The antiferroptotic effect of indigo on ulcerative colitis

The protective effect of indigo on intestinal epithelial cells remains unclear. Yokote Akihito et al. preliminarily investigated the anti-ferroptosis effect of indigo in inflammatory bowel disease. Here, we further discuss and evaluate the role of indigo based on the results.

Ferroptosis in the colon epithelial cells as a therapeutic target for ulcerative colitis

BACKGROUND

Ferroptosis, a type of programmed cell death triggered by oxidative stress, was suspected to play a role in ulcerative colitis. Indigo naturalis is highly effective against ulcerative colitis, but its mechanism is unclear. This study found that indigo naturalis treatment suppressed ferroptosis.

METHODS

We analyzed 770 mRNA expressions of patients with ulcerative colitis. Suppression of ferroptosis by indigo naturalis treatment was shown using a cell death assay. Malondialdehyde levels and reactive oxygen species were analyzed in CaCo-2 cells treated with indigo naturalis. Glutathione metabolism was shown by metabolomic analysis. Extraction of the ingredients indigo naturalis from the rectal mucosa was performed using liquid chromatograph-mass spectrometry.

RESULTS

Gene expression profiling showed that indigo naturalis treatment increased antioxidant genes in the mucosa of patients with ulcerative colitis. In vitro analysis showed that nuclear factor erythroid-2-related factor 2-related antioxidant gene expression was upregulated by indigo naturalis. Indigo naturalis treatment rendered cells resistant to ferroptosis. Metabolomic analysis suggested that an increase in reduced glutathione by indigo naturalis. The protein expression of CYP1A1 and GPX4 was increased in the rectum by treatment with indigo naturalis. The main ingredients of indigo naturalis, indirubin and indigo inhibited ferroptosis. Indirubin was detected in the rectal mucosa of patients with ulcerative colitis who were treated with indigo naturalis.

CONCLUSIONS

Suppression of ferroptosis by indigo naturalis in the intestinal epithelium could be therapeutic target for ulcerative colitis. The main active ingredient of indigo naturalis may be indirubin.

Patent blue versus methylene blue and indigo carmine as a better dye for chromodiscography: in vitro staining efficacy and cytotoxicity study using bovine coccygeal intervertebral discs

BACKGROUND CONTEXT

Chromodiscography is an integral part of full-endoscopic discectomy (FED), comprising ordinary discography with radiopacity produced by contrast medium and intradiscal stain for visualizing annular defects in the endoscopic field. Nevertheless, concerns remain about the cytotoxicity of the stains used. The study of their staining efficacy is also lacking.

PURPOSE

To evaluate the feasibility of methylene blue, patent blue, and indigo carmine for intradiscal injection, investigate the effectiveness of each dye, and define critical concentration with adequate staining efficacy and tolerable cytotoxicity for use in chromodiscography during FED.

STUDY DESIGN

An experimental in vitro study.

METHODS

Dye stock solutions were prepared from powder. The stock was diluted with culture medium or balanced saline and used for cytotoxicity or intervertebral disc staining assays, respectively. Bovine tails were obtained from the local slaughterhouse and functional spine units of intervertebral discs were acquired by transverse incision at the disc level. Each disc was punctured over the posterolateral aspect using a surgical knife to simulate an annular defect. The intradiscal injection was performed with each dye at different concentrations using a 22G needle from the contralateral aspect of the punctured site. Staining efficacy was quantified using ImageJ software. Primary cells of bovine tails were cultivated in each dye at different concentrations. Cytotoxicity was assessed 24 hours after stain exposure using the CCK-8 toxicity assay.

RESULTS

Staining efficacy and cytotoxicity were proportional to the concentration of tested dyes. Lower limits of concentration producing significant staining efficacy of indigo carmine, methylene blue, and patent blue were 0.25 mg/mL, 0.25 mg/mL, and 0.05 mg/mL, respectively. Compared with controls, concentrations showing significant toxicity for indigo carmine, methylene blue, and patient blue were 1 mg/mL, 0.5 mg/mL, and 2.5 mg/mL, respectively.

