Systemic inflammation score as a predictor of death within one year after esophagectomy.

BACKGROUND: After radical resection for esophageal cancer, death within 1 year of surgery can occur due both to recurrence and to other diseases, even after postoperative complications have been overcome. This study identified risk factors for early death within 1 year of esophagectomy for reasons other than death in hospital in patients undergoing esophagectomy for esophageal cancer or esophagogastric junction cancer. METHODS: We reviewed 366 patients who underwent esophagectomy without adjuvant treatment between January 2009 and July 2022 for thoracic esophageal cancer or esophagogastric junction cancer. Patients who died within 1 year excluding in-hospital death were compared with those who did not. Multivariable logistic regression analysis was used to identify predictors of death within 1 year after surgery. RESULTS: Death within 1 year occurred in 32 of 366 patients, 24 from primary disease and 8 from other diseases. Deaths within 1 year were significantly older than the other cases, had significantly lower % vital capacity (%VC), and occurred significantly more often in cases in advanced stages of disease. In a multivariable analysis, a systemic inflammation score (SIS) based on serum albumin level and lymphocyte-to-monocyte ratio was identified as an independent predictor of death within 1 year. As SIS increased, %VC decreased significantly, and CRP level and neutrophil-lymphocyte ratio increased significantly. There was no relationship between SIS and pN. Death within 1 year increased as SIS increased (p = 0.001 for trend). CONCLUSION: SIS assessment undertaken before beginning esophageal cancer treatment is a useful predictor of death within 1 year of surgery.

Esophageal ulcer related to zinc deficiency following a total gastrectomy.

A 76-y-old Japanese man who had undergone gastrectomy 4.5 y earlier experienced 2 wk of sore throat, heartburn, and difficulty swallowing. Endoscopy showed deep, craterlike, longitudinal ulcers in the lower and middle esophagus. Immunohistochemistry and blood tests were negative for herpes simplex virus and cytomegalovirus infections. The patient reported no other symptoms affecting the gastrointestinal tract. Although his symptoms ameliorated after initial hospitalization and treatment, they re-emerged a few days after being discharged. Fifty-one days after being first admitted, he complained of glossalgia. The serum zinc level was found to be 38 µg/dL, which was below the reference range; the patient was diagnosed with zinc deficiency. After oral zinc administration, the patient was relieved of the symptoms, and his pain was alleviated. Upper gastrointestinal endoscopy after symptom relief showed improvement in the esophageal ulcers. He has continued taking zinc supplementations, and has not developed similar symptoms in the 5 y since being treated. To the best of our knowledge, this is the first case report of esophageal ulcers related to zinc deficiency.

Skeletal Muscle Loss During Neoadjuvant Chemotherapy Predicts the Incidence of Postoperative Infectious Complications in Esophageal Cancer Patients Undergoing Esophagectomy.

BACKGROUND/AIM: Malnutrition, immune deficiency, and skeletal muscle loss are associated with a risk of postoperative complications in patients with various types of cancer. This study evaluated whether malnutrition, immunological deficiencies, and skeletal muscle loss during neoadjuvant chemotherapy (NAC) predict postoperative complications in patients with esophageal cancer. PATIENTS AND METHODS: We retrospectively reviewed 123 patients with esophageal squamous cell carcinoma treated with NAC and esophagectomy at our hospital between 2014 and 2019. Patients were divided into two groups based on the presence or absence of postoperative infectious complications, such as pneumonia, anastomotic leakage, surgical site infections, pyothorax, acalculous cholecystitis, and peripheral phlebitis. Neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, and Onodera prognostic nutritional index were used as indicators of systemic inflammation and nutritional status. Skeletal muscle mass was evaluated using the skeletal muscle index (SMI), calculated by evaluating the total cross-sectional area of muscle tissue at the third lumbar level in computed tomography imaging. Univariable and multivariable logistic regression analyses were used to identify predictors of postoperative infectious complications. RESULTS: Postoperative infectious complications occurred in 41 patients (33.3%). A reduction in SMI was observed in 105 patients (87.8%) during NAC. Univariable and multivariable analyses indicated that the reduction in SMI during NAC was an independent predictor of postoperative complications (odds ratio=0.89; 95% confidence interval=0.79-0.99; p=0.048). CONCLUSION: Skeletal muscle loss during NAC is a useful predictor of postoperative complications in patients with esophageal cancer undergoing esophagectomy.

Esophageal cancer presenting with brain abscess.

