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H Bader

Publications and source records attributed to H Bader.

At least 55 records · Page 3Linked to original sources
PubMed1989

Prevention of anaphylactoid shock in the rat by the calmodulin antagonist thioridazine.

Calmodulin antagonists, which block intracellular calcium/calmodulin-dependent processes like exocytosis, inhibit effectively mast cell mediator release in vitro. Our experiments confirm that they are also effective in vivo. Thioridazine (5 mg/kg), a representative of the group, prevents the severe anaphylactoid shock in the rat, induced with compound 48/80, and permits a rapid and complete recovery, with special protection of respiration. Thus, calmodulin antagonists seem to be potential drugs for the management of mast cell-mediated allergic diseases.

Anaphylaxis↗
PubMed1988

Methotrexate analogues. 31. Meta and ortho isomers of aminopterin, compounds with a double bond in the side chain, and a novel analogue modified at the alpha-carbon: chemical and in vitro biological studies.

Five heretofore undescribed analogues of methotrexate (MTX) and aminopterin (AMT) were synthesized and tested as dihydrofolate reductase (DHFR) inhibitors and tumor cell growth inhibitors. The meta isomer of AMT was obtained from 2,4-diamino-6-(bromomethyl)pteridine and m-(aminobenzoyl)-L-glutamic acid, while the ortho isomer was obtained via the same route by using alpha-methyl gamma-tert-butyl o-(aminobenzoyl)-L-glutamate instead of the free acid. Analogues of MTX and AMT containing a double bond in the side chain were prepared from dimethyl D,L-2-amino-4-hexenedioate and 4-amino-4-deoxy-N10-methylpteroic acid and 4-amino-4-deoxy-N10-formylpteroic acid, respectively. Finally, a positional isomer of MTX with the CH2CH2COOH moiety moved from the alpha-carbon to the adjacent carboxamide nitrogen was synthesized from 3-[N-(carboxymethyl)amino]propanoic acid diethyl ester and 4-amino-4-deoxy-N10-methylpteroic acid. The positional isomers of AMT were weak DHFR inhibitors and showed very little growth-inhibitory activity against L1210 murine leukemia cells or the MTX-resistant L1210/R81 mutant line in culture. The MTX and AMT analogues with the CH2CH2COOH moiety replaced by a CH2CH = CHCOOH side chain showed anti-DHFR activity similar to that of the previously described saturated compound N-(4-amino-4-deoxy-N10-methylpteroyl)-L-2-aminoadipic acid, but were less potent than the parent drugs. The MTX analogue with the CH2CH2COOH side chain displaced from C to N was weakly bound to DHFR, confirming the importance of an intact CONH moiety, and showed greatly diminished cell growth inhibitory potency relative to MTX. None of the compounds was a substrate for folylpolyglutamate synthetase (FPGS) from mouse liver. Furthermore, inhibition of folic acid polyglutamylation in vitro at equimolar 500 microM concentrations of drug and substrate was negligible. The structural changes embodied in these five novel compounds are therefore too great for binding to the FPGS active site.

Aminopterin↗
PubMed1988

Methotrexate analogues. 33. N delta-acyl-N alpha-(4-amino-4-deoxypteroyl)-L-ornithine derivatives: synthesis and in vitro antitumor activity.