CONCLUSIONS

Patent blue can serve as a more suitable tissue stain than either indigo carmine or methylene blue due to the widest range of tradeoff concentration within 0.05 to 2.5 mg/mL.

CLINICAL SIGNIFICANCE

Patent blue with the characteristic of good staining efficacy and lower cytotoxicity may be a promising option for chromodiscography during FED.

Antioxidant effects of bis-indole alkaloid indigo and related signaling pathways in the experimental model of Duchenne muscular dystrophy

Indigo is a bis-indolic alkaloid that has antioxidant and anti-inflammatory effects reported in literature and is a promissory compound for treating chronic inflammatory diseases. This fact prompted to investigate the effects of this alkaloid in the experimental model of Duchenne muscular dystrophy. The main aim of this study was to evaluate the potential role of the indigo on oxidative stress and related signaling pathways in primary skeletal muscle cell cultures and in the diaphragm muscle from mdx mice. The MTT and Neutral Red assays showed no indigo dose-dependent toxicities in mdx muscle cells at concentrations analyzed (3.12, 6.25, 12.50, and 25.00 μg/mL). Antioxidant effect of indigo, in mdx muscle cells and diaphragm muscle, was demonstrated by reduction in 4-HNE content, H2O2 levels, DHE reaction, and lipofuscin granules. A significant decrease in the inflammatory process was identified by a reduction on TNF and NF-κB levels, on inflammatory area, and on macrophage infiltration in the dystrophic sample, after indigo treatment. Upregulation of PGC-1α and SIRT1 in dystrophic muscle cells treated with indigo was also observed. These results suggest the potential of indigo as a therapeutic agent for muscular dystrophy, through their action anti-inflammatory, antioxidant, and modulator of SIRT1/PGC-1α pathway.

Immunomodulatory drug discovery from herbal medicines: Insights from organ-specific activity and xenobiotic defenses

Traditional herbal medicines, which emphasize a holistic, patient-centric view of disease treatment, provide an exciting starting point for discovery of new immunomodulatory drugs. Progress on identification of herbal molecules with proven single agent activity has been slow, in part because of insufficient consideration of pharmacology fundamentals. Many molecules derived from medicinal plants exhibit low oral bioavailability and rapid clearance, leading to low systemic exposure. Recent research suggests that such molecules can act locally in the gut or liver to activate xenobiotic defense pathways that trigger beneficial systemic effects on the immune system. We discuss this hypothesis in the context of four plant-derived molecules with immunomodulatory activity: indigo, polysaccharides, colchicine, and ginsenosides. We end by proposing research strategies for identification of novel immunomodulatory drugs from herbal medicine sources that are informed by the possibility of local action in the gut or liver, leading to generation of systemic immune mediators.

Optimization of dye solutions for detecting damaged pancreatic tissues during islet isolation procedures

We previously reported that dye was effective to prevent the leakage of enzyme solutions from pancreatic glands during an islet isolation procedure. However, the dye used for islet isolation has not yet been optimized. In this study, we focused on pyoktanin blue (PB), diagnogreen (DG), and indigo carmine (IC) as potential candidates among clinically established dyes. A serial dilution assay was performed to determine minimal effective concentrations of each dye for detecting damaged pancreatic tissues. According to the outcome of serial dilution assays, double minimum effective concentrations of each dye were used for in vitro toxicity assays on islets and used in the isolation procedure to investigate whether they adversely affect islet isolation efficiency. The evaluations included islet yield, ADP/ATP, ATP/DNA, glucose stimulation test, and insulin/DNA assays. Islet viability cultured with PB contained medium was significantly lower than the other dyes. DG and IC appeared to be non-toxic to the islets. In isolation experiments, the islet yield in the DG group was considerably lower than that in the Control group, suggesting that DG might inhibit enzyme activity. The present study demonstrates that IC could be a promising candidate for an effective dye to detect damaged pancreatic tissues without affecting the enzyme activity and islet quality.

