SUMMARY: Gastrin plays a vital role in the development and progression of gastric cancer (GC). Its expression is up-regulated in GC tissues and several GC cell lines. Yet, the underlying mechanism remains to be investigated. Here, we aim to investigate the role and mechanism of gastrin in GC proliferation. Gastrin-overexpressing GC cell model was constructed using SGC7901 cells. Then the differentially expressed proteins were identified by iTRAQ analysis. Next, we use flow cytometry and immunofluorescence to study the effect of gastrin on the mitochondrial potential and mitochondria-derived ROS production. Finally, we studied the underlying mechanism of gastrin regulating mitochondrial function using Co-IP, mass spectrometry and immunofluorescence. Overexpression of gastrin promoted GC cell proliferation in vitro and in vivo. A total of 173 proteins were expressed differently between the controls and gastrin- overexpression cells and most of these proteins were involved in tumorigenesis and cell proliferation. Among them, Cox17, Cox5B and ATP5J that were all localized to the mitochondrial respiratory chain were down-regulated in gastrin-overexpression cells. Furthermore, gastrin overexpression led to mitochondrial potential decrease and mitochondria-derived ROS increase. Additionally, gastrin-induced ROS generation resulted in the inhibition of cell apoptosis via activating NF-kB, inhibiting Bax expression and promoting Bcl-2 expression. Finally, we found gastrin interacted with mitochondrial membrane protein Annexin A2 using Co-IP and mass spectrometry. Overexpr ession of gastrin inhibits GC cell apoptosis by inducing mitochondrial dysfunction through interacting with mitochondrial protein Annexin A2, then up-regulating ROS production to activate NF-kB and further leading to Bax/Bcl-2 ratio decrease.

RESUMEN: La gastrina juega un papel vital en el desarrollo y progresión del cáncer gástrico (CG). Su expresión está regulada al alza en tejidos de CG y en varias líneas celulares de CG. Sin embargo, el mecanismo subyacente aun no se ha investigado. El objetivo de este estudio fue investigar el papel y el mecanismo de la gastrina en la proliferación de CG. El modelo de células CG que sobre expresan gastrina se construyó usando células SGC7901. Luego, las proteínas expresadas diferencialmente se identificaron mediante análisis iTRAQ. A continuación, utilizamos la citometría de flujo y la inmunofluorescencia para estudiar el efecto de la gastrina en el potencial mitocondrial y la producción de ROS derivada de las mitocondrias. Finalmente, estudiamos el mecanismo subyacente de la gastrina que regula la función mitocondrial utilizando Co-IP, espectrometría de masas e inmunofluorescencia. La sobreexpresión de gastrina promovió la proliferación de células CG in vitro e in vivo. Un total de 173 proteínas se expresaron de manera diferente entre los controles y las células con sobreexpresión de gastrina y la mayoría de estas proteínas estaban implicadas en la tumorigenesis y la proliferación celular. Entre estas, Cox17, Cox5B y ATP5J, todas localizadas en la cadena respiratoria mitocondrial, estaban reguladas a la baja en las células con sobreexpresión de gastrina. Además, la sobreexpresión de gastrina provocó una disminución del potencial mitocondrial y un aumento de las ROS derivadas de las mitocondrias. Por otra parte, la generación de ROS inducida por gastrina resultó en la inhibición de la apoptosis celular mediante la activación de NF-kB, inhibiendo la expresión de Bax y promoviendo la expresión de Bcl-2. Finalmente, encontramos que la gastrina interactuaba con la proteína de membrana mitocondrial Anexina A2 usando Co-IP y espectrometría de masas. La sobreexpresión de gastrina inhibe la apoptosis de las células CG al inducir la disfunción mitocondrial a través de la interacción con la proteína mitocondrial Anexina A2, luego regula el aumento de la producción de ROS para activar NF-kB y conduce aún más a la disminución de la relación Bax/Bcl-2.

