Photochemically enhanced binding of small molecules to the tumor necrosis factor receptor-1 inhibits the binding of TNF-alpha

The binding of tumor necrosis factor alpha (TNF-alpha) to the type-1 TNF receptor (TNFRc1) plays an important role in inflammation. Despite the clinical success of biologics (antibodies, soluble receptors) for treating TNF-based autoimmune conditions, no potent small molecule antagonists have been developed. Our screening of chemical libraries revealed that N-alkyl 5-arylidene-2-thioxo-1,3-thiazolidin-4-ones were antagonists of this protein-protein interaction. After chemical optimization, we discovered IW927, which potently disrupted the binding of TNF-alpha to TNFRc1 (IC(50) = 50 nM) and also blocked TNF-stimulated phosphorylation of Ikappa-B in Ramos cells (IC(50) = 600 nM). This compound did not bind detectably to the related cytokine receptors TNFRc2 or CD40, and did not display any cytotoxicity at concentrations as high as 100 microM. Detailed evaluation of this and related molecules revealed that compounds in this class are "photochemically enhanced" inhibitors, in that they bind reversibly to the TNFRc1 with weak affinity (ca. 40-100 microM) and then covalently modify the receptor via a photochemical reaction. We obtained a crystal structure of IV703 (a close analog of IW927) bound to the TNFRc1. This structure clearly revealed that one of the aromatic rings of the inhibitor was covalently linked to the receptor through the main-chain nitrogen of Ala-62, a residue that has already been implicated in the binding of TNF-alpha to the TNFRc1. When combined with the fact that our inhibitors are reversible binders in light-excluded conditions, the results of the crystallography provide the basis for the rational design of nonphotoreactive inhibitors of the TNF-alpha-TNFRc1 interaction.

Sex differences in the absence of massa intermedia in patients with schizophrenia versus healthy controls

OBJECTIVE

To evaluate sexual dimorphism and incidence of absent massa intermedia (MI), a midline thalamic structure, in patients with schizophrenia and healthy controls.

METHODS

Thin slice magnetic resonance images of the brain were obtained. The presence of MI was determined by viewing sagittal, coronal, and axial planes.

RESULTS

In healthy controls, females had a significantly lower incidence of absent MI (13.56%) compared with males (32.08%). In patients with schizophrenia, there was a sex by diagnosis interaction. Female patients had significantly higher incidence of absent MI (32.76%) compared with their healthy controls (13.56%), whereas the male patients showed no difference in incidence of absent MI compared with their controls.

CONCLUSION

The MI, a sexually dimorphic midline structure, is more commonly absent in female patients with schizophrenia. These results support the growing literature reporting structural aberration of the thalamus, as well as other midline structures in the brains of patients with schizophrenia.

Selective activation of an apoptotic retinoid precursor in macrophage cell lines

Advances in the understanding of the retinoid signaling mechanism has allowed the discovery of highly selective retinoids that activate only one specific receptor class, subtype, or signaling pathway. These novel compounds lack certain of the common retinoid toxicities and therefore suggest promising new approaches for therapeutic applications. We describe here a new compound, 6-[3-(1-adamantyl)-4-hydroxyphenyl]-2-naphthalene carboxylic acid methyl ester (MX84), that is selectively activated in macrophages, leading to killing of only macrophage monocyte type cells in vitro. We provide evidence that MX84 is an inactive precursor that is converted into an active apoptosis-inducing retinoid in macrophages. The macrophage activity is also secreted, and our data suggest that the secreted activity is a phospholipase D type activity. Our observation may lead to the development of molecules that are highly macrophage-selective apoptosis inducers in vivo and that could represent important novel therapeutics against diseases caused by excessive macrophage activity.

4-Hydroxyphenyl retinamide is a highly selective activator of retinoid receptors

Retinoids have shown promise as anti-cancer and cancer preventative agents. All-trans-N-(4-hydroxyphenyl)retinamide (4HPR) belongs to a new group of retinoids that not only inhibit the proliferation of cancer cells but also can induce apoptosis in certain cancer cells. Because of its increased efficacy against cancer cells and its low toxicity it has been entered into a number of clinical trials. However, its mechanism of action is not known, and it had been assumed that it is not a true retinoid. Here we analyze its ability to function as an activator of nuclear retinoid receptors (RARs and RXRs). We observe that, in transactivation assays, 4HPR is a potent transactivator with RARgamma and a moderate activator with RARbeta but is not an activator with RARalpha and RXRalpha. Furthermore, RARgamma-selective transactivation by 4HPR is enhanced on some response elements and reduced on others when compared to natural retinoids. In contrast to transactivation, 4HPR in transrepression assays functions mostly with RARalpha, RARbeta, and RXRalpha. Optimal receptor activation is seen at 4HPR concentrations at which it is a potent growth inhibitor and inducer of apoptosis. We conclude that 4HPR is a highly selective activator of retinoid receptors. We propose that this selective activation of the nuclear receptors is likely to be the basis for its specific biological activities and its favorable pharmaceutical properties.

