Bioimaging of isosteric osmium and ruthenium anticancer agents by LA-ICP-MS.

Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) was used to study the spatial distribution of two metallodrugs with anticancer activities in vivo, namely the organoruthenium plecstatin-1 (1) and its isosteric osmium analogue (2), in liver, kidneys, muscles and tumours of treated mice bearing a CT-26 tumour after single-dose i.p. administration. To the best of our knowledge, this is the first time that the spatial distribution of an osmium drug candidate has been investigated using LA-ICP-MS in tissues. Independent measurements of the average ruthenium and osmium concentration via microwave digestion and ICP-MS in organs and tumours were in good agreement with the LA-ICP-MS results. Matrix-matched standards (MMS) ranging from 1 to 30 µg g-1 were prepared to quantify the spatial distributions of the metals and the average metal content of the MMS samples was additionally quantified by ICP-MS after microwave digestion. The recoveries for osmium and ruthenium in the MMS were 105% and 101% on average, respectively, validating the sample preparation procedure of the MMS. Preparation of MMS was carried out under an argon atmosphere to prevent oxidation of osmium-species to the volatile OsO4. The highest metal concentrations were found in the liver, followed by kidney, lung and tumour tissues, while muscles displayed only very low quantities of the respective metal. Both metallodrugs accumulated in the cortex of the kidneys more strongly compared to the medulla. Interestingly, osmium from 2 was largely located at the periphery and tissue edges, whereas ruthenium from 1 was observed to penetrate deeper into the organs and tumours.

A NIR phosphorescent osmium(ii) complex as a lysosome tracking reagent and photodynamic therapeutic agent.

A novel near infrared (NIR) phosphorescent osmium complex (Os1) was developed for lysosome tracking and photodynamic therapy. Owing to its NIR photophysical properties, cellular imaging ability and phototoxicity, it has advantages over its ruthenium analogue (Ru1).

Local and systemic toxicity of h-R3, an anti-epidermal growth factor receptor monoclonal antibody, labeled with 188osmiun after the intracerebral administration in rats.

h-R3 is a humanized anti-epidermal growth factor receptor (EGFR) monoclonal antibody (MAb). This receptor is over-expressed in the majority of tumors of epithelial origin, including glioblastomas. 188Rhenium (188Re) constitutes an ideal radionuclide for imagining and radioimmunotherapy, and its toxicity is known, nevertheless, it is unknown if 188Os, as 188Re's daughter, has any local or systemic toxicity effect when it is administered intracerebrally for treating intracranial tumors. For this reason we decided to assess the toxicity of stable 188Os once the complete decay of 188Re has occurred, by administering intracerebrally to rats the h-R3 labeled with 188Os. Forty rats (20 each sex) were distributed randomly into four experimental groups (ten per group): control group received 5microL of glucoheptonate solution vehicle; two other groups were treated with unlabeled or labeled h-R3 with 188Os. The remaining group served as a non-treated control group. A single 5 microL dose (2.5 microL into each lateral ventricle) of neutral solution containing 50 microg of h-R3 labeled initially with 13.25 microCi of 188Re was stereotactically administered into lateral ventricles 8 days after the conjugation with the radionuclide was done. Each animal was observed daily for detection of toxicity signs. Body weights were recorded on days 0, 7 and 14. Blood samples for analysis of hematological and clinical chemistry parameters were taken on days 0 and 14. Necropsy and histopathological studies were carried out at the end of the study. All animals gained weight by day 14. There were no changes in hematological and clinical chemistry, but minimal histopathological changes were observed at the application sites. This study shows that single doses of 188Os-h-R3 is tolerable and causes minimal local and no systemic toxicity effects in rats.

[Radiological opacities after intra-articular injection of osmic acid. Relationship with the injection site (author's transl)]. / Opacités radiologiques après synoviorthèse du genou à l'acide osmique. Relation avec le site d'injection.

Abnormal radiological opacities are sometimes observed after intra-articular injection of osmic acid. These opacities are radio-opaque because osmium is a heavy metal (atomic number = 76). They are usually found near the suprapatellar pouch which is the usual injection site. A parasynovial injection (or back flow from the joint cavity) of some of the osmic solution, followed by concentration and fixation of the osmic deposits at this level, seems to be the cause of these radiological opacities. This could be the reason for the poor clinical results encountered in some cases of osmic acid therapy followed by such deposits.

[Synoviorthesis of the knee using osmic acid: apropos of 61 injections]. / Synoviorthèses du genou par l'acide osmique. A propos de 61 injections.

The authors report their experience of 61 injections of osmic acid into the knee during the course of rheumatoid polyarthritis. The results stated to be very good and good, are classified by the disappearance of pain, swelling and stiffness, or a improvement in any one of these criteria. As observed in 67% of cases at the third month the result following changed with time. While these favourable results persisted into the fifth month, there was a remarkable maintenance of them to the 30th month in those patients who it was able to follow so long. The most distinct and lasting results were seen in those joints which showed the least radiological change. Tolerance of the injection of osmic acid was satisfactory apart from several painful reactions which improved in the 24 hours following injection. Two cases of thrombo-phlebitis were seen and one case of rupture of the synovium. If the results obtained with osmic acid appear less impressive than those obtained with isotopes, the simplicity of the method attracts attention as it needs no complicated equipment and is applicable to young invalids.

[Treatment of hemophilic arthropathies by medical synoviorthesis]. / Le traitement des arthropathies hémophiliques par la synoviorthèse médicale

The effects of medical synoviorthesis were studied by the authors in the haemophiliac. The use of radioisotopes was limited in view of the young age of the patients but a good result was achieved for the 5 elbows treated and for the 4 knees (yttrium 90) the results were 2 good, 1 fair and 1 failure. Osmic acid was injected in 44 knees. The results were good and fair in 51% of 39 knees. The results can be improved by a second injection. Synoviorthesis should be kept for joints with very few destructions because of the danger of worsening the osteocartilaginous lesions, specially with osmic acid.