Abstract Long non-coding RNA AK001796 was initially identified altered in lung cancer. Recent research showed it could participate in the prognosis of hepatocellular carcinoma (HCC). However, the general biological role of AK001796 and its underlying mechanisms in HCC remain unclear. Here we demonstrated that the expression level of AK001796 in HCC tissues and cell lines was up-regulated. Silencing AK001796 suppressed the proliferation ability of HCC cells. Through dual luciferase reporter assays and loss/gain of functions studies, we identified that AK001796 could bind to miR-150, a star microRNA, promoting HCC proliferation. Furthermore, it was reported that growth factor receptor binding protein 2-associated binder 1 (GAB1) is a target gene of miR-150. Owing to AK001796 being a decoy for miR-150 and binding the same putative sites of miR-150 as GAB1, we presented that inhibition of miR-150 in AK001796 silencing cells reversed the reduction in GAB1. Subsequently, our findings demonstrated that silencing AK001796 can impair phospho-ERK1/2 and phospho-AKT. In conclusion, our investigation revealed that AK001796 promoted proliferation by enhancing phospho-ERK1/2 and phospho-AKT through AK001796/miR-150/GAB1 axis in HCC. These results provided further evidence for the critical roles of AK001796 accumulating HCC and suggested that AK001796 might act as an HCC biomarker in clinical treatment.

ABSTRACT Purpose: To observe the effect of puerarin on renal ischemia-reperfusion (I/R) injury in rats, and to explore its mechanism based on NLRP3/Caspase-1/GSDMD pathway. Methods: Twenty-one Sprague-Dawley rats were divided into three groups: sham-operated group (sham), model group (RIRI), and puerarin treatment group (RIRI + Pue). The model of acute renal I/R injury was established by cutting the right kidney and clamping the left renal pedicle for 45 min. Results: Renal function parameters were statistically significant in group comparisons. The renal tissue structure of rats in sham group was basically normal. Pathological changes were observed in the RIRI group. The renal pathological damage score and apoptosis rate in the RIRI group were higher than those in the sham group, and significantly lower in the RIRI + Pue group than in the RIRI group. Indicators of oxidative stress–superoxide dismutase, malondialdehyde, and glutathione peroxidase–were statistically significant in group comparisons. Compared with the sham group, the relative expressions of NLRP3, Caspase-1 and GSDMD proteins in the RIRI group were increased. Compared with the RIRI group, the RIRI + Pue group had significant reductions. Conclusions: Puerarin can inhibit the activation of NLRP3/Caspase-1/GSDMD pathway, inhibit inflammatory response and pyroptosis, and enhance the antioxidant capacity of kidney, thereby protecting renal I/R injury in rats.

Abstract Introduction: Noise-induced hearing loss is one of the most common forms of sensorineural hearing loss. Nevertheless, the mechanisms of noise-induced hearing loss are still not fully understood. Objective: To investigate the dynamics of inflammatory responses in the mammalian cochlea following noise trauma at two different times, once during the light cycle and once during the dark. Methods: We challenged C57BL/6J mice with moderate, continuous noise trauma at either 9 a.m. or 9 p.m. Auditory function, histological changes in hair cells, and modifications in gene expression levels of inflammatory mediators were assessed at specific time points. Shifts in auditory brainstem response thresholds were measured at 1, 3, 7 and 14 days after noise exposure to measure potential noise-induced hearing loss. Cochlear basilar-membrane immunofluorescent staining was performed at 3 and 14 days after noise exposure. The mRNA levels of several inflammatory mediators were measured via quantitative real-time polymerase chain reaction before (pre) and after (0, 3, 12, 24 and 72 h) noise exposure. Results: We found that all noise-exposed mice developed a temporary threshold shift and that there were no significant differences between daytime and nighttime noise exposures in terms of inducing hearing-threshold shifts. Similarly, we did not detect significant histological changes in hair cells between these two groups. However, we discovered an interesting phenomenon in that the peak mRNA levels of IL-1β, IL-6, CCL2 and TNF-α were higher in day noise-exposed mice compared to those in night noise-exposed mice, and these mRNA levels subsided more slowly in day noise-exposed mice. Conclusion: Overall, these observations suggest that the circadian timing of noise exposure has a significant effect on noise-induced inflammatory responses in the mouse cochlea and that a greater inflammatory response might occur after daytime exposure.