N delta-Acyl derivatives of the potent folylpolyglutamate synthetase (FPGS) inhibitor N alpha-(4-amino-4-deoxypteroyl)-L-ornithine (APA-L-Orn) were synthesized from N alpha-(4-amino-4-deoxy-N10-formylpteroyl)-L-ornithine by reaction with an N-(acyloxy)succinimide or acyl anhydride, followed by deformylation with base. The N delta-hemiphthaloyl derivative was also prepared from 4-amino-4-deoxy-N10-formylpteroic acid by reaction with persilylated N delta-phthaloyl-L-ornithine, followed by simultaneous deformylation and ring opening of the N delta-phthaloyl moiety with base. The products were potent inhibitors of purified dihydrofolate reductase (DHFR) from L1210 murine leukemia cells, with IC50's ranging from 0.027 and 0.052 microM as compared with 0.072 microM for APA-L-Orn. Several of the N delta-acyl-N10-formyl intermediates also proved to be good DHFR inhibitors. One of them, N alpha-(4-amino-4-deoxy-N10-formylpteroyl)-N delta-(4-chlorobenzoyl)-L- ornithine, had a 2-fold lower IC50 than its deformylated product, confirming that the N10-formyl group is well tolerated for DHFR binding. While N delta-acylation of APA-L-Orn did not significantly alter anti-DHFR activity, inhibition of FPGS was dramatically diminished, supporting the view that the basic NH2 on the end of the APA-L-Orn side chain is essential for the activity of this compound against FPGS. N delta-Acylation of APA-L-Orn markedly enhanced toxicity to cultured tumor cells. However, N delta-acyl derivatives also containing an N10-formyl substituent were less cytotoxic than the corresponding N10-unsubstituted analogues even though their anti-DHFR activity was the same, suggesting that N10-formylation may be unfavorable for transport. Two compounds, the N delta-benzoyl and N delta-hemiphthaloyl derivatives of APA-L-Orn, with IC50's against L1210 cells of 0.89 and 0.75 nM, respectively, were more potent than either methotrexate (MTX) or aminopterin (AMT) in this system. These compounds were also more potent than MTX against CEM human lymphoblasts and two human head and neck squamous cell carcinoma cell lines (SCC15, SCC25) in culture. Moreover, in assays against SCC15/R1 and SCC25/R1 sublines with 10-20-fold MTX resistance, the N delta-hemiphthaloyl derivative of APA-L-Orn showed potency exceeding that of MTX itself against the parental cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Aminopterin↗
PubMed1988

Methotrexate analogues. 34. Replacement of the glutamate moiety in methotrexate and aminopterin by long-chain 2-aminoalkanedioic acids.

Eight previously unreported methotrexate (MTX) and aminopterin (AMT) analogues with the L-glutamate moiety replaced by DL-2-aminoalkanedioic acids containing up to 10 CH2 groups were synthesized from 4-amino-4-deoxy-N10-methylpteroic or 4-amino-4-deoxy-N10-formylpteroic acid. All the compounds were potent inhibitors of purified L1210 mouse leukemia dihydrofolate reductase (DHFR), with IC50's of 0.023-0.034 microM for the MTX analogues and 0.054-0.067 microM for the AMT analogues. The compounds were not substrates for, but were inhibitors of, partially purified mouse liver folylpolyglutamate synthetase (FPGS). Activity was correlated with the number of CH2 groups in the side chain. The IC50's for inhibition of cell growth in culture by the chain-extended MTX analogues were 0.016-0.64 microM against CEM human leukemic lymphoblasts and 0.0012-0.026 microM against L1210 mouse leukemia cells. However, the optimal chain length for growth-inhibitory activity was species-dependent. Our results suggested that CEM cells were inhibited most actively by the analogue with nine CH2 groups, while L1210 cells were most sensitive to the analogue with six CH2 groups. Among the AMT analogues, on the other hand, the most active compound against L1210 cells was the one with nine CH2 groups, which had an IC50 of 0.000 65 microM as compared with 0.0046 microM for MTX and 0.002 microM for AMT. A high degree of cross-resistance was observed between MTX and the chain-extended compounds in two MTX-resistant cell lines, CEM/MTX and L1210/R81. All the MTX analogues were active against L1210 leukemia in mice on a qd X 9 schedule, with optimal increases in lifespan (ILS) of 75-140%. Notwithstanding their high in vitro activity, the AMT analogues were more toxic and less therapeutically effective than MTX analogues of the same chain length even though neither series of compounds possessed FPGS substrate activity. These MTX and AMT analogues are an unusual group of compounds in that they retain the dicarboxylic acid structure of classical antifolates yet are more lipophilic than the parent compounds because they have more CH2 groups and are almost equivalent in vivo to MTX on the same schedule even though they do not form polyglutamates.

Amino Acids, Dicarboxylic↗
PubMed1987

Synthesis and biologic activity of new side-chain-altered methotrexate and aminopterin analogs with dual inhibitory action against dihydrofolate reductase and folylpolyglutamate synthetase.

