Predicting the impact of biochar on the saturated hydraulic conductivity of natural and engineered media.

If biochar is applied to soil or stormwater treatment media, the saturated hydraulic conductivity (K) may be altered, which is a critical property affecting media performance. While a significant number of studies document biochar's effect on a porous medium's K, predictive models are lacking. Herein models are advanced for predicting K for repacked natural soil and engineered media when amended with biochar of various particle sizes and application rates. Experiments were conducted using three repacked natural soils, two uniform sands, and a bioretention medium amended with a wood biochar sieved to seven different biochar particle size distributions and applied at three rates. Experimental measurements showed a strong positive correlation between the interporosity of each medium and K. Across all media, the classic Kozeny-Carman (K-C) model predicted K and the relative change in K because of biochar amendment for each medium best. For soils alone, a recently developed model based on existing pedotransfer functions was optimal. The K-C model error was improved if the particle specific surface area was increased for large biochar particles, which indicates the importance of biochar particle shape on pore structure and K. X-ray Computed Tomography was coupled with pore network modeling to explain the unexpected decrease in K for sands amended with medium and large biochar. While biochar increased interporosity, mean pore radii decreased by ~25% which reduced K. The X-ray measurements and pore network modeling help to explain anomalous results reported for biochar-amended sands in other studies.

[Effect of intra- and out-anorectal drainage in the prevention of anastomotic leakage after low anterior resection].

OBJECTIVE: To investigate the effect of intra- and out-anorectal drainage in the prevention of anastomotic leakage after low anterior resection (LAR). METHODS: Two hundred and thirty-five patients undergone LAR were divided into two groups according to two periods, the former group from Mar. 2003 to Aug. 2004 and the later group from Sep. 2004 to Nov. 2007. Technique advances were adopted in the later group, especially the routine intra- and out-anorectal drainage. Incidence of anastomotic leakage and clinicopathological data of two groups were compared. RESULTS: Anastomotic leakage occurred in 4 patients of the former group (4/89) and 1 of the later group (1/146). Logistic analysis found that intra- and out-anorectal drainage was the main issue which prevented anastomotic leakage. CONCLUSION: Intra- and out-anorectal drainage is useful for the prevention of anastomotic leakage after low anterior resection.

Genetic detection of Chinese hereditary nonpolyposis colorectal cancer.

AIM: To explore the germline mutations of the two main DNA mismatch repair genes (hMSH2 and hMLH1) between patients with hereditary non-polyposis colorectal cancer (HNPCC) and suspected (atypical) HNPCC. METHODS: Genomic DNA was extracted from the peripheral blood of the index patient of each family, and germline mutations of hMSH2 and hMLH1 genes were detected by PCR-single strand conformation polymorphism (PCR-SSCP) and DNA sequencing techniques. RESULTS: For PCR-SSCP analysis, 67% (4/6) abnormal exons mobility in typical group and 33% (2/6) abnormal exons mobility in atypical group were recognized. In direct DNA sequencing, 50% (3/6) mutation of MMR genes in typical group and 33% (2/6) mutation of MMR genes in atypical group were found, and 4/6 (66.67%) and 1/6 (16.67%) mutations of hMSH2 and hMLH1 were identified in typical HNPCC and atypical HNPCC, respectively. CONCLUSION: Mutation detection of the patients is of benefit to the analysis of HNPCC and, PCR-SSCP is an effective strategy to detect the mutations of HNPCC equivalent to direct DNA sequence. It seems that there exist more complicated genetic alterations in Chinese HNPCC patients than in Western countries.

[Clinicopathological features of typical and non-typical hereditary non-polyposis colorectal cancer and their germline mutation of hMLH1 and hMSH2].

OBJECTIVE: To study the clinicopathological features of the Chinese hereditary non-polyposis colorectal cancer and its germline mutation of hMLH(1) and hMSH(2). METHODS: Thirteen typical Chinese hereditary non-polyposis colorectal carcinoma (HNPC)C kindreds and 19 non-typical HNPCC families were registered and followed up. The germline mutation of the hMLH(1) and hMSH(2) of 12 index cases of 6 typical and 6 non-typical HNPCC were screened by PCR-SSCP. Samples with abnormal mobility were sequenced directly. RESULTS: The average age of typical HNPCC was 47, no difference existed between sexes. Location of the tumors of typical HNPCC represented 44.7% on the right half colon and non-typical HNPCC 65.8% on the rectum. The rate of the metachronos cancer was 11.5%. The 3-, 5-and 10-year survival rate was 64.0%, 45.3% and 31.2% respectively. Among 12 cases, 8 showed abnormal mobility. Except for an intron polymorphism, six exons abnormalities were found in 5 of 12 proband. Sequencing showed 4 missense, 7 insertion and a nonsense mutations. CONCLUSIONS: Chinese HNPCC is early onset, more common on proximal colon and better prognosis. Mutation of hMSH(2) is dominant in the Chinese typical HNPCC, but mutation of hMLH(1) is more common in the non-typical group.

[The role of the immunohistochemistry for hMLH1 and hMSH2 with detection of microsatellite instability to identify the kindreds with hereditary nonpolyposis colorectal cancer].

OBJECTIVE: To investigate the specificity and sensitivity of the immunohistochemistry for hMLH1 and hMSH2 with detection of microsatellite instability (MSI) to identify the kindreds with hereditary nonpolyposis colorectal cancer and to analyse its value in clinical practice. METHOD: Specimens of 16 cases with HNPCC and 16 cases with sporadic colorectal cancer were detected by immunostaining with hMLH1 and hMSH2 and MSI was also detected. RESULTS: The specificity and sensitivity of the immunohistochemistry for hMLH1 and hMSH2 were 91.7% and 87.5% respectively. The specificity and sensitivity of MSI were 100% and 75.0%. By combining two methods, the specificity and sensitivity were 91.7% and 93.8% respectively. CONCLUSIONS: By combination of the immunohistochemistry for hMLH1 and hMSH2 and detection of MSI to identify the kindreds with HNPCC, the specificity and sensitivity are improved which is better than to use either of them alone. And it is very easy and cheap that it can be used in clinics.