How to treat gastrinomas in patients with multiple endocrine neoplasia type1: surgery or long-term proton pump inhibitors?

In patients with multiple endocrine neoplasia type 1 syndrome (MEN 1) and Zollinger-Ellison syndrome (ZES), gastrinomas arise from the duodenum, about 60% are multiple, and about 15% of patients have coexisting pancreatic gastrinomas, which can be localized by the selective arterial secretagogue injection test (SASI test). The guidelines (GLs) by the Japanese Neuroendocrine Tumor Society (JNETS) recommend surgical resection for functioning duodenopancreatic neuroendocrine tumors (NETs), including gastrinomas, in patients with MEN1 (Grade A, 100% agreement among members). Conversely, the GLs of the National Comprehensive Cancer Network (NCCN) in the USA recommend observation and treatment with proton pump inhibitors (PPIs) or exploratory surgery for occult gastrinomas. An international Consensus Statement (ICS) from the European Union (EU) also does not recommend resection of gastrinomas in patients with MEN1, despite some surgeons having reported surgery being curative for gastrinomas in MEN1 patients. In this review, we discuss the serious side effects and tumorigenic effects of the prolonged use of PPIs and the safety and curability of surgery, supported by our results of curative surgery for gastrinomas in 20 patients with MEN1 over 30 years. We conclude that surgery should be the first-line treatment for gastrinomas in MEN1 patients.

Primary pancreatic glomus tumor invading into the superior mesenteric vein: a case report.

BACKGROUND: Glomus tumors are subcutaneous tumors arising from glomus bodies, thermoregulatory components of the skin. These tumors could occur in visceral organs where glomus bodies are not normally present. Herein, we report a case of primary pancreatic glomus tumor with aggressive direct invasion into the superior mesenteric vein (SMV). To the best of our knowledge, this is the second case report of a glomus tumor arising in the pancreas. CASE PRESENTATION: A 46-year-old woman was referred to our hospital due to vomiting with epigastric and back pain. Dynamic-CT revealed a well-circumscribed hypervascular mass, measuring 37 mm in its maximal diameter involving the pancreatic head. Both CT and endoscopic ultrasonography (EUS) revealed direct invasion into the SMV and radiologically suspected tumor thrombus. Biopsy sample obtained by EUS-guided fine needle aspiration revealed proliferation of small cells, round-to-oval tumor cells with round nuclei and scant cytoplasm. A histological diagnosis of pancreatic neuroendocrine tumor, G1 was initially considered. Therefore, subtotal stomach-preserving pancreatoduodenectomy using Child-II reconstruction was subsequently performed. Her SMV was resected and reconstructed due to extensive tumor involvement. Subsequent histopathological analysis revealed solid tumor cells proliferation that comprised oval-shaped nuclei and scant cytoplasm around disorganized or slit-shaped vessels in hematoxylin-eosin-stained slides. Immunohistochemical analysis then demonstrated positive immunoreactivity for smooth muscle actin, vimentin, and CD34, but negative for chromogranin A, synaptophysin, CD56, and signal transducer and activator of transcription 6. Based on these histological findings of resected specimens, the lesion was subsequently diagnosed as a primary pancreatic glomus tumor harboring direct invasion into the SMV. Her postoperative course was uneventful and annual surveys for the following 4 years post-op detected no clinical signs of recurrence. CONCLUSIONS: We report a very rare case of glomus tumor of the pancreas accompanied by venous invasion. Curative surgical resection is the best treatment option for pancreatic glomus tumors. Although pancreatic glomus tumor is rare, it should be taken into consideration in the differential diagnosis of a pancreatic solid tumor with hypervascularity.

[A Case of Thymic Carcinoma of Postoperative Liver and Mediastinal Lymph Node Metastases Where Long-Term Survival Was Achieved through Multidisciplinary Treatment].

The patient was a 67-year-old man. At the age of 60, he underwent resection of thymic carcinoma with partial resection of the right upper lobe of the lung because of invasive thymic carcinoma. The pathological diagnosis was Masaoka stage Ⅲ squamous cell carcinoma. Follow-up examination 2 years after surgery showed metastases to the mediastinall ymph node and liver. After undergoing radiotherapy of 50 Gy to the mediastinal lymph node metastasis, partial hepatectomy was performed for metastatic liver cancer. Post-operation, he received 4 courses of combination therapy of carboplatin and paclitaxel. Five years post-hepatectomy, the patient developed liver metastasis again and underwent hepatectomy for local control. Postoperative recurrent cases of thymic carcinoma generally have poor prognosis. We describe a patient with thymic carcinoma of postoperative liver and mediastinal lymph node metastases who achieved long-term survival through multidisciplinary treatment.

