Endogenous tumor necrosis factor exerts its protective function intracellularly against the cytotoxicity of exogenous tumor necrosis factor.

Based on the findings that expression of endogenous tumor necrosis factor (enTNF), which is not present in TNF-susceptible cells, was generally observed in TNF-resistant cells and that TNF gene transfection gives rise to TNF resistance, the assumption was made that enTNF may be a protective protein against the cytotoxicity of exogenous TNF. However, it remains unknown whether the protection by enTNF is exerted in an intracellular or extracellular (autocrine) manner. We therefore transfected a nonsecretory human TNF gene (pTNF delta pro) into highly TNF-sensitive mouse tumorigenic fibroblasts (L-M cells) and investigated their TNF susceptibility. The transfectants expressed enTNF which was not secreted into the medium and acquired an appreciable degree of resistance to exogenous TNF. A significant increase in the manganous superoxide dismutase level was also noted in the transfectants. These findings suggest that enTNF exerts its protective function intracellularly by inducing manganous superoxide dismutase production.     

Endogenous tumor necrosis factor functions as a resistant factor against hyperthermic cytotoxicity.

One of the mechanisms of cytotoxicity by tumor necrosis factor (TNF) is the induction of reactive oxygen molecules. Cells producing endogenous tumor necrosis factor (enTNF) show resistance to the cytotoxicity of exogenous TNF by scavenging the reactive oxygen molecules. The intracellular hydroxyl radical production is also known to be involved in the heat-induced cytotoxicity. In the present study, we therefore examined the possibility that enTNF may act as a protective protein against the heat-induced cytotoxicity in a manner similar to that of exogenous TNF. Heat-sensitive L-M (mouse tumorigenic fibroblast) cells, originally expressing no enTNF, were transfected with a human TNF expression vector to produce enTNF. The stable transfectants showed apparent resistance to heat treatment. Conversely, when HeLa (human uterine cervical cancer) cells, originally producing an appreciable amount of enTNF, were transfected with an antisense TNF mRNA expression vector to inhibit enTNF synthesis, their heat sensitivity was enhanced. Furthermore, L-M cells which were transfected with nonsecretory human TNF expression vector also acquired resistance to heat treatment. In these cells, heat resistance correlated well with expression of enTNF and intracellular levels of manganous superoxide dismutase. These results indicate that enTNF exerts its intracellular protective effect against the heat-induced cytotoxicity by scavenging reactive oxygen with induced manganous superoxide dismutase in a manner similar to that found in cells treated with exogenous TNF.     

A case of retroperitoneal mucinous cystadenoma of borderline malignancy

Surgical experience of a rare case of malignant retroperitoneal cyst is reported. A 41-year-old female was admitted on Feb. 26, 1986, complaining of left lower abdominal tumor and mild abdominal pain. She underwent complete removal of an abdominal tumor located at the left flank lateral to the sigmoid colon on March 5. The tumor was well encapsulated, cystic and oval, 12 X 10 X 9 cm in size. Histologic feature of the tumor is classified as mucinous cystadenoma of low grade malignancy by WHO classification.     

Purification of B16-F1 melanoma autocrine motility factor and its receptor.

Tumor autocrine motility factor (AMF) is a cytokine which stimulates both random and directed cell migration by self-producing cells. AMF has been detected in and purified from serum-free conditioned medium of murine B16-F1 melanoma cells. Under nonreducing conditions AMF migrates in sodium dodecyl sulfate-polyacrylamide gel electrophoresis as a single band of Mr 55,000, whereas under reducing conditions it migrates as a single polypeptide of Mr 64,000. Two-dimensional polyacrylamide gel electrophoresis of the purified AMF resolved two polypeptides with isoelectric points of 6.35 (major) and 6.4 (minor). No carbohydrate side chains were detected in the B16-F1 AMF. Purified AMF stimulated B16-F1 cell migration in a dose-dependent fashion and bound directly in a protein-protein-binding assay to the AMF receptor, a cell surface glycoprotein of Mr 78,000 [glycoprotein (gp) 78]. The involvement of gp78 in AMF-stimulated function was demonstrated by motility assays. These results suggest that AMF is the natural ligand for the gp78-AMF receptor.     

