Clustered regulatory interspaced short palindromic repeats (CRISPR) found in bacteria and archaea genome that contains multiple short repeats loci, provides acquired immunity against invading foreign DNA via RNA-guided DNA cleavage. The first inkling of this hot new genetic engineering tool turned up in 1987, when a research team observed an oddly repetitive sequence at one end of a bacterial gene. Now three types of CRISPR/Cas system have been identified: types I, II and III. In the type II CRISPR/Cas9 system, short segments of foreign DNA termed 'spacers' are integrated within the CRISPR genomic loci, transcribed and processed into short CRISPR RNA (crRNA). These crRNAs anneal to trans-activating crRNA (tracrRNA) and direct sequence-specific cleavage in that a double-strand break (DSB) is generated by Cas proteins. Based on these findings, various genetic methods, including gene targeting (Gene disruption), gene insertion, gene correction etc., are being designed to manipulate the genomes of different species at specific loci. Compared with zinc finger nucleases (ZFN) and transcription activator-like effector nucleases (TALEN), CRISPR/Cas9 is simpler with higher specificity and less toxicity. This review summarizes recent progress, discusses the prospects of CRISPR/Cas9 system, with an emphasis on its structure, principle, applications and potential challenges, and provides a useful reference for researchers who are interested in this new technique.
Bacteria ; CRISPR-Cas Systems ; DNA ; Genetic Engineering ; Genomics ; RNA

Based on the research of risk assessment of medical equipment safety and operation to formulate evaluation criteria and methods of how to use the practical management work. Objective to evaluate the practical method is to use and the risk of adverse events of medical equipment in operation risk in order to find the risk, control risk, ensure safety in time, so that Improve the level of risk management of medical equipment.
Equipment Safety ; Humans ; Risk Assessment ; Risk Management

Vascular dementia (VaD) is one of the most common dementia types in the elderly population. Its incidence is only second to Alzheimer's disease. At present, the diagnosis of VaD mainly based on the clinical manifestations, neuroimaging and neuropsychological scales of the patients. It still lacks higher sensitive and specific metabolism indexes. Magnetic resonance spectroscopy is a noninvasive technique for detecting the energy of living tissues and the changes of metabolism. In recent years, it has been more and more used to patients with VaD and has achieved initial results in the diagnosis, differential diagnosis and cognition-related studies of

Objective To study the effect of different dialysis modalities on pruritus in uremic patients .Methods Patients with maintenance hemodialysis who were suffered with severe cutaneous pruritus were randomly divided into hemodialysis group (HD group) ,hemodialysis combined with hemodiafiltration group (HD+ HDF group) ,hemodialysis and hemodiafiltration combined with hemoperfusion group (HD+ HDF+ HP group) .Plasma P3+ ,parathyroid hormone (PTH) and β2-microglobulin (β2-MG) were measured at pre-dialysis ,1 weeks ,4 weeks and 12 weeks after dialysis ,cutaneous pruritus was scored too .Results Compared with pre-dialysis ,the level of plasma P3+ ,PTH ,β2-MG and the scores of cutaneous pruritus were significantly lower at 4 weeks and 12 weeks after dialysis in HD+ HDF+ HP group (P<0 .05) .The were statistically significant difference in P3+ ,PTH ,β2-MG and cu-taneous pruritus scores among 3 groups after 12 weeks (P<0 .05) .Conclusion HD+ HDF+ HP is superior to HD+ HDF in effi-ciently clear P3+ ,PT H andβ2-M G ,and relief cutaneous pruritus and itching .

The clinical classification of metastatic spinal tumors is based on the degree of malignancy, nervous system function, osteoclasia, and prognosis of patients. The application of this classification system is relatively simple. The assessment and evaluation of patients to estimate the period of survival can guide the individualized treatment of patients. Patients with clear surgical indications can choose to undergo a palliative operation, tumor resection, or total spondylectomy. Alternatively, other patients can opt to have mini-mally invasive surgery aside from the normal surgical approach. Stereotactic radiotherapy and intensity-modulated radiation therapy combined with the use of radiofrequency ablation, radiation, and other therapies can achieve local tumor control, relieve pain, and main-tain normal neurological function. Thus, the quality of life of the patient is improved. Percutaneous vertebroplasty, radiofrequency abla-tion, spinal endoscopy, and other modern forms of minimally invasive surgery will have more applications in the treatment of spinal metastatic tumors.

