Optical properties of white organic light-emitting devices fabricated utilizing a mixed CaAl12O19:Mn4+ and Y3Al5O12:Ce3+ color conversion layer

White organic light-emitting devices (OLEDs) were fabricated by combining a blue OLED with a color conversion layer made of mixed Y3Al5O12:Ce3+ green and Ca2AlO19:Mn4+ red phosphors. The X-ray diffraction patterns showed that Ce3+ ions in the Y3Al5O12:Ce3+ phosphors completely substituted for the Y3+ ions and the Mn4+ ions in the CaAl12O19:Mn4+ phosphors completely substituted for the Ca2+ ions. Electroluminescence spectra at 11 V for the OLEDs fabricated utilizing a color conversion layer showed that the Commission Internationale de l'Eclairage coordinates for the Y3Al5O12:Ce3+ and CaAl12O19:Mn4+ phosphors mixed at the ratio of 1:5 and 1:10 were (0.31, 0.34) and (0.32, 0.37), respectively, indicative of a good white color.

Loss of asymmetry in D2 receptors of putamen in unaffected family members at increased genetic risk for schizophrenia

OBJECTIVE

Dopamine dysregulation has been implicated in the pathophysiology of schizophrenia. The present study was performed to examine whether unaffected relatives at high genetic risk of schizophrenia have dopamine dysregulation in comparison with healthy controls.

METHOD

Eleven unaffected relatives from families with two or more first- or second-degree relatives with schizophrenia (n = 9) or with a monozygotic schizophrenic twin (n = 2) and 11 age- and sex-matched controls were examined using positron emission tomography (PET) with [(11)C] raclopride. Subjects also underwent extensive neuropsychological testing.

RESULTS

Subjects with high genetic risk showed a loss of asymmetry of D(2) receptors in the putamen in comparison with healthy controls. In addition, they showed significantly poorer performance on neuropsychological tests than controls.

CONCLUSION

Our results suggest that dopamine dysregulation and neuropsychological dysfunction may be present in subjects at high genetic risk of schizophrenia. However, further studies are required to confirm these findings.

Modeling of Brain D2 Receptor Occupancy-Plasma Concentration Relationships with a Novel Antipsychotic, YKP1358, Using Serial PET Scans in Healthy Volunteers

YKP1358 is a novel serotonin (5-HT(2A)) and dopamine (D(2)) antagonist that, in preclinical studies, fits the general profile of an atypical antipsychotic. We conducted a D(2) receptor occupancy study with YKP1358 in healthy volunteers using positron emission tomography (PET) to measure the D(2) receptor occupancy of YKP1358 and to characterize its relationship to plasma drug concentrations. A single oral dose, parallel group, dose-escalation (100, 200, and 250 mg) study was performed in 10 healthy male volunteers with the PET radiotracer [(11)C]raclopride. The D(2) receptor occupancy of striatum was measured pre-dose, and at 2, 5, and 10 h after YKP1358 administration. Serial blood samples were taken for measurement of plasma YKP1358 concentrations. D(2) receptor occupancy by YKP1358 increased to 53-83% at 2 h, and then decreased afterwards, ranging from 40-64% at 5 h to 20-51% at 10 h. The YKP1358 dose-plasma concentration relationship exhibited extensive variability, but there was a good relationship between plasma concentrations and D(2) receptor occupancy that was well predicted by a sigmoid E(max) model using nonlinear mixed effects modeling. To our knowledge, this is the first study in which the relationship between plasma concentration and the biomarker of D(2) receptor occupancy was modeled using nonlinear mixed effects modeling. It is anticipated that these results will be useful in estimating for subsequent studies the initial doses of YKP1358 required to achieve a therapeutically effective range of D(2) receptor occupancy.

Changes of 2-deoxyglucose uptake in the rat auditory pathway after bilateral ablation of the cochlea

It has been reported that the area of decreased glucose metabolism in the FDG-PET of prelingually deaf children correlates significantly with speech performance after cochlear implantation. In this study, we undertook to confirm changes of glucose metabolism in the cerebral cortex using an animal model with age-matching groups to completely exclude the influence of age differences between the deaf and normal-hearing groups. The cochlea was ablated bilaterally at a postnatal 10-14 days in the deaf groups; 3-4 deaf and normal rats were included at each time point at 1, 2, 4 and 8 weeks and 7 months after ablation. After injecting 2-deoxyglucose intraperitoneally, digitalized autoradiographic images were obtained, and analyzed by using two different methods; 3-dimensional voxel-wise statistical analysis and conventional 2-dimensional densitometry. The hypometabolic area analyzed using 3-dimensional analysis and the differences of optical density between normal and deaf as determined by densitometry were widest and most prominent between 4 and 8 weeks after ablation. Differences were not significant before 2 weeks or after 7 months after ablation. This result shows that the hypometabolic area becomes prominent after a critical period and it decreases as the duration of deafness increases. We believe that cross-modal plasticity may be the mechanism of changes in glucose metabolism and that this result reinforced the usefulness of evaluating hypometabolic area using FDG-PET in deaf children.

