Replacement of lysine residue 1030 in the putative ATP-binding region of the insulin receptor abolishes insulin- and antibody-stimulated glucose uptake and receptor kinase activity

To test whether the tyrosine kinase activity of the insulin receptor is crucial for insulin action, we have constructed mutations of the human insulin receptor at Lys-1030, which is in the presumed ATP-binding region. By using oligonucleotide-directed mutagenesis, this lysine residue was replaced with either methionine, arginine, or alanine. Chinese hamster ovary cells were transfected by mutant cDNAs and the expressed insulin receptors were characterized. We show here that none of these mutants exhibited insulin-activated autophosphorylation and kinase activity in vitro. They also do not mediate insulin- and antibody-stimulated uptake of 2-deoxyglucose. The tyrosine kinase activity is thus required for a key physiological response of insulin.

[A surgical case of submucosal esophageal carcinoma with esophageal leiomyoma misdiagnosed as esophageal]

A 56-year-old man with submucosal esophageal carcinoma combined with esophageal leiomyoma is presented. He had suffered from progressive dysphagia and vomiting. X-ray and endoscopic examination revealed severe stenosis of the lower esophagus with smooth mucosa, and CT scan demonstrated a circular and localized tumor. The histological diagnosis of esophageal leiomyoma was made by means of surgical biopsy. Resection of the lower esophagus and upper stomach was performed. But the postoperative pathological examination revealed submucosal esophageal squamous cell carcinoma combined with esophageal leiomyoma. The etiology and diagnosis in this case were discussed.

A sensitive and specific assay for dipeptidyl-aminopeptidase II in serum and tissues by liquid chromatography-fluorometry

A highly sensitive and specific method for the assay of dipeptidyl-aminopeptidase II (DAP II) in crude enzyme preparations such as serum and tissue homogenates has been established by using a newly synthesized fluorogenic substrate, 7-Lys-Ala-4-methylcoumarinamide. The enzymatically formed 7-amino-4-methylcoumarin was determined by high-performance liquid chromatography with fluorescence detection. The activities of other aminopeptidases in human serum and rat brain homogenates were completely inhibited by o-phenanthroline without any effect on DAP II activity to permit specific determination of DAP II. The limit of sensitivity for DAP II activity was about 300 fmol/30 min. DAP II activity was found to be increased in sera from cancer patients, in contrast to the decrease in serum DAP IV activity. DAP II activity was found to be unequally distributed in rat brain regions, and the highest activity was found in the hypothalamus.

Selenium in the blood of Japanese and American women with and without breast cancer and fibrocystic disease

Selenium concentrations in whole blood of Japanese and American women with and without breast cancer and benign fibrocystic breast disease were determined. The observed blood Se levels of healthy Japanese women (0.286 +/- 0.021 micrograms/ml) were similar to previously reported values for healthy Japanese adults. The Japanese patients with benign breast disease and with breast cancer exhibited blood selenium concentrations of 0.200 +/- 0.045 and 0.195 +/- 0.057 micrograms/ml, respectively. The mean blood Se concentration of Japanese breast cancer patients with recurrence was 0.188 +/- 0.061 micrograms/ml. The mean blood Se concentrations of healthy American women from San Diego, Calif., were 0.191 +/- 0.023 micrograms/ml; of women with benign fibrocystic disease, 0.142 +/- 0.010 micrograms/ml; and of breast cancer patients, 0.167 +/- 0.032 micrograms/ml. The higher blood Se concentrations of Japanese healthy subjects as compared to healthy Americans can be attributed to differences in the dietary Se intakes; low blood Se concentration may be indicative of increased breast cancer risk.

[Detection and follow-up of the high risk group for hepatocellular carcinoma]

To determine the high risk group for hepatocellular carcinoma (H.C.C.) 79 patients with diagnosed H.C.C. were studied retrospectively and compared with 15,948 healthy subjects regarding their prior history of liver disease, positivity of HBV related factors and s-GOT. A strong association of HBsAg and H.C.C. was demonstrated and the following factors were found in the high risk group: (1) prior history of liver disease, (2) positive HBsAg, (3) prior history of blood transfusion, and (4) males between 45 and 65 years. For follow-up of the high risk group for H.C.C., the use of a "liver-note book" for individuals in this group is proposed.

Elevated activity of beta-hexosaminidase and sulfhydryl modification in the B-variant of human lung cancer

Activities of beta-hexosaminidase A and beta-hexosaminidase B (Hex B) were measured both in human lung carcinoma and the adjacent normal tissues of 47 patients. The specific activity of total beta-hexosaminidase in the tumors was considerably higher than in the adjacent normal tissues, irrespective of histological types. In isoelectric focusing experiments, Hex B purified from normal lung exhibited a single peak with an isoelectric point (pI) of 7.9, while Hex B purified from adenocarcinoma contained two forms with pI 7.6 and 7.9. With respect to heat stability, Hex B from the normal lung was very stable at 52 degrees, while the tumor Hex B (mixture of pI 7.6 and 7.9 forms) was unstable. After treatment of the tumor enzyme with dithiothreitol, heat stability was restored. When the tumor pI 7.6 form was treated with dithiothreitol and subjected to polyacrylamide gel electrophoresis, the enzyme converted to a pI 7.9 form similar to that of the normal lung. Determination of the sulfhydryl group of the tumor pI 7.6 form under nondenaturing conditions showed that the enzyme had some easily reducible disulfide bonds on its surface. These findings indicate that the formation of mixed disulfide bonds in the tumor Hex B increases the net negative charge and results in the appearance of a heat-labile form.