A 76-year-old man experienced fatigue and progressive dysphagia. He underwent endoscopy at another hospital and was diagnosed with thoracic esophageal cancer. Three days after the endoscopy, the patient was rushed to our hospital with sudden seizures of the right upper and lower extremities. Contrast-enhanced computed tomography scan revealed a ring-shaped contrast-enhanced mass formation in the left parietal lobe with edema in the surrounding brain parenchyma. Contrast-enhanced magnetic resonance imaging showed a ring-shaped lesion with a high intensity on diffusion-weighted images. He was diagnosed with a brain abscess in the left parietal lobe. For abscess drainage, a quasi-emergent small craniotomy was performed. Culture of the drainage fluid revealed Streptococcus species and Haemophilus parainfluenzae. After 6 weeks of antibiotic therapy, the patient underwent a thoracoscopic esophagectomy. After the esophagectomy, there was no recurrence of the brain abscess for more than 2 years and only symptomatic epilepsy remained. Conclusively, although brain abscesses caused by esophageal cancer are rare, the possibility of brain abscess and metastasis should be considered when patients present with convulsions or higher brain disorders.

The impact of the American Society of Anesthesiology-Physical Status classification system on the treatment and prognosis of patients with esophageal cancer undergoing esophagectomy.

BACKGROUND: The American Society of Anesthesiologists-Physical Status (ASA-PS) classification system has been shown to predict morbidity and mortality after surgery. However, the impact of the ASA-PS on esophageal cancer treatment remains unclear. This study examined both the impact of the ASA-PS on treatment, including surgery and perioperative chemotherapy, and the prognostic effects of ASA-PS class in patients who had undergone esophagectomy for thoracic esophageal cancer or esophagogastric junction cancer. METHODS: ASA-PS status was collected for 301 patients who had undergone esophagectomy between January 2007 and June 2016 for thoracic esophageal cancer or esophagogastric junction cancer at a single institution. As the ASA-PS was updated in 2014, the previous classifications of all patients were reevaluated using the updated standard by a surgeon with the previous classifications masked. The dose intensity of preoperative chemotherapy was also compared across classes. Multivariate Cox regression analysis was used to analyze the association between ASA-PS class and overall survival. RESULTS: Patients whose reevaluations had placed them in a more severe ASA-PS class showed significantly poorer overall and cancer-specific survival rates. The dose intensities of cisplatin and 5-fluorouracil for preoperative chemotherapy were significantly lower in patients in the more severe ASA-PS classes. Multivariate analysis showed that ASA-PS class was an independent prognostic factor for overall survival. CONCLUSION: Preoperative ASA-PS classification may influence the intensity of perioperative treatment and may be a valuable long-term prognostic factor for patients with esophageal cancer undergoing esophagectomy.

Risk Factors for Candidiasis as an Intra-Abdominal Infection after Gastrectomy in Patients with Gastric Cancer.

Intra-abdominal infections (IAIs) develop in 2.4%-26.6% of patients who underwent gastrectomy for gastric cancer and are occasionally serious. However, there are few reports on the causative organisms of IAI following upper gastrointestinal tract surgery and subsequent risk factors for Candida infections. This study aimed to identify the microorganisms that cause IAIs after gastrectomy and risk factors for Candida-related IAI. The records of patients who underwent gastrectomy for gastric cancer between January 2009 and December 2019 at Shizuoka General Hospital were retrospectively collected. Patients with IAIs of grade II or higher, as measured by the Clavien-Dindo classification, were included in the analysis. The selected patients were divided into the Candida and non-Candida groups according to the presence or absence of Candida as the causative organism. Of 1,379 patients, 56 (4.1%) were diagnosed with IAIs after gastrectomy. Fifty-two patients were included in the study based on culture analyses. A total of 111 strains and 28 bacterial species were isolated during the initial culture test. Candida constituted 7.2% of all identified pathogens. Regarding the risk factors for Candida-related IAI, a history of antimicrobial use and ≥ 4 postoperative days of IAI development were independent risk factors for Candida-related IAI.

Serum carnitine as a biomarker of sarcopenia and nutritional status in preoperative gastrointestinal cancer patients.

