Metabolic effects of mealtime insulin lispro in comparison to glibenclamide in early type 2 diabetes.

The efficacy and safety of the preprandial injection of insulin lispro was compared with the oral administration of glibenclamide in patients with early type 2 diabetes. In this open-label, multicenter study, 143 patients with a glucagon-stimulated increase in C-peptide of at least 0.4 nmol/L were randomized to receive preprandial insulin lispro (LP) or glibenclamide (GB) for 26 weeks. Seventy-five patients received LP (51 male/24 female; age 40 to 70 years, duration of diabetes 4.4 +/- 2.9 years) and 68 patients received GB (39 male/29 female; age 39 to 70 years; duration of diabetes 4.3 +/- 3.4 years). After 12 weeks, mean 90 minute blood glucose excursions were 0.9 +/- 1.0 mmol/L for LP and 1.8 +/- 1.2 mmol/L for GB (p < 0.0001). After 24 weeks, mean blood glucose excursions were 1.0 +/- 1.1 mmol/L for LP and 1.7 +/- 1.2 mmol/L for GB (p = 0.002). Body weight decreased slightly from 87.2 +/- 2.3 to 86.5 +/- 12.2 kg in the LP group and increased from 84.1 +/- 13.7 to 84.4 +/- 13.3 kg in the GB group. LP versus GB induced changes from baseline to endpoint in fasting C-peptide (nmol/L), proinsulin and insulin levels (pmol/L) were - 0.2 +/- 0.4 versus - 0.1 +/- 0.6 (p = 0.04), - 11.2 +/- 26.0 versus - 1.1 +/- 17.3 (p = 0.03), and - 27.8 +/- 147.4 versus + 32.6 +/- 286.2 (not significant), respectively. HbA 1c at baseline was 7.5 +/- 1.0 % for LP and 7.7 +/- 1.2 % for GB and did not change significantly in either group during the investigation. No significant difference was observed between the groups with respect to hypoglycemic episodes. Treatment with LP improved postprandial blood glucose control more than GB without increasing body weight or hypoglycemic episodes. In addition, use of LP was associated with a decrease in fasting C-peptide and proinsulin levels, suggesting a potential down regulation of endogenous insulin production and improved proinsulin processing efficiency.

Effect of long-term exposure to insulin lispro on the induction of antibody response in patients with type 1 or type 2 diabetes.

OBJECTIVE: To determine the long-term effects of insulin lispro on inducing lispro-specific, insulin-specific, and cross-reactive (reactive with both insulin lispro and human insulin) antibodies. RESEARCH DESIGN AND METHODS: A multinational, multicenter combination of controlled and noncontrolled, open-label studies of 4.5 years' duration was designed to evaluate the long-term immunologic profile of subcutaneously administered insulin lispro. A total of 1,221 patients (men and women; 12-81 years of age) with type 1 or type 2 diabetes were enrolled. Circulating anti-insulin antibodies were measured using radioimmunoassays. RESULTS: Insulin-specific and lispro-specific antibody responses were within the background noise levels of the assays. Significant elevations of antibody were confined to a cross-reactive antibody response. Antibody levels resulting from prior exposure to long- and short-acting insulins changed little after transfer to insulin lispro and remained within or near the baseline levels. De novo exposure to insulin lispro resulted in increases in cross-reactive but not insulin- or lispro-specific antibody levels. Cross-reactive insulin antibodies developed more readily in patients with type 1 diabetes than in those with type 2 diabetes. Long-term antibody responses tended to decrease over time and returned to baseline or near-baseline levels by the end of the long-term studies. No evidence of an anamnestic antibody response could be found in individuals treated intermittently with insulin lispro. CONCLUSIONS: The immunogenic profile of patients treated with insulin lispro was comparable to that of patients treated with recombinant human insulin. Inductions of significant levels of specific or cross-reactive antibodies were not observed in patients who had received insulin previously. No significant antibody-dependent increases in insulin dosage requirements were noted in these patients. The incidence of insulin allergy was not different from that in patients treated with recombinant regular human insulin.

