A caspase inhibitor blocks ischaemia-induced delayed neuronal death in the gerbil

Caspases play a critical role in the cell death machinery in various cell types. Here we investigated the involvement of caspases in the delayed neuronal death after transient global forebrain ischaemia in the gerbil. Intrahippocampal injection of benzyloxycarbonyl-Asp-CH2-dichlorobenzene (zD), an irreversible inhibitor of caspases, saved hippocampal CA1 neurones from chromatin condensation and DNA fragmentation at post-ischaemia day 4, and these neurones maintained normal morphology at day 8 post-insult. Intrahippocampal injection of interleukin-1beta (IL-1beta) after ischaemic insults did not influence the neuroprotective effect of zD, suggesting that the neuroprotective effect does not depend on the inhibition of mature IL-1beta production. Animals that received zD-injection showed significant improvement in step-through and step-down passive avoidance learning at post-ischaemia days 4 and 5, suggesting that neural functions were preserved in these animals. At post-ischaemia day 4, the cleavage of poly(ADP-ribose)polymerase was observed, and this cleavage was almost completely suppressed in zD-injected hippocampus, suggesting involvement of caspase-3 and caspase-3-like caspase in the delayed neuronal death. Our findings indicate that caspases play important roles in the delayed neuronal death after transient global forebrain ischaemia in the gerbil, and suggest that ischaemia-induced brain damage can be blocked by caspase inhibitors.

A role for caspases in lens fiber differentiation

There is increasing evidence that programmed cell death (PCD) depends on a novel family of intracellular cysteine proteases, called caspases, that includes the Ced-3 protease in the nematode Caenorhabditis elegans and the interleukin-1beta-converting enzyme (ICE)-like proteases in mammals. Some developing cells, including lens epithelial cells, erythroblasts, and keratinocytes, lose their nucleus and other organelles when they terminally differentiate, but it is not known whether the enzymatic machinery of PCD is involved in any of these normal differentiation events. We show here that at least one CPP32 (caspase-3)-like member of the caspase family becomes activated when rodent lens epithelial cells terminally differentiate into anucleate lens fibers in vivo, and that a peptide inhibitor of these proteases blocks the denucleation process in an in vitro model of lens fiber differentiation. These findings suggest that at least part of the machinery of PCD is involved in lens fiber differentiation.

Imidazolone, a novel advanced glycation end product, is present at high levels in kidneys of rats with streptozotocin-induced diabetes

We produced a monoclonal antibody to imidazolones A and B, novel advanced glycation end products formed from the reaction of 3-deoxyglucosone (3-DG) with the guanidino group of arginine. Liquid chromatography/mass spectrometry demonstrated that the formation of imidazolone A by incubating 3-DG with arginine is very rapid, reaching a maximum concentration within 24 h, but the formation of imidazolone B is very slow and low in quantity even after 2 weeks. Thus, at physiological conditions the formation of imidazolone A is dominant, while that of imidazolone B is negligible. Immunochemistry demonstrated that the imidazolone content in the kidneys of streptozotocin-induced diabetic rats was significantly higher than in the control rats. Serum levels of 3-DG in the diabetic rats were also significantly higher than in control rats. 3-DG attacks the arginine residues of the tissue proteins, producing imidazolone at high levels in the kidneys affected by diabetic nephropathy.

Immunohistochemical detection of imidazolone, a novel advanced glycation end product, in kidneys and aortas of diabetic patients

To investigate the role of the Maillard reaction in the pathogenesis of diabetic complications, we produced several clones of monoclonal antibodies against advanced glycation end products (AGEs) by immunizing mice with AGE-modified keyhole limpet hemocyanin, and found that one clone (AG-1) of the anti-AGE antibodies reacted specifically with imidazolones A and B, novel AGEs. Thus, the imidazolones, which are the reaction products of the guanidino group of arginine with 3-deoxyglucosone (3-DG), a reactive intermediate of the Maillard reaction, were found to be common epitopes of AGE-modified proteins produced in vitro. We determined the erythrocyte levels of imidazolone in diabetic patients using ELISA with the monoclonal anti-imidazolone antibody. The imidazolone levels in the erythrocytes of diabetic patients were found to be significantly increased as compared with those of healthy subjects. Then we studied the localization of imidazolone in the kidneys and aortas obtained from diabetic patients by immunohistochemistry using the antibody. Specific imidazolone immunoreactivity was detected in nodular lesions and expanded mesangial matrix of glomeruli, and renal arteries in an advanced stage of diabetic nephropathy, as well as in atherosclerotic lesions of aortas. This study first demonstrates the localization of imidazolone in the characteristic lesions of diabetic nephropathy and atherosclerosis. These results, taken together with a recent demonstration of increased serum 3-DG levels in diabetes, strongly suggest that imidazolone produced by 3-DG may contribute to the progression of long-term diabetic complications such as nephropathy and atherosclerosis.