BACKGROUND: Sarcopenia is an important factor in the postoperative outcome of gastrointestinal cancer patients. However, little research has been carried out on potential biomarkers of sarcopenia. Carnitine is an amino acid derivative that is stored in skeletal muscle and is essential for muscle energy metabolism. The primary purpose of this study was to investigate whether serum carnitine level is a biomarker of sarcopenia in preoperative patients with gastrointestinal cancer. The secondary purposes were (i) to examine the associations between carnitine, nutritional status, and albumin level, and (ii) to determine whether carnitine is a prognostic factor for postoperative complications. METHODS: One hundred fourteen patients scheduled to undergo gastroenterological surgery between August 2016 and January 2017 were enrolled. Their mean age was 68.4 ± 10.5, and 64.9% were male. Serum carnitine fractions [total carnitine (TC), free l-carnitine (FC), and acylcarnitine (AC)] were measured prior to surgery. The correlation between carnitine level and a variety of clinical features was analysed, including skeletal muscle index (SMI), sarcopenia, prognostic nutritional index (PNI), and postoperative complications. RESULTS: Tumour locations included the oesophagus (n = 17), stomach (n = 16), pancreas (n = 20), bile duct (n = 9), liver [n = 33; primary liver cancer (n = 18), liver metastasis (n = 15)], and colorectal region (n = 19). TC and FC levels varied significantly by tumour location. TC and FC showed significant positive correlations with SMI [TC (r = 0.295, P = 0.0014), FC (r = 0.286, P = 0.0020)] and PNI [TC (P = 0.0178, r = 0.222), FC (P = 0.0067, r = 0.2526)]. These levels were significantly lower in the sarcopenia group (TC, P = 0.0124; FC, P = 0.0243). In addition, TC and FC showed significant positive correlations with ALB level [TC (P = 0.038 r = 0.19), FC (P = 0.016 r = 0.23)]. When patients were divided into high ALB (≥3.5 g/dL, 96 patients) and low ALB (<3.5 g/dL, 18 patients) groups, these correlations were no longer significant, but in the low ALB group there was a tendency towards a negative relationship between ALB level and both TC and FC. No significant relationship was found between postoperative complications and carnitine level. CONCLUSIONS: This study suggests that carnitine level is a biomarker of sarcopenia and nutritional status. However, it did not find an association between carnitine level and postoperative complications.

Esophageal inflammatory pseudotumor with low-dose corticosteroid therapy after surgery.

Inflammatory pseudotumors of the esophagus are extremely rare, and the treatment has been controversial. Herein, we report a case of esophageal inflammatory pseudotumor with low-dose corticosteroid treatment following surgery. A 50-year-old woman with a 3-month history of progressive dysphagia and weight loss, was admitted to our hospital for examination and treatment. Esophagography and endoscopic examination revealed a mass present from the cervical esophagus to the upper thoracic esophagus with severe esophageal stricture. Ultrasound-guided fine needle aspiration cytology, boring biopsy, and mucosal incision-assisted biopsy reveal chronic inflammation, but histological diagnosis was not proven. Surgery was performed to confirm diagnosis and to relieve esophageal stricture. However, because of dense adhesions around the tumor, complete tumor resection was not achieved. Histopathological examination showed an inflammatory infiltrate with plasma cells, eosinophils, neutrophils, and lymphocytes, suggesting an inflammatory pseudotumor. After surgical resection, the esophageal stricture remained, possibly due to the residual tumor. We used a postoperative low-dose steroid treatment that resulted in complete resolution. There has not been any evident sign of recurrence for more than 2 years.

Preoperative skeletal muscle index and visceral-to-subcutaneous fat area ratio are associated with long-term outcomes of elderly gastric cancer patients after gastrectomy.

PURPOSE: Sarcopenia is a risk factor of severe surgical complications, short-term outcomes, and long-term outcomes for patients with gastric cancer. Several computed tomography (CT) measurements have been performed to diagnose sarcopenia. However, the optimal CT measurements for determining long-term outcomes have not been revealed. METHODS: A retrospective review of gastric cancer patients with clinical stage I, II, or III who underwent gastrectomy at age 75 years or more at Shizuoka General Hospital from 2007 to 2015 was performed. Using preoperative CT, skeletal muscle index (SMI), total psoas area, intramuscular adipose tissue content in multifidus muscle, morphologic change of psoas muscle, and visceral-to-subcutaneous adipose tissue area ratio (VSR) were measured in the third lumbar section. A Cox regression analysis was used to explore prognostic factors for overall survival. RESULTS: A total of 257 patients were reviewed. There were 171, 53, and 33 patients with clinical stages I, II, and III, respectively. A multivariate analysis indicated that, in addition to age, performance status, clinical stage, and types of resection, which are known prognostic factors, SMI and VSR are prognostic factors (p = 0.016, 0.046, respectively). The prognostic score, which was the frequency of positive SMI and VSR values within the cutoff, also indicates overall survival. The five-year OS rates of patients with prognostic scores of 0, 1, and 2 were 90.9%, 62.3%, and 52%, respectively (p < 0.001). CONCLUSION: Preoperative SMI and VSR were prognostic factors for the overall survival of elderly patients with gastric cancer after gastrectomy.

