Radiolabeling of annexin A5 with (99m)Tc: comparison of HYNIC-Tc vs. iminothiolane-Tc-tricarbonyl conjugates.

In the perspective of expanding the use of annexin A5 (anx A5) as radioactive tracer of cell death in vivo, we recently described its radiolabeling with (99m)Tc-tricarbonyl [(99m)Tc(H(2)O)(3)(CO)(3)](+) via the mercaptobutyrimidyl group (anx A5-SH). The aim of the present article was to compare this new method with the HYNIC strategy (anx A5-HYNIC), recognized at present as the reference for the radiolabeling of proteins with (99m)Tc. Similar radiolabeling yields and better chemical stability were obtained with the [anx A5-SH-(99m)Tc-tricarbonyl] complex. Since the [anx A5-HYNIC-(99m)Tc(tricine)(2)] conjugate shows isomeric forms which can affect the biological properties whereas [anx A5-SH-(99m)Tc-tricarbonyl] is less or not prone to such drawback, the latter seems superior to the former. Furthermore, (anx A5-SH) is readily obtained via commercial sources of Traut's reagent whereas (anx A5-HYNIC) is not. The results provide encouraging evidence in the development of anx A5-labeled reagent for apoptose imaging.

Is scintigraphic double-track appearance a sign of severe acute episodes of ulcerative colitis?

AIM: In comparison to endoscopy, clinical and biological criteria are less predictive of severity in attacks of ulcerative colitis (UC). Our aim was to assess the value of the double-track scintigraphic appearance in the assessment of the severity of acute UC by comparing it to endoscopic criteria. PATIENTS AND METHODS: We reviewed medical records of 52 patients hospitalized for an acute attack of UC, who had undergone within 48 hours of presentation both a technetium 99m hexamethyl propylene amine oxime (99mTc-HMPAO) granulocyte scintigraphy and endoscopic examination (colonoscopy: n=20; rectosigmoidoscopy: n=32). RESULTS: Taking into account the colonic segments examined together with both methods in the same patient or results obtained with colonoscopies, there was an excellent agreement between the double-track scintigraphic appearance and endoscopic criteria of severity. CONCLUSION: In patients with previously diagnosed UC, 99mTc-HMPAO granulocyte scintigraphy when available may replace endoscopic examination to assess the severity of attacks.

Intracerebral C6 glioma model in female hairless rats: assessment by using MRI and follow-up of irradiation.

An experimental intracerebral C6 glioma model in immunosuppressed female hairless rats has been developed. The rate of tumor uptake was evaluated by magnetic resonance imaging (MRI), using specific sequences without gadolinium enhancement. Twenty-four hours before intracerebral transplantation, a control cranial MRI was carried out and rats underwent a total body irradiation (TBI). MRI was repeated seven days after transplantation in order to monitor tumor uptake. Then, twelve days after transplantation, tumors were treated with two different protocols of radiotherapy: 3 Gy during 5 days or 0.7 Gy three times a day during 5 days (ultra fractionation). A third MRI was performed 21 days after intracerebral transplantation. Eventually, all the rats were sacrificed and histological analysis of the tumors was performed. Our results show that TBI efficiently increases the rate of tumor uptake. Thereafter, tumor formation and growth as well as the efficiency of a therapy (radiotherapy in our case) can be monitored with MRI (without gadolinium enhancement). Treatment of C6 glioma tumors with ultrafractionation was a marked improvement compared to a more traditional radiotherapy treatment. We developed a model that is useful for the study of new glioma treatment. We also obtained promising preliminary results when using ultra fractionation radiotherapy.