Psychological stress induced by 20 days bed rest

We investigated the changes of the psychological state during 20 days bed rest (BR) in 10 young participants,(5 males and 5 females, age; 19-24 yrs). Psychological assessment was accomplished by the following authorized 3 indices: 1) Zung's Self-rating Depression Scale, 2) Cornell Medical Index, and 3) Goldberg's General Health Questionnaire. Zung's Self-rating Depression Scale is a indicator for depression, and the other two indices were used for detecting signs of neurosis. The results from Zung's Self-rating Depression Scale and the General Health Questionnaire in this study indicated a tendency toward depression and neurosis developing during BR, respectively. The scores in the Cornell Medical Index did not change. Urinary excretion of 17-hydroxycorticosteroid increased significantly, indicating that BR immobilization induced an important psychological stress. We were unable to determine which factors caused the changes in psychological state during BR, immobilization insert or personal problems.

Portal tumor thrombi due to gastric cancer

A patient with a primary gastric carcinoma complicated with a tumor thrombus in the portal vein is described. Pancreatoduodenectomy with tube pancreatostomy was performed. The location and size of tumor thrombi in the portal vein could be determined accurately by intraoperative ultrasonography and removed with the wall of the portal vein and superior mesenteric vein. There was no evidence of recurrence one year after the operation. Tumor thrombus in the portal vein in gastric cancer is rarely reported and has a poor prognosis. If there is no associated liver metastasis, aggressive surgical approach followed by appropriate chemotherapy may prolong the life of the patient.

Programmed cell death by default in embryonic cells, fibroblasts, and cancer cells

We recently proposed that most mammalian cells constitutively express all of the proteins required to undergo programmed cell death (PCD) and undergo PCD unless continuously signaled by other cells not to. Although some cells have been shown to work this way, the vast majority of cell types remain to be tested. Here we tested purified fibroblasts isolated from developing or adult rat sciatic nerve, a mixture of cell types isolated from normal or p53-null mouse embryos, an immortalized rat fibroblast cell line, and a number of cancer cell lines. We found the following: 1) All of these cells undergo PCD when cultured at low cell density in the absence of serum and exogenous signaling molecules but can be rescued by serum or specific growth factors, suggesting that they need extracellular signals to avoid PCD. (2) The mixed cell types dissociated from normal mouse embryos can only support one another's survival in culture if they are in aggregates, suggesting that cell survival in embryos may depend on short-range signals. (3) Some cancer cells secrete factors that support their own survival. (4) The survival requirements of a human leukemia cell line change when the cells differentiate. (5) All of the cells studied can undergo PCD in the presence of cycloheximide, suggesting that they constitutively express all of the protein components required to execute the death program.

Appraisal of intraoperative ultrasonography during laparoscopic cholecystectomy

BACKGROUND

The usefulness of intraoperative ultrasonography during laparoscopic cholecystectomy (LC) has yet to be evaluated fully.

METHODS

In 50 patients who underwent LC, the intraoperative ultrasonography findings were compared with those of preoperative ultrasonography, intraoperative cholangiography, and histology, and then its usefulness for examining anatomic relationships in the hepatoduodenal ligament, detecting bile duct stones, diagnosing gallbladder polyps and abnormally thickened walls, and determining the propriety of LC was appraised.

RESULTS

The preoperative ultrasonography diagnoses were gallstones in 38 patients, polyps in 10, and cancer and adenomyomatosis in one each. In four patients endoscopic retrograde cholangiography showed bile duct stones. In all 50 patients intraoperative ultrasonography was useful for examining the anatomic relationships between the bile duct and vessels, such as the portal vein and hepatic artery, and showing the presence or absence of bile duct stones. On the basis of the intraoperative ultrasonography findings, gallstones were diagnosed in 38 patients, in five of whom bile duct stones were shown clearly, cholesterol polyps in eight, early-stage cancer or adenoma in two, and adenomyomatosis in two, and subsequently LC was performed. Histologic diagnoses of cholesterol polyps were made in eight of ten patients with polyps, and intramucosal cancer and an inflammatory polyp in one each. In one patient with a preoperative diagnosis of cancer the apparently elevated flat lesion was found to be partial thickening of the gallbladder wall, which was diagnosed as adenomyomatosis, and LC was chosen as the operative procedure.

