High-resolution reversed-phase high-performance liquid chromatography analysis of polyamines and their monoacetyl conjugates by fluorescence detection after derivatization with N-hydroxysuccinimidyl 6-quinolinyl carbamate

A highly sensitive, accurate, and reproducible HPLC method for the determination of all natural polyamines and their monoacetyl conjugates is described. The presented method is based on precolumn derivatization with N-hydroxysuccinimidyl 6-quinolinyl carbamate (HSQC) followed by C18-HPLC separation using a ternary gradient and fluorescence detection (lambda Ex = 248 nm, lambda Em = 398 nm). The derivatives of the four main polyamines (putrescine, cadaverine, spermidine, and spermine) and the internal standard were synthesized on a preparative scale and characterized, especially with respect to their molar absorptivities and fluorescence quantum yields. The limits of detection of the highly stable derivatives ranged from 30 to 130 fmol (injection volume 10 microliters) for putrescine and N-acetylcadaverine, respectively (signal to noise ratio = 10), with excellent linearity within the range from 1 to 100 microM. High reproducibility for both retention times and peak areas, with coefficients of variation ranging from 0.14 to 0.88% and from 1.83 to 3.80%, respectively, were achieved. Provided that deproteinization of the samples was carried out immediately, recoveries of the analytes from homogenates of pancreatic cancer xenografts were high and reproducible. The optimized method was applied to the determination of the polyamine content of cultured pancreatic cancer cells and of tissue from colorectal adenocarcinoma, proving precise and reproducible quantification in these complex biological matrices.

The promoters for human and monkey poliovirus receptors. Requirements for basic and cell type-specific activity

The cellular receptors for poliovirus (PVR) are glycoproteins belonging to the immunoglobulin superfamily. Functional receptors for poliovirus are only expressed by primates; known rodent homologues lack the ability to bind virus due to amino acid differences. Human poliovirus infections are targeted to the gastrointestinal tract and, rarely, to motor neurons in the central nervous system. Available evidence suggests that poliovirus uses only one cellular receptor, implying that the tissue tropism of poliovirus is likely to be related to the expression of the human PVR (hPVR). However, low levels of expression of hPVR-specific mRNAs can be detected in many human tissues other than the apparent target cells. The nonpathogenic function of hPVR is unknown. For a study of the transcriptional control of hPVR expression, we have isolated and characterized the promoter of the hPVR gene. Deletion analysis defined an approximately 280 base pair minimal promoter fragment that: 1) lacks TATA- and CAAT-like elements, 2) is distinguished by a high GC content, and 3) promotes transcription at multiple start sites. The pattern of activity caused by transfection of serial 5'- and 3'-promoter deletions is almost identical in HEp2, HeLa, COS-1, and mouse L929 cells, indicating a similar transcriptional regulation of the hPVR promoter in these cell lines. However, on transfection of Raji cells, a Burkitt's lymphoma cell line harboring a transcriptionally inactive hPVR gene, all promoter reporter constructs tested exerted only residual activity. These results suggest that the cis-element(s) governing cell type-specific hPVR expression resides in the minimal promoter region. We also report the sequences of the promoters of two monkey homologues to hPVR (AGMalpha1 and AGMalpha2). Transcripts encoding the monkey poliovirus receptors originate from a region analogous to that identified for hPVR transcripts.

Hyaluronidase pretreatment produces selective melphalan enrichment in malignant melanoma implanted in nude mice

Preclinical and clinical observations suggest that the administration of hyaluronidase (Hyase) shortly before that of chemotherapy increases the access and, thus, the effectiveness of anticancer drugs in tumors. To examine this hypotheses as well as the selectivity of such a therapeutic approach potentially beneficial in isolated limb perfusion, the Hyase-induced distribution of melphalan was measured in tumor-bearing nude mice with respect to the mode of drug administration using RP-18 ion-pair high-performance liquid chromatography (HPLC) with fluorimetric detection. Melphalan alone (50 micromol/kg) or a combination of melphalan (50 micro mol/kg) and Hyase (100,000 IU/kg) was injected either i.p. or s.c. in the vicinity of the tumors. The s.c. melphalan injection caused a 4-fold rise in melphalan concentration (59 microM) in the tumors as compared with i.p. application (15 microM). Only minor effects were observed with respect to the route of melphalan application on its distribution in other tissues (ca. 13 microM in plasma, 15 microM in muscle, 30 microM in the liver, 26 microM in the kidney, and 21 microM in the testicle). Irrespective of the route of Hyase coadministration, the enzyme increased the concentration of i.p. injected melphalan in all tissues to ca. 20 microM in the tumor, 15 microM in plasma, 27 microM in muscle, 40 microM in the liver, 29 microM in the kidney, and 28 microM in the testicle. In contrast, s.c. injected melphalan was selectively accumulated by the tumors after both s.c. and i.p. Hyase administration (462 and 388 microM, respectively). Melphalan enrichment in the tumors was higher (16- to 32-fold higher than in the other tissues) after i.p. administration of Hyase since, in contrast to s.c. injection of the enzyme, its i.p. administration caused a decrease in the concentration of the cytostatic in all other tissues as compared with the s.c. administration of melphalan alone.

