[The exposure of antibiotics on the eradication of bismuth quadruple therapy in H.pylori infection]

Objective: To analyze the impact of previous exposure to macrolide, quinolones and nitroimidazole antibiotics on eradication rate of bismuth quadruple therapy (BQT) in newly diagnosed patients with Helicobacter pylori(H. pylori). Methods: A total of 469 patients with H. pylori initially treated at the Third Hospital of Peking University from September 2017 to August 2020 were retrospectively recruited. The therapeutic regimens were BQT containing clarithromycin/levofloxacin/metronidazole recommended by Chinese guidelines. Clinical data were collected, including general demographic data, exposure history of antibiotics, CYP2C16 metabolic pattern, endoscopic diagnosis, bacterial density, H.pylori resistance, eradication results, etc. Univariate analysis, Chi-square test, Fisher exact probability test, Kruskal-Wallis H test and Logistic regression model were used as statistical methods. Results: Among different eradication therapies, univariate and multivariate analyses suggested that previous exposure to macrolides (OR=3.37,95%CI 1.04-10.98, P<0.05) was relevant to the decreased eradication rate of BQT containing clarithromycin. This may be due to increased resistance to clarithromycin (OR=6.12,95%CI 3.99-9.40, P<0.01).The previous exposure to quinolones (OR=3.65, 95%CI 1.27-10.49, P<0.05) was relevant to the decreased eradication rate of BQT containing levofloxacin, which was probably explained by the increased resistance to levofloxacin (OR=2.50, 95%CI 1.69-3.71, P<0.01). But the previous history of nitroimidazole did not impact the efficacy of BQT containing metronidazole. Conclusions: In patients newly diagnosed with H.pylori infection, the previous exposure to macrolide or quinolones antibiotics is related to lower eradiation rates of H. pylori. Although the exposure to nitroimidazole also indicates drug resistance to metronidazole, the clinical efficacy of BQT with metronidazole 400 mg four times a day is not affected.

[Preoperative dynamic contrast-enhanced MRI can reduce the rate of tumor-positive resection margins after breast conserving surgery in patients with early non-mass breast carcinoma]

Objective: To investigate the value of preoperative dynamic contrast-enhanced MRI in reducing the rate of tumor-positive resection margins after breast conserving surgery in patients with early non-mass breast carcinoma. Methods: Seventy-two patients with early non-mass breast carcinoma received ultrasonographic and mammographic examination and subsequently underwent dynamic contrast-enhanced MRI examination before breast conserving surgery. The control group consisted of 74 patients who had early non-mass breast carcinoma. They only received ultrasonographic and mammographic examination and didn't undergo contrast-enhanced MRI examination. The comparison of the rate of tumor-positive resection margins between two groups was performed. The MRI findings that had the significant influence on the rate of tumor-positive resection margins were analyzed using Logistic regression model. Results: In 28 patients (28/72, 38.9%), dynamic contrast-enhanced MRI could correct or supplement the ultrasonographic and mammographic findings and resulted in the reasonable change of surgical program. The preoperative MRI examination group (n=30) had lower rate of tumor-positive resection margins than control group for invasive ductal carcinoma (23.3% vs 40.0%, P=0.02), but there was no significant difference (21.4% vs 26.9%, P=0.10) between two groups for ductal carcinoma in situ (n=28). The preoperative MRI examination group (n=14) had lower rate of tumor-positive resection margins than control group for the other pathologic types of breast carcinoma (14.3% vs 38.9%, P=0.02). The statistical analysis on the basis of Logistic regression model showed that some main MRI findings, including change surrounding the tumor, distance between tumor and nipple and tumor size, had the significant influence on the rate of tumor-positive resection margins. Conclusion: Preoperative dynamic contrast-enhanced MRI significantly increased the accuracy of resection margins evaluation, and greatly reduced the rate of tumor-positive resection margins after breast conserving surgery in patients with early non-mass breast carcinoma.

