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PubMed2003

Synthesis, photophysical and electrochemical properties, and biological labeling studies of cyclometalated iridium(III) bis(pyridylbenzaldehyde) complexes: novel luminescent cross-linkers for biomolecules.

We report the synthesis, characterization, photophysical, and electrochemical properties of a series of luminescent cyclometalated iridium(III) complexes containing two aldehyde functional groups [Ir(pba)(2)(N-N)](PF(6)) (Hpba=4-(2-pyridyl)benzaldehyde; N-N=2,2'-bipyridine, bpy (1), 1,10-phenanthroline, phen (2), 3,4,7,8-tetramethyl-1,10-phenanthroline, 3,4,7,8-Me(4)-phen (3), 4,7-diphenyl-1,10-phenanthroline, 4,7-Ph(2)-phen (4)). The X-ray crystal structure of complex 1 has been investigated. Upon photoexcitation, complexes 1-4 exhibit intense and long-lived emission in fluid solutions at 298 K and in low-temperature glass. The luminescence is assigned to a triplet intra-ligand ((3)IL) excited state associated with the pba(-) ligand, probably with mixing of some triplet metal-to-ligand charge-transfer ((3)MLCT) (dpi(Ir)-->pi*(pba(-))) character. Since each of these complexes possesses two aldehyde groups, which can react with the primary amine groups of biomolecules to form stable secondary amines after reductive amination, we have investigated the possibility of these complexes as novel luminescent cross-linkers for biological substrates. L-Alanine has been labeled with complexes 1-4 to give the luminescent bioconjugates 1-(Ala)(2)-4-(Ala)(2). These conjugates show strong photoluminescence with long emission lifetimes under ambient conditions. On the basis of the emission energy trend, the excited state of these luminescent bioconjugates is likely to bear a high parentage of (3)MLCT (dpi(Ir)-->pi*(N-N)) character. In addition, the glycoprotein avidin (Av) has also been conjugated with complexes 1-4 to give the bioconjugates 1-Av-4-Av. Upon photoexcitation, these bioconjugates also display intense and long-lived (3)MLCT (dpi(Ir)-->pi*(N-N)) emission in aqueous buffer at 298 K. Furthermore, a heterogeneous competitive assay for biotin has been developed using 2-Av and biotinylated microspheres. We have shown that complexes 1-4 represent a new class of multicolor luminescent cross-linkers for biomolecular species.

Avidin↗
PubMed2006

Nucleic acid intercalators and avidin probes derived from luminescent cyclometalated iridium(III)-dipyridoquinoxaline and -dipyridophenazine complexes.

Six luminescent cyclometalated iridium(III)-dipyridoquinoxaline and -dipyridophenazine complexes [Ir(ppy)2(N-N)](PF6) (Hppy = 2-phenylpyridine; N-N = dipyrido[3,2-f:2',3'-h]quinoxaline, dpq (1); 2-n-butylamidodipyrido[3,2-f:2',3'-h]quinoxaline, dpqa (2); 2-((2-biotinamido)ethyl)amidodipyrido[3,2-f:2',3'-h]quinoxaline, dpqB (3); dipyrido[3,2-a:2',3'-c]phenazine, dppz (4); benzo[i]dipyrido[3,2-a:2',3'-c]phenazine, dppn (5); 11-((2-biotinamido)ethyl)amidodipyrido[3,2-a:2',3'-c]phenazine, dppzB (6)) have been designed as luminescent intercalators for DNA and probes for avidin. The structure of complex 4 has been studied by X-ray crystallography. The photophysical and electrochemical properties of the complexes have also been investigated. The binding of these complexes to double-stranded calf thymus DNA and synthetic double-stranded oligonucleotides poly(dA) x poly(dT) and poly(dG) x poly(dC) has been investigated by spectroscopic titrations. The interactions between the two biotin-containing complexes and avidin have been studied by 4'-hydroxyazobenzene-2-carboxylic acid (HABA) assays and emission titrations.

Avidin↗
PubMed1986

Early and late effects on the normal dog brain of permanent interstitial iridium-192 irradiation.

