Enhancement of leptin receptor signaling by SOCS3 deficiency induces development of gastric tumors in mice.

Leptin acts on its receptor (ObR) in the hypothalamus to inhibit food intake and energy expenditure. Leptin and ObR are also expressed in the gastrointestinal tract; however, the physiological significance of leptin signaling in the gut remains uncertain. Suppressor of cytokine signaling 3 (SOCS3) is a key negative feedback regulator of ObR-mediated signaling in the hypothalamus. We now show that gastrointestinal epithelial cell-specific SOCS3 conditional knockout (T3b-SOCS3 cKO) mice developed gastric tumors by enhancing leptin production and the ObRb/signal transducer and activator of transcription 3 (STAT3) signaling pathway. All T3b-SOCS3 cKO mice developed tumors in the stomach but not in the bowels by 2 months of age, even though the SOCS3 deletion occurred in both the epithelium of stomach and bowels. The tumors developed in the absence of the inflammatory response and all cKO mice died within 6 months. These tumors displayed pathology and molecular alterations, such as an increase in MUC2 (Mucin 2, oligomeric mucus/gel-forming) and TFF3 (trefoil factor 3), resembling human intestinal-type gastric tumors. Administration of antileptin antibody to T3b-SOCS3 cKO mice reduced hyperplasia of gastric mucosa, which is the step of the initiation of gastric tumor. These data suggest that SOCS3 is an antigastric tumor gene that suppresses leptin overexpression and ObRb/STAT3 hyperactivation, supporting the hypothesis that the leptin/ObRb/STAT3 axis accelerates tumorigenesis and that it may represent a new therapeutic target for the treatment of gastric cancer.

Percutaneous hydrodynamic thrombectomy for congenital deep vein thrombosis in a neonate.

A 1-day-old boy with a complete occlusive inferior vena cava and bilateral renal vein thrombus removed successfully using a hydrodynamic thrombectomy catheter is reported. Although blood flow to the inferior vena cava and bilateral renal veins was restored with no distal embolism or vascular injury, he died of bleeding complications due to fibrinolytic therapy after hydrodynamic thrombectomy. To the best of our knowledge, this is the first report of hydrodynamic thrombectomy of a neonate.

[Two cases of the epidermoid on the petrous bone].

Epidermoids known as cholesteatomas, are congenital benign tumors and originate in the embryonic ectoderm. They account for 1.3% of all intracranial tumors. They are often found in the cerebellopontine angle and the paraseller region, but rarely in the petrous portion of the temporal bone. Epidermoids of the petrous bone tend to slowly present progressive facial palsy and hearing disturbance. In this article, two cases of epidermoids involving the petrous bone are reported. A 55-year-old male presented left facial palsy, left hearing disturbance and decreased gustation in the left side of the tongue. MRI revealed a non-enhanced mass on the petrous portion of the left temporal bone, and bone-window CT showed bone destruction in the same region (Case 1). A 71-year-old female was aware of left facial palsy and left hearing loss for 15 years. MRI showed a non-enhanced mass on the petrous bone, and bone-window CT demonstrated extensive bone erosion of the petrous bone and the middle cranial fossa (Case 2). In both cases, total removal was performed via the middle cranial fossa approach. Both tumors existed extradurally and had pressed against the genicurate ganglion of the facial nerve. The facial palsy of the former case recovered 12 months after surgery. We discuss the problems of diagnosis and treatment of epidermoids of the petrous bone.

Antitumor active protein-containing glycans from the Chinese mushroom songshan lingzhi, Ganoderma tsugae mycelium.

A water-soluble polysaccharide, FI, extracted from the mycelium of Granoderma tsugae, was fractionated and purified by ion-exchange chromatography, gel filtration, and affinity chromatography. Sixteen polysaccharides obtained were examined for antitumor effects on Sarcoma 180 in mice. The three active polysaccharides obtained were as follows: FIo-a: A glycan-protein complex containing 9.3% protein, and having a hetero-glyco-chain of mannose and xylose. FIo-b-alpha: Molecular weight 10,000, glucan-protein complex containing 25.8% protein. The inhibition ratio was 61.8% against the solid cancer Sarcoma 180/mice; the survival ratio was more than 194% of the control group (100). FA-1-b-alpha: Molecular weight 16,000, a complex of glycan:protein = 42:58 w/w, consisting of glucose as a main component, and associated with arabinose, mannose, xylose, and galactose. This had a tumor inhibition ratio of 56% and a survival ratio of more than 182%. Comparison of active glycan with the fruiting body and mycelium: Among water-soluble polysaccharides of fruiting body, FIo-a and FA-1, with antitumor activity, were both glucogalactan-protein complexes of molecular weight 10,000, but that of mycelium was a homoglucan protein complex in FIo-b-alpha and heteroglucan protein in both FA-1-a and FA-1-b-alpha. The heteroglucan had a low tumor inhibition ratio, but caused a high survival ratio in mice.