Hand-assisted robotic surgery in the abdominal phase of robot-assisted oesophagectomy.

Robot-assisted minimally invasive oesophagectomy (RAMIE) has been developed to overcome the technical limitations of conventional thoracoscopic oesophagectomy. Hand-assisted laparoscopic surgery (HALS) is used as a practical and useful technique during the abdominal phase of thoracoscopic oesophagectomy. During RAMIE, a robotic vessel sealer cannot be used with HALS; another vessel sealer or ultrasonic coagulating device for laparoscopic surgery is required. We report an initial experiment using hand-assisted robotic surgery (HARS) for abdominal manipulation during RAMIE as a novel method. Under the pneumoperitoneum induced by insufflating the abdomen to 10 mmHg with carbon dioxide, the assistant surgeon lifted the stomach and greater omentum using the left hand through a 7 cm upper abdominal midline incision at approximately 2 cm below the xiphoid. Subsequently, gastric mobilisation was performed by robot-assisted surgery. Between January 2019 and February 2020, eight patients with thoracic oesophageal cancer underwent RAMIE with HARS at our hospital. The median operative time for extracorporeal manipulation and preparation for the roll-in of the robot was 39.5 min. The median console time was 47.5 min. There were no intraoperative or postoperative complications related to the use of the robot and no in-hospital mortality. In conclusion, HARS seems to be feasible and safe for abdominal manipulation during oesophageal cancer surgery.

Duplicate left gastric artery identified during laparoscopic distal gastrectomy.

The reported incidence of duplicate left gastric artery is not very low, with a rate of 0.4%. However, there have been no reports of the surgical management of patients with a duplicate left gastric artery. Here, we report a 60-year-old Japanese man diagnosed with clinical T1bN0M0 stage IA gastric cancer. Preoperative 5-mm slice CT showed no anatomical abnormality, and the patient underwent laparoscopic distal gastrectomy. When we dissected the nerve plexus around the left gastric artery with an ultrasonic vessel-sealing device, pulsating bleeding was observed from a small vessel in the nerve plexus. The bleeding was stopped by suture and clipping. A 1.2-mm vessel was identified on 1-mm slice preoperative CT and postoperative CT angiography. The patient was discharged without any complications. To the best of our knowledge, this is the first report of a patient undergoing surgery for a duplicate left gastric artery.

Size of the thoracic inlet predicts cervical anastomotic leak after retrosternal reconstruction after esophagectomy for esophageal cancer.

BACKGROUND: Although an anastomotic leak after esophagectomy is one of the most common postoperative complications, it is not well understood whether specific anatomic factors of the different route of reconstruction can predispose to the development of anastomotic leak after esophagectomy. This study aimed to clarify whether various factors related to the size of the thoracic inlet are independent predictors of anastomotic leak after esophagectomy. METHODS: We reviewed 248 patients who underwent esophagectomy with retrosternal reconstruction of the gastric conduit between January 2013 and March 2019. Various factors related to the size of the thoracic inlet were measured using computed tomography. Multivariate logistic regression was used to analyze the association between various measurements and anastomotic leak. RESULTS: Anastomotic leak occurred in 38 patients (15.3%). On univariate analysis, the thickness of the sternum, the thickness of the clavicle, the sternum-trachea distance, the ratio of the sternum-trachea distance/sternum-vertebral body distance, sex, body mass index, and method of anastomosis were statistically significantly associated with anastomotic leak. On multivariate analysis, the ratio of the sternum-trachea distance/sternum-vertebral body distance and the method of anastomosis were the independent risk factors for anastomotic leak. CONCLUSION: The ratio of the sternum-trachea distance/sternum-vertebral body distance is associated with cervical anastomotic leak after retrosternal gastric conduit reconstruction after esophagectomy. Measurement of the thoracic inlet space may contribute to preoperative planning, such as for the route of the conduit for reconstruction and anastomotic site.

Video-assisted esophagectomy using a port-free organ retractor for the prevention of laryngeal nerve paralysis.