To investigate the effects of a permanent interstitial source of gamma-irradiation on normal brain tissue, single iridium-192 (Ir-192) wires (1.05 mCi) were stereotactically implanted into the left centrum semiovale of adult dogs (survival times, 25, 46, 74, 230 and 362 days). Within 25 days, a coagulation necrosis developed in the immediate vicinity of the radioactive source. In later stages, the necrosis increased in size and became progressively mineralized. Staining for extravascular immunoreactive serum proteins revealed the presence of a chronic perifocal vasogenic edema, which extended into the white matter of the entire ipsilateral hemisphere. This edema persisted through all stages and showed a significant decrease only in the animal with a 1-year survival. A reactive gliosis with formation of a dense network of glial fibrillary acidic protein-positive astrocytes developed around the central necrosis in the adjacent white matter and, at later stages, in the contralateral hemisphere. Demyelination was restricted to the ipsilateral centrum semiovale without affecting the internal capsule or the contralateral hemisphere. It was present as early as 25 days and showed no tendency to increase at later stages. Analysis of the sequential morphological changes following Ir-192 implantation suggests that the central coagulation necrosis represents a direct radiation effect, the sharp focal delineation of which can be explained by the physical characteristics of the radiation source, i.e., rapid fall-off of the dose at short distances. Due to the continuous emission of radiation energy, there is a perifocal zone with overlapping of progressive radiation damage and tissue organization. This focus becomes the source of a chronic vasogenic edema, which in turn is most likely to be responsible for the partial demyelination of the adjacent centrum semiovale. The widespread reactive gliosis observed at all stages may also, in part, be a consequence of chronic vasogenic edema, but its distribution suggests that direct radiation effects may also be involved.

Animals↗
PubMed1978

Post-operative stereotactic Curie-therapy using the iridium-192 GammaMed contact irradiation apparatus combined with radio-sensitizers in treating multiform glioblastomas.

Experimental investigations on the dimethyl-amino-stilbous carcino-sarcoma of the rat have led to a modified interstitial post-operative Curie-therapy of gliomas in the brain hemispheres following treatment with radio sensitizers. After treatment with the thymine-analogous radio-sensitizers 5-brom-2-desoxyuridine (BUDR) and 5-brom-2-desoxycytidine (BCDR) and desoxyguanosine as well as the anti-metabolites 5-fluor-uracile (FU) and methotrexate (Mtx), there is greater incorporation of the thymine analogues in the DNS of the tumour cells. More than any other combination, BUDR and Mtx effectively sensibilizes the tumour cells. Syncavit and actinomycine-D are also effective. After radio-sensitizing the post-iridium-192 contact irradiation apparatus on 133 patients with gliomas. This treatment lengthened postoperative survival times.

Brain Neoplasms↗
PubMed1985

[Intraluminal irradiation with iridium 192--a new method for the treatment of inoperable esophageal cancers?].

In inoperable esophageal carcinoma the intraluminal high dose afterloading therapy with Iridium 192 was employed as an alternative to the palliative resection. Prerequisite for this treatment, which was used in 19 patients during the last year, is the preceding passage restoration of the tumor stenosis by endoscopic laser therapy. Every two weeks the patients are endocavitarily irradiated up to 3 times with a dose of 7 Gy. Observing the patients by endoscopic means the implantation of a tubus is avoidable achieving better quality of life and comparable survival times.

Brachytherapy↗
PubMed1986

An unusual complication of a myocardial electrode--apatite mantle on the platinum-iridium spurs.

A case of a high excitation threshold that occurred 2 years 5 months after the initial implantation of pacemaker electrodes is described in a girl 4 years 3 months of age. This complication was considered to be due to calcification of the platinum-iridium electrode spurs. The calcified material was shown to be a kind of apatite using the X-ray powder diffraction method. This complication is rare, but it must be kept in mind since battery longevity has markedly improved in recent years.

Apatites↗
PubMed1980

Iridium implants in treatment of anorectal carcinoma.

A technique is described for the use of iridium-192 implants, combined with external irradiation, in the treatment of primary anorectal malignancy. The method allows large doses of radiation to the primary growth, regional infiltration and extensions, with much lower doses to the surrounding normal tissues and organs. Acceptable criteria for conservative local treatment of selected primary anorectal carcinomas are established. For the poor risk patient, the patient who refuses operation, and those having primary or recurrent carcinoma with distant metastases, this method of treatment offers maximum benefit, palliation, and acceptable complication rates. With judicious selection of patients and careful attention to volume of tissue treated, total dose, and fractionalization, serious complications should be substantially reduced.

