Partial purification and characterization of a Ca(2+)-dependent protein kinase from pea nuclei

Almost all the Ca(2+)-dependent protein kinase activity in nuclei purified from etiolated pea (Pisum sativum, L.) plumules is present in a single enzyme that can be extracted from chromatin by 0.3 molar NaCl. This protein kinase can be further purified 80,000-fold by salt fractionation and high performance liquid chromatography, after which it has a high specific activity of about 100 picomoles per minute per microgram in the presence of Ca2+ and reaches half-maximal activation at about 3 x 10(-7) molar free Ca2+, without calmodulin. It is a monomer with a molecular weight near 90,000. It can efficiently use histone III-S, ribosomal S6 protein, and casein as artificial substrates, but it phosphorylates phosvitin only weakly. Its Ca(2+)-dependent kinase activity is half-maximally inhibited by 0.1 millimolar chlorpromazine, by 35 nanomolar K-252a and by 7 nanomolar staurosporine. It is insensitive to sphingosine, an inhibitor of protein kinase C, and to basic polypeptides that block other Ca(2+)-dependent protein kinases. It is not stimulated by exogenous phospholipids or fatty acids. In intact isolated pea nuclei it preferentially phosphorylates several chromatin-associated proteins, with the most phosphorylated protein band being near the same molecular weight (43,000) as a nuclear protein substrate whose phosphorylation has been reported to be stimulated by phytochrome in a calcium-dependent fashion.

[Determination of coumarins in radix Angelicae Dahuricae before and after processing]

This paper reports the contents of coumarins in Radix Angelicae Dahuricae before and after processing. By CS-930 TLC scanner, the total contents have been determined to be 0.190%, 0.571%, 0.178% and 0.421% respectively.

Low frequency of ras activation in 2-acetylaminofluorene- and 3'-methyl-4-(dimethylamino)azobenzene-induced rat hepatocellular carcinomas

Activation of ras protooncogenes in 11 2-acetylaminofluorene (AAF)-induced hepatocellular carcinomas (HCCs) or liver cell lines and 9 3'-methyl-(dimethylamino)azobenzene (3'-Me-DAB)-induced HCCs in rats was examined using the NIH3T3 cell transfection assay and oligonucleotide hybridization analysis. Only one cell line established from a AAF-treated rat liver demonstrated transforming activity with a point mutation and ATTA transversion at the second position of H-ras codon 61. The rates of ras activation were thus very low for both AAF- and 3'-Me-DAB-induced rat HCCs, the results thus extending and confirming the findings indicating that ras activation in rat HCCs induced by various type of carcinogens is infrequent.

In vitro progression-associated c-H-ras activation in neoplastic hepatocyte lines established from SV40-T antigen gene-harboring transgenic mice

In order to investigate the molecular mechanisms of multistep hepatocarcinogenesis in SV40-T antigen gene-harboring transgenic mice, 9 hepatocellular carcinoma (HCC) lines and 10 "preneoplastic" hepatocyte lines were established from the animals and their biological and molecular changes during culture were investigated. Three of the 9 HCC lines showed progression during culture in terms of growth rate and growth capability in soft agar and in nude mice. This progression was associated with the appearance of activated c-H-ras oncogene. Including these 3 lines, H-ras activation was observed in a total of 7 of the 9 HCC lines (78%), whereas it was found only in 1 of 10 (10%) "preneoplastic" hepatocyte lines. These data thus indicate that H-ras activation may be an event occurring at a relatively late stage of hepatocarcinogenesis in this transgenic mouse system and that it may serve towards completion of the carcinogenic process together with the T-antigen.

