Exploration capacity versus specific enzymatic activity of ectomycorrhizas in response to primary productivity and soil phosphorus availability in Bornean tropical rainforests.

Ectomycorrhizal (ECM) fungi are functionally important in biogeochemical cycles in tropical ecosystems. Extracellular enzymatic activity of ECM on a ground-area basis is the product of two attributes; exploration capacity (ECM surface-area) and specific enzymatic activity. Here, we elucidated which attribute better explained the ECM enzymatic activity in response to different levels of soil phosphorus (P) and Nitrogen (N) availability in five Bornean tropical rainforests. We determined the surface area of ECM root tips as well as the enzymatic activities per ECM surface area for carbon (C), N and P degrading enzymes in each site. We evaluated the relationship of ECM enzyme activities with the resource availabilities of C (Above-ground net primary production; ANPP), N, and P of ECM by a generalized linear mixed model. The ECM enzymatic activities on a ground-area basis were more significantly determined by specific enzymatic activity than by the exploration capacity. Specific enzymatic activities were generally negatively affected by C (ANPP) and soil P availability. ECM fungi enhance the specific enzyme activity rather than the exploration capacity to maintain the capacity of nutrient acquisition. The less dependence of ECM fungi on the exploration capacity in these forests may be related to the limitation of C supply from host trees. We highlighted the adaptive mechanisms of ECM fungi on nutrient acquisition in tropical ecosystems through the response of enzymatic activity to nutrient availability across the elements.

Conversion surgery by hand-assisted laparoscopic surgery following chemotherapy for rectal cancer with H3 liver metastases: a case report.

Background: Recent advancements in molecularly targeted chemotherapy for stage IV colorectal cancer have enabled the possibility of complete resection in primary colorectal cancer, which often involves distant liver or lung metastases, by aggressive surgical resection followed by multi-combination chemotherapy. Case description: A 73-year-old man treated previously for hyperuricemia, hypertension, and a dissecting abdominal aortic aneurysm was referred to us after an incidental finding of multiple liver masses on abdominal ultrasound during follow-up for the aneurysm. A detailed examination by contrast-enhanced computed tomography revealed a ring-enhancing mass larger than 5 cm in diameter in segment 3 of the liver and more than 6 low-density areas with total diameter of 1 to 2 cm in both lobes. A barium enema examination revealed a Borrmann type 2 lesion covering two-thirds of the circumference of the colon, with a 5-cm major axis in the rectosigmoid colon. Biopsy revealed a well-differentiated adenocarcinoma. The patient was diagnosed with stage IV rectal cancer. Because there was no intestinal obstruction, we administered 9 cycles of bevacizumab with capecitabine and oxaliplatin as chemotherapy. Subsequent diagnostic imaging revealed the metastatic lesions in liver segment 3 had reduced to 2 low-density areas with a diameter of 8 mm, and the other hepatic metastases had disappeared; the main tumor had flattened and shrunk. Therefore, we used hand-assisted laparoscopic surgery (HALS) to perform anterior resection of the rectosigmoid colon and partial resection of liver segment 3 as conversion therapy. The patient was discharged 10 days after surgery. The rectal lesion was a well-differentiated adenocarcinoma with a depth of invasion of p-MP and a spread of L0, V0, and pN0. The partial hepatectomy did not indicate viable cancer cells; only necrotic, lysed tissue was observed. Postoperative chemotherapy involved 4 cycles of bevacizumab with capecitabine and oxaliplatin. At more than 42 months postoperatively, no metastasis or recurrence has been observed. Conclusions: This rare case demonstrates that conversion surgery can be a viable option following systemic chemotherapy in patients with advanced colon cancer and H3 liver metastases.