Discrepancy between cytotoxicity, platinum accumulation, and DNA platination in MCF-7 breast cancer cells treated with diaqua (1,2-diphenylethylenediamine) platinum (II) sulfates and cisplatin

Cisplatin (cis), raceme-diaqua[1,2-bis(4-fluorophenyl)ethylenediamine] platinum(II) sulfate (r-4F-PtSO4), meso-diaqua[1,2-bis(4-fluorophenyl)ethylenediamine]platinum(II) sulfate (m-4F-PtSO4), and meso-diaqua[1,2-bis(2,6-dichloro-4-hydroxyphenyl)ethylenediamine] platinum(II) sulfate (m-2,6Cl2-4OH-PtSO4) were compared with regard to their growth inhibitory effect on MCF-7 breast cancer cells. At concentrations of 5 microM, cis, r-4F-PtSO4, and m-4F-PtSO4 were essentially equiactive, whereas m-2,6Cl2-4OH-PtSO4 was ineffective. Platinum measurements by neutron activation analysis showed that a 24-h treatment of the MCF-7 cells with r-4F-PtSO4 and m-4F-PtSO4 caused a 22.3- and 10.3-fold accumulation, respectively, whereas the accumulation factors for cis (2.55) and m-2,6Cl2-4OH-PtSO4 (1.83) were very low. The comparison of DNA-associated platinum revealed a similar tendency. After 24 h of drug exposure, the base pair/ platinum ratios were: 2.1.10(4) for r-4F-PtSO4, 3.7.10(4) for m-4F-PtSO4, 6.1.10(4) for cisplatin, and 8.1. 10(4) for m-2,6Cl2-4OH-PtSO4. Thus, the grade of cytotoxicity was correlated neither with the extent of cellular platinum enrichment nor with the degree of genomic DNA platination.

Canyon rim residues, including antigenic determinants, modulate serotype-specific binding of polioviruses to mutants of the poliovirus receptor

Several mouse cell lines expressing hybrid human poliovirus receptors (hPVRs) bearing mutations in the first immunoglobulin-like domain were previously characterized for their defective binding and replication of poliovirus type 1 Mahoney (G. Bernhardt, J. Harber, A. Zibert, M. DeCrombrugghe, and E. Wimmer, Virology, 203, 344-356, 1994). Here we report that these mutant hPVRs were utilized to explore differences in the binding behavior of the three serotypes of poliovirus. Type 3 polioviruses (both Sabin and the neurovirulent Leon strain) clearly bound to the hPVR mutant Q130G/GD, but were incapable of initiating infection. Also, binding at 25 degrees of poliovirus types 2 and 3 to cell lines expressing the hPVR mutants P84SYS/HPGA, L99GAE/AAAA, and D117F was greater than type 1 poliovirus. Further study of the serotype-specific interaction with mutant hPVRs was accomplished with antigenic hybrid viruses. Improved binding by antigenic hybrid viruses demonstrated that serotype-specific binding to mutant hPVRs is, in part, determined by the amino acid sequence of neutralization antigenic sites (NAgs) and the probable conformational rearrangement of amino acids adjacent to the NAg sites. Finally, site-directed mutants of poliovirus were utilized to determine the relative contributions, to hPVR interactions, of individual amino acids with solvent accessible side chains in the viral canyon. Of the 18 viable virus mutants produced, 3 (D1226A, I1089A, and VPEK1166HPGA) expressed impaired replication phenotypes on the mutant hPVR cell lines P84SYS/HYSA and D117F. A location at the rim of the poliovirus canyon was implicated for the interaction of the amino terminal domain of the poliovirus receptor with conserved and serotype-specific viral surface amino acids. The possible involvement of elements of neutralization antigenic sites in receptor binding may explain, in part, why poliovirus exists in only three serotypes.

Development of a parenterally administrable hydrosol preparation of the "third generation platinum complex" [(+/-)-1,2-bis(4-fluorophenyl)ethylenediamine]dichloroplatinum(II). Part 1. Preparation and studies on the stability and antitumor activity

The development of a galenical formulation for poorly water soluble dichloroplatinum(II) complexes suitable for the parenteral administration in cancer chemotherapy is described. The procedure, which we elaborated for [(+/-)-1,2-bis(4-fluorophenyl)ethylenediamine]dichloroplatinum(II) (rac-4F-PtCl2), is based on the reaction of a soluble diaquaplatinum(II) salt with sodium chloride in water in the presence of pluronic F 68 as stabilizer and results in a sufficiently stable colloidal solution (i.e. hydrosol). In contrast to the poorly water soluble synthetic rac-4F-PtCl2, which was ineffective towards the hormone sensitive MXT-M-3.2 breast cancer of the mouse, its hydrosol formulation proved to be highly active and was very well tolerated.

The human poliovirus receptor. Receptor-virus interaction and parameters of disease specificity

The host range of poliovirus is determined by the expression of the hPVR, a member of the immunoglobulin superfamily. We characterized hPVR proteins biochemically and found them to be complex-type glycoproteins. The outermost V-like domain of three extracellular domains harbors the PVR function. A panel of single or multiple amino acid exchanges were introduced throughout this domain in order to localize regions involved in virus-receptor interactions. Putative contact amino acids were found to reside in the C'C"D and DE regions. Binding and uptake of poliovirus paralleled virus replication in all mutants tested suggesting that virus binding was affected without abrogating the ability to mediate subsequent events in the infection. Although the primate PVR is essential in conferring susceptibility to poliovirus infection, certain strains can induce neurological disease in rodents. Mouse neurovirulent PV isolates of divergent serotypical origin each provoked a distinctive, characteristic neurological syndrome upon intracerebral infection of wild-type mice. We analyzed clinical and histopathological features of diffuse encephalomyelitis caused by these PV strains and compared the condition with poliomyelitis in mice transgenic for the hPVR. Diffuse PV encephalomyelitis in wild-type mice could be distinguished clinically and histopathologically from hPVR-mediated poliomyelitis in trangenic mice. We localized the determinants of mouse neurovirulence of PV1(LS-a), a derivative of PV1 (Mahoney), in a portion of the viral genome encompassing parts of the capsid protein VP1 as well as the nonstructural protein 2A. Mouse neuropathogenicity could possibly be conferred by reduced particle stability of PV1(LS-a) inasmuch as we found particles to be thermolabile.

