Dose reduction in spiral CT coronary angiography with dual-source equipment. Part I. A phantom study applying different prospective tube current modulation algorithms

PURPOSE

The authors sought to compare different algorithms for dose reduction in retrospectively echocardiographically (ECG)-gated dual-source computed tomography (CT) coronary angiography (DSCT-CA) in a phantom model.

MATERIALS AND METHODS

Weighted CT dose index (CTDI) was measured by using an anthropomorphic phantom in spiral cardiac mode (retrospective ECG gating) at five pitch values adapted with two heart-rate-adaptive ECG pulsing windows using four algorithms: narrow pulsing window, with tube current reduction to 20% (A) and 4% (B) of peak current outside the pulsing window; wide pulsing window, with tube current reduction to 20% (C) and 4% (D). Each algorithm was applied at different heart rates (45, 60, 75, 90, 120 bpm).

RESULTS

Mean CTDI volume (CTDIvol) was 36.9+/-9.7 mGy, 23.9+/-5.6 mGy, 49.7+/-16.2 mGy and 38.5+/-12.3 mGy for A, B, C and D, respectively. Consistent dose reduction was observed with protocols applying the 4% tube current reduction (B and D). Using the conversion coefficient for the chest, the mean effective dose was the highest for C (9.6 mSv) and the lowest for B (4.6 mSv). Heart-ratedependent pitch values (pitch=0.2, 0.26, 0.34, 0.43, 0.5) and the use of heart-rate-adaptive ECG pulsing windows provided a significant decrease in the CTDIvol with progressively higher heart rates (45, 60, 75, 90, 120 bpm), despite using wider pulsing windows.

CONCLUSIONS

Radiation exposure with DSCT-CA using a narrow pulsing window significantly decreases when compared with a wider pulsing window. When using a protocol with reduced tube current to 4%, the radiation dose is significantly lower.

Clinical applications of multi-detector computed tomography coronary angiography

Cardiac computed tomography (CT) is a fast developing technique. In 10 years it developed from investigative tool into a clinical reality. The technology drive has been the key to success for this technique which is to date the only non invasive clinical tool for coronary angiographic assessment. Technical background is quite complex and the newer solutions are aiming at reducing the scan time and the radiation dose while improving temporal resolution, contrast resolution and ultimately image quality. The key technical development has been in the late 1990, the introduction of ECG triggering/gating techniques. Spatial resolution has also been improved reaching sub-millimeter performance. The latest innovations provide fast coverage with >64 slice detectors, high spatial resolution with 0.5 mm slice thickness, high temporal resolution with <100 ms in hardware, and higher contrast resolution with the forthcoming dual-energy solutions. Recently, also dose issues have been exploited and current state of the art technology are able to perform cardiac CT with 1-2 mSv. These improvements put cardiac CT as the most promising clinical tool for the non invasive assessment of coronary arteries.

Computed tomography coronary angiography vs. stress ECG in patients with stable angina

PURPOSE

This study compared the role of multislice computed tomography coronary angiography (MSCT-CA) and stress electrocardiography (ECG) in the diagnostic workup of patients with chronic chest pain.

MATERIALS AND METHODS

MSCT-CA was performed in 43 patients (31 men, 12 women, mean age 58.8+/-7.7 years) with stable angina after a routine diagnostic workup involving stress ECG and conventional CA. The following inclusion criteria were adopted: sinus rhythm and ability to hold breath for 12 s. Beta-blockers were administered in patients with heart rate>or=70 beats/minute. In order to identify or exclude patients with significant stenoses (>or=50% lumen), we determined posttest likelihood ratios of stress test and MSCT-CA separately and of MSCT-CA performed after the stress test.

RESULTS

The pretest probability of significant coronary artery disease (CAD) was 74%. Positive and negative likelihood ratios were 2.3 [95% confidence interval (CI) 1.0-5.3] and 0.3 (95% CI: 0.2-0.7) for the stress test and 10.0 (95% CI: 1.8-78.4) and 0.0 (95% CI: 0.0-infinity) for MSCT-CA, respectively. MSCT-CA increased the posttest probability of significant CAD after a negative stress test from 50% to 86% and after a positive stress test from 88% to 100%. MSCT-CA correctly detected all patients without CAD.