[A Case Report of a Difficult to Diagnose, Extremely Well-Differentiated Stomach Adenocarcinoma Diagnosed by Biopsy].

A Japanese man in his 60s presented with complaints of epigastric pain and weight loss. A gastrointestinal endoscopy revealed multiple gastric ulcers and an irregular mound located on the wall of the lower gastric body along the greater curvature, which was suspected to be cancerous. A biopsy revealed that it was a Group 2 tumor even though the biopsy was repeated 4 times. He was referred to our hospital and 3 biopsies were performed. The final result classified the tumor as Group 4. The patient underwent surgery and the pathological examination revealed an extremely well-differentiated adenocarcinoma( EWDA). An EWDA is characterized by a well-formed mucinous gland with little or no nuclear atypia, which makes preoperative biopsy diagnosis difficult.

[Two-Stage Radical Resection of a Case of Colon Cancer with Abdominal Wall Invasion and Cholangiocarcinoma].

A woman in her 50s was admitted to our hospital with fever and lower abdominal swelling. Abdominal CT/MRI examinations revealed irregular thickening of the transverse colon wall, which was attached to a subcutaneous abscess. An abdominal wall mass, a patent urachus, and a tumor in the 5th segment of the liver were also noted. Colonoscopy revealed type 2 advanced transverse colon cancer. The solitary, sessile tumor was observed at the apex of the bladder under cystoscopy, suggesting the formation of the urachal carcinoma. Transcutaneous liver biopsy obtained from the liver tumor indicated adenocarcinoma, which was morphologically different from the existing transverse colon cancer. Right hemicolectomy with resection of the umbilicus, abdominal wall, urachus, and part of the bladder wall was performed. Diagnosis of the transverse colon cancer invading the abdominal wall and bladder was confirmed by histopathological examination. Hepatectomy was performed in the next surgery, and the tumor was histopathologically diagnosed as an intrahepatic cholangiocarcinoma. Both the transverse colon cancer and the intrahepatic cholangiocarcinoma were radically resected. Radical surgical diagnostic resection may be valuable in cases of multicentric cancers of unknown primary origin, if radical resection of each individual tumor is required.

[A Case of Esophageal Carcinoma with Large Intramural Metastasis to the Stomach].

We report a rare case of esophageal carcinoma with gastric wall metastasis. A 73-year-old man with dysphagia underwent endoscopy and upper GI series and chest-abdominal computed tomography, revealing esophageal carcinoma and gastric cancer, which was diagnosed as squamous cell carcinoma by biopsy. The esophageal carcinoma was located in the lower thoracic esophagus(Lt). Total gastrectomy was performed. The resected specimen showed a type 3 tumor measuring 7×7 cm in the anterior wall of the stomach. Pathologically, the depth of invasion of the stomach was SE. He died 3 months after the operation. Esophageal carcinoma with gastric intramural metastasis is very rare and has a dismal prognosis. We report a rare case of esophageal carcinoma with large intramural metastasis to the stomach.

A primary hepatic gastrinoma accompanied by hyperplasia of multi-nodular Brunner's glands.