Novel phosphonium salts display in vitro and in vivo cytotoxic activity against human ovarian cancer cell lines

Phosphonium salts are part of a class of lipophilic cationic molecules that accumulate preferentially in mitochondria and inhibit the growth of human and rodent carcinoma cells in vitro and in animal models. The delocalized cations tested previously such as dequalinium have exhibited considerable cross resistance against multiple drug-resistant cells expressing gp 170. In order to overcome this cross resistance, we have developed two novel phosphonium salts which contain haloalkyl moieties with potential protein alkylating capabilities. 3-Chloropropyltris(4-dimethylaminophenyl)phosphonium chloride (APPCL) and 3-iodopropyltris(4-dimethylaminophenyl)phosphonium iodide (APPI) are more lipophilic than other phosphonium salts described to date. By comparing the 50% inhibitory concentration (IC50) values for the A2780 human ovarian carcinoma parental line to a multiple drug-resistant variant (A2780-DR), the degree of cross resistance (IC50 for A2780-DR/IC50 for A2780 Parental) were found to be 494 for doxorubicin, but only 2.7 for APPCL. Similarly, the degree of cross resistance using a cisplatin-resistant variant (IC50 for A2780-CR/IC50 for A2780 Parental) was 30 for cisplatin, but only 2.2 for APPCL. APPCL is also active in vitro against UCI 101 (IC50 = 80 nM), an ovarian carcinoma line isolated from a patient who had failed chemotherapy with taxol, doxorubicin, and high-dose cisplatin. The cytotoxicity of APPI was comparable to that of APPCL with an IC50 ranging from 16.7 to 83.0 nM for a panel of seven cell lines. When administered intraperitoneally at a total dose of 46 mg/kg over 15 days, APPCL increased the median lifespan of nude mice bearing UCI 101, from a control value of 48.0 to 92.5 days (P < 0.0061). The median survival of the APPI-treated mice was 55 days. A total of 37.5% of the APPCL-treated group and 12.5% of the APPI-treated group were long-term survivors: sacrifice of these mice on Day 180 and subsequent histology showed no evidence of disease. Exposure to APPCL and APPI caused mitochondrial damage to UCI 101 cells at sublethal doses in vitro, as shown by morphological damage observed with transmission electron microscopy. APPCL appears to decrease the uptake of rhodamine 123 by mitochondria, suggesting that mitochondria may be significant targets or initial reservoirs for this agent. In conclusion, APPI and APPCL show promising anticancer activity against a variety of human ovarian carcinoma cell lines warranting further investigation.

Effects of suramin-related and other clinically therapeutic polyanions on protein kinase C activity

The mechanism of the antineoplastic effects of suramin may involve interference with signal transduction, but in general is not well understood. We examined several polyanions to determine their effects on the kinase activity of the protein kinase C (PKC) beta1 and other PKC isoforms. Similar to suramin, a phosphorothioate oligodeoxynucleotide 28-mer homopolymer of cytidine (SdC28) inhibited the phosphatidylserine and Ca2+-dependent phosphorylation of an epidermal growth factor receptor octapeptide substrate. The inhibition by suramin was mixed competitive/noncompetitive with respect to ATP, but uncompetitive with respect to substrate. In contrast, the inhibition by SdC28 was competitive with respect to substrate (Ki = 5.4 microM) and not competitive with respect to ATP. The PKC alpha and beta1 isoforms were inhibited to the same extent with SdC28, while PKC epsilon was not inhibited. SdC28, in the absence of lipid cofactor, stimulated substrate phosphorylation, and in the absence of substrate induced PKC beta1 autophosphorylation. Similar behavior was seen with another polyanion, the polysulfated carbohydrate pentosan polysulfate (polyxylyl hydrogen sulfate). H4, a bis-naphthalene disulfonate tetraanion structurally related to suramin, also inhibited kinase activity but was not competitive with respect to ATP. Dianions closely related to H4 failed to inhibit PKC beta1, suggesting that multiple (>2) negative charges are required. The interactions of polyanions with PKC are complex, and are dependent on the molecular structure of the polyanion, the presence of cofactors, and the PKC isoform.