Hyaluronidase significantly enhances the efficacy of regional vinblastine chemotherapy of malignant melanoma

The regional chemotherapy of the human malignant melanomas (SK-MEL-2, -3, -5, -24) implanted in NMRI nu/nu mice with a combination of the hyaluronic-acid-cleaving enzyme hyaluronidase (HYase) and vinblastine is a very effective therapeutic procedure. In three out of four melanoma models (SK-MEL-2, -3, -5) the weekly peritumoral administration of high-dose HYase (100,000 IU/kg) 4 h prior to the injection of 0.3 mg/kg vinblastine in the vicinity of the tumor (seven weekly therapeutic cycles) caused marked antitumor effects, while HYase and vinblastine were inactive when given alone. The pretreatment with HYase, which is well tolerated by the test animals, prevented local inflammation reactions commonly seen after subcutaneous vinblastine administration. Tumor growth and metastatic behavior of the melanomas used were neither increased nor reduced by HYase after peritumoral administration without subsequent vinblastine injection. The curative activity of the regional chemotherapy with HYase/vinblastine could be demonstrated on the SK-Mel-3 melanoma. After an observation time of 18 weeks, tumor cells could no longer be detected in the subcutaneous region of the former lesion. Only macrophages, which had abundantly incorporated melanin, gave evidence of previously growing tumors. In contrast to the controls, no metastases could be observed in the axillary lymph nodes of the test animals.

The human poliovirus receptor alpha is a serine phosphoprotein

The human receptors for poliovirus (hPVR) are members of the immunoglobulin superfamily. Whereas the two membrane-bound isoforms, hPVR alpha and hPVR delta, share identical three-domain extracellular portions, their C-terminal cytoplasmic parts differ considerably. This feature is well conserved in the corresponding monkey proteins AGM alpha 1, AGM delta 1, and AGM alpha 2. The cellular function of these proteins is presently unknown. In this short communication we report that hPVR alpha and possibly also AGM alpha 1 and AGM alpha 2, but not the delta isoforms, are phosphoproteins. The phosphorylation occurs at a serine in the cytoplasmic tails of these receptors. We further present evidence suggesting that the kinase responsible for the phosphorylation is calcium/calmodulin kinase II.

The poliovirus receptor: identification of domains and amino acid residues critical for virus binding

The N-terminal domain 1 of the human poliovirus receptor (hPVR), a three-domain, immunoglobulin-like molecule, was previously shown to be necessary and sufficient to confer poliovirus (PV) susceptibility to mouse cells. However, studies with truncated versions of hPVR suggested that the C-terminal hPVR domains may contribute to receptor function. We describe sets of hybrid receptors, constructed between hPVR and hICAM-1 (human intercellular adhesion molecule-1) that were tested in mouse cells for hPVR functionally. Whereas the context in which hPVR is expressed is of minor importance, all three domains of hPVR are required to reach wild-type function. Single and multiple amino acid exchanges were introduced into the first hPVR domain in order to localize regions that were involved in virus-receptor interactions. The mutations were analyzed for their ability to bind PV1 (Mahoney) or monoclonal antibodies as well as their ability to support viral replication in either the hPVR alpha or hybrid hPVR-hICAM-1 receptor context. When placed into a model of the V domain of hPVR, the effect of the mutations indicated that the C'C"D as well as the DE region harbored amino acids that contacted the PV1(M) surface in the process of receptor-virus complex formation. The binding of the virus to the receptor and subsequent uptake into the cells were linked; no hPVR mutants were observed that bound the virus but blocked infection. N-glycosylation of the four sites in domains 1 and 2 is not required for hPVR function, but glycosylation in domain 1 has a greater effect on receptor function than that of domain 2.

Cleavage site of the poliovirus receptor signal sequence

We have shown recently that the human poliovirus receptors (hPVRs) expressed on the surface of cultured cells are 80K glycoproteins, whereas the previously reported 67K forms are partially glycosylated intermediate glycoforms. Both the membrane-bound 80K and 67K forms of hPVR are glycosylated derivatives of the two isoforms hPVR alpha and hPVR delta, where the latter two can be resolved only by SDS-PAGE upon enzymatic deglycosylation. Here we report the N-terminal sequence analysis of the mature 80K as well as the intermediate 67K glycoforms of hPVR which has allowed us to identify the signal peptidase cleavage site of the unprocessed hPVR. The signal sequence that directs translocation of hPVR across the membrane of the endoplasmic reticulum on its route to the glycoprocessing pathway has thus been defined. We compare this signal sequence with those of the putative monkey poliovirus receptor and the mouse poliovirus receptor homologue.

Interaction of poliovirus with its cell surface binding site

The interaction of poliovirus with its cellular binding sites was characterized by using a receptor-excess silicon oil partition assay. Poliovirus type 1 Mahoney [PV1(M)] binding to HeLa cells fits a theoretical simple bimolecular noncooperative binding curve with an equilibrium dissociation constant (Kd) of 4.3 x 10(7) cells.ml-1 at 4 degrees, or 2.1 x 10(-10) M, assuming 3000 virus binding sites/cell. The association rate of complex formation was measured to be 3.6 x 10(-9) ml.cell-1.min-1 (7.2 x 10(8) M-1.min-1) and the dissociation rate calculated to be 1.5 x 10(-1) min-1, giving the complex a half-life of 4.5 min. The equilibrium dissociation constant, association rate, and dissociation rate were also measured for the binding of the attenuated poliovirus type 3 Sabin strain [PV3(S)] to HeLa cells. PV3(S) bound HeLa cells with a Kd of 3.3 x 10(7) cells.ml-1 (1.6 x 10(-10) M), an association rate of 4.1 x 10(-9) ml.cell-1.min-1 (8.2 x 10(8) M-1.min-1), and a dissociation rate calculated to be 1.4 x 10(-1) min-1, giving the complex a half-life of 5.1 min. Thus the virulent and avirulent strains of poliovirus bind HeLa cells with nearly identical binding constants and rate constants. Equilibrium binding constants for PV1(M) to various other cell types varied from a high affinity of 4.1 x 10(6) cells.ml-1 for JA-1 cells to a low affinity of 7 x 10(7) cells.ml-1 for NGP cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Molecular characterization of the cellular receptor for poliovirus

