Radiochemical synthesis and preclinical evaluation of 68Ga-labeled NODAGA-hydroxypropyl-beta-cyclodextrin (68Ga-NODAGA-HPBCD).

A new renaissance started in the research and application of cyclodextrins a few years ago. 2-Hydroxypropyl-beta-cyclodextrin (HPBCD) is used in the formulation of drugs and recently orphan designation was granted for the treatment of Niemann-Pick disease, type C. HPBCD is considered to be safe, but the exact mechanism of action and side effects are not completely explained. Labeled cyclodextrin derivatives are required to reveal the biological activity and in vivo distribution by imaging techniques. The aims of our study were to synthetize the 68Ga-labeled NODAGA-hydroxypropyl-beta-cyclodextrin (68Ga-NODAGA-HPBCD) and test the pharmacokinetic properties and in vivo distribution of this radiolabeled molecule. p-NCS-benzyl-NODA-GA (NODAGA) was conjugated to the 6-deoxy-6-monoamino-(2-hydroxypropyl)-ß-cyclodextrin (NH2-HPBCD). The product (NODAGA-HPBCD) was analyzed by analytical RP-HPLC and verified with high resolution mass spectrometry. In the next step the NODAGA-HPBCD was labeled with Gallium-68 (68Ga). The 68Ga labeled NODAGA-HPBCD (68Ga-NODAGA-HPBCD) was characterized and the radiochemical purity (RCP%), partition coefficient (log P values), and in vitro stability was determined. Thereafter in vivo distribution and pharmacokinetic properties of 68Ga-NODAGA-HPBCD was monitored by positron emission tomography (PET). NODAGA-HPBCD was purified by preparative RP-HPLC and the purity was better than 98%. The radiochemical purity of the 68Ga-NODAGA-HPBCD was higher than 98%, the specific activity was 17.62 ±â€¯2.43 GBq/µmol, and the decay corrected yield was 76.54 ±â€¯6.12% (n = 8). The octanol/water partition coefficient of 68Ga labeled NODAGA-HPBCD was found to be -3.07 ±â€¯0.11. In vivo dynamic and ex vivo biodistribution studies using control BALB/c mice revealed that 68Ga labeled NODAGA-HPBCD was mainly excreted by the kidney, due to its hydrophilic properties that has been proved by the partition coefficient. The accumulation of the radiotracer in abdominal organs was low, and no uptake was found in the brain. In conclusion 68Ga labeled NODAGA-HPBCD was successfully produced for the first time and tested in vitro and in vivo. The synthesized NODAGA-HPBCD was characterized and labeled with 68Ga successfully. Overall, the outcome of our study indicates that the in vivo behavior of radiolabeled cyclodextrins can be examined by PET techniques, thus these derivatives are suitable for further pharmacokinetic measurements.

In Vivo Imaging of Experimental Melanoma Tumors using the Novel Radiotracer 68Ga-NODAGA-Procainamide (PCA).

PURPOSE: The most aggressive form of skin cancer is the malignant melanoma. Because of its high metastatic potential the early detection of primary melanoma tumors and metastases using non-invasive PET imaging determines the outcome of the disease. Previous studies have already shown that benzamide derivatives, such as procainamide (PCA) specifically bind to melanin pigment. The aim of this study was to synthesize and investigate the melanin specificity of the novel 68Ga-labeled NODAGA-PCA molecule in vitro and in vivo using PET techniques. METHODS: Procainamide (PCA) was conjugated with NODAGA chelator and was labeled with Ga-68 (68Ga-NODAGA-PCA). The melanin specificity of 68Ga-NODAGA-PCA was tested in vitro, ex vivo and in vivo using melanotic B16-F10 and amelanotic Melur melanoma cell lines. By subcutaneous and intravenous injection of melanoma cells tumor-bearing mice were prepared, on which biodistribution studies and small animal PET/CT scans were performed for 68Ga-NODAGA-PCA and 18FDG tracers. RESULTS: 68Ga-NODAGA-PCA was produced with high specific activity (14.9±3.9 GBq/µmol) and with excellent radiochemical purity (98%<), at all cases. In vitro experiments showed that 68Ga-NODAGA-PCA uptake of B16-F10 cells was significantly (p≤0.01) higher than Melur cells. Ex vivo biodistribution and in vivo PET/CT studies using subcutaneous and metastatic tumor models showed significantly (p≤0.01) higher 68Ga-NODAGA-PCA uptake in B16-F10 primary tumors and lung metastases in comparison with amelanotic Melur tumors. In experiments where 18FDG and 68Ga-NODAGA-PCA uptake of B16-F10 tumors was compared, we found that the tumor-to-muscle (T/M) and tumor-to-lung (T/L) ratios were significantly (p≤0.05 and p≤0.01) higher using 68Ga-NODAGA-PCA than the 18FDG accumulation. CONCLUSION: Our novel radiotracer 68Ga-NODAGA-PCA showed specific binding to the melanin producing experimental melanoma tumors. Therefore, 68Ga-NODAGA-PCA is a suitable diagnostic radiotracer for the detection of melanoma tumors and metastases in vivo.