INTRODUCTION: Recurrent laryngeal nerve (RLN) paralysis is a major complication of esophageal cancer surgery. The free jaw clip (FJ clip) was developed as an organ-retracting device, and it can also reduce the number of ports required during surgery. Here, we describe a new technique for lymphadenectomy along the left RLN using the FJ clip. MATERIALS AND SURGICAL TECHNIQUE: After the middle and lower mediastinal lymph nodes were dissected, the upper esophagus and other tissues, including the lymph nodes and left RLN, were retracted by cutting the tracheal arteries between the esophagus and trachea and then pulling the upper esophagus to the dorsal side with the FJ clip. The esophagus was transected at the upper mediastinum, and the proximal esophagus was drawn by the FJ clip. This technique helped provide a good field of view during lymphadenectomy along the left RLN. The data of nine consecutive patients who underwent video-assisted esophagectomy in the left lateral decubitus position by the same surgeon were reviewed. Postoperative left RLN paralysis occurred in only one patient in whom the RLN could not be preserved. DISCUSSION: Given the excellent short-term outcomes with respect to left RLN paralysis, lymphadenectomy along the left RLN using the FJ clip was safe and feasible.

Emergency laparoscopic cholecystectomy for intraabdominal hemorrhage in a patient with a left ventricular assist device: a case report.

BACKGROUND: Continuous-flow left ventricular assist devices (LVADs), called "second generation LVADs," have significantly improved the survival and quality of life outcomes. Accordingly, non-cardiac surgery in a patient with LVADs has required for conditions not directly related to their LVADs. And the management of bleeding in non-cardiac site remains one of long-term critical topics. Laparoscopic approach is useful in a patient with LVADs; however, there have been only few clinical reports. This report describes the first case of laparoscopic cholecystectomy (LC) for intraabdominal hemorrhage from the gallbladder serosa in a patient with LVADs. CASE PRESENTATION: A 56-year-old man with an LVAD had undergone LVAD (Jarvik 2000™; Jarvik Heart, Inc., New York, NY, USA) implantation at 53 years of age. He was in shock, and contrast-enhanced computed tomography revealed abdominal hemorrhage from the gallbladder serosa. Emergency laparoscopic cholecystectomy was performed. We could avoid injury of the LVADs driveline, which was located across the upper abdominal midline, near the right hypochondriac region, by laparoscopic approach. LVADs (Jarvik 2000) did not disturb the operating field because of its smaller size. There were no intra- and postoperative complications. CONCLUSIONS: Laparoscopic approach is useful and safe in a patient with LVADs for abdominal surgery. We could perform LC for intraabdominal hemorrhage from gallbladder serosa safety.

A case of acute respiratory distress syndrome due to lymphography with Lipiodol for chylothorax after esophagectomy.

BACKGROUND: Lymphography with Lipiodol is useful for chylothorax. There were many slight complications, but reports of acute respiratory distress syndrome (ARDS) after lymphography were few. CASE PRESENTATION: A 75-year-old man with esophageal cancer developed chylothorax after esophagectomy. Conservative treatment was ineffective, and he underwent lymphography with 8.5 mL of Lipiodol. He developed a high fever soon after lymphography, followed by severe ARDS requiring artificial respiration 5 days later. He recovered from ARDS but subsequently developed pulmonary fibrosis and was discharged with domiciliary oxygen therapy 3 months later. CONCLUSION: Although ARDS is a rare complication of lymphography with Lipiodol, this procedure should be applied carefully in patients with chylothorax.

Hand grip strength as a predictor of postoperative complications in esophageal cancer patients undergoing esophagectomy.

BACKGROUND: Radical esophagectomy remains the primary treatment option for resectable esophageal cancer. However, it sometimes induces postoperative complications due to its invasive nature. Recently, the impact of loss of muscle mass on postoperative complications and survival among cancer patients has been highlighted. This study aimed to identify the impact of low hand grip strength (HGS) on postoperative complications after esophagectomy. METHODS: A total of 188 patients (male: 166, female: 22) who underwent radical esophagectomy with gastric tube reconstruction between 2008 and 2014 were included. The correlation between HGS and age was analyzed using Pearson's correlation coefficient. Due to the small patient numbers, only male patients were stratified into two groups according to age (<70 years: non-elderly group, ≥70 years: elderly group). Receiver operating characteristic curve analysis was performed for each group using postoperative complication occurrence as the endpoint to determine an optimal HGS cutoff value. RESULTS: Postoperative complications occurred in 60.9% of the elderly group and 47.4% of the non-elderly group. When the cutoff values were set at 30.5 and 37 kg for the elderly and non-elderly group, respectively, low HGS was an independent predictive factor of postoperative complications on multivariate analysis only in the elderly group (p = 0.008). In the elderly group, the incidence of postoperative pneumonia was 39.5% among patients with low HGS vs. 3.8% among patients with high HGS. CONCLUSION: Preoperative HGS is an independent predictive factor of postoperative complications, especially postoperative pneumonia, for elderly male patients with esophageal cancer treated with radical esophagectomy.