CONCLUSIONS

Noninvasive MSCT-CA is a potentially useful tool in the diagnostic workup of patients with stable angina owing to its capability to detect or exclude significant CAD.

Regulation of A1 adenosine receptor functioning induced by P2Y1 purinergic receptor activation in human astroglial cells

In the rat brain, a heteromeric association between adenosine A(1) and purinergic P2Y(1) receptors has been demonstrated. It is suggested that this association plays an important role in the control of purine-mediated responses during pathophysiological conditions. Recently, we have demonstrated that these receptors colocalize on glutamatergic synaptic and astroglial membranes in rat hippocampus and reciprocally interact, thus modulating their functional responses at the G protein coupling level. In the present work, by means of immunoprecipitation studies, we demonstrated that A(1) and P2Y(1) receptors are present in human astroglial cells (ADF) and aggregate to form a multimeric complex. P2Y(1) receptor activation by its agonist, 2-methylthio-adenosine 5'-diphosphate (MeSADP), induced a time-dependent reduction in agonist-mediated A(1) receptor functional responses, causing a drop in A(1) receptor agonist potency to promote receptor-G protein coupling and to inhibit the adenylate cyclase pathway. These effects appeared to be selectively mediated by P2Y(1) receptor activation and probably occurred as a consequence of a direct receptor-receptor interaction at the plasma membrane level. These results indicated that P2Y(1) receptor activation induces A(1) receptor heterologous desensitization. The interaction between A(1) and P2Y(1) receptors may play an important role in the purinergic signaling cascade in astrocytes, which are involved in cell-to-cell communication and in control of synaptic transmission, particularly during pathological conditions, when large amounts of purines are released.

Estrogen regulation of adipose tissue functions: involvement of estrogen receptor isoforms

Adipose tissue has recently been described as one of the major endocrine gland that plays a role in energy homeostasis, lipid metabolism, immune response, and reproduction. An excess of white adipose tissue, caused by a complex interaction between genetic, hormonal, behavioral, and environmental factors, results in obesity: a heterogeneous disorder that predisposes humans to a variety of diseases. Among several hormones, estrogens promote, maintain, and control the typical distribution of body fat and adipose tissue metabolism through still unknown mechanisms. These steroids are known to regulate fat mass, adipose deposition and differentiation, and adipocyte metabolism. Moreover, estrogen deficiency results in increases in adipose tissue, preferentially in visceral fat, which would link obesity to the susceptibility of related disorders. In this review the role of estrogens in adipose tissue differentiation and in the protection against the onset of obesity will be discussed with particular attention being drawn to the underlying molecular mechanisms mediated by estrogen receptor isoforms ERalpha and ERbeta.

GABA A/Bz receptor subtypes as targets for selective drugs

The gamma-aminobutyric acid type A (GABA(A)) receptors are the major inhibitory neuronal receptors in the mammalian brain. Their activation by GABA opens the intrinsic ion channel, enabling chloride flux into the cell with subsequent hyperpolarization. Several GABA(A) receptor subunit isoforms have been cloned, the major isoform containing alpha, beta, and gamma subunits, and a regional heterogeneity associated with distinct physiological effects has been suggested. As a variety of allosteric ligands can modulate GABA-gated conductance changes through binding to distinct sites, the development of subtype-selective ligands may lead to the selective treatment of GABA system-associated pathology. In particular, the best characterized binding site is the benzodiazepine site (BzR), localized at the alpha/gamma subunit interface, in which the alpha subunit is the main determinant of BzR ligand action selectivity. The alpha1-containing BzR have been proposed to be responsible for the sedative action; the alpha2 and/or the alpha3 subtypes have been suggested to mediate the anxiolytic activity and the myorelaxation effects, and the alpha5 subtype has been associated with cognition processes. The discovery of alpha-selective subtype ligands may help in the specific treatment of anxiety, sleep disorders, convulsions and memory deficits with fewer side effects. Selectivity may be achieved by two approaches: selective affinity or selective efficacy. Selective affinity needs a compound to bind with a higher affinity to one receptor subtype compared with another, whereas subtype-selective efficacy relies on a compound binding to all subtypes, but having different efficacies at various subtypes. The status of BzR ligands, subdivided on the basis of their main chemical structural features, is reviewed in relation to structure-activity relationships which determine their affinity or efficacy selectivity for a certain BzR subtype.

