Biology of Isl1+ cardiac progenitor cells in development and disease

The LIM-homeodomain transcription factor Islet-1 (Isl1) marks a cell population which makes a substantial contribution to the embryonic heart. Isl1 expression is downregulated as soon as the cells adopt a differentiated phenotype, suggesting that this transcription factor delineates a cardiogenic progenitor cell population. Taking advantage of this developmental lineage marker, we have identified in the postnatal heart a novel cardiac cell type, which is capable of self-renewal and readily differentiates into mature cardiomyocytes. Utilization of embryonic stem (ES) cells that harbour knock-ins of reporter genes into the endogenous Isl1 locus will enable us to isolate Isl1+ cardiac progenitors from mouse and human ES cell systems during in vitro cardiogenesis. These genetic cell-based systems should allow the direct identification of signalling pathways which guide formation, renewal and diversification of Isl1+ cardiogenic progenitors into distinct heart cell lineages, and would complement in vitro studies in the mouse embryo during cardiac development.

Two-dimensional tracking and TDI are consistent methods for evaluating myocardial longitudinal peak strain in left and right ventricle basal segments in athletes

Background

Myocardial contractility can be investigated using longitudinal peak strain. It can be calculated using the Doppler-derived TDI method and the non-Doppler method based on tissue tracking on B-mode images. Both are validated and show good reproducibility, but no comparative analysis of their results has yet been conducted. This study analyzes the results obtained from the basal segments of the ventricular chambers in a group of athletes.

Methods

30 regularly-trained athletes were submitted to an echocardiography at rest and after handgrip. Starting from the four-chamber view, overall myocardial function and regional velocities were evaluated. The images obtained were processed to determine strain in left and right ventricle basal segments. Strain was calculated using the TDI method and a validated "speckle tracking" or, more correctly, "feature tracking" algorithm. The statistical analysis included a Student's t-test (p < 0.05).

Results

The range of strain values obtained is in agreement with the data reported in the literature. In the left ventricle (LV) the average strain values of the basal segments calculated with TDI on IVS and LW at rest and after stress were: -21.05 ± 3.31; -20.41 ± 2.99 and -20.05 ± 2.61; -21.20 ± 2.37, respectively. In the right ventricle (RV) the same method gave IVS and LW strain values at rest of -22.22 ± 2.58 ; -24.42 ± 5.84, and after HG of -22.02 ± 5.20 ;-23.93 ± 6.34. The values obtained using feature tracking were: LV at rest -20.48 ± 2.65 for IVS, and -21.25 ± 2.85 for LW; LV after HG: -19.48 ± 3 for IVS and -21.69 ± 3.85 for LW. In RV at rest: -21.46 ± 3.25 for IVS and -24.13 ± 5.86 for LW; RV after HG: -24.79 ± 7.9 for IVS and -24.13 ± 7.0 for LW. Tissue Doppler and "feature tracking" methods showed the respective consistency of the results in the basal segments of myocardial ventricle walls.

Conclusion

Provided that echographic imaging is good, strain can be computed in athletes by both Doppler-derived and tracking methods. It is technically feasible to use both -interchangeably, at least in basal segments.

18F-FDG PET/CT in the assessment of carcinoma of unknown primary origin

PURPOSE

Metastatic cancers of unknown primary origin are characterised by a poor prognosis, with a survival rate from diagnosis of approximately 12 months. Conventional radiological imaging allows detection of 20%-27% of primary cancers, whereas the detection rate with positron emission tomography (PET) is 24%-40%. The aim of this study was to assess the role of 18F-fluorodeoxyglucose (FDG) PET/computed tomography (CT) in the identification of occult primary cancers.

MATERIALS AND METHODS

The study population consisted of 38 consecutive patients with histologically proven metastatic disease and negative or nonconclusive conventional diagnostic procedures. All patients were studied by 18F-FDG PET performed according to the standard procedure (6 h of fasting, intravenous injection of 370 MBq 18F-FDG, and image acquisition with a PET/CT scanner for 4 min per bed position).

RESULTS

18F-FDG-PET/CT detected the occult primary cancer in 20 cases (53%), showing higher sensitivity than that reported for any other imaging modality, including PET.

