[Determination of creatinine and 2-thiothiazolidine-4-carboxylic acid in urine by ultra high performance liquid chromatography tandem mass spectrometry]

Objective: To establish an ultrahigh performance liquid chromatography tandem mass spectrometry method for the determination of creatinine (Cre) and 2-thiothiazolidine-4-carboxylic acid (TTCA) in urine. Methods: In October 2020, the end-of-shift urine samples of the monitored subjects were taken, and the filtrate was prepared by centrifugation. After separated by ultra high performance liquid chromatography C18 column, acetonitrile and 0.2% acetic acid aqueous solution were used as mobile phases for gradient elution, the three quadrupole tandem mass spectrometry adopted an electrospray ion source (ESI) , the ion source temperature was 500 ℃ , and the air curtain gas flow rate was 31.4 L/min, qualitative and quantitative analysis of Cre and TTCA were carried out under the multiple reaction monitoring mode. Results: The linear range of Cre was 1.0-1 000.0 μg/L, the linear equation was y=947.3x-1605.6, and the correlation coefficient was 0.9994. The detection limit and the limit of quantitation were 0.3, 1.0 μg/L. When the addition concentrations were 50.0, 150.0 and 450.0 μg/L, the recovery rates were 92.8%-94.6% , the intra assay precisions were 3.6%-5.7% , and the inter assay precisions were 3.4%-5.4%. The linear range of TTCA was 0.1-200.0 μg/L, the linear equation was y=1164.7x-2243.9, and the correlation coefficient was 0.9991. The detection limit and the limit of quantitation were 0.03, 0.1 μg/L. When the addition concentrations were 10.0, 40.0 and 160.0 μg/L, the recovery rates were 90.8%-93.6%, the intra assay precisions were 4.6%-7.4%, and the inter assay precisions were 4.4%-6.9%. Conclusion: The sample pretreatment process of the ultra high performance liquid chromatography tandem mass spectrometry method for the determination of Cre and TTCA in urine is simple, and the continuous determination of Cre and TTCA in urine can be realized only by switching mass spectrometry parameters under the same chromatographic conditions, which is accurate and efficient, and each performance index of the method meets the determination requirements.

[Multicenter cross-sectional investigation on the cleaning status and influencing factors of skin cleaning outside the wound in adult trauma patients]

Objective: To investigate the status and influencing factors of skin cleaning outside wound (hereinafter referred to as skin) in adult trauma patients. Methods: A multicenter cross-sectional investigation was conducted. From September 1 to 30, 2020, a total of 952 adult trauma patients who met the inclusion criteria were admitted to wound care clinics or trauma surgery wards of 13 military or local Grade Ⅲ Level A hospitals, including the General Hospital of the Eastern Theater Command of People's Liberation Army and the Army Medical Center, etc. A self-designed questionnaire on cleaning status of skin in trauma patients was released through the "questionnaire star" website to investigate basic information such as gender, age, education level, living status, and self-care ability, trauma information such as cause of injury, wound duration, trauma site, trauma depth, wound pain, wound peculiar smell, and wound cleaning solution, and skin cleaning status after injury such as whether to clean or not, cleaning method, cleaning frequency, cleaning duration in each time, or reasons for not cleaning. The patients who cleaned skin regularly after injury were included in cleaning group, and the other patients were included in no cleaning group. The basic information, trauma information, and skin cleaning status after injury of patients in 2 groups were investigated. Data were statistically analyzed with chi-square test, and binary multivariate logistic regression analysis was performed on indicators with statistically significant differences between the two groups to screen the independent influencing factors of skin cleaning in trauma patients. Results: A total of 952 questionnaires were received, and the recovery rate was 100%. Three invalid questionnaires were eliminated, and 949 valid questionnaires were obtained, with an effective rate of 99.68%. In 949 patients, there were 461 (48.6%) males and 488 (51.4%) females, aged 18-100 (50±18) years. Most patients were less than 60 years old, lived with their families, and could take care of themselves completely. Nearly half of the patients were with junior high school or below education level. The main causes of injury were sharp cutting injury and falling injury, the wound duration was 2-365 days, most of the injured parts were limbs and trunk, the wound depth was mostly full-thickness injury, and most patients had wound-related pain and no peculiar smell and used 5 g/L iodophor to clean the wound. Totally 684 (72.1%) patients cleaned their skin after injury, mainly by scrubbing with warm water, the cleaning frequency was mainly once or twice a week, and the cleaning time was mainly 10 or 15 min for each time. Totally 265 (27.9%) patients didn't clean their skin after injury, and the main causes for not cleaning were following the doctor's advice, followed by worrying about wound infection and loss of self-care ability. There were significantly statistical differences in constituent ratios of education level, self-care ability, cause of injury, wound pain, and wound peculiar smell of patients in 2 groups (χ²=12.365, 24.519, 22.820, 9.572, 92.342, P<0.01). Education level, self-care ability, cause of injury, wound pain, and wound peculiar smell were potential influencing factors of skin cleaning in patients. Binary multivariate logistic regression analysis showed that self-care ability, wound pain, and wound peculiar smell were independent influencing factors of skin cleaning in patients (odds ratio=1.51, 0.52, 3.72, 95% confidence interval=1.08-2.12, 0.42-0.89, 2.66-5.22, P<0.05 or P<0.01). Conclusions: Self-care ability, wound pain, and wound peculiar smell are independent influencing factors of skin cleaning in adult trauma patients.