Replacement of the glutamic acid (Glu) moiety in methotrexate (MTX) and aminopterin (AMT) by 2-amino-4-phosphonobutyric acid (APBA) and ornithine (Orn) has been found to give analogs that retain the ability to inhibit dihydrofolate reductase (DHFR) while also displaying high activity against folylpolyglutamate synthetase (FPGS). One of these compounds, the Orn analog of AMT, is the most potent FPGS inhibitor we have found to date. A model to account for the fact that side-chain analogs containing a basic and those containing an acidic terminal group can both competitively inhibit FPGS is proposed. According to this model, binding may involve interaction of an acidic terminal group on the inhibitor with a positively charged active-site residue to which the gamma-carboxyl of the folate-antifolate substrate normally binds. It may also involve the interaction of a basic terminal group on the inhibitor with a different active-site residue which is negatively rather than positively charged and to which the alpha-amino group of the incoming Glu cosubstrate must bind before an amide bond to the gamma-carboxyl of the folate-antifolate can form. The 2 oppositely charged active-site residues assumed to take part in this binding are probably situated near each other and at approximately the same distance from the pteridine-binding site. The ability of compounds to inhibit both DHFR and FPGS makes it possible in principle for such compounds to kill cells via a "self-potentiation" mechanism in which inhibition of tetrahydrofolate synthesis is complemented by interference with the subsequent conversion of tetrahydrofolates to their polyglutamate conjugates. Possible exploitation of this mechanism to overcome MTX resistance is considered.

Aminobutyrates↗
PubMed1986

Methotrexate analogues. 26. Inhibition of dihydrofolate reductase and folylpolyglutamate synthetase activity and in vitro tumor cell growth by methotrexate and aminopterin analogues containing a basic amino acid side chain.

Analogues of the antitumor antifolate methotrexate (MTX) were synthesized in which the glutamate (Glu) moiety was replaced by ornithine (Orn), 2,4-diaminobutyric acid (Dab), or 2,3-diaminopropionic acid (Dap). An aminopterin (AMT) analogue with Orn in place of Glu was also synthesized. The MTX analogues were obtained by reaction of 4-amino-4-deoxy-N10-methylpteroic acid (mAPA) and N omega-Boc-alpha,omega-diaminoalkanoic acids in the presence of diethyl phosphorocyanidate, followed by deprotection with trifluoroacetic acid (TFA) or by reaction of p-nitrophenyl-mAPA and N omega-Boc-alpha,omega-diaminoalkanoic acids and subsequent treatment with TFA. The AMT analogue (APA-Orn) was synthesized by reaction of p-nitrophenyl 4-amino-4-deoxy-N10-formylpteroate with silylated N delta-Boc-L-ornithine in DMF at 55 degrees C for 3 days (45% yield), saponification (83%), and TFA cleavage (89%). APA-Orn was a potent inhibitor of both dihydrofolate reductase (DHFR) from L1210 mouse leukemia (IC50 = 0.072 microM) and partly purified folylpolyglutamate synthetase (FPGS) from mouse liver (Ki = 0.15 +/- 0.06 microM). The MTX analogue (mAPA-Orn) was likewise active against both enzymes, with an IC50 of 0.160 microM for DHFR and a Ki of 20.4 +/- 7.7 microM for FPGS inhibition. The other MTX analogues and the previously reported lysine derivative (mAPA-Lys) showed DHFR affinity similar to that of mAPA-Orn but lacked activity as FPGS inhibitors. The positively charged amino group appears to be detrimental to cellular uptake, as evidenced by the low cytotoxicity of these compounds (IC50 = 0.40-2.4 microM) in comparison with MTX and AMT (IC50 = 0.002 microM) against wild-type L1210 cells. On the other hand, mAPA-Orn and APA-Orn were both more potent than the corresponding Glu derivatives MTX and AMT against L1210/R81 cells, suggesting that in these MTX-resistant cells there may occur a "self-potentiation" process involving enhanced antifolate activity via interference with the polyglutamylation of reduced folates. APA-Orn is the most potent dual inhibitor of DHFR and FPGS discovered to date, but its effectiveness as a therapeutic agent may require some form of prodrug modification to neutralize the terminal amino group of the side chain.

Aminobutyrates↗
PubMed1986

Methotrexate analogues. 28. Synthesis and biological evaluation of new gamma-monoamides of aminopterin and methotrexate.