Comparison of [18F]fluorodeoxyglucose uptake with glucose transporter-1 expression and proliferation rate in human glioma and non-small-cell lung cancer

To clarify the biological significance of [18F]fluorodeoxyglucose (18F-FDG) accumulation in patients with cancer, we assessed the relationships between 18F-FDG uptake and glucose transporter-1 (GLUT-1) expression and proliferation rate in human glioma and lung cancer. We obtained FDG PET images and measured standardized uptake values (SUVs) of primary tumours in 13 patients with brain glioma and 25 patients with non-small-cell lung cancer. After surgery, portions of respected tumours were obtained, and the proliferation rate was measured as proliferation index (per cent of (S+G2+M)/(G0+G1+S+G2+M)) using DNA flow cytometry. The expression of GLUT-1 in a tumour was evaluated by using immunostaining. We classified GLUT-1 expression as grade 0 (no positive cell), grade 1 (< 10% cells positive), grade 2 (11-50% cells positive) and grade 3 (51-100% cells positive). Based on the expression of GLUT-1, cases with grades 0, 1, 2 and 3 showed SUVs of 6.1 +/- 2.8, 5.0 +/- 3.2, 8.3 +/- 3.3 and 10.4 +/- 6.6, respectively (P < 0.05). Non-small-cell lung cancer showed higher FDG uptake (SUV, 8.5 +/- 5.1) and higher GLUT-1 expression (grade, 2.0 +/- 1.0) than did brain glioma (SUV, 4.7 +/- 2.5; grade, 0.8 +/- 0.8). Based on the total number of cases, SUVs did not relate to proliferation index (r = 0.19). In non-small-cell lung cancer, SUVs did not correlate with proliferation index, whereas in glioma, SUVs were strongly related to proliferation index (r = 0.79, P < 0.01). In conclusion, FDG uptake generally correlated with GLUT-1 expression in non-small-cell lung cancer and glioma. In the case of glioma, FDG uptake also indicated increased cellular proliferation, which was not demonstrated in non-small-cell lung cancer.

188Re-tin-colloid as a new therapeutic agent for rheumatoid arthritis

Radiation synovectomy is a useful treatment modality in patients with refractory synovitis. We have developed a 188Re-tin-colloid as a new radiopharmaceutical agent and investigated its efficacy and safety in patients with rheumatoid arthritis. Radiation synovectomy was performed using 188Re-tin-colloid in 22 knees from 21 rheumatoid arthritis patients refractory to intra-articular corticosteroid injection. The efficacy and safety of administration of 370-1110 MBq of 188Re-tin-colloid were evaluated after 1, 3, 6, 9 and 12 months. Pain intensity on a visual analogue scale decreased significantly 12 months after therapy (mean+/-SD: 68.0+/-26.1 mm vs. 25.1+/-23.4 mm; P=0.0001 by the paired t-test). Pain decreased in 19 cases (86.3%), joint tenderness improved in 14 cases (63.6%) and joint swelling was reduced in all cases (100%). 188Re-tin-colloid was safe. The residual activity of 188Re in the blood was 0.077%+/-0.25% of the injected dose. The radioactivity of 188Re in the urine was 0.14%+/-0.13% of the injected dose. Transient reactive synovitis was observed in 18 cases (81.8%). No clinical side-effects or abnormalities in leucocyte count, platelet count, liver function tests or urine analysis were observed in any patient. In conclusion, in this first study of radiation synovectomy using 188Re-tin-colloid for patients with rheumatoid arthritis, the treatment resulted in the improvement of arthritis and was well tolerated.

Determination of the prognostic value of [(18)F]fluorodeoxyglucose uptake by using positron emission tomography in patients with non-small cell lung cancer

The aim of this study was to determine whether quantitative information obtained from [(18)F]fluorodeoxyglucose positron emission tomography ((18)F-FDG PET) has a prognostic significance for patients with non-small cell lung cancer (NSCLC). We investigated (18)F-FDG PET imaging of 73 patients with NSCLC. The maximum standardized uptake value (SUV(max)) was significantly different between the histopathological types of tumour (squamous cell carcinoma (n=37, 12.4+/-5.1), adenocarcinoma (n=30, 8.2+/-5.8), bronchioloalveolar carcinoma (n=4, 2.6+/-1.7), <0.01). In the univariate analysis of all patients, staging (P=0.0001), tumour cell type (P=0.013), and a SUV(max) greater than 7 (P=0.0011) was correlated with survival. However, a multivariate analysis identified staging and SUV(max) greater than 7 were affected survival adversely. The mortality rate of patients with group I disease (stage I to stage IIIA) was 5.8 times lower than that of patients with group II disease (stage IIIB to stage IV). Patients with a high SUV(max) (> or =7) had a 6.3 times higher mortality than those with a low SUV(max)(<7). By multivariate analysis of patients with squamous cell carcinoma, only grouping affected survival (P=0.008, relative risk=4.3). In the case of adenocarcinoma, the SUV(max) (>10) correlated exclusively with poorer survival (P=0.031, relative risk=11.152). (18)F-FDG uptake correlated with survival in NSCLC. Especially in adenocarcinomas, the SUV(max) was complementary to other known prognostic factors.

Synthesis of 188 Re-labelled long chain alkyl diaminedithiol for therapy of liver cancer

Radioisotope-labelled lipiodol has been used in the therapy of liver cancer. Recently a lipiodol solution of 188Re-labelled diaminedithiol (DD) has been reported to show a high uptake in the liver cancer. We synthesized long-chain alkyl DD derivatives to improve their uptake and retention in tissue. As the length of the alkyl chain increased, tissue uptake and retention also increased due to hydrophobic interaction with lipiodol. Among the synthesized compounds, the lipiodol solution of 188Re-HDD, the DD derivative with the longest side chain (C16), is a promising agent for therapy of liver cancer.