Cholesterol: from feeding to gene regulation

We present here a brief description of the path that cholesterol covers from its intestinal absorption to its effects exerted on gene regulation. In particular, the relationship between cholesterol and the protein complexes involved in the intricate gene regulation mechanism implicated in cholesterol homeostasis will be discussed. In addition, a new target role for the pharmacological interventions of one of these factors, the insulin-induced gene (Insig) protein, will be introduced.

[Register for the evaluation of side effects after radiation in childhood and adolescence--first results]

BACKGROUND

Late effects after radiotherapy in childhood and adolescence have mainly been characterized retrospectively with small patient numbers. Therefore the German Group of Pediatric Radiation Oncology (APRO) established the "RegIster for the evaluation of late Side effects after radiation in childhood and adolescence" (RiSK). After a pilot phase starting in 2001 documentation has been performed all over Germany since 2004. This analysis shows the first results of "RiSK".

PATIENTS AND METHODS

Radiation parameters including detailed organ doses as well as toxicity evaluations were collected prospectively from centers all over Germany in the study center. Standardized documentation forms were used. Documentation is planned for all children who receive radiotherapy in one of the German pediatric therapy trials.

RESULTS

Until December 31st 2006, 696 documentations of radiotherapy and 526 acute as well as 836 late follow-up documentation forms have been collected. Altogether, 41 patients with late grade 3 and 16 patients with late grade 4-side effects were identified. Side effects mainly concerned joints with functional impairment (after combined radiotherapy and surgery), the bowel, skin and subcutis as well as blood parameters under continued chemotherapy. Patients with late side effects of a higher grade were mainly treated for Ewing's or soft tissue sarcomas (n=235 patients), representing 33.8% of all patients in this study.

CONCLUSION

Fortunately, up to now only a few late grade 3 or 4 side effects of radiotherapy are shown for almost 700 documented patients. For further results, especially for the characterization of dose-effect-relationships, this study has to be continued with a higher patient number and a longer follow-up.

Co-localization and functional cross-talk between A1 and P2Y1 purine receptors in rat hippocampus

Adenosine and ATP, via their specific P1 and P2 receptors, modulate a wide variety of cellular and tissue functions, playing a neuroprotective or neurodegenerative role in brain damage conditions. Although, in general, adenosine inhibits excitability and ATP functions as an excitatory transmitter in the central nervous system, recent data suggest the existence of a heterodimerization and a functional interaction between P1 and P2 receptors in the brain. In particular, interactions of adenosine A1 and P2Y1 receptors may play important roles in the purinergic signalling cascade. In the present work, we investigated the subcellular localization/co-localization of the receptors and their functional cross-talk at the membrane level in Wistar rat hippocampus. This is a particularly vulnerable brain area, which is sensitive to adenosine- and ATP-mediated control of glutamatergic transmission. The postembedding immunogold electron microscopy technique showed that the two receptors are co-localized at the synaptic membranes and surrounding astroglial membranes of glutamatergic synapses. To investigate the functional cross-talk between the two types of purinergic receptors, we evaluated the reciprocal effects of their activation on their G protein coupling. P2Y1 receptor stimulation impaired the potency of A1 receptor coupling to G protein, whereas the stimulation of A1 receptors increased the functional responsiveness of P2Y1 receptors. The results demonstrated an A1-P2Y1 receptor co-localization at glutamatergic synapses and surrounding astrocytes and a functional interaction between these receptors in hippocampus, suggesting ATP and adenosine can interact in purine-mediated signalling. This may be particularly important during pathological conditions, when large amounts of these mediators are released.