BACKGROUND: Primary hepatic gastrinoma causing severe ulcerogenic syndrome is extremely rare. Herein, we report a case of primary hepatic gastrinoma accompanied by hyperplasia of multi-nodular Brunner's glands in a patient who instead, preoperatively, was suspected of having multiple duodenal gastrinomas and hepatic metastasis. CASE PRESENTATION: A 57-year-old woman consulted a clinic complaining of melena, intermittent abdominal pain, diarrhea, and vomiting which had persisted for about 3 years. Six months before her presentation, she underwent segmental resection of the jejunum for acute peritonitis due to the spontaneous jejunal perforation. A blood test revealed that her serum immunoreactive gastrin (IRG) level was 12,037 pg/mL. Subsequently, she was transferred to our hospital. On computed tomography (CT), a hypervascular tumor of 23 mm in the segment 5 (S5) region of the liver was visualized. A selective arterial secretagogue injection test (SASI test) was performed twice. The first SASI test revealed that the hepatic tumor was a gastrinoma, and there was no gastrinoma in the duodeno-pancreatic region. Additionally, somatostatin receptor scintigraphy only visualized the tumor in the liver. However, the second SASI test, which was performed during the administration of a proton pump inhibitor and a somatostatin analog (octreotide acetate), revealed that there may have been gastrinomas existing not only in the liver but also in the upper part of the duodenum or the head of the pancreas. Duodenal endoscopy revealed multiple submucosal tumors in the first and the second portion of the duodenum, although a pathological examination of biopsied specimens obtained from the duodenal lesions was negative for malignant cells. Multiple endocrine neoplasia type 1 (MEN1) was excluded from her family history, and serum levels of both intact parathyroid hormone (iPTH) and calcium were within normal ranges. An anterior segmentectomy of the liver and pancreas-preserving total duodenectomy were performed on September 9, 2013. Postoperatively, her serum immunoreactive gastrin level decreased to less than 50 pg/mL. Pathological study of the resected specimens revealed a gastrinoma in the liver, but no gastrinoma in the duodenum. Interestingly, the duodenal submucosal tumor-like lesions were hyperplastic Brunner's glands. Postoperatively, she has been well without recurrence of hypergastrinemia for 4 years. CONCLUSION: We report a case of primary hepatic gastrinoma in a patient who has been cured for 4 years postoperatively. The diagnosis was somewhat difficult due to the coexisting, multiple hyperplastic Brunner's glands of the duodenum mimicking the submucosal neuroendocrine tumors, which might have developed due to long-term hypergastrinemia.

[A Case of Triple Negative Spindle Cell Carcinoma of the Breast and Improved Quality of Life Following Irinotecan Chemotherapy].

We report a case of triple negative spindle cell carcinoma of the breast, responsive to irinotecan chemotherapy. A 49-year old woman who had a tumor in the chest wall with a skin ulcer visited our hospital. After being diagnosed with triple negative spindle cell carcinoma of the breast, she underwent surgery, adjuvant chemotherapy, and radiation at the other hospital. Fourteen months after the surgery, she developed an ipsilateral breast tumor as a result of local recurrence. Since eribulin and paclitaxel plus bevacizumab chemotherapies were not effective, she was transferred to our hospital, and we administered irinotecan as third-line chemotherapy. Skin lesions and effusion were reduced and her quality of life improved for 4 months.

[A Case of Unresectable Locally Advanced Pancreatic Cancer Resulted in R0 Surgery after Chemotherapy].

A 67-year-old man visited our hospital for jaundice. Abdominal dynamic CT showed the hypovascular tumor at the head of the pancreas that surrounded superior mesenteric artery(SMA)at an angle of 220 degree. No metastasis in lymph nodes and other organs was observed. We diagnosed the tumor unresectable locally advanced(UR-LA)pancreatic cancer. Chemotherapy was administered with gemcitabine and nab-paclitaxel(GEM+nab-PTX)and achieved partial response. Regression in size and in range around SMA to an angle of 150 was observed. We assessed it possible to resect the tumor curatively, and performed subtotal stomach preserving pancreaticoduodenectomy and dissection of the plexus around the SMA, resulted in R0 surgery. Adjuvant chemotherapy was administered, and no recurrence was observed up to present, more than a year. It is suggested that GEM+nab-PTX can be effective as the primary therapy against UR-LA pancreatic cancer.

[Recurrent Gastric Carcinoma(Endocrine Cell Type)Successfully Treated with Multidisciplinary Therapy - A Case Report].

A 62-year-old woman was diagnosed with carcinoma of the stomach at another hospital. Distal gastrectomy with D2 dissection was performed and she was referred to our hospital. Histopathological and immunopathological examinations showed the tumor to be composed of adenocarcinoma and neuroendocrine carcinoma. The patient was followed until 4 months after the operation when an abdominal computed tomographic(CT)scan showed a metastatic tumor at S2 and S5/6 of the liver. No other organ metastases were found, and a hepatectomy was performed. The primary tumor of the stomach consisted of adenocarcinoma and neuroendocrine carcinoma; however, the resected metastatic liver tumor consisted of only neuroendocrine carcinoma. Liver and lung metastases appeared 2 months after the operation, and we started chemotherapy with VP-16 and cisplatin. After 8 courses of treatment, the lung metastases showed a CR, and the liver metastasis was SD. She is alive without lung metastases 9 months after the hepatectomy.