Non-communicating human and murine carcinoma cells produce alpha 1 gap junction mRNA

The gap junctional communication capacity of six human carcinoma-derived tumorigenic cell lines (pancreatic, pharyngeal and cervical), two murine carcinoma-derived tumorigenic cell lines (bladder-derived and Ehrlich ascites) and one monkey non-tumorigenic cell line (kidney epithelium) have been compared by the dye-transfer technique. All the tumorigenic cell lines were communication defective, while the non-tumorigenic cell line was not. Moreover, six of the eight tumorigenic cell lines expressed a gap junction transcript coding for the connexin 43 (alpha 1). Finally, gap junction plaques were not detected between tumorigenic cells by immunofluorescence staining. Consequently, these data suggest that communication defects in tumorigenic cells may result from either abnormally low levels of translation of junction mRNA or alterations in the assembly of junction protein into cell surface plaques, and not from failure to produce junction transcripts. Furthermore, since induction of alpha 1 expression has been associated with dedifferentiation processes, the presence of alpha 1 mRNA might be a characteristic property of certain tumorigenic cells that originate from cells that do not normally express alpha 1 mRNA.

Mechanism of inhibition of FaDu hypopharyngeal carcinoma cell growth by tetraphenylphosphonium chloride

Cationic phosphonium salts are interesting because they inhibit the proliferation of carcinoma cells more than untransformed epithelial cells in vitro. This differential anti-proliferative effect has been used to identify phosphonium salts and other lipophilic cations that later demonstrated effects in animals. Using 6 carcinoma-derived and 2 untransformed epithelial cell lines, tetraphenylphosphonium chloride (TPP) and other cationic aryl phosphonium salts (CAPS) demonstrated a growth inhibition pattern similar to that of cation rhodamine 123, suggesting that CAPS may inhibit mitochondrial function. We tested this hypothesis for the effect of phosphonium salt TPP on FaDu human hypopharyngeal carcinoma cells. TPP inhibited the proliferation of FaDu carcinoma cells at submicromolar concentrations. Uptake of 3H-TPP by FaDu cells was partially inhibited in medium containing high K+ and fully inhibited by valinomycin in this medium, indicating that TPP accumulates preferentially in mitochondria, and to a lesser extent in the cytoplasm. FaDu cells exposed to TPP exhibited damage to mitochondrial inner membranes, reduced ATP/ADP ratios, decreased oxygen uptake rates and decreased mitochondrial membrane potentials. The treated cells secreted lactate more rapidly than untreated controls and exhibited hypersensitivity to 2-deoxyglucose, an inhibitor of glycolysis. TPP's antimitochondrial effects apparently enhance cytoplasmic glycolysis. In conclusion, TPP inhibits FaDu carcinoma cell growth by inhibiting mitochondrial respiration and ATP synthesis. Cationic phosphonium salts that inhibit carcinoma cell growth through antimitochondrial effects might be used to treat solid tumors without the risk of secondary tumors associated with agents affecting nuclear DNA.

Antineoplastic activity, synergism, and antagonism of triarylalkylphosphonium salts and their combinations

Previously, some of us demonstrated that monocationic phosphonium salt [4-(formylphenyl)methyl]triphenylphosphonium chloride (A) and [4-(hydrazinocarboxy)-1-butyl]tris(4-dimethylaminophenyl)phosph oni um chloride (B) in combination, exhibit inhibitory synergism against ELA mammary carcinoma. Here we show that A + B also exhibits synergism against cultured MB49 murine bladder carcinoma, but antagonism against HT-29 human colon carcinoma. This is probably due to assembly of the hydrazone (C) in situ: synthetic C is a more potent growth inhibitor than either A or B for MB49 and ELA, yet inferior to B for HT-29 cells. A, B, C, [4-(hydrazinocarboxy)-1-butyl]tris(3-tolyl)phosphonium chloride (D) and [4-(methylcarboxy)butyl]triphenylphosphonium chloride (F) selectively inhibit carcinoma growth relative to untransformed cells, most likely due to high carcinoma transmembrane potentials. D and F are tolerated in mice at 100 mg/kg. Intraperitoneal administration of D slows subcutaneous HT-29 xenograft growth by 41 to 59% versus controls in nu/nu mice, and intraperitoneal administration of B slows MB49 xenograft growth by 46 to 57% versus controls and extends the median lifespan of mice bearing ELA breast carcinoma allografts by 86%. Triarylalkylphosphonium salts represent a promising class of antineoplastic cations exhibiting unusual selectivity and synergism.