The expression of the human poliovirus receptor (hPVR) in several cultured cell lines was studied with the use of different antibodies directed against hPVR proteins. Immunoprecipitations of metabolically labeled cell lysates revealed that membrane-bound glycoforms of hPVR proteins have a molecular weight of about 80 kDa. By applying inhibitors of the glycosylation pathway (deoxymannojirimycin and swainsonine) we were able to monitor the modification of the hPVR glycoproteins when passing through the processing pathway. We show that a 67-kDa hPVR protein identified earlier (using a vaccinia virus expression system) is an intermediate glycoform probably located in the endoplasmic reticulum or cis-Golgi. Further modification of this glycoform is blocked by vaccinia virus infection or by the inhibitor deoxymannojirimycin. We, therefore, conclude that the 80-kDa glycoforms identified here are the fully processed hPVR isoforms. Surface iodination confirms that only the 80-kDa glycoforms are expressed on the cell surface. Treatment with various deglycosylating enzymes (N-Glycanase, O-Glycanase, Endo-H, and neuraminidase) demonstrates that the hPVR proteins bear sialylated complex-type oligosaccharides. Deglycosylation of the hPVR proteins also reveals the presence of both hPVR membrane-bound forms in cultured cells. Their relative expression levels, with respect to each other, vary considerably. The distribution of these hPVR isoforms in tissues may help explain the natural function of the hPVR proteins.

In vitro activity of immunoconjugates between cisplatin and an anti-CA125 monoclonal antibody on ovarian cancer cell lines

Cis-diammine dichloro platinum (II) (CDDP), is a highly potent antineoplastic agent that is used in the treatment of ovarian cancer. However, the clinical use of CDDP is restricted by its severe side effects. In order to reduce these side effects and to enhance its therapeutic efficacy, we developed specific immunoconjugates consisting of the murine monoclonal antibody OC125 and CDDP, using diethylene triamine pentaacetic acid (DTPA) as a linker. The coupling efficiencies of the different preparations synthesized, varied between 1.10 +/- 0.42 and 2.65 +/- 1.60 mol of CDDP per mol of antibody protein. Despite the chemical modification of the antibody molecule, specific binding activity of the OC125-CDDP conjugates toward the CA125 antigen was maintained as was demonstrated by means of immunohisto-/cytochemical staining of frozen sections of ovarian cancer tissue, amniotic epithelium, and the CA125 positive ovarian cancer cell line NIH:OVCAR 3. The antiproliferative activity of the immunoconjugates was tested against the human ovarian cancer cell lines NIH:OVCAR 3 and SKOV 3, applying a kinetic crystal violet microassay. Despite the promising results obtained with the specific immunostaining of the target cells, no significant antiproliferative activity of our immunoconjugates against the cell lines tested was observed. One possible explanation for the lack of antitumor activity could be the fact that CA125 is released in large amounts by the NIH:OVCAR 3 cells. This may have prevented an efficient immunotargeting of the cancer cells by the formation of soluble immune complexes.

Antitumour activity of miltefosine alone and after combination with platinum complexes on MXT mouse mammary carcinoma models

Miltefosine, an alkylphosphocholine structurally related to alkyllysophospholipids showed highly selective antitumour activity against the hormone-sensitive variant of the s.c. transplantable MXT mouse mammary adenocarcinoma, the ovary-dependent MXT (M3.2), whereas it was inactive against the hormone-insensitive MXT (M3.2) OVEX variant. A dose of 32 mg/kg miltefosine p.o. daily for 5 weeks was well tolerated. Histopathological evaluation gave no signs of gastroenteral toxicity. After therapy the microarchitecture of the MXT (M3.2) tumours changed from that of a moderately differentiated adenocarcinoma to that of an anaplastic mammary carcinoma. A dose of 16 mg/kg miltefosine p.o. daily, though in effective per se, enhanced the antitumour activity of suboptimal i.p. doses of cisplatin and the hormone-like platinum analogue meso-1,2-bis(2,6-dichloro-4-hydroxyphenyl) ethylenediamine]dichloroplatinum(II). Furthermore, it was shown, that miltefosine exhibited no (anti)hormonal properties. However, the mechanism of action of miltefosine remains unclear.

Establishment and characterization of a human papillary thyroid carcinoma cell line with oxyphilic differentiation (ONCO-DG 1)

In the present study the establishment and characterization of a new oxyphilic papillary thyroid carcinoma cell line--ONCO-DG1- is given. With immunohistological, histochemical and flow cytometric methods, ONCO-DG 1 cells revealed features of epithelial differentiation. Furthermore the cells formed von Kossa-positive deposits resembling psammoma bodies in monolayer and spheroid culture until late passages. The tumor cell line is now in the 40th subculture. Because of the ability to form multicellular tumor spheroids (MCTS), this cell line is a good model for examining the interaction between thyroid tumor cells and confluent human endothelial cells on extracellular matrix in vitro. It is also suitable for xenotransplantation studies, because it is tumorigenic in NMRI nude mice in vivo.