SUMMARY OBJECTIVE: Stroke-associated pneumonia is an infection that commonly occurs in patients with spontaneous intracerebral hemorrhage and causes serious burdens. In this study, we evaluated the validity of the Braden scale for predicting stroke-associated pneumonia after spontaneous intracerebral hemorrhage. METHODS: Patients with spontaneous intracerebral hemorrhage were retrospectively included and divided into pneumonia and no pneumonia groups. The admission clinical characteristics and Braden scale scores at 24 h after admission were collected and compared between the two groups. Receiver operating characteristic curve analysis was performed to assess the predictive validity of the Braden scale. Multivariable analysis was conducted to identify the independent risk factors associated with pneumonia after intracerebral hemorrhage. RESULTS: A total of 629 intracerebral hemorrhage patients were included, 150 (23.8%) of whom developed stroke-associated pneumonia. Significant differences were found in age and fasting blood glucose levels between the two groups. The mean score on the Braden scale in the pneumonia group was 14.1±2.4, which was significantly lower than that in the no pneumonia group (16.5±2.6), p<0.001. The area under the curve for the Braden scale for the prediction of pneumonia after intracerebral hemorrhage was 0.760 (95%CI 0.717–0.804). When the cutoff point was 15 points, the sensitivity was 74.3%, the specificity was 64.7%, the accuracy was 72.0%, and the Youden's index was 39.0%. Multivariable analysis showed that a lower Braden scale score (OR 0.696; 95%CI 0.631–0.768; p<0.001) was an independent risk factor associated with stroke-associated pneumonia after intracerebral hemorrhage. CONCLUSION: The Braden scale, with a cutoff point of 15 points, is moderately valid for predicting stroke-associated pneumonia after spontaneous intracerebral hemorrhage.

Abstract Curcumin has been found to have anti-cancer role in many cancer, including colorectal cancer (CRC). However, it is not clear whether curcumin can be involved in CRC progression by mediating the circRNA regulatory axis. Curcumin inhibited the proliferation, migration, invasion, and promoted the apoptosis of CRC cells. Circ_KIAA1199 was an upregulated circRNA in CRC, and its overexpression could reverse the negative regulation of curcumin on CRC progression. MiR-433-3p was found to be sponged by circ_KIAA1199, and its mimic abolished the regulation of circ_KIAA1199 overexpression on the progression of curcumin-treated CRC cells. ADAM10 was a target of miR-433-3p and its expression was regulated by circ_KIAA1199 and curcumin. The suppressive effect of miR-433-3p inhibitor on the progression of curcumin-treated CRC cells could be reversed by ADAM10 silencing. Also, curcumin reduced CRC tumor growth by regulating the circ_KIAA1199/miR-433-3p/ADAM10 axis in vivo. Our data showed that curcumin could restrain CRC progression, which was achieved through the circ_KIAA1199/miR-433-3p/ADAM10 pathway.

Abstract The present study aimed to determine whether oleanolic acid (Ole) could be used to treat psoriasis and its related underlying mechanism of action via in vitro analysis. HaCaT cells were stimulated with IL-22 to established an in vitro psoriasis cell model. MTT, flow cytometry and TUNEL assays, respectively. Transmission electron microscopy was used to observe the cell ultrastructure. LC3B protein expression levels were analyzed using immunofluorescence, other protein expression levels were determined using western blotting. Cell viability was significantly increased, while the apoptotic rate was significantly decreased in the model group (P < 0.001). In addition, Notch1, Hes1, beclin 1 and LC3B protein expression levels were significantly downregulated, while P62 protein expression levels were significantly upregulated in the model group compared with the control group (P < 0.001). Supplementation of Ole, the increased levels of proliferation were significantly suppressed, while cell apoptosis was significantly increased (P < 0.05) in a dose-dependent manner, which was discovered to occur via Notch1 upregulation. Notably, the transfection with small interfering RNA-Notch1 significantly reversed the effect of Ole treatment (P < 0.001) and the levels of autophagy were also decreased. In conclusion, the findings of the current study suggested that Ole may relieve psoriasis via upregulating Notch1, which subsequently regulates cell autophagy.

Abstract Objectives: This study sought to further verify the protective mechanism of Melatonin (MT) against ovarian damage through animal model experiments and to lay a theoretical and experimental foundation for exploring new approaches for ovarian damage treatment. Method: The wet weight and ovarian index of rat ovaries were weighted, and the morphology of ovarian tissues and the number of follicles in the pathological sections of collected ovarian tissues were recorded. And the serum sex hormone levels, the key proteins of the autophagy pathway (PI3K, AKT, mTOR, LC3II, LC3I, and Agt5) in rat ovarian tissues, as well as the viability and mortality of ovarian granulosa cells in each group were measured by ELISA, western blotting, CCK8 kit and LDH kit, respectively. Results: The results showed that MT increased ovarian weight and improved the ovarian index in ovarian damage rats. Also, MT could improve autophagy-induced ovarian tissue injury, increase the number of primordial follicles, primary follicles, and sinus follicles, and decrease the number of atretic follicles. Furthermore, MT upregulated serum AMH, INH-B, and E2 levels downregulated serum FSH and LH levels in ovarian damage rats and activated the PI3K/AKT/mTOR signaling pathway. Besides, MT inhibited autophagic apoptosis of ovarian granulosa cells and repressed the expression of key proteins in the autophagic pathway and reduced the expression levels of Agt5 and LC3II/I. Conclusions: MT inhibits granulosa cell autophagy by activating the PI3K/Akt/mTOR signaling pathway, thereby exerting a protective effect against ovarian damage.