[A Case of Rectal Cancer Successfully Treated with Surgery and Stereotactic Radiotherapy for Metachronous Lung Metastases].

A 64-year-old woman underwent polypectomy for a rectal polyp(Isp). Pathological findings were invasion of the submucosa( 3,500 mm diameter), and she underwent anterior resection for rectal cancer(RS, pT1b, pN0, cM0, Stage I )without adjuvant chemotherapy. Lung masses were found in her right(8mm)and left lung(7mm). The tumors enlarged during the 4 month follow-up period. We decided to perform left partial pneumonectomy. The tumor was diagnosed as a lung metastasis from colon cancer by pathology. Because the right tumor was located towards the center, performing right pneumonectomy would have been quite invasive and we feared occult metastases. We decided to apply SRT(50 Gy)to the right tumor. The tumor shrunk and became a scar after treatment. There were no complications such as radiation pneumonitis. The patient was in good health without any recurrence for 12 months after SRT. Surgical resection is an optimal method to control lung metastasis from colon cancer if the lesion is operable. However, in the case of a tumor centrally located, surgical resection may cause deterioration of lung function. There are also cases with contraindications for surgery due to co-morbidities. In addition, there is no consensus on observation periods to exclude occult metastases. SRT can be an effective treatment for lung metastases from colon cancer when there are bilateral lung metastases and no metastases outside the lungs.

Diagnosis of functioning pancreaticoduodenal neuroendocrine tumors.

Functioning pancreaticoduodenal neuroendocrine tumors (PD-NETs) are popular in a textbook, but they are still unfamiliar to a general clinician, and delay of diagnosis or misdiagnosis has been reported even today. It is a consensus that sporadic functioning PD-NET is cured only by surgical resection. So, early detection and early resection is the gold standard for the treatment of functioning PD-NET. Functioning PD-NETs in patients with multiple endocrine neoplasia type 1 (MEN 1) are often multiple. You should check about MEN 1 whenever you encountered multiple PD-NET. They are diagnosed in younger age than sporadic cases. In most cases they are accompanied with numerous microscopic or macroscopic nonfunctioning P-NETs, which are potentially metastatic and the most common cause of death in MEN 1 patients.

[Adult Case of Invagination Due to Small Intestinal Metastases of Malignant Melanoma].

An 84-year-old woman was diagnosed with malignant melanoma after resection of a nasal cavity tumor in February 2008. In April 2010, she underwent small bowel resection because of ileus due to small intestinal metastases. She was diagnosed with ileus again in October 2010. Computed tomography (CT) and 18F-fluorodeoxyglucose-positron emission tomography (FDG-PET) revealed invagination of the small intestine and small intestinal metastases. We performed a palliative small bowel resection. She had a good postoperative course and was discharged 2 weeks after surgery. Oral intake was possible for 6 months until her death.

Soluble tumor necrosis factor receptor 2 is independently associated with pulse wave velocity in nonobese Japanese patients with type 2 diabetes mellitus.

The aim of the present study was to investigate the factors contributing to pulse wave velocity (PWV) in patients with type 2 diabetes mellitus. We focused on tumor necrosis factor (TNF) including soluble TNF receptors (sTNF-R1, sTNF-R2) in this study because TNF seems to be associated with the progression of atherosclerosis and because the relationships between PWV and TNF were not yet examined in type 2 diabetic patients. Univariate regression analyses showed that PWV was positively correlated with age (r=0.492, P<.001), diabetes duration (r=0.251, P=.021), systolic (r=.595, P<.001) and diastolic (r=0.248, P=.022) blood pressure, antihypertensive medication (r=0.268, P=.013), and the concentrations of sTNF-R1 (r=0.354, P=.001) and sTNF-R2 (r=0.415, P<.001). Although there was a positive correlation between TNF-alpha and sTNF-R1 (r=0.382, P<.001) or sTNF-R2 (r=0.394, P<.001), TNF-alpha was not associated with PWV. Other variables including gender were not associated with PWV. Multiple regression analyses showed that PWV was independently predicted by the level of age (F=15.1), systolic blood pressure (F=31.6), and sTNF-R2 (F=5.2), which explained 49.2% of the variability of PWV. From these results, it can be concluded that serum soluble TNF receptor is an important independent factor associated with aortic PWV in type 2 diabetic patients.

Interleukin 6, adiponectin, leptin, and insulin resistance in nonobese Japanese type 2 diabetic patients.