Hyaluronidase enhances the activity of adriamycin in breast cancer models in vitro and in vivo

The effect of hyaluronidase and a combination of hyaluronidase with Adriamycin was investigated on several breast cancer models in vitro and in vivo. In vitro enzyme treatment (using concentrations up to 80,000 IU/1) of murine (MXT-, MXT +/-, and MXT+) and human (MCF-7, ZR-75-1 and T-47-D) breast cancer cell lines did not inhibit tumour cell proliferation (measured by a kinetic crystal violet assay) in either case. Although high-dose hyaluronidase (1.2 x 10(6) IU/kg) was ineffective, when administered peritumourally to the MXT M3.2 mammary carcinoma of the B6D2F1 mouse, it is remarkable that five "megadoses" were excellently tolerated. However, the antineoplastic activity of Adriamycin against the oestrogen-receptor-positive variant of the MXT tumour was significantly enhanced by combination with concentrations of hyaluronidase that were inactive per se, both in vitro and in vivo. Interestingly, the enhancement of the in vivo antitumour activity was not compromised by toxic side-effects.

[1,2-Bis(2-hydroxyphenyl)ethylenediamine]dichloroplatinum(II), a new compound for the therapy of ovarian cancer. II. Synthesis and preliminary testing of the enantiomeric complexes

The enantiomeric [1,2-bis(2-hydroxyphenyl)-ethylenediamine]dichloroplatinum(II) complexes were synthesized and their configuration assessed. A preliminary test in the cisplatin-resistant human NIH:OVCAR-3 ovarian cancer cell line, which was previously characterized by its sensitivity against several therapeutically used drugs, showed that both enantiomers produce cytocidal effects in a concentration of 2.5 microM. A difference between the enantiomers became evident from the faster onset of cytocidal activity of the S,S-configurated compound.

[1,2-Bis(2-hydroxyphenyl)ethylenediamine]dichloroplatinum(II), a new compound for the therapy of ovarian cancer. III. Detailed evaluation of the antitumor activity of the enantiomeric complexes on the human NIH:OVCAR-3 ovarian cancer cell line

The stereoisomeric [1,2-bis(2-hydroxyphenyl)ethylenediamine]dichloroplatinum(II) complexes were thoroughly tested on the cisplatin-resistant human NIH:OVCAR-3 ovarian cancer cell line. The racemate and its enantiomers produced cytocidal effects at a concentration of 2.5 microM (incubation time 256 h). The meso form, however, was merely cytostatically active. Differences between the enantiomers became evident after a short drug incubation time (1 h) followed by an incubation in drug-free medium (243 h). The S,S-configurated enantiomer (-)-3-PtCl2 proved to be the most active compound. To achieve cytocidal effects concentrations of 2.5-5.0 microM and incubation times of about 3 h were necessary for (-)-3-PtCl2. This compound is also sufficiently stable under test conditions as shown by the preincubation in cell-free medium for 3 h. These results and the augmentation of its antitumor activity by buthionine sulfoximine recommend the further preclinical development of (-)-3-PtCl2 for clinical use.

Dichloro-[1-(hydroxyphenyl)-2-phenylethylenediamine]platinum(II) complexes: testing on the human ovarian cancer cell lines NIH: OVCAR3 and SK OV 3

The diastereoisomeric dichloro-[1-(2-, 3- and 4-hydroxyphenyl)-2-phenylethylenediamine]platinum(II) complexes were tested on two human ovarian cancer cell lines NIH: OVCAR-3 and SK-OV-3, both resistant against cisplatin. Dichloro-[threo-1-(3-hydroxyphenyl)-2-phenylethylenediamine]platinum(II) (threo-5-PtCl2) proved to be the most active representative of the new series, producing cytocidal effects at a concentration range of 2.5 to 5.0 microM on the NIH: OVCAR-3 cell line. On the more resistant SK-OV-3 cell line, threo-5-PtCl2 was only moderately active, while in combination with BSO, a GSH level lowering compound, threo-5-PtCl2 showed a strong synergistic effect.

Standardized kinetic microassay to quantify differential chemosensitivity on the basis of proliferative activity

Conventionally in vitro cytotoxicity assays are performed as single-end-point determinations. To compensate for the diversity of growth rates among different cell lines in this report we describe a computerized kinetic chemosensitivity assay based on quantification of biomass by staining cells with crystal violet. As a prerequisite four human breast cancer cell lines (MDA-MB-231, MCF-7, T-47-D and ZR-75-1) were characterized with regard to oestrogen and progesterone receptor content, modal chromosome number and proliferation kinetics depending on the number of passages in culture. With prolonged time in culture for ZR-75-1 exposed to various concentrations of cisplatinum a dose-related increase in drug effect was observed. Owing to a correction of the T/C values for the initial cell mass (at the time when drug is added) a sharp distinction between cytostatic and cytocidal drug effects becomes obvious in plots of corrected T/C values versus time of incubation. The influence of the untreated control on the corrected T/C values and possible time courses of theoretical inhibition profiles (reflecting cytostatic, transient cytotoxic or cytocidal drug effects as well as development of resistance) and their relationship to the corresponding growth curves of drug-treated cells are discussed. Chemosensitivity assays with diethylstilbestrol dipropionate, tamoxifen, melphalan, cisplatinum, vinblastine, Adriamycin and 5-fluorouracil prove the theoretical considerations to be true for MDA-MB-231, MCF-7, T-47-D and ZR-75-1 human breast cancer cell lines in practice.