CONCLUSIONS

The encouraging results, if validated by larger series, support the use of PET/CT in patients with carcinoma of unknown primary origin and negative conventional imaging results.

Unusual association of adrenal pheochromocytoma and para-aortic neurofibroma in pregnancy

The association of pheochromocytoma (PHEO) and pregnancy is uncommon and life threatening for both the fetus and the mother. Early diagnosis and treatment is essential to decrease maternal and fetal mortality and to differentiate the disease from the more common pre-eclampsia. While medical treatment should be started immediately after diagnosis, the timing of surgical treatment is still debated. We describe the case of a 27-yr-old woman in the 18th week of pregnancy who showed a biochemical pattern typical of PHEO and, by imaging studies, 2 tumors with the same characteristics: the first localized on the right adrenal gland, the second at the right renal hilum. The patient underwent surgery because of suspicion of malignant PHEO with local metastasis, while histology revealed a rare association of a solitary PHEO and para-aortic neurofibroma, both tumors embryologically deriving from a common cell precursor.

The association of GRB 060218 with a supernova and the evolution of the shock wave

Although the link between long gamma-ray bursts (GRBs) and supernovae has been established, hitherto there have been no observations of the beginning of a supernova explosion and its intimate link to a GRB. In particular, we do not know how the jet that defines a gamma-ray burst emerges from the star's surface, nor how a GRB progenitor explodes. Here we report observations of the relatively nearby GRB 060218 (ref. 5) and its connection to supernova SN 2006aj (ref. 6). In addition to the classical non-thermal emission, GRB 060218 shows a thermal component in its X-ray spectrum, which cools and shifts into the optical/ultraviolet band as time passes. We interpret these features as arising from the break-out of a shock wave driven by a mildly relativistic shell into the dense wind surrounding the progenitor. We have caught a supernova in the act of exploding, directly observing the shock break-out, which indicates that the GRB progenitor was a Wolf-Rayet star.

Human brain activation during passive listening to sounds from different locations: an fMRI and MEG study

Recent animal and human studies indicate the existence of a neural pathway for sound localization, which is similar to the "where" pathway of the visual system and distinct from the sound identification pathway. This study sought to highlight this pathway using a passive listening protocol. We employed fMRI to study cortical areas, activated during the processing of sounds coming from different locations, and MEG to disclose the temporal dynamics of these areas. In addition, the hypothesis of different activation levels in the right and in the left hemispheres, due to hemispheric specialization of the human brain, was investigated. The fMRI results indicate that the processing of sound, coming from different locations, activates a complex neuronal circuit, similar to the sound localization system described in monkeys known as the auditory "where" pathway. This system includes Heschl's gyrus, the superior temporal gyrus, the supramarginal gyrus, and the inferior and middle frontal lobe. The MEG analysis allowed assessment of the timing of this circuit: the activation of Heschl's gyrus was observed 139 ms after the auditory stimulus, the peak latency of the source located in the superior temporal gyrus was at 156 ms, and the inferior parietal lobule and the supramarginal gyrus peaked at 162 ms. Both hemispheres were found to be involved in the processing of sounds coming from different locations, but a stronger activation was observed in the right hemisphere.

An origin for short gamma-ray bursts unassociated with current star formation

Two short (< 2 s) gamma-ray bursts (GRBs) have recently been localized and fading afterglow counterparts detected. The combination of these two results left unclear the nature of the host galaxies of the bursts, because one was a star-forming dwarf, while the other was probably an elliptical galaxy. Here we report the X-ray localization of a short burst (GRB 050724) with unusual gamma-ray and X-ray properties. The X-ray afterglow lies off the centre of an elliptical galaxy at a redshift of z = 0.258 (ref. 5), coincident with the position determined by ground-based optical and radio observations. The low level of star formation typical for elliptical galaxies makes it unlikely that the burst originated in a supernova explosion. A supernova origin was also ruled out for GRB 050709 (refs 3, 31), even though that burst took place in a galaxy with current star formation. The isotropic energy for the short bursts is 2-3 orders of magnitude lower than that for the long bursts. Our results therefore suggest that an alternative source of bursts--the coalescence of binary systems of neutron stars or a neutron star-black hole pair--are the progenitors of short bursts.

