Harmonisation of PET/CT contrast recovery performance for brain studies.

PURPOSE: In order to achieve comparability of image quality, harmonisation of PET system performance is imperative. In this study, prototype harmonisation criteria for PET brain studies were developed. METHODS: Twelve clinical PET/CT systems (4 GE, 4 Philips, 4 Siemens, including SiPM-based "digital" systems) were used to acquire 30-min PET scans of a Hoffman 3D Brain phantom filled with ~ 33 kBq·mL-1 [18F]FDG. Scan data were reconstructed using various reconstruction settings. The images were rigidly coregistered to a template (voxel size 1.17 × 1.17 × 2.00 mm3) onto which several volumes of interest (VOIs) were defined. Recovery coefficients (RC) and grey matter to white matter ratios (GMWMr) were derived for eroded (denoted in the text by subscript e) and non-eroded grey (GM) and white (WM) matter VOIs as well as a mid-phantom cold spot (VOIcold) and VOIs from the Hammers atlas. In addition, left-right hemisphere differences and voxel-by-voxel differences compared to a reference image were assessed. RESULTS: Systematic differences were observed for reconstructions with and without point-spread-function modelling (PSFON and PSFOFF, respectively). Normalising to image-derived activity, upper and lower limits ensuring image comparability were as follows: for PSFON, RCGMe = [0.97-1.01] and GMWMre = [3.51-3.91] for eroded VOI and RCGM = [0.78-0.83] and GMWMr = [1.77-2.06] for non-eroded VOI, and for PSFOFF, RCGMe = [0.92-0.99] and GMWMre = [3.14-3.68] for eroded VOI and RCGM = [0.75-0.81] and GMWMr = [1.72-1.95] for non-eroded VOI. CONCLUSIONS: To achieve inter-scanner comparability, we propose selecting reconstruction settings based on RCGMe and GMWMre as specified in "Results". These proposed standards should be tested prospectively to validate and/or refine the harmonisation criteria.

Expression patterns of three α-expansin isoforms in Coffea arabica during fruit development.

As a first step towards understanding the physiological role and regulation of the expansin gene (EXP) family in Coffea arabica fruits during growth and maturation, we identified 11 expansin genes, nine belonging to the α-expansin family (EXPA), one EXLA and one EXLB, through in silico analysis of expressed sequence tags (ESTs). Within the α-expansin family, three isoforms were selected for detailed examination based on their high expression in coffee fruits or because they were specifically induced during different fruit developmental stages, according to the EST information. The expression patterns were analysed in different fruit tissues (perisperm, endosperm and pericarp) of C. arabica cv. IAPAR-59 and C. arabica cv. IAPAR-59 Graúdo, the latter being a closely related cultivar with a larger fruit size. Accumulation of CaEXPA1 and CaEXPA3 transcripts was high in the perisperm (tissue responsible for coffee bean size) and in the early stages of pericarp development. Transcripts of CaEXPA2 were detected only in the pericarp during the later stages of fruit maturation and ripening. There was no detectable transcription of the three EXPs analysed in the endosperm. The observed differences in mRNA expression levels of CaEXPA1 and CaEXP3 in the perisperm of IAPAR-59 and IAPAR-59 Graúdo suggest the participation of these two isoforms in the regulation of grain size.

High-resolution visualization of tumours in rabbit lung using refraction contrast X-ray imaging.

Contrast enhancement by refraction was used to visualize tumours in the rabbit lung. VX2 tumour cells were intravenously injected into a rabbit. After 14 days the rabbit was euthanized and the lungs were imaged. Refraction-enhanced X-ray images were obtained with a sample-to-detector distance of 2.65-6m. The beamline BL20B2 at the SPring-8 synchrotron radiation facility was used for the experiment, with a monochromatic X-ray beam with an energy of 33.2 keV. In the case of projection images, it was found that refraction did not help visualization of small tumours: the nodules did not show up with sharply defined edges. In tomography, tumours with a size of 1-10mm were clearly visualized, together with blood vessels with a diameter down to 0.4mm. These results show that refraction-enhanced imaging may be useful in human lung tomography to find small tumours.

Refraction-enhanced tomography of mouse and rabbit lungs.

In order to evaluate the effectiveness of edge enhancement by refraction in computed tomography, images of a cross section of a euthanized mouse thorax were recorded at low (20 keV) and high (72 keV) x-ray energies at a spatial resolution of about 40 microm. Compared with the images obtained with the detector at 30 cm from an object, when the object was located at 113 cm from the detector, the contrast between tissues and air was improved at both energies. The improvement was more pronounced at 72 keV where the absorption contrast was weaker. This effect was due to refraction at the surfaces of alveolar membranes and small airways which creates areas with apparently high and low linear attenuation coefficients within tissues. The edge enhancement by refraction was also effective in images of a euthanized rabbit thorax at x-ray energies of 40 and 70 keV at a spatial resolution of about 0.15 mm. These results raise the possibility that the refraction contrast may be utilized to obtain a high-resolution tomographic image of human lung and bone with low dose.