Chemosensitivity of human MCF-7 breast cancer cells to diastereoisomeric diaqua(1,2-diphenylethylenediamine) platinum(II) sulfates and specific platinum accumulation

Cisplatin, raceme-diaqua[1,2-bis(4-fluorophenyl)ethylenediamine]platinu m(II) sulfate (compound I), meso-diaqua[1,2-bis(4-fluorophenyl)ethylenediamine]-platinum(II) sulfate (compound II), and meso-diaqua[1,2-bis(2,6-dichloro-4- hydroxyphenyl)ethylenediamine]platinum(II) sulfate (compound III) were compared with regard to their effect on the MCF-7 breast cancer cell line in vitro. At equimolar concentrations (5 microM), cisplatin, compound I, and compound II were equiactive after 231 h drug exposure, whereas compound III was ineffective. Although compounds I and II showed markedly greater inactivation than did cisplatin after 6 h incubation with culture medium, compound I (but not compound II) exhibited antitumor activity equivalent to that of cisplatin when cells were exposed to the drugs for 6 h. Platinum measurements by neutron-activation analysis revealed that compound I was selectively and rapidly accumulated by MCF-7 cells, resulting in a high degree of DNA platination within the first few hours of drug exposure. However, when the drug-exposure period was long enough, platinum enrichment was not reflected in an overall difference in the cytotoxicity of compound I vs cisplatin. Nevertheless, compound I should be superior to cisplatin in vivo, provided that effective plasma levels can be maintained for about 6 h.

Different response of murine and human mammary tumour models to a series of diastereoisomeric [1,2-bis(difluorophenyl) ethylenediamine]dichloroplatinum(II) complexes

A series of isomeric [1,2-bis(difluorophenyl) ethylenediamine]dichloroplatinum(II) complexes and cisplatin were tested on the P388 leukemia and on the murine hormone-independent MXT (M3.2) OVEX and the ovarian-hormone-dependent MXT (M3.2) mammary carcinoma for evaluating antineoplastic activity against breast cancer in vivo. Although these results were heterogeneous, a trend to the 2,6-difluorosubstituted compound as the most active platinum complex was observed. For the development of a large-scale in vitro screening method on human breast cancer cell lines, cell number, [3H]thymidine incorporation, and crystal violet staining were evaluated as parameters for end-point determination. Chemosensitivity testing on the human breast cancer cell lines MDA-MB-231 and MCF-7 unambiguously identified [1,2-bis(2,4-difluorophenyl)ethylenediamine]dichloroplatinum(II) as the complex with the highest activity in the crystal violet micro-assay. In equimolar concentration this compound was superior to cisplatin on both cell lines. The analysis of the conflicting results of this study indicates that murine mammary carcinomas are most probably unrealistic and inappropriate models for the screening of cytotoxic platinum complexes with potential activity on human breast cancer.

Mechanism of sucrose retrieval along the phloem path - a kinetic approach

In contrast to hexoses (fructose, glucose, 3-oxymethylglucose) sucrose is preferentially taken up by isolated conducting tissue ofCyclamen persicum Mill. Sucrose absorption follows a biphasic kinetic, with a saturable component (Km=5.2 mM; Vmax = 4.2 μmol · g FW(-1) · h(-1)) in the lower range (<20 mM) and a linear component in the upper range (20-400 mM). The saturable, carrier-mediated uptake operates against the concentration gradient without attaining any equilibrium over 6 h. It is characterized by a pH optimum at 4.5 and sensitivity to the protonophore CCCP (carbonylcyanidem-chlorophenylhydrazone). The activity of the saturable uptake increases with decreasing turgor and it is independent of the presence of hexoses. There is no effect of pH or CCCP on linear sucrose uptake at high external concentrations. Hexose uptake between 0.25 and 20 mM shows a entirely linear kinetic. Leakage after preincubation with 1 mM sucrose exhibits a minimum at pH 5.0 and enters a steady state within 100 min. Furthermore, it was found to be independent of the osmolarity of the external solution. Results are discussed in terms of apoplastic leakage and reabsorption along the phloem path: efflux of sucrose is compensated by a specific, carrier-mediated influx, which is qualitatively similar to apoplastic phloem loading accomplished by proton cotransport. In according with the balanced efflux and influx it should be considered rather as a retrieval than a loading mechanism.

Tumor-inhibiting [1,2-bis(fluorophenyl)ethylenediamine]platinum(II) complexes. V. Synthesis and evaluation of enantiomeric [1,2-bis-(4-fluorophenyl)ethylenediamine]dichloroplatinum(II) complexes

The enantiomeric [1,2-bis(4-fluorophenyl)ethylenediamine]dichloroplatinum(II) complexes were synthesized and tested on the hormone-sensitive human MCF7 breast cancer cell line and on the P388 leukemia of the mouse. They showed a strong and comparable activity on both tumor models.

Computerized determination of growth kinetic curves and doubling times from cells in microculture

In this paper we describe the microcomputer-aided determination of cell proliferation kinetics and doubling times utilizing a crystal violet assay and a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide assay in microtitration plates. The analysis of spectrophotometric data provides the doubling times at any time of incubation. Plots of doubling time versus time of incubation give reproducible information on the exact duration of the logarithmic growth phase. This method is applicable to anchorage-dependent as well as anchorage-independent cells when colorimetric or fluorometric data are accessible.

