Isolation of a calcium-sensitive, 35,000-dalton microfilament- and liposome-binding protein from ascites tumor cell microvilli: identification as monomeric calpactin

Microvilli isolated from the MAT-C1 ascites subline of the 13762 rat mammary adenocarcinoma contain a major calcium-sensitive microfilament-binding protein, AMV-p35 (ascites microvillar p35). Association of AMV-p35 with microfilament cores during Triton X-100 extraction of the microvilli is half-maximal at 0.1-0.2 mM calcium. The protein, which comprises 6% of the total microvillar protein, can be isolated from microfilament cores prepared in the presence of calcium by extraction with EGTA and purification by ion-exchange chromatography. Alternatively, the protein can be isolated from Triton extracts of microvilli prepared in the absence of calcium by precipitation with calcium, solubilization of the precipitate with EGTA, and chromatography on an ion-exchange column. AMV-p35 binds to phosphatidylserine liposomes and F-actin with half-maximal calcium concentrations of about 10 microM and 0.2 mM, respectively. Treatment of AMV-p35 with chymotrypsin yields a 33,000-dalton fragment, behavior similar to the tyrosine kinase substrates calpactins I and II and lipocortins I and II. Immunoblot analyses using antibodies directed against calpactin I, lipocortin I, and lipocortin II showed strong reactivity of AMV-p35 with anti-calpactin I and anti-lipocortin II, but little reactivity toward anti-lipocortin I. The close relationship between AMV-p35 and calpactin I was verified by amino acid sequence analyses of peptides isolated from cyanogen bromide digests of AMV-p35. By gel filtration and velocity sedimentation analyses purified AMV-p35 is a 35,000-dalton monomer. Moreover, AMV-p35 extracted directly from microvilli in Triton/EGTA also behaves as a 35,000-dalton menomer. These findings indicate that AMV-p35 is closely related to the pp60src kinase substrate calpactin I (p36). However, AMV-p35 occurs in the microvilli as a monomer rather than as the heterotetrameric calpactin found in several other cell types.

Establishment and characterization of a continuous murine uterine cervix cancer cell line metastatic to lymph nodes and lungs

The murine uterine cervix cancer (MUCC) cell line was derived from a chemically induced Kunming mouse uterine cervix cancer (U27) and maintained in culture on solid substrates for over 100 passages. Cultures were morphotypically heterogeneous and heteroploid, with a modal number of chromosomes = 80. Each cell showed at least two abnormal chromosomes. Immunogold-silver staining was positive for keratin, vimentin, and laminin but not for desmin. The population doubling time was 27.8 h with a saturation density of 3.2 X 10(5) cells/cm2 and a peak mitotic index of about 6%. MUCC cells produced colonies on tissue culture plastic (68%) and in soft agar (8%). MUCC cells were fully malignant inasmuch as they produced in syngeneic mice invasive tumors that reproducibly were metastatic to lymph nodes and lungs. The MUCC cell line is the first mouse cervix cancer cell line useful for the study of invasion and metastasis.

[Chemoprevention of cancer of the uterine cervix--preliminary study on the intervention of the cervical precancerous lesion by retinamide RII]

Twenty seven women with mild, moderate or severe cervical dysplasia proven by pathology were treated by retinamide RII suppository. Retinamide RII suppository, 10 mg QD, was given intravaginally for six months (three months as a course). Clinical examination, Papanicolaou cytology and tissue biopsy under colposcope were carried out before and after treatment. The results indicated that after the second course, 26 out of 27 patients responded; of them, precancerous lesions disappeared in 24 and even normal squamous epithelium was observed in 3. The overall response rate was 96.29% and the marked response rate was 88.89%. The general side effects were mild. There was little cervical and vaginal irritation which was well tolerated. The results of this clinical trial make available a practical base for chemoprevention of cervical cancer.