Cationic drug analysis using matrix-assisted laser desorption/ionization mass spectrometry: application to influx kinetics, multidrug resistance, and intracellular chemical change

Highly sensitive and convenient analysis of intracellular cationic drugs has been achieved by applying matrix-assisted laser desorption/ionization mass spectrometry (MALD-MS). Tetraphenylphosphonium cation was readily identified and quantified (using methyltriphenylphosphonium cation as an internal standard) at subpicomole levels in crude lysate from < 4 x 10(3) FaDu human hypopharyngeal carcinoma cells. A quantitative MALD-MS time course for tetraphenylphosphonium cation accumulation into FaDu cells was comparable to a time course using scintillation counting with tritiated tetraphenylphosphonium. MALD-MS was also capable of demonstrating the reduced accumulation of the cationic drug rhodamine-123 by DoxR MCF7, a multiply drug-resistant human breast adenocarcinoma cell line, relative to the nonresistant parent line MCF7. In addition, MALD-MS was used to follow a chemical reaction inside intact FaDu cells: the formation of a hydrazone (II-51) from benzaldehyde and an acylhydrazide, 5-[tris(4-dimethylaminophenyl)phosphonio]pentanoyl hydrazide (II-25). These results suggest that MALD-MS may provide a rapid and practical alternative to existing methods for the analysis of cationic drugs, toxins, and their metabolites in cells and tissues.

Design, synthesis and biological activity of protaxols

Taxol is a product isolated from the Pacific yew tree (Taxus brevifolia) and is a potent microtubule-stabilizing agent which has recently been approved for treatment of otherwise intractable ovarian cancer. Despite taxol's therapeutic promise, its aqueous insolubility (< 0.004 mg ml-1) hampers its clinical application. Here we report the design, synthesis and biological activity of a series of taxol-releasing compounds (protaxols) with improved pharmacological properties. These prodrugs were designed to increase their aqueous solubility and allow for taxol release under basic or physiological conditions. We demonstrate the stability of these prodrugs at pH < or = 7 and their ability to release taxol in a basic medium. Taxol-like microtubule-stabilizing activity appears after the release of taxol. In vitro these prodrugs have cytotoxic properties against tumour cell lines comparable to those of taxol; moreover, human plasma catalyses the release of active taxol. These protaxols have greater potential as anticancer agents than the parent compounds taxol and taxotere (Fig. 1a).

Derivatives of 4-amino-3,6-disulfonato-1,8-naphthalimide inhibit reverse transcriptase and suppress human and feline immunodeficiency virus expression in cultured cells

We have developed a series of 4-amino-3,6-disulfonato-1,8-naphthalimide (ADSN) derivatives in an attempt to create nontoxic compounds effective against lentivirus infections. The ADSN derivative Lucifer Yellow CH ([N-(hydra zinocarbonyl)amino]-4-amino-3,6-disulfonato-1,8-naphthalimid e) (LYCH) was chosen as a parent compound because of its low toxicity in vivo and in vitro and its tendency to accumulate in monocyte/macrophages, a major reservoir for lentiviruses in vivo. Several ADSN derivatives inhibited reverse transcriptases (RTs) from human immunodeficiency virus type 1 (HIV-1) and feline immunodeficiency virus (FIV). Viral expression in HIV-infected human peripheral blood mononuclear cells was inhibited by noncytotoxic concentrations of two ADSN derivatives, designated A4 (biphenyl-4,4'-dicarboxaldehyde, Lucifer Yellow CH monohydrazone; EC50 = 29 microM after 6 days) and H4 (biphenyl-4,4'-dicarboxaldehyde, Lucifer Yellow CH dihydrazone; EC50 = 5.61 microM). A4 effectively suppressed the expression of FIV in infected Crandall feline kidney fibroblasts (CRFK) at 46.2 microM, reducing the RT levels by 97% after 19 days under conditions allowing direct cell-to-cell transmission of the virus. The viability of drug-treated FIV-infected CRFK cells increased significantly in the presence of A4 relative to the viability of untreated virus-infected cells. In contrast to A4 and H4, LYCH (which lacks the appended aromatic rings characteristic of A4 and H4) had no inhibitory effects on either virus and did not inhibit RT ex vivo. However, flow cytometry studies showed that both A4 and LYCH accumulate in two cell types that can support lentiviral infections: U937 human monocytic leukemic cells that have been induced to differentiate by using tetradecanoyl phorbol acetate, and CRFK cells.