[DL-1,2-bis(2-hydroxyphenyl)ethylenediamine]dichloroplatinum(II), a new compound for the therapy of ovarian cancer

The synthesis of diastereoisomeric [1,2-bis(2-hydroxyphenyl)ethylenediamine]dichloroplatinum(II) complexes, DL-3-PtCl2 and meso-3-PtCl2, and their evaluation on the hormone-independent, human MDA-MB231 breast cancer cell line, on the cisplatin-sensitive and -resistant L1210 leukemia cell line, on the cisplatin-resistant human NIH:OVCAR 3 ovarian cancer cell line, on the P-388 leukemia of the mouse and on the cisplatin-sensitive and -resistant Ehrlich ascites tumor of the mouse are described. On all tumor models DL-3-PtCl2 produces a marked inhibitory effect. The diastereoisomer meso-3-PtCl2 is less active and more toxic. It is striking that DL-3-PtCl2 leads to a pronounced inhibition of all cisplatin-resistant tumors. At non-toxic concentrations DL-3-PtCl2 produces cytocidal effects on the NIH:OV-CAR 3 cell line. Therefore DL-3-PtCl2 is of interest for further evaluation for the therapy of ovarian cancer.

Tumor inhibiting [1,2-bis(fluorophenyl)ethylenediamine]platinum(II) complexes, III: Evaluation of the mammary tumor inhibiting properties

Diastereomeric diaqua[1,2-bis(4-fluorophenyl)ethylenediamine]platinum(II) sulfates and nitrates produce a strong inhibition of the hormone-dependent MXT-M 3.2 mammary carcinoma of the B6D2F1 mouse. Besides an interference in the DNA synthesis in analogy to cisplatin a lowering of the estrogen level due to an interference in steroid biosynthesis is suggested as the mode of action. In contrast to the R,R/S,S configurated diaqua[1,2-bis(4-fluorophenyl)ethylenediamine]platinum(II) salts the corresponding R,S configurated compounds are also markedly active on the hormone-independent MXT-Ovex mammary carcinoma of the B6D2F1 mouse.

Tumor inhibiting [1,2-bis(fluorophenyl)ethylenediamine]platinum(II) complexes. Part II: Biological evaluation-in vitro studies on the P 388 D1 leukemia cell line

Experiments on the P 388 D1 cell line (48 h exposure) demonstrate that [1,2-bis-(fluorophenyl)ethylenediamine]platinum(II) complexes are comparably active on the cell number and 3H-thymidine incorporation, irrespective of the position of the fluorine atom (ortho, meta, or para) and the nature of the "leaving group" (Cl- or H2O). However, the compounds of the R,R/S,S series are more active than those of the R,S series and comparable to cisplatin. In the "tumor colony forming assay" the R,R/S,S configurated compounds are about ten times as active as cisplatin. The R,R/S,S configurated diaqua[1,2-bis(4-fluorophenyl)ethylenediamine]platinum(II) salts reach their half maximum effect more readily (t1/2 approximately equal to 1.6 h) than their R,S configurated analogues (t1/2 approximately equal to 20 h). A time limited contact of the cells with R,R/S,S configurated diaqua[1,2-bis(4-fluorophenyl)ethylenediamine]platinum(II) salts (-1h) leads to a similar inhibition like a permanent drug exposure indicating a fast uptake of the complex by the tumor cell. In experiments on the Ehrlich ascites tumor of the mouse and on the L 1210 leukemia cell line R,R/S,S-[1,2-bis(4-fluorophenyl)ethylenediamine]dichloroplatinum(II) turns out to be equipotent with cisplatin.

Trans-activation of human MYC: the second promoter is target for the stimulation by adenovirus E1a proteins

The detailed mechanisms leading to transcriptional activation of the human MYC oncogene in general as well as in certain tumor cells are poorly understood. In view of the ability of a number of viral oncogenes to stimulate transcription in trans, the identification of cellular target genes could contribute to the understanding of components of the transformation process. It is demonstrated that the human MYC promoter is such an efficient target for the trans-acting activity mediated by E1a proteins of adenoviruses (Ad). Using the chloramphenicol acetyltransferase (CAT) gene as a marker for promoter activity, co-transfection of constructs containing both MYC promoters and most of the untranslated first exon with plasmids expressing the E1a gene of different adenoviruses stimulates CAT activity up to 24-fold. Trans-activation depends upon the presence of the second promoter (P2), and transcription is initiated at the authentic cap site of P2. This observation is confirmed by the behaviour of stably transformed cell lines carrying single or multiple copies of MYC-cat constructs, which were transfected either with E1a-expressing plasmids, infected with Ad5, or fused with 293 cells constitutively expressing E1a protein. These results suggest that E1a proteins can lead to an imbalance of the regulation of the human MYC gene, which might be a sufficient prerequisite for initiation and progression of transformation.

Pressure-Induced Alterations in the Protein Pattern of the Thermophilic Archaebacterium Methanococcus thermolithotrophicus

Elevated hydrostatic pressure has been shown to affect the growth rate of the thermophilic methanobacterium Methanococcus thermolithotrophicus without extending its temperature range of viability. Analysis of the cell inventory after ≈ 10 h of incubation at 65°C and 50 MPa (applying high-pressure liquid chromatography and two-dimensional gel electrophoresis) proved that pressure induces alterations in the protein pattern and the amino acid composition of the total cell hydrolysate. Gels showed that after pressurization a series of (basic) proteins with a molecular mass in the range of 38 and 70 kilodaltons occurs which is not detectable in cells grown at normal atmospheric pressure. The question of whether the observed alterations are caused by the perturbation of the balance of protein synthesis and turnover or by the pressure-induced synthesis of compounds analogous to heat shock proteins remains unanswered.