Absence of inhibition by lipoprotein (a) inhibition of tPA induced thrombolysis in a patient's plasma milieu

The increase in Lp(a) is strongly correlated with premature coronary artery disease. The Apo(a) has striking homology to plasminogen. It was found in an in vitro purified system that Lp(a) competes with both plasminogen and tissue-type plasminogen activator (tPA) for fibrin binding sites, thus resulting in a decrease in fibrin-dependent plasminogen activation. In this study, plasma fibrinolysis was studied in a young patient who had a consistently high level of Lp(a) (198 mg/dl) and had suffered from cerebral thrombophlebitis 12 months previously. The patient had normal levels of plasma plasminogen and fibrinogen. The euglobulin lysis time before and after venous occlusion was not prolonged, and after the addition of tPA to the patient's plasma or whole blood, the clot lysis time was normal. The same result was obtained when the patient's plasma was depleted of Lp(a) before clotting. When the patient's plasma serpins were inhibited, plasminogen activation by tPA in the presence of several fibrin concentrations was normal, suggesting that the formation of the ternary complex tPA - plasminogen - fibrin was not inhibited by the presence of high levels of Lp(a). It is concluded that a consistently high level of Lp(a) in this patient did not inhibit tPA-dependent fibrinolysis, and the thrombotic episode was not therefore related to deficient thrombolysis.

The propeptide of beta-glucuronidase. Further evidence of its involvement in compartmentalization of beta-glucuronidase and sequence similarity with portions of the reactive site region of the serpin superfamily

A significant portion of murine hepatocyte beta-glucuronidase is maintained within the endoplasmic reticulum (ER) by complex formation with the esterase active site of the protein egasyn. The carboxyl-terminal propeptide of the precursor form of glucuronidase appears important in localization of glucuronidase to the ER since a naturally occurring mutation in it is associated with decreased levels of ER glucuronidase. A sequence similarity was noted between the carboxyl-terminal propeptide and portions of the conserved sequences of the reactive site region of members of the serpin (serine proteinase inhibitor) superfamily. Also, previous studies had shown that a synthetic peptide, corresponding to the propeptide region, was a specific and potent inhibitor of the esterase activity of purified egasyn. Taken together, these results suggest that (a) the egasyn-glucuronidase system may use a novel mechanism related to that of serine proteinases and their inhibitors in complex formation and in subsequent localization of glucuronidase within the ER and that (b) a possible function of ER glucuronidase is to modulate the esterase activity of egasyn.

Detection of activated c-H-ras oncogene in hepatocellular carcinomas developing in transgenic mice harboring albumin promoter-regulated simian virus 40 gene

Hepatocellular carcinomas (HCCs) developing in transgenic mice harboring an albumin promoter-regulated simian virus 40 (SV40) tumor antigen gene were analyzed for activating point mutations of the c-H-ras oncogene. Oligonucleotide hybridization studies utilizing enzymatically amplified DNA sequences of paraffin-embedded tumor tissues revealed that 10 out of 25 HCCs contained either an A-to-T or an A-to-G conversion at the second position of codon 61. Northern blot studies confirmed expression of SV40 gene mRNAs in the tumor tissues of both mutation-positive and mutation-negative HCCs. These findings in association with earlier results thus strongly suggest that mutational activation of cellular oncogene may play an important role in SV40-initiated multistage hepatocarcinogenesis in vivo.

Direct electrophoretic detection of the allelic state of single DNA molecules in human sperm by using the polymerase chain reaction

We have developed a procedure that allows the detection of polymerase chain reaction (PCR) products derived from a single target DNA molecule in a human sperm without using radioactive probes. With this method, three genetic loci present in a single sperm can be amplified simultaneously. The amplification procedure is specific as well as efficient and permits detection of the PCR product by ethidium bromide staining after polyacrylamide gel electrophoresis. When allele-specific PCR primers that differ in length are used, the size of the PCR products of different alleles also vary in length, allowing the allelic state at each locus to be determined electrophoretically. Studies on individual sperm by using this procedure should facilitate the measurement of genetic recombination in humans over small physical distances. The ability to directly analyze the allelic state of PCR products from one cell rapidly and simply will also be useful for the prenatal diagnosis of genetic disease, especially in the analysis of single blastomeres taken from in vitro fertilized eggs prior to implantation.