Preparation and biological evaluation of 188Re-ethylenediamine-N,N,N',N'-tetrakis(methylene phosphonic acid) as a potential agent for bone pain palliation

This study was undertaken in order to prepare 188Re labelled ethylenediamine-N,N,N',N'-tetrakis(methylene phosphonic acid) (EDTMP), and to determine its potential as a therapeutic radiopharmaceutical for the palliation of metastatic bone pain. The effects of pH, incubation methods, and concentrations of stannous chloride, EDTMP, and ammonium perrhenate as a carrier on radiochemical yield and stability were evaluated. Biodistribution studies were performed in male Wistar rats after intravenous injection of 188Re-EDTMP and compared with those of hydroxyethylidene diphosphonate (HEDP). Greater than 95% radiochemical yield of 188Re-EDTMP was obtained under the optimal conditions (0.1 mmol x ml(-1) of EDTMP, 0.5 mg x ml(-1) of stannous chloride, and pH 1.0). Heating the reaction mixture (boiling water for 15 min, and microwave heating for 15 s) and the addition of ammonium perrhenate increased the radiochemical stability (>90% at 3 h, and >80% at 48 h). The biodistribution of 188Re-EDTMP showed high bony uptake and rapid clearance from other organs, and high bone-to-soft tissue ratios, which are similar to 188Re-HEDP. In conclusion, 188Re-EDTMP was prepared with high radiochemical yield and stability, and showed favourable biological characteristics. Microwave heating was a convenient and rapid method for the preparation of 188Re-EDTMP. It is considered that 188Re-EDTMP is a potential therapeutic agent for bone metastasis.

188rhenium-TDD-lipiodol in treatment of inoperable primary hepatocellular carcinoma--a case report

INTRODUCTION

The aim of this study was to investigate the potential of using 188Re Lipiodol for selective internal radiation therapy of inoperable hepatocellular carcinoma (HCC).

CLINICAL PICTURE

A 33-year-old female with poorly-differentiated multicentric HCC, elevated alpha-fetoprotein (AFP) and increased serum alkaline phosphatase.

TREATMENT

Over a 2-month interval, the patient was treated twice with 4GBq of 188Re-TDD-Lipiodol.

OUTCOMES

There was good localisation of 188Re Lipiodol in the tumours, but also in thyroid (first treatment) and gastrointestinal tract (both treatments). So far (5 months post-treatment), the patient remains well with stable disease.

CONCLUSIONS

188Re Lipiodol can be an effective radiopharmaceutical for the treatment of HCC; however, more work must be done to minimise the uptake in bowel.

Relationship between expression of the sodium/iodide symporter and 131I uptake in recurrent lesions of differentiated thyroid carcinoma

The sodium/iodide symporter (NIS) is known to be responsible for the active accumulation of iodide within the thyroid gland. We evaluated the relationship between the expression of NIS in primary or lymph node lesions and iodine-131 uptake in recurrent lesions of differentiated thyroid cancer. In 67 patients with differentiated thyroid cancer (5 follicular and 62 papillary carcinomas), the expression of NIS was analysed by immunohistochemical staining using polyclonal antibodies against human NIS. We used paraffin block tissues of primary tumours or metastatic lesions, and also assessed 131I uptake in recurrent lesions of thyroid cancer on post-operative 131I whole-body scan. Immunohistochemical staining was positive in 22 patients (32.8%), including 2 of 5 follicular and 20 of 62 papillary carcinomas. Recurrence was confirmed in 40 patients pathologically or clinically by serum thyroglobulin, 131I scan, fluorine-18 fluorodeoxyglucose positron emission tomography and/or computed tomography. Among these 40 patients, 28 showed positive uptake on 131I scan. Fourteen tumour specimens out of 28 (50%) were positive by NIS immunohistochemical staining. The remaining 12 patients with recurrent cancer showed negative 131I scans, and all specimens were negative by NIS immunohistochemical staining. Thus, NIS immunohistochemical staining predicted 131I uptake in recurrent cancer with a 100% positive predictive value and a 46.2% negative predictive value. There was no difference in the positivity of NIS according to the site of recurrence on 131I scan. Outcome of 131I therapy could be assessed in 22 of the 28 patients who showed 131I uptake in recurrent lesions. Patients with positive NIS immunostaining responded to 131I therapy better than did patients with negative immunostaining (P<0.05). In conclusion, NIS immunohistochemical staining showed a high positive predictive value in predicting iodine uptake. Positive immunohistochemical staining of human NIS in primary or lymph node lesions may predict 131I accumulation and effectiveness of 131I therapy in recurrent lesions.

Lipiodol solution of a lipophilic agent, (188)Re-TDD, for the treatment of liver cancer

Radiolabeled lipiodol has been used for targeting liver cancer. We developed a lipiodol solution of (188)Re-TDD (2,2,9,9-tetramethyl-4,7-diaza-1,10-decanedithiol) and investigated its feasibility for the treatment of liver cancer. The lipiodol solution of (188)Re-TDD was well-retained in the lipiodol phase in vitro. After injection through the tail veins of mice, high lung-uptake was investigated which is evidence of embolizing activity. We also found high accumulation in hepatoma after injection through the hepatic arteries of hepatoma-bearing rats. In conclusion, the lipiodol solution of (188)Re-TDD is a promising agent for liver cancer therapy.