[The application of conscious sedation with a small dose of dexmedetomidine and sufentanil in elderly patients undergoing multiple intestinal polyps resection]

Objective: To explore the effectiveness and feasibility of conscious sedation with a low dose of dexmedetomidine and sufentanil during multiple intestinal polyps resection in elderly patients. Methods: Sixty elderly patients who underwent multiple intestinal polyps resection in Peking University Third Hospital from Janurary to May 2016 were randomly divided into dexmedetomidine group (D group, n=30) and propofol group (P group, n=30). There were 28 males and 32 females with a mean age of (70.4±4.5) years old (range: 65-80 years old). The patients in the dexmedetomidine group received a loading dose of 0.3 μg/kg followed by a continuous infusion of 0.2-0.4 μg·kg^-1·min^-1 of dexmedetomidine and sufentanil (0.1 μg/kg) respectively.The patients in the propofol group received sufentanil 0.1 μg/kg and propofol 1.5 mg/kg and followed by a continuous infusion of 3-6 mg·kg^-1·h^-1 of propofol.Blood pressure, heart rate, pulse oxygen saturation (SpO₂), respiratory rate and bispectral index (BIS) were recorded at the basic status and at the beginning of operation, 10 min, 20 min, 30 min after operation, the end of operation and departure.The observer's assessment of alertness/sedation (OAA/S) scores and the clinical responses were also recorded.A statistical analysis was performed. Results: All patients in the two groups were sedated compared with baseline.The BIS values of patients in group D at beginning of the operation, 10 min, 20 min, 30 min after operation and the end of operation were 89.6(87.8-91.0), 79.4(78.0-80.0), 76.9(75.0-80.0), 76.0(73.0-79.0) and 75.6(70.0-79.0) respectively, and those values were all significantly lower than baseline value[96.4(95.0-98.0)], (Z=-4.645, -4.788, -4.787, -4.789, -4.789, P<0.05). The OAA/S score at beginning of the operation, 10 min, 20 min, 30 min after operation and the end of operation were 4.5(4.0-5.0), 3.4(3.0-4.0), 3.0(3.0-3.0), 3.5(3.0-4.0) and 3.3(3.0-4.0) respectively, and were significantly lower than baseline score [4.8(5.0-5.0)] (Z=-2.828, -4.862, -5.031, -4.420, -4.710, P<0.05). The BIS value of patients in group P at beginning of the operation, 10 min, 20 min, 30 min after operation and the end of operation were 54.7(50.0-59.3), 54.8(50.0-59.3), 50.7(47.8-56.8), 54.4(51.5-58.0) and 53.7(50.0-57.3) respectively, and were significantly lower than baseline value[95.8(95.0-96.3)] (Z=-4.786, -4.787, -4.788, -4.786, -4.786, P<0.05). The OAA/S score at beginning of the operation , 10 min, 20 min, 30 min after operation and the end of operation were 0.4(0.0-1.0), 0.4(0.0-1.0), 0.4(0.0-1.0), 0.4(0.0-1.0) and 0.4(0.0-1.0) respectively, and were significantly lower than baseline score[4.9(5.0-5.0)] (Z=-4.927, -4.901, -4.912, -4.912, -4.901, P<0.05). The sedation state of group D were lighter than group P. The BIS value and OAA/S score at beginning of the operation, 10 min, 20 min, 30 min after operation and the end of operation in group D were higher than group P (P<0.05). The breath and circulation were more stable in group D. The mean arterial pressure, breath rate and SpO₂ at beginning of the operation, 10 min, 20 min, 30 min after operation and the end of operation in group D were higher than group P (P<0.05). There was no oxygen desaturation , hypotension and drowsiness in group D and the incidence in group P were 30.0%, 33.3% and 13.3% respectively.The emergency time and duration of stay in the PACU (post anesthesia care unit) were (2.0±1.2) and (22.0±7.4) min in group D, and they were (4.9±2.4) and (35.8±11.6) min in group P (t=-5.839, t=-5.472, P<0.05). There was no difference in surgery time, patient satisfaction and acceptance rate of reexamination (t=-3.031, t=-7.322, t=2.069, P>0.05). Conclusion: Conscious sedation with dexmedetomidine and sufentanil is effective and feasible in elderly patients undergoing multiple intestinal polyps resection.

Right arm injection of contrast medium reduces venous artifacts in head and neck multislice spiral computed tomography angiography

OBJECTIVE

We tested whether injection of contrast medium via right or left arm would affect venous artifacts on head and neck multislice spiral computed tomography (CT) angiography.

PATIENTS AND METHODS

326 patients were enrolled. Each patient was injected with 10 ml of contrast medium at 5 ml/sec. Time of peak contrast value plus an additional 1 sec was defined as delay time. Another 40 ml of contrast medium were injected with the same injection speed. The scanning area ranged from the aortic arch to the top of the head. Left and right forearms were used for intravenous injections of contrast medium in, respectively, 151 and 175 patients. Comparative analyses of image quality included determining contrast medium residues remaining in the superior vena cava, brachiocephalic vein, or subclavian vein, and comparisons of quality of three-dimensional CT angiography.