CONCLUSIONS

Intraoperative ultrasonography during LC is useful for detecting bile duct stones, diagnosing gallbladder polyps and abnormally thickened walls, and deciding whether LC is adequate for resection of the gallbladder.

Healing process of sutureless choledochojejunostomy in an experimental model

The healing characteristics and morphological features of sutureless choledochojejunostomy were investigated in a rat experimental model. The common bile duct of 34 conditioned Wistar rats was exposed, divided transversely and a choledochojejunostomy constructed with only a vinyl chloride tube positioned between the common duct and jejunum. The animals were killed 4, 12 and 52 weeks after surgery. Cholangiographic evaluation of the anastomosis in all three groups showed wide openings with dilatation of the extrahepatic bile duct. Microscopic examination of the anastomosis showed hyperplastic changes of the bile duct epithelium. The epithelial defect was completely covered with proliferative epithelium 12 weeks after operation. At long-term follow-up of 52 weeks there were no biliary strictures after the sutureless technique. This surgical approach may be useful for patients in whom sutured anastomosis of the bile duct might lead to stricture, such as those with a normal thin-walled bile duct.

How should polypoid lesions of the gallbladder be treated in the era of laparoscopic cholecystectomy?

BACKGROUND

Definitive criteria for choosing the most appropriate treatment for each type of polypoid lesion of the gallbladder (PLG) have yet to be established.

METHODS

The shapes, sizes, echo patterns, and echogenicities of PLGs that had been evaluated by means of ultrasonography in 72 patients who had undergone resective surgery were analyzed retrospectively to elucidate the ultrasonic characteristics of polypoid cancers and to establish criteria for selecting the most suitable treatment such as laparoscopic cholecystectomy for each type of PLG.

RESULTS

Histologic examinations showed cholesterol polyps in 47 patients, adenomas in 8, cancers in 16, and an inflammatory polyp in 1. The diameters of 61% of the benign PLGs were less than 10 mm, whereas those of 88% of the cancers were more than 10 mm; 80% of the former were pedunculated and 56% of the latter were sessile. Seven of eight early-stage cancers had diameters less than 18 mm, whereas those of all eight more advanced cancers were greater than 18 mm. Five of the eight early-stage cancers were pedunculated, and six of the eight more advanced cancers were sessile. Cholecystectomy with or without full-thickness dissection were main surgical procedures used to resect benign PLGs and early-stage cancers, whereas cholecystectomy with partial liver resection was used for more advanced cancers. Laparoscopic cholecystectomy was performed in the recent 34 patients, four of whom had early-stage cancers.

CONCLUSIONS

A PLG with a diameter of less than 18 mm is a potential early-stage cancer and therefore can be resected by laparoscopic cholecystectomy with full-thickness dissection. However, when cancer invades the subserosal layer or beyond, a second-look operation is necessary. A PLG with a diameter of greater than 18 mm may be an advanced cancer and should be removed by using cholecystectomy with partial liver resection or a more extended procedure with lymph node dissection.

Role of the heparin-binding domain of chimeric peptides derived from fibronectin in cell spreading and motility

Cellular responses to fibronectin (FN) are likely to have a complex molecular basis involving the interactions between multiple functional domains of FN and specific cell surface molecules. We have utilized several types of recombinant FN fragments and their chimeric fragments to examine the regulatory mechanisms of the spreading and chemotactic migration of HT1080 human fibrosarcoma cells on FN. The CH-271 fusion fragment, in which the cell-binding domain (C-274) of FN is adjacent to the heparin-binding domain (H-271), promoted cell spreading more efficiently than C-274, H-271, or their mixture (C-274 + H-271) over a 60-min incubation. The CH-271 variants containing various modules in the heparin-binding domain (CHV peptide) showed different promotion of cell migration, spreading, and vinculin accumulation at focal adhesion, respectively. The preincubation of the cells with heparitinase I resulted in significant inhibition of chemotactic migration to FN and its fragments containing the III13 and/or III14 modules of the heparin-binding domain. Additionally, migration to CH-271 was inhibited by the presence of the RGDS peptide in a concentration-dependent fashion. Thus, the spread and migration responses of HT1080 cells onto FN fusion peptides require the adjacent coexistence of cell- and heparin-binding domains and are mediated by the interactions between cell surface heparan sulfate and the heparin-binding domain, in concert with the interaction between cell surface integrin and the cell-binding domain. In conclusion, our present study demonstrated that fusion peptides of fibronectin can efficiently induce two signals from the cell-binding and heparin-binding domains required for the completion of cell spreading, the formation of focal contact, and motility at the early stage of the culture, suggesting that the III13 or III14 modules within the heparin-binding domain are responsible for the initiation of different cellular responses.