Preparation of rhenium-188-tin colloid as a radiation synovectomy agent and comparison with rhenium-188-sulfur colloid

As a generator-produced beta-emitting radionuclide, the importance of 188Re for radionuclide therapy is increasing rapidly. We prepared 188Re-tin colloid and compared its properties with 188Re-sulfur colloid. Labeling efficiencies reached >98% for tin colloid at 2 h and 89-94% for sulfur colloid at 3 h. All the preparations were stable for 72 h in water, serum, and synovial fluid. If labeled at higher temperature, the particle size of tin colloid increased. The residual radioactivity of 188Re-sulfur colloid in disposable polypropylene syringes after injecting mice was high (62.0+/-7.0%) due to its hydrophobic nature, while that of 188Re-tin colloid was low (2.9+/-1.6%). Although both 188Re-tin colloid and 188Re-sulfur colloid might be useful for radionuclide therapy, we conclude that 188Re tin colloid is more advantageous over 188Re sulfur colloid, due to higher labeling efficiency, control of the particle size, and lower residual activity in the injection syringes.

Amniotic membrane patching promotes healing and inhibits proteinase activity on wound healing following acute corneal alkali burn

Amniotic membrane (AM) contains basement membrane components and various proteinase inhibitors. Furthermore, when used as a graft, the basement membrane of AM could block inflammatory insults to a damaged corneal surface. Thus, we evaluated whether amniotic membrane patching could promote the healing process by inhibiting proteolytic damage. Alkali wounds were inflicted on the central corneas of rabbits by applying a round filter paper, 6.0 mm in diameter, soaked in 1 N NaOH for 30 sec. Amniotic membrane patching was performed over the perilimbal sclera immediately after wounding. A total of 115 rabbits were divided into four groups: (1) immediately covered by AM with the amnion cell side down up to the perilimbal sclera (n =26); (2) covered by AM with the stromal side down up to the perilimbal sclera (n =19); (3) anchored to the fornix (n =29); and (4) uncovered as a control (n =41). AM was removed 3 days postoperatively. During follow-ups, epithelial defects, corneal thickness and its opacity of each eye were measured. Some corneas were removed for histopathologic studies and for proteinase activity assay and zymography. The epithelial healing was faster and the corneal thickness was thicker in all three AM-covered groups than in the control (P<0.05). No significant difference was found between covered and anchored groups (P>0.05). Corneal opacity was least in the amnion cell side down group. Infiltration of polymorphonuclear leukocytes (PMNs) was much less in AM-covered groups than in the control. Pathological results were associated with zymographic findings, which revealed much higher proteinase activity in uncovered group than AM-covered groups. Immediate intervention for acute alkali burns with AM as a temporary patch promotes wound healing by inhibiting proteinase activity and PMNs infiltration.

Dosimetry of rhenium-188 diethylene triamine penta-acetic acid for endovascular intra-balloon brachytherapy after coronary angioplasty

To examine the possibility of using rhenium-188 diethylene triamine penta-acetic acid (DTPA) for endovascular intra-balloon brachytherapy after angioplasty, dose distribution around the balloon was calculated and validated by film dosimetry. Medical internal radiation dosimetry (MIRD) was calculated assuming that the balloon had ruptured and that the contents had been released into the systemic circulation. 188Re-perrhenate eluate from the 188W/188Re generator was concentrated using an ion column and used to label DTPA. The dose distribution around the angioplasty balloon (20 mm length, 3 mm diameter cylinder) was estimated by Monte Carlo simulation using the EGS4 code. The time required for 17.6 Gy to be absorbed at 1 mm from the balloon's surface following application of 3700 MBq/ml of 188Re was found to be 278 s. Fifty percent of the energy was deposited in the first millimetre of the vessel wall from the balloon's surface. The calculated radiation absorbed dose agreed with that measured by film dosimetry, which was performed using a water phantom, with errors ranging from 9.4% to 17%. Upon balloon rupture the total amount of 188Re-DTPA was presumed to enter the systemic circulation. The resulting radiation absorbed dose was calculated using the MIRDOSE3 program and residence times obtained from dogs and amounted to 0.0056 mGy/MBq to the whole body and 4.56 mGy/MBq to the urinary bladder. The absorbed dose of 188Re-DTPA to the whole body was one-tenth of that of 188Re-perrhenate. A window-based program was developed to calculate the exposure time and the radiation dose absorbed as a function of the 188Re concentration and the arbitrary distance from the balloon to the surrounding tissues. We conclude that 188Re-DTPA is easy to prepare, safe to use and suitable for intra-balloon brachytherapy after coronary angioplasty.

The effect of tumor size on F-18-labeled fluorodeoxyglucose and fluoroerythronitroimidazole uptake in a murine sarcoma model

The purpose of this study was to evaluate the effect of tumor size on the uptake of 18F-fluorodeoxyglucose (FDG) and fluoroerythronitroimidazole (FETNIM) in a murine sarcoma model. ICR mice were xenografted with sarcoma 180 cell line and tumors were allowed to grow to a weight of 0.26-5.82 grams. 18F-FDG and 18F-FETNIM were injected intravenously in separate groups of mice, and after 1 hr, the tumors were excised and radiotracer uptake was measured. In another group of mice tumors were autoradiographically analyzed and subjected to H & E staining. In both the FDG and FETNIM group, per-gram radiotracer uptake by a tumor was inversely proportional to tumor weight. 18F-FETNIM correlated more (r = -0.593, p < 0.05) than 18F-FDG (r = -0.447, p < 0.05). Autoradiographic studies revealed that FDG accumulated in viable tumor areas, whereas FETNIM accumulated in both viable and partially necrotic areas. In the case of 18F-FETNIM, a direct correlation between tumor weight and the no-uptake-area to total-tumor-area was demonstrated. We concluded that increased tumor size is associated with decreased uptake of 18F-FDG and FETNIM, though this depends on the type of radiotracers and distribution of necrosis.