RESULTS

In 75% of head and neck angiographies, the delay time of the common carotid artery ranged from 16 to 22 sec. In 60% of the images, the quality was graded as excellent, with the left arm injection resulting in delay time of > 23 sec and the right arm delay time of > 18 sec. The CT imaging quality after contrast injections via left or right arms was statistically significant (p < 0.05). The image quality after right arm injection was better than after left arm injection.

CONCLUSIONS

Intravenous injection of contrast medium via right arm reduces artifacts from contrast medium residues and improves the image quality of head and neck CT angiography.

Temporal coherence and spectral linewidth of an injection-seeded transient collisional soft x-ray laser

The temporal coherence of an injection-seeded transient 18.9 nm molybdenum soft x-ray laser was measured using a wavefront division interferometer and compared to model simulations. The seeded laser is found to have a coherence time similar to that of the unseeded amplifier, ~1 ps, but a significantly larger degree of temporal coherence. The measured coherence time for the unseeded amplifier is only a small fraction of the pulsewidth, while in the case of the seeded laser it approaches full temporal coherence. The measurements confirm that the bandwidth of the solid target amplifiers is significantly wider than that of soft x-ray lasers that use gaseous targets, an advantage for the development of sub-picosecond soft x-ray lasers.

[Efficacy of Phyllanthus spp. in treating patients with chronic hepatitis B]

The efficacy of Phyllanthus amarus produced in india, P. niruri gathered from hainan province and P. urinaria from henan province was assessed in a total of 88 cases of chronic hepatitis B with 11.42 and 35 each. It was shown that P. urinaria had the effect of seroconversion on HBeAg from positive to negative as well as on HBeAb from negative to positive, while the other two herbs had not. In addition none of these three herbs had similar effect on HBsAg.

Identification of hypoxanthine and guanine as the co-repressors for the purine regulon genes of Escherichia coli

Addition of purine compounds to the growth medium of Escherichia coli and Salmonella typhimurium causes repressed synthesis of the purine biosynthetic enzymes. The repression is mediated through a regulatory protein, PurR. To identify the co-repressor(s) of PurR, two approaches were used: (i) mutations were introduced into purine salvage genes and the effects of different purines on pur gene expression were determined; (ii) purine compounds which dictate the binding of the PurR protein to its operator DNA were resolved by gel retardation. Both the in vivo and the in vitro data indicated that guanine and hypoxanthine are co-repressors. The toxic purine analogues 6-mercaptopurine and 6-thioguanine also activated the binding of PurR to its operator DNA.

Autoregulation of PurR repressor synthesis and involvement of purR in the regulation of purB, purC, purL, purMN and guaBA expression in Escherichia coli

The purR gene encodes a repressor (PurR) controlling the synthesis of the enzymes of purine biosynthesis. The subunit of PurR was identified as a 38-kDa polypeptide by SDS/polyacrylamide gel electrophoresis. Analysis of a purR-lacZ transcriptional fusion indicated that purR expression is autoregulated. This was confirmed by gel retardation and DNaseI footprinting experiments, where two PurR-binding sites were identified in the transcribed part of purR. Introduction of a purR mutation in wild-type and pur-lac fusion strains was found to abolish purine repression of all genes of the purine biosynthetic pathway except for purA.

Genetic evidence for a repressor of synthesis of cytosine deaminase and purine biosynthesis enzymes in Escherichia coli

Addition of purines to the growth medium of Escherichia coli represses synthesis of cytosine deaminase (codA) and enzymes of purine de novo synthesis. After Tn10 mutagenesis, mutants displaying derepressed levels of cytosine deaminase in the presence of hypoxanthine were isolated. One of these had simultaneously acquired resistance to the hypoxanthine analog 6-mercaptopurine. The mutation purR6::Tn10 was shown to affect de novo synthesis of the purine enzymes glutamine phosphoribosylpyrophosphate amidotransferase (purF) and phosphoribosyl glycinamide synthetase (purD). The mutation was mapped by P1 transduction at 36 min on the E. coli linkage map. A plasmid containing the purR region was obtained by complementation of the purR6::Tn10 mutation. By comparing the restriction maps of the cloned fragment and the E. coli chromosome, the purR gene was found to be located very close to the lpp gene (36.3 min).