Antitumour activity and side effects of combined treatment with chitosan and cisplatin in sarcoma 180-bearing mice.

We examined the possible modulation by chitosan of the antitumour effects and side effects of cisplatin (cis-diaminedichloroplatinum, CDDP). The study showed that CDDP had potent antitumour activity when administered orally as well as intraperitoneally. We also compared the antitumour activity and side effects of orally administered CDDP plus orally administered chitosan versus intraperitoneally administered CDDP plus orally administered chitosan in sarcoma 180-bearing mice. When CDDP (1.25 mgkg(-1) x 2 day(-1)) was intraperitoneally administered to sarcoma 180-bearing mice, myelotoxicity (the reduction of leucocyte and platelet numbers), nephrotoxicity (the increase of blood nitrogen urea level), immunotoxicity (the reduction of spleen and thymus weight) and a reduction in body weight resulted. These intraperitoneally administered CDDP-induced side effects were not prevented by oral administration of chitosan (150 mgkg(-1) x 2 day(-1) and 750 mgkg(-1) x 2 day(-1)) for 14 consecutive days. On the other hand, the side effects such as the reductions of body and spleen weights induced by orally administered CDDP (1.25 mgkg(-1) x 2 day(-1)) were prevented by the oral administration of chitosan (150 mgkg(-1) x 2 day(-1) and 750 mg kg(-1) x 2 day(-1)). From these results, we conclude that the orally administered chitosan plus CDDP might be useful for the prevention of body weight reduction and immunotoxicity (the reduction of spleen weight) induced by the orally administered CDDP without diminishing antitumour activity.

[Clinical experience with rhenium-188 HEDP therapy for metastatic bone pain]. / 188Re HEDP-terápiával szerzett tapasztalatok a metasztatikus csontfájdalom kezelésében.

Rhenium-188 hydroxyethylidene diphosphonate (Re-188 HEDP) is a new radiopharmaceutical for treatment of metastatic bone pain. Re-188 is a generator-produced radionuclide emitting high energy beta and gamma rays and having a relative short physical half-life makes it of especially interesting for therapeutic purpose. Seven patients (pts) with multiple painful bone metastases were treated with Re-188 HEDP. Five pts with prostate cancer and 2 pts with breast cancer received a fixed activity of 3000 MBq of Re-188 HEDP intravenously in two steps. Complete blood counts were determined, blood chemistry examinations and urine-analysis were performed before and 1, 2, 3, 4, 6, 8, 12 weeks following the treatment. A visual analogue score, a verbal rating scale, the Spitzer index and the Karnofsky score were used to assess pain and performance status. Three hours after Re-188 HEDP administration at 1 m from the anterior mid-trunk of the pts gamma and at the patient body surface beta-radiation dose measurements were made, together with urine radioactivity measurements. Three pts become pain-free, 2 pts exhibited partial pain improvement and 1 patient gave no response to the Re-188 HEDP therapy. In 1 patient due to central nervous system metastasis the modification of the pain intensity could not be evaluated. Three pts displayed a flare reaction within 1 week after the treatment. Transient decreases in platelet and white blood cell counts were observed. There were no significant changes in the liver and renal functions. Radiation dose rate values of 6.3 +/- 1.0 microSv/h for gamma, and of 183 +/- 40 s-1 for beta-radiation were found. 25-32% of the administered dose was eliminated via the urinary tract in the first three hours. The preliminary data suggests that Re-188 HEDP is an effective radiopharmaceutical in treatment for metastatic bone pain. An administered activity of 3000 MBq can bring about a pain reduction without causing any clinically significant bone marrow toxicity.

[Initial experiences with 123-Iodine-IBZM neuroreceptor scintigraphy in extrapyramidal disorders]. / 123I-IBZM (3-jód-6-metoxi-benzamid) neuroreceptor-szcintigráfiával szerzett kezdeti tapasztalatok extrapyramidalis kórképekben.