Aged↗
PubMed2004

Accelerated partial breast irradiation with iridium-192 multicatheter PDR/HDR brachytherapy. Preliminary results of the German-Austrian multicenter trial.

PURPOSE: To evaluate perioperative morbidity, toxicity, and cosmetic outcome in patients treated with interstitial brachytherapy to the tumor bed as the sole irradiation modality after breast-conserving surgery. PATIENTS AND METHODS: From November 1, 2000 to January 31, 2004, 176 women with early-stage breast cancer became partakers in a protocol of tumor bed irradiation alone using pulsed-dose-rate (PDR) or high-dose-rate (HDR) interstitial multicatheter implants. Patients became eligible, if their tumor was an infiltrating carcinoma < or = 3 cm in diameter, the surgical margins were clear by at least 2 mm, the axilla was surgically staged node-negative, the tumor was estrogen and/or progesterone receptor-positive, well or moderately differentiated (G1/2), the tumor did not contain an extensive intraductal component (EIC) and the patient's age was > 35 years. Implants were positioned using a template guide, delivering either 49.8 Gy in 83 consecutive hours (PDR) or 32.0 Gy in two daily fractions over 4 days (HDR). Perioperative morbidity, toxicity, and cosmetic outcome were assessed. Interim findings of the first 69 patients, who were treated in this multicenter trial, after a median follow-up of 24 months (range, 15-39 months) are presented. RESULTS: One of the 69 patients (1.4%) developed a bacterial infection of the implant. No other perioperative complications, for example bleeding or hematoma, were observed. Acute toxicity was low: 2.9% of the patients (2/69) experienced mild radiodermatitis. Late toxicity: hypersensation/mild pain 7.2% (5/69), intermittent but tolerable pain 1.4% (1/69), mild dyspigmentation 10.1% (7/69), mild fibrosis 11.6% (8/69), moderate fibrosis 1.4% (1/69), mild telangiectasia (< 1 cm(2)) 11.6% (8/69), and moderate teleangiectasia (1-4 cm(2)) 1.4% (1/69). Good to excellent cosmetic results were observed in 92.4% of the patients evaluated. All patients (n = 176) remained disease-free to the date of evaluation. CONCLUSION: This analysis indicates that accelerated partial breast irradiation with iridium-192 interstitial multicatheter PDR/HDR implants is feasible with low perioperative morbidity, low acute and mild late toxicity, and does not significantly affect cosmetic results at a median follow-up of 24 months.

Adult↗
PubMed1999

[Combined treatment of localized prostate cancer with HDR-Iridium 192 remote brachytherapy and external beam irradiation].

BACKGROUND: The localized prostate cancer can be treated curatively by radiation therapy. The combined treatment of external beam irradiation and HDR-Iridium 192 remote brachytherapy allows higher radiation doses within the tumor without increasing radiation sequelae. PATIENTS AND METHODS: Patients of our clinic have been treated with this combined procedure since 1991. Between 1991 and 1994 15 patients received 2 x 9 Gy of high-dose-rate brachytherapy, followed by 36 Gy external beam irradiation (group A). Because of the frequent local failures in group A, the reference dose of external beam irradiation was increased to 50.4 Gy after brachytherapy between 1994 and 1996. RESULTS: Seven of 15 patients (47%) in group A developed a local recurrence after a median of 17 (13 to 30) months. In group B (20 patients) local failure occurred in 3 patients (15%) after 11, 16 and 32 months. CONCLUSION: The combined radiation therapy of localized prostate cancer cannot substitute radical prostatectomy completely, but it is a promising alternative in the curative treatment in selected patients.

Aged↗
PubMed2001

Advantages of the iridium permanent modifier in fast programs applied to trace-element analysis of plant samples by electrothermal atomic absorption spectrometry.

The application of a fast program combined with the advantages of the iridium permanent modifier is proposed for trace element analysis of plant samples by electrothermal atomic absorption spectrometry (ETAAS). For two volatile elements (Cd, Pb) and two mid-refractory elements (Cr, Ni) it was demonstrated that coating of the platform or of the tube atomization area with Ir is an efficient means of improving the accuracy and precision of results. A detailed study of interference from individual main matrix components and from composite plant matrices has confirmed the usefulness of the whole approach. The validity of the method has been confirmed by analysis of eight reference plant materials.

