[Effects of Farming Practices on Soil Nitrogen and Phosphorus Concentrations and Its Loss in the Drawdown Area of the Tributary Embayment of the Three Gorges Reservoir]

As the Three Gorges Reservoir (TGR) periodically operates at low water levels, its drawdown area has been utilized for cultivation by local farmers due to the overlap of the non-inundated period and the crop-growth period. However, traditional agricultural planting may affect the aquatic environment of the TGR area. To explain the effects of agricultural farming and abandoned farming on the water environment, a study was conducted in the drawdown area in an embayment of the Pengxi River (a tributary of the TGR). Corn, potato, and peanut fields were investigated for nitrogen and phosphorus content in surface soil, during the farming period (March to September 2018) and the conversion period (March to September 2019). Nitrogen and phosphorus balance models were constructed for farmland and abandoned farmland, to compare and analyze the budgets and loss risk of nitrogen and phosphorus from soil in the drawdown area. The results showed that the ammonia nitrogen (NH₄⁺-N), total phosphorus (TP), and inorganic phosphorus (IP) content of soil in the corn field varied significantly across different planting periods. The concentrations of ammonium nitrogen and nitrate nitrogen (NO₃^--N) were significantly higher in farmland soil than in abandoned farmland soil, and the concentrations of total phosphorus (TP), inorganic phosphorus (IP), and calcium-bound phosphorus (Ca-P) were significantly lower in farmland soil than in abandoned farmland soil. The different soils were ranked according to the intensity of nitrogen and phosphorus surplus as follows:corn field>potato field>peanut field. The apparent surplus values in the different farmland soils were 76.89 kg ·hm^-2(corn field), 51.92 kg ·hm^-2(potato field), and 43.74 kg ·hm^-2(peanut field) for nitrogen, and 79.69 kg ·hm^-2(corn field), 75.76 kg ·hm^-2(potato field), and 17.78 kg ·hm^-2(peanut field) for phosphorous. Overall, the surplus intensities of nitrogen and phosphorus in all three croplands were higher than the respective risk thresholds, indicating potential nitrogen and phosphorus pollution in the three farmland types. Agricultural farming in the drawdown area may therefore increase the risk of nitrogen and phosphorus loss and is not conducive to the protection of the aquatic environment.

Intraindividual Variation and Personal Specificity of Salivary Microbiota

Salivary microbiota is a typical habitat of the human microbiome. This study intended to use salivary microbiota as a model aiming to systematically address the influence of collection methods and temporal dynamics on the human microbiota compared to personal specificity. We carried out a supervised short-term longitudinal study to evaluate the influence of the change of collection methods and sampling time point on salivary microbiota in 10 systemically and orally healthy individuals with certain confounding factors (sex, oral and general health state, medication history, physical exercise, diet, and oral hygiene behavior) controlled before and during the sampling period. The microbial profiles were analyzed by 16S rDNA V3 to V4 hypervariable region amplicon sequencing. The taxonomic structure represented by the dominant species and the weighted UniFrac distance algorithm were used to demonstrate the individual specificity and the intraindividual variation introduced by the change of collection method and sampling time point. The findings suggested individual specificity existed in salivary microbiota from individuals with similar oral and general health status. The intraindividual variation brought by the change of collection method or sampling time point might introduce remarkable perturbation with the personal specificity. Insights into the intraindividual variation and personal specificity of salivary microbiota will enhance our understanding in salivary microbiota-related research. We recommend keeping collection conditions consistent within a study to avoid interference brought by the sampling. The strategy of repeated sampling at multiple time points as representative samples, as well as thorough interpretation of the complex relationships and causality between microbiome composition and disease without the interference of temporal dynamics, is optimal for research exploring the relationship between the salivary microbiome and disease.

Cystic duct cancer: Should it be deemed as a type of gallbladder cancer?

BACKGROUND

According to the latest American Joint Committee on Cancer and Union for International Cancer Control manuals, cystic duct cancer (CC) is categorized as a type of gallbladder cancer (GC), which has the worst prognosis among all types of biliary cancers. We hypothesized that this categorization could be verified by using taxonomic methods.

AIM

To investigate the categorization of CC based on population-level data.

METHODS

Cases of biliary cancers were identified from the Surveillance, Epidemiology, and End Results 18 registries database. Together with routinely used statistical methods, three taxonomic methods, including Fisher’s discriminant, binary logistics and artificial neuron network (ANN) models, were used to clarify the categorizing problem of CC.

RESULTS

The T staging system of perihilar cholangiocarcinoma [a type of extrahepatic cholangiocarcinoma (EC)] better discriminated CC prognosis than that of GC. After adjusting other covariates, the hazard ratio of CC tended to be closer to that of EC, although not reaching statistical significance. To differentiate EC from GC, three taxonomic models were built and all showed good accuracies. The ANN model had an area under the receiver operating characteristic curve of 0.902. Using the three models, the majority (75.0%-77.8%) of CC cases were categorized as EC.