The receptor scintigraphy of the dopaminergic system of the brain is of interest in the evaluation of movement disorders. The 123I-IBZM is a radiopharmaceutical with affinity predominantly to postsynaptic D2 receptors. The aim of this study was to evaluate the role of IBZM SPECT investigations in the differentiation of disorders with Parkinson's syndrome. Eight patients with idiopathic Parkinson's syndrome and 8 patients Parkinson's syndrome with other etiology were investigated with 123I-IBZM SPECT (6 females, 10 males, mean age +/- SD: 59 +/- 9). The patients according to the clinical signs and symptoms, results of CT/MRI and rCBF SPECT investigation were categorized. The reconstructed SPECT slices were evaluated visually and quantitatively. The visual interpretation of the images were performed by two observer and scored the radiopharmaceutical uptake (from 1-3) of the cortex and the striatum separately. For quantification striatum/frontal cortex activity ratio were calculated with ROI technique. The differences between the patient groups were statistically analyzed by two tailed t-test. The IBZM uptake were different in the two group of patients. The striatal IBZM accumulation was higher in the idiopathic Parkinson's syndrome patients compared to the other parkinsonians. The striatum/frontal lobe activity ratio was 1.69 +/- 0.9 (mean +/- SD) in the right, 1.67 +/- 0.04 (mean +/- SD) in the left hemisphere of the patients with idiopathic Parkinson's syndrome. The corresponding data in the nonidiopathic parkinsonian group were 1.53 +/- 0.06 (mean +/- SD), 1.52 +/- 0.04 (mean +/- SD) respectively (p < 0.01). The quantitative data correlated with the results of the visual evaluation. According to the data presented IBZM-SPECT is an effective tool in the differentiation of disorders with Parkinson syndrome.

[Experience with ambulatory radioiodine therapy of hyperthyroidism]. / Ambuláns radiojód kezeléssel szerzett tapasztalatok a hyperthyreosis gyógyításában.

Since 1993, outpatient radioiodine therapy has been available in Hungary. The reported study evaluated the efficacy of outpatient radioiodine treatment in subjects with hyperthyroidism. The data on 118 patients with Graves' disease and 36 patients with thyroid autonomy were analysed retrospectively. All patients were treated within the period 1994-1997. The activities of radioiodine were individually calculated. The applied dose in Graves' disease was 150 Gy, and in thyroid autonomy 150 Gy or 300 Gy. The efficacy of the treatment were evaluated 3, 6, and 12 months after radioiodine therapy. In patients with persistent hyperthyroidism repeated therapies were performed. Overall the radioiodine therapy was successful in 85% of the Graves' disease patients. The first 150 Gy treatment was effective in 70% of the patients with Graves' disease and in 43% of the patients with increased radioiodine turnover. In thyroid autonomy, the treatment with 150 Gy was successful in 71%, with 300 Gy in 89% of the patients. The efficacy of radioiodine treatment was similar to the results of one dose application. It was concluded, that radioiodine therapy with 150 Gy absorbed dose in Graves' disease and with 300 Gy absorbed dose in thyroid autonomy proved successful by the method of the authors.

Disruption of higher-order folding by core histone acetylation dramatically enhances transcription of nucleosomal arrays by RNA polymerase III.

We have examined the effects of core histone acetylation on the transcriptional activity and higher-order folding of defined 12-mer nucleosomal arrays. Purified HeLa core histone octamers containing an average of 2, 6, or 12 acetates per octamer (8, 23, or 46% maximal site occupancy, respectively) were assembled onto a DNA template consisting of 12 tandem repeats of a 208-bp Lytechinus 5S rRNA gene fragment. Reconstituted nucleosomal arrays were transcribed in a Xenopus oocyte nuclear extract and analyzed by analytical hydrodynamic and electrophoretic approaches to determine the extent of array compaction. Results indicated that in buffer containing 5 mM free Mg2+ and 50 mM KCl, high levels of acetylation (12 acetates/octamer) completely inhibited higher-order folding and concurrently led to a 15-fold enhancement of transcription by RNA polymerase III. The molecular mechanisms underlying the acetylation effects on chromatin condensation were investigated by analyzing the ability of differentially acetylated nucleosomal arrays to fold and oligomerize. In MgCl2-containing buffer the folding of 12-mer nucleosomal arrays containing an average of two or six acetates per histone octamer was indistinguishable, while a level of 12 acetates per octamer completely disrupted the ability of nucleosomal arrays to form higher-order folded structures at all ionic conditions tested. In contrast, there was a linear relationship between the extent of histone octamer acetylation and the extent of disruption of Mg2+-dependent oligomerization. These results have yielded new insight into the molecular basis of acetylation effects on both transcription and higher-order compaction of nucleosomal arrays.

Role of histone H1 as an architectural determinant of chromatin structure and as a specific repressor of transcription on Xenopus oocyte 5S rRNA genes.