Indigo Naturalis ameliorates murine dextran sodium sulfate-induced colitis via aryl hydrocarbon receptor activation

BACKGROUND

Indigo Naturalis (IN) is used as a traditional herbal medicine for ulcerative colitis (UC). However, the mechanisms of action of IN have not been clarified. We aimed to evaluate the efficacy of IN for ameliorating colonic inflammation. We further investigated the mechanisms of action of IN.

METHODS

Colitis severity was assessed in dextran sodium sulfate-induced colitis and trinitrobenzene sulfonic acid-induced colitis models with or without the oral administration of IN or indigo, which is a known major component of IN. Colonic lamina propria (LP) mononuclear cells isolated from IN-treated mice were analyzed with quantitative reverse transcription polymerase chain reaction (qRT-PCR) and flow cytometry. LP and splenic mononuclear cells cultured in vitro with IN or indigo were also analyzed. The role of the candidate receptor for indigo, the aryl hydrocarbon receptor (AhR), was analyzed using Ahr-deficient mice.

RESULTS

Colitis severity was significantly ameliorated in the IN and indigo treatment groups compared with the control group. The mRNA expression levels of interleukin (Il)-10 and Il-22 in the LP lymphocytes were increased by IN treatment. The treatment of splenocytes with IN or indigo increased the expression of anti-inflammatory cytokines and resulted in the expansion of IL-10-producing CD4+ T cells and IL-22-producing CD3-RORγt+ cells, but not CD4+Foxp3+ regulatory T cells. The amelioration of colitis by IN or indigo was abrogated in Ahr-deficient mice, in association with diminished regulatory cytokine production.

CONCLUSIONS

IN and indigo ameliorated murine colitis through AhR signaling activation, suggesting that AhR could be a promising therapeutic target for UC.

Modern industrial and pharmacological applications of indigo dye and its derivatives--a review

Plant sources, chemical properties, bioactivities, as well as the synthesis of indigo dye and its derivatives, are reviewed in this paper. These compounds were chosen because of their significant benefits and scope of application as both coloring agents in the textile industry and as pharmacologically active natural products. Their use in traditional chinese medicine (TCM) has directed the attention of European researchers and medical doctors alike. The preparation of indigoferous plants--Indigo naturalis is currently about to be introduced into the European Pharmacopoeia.

An in vitro study of the antimicrobial effects of indigo naturalis prepared from Strobilanthes formosanus Moore

Indigo naturalis is effective in treating nail psoriasis coexisting with microorganism infections. This study examines the antimicrobial effects of indigo naturalis prepared from Strobilanthes formosanus Moore. Eight bacterial and seven fungal strains were assayed using the agar diffusion method to examine the effects of indigo naturalis and its bioactive compounds. The bioactive compounds of indigo naturalis were purified sequentially using GFC, TLC, and HPLC. Their structures were identified using mass spectrometry and NMR spectroscopy. UPLC-MS/MS was applied to compare the metabolome profiles of indigo naturalis ethyl-acetate (EA) extract and its source plant, Strobilanthes formosanus Moore. The results of in vitro antimicrobial assays showed that indigo naturalis EA-extract significantly (≥1 mg/disc) inhibits Gram-positive bacteria (Staphylococcus aureus, S. epidermis and methicillin-resistant S. aureus (MRSA)) and mildly inhibits non-dermatophytic onychomycosis pathogens (Aspergillus fumigates and Candida albicans), but has little effect on dermatophyes. Isatin and tryptanthrin were identified as the bioactive compounds of indigo naturalis using S. aureus and S. epidermis as the bioassay model. Both bioactive ingredients had no effect on all tested fungi. In summary, indigo naturalis prepared from Strobilanthesformosanus Moore exhibits antimicrobial effects on Staphylococcus and non-dermatophytic onychomycosis pathogens. Tryptanthrin and isatin may be its major bioactive ingredients against Staphylococcus and the inhibitory effect on MRSA may be due to other unidentified ingredients.