Mechanisms related to [18F]fluorodeoxyglucose uptake of human colon cancers transplanted in nude mice

[18F]Fluorodeoxyglucose ([18F]FDG), a glucose analogue, has been widely used for tumor imaging. To investigate the mechanisms related to [18F]FDG uptake by tumors, an experiment involving nude mice was performed.

METHODS

Human colon cancer cell lines SNU-C2A, SNU-C4 and SNU-C5 were transplanted to nude mice. Using immunohistochemical staining and Western blot, the expression of glucose transporter (Glut) isoforms (Glut-1 through -5) in xenografted tumors was analyzed. For the analysis of messenger ribonucleic acid (mRNA) expression, reverse-transcription polymerase chain reaction and Northern blot were used and the enzyme activity of hexokinase in cancer tissues was measured by continuous spectrophotometric rate determination.

RESULTS

[18F]FDG uptake in SNU-C4 and SNU-C5 cells was higher than in normal colon cells. Among these cells and xenografted tumors, SNU-C5 showed the highest level of [18F]FDG uptake, followed by SNU-C4 and SNU-C2A. An immunostaining experiment showed intense staining of Glut-1 in SNU-C5 tumors but somewhat faint staining in SNU-C4. SNU-C5 tumors also showed positive staining with Glut-3, although this was not the case with SNU-C2A and SNU-C4. Western blot analysis showed the expression of Glut-1 and Glut-3 in all tumors. Experiments involving Northern blot analysis and reverse-transcription polymerase chain reaction confirmed the overexpression of Glut-1 mRNA in all tumors, with the highest level in SNU-C5. The level of Glut-3 mRNA was also elevated in SNU-C5 tumors but not in SNU-C2A and SNU-C4. The enzyme activity of hexokinase did not vary among different tumors.

CONCLUSION

Gluts, especially Glut-1, are responsible for [18F]FDG uptake in a nude mouse model of colon cancer rather than hexokinase activity. Increased numbers of glucose transporters at the plasma membrane of cancer cells is attributed to an increased level of transcripts of glucose transporter genes and may be a cause of increased [18F]FDG uptake, at least in colon cancer tumors.

Dopamine transporter imaging with [123I]-beta-CIT demonstrates presynaptic nigrostriatal dopaminergic damage in Wilson's disease

OBJECTIVES

The most common neurological manifestations in Wilson's disease are parkinsonism and dystonia. These are assumed to be due to striatal injury, which has been repeatedly demonstrated by pathology and CT or MRI. The substantia nigra has not been shown to be damaged in pathological studies. However, there have been clinical and imaging studies suggesting presynaptic nigrostriatal injury. (1r)-2Beta-carbomethoxy-3beta-(4-iodophenyl)tropane (beta-CIT) is a specific ligand that binds to the dopamine transporter (DAT), and can examine the integrity of dopaminergic nerve terminals. Evidence for presynaptic nigrostriatal dopaminergic damage in Wilson's disease was searched for using [123I]-beta-CIT SPECT.

METHODS

Six patients with Wilson's disease were studied, together with 15 healthy normal controls, and six patients with Parkinson's disease. After injection of [123I]-beta-CIT, SPECT studies were done at 18 hours. Specific striatal/occipital binding ratio (S/O ratio) was calculated as (striatal binding-occipital binding)/occipital binding.

RESULTS

The specific S/O ratios were 6.22 (1.32) (mean (SD)) in normal volunteers, 3.78 (0.65) in Parkinson's disease, and 3.60 (0.49) in Wilson's disease.

CONCLUSION

There was severe loss of the DAT in the striatum suggesting significant damage in presynaptic nigrostriatal dopaminergic nerve terminals. Therefore, a presynaptic lesion may contribute to neurological manifestations in Wilson's disease.

Dopamine transporter density measured by [123I]beta-CIT single-photon emission computed tomography is normal in dopa-responsive dystonia

The clinical distinction between dopa-responsive dystonia (DRD) and juvenile Parkinson's disease JPD) can pose a diagnostic challenge. Both conditions are dopa responsive. However, long-term L-dopa benefit is very different between the two. The difference in the prognosis is due to presence or absence of nigral cell loss. In JPD, there is degenerative nigral cell loss, whereas there are enzymatic defects in dopamine synthesis without cell loss in DRD. Mutations have been found in the GTP cyclohydrolase I (GCH-I) and tyrosine hydroxylase genes in DRD. As the discovered mutations are multiple and more are expected to be found, it is difficult to confirm or exclude DRD by mutation studies. Measurement of cerebrospinal fluid (CSF) neopterin will detect DRD from mutations in the GCH-I gene but not from mutations in tyrosine hydroxylase. The dopamine transporter (DAT) is a protein in the dopaminergic nerve terminals. (1R)-2beta-Carbomethoxy-3beta-(4-[123I]iodophenyl)tropane ([123I]beta-CIT) is a ligand for the DAT, and it was shown to be a useful nuclear imaging marker for neurons that degenerate in Parkinson's disease (PD). As DRD was shown to have a normal DAT without nigral cell loss in a postmortem study, we predicted that the DAT measured in vivo by nuclear imaging will be normal in DRD and will differentiate DRD from JPD. Therefore, we performed [123I]beta-CIT single-photon emission computed tomography ([123I]beta-CIT SPECT) in clinically diagnosed DRD, PD, and JPD, and examined whether DAT imaging can differentiate DRD from PD and JPD. We then examined whether DAT imaging can provide a screening tool for molecular genetic studies, by studying mutations in the candidate gene GCH-I and measuring CSF neopterin. Five females (4 from two families, and 1 sporadic) were diagnosed as DRD based on early-onset foot dystonia and progressive parkinsonism beginning at ages 7 to 12. All patients were functioning normally on L-dopa 100 to 250 mg/day for up to 8 years. SPECT imaging was obtained after intravenous injection of [123I]beta-CIT; 15 healthy volunteers served as normal control, and 6 PD and 1 JPD as disease controls. [123I]beta-CIT striatal binding was normal in DRD, whereas it was markedly decreased in PD and JPD. Gene analysis showed a novel nonsense mutation in the GCH-I gene in one family. No mutation was found in the other family or in the sporadic case. CSF neopterin was markedly decreased in the 4 tested patients. [123I]beta-CIT SPECT is a sensitive method for probing the integrity of nigrostriatal dopaminergic nerve terminals. A normal striatal DAT in a parkinsonian patient is evidence for a nondegenerative cause of parkinsonism and differentiates DRD from JPD. Finding a new mutation in one family and failure to demonstrate mutations in the putative gene in other cases supports the usefulness of DAT imaging in diagnosing DRD.