We explore the role of histone H1 as a DNA sequence-dependent architectural determinant of chromatin structure and of transcriptional activity in chromatin. The Xenopus laevis oocyte- and somatic-type 5S rRNA genes are differentially transcribed in embryonic chromosomes in vivo depending on the incorporation of somatic histone H1 into chromatin. We establish that this effect can be reconstructed at the level of a single nucleosome. H1 selectively represses oocyte-type 5S rRNA genes by directing the stable positioning of a nucleosome such that transcription factors cannot bind to the gene. This effect does not occur on the somatic-type genes. Histone H1 binds to the 5' end of the nucleosome core on the somatic 5S rRNA gene, leaving key regulatory elements in the promoter accessible, while histone H1 binds to the 3' end of the nucleosome core on the oocyte 5S rRNA genes, specifically blocking access to a key promoter element (the C box). TFIIIA can bind to the somatic 5S rRNA gene assembled into a nucleosome in the presence of H1. Because H1 binds with equivalent affinities to nucleosomes containing either gene, we establish that it is the sequence-selective assembly of a specific repressive chromatin structure on the oocyte 5S rRNA genes that accounts for differential transcriptional repression. Thus, general components of chromatin can determine the assembly of specific regulatory nucleoprotein complexes.

[The role of 99mTc-MIBI mammoscintigraphy in the diagnosis of breast cancer]. / 99mTc-MIBI mammoszcintigráfia szerepe az emlödaganatok diagnosztikájában.

Among several investigative methods currently undergoing evaluation for the differentiation of biological features of breast mass lesions, mammoscintigraphy with different radiopharmaceuticals appears promising. The reported study evaluated the efficacy of 99mTc-MIBI mammoscintigraphy in detection of the malignancy of focal breast lesions. Mammography, 99mTc-MIBI mammoscintigraphy were performed in 51 women with palpable breast mass lesions. Following surgical removal of the abnormalities, histological examination revealed 40 malignant and 11 benign breast mass lesions. In the mammoscintigraphy, early (5 min p. i. of MIBI) and late (2 h p. i. of MIBI) planar images of the breast and the axillary regions were evaluated visually and semiquantitatively. The sensitivity and specificity values of MIBI mammoscintigraphy were in the detection malignant breast lesions evaluated visually according to the early images 95% and 73%, according to the late images 98% and 82%, respectively. Revealed to the quantitative results the corresponding results were according to the early images 90% and 64% according to the late images 95% an 64%. The visual scores and the quantitative T/NT values with MIBI demonstrated a significant difference between malignant and benign breast mass lesions. A significant difference was also found as concerns the grade of malignancy from the MIBI accumulation. The late MIBI images seemed optimal. In the detection of metastatic lymph node involvement, the sensitivity and specificity with MIBI were 53% and 81%. It was concluded that MIBI (2 h p. i.) mammoscintigraphy is a useful and simple method for differentiation of malignant breast abnormalities from benign lesions and for determination of the grade of malignancy.

rCBF SPECT and the acetazolamide test in the evaluation of dementia.

BACKGROUND: The diagnostic potential of 99mTc-HMPAO following systemic administration of the cerebral vasodilator acetazolamide (acetazolamide test) was evaluated using regional-cerebral-blood-flow (rCBF) SPECT in patients with Alzheimer's disease (AD) or with vascular-type of dementia (VD). METHODS: An initial, high-resolution SPELT study was performed with 99mTc-HMPAO, and after 2 days patients were re-evaluated with 99mTc-HMPAO following systemic administration of acetazolamide. Reconstructed SPELT slices were evaluated visually and semiquantitatively by a semiautomatic rCBF map method. RESULTS: Using 99mTc-HMPAO alone, a bilateral hypoperfusion was found in the temporal and/or parietal regions in 33% (6/18) of VD patients and in 70% (23/33) of AD patients. The vascular reserve capacity, as determined with the acetazolamide test, was not impaired in 22% of the VD patients but in 76% of the AD patients. The differences in the perfusion patterns between VD and AD patients were statistically different (p < 0.01, Fischer's exact test). Of the 6 VD patients with hypoperfusion (bilateral temporal and/or parietal), 4 had a decreased vascular reserve capacity as determined in the acetazolamide test. Decreased reserve capacity was found in only 4 out of 25 patients with AD. CONCLUSIONS: The acetazolamide test is helpful in rCBF SPECT to differentiate VD from AD.

Investigation of gamma camera detector uniformity using a dynamic line phantom.