Removal of indigo carmine dye from water to Mg-Al-CO(3)-calcined layered double hydroxides

Layered double hydroxides (LDHs) calcined, denoted as CLDHs, have been shown to recover their original layered structure in the presence of appropriate anions. In the light of this so-called "memory effect", the removal of indigo carmine (IC), an anionic dye, from aqueous solution by calcined Mg-Al-CO(3) LDHs was investigated in batch mode. We looked at the influence of pH values, dye-adsorbent contact time, initial dye concentration and various temperatures of heating of LDHs on the decolorization rate of IC. The adsorption isotherms, described by Freundlich model are L-type. The characterization of the solids CLDHs, both fresh and after removal of IC, by X-ray diffraction and infrared spectroscopy shows that the IC adsorption on CLDHs is enhanced by reconstruction of a matrix hydrotalcite intercaled by the dye, and the intercalation of the organic ion was clearly evidenced by the net increase in the basal spacing from 0.76 nm for [Mg-Al-CO(3)] to 2.13 nm for the organic derivative.

Characterization of colonic polyps at conventional (nonmagnifying) colonoscopy after spraying with 0.2 % indigo carmine dye

BACKGROUND AND STUDY AIMS

Japanese endoscopists have devised a classification system based on mucosal crypt patterns which is helpful for distinguishing between hyperplastic polyps, adenomas, and invasive cancers at colonoscopy. The aim of this study was to assess how well the various types of colonic polyp could be distinguished using conventional colonoscopes after spraying with 0.2 % indigo carmine dye.

PATIENTS AND METHODS

The endoscopic appearances of all colonic lesions were assessed in 476 unselected patients using normal-resolution, nonmagnifying colonoscopes after spraying with 0.2 % indigo carmine dye.

RESULTS

A total of 709 lesions were found in the 476 patients, and histology was available for 673 of these lesions: 187 lesions were found to be non-neoplastic (128 hyperplastic, 2 juvenile, 30 inflammatory, and 27 classified as "others"); 467 lesions were adenomatous; and 19 lesions were carcinomas. Of the 467 adenomas, 377 were tubular, 77 were tubulovillous, 8 were villous and 5 were serrated; 423/467 were correctly identified (sensitivity 91 %). Of the 187 non-neoplastic lesions, 153 were correctly classified (specificity 82 %). A total of 343 of the 377 tubular lesions were correctly identified as tubular adenomas (sensitivity 90 %), and 46 of the 77 tubulovillous lesions were correctly identified.

CONCLUSIONS

Standard colonoscopy with dye spraying can be used to differentiate colonic polyps. Magnification is not always necessary to distinguish neoplastic from nonneoplastic colonic lesions. This finding could result in resource savings in colonoscopic screening.

Design and biological evaluation of photo-switchable inhibitors

Photo-switchable compounds are becoming increasingly popular for a series of biological applications based on the reversible photo-control of structure and function of biomolecules. Three applications for the usage of BODTCM and hemithioindigo as photo-reactive compounds are described here. The structure of the villin headpiece was modified by replacing a part of the backbone with hemithioindigo, aiming at induction of the folding process by irradiation with a defined wavelength. The E-isomer of BODTCM was applied as potential inhibitor of the 12/15-lipoxygenase (12/15-LOX), which is implicated in the pathogenesis of inflammatory diseases. A required death domain for the binding of proapoptotic proteins (e.g. Bak) to the hydrophobic groove of antiapoptotic proteins is the BH3 helix. Inserting hemithioindigo into this short peptide, stabilization towards proteolytic degradation is achieved. Such photo-reactive compounds might be developed as potential drugs for a great variety of diseases.

Influence of synthetic and natural food dyes on activities of CYP2A6, UGT1A6, and UGT2B7