[Establishment of a mouse forestomach carcinoma cell line (MFC) with spontaneous hematogenous metastasis and preliminary study of its biological characteristics]

A mouse forestomach carcinoma cell line (MFC) prone to blood-born metastasis to lung was established in vitro. This cell line has been subcultured for more than 132 passages. MFC cells lacked in contact inhibition and, morphologically, appeared as round, polygonal and spindle cells. Ultrastructurally, there were abundant microvilli on the cellular surface and extensive filopodia in the cytoplasm; nuclei showed irregular shape with an increased nucleus-cytoplasm ratio; desmosomes, hemidesmosomes as well as a small number of tonofibrils were observed. The doubling time of MFC cell population was 24.7 hours. The average mitotic index was 32.9% and the maximum was 62% with 70-76 mode. The homotransplant efficiency was 100% (11/11). In morphology, the solid tumors induced were similar to FC tumor, from which the MFC cell line was derived and 81.8% (9/11) developed spontaneous lung metastasis. It is indicated that this cell line still retains the primary tumor's feature of spontaneous hematogenous metastasis. MFC cell line might be very useful in experimental treatment, study of tumor metastatic mechanism and isolating subpopulation.

Phenothiazine binding by a homolog of calpactin, the pp60src tyrosine kinase substrate

Microvilli isolated from 13762 mammary ascites tumor cells contain a major calcium-sensitive protein (AMV-p35) that can be isolated with microvillar microfilament cores prepared by Triton X-100 extraction in the presence but not absence of calcium. AMV-p35 can be readily purified from ethylene glycol bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid extracts of the microfilament cores by chromatography on an anion exchange column, to which it does not bind. Immunoblot analysis indicates that AMV-p35 is related to calpactin I, the pp60src tyrosine kinase substrate. In the presence of calcium, AMV-p35 binds approximately 4 mol of chlorpromazine per mole of protein in a binding process showing apparent positive cooperativity, similar to calmodulin; however, in contrast to calmodulin, AMV-p35 also binds phenothiazine in the absence of calcium.

Occupational exposure to benzene in China

Of a total of 528,729 workers exposed to benzene or benzene mixtures in China, 508,818 (96.23%) were examined. Altogether 2,676 cases of benzene poisoning were found, a prevalence of 0.15%. A higher prevalence of benzene poisoning was found in the cities of Hangjou, Hefei, Nanjing, Shenyang, and Xian. The geometric mean concentration of benzene in 50,255 workplaces was 18.1 mg/m3 but 64.6% of the workplaces had less than 40 mg/m3. There was a positive correlation between the prevalence of benzene poisoning and the concentration in shoemaking factories. The prevalence of benzene induced aplastic anaemia in shoemakers was about 5.8 times that occurring in the general population. The results of this investigation show the need for a practicable hygiene standard to prevent benzene poisoning.

The rise of technology in Chinese hospitals

Chinese hospitals in the 1980s are in the midst of a technological revolution. Based upon data from several regions in China, this paper describes the political, organizational, economic, and philosophical changes which have accompanied the shift in focus from primary care medicine to high technology tertiary care. The increased authority of physicians, greater contact with the West, and increased funding for medical equipment are key factors in these changes. Although the Chinese state continues to control the administration and financing of most hospitals, the decentralizing reforms of Deng Xiaoping have undermined its ability to effectively plan for, and assess new technology. At present, limited resources prevent most regions from excessive technology acquisition, but the state must rebuild its planning capacity in order to foster rational allocation of scarce medical resources.

[Establishment and biologic properties of a mouse uterine cervix cancer cell line (MUCC) with lymphatic and hematogenous metastatic capacities]

For study of tumor metastatic mechanism, a mouse uterine cervix cancer cell line (MUCC), as derived from a transplantable mouse uterine cervix cancer No. 27 (U 27) with metastatic capacities through lymphatics and blood, was established in vitro. It has been successfully maintained for more than 24 months through more than 100 passages. MUCC cells are epithelioid with definite malignant morphological features. The doubling time of the cell population is 27.8 hours. The average mitotic index is 30.6%, with a maximum of 58.9%. Chromosomes show aberration in number and structure. The homotransplant rate is 75% (9/12). The solid tumor, produced by homotransplant, is similar to the tumor U 27. Metastases are present in the lymph nodes and lungs in these 9 animal models. It is evident that this cell line retains the capacity of inducing daughter tumor lines with spontaneous lymphatic and blood metastases. MUCC cell line might be very useful in isolating subpopulations which possess the different metastatic abilities and the study of metastatic mechanism.