In vivo imaging of Aminopeptidase N (CD13) receptors in experimental renal tumors using the novel radiotracer (68)Ga-NOTA-c(NGR).

PURPOSE: Aminopeptidase N (APN/CD13) plays an important role in tumor neoangiogenic process and the development of metastases. Furthermore, it may serve as a potential target for cancer diagnosis and therapy. Previous studies have already shown that asparagine-glycine-arginine (NGR) peptides specifically bind to APN/CD13. The aim of the study was to synthesize and investigate the APN/CD13 specificity of a novel (68)Ga-labeled NOTA-c(NGR) molecule in vivo using miniPET. METHODS: c[KNGRE]-NH2 peptide was conjugated with p-SCN-Bn-NOTA and was labeled with Ga-68 ((68)Ga-NOTA-c(NGR)). Orthotopic and heterotopic transplanted mesoblastic nephroma (NeDe) bearing Fischer-344 rats were prepared, on which biodistribution studies and miniPET scans were performed for both (68)Ga-NOTA-c(NGR) and ανß3 integrin selective (68)Ga-NODAGA-[c(RGD)]2 tracers. APN/CD13 receptor expression of NeDe tumors and metastases was analyzed by western blot. RESULTS: (68)Ga-NOTA-c(NGR) was produced with high specific activity (5.13-5.92GBq/µmol) and with excellent radiochemical purity (95%<), at all cases. Biodistribution studies in normal rats showed that uptake of the (68)Ga-NOTA-c(NGR) was significantly (p⩽0.05) lower in abdominal organs in comparison with (68)Ga-NODAGA-[c(RGD)]2. Both radiotracers were mainly excreted from the kidney. In NeDe tumor bearing rats higher (68)Ga-NOTA-c(NGR) accumulation was found in the tumors than that of the (68)Ga-NODAGA-[c(RGD)]2. Using orthotopic transplantation, metastases were developed which showed specific (68)Ga-NOTA-c(NGR) uptake. Western blot analysis confirmed the presence of APN/CD13 expression in NeDe tumors and metastases. CONCLUSION: Our novel radiotracer (68)Ga-NOTA-c(NGR) showed specific binding to the APN/CD13 expressed ortho- and heterotopic transplanted NeDe tumors. Therefore, (68)Ga-NOTA-c(NGR) is a suitable tracer for the detection of APN/CD13 positive tumors and metastases in vivo.

[Oral health-related quality of life associations to periodontal conditions]. / Az orális egészséghez kapcsolódó életminöség összefüggése a parodontális státusszal.

The clinical form and severity of periodontal of periodontal disorders may have negative effects on oral health related quality of life (OHQoL). The oral health impact profile questionnaire (OHIP-14) is the most frequently used instrument to evaluate the effects of intraoral disorders on the perception of well-being of patients. The modified OHIP-14 was used with 45 people (29 were in the chronic periodontitis and 16 in the control group) to evaluate the effects of periodontal conditions on OHQoL. In the periodontitis group significantly higher level of impact was observed in questions connected to aesthetics, psychological discomfort, physical pain and functional limitation. Higher periodontal probing depth was frequently associated with self-report of pain either in the anterior or posterior dental regions. There was also a significant correlation between the functional limitation and the number of missing teeth, the bleeding on probing and the probing depth. It is concluded that the periodontal disorders may have negative effects on certain parameters of OHQoL, hence during periodontal investigation the dental clinician should ask anamnestic questions in relation to quality of life.

[Chronological age estimation based on dental panoramic radiography]. / Kormeghatározás panoráma röntgenfelvételek alapján.

Determination of the dental age is a valuable tool in planning of orthodontic treatment and could be used to estimate the chronological age of unidentified human beings. Among the various age estimation methods one of the most accepted one is the Demirjian method, which has already been modified to selected Hungarian population. In this study we have evaluated the association between the dental age determined by panoramic radiography and the chronological age. 199 panoramic radiographs taken from persons between the ages of 2,8 and 20,3 years were selected to the study. The dental ages of persons were estimated either with the Demirjian or the modified Demirjian method adapted to Hungarian population and the results were compared to the chronological ages in selected age groups. Furthermore the angle of the mandible was registered on both sides with an image analysing software. Statistical analysis of data was performed using SPSS software. Our results show that mean values of mandibular angles exhibited a decreasing trend with age. The two age determination methods resulted in different values. Between 3 and 9 years and the age group between 15 and 17,3 years the adapted Hungarian method proved to be more accurate than the Demirjian method. We have established a mathematical function between the two methods. We could conclude that the panoramic radiography based dental age calculation is a reliable method to estimate the chronological age, but the utility of gonial angle has not been proved.