Sensitivity of committed hematopoietic progenitor cells in vitro (BFU-E, CFU-E, CFU-GM) and two human carcinoma cell lines toward rhodamine-123 and phosphonium salt II-41

Lipophilic cationic compounds accumulate more rapidly in the mitochondria of many carcinoma-derived cells than in non-transformed cells, thus leading to their pronounced cytotoxic effects on carcinoma cells. In this report, in order to measure tumoricidal effects vs cytotoxicity to normal hematopoietic progenitors, we studied the sensitivity of committed human hematopoietic cells in vitro and two human carcinoma cell lines (2008 ovary carcinoma cells and HT29 colon cells) toward two such compounds, rhodamine-123 and phosphonium salt II-41. Continuous exposure of human marrow cells to rhodamine-123 or phosphonium salt II-41 for 7 and 14 days produced dose-related inhibition of colony formation of erythroid burst-forming units (BFU-E), erythroid colony forming units (CFU-E), and CFU-granulocyte/macrophage (CFU-GM). The average values of IC50 for several different human bone marrows are approximately 0.9-1.1 microM for rhodamine-123 toward BFU-E, CFU-E and CFU-GM, and 31-38 microM for phosphonium salt II-41 toward the same hematopoietic progenitors. These IC50 values are similar for each type of hematopoietic progenitors. In each case, rhodamine-123 appears to be at least 30-fold more growth suppressive than phosphonium salt II-41 in these in vitro colony assays. In addition, the sensitivity of these hematopoietic progenitors toward these two compounds is comparable to the inhibition of colony formation for the two human carcinoma cell lines. The lack of differences in the sensitivity among the various hematopoietic progenitors in vitro may disagree with previous studies showing there are vast differences in the state of cell cycle for these hematopoietic progenitor cells. However, these observations about the cytotoxicity in vitro can be explained by assuming that the cytotoxicity of these compounds depends on other factors such as differentiation processes, which result in the appearance of many or very active mitochondria. Alternatively, the lack of differences in the sensitivity of the in vitro colony formation can also be attributed to a reported decrease in expression of P-glycoprotein, a multidrug efflux pump, in the differentiating hematopoietic progeny cells.

Combined modality therapy of Hodgkin's disease: 10-year results of National Cancer Institute of Canada Clinical Trials Group multicenter clinical trial

The purpose of this study was to compare four methods of treatment for stage III-IV Hodgkin's disease. Between January 1972 and September 1976, 266 patients with stage IIIB, IVA, and IVB Hodgkin's disease from 21 cancer treatment centers across Canada were registered as eligible; 40 were found to be ineligible. Of the 226 remaining patients, only seven were followed for less than 10 years. All patients received three courses of mechlorethamine, vincristine, procarbazine, and prednisone (MOPP) chemotherapy, which induced a complete response (CR) in 36%; an additional 42% obtained adequate disease control. Patients were randomly assigned to (1) treatment with radiation to the abdomen and mantle (group AX3, 62 patients) or (2) continue their treatment with an additional three courses of MOPP (group A, 105 patients). For the A group, a second randomization took place 3 months later (regardless of status at that time) to (1) no further treatment (AC6, 23 patients), (2) radiotherapy to the abdomen and mantle (AX6, 48 patients), or (3) maintenance chemotherapy at 3-month intervals for 1 year (AC10, 26 patients). The survival of AX3 patients was somewhat better than for the A group, but the difference was not significant (P = .0565). However, there was a significant interaction (P = .0029) between age and treatment, so that among patients less than 30 years of age, the survival of the A group was better, whereas for older patients, treatment with AX3 resulted in improved survival. Age itself remained a significant prognostic factor for survival after controlling for the amount of radiotherapy delivered to the abdomen and the dose intensity of vincristine for the first three courses of chemotherapy. The addition of radiation therapy to MOPP significantly reduced the frequency of nodal relapses. These results suggest that combined modality therapy may be beneficial for some patients with Hodgkin's disease and that age must be carefully considered in interpreting the results of clinical trials in Hodgkin's disease.