ABSTRACT The objective of this trial was to investigate the potential benefits of enzyme and probiotic supplementation on the growth performance, nutrient digestibility, carcass traits, and meat quality of Simmental cattle. Sixty Simmental steers (367.75±4.69 kg) were randomly divided into three groups: control (fed basal diet), BC1 group (fed basal diet and 10 g/d brewer’s yeast and cellulase supplementation per cattle), and BC2 group (fed basal diet and 20 g/d brewer’s yeast and cellulase supplementation per cattle). A 10-d preparation period was followed by a 120-d experimental period. The results showed that the final weight of the BC2 group was greater than that of the control group. Also, feed conversion ratio of the BC2 group was better than that of the control group. Net meat weight increased by 3.86% in the BC2 group compared with the control group. The apparent digestibility of neutral detergent fiber, acid detergent fiber, and crude protein of the BC2 group was greater than that of the control group. Dietary supplementation with brewer’s yeast and cellulase supplementation could improve the growth performance and nutrient digestibility of Simmental cattle.

Abstract Chuju polysaccharide, which is extracted from a traditional Chinese flower, contains diabetes benefits. In this study, the free radical scavenging ability and reducing force of the Chuju polysaccharides were determined. The Chuju polysaccharides were given intragastrically to the diabetic mice. Results have shown that three Chuju polysaccharides had certain scavenging effects on DPPH radical, hydroxyl radical and superoxide anion radical, which are stronger than VE, but weaker than VC. The scavenging effects of three Chuju polysaccharides on hydroxyl radical were as follows: D2 > D1 > D3. The reducing force of the three components was also shown as the same, indicating that Chuju polysaccharide had strong antioxidant activity. According to the histological anatomy and pathological section analysis of mice, the three components of Chuju polysaccharide could have a certain protective effect on liver, kidney and pancreas. The components with stronger antioxidant activity contain a more significant protective effect. Together, these findings indicated that Chuju polysaccharides possess great potential as a diet supplement or medication for diabetes.

Abstract To investigate effect and mechanism of maternal exposure to trace cadmium on the differentiation and development in testis of male offspring rats. Thirty-two pregnant female SD rats were randomly divided into 4 groups: CdCl2 treated group (group A) was intraperitoneally injected with CdCl2 (1.5 mg/kg.d); DES group(group B) was subcutaneously injected with DES (100 μg/kg.d); CdCl2 +TMX group(group C) was treated with CdCl2 (same as above)+TMX (50 mg/kg.d); control group (group D) was treated with the same dose normal saline instead of CdCl2. On day 30th after parturition, the weight and sex ratio of off-spring male rats were recorded; Offspring testes were used for ultrastructural observation. Ultrastructural changes including swollen mitochondria and expanded endoplasmic reticulum in Sertoli cells, gonocyte and Leydig cells, moreover, lipid droplets cumulated in Leydig cells were observed in group A and group B, and so changes in group C were slightly more than those in group A or group B. The expression of StAR and inhibin-B in Leydig cells decreased significantly in group A and group B (p < 0.05), but there were no difference between group C and group D (P > 0.05). Cadmium has similar effect as estrogen which would affect gonadal differentiation and development in male fetal rats.

RESUMO: A aplicação de herbicidas é um método eficaz de controle de ervas daninhas para mitigar a perda de produtividade das culturas. No entanto, o uso excessivo de herbicidas pode causar toxicidade em plantas não alvo. O presente estudo avaliou os efeitos da dose recomendada para aplicação agrícola (0.45 kg ha-1) e dose excessiva (0.90 kg ha-1) de glufosinato no desempenho fotossintético e assimilação de nitrogênio das variedades de colza D148 e Zhongshuang 11 (ZS11). Ambas as concentrações de glutamato diminuíram significativamente o teor de clorofila e compostos azotados, exceto a prolina livre, e a atividade de síntese da glutamina e de síntese de glutamato, e aumentaram a atividade de desidrogenase do ácido glutâmico em ambas as variedades. Quando a concentração de glifosato foi 0.45 kg ha-1, a assimilação de azoto das duas variedades diminuiu, o que indicou que a dosagem recomendada de glifosato inibiu a assimilação de azoto das duas variedades de colza. Entretanto, a taxa fotosintética líquida do D148 aumentou enquanto o do ZS11 diminuiu, o que significa que o D148 é mais tolerante a dose recomendada de glifosato do que o ZS11. A dose de 0.90 kg ha-1 de glifosato foi prejudicial para as mudas de duas variedades de colza. Em geral, os nossos resultados indicam que o uso excessivo de glufosinato inibe a taxa fotossintética e a assimilação de nitrogênio em mudas de colza, sendo essencial aplicar uma dose adequada deste herbicida com base na variedade cultivada para minimizar os efeitos adversos nas culturas e no meio ambiente.