Biological characterization of major polypeptides on the surface of spotted fever group rickettsiae

There are two major polypeptides on the surface of spotted fever group rickettsiae that play important roles as immunogens and possibly relate to the pathogenicity of rickettsial diseases. Digestion with trypsin and staphylococcal V-8 protease shows that the 115-kDa protein of Rickettsia conorii is a trypsin-sensitive, surface-exposed protein. The 135-kDa protein is relatively trypsin resistant. Both proteins resist heat treatment up to 52 degrees C and maintain their antigenic reactivity with monoclonal antibodies when the intact rickettsiae are heated. When rickettsiae are dissolved in SDS-containing sample buffer, these polypeptides lose their antigenic reactivity with monoclonal antibodies after incubation at 45 degrees C for 10 min. Staphylococcal V-8 protease does not appear to affect these polypeptides under the current experimental conditions. Monoclonal antibody to the 115-kDa protein reduces rickettsial attachment. The 115-kDa polypeptide may play a role in rickettsial adhesion to the host cell surface.

Carbohydrate binding specificities of several poly-N-acetyllactosamine-binding lectins

The structural requirements for the interaction of the Asn-linked poly-N-acetyllactosamine-type oligosaccharide moieties of glycoproteins with various N-acetylglucosamine-binding lectins were investigated by means of affinity chromatography on immobilized lectin-Sepharose columns. High molecular weight glycopeptides containing poly-N-acetyllactosamine-type oligosaccharides obtained by Pronase digestion of human erythrocyte ghosts were treated with 0.1 M trifluoroacetic acid at 100 degrees C for 40 min and then several oligosaccharide fragments were purified with an amino-bonded silica column. Among these oligosaccharide fragments, trisaccharide Gal beta 1-4GlcNAc beta 1-6Galol bound to the wheat germ agglutinin (WGA)- and pokeweed mitogen (PWM)-Sepharose columns, and also showed affinity to the Datura stramonium agglutinin (DSA)-, Lycopersicon esculentum (tomato) agglutinin- and Solanum tuberosum (potato) agglutinin-Sepharose columns. Pentasaccharide Gal beta 1-4GlcNAc beta 1-3(Gal beta 1-4GlcNAc beta 1-6)Galol showed weaker affinity to the WGA- and PWM-Sepharose columns, compared to the trisaccharide. Trisaccharide GlcNAc beta 1-3(GlcNAc beta 1-6)Galol showed weak affinity to the WGA-Sepharose column and did not show any affinity to the other lectin-Sepharose columns. Hexasaccharide Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4GlcNAcol bound only to the DSA-Sepharose column, indicating that only DSA does not require a GlcNAc beta(1-6)- linkage for interaction.

Structural requirements for the binding of oligosaccharides to immobilized lectin of Erythrina variegata (Linn) var. orientalis

The structural requirements for the interaction of asparagine-linked oligosaccharide moieties of glycoproteins with Erythrina variegata agglutinin (EVA) were investigated by means of affinity chromatography on an EVA-Sepharose column. Some of the branched poly-N-acetyllactosamine-type oligosaccharides obtained from human erythrocyte band 3 glycoprotein were found to show high affinity to EVA-Sepharose, whereas complex-type oligosaccharides were shown to have low affinity. Hybrid type, oligomannose-type and unbranched poly-N-acetyllactosamine-type oligosaccharides bound very little or not at all to EVA-Sepharose. To further study the carbohydrate-binding specificity of this lectin, we investigated the interaction of immobilized EVA and oligosaccharide fragments obtained through partial hydrolysis from branched poly-N-acetyllactosamine-type oligosaccharides. Branched poly-N-acetyllactosamine-type oligosaccharides were subjected to limited hydrolysis with 0.1% trifluoroacetic acid at 100 degrees C for 40 min and then separated on an amino-bonded silica column. One of pentasaccharides thus prepared strongly bound to the EVA-Sepharose column. Structural analysis of this pentasaccharide showed that the Gal beta 1-4GlcNAc beta 1-3(Gal beta 1-4GlcNAc beta 1-6)Gal sugar sequence, which is an I-antigen determinant, was essential for the high affinity binding of the oligosaccharides to the EVA-Sepharose column.