Inactivation of pulmonary NAD+-dependent 15-hydroxyprostaglandin dehydrogenase by acrolein

Acrolein, a highly reactive aldehyde found in cigarette smoke, was shown to induce time-dependent inactivation of NAD+-linked 15-hydroxyprostaglandin dehydrogenase from porcine lung. The inactivation process followed pseudo-first-order kinetics and was irreversible. Inactivation by acrolein can be prevented by prior incubation of the enzyme with GSH but not by subsequent addition of GSH during assay. Inactivation can be also protected fully by prior incubation of the enzyme with NAD+, but only partially with prostaglandin E1. The results suggest that acrolein alkylates the enzyme at the coenzyme binding site and inactivates the enzyme. Inactivation of pulmonary NAD+-linked 15-hydroxyprostaglandin dehydrogenase by acrolein may alter cellular and circulating thromboxane/prostacyclin ratios and subsequently disturb vascular homeostasis and augment inflammatory and anaphylactic responses in smokers.

Establishment of a model of transplantable myelocytic leukemia (L801) in LACA mice

A transplantable myelocytic leukemia model of LACA mice, designated by the name of L801, was established by intravenous injection of spleen cell suspension from mice with radiation-induced myelocytic leukemia into mice of the same strain. Until now, for more than three years, the L801 has maintained stable and rapid growth and has been reproduced for over 130 serial passages. The incidence of leukemia in inoculated animals was approximately 100% and mean survival time was 10.9 +/- 2.1 days. The L801 is of myelocytic type which has been determined by cytological, cytochemical, pathological and ultrastructural observations. Its karyotype was hypodiploid, characterized by modal number of 39, loss of Y chromosome and an abnormal huge marker chromosome. The cell cycle duration of the L801 was 16 h. C-type viral particles were observed under the electron-microscope. The L801 was sensitive, to varying extents, to various anti-tumor agents. We presume that the L801 is a useful tool in studies on mechanism of leukemogenesis, anti-tumor agent screening and treatment of experimental tumors.

Ethylene-promoted malonylation of 1-aminocyclopropane-1-carboxylic acid participates in autoinhibition of ethylene synthesis in grapefruit flavedo discs

The increase in ethylene formation and in 1-aminocyclopropane-1-carboxylic acid (ACC) content in flavedo tissue of grapefruit (Citrus paradisi Macfad. cv. Ruby Red) in response to excision was markedly inhibited by exogenous ethylene. Ethylene treatment inhibited the synthesis of ACC, but increased the tissue's capability to malonylate ACC to N-malonyl-ACC, resulting in further reduction in the endogenous ACC content. The development of extractable ACC-malonyl-transferase activity in the tissue was markedly promoted by treatment with exogenous ethylene. These results indicate that the autoinhibition of ethylene production in this tissue results not only from suppression of ACC synthesis, but also from promotion of ACC malonylation; both processes reduce the availability of ACC for ethylene synthesis.

12-L-hydroxy-5,8,10-heptadecatrienoic acid (HHT) is an excellent substrate for NAD+-dependent 15-hydroxyprostaglandin dehydrogenase

12-L-hydroxy-5,8,10-heptadecatrienoic acid (HHT) was found to be an excellent substrate for NAD+ dependent 15-hydroxyprostaglandin dehydrogenase from porcine kidney. Kcat/Km value of HHT was comparable to that of prostaglandin E although HHT is not a prostanoic acid derivative. Product of enzyme catalyzed oxidation of HHT was identified as 12-keto-5,8,10-heptadecatrienoic acid by gas chromatography-mass spectrometry. The fact that HHT is an excellent substrate for 15-hydroxyprostaglandin dehydrogenase suggest that HHT may have profound unrecognized biological actions and its inactivation may be via oxidation of the hydroxyl group.