In situ stimulation of topoisomerase II-induced cleavage sites in the c-myc protooncogene by antitumor agent pMC540 is associated with gene expression.

The antitumor activity of pMC540 has been shown to be mediated via its interaction with topoisomerase (Topo) II eventually leading cells into apoptosis. This agent was also found to down regulate the expression of the c-myc oncogene in L1210 leukemia cells. To investigate the possibility that damage within select genomic regions may contribute to the antiproliferative activity of pMC540, differential damage in regions surrounding the c-myc locus as well as other select genes was determined. Southern blot hybridization experiments show that pMC540 treatment induces in situ DNA cleavage products in the 5' end of the c-myc oncogene of L1210 leukemia cells. In cells pre-treated with 50 microM ethidium bromide, an inhibitor of the Topo II-dependent DNA cleavage, a subsequent treatment with pMC540 failed to induce DNA cleavage, suggesting that the cleavage activity of pMC540 was Topo II dependent. pMC540-induced cleavage does not appear to correlate with the over-expression of the c-myc oncogene in these cells as another over-expressed gene c-myb was not affected. Thus, it is proposed that the c-myc gene may be a preferred target for pMC540 may mediated antiproliferative activity.

Relationship of mitochondrial function and cellular adenosine triphosphate levels to pMC540 and merodantoin cytotoxicity in MCF-7 human breast cancer cells.

In previous studies we have reported that preactivated merocyanine 540 (pMC540) and its chemically synthesized isolates merocil and merodantoin mediate their preferential cytotoxicity towards certain types of malignant cells including human breast cancer cells in vitro and in vivo. The mechanism of cytotoxic action appears to be, in part, via initial interaction with topoisomerase II leading to apoptosis. To further build upon these findings we now show that pMC540 and merodantoin disrupt mitochondrial morphology and function in intact MCF-7 human breast cancer cells as seen by their causing the release of rhodamine 123 from prestained cells, a rapid reduction in ATP levels, inhibition of succinate dehydrogenase activity and oxygen consumption. These data suggest that mitochondria may also be an important target for the cytotoxic action of pMC540 and merodantoin mediated through disruption of the energy balance.

Correlation between DNA topoisomerase II activity and cytotoxicity in pMC540 and merodantoin sensitive and resistant human breast cancer cells.

We have shown previously that preactivated merocyanine 540 (pMC540) and merodantoin appear to mediate their cytotoxic effects via interaction with Topo II. Now, we demonstrate a correlation between DNA Topo II activity and drug-sensitive (MCF-7) and -insensitive (MDA-MB-231) breast cancer cell lines. Further studies indicate that MDA-MB-231 cells are insensitive to the cytotoxic and DNA cleavage effects of pMC540 and merodantoin. This loss of sensitivity is not associated with M(r) 170,000 P-glycoprotein over expression. However, in drug insensitive cells, the Topo II catalytic activity in crude nuclear extract was reduced two- to-three-fold and in cellular extracts was virtually absent as determined by decatenation of kDNA. Topoisomerase I activities appeared similar in extracts from MCF-7 and MDA-MB-231 cell lines. Drug-induced DNA cleavage was reduced two-to-threefold in nuclear extracts from MDA-MB-231. m-AMSA was more effective in inhibiting the decatenation activity in the nuclear extracts from MDA-MB-231 as compared to MCF-7 cells. Western blot analysis of whole-cell lysates revealed undetectable immunoreactivity of Topo II in the drug-insensitive cells. These data indicate that insensitivity of MDA-MB-231 to pMC540 and merodantoin is in part due to the reduced drug-induced formation of the cleavage complex and Topo II (170 kD) enzyme content.

Growth inhibitory effects of pMC540 and merodantoin on established MCF-7 human breast tumor xenografts.