A long-surviving case of gastric cancer with main portal vein tumor thrombus after surgical resection and postoperative S-1 therapy.

Gastric cancer patients with main portal vein tumor thrombus usually have a short survival time, owing to its aggressive behavior. Herein, we report a long-surviving case of gastric cancer with main portal vein tumor thrombus. A 78-year-old man presenting with anorexia and body weight loss was diagnosed with gastric cancer. The patient was referred to our hospital for further examination and treatment. Endoscopy revealed a type 3 tumor (8.0 cm in length) in the body of the stomach. Biopsy led to the diagnosis of moderately differentiated adenocarcinoma. Enhanced computed tomography revealed a large tumor thrombus extending from the gastric coronary vein to the portal trunk. A total gastrectomy with lymphadenectomy, splenectomy, and thrombectomy was performed. Postoperative chemotherapy with S-1 was administered for 18 months. The patient died a natural death without recurrence at 49 postoperative months. To the best of our knowledge, the patient was the oldest to be diagnosed with gastric cancer with main portal vein tumor thrombus at diagnosis, who survived >36 months. Although gastric cancer with main portal vein tumor thrombus is a rare occurrence, its prognosis is extremely poor. Intensive surgery and long-term chemotherapy may be effective at improving survival time in these patients.

Video-assisted thoracoscopic esophagectomy in the left lateral decubitus position in an esophageal cancer patient with pectus excavatum.

During thoracic cavity operations, it is difficult to obtain sufficient working space and good operative field visibility in patients with pectus excavatum because the space between the vertebral bodies and sternum is very narrow. Here, we report the successful treatment of esophageal cancer in a patient with pectus excavatum. A 77-year-old man with esophageal cancer was referred to our hospital for further treatment. He was diagnosed with multiple early esophageal squamous cell carcinomas. The patient had pectus excavatum, but because it was asymptomatic, a video-assisted thoracoscopic radical esophagectomy in the left lateral decubitus position without pectus excavatum repair was selected. Despite the patient's unusual anatomy, video-assisted thoracoscopic esophagectomy in the left decubitus position allowed for good operative field visibility, as the videoscope was inserted from the side of the diaphragm. This operative procedure is useful in patients with esophageal cancer who also have pectus excavatum. To the best of our knowledge, this is the second report of video-assisted thoracoscopic esophagectomy in an esophageal cancer patient with pectus excavatum.

Control of oxalate formation from L-hydroxyproline in liver mitochondria.

Serine:pyruvate/alanine:glyoxylate aminotransferase (SPT/AGT) is largely located in mitochondria in carnivores, whereas it is entirely found within peroxisomes in herbivores and humans. In rat liver, SPT/AGT is found in both of these organelles, and only the mitochondrial enzyme is markedly induced by glucagon. Although SPT/AGT is a bifunctional enzyme involved in the metabolism of both L-serine and glyoxylate, its contribution to L-serine metabolism is independent of mitochondrial or peroxisomal localization (Xue HH et al., J Biol Chem 274: 16028-16033, 1999). Therefore, the species-specific and food habit-dependent organelle distribution might be required for proper metabolism of glyoxylate at the subcellular site of its formation. Glyoxylate formation from glycolate and that from L-hydroxyproline have been shown to occur in peroxisomes and mitochondria, respectively. The present study found that urinary excretion of oxalate was markedly increased when a large dose of L-hydroxyproline or glycolate was administered to rats. Oxalate formation from L-hydroxyproline but not that from glycolate was significantly reduced when mitochondrial SPT/AGT had been induced by glucagon. The hydroxyproline content of collagen is 10 to 13%, and collagen accounts for about 30% of total animal protein; therefore, these results suggest that an important role of mitochondrial SPT/AGT in carnivores is to convert L-hydroxyproline-derived glyoxylate into glycine in situ, preventing undesirable overflow into the production of oxalate.