Kinetics and mechanism of methanol and formaldehyde interconversion and formaldehyde oxidation catalyzed by liver alcohol dehydrogenase

It has been shown that the hydrophobic interaction in the active-site plays a fundamental role in substrate binding. Proper molecular orientation is required for hydride transfer (Dalziel and Dickinson, 1967). For methanol, the binding is unfavored due to the lack of a hydrophobic chain. In the enzyme-coenzyme-substrate complex, the small methyl group of the substrate is not held in a fixed position, resulting in a low hydride transfer rate. The binding of NAD+ to the enzyme does not exhibit a significant effect on the binding of methanol, nor does methanol affect NAD+ binding. In the presence of LADH, methanol is oxidized by NAD+ to formaldehyde, while formaldehyde can be oxidized by NAD+ to formate ion or reduced by NADH to methanol. These reactions follow a rapid equilibrium random mechanism. Among these three reactions, the reduction of formaldehyde is the most rapid. The rate of formaldehyde oxidation is faster than the oxidation of methanol. Our study with these non-hydrophobic substrates provides an important bridge between the bioinorganic activation of zinc-bound water and the bioorganic oxidation of ethanol. Furthermore, it furnishes some insight into an enzymatic system that is so highly sensitive to small changes in substrate chain length that it can magnify the consequence of a modest change in substrate hydrophobicity.

Some consideration of data corrections for a SAXS system employing a linear PSPC

When a one-dimensional position-sensitive proportional counter (PSPC) is employed in a small-angle X-ray scattering (SAXS) system, detector-related problems might be encountered, such as nonuniformity of the detector, resolution function defined by the geometry of the receiving slit etc., all of which could cause distortion to the measured intensity profile. A set of experiments has been performed to test the significance of some of these problems, and corrections have been worked out to circumvent them. To obtain an optimized condition between flux and resolution, a wedge-shaped receiving slit is recommended.

Effect of ethane dimethane sulphonate on proopiomelanocortin (POMC) mRNA and POMC-derived peptides in the rat testis

Recent studies have shown that both proopiomelanocortin (POMC)-derived peptides and a range of POMC gene transcripts are present in the testis. Previous immunocytochemical studies have reported immunoreactive (ir)-beta-endorphin (EP) and ir-ACTH to be localized in the Leydig cells, and ir-NacEP in spermatogonia and primary spermatocytes. In the present study, we have further examined the hypothesis that testicular Leydig cells are the principal site of synthesis of these peptides, by determining the effects of the administration of the cytotoxic drug ethane dimethane sulphonate (EDS) which selectively destroys the Leydig cells of the testis. As expected, serum testosterone levels fell and serum FSH/LH levels increased within 3 days of EDS administration, returning to normal levels 4-8 weeks later. In contrast, the testicular content of POMC-derived peptides and POMC mRNA levels in these animals was not significantly altered throughout the experimental period. In addition, POMC mRNA was not detected in a purified Leydig cell preparation derived from adult male rats, and POMC-derived peptides were also undetectable in the media of a similar preparation following cell culture. These data suggest that in the adult the predominant site of rat POMC gene expression is in testicular interstitial cells other than Leydig cells.

[Effects of kappa-opiate receptor antagonist MR-2266-BS on ACTH and prolactin release]

The effect of intravenous injection of different doses of MR-2266-BS, a selective antagonist of kappa-opiate receptor, on plasma adrenocorticotropin (ACTH) and prolactin (PRL) in conscious male rats bearing an intrajugular cannulae was assessed. The results revealed that the MR-2266-BS of 3 mg/kg completely blocked the restraint stress-induced increase in plasma ACTH levels, and further elevated plasma PRL levels in these animals, while there were no effects on the resting levels of ACTH and PRL. MR-2266-BS of 6 mg/kg significantly increased the resting levels of plasma ACTH and also further elevated the restraint stress-induced increase of plasma ACTH and PRL. The present data suggest that kappa-opiate receptor and its endogenous ligand may be involved in the regulation of the resting and restraint stress-induced release of ACTH, and their action appears to be both stimulatory and inhibitory. Furthermore, kappa-opiate receptor and its endogenous ligand may only inhibit the stress-induced release of PRL.