The aim of the present study was to investigate the relationships between interleukin 6 (IL-6) and insulin resistance, serum leptin, serum adiponectin, or serum lipids including triglycerides in 98 nonobese Japanese type 2 diabetic patients. Insulin resistance was estimated by the insulin resistance index of homeostasis model assessment (HOMA-IR). Serum IL-6 concentration was negatively correlated to high-density lipoprotein cholesterol (r = -0.295, P = .004), but was not associated with HOMA-IR (r = 0.016, P = .871), body mass index (BMI) (r = 0.090, P = .375), systolic (r = 0.169, P = .116) and diastolic (r = -0.061, P = .570) blood pressures, leptin (r = 0.062, P = .544), and adiponectin (r = -0.020, P = .841) in these patients. In contrast, serum leptin level was positively correlated to HOMA-IR (r = 0.291, P = .004), BMI (r = 0.338, P < .001), and systolic blood pressure (r = 0.241, P = .025). Serum adiponectin level was negatively correlated to HOMA-IR (r = -0.288, P = .005), BMI (r = -0.308, P = .002), diastolic blood pressure (r = -0.269, P = .012), and triglycerides (r = -0.338, P < .001), and positively correlated to high-density lipoprotein cholesterol (r = 0.300, P = .003) in our patients. From these results, it can be suggested that fasting serum IL-6 is not a major factor responsible for the evolution of insulin resistance in nonobese Japanese type 2 diabetic patients.

[A phase I study of intraperitoneal plus intravenous paclitaxel against gastric cancer with peritoneal dissemination (HGCG 0301)].

The safety of the intraperitoneal (ip) plus intravenous (iv) paclitaxel against gastric cancer with peritoneal dissemination was evaluated on a phase I dose escalation trial. Patients were treated with ip paclitaxel administered in 500 ml of normal saline before closing the abdomen, using the following dose levels: level 1, 50 mg/m(2); level 2, 60 mg/m(2); level 3, 70 mg/m(2); and level 4, 80 mg/m(2), followed by iv infusion of the same doses of paclitaxel on days 14 and 21. Twelve patients were enrolled in this study: 7 underwent reduction surgery,while 5 had only a laparotomy. ip therapy was well tolerated, and did not bring about any postoperative complications even in patients who underwent gastrectomy. Although multiple NCI/CTC grade 1 toxicities and grade 2 anemia (4 of six patients at dose levels 2 and 3) were observed, there was no dose-limiting toxicity. The overall median survival time was 316 days, and that for patients who underwent gastrectomy was 413 days. Paclitaxel at a dose of 80 mg/m(2) can be delivered by the operative ip route with acceptable toxicity profile.

Three measures of tumor necrosis factor alpha activity and insulin resistance in nonobese Japanese type 2 diabetic patients.

The aim of the present study was to investigate the relationship between insulin resistance and tumor necrosis factor alpha (TNF-alpha) as well as soluble TNF receptors (sTNF-R), body mass index (BMI), leptin, adiponectin, and serum lipid profile including triglycerides in nonobese Japanese patients with type 2 diabetes. A total of 88 nonobese Japanese type 2 diabetic patients were studied. The duration of diabetes was 11.0 +/- 0.8 years. In conjunction with BMI, glycosylated hemoglobin (HbA1c), fasting concentrations of plasma glucose, serum lipids (triglycerides, high-density lipoprotein cholesterol, and total cholesterol), serum leptin, serum adiponectin, serum TNF-alpha, and soluble TNF receptors (sTNF-R1 and sTNF-R2) were also measured. Insulin resistance was estimated by the insulin resistance index of homeostasis model assessment. Insulin resistance was positively correlated with BMI, triglycerides, leptin, and total cholesterol and negatively correlated with adiponectin and high-density lipoprotein cholesterol. In contrast, insulin resistance was not associated with TNF-alpha, nor sTNF-R (sTNF-R1 and sTNF-R2) in our diabetic patients. There was no significant relationship between the 3 measures of TNF-alpha system (TNF-alpha, sTNF-R1, and sTNF-R2) and BMI, serum triglycerides, leptin, or adiponectin in these patients. From these results, it can be concluded that peripheral levels of TNF-alpha system activity are not a major factor responsible for insulin resistance in nonobese Japanese type 2 diabetic patients.

Soluble E-selectin, leptin, triglycerides, and insulin resistance in nonobese Japanese type 2 diabetic patients.