Lipophilic gamma-monoamide derivatives of aminopterin (AMT) were synthesized in high overall yield from 4-amino-4-deoxy-N10-formylpteroic acid and gamma-N-tert-alkyl-, gamma-N-aralkyl-, or gamma-N-arylamides of alpha-benzyl L-glutamate via a modification of the mixed carboxylic-carbonic anhydride coupling method. Coupling was also accomplished with p-nitrophenyl 4-amino-4-deoxy-N10-formylpteroate. Compounds obtained in this manner included the gamma-tert-butylamide, gamma-(1-adamantylamide), gamma-benzylamide, gamma-(3,4-dichlorobenzylamide), gamma-(2,6-dichlorobenzylamide), gamma-anilide, gamma-(3,4-methylenedioxyanilide), and gamma-(3,4-dihydroxanilide) derivatives of AMT. Also prepared, from 4-amino-4-deoxy-N10-methylpteroic acid via diethyl phosphorocyanidate coupling, was the gamma-(3,4-methylenedioxyanilide) of MTX. The methylenedioxyanilides were cleaved smoothly to dihydroxyanilides with boron tris(trifluoroacetate) in trifluoroacetic acid. All the gamma-monoamides were tested as inhibitors of purified dihydrofolate reductase (DHFR) from murine L1210 leukemia cells and as inhibitors of the growth of wild-type L1210 cells and a subline (L1210/R81) with high-level resistance to MTX and AMT based mainly on a defect in drug uptake via active transport. Several compounds were also tested against human leukemic lymphoblasts (CEM cells) and a resistant subline (CEM/MTX) whose resistance is likewise based on uptake. The IC50 of the gamma-monoamides against DHFR was 1.5- to 5-fold higher than that of the parent acids, but the IC50 against cultured cells varied over a much broader range, suggesting that uptake and/or metabolism rather than DHFR binding are principal determinants of in vitro growth inhibitory activity for these compounds. gamma-N-Aryl and gamma-N-aralkyl derivatives appeared to be more potent than gamma-N-tert-alkyl derivatives. Where comparison could be made, AMT gamma-monoamides were more potent than MTX gamma-monoamides. Several of the gamma-monoamides showed potency comparable to that of the parent acid against wild-type L1210 and CEM cells; all of them were more potent than MTX against the L1210/R81 subline; and some of the AMT gamma-monoamides were also more potent than the parent acid against resistant CEM/MTX cells. As a group, however, the gamma-monoamides were considerably more active against the murine cells than against the human cells, suggesting that the former may take up the amides better or may be able to metabolize them more efficiently than the parent acids. All the gamma-monoamides were tested in vivo against L1210 leukemia in mice.(ABSTRACT TRUNCATED AT 400 WORDS)

Amides↗
PubMed1986

[Cancer of the large intestine--a sequela of ureterosigmoidostomy].

Carcinoma or polyps of the colon as a late complication of ureterosigmoidostomia (USS) have been reported with increasing frequency. Three patients are presented, two of them developed a signet-ring cell carcinoma after USS; one patient showed, 6 years after rediversion of the ureter, a carcinoma at the anastomotic site. Changes in the secretion patterns of sialo- and sulphomucines of the tumor and mucosa are histochemically demonstrated and, together with an appraisal of etiologic factors, discussed. We suggest a careful follow-up of patients with USS, particularly of those performed many years ago.

Adenocarcinoma, Mucinous↗
PubMed1985

Methotrexate analogues. 25. Chemical and biological studies on the gamma-tert-butyl esters of methotrexate and aminopterin.

gamma-tert-Butylaminopterin (gamma-tBAMT), the first example of an aminopterin (AMT) gamma-monoester, was synthesized, and new routes to the known N10-methyl analogue gamma-tert-butyl methotrexate (gamma-tBMTX) were developed. The inhibitory effects of gamma-tBAMT on the activity of purified dihydrofolate reductase (DHFR) from L1210 murine leukemia cells, the growth of L1210 cells and CEM human leukemic lymphoblasts in suspension culture, and the growth of several lines of human squamous cell carcinoma of the head and neck in monolayer culture were compared with the effects of gamma-tBMTX and the parent acids AMT and methotrexate (MTX). Patterns of cross-resistance to gamma-tBAMT, gamma-tBMTX, and AMT among several MTX-resistant cell lines were examined. In vivo antitumor activities of gamma-tBAMT and gamma-tBMTX were compared in mice with L1210 leukemia. While the activity of gamma-tBAMT was very close to that of gamma-tBMTX in the DHFR inhibition assay, the AMT ester was more potent than the MTX ester against cells in culture and against L1210 leukemia in vivo. Only partial cross-resistance was shown against gamma-tBMTX and gamma-tBAMT in cultured cells that were resistant to MTX by virtue of a transport defect or a combination of defective transport and elevated DHFR activity.