The effect of preactivated merocyanine 540 (pMC540) and one of its chemically synthesized active isolate merodantoin on established human MCF-7 human breast tumor xenografts was investigated. Preactivation is a novel photochemical method for the production of chemotherapeutic compounds that exert their biological effects independent of light. These compounds thus produced, are cytotoxic to human breast cancer cells in vitro and in vivo but only minimally cytotoxic towards normal cells. Nude mice bearing established breast tumors (with or without exogenous estradiol) received injections of pMC540 (250 mg/kg) or merodantoin (75 mg/kg) with or without concurrent treatment with tamoxifen. Treatment with pMC540 and merodantoin caused a 74% and 84% inhibition of tumor growth respectively. Combination of these drugs with tamoxifen did not produce a significant enhancement of growth inhibition. In the absence of exogenous estradiol, identical treatment with pMC540 and merodantoin resulted in 41% and 25% inhibition of tumor growth respectively. Both agents caused a significant (59%) inhibition of growth of estrogen independent human breast tumors established from MDA-MB-435 cells. These results show that photochemically generated novel compounds in pMC540 are effective in suppressing the growth of established human MCF-7 and MDA-MB-435 breast tumor xenografts.

Topoisomerase II-dependent novel antitumor compounds merocil and merodantoin induce apoptosis in Daudi cells.

Three photoproducts of merocyanine 540 have been isolated, chemically characterized and synthesized. Two of these photoproducts, merocil and merodantoin, show significant antitumor activity in vitro and in vivo while demonstrating minimal toxicity to normal cells and tissues. Treatment of lymphoma cells with these compounds resulted in a rapid decline in macromolecular synthesis, DNA fragmentation inhibitable by actinomycin D and cycloheximide, and a marked rise in intracellular calcium. In vitro analysis revealed that activity of these compounds is dependent on topoisomerase II. These results are discussed in terms of the novel class of topoisomerase II-dependent compounds for potential use in chemotherapy.

In vitro and in vivo growth suppression of MCF-7 human breast cancer by novel photoproducts and tamoxifen.

BACKGROUND: Preactivation is a novel photochemical method for the production of chemotherapeutic compounds that exert their biologic effects independent of light. The compounds that are produced, preactivated merocyanine 540 (pMC540) and merodantoin, are cytotoxic to cultured human breast cancer cells but are only minimally cytotoxic toward normal cells. Their effects against breast cancer have not been studied in vivo. METHODS: Estrogen-stimulated human MCF-7 breast adenocarcinoma cells were grown as solid tumors in athymic carrier mice. Animals bearing defined sizes of subcutaneously transplanted solid breast tumors received injections of pMC540 (250 mg/kg) with or without concurrent treatment with tamoxifen. Growth inhibitory effects of merodantoin (N,N'-dibutyl-2-thio-4,5-imidazolidion) on the breast tumor growth were determined. RESULTS: Direct injection of established tumors with eight doses of pMC540 (250 mg/kg) administered on alternate days resulted in significant tumor regression (P = 0.002). In three of seven animals, palpable tumors could not be detected after this treatment (16 days). Treatment through intramuscular injections (20 doses) with pMC540 (250 mg/kg) also caused a significant suppression of tumor area (P = 0.004; P = 0.0882; P = 0.0903) and a marginally significant suppression of tumor weight and volume, respectively. Combined treatment with tamoxifen and pMC540 (100 mg/kg) caused a 67% suppression of breast tumor growth. Treatment with 20 doses of merodantoin (75 mg/kg) suppressed the growth of breast tumors by 98%. CONCLUSION: To the authors' knowledge, these results show for the first time that photochemically generated novel compounds in pMC540 alone and in combination with tamoxifen are effective in suppressing in vivo growth of xenografted human MCF-7 breast tumors.

Effects of preactivated MC540 in the treatment of lymphocytic plasmacytic stomatitis in feline leukemia virus and feline immunodeficiency virus positive cats.

