Application of metagenomics in the human gut microbiome

There are more than 1000 microbial species living in the complex human intestine.The gut microbial community plays an important role in protecting the host against pathogenic microbes,modulating immunity,regulating metabolic processes,and is even regarded as an endocrine organ.However,traditional culture methods are very limited for identifying microbes.With the application of molecular biologic technology in the field of the intestinal microbiome,especially metagenomic sequencing of the next-generation sequencing technology,progress has been made in the study of the human intestinal microbiome.Metagenomics can be used to study intestinal microbiome diversity and dysbiosis,as well as its relationship to health and disease.Moreover,functional metagenomics can identify novel functional genes,microbial pathways,antibiotic resistance genes,functional dysbiosis of the intestinal microbiome,and determine interactions and co-evolution between microbiota and host,though there are still some limitations.Metatranscriptomics,metaproteomics and metabolomics represent enormous complements to the understanding of the human gut microbiome.This review aims to demonstrate that metagenomics can be a powerful tool in studying the human gut microbiome with encouraging prospects.The limitations of metagenomics to be overcome are also discussed.Metatranscriptomics,metaproteomics and metabolomics in relation to the study of the human gut microbiome are also briefly discussed.

Central pancreatectomy for pancreatic schwannoma: A case report and literature review

Schwannomas are mesenchymal tumors originating from Schwann cells in peripheral nerve sheaths. Although the tumor can be located in any part of the human body, the most common locations are the head, neck, trunk and extremities. Pancreaticschwannomas are rare. To our knowledge, only 64 cases of pancreatic schwannoma have been reported in the English literature over the past 40 years. In this paper, we present a pancreatic schwannoma in a 59-year-old female. Ultrasound, computed tomography and magnetic resonance imaging revealed the tumor located in the pancreatic body; however, accurate diagnosis was hard to obtain preoperatively and a pancreatic cystadenoma was preliminarily considered. During laparotomy, the mass was found in the body of the pancreas. An enlarged gallbladder with multiple stones was also observed. We performed central pancreatectomy, end-to-side pancreaticojejunostomy and cholecystectomy. Notably, central pancreatectomy has been reported in only one case prior to this report. The gross specimen showed a mass with a thin capsule, 1.6 cm × 1.1 cm × 1.1 cm in size. Microscopic examination showed that the tumor was mainly composed of spindle-shaped cells with palisading arrangement and no atypia, which is consistent with a benign tumor. Both hypercellular and hypocellular areas were visible. Immunohistochemical staining revealed strongly positive results for protein S-100. Finally, the tumor was diagnosed as a schwannoma of the pancreatic body. Postoperatively, the patient recovered well and left the hospital 6 d later. During the 53-mo follow-up period, the patient remained well and free of complications.

Successful treatment of a pancreatic schwannoma by spleen-preserving distal pancreatectomy

Schwannomas are neurogenic tumors that arise from the neural sheaths of peripheral nerves.These tumors can be located in any area of the human body;the most common locations are the head,neck,trunk and extremities.Pancreatic schwannomas are very rare.Over the past 40 years,only 67 cases of pancreatic schwannomas have been reported in the English literature.Here we present a case of pancreatic schwannoma in a 62-year-old male.The tumor was revealed by ultrasound and computed tomography in the neck and body of the pancreas.An accurate diagnosis was difficult to obtain preoperatively.The patient consented to the performance of a laparotomy,and the mass was found in the neck and body of the pancreas and successfully treated using a spleenpreserving distal pancreatectomy with splenic artery and vein preservation.The procedure has only been reported in one other case of pancreatic schwannoma;here we present the second reported case.Macroscopically,the tumor was well circumscribed,gray-white in color and3.3 cm×2.8 cm in size.Microscopically,the tumor cells were spindle-shaped and had a palisading arrangement with no atypia,which are results compatible with a benign tumor.Both hypercellular and hypocellular areas were visible.Immunohistochemically,the tumor cells were strongly positive for S-100 protein.The tumor was definitively diagnosed as a schwannoma of the pancreatic neck and body.The patient was followed for 72 mo and has been doing well without any complications.

Schwannoma in the hepatoduodenal ligament: A case report and literature review

Schwannomas are mesenchymal neoplasms with low malignant potential that arise from Schwann cells. They can occur almost anywhere, although the most common locations are the head, neck and extremities. Primary benign schwannoma of the hepatoduodenal ligament is rare. To date, only three cases have been reported in the English literature. In the present study, we report a case of hepatoduodenal ligament schwannoma in a 43-year-old male, who was admitted to our hospital because of a abdominal mass found by physical examination. It was hard to determine the definitive location and diagnosis of the mass using ultrasound, computed tomography and magnetic resonance cholangiopancreatography. During laparotomy, the mass was found in the hepatoduodenal ligament and close to the cholecystic duct, so we resected the gallbladder and cholecystic duct along with the mass. The gross specimen revealed an 8.5 cm × 5.5 cm × 3.0 cm localized tumor. Microscopic examination showed that the tumor was mainly composed of spindle-shaped cells. Immunohistochemical staining showed a strong positive S-100 protein reaction. Finally, the lesion was diagnosed as a benign schwannoma in the hepatoduodenal ligament. However, one month later, the patient was readmitted to our hospital because of skin and sclera jaundice caused by common bile duct stenosis without common bile duct stone or tumor. The patient recovered well after implantation of a common bile duct stent under endoscopic retrograde cholangiopancreatography. He was followed up for a period of 17 mo, during which he was well with no complications.