Iridium↗
PubMed1999

Rapid renal single-photon emission tomography by continuous infusion of iridium-191m.

Continuous infusion of iridium-191m (t1/2 = 5 s), produced with an 191Os/191mIr generator, was used to obtain rapid high-resolution single-photon emission tomography (SPET) of renal blood flow in the rabbit. SPET scans of the abdomen were obtained with a triple-detector SPET system (MS3, Siemens Gammasonics). The generator was eluted at a flow rate of 3 ml/min, which delivered a steady-state dose of 170 MBq (4.5 mCi) of 191mIr. The total 191Os breakthrough was 850 kBq (23 microCi). A 5-min SPET acquisition recorded a total of 2.8 million counts, resulting in images of high technical quality. Volume-rendered images clearly showed the abdominal aorta, splenic artery, spleen, renal arteries, kidneys and splanchnic vasculature. Tomographic slices through the kidneys revealed tracer primarily within the renal cortices without visualization of the collecting system. The estimated effective dose equivalent for a 5 min infusion of 191mIr at a steady-state dose of 170 MBq is 0.74 mSv compared with 2.7 mSv from a 170 MBq dose of 99mTc-DMSA. This study demonstrates the feasibility of high-resolution SPET of regional renal perfusion in the rabbit by continuous intravenous infusion of 191mIr. The renal distribution of continuously infused 191mIr is largely within the cortices, with minimal or no detectable activity in the region of the renal pelvicalyceal system. Using this technique, cortical renal SPET can be completed much more rapidly (< 5 min) than with conventional renal cortical imaging agents, which suggests that this technique could be applied to the observation of rapid changes in renal perfusion such as those resulting from pharmacologic intervention, obviating the need for the patient to return for additional visits. Additional studies are required to (a) validate the methodology in larger animals prior to considering the potential for use in human beings, (b) optimize the generator design for continuous infusion, and (c) evaluate the changes in the distribution of 191mIr that occur in animal models of altered renal perfusion.

Animals↗
PubMed1976

Use of an iridium electrode for direct measurements of pI of proteins after isoelectric focusing in polyacrylamide gel.

The use of an iridium microelectrode 0.5 mm in diameter is proposed for measuring the pH gradient in polyacrylamide gels after isoelectric focusing. The electrode exhibits a perfectly linear potential/pH relationship; thus it can be used directly in conjunction with a pH meter using the pH scale for readings. pH equilibrium values are rapidly reached (10-15 s) and pI determinations are obtainable with good accuracy (better than 0.1 pH).

Calorimetry↗
PubMed1983

Antitumor effects of rhodium(I), iridium(I) and ruthenium(II) complexes in comparison with cis-dichlorodiammino platinum(II) in mice bearing Lewis lung carcinoma.

The effects of square planar rhodium, [RhacacCOD]o and iridium, [IracacCOD]o complexes and of octahedral ruthenium, [cis-RuCl2 (DMSO)4]o complex have been examined in comparison with cis-dichlorodiammino platinum(II) (cis-PDD). The toxicity in BDF1 mice varies widely and decreasing LD50-values, ranging from 0.94 mg/kg to 1000 mg/kg, have been obtained for cis-PDD, [RhacacCOD]o, [IracacCOD]o and [cis-RuCl2(DMSO)4]o, respectively. All the tested complexes similarly inhibit the growth of subcutaneous Lewis lung carcinoma and the development of spontaneous as well as of artificial metastases, with the exception of [IracacCOD]o which is inactive on metastases. The antitumor activity of [RhacacCOD]o and [cis-RuCl2(DMSO)4]o appears interesting, since it is of the same magnitude as that of cis-PDD, considering also that they were found to be only marginally nephrotoxic.

Animals↗
PubMed1980

Treatment of malignant bladder tumors by iridium-192 wiring.

Small tumors of the mobile portion of the bladder may be treated by means of interstitial irradiation by iridium-192 wiring. Twenty-six tumors (mostly T1, but also T2 and T3) were treated by this procedure. Good results are attained in 89 per cent of 19 cases followed over three years. This method has the benefit of avoiding irradiation to the surgeon's hands, and of delivering to a specific site a dose of 6,000 rads. No bladder contraction was observed.