Lack of prostanoid receptor involvement in ischemic acute renal failure in mice

Background. Thromboxane (TX) A₂ inhibition or prostaglardin (PGI₂) infusion prevents ischemic acute renal failure (ARF) in animal models. However, the pathophysiological roles of the prostanoid receptors in the development of ischemic ARF are not fully understood, partly because of the limited specificity of their inhibitors or antagonists. Methods. We investigated whether targeted disruption of the PGI₂ receptor (IP) or TXA₂ receptor (TP) genes conferred susceptibility to renal ischemic-reperfusion injury, using IP and TP knockout mice. Results. Serum creatinine concentration in TP knockout mice was not significantly different from that in wild-type controls. There were no significant histological differences between TP knockout and wild-type mice. Likewise, IP knockout mice showed no significant differences from the wild-type controls in regard to creatinine concentration or histological damage. Conclusions. Lack of TP or IP had no influence on postischemic ARF in mice, indicating that receptors for TXA₂ or PGI₂ may have minimal roles in the development of this mouse model of ischemic ARF. Received: July 5, 2001 / Accepted: April 8, 2002     

Diffuse heterotopic submucosal cystic malformation of the stomach: ultrasonographic diagnosis.

The preoperative diagnosis of diffuse heterotopic submucosal cystic malformation of the stomach is very difficult to make with upper gastrointestinal (GI) series or endoscopy. We report a case of submucosal cysts associated with an early gastric carcinoma in which ultrasonography (US) and endoscopic ultrasonography (EUS) were very useful in the preoperative diagnosis.     

Plasma Ratios of Tryptophan and Tyrosine to Other Large Neutral Amino Acids in Manic-Depressive Patients

Abstract: The plasma ratio of each neutral amino acid (tryptophan (TRP), tyrosine (TYR), valine, isoleucine, leucine (LEU) or phenylalanine) to the sum of the other neutral amino acids was measured in 16 : manic and 14 : depressed patients. In the manics, there was a correlation between the psychomotor activity and the plasma TRP and LEU ratios. In the depressives, the depressed mood, retardation and global severity were correlated with the TRP ratio. The zotepine responders showed an increase in the TRP ratio after treatment. In the mianserin responders, the TYR ratio, which was high before the treatment, decreased to the normal range after the treatment. But, the plasma amino acid ratios remained unchanged in the patients treated with lithium carbonate or amitriptyhe. These results suggest that, in manic-depressive illness, there might be abnormalities in the metabolism of neutral amino acids, mainly of TRP and TYR, and that the plasma TRP and TYR ratios might be important indicators for determining the efflcacy of some drugs.     

Cyclic AMP elicits biphasic current whose activation is mediated through protein phosphorylation in snail neurons.

The involvement of protein phosphorylation in cAMP-induced transmembrane current was tested electrophysiologically and pharmacologically in identified neurons of the Japanese land snail, Euhadra peliomphala. Intracellular injection of cAMP elicited a biphasic transmembrane current (cAMP current) which consisted of inward and outward components. The inward component was blocked with Na(+)-free, Ca2(+)-free saline and the outward component abolished by either application of tetraethylammonium or a long-lasting exposure to caffeine in Ca2(+)-free saline. The cAMP current was completely suppressed by the protein kinase inhibitors, protein kinase inhibitor isolated from rabbit muscle or isoquinoline sulfonamide (H-8). The catalytic subunit of cAMP-dependent protein kinase transiently restored the cAMP current suppressed by H-8 nearly to pre-H-8 level. These findings suggest that protein phosphorylation may be an intermediate step in the activation process of the cAMP current.