[Epidemiologic study of breast fluid in Japanese women]

Breast fluid was collected from 805 Japanese women using a negative-pressure breast-pump procedure. All subjects were non-lactating; there were 275 breast cancer patients and 530 healthy women. Women who secreted 20 microliters or more were classified as "secretors" (290/805, 36%); those who secreted less than 20 microliters to as "non-secretors". Breast cancer patients showed a significantly higher incidence of secretion, particularly in the diseased breast, than healthy women. Among secretors, the risk for breast cancer was high in those with earlier menarche, unmarried women, those with a smaller number of pregnancies and children and those with older age at their first delivery.

Elevation of glycoprotein galactosyltransferase activity in human lung cancer related to histological types

Uridine diphosphogalactose:glycoprotein galactosyltransferases were examined in human lung adenocarcinoma and squamous cell carcinoma. The galactosyltransferase activities in tissue homogenates from both carcinomas were higher than in adjacent normal control with asialoagalactofetuin as a substrate. This activity in adenocarcinoma (27 cases) was two times higher than that in squamous cell carcinoma (19 cases) with statistical significance (p less than 0.001). Using Triton-solubilized enzymes from a particulate fraction, similar differences in the activity were observed with ovalbumin, asialoagalactofetuin, and its beta-eliminated derivative as acceptors but not with bovine submaxillary mucin. These observations mean that the higher activity of galactosyltransferase(s) in lung carcinomas (especially in adenocarcinoma) is mainly responsible for galactosylation of carbohydrate chains in N-glycoside-type but not O-glycoside-type glycoproteins.

Elevated activities and properties of arylsulfatases A and B and B-variant in human lung tumors

The activities of arylsulfatases A and B were determined in human primary and secondary tumor tissues (total, 53 cases) of various histological types. Significantly higher activities of these sulfatases were found in almost all the primary lung carcinomas as compared to their corresponding uninvolved tissues. No significant correlation was demonstrated between the enzyme activities and histological figures (stroma amounts, etc.). Lung adenocarcinoma and squamous cell carcinoma showed the presence of an additional arylsulfatase component (B1) which was not detected in normal human lung. The tumor arylsulfatase B1 had an isoelectric point (pI) of 6.7 and was clearly distinguished from arylsulfatase A (pI 4.9) and arylsulfatase B (pI 9.1 to 9.2) in normal lung and lung tumor. The tumor B1 enzyme was demonstrated to be most probably an isoenzyme of arylsulfatase B, since this unusual enzyme was indistinguishable from arylsulfatase B in terms of Ag+ inhibition; its kinetic parameters of Km for p-nitrocatechol sulfate, which was 2.9 mM with B1; optimum pH of 6.3 for B1; heat stability; and substrate specificity for three synthetic and two physiological substrates.

Determination of double bond positions of unsaturated fatty acids by a chemical ionization mass spectrometry computer system

After stereospecific oxidation, trimethylsilylated methyl esters of mono- and diunsaturated fatty acids were analyzed by combined gas-liquid chromatography-chemical ionization mass spectrometry. The positions of original double bonds were deduced from the fragment ions produced by the cleavage of the carbon-carbon bond between two trimethylsilyl ethers. These fragment ions were recorded at m/e 187 and 259 in the case of 16:1(n-7), at m/e 187 and 287 in the case of 18:1(n-7), at m/e 215 and 259 in the case of 18:1(n-9), and at m/e 172 and 259 in the case of 18:2(n-6), respectively. The diastereoisomers of monounsaturated fatty acids can be discriminated by comparing the intensities of the fragment ions at m/e 253 and 285 in the case of 16:1 and at m/e 281 and 313 in the case of 18:1. The diastereosiomers of diunsaturated fatty acids may also be distinguished from each other by comparing the intensities of the fragment ions formed by the loss of trimethylsilyl function from the characteristic ions. Mono- and diunsaturated fatty acids in liver may be dominantly in cis- 18:1(n-1) and cis-cis-18:2(n-6) as determined by a mass chromatographic technique.

Eicosatrienoic acid omega9 in human hepatoma transplanted into athymic nude mice

Fatty acid compositions of human hepatoma transplanted successively into athymic nude mice were analysed. Eicosatrienoic acid omega9, which occurred as an unusual positional isomer of eicosatrienoic acid in the original hepatoma tissues, was preserved in these hepatoma tissues over three transplant generations, while the content of linoleic acid in liver was higher in nude mice than in humans. It appears, therefore, that the synthesis of eicosatrienoic acid omega9 is one of the essential metabolic aberrations of human hepatoma, quite independent of nutritional condition.

Chemical ionization mass spectrometry of polyunsaturated fatty acids of human serum

Polyunsaturated fatty acids of human serum were analysed by combination gas-liquid chromatography and chemical ionization mass spectrometry, using isobutane as the reagent gas. The method described yielded the molecular ion of long chain unsaturated fatty acids as the base peak; these were weak or unobservable in the corresponding electron impact mass spectra. In the chemical ionization mass spectrometry, the derivatization with trimethylsilyl ether was demonstrated to be useful for the location of the double bonds of unsaturated fatty acids. Applied toteh serum polyunsaturated fatty acids, these methods have given identification of C18:4, C20:4, C20:5, C22:4, C22:5omega-6, C22:5omega-3, and C22:6.