[Clinical evaluation of a new parenteral cephem, cefozopran, in children]

Cefozopran (CZOP, SCE-2787), a new parenteral cephem, was evaluated for its antibacterial activity and clinical efficacy. CZOP, 24.0-78.0 mg/kg/day, was given to 11 pediatric patients in 3 dose a day via 30-minute drip infusion. Clinically evaluated were nine patients including 4 with acute pneumonia, 2 with urinary tract infections, 2 with lymphadenitis and 1 with sepsis. Two patients were excluded because of possible non-bacterial infections. Clinical efficacies were excellent in 5, good in 3 and fair in 1. Bacteriological responses were confirmed for 5 strains in 5 patients. Four strains were eradicated, but one strain was not. MICs of CZOP were equal to those of ceftazidime. Side effects or abnormal laboratory test results were observed in 3 patients; diarrhea in 1, elevated GPT in 1 and thrombocytosis in 1, but none of them was significant.

Programmed cell death and the control of cell survival

We draw the following tentative conclusions from our studies on programmed cell death (PCD): (i) the amount of normal cell death in mammalian development is still underestimated; (ii) most mammalian cells constitutively express the proteins required to undergo PCD; (iii) the death programme operates by default when a mammalian cell is deprived of signals from other cells; (iv) many normal cell deaths may occur because cells fail to obtain the extracellular signals they need to suppress the death programme; and (v) neither the nucleus nor mitochondrial respiration is required for PCD (or Bcl-2 protection from PCD), raising the possibility that the death programme, like mitosis, is orchestrated by a cytosolic regulator that acts on multiple organelles in parallel.

Autocrine signals enable chondrocytes to survive in culture

We recently proposed that most mammalian cells other than blastomeres may be programmed to kill themselves unless continuously signaled by other cells not to. Many observations indicate that some mammalian cells are programmed in this way, but is it the case for most mammalian cells? As it is impractical to test all of the hundreds of types of mammalian cells, we have focused on two tissues--lens and cartilage--which each contain only a single cell type: if there are cells that do not require signals from other cells to avoid programmed cell death (PCD), lens epithelial cells and cartilage cells (chondrocytes) might be expected to be among them. We have previously shown that rat lens epithelial cells can survive in serum-free culture without signals from other cell types but seem to require signals from other lens epithelial cells to survive: without such signals they undergo PCD. We show here that the same is true for rat (and chick) chondrocytes. They can survive for weeks in culture at high cell density in the absence of other cell types, serum, or exogenous proteins or signaling molecules, but they die with the morphological features of apoptosis in these conditions at low cell density. Medium from high density cultures, FCS, or a combination of known growth factors, all support prolonged chondrocyte survival in low density cultures, as long as antioxidants are also present. Moreover, medium from high density chondrocyte cultures promotes the survival of lens epithelial cells in low density cultures and vice versa. Chondrocytes isolated from adult rats behave similarly to those isolated from developing rats. These findings support the hypothesis that most mammalian cells require signals from other cells to avoid PCD, although the signals can sometimes be provided by cells of the same type, at least in tissues that contain only one cell type.

Risk factors influencing the short-term results of gastroduodenal perforation

The purpose of this study was to evaluate the risk factors influencing the short-term results of gastroduodenal perforation to determine the optimal treatment for reducing mortality. A total of 136 patients were retrospectively reviewed and the prognostic factors were examined. Seven patients died within 30 days, with an overall mortality rate of 5.1%. Mortality was significantly worse in those aged 50 years or more, when the leukocyte count was less than 9,500/mm3, when treatment was delayed more than 12h after perforation, in cases of preoperative shock and renal failure, and when associated with liver cirrhosis or an immunocompromised state. Tolerance to the time delay was inversely proportional to age, while the deaths in patients aged 65 years or younger were related to serious concurrent diseases. Shock and renal failure occurred most often in elderly patients as a result of delayed surgery, and the leukocyte count was an age-dependent prognostic indicator. Thus, age, the time interval between perforation and treatment, serious concurrent disease, shock, and renal failure were presumed to be the most important prognostic factors. Although definitive operations were performed on low-risk patients with an acceptably low mortality, it remains to be determined whether simpler procedures should be adopted for high-risk patients.