A self-assembling protein kinase C inhibitor

Previous studies have described a dicationic anticarcinoma agent that can chemically assemble in situ from monocationic phosphonium salts. The chemical combination of these monocationic precursors in the micromolar concentration range, occurring after their uptake by cells, was probably responsible for their synergistic inhibition of cell growth and for their selective cytotoxicity to Ehrlich ascites murine carcinoma cells relative to untransformed epithelial cells. Here, we report that the dicationic product that forms in this assembly reaction is an in vitro inhibitor of protein kinase C (PKC) alpha and beta 1 isoforms, exhibiting IC50 values of 20.4 microM and 35 microM, respectively. The monocationic precursors proved to be much weaker inhibitors of PKC (IC50 values greater than 200 microM). When PKC is exposed to combinations of the two precursors, the enzymatic activity decreases steadily as a function of time. Using dose-response data and HPLC kinetic studies, we show that when the two precursor compounds are added as a combination to PKC under these conditions, the rate of formation of the inhibitory product follows the observed time course of decline in PKC activity under identical conditions. We discuss the possibility that antiproliferative effects against carcinoma cells of the preformed dication and of the combined monocationic precursors involve inhibition of PKC.

Synergism through direct covalent bonding between agents: a strategy for rational design of chemotherapeutic combinations

Self-assembling chemotherapeutic agents are mixtures of relatively nontoxic precursors that can combine chemically under physiological conditions to form products with greater cytotoxic and/or antimicrobial activity than either of the precursors. Combinations that form products more rapidly in or near the target (tumor, pathogen, virally infected cell) than in normal tissues will exhibit target-selective synergism, thus exhibiting an antitarget selectivity that is greater than the selectivities of the product (e.g., a hydrazone) and of either precursor (e.g., a hydrazine derivative or ketone) used singly. This paper describes the target-selective cytotoxic synergism of a cationic aldehyde (A) and a cationic acylhydrazine (B) containing a triarylalkylphosphonium moiety against Ehrlich ascites carcinoma cells (ELA) in culture, in addition to reviewing previous work on self-assembling cytotoxins. The synergism between A and B is carcinoma selective when the ELA cells (the target) are compared to CV-1, an untransformed African green monkey kidney epithelial line. Like tetraphenylphosphonium and rhodamine 123, which are selectively concentrated in ELA cells relative to CV-1, A, B and the hydrazone C resulting from their reaction are lipophilic delocalized cations that selectively inhibit ELA growth relative to CV-1 growth. The hydrazone C is more growth inhibitory than either A or B for both cell lines. A combination of A with an unreactive analogue of B and a combination of B with an unreactive analogue of A did not synergistically inhibit ELA proliferation. The degree of synergism is greater against the ELA cells than against the CV-1 cells. These data, together with hydrazone formation kinetics, suggest that A and B are both concentrated together selectively inside the ELA due to the transmembrane potentials, reacting inside the ELA cells at a higher velocity than inside the CV-1 cells to form the more growth-inhibitory hydrazone C.

A study of post-orchiectomy surveillance in stage I testicular seminoma

A study of post-orchiectomy surveillance without radiation therapy was done in patients with histologically pure seminoma apparently confined to the testicle. Criteria for study entry included a negative physical examination, chest x-ray, bipedal lymphogram, excretory urogram, abdomino-pelvic computerized tomography scan and serum alpha-fetoprotein. Followup consisted of frequent clinical examination, repeat lymphograms, abdominal computerized tomography scans, chest x-rays and serum markers. The purpose of this study was to determine the percentage of patients cured by orchiectomy alone, percentage who ultimately required therapy for occult metastases beyond the testicle, sites of relapse, factors predictive of relapse, and over-all cure rate and treatment morbidity. Of 81 patients followed for 3 to 43 months (median 19 months) only 3 had relapse at 3, 5 and 18 months after orchiectomy with nonbulky retroperitoneal disease: 1 patient had disease 17 months after salvage infradiaphragmatic radiation therapy, 1 had an increase in beta-human chorionic gonadotropin 11 months after radiation therapy, presumably due to occult nonseminoma, and he is receiving chemotherapy, and 1 has not yet completed treatment. Further followup is necessary to determine ultimate survival, since a risk for later relapse exists. However, to date it does not appear as if the outcome has been compromised when surveillance was applied in place of routine adjuvant radiotherapy.