Fine-structure genetic mapping of human chromosomes using the polymerase chain reaction on single sperm: experimental design considerations

The polymerase chain reaction (PCR) makes it possible to rapidly generate a very large number of copies of a specific region of DNA. Application of PCR to individual human sperm cells permits the typing of a large number of independent male meiotic events. If the donor male is heterozygous at three loci, sperm typing using PCR will permit ordering of loci in a manner analogous to classical methods of experimental genetics. Sequential analysis of trios of loci by sperm typing will provide a very accurate means of ordering any number of tightly linked loci. Here, we describe experimental design and sample-size issues raised by the application of sperm typing by PCR for mapping human chromosomes, and we demonstrate that sperm typing will be an efficient method for generating fine-structure human genetic maps.

[Cost-effectiveness analysis of two-dimensional/Doppler echocardiography, cardiac catheterization and angiography in the diagnosis of congenital heart disease]

To compare the costs and effectivenesses of 2-dimensional/Doppler echocardiography (2D/DE), cardiac catheterization (CC) and angiography (CA) in the evaluation of cardiac anatomy in patients with congenital heart disease, these three kinds of examinations were performed in 100 patients before operation. The 100 patients had 120 separate cardiovascular abnormalities, of which 100 (83.3%) were prospectively identified by 2D/DE. The sensitivity and specificity of 2D/DE were: ASD, 87.9% and 100%; VSD, 97.9% and 96.1%; PDA, 86.7% and 98.2%, Tetralogy of Fallot, 6 of 6 patients; the overall sensitivity and specificity of the less common defects, 31.6% and 95.8%. Ninety-seven (80.8%) were prospectively identified by catheterization. The sensitivity and specificity of catheterization were: ASD, 87.9% and 100.0%; VSD, 80.9% and 94.6%; PDA 93.3% and 96.6%; Tetralogy of Fallot, 6 of 6 patients, the less common defects, 52.6% and 95.5%. Forty-five (81.8%) were prospectively identified by angiography in 55 patients. The sensitivity and specificity of angiography: ASD, 5 of 7 patients, VSD, 88.0% and 94.3%; PDA, 2 of 2 patients; Tetralogy of Fallot, 5 of 5 patients; the less common defects, 68.8% and 100.0%. The economic evaluations were performed. The costs of the depreciation (including equipments and houses), hospital bed, water and electricity, management and staffs' wage were: 2D/DE, RMB 46.09 per patient; catheterization, RMB 314.17 per patient; angiography, RMB 314.17. The ratios of cost to outcome (cost per correct diagnosis) of 2D/DE, CC and CA were: 55.33, 388.82 and 384.07 respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Experimental and clinical studies of "Shen Yan Ling" in treatment of chronic glomerulonephritis

"Shen Yan Ling" (SYL) is a compound herbal preparation consisting of 16 ingredients: Herba Ecliptae, Radix Rhemanniae, Rhizoma Cibotii, Radix Angelica Sinensis, Rhizoma Ligustici Chuanxiong, Radix Paeoniae Rubra, Rhizoma Diosocoreae, Poria, Radix Sanguisorbae, Radix Rubiae, Herba Portulacae, Fructus Gardeniae, Herba Cirsii Japonici, Herba Cephalanoploris, etc. In animal experiments, SYL was shown to have therapeutic effect for Masugi's nephritis models. It has also been used with satisfactory results in the treatment of 314 cases of chronic glomerulonephritis of the common type with manifestations of Yin deficiency and endogenous heat.