Inhibitory effect of recombinant fibronectin polypeptides on the adhesion of liver-metastatic lymphoma cells to hepatic sinusoidal endothelial cells and tumor invasion

We have investigated the inhibitory mechanism of the initial arrest of L5178Y-ML25 lymphoma cells in a target organ (liver) by using recombinant fibronectin fragments with cell- and/or heparin-binding domains (C-274, H-271 or the fusion fragment CH-271). Pretreatment of hepatic sinusoidal endothelial (HSE) cell monolayers with lymphoma cells or their conditioned medium for 4 to 6 h resulted in the enhancement of lymphoma cell adhesion to HSE cell monolayer. The increased tumor adhesiveness was completely abolished by preincubation of the conditioned medium with anti interleukin-1 beta monoclonal antibody (mAb). Synthetic sialyl Le(x) (SLe(x)) as a ligand for endothelial cell leukocyte adhesion molecule-1 (ELAM-1) adhesion receptor and anti ELAM-1 mAb blocked the conditioned medium-induced enhancement of tumor-endothelial cell interaction, while pretreatment of the activated HSE cell monolayer with anti vascular cell adhesion molecule-1 (VCAM-1) mAb did not affect the enhanced tumor cell adhesion. These results indicate that tumor cell interaction with the stimulated HSE cells is mediated by ELAM-1 molecules on HSE cells. However, the expression of SLe(x) and SLe(a) on the tumor surface was not observed by flow cytometric analysis. ELAM-1-mediated enhancement of tumor cell adhesion to HSE monolayer was also inhibited in a concentration-dependent manner by CH-271 fusion polypeptide or the sulfated chitin derivative sulfated carboxymethyl-chitin, which can bind to the heparin-binding domain of CH-271. In addition, CH-271 inhibited not only tumor-endothelium interaction but also tumor cell invasion into reconstituted basement membrane Matrigel in vitro.

Surgical implications of preduodenal portal vein in the adult. Case report and review of the literature

Occasionally, a preduodenal portal vein (PDPV) is found in pediatric patients with intestinal obstruction due to duodenal compression. In adults, it is often symptom-less and is an exceptionally rare condition. It is of surgical importance, however, because the vein lies in the most superficial position ventral to the common bile duct and is easily damaged during operations involving the biliary tract and duodenum. We recently treated a patient with PDPV, which stimulated a review of the disease process, including diagnosis, association with other anomalies, and surgical treatment.

[Gallstones in liver cirrhosis]

The prevalence of gallstones in cirrhotic patients has been found to be higher than in the general population, by at least twofold. Of this increment, the majority of stones are of the pigment type in the gallbladder. The composition of black stone is unique because of the large fraction of unconjugated bilirubin, which is present as calcium bilirubinate or in an undefined polymeric form. There is little doubt that biliary surgery is hazardous in cirrhotic patients. Elective surgery for symptomatic Child A and B patients would normally be warranted. For Child C patients with life-threatened cholecystitis or cholangitis, every type of medical treatment should be attempted. After considering the bleeding tendency or ascites, percutaneous transhepatic gallbladder drainage or endoscopic sphincterotomy is considered to be one of the treatments.

Magnetic resonance cholangiography for evaluation of obstructive jaundice

OBJECTIVES

Magnetic resonance (MR) cholangiography is a newly developed adjunctive tool for noninvasive evaluation of patients with obstructive jaundice. We discuss whether MR cholangiography can provide useful information about the biliary tract, compared with other diagnostic modalities.

METHODS

MR cholangiographies of 20 patients with obstructive jaundice were reviewed to evaluate the site of obstruction, the cause of obstruction, and the degree of stricture.

RESULTS

The precise location of an obstructing lesion and complete display of the dilated biliary tree just proximal to the obstruction were provided in all 20 patients by MR cholangiography the same as in direct cholangiography. MR cholangiography could completely distinguish common duct stones from malignancies, whereas accurate differentiation among the malignancies was impossible. In six patients, MR cholangiography was not able to help in differentiating between high-grade stenosis and complete occlusion.

CONCLUSION

Although precise cholangiographic estimation of the morphology and extent of the malignant disease by MR cholangiography was inferior to direct cholangiography, MR cholangiography is easily performed for a short duration and is a noninvasive diagnostic modality for assessing the outline of the anatomy of the dilated biliary tree. Therefore, we recommend promptly performing MR cholangiography if obstructive jaundice is suspected on clinical grounds.