Brachytherapy↗
PubMed1983

Treatment of prostatic carcinoma by pelvic lymphadenectomy, temporary Iridium-192 implant, and external irradiation.

Forty patients with clinically localized adenocarcinoma of the prostate have been treated by a combination of pelvic lymphadenectomy, temporary Iridium-192 implantation, and external irradiation with follow-up of one to five years. 192Ir implant delivers a minimum tumor dose of 3,000 rad to A2 and B1 lesions and 3,500 to B2 and C lesions. Two weeks later patients receive 4,000 rad of external irradiation to the prostate over four to five weeks. Patients with pelvic nodal metastases receive 5,000 rad to the pelvis with a midline block at 4,000 rad. All patients have had a complete local response as judged by clinical criteria. Prostate needle biopsies have been performed on 16 patients one year or less after treatment, with 15 biopsies benign. The technique appears to offer excellent local control of prostatic adenocarcinoma with acceptably low morbidity.

Adenocarcinoma↗
PubMed1988

Studies on some iridium(III) complexes with Schiff bases derived from amino carboxylic acids.

The reactions of iridium(III) chloride with different Schiff bases gave complexes of types [Ir(SB)3], [Ir(SB')Cl(H2O)2], [Ir(SB'')Cl2]n, [Ir(SB'' ')Cl(H2O)]n (SBH = Schiff bases derived from anthranilic acid and benzaldehyde, acetophenone, vanillin, cinnamaldehyde or m-hydroxyacetophenone; SB'H2 = Schiff bases derived from anthranilic acid and salicylaldehyde or o-hydroxyacetophenone; SB''H = Schiff bases derived from p-aminobenzoic acid and benzaldehyde, acetophenone, vanillin, cinnamaldehyde, or m-hydroxyacetophenone; SB'' 'H2 = Schiff bases derived from p-aminobenzoic acid and salicylaldehyde or o-hydroxyacetophenone). These complexes have been characterized on the basis of elemental analyses, conductance, magnetic moment, and spectral (electronic, i.r., and 1H n.m.r.) data. The electronic spectra reveals octahedral geometry for these complexes except for [Ir(SB'')Cl2]n, which is trigonal bipyramidal. The thermal behavior of these complexes has also been studied by TG, DTG, and DSC techniques. The different kinetic parameters, viz., order of reaction, activation of energy, and heat of reaction were calculated. The antifungal and antiviral activities of the complexes with Schiff bases derived from anthranilic acid have also been investigated.

4-Aminobenzoic Acid↗
PubMed1991

Effect of dose rate on local control and complications in definitive irradiation of T1-2 squamous cell carcinomas of mobile tongue and floor of mouth with interstitial iridium-192.

From 1971 to 1988, 134 T1 and 145 T2 biopsy-proven squamous cell carcinomas of mobile tongue and floor of mouth were definitively managed by iridium-192. Implantations were performed using either guide gutters or afterloading plastic catheters. The prescribed dose at the reference isodose (85% of the basal dose rate, Paris system) was 60-70 Gy. Total dose was not adjusted to dose rate or tumor volume. Results of the 279 implants have been analysed to look for a possible influence of dose rate on local control and necrosis. Follow-up patients free of local recurrence is 1-180 months with average of 51 months. The 279 tumors were divided in four groups according to dose and dose rate: greater than or equal to 62.5 Gy and greater than or equal to 0.5 Gy/h (n = 130), greater than or equal to 62.5 Gy and less than 0.5 Gy/h (n = 36), less than 62.5 Gy and greater than or equal to 0.5 Gy/h (n = 81), less than 62.5 Gy and less than 0.5 Gy/h (n = 32). The four groups were comparable according to age, sex, tumor diameter and macroscopic aspect. At 5 years, the estimated local control (Kaplan Meier) was 93, 87, 79 and 52%, respectively (dose adjusted to dose rate: p less than 0.001, dose rate adjusted to dose: p less than 0.01, Log-rank); the necrosis rate was 44, 24, 37 and 5%, respectively (dose adjusted to dose rate: p = 0.08, dose rate adjusted to dose: p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Carcinoma, Squamous Cell↗