Cooperative effects of colony-stimulating factor 1 and recombinant interleukin 2 on proliferation and induction of cytotoxicity of macrophage precursors generated from mouse bone marrow cell cultures

Precursor cells for NK activity, present in the light fraction of fresh mouse bone marrow, were cultivated in vitro in the presence of either CSF-1, IL-2, or a combination of both factors. In the presence of only CSF-1, strong proliferation was induced. Cells quickly passed the macrophage precursor stage and matured to typical macrophages. Neither granula formation nor NK activity were induced. Under culture conditions with only IL-2 NK activity had developed after 3 d, however, no significant proliferation occurred. In the presence of both factors strong proliferation was induced, and concomitantly, granula formation and NK activity developed. Apparently, proliferation depended on CSF-1 and granula formation, and NK cytotoxicity was induced by IL-2. When proliferating cells with strong anti-YAC-1 activity from a culture in CSF-1 plus IL-2 were further cultivated in only IL-2, the content of granula further increased, whereas proliferation gradually stopped. In contrast, when these cells from CSF-1 plus IL-2 culture were further cultivated in only CSF-1, granula disappeared and NK activity was lost, whereas sustained proliferation and differentiation to macrophages occurred. Only under culture conditions with both factors were proliferation and NK activity both maintained. More than 90% of cells from a 3-d culture in CSF-1 plus IL-2 expressed the NK 1.1. marker, whereas F4/80 was only marginally detected by FACS analysis. After two further days in culture, 70% of the cells expressed F4/80 and 60% coexpressed NK 1.1. and F4/80. By setting the size scatter in order to gate for large granular cells, a population was obtained with 100% coexpression of NK1.1. and F4/80. The data indicate that early cells of the macrophage lineage can develop into different functional and morphological directions depending on the varying influence of IL-2 and CSF-1.

Non-specific response of serum growth hormone to thyrotropin-releasing hormone in diabetics

It is well known that growth hormone (GE) secretion and regulation in diabetics are abnormal. In order to evaluate the response of GH to nonphysiological stimuli in diabetics, a thyrotropin-releasing hormone (TRH) test (500 micrograms by IV bolus injection) was carried out in 12 patients with insulin-dependent diabetes (IDD, 6 males and 6 females). 11 noninsulin-dependent diabetes (NIDD, 5 males and 6 females), and 10 normal controls (6 males and 4 females). The results showed that the basal serum GH levels in diabetics were higher than that in normal controls and it was even higher in IDD than in NIDD. Following the TRH stimulus, the mean peak level of GH in IDD was the highest among the three groups, the differences being statistically significant (F = 9.323, P less than 0.01). It was concluded that a nonspecific response to TRH of GH did occur in IDD, and the peak values were even higher in female than in male subjects. A negative correlation existed between the GH peak values and the age of the patients as well as in the controls. This supported the view that GH responsiveness to TRH has a tendency of progressive decline with age. However, no significant correlation was found between the peak value of GH and the blood glucose level or the microangiopathic complications. The mechanism of TRH stimulation on GH release in diabetics is discussed.

[Metastatic characteristics of SY86B human gastric carcinoma in athymic nude mice]

The invasive and metastatic behavior of SY86B human gastric carcinoma in nude mice were further studied. The results showed that this human cancer strain had a relatively high spontaneous metastatic rate (68.4%). The metastasis was related to the invasiveness of the transplanted tumor and tumor-bearing time. Since the metastasis developed from 2nd to 9th passages, it was considered that this model had a stable metastatic tendency. It was observed that the genetic background, age and sex difference of the recipient nude mice may not be associated with the metastasis. Aside from the high transplantable rate (100%) and spontaneous metastatic rate (68.4%), SY86B human gastric carcinoma strain still maintains the morphologic, immunologic, genetic and ultrastructural characteristics of the original tumor. All these make it a useful means in the study of diagnosis and treatment of cancer metastasis.