Synthetic or natural food dyes are typical xenobiotics, as are drugs and pollutants. After ingestion, part of these dyes may be absorbed and metabolized by phase I and II drug-metabolizing enzymes and excreted by transporters of phase III enzymes. However, there is little information regarding the metabolism of these dyes. It was investigated whether these dyes are substrates for CYP2A6 and UDP-glucuronosyltransferase (UGT). The in vitro inhibition of drug-metabolizing enzymes by these dyes was also examined. The synthetic food dyes studied were amaranth (food red no. 2), erythrosine B (food red no. 3), allura red (food red no. 40), new coccine (food red no. 102), acid red (food red no. 106), tartrazine (food Yellow no. 4), sunset yellow FCF (food yellow no. 5), brilliant blue FCF (food blue no. 1), and indigo carmine (food blue no. 2). The natural additive dyes studied were extracts from purple sweet potato, purple corn, cochineal, monascus, grape skin, elderberry, red beet, gardenia, and curthamus. Data confirmed that these dyes were not substrates for CYP2A6, UGT1A6, and UGT2B7. Only indigo carmine inhibited CYP2A6 in a noncompetitive manner, while erythrosine B inhibited UGT1A6 (glucuronidation of p-nitrophenol) and UGT2B7 (glucuronidation of androsterone). In the natural additive dyes just listed, only monascus inhibited UGT1A6 and UGT2B7.

Production of superoxide radical in reductive metabolism of a synthetic food-coloring agent, indigocarmine, and related compounds

Indigocarmine, which is widely used as a synthetic colouring agent for foods and cosmetics in many countries, was reduced to its leuco form and decolorized by rat liver microsomes with NADPH under anaerobic conditions. The reductase activity was enhanced in liver microsomes of phenobarbital-treated rats, and inhibited by diphenyliodonium chloride, a NADPH-cytochrome P450 reductase (P450 reductase) inhibitor, but was not inhibited by SKF 525-A or carbon monoxide. Indigocarmine reductase activity was exhibited by purified rat P450 reductase. In contrast, when indigocarmine was incubated with rat liver microsomes and NADPH under aerobic conditions, superoxide radical was produced and its production was inhibited by superoxide dismutase and diphenyliodonium chloride. When indigocarmine was incubated with purified rat P450 reductase in the presence of NADPH, superoxide radical production was enhanced 17.7-fold (similar to the enhancement of indigocarmine-reducing ability) as compared with that of rat liver microsomes. A decrease of one molecule of NADPH was accompanied with formation of about two molecules of superoxide radical. P450 reductase exhibited little reductase activity towards indigo and tetrabromoindigo, which also afforded little superoxide radical under aerobic conditions. These results indicate that indigocarmine is reduced by P450 reductase to its leuco form, and superoxide radical is produced by autoxidation of the leuco form, through a mechanism known as futile redox cycling.

Inhibition of human aldehyde reductase by drugs for testing the function of liver and kidney

Drugs for testing the function of liver and kidney (sulfobromophthalein, phenolsulfonphthalein, indigo carmine and indocyanine green) and other organic anions (rose bengal and haematin) were found to potently inhibit human liver aldehyde reductase that is involved in the detoxification of 3-deoxyglucosone and methylglyoxal, reactive intermediates, during the formation of advanced glycation end products. The inhibition patterns by the compounds were non-competitive with respect to both coenzyme (NADPH) and substrate (D-glucuronate). The kinetics of the inhibition by a mixture of the 2 inhibitors suggests that all the inhibitory compounds bind to overlapping sites on the enzyme. The binding of rose bengal, sulfobromophthalein and phenylsulfonphthalein to the free enzyme was detected by ultrafiltration assay. However, in the reverse reaction, the enzyme was inhibited competitively with respect to the alcohol substrate by rose bengal, haematin, phenolsulfonphthalein, sulfobromophthalein, indigo carmine and indocyanine green, which showed Ki values of 0.1, 1, 3, 4, 4 and 10 microM, respectively. The results suggest that these potent inhibitors bind weakly to the free enzyme and tightly to the enzyme-NADP binary complex.

Effect of methylene blue, indigo carmine, and Renografin on human sperm motility

OBJECTIVES

To evaluate the effect of commonly used intraoperative vasography and tissue staining agents, indigo carmine, methylene blue, and Renografin, on sperm motility.

METHODS

Semen from 20 healthy men was obtained after 2 to 4 days of abstinence. Sperm motility was initially evaluated in each specimen. Standard solutions of indigo carmine, methylene blue, and Renografin-60 were diluted 2x and 4x with lactated Ringer's solution. Equal aliquots of sperm were mixed with undiluted and diluted drugs, and sperm motility was assessed.