ABSTRACT: Herbicide application is an effective weed control method for mitigating crop yield loss; however, herbicide overuse can cause toxicity in non-target plants. The present study evaluated the effects of glufosinate at recommended dose for agricultural application (0.45 kg ha-1) and at overuse dose (0.90 kg ha-1) glufosinate application on photosynthetic performance and nitrogen assimilation of the rapeseed varieties D148 and Zhongshuang 11 (ZS11). Both glufosinate concentrations significantly decreased the content of chlorophyll and nitrogenous compounds, except free proline, and the activity of glutamine synthetase and glutamate synthase, and increased the activity of glutamic acid dehydrogenase in both varieties. When the concentration of glyphosate was 0.45kg ha-1, the nitrogen assimilation of the two varieties decreased, which indicated that the recommended dosage inhibited the nitrogen assimilation of the two varieties; however, the increase of net photosynthetic rate of D148 and the decrease of that of ZS11 mean that D148 is more tolerant to the recommended dose of glyphosate than ZS11. The 0.90 kg ha-1 dosage was toxic to both rapeseed varieties. Overall, our results indicated that herbicide overuse inhibited the photosynthetic rate and nitrogen assimilation in rapeseed seedlings, and it is essential to apply a suitable glufosinate dose based on the variety grown to minimize adverse effects on crops and environment.

In this study, the effects of sea-buckthorn (Hippophae rhamnoides L.) leaves (SL) on the biochemical parameters and metabolomic profiling in Altay lamb (Ovis aries) were observed. Sixty six-month-old male Altay lambs (body weight 28.0 ± 3.5 kg) were randomly assigned to four groups (n=15). The experimental groups were named as CON, 2.5%, 5.0% and 7.5%. The group CON, contained animals fed with a basal diet. Animals of the other groups were fed a treatment diet consisting of 2.5% (Group 2.5%), 5.0% (Group 5.0%) and 7.5% (Group 7.5%) SL. The experimental period lasted 56 days. The results showed that the average daily gain (ADG) and average daily feed intake (ADFI) increased with the increase in the levels of dietary SL. Dietary SL showed a direct relationship with total protein (TP), albumin, globulin and total cholesterol (TC) content of the experimental animals. However, an indirect relationship was observed between dietary SL and the concentration of urea nitrogen (UN). The concentrations of glucose, high -density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) showed quadratic change. Additional changes occurred in the endogenous metabolites involving multiple pathways. The pathways were tricarboxylic acid (TCA) cycle, the metabolism of protein and amino acid and the metabolism of fatty acid and steroid. The changes in metabolites primarily revealed an increase in amino acids and carbohydrates and a decrease in lipid metabolites. These findings provide a comprehensive insight into the effects of the metabolic aspects of sea-buckthorn leaves on Altay lambs. In addition, the present research results provide a better understanding to the development and utilization of sea-buckthorn as a healthy additive for small ruminant production.

Cervical cancer is one of the most common cancers among women around the world. However, the underlying mechanism involved in cervical cancer progression is incompletely known. In the present study, we determined the role of glycoprotein nonmetastatic melanoma protein B (GPNMB) in tumorigenesis of cervical cancer. According to the GEO database, we found that GPNMB expression was significantly higher in cervical cancer than in normal cervix epithelium. A similar pattern was observed in GPNMB expression in cultured cervical cancer cells and normal cervical epithelial cells. Compared with the control, GPNMB knockdown significantly decreased the proliferation and migration capacity, but enhanced the apoptosis capacity of SiHa and HeLa cells. Additionally, the activity of MMP-2 and MMP-9 were aberrantly increased in SiHa and HeLa cells compared with normal cervical epithelial cells, whereas their activities were strongly inhibited by GPNMB siRNA. Furthermore, Wnt/β-catenin signaling was activated by GPNMB in SiHa and HeLa cells. Increased MMP-2/MMP-9 expression was suppressed by Dkk-1, inhibitor of Wnt/β-catenin signaling, while it was enhanced by stimulator BIO. The proliferation, migration, and apoptosis capacity of HeLa cells were found to be affected by Dkk-1 and BIO to different extents. In conclusion, we demonstrated that GPNMB contributed to the tumorigenesis of cervical cancer, at least in part, by regulating MMP-2/MMP-9 activity in tumor cells via activation of canonical Wnt/β-catenin signaling. This might be a potential therapeutic target for treating human cervical cancer.