Clinical significance of hepatic visualization on iodine-131 whole-body scan in patients with thyroid carcinoma

The purpose of this study was to evaluate the frequency and clinical significance of diffuse hepatic uptake on 131I whole-body scan in 399 patients (53 males, 348 females) with well-differentiated adenocarcinomas of the thyroid.

METHODS

Two hundred and ninety-one diagnostic scans were performed 2 days after the administration of 74-370 MBq (2-10 mCI) 131I, and 824 post-therapy scans were done 3-5 days after the administration of 1.11-7.4 GBq (30-200 mCI) 131I. There was no evidence of liver metastasis in these patients. Liver and thyroid visualization on each 131I scan were graded from 0-4. To evaluate the incorporation of radioiodine to thyroglobulin and thyroid hormones, a patient's serum was extracted by 80% ethanol/20% trichloroacetic acid solution and analyzed by silica gel thin-layer chromatography.

RESULTS

Diffuse hepatic uptake (> Grade 2) was definitely seen in 239 of 399 (59.9%) of the patients and 397 of 1115 (35.6%) of the studies. In the diagnostic scans, 36 (12.0%) showed uptake in the liver. In post-therapy scans, however, the incidence of liver uptake increased according to increased doses of 131I (39.1% with 1.11 GBq, 61.5% with 2.775-3.7 GBq and 71.3% with 5.55-7.4 GBq). The more that uptake appeared in the residual thyroid, the more it appeared in the liver. There were 13 patients whose scans showed metastatic and liver uptake without any thyroid uptake. Fifteen patients showed diffuse liver uptake without uptake by the thyroid or metastasis. Follow-up studies of seven of these patients revealed metastatic lesions. Liver uptake on scan related to the fraction of 131I-labeled thyroglobulin in the serum.

CONCLUSION

Diffuse liver uptake indicated functioning thyroid remnant or metastasis. In a few cases, liver uptake without uptake by the thyroid or metastasis on whole-body scans suggests hidden metastases.

In vitro and in vivo properties of murine monoclonal antibody for a novel immature thymocyte-differentiated antigen, JL1

JL1 is a novel thymocyte-differentiated antigen strictly confined to stage II immature cortical thymocytes. It is expressed in several types of leukemias and lymphomas. Murine anti-JL1 monoclonal antibody labeled with 131I and 99mTc showed 60-70% of immunoreactivity and 1.4-1.9 x 10(9) L/mol of affinity constant. The incubation of the radiolabeled antibody with Molt-4 cells showed no evidence of modulation or shedding. Localization indices increased from day 3 to day 5 in SCID mice bearing Molt-4 cells.

Technetium-99m-labeled antigranulocyte antibody bone marrow scintigraphy

Although bone scintigraphy is a sensitive method for detecting skeletal metastases, it is often equivocal for metastases due to poor specificity. This study evaluates 99mTc-antigranulocyte antibody (AGA) bone marrow scintigraphy in differentiating malignant from benign lesions, in 42 patients with skeletal tumors who had equivocal bone scans.

METHODS

AGA scans performed approximately 1 wk after 99mTc-MDP bone imaging were visually assessed for the presence of concordant marrow defects. Final diagnoses were made from radiological results, follow-up bone scans or clinical evaluation for 12 mo or longer.

RESULTS

The final diagnoses were: skeletal metastasis (19 patients), no metastasis (20 patients) and unconfirmed (3 patients). AGA scans could not determine the presence of a concordant defect in three patients because of overlying liver activity or previous irradiation of the region. Seventeen patients had bone marrow defects concordant with bone scan lesions, whereas 15/19 patients without metastasis had normal AGA scans. The sensitivity and specificity of AGA for detecting skeletal metastases were 100% and 79%, respectively.

CONCLUSION

AGA scans had a low incidence of skeletal metastases in patients who had equivocal bone scans. Although a concordant marrow defect increases the possibility of metastasis, further radiological investigation to exclude benign disease is warranted.

The fibronectin-binding domain of transglutaminase

Guinea pig liver transglutaminase (EC 2.3.2.13) displays a Ca(2+)-independent binding (Ka = 10(7) M-1) to the same gelatin-binding domain of human plasma fibronectin that is known to form a very tight complex with the human red cell enzyme. The fibronectin-combining site of the liver transglutaminase was investigated by testing fragments obtained from the parent protein by controlled digestion with endoproteinase Lys-C. Overlay assays, probed with anti-fibronectin antibody, revealed that the fibronectin binding ability of the transglutaminase was encoded in a linear sequence in its 28-kDa N-terminal domain. Removal of the first 7 residues by further digestion of the purified 28-kDa material with endoproteinase Glu-C generated a 27-kDa fragment that, however, showed no binding activity. Thus, residues 1-7 in the liver enzyme seem to be of particular importance for influencing its ability to bind to fibronectin.