Mercury in urban soils: a comparison of local spatial variability in six European cities

The objective of this study was to quantify and assess for the first time the variability of total mercury in urban soils at a European level, using a systematic sampling strategy and a common methodology. We report results from a comparison between soil samples from Aveiro (Portugal), Glasgow (Scotland), Ljubljana (Slovenia), Sevilla (Spain), Torino (Italy) and Uppsala (Sweden). At least 25 sampling points (in about 4-5 ha) from a park in each city were sampled at two depths (0-10 and 10-20 cm). Total mercury was determined by pyrolysis atomic absorption spectrometry with gold amalgamation. The quality of results was monitored using certified reference materials (BCR 142R and BCR 141R). Measured total mercury contents varied from 0.015 to 6.3 mg kg(-1). The lowest median values were found in Aveiro, for both surface (0-10 cm) and sub-surface (10-20 cm) samples (0.055 and 0.054 mg kg(-1), respectively). The highest median mercury contents in soil samples were found in samples from Glasgow (1.2 and 1.3 mg kg(-1), for surface and sub-surface samples, respectively). High variability of mercury concentrations was observed, both within each park and between cities. This variability reflecting contributions from natural background, previous anthropogenic activities and differences in the ages of cities and land use, local environmental conditions as well as the influence of their location within the urban area. Short-range variability of mercury concentrations was found to be up to an order of magnitude over the distance of only a few 10 m.

Electrophysiological evaluation of visual pathways in paclitaxel-treated patients

As paclitaxel may induce positive spontaneous visual symptoms or persistent visual loss, we carried out this electrophysiological study in an attempt to clarify the underlying pathophysiological mechanisms of visual pathway involvement. The study involved 30 breast cancer patients: 14 were treated with paclitaxel alone (group A) and 16 with paclitaxel and adriamycin (group B). Pattern visual evoked potentials (VEPs), and transient, 30 Hz flicker (FLK) and oscillatory potential (OP) white flash electroretinograms (ERGs), were recorded before treatment, after the third and sixth therapeutic cycle, and at the end of the programmed regimen. Pretreatment: Abnormal VEP and OP and FLK changes occurred more than 75% of patients; transient ERGs were normal in more than 90%. Serial recordings: VEPs remained unchanged in both goups. In group A, ERG b-wave latency significantly increased (ANOVA P<0.005), and OP and FLK were characterised by non-significant mild attenuation. Several combinations of ERG, OP, FLK and VEP changes occurred in 50% of the patients. The association between transitory lightining scotoma or blurred vision (reported by 12 patients) and VEP, ERG and FLK was poor, whereas that with OP was satisfactory. A few patients showed stable and persistent subclinical electrophysiological changes. Electrophysiological changes during treatment revealed the involvement of both the retina and anterior optic pathway. There was only a weak correlation between visual symptoms and electrophysiology. We suggest that the most likely mechanism of visual symptoms and electrophysiological changes during paclitaxel administration is vascular dysregulation in the retina, or ischemic mechanisms when the optic nerve is involved.

The early diagnosis of multiple endocrine neoplasia type 1 (MEN 1): a case report

We report the case of a patient presenting amenorrhea, hyperprolactinemia, headache and nuclear magnetic resonance (NMR) evidence of pituitary macroadenoma. The family history revealed that the patient's father had had a referred sporadic insulinoma, removed 25 yr before without evidence of other endocrine disorders. Physical examination evidenced a slight neck enlargement. Among biochemical and endocrinological assays performed, only hyperprolactinemia was observed. Neck ultrasonography (US) revealed a parathyroid enlargement and a 99mTcO4/MIBI scan showed two hyperplasic lesions. Considering the diagnostic suspect of multiple endocrine neoplasia (MEN1), we performed abdominal US and NMR studies, showing a pancreatic lesion compatible with neuroendocrine tumor. A total body 111In-DTPA-d-Phe1 -octreotide scan (Octreoscan) was also carried out, evidencing no pituitary tumor uptake but high uptake of the abdominal lesion. After surgery, the histological examination confirmed the two parathyroid adenomas and four non-functioning pancreatic neuroendocrine tumors. When the patient was admitted for studying the pituitary lesion and for planning the opportune therapy, an early and partially subclinical stage of MEN1 was identified, potentially already clear but otherwise undiagnosed, and the genetic state of the patient's relatives, as possible carriers of DNA mutation, was checked. The DNA study for germline mutations confirmed the clinical diagnosis of MEN1 syndrome in the patient and evidenced the same MEN1 mutation in her father and twin sister. In this case report, we would like to underline that, still today, a correct anamnesis and physical examination are the cornerstone of clinical approach to the patient. Furthermore, initial good practice approach is necessary to plan the diagnostic iter, enabling clinicians to decide upon the best orientation and interpretation of the results among several complicated and expensive exams.