[Measurement of periapical pressure created by occlusal loading]. / A rágóeró keltette periapikális nyomás mérése.

The aim of this study was to develop an in vitro model in which the pressure in the periapical tissues can be measured during loading. Extracted human maxillary central incisors were embedded into resin blocks that had physical characteristics similar to bone and periodontal ligament. Each tooth was loaded with 20, 40, 50, 60, 75, 85, 100, 200, 300 and 450 N vertical forces from the incisal edge of the crown; this procedure was carried out three consecutive times. A minute resistor embedded in the periapical space was used to detect apical pressure changes during occlusal loading. The ratio of apical pressure changes (delta P) to the loading force changes (delta F) was calculated. The periapical pressure detected was in direct proportion to the loading force. The mean value of delta P/delta F was 5.994 kPa/N (SD = 2.04). Direct proportionality was found between the coronal loading and the apical hydrostatic pressure. The (delta P)/(delta F) ratio determined in this study makes it easier to estimate the apical hydrostatic pressure values during occlusal loading of single rooted teeth. In this study the apical pressure generated under occlusal loading was of the same magnitude as that estimated with the finite element method.

[Effect of long-lasting clenching on dental occlusion]. / Tartós rágóeró hatása a fogak érintkezésére.

Durable clenching on a particular occlusal area may affect the masticatory muscle activity and induce transitional deformation of the dentoalveolar, mandibular and temporomandibular tissues. These effects may provide detectable alterations in the occlusal contact pattern. The aim of this study was to evaluate the subsequent effect of clenching on the number and location of occlusal contacts. This study was carried out on 16 volunteers with correct occlusion and sharply demarcated occlusal contact pattern. The patient closed to intercuspal position with maximal biting force and the occlusal contacts were revealed with a 12 microns thick occlusal foil. Then a gnathometer was placed between the upper and lower incisors and the mouth was closed for two minutes with about 50 N closing force. After that the occlusal contacts were evaluated again. Paired t-test was used to evaluate the data. Both before and after clenching the highest average number of contacts was recorded on the surface of first molars. They were followed in decreasing order by the second molars, second premolars, first premolars, and finally the canines. When the number of contacts was compared in tooth groups, the first molars and the second premolars had more contacts than the second molars and the first premolars. On the surfaces of molars more occlusal contacts were registered after clenching than before. Significant differences were found in case of the left second molar only. It was concluded that durable clenching on a particular occlusal area might change transitionally the distribution of occlusal contacts.

[Diagnosis and therapy of temporomandibular disorders]. / A temporomandibuláris kórképek diagnosztikája és terápiája.

Temporomandibular disorders is a collective term covering a number of related disorders affecting the temporomandibular joints, masticatory muscles, and related structures. The study reviews the recent knowledge about the diagnosis and complex therapy of temporomandibular disorders on the basis of published scientific literature. The role of general dental practitioner in management of patients with temporomandibular disorders is emphasised. Since a lot of patients turn to them for a first consultation, they should be familiar with the main diagnostic aspects of these disorders. The non-invasive conservative therapeutic possibilities are described in detail and they are suggested in the initial phase of the treatment. The disorders, which usually need further consultations with other specialist, are also described.

[Effect of interocclusal records on the condylar path of the articulator]. / Regisztrációs anyagok hatása az artikulátor condylus sagittalis szögértékére.

Although there are studies on materials used for interocclusal records, there are no scientific data how the condylar path is influenced by the positional interocclusal records. The purpose of this in vitro study was to determine the effects of different interocclusal mediums on condylar inclination of the articulator. The materials selected for this experiment were: two addition type silicone pastes, two silicone putty materials and two waxes. The samples of protrusive records were performed on a Quick-Master semiadjustable articulator (FAG Dentaire). The same pre-established eminentia angles were used during the experiment for each type of materials. To improve the control of the condylar angles a protractor was mounted to the upper member of the articulator at right angels to each condylar fossa housing. A stylus moving simultaneously with the condylar fossa marked the eminentia angle on the protractor. 108 interocclusal records were performed and in 24 hours they were returned to the articulator. Then the articulator was adjusted and the settings of the eminentia angle were recorded. Numerical deviations between the pre-established and the adjusted settings in degrees were subjected to statistical analysis. The results indicated that these deviations for addition type silicones were significantly smaller than that of the other materials. The two waxes proved to be the least accurate materials. It is concluded that the condylar inclination is influenced by the properties of the registration materials, which may increase the shortcomings of the protrusive bite records.