[Chemical synovectomy with osmic acid]. / La sinoviectomia chimica con acido osmico.

The authors face the problem of the treatment in chronic arthrosynovitis. After some general premises they dwell upon the use of osmic acid in such cases and report the results and casuistr of Verona Orthopaedic Clinic.

Intra-articular triamcinolone hexacetonide and osmic acid in persistent synovitis of the knee.

43 rheumatoid knees with persistent effusion were treated by intra-articular injections of triamcinolone hexacetonide (40 mg) or combined triamcinolone - osmic acid. Both treatments produced long-lasting improvements in the treated knees. Osmic acid seemed to potentiate the effect of the steroid. This demonstrated by measurement of joint circumference and local 99mTc uptake. In the general clinical evaluation the difference between the treatments was not noticeable. The percentage of 'excellent' and 'good' improvements was 36 at 12 months in the steroid-group and 44 in the steroid-osmic acid group.

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.

Post-yersinotic Reiter's disease in a physician treated with osmium tetroxide.

A case of general yersinosis in a male physician is described. Most probably the infection was acquired nosocomially in a paediatric ward. The infection affected several organs including the liver, but osmium tetroxide was nevertheless used to perform chemical synovectomy in a knee joint suffering from active arthritis. The arthritis was cured, and the already existing liver affection did not progress. The only complaint from the patient, months after the osmic acid injection, was a strong metallic taste on the tongue. More than a year after the intra-articular injection, the metallic taste disappeared. The amount of osmium in the patient's blood was then calculated to be less than 100 molecules of osmium per ml blood.

Osmium deposits detected by x-ray after synoviorthesis of the knee.

A study of 113 knees of 72 patients treated with intra-articular injection of osmic acid for chronic exudative synovitis caused by various rheumatic diseases is reported. Certain cases presented abnormal radiological opacities, statistically more frequent after the injection of 200 mg than after 100 mg of osmic acid (33.9% and 15.7%). These images appear early after the injection and can remain for years. They should not be confused with intra-articular calcium deposits, or with synovial ossifications or various periosteal osteogenic processes. Their appearance does not seem to be related to the rheumatic disease treated or the therapeutic result obtained. They reflect the fixation of osmium in the synovial fatty tissue, which causes a fibrous reaction at this level. Their longterm action in the cicatrization of the synovia, or their part in a relapse of an inflammatory episode should be clarified.

Radiological opacities of the knee after intra-articular injections of osmic acid.

Unusual radiological opacities have been observed in 29 cases after intraarticular injection of osmic acid in 113 knees of 72 patients under treatment for a chronic exudative synovitis in different types of rheumatic diseases. They are statistically more frequent after the injection of 200 mg than after 100 mg (33.9 and 15.7% respectively). Most of the time, they are located in the suprapatellar pouch. The opacities appear soon after the injection and can last for several years. They do not seem to have an unfavorable influence on the clinical course. They appear to be caused by a deposition of osmium in synovial fat tissue. From here the osmium might stimulate fibrosis. The radiological image has to be differentiated from intra-articular calcifications, synovial ossifications and various periosteal osteogenic processes.

The immediate effects of intra-articular injections of osmic acid.

One hundred mg of osmic acid (with corticosteroid and lidocaine) was injected for therapeutic purposes into the knee in 10 patients suffering from various types of recalcitrant synovitis (mostly rheumatoid arthritis). The effects of this injection were followed by examination of synovial fluid, blood, and urine of these patients, collected at various intervals after intra-articular injection. As a control, a group of 3 patients (5 knees) received corticosteroid and lidocaine intra-articularly, and another group (6 patients, 7 knees) was injected with lidocaine only, both with the same total volume as the first group. Blood and urine examinations revealed essentially no effects of osmic acid, whereas in synovial fluid a strong inflammatory reaction was observed up to the second day after the injection, though the effusion soon disappeared. In a group treated with lidocaine + corticosteroid, a mild, early inflammatory reaction was noted, while lidocaine alone produced only a dilution effect, and the exudate remained relatively longer. Thus, the early local inflammatory reaction due to osmic acid is an expression of the necessary drastic effect of this beneficial therapeutic agent.

The role of osmic acid in the treatment of immune synovitis.

Thirty-seven New Zealand rabbits were observed for up to 1 year after their knee joints were instilled with 1 ml of 1% osmic acid. A selective destruction of synovial lining cells occurred with a concurrent synovitis, but lining cell regenerated by the eighth week. Nonprogressive abnormalities were also present in the cartilage. When an immune synovitis was induced in both knees of 16 rabbits, the osmic acid treated joint demonstrated a significantly greater synovitis and progressive aberrations compared to the untreated knee.

Response of synovial immunocytes to intra-articular agents in experimental arthritis.

In rabbits with immune arthritis the numbers of lymphoid aggregates and pyroninophilic and non-pyroninophilic cells per unit area of synovium were calculated from sections taken at various intervals after intra-articular drug injections. A model of immune arthritis based on the results is presented. In the active phase of the arthritis, plasma cells, plasmablasts and lymphoid aggregates proliferate, while the number of lymphocytes decreases. In the inactive phase after treatment, the cell pattern is the reverse. The ratio of pyroninophilic to non-pyroninophilic cells proved to be a good measure of the activity of the arthritis. A favourable therapeutic effect was achieved with triamcinolone hexacetonide and combined steroid-osmic acid, but not with osmic acid alone.