Ethylene Promotes the Capability To Malonylate 1-Aminocyclopropane-1-carboxylic Acid and d-Amino Acids in Preclimacteric Tomato Fruits

When whole unripe green tomato fruits (Lycopersicon esculentum Mill, cv T(3)) were treated with ethylene (10 microliters per liter) for 18 hours, the fruit's ability to convert 1-aminocyclopropane-1-carboxylic acid (ACC) to N-malonyl-ACC (MACC) increased markedly and such an effect was also observed in fruits of mutant nor, which cannot ripen normally. The promotion of the capability to malonylate ACC by ethylene increased with the increasing ethylene concentration from 0.1 to 100 microliters per liter and with increasing duration of ethylene treatment up to 8 hours; a longer duration of ethylene treatment did not further increase the malonylation capability. When ethylene was withdrawn, the promotion disappeared within 72 hours. Norbornadiene, a competitive inhibitor of ethylene action, effectively eliminated the promotive effect of ethylene. Ethylene treatment also promoted the fruits' capability to conjugate d-amino acids and alpha-amino-isobutyric acid. Since the increase in the tissue's capability to malonylate ACC was accompanied by an increase in the extractable activity of ACC and d-amino acid malonyltransferase, ethylene is thought to promote the development of ACC/d-amino acid malonyltransferase in unripe tomato fruits.

Promotion by Ethylene of the Capability to Convert 1-Aminocyclopropane-1-carboxylic Acid to Ethylene in Preclimacteric Tomato and Cantaloupe Fruits

The intact fruits of preclimacteric tomato (Lycopersicon esculentum Mill) or cantaloupe (Cucumis melo L.) produced very little ethylene and had low capability of converting 1-aminocyclopropane-1-carboxylic acid (ACC) to ethylene. When these unripe tomato or cantaloupe fruits were treated with ethylene for 16 hours there was no increase in ACC content or in ethylene production rate, but the tissue's capability to convert ACC to ethylene increased markedly. Such an effect was also observed in fruits of tomato mutants rin and nor, which do not undergo ripening and the climacteric increase in ethylene production during the senescence. The development of this ethylene-forming capability induced by ethylene increased with increasing ethylene concentration (from 0.1 to 100 microliters per liter) and duration (1 to 24 hours); when ethylene was removed this capability remained high for sometime (more than 24 hours). Norbornadiene, a competitive inhibitor of ethylene action, effectively eliminated the promotive effect of ethylene in tomato fruit. These data indicate that the development of the capability to convert ACC to ethylene in preclimacteric tomato and cantaloupe fruits are sensitive to ethylene treatment and that when these fruits are exposed to exogenous ethylene, the increase in ethylene-forming enzyme precedes the increase in ACC synthase.

Functional analysis of macrophage hybridomas. I. Production and initial characterization

A series of macrophage hybridomas were generated by fusion of splenic adherent cells with P388D1 tumor cells. Forty-two cell lines were established, and each was cloned by limiting dilution. Six clones that exemplified the spectrum of macrophage heterogeneity were selected for further analysis. Qualitative and quantitative differences in phenotype and functional activity were noted. Some clones constitutively expressed Ia antigens, whereas others only expressed detectable levels of Ia after lymphokine activation. The level of antigen-presenting activity generally correlated with the level of Ia expression. Furthermore, interclonal differences were noted in the levels of receptor-mediated phagocytosis and IL 1 secretion. Generally, the hybridoma clones maintained stable phenotypic and functional properties during approximately 1 yr of continuous in vitro culture. These cloned hybridoma cell lines represent a useful resource to analyze macrophage biology and to dissect structure and function relationships.