Autoimmune diabetes mellitus, Hodgkin's disease and Graves' ophthalmopathy in a patient with 8.1 ancestral haplotype

In this report, we describe the case of a 43-year-old woman affected by type 1 diabetes mellitus diagnosed 8 years before, who developed Graves' disease 2 years after chemotherapy and mantle radiotherapy treatment for Hodgkin's disease. Bilateral Graves' ophthalmopathy appeared four months before our observations. Intravenous methyl-prednisolone therapy was started, but was interrupted due to severe metabolic failure. Autoantibodies (anti-islet cells, anti-thyroid, thyroid-stimulating, non-organ-specific) were positive. Since the clinical picture suggested a genetic immunological ground predisposing to autoimmunity, we evaluated her HLA haplotype. Genomic typing of the patient permitted identification of the 8.1 ancestral haplotype, a Caucasoid haplotype unique in its association with many immunopathological diseases. Moreover, we also observed a haplotype unusual in Caucasians, trans DRB1*1101, DQA1*0103, DQB1*0603. To our knowledge, HLA-related genetic risk of developing thyroid autoimmunity after neck irradiation has never been studied. Although we cannot confirm a direct association between the 8.1 ancestral haplotype or DRB1*1101, DQA1*0103, DQB1*0603 and the diseases described, we suggest considering immunological parameters and HLA typing in candidate patients for mantle radiation therapy for Hodgkin's disease or other tumors. HLA haplotype determination could be useful in identifying the patients at raised risk of developing autoimmune diseases after irradiation, thus permitting a more appropriate follow-up schedule.

A new tiazofurin pronucleotide: synthesis and biological evaluation of cyclosaligenyl-tiazofurin monophosphate

Synthesis and biological activities of cyclosaligenyl-tiazofurin monophosphate (CycloSal-TRMP), a new tiazofurin pronucleotide, are reported. CycloSal-TRMP proved to be active in vitro against human myelogenous leukemia K562 cell line and as A1 adenosine receptor agonist.

[New perspectives in diagnosis and therapy of endocrine gastroenteropancreatic (GEP) tumors with somatostatin analogues]

In the last decade important progresses have been obtained in the diagnosis and therapy of endocrine gastroenteropancreatic (GEP) tumors, mainly derived from the somatostatin receptors characterization and the introduction of long acting somatostatin analogues. Receptorial scintigraphy with radio-labeled analogues (Octreoscan) is the first choice investigation for staging and follow-up of endocrine GEP tumors, thanks to the high sensitivity in revealing the primary tumor and metastases, and for its capability to reveal lesions that are not identified by other imaging methods. Moreover, somatostatin analogues uptake by tumors allow us to use radiopharmaceutical compounds for advanced disease treatment. Between the radio-labeled drugs until now studied, interesting results have been obtained by DOTA-lanreotide (MAURITIUS), DOTA0 Tyr3-octreotide (DOTATOC) and DOTA0 Tyr3-octreotate, bound to beta-emitting radio-isotope suitable for therapeutic use. In the field of the pharmacological therapy of GEP tumors, the clinical trials show that somatostatin analogues reduce the symptoms related to functionally active tumors and stabilize or slow tumor growth improving the patient quality of life. Although somatostatin analogues alone could not be able to cure GEP tumors, their early utilization in association with surgical debulking of primary tumor and metastases, embolization or chemoembolization, and interferon, chemotherapy and radio-metabolic therapy (mainly directed to the destruction of micrometastases), increases the possibility of a radical therapeutic intervention. The continuous evolution of pharmacological research provides always new analogues (octreotide LAR, lanreotide, vapreotide, BIM-23244, BN 81644, PTR-3173, BIM-23A387, SOM-230, etc.) with different pharmacokinetic and receptorial properties and acting with more effectiveness in the different individual clinical situations. In this context there have been recently introduced also the "chimeric" analogues. On the other hand, the widespread utilization of molecular biology and immunohistochemical methods can allow, in perspective, to better define the receptorial pattern of individual endocrine tumors, after their surgical removal. The necessity to integrate endocrinological, nuclear medicine, surgical, oncologic and laboratory competencies behaves a multidisciplinary approach based on the utilization of diagnostic-therapeutic protocols supplying comparable results. It does not appear unjustified to expect, in the future, a scenery of more "individual" and more effective therapies for patients affected by GEP tumours.