Essential role of His163 of cytochrome P450 1A2 in catalytic functions associated with cytochrome b5.

The effect of cytochrome b5 on the activity of cytochrome P450 1A2 (P450 1A2) and three site-directed mutants designed to alter surface charges has been investigated. Cytochrome b5 increased the rate of oxidation of methanol and/or 7-ethoxycoumarin 2- to 10-fold in both wild type and mutant P450. Cytochrome b5 also increased the coupling of electron transfer to substrate hydroxylation as opposed to the uncoupling reaction which leads to peroxide production. The effect of cytochrome b5 on both wild type and the Lys99Glu and Lys401Glu mutants are similar. In contrast, turnover numbers in the His163Glu mutant did not change in the presence of cytochrome b5. The reduction potential of the His163Glu mutant decreased approximately -40 mV while the Lys99Glu and Lys401Glu mutants exhibited little change. The rate of photoreduction decreased from 1.1 x 10(-1) min-1 to 8.3 x 10(-3) min-1 in the His163Glu mutant while the rate of electron transfer from ferrous P450 to ferric cytochrome b5 increased from 0.02 min-1 to > 5 min-1. Overall, the present study suggests that His163 is important to keep an appropriate redox potential of P450 1A2 for optimum electron transfer to occur from cytochrome b5. Based on the P450 101 crystal structure, His163 is not expected to directly contact the heme. Therefore, the resulting change in redox properties in the His163Glu mutant is probably not the result of a direct electrostatic change in the heme environment.

Effect of mutations of ionic amino acids of cytochrome P450 1A2 on catalytic activities toward 7-ethoxycoumarin and methanol.

Catalytic efficiencies, percentages of rates of product formation per NADPH oxidized, and rates of product formation per O2 consumed of ionic mutants of cytochrome P450 1A2 (P450 1A2) were studied. Efficiencies of Lys99Glu, Lys453Glu, and Arg455Glu mutants for the hydroxylation reaction toward 7-ethoxycoumarin in the reconstituted system were much lower than that of the wild type (less than 17%), which corresponds to lower turnover numbers for these mutants. In contrast, the catalytic efficiencies for the hydroxylation reaction toward methanol of the three mutants were more than 45% that of the wild type in spite of these mutants' lower turnover numbers. Turnover numbers and catalytic efficiencies of Arg137Leu and Lys401 Glu mutants toward both substrates were comparable to those of the wild type. The electron-transfer rate from the reductase to the heme of P450 1A2 was decreased by 30% upon addition of excess methanol, while it was not influenced by addition of excess 7-ethoxycoumarin. The turnover numbers toward both 7-ethoxycoumarin and methanol as well as the rate constant of electron transfer were decreased by 25-40% by raising the concentration of KCl from 0 to 300 mM in the reconstituted system containing 50 mM potassium phosphate buffer. The turnover numbers toward both substrates of the above-mentioned five ionic mutants caused by tert-butyl hydroperoxide in the absence of the reductase and NADPH were comparable to those of the wild type. The effect of phospholipid constituents on the catalytic activity toward 7-ethoxycoumarin of the wild type was also studied.(ABSTRACT TRUNCATED AT 250 WORDS)

Antitumor active polysaccharides from the Chinese mushroom Songshan lingzhi, the fruiting body of Ganoderma tsugae.

A systematic method of extraction, fractionation, and purification of polysaccharides from Songshan Lingzhi (Ganoderma tsugae) with antitumor activity was established. Seven glycans with strong antitumor activities were obtained from 14 water-soluble, and 15 water-insoluble fractions: FIo-a, FA-1, FII-1, FIII-2, and FIII-2-a, -b, and -c. FIo-a and FA-1 were protein-containing glucogalactans associated with mannose and fucose. FII-1 was a (1-->3)-beta-D-glucan having a lower protein content. The water-insoluble fractions FIII-2-a, -b, and -c were extracted with alkali, and were found to be protein-containing (1-->3)-beta-D-glucans showing the strongest activity. Chemical properties and structure of each antitumor polysaccharide were compared with three fungi of the Ganoderma family, Kofukitake (G. applanatum), Mannentake (G. lucidum), and Songshan Lingzhi (G. tsugae).