RESULTS

Initial mean sperm motility was 70.3%+/-3.0%. Undiluted methylene blue and Renografin severely depressed sperm motility to 1.1%+/-0.5% and 2.3%+/-0.7%, respectively (P <0.05). Diluted methylene blue depressed motility to 4.9%+/-1.8% and 11.2%+/-3.0% (P < 0.05). Diluted Renografin depressed motility to 25.1%+/-4.1% and 55.3%+/-3.3% (P < 0.05). Although undiluted and 2x-diluted indigo carmine moderately decreased sperm motility (48.9%+/-3.2% and 61.7%+/-3.0%, P < 0.05), 4x-diluted indigo carmine had minimal effect on sperm motility (67.3%+/-2.8%, P > 0.05). Lactated Ringer's solution had no effect on sperm motility.

CONCLUSIONS

We found a severe, immediate reduction in sperm motility after exposure to undiluted standard solutions of methylene blue and Renografin. Dilution of Renografin significantly decreased its negative impact on the sperm motility, whereas the adverse effect of methylene blue remained fairly constant even with increasing dilution. Sperm motility should be assessed prior to application of these agents. Sperm should be aspirated for immediate use and/or cryopreservation prior to the use of these agents. Indigo carmine may be safely used as a tissue stain or vasography agent with a minimal effect on sperm motility in dilutions of 4x and higher.

Indigo carmine inhibits endothelium-dependent and -independent vasodilation

To investigate the potential mechanisms by which indigo carmine produces hypertension, we tested the hypothesis that indigo carmine inhibits endothelium-dependent vasodilation and determined the possible site of the inhibition (endothelium versus smooth muscle). Using isolated rat thoracic aortic rings that were precontracted with phenylephrine, we examined vasodilatory responses to acetylcholine, histamine, and Ca2+ ionophore A23187 (in endothelium-intact rings) and sodium nitroprusside and isoproterenol (in endothelium-denuded rings) in the presence and absence of indigo carmine. In addition, the effects of methylene blue on the acetylcholine- and sodium nitroprusside-induced vasodilation were compared with those of indigo carmine. Indigo carmine (10(-6), 10(-5), and 10(-4) mol/L) significantly inhibited receptor- and non-receptor-mediated endothelium-dependent vasorelaxation. Indigo carmine (10(-4) mol/L) also inhibited endothelium-independent vasorelaxation induced by sodium nitroprusside (an activator of vascular smooth muscle soluble guanylyl cyclase), although to a lesser extent than vasodilation from acetylcholine, histamine, and Ca2+ ionophore A23187. In contrast, indigo carmine (10(-4) mol/L) had no effect on the vasodilation induced by isoproterenol (an activator of adenylyl cyclase), indicating that indigo carmine selectively inhibits nitric oxide-mediated responses. Methylene blue, a known inhibitor of soluble guanylyl cyclase, inhibited both acetylcholine- and sodium nitroprusside-induced vasorelaxation. The inhibition was also greater in the acetylcholine- than the sodium nitroprusside-induced vasodilation. These results suggest that indigo carmine, like methylene blue, may inhibit endothelium-dependent relaxation by a mechanism that involves two levels. The major action of indigo carmine appears to be at the level of nitric oxide generation and/or release from the endothelial cell. In addition, indigo carmine appears to inhibit vascular smooth muscle guanylyl cyclase. Thus, indigo carmine may elevate blood pressure by interfering with these nitric oxide-mediated vasodilatory mechanisms.

Hysterosalpingography contrast media and chromotubation dye inhibit peritoneal lymphocyte and macrophage function in vitro: a potential mechanism for fertility enhancement

OBJECTIVE

To determine the effects of hysterosalpingography (HSG) contrast media (CM) and chromotubation dye on peritoneal lymphocyte proliferation and macrophage phagocytosis in vitro.

DESIGN

Peritoneal fluid (PF) lymphocytes and macrophages were isolated from 40 subfertile women undergoing diagnostic laparoscopy and 12 fertile women having laparoscopic tubal ligation. Dilutions of renografin, ethiodol, methylene blue, and indigo carmine were added to peritoneal lymphocyte and macrophage cultures. Tissue culture media alone served as control. Lymphocyte proliferation was assessed by hemocytometer counts and 3H-thymidine incorporation. Macrophage function was determined by phagocytosis of fluorescent microspheres.