[Laser trabeculoplasty in glaucoma chronicum simplex. Results of a prospective, clinical study]

Between 1984 and 1986, 104 patients with open-angle glaucoma of various etiologies were treated by laser trabeculoplasty (LTP) in a prospective clinical study. In order to ensure that the group of patients studied was homogeneous, only the 85 consecutive patients (85 eyes) with primary open-angle glaucoma were included, using a specially designed software program. The number of patients with pseudoexfoliation glaucoma, aphakic glaucoma, and congenital glaucoma was too small to allow statistical comparison with those who had chronic open-angle glaucoma. Criteria for success were defined as follows: no progression of disk cupping or visual field defects, mean intraocular pressure below 24 mm Hg as calculated by a day profile, and no increase in medication. These conditions were satisfied by 76% of the patients after six months and by 64% after 12 months. Initially, coagulations were performed over 180 degrees in the inferior circumference. If this did not suffice, the upper 180 degrees were also coagulated. If LTP is to be effective, thorough coagulation with tender blanching effects is mandatory. Average preoperative pressure values of over 22 mm Hg and a postoperative pressure increase of between 5 and 14 mm Hg are favorable prognostic signs. None of the parameters age, sex, duration, intensity of glaucomatous disease, or preoperative medication had any influence on the efficacy of LTP. In 14 of the 45 patients in whom only one eye was treated a simultaneous decrease in pressure was also observed in the untreated eye. The side effects of LTP bear no relation to its benefits, so that LTP is very suitable as a therapy between medication and surgery. Careful follow-ups of the patients are necessary because of possible increases in intraocular pressure in the course of time.

High Pressure Enhances the Growth Rate of the Thermophilic Archaebacterium Methanococcus thermolithotrophicus without Extending Its Temperature Range

Temperature and hydrostatic pressure are essential in determining the assemblage of species in their specific biotopes. To evaluate the effect of high pressure on the range of viability of thermophiles, the pressure and temperature dependence of the growth of the methanogenic archaebacterium Methanococcus thermolithotrophicus was investigated. High pressure up to 50 MPa enhanced the growth rate without extending the temperature range of viability. The optimum temperature remained unaltered (65°C). Beyond 50 MPa, cell lysis predominated over cell proliferation. Destabilization was also observed at temperatures below and above the optimum growth temperature (<60°C, ≥70°C) and at low substrate concentrations.

High-Pressure Equipment for Growing Methanogenic Microorganisms on Gaseous Substrates at High Temperature

High-pressure, high-temperature investigations on thermophilic microorganisms that grow on hydrogen or other gaseous substrates require instrumentation which provides sufficient substrate for cell proliferation up to 2 × 10 8 to 3 × 10 8 cells per ml under isothermal and isobaric conditions. To minimize H 2 leakage and to optimize reproducibility at high pressure and high temperature, 10-ml nickel tubes with a liquid/gas ratio of 1:2 were used in a set of autoclaves connected in series. By applying a hydraulic pump and a 2.5-kW heating device, fast changes in temperature (up to 400°C) and pressure (up to 400 MPa) can be accomplished within less than 10 min. To quantify bacterial growth, determinations of cell numbers per unit volume yielded optimum accuracy. Preliminary experiments with the thermophilic, methanogenic archaebacterium Methanococcus thermolithotrophicus showed that bacterial growth depends on both temperature and pressure. At the optimum temperature, increased hydrostatic pressure up to 50 MPa enhanced the growth yield; at a pressure of >75 MPa, cell lysis dominated. Changes in cell proliferation were accompanied by changes in morphology.

Reassociation of lactic dehydrogenase from pig heart studied by cross-linking with glutaraldehyde

Cross-lining with glutaraldehyde has been successfully applied in order to analyze the kinetics of reassociation of oligomeric enzymes (R. Hermann, R. Rudolph, and R. Jaenicke Nature 277, 243 - 245 (1979). In the present study other assembly of lactic dehydrogenase from pig heart is investigated using this approach. In order to eliminate pertubations caused by excessive folding reactions, acid dissociation was performed in the presence o 0.8 M Na2SO4 at 0 degrees C. Under optimum conditions complete cross-linking during reconstitution proves the dimer to be the only intermediate of reassociation. The dimer leads to tetramer transition is found to be rate-limiting for both reassociation and reactivation, suggesting the tetramer to be the enzymatically active species. The presence of monomers during reconstitution indicates that tetramer formation is preceded by a fast monomer-dimer equilibrium. The kinetics model describing the experimental data.

Similar cell surface antigens on hamster cells transformed by different papovaviruses

Transformed baby hamster kidney (BHK) cells were tested for surface antigens by an immunocytoadhesion method. The cells were sensitized with rabbit antisera to cell clones transformed by polyoma or by BK virus and then rosetted with erythrocytes coated with antibody to rabbit immunoglobulin. These antisera detected common antigens on BHK cells transformed by either of three papovaviruses, polyoma, BK, or SV40, but apparently not on normal BHK cells.

Comparison of the serology, transforming ability, and polypeptide composition of human papovaviruses isolated from urine

Four isolates of human papovaviruses (RF, GS, DW, and MG viruses) obtained from the urine specimens of renal allograft recipients in widely separated locations were compared with BK virus. Hemagglutination inhibition tests and plaque neutralization assays showed that all were antigenically related to BK virus. All isolates transformed baby hamster kidney cells, transformation being determined by the ability of the cells to plate in soft agar. Purified preparations of each isolate were iodinated with chloramine T and the polypeptide compositions were compared by electrophoresis of disrupted viruses in polyacrylamide gels containing sodium dodecyl sulfate. The gel patterns of all isolates were similar to that of BK virus. The tryptic digests of two major iodinated virion proteins, VP1 and VP3, were analyzed on an ion exchange column. The peptide patterns of GS, DW, and BK virus were identical; those of RF and MG virus closely resembled the patterns of the above three with only minor differences in some peptides. The results show that the four isolates and BK virus are antigenically closely related, have similar onocogenic potential, and are distinguishable from simian virus 40 and JC virus.