Objective:To study the mesiodistal teeth size and the relationship between upper and lower teeth dimension of normal occlusion from Han Chinese in Xi'an. Methods: 52 males and 55 females with normal occlusion were selected. The mesiodistal width of each tooth was measured using a vernier gauge caliper. Statistical analysis was performed. Results: For the 107 cases with normal occlusion, the mean and standard deviation of the teeth size were calculated. There were significant differences between males and females in maxillary incisors, canines, first molar and mandibular canines, premolars. The normal range was obtained for the anterior and overall tooth size ratio(anterior ratio:78.32?3.01 overall ratio:91.10?2.27); and the regression equation that was used to quantify the tooth size discrepancies was expressed according to the significant correlation between the upper and lower tooth (r anterior=0.754, rtotal=0.851). Conclusion: There is a relationship between upper and lower teeth dimension. Sex difference should be considered when tooth size was used in clinic.

Objective:To compare the difference between the measurement methods of wire and divider applied in the measurement of arch length at orthodontic dental model analysis.Methods:80 pairs of dental models were selected,including 40 normal occlusion models and 40 crowded models.The arch length of every model was measured by the wire and divider methods respectively,and the casual error and paired t test was subsequently employed to compare the difference between the measurements data.Results:The variance coefficients of the dental lengths measured by the divider method was larger than those measured by the wire method in both crowding and normal occlusion(P

Objective To compare the long-term outcome between breast-conserving therapy with mastectomy therapy for early stage invasive breast cancer through a Meta analysis of the randomized controlled trials published worldwide.Methods Cochrane systematic evaluation was used to search through Cochrane libraries of clinical comparative trials,PubMed,Embase,Cancer Lit,and so on.The quality of literatures was independently evaluated and cross-checked by two evaluators,indicators for assessment including death number at the end of follow-up,locoregional and total recurrence.The results were analyzed with RevMan 4.2.2 software.Results Six articles were involved in the Meta analysis with total 3 933 patients.No statistical difference was found in the death at the end of follow-up between breast-conserving therapy group and mastectomy therapy group(OR=1.05,95% CI=0.93-1.19,P=0.45).Locoregional and total recurrence rate of breast-conserving therapy group were statistical higher than those in mastectomy therapy group(OR=1.64,95% CI:1.10-2.44,P=0.01;OR=1.42,95% CI:1.22-1.64,P

Objective:To investigate the relationship of TNF-A-863 and CGRP979 gene polymorphisms with the susceptibility to severe chronic periodontitis in Chinese.Methods:Buccal swabs were collected from 100 adult patients with severe chronic periodontitis and 118 healthy adult controls.DNA was extracted from each subjects of the two groups.PCR-LDR technique was used to identify the genotypes of TNF-A-863 and CGRP979.The difference in the genotypes between the two groups was analyzed by statistics software.Results:The genotype of TNF-A-863 was mainly TNF-A-863 A/C in patients with severe chronic periodontitis and TNF-A-863 C/C in healthy controls.There were significant differences in TNF-A-863 distribution between the two groups(P

Background and purpose:Nausea and vomiting were the most common side effects of chemotherapy and they are difficult to control especially in terms of delayed nausea and vomiting induced by CDDP. Acupuncture treatment is popularly the traditional medical method used in China,being economic and easy to carry out.This research is to study the role of acupuncture treatment in the prevention of NP regimen induced delayed nausea and vomiting. Methods:26 patients with NSCLC were enrolled into a randomized double blind crossover trial. The patients received either hydrochloride ondostrone+Dexm+acupuncture treatment(the first cycle of chemotherapy) →hydrochloride ondostrone+Dexm (the second cycle of chemotherapy)(defined as AB group) or hydrochloride ondostrone+Dexm (the first cycle of chemotherapy)→hydrochloride ondostrone+Dexm+acupuncture treatment (the second cycle of chemotherapy)( defined as BA group).Results:Twenty six patients were evaluated. The complete controls of nausea for the AB group with acupuncture treatment were 96.15%, 96.15%, 76.92%, 84.62%, 92.31% and 100.00% for day 1-6, respectively, for the BA group without acupuncture treatment were 100.00%, 76.92%, 57.69%, 34.62%, 65.38% and 76.92%, respectively. There were statistically difference in terms of the control of nausea for day 3-5(P