The multi-molecular mechanisms of tumor-targeted drug resistance in precision medicine.

Clinically, cancer drug therapy is still dominated by chemotherapy drugs. Although the emergence of targeted drugs has greatly improved the survival rate of patients with advanced cancer, drug resistance has always been a difficult problem in clinical cancer treatment. At the current level of medicine, most drugs cannot escape the fate of drug resistance. With the emergence and development of gene detection, liquid biopsy ctDNA technology, and single-cell sequencing technology, the molecular mechanism of tumor drug resistance has gradually emerged. Drugs can also be updated in response to drug resistance mechanisms and bring higher survival benefits. The use of new drugs often leads to new mechanisms of resistance. In this review, the multi-molecular mechanisms of drug resistance are introduced, and the overcoming of drug resistance is discussed from the perspective of the tumor microenvironment.

SARS-CoV-2: The Monster Causes COVID-19.

Coronaviruses are viruses whose particles look like crowns. SARS-CoV-2 is the seventh member of the human coronavirus family to cause COVID-19 which is regarded as a once-in-a-century pandemic worldwide. It holds has the characteristics of a pandemic, which has broy -55ught many serious negative impacts to human beings. It may take time for humans to fight the pandemic. In addition to humans, SARS-CoV-2 also infects animals such as cats. This review introduces the origins, structures, pathogenic mechanisms, characteristics of transmission, detection and diagnosis, evolution and variation of SARS-CoV-2. We summarized the clinical characteristics, the strategies for treatment and prevention of COVID-19, and analyzed the problems and challenges we face.

[Effect of ultrasonic in instrumentation on curved and obstructed root canal preparation].

PURPOSE: To investigate and evaluate the effect of ultrasonic instrumentation on curved and obstructed root canal preparation. METHODS: Ultrasonic preparation was used on 117 root canals of 92 teeth due to resinifying therapy, pulp mummification and aging which could not be reopened and treated with traditional methods. RESULTS: 108 canals were successfully reopened with a successful rate of 92.3%. Failure occurred in 9 cases. 2 of them were lateral perforation. 2 were obstructed on curving position. 2 of them were due to pulp calcification in older patients. 3 were failing after resinifying therapy. CONCLUSION: The ultrasonic treatment of root canal was an effective and safe method. It was still limited in a cases with pulp calcification and some fine root canals treated by resinifying therapy.