Prevalence, resistance phenotypes, and fluoroquinolone resistance genes of Salmonella isolates from raw milk of healthy dairy cows in Henan province, China.

OBJECTIVE: Salmonella isolates have been discovered in many regions of the world. We investigated the prevalence and resistance of Salmonella isolates in raw milk of healthy dairy cows on farms in different regions of Henan Province, China. MATERIALS AND METHODS: From July 2020 to November 2021, 422 raw milk samples were collected. The minimum inhibitory concentrations (MICs) of 16 antimicrobial agents against 89 Salmonella strains detected from the raw milk samples were determined using the broth microdilution method, and the resistance genes for fluoroquinolones were identified using polymerase chain reaction. RESULTS: Eighty-nine (21.09%) Salmonella isolates were recovered from 422 raw milk samples. The Salmonella strains exhibited high resistance to amoxicillin (100.00%), tylosin (95.50%), and lincomycin (95.50%). Additionally, tigecycline showed good activity against Salmonella, with an MIC50 of 0.25 µg/mL. All Salmonella isolates showed multidrug resistance (MDR), and >50% of the strains showed resistance to more than six antimicrobials. The strains from Jiaozuo exhibited 100% resistance to amoxicillin, terramycin, tylosin, and lincomycin. Two efflux pump genes, oqxA and oqxB, had the highest carrying rates of 66.29% and 64.04%, respectively. Additionally, the carrying rates of oqxA and oqxB were high in Shangqiu, Zhengzhou, and Jiaozuo. The carrying rates of aac(6')-Ib-cr in Shangqiu and Zhengzhou were 33.33% and 38.46%, respectively. CONCLUSIONS: This study revealed a high prevalence of Salmonella isolates obtained from raw milk of healthy dairy cows in different regions of Henan Province, China. The Salmonella strains exhibited various degrees of MDR. Salmonella can be transmitted to humans via consumption of contaminated raw milk; thus, the presence of resistance genes poses a potential threat to public health, highlighting the need for vigilant monitoring of Salmonella isolates.

Surface Characteristics and Hydrophobicity of Ni-Ti Alloy through Magnetic Mixed Electrical Discharge Machining.

Nickel⁻titanium (Ni-Ti) alloy has been selected as stent material given its good biocompatibility. In this study, experimental research on this material was conducted using magnetic field-assisted electrical discharge machining (EDM). The surface topography of the machined workpiece was analyzed with a scanning electron microscope (SEM). Hydrophobicity was measured by using an optical contact angle measuring instrument. The roughness values of different positions on the surface were measured using a TR200 roughness instrument. Results showed that the composite structure of solidification bulge⁻crater⁻pore⁻particle can be prepared on the surface of the Ni-Ti alloy through magnetic mixed EDM using suitable processing parameters. Moreover, the contact angle of the surface reaches 138.2°.

Evidence for the simultaneous translocation of muscarinic acetylcholine receptor and G protein by carbachol.

Interactions between guanine nucleotide regulatory proteins (G proteins) and muscarinic acetylcholine receptors (mAChRs) were studied in vivo following carbachol treatment. Rat brain homogenates were separated by high speed ultracentrifugation into heavy and light membrane and 300,000 g supernate fractions. The G proteins were partially purified by Sephadex-G200 and heptylamine-Sepharose and the mAChRs by (3,2'-aminobenzhydryloxy)-tropane-(ABT)-affinity chromatographies. Radioligand binding assays showed that acute carbachol induced a biphasic translocation of the mAChRs and G proteins into the light membrane fraction with an initial release at 5-10 min and a second phase at 60 min. Portions of the released mAChRs and the G proteins, were found in the 300,000 g supernates and light membranes and were eluted in the same peak fractions from a Sephadex G-200 column. This dually labelled peak dissociated in the presence of digitonin, suggesting close association between the mAChR and G protein. ABT-affinity chromatography yielded dually labelled mAChR-G protein fractions which eluted as a single radioactive peak on a second ABT column. The partially purified G proteins from these fractions were photoaffinity labelled with 8-azidoguanosine-5'-triphosphate, [gamma-32P]. SDS-PAGE autoradiography revealed the presence of Go alpha and Gi alpha which may be released simultaneously with the mAChRs from the plasma membrane. In addition, 110,000 molecular weight polypeptide was dually labelled by [3H]-PrBCM and [gamma-32P]-8-azido-GTP suggesting the presence of a "mAChR-G protein complex." These findings provide direct evidence for the release of mAChRs and G proteins and a mAChR-G protein complex by agonist occupation of the mAChRs.

Mass screening for rectal neoplasm in Jiashan County, China.

Jiashan county is a rural area in China with very high incidence and mortality rates of colorectal cancer. From 1980 to 1984, we conducted a mass screening for rectal neoplasm in the 11 people's communes in this county. Of the 72,879 individuals who were eligible for screening, 60,496 participated, representing an overall participation rate of 83.0%. Both the fecal occult blood (OB) test and rectoscopy were performed on 47,560 of the participants, and rectoscopy only was performed on the remaining 12,936 individuals. From the mass screening, 15 rectal cancers, 3 carcinoids, 899 polyps, 98 ulcers, and 7 inflammatory tumors were detected, a total of 1022 cases. Eight of the 15 detected cases of rectal cancer were in Dukes' stage A. We did not find any evidence for an association between schistosomiasis and colorectal cancer. Results from the OB test were found to have a negative correlation with results from rectoscopy (odds ratio = 0.8, 95% CI = 0.6, 1.1). The OB test had a high false positive rate of 32.7%, and a poor positive predictive value of 3.5%. Both its positive and negative predictive powers were below 1.0, in other words, its positive likelihood ratio was below 1.0 and negative likelihood ratio was above 1.0, indicating that the OB test is not informative and has a poor predictive accuracy for rectal neoplasm. In addition, there were a number of practical problems concerning the use of the OB test for mass screening in the rural community.(ABSTRACT TRUNCATED AT 250 WORDS)

Phosphorylation-dephosphorylation of muscarinic acetylcholine receptors: evidence for the in vivo and in vitro release of receptors from rat brain plasma membrane.

The effects of phosphorylation on muscarinic acetylcholine receptors (mAChRs) were studied in vitro and in vivo using rat brain plasma membrane and receptors partially purified at least 2500-fold. Purified mAChRs were phosphorylated in vitro by cAMP-dependent protein kinase and dephosphorylated by calcineurin. Phosphorylation of purified mAChRs was enhanced by carbachol and blocked by atropine. The filtrate which passed through glass fiber filters and high speed supernates were assayed for mAChRs by an ammonium sulfate precipitation method. Following incubation of the plasma membrane under phosphorylating conditions and ultracentrifugation at 300,000 g, the mAChRs appeared in the high speed supernate. This release was stimulated by adding carbachol to the incubation medium. In rats treated with carbachol, brain mAChRs redistributed from the heavy into the light membrane fractions. Ultrastructural examination of the light membrane fractions and the 300,000 g supernatant fractions after in vivo and in vitro carbachol treatment calcineurin increased the reincorporation of added partially purified receptors into the plasma membrane. The release and reincorporation of mAChRs strongly imply that there is a translocation and recycling of mAChRs between plasma membrane and cytosol in vivo. The significance and the function of the translocation of mAChRs remain to be investigated.