Effect of metabolism on retention of indium-111-labeled monoclonal antibody in liver and blood

The effect of a chelator structure on the metabolic fate of the 111In-labeled monoclonal antibody (Mab) T101 was investigated in normal Balb/c mice to assess the importance of this chemical parameter in the reduction of the background radioactivity in blood and liver.

METHODS

Mab T101 was conjugated with either 2-(p-isothiocyanatobenzyl)-6-methyl-diethylaminetriaminepentaac etic acid (DTPA) (1B4M), 2-(p-isothiocyanatobenzyl) cyclohexyl-DTPA (CHX-B) or cyclic DTPA dianhydride (cDTPA) and then radiolabeled with 111In. Normal mice were injected intravenously with these 111In-labeled T101 conjugates and sacrificed in groups of five up to 5 days postinjection for comparative biodistribution studies and analyses of liver, blood and urine samples for radioindium products.

RESULTS

The biodistribution of 111In-1B4M-T101 and 111In-CHX-B-T101 were similar to each other but significantly different from that of 111In-cDTPA-T101, particularly in the blood and liver. Size-exclusion high-performance liquid chromatography indicated that the concentration of the intact 111In-immunoglobulin (Ig)G in liver decreased with similar rates for the three conjugates. Meanwhile, the concentration of a small DTPA-like metabolite in liver increased to a different peak value (4.6% ID/g for the cDTPA conjugate and 1.6% ID/g for the 1B4M and CHX-B conjugates) approximately at 24 hr and maintained a steady-state concentration up to 5 days.

CONCLUSION

The thiourea linkage between T101 and the 111In-labeled chelates and a higher complex stability and higher lipophilicity of 111In-1B4M and 111In-CHX-B appear to be responsible for lower liver and higher blood radioactivity for the 1B4M and CHX-B conjugates.

Application of high affinity binding concept to radiolabel avidin with Tc-99m labeled biotin and the effect of pI on biodistribution

In order to label avidin with Tc-99m, we took advantage of the high affinity binding of biotin to avidin; we radiolabeled a biotin derivative with Tc-99m and then bound this Tc-99m labeled biotin derivative to avidin. For our labeling approach, N epsilon-biotinyl-L-lysine (Biocytin) was reacted with the N-hydroxy-succinimide ester of benzoylmercaptoacetyltriglycine (Bz-MAG3). The resulting Bz-MAG3-Biocytin was labeled with Tc-99m using Tc-99m glucarate as a Tc-99m transchelating agent and mixed with avidin at a 1:1 molar ratio resulting in almost a quantitative labeling yield. Tc-99m-MAG3-Biocytin/Avidin was stable in serum at 37 degrees C with 97 and 95% of the total Tc-99m activity still bound to avidin at 2 and 24 h, respectively. The biodistribution of Tc-99m-MAG3-Biocytin/Avidin in normal Balb/c mice showed a high liver and kidney uptake with 56.6 and 28.9%, respectively at 10 min. We attempted to lower the liver and the kidney activities by reducing the isoelectric point (pI) of avidin by conjugating succinic acid moieties at lysine residues of avidin (pI 10). The kidney uptake decreased to 19.0, 3.1 and 1.7% when the pI of avidin was reduced to 7.0-9.3, 5.5-6.2 and 4.0-4.8, respectively. The lowering of the pI, however, did not change the liver activity appreciably.

Two-step targeting of experimental lung metastases with biotinylated antibody and radiolabeled streptavidin

Two-step monoclonal antibody tumor targeting using an avidin-biotin system has unique characteristics because of the high-affinity binding (10(15) M-1) and the lower molecular weight ligands (avidin, streptavidin, or biotin) used as carriers of radioisotopes, toxins, or drugs. The distribution of radiolabeled streptavidin in a two-step targeting strategy was investigated in lung metastases of line 10 carcinoma in guinea pigs. The microdistribution of administered D3 monoclonal antibody and 125I-labeled streptavidin in metastatic nodules was examined by immunohistochemistry and autoradiography, and the uptake was quantitated. With monoclonal antibody pretargeting, streptavidin was found mainly at the periphery of metastatic nodules 1.5 h after injection; it had penetrated deeper at 4 h and was approaching homogeneity in many of the tumor nodules at 24 h. These results indicate that streptavidin can penetrate into metastatic nodules more rapidly than can the antibody. The concentration of streptavidin in metastatic nodules 4 h after injection was 5.6 times higher for the pretargeted group than for the nonpretargeted group, and the pretargeting index was 4.7. Although the absolute uptake of streptavidin had decreased between 4 and 24 h, the metastasis:blood ratio had increased from 1.2 to 2.4. When compared with the animals injected with 125I-labeled D3 antibody alone, the pretargeted group achieved higher tumor:blood and tumor:lung ratios and a higher localization index at early times after injection of the radiolabeled species.

