ABSTRACT
Necrosis is a form of cell death, which is related to various serious diseases such as cardiovascular disease, cancer, and neurodegeneration. Necrosis-avid agents (NAAs) selectively accumulated in the necrotic tissues can be used for imaging and/or therapy of related diseases. The aim of this study was to preliminarily investigate necrosis avidity of I-evans blue (I-EB) and its mechanism. The biodistribution of I-EB at 24 h after intravenous administration showed that the radioactivity ratio of necrotic to viable tissue was 3.41 in the liver and 11.82 in the muscle as determined by counting in model rats. Autoradiography and histological staining displayed preferential uptake of I-EB in necrotic tissues. nuclear extracts from necrotic cells exhibited 82.3% of the uptake in nuclei at 15 min, as well as 79.2% of the uptake at 2 h after I-EB incubation. The DNA binding study demonstrated that evans blue (EB) has strong binding affinity with calf-thymus DNA (CT-DNA) (=5.08×10 L/(mol/L)). Furthermore, the accumulation of I-EB in necrotic muscle was efficiently blocked by an excess amount of unlabeled EB. In conclusion, I-EB can not only detect necrosis by binding the DNA released from necrotic cells, but also image necrotic tissues generated from the disease clinically.
ABSTRACT
The purpose of this study was to synthesize and evaluate the necrosis target of MRI contrast agent based on rhein.The novel ligand 10-{ [6-(1,8-dihydroxyanthraquinone-3-carboxamido) hexyl] amino} acetyl-1,4,7,10-tetraazacyclododecan-1,4,7-triacetic acid (DO3A-rhein) was synthesized by two-step acylation and two-step deprotection.The paramagnetic contrast agent gadolinium 10-{ [6-(1,8-dihydroxyanthraquinone-3-carboxamido) hexyl] amino} acetyl-1,4,7,10-tetraazacyclododecan-1,4,7-triacetate (Gd-DO3A-rhein) was obtained by coordination of Gd3+ with the synthesized ligand.Its necrosis affinity was evaluated by liver infarction and muscular necrosis on rat models.The MRI was performed before administration of Gd-DO3A-rhein and during 0 h to 12 h after administration of Gd-DO3A-rhein (0.1 mmol/kg),respectively,and Gd-DOTA was used as control.After MRI scanning,rats were sacrificed and necrotic tissues were stained using triphenyltetrazolium chloride (TTC) and hematoxylin-eosin (HE).MRI images of liver infarction and muscular necrosis on rat models showed significantly enhanced signal intensity compared with normal tissues.The contrast ratios of necrotic liver/normal liver were 1.61 ±0.14 and 2.36 ±0.20 at 3 h and 12 h postinjection of Gd-DO3A-rhein (0.1 mmol/kg) respectively,demonstrating a significant difference compared with pre-administration of Gd-DO3A-rhein (1.16 ±0.10;P ＜ 0.05).The same results were obtained from necrotic muscles.These findings suggested that Gd-DO3A-rhein possessed the necrosis target and imaging capability of necrotic tissues.
ABSTRACT
Objective To establish the rat model of collagen-induced arthritis and study the diagnostic value of MRI for early RA by comparing to pathological changes. Methods Thirty Wistar rats were randomly divided into normal groups and experimental groups.Fifteen rats of the experimental groups were immunized with type Ⅱ collagen and Freund's Adjuvant Incomplete. At the scheduled days, the selected rats of both experimental and normal groups underwent X-ray, 1.5T MR scan plus enhancement and histological analysis. Results Arthritis Index increased on the 14th day after immunization and reached the peak on the 28th day in the experimental group, the positivity of Anti-CⅡ antibody was significantly different from the normal group.The experiemental model was established in 93.33% of all rats. The enhanced MRI showed that 12 (12/15) rats presented with abnormal signs . The sensitivity of MRI was 85.71% and the specificity was 100%. There was no significant correlation could be found between MRI and histological changes X-ray revealed soft tissue swollen in 4 (4/15) rats, which showed that MRI had higher sensitivity in detecting abnormal signs of arthritis than X-ray. Conclusion MRI may be used in the early diagnosis of early RA.