CONCLUSION

Our study suggested that CC should be categorized as a type of EC, not GC. Aggressive surgical attitude might be considered in CC cases, to see whether long-term prognosis could be immensely improved like the situation in EC.

[Application of laparoscopic transection of median hepatic fissure in difficult laparoscopic liver resections]

Objective: The aim was to explore the strategy and clinical value of laparoscopic transection of median hepatic fissure (MHF) in difficult laparoscopic liver resections. Methods: First the MHF was located and marked, then the transection plane of the MHF was set. Next, the laparoscopic Multifuctional Operative Dissector (LPMOD) and the technique of curettage and aspiration were utilized to transect the liver beginning from the middle portion of the gallbladder fossa, in a caudal-to-cranial and anterior-to-posterior direction, until the clear exposure of the anterior surface of the intrahepatic inferior vena cava. Transection of the MHF was accurately achieved. Finally, dissection of the second and third porta hepatis were carefully performed and mobilization of the transected liver was achieved. This technique of laparoscopic transection of MHF was successfully performed in 13 patients in difficult laparoscopic liver resections. Results: Between April 2014 and August 2015, 13 patients received the technique of laparoscopic transection of MHF in difficult laparoscopic liver resections, including 10 cases of laparoscopic right hepatectomy, two cases of laparoscopic left hepatectomy and one case of associating liver partition and portal vein ligation for staged hepatectomy (ALPPS). The maximum size of the transected tumor was 15 centimeter. Duration of surgery was 240-430 min[Mean, 324.4±50.0]; the time for transection of the MHF was 40-118 min[mean, 66.4±22.7]. Blood loss was 200-2 000 ml[583.3±452.9]. The length of postoperative hospital stay was 6-25 days[mean, 13.2±5.2]. Seven patients received intraoperative transfusions. No postoperative intraabdominal bleeding, liver failure or other severe postoperative complications occurred. No perioperative death occurred. Conclusions: Application of laparoscopic transection of the MHF in difficult laparoscopic liver resections can help to clearly expose the second and third porta hepatis, especially in patients who have huge tumors and poor exposure for hepatic dissection. Moreover, precise location and transection of the MHF remains very important strategies of applying this technique.

Can retrohepatic tunnel be quickly and easily established for laparoscopic liver hanging maneuver by Goldfinger dissector in laparoscopic right hepatectomy?

OBJECTIVE

The liver hanging maneuver (LHM) is rarely applied in laparoscopic right hepatectomy (LRH) because of the difficulty encountered in retrohepatic tunnel (RT) dissection and tape positioning. Thus far no report has detailed how to quickly and easily establish RT for laparoscopic LHM in LRH, nor has employment of the Goldfinger dissector to create a total RT been reported. This study's aim was to evaluate the safety and feasibility of establishing RT for laparoscopic LHM using the Goldfinger dissector in LRH.

METHODS

Between March 2015 and July 2015, five consecutive patients underwent LRH via the caudal approach with laparoscopic LHM. A five-step strategy using the Goldfinger dissector to establish RT for laparoscopic LHM was adopted. Perioperative data were analyzed.

RESULTS

The median age of patients was 58 (range, 51-65) years. Surgery was performed for one intrahepatic lithiasis and four hepatocellular carcinomas with a median size of 90 (40-150) mm. The median operative time was 320 (282-358) min with a median blood loss of 200 (200-600) ml. Laparoscopic LHM was achieved in a median of 31 (21-62) min, and the median postoperative hospital stay was 14 (9-16) d. No transfusion or conversion was required, and no severe liver-related morbidity or death was observed.

CONCLUSIONS

The Goldfinger dissector is a useful instrument for the establishment of RT. A five-step strategy using the Goldfinger dissector can quickly and easily facilitate an RT for a laparoscopic LHM in LRH.

Age estimation using a modified HPLC determination of ratio of aspartic acid in dentin

Diastereomeric dipeptides were derived from the amino acid enantiomers in dentin by O-phthalaldehyde-N-acetyl-L-cysteine. The products were separated using high performance liquid chromatography (HPLC) and detected by fluorescence detector. A short analysis time (total analysis time was 15 min, including retention time, sample derivatization time and column regeneration time) was used. The sensitivity of detection was 1 pmol and high resolution (Rs = 1.5) was reached. We determined the D/L ratio of aspartic acid in dentin of 28 first premolars. The correlation value between the D/L ratio of aspartic acid and actual age was 0.9887; errors of +/- 1 year accounted for 46.4%, and no error exceeded 5 years.