BACKGROUND: Investigation of the applicability of the dynamic line phantom for determination o the uniformity of circular and rectangular field-of-view gamma cameras. METHODS: Count rate - activity and uniformity - count rate functions were determined by the dynamic line phantom on three circular field-of-view gamma cameras with 37 PMTs, on one circular field of view camera with 19 PMTs, and on one rectangular field-of view gamma camera with 59 PMTs, with and without a collimator. For an evaluation of the efficacy of the dynamic line phantom, the results were compared with the uniformity values obtained with a 99mTc point source and a 57-Co sheet source. RESULTS: In the optimum count rate range (20,000-30,000 cps for a circular field-of-view, 15,000-65,000 cps for a rectangular field-of-view) determined individually for each gamma camera, the uniformity values obtained with the dynamic line phantom did not differ statistically from the refined with the 99mTc point source or the 57-Co sheet source. CONCLUSIONS: The dynamic line phantom is suitable for the determination of detector uniformity, but the measurements should be performed within a well-defined activity (count rate) interval.

Value of 99m-Tc MIBI and 99m-Tc(V) DMSA scintigraphy in evaluation of breast mass lesions.

Among several investigative methods currently undergoing evaluation for the differentiation of biological features of breast mass lesions, mammoscintigraphy with different radiopharmaceuticals appears promising. This study evaluated the efficacy of 99m-Tc MIBI and 99m-Tc(V) DMSA mammoscintigraphy in the detection of malignant focal breast lesions. Mammography, ultrasonography, 99m-Tc MIBI and 99m-Tc(V) DMSA mammoscintigraphy were performed in 51 women with palpable breast mass lesions. Following surgical removal of the abnormalities, histological examination revealed 40 malignant and 11 benign breast mass lesions. In mammoscintigraphy, early (5 minute p.i. of MIBI, 2 hours p.i. of DMSA) and late (2 hours p.i. of MIBI and 5 hours p.i. of DMSA) planar images of the breast and the axillary regions were evaluated visually and quantitatively. The efficacy of the methods was assessed via ROC curves and variance analysis. The visual scores and the quantitative T/NT values with MIBI demonstrated a significant difference between malignant and benign breast mass lesions. A significant difference was also found as concerns the grade of malignancy from the MIBI accumulation. The late MIBI images seemed optimal. The DMSA values indicated no relationship with the breast lesion malignancy. In the detection of metastatic lymph node involvement the sensitivity and specificity with mammography and ultrasonography were 57% and 85%, with MIBI 53% and 81%, and with DMSA 53% and 95%, respectively. It is concluded that MIBI (2 hours p.i.) mammoscintigraphy is a useful and simple method for differentiation of malignant breast abnormalities from benign lesions and for determination of the grade of malignancy. DMSA mammoscintigraphy appears superior to MIBI only in the detection of axillary lymph node metastases.

In vivo selection of basic region-leucine zipper proteins with altered DNA-binding specificities.

A transcription interference assay was used to generate mutant basic region-leucine zipper proteins with altered DNA-binding specificities. A library of mutants of a CCAAT/enhancer binding protein was constructed by randomizing five DNA-contacting amino acids in the basic region Asn-18, Ala-15, Val-14, Ser-11, and Arg-10. These mutants were then selected for their ability to bind mutant recognition sequences containing substitutions at the 2 and 3 positions of the wild-type sequence 5'-A5T4T3G2C1G1'C2'A3A4'T5'-3'. Mutants containing the sequence Leu-18Tyr-15Xaa-14Tyr-11Arg-10, in which four of the five contact residues are altered, were identified that recognize the palindromic sequence 5'-ATCYCGY'GAT-3' (Xaa = asparagine when Y = G; Xaa = methionine when Y = A). Moreover, in a selection against the sequence 5'-ATTACGTAAT-3', mutants were obtained containing substitutions not only in the basic region but also in the hinge region between the basic and leucine zipper regions. The mutant proteins showed high specificity in a functional transcription interference assay. A model for the interaction of these mutants with the target DNA sequences is discussed.

A permutational approach toward protein-DNA recognition.

The cI repressor of bacteriophage 434, known as 434 repressor, binds to 14-bp operator sequences by means of a helix-turn-helix motif. To probe the requirements for selective DNA recognition by this class of DNA binding proteins, as well as to generate new proteins with altered specificities, a library of approximately 3 x 10(6) mutants was generated that contains all permutations of five residues in the recognition helix (helix 3) of the repressor. These mutants were then selected in vivo for their ability to bind both wild-type (WT) and mutant operator sequences. The results of the selection demonstrate that four of these residues--Gln28, Gln29, Ser30, and Gln33--play a critical role in recognition of the WT operator. A number of repressors with mutations at Thr27 showed altered DNA binding affinities and specificities. The approach described here may also prove useful in studies of DNA recognition by other classes of DNA binding proteins.