Gaucher's disease with Parkinson's disease: clinical and pathological aspects

The association between type 1 Gaucher disease and PD has been reported in the literature. The clinical picture is characterized by the predominance of bilateral akinetic-rigid signs and poor response to levodopa therapy. The authors describe four patients (two siblings) with type 1 Gaucher disease presenting with the following signs of typical PD: asymmetric onset of rigidity, resting tremor, bradykinesia, and a favorable response to Parkinson therapies.

[Multimodal treatment of liver metastases: our experience]

Our recent experience in multimodal treatment of liver metastases. Surgical treatment of liver metastases is increasing in these years regarding more and more patients, as well as more and more surgeons. In the same time the introduction of therapies allows today the integration of surgical treatment and also satisfactory palliation. Authors report their experience in these last 4 years and suggest interdisciplinary approach to get good results even in non dedicated centres.

Bone marker alterations in patients with type 1 Gaucher disease

Bone involvement is one of the most disabling aspects of type I Gaucher disease and its pathophysiology is still not well understood. As an invasive procedure, bone biopsies are not appropriate in a large population study. The development of sensitive bone resorption and formation tests have allowed the authors to study bone metabolism in a noninvasive manner in a group of type 1 Gaucher patients. Ten type I Gaucher adult patients with mild-to-severe bone disease were evaluated. Bone mineral density and markers of bone formation (total alkaline phosphatase and isoenzymes, carboxyterminal propeptide of type I procollagen, osteocalcin) and resorption (carboxyterminal telopeptide of type I collagen, urinary hydroxyproline, free-deoxypyridinoline and calcium) were measured in patients and in a control group, matched for sex and age. In Gaucher patients, carboxyterminal propeptide of type I procollagen (PICP), a bone formation index, was significantly lower compared with normal subjects (mean 101.17 ng/ml vs 140.75 ng/ml, P = 0.038), and analysis of bone resorption indexes showed a significant increase (mean 4.24 ng/ml vs 2.87 ng/ml, P = 0.012) of serum carboxyterminal telopeptide of type I collagen (ICTP). No significant differences were observed in osteocalcin, alkaline phosphatase, and urinary hydroxyproline. Bone mineral density revealed osteopenia in six patients, with a mean Z-score of ?1.04. It was not possible to show a relationship between sex, splenectomy status, age, weight, spleen, and liver volume and bone density, expressed as a Z-score nor a correlation between Z score and severity of skeletal disease. Results have shown a predominance of the resorption phase in the bone metabolism of Gaucher patients. These markers could be useful in monitoring the effect of enzyme replacement therapy on Gaucher disease skeletal involvement.

Pilot-plant comparative study of peracetic acid and sodium hypochlorite wastewater disinfection

Peracetic acid (PAA) use in wastewater disinfection was assessed by examining its performances in a pilot plant fed by the effluent from a conventional activated-sludge treatment plant. The influence of PAA initial concentrations (0.5-4.0 mg/l) and contact times (8-38 min) on the presence of seven microorganisms (total coliforms, fecal coliforms, fecal streptococci, Escherichia coli, Pseudomonas sp., Salmonella sp., and bacteriophages anti-E. coli) and on residual biocide and halogenated organic compound (AOXs) concentrations were evaluated. The data so obtained were compared to the corresponding results acquired using sodium hypochlorite (HYP) in the same experimental conditions. The biocide effect of PAA against total and fecal coliforms, E. coli, Pseudomonas sp. and Salmonella sp. was similar to that shown by HYP. The former disinfectant was, however, less efficient than the latter in the reduction of fecal streptococci and bacteriophages anti-E. coli. In both cases the biocide quantities initially introduced in the sewage resulted in the presence of significant concentrations at the end of the contact time. No significant variation of AOX content was detected in the effluent treated with PAA, whereas a progressive increment of such compounds was found when increasing quantities of HYP were added to the sewage.