Aminopterin↗
PubMed1984

Typing of intermediate filaments in malignant fibrous pleural tumors.

We report two cases of a malignant fibrous pleural tumor, one of the localized type and one of the diffuse type. In both cases, typing of intermediate filaments by immunofluorescence microscopy showed that the tumor cells were positive for vimentin and negative for (cyto)keratin and desmin. This result supports the concept that malignant fibrous pleural tumors do not arise from the (cyto)keratin-positive pleural mesothelium but from the submesothelial fibrous tissue. Thus, instead of the usual term "malignant fibrous mesothelioma", the term "malignant submesothelial fibrosarcoma" should be preferred.

Adolescent↗
PubMed1984

Seasonal changes of steroid concentrations in seminal plasma of a European wild boar.

The influence of season on testicular steroid production as a parameter of testicular function has been studied in a wild boar. Semen was collected once weekly while it served the dummy. In seminal plasma concentrations of the following steroids were determined by radioimmunoassay: unconjugated testosterone, conjugated testosterone, unconjugated total oestrogens, conjugated total oestrogens and 5 alpha-androst-16-en-3-one ('boar-taint steroid'). All steroids showed a clear seasonal pattern with highest concentrations in autumn and early winter and low levels from January to July. Maxima during the rutting season were 10-25 times greater than average values out of season. During a 2-month-period (mid-July until mid-September) libido was abolished and the wild boar refused to mount the dummy. These results indicate that the seasonal variation in testicular steroid production by the wild boar, regulated by photoperiod, are similar to those of the domestic boar.

Androstenes↗
PubMed1983

Compound 48/80 is a selective and powerful inhibitor of calmodulin-regulated functions.

Compound 48/80, a condensation product of N-methyl-p-methoxyphenethylamine with formaldehyde, is composed of a family of cationic amphiphiles differing in the degree of polymerization. Compound 48/80 was found to be a potent inhibitor of the calmodulin-activated fraction of brain phosphodiesterase and red blood cell Ca2+-transport ATPase, with IC50 values of 0.3 and 0.85 micrograms/ml, respectively. However, the basal activity of both enzymes is not at all suppressed by the drug at concentrations up to 300 micrograms/ml. Inhibition of Ca2+ transport into inside-out red blood cell vesicles by compound 48/80 follows a similar pattern in that basal, calmodulin-independent, transport is also not affected by the drug. Kinetic analysis revealed that the stimulation of Ca2+-transport ATPase induced by calmodulin is inhibited by compound 48/80 according to a competitive mechanism. It was demonstrated that the inhibitory constituents of compound 48/80 bind to calmodulin in a Ca2+-dependent fashion. Comparison of the specificity of several anti-calmodulin drugs showed that compound 48/80 is the most specific inhibitor of the calmodulin-dependent fraction of red blood cell Ca2+-transport ATPase that has been described hitherto. In addition, compound 48/80 was found to be a rather specific inhibitor of the calmodulin-induced activation of Ca2+-transport ATPase when compared with the stimulation induced by an anionic amphiphile or by limited proteolysis. Half-maximal inhibition of the activity stimulated by oleic acid or mild tryptic digestion required 8- and 32-times higher concentrations of compound 48/80, respectively, compared with the calmodulin-dependent fraction of the ATPase activity. Moreover, calmodulin-independent systems as rabbit skeletal muscle sarcoplasmic reticulum Ca2+-transport ATPase or calf cardiac sarcolemma (Na+ + K+)-transport ATPase are far less influenced by compound 48/80 as compared with trifluoperazine and calmidazolium. Because of its high specificity compound 48/80 is proposed to be a promising tool for studying calmodulin-dependent processes.

Animals↗