Photoactive compounds and drugs are used therapeutically as antibacterial, antiviral and antitumor agents. This report examines the use of a photoactive compound, preactivated merocyanine 540 (pMC540), in the treatment of stomatitis in two cats that are both feline immunodeficiency virus (FIV) positive. One of the cats was also feline leukemia virus (FeLV) positive. Dramatic short term improvement is reported with the dosage regimen and complications.

Biodistribution and toxicity of photoproducts of merocyanine 540.

Light-activated merocyanine 540 (pMC540) has been shown in our earlier studies to be effective against certain types of tumor cells and viruses, including human immunodeficiency virus (HIV-1). To test the potential extracorporeal and systemic use of pMC540, its toxicity was investigated in DBA/2 mice, pigs, and dogs. The lethal dose in DBA/2 mice after an i.p. injection was 370 mg/kg, and the 50% lethal dose (LD50) was 320 mg/kg; however, following i.v. administration, the lethal dose and the LD50 dose were 240 and 160 mg/kg, respectively. Tritium-labeled MC540 was used to study the biodistribution of pMC540 in DBA/2 mice. Almost 70% of the injected radioactivity was excreted within 6 h of injection. After 1 week, the pMC540 was almost completely cleared, with only 1.89% of the activity remaining, and had a plasma half-life of 23 h. Pigs injected with an accumulated dose of 10 mg/kg and followed for a period of 30 days did not show adverse signs of toxicity as monitored by SMAC-28 analysis, CBC profile, and blood-coagulation studies. A dog injected with a single dose of 20 mg/kg showed induction of the hepatic enzymes glutamic oxaloacetic transaminase (AST) and glutamic pyruvic transaminase (AST); however, serum levels of gamma-glutamyl transpeptidase (GGT) remained unchanged. The data presented herein may serve to identify certain drug-dose limitations in the systemic use of pMC540.

Preactivation: a new concept for generation of photoproducts for potential therapeutic applications.

Controlled exposure of photoactive compounds to light prior to their use in biological targets results in the formation of heretofore unknown photoproducts. This process of photoproduct generation, termed preactivation, renders the photoactive compound capable of systemic use without further dependence on light. We have demonstrated that preactivated Merocyanine and preactivated Photofrin-II possess significant antitumor and antiviral activity against certain tumor cells and viruses, while under identical conditions normal cells and tissues are minimally affected. Thus, the preactivation procedure may represent a promising therapeutic modality for controlling systemic malignancies and viral infections.

Protein damage by photoproducts of merocyanine 540.

Exposure of certain photoactive dyes to light prior to their use in biological systems (preactivation) has been shown to result in formation of long-lived cytotoxic photoproducts. The cytotoxic species responsible for the biological activity of preactivated merocyanine 540 (pMC540) appears to be a hydroperoxide generated by oxidation of ground-state dye by singlet molecular oxygen, formed via energy transfer from triplet excited-state dye to oxygen. A positive correlation (r = .93) exists between the levels of hydroperoxides and percent of tumor cells killed upon exposure to pMC540. Exposure of bovine serum albumin (BSA) (0.5 mg/mL) to pMC540 (0.2 mg/mL-1 mg/mL) results in loss of tryptophan fluorescence and 345 nm emission, suggesting a probable role of either hydroxyl (.OH) or .OH + superoxide (O2-). Polyacrylamide gel electrophoresis indicates fragmentation of treated BSA. Aggregation of pMC540-treated BSA is not detected. Bityrosine production is not observed. A dose-dependent decrease in BSA solubility is observed in treated samples, suggesting an increase in hydrophobicity. Amino acid analysis of BSA treated with pMC540 shows loss of some amino acids residues. The data presented here suggest that photoproducts of MC540 derived via the process of preactivation may mediate their effect (at least in part) by reactive oxygen species.