Environment-selective synergism using self-assembling cytotoxic and antimicrobial agents

Environment-selective synergistic toxicity using combinations of aldehydes and hydrazine derivatives was demonstrated in two different model systems in vitro. Combinations of 5-nitro-2-furaldehyde with semi-carbazide and of 2-hydrazinopyridine with pyridine-2-carboxaldehyde, which can react in situ to form antimicrobial hydrazones, demonstrated greater degrees of synergism against the intracellular pathogen, Salmonella typhimurium, at pH 5 relative to pH 7.4. Combinations are more selectively toxic at pH 5 (vs pH 7.4) than individual precursors and preformed hydrazone products because acid catalysis of hydrazone formation plays a role only for the combinations. A combination of decanal and N-amino, N'-octylguanidine (AOG) exhibited more pronounced synergistic cytolytic activity against erythrocytes in 0% serum than in 1% serum. Serum protein binding of decanal inhibited the formation of the more cytotoxic hydrazone, N-decylidenimino,N'-1-octylguanidine (DIOG), from the less cytotoxic AOG and decanal, and serum protein binding of DIOG prevented this cytotoxin from reaching the cell membrane. Because decanal binding cannot play a role in the cytotoxicity of preformed DIOG, it was less selective for cells in 0% serum than the combination of AOG and decanal. The pH 5 and 0% serum environments represent very simple models for macrophage phagolysosomal compartments and poorly vascularized solid tumor interiors respectively. If environment-selective synergism can be used as a basis for target-selective synergism in other in vitro model systems and in vivo, self-assembling combinations could provide a basis for rational introduction of target-selective synergism into chemotherapeutic drug design.

Self-assembling cytotoxins

Decanal and N-amino-N'-1-octylguanidine (AOG), combined at 28 microM each, mediated erythrocyte lysis within 80 minutes under physiological conditions. By contrast, no lysis was observed after 20 hours with either decanal (56 microM) or AOG (100 microM) alone. The pronounced synergism observed for these chemicals and similar reactive pairs of chemicals is due to the self-assembly of more cytotoxic hydrazones in situ. Decanal and AOG also exhibit synergistic activity against cultured human cells (HeLa) and bacteria (Escherichia coli J96). This synergism may be useful in the design of cytotoxins that would self-assemble selectively from nontoxic precursors within tumors, while sparing normal tissue.

Class III alleles and high-risk MHC haplotypes in type I diabetes mellitus, Graves' disease and Hashimoto's thyroiditis

By typing a large quantity of family-based material for HLA-B, HLA-DR, C4, C2 and factor B, we were able to derive four-gene complement haplotypes (C4A, C4B, C2, BF) and six-gene MHC haplotypes (HLA-B, complement, HLA-DR). Fourteen six-gene MHC haplotypes showed linkage disequilibrium but exact frequencies could not be determined because it was not always possible to assign null C4 alleles in families where null genes were not clearly seen to segregate. Comparison of unrelated type I diabetes, Graves' disease and Hashimoto's thyroiditis patients with healthy unrelated controls revealed the following MHC allele associations: C4B*3, HLA-DR3 and HLA-DR4 with type I diabetes; BF*F1 and HLA-DR3 with Graves' disease; HLA-DR4 with Hashimoto's thyroiditis. By typing families of type I diabetes and Graves' disease patients we were able to derive two high-risk DR3+ MHC haplotypes for both type I diabetes and Graves' disease. These are HLA-B8 C4A*Q0 C4B*1 BF*S HLA-DR3 and HLA-B18 C4A*3 C4B*Q0 BF*F1 HLA-DR3, and these haplotypes account for most of the associations between these diseases and HLA-DR3. The MHC haplotype HLA-B15 C4A*3 C4B*3 BF*S HLA-DR4 also carries high risk for type I diabetes in this group of patients. Our data suggest that other DR4+ haplotypes, probably containing C4A*3 C4B*1, carry increased risk for type I diabetes whereas haplotypes containing DR4 and C4 C4A*3 C4B*Q0 do not. Our phenotype data suggest that DR4 in Hashimoto's thyroiditis is frequently associated with HLA-B44, C4A*3, C4B*1 and BF*S.