Spherical reconstruction: a method for structure determination of membrane proteins from cryo-EM images

We propose a new method for single-particle reconstruction, which should be generally applicable to structure determination for membrane proteins. After reconstitution into a small spherical vesicle, a membrane protein takes a particular orientation relative to the membrane normal, and its position in the projected image of the vesicle directly defines two of its three Euler angles of orientation. The spherical constraint imposed by the vesicle effectively reduces the dimensionality of the alignment search from 5 to 3 and simplifies the detection of the particle. Projection images of particles in vesicles collectively take all possible orientations and therefore cover the whole Fourier space. Analysis of images of vesicles in ice showed that the vesicle density is well described by a simple model for membrane electron scattering density. In fitting this model we found that osmotically swollen vesicles remain nearly spherical through the freezing process. These results satisfy the basic experimental requirements for spherical reconstruction. A computer simulation of particles in vesicles showed that this method provides good estimates of the two Euler angles and thus may improve single-particle reconstruction and extend it to smaller membrane proteins.

[Study of improving professional training: effect on data collection]

In this study, 30 nurses who worked and studied in one ward were divided into three groups. They accepted one of the three measures for training, that is, lecture, teach by demonstration, and pre-practice and after practice discussion. The quality of data collecting process and data records for everyone have been checked. Result showed the quality of three groups got progress by training and the group of discussion was the best. The progress was increasing obviously with time of work and education.

[Analysis of relative factors on paralytic patients with pressure sore complications]

In this study, risk factors for bedsore were studied on 100 paralytic patients with neurologic diseases. The patient's assessment scores based on the risk factors for bedsore were evaluated and analyzed. According to the result, the critical point of assessment score for bedsore was established. The patient will be put into the high risk group of bedsore if his/her assessment score is higher than the critical point and special nursing intervention will be given.

Interactions of both melittin and its site-specific mutants with bacteriorhodopsin of Halobacterium halobium: sites of electrostatic interaction on melittin

Melittin and its site-specific mutants differentially delay the slow-decaying component of the photocycle intermediate M412 of bacteriorhodopsin in the purple membrane and the acetylated purple membrane whose several lysine residues are modified. This effect is attributed to the interaction of the total positive charges of melittin or its mutants with the total negative charges of bacteriorhodopsin. The effects of melittin and its mutants on the Triton X-100-solubilized bacteriorhodopsin monomers are somewhat complicated but are associated with their charges. These results show that there is electrostatic interaction between bacteriorhodopsin and melittin and that both N- and C-termini of melittin function as sites of the interaction, with Arg 22 and Arg 24 making a prominent contribution to the effective surface charge of melittin. Melittin, at certain concentrations, partially restores the decreased photoactivity of the bacteriorhodopsin monomers trapped in the Triton-lipid-protein mixed micelles, which suggests that melittin may compete with Triton X-100 for the binding sites on the bacteriorhodopsin monomers. Other kinds of interactions between bacteriorhodopsin and melittin are also indicated. The possible states of melittin in membranes are discussed.