Inactivation of viruses with photoactive compounds.

The transmission of human immunodeficiency virus (HIV-1) and other enveloped virus by blood transfusion is a major concern. Photosensitive dyes such as hematoporphyrin derivative (HPD), dihematoporphyrin ether (DHE), benzoporphyrin derivatives (BPD), extended ring porphyrins, sapphyrins and texaphyrins, and various cyanines were used with viral cultures to test the feasibility of using those light-excitable dyes to kill virus. A photodynamic flow cell was used to irradiate viral suspensions or viral infected cells in culture media or in whole blood. Herpes virus (HSV-1) was used to screen compounds. Effective compounds were subsequently tested for their ability to kill HIV-1, CMV, and SIV in culture medium and in blood and proved to effectively kill free virus and infected cells at significant viremias. Irradiation was achieved with a filtered xenon light source and/or tunable dye laser. Concentrations of dyes at 10 times viral kill dose were irradiated in blood which was tested for damage to erythrocytes (RBC), platelets, and blood proteins. No damage to RBC, complement factors, and immunoglobulins was evident immediately after photodynamic treatment. Platelet condition is minimally modified with time. Photodynamic treatment of blood appears to be a feasible means of eradicating virus and some protozoans from blood.

Preactivated merocyanine 540 inactivates HIV-1 and SIV: potential therapeutic and blood banking applications.

A novel photodynamic procedure employing "preactivated" merocyanine 540 (P-MC 540) was assessed for its effectiveness in inactivating human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency virus (SIV). Merocyanine 540 was preactivated by exposure to laser light at 514 nm prior to addition to viruses or infected cells. Treatment of cell-free HIV-1 and SIV with P-MC 540 significantly reduced their ability to infect and kill MT-4 cells in vitro. Preactivated MC 540 treatment of in vitro HIV-1-infected human peripheral blood mononuclear cells also decreased viral infection as assessed by a reduction in the amounts of HIV-1 p24 antigen produced and in the number of HIV-1 antigen-positive cells. Indirect immunofluorescence assays of target cell binding showed that treatment of cell-free HIV-1 and SIV with P-MC 540 interfered with their ability to bind to CD4+ target cells. Immunoprecipitation with a monoclonal anti-CD4 antibody of P-MC 540-treated and radiolabeled HIV-1 incubated with soluble recombinant CD4 (srCD4) resulted in coprecipitation of HIV-1 viral p17 and p24 core antigens with the envelope gp120/CD4 complex, suggesting cross-linking of viral components. However, no significant decrease in the binding of treated HIV-1 to srCD4 was observed. Because of the antitumor and antiviral properties of P-MC 540, this photopreactivation procedure may represent a promising therapeutic means for controlling systemic malignancies and viral infections, and for eliminating viral contaminants in biological fluids. Unlike conventional phototherapy, this procedure does not require the delivery of light energy at the target sites following binding of the photosensitizing compounds.

Photochemistry of merocyanine 540: the mechanism of chemotherapeutic activity with cyanine dyes.

The photophysical properties of merocyanine 540 have been determined in methanol solution over a modest temperature range. Triplet state population is inefficient (the limiting triplet quantum yield being 0.25) due to rapid isomerization of the central double bond from the first excited singlet state. Activation energies have been measured for isomerization from the excited singlet state (20 kJ mol-1) and for conversion of the resultant cis-isomer back to the original trans-form (63 kJ mol-1), both processes involving formation of a twisted species. The dye is easily oxidized to give an unstable adduct which decomposes on the sub-ms timescale. Reversible redox chemistry occurs upon excitation in the presence of electron acceptors. These various observations are discussed in terms of the known chemotherapeutic activity of MC540 and it is concluded that the most probable mechanisms for cytotoxicity involve either local thermal disruption of cell membranes or in situ photogeneration of toxins derived from breakdown of the dye.

