: Thirty trainees received a course on the practice of amniocentesis. The curriculum consisted of a lecture, a syllabus, and a hands-on training session with the simulator. Pre- and post-training performance were evaluated with two rating scales. Training and performance evaluation were completed using the same simulator. The effectiveness of the simulator-based workshop and the effect of year of training were assessed using a two-way analysis of variance. RESULTS: Performance scores improved from a mean score of 55% to 94% using checklist scoring and from 57% to 88% using global ratings. The two-way analysis of variance revealed a significant effect of training (F1,60 = 43.57; P < 0.001) accounting for 45% of the variance in scores, and a significant effect of experience level (F2,60 = 9.16; P < 0.001) accounting for 25% of the variance in scores. CONCLUSIONS: A comprehensive curriculum based on a high-fidelity simulator was effective at improving skills demonstrated on the simulator. The challenge remains to establish that skills acquired on a simulator are transferable to the clinical setting.     

Effect of short- and long-term endurance training on creatine phosphokinase activity in skeletal and cardiac muscles of CW-1 and C57BL mice

Creatine phosphokinase (CPK) has been shown to provide the initial ATP for muscle contraction. The effect of wheel running on CPK levels was compared in hindleg and cardiac muscles of young, intermediate-age and old outbred CW-1 and inbred C57BL mice. Short-term (5 weeks) and long-term (over 12 months) regimens were used in these studies. It was shown that as a function of age there was a 20-30% decrease of CPK activity in hindleg muscles of old sedentary animals. No change with age was observed in cardiac muscles of old animals. Short-term exercise of 5 weeks resulted in an increase in CPK levels in young running mice in both hindleg and cardiac muscles. In old animals there was a slight decrease in striated hindleg muscles, but no change in cardiac muscles. In the long-term exercise group, young (6-month-old) and intermediate-age (15-month-old) animals showed a 20-40% increase in CPK specific activity in hindleg muscles over sedentary control mice. No such increase in CPK activity was observed in old trained mice. However, the long-term exercise regimen prevented the age-associated decline in CPK activity found in sedentary animals.     

HTK保护液对尸肾移植器官的影响

近期出版的第5期美国移植杂志(American Journal of Transplantation)报道了两项关于比较HTK和UW保护液对尸肾移植物预后的影响的研究结果,来自美国UNOS数据库和内布拉斯加医学中心大学的数据均显示HTK液对尸肾肾移植后移植肾的早期功能恢复不利.