Functional analysis of macrophage hybridomas. I. Production and initial characterization

A series of macrophage hybridomas were generated by fusion of splenic adherent cells with P388D1 tumor cells. Forty-two cell lines were established, and each was cloned by limiting dilution. Six clones that exemplified the spectrum of macrophage heterogeneity were selected for further analysis. Qualitative and quantitative differences in phenotype and functional activity were noted. Some clones constitutively expressed Ia antigens, whereas others only expressed detectable levels of Ia after lymphokine activation. The level of antigen-presenting activity generally correlated with the level of Ia expression. Furthermore, interclonal differences were noted in the levels of receptor-mediated phagocytosis and IL 1 secretion. Generally, the hybridoma clones maintained stable phenotypic and functional properties during approximately 1 yr of continuous in vitro culture. These cloned hybridoma cell lines represent a useful resource to analyze macrophage biology and to dissect structure and function relationships.

Stereoselectivity of 1-aminocyclopropanecarboxylate malonyltransferase toward stereoisomers of 1-amino-2-ethylcyclopropanecarboxylic acid

A malonyltransferase isolated from mungbean (Vigna radiata L.) hypocotyls catalyzed the malonylation of both 1-aminocyclopropane-1-carboxylic acid (ACC) and D-amino acids. The possibility that ACC was recognized by the enzyme as a D-amino acid was investigated by examining the efficiencies of the four stereoisomers of 1-amino-2-ethylcyclopropane-1-carboxylic acid (AEC) serving as substrates of malonyltransferase and as inhibitors of ACC malonyltransferase. Although all four isomers were malonylated by the enzyme and competitively inhibited the malonylation of ACC to N-malonyl-ACC, (1R,2S)-AEC and (1R,2R)-AEC, both of which have an R-configuration as a D-amino acid, had lower Km and Ki values (0.1 to 0.2 mM) than their enantiomers, (1S,2R)-AEC (Km and Ki values were about 1 mM) and (1S,2S)-AEC (Km and Ki values were higher than 10 mM), which have an S-configuration as an L-amino acid. Similarly, (R)-isovaline (2-amino-2-methylbutanoic acid), which has an R-configuration as a D-amino acid, inhibited more effectively the enzymatic conversion of ACC to malonyl-ACC than did (S)-isovaline, which has an S-configuration as an L-amino acid. In mungbean hypocotyls (1R,2S)-AEC and (1R,2R)-AEC were also more efficiently converted into malonyl conjugates and more efficiently inhibited the conversion of radioactive ACC into malonyl-ACC than their enantiomers, although the differences in efficiency among stereoisomers were smaller in hypocotyls than in enzymatic reactions. These results suggest that ACC is recognized by the enzyme as a D-amino acid.

Metabolism of α-aminoisobutyric acid in mungbean hypocotyls in relation to metabolism of 1-aminocyclopropane-1-carboxylic acid

1-Aminocyclopropane-1-carboxylic acid (ACC) is known to be converted to ethylene and conjugated into N-malonyl-ACC in plant tissues. When α-amino[1-(14)C]isobutyric acid (AIB), a structural analog of ACC, was administered to mungbean (Vigna radiata L.) hypocotyl segments, it was metabolized to (14)CO2 and conjugated to N-malonyl-AIB (MAIB). α-Aminoisobutyric acid inhibited the conversion of ACC to ethylene and also inhibited, to a lesser extent, N-malonylation of ACC and D-amino acids. Although the malonylation of AIB was strongly inhibited by ACC as well as by D-amino acids, the metabolism of AIB to CO2 was inhibited only by ACC but not by D-amino acids. Inhibitors of ACC conversion to ethylene such as anaerobiosis, 2,4-dinitrophenol and Co(2+), similarly inhibited the conversion of AIB to CO2. These results indicate that the malonyalation of AIB to MAIB is intimately related to the malonylation of ACC and D-amino acids, whereas oxidative decarboxylation of AIB is related to the oxidative degradation of ACC to ethylene.