Synergy between preactivated photofrin-II and tamoxifen in killing retrofibroma, pseudomyxoma and breast cancer cells.

Exposure of photoactive compounds to light prior to their use in biological systems (preactivation) results in the generation of tumour cell specific metastable cytotoxic species that are no longer dependent on the light energy. Thus, preactivation renders the photoactive compounds suitable for systemic use. We have examined the in vitro effect of preactivated photofrin-II and tamoxifen in retroperitoneal fibroma, pseudomyxoma and male breast carcinoma cell lines. These cells were found to be non-responsive to tamoxifen and were negative for oestrogen receptors. Incubation of these cells with 0.5 microgram/ml preactivated photofrin-II and tamoxifen (less than 10(-6) mol/l) resulted in a significantly enhanced (P less than 0.001) inhibition of DNA synthesis compared with either agent alone. This synergistic effect between tamoxifen and preactivated photofrin-II was determined by multiple drug effect analysis. Treatment of cells with preactivated photofrin-II did not cause the increased expression of oestrogen receptors. These observations suggest that a combination of antihormonal drugs with preactivated compounds may be of clinical value.

In vitro photodynamic activity of kryptocyanine.

The photophysical properties of 1,1'-diethyl-4,4'-carbocyanine chloride (kryptocyanine) have been measured in methanol solution and for the dye bound to human serum albumin, incorporated in neutral micelles and after incubation with leukemia cells. In all cases, it is found that formation of the triplet state of the dye occurs with low efficiency and that illumination of the dye under aerobic conditions does not produce significant yields of O2(1 delta g). Instead, the only efficient photoprocess involves rapid internal conversion from the first excited singlet state to the ground state, probably via isomerization of the polymethine sequence. These findings are discussed with respect to the demonstrated ability of kryptocyanine to photodestroy leukemic cells.

Tumor cell specific dark cytotoxicity of light-exposed merocyanine 540: implications for systemic therapy without light.

Merocyanine 540 (MC540) was activated by exposure to 514 nm laser light. The light-exposed MC540 was then mixed (in the dark) with tumor cells and normal cells to determine the antiproliferative activity. Treatment with light-exposed MC540 resulted in 70-90% tumor cell kill from different cell lines, while 85% of the normal human mononuclear cells and 41% of the granulocyte-macrophage colony forming cells (CFU-GM) survived the treatment. The observed cytotoxicity of light-exposed MC540 to the tumor cells was significantly greater (P less than 0.05) than the native MC540. Results show that tumor cell specificity and cytotoxicity in the light activated dye are retained for at least 30 days. Addition of catalase and mannitol decreased the cell kill by light-exposed compound, indicating that the observed effects may be due to reactive oxygen species. The electron micrographs of treated cells show a progression towards apoptosis in a majority of the cells. The life span of L1210 leukemia-bearing mice treated with light-exposed MC540 was prolonged compared to the untreated and native MC540 treated mice. High pressure liquid chromatography (HPLC) analysis of light-exposed material shows a completely different elution profile compared to the native compound. Results presented here show that light-exposed photoactive compounds can be used without further illumination and may have significant clinical applications. Photoactive mechanisms dependent on events other than short-lived transient elevations in energy or singlet oxygen must be invoked to explain the reported cytotoxicity.

Preactivation--a novel antitumour and antiviral approach.

Merocyanine 540 was activated by exposure to 514 nm laser light. This preactivated merocyanine 540 was then mixed (in the dark) with tumour cells, normal cells and envelope viruses to assess its antiproliferative activity. This treatment resulted in 70-90% killing of tumour cells from different cell lines while 85% of normal human peripheral blood mononuclear cells survived the treatment. However, not all types of tumour cells were affected. Preactivated merocyanine 540 was also effective in virtually completely inactivating cell-free herpes simplex and human immunodeficiency viruses. Preactivated photoactive compounds can exert their toxic effects in the dark without further dependence on light and may have potential systemic use.