Programmed cell death and the control of cell survival: lessons from the nervous system

During the development of the vertebrate nervous system, up to 50 percent or more of many types of neurons normally die soon after they form synaptic connections with their target cells. This massive cell death is thought to reflect the failure of these neurons to obtain adequate amounts of specific neurotrophic factors that are produced by the target cells and that are required for the neurons to survive. This neurotrophic strategy for the regulation of neuronal numbers may be only one example of a general mechanism that helps to regulate the numbers of many other vertebrate cell types, which also require signals from other cells to survive. These survival signals seem to act by suppressing an intrinsic cell suicide program, the protein components of which are apparently expressed constitutively in most cell types.

Safe intraabdominal pressure of carbon dioxide pneumoperitoneum during laparoscopic surgery

BACKGROUND

The deliberate induction of carbon dioxide pneumoperitoneum during laparoscopic surgery could be a possible source of cardiovascular collapse. The effects of elevated intraabdominal pressure (IAP) on systemic hemodynamics and splanchnic blood flow created by insufflation of carbon dioxide were examined in anesthetized dogs.

METHODS

Stepwise increases in IAP of 8 (n = 7), 12 (n = 7), and 16 (n = 7) mm Hg were applied to determine the threshold pressure that had minimum influence on these hemodynamics. Hemodynamic parameters were measured at baseline and 1, 2, and 3 hours after the start of insufflation.

RESULTS

At an IAP of 16 mm Hg, cardiac output was decreased significantly by 1 hour after the start of insufflation and became progressively lower during the procedure. Systemic vascular resistance was elevated significantly in parallel with the change in cardiac output. Although hepatic arterial blood flow was not decreased significantly, portal venous and superior mesenteric arterial blood flows were diminished significantly at 16 mm Hg, resulting in a decrease in total hepatic blood flow. No significant changes were observed in these parameters at 8 or 12 mm Hg.

CONCLUSIONS

Based on these results, an IAP from 8 to 12 mm Hg is recommended for laparoscopic surgery, to avoid complications caused by hemodynamic derangements.

Changes in splanchnic blood flow and cardiovascular effects following peritoneal insufflation of carbon dioxide

Laparoscopic surgery has rapidly become a popular and widely used technique. Although this procedure has been shown to be generally safe, cardiovascular derangement related to carbon dioxide pneumoperitoneum has been reported. There are few data available on the relationship between systemic and regional hemodynamics in cases of pneumoperitoneum. Changes in splanchnic blood flow and cardiovascular effects following a moderate increase of intraabdominal pressure (IAP) to 16 mmHg during a 3-h period were analyzed in six anesthetized dogs. After insufflation, cardiac output and blood flow in the superior mesenteric artery and portal vein decreased progressively and returned to the preinsufflation values following deflation. Hepatic arterial blood flow did not change significantly, perhaps due to compensatory mechanisms for maintenance of hepatic blood flow. Mechanical compression of the splanchnic capillary beds due to the elevated IAP may possibly reflect the increase in systemic vascular resistance causing the decrease in cardiac output. To prevent this impairment, intermittent decompression of gas during surgical laparoscopy is recommended.

Evaluation of diagnostic criteria of acute renal failure in premature infants

A prospective study was performed to investigate the validity of renal failure index (RFI) or fractional excretion of sodium (FENa) in preterm infants. The subjects were 128 newborn infants, 72 with oliguria and 56 without renal dysfunction (control). Oliguric infants were divided into two categories: acute renal failure (ARF) and prerenal failure (PRF), according to creatinine clearance (Ccr). Furthermore, all subjects were divided into four groups according to gestation, that is, 38 infants with gestational age of 25-28 weeks (group 1), 28 with 29-30 weeks (group 2), 38 with 31-36 weeks (group 3) and 24 of > 37 weeks (group 4). As a result, differentiation between ARF and PRF was valid when the RFI or FENa was used in infants of > 29 weeks gestation (groups 2, 3 and 4). Although infants of > 31 weeks gestation (groups 3 and 4) who present with an RFI > 3 or an FENa > 3% may be diagnosed as having ARF, infants in group 2 with an RFI of > 8 or an FENa of > 6% may be diagnosed as having ARF. For the infants in group 1, the application of RFI or FENa for diagnosis of ARF may be limited because of some overlap among the groups.