Successful treatment of a giant ossified benign mesenteric schwannoma

Primary benign schwannoma of the mesentery is extremely rare. To date, only 9 cases have been reported in the English literature, while mesenteric schwannoma with ossified degeneration has not been reported thus far. In the present study, we present the first giant ossified benign mesenteric schwannoma in a 58-year-old female. Ultrasound, computed tomography and magnetic resonance imaging were used, but it was still difficult to determine the definitive location and diagnose the mass. By laparotomy, a 10.0 cm × 9.0 cm × 9.0 cm giant mass was found in the mesentery and was then completely resected. Microscopically, the tumour located in the mesentery mainly consisted of spindleshaped cells with a palisading arrangement. Some areas of the tumour were ossified, and a true metaplastic bone formation was observed, with the presence of bone lamellae and osteoblasts. Immunohistochemical investigation of the tumour located in the mesentery showed that the staining for the S-100 protein was strongly positive, while the stainings of SMA, CD34, CD117 and DOG-1 were negative. The cell proliferation index, measured with Ki67 staining, was less than 3%. Finally, a giant ossified benign mesenteric schwannoma was diagnosed. After surgery, the patient was followed up for a period of 43 mo, during which she remained well, with no evidence of tumour recurrence.

Synchronous occurrence of a hepatic myelolipoma and two hepatocellular carcinomas

Myelolipoma is a rare tumor composed of fat and bone marrow components, most of which are located in the adrenal gland. Myelolipoma in the liver is extremely rare. To date, only 10 cases have been reported in the English-language medical literature. In one of these cases, the hepatic myelolipoma was found within a hepatocellular carcinoma(HCC). In the present study, we report the first case of the synchronous occurrence of hepatic myelolipoma and HCCs in different liver sections of one patient, a 26-year-old female who was admitted to our hospital because of a 4-d history of upper abdominal pain. The unenhanced computed tomography(CT) images showed a well-defined lowdensity mass with adipose components in the right liver lobe, 4.2 cm × 4.1 cm in size. Two inhomogeneous low-density masses were found in the left liver lobe, 8.6 cm × 7.7 cm and 2.6 cm × 2.6 cm in size. The masses in both the right and left liver lobes were heterogeneously enhanced in the contrast-enhanced CT images. Based on the results of the imaging examination, the mass in the right liver lobe was preliminarily considered to be a hamartoma, and the two masses in the left liver were preliminarily considered to be HCCs. We performed a right hepatectomy, a left hepatic lobectomy, and a cholecystectomy. Microscopic and immunohistochemical results revealed that the tumor in the right liver lobe was a hepatic myelolipoma, and that the two tumors in the left liver lobe were HCCs.

Successful treatment of pancreatic accessory splenic hamartoma by laparoscopic spleen-preserving distal pancreatectomy:A case report

BACKGROUND Pancreatic accessory spleen(PAS)is an uncommon congenital abnormality of the spleen.Spleen hamartoma(SH)is also rare.Moreover,hamartoma in the PAS has not been reported thus far.We report the first case here.CASE SUMMARY A 26-year-old male presented with a one-month history of left upper quadrant abdominal pain,and computerized tomography(CT)examination suggested a mass in the pancreas tail.The patient then attended our hospital for diagnosis and treatment.Ultrasonography,CT,and magnetic resonance imaging revealed a solid mass with cystic degeneration growing from the tail of the pancreas.The tumor marker carbohydrate antigen 19-9(CA19-9)increased to 96.7 U/mL(normal range 0-37 U/mL).An epidermoid cyst in a PAS was considered preoperatively.However,a malignant tumor cannot be ruled out.We performed laparoscopic surgery,and two pancreatic masses were found growing from the pancreatic tail.The two masses were so closely connected that preoperative imaging examinations suggested only one mass.We carefully isolated the masses from the splenic artery and vein.A laparoscopic spleen-preserving distal pancreatectomy was successfully performed.On pathological examination,the masses were well-defined,homogeneous red-tan,4×3,and 4.5×1.5 in size,respectively.One of them was cystically degenerated.On microscopical examination,the mass contained unorganized small slit-like vascular channels enclosing red blood cells and lined with plump endothelial cells.No area of cytologic atypia was identified.Focal lymphoid aggregates were found in the intravascular areas.White pulp or fibrosis was not observed.The final diagnosis was pancreatic accessory SH with cystic degeneration.After the operation,CA19-9 was reduced to normal.The patient recovered well,and the 34-mo follow-up period was uneventful.CONCLUSION Here,we report the first case of pancreatic accessory SH.A laparoscopic spleen-preserving distal pancreatectomy was successfully performed.The patient recovered well and had a good prognosis.