RESULTS

Peritoneal lymphocyte proliferation and macrophage phagocytosis were significantly inhibited by renografin, ethiodol, methylene blue, and indigo carmine in a dose-dependent manner.

CONCLUSION

Inhibition of PF immune cell function by HSG CM and chromotubation dye may provide a potential mechanism for fertility enhancement after these diagnostic procedures.

Aerobically purified hydrogenase from Azotobacter vinelandii: activity, activation, and spectral properties

The hydrogenase from Azotobacter vinelandii is typically purified under anaerobic conditions. In this work, the hydrogenase was purified aerobically. The yields were low (about 2%) relative to those of the anaerobic purification (about 20%). The rate of enzyme activity depended upon the history of the enzyme. The enzyme preparations were active as isolated in H2 oxidation, and isotope exchange. The activity increased during the assay to a new maximal level (turnover activation). Treatment with reductants (e.g., H2, dithionite, dithiothreitol, indigo carmine) resulted in greater activation (reductant activation). Activation of the hydrogenase was accompanied by decrease in visible light absorption (300-600 nm) with maximal decreases at 450 and 345 nm which indicated the reduction of iron-sulfur clusters. The aerobically purified hydrogenase was susceptible to irreversible inactivation by cyanide. Pretreatment with acetylene did not influence activation of the hydrogenase. Once activated, the aerobically purified hydrogenase was indistinguishable from the anaerobically purified hydrogenase with respect to the catalytic properties tested.

Sister chromatid exchange induced by secondary and tertiary amine containing dyes and in combination with nitrite in vivo in mice

Sister chromatid exchange (SCE) induced by Indigo carmine (secondary amine containing dye), Fast green FCF (tertiary amine containing dye) and nitrite singly and in combination with nitrite were carried out in vivo in mice following acute exposure. A significant trend in the frequency of SCE in bone marrow cells was observed for all the dyes and nitrite tested when compared to the negative control. Fast green FCF was found to be more toxic than Indigo carmine. In addition, when a combination of half the concentrations of the dyes and nitrite was given, the values of SCEs were consistently lower than the sum of the expected values of the agents given individually. This indicates antagonistic response between the dyes and nitrite on SCEs.

The effect of dyes used to evaluate the in situ, ex-vivo, and perfused kidney

Methylene blue, indigo carmine, and fluorescein dyes were evaluated to determine their effect on the dog kidney. Methylene blue and indigo carmine were administered intravenously and intraarterially to the in situ vascularized kidney and serial histologic appearance of the kidney was determined. The three dyes were administered intraarterially to excised kidneys that were then preserved for 1 hour in the cold and autotransplanted; and finally the three dyes were administered to the perfusate of excised kidneys that were perfused for 18 hours by cryoperfusion with an albumin perfusate and then autotransplanted. Renal function and histology were determined 5 days after autotransplantation. Methylene blue dye did not damage the in situ vascularized kidney as judged by renal histology. However, administration of methylene blue to the ex vivo kidney that was subsequently short term cold stored or perfusion stored was associated with marked apparent ischemic damage of the organ. Indigo carmine dye did not adversely affect either the in situ vascularized kidney or the short term cold stored kidney. However, with perfusion storage, indigo carmine produced apparent vasoconstriction that led to perfusion failure. Fluorescein dye was not harmful to the kidney either during short term cold storage or during perfusion preservation. It is concluded that fluorescein is the dye of choice for evaluating the vascular anatomy or macroperfusion status of the kidney.

Reaction to indigo carmine

The commonly encountered cardiovascular effects of intravenous indigo carmine administration is transient alpha-receptor stimulation, namely increased total peripheral resistance, diastolic and systolic blood pressure, and central venous pressure with decreased cardiac output, stroke volume and heart rate. These usually cause no problems and frequently go undetected unless the patient is monitored closely during that brief interval. However, significant problems occur occasionally and its use is not totally without risks.