Protective monoclonal antibodies recognize heat-labile epitopes on surface proteins of spotted fever group rickettsiae

Thirty-eight monoclonal antibodies that have not been reported previously were developed from mice immunized with Rickettsia rickettsii, R. conorii, and R. sibirica. Western immunoblotting showed that these monoclonal antibodies are directed against heat-sensitive epitopes which are located on two major surface polypeptides with molecular sizes ranging from 115 to 150 kilodaltons. The detection of the two bands did not depend on the presence of 2-mercaptoethanol. Both bands were destroyed by treatment with proteinase K. Monoclonal antibodies examined by immunofluorescence assay reacted with epitopes that are species specific, group reactive, or shared among a smaller subset of species of spotted fever group rickettsiae. Nine of the monoclonal antibodies were evaluated for their ability to neutralize rickettsial infection and thus protect animals against disease caused by homologous species of rickettsiae. Treatment of rickettsiae with monoclonal antibodies F3-12, F3-14, and F3-36 completely protected guinea pigs against illness caused by the homologous organism R. rickettsii. Monoclonal antibodies F9-5G11 and F15-5B12, derived from mice immunized with R. sibirica, conferred partial protection by delaying the onset and shortening the duration of fever in guinea pigs inoculated with R. sibirica. Monoclonal antibodies F2-15, F2-31, F2-53, and F3-12 protected mice from a lethal infection with R. conorii. Heat-labile epitopes of spotted fever group rickettsial surface proteins are important candidate antigens for development of vaccines to confer protective immunity.

Analogs of unusual sponge phospholipids. Synthesis and thermotropic properties of 1,2-di-(6Z,9Z)-6,9-hexacosadienoyl phosphatidylcholine and phosphatidylethanolamine

The major marine sponge phospholipids 1,2-di-(5Z,9Z)-5,9-hexacosadienoyl phosphatidylcholine (PC) and phosphatidyl-ethanolamine (PE) hardly incorporate cholesterol into their liposomal bilayers, as reported earlier. Our previous studies indicated that their synthetic short chain (C18-C24) analogs with the same double bond pattern readily incorporated cholesterol, thus demonstrating the importance of the chain length. In order to investigate the possible role of the unusual delta 5,9 diunsaturation 1,2-di-(6Z,9Z)-6,9-hexacosadienoyl phosphatidylcholine and phosphatidylethanolamine were synthesized and their thermotropic behavior studied. Both analogs shows a transition endoterm at 45 degrees C, while the natural 1,2-di-(5Z,9Z)-5,9-hexacosadienoyl PC and its PE counterpart exhibited it at 42 degrees C. A partial incorporation of cholesterol into liposomal bilayers of 1,2-di-(6Z,9Z)-6,9-hexacosadienoyl PC was observed. Our results suggest that while the chain length is the predominant factor in the interactions of these phospholipids with sterols, the double bond location may also play a contributing role.

Parallel induction of fibrinolysis and receptors for plasminogen and urokinase by interferon gamma on U937 cells

A new cell sorter technique was employed to study the role of interferon gamma (INF gamma) in fibrinolysis induced by U937 monocytic cells. INF-gamma induced the differentiation of U937 cells as evidenced by the appearance of CD 14 antigen on the cell surface. Scatchard analysis and dose response curves showed a parallel increase in the number of receptors on U937 cells capable of accepting exogenous plasminogen and urokinase (UPA) synthetized by differentiating U937 monocytic cells. This would favour an activation of plasminogen by UPA. This adds a new parameter in the regulation of cell-mediated fibrinolysis and may be important in a number of biological processes.

Invasion and metastasis of SY86B human gastric carcinoma cells in nude mice

A moderately differentiated tubular adenocarcinoma of human stomach, named SY86B, was successfully transplanted subcutaneously to nude mice of different genetic backgrounds (BALB/CA/PBI-nu, C57BL/6J.615/PBI-nu and ICR.BALB/CA/PBI-nu). The tumor has been passaged for 13 generations and the transplantability was 100%. The SY86B cells retained the capacity of invasive and metastatic growth in the nude mice and showed a high rate of metastasis to the regional lymph nodes and to such distant organs as the lungs, liver and pancreas. The overall rate of metastasis was 77.7%. The species of the nude mice, their age and sex apparently did not significantly affect the occurrence of metastasis. Tumor-bearing time and the aggressive character of the tumor cells themselves appeared important for the genesis of metastasis. This experimental model can provide a new approach to basic and clinical studies of cancer metastasis.