Resumen Introducción: Neumonía adquirida por en la comunidad (NAC) es una enfermedad responsable por un gran número de muertes y un impacto económico importante. Debido a que el diagnostico incrementó la sensibilidad, se cambió la etiología de la NAC. Adicionalmente, Mycoplasma pneumoniae es uno de los patógenos que causan la NAC. Los macrólidos y antibióticos relacionados son la primera línea de tratamiento para M. pneumoniae. La resistencia a macrólidos se aumentó en los últimos 15 años y ahora se encuentra distribuido en todo el mundo. Nosotros realizamos el primer estudio de resitencia a M. pneumoniae a los macrólidos en Yantai. Esto podría ser útil para determinar una terapia apropiada para NAC en esta población. Objetivo: Investigar la tasa y el mecanismo para la resitencia a los macrólidos en Yantai. Métodos: Se colectaron muestras faringeas usando un hisopo. Las muestras se analizaron mediante la reacción en cadena de la polimerasa (PCR) y por cultivo para M. pneumoniae. Se uso una PCR anidad para amplificar fragmentos del gen 23S rRNA especifico con las mutaciones para M. pneumoniae. Se analizaron amplicomes por CE-SSCP para determinar la resitencia a los macrólidos. Estos resultados se confirmaron por secuenciación. Se aislaron 27 cepas de M. pneumoniae y se probaron nueve antibióticos in vitro. Resultados: De 128 muestras, 27 fueron positivas para M. pneumoniae. Se determinó una resistencia a macrólidos por Mycoplasma del 100%. Los mecanismos de esta resitencia fue una mutacion punctual A2063G en la secuencia que se une directamente a los macrólidos en el dominio 23S rRNA V in vitro. El tiempo piotolítico medio para el grupo de fluoroquinolonas fue 4.7 ±2.9 d, que fue significativamente más corto que para el grupo de azitromicina: 8.2 ±4.1 d. Conclusiones: Los macrólidos no son la primera linea de tratamiento para las infecciones del tracto respiratorio contra M. pneumoniae respiratory tract infections en Yantai.

Abstract Introduction: Community-acquired pneumonia (CAP) is a global disease responsible for a large number of deaths, with significant economic impact. As diagnostic tools have increased in sensitivity, understanding of the etiology of CAP has begun to change. Mycoplasma pneumoniae is one of the major pathogens causing CAP. Macrolides and related antibiotics are first-line treatments for M. pneumoniae. Macrolide resistance has been spreading for 15 years and now occurs in worldwide. We undertook the first study on macrolide resistance of M. pneumoniae in Yantai. This may be helpful to determine the appropriate therapy for CAP in this population. Objective: To investigate the rate and mechanism of macrolide resistance in Yantai. Methods: Pharyngeal swab samples were collected from adult CAP patients. Samples were assayed by polymerase chain reaction (PCR) and cultivated to test for M. pneumoniae. Nested PCR was used to specifically amplify M. pneumoniae 23S rRNA gene fragments containing mutations, and amplicons were analyzed by CE-SSCP for macrolide resistance mutations. Results were confirmed by sequencing. Twenty-seven strains of M. pneumoniae were isolated and the activities of nine antibiotics against M. pneumoniae were tested in vitro. Results: Out of 128 samples tested, 27 were positive for M. pneumoniae. Mycoplasma 100% macrolides resistance to Mycoplasma pneumoniae. The mechanism of macrolides resistance was A2063G point mutation in the sequence directly binding to macrolides in the 23S rRNA V domain in vitro. The mean pyretolytic time for the fluoroquinolone group was 4.7 ±2.9 d, which was significantly shorter than 8.2 ±4.1 d for the azithromycin group. Conclusions: Macrolides are not the first-line treatment for M. pneumoniae respiratory tract infections in Yantai.