Affinity of human erythrocyte transglutaminase for a 42-kDa gelatin-binding fragment of human plasma fibronectin

Complex formation between the human erythrocyte transglutaminase (protein-glutamine:amine gamma-glutamyltransferase, EC 2.3.2.13) and fibronectin or its fragments was examined by immunoanalytical procedures and by fluorescence polarization. A 42-kDa gelatin-binding structure, obtained from human plasma fibronectin by thermolytic digestion, showed as high an affinity for the cytosolic enzyme as the parent fibronectin chains themselves. A 21-kDa fragment comprising type I modules 8 and 9, the last two modules in the 42-kDa fragment, bound with an affinity 100-fold less than the 42-kDa fragment. Binding was remarkably specific and could be exploited for the affinity purification of transglutaminase directly from the hemoglobin-depleted erythrocyte lysate. In spite of the high affinity, it was possible to elute active enzyme from the 42-kDa fragment column with 0.25% monochloroacetic acid. This solvent might have general applicability in other systems involving separation of tightly bound ligands.

Association of the A subunits of recombinant placental factor XIII with the native carrier B subunits from human plasma

Interactions of a recombinant human placental protein (rA2) expressed in yeast and considered to be identical to the catalytic A2 subunits of factor XIII, the fibrin stabilizing factor zymogen, were examined with the native carrier subunits (B2) of the factor isolated from human plasma. Nondenaturing electrophoresis and HPLC gel-filtration experiments showed a tight binding of rA2 to B2 for forming an ensemble similar to that of plasma factor XIII (A2B2). In the presence of excess B2, however, some higher ordered oligomers (rA2Bn, where n > 2) were also seen in electrophoresis. The same technique revealed a microheterogeneity in the rA2 preparation; nevertheless, all isoforms could bind to B2. By employing an ELISA procedure for measuring free B2 in mixtures with rA2, an apparent binding constant of 4 x 10(7) M-1 was derived for the association of rA2 with B2. Fluorescence depolarization was used to monitor the heterologous association of rA2 with fluorescein-labeled B2F as well as the dissociation of the rA2B2F structure. The former was characterized by an increase, and the latter by a decrease, in the fluorescence anisotropy of the system. Binding of rA2 to B2F (pH 7.5, mu = 0.315, 37 degrees C) was not influenced by low concentrations of Ca2+ (< or = 30 mM), and rA2B2F proved to be quite stable under these conditions. Much higher concentrations of Ca2+, as well as higher ionic strengths, were required to dissociate this assembly. By contrast, release of B2F from the thrombin-modified rA2'B2F occurred rapidly in the presence of low concentrations of Ca2+ at low ionic strength.(ABSTRACT TRUNCATED AT 250 WORDS)

An improved synthesis of [125I]N-(diethylaminoethyl)-4-iodobenzamide: a potential ligand for imaging malignant melanoma

To improve the radiolabeling yield and the specific activity of [125I]N-(2-diethylaminoethyl)-4-iodobenzamide (DAB), the aryltributyltin precursor was synthesized from the N-(2-diethylaminoethyl)-4-bromobenzamide derivative by palladium catalyzed stannylation using bis(tributyltin). The radiolabeled product, [125I]DAB, was obtained by an iododestannylation reaction in high radiochemical yields (85-94%, radiochemical purity, > 98%) using chloramine-T as an oxidizing agent. The specific activity was greater than 1600 Ci/mmol. The biodistribution studies in nude mice implanted with human malignant melanoma xenograft showed a good tumor uptake (6.14% ID/g at 1 h, 2.81% ID/g at 6 h and 0.42% ID/g at 24 h) of [125I]DAB. Unfortunately, a high uptake in the non-target organs, such as liver and lung, was found. At 1 h post-injection the activity level in liver and lung was 11.76 and 7.58% ID/g, respectively. A slow clearance of activity from liver and lung was observed at 6 h (3.43 and 0.49% ID/g). These results demonstrate that iodinated IDAB is a potential radiopharmaceutical for the management of patients with malignant melanoma.

Cloning and expression of chicken erythrocyte transglutaminase

We report the sequences of cDNAs encoding chicken erythrocyte transglutaminase (EC 2.3.2.13). The complete mRNA consists of 3345/3349 nucleotides and predicts a single open reading frame. Nine peptide sequences derived from partial digests of the isolated protein agreed with the corresponding translation of the open reading frame. Approximately 60% identities between the avian protein and three related mammalian enzymes were found. Chicken erythrocyte transglutaminase mRNA is most abundant in red blood cells and kidney, and it accumulates during erythroid cell differentiation.

Visualization of purified fibronectin-transglutaminase complexes

It has been reported previously (Turner, P.M., and Lorand, L. (1989) Biochemistry 28, 628-635) that human erythrocyte transglutaminase forms a noncovalent complex with human plasma fibronectin near its collagen-binding domain. In the present study, we show by nondenaturing electrophoresis that guinea pig liver transglutaminase, similarly to the erythrocyte enzyme, forms a complex with human fibronectin. Studies of anisotropic shifts of fluorescein-labeled liver and erythrocyte transglutaminases, upon addition of fibronectin, indicated that both transglutaminases bind to fibronectin with a stoichiometry of about 2:1. Polymerization of fibrinogen by human erythrocyte transglutaminase was inhibited after complex formation with fibronectin. Complexes of fibronectin with either erythrocyte or liver transglutaminase were isolated by glycerol gradient zone sedimentation and examined by rotary shadowing electron microscopy. The globular transglutaminase could be readily identified binding to the thin fibronectin strand. The binding site for transglutaminase was within 5-10 nm of the N terminus of fibronectin, consistent with its proximity to the collagen-binding domain. Under some experimental conditions, the complex of fibronectin with erythrocyte transglutaminase appeared as a ring-shaped structure in which two transglutaminase molecules had probably dimerized. The molecular weight of the erythrocyte transglutaminase was determined by sedimentation equilibrium to be 71,440 +/- 830.