Unique association of non-functioning pheochromocytoma, ganglioneuroma, adrenal cortical adenoma, hepatic and vertebral hemangiomas in a patient with a new intronic variant in the VHL gene

We analyzed the clinical, hormonal, immunohistochemical and genetic features in a 69-yr-old Caucasian woman with a very rare "composite and mixed pheochromocytoma". This was characterized by right adrenal pheochromocytoma associated with homolateral ganglioneuroma and controlateral adrenal cortical adenoma. The three tumors, incidentally discovered, proved to be non-functioning (normal secretion of catecholamines and of other neuroendocrine peptides, glucocorticoids, mineralcorticoids and androgens). Accordingly, the patient showed no sign or symptom of endocrine disease. Computed tomography (CT) and magnetic resonance (MR) demonstrated a typical adenomatous lesion on the left adrenal gland with precocious uptake of the radiotracer on radioidine (131I)-norcholesterol adrenal scintigraphy, while the controlateral gland showed hyperdensity on CT, hyperintensity on MR and no uptake at adrenal scintigraphy. In addition, CT and MR revealed a vertebral and two hepatic hemangiomas. The right adrenal gland was surgically removed and, microscopically, pheochromocytoma and ganglioneuroma areas appeared intermixed without a predominant component. The former showed strong immunoreactivity for chromogranin, synaptophysin, vascular endothelial growth factor (VEGF) and CD34, while the latter appeared positive for neuron-specific enolase (NSE) and S-100. Peripheral blood genomic DNA analysis revealed a new intronic variant (5557A > G) in the von Hippel-Lindau gene (VHL) not observed in our control population.

A short γ-ray burst apparently associated with an elliptical galaxy at redshift z = 0.225

Gamma-ray bursts (GRBs) come in two classes: long (> 2 s), soft-spectrum bursts and short, hard events. Most progress has been made on understanding the long GRBs, which are typically observed at high redshift (z approximately 1) and found in subluminous star-forming host galaxies. They are likely to be produced in core-collapse explosions of massive stars. In contrast, no short GRB had been accurately (< 10'') and rapidly (minutes) located. Here we report the detection of the X-ray afterglow from--and the localization of--the short burst GRB 050509B. Its position on the sky is near a luminous, non-star-forming elliptical galaxy at a redshift of 0.225, which is the location one would expect if the origin of this GRB is through the merger of neutron-star or black-hole binaries. The X-ray afterglow was weak and faded below the detection limit within a few hours; no optical afterglow was detected to stringent limits, explaining the past difficulty in localizing short GRBs.

Bright X-ray Flares in Gamma-Ray Burst Afterglows

Gamma-ray burst (GRB) afterglows have provided important clues to the nature of these massive explosive events, providing direct information on the nearby environment and indirect information on the central engine that powers the burst. We report the discovery of two bright x-ray flares in GRB afterglows, including a giant flare comparable in total energy to the burst itself, each peaking minutes after the burst. These strong, rapid x-ray flares imply that the central engines of the bursts have long periods of activity, with strong internal shocks continuing for hundreds of seconds after the gamma-ray emission has ended.

An unexpectedly rapid decline in the X-ray afterglow emission of long γ-ray bursts

'Long' gamma-ray bursts (GRBs) are commonly accepted to originate in the explosion of particularly massive stars, which give rise to highly relativistic jets. Inhomogeneities in the expanding flow result in internal shock waves that are believed to produce the gamma-rays we see. As the jet travels further outward into the surrounding circumstellar medium, 'external' shocks create the afterglow emission seen in the X-ray, optical and radio bands. Here we report observations of the early phases of the X-ray emission of five GRBs. Their X-ray light curves are characterised by a surprisingly rapid fall-off for the first few hundred seconds, followed by a less rapid decline lasting several hours. This steep decline, together with detailed spectral properties of two particular bursts, shows that violent shock interactions take place in the early jet outflows.

18F-FDG PET early after radiotherapy in lymphoma patients

OBJECTIVE

The aim of this study was to evaluate the rate of postactinic inflammatory alterations that could lead to false-positive results in FDG-PET images, in a group of lymphoma patients studied with positron emission tomography (PET) early after the end of radiation therapy.