The aim of the present study was to investigate the relationships between insulin resistance and soluble E-selectin, body mass index (BMI), leptin, and serum lipid profile including triglycerides in nonobese Japanese type 2 diabetic patients. A total of 97 nonobese Japanese type 2 diabetic patients aged 43 to 84 years were examined. The duration of diabetes was 11.2 +/- 0.8 years. In conjunction with BMI and fasting concentrations of plasma glucose, serum lipids (triglycerides, total cholesterol, and high-density lipoprotein cholesterol) and serum insulin, soluble E-selectin, and leptin were also measured. The low-density lipoprotein (LDL) cholesterol level was calculated using the Friedewald formula. Insulin resistance was estimated by the homeostasis model assessment. The subjects were divided into 2 groups according to the value of insulin resistance estimated by the homeostasis model assessment. Values greater than 2.5 were indicative of the insulin-resistant state, and values less than 2.5 were indicative of the insulin-sensitive state. The insulin-resistant group had significantly higher levels of E-selectin, leptin, triglycerides, total and LDL cholesterol, and diastolic blood pressure as compared with the insulin-sensitive group. There was, however, no significant difference in age, sex, diabetes duration, BMI, systolic blood pressure, HbA1c, and high-density lipoprotein cholesterol between the 2 groups. Univariate regression analysis showed that insulin resistance was positively correlated to E-selectin (r = 0.305, P = .003), BMI (r = 0.283, P = .006), leptin (r = 0.296, P = .004), HbA1c (r = 0.241, P = .018), serum triglycerides (r = 0.385, P < .001), serum total (r = 0.240, P = .019) and LDL cholesterol (r = 0.254, P = .013) levels, and systolic (r = 0.247, P = .024) and diastolic (r = 0.305, P = .006) blood pressure. Multiple regression analyses showed that insulin resistance was independently predicted by serum E-selectin (F = 18.4), serum leptin (F = 14.0) and serum triglycerides (F = 20.0) levels, which explained 45.0% of the variability of insulin resistance. From these results, it can be concluded that in conjunction with serum triglycerides and serum leptin, serum E-selectin is another important independent factor associated with insulin resistance in nonobese Japanese type 2 diabetic patients.

Restoration of function after spinal cord transection using a collagen bridge.

The restoration of function of transected adult mammalian spinal cord without living tissue has not been reported previously. We report the first success of functional restoration of transected spinal cord without living tissue. We grafted collagen filaments parallel or transverse to the axis of the spinal cord to bridge 5-mm defects of 47 adult rat spinal cords. Twenty-five rats were used as a control. Of the 72 rats, 42 rats survived the experimental period. At 4 weeks postoperatively, regenerated axons crossed the proximal and distal spinal cord-implant interfaces in all 5 rats of the parallel-grafted group. At 12 weeks postoperatively, the rats in the parallel-grafted group (8 rats) could walk, run, and climb with hind-forelimb coordination. The somatosensory-evoked potentials were seen. Results suggest that the collagen filaments support the axonal regeneration of the transected spinal cord and the restoration of function when grafted parallel to the axis of the spinal cord. The functional restoration appeared to be permanent, raising the possibility of therapeutic application in humans.

Nerve regeneration along collagen filament and the presence of distal nerve stump.

This article describes the regeneration of severed peripheral nerve axons along collagen filaments in the absence of the distal nerve stump. 22-mm long nerve guides made of collagen filaments were sutured to the proximal ends of severed rat sciatic nerves. The distal ends of the guides were sutured to the distal stumps of the nerves in a group and not sutured in the other. Nerve autografts and collagen tubes were used as controls. At 8 weeks postoperatively, the mean number and the mean diameter of myelinated axons were 5491 +/- 617 (mean +/- SD) and 2.3 +/- 1.3 microns at the distal ends of the collagen filaments nerve guides those the distal ends were sutured to the distal stumps of the nerves, while in the nerve autografts these were 4837 +/- 604 and 3.3 +/- 1.4 microns. These were 1992 +/- 770 and 2.7 +/- 1.2 microns at the distal ends of the collagen-filaments guides those the distal ends were not sutured to the distal stumps of the nerves, while in the nerve autografts these were 3041 +/- 847 and 2.3 +/- 1.1 microns. No axon was found at the distal ends of the collagen tubes. The results suggested that the contact guidance and the chemotaxis guided regenerating axons along the collagen filaments.