MATERIALS AND METHODS

Sixteen (16) consecutive patients were referred to our center for malignant lymphoma; 14 of 16 patients had a mediastinal bulky mass at diagnosis. Each patient underwent chemotherapy and then radiotherapy (RT): for clinical reasons, shortly after RT (range, 25-56 days; mean, 38.7 days) a FDG PET scan was required to evaluate the effect of therapy. We intravenously injected 370 MBq of 18F-FDG, and after 60-90 minutes we recorded images.

RESULTS

Despite a relatively short time after RT, there was no pathological tracer uptake in 13 of 16 patients. In 3 cases, a mild increase in FDG uptake was observed, but no findings which would lead to a false-positive diagnosis. In 2 of 3 cases, postactinic pneumopathy was diagnosed (PET scan performed 51 and 52 days after RT); while in 1 patient, soft-tissue inflammation was present (PET scan performed 42 days after RT).

CONCLUSION

Our data indicates that the rate of postactinic PET inflammatory alterations in lymphoma patients is not very high and appear to be not strictly linked to the elapsed time since the end of RT treatment.

Long-term morphological and hormonal follow-up in a single unit on 115 patients with adrenal incidentalomas

We investigated the natural course of adrenal incidentalomas in 115 patients by means of a long-term endocrine and morphological (CT) follow-up protocol (median 4 year, range 1–7 year). At entry, we observed 61 subclinical hormonal alterations in 43 patients (mainly concerning the ACTH–cortisol axis), but confirmatory tests always excluded specific endocrine diseases. In all cases radiologic signs of benignity were present. Mean values of the hormones examined at last follow-up did not differ from those recorded at entry. However in individual patients several variations were observed. In particular, 57 endocrine alterations found in 43 patients (37.2%) were no longer confirmed at follow-up, while 35 new alterations in 31 patients (26.9%) appeared de novo. Only four alterations in three patients (2.6%) persisted. Confirmatory tests were always negative for specific endocrine diseases. No variation in mean mass size was found between values at entry (25.4±0.9 mm) and at follow-up (25.7±0.9 mm), although in 32 patients (27.8%) mass size actually increased, while in 24 patients (20.8%) it decreased. In no case were the variations in mass dimension associated with the appearance of radiological criteria of malignancy. Kaplan–Meier curves indicated that the cumulative risk for mass enlargement (65%) and for developing endocrine abnormalities (57%) over time was progressive up to 80 months and independent of haemodynamic and humoral basal characteristics. In conclusion, mass enlargement and the presence or occurrence over time of subclinical endocrine alterations are frequent and not correlated, can appear at any time, are not associated with any basal predictor and, finally, are not necessarily indicative of malignant transformation or of progression toward overt disease.

Evolution of clinical behaviour in Crohn's disease: predictive factors of penetrating complications

BACKGROUND AND AIMS

Crohn's disease is a heterogeneous entity. The Vienna Classification defines three different clinical patterns: 'non-stricturing, non-penetrating', 'stricturing' and 'penetrating'. Aim of this study was to assess the change in clinical behaviour over time and to evaluate whether an evolution towards penetrating complications can be predicted.

METHODS

A total of 139 patients with non-penetrating behaviour at the time of diagnosis were included. The mean follow-up was 4.84 years (range 1-23.2 years). The clinical behaviour, according to the Vienna Criteria, was assessed at the diagnosis and at the end of follow up. Statistical analysis was performed by means of the Kaplan-Meier method and standard logistic regression analysis.

RESULTS

The cumulative probability of a change in clinical behaviour was 22, 38 and 63% at 3, 6 and 12 years, respectively, and the cumulative probability of developing penetrating complications was 22, 33 and 55% at 3, 6 and 12 years, respectively. Young age at diagnosis (<40 years) and a stricturing behaviour are independent risk factors of developing major penetrating complications (internal fistula, mass or abscess): OR=6.0, 95% CI 1.1-30.5; OR=4.0, 95% CI 1.5-10.9, respectively, but not perianal disease.

CONCLUSIONS

The behavioural classification of Crohn's disease is a dynamic model in which each status should be considered as not fixed but evolutive. Perianal disease should be considered a distinct pattern of penetrating behaviour.